diff --git a/Cargo.lock b/Cargo.lock
index 3f7427f594072..99bcfd7c7ccc1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3624,6 +3624,7 @@ dependencies = [
  "rustc_data_structures",
  "rustc_hir",
  "rustc_metadata",
+ "rustc_session",
  "rustc_span",
  "rustc_target",
 ]
@@ -3677,6 +3678,7 @@ dependencies = [
  "rustc_parse",
  "rustc_plugin_impl",
  "rustc_save_analysis",
+ "rustc_session",
  "rustc_span",
  "rustc_target",
  "serialize",
@@ -3791,6 +3793,7 @@ dependencies = [
  "rustc_hir",
  "rustc_index",
  "rustc_macros",
+ "rustc_session",
  "rustc_span",
  "rustc_target",
  "smallvec 1.0.0",
@@ -3903,6 +3906,7 @@ dependencies = [
  "rustc_expand",
  "rustc_hir",
  "rustc_index",
+ "rustc_session",
  "rustc_span",
  "rustc_target",
  "serialize",
@@ -3933,6 +3937,7 @@ dependencies = [
  "rustc_infer",
  "rustc_lexer",
  "rustc_macros",
+ "rustc_session",
  "rustc_span",
  "rustc_target",
  "rustc_trait_selection",
@@ -4013,6 +4018,7 @@ dependencies = [
  "rustc_hir",
  "rustc_lint",
  "rustc_metadata",
+ "rustc_session",
  "rustc_span",
 ]
 
@@ -4027,6 +4033,7 @@ dependencies = [
  "rustc_data_structures",
  "rustc_errors",
  "rustc_hir",
+ "rustc_session",
  "rustc_span",
  "rustc_typeck",
 ]
@@ -4068,6 +4075,7 @@ dependencies = [
  "rustc_data_structures",
  "rustc_hir",
  "rustc_parse",
+ "rustc_session",
  "rustc_span",
  "serde_json",
 ]
@@ -4174,6 +4182,7 @@ dependencies = [
  "rustc_data_structures",
  "rustc_hir",
  "rustc_infer",
+ "rustc_session",
  "rustc_span",
  "rustc_target",
  "rustc_trait_selection",
@@ -4193,6 +4202,7 @@ dependencies = [
  "rustc_hir",
  "rustc_index",
  "rustc_infer",
+ "rustc_session",
  "rustc_span",
  "rustc_target",
  "rustc_trait_selection",
diff --git a/src/bootstrap/format.rs b/src/bootstrap/format.rs
index a4acb14ee4b14..1616ae15d31d6 100644
--- a/src/bootstrap/format.rs
+++ b/src/bootstrap/format.rs
@@ -37,6 +37,9 @@ struct RustfmtConfig {
 }
 
 pub fn format(build: &Build, check: bool) {
+    if build.config.dry_run {
+        return;
+    }
     let mut builder = ignore::types::TypesBuilder::new();
     builder.add_defaults();
     builder.select("rust");
diff --git a/src/librustc/hir/map/mod.rs b/src/librustc/hir/map/mod.rs
index 55ed07a97d168..ba1665fb53083 100644
--- a/src/librustc/hir/map/mod.rs
+++ b/src/librustc/hir/map/mod.rs
@@ -346,7 +346,7 @@ impl<'hir> Map<'hir> {
     }
 
     fn get_entry(&self, id: HirId) -> Entry<'hir> {
-        if id.local_id == ItemLocalId::from_u32_const(0) {
+        if id.local_id == ItemLocalId::from_u32(0) {
             let owner = self.tcx.hir_owner(id.owner_def_id());
             Entry { parent: owner.parent, node: owner.node }
         } else {
diff --git a/src/librustc/ich/hcx.rs b/src/librustc/ich/hcx.rs
index c15d54745a105..8fd86b3232d00 100644
--- a/src/librustc/ich/hcx.rs
+++ b/src/librustc/ich/hcx.rs
@@ -1,8 +1,6 @@
-use crate::hir::map::definitions::Definitions;
-use crate::hir::map::DefPathHash;
+use crate::hir::map::definitions::{DefPathHash, Definitions};
 use crate::ich::{self, CachingSourceMapView};
 use crate::middle::cstore::CrateStore;
-use crate::session::Session;
 use crate::ty::{fast_reject, TyCtxt};
 
 use rustc_ast::ast;
@@ -11,6 +9,7 @@ use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lrc;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, DefIndex};
+use rustc_session::Session;
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::Symbol;
 use rustc_span::{BytePos, SourceFile};
diff --git a/src/librustc/lib.rs b/src/librustc/lib.rs
index 24237235e0c4a..8d0f604de6d76 100644
--- a/src/librustc/lib.rs
+++ b/src/librustc/lib.rs
@@ -26,6 +26,9 @@
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
+#![feature(const_if_match)]
+#![feature(const_fn)]
+#![feature(const_panic)]
 #![feature(const_transmute)]
 #![feature(core_intrinsics)]
 #![feature(drain_filter)]
@@ -80,7 +83,6 @@ pub mod infer;
 pub mod lint;
 pub mod middle;
 pub mod mir;
-pub use rustc_session as session;
 pub mod traits;
 pub mod ty;
 
diff --git a/src/librustc/lint.rs b/src/librustc/lint.rs
index dcc8dcbf21961..d4d01a716db97 100644
--- a/src/librustc/lint.rs
+++ b/src/librustc/lint.rs
@@ -5,7 +5,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_errors::{pluralize, Applicability, DiagnosticBuilder, DiagnosticId};
 use rustc_hir::HirId;
-pub use rustc_session::lint::{builtin, Level, Lint, LintId, LintPass};
+use rustc_session::lint::{builtin, Level, Lint, LintId};
 use rustc_session::{DiagnosticMessageId, Session};
 use rustc_span::hygiene::MacroKind;
 use rustc_span::source_map::{DesugaringKind, ExpnKind, MultiSpan};
diff --git a/src/librustc/middle/cstore.rs b/src/librustc/middle/cstore.rs
index 42d56c654627a..9f5a56903aa6e 100644
--- a/src/librustc/middle/cstore.rs
+++ b/src/librustc/middle/cstore.rs
@@ -2,10 +2,9 @@
 //! are *mostly* used as a part of that interface, but these should
 //! probably get a better home if someone can find one.
 
-use crate::hir::map as hir_map;
-use crate::hir::map::definitions::{DefKey, DefPathTable};
-use crate::session::search_paths::PathKind;
-use crate::session::CrateDisambiguator;
+pub use self::NativeLibraryKind::*;
+
+use crate::hir::map::definitions::{DefKey, DefPath, DefPathHash, DefPathTable};
 use crate::ty::TyCtxt;
 
 use rustc_ast::ast;
@@ -14,15 +13,16 @@ use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::{self, MetadataRef};
 use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
 use rustc_macros::HashStable;
+use rustc_session::search_paths::PathKind;
+pub use rustc_session::utils::NativeLibraryKind;
+use rustc_session::CrateDisambiguator;
 use rustc_span::symbol::Symbol;
 use rustc_span::Span;
 use rustc_target::spec::Target;
+
 use std::any::Any;
 use std::path::{Path, PathBuf};
 
-pub use self::NativeLibraryKind::*;
-pub use rustc_session::utils::NativeLibraryKind;
-
 // lonely orphan structs and enums looking for a better home
 
 /// Where a crate came from on the local filesystem. One of these three options
@@ -197,8 +197,8 @@ pub trait CrateStore {
 
     // resolve
     fn def_key(&self, def: DefId) -> DefKey;
-    fn def_path(&self, def: DefId) -> hir_map::DefPath;
-    fn def_path_hash(&self, def: DefId) -> hir_map::DefPathHash;
+    fn def_path(&self, def: DefId) -> DefPath;
+    fn def_path_hash(&self, def: DefId) -> DefPathHash;
     fn def_path_table(&self, cnum: CrateNum) -> &DefPathTable;
 
     // "queries" used in resolve that aren't tracked for incremental compilation
diff --git a/src/librustc/middle/dependency_format.rs b/src/librustc/middle/dependency_format.rs
index 6ece51fe86674..ee5f822d3134c 100644
--- a/src/librustc/middle/dependency_format.rs
+++ b/src/librustc/middle/dependency_format.rs
@@ -4,7 +4,7 @@
 //! For all the gory details, see the provider of the `dependency_formats`
 //! query.
 
-use crate::session::config;
+use rustc_session::config;
 
 /// A list of dependencies for a certain crate type.
 ///
diff --git a/src/librustc/middle/limits.rs b/src/librustc/middle/limits.rs
index 22e4f5ea22261..6de53c703e165 100644
--- a/src/librustc/middle/limits.rs
+++ b/src/librustc/middle/limits.rs
@@ -5,13 +5,13 @@
 //! this via an attribute on the crate like `#![recursion_limit="22"]`. This pass
 //! just peeks and looks for that attribute.
 
-use crate::session::Session;
-use core::num::IntErrorKind;
 use rustc::bug;
 use rustc_ast::ast;
+use rustc_data_structures::sync::Once;
+use rustc_session::Session;
 use rustc_span::symbol::{sym, Symbol};
 
-use rustc_data_structures::sync::Once;
+use std::num::IntErrorKind;
 
 pub fn update_limits(sess: &Session, krate: &ast::Crate) {
     update_limit(sess, krate, &sess.recursion_limit, sym::recursion_limit, 128);
diff --git a/src/librustc/middle/stability.rs b/src/librustc/middle/stability.rs
index 048e24ce3aa89..46525bdedad35 100644
--- a/src/librustc/middle/stability.rs
+++ b/src/librustc/middle/stability.rs
@@ -3,7 +3,6 @@
 
 pub use self::StabilityLevel::*;
 
-use crate::session::{DiagnosticMessageId, Session};
 use crate::ty::{self, TyCtxt};
 use rustc_ast::ast::CRATE_NODE_ID;
 use rustc_attr::{self as attr, ConstStability, Deprecation, RustcDeprecation, Stability};
@@ -17,6 +16,7 @@ use rustc_hir::{self, HirId};
 use rustc_session::lint::builtin::{DEPRECATED, DEPRECATED_IN_FUTURE, SOFT_UNSTABLE};
 use rustc_session::lint::{BuiltinLintDiagnostics, Lint, LintBuffer};
 use rustc_session::parse::feature_err_issue;
+use rustc_session::{DiagnosticMessageId, Session};
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::{MultiSpan, Span};
 
diff --git a/src/librustc/mir/interpret/allocation.rs b/src/librustc/mir/interpret/allocation.rs
index 546ba586d30f9..9474f05b55df7 100644
--- a/src/librustc/mir/interpret/allocation.rs
+++ b/src/librustc/mir/interpret/allocation.rs
@@ -41,6 +41,7 @@ pub struct Allocation<Tag = (), Extra = ()> {
     /// The size of the allocation. Currently, must always equal `bytes.len()`.
     pub size: Size,
     /// The alignment of the allocation to detect unaligned reads.
+    /// (`Align` guarantees that this is a power of two.)
     pub align: Align,
     /// `true` if the allocation is mutable.
     /// Also used by codegen to determine if a static should be put into mutable memory,
@@ -314,7 +315,7 @@ impl<'tcx, Tag: Copy, Extra: AllocationExtra<Tag>> Allocation<Tag, Extra> {
                 &self.get_bytes(cx, ptr, size_with_null)?[..size]
             }
             // This includes the case where `offset` is out-of-bounds to begin with.
-            None => throw_unsup!(UnterminatedCString(ptr.erase_tag())),
+            None => throw_ub!(UnterminatedCString(ptr.erase_tag())),
         })
     }
 
@@ -573,7 +574,7 @@ impl<'tcx, Tag, Extra> Allocation<Tag, Extra> {
     fn check_defined(&self, ptr: Pointer<Tag>, size: Size) -> InterpResult<'tcx> {
         self.undef_mask
             .is_range_defined(ptr.offset, ptr.offset + size)
-            .or_else(|idx| throw_unsup!(ReadUndefBytes(idx)))
+            .or_else(|idx| throw_ub!(InvalidUndefBytes(Some(Pointer::new(ptr.alloc_id, idx)))))
     }
 
     pub fn mark_definedness(&mut self, ptr: Pointer<Tag>, size: Size, new_state: bool) {
diff --git a/src/librustc/mir/interpret/error.rs b/src/librustc/mir/interpret/error.rs
index 0b33408edf02d..ff107a5f1e268 100644
--- a/src/librustc/mir/interpret/error.rs
+++ b/src/librustc/mir/interpret/error.rs
@@ -1,7 +1,6 @@
-use super::{CheckInAllocMsg, Pointer, RawConst, ScalarMaybeUndef};
+use super::{AllocId, CheckInAllocMsg, Pointer, RawConst, ScalarMaybeUndef};
 
 use crate::hir::map::definitions::DefPathData;
-use crate::mir;
 use crate::mir::interpret::ConstValue;
 use crate::ty::layout::{Align, LayoutError, Size};
 use crate::ty::query::TyCtxtAt;
@@ -14,8 +13,7 @@ use rustc_errors::{struct_span_err, DiagnosticBuilder};
 use rustc_hir as hir;
 use rustc_macros::HashStable;
 use rustc_session::CtfeBacktrace;
-use rustc_span::{Pos, Span};
-use rustc_target::spec::abi::Abi;
+use rustc_span::{def_id::DefId, Pos, Span};
 use std::{any::Any, fmt};
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, HashStable, RustcEncodable, RustcDecodable)]
@@ -296,6 +294,8 @@ pub enum InvalidProgramInfo<'tcx> {
     TypeckError,
     /// An error occurred during layout computation.
     Layout(layout::LayoutError<'tcx>),
+    /// An invalid transmute happened.
+    TransmuteSizeDiff(Ty<'tcx>, Ty<'tcx>),
 }
 
 impl fmt::Debug for InvalidProgramInfo<'_> {
@@ -306,6 +306,11 @@ impl fmt::Debug for InvalidProgramInfo<'_> {
             ReferencedConstant => write!(f, "referenced constant has errors"),
             TypeckError => write!(f, "encountered constants with type errors, stopping evaluation"),
             Layout(ref err) => write!(f, "{}", err),
+            TransmuteSizeDiff(from_ty, to_ty) => write!(
+                f,
+                "tried to transmute from {:?} to {:?}, but their sizes differed",
+                from_ty, to_ty
+            ),
         }
     }
 }
@@ -321,7 +326,10 @@ pub enum UndefinedBehaviorInfo {
     /// An enum discriminant was set to a value which was outside the range of valid values.
     InvalidDiscriminant(ScalarMaybeUndef),
     /// A slice/array index projection went out-of-bounds.
-    BoundsCheckFailed { len: u64, index: u64 },
+    BoundsCheckFailed {
+        len: u64,
+        index: u64,
+    },
     /// Something was divided by 0 (x / 0).
     DivisionByZero,
     /// Something was "remainded" by 0 (x % 0).
@@ -330,6 +338,43 @@ pub enum UndefinedBehaviorInfo {
     PointerArithOverflow,
     /// Invalid metadata in a wide pointer (using `str` to avoid allocations).
     InvalidMeta(&'static str),
+    /// Reading a C string that does not end within its allocation.
+    UnterminatedCString(Pointer),
+    /// Dereferencing a dangling pointer after it got freed.
+    PointerUseAfterFree(AllocId),
+    /// Used a pointer outside the bounds it is valid for.
+    PointerOutOfBounds {
+        ptr: Pointer,
+        msg: CheckInAllocMsg,
+        allocation_size: Size,
+    },
+    /// Used a pointer with bad alignment.
+    AlignmentCheckFailed {
+        required: Align,
+        has: Align,
+    },
+    /// Using an integer as a pointer in the wrong way.
+    InvalidIntPointerUsage(u64),
+    /// Writing to read-only memory.
+    WriteToReadOnly(AllocId),
+    /// Using a pointer-not-to-a-function as function pointer.
+    InvalidFunctionPointer(Pointer),
+    // Trying to access the data behind a function pointer.
+    DerefFunctionPointer(AllocId),
+    /// The value validity check found a problem.
+    /// Should only be thrown by `validity.rs` and always point out which part of the value
+    /// is the problem.
+    ValidationFailure(String),
+    /// Using a non-boolean `u8` as bool.
+    InvalidBool(u8),
+    /// Using a non-character `u32` as character.
+    InvalidChar(u32),
+    /// Using uninitialized data where it is not allowed.
+    InvalidUndefBytes(Option<Pointer>),
+    /// Working with a local that is not currently live.
+    DeadLocal,
+    /// Trying to read from the return place of a function.
+    ReadFromReturnPlace,
 }
 
 impl fmt::Debug for UndefinedBehaviorInfo {
@@ -348,6 +393,50 @@ impl fmt::Debug for UndefinedBehaviorInfo {
             RemainderByZero => write!(f, "calculating the remainder with a divisor of zero"),
             PointerArithOverflow => write!(f, "overflowing in-bounds pointer arithmetic"),
             InvalidMeta(msg) => write!(f, "invalid metadata in wide pointer: {}", msg),
+            UnterminatedCString(p) => write!(
+                f,
+                "reading a null-terminated string starting at {:?} with no null found before end of allocation",
+                p,
+            ),
+            PointerUseAfterFree(a) => {
+                write!(f, "pointer to {:?} was dereferenced after this allocation got freed", a)
+            }
+            PointerOutOfBounds { ptr, msg, allocation_size } => write!(
+                f,
+                "{} failed: pointer must be in-bounds at offset {}, \
+                           but is outside bounds of {} which has size {}",
+                msg,
+                ptr.offset.bytes(),
+                ptr.alloc_id,
+                allocation_size.bytes()
+            ),
+            InvalidIntPointerUsage(0) => write!(f, "invalid use of NULL pointer"),
+            InvalidIntPointerUsage(i) => write!(f, "invalid use of {} as a pointer", i),
+            AlignmentCheckFailed { required, has } => write!(
+                f,
+                "accessing memory with alignment {}, but alignment {} is required",
+                has.bytes(),
+                required.bytes()
+            ),
+            WriteToReadOnly(a) => write!(f, "writing to {:?} which is read-only", a),
+            InvalidFunctionPointer(p) => {
+                write!(f, "using {:?} as function pointer but it does not point to a function", p)
+            }
+            DerefFunctionPointer(a) => write!(f, "accessing {:?} which contains a function", a),
+            ValidationFailure(ref err) => write!(f, "type validation failed: {}", err),
+            InvalidBool(b) => write!(f, "interpreting an invalid 8-bit value as a bool: {}", b),
+            InvalidChar(c) => write!(f, "interpreting an invalid 32-bit value as a char: {}", c),
+            InvalidUndefBytes(Some(p)) => write!(
+                f,
+                "reading uninitialized memory at {:?}, but this operation requires initialized memory",
+                p
+            ),
+            InvalidUndefBytes(None) => write!(
+                f,
+                "using uninitialized data, but this operation requires initialized memory"
+            ),
+            DeadLocal => write!(f, "accessing a dead local variable"),
+            ReadFromReturnPlace => write!(f, "tried to read from the return place"),
         }
     }
 }
@@ -359,203 +448,45 @@ impl fmt::Debug for UndefinedBehaviorInfo {
 ///
 /// Currently, we also use this as fall-back error kind for errors that have not been
 /// categorized yet.
-pub enum UnsupportedOpInfo<'tcx> {
+pub enum UnsupportedOpInfo {
     /// Free-form case. Only for errors that are never caught!
     Unsupported(String),
-
     /// When const-prop encounters a situation it does not support, it raises this error.
     /// This must not allocate for performance reasons (hence `str`, not `String`).
     ConstPropUnsupported(&'static str),
-
-    // -- Everything below is not categorized yet --
-    FunctionAbiMismatch(Abi, Abi),
-    FunctionArgMismatch(Ty<'tcx>, Ty<'tcx>),
-    FunctionRetMismatch(Ty<'tcx>, Ty<'tcx>),
-    FunctionArgCountMismatch,
-    UnterminatedCString(Pointer),
-    DanglingPointerDeref,
-    DoubleFree,
-    InvalidMemoryAccess,
-    InvalidFunctionPointer,
-    InvalidBool,
-    PointerOutOfBounds {
-        ptr: Pointer,
-        msg: CheckInAllocMsg,
-        allocation_size: Size,
-    },
-    InvalidNullPointerUsage,
+    /// Accessing an unsupported foreign static.
+    ReadForeignStatic(DefId),
+    /// Could not find MIR for a function.
+    NoMirFor(DefId),
+    /// Modified a static during const-eval.
+    /// FIXME: move this to `ConstEvalErrKind` through a machine hook.
+    ModifiedStatic,
+    /// Encountered a pointer where we needed raw bytes.
     ReadPointerAsBytes,
+    /// Encountered raw bytes where we needed a pointer.
     ReadBytesAsPointer,
-    ReadForeignStatic,
-    InvalidPointerMath,
-    ReadUndefBytes(Size),
-    DeadLocal,
-    InvalidBoolOp(mir::BinOp),
-    UnimplementedTraitSelection,
-    CalledClosureAsFunction,
-    NoMirFor(String),
-    DerefFunctionPointer,
-    ExecuteMemory,
-    InvalidChar(u128),
-    OutOfTls,
-    TlsOutOfBounds,
-    AlignmentCheckFailed {
-        required: Align,
-        has: Align,
-    },
-    ValidationFailure(String),
-    VtableForArgumentlessMethod,
-    ModifiedConstantMemory,
-    ModifiedStatic,
-    TypeNotPrimitive(Ty<'tcx>),
-    ReallocatedWrongMemoryKind(String, String),
-    DeallocatedWrongMemoryKind(String, String),
-    ReallocateNonBasePtr,
-    DeallocateNonBasePtr,
-    IncorrectAllocationInformation(Size, Size, Align, Align),
-    HeapAllocZeroBytes,
-    HeapAllocNonPowerOfTwoAlignment(u64),
-    ReadFromReturnPointer,
-    PathNotFound(Vec<String>),
-    TransmuteSizeDiff(Ty<'tcx>, Ty<'tcx>),
 }
 
-impl fmt::Debug for UnsupportedOpInfo<'tcx> {
+impl fmt::Debug for UnsupportedOpInfo {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         use UnsupportedOpInfo::*;
         match self {
-            PointerOutOfBounds { ptr, msg, allocation_size } => write!(
-                f,
-                "{} failed: pointer must be in-bounds at offset {}, \
-                           but is outside bounds of allocation {} which has size {}",
-                msg,
-                ptr.offset.bytes(),
-                ptr.alloc_id,
-                allocation_size.bytes()
-            ),
-            ValidationFailure(ref err) => write!(f, "type validation failed: {}", err),
-            NoMirFor(ref func) => write!(f, "no MIR for `{}`", func),
-            FunctionAbiMismatch(caller_abi, callee_abi) => write!(
-                f,
-                "tried to call a function with ABI {:?} using caller ABI {:?}",
-                callee_abi, caller_abi
-            ),
-            FunctionArgMismatch(caller_ty, callee_ty) => write!(
-                f,
-                "tried to call a function with argument of type {:?} \
-                           passing data of type {:?}",
-                callee_ty, caller_ty
-            ),
-            TransmuteSizeDiff(from_ty, to_ty) => write!(
-                f,
-                "tried to transmute from {:?} to {:?}, but their sizes differed",
-                from_ty, to_ty
-            ),
-            FunctionRetMismatch(caller_ty, callee_ty) => write!(
-                f,
-                "tried to call a function with return type {:?} \
-                           passing return place of type {:?}",
-                callee_ty, caller_ty
-            ),
-            FunctionArgCountMismatch => {
-                write!(f, "tried to call a function with incorrect number of arguments")
-            }
-            ReallocatedWrongMemoryKind(ref old, ref new) => {
-                write!(f, "tried to reallocate memory from `{}` to `{}`", old, new)
-            }
-            DeallocatedWrongMemoryKind(ref old, ref new) => {
-                write!(f, "tried to deallocate `{}` memory but gave `{}` as the kind", old, new)
-            }
-            InvalidChar(c) => {
-                write!(f, "tried to interpret an invalid 32-bit value as a char: {}", c)
-            }
-            AlignmentCheckFailed { required, has } => write!(
-                f,
-                "tried to access memory with alignment {}, but alignment {} is required",
-                has.bytes(),
-                required.bytes()
-            ),
-            TypeNotPrimitive(ty) => write!(f, "expected primitive type, got {}", ty),
-            PathNotFound(ref path) => write!(f, "cannot find path {:?}", path),
-            IncorrectAllocationInformation(size, size2, align, align2) => write!(
-                f,
-                "incorrect alloc info: expected size {} and align {}, \
-                           got size {} and align {}",
-                size.bytes(),
-                align.bytes(),
-                size2.bytes(),
-                align2.bytes()
-            ),
-            InvalidMemoryAccess => write!(f, "tried to access memory through an invalid pointer"),
-            DanglingPointerDeref => write!(f, "dangling pointer was dereferenced"),
-            DoubleFree => write!(f, "tried to deallocate dangling pointer"),
-            InvalidFunctionPointer => {
-                write!(f, "tried to use a function pointer after offsetting it")
-            }
-            InvalidBool => write!(f, "invalid boolean value read"),
-            InvalidNullPointerUsage => write!(f, "invalid use of NULL pointer"),
-            ReadPointerAsBytes => write!(
-                f,
-                "a raw memory access tried to access part of a pointer value as raw \
-                    bytes"
-            ),
-            ReadBytesAsPointer => {
-                write!(f, "a memory access tried to interpret some bytes as a pointer")
-            }
-            ReadForeignStatic => write!(f, "tried to read from foreign (extern) static"),
-            InvalidPointerMath => write!(
-                f,
-                "attempted to do invalid arithmetic on pointers that would leak base \
-                    addresses, e.g., comparing pointers into different allocations"
-            ),
-            DeadLocal => write!(f, "tried to access a dead local variable"),
-            DerefFunctionPointer => write!(f, "tried to dereference a function pointer"),
-            ExecuteMemory => write!(f, "tried to treat a memory pointer as a function pointer"),
-            OutOfTls => write!(f, "reached the maximum number of representable TLS keys"),
-            TlsOutOfBounds => write!(f, "accessed an invalid (unallocated) TLS key"),
-            CalledClosureAsFunction => {
-                write!(f, "tried to call a closure through a function pointer")
+            Unsupported(ref msg) => write!(f, "{}", msg),
+            ConstPropUnsupported(ref msg) => {
+                write!(f, "Constant propagation encountered an unsupported situation: {}", msg)
             }
-            VtableForArgumentlessMethod => {
-                write!(f, "tried to call a vtable function without arguments")
+            ReadForeignStatic(did) => {
+                write!(f, "tried to read from foreign (extern) static {:?}", did)
             }
-            ModifiedConstantMemory => write!(f, "tried to modify constant memory"),
+            NoMirFor(did) => write!(f, "could not load MIR for {:?}", did),
             ModifiedStatic => write!(
                 f,
                 "tried to modify a static's initial value from another static's \
                     initializer"
             ),
-            ReallocateNonBasePtr => write!(
-                f,
-                "tried to reallocate with a pointer not to the beginning of an \
-                    existing object"
-            ),
-            DeallocateNonBasePtr => write!(
-                f,
-                "tried to deallocate with a pointer not to the beginning of an \
-                    existing object"
-            ),
-            HeapAllocZeroBytes => write!(f, "tried to re-, de- or allocate zero bytes on the heap"),
-            ReadFromReturnPointer => write!(f, "tried to read from the return pointer"),
-            UnimplementedTraitSelection => {
-                write!(f, "there were unresolved type arguments during trait selection")
-            }
-            InvalidBoolOp(_) => write!(f, "invalid boolean operation"),
-            UnterminatedCString(_) => write!(
-                f,
-                "attempted to get length of a null-terminated string, but no null \
-                    found before end of allocation"
-            ),
-            ReadUndefBytes(_) => write!(f, "attempted to read undefined bytes"),
-            HeapAllocNonPowerOfTwoAlignment(_) => write!(
-                f,
-                "tried to re-, de-, or allocate heap memory with alignment that is \
-                    not a power of two"
-            ),
-            Unsupported(ref msg) => write!(f, "{}", msg),
-            ConstPropUnsupported(ref msg) => {
-                write!(f, "Constant propagation encountered an unsupported situation: {}", msg)
-            }
+
+            ReadPointerAsBytes => write!(f, "unable to turn pointer into raw bytes",),
+            ReadBytesAsPointer => write!(f, "unable to turn bytes into a pointer"),
         }
     }
 }
@@ -590,7 +521,7 @@ pub enum InterpError<'tcx> {
     UndefinedBehavior(UndefinedBehaviorInfo),
     /// The program did something the interpreter does not support (some of these *might* be UB
     /// but the interpreter is not sure).
-    Unsupported(UnsupportedOpInfo<'tcx>),
+    Unsupported(UnsupportedOpInfo),
     /// The program was invalid (ill-typed, bad MIR, not sufficiently monomorphized, ...).
     InvalidProgram(InvalidProgramInfo<'tcx>),
     /// The program exhausted the interpreter's resources (stack/heap too big,
@@ -606,7 +537,7 @@ pub type InterpResult<'tcx, T = ()> = Result<T, InterpErrorInfo<'tcx>>;
 impl fmt::Display for InterpError<'_> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         // Forward `Display` to `Debug`.
-        write!(f, "{:?}", self)
+        fmt::Debug::fmt(self, f)
     }
 }
 
@@ -631,7 +562,7 @@ impl InterpError<'_> {
         match self {
             InterpError::MachineStop(_)
             | InterpError::Unsupported(UnsupportedOpInfo::Unsupported(_))
-            | InterpError::Unsupported(UnsupportedOpInfo::ValidationFailure(_))
+            | InterpError::UndefinedBehavior(UndefinedBehaviorInfo::ValidationFailure(_))
             | InterpError::UndefinedBehavior(UndefinedBehaviorInfo::Ub(_))
             | InterpError::UndefinedBehavior(UndefinedBehaviorInfo::UbExperimental(_)) => true,
             _ => false,
diff --git a/src/librustc/mir/interpret/mod.rs b/src/librustc/mir/interpret/mod.rs
index 64c07b431db38..0b5bb7f3c03fa 100644
--- a/src/librustc/mir/interpret/mod.rs
+++ b/src/librustc/mir/interpret/mod.rs
@@ -161,7 +161,13 @@ pub struct AllocId(pub u64);
 
 impl fmt::Debug for AllocId {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(fmt, "alloc{}", self.0)
+        fmt::Display::fmt(self, fmt)
+    }
+}
+
+impl fmt::Display for AllocId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "alloc{}", self.0)
     }
 }
 
@@ -351,12 +357,6 @@ impl<'s> AllocDecodingSession<'s> {
     }
 }
 
-impl fmt::Display for AllocId {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}", self.0)
-    }
-}
-
 /// An allocation in the global (tcx-managed) memory can be either a function pointer,
 /// a static, or a "real" allocation with some data in it.
 #[derive(Debug, Clone, Eq, PartialEq, Hash, RustcDecodable, RustcEncodable, HashStable)]
diff --git a/src/librustc/mir/interpret/pointer.rs b/src/librustc/mir/interpret/pointer.rs
index cc3c50b7899f3..2cbe25f967426 100644
--- a/src/librustc/mir/interpret/pointer.rs
+++ b/src/librustc/mir/interpret/pointer.rs
@@ -213,20 +213,4 @@ impl<'tcx, Tag> Pointer<Tag> {
     pub fn erase_tag(self) -> Pointer {
         Pointer { alloc_id: self.alloc_id, offset: self.offset, tag: () }
     }
-
-    /// Test if the pointer is "inbounds" of an allocation of the given size.
-    /// A pointer is "inbounds" even if its offset is equal to the size; this is
-    /// a "one-past-the-end" pointer.
-    #[inline(always)]
-    pub fn check_inbounds_alloc(
-        self,
-        allocation_size: Size,
-        msg: CheckInAllocMsg,
-    ) -> InterpResult<'tcx, ()> {
-        if self.offset > allocation_size {
-            throw_unsup!(PointerOutOfBounds { ptr: self.erase_tag(), msg, allocation_size })
-        } else {
-            Ok(())
-        }
-    }
 }
diff --git a/src/librustc/mir/interpret/value.rs b/src/librustc/mir/interpret/value.rs
index 1e630c96dd409..04fe70b36c1e0 100644
--- a/src/librustc/mir/interpret/value.rs
+++ b/src/librustc/mir/interpret/value.rs
@@ -455,10 +455,11 @@ impl<'tcx, Tag> Scalar<Tag> {
     }
 
     pub fn to_bool(self) -> InterpResult<'tcx, bool> {
-        match self {
-            Scalar::Raw { data: 0, size: 1 } => Ok(false),
-            Scalar::Raw { data: 1, size: 1 } => Ok(true),
-            _ => throw_unsup!(InvalidBool),
+        let val = self.to_u8()?;
+        match val {
+            0 => Ok(false),
+            1 => Ok(true),
+            _ => throw_ub!(InvalidBool(val)),
         }
     }
 
@@ -466,7 +467,7 @@ impl<'tcx, Tag> Scalar<Tag> {
         let val = self.to_u32()?;
         match ::std::char::from_u32(val) {
             Some(c) => Ok(c),
-            None => throw_unsup!(InvalidChar(val as u128)),
+            None => throw_ub!(InvalidChar(val)),
         }
     }
 
@@ -609,7 +610,7 @@ impl<'tcx, Tag> ScalarMaybeUndef<Tag> {
     pub fn not_undef(self) -> InterpResult<'static, Scalar<Tag>> {
         match self {
             ScalarMaybeUndef::Scalar(scalar) => Ok(scalar),
-            ScalarMaybeUndef::Undef => throw_unsup!(ReadUndefBytes(Size::ZERO)),
+            ScalarMaybeUndef::Undef => throw_ub!(InvalidUndefBytes(None)),
         }
     }
 
diff --git a/src/librustc/mir/mono.rs b/src/librustc/mir/mono.rs
index 4f8efc1607eaa..27d82d25803c7 100644
--- a/src/librustc/mir/mono.rs
+++ b/src/librustc/mir/mono.rs
@@ -1,6 +1,5 @@
 use crate::dep_graph::{DepConstructor, DepNode, WorkProduct, WorkProductId};
 use crate::ich::{Fingerprint, NodeIdHashingMode, StableHashingContext};
-use crate::session::config::OptLevel;
 use crate::ty::print::obsolete::DefPathBasedNames;
 use crate::ty::{subst::InternalSubsts, Instance, InstanceDef, SymbolName, TyCtxt};
 use rustc_attr::InlineAttr;
@@ -9,6 +8,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
 use rustc_hir::HirId;
+use rustc_session::config::OptLevel;
 use rustc_span::source_map::Span;
 use rustc_span::symbol::Symbol;
 use std::fmt;
diff --git a/src/librustc/ty/context.rs b/src/librustc/ty/context.rs
index d6f6788697cd8..d7a259cc87074 100644
--- a/src/librustc/ty/context.rs
+++ b/src/librustc/ty/context.rs
@@ -23,7 +23,6 @@ use crate::mir::{
 };
 use crate::traits;
 use crate::traits::{Clause, Clauses, Goal, GoalKind, Goals};
-use crate::ty::free_region_map::FreeRegionMap;
 use crate::ty::layout::{LayoutDetails, TargetDataLayout, VariantIdx};
 use crate::ty::query;
 use crate::ty::steal::Steal;
@@ -416,11 +415,6 @@ pub struct TypeckTables<'tcx> {
     /// this field will be set to `true`.
     pub tainted_by_errors: bool,
 
-    /// Stores the free-region relationships that were deduced from
-    /// its where-clauses and parameter types. These are then
-    /// read-again by borrowck.
-    pub free_region_map: FreeRegionMap<'tcx>,
-
     /// All the opaque types that are restricted to concrete types
     /// by this function.
     pub concrete_opaque_types: FxHashMap<DefId, ResolvedOpaqueTy<'tcx>>,
@@ -456,7 +450,6 @@ impl<'tcx> TypeckTables<'tcx> {
             coercion_casts: Default::default(),
             used_trait_imports: Lrc::new(Default::default()),
             tainted_by_errors: false,
-            free_region_map: Default::default(),
             concrete_opaque_types: Default::default(),
             upvar_list: Default::default(),
             generator_interior_types: Default::default(),
@@ -719,7 +712,6 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TypeckTables<'tcx> {
 
             ref used_trait_imports,
             tainted_by_errors,
-            ref free_region_map,
             ref concrete_opaque_types,
             ref upvar_list,
             ref generator_interior_types,
@@ -757,7 +749,6 @@ impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TypeckTables<'tcx> {
             coercion_casts.hash_stable(hcx, hasher);
             used_trait_imports.hash_stable(hcx, hasher);
             tainted_by_errors.hash_stable(hcx, hasher);
-            free_region_map.hash_stable(hcx, hasher);
             concrete_opaque_types.hash_stable(hcx, hasher);
             upvar_list.hash_stable(hcx, hasher);
             generator_interior_types.hash_stable(hcx, hasher);
diff --git a/src/librustc/ty/layout.rs b/src/librustc/ty/layout.rs
index dedb3035cedb3..6a576ef3ce9a1 100644
--- a/src/librustc/ty/layout.rs
+++ b/src/librustc/ty/layout.rs
@@ -1,30 +1,28 @@
-use crate::session::{self, DataTypeKind};
+use crate::ich::StableHashingContext;
+use crate::mir::{GeneratorLayout, GeneratorSavedLocal};
+use crate::ty::subst::Subst;
 use crate::ty::{self, subst::SubstsRef, ReprOptions, Ty, TyCtxt, TypeFoldable};
 
 use rustc_ast::ast::{self, Ident, IntTy, UintTy};
 use rustc_attr as attr;
-use rustc_span::DUMMY_SP;
-
-use std::cmp;
-use std::fmt;
-use std::iter;
-use std::mem;
-use std::ops::Bound;
-
-use crate::ich::StableHashingContext;
-use crate::mir::{GeneratorLayout, GeneratorSavedLocal};
-use crate::ty::subst::Subst;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_hir as hir;
 use rustc_index::bit_set::BitSet;
 use rustc_index::vec::{Idx, IndexVec};
-
+use rustc_session::{DataTypeKind, FieldInfo, SizeKind, VariantInfo};
+use rustc_span::DUMMY_SP;
 use rustc_target::abi::call::{
     ArgAbi, ArgAttribute, ArgAttributes, Conv, FnAbi, PassMode, Reg, RegKind,
 };
 pub use rustc_target::abi::*;
 use rustc_target::spec::{abi::Abi as SpecAbi, HasTargetSpec};
 
+use std::cmp;
+use std::fmt;
+use std::iter;
+use std::mem;
+use std::ops::Bound;
+
 pub trait IntegerExt {
     fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>, signed: bool) -> Ty<'tcx>;
     fn from_attr<C: HasDataLayout>(cx: &C, ity: attr::IntType) -> Integer;
@@ -1648,7 +1646,7 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
                         if min_size < field_end {
                             min_size = field_end;
                         }
-                        session::FieldInfo {
+                        FieldInfo {
                             name: name.to_string(),
                             offset: offset.bytes(),
                             size: field_layout.size.bytes(),
@@ -1658,13 +1656,9 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
                 })
                 .collect();
 
-            session::VariantInfo {
+            VariantInfo {
                 name: n.map(|n| n.to_string()),
-                kind: if layout.is_unsized() {
-                    session::SizeKind::Min
-                } else {
-                    session::SizeKind::Exact
-                },
+                kind: if layout.is_unsized() { SizeKind::Min } else { SizeKind::Exact },
                 align: layout.align.abi.bytes(),
                 size: if min_size.bytes() == 0 { layout.size.bytes() } else { min_size.bytes() },
                 fields: field_info,
diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs
index d622d6fbe2c1f..74d677298d3f8 100644
--- a/src/librustc/ty/mod.rs
+++ b/src/librustc/ty/mod.rs
@@ -9,7 +9,6 @@ pub use self::Variance::*;
 use crate::arena::Arena;
 use crate::hir::exports::ExportMap;
 use crate::hir::map as hir_map;
-
 use crate::ich::Fingerprint;
 use crate::ich::StableHashingContext;
 use crate::infer::canonical::Canonical;
@@ -19,7 +18,6 @@ use crate::middle::resolve_lifetime::ObjectLifetimeDefault;
 use crate::mir::interpret::ErrorHandled;
 use crate::mir::GeneratorLayout;
 use crate::mir::ReadOnlyBodyAndCache;
-use crate::session::DataTypeKind;
 use crate::traits::{self, Reveal};
 use crate::ty;
 use crate::ty::layout::VariantIdx;
@@ -42,6 +40,7 @@ use rustc_hir::{Constness, GlobMap, Node, TraitMap};
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_macros::HashStable;
 use rustc_serialize::{self, Encodable, Encoder};
+use rustc_session::DataTypeKind;
 use rustc_span::hygiene::ExpnId;
 use rustc_span::symbol::{kw, sym, Symbol};
 use rustc_span::Span;
@@ -1700,7 +1699,7 @@ rustc_index::newtype_index! {
 }
 
 impl UniverseIndex {
-    pub const ROOT: UniverseIndex = UniverseIndex::from_u32_const(0);
+    pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
 
     /// Returns the "next" universe index in order -- this new index
     /// is considered to extend all previous universes. This
diff --git a/src/librustc/ty/query/mod.rs b/src/librustc/ty/query/mod.rs
index 3d17883fec3bd..e3859ed12a2eb 100644
--- a/src/librustc/ty/query/mod.rs
+++ b/src/librustc/ty/query/mod.rs
@@ -19,8 +19,6 @@ use crate::mir::interpret::GlobalId;
 use crate::mir::interpret::{ConstEvalRawResult, ConstEvalResult, ConstValue};
 use crate::mir::interpret::{LitToConstError, LitToConstInput};
 use crate::mir::mono::CodegenUnit;
-use crate::session::config::{EntryFnType, OptLevel, OutputFilenames, SymbolManglingVersion};
-use crate::session::CrateDisambiguator;
 use crate::traits::query::{
     CanonicalPredicateGoal, CanonicalProjectionGoal, CanonicalTyGoal,
     CanonicalTypeOpAscribeUserTypeGoal, CanonicalTypeOpEqGoal, CanonicalTypeOpNormalizeGoal,
@@ -49,6 +47,8 @@ use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, DefIdSet, DefIndex};
 use rustc_hir::{Crate, HirIdSet, ItemLocalId, TraitCandidate};
 use rustc_index::vec::IndexVec;
+use rustc_session::config::{EntryFnType, OptLevel, OutputFilenames, SymbolManglingVersion};
+use rustc_session::CrateDisambiguator;
 use rustc_target::spec::PanicStrategy;
 
 use rustc_ast::ast;
diff --git a/src/librustc/ty/query/on_disk_cache.rs b/src/librustc/ty/query/on_disk_cache.rs
index 9c1db7c5f2b70..62c2bd801ee33 100644
--- a/src/librustc/ty/query/on_disk_cache.rs
+++ b/src/librustc/ty/query/on_disk_cache.rs
@@ -3,7 +3,6 @@ use crate::hir::map::definitions::DefPathHash;
 use crate::ich::{CachingSourceMapView, Fingerprint};
 use crate::mir::interpret::{AllocDecodingSession, AllocDecodingState};
 use crate::mir::{self, interpret};
-use crate::session::{CrateDisambiguator, Session};
 use crate::ty::codec::{self as ty_codec, TyDecoder, TyEncoder};
 use crate::ty::context::TyCtxt;
 use crate::ty::{self, Ty};
@@ -19,6 +18,7 @@ use rustc_serialize::{
     opaque, Decodable, Decoder, Encodable, Encoder, SpecializedDecoder, SpecializedEncoder,
     UseSpecializedDecodable, UseSpecializedEncodable,
 };
+use rustc_session::{CrateDisambiguator, Session};
 use rustc_span::hygiene::{ExpnId, SyntaxContext};
 use rustc_span::source_map::{SourceMap, StableSourceFileId};
 use rustc_span::{BytePos, SourceFile, Span, DUMMY_SP};
diff --git a/src/librustc_ast/lib.rs b/src/librustc_ast/lib.rs
index adb96356aae7d..2594cc536ac5f 100644
--- a/src/librustc_ast/lib.rs
+++ b/src/librustc_ast/lib.rs
@@ -7,7 +7,9 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/", test(attr(deny(warnings))))]
 #![feature(bool_to_option)]
 #![feature(box_syntax)]
+#![feature(const_if_match)]
 #![feature(const_fn)] // For the `transmute` in `P::new`
+#![feature(const_panic)]
 #![feature(const_transmute)]
 #![feature(crate_visibility_modifier)]
 #![feature(label_break_value)]
diff --git a/src/librustc_ast/node_id.rs b/src/librustc_ast/node_id.rs
index 58d2334a7b148..cd562c48e9115 100644
--- a/src/librustc_ast/node_id.rs
+++ b/src/librustc_ast/node_id.rs
@@ -12,7 +12,7 @@ rustc_index::newtype_index! {
 rustc_data_structures::define_id_collections!(NodeMap, NodeSet, NodeId);
 
 /// `NodeId` used to represent the root of the crate.
-pub const CRATE_NODE_ID: NodeId = NodeId::from_u32_const(0);
+pub const CRATE_NODE_ID: NodeId = NodeId::from_u32(0);
 
 /// When parsing and doing expansions, we initially give all AST nodes this AST
 /// node value. Then later, in the renumber pass, we renumber them to have
diff --git a/src/librustc_ast_lowering/lib.rs b/src/librustc_ast_lowering/lib.rs
index 32b0f0db3589d..43a6b7ac04cd9 100644
--- a/src/librustc_ast_lowering/lib.rs
+++ b/src/librustc_ast_lowering/lib.rs
@@ -37,7 +37,6 @@
 use rustc::arena::Arena;
 use rustc::dep_graph::DepGraph;
 use rustc::hir::map::definitions::{DefKey, DefPathData, Definitions};
-use rustc::hir::map::Map;
 use rustc::{bug, span_bug};
 use rustc_ast::ast;
 use rustc_ast::ast::*;
@@ -1463,7 +1462,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         }
 
         impl<'r, 'a, 'v, 'hir> intravisit::Visitor<'v> for ImplTraitLifetimeCollector<'r, 'a, 'hir> {
-            type Map = Map<'v>;
+            type Map = intravisit::ErasedMap<'v>;
 
             fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
                 intravisit::NestedVisitorMap::None
diff --git a/src/librustc_ast_lowering/path.rs b/src/librustc_ast_lowering/path.rs
index db8517bfbf0c7..b5b0a3089ce0f 100644
--- a/src/librustc_ast_lowering/path.rs
+++ b/src/librustc_ast_lowering/path.rs
@@ -1,7 +1,6 @@
 use super::{AnonymousLifetimeMode, ImplTraitContext, LoweringContext, ParamMode};
 use super::{GenericArgsCtor, ParenthesizedGenericArgs};
 
-use rustc::lint::builtin::ELIDED_LIFETIMES_IN_PATHS;
 use rustc::span_bug;
 use rustc_ast::ast::{self, *};
 use rustc_errors::{struct_span_err, Applicability};
@@ -9,6 +8,7 @@ use rustc_hir as hir;
 use rustc_hir::def::{DefKind, PartialRes, Res};
 use rustc_hir::def_id::DefId;
 use rustc_hir::GenericArg;
+use rustc_session::lint::builtin::ELIDED_LIFETIMES_IN_PATHS;
 use rustc_session::lint::BuiltinLintDiagnostics;
 use rustc_span::Span;
 
diff --git a/src/librustc_builtin_macros/cmdline_attrs.rs b/src/librustc_builtin_macros/cmdline_attrs.rs
index 7ddbf08306b72..093815dbbcd4f 100644
--- a/src/librustc_builtin_macros/cmdline_attrs.rs
+++ b/src/librustc_builtin_macros/cmdline_attrs.rs
@@ -3,7 +3,6 @@
 use rustc_ast::ast::{self, AttrItem, AttrStyle};
 use rustc_ast::attr::mk_attr;
 use rustc_ast::token;
-use rustc_expand::panictry;
 use rustc_session::parse::ParseSess;
 use rustc_span::FileName;
 
@@ -16,7 +15,13 @@ pub fn inject(mut krate: ast::Crate, parse_sess: &ParseSess, attrs: &[String]) -
         );
 
         let start_span = parser.token.span;
-        let AttrItem { path, args } = panictry!(parser.parse_attr_item());
+        let AttrItem { path, args } = match parser.parse_attr_item() {
+            Ok(ai) => ai,
+            Err(mut err) => {
+                err.emit();
+                continue;
+            }
+        };
         let end_span = parser.token.span;
         if parser.token != token::Eof {
             parse_sess.span_diagnostic.span_err(start_span.to(end_span), "invalid crate attribute");
diff --git a/src/librustc_builtin_macros/source_util.rs b/src/librustc_builtin_macros/source_util.rs
index 5ad72a7443dd2..1aae93e19f369 100644
--- a/src/librustc_builtin_macros/source_util.rs
+++ b/src/librustc_builtin_macros/source_util.rs
@@ -4,7 +4,6 @@ use rustc_ast::token;
 use rustc_ast::tokenstream::TokenStream;
 use rustc_ast_pretty::pprust;
 use rustc_expand::base::{self, *};
-use rustc_expand::panictry;
 use rustc_parse::{self, new_sub_parser_from_file, parser::Parser, DirectoryOwnership};
 use rustc_session::lint::builtin::INCOMPLETE_INCLUDE;
 use rustc_span::symbol::Symbol;
@@ -116,7 +115,7 @@ pub fn expand_include<'cx>(
     }
     impl<'a> base::MacResult for ExpandResult<'a> {
         fn make_expr(mut self: Box<ExpandResult<'a>>) -> Option<P<ast::Expr>> {
-            let r = panictry!(self.p.parse_expr());
+            let r = base::parse_expr(&mut self.p)?;
             if self.p.token != token::Eof {
                 self.p.sess.buffer_lint(
                     &INCOMPLETE_INCLUDE,
@@ -131,18 +130,17 @@ pub fn expand_include<'cx>(
         fn make_items(mut self: Box<ExpandResult<'a>>) -> Option<SmallVec<[P<ast::Item>; 1]>> {
             let mut ret = SmallVec::new();
             while self.p.token != token::Eof {
-                match panictry!(self.p.parse_item()) {
-                    Some(item) => ret.push(item),
-                    None => {
+                match self.p.parse_item() {
+                    Err(mut err) => {
+                        err.emit();
+                        break;
+                    }
+                    Ok(Some(item)) => ret.push(item),
+                    Ok(None) => {
                         let token = pprust::token_to_string(&self.p.token);
-                        self.p
-                            .sess
-                            .span_diagnostic
-                            .span_fatal(
-                                self.p.token.span,
-                                &format!("expected item, found `{}`", token),
-                            )
-                            .raise();
+                        let msg = format!("expected item, found `{}`", token);
+                        self.p.struct_span_err(self.p.token.span, &msg).emit();
+                        break;
                     }
                 }
             }
diff --git a/src/librustc_builtin_macros/test.rs b/src/librustc_builtin_macros/test.rs
index 39009ca27f102..bdc4ae2fe274b 100644
--- a/src/librustc_builtin_macros/test.rs
+++ b/src/librustc_builtin_macros/test.rs
@@ -74,16 +74,16 @@ pub fn expand_test_or_bench(
         return vec![];
     }
 
-    let item = if let Annotatable::Item(i) = item {
-        i
-    } else {
-        cx.parse_sess
-            .span_diagnostic
-            .span_fatal(
-                item.span(),
+    let item = match item {
+        Annotatable::Item(i) => i,
+        other => {
+            cx.struct_span_err(
+                other.span(),
                 "`#[test]` attribute is only allowed on non associated functions",
             )
-            .raise();
+            .emit();
+            return vec![other];
+        }
     };
 
     if let ast::ItemKind::MacCall(_) = item.kind {
diff --git a/src/librustc_builtin_macros/test_harness.rs b/src/librustc_builtin_macros/test_harness.rs
index 15997a27fadf2..778bfc1a1f7df 100644
--- a/src/librustc_builtin_macros/test_harness.rs
+++ b/src/librustc_builtin_macros/test_harness.rs
@@ -345,14 +345,14 @@ fn is_test_case(i: &ast::Item) -> bool {
 
 fn get_test_runner(sd: &rustc_errors::Handler, krate: &ast::Crate) -> Option<ast::Path> {
     let test_attr = attr::find_by_name(&krate.attrs, sym::test_runner)?;
-    test_attr.meta_item_list().map(|meta_list| {
-        if meta_list.len() != 1 {
-            sd.span_fatal(test_attr.span, "`#![test_runner(..)]` accepts exactly 1 argument")
-                .raise()
-        }
-        match meta_list[0].meta_item() {
-            Some(meta_item) if meta_item.is_word() => meta_item.path.clone(),
-            _ => sd.span_fatal(test_attr.span, "`test_runner` argument must be a path").raise(),
-        }
-    })
+    let meta_list = test_attr.meta_item_list()?;
+    let span = test_attr.span;
+    match &*meta_list {
+        [single] => match single.meta_item() {
+            Some(meta_item) if meta_item.is_word() => return Some(meta_item.path.clone()),
+            _ => sd.struct_span_err(span, "`test_runner` argument must be a path").emit(),
+        },
+        _ => sd.struct_span_err(span, "`#![test_runner(..)]` accepts exactly 1 argument").emit(),
+    }
+    None
 }
diff --git a/src/librustc_codegen_llvm/attributes.rs b/src/librustc_codegen_llvm/attributes.rs
index a9e4fdba03036..072607fff85c7 100644
--- a/src/librustc_codegen_llvm/attributes.rs
+++ b/src/librustc_codegen_llvm/attributes.rs
@@ -3,8 +3,6 @@
 use std::ffi::CString;
 
 use rustc::middle::codegen_fn_attrs::CodegenFnAttrFlags;
-use rustc::session::config::{OptLevel, Sanitizer};
-use rustc::session::Session;
 use rustc::ty::layout::HasTyCtxt;
 use rustc::ty::query::Providers;
 use rustc::ty::{self, Ty, TyCtxt};
@@ -13,6 +11,8 @@ use rustc_data_structures::const_cstr;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::small_c_str::SmallCStr;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
+use rustc_session::config::{OptLevel, Sanitizer};
+use rustc_session::Session;
 use rustc_target::abi::call::Conv;
 use rustc_target::spec::PanicStrategy;
 
diff --git a/src/librustc_codegen_llvm/back/archive.rs b/src/librustc_codegen_llvm/back/archive.rs
index 455b7086212ba..239ca57ba4143 100644
--- a/src/librustc_codegen_llvm/back/archive.rs
+++ b/src/librustc_codegen_llvm/back/archive.rs
@@ -9,9 +9,9 @@ use std::str;
 
 use crate::llvm::archive_ro::{ArchiveRO, Child};
 use crate::llvm::{self, ArchiveKind};
-use rustc::session::Session;
 use rustc_codegen_ssa::back::archive::{find_library, ArchiveBuilder};
 use rustc_codegen_ssa::{looks_like_rust_object_file, METADATA_FILENAME, RLIB_BYTECODE_EXTENSION};
+use rustc_session::Session;
 use rustc_span::symbol::Symbol;
 
 struct ArchiveConfig<'a> {
diff --git a/src/librustc_codegen_llvm/back/lto.rs b/src/librustc_codegen_llvm/back/lto.rs
index 310cae978bf5e..1b64750f51feb 100644
--- a/src/librustc_codegen_llvm/back/lto.rs
+++ b/src/librustc_codegen_llvm/back/lto.rs
@@ -9,7 +9,6 @@ use log::{debug, info};
 use rustc::bug;
 use rustc::dep_graph::WorkProduct;
 use rustc::middle::exported_symbols::SymbolExportLevel;
-use rustc::session::config::{self, Lto};
 use rustc_codegen_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule, ThinShared};
 use rustc_codegen_ssa::back::symbol_export;
 use rustc_codegen_ssa::back::write::{CodegenContext, FatLTOInput, ModuleConfig};
@@ -19,6 +18,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_errors::{FatalError, Handler};
 use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_session::cgu_reuse_tracker::CguReuse;
+use rustc_session::config::{self, Lto};
 
 use std::ffi::{CStr, CString};
 use std::fs::File;
diff --git a/src/librustc_codegen_llvm/back/write.rs b/src/librustc_codegen_llvm/back/write.rs
index 0c243128104e7..2327b96e26c36 100644
--- a/src/librustc_codegen_llvm/back/write.rs
+++ b/src/librustc_codegen_llvm/back/write.rs
@@ -15,8 +15,6 @@ use crate::LlvmCodegenBackend;
 use crate::ModuleLlvm;
 use log::debug;
 use rustc::bug;
-use rustc::session::config::{self, Lto, OutputType, Passes, Sanitizer, SwitchWithOptPath};
-use rustc::session::Session;
 use rustc::ty::TyCtxt;
 use rustc_codegen_ssa::back::write::{run_assembler, CodegenContext, ModuleConfig};
 use rustc_codegen_ssa::traits::*;
@@ -25,6 +23,8 @@ use rustc_data_structures::small_c_str::SmallCStr;
 use rustc_errors::{FatalError, Handler};
 use rustc_fs_util::{link_or_copy, path_to_c_string};
 use rustc_hir::def_id::LOCAL_CRATE;
+use rustc_session::config::{self, Lto, OutputType, Passes, Sanitizer, SwitchWithOptPath};
+use rustc_session::Session;
 
 use libc::{c_char, c_int, c_uint, c_void, size_t};
 use std::ffi::CString;
diff --git a/src/librustc_codegen_llvm/base.rs b/src/librustc_codegen_llvm/base.rs
index 04c084e459eab..0d063d82c6934 100644
--- a/src/librustc_codegen_llvm/base.rs
+++ b/src/librustc_codegen_llvm/base.rs
@@ -28,13 +28,13 @@ use rustc::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
 use rustc::middle::cstore::EncodedMetadata;
 use rustc::middle::exported_symbols;
 use rustc::mir::mono::{Linkage, Visibility};
-use rustc::session::config::DebugInfo;
 use rustc::ty::TyCtxt;
 use rustc_codegen_ssa::base::maybe_create_entry_wrapper;
 use rustc_codegen_ssa::mono_item::MonoItemExt;
 use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{ModuleCodegen, ModuleKind};
 use rustc_data_structures::small_c_str::SmallCStr;
+use rustc_session::config::DebugInfo;
 use rustc_span::symbol::Symbol;
 
 use std::ffi::CString;
diff --git a/src/librustc_codegen_llvm/builder.rs b/src/librustc_codegen_llvm/builder.rs
index 1c5987f26f129..b37d63fce6592 100644
--- a/src/librustc_codegen_llvm/builder.rs
+++ b/src/librustc_codegen_llvm/builder.rs
@@ -7,7 +7,6 @@ use crate::type_of::LayoutLlvmExt;
 use crate::value::Value;
 use libc::{c_char, c_uint};
 use log::debug;
-use rustc::session::config::{self, Sanitizer};
 use rustc::ty::layout::{self, Align, Size, TyLayout};
 use rustc::ty::{self, Ty, TyCtxt};
 use rustc_codegen_ssa::base::to_immediate;
@@ -19,6 +18,7 @@ use rustc_codegen_ssa::MemFlags;
 use rustc_data_structures::const_cstr;
 use rustc_data_structures::small_c_str::SmallCStr;
 use rustc_hir::def_id::DefId;
+use rustc_session::config::{self, Sanitizer};
 use rustc_target::spec::{HasTargetSpec, Target};
 use std::borrow::Cow;
 use std::ffi::CStr;
diff --git a/src/librustc_codegen_llvm/context.rs b/src/librustc_codegen_llvm/context.rs
index d9c88951440f4..7b1526e9da154 100644
--- a/src/librustc_codegen_llvm/context.rs
+++ b/src/librustc_codegen_llvm/context.rs
@@ -1,31 +1,30 @@
 use crate::attributes;
+use crate::callee::get_fn;
 use crate::debuginfo;
 use crate::llvm;
 use crate::llvm_util;
-use crate::value::Value;
-use rustc::dep_graph::DepGraphSafe;
-
 use crate::type_::Type;
-use rustc_codegen_ssa::traits::*;
+use crate::value::Value;
 
-use crate::callee::get_fn;
 use rustc::bug;
+use rustc::dep_graph::DepGraphSafe;
 use rustc::mir::mono::CodegenUnit;
-use rustc::session::config::{self, CFGuard, DebugInfo};
-use rustc::session::Session;
 use rustc::ty::layout::{
     HasParamEnv, LayoutError, LayoutOf, PointeeInfo, Size, TyLayout, VariantIdx,
 };
 use rustc::ty::{self, Instance, Ty, TyCtxt};
 use rustc_codegen_ssa::base::wants_msvc_seh;
+use rustc_codegen_ssa::traits::*;
 use rustc_data_structures::base_n;
 use rustc_data_structures::const_cstr;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::small_c_str::SmallCStr;
-use rustc_target::spec::{HasTargetSpec, Target};
-
+use rustc_session::config::{self, CFGuard, DebugInfo};
+use rustc_session::Session;
 use rustc_span::source_map::{Span, DUMMY_SP};
 use rustc_span::symbol::Symbol;
+use rustc_target::spec::{HasTargetSpec, Target};
+
 use std::cell::{Cell, RefCell};
 use std::ffi::CStr;
 use std::str;
diff --git a/src/librustc_codegen_llvm/debuginfo/gdb.rs b/src/librustc_codegen_llvm/debuginfo/gdb.rs
index 753a4e18faf5e..e4cbffb6db3c3 100644
--- a/src/librustc_codegen_llvm/debuginfo/gdb.rs
+++ b/src/librustc_codegen_llvm/debuginfo/gdb.rs
@@ -6,8 +6,8 @@ use crate::builder::Builder;
 use crate::common::CodegenCx;
 use crate::value::Value;
 use rustc::bug;
-use rustc::session::config::DebugInfo;
 use rustc_codegen_ssa::traits::*;
+use rustc_session::config::DebugInfo;
 
 use rustc_ast::attr;
 use rustc_span::symbol::sym;
diff --git a/src/librustc_codegen_llvm/debuginfo/metadata.rs b/src/librustc_codegen_llvm/debuginfo/metadata.rs
index 55eee13d028ca..6a7ed4e1dc384 100644
--- a/src/librustc_codegen_llvm/debuginfo/metadata.rs
+++ b/src/librustc_codegen_llvm/debuginfo/metadata.rs
@@ -24,7 +24,6 @@ use rustc::ich::NodeIdHashingMode;
 use rustc::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc::mir::interpret::truncate;
 use rustc::mir::{self, Field, GeneratorLayout};
-use rustc::session::config::{self, DebugInfo};
 use rustc::ty::layout::{
     self, Align, Integer, IntegerExt, LayoutOf, PrimitiveExt, Size, TyLayout, VariantIdx,
 };
@@ -42,6 +41,7 @@ use rustc_fs_util::path_to_c_string;
 use rustc_hir::def::CtorKind;
 use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
 use rustc_index::vec::{Idx, IndexVec};
+use rustc_session::config::{self, DebugInfo};
 use rustc_span::symbol::{Interner, Symbol};
 use rustc_span::{self, FileName, Span};
 use rustc_target::abi::HasDataLayout;
diff --git a/src/librustc_codegen_llvm/debuginfo/mod.rs b/src/librustc_codegen_llvm/debuginfo/mod.rs
index bbde541c58f1e..85decff35b9e0 100644
--- a/src/librustc_codegen_llvm/debuginfo/mod.rs
+++ b/src/librustc_codegen_llvm/debuginfo/mod.rs
@@ -20,12 +20,12 @@ use crate::builder::Builder;
 use crate::common::CodegenCx;
 use crate::value::Value;
 use rustc::mir;
-use rustc::session::config::{self, DebugInfo};
 use rustc::ty::{self, Instance, ParamEnv, Ty};
 use rustc_codegen_ssa::debuginfo::type_names;
 use rustc_codegen_ssa::mir::debuginfo::{DebugScope, FunctionDebugContext, VariableKind};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_index::vec::IndexVec;
+use rustc_session::config::{self, DebugInfo};
 
 use libc::c_uint;
 use log::debug;
diff --git a/src/librustc_codegen_llvm/lib.rs b/src/librustc_codegen_llvm/lib.rs
index f32657545745f..fa730d289b16b 100644
--- a/src/librustc_codegen_llvm/lib.rs
+++ b/src/librustc_codegen_llvm/lib.rs
@@ -15,31 +15,30 @@
 #![recursion_limit = "256"]
 
 use back::write::{create_informational_target_machine, create_target_machine};
-use rustc_span::symbol::Symbol;
 
 pub use llvm_util::target_features;
-use rustc::dep_graph::WorkProduct;
+use rustc::dep_graph::{DepGraph, WorkProduct};
+use rustc::middle::cstore::{EncodedMetadata, MetadataLoaderDyn};
+use rustc::ty::{self, TyCtxt};
+use rustc::util::common::ErrorReported;
 use rustc_ast::expand::allocator::AllocatorKind;
 use rustc_codegen_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule};
 use rustc_codegen_ssa::back::write::{CodegenContext, FatLTOInput, ModuleConfig};
 use rustc_codegen_ssa::traits::*;
+use rustc_codegen_ssa::ModuleCodegen;
 use rustc_codegen_ssa::{CodegenResults, CompiledModule};
+use rustc_codegen_utils::codegen_backend::CodegenBackend;
 use rustc_errors::{FatalError, Handler};
+use rustc_serialize::json;
+use rustc_session::config::{self, OptLevel, OutputFilenames, PrintRequest};
+use rustc_session::Session;
+use rustc_span::symbol::Symbol;
+
 use std::any::Any;
 use std::ffi::CStr;
 use std::fs;
 use std::sync::Arc;
 
-use rustc::dep_graph::DepGraph;
-use rustc::middle::cstore::{EncodedMetadata, MetadataLoaderDyn};
-use rustc::session::config::{self, OptLevel, OutputFilenames, PrintRequest};
-use rustc::session::Session;
-use rustc::ty::{self, TyCtxt};
-use rustc::util::common::ErrorReported;
-use rustc_codegen_ssa::ModuleCodegen;
-use rustc_codegen_utils::codegen_backend::CodegenBackend;
-use rustc_serialize::json;
-
 mod back {
     pub mod archive;
     pub mod bytecode;
diff --git a/src/librustc_codegen_llvm/llvm/ffi.rs b/src/librustc_codegen_llvm/llvm/ffi.rs
index 388b6c7483958..c17c06718f506 100644
--- a/src/librustc_codegen_llvm/llvm/ffi.rs
+++ b/src/librustc_codegen_llvm/llvm/ffi.rs
@@ -694,8 +694,8 @@ pub mod debuginfo {
     }
 
     impl DebugEmissionKind {
-        pub fn from_generic(kind: rustc::session::config::DebugInfo) -> Self {
-            use rustc::session::config::DebugInfo;
+        pub fn from_generic(kind: rustc_session::config::DebugInfo) -> Self {
+            use rustc_session::config::DebugInfo;
             match kind {
                 DebugInfo::None => DebugEmissionKind::NoDebug,
                 DebugInfo::Limited => DebugEmissionKind::LineTablesOnly,
diff --git a/src/librustc_codegen_llvm/llvm_util.rs b/src/librustc_codegen_llvm/llvm_util.rs
index 0081a75a4da11..5e924c9af8481 100644
--- a/src/librustc_codegen_llvm/llvm_util.rs
+++ b/src/librustc_codegen_llvm/llvm_util.rs
@@ -2,10 +2,10 @@ use crate::back::write::create_informational_target_machine;
 use crate::llvm;
 use libc::c_int;
 use rustc::bug;
-use rustc::session::config::PrintRequest;
-use rustc::session::Session;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_feature::UnstableFeatures;
+use rustc_session::config::PrintRequest;
+use rustc_session::Session;
 use rustc_span::symbol::sym;
 use rustc_span::symbol::Symbol;
 use rustc_target::spec::{MergeFunctions, PanicStrategy};
diff --git a/src/librustc_codegen_ssa/back/archive.rs b/src/librustc_codegen_ssa/back/archive.rs
index a357c350287fb..f83b4b2b0c025 100644
--- a/src/librustc_codegen_ssa/back/archive.rs
+++ b/src/librustc_codegen_ssa/back/archive.rs
@@ -1,4 +1,4 @@
-use rustc::session::Session;
+use rustc_session::Session;
 use rustc_span::symbol::Symbol;
 
 use std::io;
diff --git a/src/librustc_codegen_ssa/back/link.rs b/src/librustc_codegen_ssa/back/link.rs
index a71fe4430388d..af413d3cdfe68 100644
--- a/src/librustc_codegen_ssa/back/link.rs
+++ b/src/librustc_codegen_ssa/back/link.rs
@@ -1,15 +1,15 @@
 use rustc::middle::cstore::{EncodedMetadata, LibSource, NativeLibrary, NativeLibraryKind};
 use rustc::middle::dependency_format::Linkage;
-use rustc::session::config::{
+use rustc_data_structures::fx::FxHashSet;
+use rustc_fs_util::fix_windows_verbatim_for_gcc;
+use rustc_hir::def_id::CrateNum;
+use rustc_session::config::{
     self, CFGuard, DebugInfo, OutputFilenames, OutputType, PrintRequest, Sanitizer,
 };
-use rustc::session::search_paths::PathKind;
+use rustc_session::search_paths::PathKind;
 /// For all the linkers we support, and information they might
 /// need out of the shared crate context before we get rid of it.
-use rustc::session::{filesearch, Session};
-use rustc_data_structures::fx::FxHashSet;
-use rustc_fs_util::fix_windows_verbatim_for_gcc;
-use rustc_hir::def_id::CrateNum;
+use rustc_session::{filesearch, Session};
 use rustc_span::symbol::Symbol;
 use rustc_target::spec::{LinkerFlavor, PanicStrategy, RelroLevel};
 
diff --git a/src/librustc_codegen_ssa/back/linker.rs b/src/librustc_codegen_ssa/back/linker.rs
index 5aafb8a12d74b..6b30ae8559db9 100644
--- a/src/librustc_codegen_ssa/back/linker.rs
+++ b/src/librustc_codegen_ssa/back/linker.rs
@@ -2,7 +2,6 @@ use super::archive;
 use super::command::Command;
 use super::symbol_export;
 
-use rustc_data_structures::fx::FxHashMap;
 use std::ffi::{OsStr, OsString};
 use std::fs::{self, File};
 use std::io::prelude::*;
@@ -10,11 +9,12 @@ use std::io::{self, BufWriter};
 use std::path::{Path, PathBuf};
 
 use rustc::middle::dependency_format::Linkage;
-use rustc::session::config::{self, CrateType, DebugInfo, LinkerPluginLto, Lto, OptLevel};
-use rustc::session::Session;
 use rustc::ty::TyCtxt;
+use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_serialize::{json, Encoder};
+use rustc_session::config::{self, CrateType, DebugInfo, LinkerPluginLto, Lto, OptLevel};
+use rustc_session::Session;
 use rustc_span::symbol::Symbol;
 use rustc_target::spec::{LinkerFlavor, LldFlavor};
 
diff --git a/src/librustc_codegen_ssa/back/symbol_export.rs b/src/librustc_codegen_ssa/back/symbol_export.rs
index 178a74c791b4c..8368d98884a5d 100644
--- a/src/librustc_codegen_ssa/back/symbol_export.rs
+++ b/src/librustc_codegen_ssa/back/symbol_export.rs
@@ -3,7 +3,6 @@ use std::sync::Arc;
 
 use rustc::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc::middle::exported_symbols::{metadata_symbol_name, ExportedSymbol, SymbolExportLevel};
-use rustc::session::config::{self, Sanitizer};
 use rustc::ty::query::Providers;
 use rustc::ty::subst::{GenericArgKind, SubstsRef};
 use rustc::ty::Instance;
@@ -16,6 +15,7 @@ use rustc_hir as hir;
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_hir::Node;
 use rustc_index::vec::IndexVec;
+use rustc_session::config::{self, Sanitizer};
 
 pub fn threshold(tcx: TyCtxt<'_>) -> SymbolExportLevel {
     crates_export_threshold(&tcx.sess.crate_types.borrow())
diff --git a/src/librustc_codegen_ssa/back/write.rs b/src/librustc_codegen_ssa/back/write.rs
index dbc2ef6f2b05e..303ee38565848 100644
--- a/src/librustc_codegen_ssa/back/write.rs
+++ b/src/librustc_codegen_ssa/back/write.rs
@@ -14,10 +14,6 @@ use jobserver::{Acquired, Client};
 use rustc::dep_graph::{WorkProduct, WorkProductFileKind, WorkProductId};
 use rustc::middle::cstore::EncodedMetadata;
 use rustc::middle::exported_symbols::SymbolExportLevel;
-use rustc::session::config::{
-    self, Lto, OutputFilenames, OutputType, Passes, Sanitizer, SwitchWithOptPath,
-};
-use rustc::session::Session;
 use rustc::ty::TyCtxt;
 use rustc_ast::attr;
 use rustc_data_structures::fx::FxHashMap;
@@ -34,6 +30,10 @@ use rustc_incremental::{
     copy_cgu_workproducts_to_incr_comp_cache_dir, in_incr_comp_dir, in_incr_comp_dir_sess,
 };
 use rustc_session::cgu_reuse_tracker::CguReuseTracker;
+use rustc_session::config::{
+    self, Lto, OutputFilenames, OutputType, Passes, Sanitizer, SwitchWithOptPath,
+};
+use rustc_session::Session;
 use rustc_span::hygiene::ExpnId;
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::{sym, Symbol};
diff --git a/src/librustc_codegen_ssa/base.rs b/src/librustc_codegen_ssa/base.rs
index d6e1ab8909c59..e57cae30b7795 100644
--- a/src/librustc_codegen_ssa/base.rs
+++ b/src/librustc_codegen_ssa/base.rs
@@ -31,8 +31,6 @@ use rustc::middle::cstore::{self, LinkagePreference};
 use rustc::middle::lang_items;
 use rustc::middle::lang_items::StartFnLangItem;
 use rustc::mir::mono::{CodegenUnit, CodegenUnitNameBuilder, MonoItem};
-use rustc::session::config::{self, EntryFnType, Lto};
-use rustc::session::Session;
 use rustc::ty::layout::{self, Align, HasTyCtxt, LayoutOf, TyLayout, VariantIdx};
 use rustc::ty::layout::{FAT_PTR_ADDR, FAT_PTR_EXTRA};
 use rustc::ty::query::Providers;
@@ -46,6 +44,8 @@ use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_index::vec::Idx;
 use rustc_session::cgu_reuse_tracker::CguReuse;
+use rustc_session::config::{self, EntryFnType, Lto};
+use rustc_session::Session;
 use rustc_span::Span;
 
 use std::cmp;
diff --git a/src/librustc_codegen_ssa/common.rs b/src/librustc_codegen_ssa/common.rs
index 28b61e0b36d64..147b23995023f 100644
--- a/src/librustc_codegen_ssa/common.rs
+++ b/src/librustc_codegen_ssa/common.rs
@@ -1,8 +1,8 @@
 #![allow(non_camel_case_types, non_snake_case)]
 
-use rustc::session::Session;
 use rustc::ty::{Ty, TyCtxt};
 use rustc_errors::struct_span_err;
+use rustc_session::Session;
 use rustc_span::Span;
 
 use crate::base;
diff --git a/src/librustc_codegen_ssa/lib.rs b/src/librustc_codegen_ssa/lib.rs
index a2bb39b9e4019..d2afbdc23e1fd 100644
--- a/src/librustc_codegen_ssa/lib.rs
+++ b/src/librustc_codegen_ssa/lib.rs
@@ -21,12 +21,12 @@ use rustc::dep_graph::WorkProduct;
 use rustc::middle::cstore::{CrateSource, LibSource, NativeLibrary};
 use rustc::middle::dependency_format::Dependencies;
 use rustc::middle::lang_items::LangItem;
-use rustc::session::config::{OutputFilenames, OutputType, RUST_CGU_EXT};
 use rustc::ty::query::Providers;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::Lrc;
 use rustc_hir::def_id::CrateNum;
+use rustc_session::config::{OutputFilenames, OutputType, RUST_CGU_EXT};
 use rustc_span::symbol::Symbol;
 use std::path::{Path, PathBuf};
 
diff --git a/src/librustc_codegen_ssa/mir/debuginfo.rs b/src/librustc_codegen_ssa/mir/debuginfo.rs
index 2dc1405f4e438..cbe5f51115246 100644
--- a/src/librustc_codegen_ssa/mir/debuginfo.rs
+++ b/src/librustc_codegen_ssa/mir/debuginfo.rs
@@ -1,10 +1,10 @@
 use crate::traits::*;
 use rustc::mir;
-use rustc::session::config::DebugInfo;
 use rustc::ty;
 use rustc::ty::layout::{LayoutOf, Size};
 use rustc_hir::def_id::CrateNum;
 use rustc_index::vec::IndexVec;
+use rustc_session::config::DebugInfo;
 
 use rustc_span::symbol::{kw, Symbol};
 use rustc_span::{BytePos, Span};
diff --git a/src/librustc_codegen_ssa/traits/backend.rs b/src/librustc_codegen_ssa/traits/backend.rs
index 5535841156acd..7acae300a2f02 100644
--- a/src/librustc_codegen_ssa/traits/backend.rs
+++ b/src/librustc_codegen_ssa/traits/backend.rs
@@ -3,12 +3,12 @@ use super::CodegenObject;
 use crate::ModuleCodegen;
 
 use rustc::middle::cstore::EncodedMetadata;
-use rustc::session::{config, Session};
 use rustc::ty::layout::{HasTyCtxt, LayoutOf, TyLayout};
 use rustc::ty::Ty;
 use rustc::ty::TyCtxt;
 use rustc_ast::expand::allocator::AllocatorKind;
 use rustc_codegen_utils::codegen_backend::CodegenBackend;
+use rustc_session::{config, Session};
 use rustc_span::symbol::Symbol;
 
 use std::sync::Arc;
diff --git a/src/librustc_codegen_ssa/traits/misc.rs b/src/librustc_codegen_ssa/traits/misc.rs
index d7587163ba001..6863b474cb6de 100644
--- a/src/librustc_codegen_ssa/traits/misc.rs
+++ b/src/librustc_codegen_ssa/traits/misc.rs
@@ -1,8 +1,8 @@
 use super::BackendTypes;
 use rustc::mir::mono::CodegenUnit;
-use rustc::session::Session;
 use rustc::ty::{self, Instance, Ty};
 use rustc_data_structures::fx::FxHashMap;
+use rustc_session::Session;
 use std::cell::RefCell;
 use std::sync::Arc;
 
diff --git a/src/librustc_codegen_utils/Cargo.toml b/src/librustc_codegen_utils/Cargo.toml
index b5533a8307c3d..7ab59029bc8a9 100644
--- a/src/librustc_codegen_utils/Cargo.toml
+++ b/src/librustc_codegen_utils/Cargo.toml
@@ -21,3 +21,4 @@ rustc_hir = { path = "../librustc_hir" }
 rustc_target = { path = "../librustc_target" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_metadata = { path = "../librustc_metadata" }
+rustc_session = { path = "../librustc_session" }
diff --git a/src/librustc_codegen_utils/codegen_backend.rs b/src/librustc_codegen_utils/codegen_backend.rs
index 96166e04c2e3c..561692e70669a 100644
--- a/src/librustc_codegen_utils/codegen_backend.rs
+++ b/src/librustc_codegen_utils/codegen_backend.rs
@@ -10,11 +10,11 @@ use std::any::Any;
 
 use rustc::dep_graph::DepGraph;
 use rustc::middle::cstore::{EncodedMetadata, MetadataLoaderDyn};
-use rustc::session::config::{OutputFilenames, PrintRequest};
-use rustc::session::Session;
 use rustc::ty::query::Providers;
 use rustc::ty::TyCtxt;
 use rustc::util::common::ErrorReported;
+use rustc_session::config::{OutputFilenames, PrintRequest};
+use rustc_session::Session;
 use rustc_span::symbol::Symbol;
 
 pub use rustc_data_structures::sync::MetadataRef;
diff --git a/src/librustc_codegen_utils/link.rs b/src/librustc_codegen_utils/link.rs
index 2850a29148ed0..1f53eec514bbf 100644
--- a/src/librustc_codegen_utils/link.rs
+++ b/src/librustc_codegen_utils/link.rs
@@ -1,6 +1,6 @@
-use rustc::session::config::{self, Input, OutputFilenames, OutputType};
-use rustc::session::Session;
 use rustc_ast::{ast, attr};
+use rustc_session::config::{self, Input, OutputFilenames, OutputType};
+use rustc_session::Session;
 use rustc_span::symbol::sym;
 use rustc_span::Span;
 use std::path::{Path, PathBuf};
diff --git a/src/librustc_codegen_utils/symbol_names.rs b/src/librustc_codegen_utils/symbol_names.rs
index cfde09fad62cc..eb3fe49a5e9cc 100644
--- a/src/librustc_codegen_utils/symbol_names.rs
+++ b/src/librustc_codegen_utils/symbol_names.rs
@@ -89,12 +89,12 @@
 
 use rustc::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc::mir::mono::{InstantiationMode, MonoItem};
-use rustc::session::config::SymbolManglingVersion;
 use rustc::ty::query::Providers;
 use rustc::ty::subst::SubstsRef;
 use rustc::ty::{self, Instance, TyCtxt};
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_hir::Node;
+use rustc_session::config::SymbolManglingVersion;
 
 use rustc_span::symbol::Symbol;
 
diff --git a/src/librustc_driver/Cargo.toml b/src/librustc_driver/Cargo.toml
index 26f1741153c8c..3e6449582319f 100644
--- a/src/librustc_driver/Cargo.toml
+++ b/src/librustc_driver/Cargo.toml
@@ -33,6 +33,7 @@ rustc_interface = { path = "../librustc_interface" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 rustc_ast = { path = "../librustc_ast" }
 rustc_span = { path = "../librustc_span" }
+rustc_session = { path = "../librustc_session" }
 
 [target.'cfg(windows)'.dependencies]
 winapi = { version = "0.3", features = ["consoleapi", "debugapi", "processenv"] }
diff --git a/src/librustc_driver/lib.rs b/src/librustc_driver/lib.rs
index 8acb2260cbe89..34f0c182499db 100644
--- a/src/librustc_driver/lib.rs
+++ b/src/librustc_driver/lib.rs
@@ -18,12 +18,7 @@ extern crate lazy_static;
 
 pub extern crate rustc_plugin_impl as plugin;
 
-use rustc::lint::{Lint, LintId};
 use rustc::middle::cstore::MetadataLoader;
-use rustc::session::config::nightly_options;
-use rustc::session::config::{ErrorOutputType, Input, OutputType, PrintRequest};
-use rustc::session::{config, DiagnosticOutput, Session};
-use rustc::session::{early_error, early_warn};
 use rustc::ty::TyCtxt;
 use rustc::util::common::ErrorReported;
 use rustc_codegen_ssa::CodegenResults;
@@ -43,6 +38,11 @@ use rustc_metadata::locator;
 use rustc_save_analysis as save;
 use rustc_save_analysis::DumpHandler;
 use rustc_serialize::json::{self, ToJson};
+use rustc_session::config::nightly_options;
+use rustc_session::config::{ErrorOutputType, Input, OutputType, PrintRequest};
+use rustc_session::lint::{Lint, LintId};
+use rustc_session::{config, DiagnosticOutput, Session};
+use rustc_session::{early_error, early_warn};
 
 use std::borrow::Cow;
 use std::cmp::max;
@@ -652,7 +652,7 @@ impl RustcDefaultCalls {
         odir: &Option<PathBuf>,
         ofile: &Option<PathBuf>,
     ) -> Compilation {
-        use rustc::session::config::PrintRequest::*;
+        use rustc_session::config::PrintRequest::*;
         // PrintRequest::NativeStaticLibs is special - printed during linking
         // (empty iterator returns true)
         if sess.opts.prints.iter().all(|&p| p == PrintRequest::NativeStaticLibs) {
diff --git a/src/librustc_driver/pretty.rs b/src/librustc_driver/pretty.rs
index 2361046c0366c..1e5cc55a82853 100644
--- a/src/librustc_driver/pretty.rs
+++ b/src/librustc_driver/pretty.rs
@@ -1,8 +1,6 @@
 //! The various pretty-printing routines.
 
 use rustc::hir::map as hir_map;
-use rustc::session::config::{Input, PpMode, PpSourceMode};
-use rustc::session::Session;
 use rustc::ty::{self, TyCtxt};
 use rustc::util::common::ErrorReported;
 use rustc_ast::ast;
@@ -11,6 +9,8 @@ use rustc_hir as hir;
 use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_hir::print as pprust_hir;
 use rustc_mir::util::{write_mir_graphviz, write_mir_pretty};
+use rustc_session::config::{Input, PpMode, PpSourceMode};
+use rustc_session::Session;
 use rustc_span::FileName;
 
 use std::cell::Cell;
diff --git a/src/librustc_error_codes/error_codes/E0308.md b/src/librustc_error_codes/error_codes/E0308.md
index a907ca272970e..7d87d54194e9b 100644
--- a/src/librustc_error_codes/error_codes/E0308.md
+++ b/src/librustc_error_codes/error_codes/E0308.md
@@ -1,10 +1,6 @@
-This error occurs when the compiler was unable to infer the concrete type of a
-variable. It can occur for several cases, the most common of which is a
-mismatch in the expected type that the compiler inferred for a variable's
-initializing expression, and the actual type explicitly assigned to the
-variable.
+Expected type did not match the received type.
 
-For example:
+Erroneous code example:
 
 ```compile_fail,E0308
 let x: i32 = "I am not a number!";
@@ -15,3 +11,9 @@ let x: i32 = "I am not a number!";
 //      |
 //    type `i32` assigned to variable `x`
 ```
+
+This error occurs when the compiler was unable to infer the concrete type of a
+variable. It can occur for several cases, the most common of which is a
+mismatch in the expected type that the compiler inferred for a variable's
+initializing expression, and the actual type explicitly assigned to the
+variable.
diff --git a/src/librustc_errors/emitter.rs b/src/librustc_errors/emitter.rs
index 03f83e616365b..26f1fa267f9b5 100644
--- a/src/librustc_errors/emitter.rs
+++ b/src/librustc_errors/emitter.rs
@@ -5,7 +5,7 @@
 //! There are various `Emitter` implementations that generate different output formats such as
 //! JSON and human readable output.
 //!
-//! The output types are defined in `librustc::session::config::ErrorOutputType`.
+//! The output types are defined in `rustc_session::config::ErrorOutputType`.
 
 use Destination::*;
 
diff --git a/src/librustc_expand/base.rs b/src/librustc_expand/base.rs
index f5f2a5ed43f2c..7af39ee3c0bb9 100644
--- a/src/librustc_expand/base.rs
+++ b/src/librustc_expand/base.rs
@@ -9,7 +9,7 @@ use rustc_ast::visit::{AssocCtxt, Visitor};
 use rustc_attr::{self as attr, Deprecation, HasAttrs, Stability};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::{self, Lrc};
-use rustc_errors::{DiagnosticBuilder, DiagnosticId};
+use rustc_errors::{DiagnosticBuilder, ErrorReported};
 use rustc_parse::{self, parser, DirectoryOwnership, MACRO_ARGUMENTS};
 use rustc_session::parse::ParseSess;
 use rustc_span::edition::Edition;
@@ -295,16 +295,26 @@ where
 }
 
 pub trait ProcMacro {
-    fn expand<'cx>(&self, ecx: &'cx mut ExtCtxt<'_>, span: Span, ts: TokenStream) -> TokenStream;
+    fn expand<'cx>(
+        &self,
+        ecx: &'cx mut ExtCtxt<'_>,
+        span: Span,
+        ts: TokenStream,
+    ) -> Result<TokenStream, ErrorReported>;
 }
 
 impl<F> ProcMacro for F
 where
     F: Fn(TokenStream) -> TokenStream,
 {
-    fn expand<'cx>(&self, _ecx: &'cx mut ExtCtxt<'_>, _span: Span, ts: TokenStream) -> TokenStream {
+    fn expand<'cx>(
+        &self,
+        _ecx: &'cx mut ExtCtxt<'_>,
+        _span: Span,
+        ts: TokenStream,
+    ) -> Result<TokenStream, ErrorReported> {
         // FIXME setup implicit context in TLS before calling self.
-        (*self)(ts)
+        Ok((*self)(ts))
     }
 }
 
@@ -315,7 +325,7 @@ pub trait AttrProcMacro {
         span: Span,
         annotation: TokenStream,
         annotated: TokenStream,
-    ) -> TokenStream;
+    ) -> Result<TokenStream, ErrorReported>;
 }
 
 impl<F> AttrProcMacro for F
@@ -328,9 +338,9 @@ where
         _span: Span,
         annotation: TokenStream,
         annotated: TokenStream,
-    ) -> TokenStream {
+    ) -> Result<TokenStream, ErrorReported> {
         // FIXME setup implicit context in TLS before calling self.
-        (*self)(annotation, annotated)
+        Ok((*self)(annotation, annotated))
     }
 }
 
@@ -921,6 +931,7 @@ pub struct ExpansionData {
 pub struct ExtCtxt<'a> {
     pub parse_sess: &'a ParseSess,
     pub ecfg: expand::ExpansionConfig<'a>,
+    pub reduced_recursion_limit: Option<usize>,
     pub root_path: PathBuf,
     pub resolver: &'a mut dyn Resolver,
     pub current_expansion: ExpansionData,
@@ -936,6 +947,7 @@ impl<'a> ExtCtxt<'a> {
         ExtCtxt {
             parse_sess,
             ecfg,
+            reduced_recursion_limit: None,
             root_path: PathBuf::new(),
             resolver,
             current_expansion: ExpansionData {
@@ -997,31 +1009,9 @@ impl<'a> ExtCtxt<'a> {
         self.current_expansion.id.expansion_cause()
     }
 
-    pub fn struct_span_warn<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> DiagnosticBuilder<'a> {
-        self.parse_sess.span_diagnostic.struct_span_warn(sp, msg)
-    }
     pub fn struct_span_err<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> DiagnosticBuilder<'a> {
         self.parse_sess.span_diagnostic.struct_span_err(sp, msg)
     }
-    pub fn struct_span_fatal<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> DiagnosticBuilder<'a> {
-        self.parse_sess.span_diagnostic.struct_span_fatal(sp, msg)
-    }
-
-    /// Emit `msg` attached to `sp`, and stop compilation immediately.
-    ///
-    /// `span_err` should be strongly preferred where-ever possible:
-    /// this should *only* be used when:
-    ///
-    /// - continuing has a high risk of flow-on errors (e.g., errors in
-    ///   declaring a macro would cause all uses of that macro to
-    ///   complain about "undefined macro"), or
-    /// - there is literally nothing else that can be done (however,
-    ///   in most cases one can construct a dummy expression/item to
-    ///   substitute; we never hit resolve/type-checking so the dummy
-    ///   value doesn't have to match anything)
-    pub fn span_fatal<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ! {
-        self.parse_sess.span_diagnostic.span_fatal(sp, msg).raise();
-    }
 
     /// Emit `msg` attached to `sp`, without immediately stopping
     /// compilation.
@@ -1031,9 +1021,6 @@ impl<'a> ExtCtxt<'a> {
     pub fn span_err<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
         self.parse_sess.span_diagnostic.span_err(sp, msg);
     }
-    pub fn span_err_with_code<S: Into<MultiSpan>>(&self, sp: S, msg: &str, code: DiagnosticId) {
-        self.parse_sess.span_diagnostic.span_err_with_code(sp, msg, code);
-    }
     pub fn span_warn<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
         self.parse_sess.span_diagnostic.span_warn(sp, msg);
     }
@@ -1161,6 +1148,18 @@ pub fn check_zero_tts(cx: &ExtCtxt<'_>, sp: Span, tts: TokenStream, name: &str)
     }
 }
 
+/// Parse an expression. On error, emit it, advancing to `Eof`, and return `None`.
+pub fn parse_expr(p: &mut parser::Parser<'_>) -> Option<P<ast::Expr>> {
+    match p.parse_expr() {
+        Ok(e) => return Some(e),
+        Err(mut err) => err.emit(),
+    }
+    while p.token != token::Eof {
+        p.bump();
+    }
+    None
+}
+
 /// Interpreting `tts` as a comma-separated sequence of expressions,
 /// expect exactly one string literal, or emit an error and return `None`.
 pub fn get_single_str_from_tts(
@@ -1174,7 +1173,7 @@ pub fn get_single_str_from_tts(
         cx.span_err(sp, &format!("{} takes 1 argument", name));
         return None;
     }
-    let ret = panictry!(p.parse_expr());
+    let ret = parse_expr(&mut p)?;
     let _ = p.eat(&token::Comma);
 
     if p.token != token::Eof {
@@ -1183,8 +1182,8 @@ pub fn get_single_str_from_tts(
     expr_to_string(cx, ret, "argument must be a string literal").map(|(s, _)| s.to_string())
 }
 
-/// Extracts comma-separated expressions from `tts`. If there is a
-/// parsing error, emit a non-fatal error and return `None`.
+/// Extracts comma-separated expressions from `tts`.
+/// On error, emit it, and return `None`.
 pub fn get_exprs_from_tts(
     cx: &mut ExtCtxt<'_>,
     sp: Span,
@@ -1193,7 +1192,7 @@ pub fn get_exprs_from_tts(
     let mut p = cx.new_parser_from_tts(tts);
     let mut es = Vec::new();
     while p.token != token::Eof {
-        let expr = panictry!(p.parse_expr());
+        let expr = parse_expr(&mut p)?;
 
         // Perform eager expansion on the expression.
         // We want to be able to handle e.g., `concat!("foo", "bar")`.
diff --git a/src/librustc_expand/expand.rs b/src/librustc_expand/expand.rs
index 4d0548f3f868a..ae2f8cba8ca80 100644
--- a/src/librustc_expand/expand.rs
+++ b/src/librustc_expand/expand.rs
@@ -15,7 +15,7 @@ use rustc_ast::util::map_in_place::MapInPlace;
 use rustc_ast::visit::{self, AssocCtxt, Visitor};
 use rustc_ast_pretty::pprust;
 use rustc_attr::{self as attr, is_builtin_attr, HasAttrs};
-use rustc_errors::{Applicability, FatalError, PResult};
+use rustc_errors::{Applicability, PResult};
 use rustc_feature::Features;
 use rustc_parse::configure;
 use rustc_parse::parser::Parser;
@@ -204,7 +204,7 @@ ast_fragments! {
 }
 
 impl AstFragmentKind {
-    fn dummy(self, span: Span) -> AstFragment {
+    crate fn dummy(self, span: Span) -> AstFragment {
         self.make_from(DummyResult::any(span)).expect("couldn't create a dummy AST fragment")
     }
 
@@ -645,7 +645,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             ))
             .emit();
         self.cx.trace_macros_diag();
-        FatalError.raise();
     }
 
     /// A macro's expansion does not fit in this fragment kind.
@@ -665,8 +664,17 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         invoc: Invocation,
         ext: &SyntaxExtensionKind,
     ) -> ExpandResult<AstFragment, Invocation> {
-        if self.cx.current_expansion.depth > self.cx.ecfg.recursion_limit {
-            self.error_recursion_limit_reached();
+        let recursion_limit =
+            self.cx.reduced_recursion_limit.unwrap_or(self.cx.ecfg.recursion_limit);
+        if self.cx.current_expansion.depth > recursion_limit {
+            if self.cx.reduced_recursion_limit.is_none() {
+                self.error_recursion_limit_reached();
+            }
+
+            // Reduce the recursion limit by half each time it triggers.
+            self.cx.reduced_recursion_limit = Some(recursion_limit / 2);
+
+            return ExpandResult::Ready(invoc.fragment_kind.dummy(invoc.span()));
         }
 
         let (fragment_kind, span) = (invoc.fragment_kind, invoc.span());
@@ -674,7 +682,10 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             InvocationKind::Bang { mac, .. } => match ext {
                 SyntaxExtensionKind::Bang(expander) => {
                     self.gate_proc_macro_expansion_kind(span, fragment_kind);
-                    let tok_result = expander.expand(self.cx, span, mac.args.inner_tokens());
+                    let tok_result = match expander.expand(self.cx, span, mac.args.inner_tokens()) {
+                        Err(_) => return ExpandResult::Ready(fragment_kind.dummy(span)),
+                        Ok(ts) => ts,
+                    };
                     self.parse_ast_fragment(tok_result, fragment_kind, &mac.path, span)
                 }
                 SyntaxExtensionKind::LegacyBang(expander) => {
@@ -701,8 +712,11 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                     if let MacArgs::Eq(..) = attr_item.args {
                         self.cx.span_err(span, "key-value macro attributes are not supported");
                     }
-                    let tok_result =
-                        expander.expand(self.cx, span, attr_item.args.inner_tokens(), tokens);
+                    let inner_tokens = attr_item.args.inner_tokens();
+                    let tok_result = match expander.expand(self.cx, span, inner_tokens, tokens) {
+                        Err(_) => return ExpandResult::Ready(fragment_kind.dummy(span)),
+                        Ok(ts) => ts,
+                    };
                     self.parse_ast_fragment(tok_result, fragment_kind, &attr_item.path, span)
                 }
                 SyntaxExtensionKind::LegacyAttr(expander) => {
@@ -1131,6 +1145,8 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
             // macros are expanded before any lint passes so this warning has to be hardcoded
             if attr.has_name(sym::derive) {
                 self.cx
+                    .parse_sess()
+                    .span_diagnostic
                     .struct_span_warn(attr.span, "`#[derive]` does nothing on macro invocations")
                     .note("this may become a hard error in a future release")
                     .emit();
diff --git a/src/librustc_expand/lib.rs b/src/librustc_expand/lib.rs
index f119c956ced04..434d00e905281 100644
--- a/src/librustc_expand/lib.rs
+++ b/src/librustc_expand/lib.rs
@@ -7,25 +7,6 @@
 
 extern crate proc_macro as pm;
 
-// A variant of 'try!' that panics on an Err. This is used as a crutch on the
-// way towards a non-panic!-prone parser. It should be used for fatal parsing
-// errors; eventually we plan to convert all code using panictry to just use
-// normal try.
-#[macro_export]
-macro_rules! panictry {
-    ($e:expr) => {{
-        use rustc_errors::FatalError;
-        use std::result::Result::{Err, Ok};
-        match $e {
-            Ok(e) => e,
-            Err(mut e) => {
-                e.emit();
-                FatalError.raise()
-            }
-        }
-    }};
-}
-
 mod placeholders;
 mod proc_macro_server;
 
diff --git a/src/librustc_expand/mbe/macro_parser.rs b/src/librustc_expand/mbe/macro_parser.rs
index 3b9158f444519..a3ab98357f40d 100644
--- a/src/librustc_expand/mbe/macro_parser.rs
+++ b/src/librustc_expand/mbe/macro_parser.rs
@@ -84,7 +84,7 @@ use rustc_parse::parser::{FollowedByType, Parser, PathStyle};
 use rustc_session::parse::ParseSess;
 use rustc_span::symbol::{kw, sym, Ident, MacroRulesNormalizedIdent, Symbol};
 
-use rustc_errors::{FatalError, PResult};
+use rustc_errors::PResult;
 use rustc_span::Span;
 use smallvec::{smallvec, SmallVec};
 
@@ -271,6 +271,7 @@ crate enum ParseResult<T> {
     Failure(Token, &'static str),
     /// Fatal error (malformed macro?). Abort compilation.
     Error(rustc_span::Span, String),
+    ErrorReported,
 }
 
 /// A `ParseResult` where the `Success` variant contains a mapping of
@@ -652,6 +653,7 @@ pub(super) fn parse_tt(parser: &mut Cow<'_, Parser<'_>>, ms: &[TokenTree]) -> Na
             Success(_) => {}
             Failure(token, msg) => return Failure(token, msg),
             Error(sp, msg) => return Error(sp, msg),
+            ErrorReported => return ErrorReported,
         }
 
         // inner parse loop handled all cur_items, so it's empty
@@ -735,10 +737,11 @@ pub(super) fn parse_tt(parser: &mut Cow<'_, Parser<'_>>, ms: &[TokenTree]) -> Na
             let mut item = bb_items.pop().unwrap();
             if let TokenTree::MetaVarDecl(span, _, ident) = item.top_elts.get_tt(item.idx) {
                 let match_cur = item.match_cur;
-                item.push_match(
-                    match_cur,
-                    MatchedNonterminal(Lrc::new(parse_nt(parser.to_mut(), span, ident.name))),
-                );
+                let nt = match parse_nt(parser.to_mut(), span, ident.name) {
+                    Err(()) => return ErrorReported,
+                    Ok(nt) => nt,
+                };
+                item.push_match(match_cur, MatchedNonterminal(Lrc::new(nt)));
                 item.idx += 1;
                 item.match_cur += 1;
             } else {
@@ -849,20 +852,16 @@ fn may_begin_with(token: &Token, name: Name) -> bool {
 /// # Returns
 ///
 /// The parsed non-terminal.
-fn parse_nt(p: &mut Parser<'_>, sp: Span, name: Symbol) -> Nonterminal {
+fn parse_nt(p: &mut Parser<'_>, sp: Span, name: Symbol) -> Result<Nonterminal, ()> {
     // FIXME(Centril): Consider moving this to `parser.rs` to make
     // the visibilities of the methods used below `pub(super)` at most.
-
     if name == sym::tt {
-        return token::NtTT(p.parse_token_tree());
-    }
-    match parse_nt_inner(p, sp, name) {
-        Ok(nt) => nt,
-        Err(mut err) => {
-            err.emit();
-            FatalError.raise();
-        }
+        return Ok(token::NtTT(p.parse_token_tree()));
     }
+    parse_nt_inner(p, sp, name).map_err(|mut err| {
+        err.span_label(sp, format!("while parsing argument for this `{}` macro fragment", name))
+            .emit()
+    })
 }
 
 fn parse_nt_inner<'a>(p: &mut Parser<'a>, sp: Span, name: Symbol) -> PResult<'a, Nonterminal> {
diff --git a/src/librustc_expand/mbe/macro_rules.rs b/src/librustc_expand/mbe/macro_rules.rs
index 2268c9b385477..c4a79b87bfdef 100644
--- a/src/librustc_expand/mbe/macro_rules.rs
+++ b/src/librustc_expand/mbe/macro_rules.rs
@@ -4,7 +4,7 @@ use crate::expand::{ensure_complete_parse, parse_ast_fragment, AstFragment, AstF
 use crate::mbe;
 use crate::mbe::macro_check;
 use crate::mbe::macro_parser::parse_tt;
-use crate::mbe::macro_parser::{Error, Failure, Success};
+use crate::mbe::macro_parser::{Error, ErrorReported, Failure, Success};
 use crate::mbe::macro_parser::{MatchedNonterminal, MatchedSeq};
 use crate::mbe::transcribe::transcribe;
 
@@ -15,7 +15,7 @@ use rustc_ast_pretty::pprust;
 use rustc_attr::{self as attr, TransparencyError};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::Lrc;
-use rustc_errors::{Applicability, DiagnosticBuilder, FatalError};
+use rustc_errors::{Applicability, DiagnosticBuilder};
 use rustc_feature::Features;
 use rustc_parse::parser::Parser;
 use rustc_parse::Directory;
@@ -84,41 +84,56 @@ fn suggest_slice_pat(e: &mut DiagnosticBuilder<'_>, site_span: Span, parser: &Pa
     );
 }
 
+fn emit_frag_parse_err(
+    mut e: DiagnosticBuilder<'_>,
+    parser: &Parser<'_>,
+    site_span: Span,
+    macro_ident: ast::Ident,
+    arm_span: Span,
+    kind: AstFragmentKind,
+) {
+    if parser.token == token::Eof && e.message().ends_with(", found `<eof>`") {
+        if !e.span.is_dummy() {
+            // early end of macro arm (#52866)
+            e.replace_span_with(parser.sess.source_map().next_point(parser.token.span));
+        }
+        let msg = &e.message[0];
+        e.message[0] = (
+            format!(
+                "macro expansion ends with an incomplete expression: {}",
+                msg.0.replace(", found `<eof>`", ""),
+            ),
+            msg.1,
+        );
+    }
+    if e.span.is_dummy() {
+        // Get around lack of span in error (#30128)
+        e.replace_span_with(site_span);
+        if !parser.sess.source_map().is_imported(arm_span) {
+            e.span_label(arm_span, "in this macro arm");
+        }
+    } else if parser.sess.source_map().is_imported(parser.token.span) {
+        e.span_label(site_span, "in this macro invocation");
+    }
+    match kind {
+        AstFragmentKind::Pat if macro_ident.name == sym::vec => {
+            suggest_slice_pat(&mut e, site_span, parser);
+        }
+        _ => annotate_err_with_kind(&mut e, kind, site_span),
+    };
+    e.emit();
+}
+
 impl<'a> ParserAnyMacro<'a> {
     crate fn make(mut self: Box<ParserAnyMacro<'a>>, kind: AstFragmentKind) -> AstFragment {
         let ParserAnyMacro { site_span, macro_ident, ref mut parser, arm_span } = *self;
-        let fragment = panictry!(parse_ast_fragment(parser, kind).map_err(|mut e| {
-            if parser.token == token::Eof && e.message().ends_with(", found `<eof>`") {
-                if !e.span.is_dummy() {
-                    // early end of macro arm (#52866)
-                    e.replace_span_with(parser.sess.source_map().next_point(parser.token.span));
-                }
-                let msg = &e.message[0];
-                e.message[0] = (
-                    format!(
-                        "macro expansion ends with an incomplete expression: {}",
-                        msg.0.replace(", found `<eof>`", ""),
-                    ),
-                    msg.1,
-                );
+        let fragment = match parse_ast_fragment(parser, kind) {
+            Ok(f) => f,
+            Err(err) => {
+                emit_frag_parse_err(err, parser, site_span, macro_ident, arm_span, kind);
+                return kind.dummy(site_span);
             }
-            if e.span.is_dummy() {
-                // Get around lack of span in error (#30128)
-                e.replace_span_with(site_span);
-                if !parser.sess.source_map().is_imported(arm_span) {
-                    e.span_label(arm_span, "in this macro arm");
-                }
-            } else if parser.sess.source_map().is_imported(parser.token.span) {
-                e.span_label(site_span, "in this macro invocation");
-            }
-            match kind {
-                AstFragmentKind::Pat if macro_ident.name == sym::vec => {
-                    suggest_slice_pat(&mut e, site_span, parser);
-                }
-                _ => annotate_err_with_kind(&mut e, kind, site_span),
-            };
-            e
-        }));
+        };
 
         // We allow semicolons at the end of expressions -- e.g., the semicolon in
         // `macro_rules! m { () => { panic!(); } }` isn't parsed by `.parse_expr()`,
@@ -166,6 +181,14 @@ impl TTMacroExpander for MacroRulesMacroExpander {
     }
 }
 
+fn macro_rules_dummy_expander<'cx>(
+    _: &'cx mut ExtCtxt<'_>,
+    span: Span,
+    _: TokenStream,
+) -> Box<dyn MacResult + 'cx> {
+    DummyResult::any(span)
+}
+
 fn trace_macros_note(cx_expansions: &mut FxHashMap<Span, Vec<String>>, sp: Span, message: String) {
     let sp = sp.macro_backtrace().last().map(|trace| trace.call_site).unwrap_or(sp);
     cx_expansions.entry(sp).or_default().push(message);
@@ -240,7 +263,13 @@ fn generic_extension<'cx>(
 
                 let rhs_spans = rhs.iter().map(|t| t.span()).collect::<Vec<_>>();
                 // rhs has holes ( `$id` and `$(...)` that need filled)
-                let mut tts = transcribe(cx, &named_matches, rhs, transparency);
+                let mut tts = match transcribe(cx, &named_matches, rhs, transparency) {
+                    Ok(tts) => tts,
+                    Err(mut err) => {
+                        err.emit();
+                        return DummyResult::any(arm_span);
+                    }
+                };
 
                 // Replace all the tokens for the corresponding positions in the macro, to maintain
                 // proper positions in error reporting, while maintaining the macro_backtrace.
@@ -284,7 +313,12 @@ fn generic_extension<'cx>(
                 Some((ref best_token, _)) if best_token.span.lo() >= token.span.lo() => {}
                 _ => best_failure = Some((token, msg)),
             },
-            Error(err_sp, ref msg) => cx.span_fatal(err_sp.substitute_dummy(sp), &msg[..]),
+            Error(err_sp, ref msg) => {
+                let span = err_sp.substitute_dummy(sp);
+                cx.struct_span_err(span, &msg).emit();
+                return DummyResult::any(span);
+            }
+            ErrorReported => return DummyResult::any(sp),
         }
 
         // The matcher was not `Success(..)`ful.
@@ -344,6 +378,18 @@ pub fn compile_declarative_macro(
     def: &ast::Item,
     edition: Edition,
 ) -> SyntaxExtension {
+    let mk_syn_ext = |expander| {
+        SyntaxExtension::new(
+            sess,
+            SyntaxExtensionKind::LegacyBang(expander),
+            def.span,
+            Vec::new(),
+            edition,
+            def.ident.name,
+            &def.attrs,
+        )
+    };
+
     let diag = &sess.span_diagnostic;
     let lhs_nm = ast::Ident::new(sym::lhs, def.span);
     let rhs_nm = ast::Ident::new(sym::rhs, def.span);
@@ -398,13 +444,15 @@ pub fn compile_declarative_macro(
         Failure(token, msg) => {
             let s = parse_failure_msg(&token);
             let sp = token.span.substitute_dummy(def.span);
-            let mut err = sess.span_diagnostic.struct_span_fatal(sp, &s);
-            err.span_label(sp, msg);
-            err.emit();
-            FatalError.raise();
+            sess.span_diagnostic.struct_span_err(sp, &s).span_label(sp, msg).emit();
+            return mk_syn_ext(Box::new(macro_rules_dummy_expander));
+        }
+        Error(sp, msg) => {
+            sess.span_diagnostic.struct_span_err(sp.substitute_dummy(def.span), &msg).emit();
+            return mk_syn_ext(Box::new(macro_rules_dummy_expander));
         }
-        Error(sp, s) => {
-            sess.span_diagnostic.span_fatal(sp.substitute_dummy(def.span), &s).raise();
+        ErrorReported => {
+            return mk_syn_ext(Box::new(macro_rules_dummy_expander));
         }
     };
 
@@ -467,24 +515,14 @@ pub fn compile_declarative_macro(
         None => {}
     }
 
-    let expander: Box<_> = Box::new(MacroRulesMacroExpander {
+    mk_syn_ext(Box::new(MacroRulesMacroExpander {
         name: def.ident,
         span: def.span,
         transparency,
         lhses,
         rhses,
         valid,
-    });
-
-    SyntaxExtension::new(
-        sess,
-        SyntaxExtensionKind::LegacyBang(expander),
-        def.span,
-        Vec::new(),
-        edition,
-        def.ident.name,
-        &def.attrs,
-    )
+    }))
 }
 
 fn check_lhs_nt_follows(
diff --git a/src/librustc_expand/mbe/transcribe.rs b/src/librustc_expand/mbe/transcribe.rs
index 1b1093c9529f4..e2d3d5c4d644e 100644
--- a/src/librustc_expand/mbe/transcribe.rs
+++ b/src/librustc_expand/mbe/transcribe.rs
@@ -8,7 +8,7 @@ use rustc_ast::token::{self, NtTT, Token};
 use rustc_ast::tokenstream::{DelimSpan, TokenStream, TokenTree, TreeAndJoint};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::Lrc;
-use rustc_errors::pluralize;
+use rustc_errors::{pluralize, PResult};
 use rustc_span::hygiene::{ExpnId, Transparency};
 use rustc_span::symbol::MacroRulesNormalizedIdent;
 use rustc_span::Span;
@@ -80,15 +80,15 @@ impl Iterator for Frame {
 /// `transcribe` would return a `TokenStream` containing `println!("{}", stringify!(bar));`.
 ///
 /// Along the way, we do some additional error checking.
-pub(super) fn transcribe(
-    cx: &ExtCtxt<'_>,
+pub(super) fn transcribe<'a>(
+    cx: &ExtCtxt<'a>,
     interp: &FxHashMap<MacroRulesNormalizedIdent, NamedMatch>,
     src: Vec<mbe::TokenTree>,
     transparency: Transparency,
-) -> TokenStream {
+) -> PResult<'a, TokenStream> {
     // Nothing for us to transcribe...
     if src.is_empty() {
-        return TokenStream::default();
+        return Ok(TokenStream::default());
     }
 
     // We descend into the RHS (`src`), expanding things as we go. This stack contains the things
@@ -152,7 +152,7 @@ pub(super) fn transcribe(
                 Frame::Delimited { forest, span, .. } => {
                     if result_stack.is_empty() {
                         // No results left to compute! We are back at the top-level.
-                        return TokenStream::new(result);
+                        return Ok(TokenStream::new(result));
                     }
 
                     // Step back into the parent Delimited.
@@ -173,11 +173,11 @@ pub(super) fn transcribe(
             seq @ mbe::TokenTree::Sequence(..) => {
                 match lockstep_iter_size(&seq, interp, &repeats) {
                     LockstepIterSize::Unconstrained => {
-                        cx.span_fatal(
+                        return Err(cx.struct_span_err(
                             seq.span(), /* blame macro writer */
                             "attempted to repeat an expression containing no syntax variables \
                              matched as repeating at this depth",
-                        );
+                        ));
                     }
 
                     LockstepIterSize::Contradiction(ref msg) => {
@@ -185,7 +185,7 @@ pub(super) fn transcribe(
                         // happens when two meta-variables are used in the same repetition in a
                         // sequence, but they come from different sequence matchers and repeat
                         // different amounts.
-                        cx.span_fatal(seq.span(), &msg[..]);
+                        return Err(cx.struct_span_err(seq.span(), &msg[..]));
                     }
 
                     LockstepIterSize::Constraint(len, _) => {
@@ -203,7 +203,10 @@ pub(super) fn transcribe(
                                 // FIXME: this really ought to be caught at macro definition
                                 // time... It happens when the Kleene operator in the matcher and
                                 // the body for the same meta-variable do not match.
-                                cx.span_fatal(sp.entire(), "this must repeat at least once");
+                                return Err(cx.struct_span_err(
+                                    sp.entire(),
+                                    "this must repeat at least once",
+                                ));
                             }
                         } else {
                             // 0 is the initial counter (we have done 0 repretitions so far). `len`
@@ -242,10 +245,10 @@ pub(super) fn transcribe(
                         }
                     } else {
                         // We were unable to descend far enough. This is an error.
-                        cx.span_fatal(
+                        return Err(cx.struct_span_err(
                             sp, /* blame the macro writer */
                             &format!("variable '{}' is still repeating at this depth", ident),
-                        );
+                        ));
                     }
                 } else {
                     // If we aren't able to match the meta-var, we push it back into the result but
diff --git a/src/librustc_expand/proc_macro.rs b/src/librustc_expand/proc_macro.rs
index cb9afa4cd4f02..df7bf9438c3d0 100644
--- a/src/librustc_expand/proc_macro.rs
+++ b/src/librustc_expand/proc_macro.rs
@@ -5,7 +5,7 @@ use rustc_ast::ast::{self, ItemKind, MetaItemKind, NestedMetaItem};
 use rustc_ast::token;
 use rustc_ast::tokenstream::{self, TokenStream};
 use rustc_data_structures::sync::Lrc;
-use rustc_errors::{Applicability, FatalError};
+use rustc_errors::{Applicability, ErrorReported};
 use rustc_span::symbol::sym;
 use rustc_span::{Span, DUMMY_SP};
 
@@ -21,21 +21,16 @@ impl base::ProcMacro for BangProcMacro {
         ecx: &'cx mut ExtCtxt<'_>,
         span: Span,
         input: TokenStream,
-    ) -> TokenStream {
+    ) -> Result<TokenStream, ErrorReported> {
         let server = proc_macro_server::Rustc::new(ecx);
-        match self.client.run(&EXEC_STRATEGY, server, input) {
-            Ok(stream) => stream,
-            Err(e) => {
-                let msg = "proc macro panicked";
-                let mut err = ecx.struct_span_fatal(span, msg);
-                if let Some(s) = e.as_str() {
-                    err.help(&format!("message: {}", s));
-                }
-
-                err.emit();
-                FatalError.raise();
+        self.client.run(&EXEC_STRATEGY, server, input).map_err(|e| {
+            let mut err = ecx.struct_span_err(span, "proc macro panicked");
+            if let Some(s) = e.as_str() {
+                err.help(&format!("message: {}", s));
             }
-        }
+            err.emit();
+            ErrorReported
+        })
     }
 }
 
@@ -50,21 +45,16 @@ impl base::AttrProcMacro for AttrProcMacro {
         span: Span,
         annotation: TokenStream,
         annotated: TokenStream,
-    ) -> TokenStream {
+    ) -> Result<TokenStream, ErrorReported> {
         let server = proc_macro_server::Rustc::new(ecx);
-        match self.client.run(&EXEC_STRATEGY, server, annotation, annotated) {
-            Ok(stream) => stream,
-            Err(e) => {
-                let msg = "custom attribute panicked";
-                let mut err = ecx.struct_span_fatal(span, msg);
-                if let Some(s) = e.as_str() {
-                    err.help(&format!("message: {}", s));
-                }
-
-                err.emit();
-                FatalError.raise();
+        self.client.run(&EXEC_STRATEGY, server, annotation, annotated).map_err(|e| {
+            let mut err = ecx.struct_span_err(span, "custom attribute panicked");
+            if let Some(s) = e.as_str() {
+                err.help(&format!("message: {}", s));
             }
-        }
+            err.emit();
+            ErrorReported
+        })
     }
 }
 
@@ -96,8 +86,7 @@ impl MultiItemModifier for ProcMacroDerive {
             | Annotatable::Expr(_) => {
                 ecx.span_err(
                     span,
-                    "proc-macro derives may only be \
-                                    applied to a struct, enum, or union",
+                    "proc-macro derives may only be applied to a struct, enum, or union",
                 );
                 return ExpandResult::Ready(Vec::new());
             }
@@ -107,8 +96,7 @@ impl MultiItemModifier for ProcMacroDerive {
             _ => {
                 ecx.span_err(
                     span,
-                    "proc-macro derives may only be \
-                                    applied to a struct, enum, or union",
+                    "proc-macro derives may only be applied to a struct, enum, or union",
                 );
                 return ExpandResult::Ready(Vec::new());
             }
@@ -121,20 +109,16 @@ impl MultiItemModifier for ProcMacroDerive {
         let stream = match self.client.run(&EXEC_STRATEGY, server, input) {
             Ok(stream) => stream,
             Err(e) => {
-                let msg = "proc-macro derive panicked";
-                let mut err = ecx.struct_span_fatal(span, msg);
+                let mut err = ecx.struct_span_err(span, "proc-macro derive panicked");
                 if let Some(s) = e.as_str() {
                     err.help(&format!("message: {}", s));
                 }
-
                 err.emit();
-                FatalError.raise();
+                return ExpandResult::Ready(vec![]);
             }
         };
 
         let error_count_before = ecx.parse_sess.span_diagnostic.err_count();
-        let msg = "proc-macro derive produced unparseable tokens";
-
         let mut parser =
             rustc_parse::stream_to_parser(ecx.parse_sess, stream, Some("proc-macro derive"));
         let mut items = vec![];
@@ -144,18 +128,15 @@ impl MultiItemModifier for ProcMacroDerive {
                 Ok(None) => break,
                 Ok(Some(item)) => items.push(Annotatable::Item(item)),
                 Err(mut err) => {
-                    // FIXME: handle this better
-                    err.cancel();
-                    ecx.struct_span_fatal(span, msg).emit();
-                    FatalError.raise();
+                    err.emit();
+                    break;
                 }
             }
         }
 
         // fail if there have been errors emitted
         if ecx.parse_sess.span_diagnostic.err_count() > error_count_before {
-            ecx.struct_span_fatal(span, msg).emit();
-            FatalError.raise();
+            ecx.struct_span_err(span, "proc-macro derive produced unparseable tokens").emit();
         }
 
         ExpandResult::Ready(items)
diff --git a/src/librustc_hir/hir_id.rs b/src/librustc_hir/hir_id.rs
index 6d2ec44576353..a11638a3bb24f 100644
--- a/src/librustc_hir/hir_id.rs
+++ b/src/librustc_hir/hir_id.rs
@@ -71,7 +71,7 @@ rustc_data_structures::impl_stable_hash_via_hash!(ItemLocalId);
 
 /// The `HirId` corresponding to `CRATE_NODE_ID` and `CRATE_DEF_INDEX`.
 pub const CRATE_HIR_ID: HirId =
-    HirId { owner: CRATE_DEF_INDEX, local_id: ItemLocalId::from_u32_const(0) };
+    HirId { owner: CRATE_DEF_INDEX, local_id: ItemLocalId::from_u32(0) };
 
 pub const DUMMY_HIR_ID: HirId = HirId { owner: CRATE_DEF_INDEX, local_id: DUMMY_ITEM_LOCAL_ID };
 
diff --git a/src/librustc_hir/intravisit.rs b/src/librustc_hir/intravisit.rs
index b13f1a91b0317..316b31f069855 100644
--- a/src/librustc_hir/intravisit.rs
+++ b/src/librustc_hir/intravisit.rs
@@ -127,6 +127,25 @@ pub trait Map<'hir> {
     fn impl_item(&self, id: ImplItemId) -> &'hir ImplItem<'hir>;
 }
 
+/// An erased version of `Map<'hir>`, using dynamic dispatch.
+/// NOTE: This type is effectively only usable with `NestedVisitorMap::None`.
+pub struct ErasedMap<'hir>(&'hir dyn Map<'hir>);
+
+impl<'hir> Map<'hir> for ErasedMap<'hir> {
+    fn body(&self, id: BodyId) -> &'hir Body<'hir> {
+        self.0.body(id)
+    }
+    fn item(&self, id: HirId) -> &'hir Item<'hir> {
+        self.0.item(id)
+    }
+    fn trait_item(&self, id: TraitItemId) -> &'hir TraitItem<'hir> {
+        self.0.trait_item(id)
+    }
+    fn impl_item(&self, id: ImplItemId) -> &'hir ImplItem<'hir> {
+        self.0.impl_item(id)
+    }
+}
+
 /// Specifies what nested things a visitor wants to visit. The most
 /// common choice is `OnlyBodies`, which will cause the visitor to
 /// visit fn bodies for fns that it encounters, but skip over nested
diff --git a/src/librustc_hir/lib.rs b/src/librustc_hir/lib.rs
index 45f806b53f50c..fa5c72b060dcf 100644
--- a/src/librustc_hir/lib.rs
+++ b/src/librustc_hir/lib.rs
@@ -3,7 +3,9 @@
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/hir.html
 
 #![feature(crate_visibility_modifier)]
+#![feature(const_if_match)]
 #![feature(const_fn)] // For the unsizing cast on `&[]`
+#![feature(const_panic)]
 #![feature(in_band_lifetimes)]
 #![feature(specialization)]
 #![recursion_limit = "256"]
diff --git a/src/librustc_incremental/persist/file_format.rs b/src/librustc_incremental/persist/file_format.rs
index 5c72b049d97e9..048a81b81bab3 100644
--- a/src/librustc_incremental/persist/file_format.rs
+++ b/src/librustc_incremental/persist/file_format.rs
@@ -14,8 +14,8 @@ use std::fs;
 use std::io::{self, Read};
 use std::path::Path;
 
-use rustc::session::config::nightly_options;
 use rustc_serialize::opaque::Encoder;
+use rustc_session::config::nightly_options;
 
 /// The first few bytes of files generated by incremental compilation.
 const FILE_MAGIC: &[u8] = b"RSIC";
diff --git a/src/librustc_incremental/persist/fs.rs b/src/librustc_incremental/persist/fs.rs
index 8548ad392d2dd..4926f726f3593 100644
--- a/src/librustc_incremental/persist/fs.rs
+++ b/src/librustc_incremental/persist/fs.rs
@@ -103,11 +103,11 @@
 //! unsupported file system and emit a warning in that case. This is not yet
 //! implemented.
 
-use rustc::session::{CrateDisambiguator, Session};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::{base_n, flock};
 use rustc_fs_util::{link_or_copy, LinkOrCopy};
+use rustc_session::{CrateDisambiguator, Session};
 
 use std::fs as std_fs;
 use std::io;
diff --git a/src/librustc_incremental/persist/load.rs b/src/librustc_incremental/persist/load.rs
index 6c57f79e1a7fb..8a11586250dec 100644
--- a/src/librustc_incremental/persist/load.rs
+++ b/src/librustc_incremental/persist/load.rs
@@ -1,12 +1,12 @@
 //! Code to save/load the dep-graph from files.
 
 use rustc::dep_graph::{PreviousDepGraph, SerializedDepGraph, WorkProduct, WorkProductId};
-use rustc::session::Session;
 use rustc::ty::query::OnDiskCache;
 use rustc::ty::TyCtxt;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_serialize::opaque::Decoder;
 use rustc_serialize::Decodable as RustcDecodable;
+use rustc_session::Session;
 use std::path::Path;
 
 use super::data::*;
diff --git a/src/librustc_incremental/persist/save.rs b/src/librustc_incremental/persist/save.rs
index 87f39dedd0273..b465a11c99c06 100644
--- a/src/librustc_incremental/persist/save.rs
+++ b/src/librustc_incremental/persist/save.rs
@@ -1,10 +1,10 @@
 use rustc::dep_graph::{DepGraph, DepKind, WorkProduct, WorkProductId};
-use rustc::session::Session;
 use rustc::ty::TyCtxt;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::join;
 use rustc_serialize::opaque::Encoder;
 use rustc_serialize::Encodable as RustcEncodable;
+use rustc_session::Session;
 use std::fs;
 use std::path::PathBuf;
 
diff --git a/src/librustc_incremental/persist/work_product.rs b/src/librustc_incremental/persist/work_product.rs
index b1861acec0426..aa3588b284b28 100644
--- a/src/librustc_incremental/persist/work_product.rs
+++ b/src/librustc_incremental/persist/work_product.rs
@@ -2,8 +2,8 @@
 
 use crate::persist::fs::*;
 use rustc::dep_graph::{WorkProduct, WorkProductFileKind, WorkProductId};
-use rustc::session::Session;
 use rustc_fs_util::link_or_copy;
+use rustc_session::Session;
 use std::fs as std_fs;
 use std::path::PathBuf;
 
diff --git a/src/librustc_index/lib.rs b/src/librustc_index/lib.rs
index 86dd1a29d0ce3..e8aa1a209e929 100644
--- a/src/librustc_index/lib.rs
+++ b/src/librustc_index/lib.rs
@@ -1,4 +1,7 @@
 #![feature(allow_internal_unstable)]
+#![feature(const_if_match)]
+#![feature(const_fn)]
+#![feature(const_panic)]
 #![feature(unboxed_closures)]
 #![feature(test)]
 #![feature(fn_traits)]
diff --git a/src/librustc_index/vec.rs b/src/librustc_index/vec.rs
index 7020939fa20b2..d8c67f6210c75 100644
--- a/src/librustc_index/vec.rs
+++ b/src/librustc_index/vec.rs
@@ -120,10 +120,10 @@ macro_rules! newtype_index {
         impl $type {
             $v const MAX_AS_U32: u32 = $max;
 
-            $v const MAX: Self = Self::from_u32_const($max);
+            $v const MAX: Self = Self::from_u32($max);
 
             #[inline]
-            $v fn from_usize(value: usize) -> Self {
+            $v const fn from_usize(value: usize) -> Self {
                 assert!(value <= ($max as usize));
                 unsafe {
                     Self::from_u32_unchecked(value as u32)
@@ -131,31 +131,13 @@ macro_rules! newtype_index {
             }
 
             #[inline]
-            $v fn from_u32(value: u32) -> Self {
+            $v const fn from_u32(value: u32) -> Self {
                 assert!(value <= $max);
                 unsafe {
                     Self::from_u32_unchecked(value)
                 }
             }
 
-            /// Hacky variant of `from_u32` for use in constants.
-            /// This version checks the "max" constraint by using an
-            /// invalid array dereference.
-            #[inline]
-            $v const fn from_u32_const(value: u32) -> Self {
-                // This will fail at const eval time unless `value <=
-                // max` is true (in which case we get the index 0).
-                // It will also fail at runtime, of course, but in a
-                // kind of wacky way.
-                let _ = ["out of range value used"][
-                    !(value <= $max) as usize
-                ];
-
-                unsafe {
-                    Self { private: value }
-                }
-            }
-
             #[inline]
             $v const unsafe fn from_u32_unchecked(value: u32) -> Self {
                 Self { private: value }
@@ -163,19 +145,19 @@ macro_rules! newtype_index {
 
             /// Extracts the value of this index as an integer.
             #[inline]
-            $v fn index(self) -> usize {
+            $v const fn index(self) -> usize {
                 self.as_usize()
             }
 
             /// Extracts the value of this index as a `u32`.
             #[inline]
-            $v fn as_u32(self) -> u32 {
+            $v const fn as_u32(self) -> u32 {
                 self.private
             }
 
             /// Extracts the value of this index as a `usize`.
             #[inline]
-            $v fn as_usize(self) -> usize {
+            $v const fn as_usize(self) -> usize {
                 self.as_u32() as usize
             }
         }
@@ -500,7 +482,7 @@ macro_rules! newtype_index {
                    const $name:ident = $constant:expr,
                    $($tokens:tt)*) => (
         $(#[doc = $doc])*
-        $v const $name: $type = $type::from_u32_const($constant);
+        $v const $name: $type = $type::from_u32($constant);
         $crate::newtype_index!(
             @derives      [$($derives,)*]
             @attrs        [$(#[$attrs])*]
diff --git a/src/librustc_infer/Cargo.toml b/src/librustc_infer/Cargo.toml
index 4f97fd82874ff..9ecd056430c20 100644
--- a/src/librustc_infer/Cargo.toml
+++ b/src/librustc_infer/Cargo.toml
@@ -18,6 +18,7 @@ rustc_errors = { path = "../librustc_errors" }
 rustc_hir = { path = "../librustc_hir" }
 rustc_index = { path = "../librustc_index" }
 rustc_macros = { path = "../librustc_macros" }
+rustc_session = { path = "../librustc_session" }
 rustc_span = { path = "../librustc_span" }
 rustc_target = { path = "../librustc_target" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
diff --git a/src/librustc_infer/infer/error_reporting/mod.rs b/src/librustc_infer/infer/error_reporting/mod.rs
index a544381f33da1..ebbfcb28db2f5 100644
--- a/src/librustc_infer/infer/error_reporting/mod.rs
+++ b/src/librustc_infer/infer/error_reporting/mod.rs
@@ -49,7 +49,7 @@ use super::lexical_region_resolve::RegionResolutionError;
 use super::region_constraints::GenericKind;
 use super::{InferCtxt, RegionVariableOrigin, SubregionOrigin, TypeTrace, ValuePairs};
 
-use crate::infer::{self, SuppressRegionErrors};
+use crate::infer;
 use crate::traits::error_reporting::report_object_safety_error;
 use crate::traits::{
     IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode,
@@ -372,17 +372,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         &self,
         region_scope_tree: &region::ScopeTree,
         errors: &Vec<RegionResolutionError<'tcx>>,
-        suppress: SuppressRegionErrors,
     ) {
-        debug!(
-            "report_region_errors(): {} errors to start, suppress = {:?}",
-            errors.len(),
-            suppress
-        );
-
-        if suppress.suppressed() {
-            return;
-        }
+        debug!("report_region_errors(): {} errors to start", errors.len());
 
         // try to pre-process the errors, which will group some of them
         // together into a `ProcessedErrors` group:
diff --git a/src/librustc_infer/infer/error_reporting/nice_region_error/different_lifetimes.rs b/src/librustc_infer/infer/error_reporting/nice_region_error/different_lifetimes.rs
index 1a09729ef6443..50b324c72278e 100644
--- a/src/librustc_infer/infer/error_reporting/nice_region_error/different_lifetimes.rs
+++ b/src/librustc_infer/infer/error_reporting/nice_region_error/different_lifetimes.rs
@@ -3,6 +3,8 @@
 
 use crate::infer::error_reporting::nice_region_error::util::AnonymousParamInfo;
 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
+use crate::infer::lexical_region_resolve::RegionResolutionError;
+use crate::infer::SubregionOrigin;
 use rustc::util::common::ErrorReported;
 
 use rustc_errors::struct_span_err;
@@ -47,6 +49,15 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
     pub(super) fn try_report_anon_anon_conflict(&self) -> Option<ErrorReported> {
         let (span, sub, sup) = self.regions()?;
 
+        if let Some(RegionResolutionError::ConcreteFailure(
+            SubregionOrigin::ReferenceOutlivesReferent(..),
+            ..,
+        )) = self.error
+        {
+            // This error doesn't make much sense in this case.
+            return None;
+        }
+
         // Determine whether the sub and sup consist of both anonymous (elided) regions.
         let anon_reg_sup = self.tcx().is_suitable_region(sup)?;
 
diff --git a/src/librustc_infer/infer/error_reporting/nice_region_error/mod.rs b/src/librustc_infer/infer/error_reporting/nice_region_error/mod.rs
index d8c314a0d2f1f..2357ee689d59e 100644
--- a/src/librustc_infer/infer/error_reporting/nice_region_error/mod.rs
+++ b/src/librustc_infer/infer/error_reporting/nice_region_error/mod.rs
@@ -17,12 +17,7 @@ mod util;
 
 impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
     pub fn try_report_nice_region_error(&self, error: &RegionResolutionError<'tcx>) -> bool {
-        if let Some(tables) = self.in_progress_tables {
-            let tables = tables.borrow();
-            NiceRegionError::new(self, error.clone(), Some(&tables)).try_report().is_some()
-        } else {
-            NiceRegionError::new(self, error.clone(), None).try_report().is_some()
-        }
+        NiceRegionError::new(self, error.clone()).try_report().is_some()
     }
 }
 
@@ -30,16 +25,11 @@ pub struct NiceRegionError<'cx, 'tcx> {
     infcx: &'cx InferCtxt<'cx, 'tcx>,
     error: Option<RegionResolutionError<'tcx>>,
     regions: Option<(Span, ty::Region<'tcx>, ty::Region<'tcx>)>,
-    tables: Option<&'cx ty::TypeckTables<'tcx>>,
 }
 
 impl<'cx, 'tcx> NiceRegionError<'cx, 'tcx> {
-    pub fn new(
-        infcx: &'cx InferCtxt<'cx, 'tcx>,
-        error: RegionResolutionError<'tcx>,
-        tables: Option<&'cx ty::TypeckTables<'tcx>>,
-    ) -> Self {
-        Self { infcx, error: Some(error), regions: None, tables }
+    pub fn new(infcx: &'cx InferCtxt<'cx, 'tcx>, error: RegionResolutionError<'tcx>) -> Self {
+        Self { infcx, error: Some(error), regions: None }
     }
 
     pub fn new_from_span(
@@ -47,9 +37,8 @@ impl<'cx, 'tcx> NiceRegionError<'cx, 'tcx> {
         span: Span,
         sub: ty::Region<'tcx>,
         sup: ty::Region<'tcx>,
-        tables: Option<&'cx ty::TypeckTables<'tcx>>,
     ) -> Self {
-        Self { infcx, error: None, regions: Some((span, sub, sup)), tables }
+        Self { infcx, error: None, regions: Some((span, sub, sup)) }
     }
 
     fn tcx(&self) -> TyCtxt<'tcx> {
diff --git a/src/librustc_infer/infer/error_reporting/nice_region_error/util.rs b/src/librustc_infer/infer/error_reporting/nice_region_error/util.rs
index cab632935fd8e..de72c276595f7 100644
--- a/src/librustc_infer/infer/error_reporting/nice_region_error/util.rs
+++ b/src/librustc_infer/infer/error_reporting/nice_region_error/util.rs
@@ -51,52 +51,44 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         };
 
         let hir = &self.tcx().hir();
-        if let Some(hir_id) = hir.as_local_hir_id(id) {
-            if let Some(body_id) = hir.maybe_body_owned_by(hir_id) {
-                let body = hir.body(body_id);
-                let owner_id = hir.body_owner(body_id);
-                let fn_decl = hir.fn_decl_by_hir_id(owner_id).unwrap();
-                if let Some(tables) = self.tables {
-                    body.params
-                        .iter()
-                        .enumerate()
-                        .filter_map(|(index, param)| {
-                            // May return None; sometimes the tables are not yet populated.
-                            let ty_hir_id = fn_decl.inputs[index].hir_id;
-                            let param_ty_span = hir.span(ty_hir_id);
-                            let ty = tables.node_type_opt(param.hir_id)?;
-                            let mut found_anon_region = false;
-                            let new_param_ty = self.tcx().fold_regions(&ty, &mut false, |r, _| {
-                                if *r == *anon_region {
-                                    found_anon_region = true;
-                                    replace_region
-                                } else {
-                                    r
-                                }
-                            });
-                            if found_anon_region {
-                                let is_first = index == 0;
-                                Some(AnonymousParamInfo {
-                                    param,
-                                    param_ty: new_param_ty,
-                                    param_ty_span,
-                                    bound_region,
-                                    is_first,
-                                })
-                            } else {
-                                None
-                            }
-                        })
-                        .next()
+        let hir_id = hir.as_local_hir_id(id)?;
+        let body_id = hir.maybe_body_owned_by(hir_id)?;
+        let body = hir.body(body_id);
+        let owner_id = hir.body_owner(body_id);
+        let fn_decl = hir.fn_decl_by_hir_id(owner_id).unwrap();
+        let poly_fn_sig = self.tcx().fn_sig(id);
+        let fn_sig = self.tcx().liberate_late_bound_regions(id, &poly_fn_sig);
+        body.params
+            .iter()
+            .enumerate()
+            .filter_map(|(index, param)| {
+                // May return None; sometimes the tables are not yet populated.
+                let ty = fn_sig.inputs()[index];
+                let mut found_anon_region = false;
+                let new_param_ty = self.tcx().fold_regions(&ty, &mut false, |r, _| {
+                    if *r == *anon_region {
+                        found_anon_region = true;
+                        replace_region
+                    } else {
+                        r
+                    }
+                });
+                if found_anon_region {
+                    let ty_hir_id = fn_decl.inputs[index].hir_id;
+                    let param_ty_span = hir.span(ty_hir_id);
+                    let is_first = index == 0;
+                    Some(AnonymousParamInfo {
+                        param,
+                        param_ty: new_param_ty,
+                        param_ty_span,
+                        bound_region,
+                        is_first,
+                    })
                 } else {
                     None
                 }
-            } else {
-                None
-            }
-        } else {
-            None
-        }
+            })
+            .next()
     }
 
     // Here, we check for the case where the anonymous region
diff --git a/src/librustc_infer/infer/lexical_region_resolve/mod.rs b/src/librustc_infer/infer/lexical_region_resolve/mod.rs
index b7278ecd5e407..3af10e850d534 100644
--- a/src/librustc_infer/infer/lexical_region_resolve/mod.rs
+++ b/src/librustc_infer/infer/lexical_region_resolve/mod.rs
@@ -7,6 +7,7 @@ use crate::infer::region_constraints::RegionConstraintData;
 use crate::infer::region_constraints::VarInfos;
 use crate::infer::region_constraints::VerifyBound;
 use crate::infer::RegionVariableOrigin;
+use crate::infer::RegionckMode;
 use crate::infer::SubregionOrigin;
 use rustc::middle::free_region::RegionRelations;
 use rustc::ty::fold::TypeFoldable;
@@ -33,12 +34,29 @@ pub fn resolve<'tcx>(
     region_rels: &RegionRelations<'_, 'tcx>,
     var_infos: VarInfos,
     data: RegionConstraintData<'tcx>,
+    mode: RegionckMode,
 ) -> (LexicalRegionResolutions<'tcx>, Vec<RegionResolutionError<'tcx>>) {
     debug!("RegionConstraintData: resolve_regions()");
     let mut errors = vec![];
     let mut resolver = LexicalResolver { region_rels, var_infos, data };
-    let values = resolver.infer_variable_values(&mut errors);
-    (values, errors)
+    match mode {
+        RegionckMode::Solve => {
+            let values = resolver.infer_variable_values(&mut errors);
+            (values, errors)
+        }
+        RegionckMode::Erase { suppress_errors: false } => {
+            // Do real inference to get errors, then erase the results.
+            let mut values = resolver.infer_variable_values(&mut errors);
+            let re_erased = region_rels.tcx.lifetimes.re_erased;
+
+            values.values.iter_mut().for_each(|v| *v = VarValue::Value(re_erased));
+            (values, errors)
+        }
+        RegionckMode::Erase { suppress_errors: true } => {
+            // Skip region inference entirely.
+            (resolver.erased_data(region_rels.tcx), Vec::new())
+        }
+    }
 }
 
 /// Contains the result of lexical region resolution. Offers methods
@@ -163,6 +181,19 @@ impl<'cx, 'tcx> LexicalResolver<'cx, 'tcx> {
         }
     }
 
+    /// An erased version of the lexical region resolutions. Used when we're
+    /// erasing regions and suppressing errors: in item bodies with
+    /// `-Zborrowck=mir`.
+    fn erased_data(&self, tcx: TyCtxt<'tcx>) -> LexicalRegionResolutions<'tcx> {
+        LexicalRegionResolutions {
+            error_region: tcx.lifetimes.re_static,
+            values: IndexVec::from_elem_n(
+                VarValue::Value(tcx.lifetimes.re_erased),
+                self.num_vars(),
+            ),
+        }
+    }
+
     fn dump_constraints(&self, free_regions: &RegionRelations<'_, 'tcx>) {
         debug!("----() Start constraint listing (context={:?}) ()----", free_regions.context);
         for (idx, (constraint, _)) in self.data.constraints.iter().enumerate() {
diff --git a/src/librustc_infer/infer/mod.rs b/src/librustc_infer/infer/mod.rs
index 9ae131c568d0d..391fce946bf43 100644
--- a/src/librustc_infer/infer/mod.rs
+++ b/src/librustc_infer/infer/mod.rs
@@ -5,7 +5,6 @@ pub use self::LateBoundRegionConversionTime::*;
 pub use self::RegionVariableOrigin::*;
 pub use self::SubregionOrigin::*;
 pub use self::ValuePairs::*;
-pub use rustc::ty::IntVarValue;
 
 use crate::traits::{self, ObligationCause, PredicateObligations, TraitEngine};
 
@@ -16,15 +15,14 @@ use rustc::middle::free_region::RegionRelations;
 use rustc::middle::region;
 use rustc::mir;
 use rustc::mir::interpret::ConstEvalResult;
-use rustc::session::config::BorrowckMode;
 use rustc::traits::select;
 use rustc::ty::error::{ExpectedFound, TypeError, UnconstrainedNumeric};
 use rustc::ty::fold::{TypeFoldable, TypeFolder};
 use rustc::ty::relate::RelateResult;
 use rustc::ty::subst::{GenericArg, InternalSubsts, SubstsRef};
+pub use rustc::ty::IntVarValue;
 use rustc::ty::{self, GenericParamDefKind, InferConst, Ty, TyCtxt};
 use rustc::ty::{ConstVid, FloatVid, IntVid, TyVid};
-
 use rustc_ast::ast;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::sync::Lrc;
@@ -32,8 +30,10 @@ use rustc_data_structures::unify as ut;
 use rustc_errors::DiagnosticBuilder;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
+use rustc_session::config::BorrowckMode;
 use rustc_span::symbol::Symbol;
 use rustc_span::Span;
+
 use std::cell::{Cell, Ref, RefCell};
 use std::collections::BTreeMap;
 use std::fmt;
@@ -79,31 +79,50 @@ pub type Bound<T> = Option<T>;
 pub type UnitResult<'tcx> = RelateResult<'tcx, ()>; // "unify result"
 pub type FixupResult<'tcx, T> = Result<T, FixupError<'tcx>>; // "fixup result"
 
-/// A flag that is used to suppress region errors. This is normally
-/// false, but sometimes -- when we are doing region checks that the
-/// NLL borrow checker will also do -- it might be set to true.
-#[derive(Copy, Clone, Default, Debug)]
-pub struct SuppressRegionErrors {
-    suppressed: bool,
+/// How we should handle region solving.
+///
+/// This is used so that the region values inferred by HIR region solving are
+/// not exposed, and so that we can avoid doing work in HIR typeck that MIR
+/// typeck will also do.
+#[derive(Copy, Clone, Debug)]
+pub enum RegionckMode {
+    /// The default mode: report region errors, don't erase regions.
+    Solve,
+    /// Erase the results of region after solving.
+    Erase {
+        /// A flag that is used to suppress region errors, when we are doing
+        /// region checks that the NLL borrow checker will also do -- it might
+        /// be set to true.
+        suppress_errors: bool,
+    },
+}
+
+impl Default for RegionckMode {
+    fn default() -> Self {
+        RegionckMode::Solve
+    }
 }
 
-impl SuppressRegionErrors {
+impl RegionckMode {
     pub fn suppressed(self) -> bool {
-        self.suppressed
+        match self {
+            Self::Solve => false,
+            Self::Erase { suppress_errors } => suppress_errors,
+        }
     }
 
     /// Indicates that the MIR borrowck will repeat these region
     /// checks, so we should ignore errors if NLL is (unconditionally)
     /// enabled.
-    pub fn when_nll_is_enabled(tcx: TyCtxt<'_>) -> Self {
+    pub fn for_item_body(tcx: TyCtxt<'_>) -> Self {
         // FIXME(Centril): Once we actually remove `::Migrate` also make
         // this always `true` and then proceed to eliminate the dead code.
         match tcx.borrowck_mode() {
             // If we're on Migrate mode, report AST region errors
-            BorrowckMode::Migrate => SuppressRegionErrors { suppressed: false },
+            BorrowckMode::Migrate => RegionckMode::Erase { suppress_errors: false },
 
             // If we're on MIR, don't report AST region errors as they should be reported by NLL
-            BorrowckMode::Mir => SuppressRegionErrors { suppressed: true },
+            BorrowckMode::Mir => RegionckMode::Erase { suppress_errors: true },
         }
     }
 }
@@ -1207,20 +1226,13 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         region_context: DefId,
         region_map: &region::ScopeTree,
         outlives_env: &OutlivesEnvironment<'tcx>,
-        suppress: SuppressRegionErrors,
+        mode: RegionckMode,
     ) {
         assert!(
             self.is_tainted_by_errors() || self.inner.borrow().region_obligations.is_empty(),
             "region_obligations not empty: {:#?}",
             self.inner.borrow().region_obligations
         );
-
-        let region_rels = &RegionRelations::new(
-            self.tcx,
-            region_context,
-            region_map,
-            outlives_env.free_region_map(),
-        );
         let (var_infos, data) = self
             .inner
             .borrow_mut()
@@ -1228,8 +1240,16 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             .take()
             .expect("regions already resolved")
             .into_infos_and_data();
+
+        let region_rels = &RegionRelations::new(
+            self.tcx,
+            region_context,
+            region_map,
+            outlives_env.free_region_map(),
+        );
+
         let (lexical_region_resolutions, errors) =
-            lexical_region_resolve::resolve(region_rels, var_infos, data);
+            lexical_region_resolve::resolve(region_rels, var_infos, data, mode);
 
         let old_value = self.lexical_region_resolutions.replace(Some(lexical_region_resolutions));
         assert!(old_value.is_none());
@@ -1240,7 +1260,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             // this infcx was in use.  This is totally hokey but
             // otherwise we have a hard time separating legit region
             // errors from silly ones.
-            self.report_region_errors(region_map, &errors, suppress);
+            self.report_region_errors(region_map, &errors);
         }
     }
 
diff --git a/src/librustc_interface/interface.rs b/src/librustc_interface/interface.rs
index e15217dfa67e6..c5ebcf0696fba 100644
--- a/src/librustc_interface/interface.rs
+++ b/src/librustc_interface/interface.rs
@@ -1,10 +1,6 @@
 pub use crate::passes::BoxedResolver;
 use crate::util;
 
-use rustc::lint;
-use rustc::session::config::{self, ErrorOutputType, Input, OutputFilenames};
-use rustc::session::early_error;
-use rustc::session::{DiagnosticOutput, Session};
 use rustc::ty;
 use rustc::util::common::ErrorReported;
 use rustc_ast::ast::{self, MetaItemKind};
@@ -16,7 +12,11 @@ use rustc_data_structures::OnDrop;
 use rustc_errors::registry::Registry;
 use rustc_lint::LintStore;
 use rustc_parse::new_parser_from_source_str;
+use rustc_session::config::{self, ErrorOutputType, Input, OutputFilenames};
+use rustc_session::early_error;
+use rustc_session::lint;
 use rustc_session::parse::{CrateConfig, ParseSess};
+use rustc_session::{DiagnosticOutput, Session};
 use rustc_span::edition;
 use rustc_span::source_map::{FileLoader, FileName, SourceMap};
 use std::path::PathBuf;
diff --git a/src/librustc_interface/passes.rs b/src/librustc_interface/passes.rs
index 4fe7a06e5609e..4e8dea5e86a2e 100644
--- a/src/librustc_interface/passes.rs
+++ b/src/librustc_interface/passes.rs
@@ -6,13 +6,8 @@ use log::{info, log_enabled, warn};
 use rustc::arena::Arena;
 use rustc::dep_graph::DepGraph;
 use rustc::hir::map::Definitions;
-use rustc::lint;
 use rustc::middle;
 use rustc::middle::cstore::{CrateStore, MetadataLoader, MetadataLoaderDyn};
-use rustc::session::config::{self, CrateType, Input, OutputFilenames, OutputType};
-use rustc::session::config::{PpMode, PpSourceMode};
-use rustc::session::search_paths::PathKind;
-use rustc::session::Session;
 use rustc::ty::steal::Steal;
 use rustc::ty::{self, GlobalCtxt, ResolverOutputs, TyCtxt};
 use rustc::util::common::ErrorReported;
@@ -34,6 +29,11 @@ use rustc_parse::{parse_crate_from_file, parse_crate_from_source_str};
 use rustc_passes::{self, hir_stats, layout_test};
 use rustc_plugin_impl as plugin;
 use rustc_resolve::{Resolver, ResolverArenas};
+use rustc_session::config::{self, CrateType, Input, OutputFilenames, OutputType};
+use rustc_session::config::{PpMode, PpSourceMode};
+use rustc_session::lint;
+use rustc_session::search_paths::PathKind;
+use rustc_session::Session;
 use rustc_span::symbol::Symbol;
 use rustc_span::FileName;
 use rustc_trait_selection::traits;
@@ -306,6 +306,8 @@ fn configure_and_expand_inner<'a>(
             ecx.parse_sess.missing_fragment_specifiers.borrow().iter().cloned().collect();
         missing_fragment_specifiers.sort();
 
+        let recursion_limit_hit = ecx.reduced_recursion_limit.is_some();
+
         for span in missing_fragment_specifiers {
             let lint = lint::builtin::MISSING_FRAGMENT_SPECIFIER;
             let msg = "missing fragment specifier";
@@ -314,8 +316,15 @@ fn configure_and_expand_inner<'a>(
         if cfg!(windows) {
             env::set_var("PATH", &old_path);
         }
-        krate
-    });
+
+        if recursion_limit_hit {
+            // If we hit a recursion limit, exit early to avoid later passes getting overwhelmed
+            // with a large AST
+            Err(ErrorReported)
+        } else {
+            Ok(krate)
+        }
+    })?;
 
     sess.time("maybe_building_test_harness", || {
         rustc_builtin_macros::test_harness::inject(
diff --git a/src/librustc_interface/queries.rs b/src/librustc_interface/queries.rs
index 426d97cc09b92..3514829dca7f7 100644
--- a/src/librustc_interface/queries.rs
+++ b/src/librustc_interface/queries.rs
@@ -3,8 +3,6 @@ use crate::passes::{self, BoxedResolver, QueryContext};
 
 use rustc::arena::Arena;
 use rustc::dep_graph::DepGraph;
-use rustc::session::config::{OutputFilenames, OutputType};
-use rustc::session::Session;
 use rustc::ty::steal::Steal;
 use rustc::ty::{GlobalCtxt, ResolverOutputs};
 use rustc::util::common::ErrorReported;
@@ -15,6 +13,8 @@ use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_hir::Crate;
 use rustc_incremental::DepGraphFuture;
 use rustc_lint::LintStore;
+use rustc_session::config::{OutputFilenames, OutputType};
+use rustc_session::Session;
 use std::any::Any;
 use std::cell::{Ref, RefCell, RefMut};
 use std::mem;
diff --git a/src/librustc_interface/tests.rs b/src/librustc_interface/tests.rs
index 1b80cf4e3dbc2..db5ada9291435 100644
--- a/src/librustc_interface/tests.rs
+++ b/src/librustc_interface/tests.rs
@@ -2,16 +2,16 @@ extern crate getopts;
 
 use crate::interface::parse_cfgspecs;
 
-use rustc::lint::Level;
 use rustc::middle::cstore;
-use rustc::session::config::{build_configuration, build_session_options, to_crate_config};
-use rustc::session::config::{rustc_optgroups, ErrorOutputType, ExternLocation, Options, Passes};
-use rustc::session::config::{ExternEntry, LinkerPluginLto, LtoCli, SwitchWithOptPath};
-use rustc::session::config::{Externs, OutputType, OutputTypes, SymbolManglingVersion};
-use rustc::session::search_paths::SearchPath;
-use rustc::session::{build_session, Session};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{emitter::HumanReadableErrorType, registry, ColorConfig};
+use rustc_session::config::{build_configuration, build_session_options, to_crate_config};
+use rustc_session::config::{rustc_optgroups, ErrorOutputType, ExternLocation, Options, Passes};
+use rustc_session::config::{ExternEntry, LinkerPluginLto, LtoCli, SwitchWithOptPath};
+use rustc_session::config::{Externs, OutputType, OutputTypes, SymbolManglingVersion};
+use rustc_session::lint::Level;
+use rustc_session::search_paths::SearchPath;
+use rustc_session::{build_session, Session};
 use rustc_span::edition::{Edition, DEFAULT_EDITION};
 use rustc_span::symbol::sym;
 use rustc_target::spec::{MergeFunctions, PanicStrategy, RelroLevel};
diff --git a/src/librustc_interface/util.rs b/src/librustc_interface/util.rs
index 9521195a1b6c0..5c4de9e7155c6 100644
--- a/src/librustc_interface/util.rs
+++ b/src/librustc_interface/util.rs
@@ -1,5 +1,4 @@
 use log::info;
-use rustc::lint;
 use rustc::ty;
 use rustc_ast::ast::{AttrVec, BlockCheckMode};
 use rustc_ast::mut_visit::{visit_clobber, MutVisitor, *};
@@ -18,7 +17,7 @@ use rustc_metadata::dynamic_lib::DynamicLibrary;
 use rustc_resolve::{self, Resolver};
 use rustc_session as session;
 use rustc_session::config::{ErrorOutputType, Input, OutputFilenames};
-use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
+use rustc_session::lint::{self, BuiltinLintDiagnostics, LintBuffer};
 use rustc_session::parse::CrateConfig;
 use rustc_session::CrateDisambiguator;
 use rustc_session::{config, early_error, filesearch, DiagnosticOutput, Session};
diff --git a/src/librustc_lint/builtin.rs b/src/librustc_lint/builtin.rs
index 54b8fad393079..408031028b102 100644
--- a/src/librustc_lint/builtin.rs
+++ b/src/librustc_lint/builtin.rs
@@ -22,7 +22,6 @@
 //! `late_lint_methods!` invocation in `lib.rs`.
 
 use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
-use rustc::hir::map::Map;
 use rustc::lint::LintDiagnosticBuilder;
 use rustc::ty::{self, layout::VariantIdx, Ty, TyCtxt};
 use rustc_ast::ast::{self, Expr};
@@ -1071,7 +1070,7 @@ impl TypeAliasBounds {
             err: &'a mut DiagnosticBuilder<'db>,
         }
         impl<'a, 'db, 'v> Visitor<'v> for WalkAssocTypes<'a, 'db> {
-            type Map = Map<'v>;
+            type Map = intravisit::ErasedMap<'v>;
 
             fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
                 intravisit::NestedVisitorMap::None
diff --git a/src/librustc_metadata/Cargo.toml b/src/librustc_metadata/Cargo.toml
index a8e308c5c9e87..088cba83ef998 100644
--- a/src/librustc_metadata/Cargo.toml
+++ b/src/librustc_metadata/Cargo.toml
@@ -26,6 +26,7 @@ stable_deref_trait = "1.0.0"
 rustc_ast = { path = "../librustc_ast" }
 rustc_expand = { path = "../librustc_expand" }
 rustc_span = { path = "../librustc_span" }
+rustc_session = { path = "../librustc_session" }
 
 [target.'cfg(windows)'.dependencies]
 winapi = { version = "0.3", features = ["errhandlingapi", "libloaderapi"] }
diff --git a/src/librustc_metadata/creader.rs b/src/librustc_metadata/creader.rs
index 18b4c9ad5044c..9616e1249dc98 100644
--- a/src/librustc_metadata/creader.rs
+++ b/src/librustc_metadata/creader.rs
@@ -6,19 +6,18 @@ use crate::rmeta::{CrateDep, CrateMetadata, CrateNumMap, CrateRoot, MetadataBlob
 use rustc::hir::map::Definitions;
 use rustc::middle::cstore::DepKind;
 use rustc::middle::cstore::{CrateSource, ExternCrate, ExternCrateSource, MetadataLoaderDyn};
-use rustc::session::config;
-use rustc::session::search_paths::PathKind;
-use rustc::session::{CrateDisambiguator, Session};
 use rustc::ty::TyCtxt;
-use rustc_ast::ast;
-use rustc_ast::attr;
 use rustc_ast::expand::allocator::{global_allocator_spans, AllocatorKind};
+use rustc_ast::{ast, attr};
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::Lrc;
 use rustc_errors::struct_span_err;
 use rustc_expand::base::SyntaxExtension;
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_index::vec::IndexVec;
+use rustc_session::config;
+use rustc_session::search_paths::PathKind;
+use rustc_session::{CrateDisambiguator, Session};
 use rustc_span::edition::Edition;
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::{Span, DUMMY_SP};
diff --git a/src/librustc_metadata/dependency_format.rs b/src/librustc_metadata/dependency_format.rs
index 4a9a9ddc4bd0f..4cfaf03b7a5f6 100644
--- a/src/librustc_metadata/dependency_format.rs
+++ b/src/librustc_metadata/dependency_format.rs
@@ -56,10 +56,10 @@ use crate::creader::CStore;
 use rustc::middle::cstore::LinkagePreference::{self, RequireDynamic, RequireStatic};
 use rustc::middle::cstore::{self, DepKind};
 use rustc::middle::dependency_format::{Dependencies, DependencyList, Linkage};
-use rustc::session::config;
 use rustc::ty::TyCtxt;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def_id::CrateNum;
+use rustc_session::config;
 use rustc_target::spec::PanicStrategy;
 
 crate fn calculate(tcx: TyCtxt<'_>) -> Dependencies {
diff --git a/src/librustc_metadata/lib.rs b/src/librustc_metadata/lib.rs
index d4cc3c32616ac..e401dc0f6e7d4 100644
--- a/src/librustc_metadata/lib.rs
+++ b/src/librustc_metadata/lib.rs
@@ -31,7 +31,7 @@ pub mod dynamic_lib;
 pub mod locator;
 
 pub fn validate_crate_name(
-    sess: Option<&rustc::session::Session>,
+    sess: Option<&rustc_session::Session>,
     s: &str,
     sp: Option<rustc_span::Span>,
 ) {
diff --git a/src/librustc_metadata/locator.rs b/src/librustc_metadata/locator.rs
index efa259d0c4e0d..1ede629e7ef7d 100644
--- a/src/librustc_metadata/locator.rs
+++ b/src/librustc_metadata/locator.rs
@@ -216,13 +216,13 @@ use crate::creader::Library;
 use crate::rmeta::{rustc_version, MetadataBlob, METADATA_HEADER};
 
 use rustc::middle::cstore::{CrateSource, MetadataLoader};
-use rustc::session::filesearch::{FileDoesntMatch, FileMatches, FileSearch};
-use rustc::session::search_paths::PathKind;
-use rustc::session::{config, CrateDisambiguator, Session};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::MetadataRef;
 use rustc_errors::{struct_span_err, DiagnosticBuilder};
+use rustc_session::filesearch::{FileDoesntMatch, FileMatches, FileSearch};
+use rustc_session::search_paths::PathKind;
+use rustc_session::{config, CrateDisambiguator, Session};
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::Span;
 use rustc_target::spec::{Target, TargetTriple};
diff --git a/src/librustc_metadata/native_libs.rs b/src/librustc_metadata/native_libs.rs
index 2fa9cb099dd51..64bbf393ba0f1 100644
--- a/src/librustc_metadata/native_libs.rs
+++ b/src/librustc_metadata/native_libs.rs
@@ -1,12 +1,12 @@
 use rustc::middle::cstore::{self, NativeLibrary};
-use rustc::session::parse::feature_err;
-use rustc::session::Session;
 use rustc::ty::TyCtxt;
 use rustc_attr as attr;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::itemlikevisit::ItemLikeVisitor;
+use rustc_session::parse::feature_err;
+use rustc_session::Session;
 use rustc_span::source_map::Span;
 use rustc_span::symbol::{kw, sym, Symbol};
 use rustc_target::spec::abi::Abi;
diff --git a/src/librustc_metadata/rmeta/decoder.rs b/src/librustc_metadata/rmeta/decoder.rs
index 5b7d89243c35f..cf0f881605866 100644
--- a/src/librustc_metadata/rmeta/decoder.rs
+++ b/src/librustc_metadata/rmeta/decoder.rs
@@ -14,36 +14,35 @@ use rustc::middle::exported_symbols::{ExportedSymbol, SymbolExportLevel};
 use rustc::middle::lang_items;
 use rustc::mir::interpret::{AllocDecodingSession, AllocDecodingState};
 use rustc::mir::{self, interpret, BodyAndCache, Promoted};
-use rustc::session::Session;
 use rustc::ty::codec::TyDecoder;
 use rustc::ty::{self, Ty, TyCtxt};
 use rustc::util::common::record_time;
+use rustc_ast::ast::{self, Ident};
+use rustc_attr as attr;
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::{AtomicCell, Lock, LockGuard, Lrc, Once};
+use rustc_expand::base::{SyntaxExtension, SyntaxExtensionKind};
+use rustc_expand::proc_macro::{AttrProcMacro, BangProcMacro, ProcMacroDerive};
 use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
 use rustc_hir::def_id::{CrateNum, DefId, DefIndex, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_index::vec::{Idx, IndexVec};
+use rustc_serialize::{opaque, Decodable, Decoder, SpecializedDecoder};
+use rustc_session::Session;
+use rustc_span::source_map::{self, respan, Spanned};
+use rustc_span::symbol::{sym, Symbol};
+use rustc_span::{self, hygiene::MacroKind, BytePos, Pos, Span, DUMMY_SP};
 
+use log::debug;
+use proc_macro::bridge::client::ProcMacro;
 use std::io;
 use std::mem;
 use std::num::NonZeroUsize;
 use std::u32;
 
-use log::debug;
-use proc_macro::bridge::client::ProcMacro;
-use rustc_ast::ast::{self, Ident};
-use rustc_attr as attr;
-use rustc_expand::base::{SyntaxExtension, SyntaxExtensionKind};
-use rustc_expand::proc_macro::{AttrProcMacro, BangProcMacro, ProcMacroDerive};
-use rustc_serialize::{opaque, Decodable, Decoder, SpecializedDecoder};
-use rustc_span::source_map::{self, respan, Spanned};
-use rustc_span::symbol::{sym, Symbol};
-use rustc_span::{self, hygiene::MacroKind, BytePos, Pos, Span, DUMMY_SP};
-
 pub use cstore_impl::{provide, provide_extern};
 
 mod cstore_impl;
diff --git a/src/librustc_metadata/rmeta/decoder/cstore_impl.rs b/src/librustc_metadata/rmeta/decoder/cstore_impl.rs
index d87e24eeed173..cc2bd51f92f3e 100644
--- a/src/librustc_metadata/rmeta/decoder/cstore_impl.rs
+++ b/src/librustc_metadata/rmeta/decoder/cstore_impl.rs
@@ -10,7 +10,6 @@ use rustc::hir::map::{DefKey, DefPath, DefPathHash};
 use rustc::middle::cstore::{CrateSource, CrateStore, EncodedMetadata, NativeLibraryKind};
 use rustc::middle::exported_symbols::ExportedSymbol;
 use rustc::middle::stability::DeprecationEntry;
-use rustc::session::{CrateDisambiguator, Session};
 use rustc::ty::query::Providers;
 use rustc::ty::query::QueryConfig;
 use rustc::ty::{self, TyCtxt};
@@ -20,6 +19,7 @@ use rustc_ast::expand::allocator::AllocatorKind;
 use rustc_data_structures::svh::Svh;
 use rustc_hir as hir;
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, CRATE_DEF_INDEX, LOCAL_CRATE};
+use rustc_session::{CrateDisambiguator, Session};
 use rustc_span::source_map::{self, Span, Spanned};
 use rustc_span::symbol::Symbol;
 
diff --git a/src/librustc_metadata/rmeta/encoder.rs b/src/librustc_metadata/rmeta/encoder.rs
index 4c8e07c223bd3..90179520a6233 100644
--- a/src/librustc_metadata/rmeta/encoder.rs
+++ b/src/librustc_metadata/rmeta/encoder.rs
@@ -12,33 +12,31 @@ use rustc::traits::specialization_graph;
 use rustc::ty::codec::{self as ty_codec, TyEncoder};
 use rustc::ty::layout::VariantIdx;
 use rustc::ty::{self, SymbolName, Ty, TyCtxt};
+use rustc_ast::ast;
+use rustc_ast::attr;
 use rustc_data_structures::fingerprint::Fingerprint;
+use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::stable_hasher::StableHasher;
+use rustc_data_structures::sync::Lrc;
+use rustc_hir as hir;
 use rustc_hir::def::CtorKind;
 use rustc_hir::def_id::{CrateNum, DefId, DefIndex, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE};
+use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
+use rustc_hir::itemlikevisit::ItemLikeVisitor;
 use rustc_hir::{AnonConst, GenericParamKind};
 use rustc_index::vec::Idx;
-
-use rustc::session::config::{self, CrateType};
-use rustc_data_structures::fx::FxHashMap;
-use rustc_data_structures::stable_hasher::StableHasher;
-use rustc_data_structures::sync::Lrc;
 use rustc_serialize::{opaque, Encodable, Encoder, SpecializedEncoder};
-
-use log::{debug, trace};
-use rustc_ast::ast;
-use rustc_ast::attr;
+use rustc_session::config::{self, CrateType};
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{self, FileName, SourceFile, Span};
+
+use log::{debug, trace};
 use std::hash::Hash;
 use std::num::NonZeroUsize;
 use std::path::Path;
 use std::u32;
 
-use rustc_hir as hir;
-use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
-use rustc_hir::itemlikevisit::ItemLikeVisitor;
-
 struct EncodeContext<'tcx> {
     opaque: opaque::Encoder,
     tcx: TyCtxt<'tcx>,
diff --git a/src/librustc_metadata/rmeta/mod.rs b/src/librustc_metadata/rmeta/mod.rs
index e2d8d5466bd3e..defa306b6d6fe 100644
--- a/src/librustc_metadata/rmeta/mod.rs
+++ b/src/librustc_metadata/rmeta/mod.rs
@@ -7,8 +7,6 @@ use rustc::middle::cstore::{DepKind, ForeignModule, LinkagePreference, NativeLib
 use rustc::middle::exported_symbols::{ExportedSymbol, SymbolExportLevel};
 use rustc::middle::lang_items;
 use rustc::mir;
-use rustc::session::config::SymbolManglingVersion;
-use rustc::session::CrateDisambiguator;
 use rustc::ty::{self, ReprOptions, Ty};
 use rustc_ast::ast::{self, MacroDef};
 use rustc_attr as attr;
@@ -19,6 +17,8 @@ use rustc_hir::def::CtorKind;
 use rustc_hir::def_id::{DefId, DefIndex};
 use rustc_index::vec::IndexVec;
 use rustc_serialize::opaque::Encoder;
+use rustc_session::config::SymbolManglingVersion;
+use rustc_session::CrateDisambiguator;
 use rustc_span::edition::Edition;
 use rustc_span::symbol::Symbol;
 use rustc_span::{self, Span};
diff --git a/src/librustc_mir/Cargo.toml b/src/librustc_mir/Cargo.toml
index cad50d50f3cec..256a80076b923 100644
--- a/src/librustc_mir/Cargo.toml
+++ b/src/librustc_mir/Cargo.toml
@@ -27,6 +27,7 @@ rustc_infer = { path = "../librustc_infer" }
 rustc_lexer = { path = "../librustc_lexer" }
 rustc_macros = { path = "../librustc_macros" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
+rustc_session = { path = "../librustc_session" }
 rustc_target = { path = "../librustc_target" }
 rustc_trait_selection = { path = "../librustc_trait_selection" }
 rustc_ast = { path = "../librustc_ast" }
diff --git a/src/librustc_mir/borrow_check/diagnostics/region_errors.rs b/src/librustc_mir/borrow_check/diagnostics/region_errors.rs
index f751a16cfce7c..494b6421fd5d4 100644
--- a/src/librustc_mir/borrow_check/diagnostics/region_errors.rs
+++ b/src/librustc_mir/borrow_check/diagnostics/region_errors.rs
@@ -284,8 +284,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         debug!("report_region_error: category={:?} {:?}", category, span);
         // Check if we can use one of the "nice region errors".
         if let (Some(f), Some(o)) = (self.to_error_region(fr), self.to_error_region(outlived_fr)) {
-            let tables = self.infcx.tcx.typeck_tables_of(self.mir_def_id);
-            let nice = NiceRegionError::new_from_span(self.infcx, span, o, f, Some(tables));
+            let nice = NiceRegionError::new_from_span(self.infcx, span, o, f);
             if let Some(diag) = nice.try_report_from_nll() {
                 diag.buffer(&mut self.errors_buffer);
                 return;
diff --git a/src/librustc_mir/borrow_check/mod.rs b/src/librustc_mir/borrow_check/mod.rs
index a61d00b0120cb..6c1901455fda9 100644
--- a/src/librustc_mir/borrow_check/mod.rs
+++ b/src/librustc_mir/borrow_check/mod.rs
@@ -1,7 +1,5 @@
 //! This query borrow-checks the MIR to (further) ensure it is not broken.
 
-use rustc::lint::builtin::MUTABLE_BORROW_RESERVATION_CONFLICT;
-use rustc::lint::builtin::UNUSED_MUT;
 use rustc::mir::{
     read_only, traversal, Body, BodyAndCache, ClearCrossCrate, Local, Location, Mutability,
     Operand, Place, PlaceElem, PlaceRef, ReadOnlyBodyAndCache,
@@ -11,7 +9,7 @@ use rustc::mir::{Field, ProjectionElem, Promoted, Rvalue, Statement, StatementKi
 use rustc::mir::{Terminator, TerminatorKind};
 use rustc::ty::query::Providers;
 use rustc::ty::{self, RegionVid, TyCtxt};
-
+use rustc_ast::ast::Name;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::graph::dominators::Dominators;
 use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder};
@@ -20,6 +18,8 @@ use rustc_hir::{def_id::DefId, HirId, Node};
 use rustc_index::bit_set::BitSet;
 use rustc_index::vec::IndexVec;
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
+use rustc_session::lint::builtin::{MUTABLE_BORROW_RESERVATION_CONFLICT, UNUSED_MUT};
+use rustc_span::{Span, DUMMY_SP};
 
 use either::Either;
 use smallvec::SmallVec;
@@ -28,9 +28,6 @@ use std::collections::BTreeMap;
 use std::mem;
 use std::rc::Rc;
 
-use rustc_ast::ast::Name;
-use rustc_span::{Span, DUMMY_SP};
-
 use crate::dataflow;
 use crate::dataflow::generic::{Analysis, BorrowckFlowState as Flows, BorrowckResults};
 use crate::dataflow::indexes::{BorrowIndex, InitIndex, MoveOutIndex, MovePathIndex};
diff --git a/src/librustc_mir/const_eval/machine.rs b/src/librustc_mir/const_eval/machine.rs
index bb661d3d2a30a..28889486c383b 100644
--- a/src/librustc_mir/const_eval/machine.rs
+++ b/src/librustc_mir/const_eval/machine.rs
@@ -240,7 +240,8 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
         Ok(Some(match ecx.load_mir(instance.def, None) {
             Ok(body) => *body,
             Err(err) => {
-                if let err_unsup!(NoMirFor(ref path)) = err.kind {
+                if let err_unsup!(NoMirFor(did)) = err.kind {
+                    let path = ecx.tcx.def_path_str(did);
                     return Err(ConstEvalErrKind::NeedsRfc(format!(
                         "calling extern function `{}`",
                         path
diff --git a/src/librustc_mir/dataflow/mod.rs b/src/librustc_mir/dataflow/mod.rs
index b4e33b9502e69..dd0f9ff75b9fe 100644
--- a/src/librustc_mir/dataflow/mod.rs
+++ b/src/librustc_mir/dataflow/mod.rs
@@ -1,16 +1,14 @@
+use rustc::mir::traversal;
+use rustc::mir::{self, BasicBlock, BasicBlockData, Body, Location, Statement, Terminator};
+use rustc::ty::{self, TyCtxt};
 use rustc_ast::ast::{self, MetaItem};
 use rustc_ast_pretty::pprust;
-use rustc_span::symbol::{sym, Symbol};
-
 use rustc_data_structures::work_queue::WorkQueue;
+use rustc_hir::def_id::DefId;
 use rustc_index::bit_set::{BitSet, HybridBitSet};
 use rustc_index::vec::Idx;
-
-use rustc::mir::traversal;
-use rustc::mir::{self, BasicBlock, BasicBlockData, Body, Location, Statement, Terminator};
-use rustc::session::Session;
-use rustc::ty::{self, TyCtxt};
-use rustc_hir::def_id::DefId;
+use rustc_session::Session;
+use rustc_span::symbol::{sym, Symbol};
 
 use std::borrow::Borrow;
 use std::fmt;
diff --git a/src/librustc_mir/interpret/eval_context.rs b/src/librustc_mir/interpret/eval_context.rs
index 450e6b2e2d611..481719bfa8e63 100644
--- a/src/librustc_mir/interpret/eval_context.rs
+++ b/src/librustc_mir/interpret/eval_context.rs
@@ -138,7 +138,7 @@ pub enum LocalValue<Tag = (), Id = AllocId> {
 impl<'tcx, Tag: Copy + 'static> LocalState<'tcx, Tag> {
     pub fn access(&self) -> InterpResult<'tcx, Operand<Tag>> {
         match self.value {
-            LocalValue::Dead => throw_unsup!(DeadLocal),
+            LocalValue::Dead => throw_ub!(DeadLocal),
             LocalValue::Uninitialized => {
                 bug!("The type checker should prevent reading from a never-written local")
             }
@@ -152,7 +152,7 @@ impl<'tcx, Tag: Copy + 'static> LocalState<'tcx, Tag> {
         &mut self,
     ) -> InterpResult<'tcx, Result<&mut LocalValue<Tag>, MemPlace<Tag>>> {
         match self.value {
-            LocalValue::Dead => throw_unsup!(DeadLocal),
+            LocalValue::Dead => throw_ub!(DeadLocal),
             LocalValue::Live(Operand::Indirect(mplace)) => Ok(Err(mplace)),
             ref mut local @ LocalValue::Live(Operand::Immediate(_))
             | ref mut local @ LocalValue::Uninitialized => Ok(Ok(local)),
@@ -326,7 +326,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 if self.tcx.is_mir_available(did) {
                     Ok(self.tcx.optimized_mir(did).unwrap_read_only())
                 } else {
-                    throw_unsup!(NoMirFor(self.tcx.def_path_str(def_id)))
+                    throw_unsup!(NoMirFor(def_id))
                 }
             }
             _ => Ok(self.tcx.instance_mir(instance)),
diff --git a/src/librustc_mir/interpret/intern.rs b/src/librustc_mir/interpret/intern.rs
index 9b13db2289e7e..90b8a4932991e 100644
--- a/src/librustc_mir/interpret/intern.rs
+++ b/src/librustc_mir/interpret/intern.rs
@@ -327,7 +327,7 @@ pub fn intern_const_alloc_recursive<M: CompileTimeMachine<'mir, 'tcx>>(
         if let Err(error) = interned {
             // This can happen when e.g. the tag of an enum is not a valid discriminant. We do have
             // to read enum discriminants in order to find references in enum variant fields.
-            if let err_unsup!(ValidationFailure(_)) = error.kind {
+            if let err_ub!(ValidationFailure(_)) = error.kind {
                 let err = crate::const_eval::error_to_const_error(&ecx, error);
                 match err.struct_error(
                     ecx.tcx,
@@ -390,7 +390,7 @@ pub fn intern_const_alloc_recursive<M: CompileTimeMachine<'mir, 'tcx>>(
             }
         } else if ecx.memory.dead_alloc_map.contains_key(&alloc_id) {
             // dangling pointer
-            throw_unsup!(ValidationFailure("encountered dangling pointer in final constant".into()))
+            throw_ub_format!("encountered dangling pointer in final constant")
         } else if ecx.tcx.alloc_map.lock().get(alloc_id).is_none() {
             // We have hit an `AllocId` that is neither in local or global memory and isn't marked
             // as dangling by local memory.
diff --git a/src/librustc_mir/interpret/intrinsics.rs b/src/librustc_mir/interpret/intrinsics.rs
index 37a60bcc8368d..03aedad0d988d 100644
--- a/src/librustc_mir/interpret/intrinsics.rs
+++ b/src/librustc_mir/interpret/intrinsics.rs
@@ -135,7 +135,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 let bits = self.force_bits(val, layout_of.size)?;
                 let kind = match layout_of.abi {
                     ty::layout::Abi::Scalar(ref scalar) => scalar.value,
-                    _ => throw_unsup!(TypeNotPrimitive(ty)),
+                    _ => bug!("{} called on invalid type {:?}", intrinsic_name, ty),
                 };
                 let (nonzero, intrinsic_name) = match intrinsic_name {
                     sym::cttz_nonzero => (true, sym::cttz),
@@ -246,9 +246,9 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     let layout = self.layout_of(substs.type_at(0))?;
                     let r_val = self.force_bits(r.to_scalar()?, layout.size)?;
                     if let sym::unchecked_shl | sym::unchecked_shr = intrinsic_name {
-                        throw_ub_format!("Overflowing shift by {} in `{}`", r_val, intrinsic_name);
+                        throw_ub_format!("overflowing shift by {} in `{}`", r_val, intrinsic_name);
                     } else {
-                        throw_ub_format!("Overflow executing `{}`", intrinsic_name);
+                        throw_ub_format!("overflow executing `{}`", intrinsic_name);
                     }
                 }
                 self.write_scalar(val, dest)?;
diff --git a/src/librustc_mir/interpret/machine.rs b/src/librustc_mir/interpret/machine.rs
index 0e70e54ad85af..c9d32f6240037 100644
--- a/src/librustc_mir/interpret/machine.rs
+++ b/src/librustc_mir/interpret/machine.rs
@@ -286,8 +286,10 @@ pub trait Machine<'mir, 'tcx>: Sized {
         int: u64,
     ) -> InterpResult<'tcx, Pointer<Self::PointerTag>> {
         Err((if int == 0 {
-            err_unsup!(InvalidNullPointerUsage)
+            // This is UB, seriously.
+            err_ub!(InvalidIntPointerUsage(0))
         } else {
+            // This is just something we cannot support during const-eval.
             err_unsup!(ReadBytesAsPointer)
         })
         .into())
diff --git a/src/librustc_mir/interpret/memory.rs b/src/librustc_mir/interpret/memory.rs
index 82a467c7ba92c..5b2cd89a12284 100644
--- a/src/librustc_mir/interpret/memory.rs
+++ b/src/librustc_mir/interpret/memory.rs
@@ -215,7 +215,10 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         kind: MemoryKind<M::MemoryKinds>,
     ) -> InterpResult<'tcx, Pointer<M::PointerTag>> {
         if ptr.offset.bytes() != 0 {
-            throw_unsup!(ReallocateNonBasePtr)
+            throw_ub_format!(
+                "reallocating {:?} which does not point to the beginning of an object",
+                ptr
+            );
         }
 
         // For simplicities' sake, we implement reallocate as "alloc, copy, dealloc".
@@ -251,7 +254,10 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         trace!("deallocating: {}", ptr.alloc_id);
 
         if ptr.offset.bytes() != 0 {
-            throw_unsup!(DeallocateNonBasePtr)
+            throw_ub_format!(
+                "deallocating {:?} which does not point to the beginning of an object",
+                ptr
+            );
         }
 
         let (alloc_kind, mut alloc) = match self.alloc_map.remove(&ptr.alloc_id) {
@@ -259,29 +265,32 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             None => {
                 // Deallocating static memory -- always an error
                 return Err(match self.tcx.alloc_map.lock().get(ptr.alloc_id) {
-                    Some(GlobalAlloc::Function(..)) => err_unsup!(DeallocatedWrongMemoryKind(
-                        "function".to_string(),
-                        format!("{:?}", kind),
-                    )),
-                    Some(GlobalAlloc::Static(..)) | Some(GlobalAlloc::Memory(..)) => err_unsup!(
-                        DeallocatedWrongMemoryKind("static".to_string(), format!("{:?}", kind))
-                    ),
-                    None => err_unsup!(DoubleFree),
+                    Some(GlobalAlloc::Function(..)) => err_ub_format!("deallocating a function"),
+                    Some(GlobalAlloc::Static(..)) | Some(GlobalAlloc::Memory(..)) => {
+                        err_ub_format!("deallocating static memory")
+                    }
+                    None => err_ub!(PointerUseAfterFree(ptr.alloc_id)),
                 }
                 .into());
             }
         };
 
         if alloc_kind != kind {
-            throw_unsup!(DeallocatedWrongMemoryKind(
-                format!("{:?}", alloc_kind),
-                format!("{:?}", kind),
-            ))
+            throw_ub_format!(
+                "deallocating `{:?}` memory using `{:?}` deallocation operation",
+                alloc_kind,
+                kind
+            );
         }
         if let Some((size, align)) = old_size_and_align {
             if size != alloc.size || align != alloc.align {
-                let bytes = alloc.size;
-                throw_unsup!(IncorrectAllocationInformation(size, bytes, align, alloc.align))
+                throw_ub_format!(
+                    "incorrect layout on deallocation: allocation has size {} and alignment {}, but gave size {} and alignment {}",
+                    alloc.size.bytes(),
+                    alloc.align.bytes(),
+                    size.bytes(),
+                    align.bytes(),
+                )
             }
         }
 
@@ -338,7 +347,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             } else {
                 // The biggest power of two through which `offset` is divisible.
                 let offset_pow2 = 1 << offset.trailing_zeros();
-                throw_unsup!(AlignmentCheckFailed {
+                throw_ub!(AlignmentCheckFailed {
                     has: Align::from_bytes(offset_pow2).unwrap(),
                     required: align,
                 })
@@ -360,7 +369,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
                 assert!(size.bytes() == 0);
                 // Must be non-NULL.
                 if bits == 0 {
-                    throw_unsup!(InvalidNullPointerUsage)
+                    throw_ub!(InvalidIntPointerUsage(0))
                 }
                 // Must be aligned.
                 if let Some(align) = align {
@@ -375,7 +384,10 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
                 // It is sufficient to check this for the end pointer. The addition
                 // checks for overflow.
                 let end_ptr = ptr.offset(size, self)?;
-                end_ptr.check_inbounds_alloc(allocation_size, msg)?;
+                if end_ptr.offset > allocation_size {
+                    // equal is okay!
+                    throw_ub!(PointerOutOfBounds { ptr: end_ptr.erase_tag(), msg, allocation_size })
+                }
                 // Test align. Check this last; if both bounds and alignment are violated
                 // we want the error to be about the bounds.
                 if let Some(align) = align {
@@ -385,7 +397,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
                         // got picked we might be aligned even if this check fails.
                         // We instead have to fall back to converting to an integer and checking
                         // the "real" alignment.
-                        throw_unsup!(AlignmentCheckFailed { has: alloc_align, required: align });
+                        throw_ub!(AlignmentCheckFailed { has: alloc_align, required: align });
                     }
                     check_offset_align(ptr.offset.bytes(), align)?;
                 }
@@ -402,7 +414,9 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         let (size, _align) = self
             .get_size_and_align(ptr.alloc_id, AllocCheck::MaybeDead)
             .expect("alloc info with MaybeDead cannot fail");
-        ptr.check_inbounds_alloc(size, CheckInAllocMsg::NullPointerTest).is_err()
+        // If the pointer is out-of-bounds, it may be null.
+        // Note that one-past-the-end (offset == size) is still inbounds, and never null.
+        ptr.offset > size
     }
 }
 
@@ -432,13 +446,13 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         let alloc = tcx.alloc_map.lock().get(id);
         let alloc = match alloc {
             Some(GlobalAlloc::Memory(mem)) => Cow::Borrowed(mem),
-            Some(GlobalAlloc::Function(..)) => throw_unsup!(DerefFunctionPointer),
-            None => throw_unsup!(DanglingPointerDeref),
+            Some(GlobalAlloc::Function(..)) => throw_ub!(DerefFunctionPointer(id)),
+            None => throw_ub!(PointerUseAfterFree(id)),
             Some(GlobalAlloc::Static(def_id)) => {
                 // We got a "lazy" static that has not been computed yet.
                 if tcx.is_foreign_item(def_id) {
                     trace!("get_static_alloc: foreign item {:?}", def_id);
-                    throw_unsup!(ReadForeignStatic)
+                    throw_unsup!(ReadForeignStatic(def_id))
                 }
                 trace!("get_static_alloc: Need to compute {:?}", def_id);
                 let instance = Instance::mono(tcx.tcx, def_id);
@@ -524,7 +538,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             // to give us a cheap reference.
             let alloc = Self::get_static_alloc(memory_extra, tcx, id)?;
             if alloc.mutability == Mutability::Not {
-                throw_unsup!(ModifiedConstantMemory)
+                throw_ub!(WriteToReadOnly(id))
             }
             match M::STATIC_KIND {
                 Some(kind) => Ok((MemoryKind::Machine(kind), alloc.into_owned())),
@@ -538,7 +552,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             Ok(a) => {
                 let a = &mut a.1;
                 if a.mutability == Mutability::Not {
-                    throw_unsup!(ModifiedConstantMemory)
+                    throw_ub!(WriteToReadOnly(id))
                 }
                 Ok(a)
             }
@@ -568,7 +582,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         if self.get_fn_alloc(id).is_some() {
             return if let AllocCheck::Dereferenceable = liveness {
                 // The caller requested no function pointers.
-                throw_unsup!(DerefFunctionPointer)
+                throw_ub!(DerefFunctionPointer(id))
             } else {
                 Ok((Size::ZERO, Align::from_bytes(1).unwrap()))
             };
@@ -596,12 +610,12 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
                 if let AllocCheck::MaybeDead = liveness {
                     // Deallocated pointers are allowed, we should be able to find
                     // them in the map.
-                    Ok(*self.dead_alloc_map.get(&id).expect(
-                        "deallocated pointers should all be recorded in \
-                            `dead_alloc_map`",
-                    ))
+                    Ok(*self
+                        .dead_alloc_map
+                        .get(&id)
+                        .expect("deallocated pointers should all be recorded in `dead_alloc_map`"))
                 } else {
-                    throw_unsup!(DanglingPointerDeref)
+                    throw_ub!(PointerUseAfterFree(id))
                 }
             }
         }
@@ -626,10 +640,10 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
     ) -> InterpResult<'tcx, FnVal<'tcx, M::ExtraFnVal>> {
         let ptr = self.force_ptr(ptr)?; // We definitely need a pointer value.
         if ptr.offset.bytes() != 0 {
-            throw_unsup!(InvalidFunctionPointer)
+            throw_ub!(InvalidFunctionPointer(ptr.erase_tag()))
         }
         let id = M::canonical_alloc_id(self, ptr.alloc_id);
-        self.get_fn_alloc(id).ok_or_else(|| err_unsup!(ExecuteMemory).into())
+        self.get_fn_alloc(id).ok_or_else(|| err_ub!(InvalidFunctionPointer(ptr.erase_tag())).into())
     }
 
     pub fn mark_immutable(&mut self, id: AllocId) -> InterpResult<'tcx> {
diff --git a/src/librustc_mir/interpret/operand.rs b/src/librustc_mir/interpret/operand.rs
index 75452b9395b50..316cf2ee41918 100644
--- a/src/librustc_mir/interpret/operand.rs
+++ b/src/librustc_mir/interpret/operand.rs
@@ -343,7 +343,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         let len = mplace.len(self)?;
         let bytes = self.memory.read_bytes(mplace.ptr, Size::from_bytes(len as u64))?;
         let str = ::std::str::from_utf8(bytes)
-            .map_err(|err| err_unsup!(ValidationFailure(err.to_string())))?;
+            .map_err(|err| err_ub_format!("this string is not valid UTF-8: {}", err))?;
         Ok(str)
     }
 
@@ -457,7 +457,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         layout: Option<TyLayout<'tcx>>,
     ) -> InterpResult<'tcx, OpTy<'tcx, M::PointerTag>> {
         let base_op = match place.local {
-            mir::RETURN_PLACE => throw_unsup!(ReadFromReturnPointer),
+            mir::RETURN_PLACE => throw_ub!(ReadFromReturnPlace),
             local => {
                 // Do not use the layout passed in as argument if the base we are looking at
                 // here is not the entire place.
diff --git a/src/librustc_mir/interpret/place.rs b/src/librustc_mir/interpret/place.rs
index a4815b9696ebb..107cfee5aceb5 100644
--- a/src/librustc_mir/interpret/place.rs
+++ b/src/librustc_mir/interpret/place.rs
@@ -926,7 +926,7 @@ where
             // most likey we *are* running `typeck` right now. Investigate whether we can bail out
             // on `typeck_tables().has_errors` at all const eval entry points.
             debug!("Size mismatch when transmuting!\nsrc: {:#?}\ndest: {:#?}", src, dest);
-            throw_unsup!(TransmuteSizeDiff(src.layout.ty, dest.layout.ty));
+            throw_inval!(TransmuteSizeDiff(src.layout.ty, dest.layout.ty));
         }
         // Unsized copies rely on interpreting `src.meta` with `dest.layout`, we want
         // to avoid that here.
diff --git a/src/librustc_mir/interpret/terminator.rs b/src/librustc_mir/interpret/terminator.rs
index 473ed9d13ecfb..22a081a9c8e0b 100644
--- a/src/librustc_mir/interpret/terminator.rs
+++ b/src/librustc_mir/interpret/terminator.rs
@@ -172,13 +172,19 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             trace!("Skipping callee ZST");
             return Ok(());
         }
-        let caller_arg = caller_arg.next().ok_or_else(|| err_unsup!(FunctionArgCountMismatch))?;
+        let caller_arg = caller_arg.next().ok_or_else(|| {
+            err_ub_format!("calling a function with fewer arguments than it requires")
+        })?;
         if rust_abi {
             assert!(!caller_arg.layout.is_zst(), "ZSTs must have been already filtered out");
         }
         // Now, check
         if !Self::check_argument_compat(rust_abi, caller_arg.layout, callee_arg.layout) {
-            throw_unsup!(FunctionArgMismatch(caller_arg.layout.ty, callee_arg.layout.ty))
+            throw_ub_format!(
+                "calling a function with argument of type {:?} passing data of type {:?}",
+                callee_arg.layout.ty,
+                caller_arg.layout.ty
+            )
         }
         // We allow some transmutes here
         self.copy_op_transmute(caller_arg, callee_arg)
@@ -223,7 +229,11 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 abi => abi,
             };
             if normalize_abi(caller_abi) != normalize_abi(callee_abi) {
-                throw_unsup!(FunctionAbiMismatch(caller_abi, callee_abi))
+                throw_ub_format!(
+                    "calling a function with ABI {:?} using caller ABI {:?}",
+                    callee_abi,
+                    caller_abi
+                )
             }
         }
 
@@ -253,110 +263,108 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                     StackPopCleanup::Goto { ret: ret.map(|p| p.1), unwind },
                 )?;
 
-                // We want to pop this frame again in case there was an error, to put
-                // the blame in the right location.  Until the 2018 edition is used in
-                // the compiler, we have to do this with an immediately invoked function.
-                let res =
-                    (|| {
-                        trace!(
-                            "caller ABI: {:?}, args: {:#?}",
-                            caller_abi,
-                            args.iter()
-                                .map(|arg| (arg.layout.ty, format!("{:?}", **arg)))
-                                .collect::<Vec<_>>()
-                        );
-                        trace!(
-                            "spread_arg: {:?}, locals: {:#?}",
-                            body.spread_arg,
-                            body.args_iter()
-                                .map(|local| (
-                                    local,
-                                    self.layout_of_local(self.frame(), local, None).unwrap().ty
-                                ))
-                                .collect::<Vec<_>>()
-                        );
-
-                        // Figure out how to pass which arguments.
-                        // The Rust ABI is special: ZST get skipped.
-                        let rust_abi = match caller_abi {
-                            Abi::Rust | Abi::RustCall => true,
-                            _ => false,
+                // If an error is raised here, pop the frame again to get an accurate backtrace.
+                // To this end, we wrap it all in a `try` block.
+                let res: InterpResult<'tcx> = try {
+                    trace!(
+                        "caller ABI: {:?}, args: {:#?}",
+                        caller_abi,
+                        args.iter()
+                            .map(|arg| (arg.layout.ty, format!("{:?}", **arg)))
+                            .collect::<Vec<_>>()
+                    );
+                    trace!(
+                        "spread_arg: {:?}, locals: {:#?}",
+                        body.spread_arg,
+                        body.args_iter()
+                            .map(|local| (
+                                local,
+                                self.layout_of_local(self.frame(), local, None).unwrap().ty
+                            ))
+                            .collect::<Vec<_>>()
+                    );
+
+                    // Figure out how to pass which arguments.
+                    // The Rust ABI is special: ZST get skipped.
+                    let rust_abi = match caller_abi {
+                        Abi::Rust | Abi::RustCall => true,
+                        _ => false,
+                    };
+                    // We have two iterators: Where the arguments come from,
+                    // and where they go to.
+
+                    // For where they come from: If the ABI is RustCall, we untuple the
+                    // last incoming argument.  These two iterators do not have the same type,
+                    // so to keep the code paths uniform we accept an allocation
+                    // (for RustCall ABI only).
+                    let caller_args: Cow<'_, [OpTy<'tcx, M::PointerTag>]> =
+                        if caller_abi == Abi::RustCall && !args.is_empty() {
+                            // Untuple
+                            let (&untuple_arg, args) = args.split_last().unwrap();
+                            trace!("eval_fn_call: Will pass last argument by untupling");
+                            Cow::from(
+                                args.iter()
+                                    .map(|&a| Ok(a))
+                                    .chain(
+                                        (0..untuple_arg.layout.fields.count())
+                                            .map(|i| self.operand_field(untuple_arg, i as u64)),
+                                    )
+                                    .collect::<InterpResult<'_, Vec<OpTy<'tcx, M::PointerTag>>>>(
+                                    )?,
+                            )
+                        } else {
+                            // Plain arg passing
+                            Cow::from(args)
                         };
-                        // We have two iterators: Where the arguments come from,
-                        // and where they go to.
-
-                        // For where they come from: If the ABI is RustCall, we untuple the
-                        // last incoming argument.  These two iterators do not have the same type,
-                        // so to keep the code paths uniform we accept an allocation
-                        // (for RustCall ABI only).
-                        let caller_args: Cow<'_, [OpTy<'tcx, M::PointerTag>]> =
-                            if caller_abi == Abi::RustCall && !args.is_empty() {
-                                // Untuple
-                                let (&untuple_arg, args) = args.split_last().unwrap();
-                                trace!("eval_fn_call: Will pass last argument by untupling");
-                                Cow::from(args.iter().map(|&a| Ok(a))
-                                .chain((0..untuple_arg.layout.fields.count())
-                                    .map(|i| self.operand_field(untuple_arg, i as u64))
-                                )
-                                .collect::<InterpResult<'_, Vec<OpTy<'tcx, M::PointerTag>>>>()?)
-                            } else {
-                                // Plain arg passing
-                                Cow::from(args)
-                            };
-                        // Skip ZSTs
-                        let mut caller_iter = caller_args
-                            .iter()
-                            .filter(|op| !rust_abi || !op.layout.is_zst())
-                            .copied();
-
-                        // Now we have to spread them out across the callee's locals,
-                        // taking into account the `spread_arg`.  If we could write
-                        // this is a single iterator (that handles `spread_arg`), then
-                        // `pass_argument` would be the loop body. It takes care to
-                        // not advance `caller_iter` for ZSTs
-                        for local in body.args_iter() {
-                            let dest = self.eval_place(&mir::Place::from(local))?;
-                            if Some(local) == body.spread_arg {
-                                // Must be a tuple
-                                for i in 0..dest.layout.fields.count() {
-                                    let dest = self.place_field(dest, i as u64)?;
-                                    self.pass_argument(rust_abi, &mut caller_iter, dest)?;
-                                }
-                            } else {
-                                // Normal argument
+                    // Skip ZSTs
+                    let mut caller_iter =
+                        caller_args.iter().filter(|op| !rust_abi || !op.layout.is_zst()).copied();
+
+                    // Now we have to spread them out across the callee's locals,
+                    // taking into account the `spread_arg`.  If we could write
+                    // this is a single iterator (that handles `spread_arg`), then
+                    // `pass_argument` would be the loop body. It takes care to
+                    // not advance `caller_iter` for ZSTs.
+                    for local in body.args_iter() {
+                        let dest = self.eval_place(&mir::Place::from(local))?;
+                        if Some(local) == body.spread_arg {
+                            // Must be a tuple
+                            for i in 0..dest.layout.fields.count() {
+                                let dest = self.place_field(dest, i as u64)?;
                                 self.pass_argument(rust_abi, &mut caller_iter, dest)?;
                             }
+                        } else {
+                            // Normal argument
+                            self.pass_argument(rust_abi, &mut caller_iter, dest)?;
                         }
-                        // Now we should have no more caller args
-                        if caller_iter.next().is_some() {
-                            trace!("Caller has passed too many args");
-                            throw_unsup!(FunctionArgCountMismatch)
+                    }
+                    // Now we should have no more caller args
+                    if caller_iter.next().is_some() {
+                        throw_ub_format!("calling a function with more arguments than it expected")
+                    }
+                    // Don't forget to check the return type!
+                    if let Some((caller_ret, _)) = ret {
+                        let callee_ret = self.eval_place(&mir::Place::return_place())?;
+                        if !Self::check_argument_compat(
+                            rust_abi,
+                            caller_ret.layout,
+                            callee_ret.layout,
+                        ) {
+                            throw_ub_format!(
+                                "calling a function with return type {:?} passing \
+                                     return place of type {:?}",
+                                callee_ret.layout.ty,
+                                caller_ret.layout.ty
+                            )
                         }
-                        // Don't forget to check the return type!
-                        if let Some((caller_ret, _)) = ret {
-                            let callee_ret = self.eval_place(&mir::Place::return_place())?;
-                            if !Self::check_argument_compat(
-                                rust_abi,
-                                caller_ret.layout,
-                                callee_ret.layout,
-                            ) {
-                                throw_unsup!(FunctionRetMismatch(
-                                    caller_ret.layout.ty,
-                                    callee_ret.layout.ty
-                                ))
-                            }
-                        } else {
-                            let local = mir::RETURN_PLACE;
-                            let callee_layout = self.layout_of_local(self.frame(), local, None)?;
-                            if !callee_layout.abi.is_uninhabited() {
-                                throw_unsup!(FunctionRetMismatch(
-                                    self.tcx.types.never,
-                                    callee_layout.ty
-                                ))
-                            }
+                    } else {
+                        let local = mir::RETURN_PLACE;
+                        let callee_layout = self.layout_of_local(self.frame(), local, None)?;
+                        if !callee_layout.abi.is_uninhabited() {
+                            throw_ub_format!("calling a returning function without a return place")
                         }
-                        Ok(())
-                    })();
+                    }
+                };
                 match res {
                     Err(err) => {
                         self.stack.pop();
diff --git a/src/librustc_mir/interpret/validity.rs b/src/librustc_mir/interpret/validity.rs
index 05bb010959b32..d93b78a5bd5b6 100644
--- a/src/librustc_mir/interpret/validity.rs
+++ b/src/librustc_mir/interpret/validity.rs
@@ -29,7 +29,7 @@ macro_rules! throw_validation_failure {
             write_path(&mut msg, where_);
         }
         write!(&mut msg, ", but expected {}", $details).unwrap();
-        throw_unsup!(ValidationFailure(msg))
+        throw_ub!(ValidationFailure(msg))
     }};
     ($what:expr, $where:expr) => {{
         let mut msg = format!("encountered {}", $what);
@@ -38,7 +38,7 @@ macro_rules! throw_validation_failure {
             msg.push_str(" at ");
             write_path(&mut msg, where_);
         }
-        throw_unsup!(ValidationFailure(msg))
+        throw_ub!(ValidationFailure(msg))
     }};
 }
 
@@ -353,31 +353,39 @@ impl<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, 'tcx, M
                     place.ptr, size, align
                 );
                 match err.kind {
-                    err_unsup!(InvalidNullPointerUsage) => {
+                    err_ub!(InvalidIntPointerUsage(0)) => {
                         throw_validation_failure!(format_args!("a NULL {}", kind), self.path)
                     }
-                    err_unsup!(AlignmentCheckFailed { required, has }) => {
-                        throw_validation_failure!(
-                            format_args!(
-                                "an unaligned {} \
-                                    (required {} byte alignment but found {})",
-                                kind,
-                                required.bytes(),
-                                has.bytes()
-                            ),
-                            self.path
-                        )
-                    }
+                    err_ub!(InvalidIntPointerUsage(i)) => throw_validation_failure!(
+                        format_args!("a {} to unallocated address {}", kind, i),
+                        self.path
+                    ),
+                    err_ub!(AlignmentCheckFailed { required, has }) => throw_validation_failure!(
+                        format_args!(
+                            "an unaligned {} (required {} byte alignment but found {})",
+                            kind,
+                            required.bytes(),
+                            has.bytes()
+                        ),
+                        self.path
+                    ),
                     err_unsup!(ReadBytesAsPointer) => throw_validation_failure!(
                         format_args!("a dangling {} (created from integer)", kind),
                         self.path
                     ),
-                    err_unsup!(PointerOutOfBounds { .. }) | err_unsup!(DanglingPointerDeref) => {
-                        throw_validation_failure!(
-                            format_args!("a dangling {} (not entirely in bounds)", kind),
-                            self.path
-                        )
-                    }
+                    err_ub!(PointerOutOfBounds { .. }) => throw_validation_failure!(
+                        format_args!(
+                            "a dangling {} (going beyond the bounds of its allocation)",
+                            kind
+                        ),
+                        self.path
+                    ),
+                    // This cannot happen during const-eval (because interning already detects
+                    // dangling pointers), but it can happen in Miri.
+                    err_ub!(PointerUseAfterFree(_)) => throw_validation_failure!(
+                        format_args!("a dangling {} (use-after-free)", kind),
+                        self.path
+                    ),
                     _ => bug!("Unexpected error during ptr inbounds test: {}", err),
                 }
             }
@@ -765,11 +773,11 @@ impl<'rt, 'mir, 'tcx, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
                     Err(err) => {
                         // For some errors we might be able to provide extra information
                         match err.kind {
-                            err_unsup!(ReadUndefBytes(offset)) => {
+                            err_ub!(InvalidUndefBytes(Some(ptr))) => {
                                 // Some byte was undefined, determine which
                                 // element that byte belongs to so we can
                                 // provide an index.
-                                let i = (offset.bytes() / layout.size.bytes()) as usize;
+                                let i = (ptr.offset.bytes() / layout.size.bytes()) as usize;
                                 self.path.push(PathElem::ArrayElem(i));
 
                                 throw_validation_failure!("undefined bytes", self.path)
@@ -817,7 +825,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         // Run it.
         match visitor.visit_value(op) {
             Ok(()) => Ok(()),
-            Err(err) if matches!(err.kind, err_unsup!(ValidationFailure { .. })) => Err(err),
+            Err(err) if matches!(err.kind, err_ub!(ValidationFailure { .. })) => Err(err),
             Err(err) if cfg!(debug_assertions) => {
                 bug!("Unexpected error during validation: {}", err)
             }
diff --git a/src/librustc_mir/lib.rs b/src/librustc_mir/lib.rs
index 284dd74ce99d4..7d3aba3ff034e 100644
--- a/src/librustc_mir/lib.rs
+++ b/src/librustc_mir/lib.rs
@@ -9,6 +9,9 @@ Rust MIR: a lowered representation of Rust.
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(box_syntax)]
+#![feature(const_if_match)]
+#![feature(const_fn)]
+#![feature(const_panic)]
 #![feature(crate_visibility_modifier)]
 #![feature(drain_filter)]
 #![feature(exhaustive_patterns)]
diff --git a/src/librustc_mir/monomorphize/collector.rs b/src/librustc_mir/monomorphize/collector.rs
index f56bef031a748..51760500b03c9 100644
--- a/src/librustc_mir/monomorphize/collector.rs
+++ b/src/librustc_mir/monomorphize/collector.rs
@@ -183,7 +183,6 @@ use rustc::mir::interpret::{ErrorHandled, GlobalAlloc, Scalar};
 use rustc::mir::mono::{InstantiationMode, MonoItem};
 use rustc::mir::visit::Visitor as MirVisitor;
 use rustc::mir::{self, Local, Location};
-use rustc::session::config::EntryFnType;
 use rustc::ty::adjustment::{CustomCoerceUnsized, PointerCast};
 use rustc::ty::print::obsolete::DefPathBasedNames;
 use rustc::ty::subst::{InternalSubsts, SubstsRef};
@@ -194,6 +193,7 @@ use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, DefIdMap, LOCAL_CRATE};
 use rustc_hir::itemlikevisit::ItemLikeVisitor;
 use rustc_index::bit_set::GrowableBitSet;
+use rustc_session::config::EntryFnType;
 use smallvec::SmallVec;
 use std::iter;
 
diff --git a/src/librustc_mir/transform/check_consts/ops.rs b/src/librustc_mir/transform/check_consts/ops.rs
index d06a2aa44f231..af7af7388bd28 100644
--- a/src/librustc_mir/transform/check_consts/ops.rs
+++ b/src/librustc_mir/transform/check_consts/ops.rs
@@ -1,9 +1,9 @@
 //! Concrete error types for all operations which may be invalid in a certain const context.
 
-use rustc::session::config::nightly_options;
-use rustc::session::parse::feature_err;
 use rustc_errors::struct_span_err;
 use rustc_hir::def_id::DefId;
+use rustc_session::config::nightly_options;
+use rustc_session::parse::feature_err;
 use rustc_span::symbol::sym;
 use rustc_span::{Span, Symbol};
 
diff --git a/src/librustc_mir/transform/check_unsafety.rs b/src/librustc_mir/transform/check_unsafety.rs
index 21788593259c2..437a154a9b80f 100644
--- a/src/librustc_mir/transform/check_unsafety.rs
+++ b/src/librustc_mir/transform/check_unsafety.rs
@@ -1,5 +1,3 @@
-use rustc::hir::map::Map;
-use rustc::lint::builtin::{SAFE_PACKED_BORROWS, UNUSED_UNSAFE};
 use rustc::mir::visit::{MutatingUseContext, PlaceContext, Visitor};
 use rustc::mir::*;
 use rustc::ty::cast::CastTy;
@@ -11,6 +9,7 @@ use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit;
 use rustc_hir::Node;
+use rustc_session::lint::builtin::{SAFE_PACKED_BORROWS, UNUSED_UNSAFE};
 use rustc_span::symbol::{sym, Symbol};
 
 use std::ops::Bound;
@@ -451,7 +450,7 @@ struct UnusedUnsafeVisitor<'a> {
 }
 
 impl<'a, 'tcx> intravisit::Visitor<'tcx> for UnusedUnsafeVisitor<'a> {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
         intravisit::NestedVisitorMap::None
diff --git a/src/librustc_mir/transform/const_prop.rs b/src/librustc_mir/transform/const_prop.rs
index 289b198d2c949..ca23c44f64668 100644
--- a/src/librustc_mir/transform/const_prop.rs
+++ b/src/librustc_mir/transform/const_prop.rs
@@ -4,7 +4,6 @@
 use std::borrow::Cow;
 use std::cell::Cell;
 
-use rustc::lint;
 use rustc::mir::interpret::{InterpResult, Scalar};
 use rustc::mir::visit::{
     MutVisitor, MutatingUseContext, NonMutatingUseContext, PlaceContext, Visitor,
@@ -25,6 +24,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def::DefKind;
 use rustc_hir::HirId;
 use rustc_index::vec::IndexVec;
+use rustc_session::lint;
 use rustc_span::Span;
 use rustc_trait_selection::traits;
 
diff --git a/src/librustc_mir/transform/dump_mir.rs b/src/librustc_mir/transform/dump_mir.rs
index 5dec2c6df99dc..795bcb57d0678 100644
--- a/src/librustc_mir/transform/dump_mir.rs
+++ b/src/librustc_mir/transform/dump_mir.rs
@@ -8,8 +8,8 @@ use std::io;
 use crate::transform::{MirPass, MirSource};
 use crate::util as mir_util;
 use rustc::mir::{Body, BodyAndCache};
-use rustc::session::config::{OutputFilenames, OutputType};
 use rustc::ty::TyCtxt;
+use rustc_session::config::{OutputFilenames, OutputType};
 
 pub struct Marker(pub &'static str);
 
diff --git a/src/librustc_mir/transform/generator.rs b/src/librustc_mir/transform/generator.rs
index 7418a7519ba2b..b2906739ff1b1 100644
--- a/src/librustc_mir/transform/generator.rs
+++ b/src/librustc_mir/transform/generator.rs
@@ -107,15 +107,15 @@ impl<'tcx> MutVisitor<'tcx> for DerefArgVisitor<'tcx> {
     }
 
     fn visit_local(&mut self, local: &mut Local, _: PlaceContext, _: Location) {
-        assert_ne!(*local, self_arg());
+        assert_ne!(*local, SELF_ARG);
     }
 
     fn visit_place(&mut self, place: &mut Place<'tcx>, context: PlaceContext, location: Location) {
-        if place.local == self_arg() {
+        if place.local == SELF_ARG {
             replace_base(
                 place,
                 Place {
-                    local: self_arg(),
+                    local: SELF_ARG,
                     projection: self.tcx().intern_place_elems(&[ProjectionElem::Deref]),
                 },
                 self.tcx,
@@ -125,7 +125,7 @@ impl<'tcx> MutVisitor<'tcx> for DerefArgVisitor<'tcx> {
 
             for elem in place.projection.iter() {
                 if let PlaceElem::Index(local) = elem {
-                    assert_ne!(*local, self_arg());
+                    assert_ne!(*local, SELF_ARG);
                 }
             }
         }
@@ -143,15 +143,15 @@ impl<'tcx> MutVisitor<'tcx> for PinArgVisitor<'tcx> {
     }
 
     fn visit_local(&mut self, local: &mut Local, _: PlaceContext, _: Location) {
-        assert_ne!(*local, self_arg());
+        assert_ne!(*local, SELF_ARG);
     }
 
     fn visit_place(&mut self, place: &mut Place<'tcx>, context: PlaceContext, location: Location) {
-        if place.local == self_arg() {
+        if place.local == SELF_ARG {
             replace_base(
                 place,
                 Place {
-                    local: self_arg(),
+                    local: SELF_ARG,
                     projection: self.tcx().intern_place_elems(&[ProjectionElem::Field(
                         Field::new(0),
                         self.ref_gen_ty,
@@ -164,7 +164,7 @@ impl<'tcx> MutVisitor<'tcx> for PinArgVisitor<'tcx> {
 
             for elem in place.projection.iter() {
                 if let PlaceElem::Index(local) = elem {
-                    assert_ne!(*local, self_arg());
+                    assert_ne!(*local, SELF_ARG);
                 }
             }
         }
@@ -180,9 +180,7 @@ fn replace_base<'tcx>(place: &mut Place<'tcx>, new_base: Place<'tcx>, tcx: TyCtx
     place.projection = tcx.intern_place_elems(&new_projection);
 }
 
-fn self_arg() -> Local {
-    Local::new(1)
-}
+const SELF_ARG: Local = Local::from_u32(1);
 
 /// Generator has not been resumed yet.
 const UNRESUMED: usize = GeneratorSubsts::UNRESUMED;
@@ -237,7 +235,7 @@ impl TransformVisitor<'tcx> {
 
     // Create a Place referencing a generator struct field
     fn make_field(&self, variant_index: VariantIdx, idx: usize, ty: Ty<'tcx>) -> Place<'tcx> {
-        let self_place = Place::from(self_arg());
+        let self_place = Place::from(SELF_ARG);
         let base = self.tcx.mk_place_downcast_unnamed(self_place, variant_index);
         let mut projection = base.projection.to_vec();
         projection.push(ProjectionElem::Field(Field::new(idx), ty));
@@ -247,7 +245,7 @@ impl TransformVisitor<'tcx> {
 
     // Create a statement which changes the discriminant
     fn set_discr(&self, state_disc: VariantIdx, source_info: SourceInfo) -> Statement<'tcx> {
-        let self_place = Place::from(self_arg());
+        let self_place = Place::from(SELF_ARG);
         Statement {
             source_info,
             kind: StatementKind::SetDiscriminant {
@@ -263,7 +261,7 @@ impl TransformVisitor<'tcx> {
         let local_decls_len = body.local_decls.push(temp_decl);
         let temp = Place::from(local_decls_len);
 
-        let self_place = Place::from(self_arg());
+        let self_place = Place::from(SELF_ARG);
         let assign = Statement {
             source_info: source_info(body),
             kind: StatementKind::Assign(box (temp, Rvalue::Discriminant(self_place))),
@@ -540,7 +538,7 @@ fn locals_live_across_suspend_points(
             live_locals_here.intersect(&liveness.outs[block]);
 
             // The generator argument is ignored.
-            live_locals_here.remove(self_arg());
+            live_locals_here.remove(SELF_ARG);
 
             debug!("loc = {:?}, live_locals_here = {:?}", loc, live_locals_here);
 
@@ -837,7 +835,6 @@ fn elaborate_generator_drops<'tcx>(
     // generator's resume function.
 
     let param_env = tcx.param_env(def_id);
-    let gen = self_arg();
 
     let mut elaborator = DropShimElaborator { body, patch: MirPatch::new(body), tcx, param_env };
 
@@ -845,7 +842,7 @@ fn elaborate_generator_drops<'tcx>(
         let (target, unwind, source_info) = match block_data.terminator() {
             Terminator { source_info, kind: TerminatorKind::Drop { location, target, unwind } } => {
                 if let Some(local) = location.as_local() {
-                    if local == gen {
+                    if local == SELF_ARG {
                         (target, unwind, source_info)
                     } else {
                         continue;
@@ -864,7 +861,7 @@ fn elaborate_generator_drops<'tcx>(
         elaborate_drop(
             &mut elaborator,
             *source_info,
-            &Place::from(gen),
+            &Place::from(SELF_ARG),
             (),
             *target,
             unwind,
@@ -918,7 +915,7 @@ fn create_generator_drop_shim<'tcx>(
     make_generator_state_argument_indirect(tcx, def_id, &mut body);
 
     // Change the generator argument from &mut to *mut
-    body.local_decls[self_arg()] = LocalDecl {
+    body.local_decls[SELF_ARG] = LocalDecl {
         mutability: Mutability::Mut,
         ty: tcx.mk_ptr(ty::TypeAndMut { ty: gen_ty, mutbl: hir::Mutability::Mut }),
         user_ty: UserTypeProjections::none(),
@@ -933,7 +930,7 @@ fn create_generator_drop_shim<'tcx>(
             0,
             Statement {
                 source_info,
-                kind: StatementKind::Retag(RetagKind::Raw, box Place::from(self_arg())),
+                kind: StatementKind::Retag(RetagKind::Raw, box Place::from(SELF_ARG)),
             },
         )
     }
@@ -991,18 +988,101 @@ fn insert_panic_block<'tcx>(
     assert_block
 }
 
+fn can_return<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>) -> bool {
+    // Returning from a function with an uninhabited return type is undefined behavior.
+    if body.return_ty().conservative_is_privately_uninhabited(tcx) {
+        return false;
+    }
+
+    // If there's a return terminator the function may return.
+    for block in body.basic_blocks() {
+        if let TerminatorKind::Return = block.terminator().kind {
+            return true;
+        }
+    }
+
+    // Otherwise the function can't return.
+    false
+}
+
+fn can_unwind<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>) -> bool {
+    // Nothing can unwind when landing pads are off.
+    if tcx.sess.no_landing_pads() {
+        return false;
+    }
+
+    // Unwinds can only start at certain terminators.
+    for block in body.basic_blocks() {
+        match block.terminator().kind {
+            // These never unwind.
+            TerminatorKind::Goto { .. }
+            | TerminatorKind::SwitchInt { .. }
+            | TerminatorKind::Abort
+            | TerminatorKind::Return
+            | TerminatorKind::Unreachable
+            | TerminatorKind::GeneratorDrop
+            | TerminatorKind::FalseEdges { .. }
+            | TerminatorKind::FalseUnwind { .. } => {}
+
+            // Resume will *continue* unwinding, but if there's no other unwinding terminator it
+            // will never be reached.
+            TerminatorKind::Resume => {}
+
+            TerminatorKind::Yield { .. } => {
+                unreachable!("`can_unwind` called before generator transform")
+            }
+
+            // These may unwind.
+            TerminatorKind::Drop { .. }
+            | TerminatorKind::DropAndReplace { .. }
+            | TerminatorKind::Call { .. }
+            | TerminatorKind::Assert { .. } => return true,
+        }
+    }
+
+    // If we didn't find an unwinding terminator, the function cannot unwind.
+    false
+}
+
 fn create_generator_resume_function<'tcx>(
     tcx: TyCtxt<'tcx>,
     transform: TransformVisitor<'tcx>,
     def_id: DefId,
     source: MirSource<'tcx>,
     body: &mut BodyAndCache<'tcx>,
+    can_return: bool,
 ) {
+    let can_unwind = can_unwind(tcx, body);
+
     // Poison the generator when it unwinds
-    for block in body.basic_blocks_mut() {
-        let source_info = block.terminator().source_info;
-        if let &TerminatorKind::Resume = &block.terminator().kind {
-            block.statements.push(transform.set_discr(VariantIdx::new(POISONED), source_info));
+    if can_unwind {
+        let poison_block = BasicBlock::new(body.basic_blocks().len());
+        let source_info = source_info(body);
+        body.basic_blocks_mut().push(BasicBlockData {
+            statements: vec![transform.set_discr(VariantIdx::new(POISONED), source_info)],
+            terminator: Some(Terminator { source_info, kind: TerminatorKind::Resume }),
+            is_cleanup: true,
+        });
+
+        for (idx, block) in body.basic_blocks_mut().iter_enumerated_mut() {
+            let source_info = block.terminator().source_info;
+
+            if let TerminatorKind::Resume = block.terminator().kind {
+                // An existing `Resume` terminator is redirected to jump to our dedicated
+                // "poisoning block" above.
+                if idx != poison_block {
+                    *block.terminator_mut() = Terminator {
+                        source_info,
+                        kind: TerminatorKind::Goto { target: poison_block },
+                    };
+                }
+            } else if !block.is_cleanup {
+                // Any terminators that *can* unwind but don't have an unwind target set are also
+                // pointed at our poisoning block (unless they're part of the cleanup path).
+                if let Some(unwind @ None) = block.terminator_mut().unwind_mut() {
+                    *unwind = Some(poison_block);
+                }
+            }
         }
     }
 
@@ -1015,8 +1095,20 @@ fn create_generator_resume_function<'tcx>(
 
     // Panic when resumed on the returned or poisoned state
     let generator_kind = body.generator_kind.unwrap();
-    cases.insert(1, (RETURNED, insert_panic_block(tcx, body, ResumedAfterReturn(generator_kind))));
-    cases.insert(2, (POISONED, insert_panic_block(tcx, body, ResumedAfterPanic(generator_kind))));
+
+    if can_unwind {
+        cases.insert(
+            1,
+            (POISONED, insert_panic_block(tcx, body, ResumedAfterPanic(generator_kind))),
+        );
+    }
+
+    if can_return {
+        cases.insert(
+            1,
+            (RETURNED, insert_panic_block(tcx, body, ResumedAfterReturn(generator_kind))),
+        );
+    }
 
     insert_switch(body, cases, &transform, TerminatorKind::Unreachable);
 
@@ -1042,7 +1134,7 @@ fn insert_clean_drop(body: &mut BodyAndCache<'_>) -> BasicBlock {
     // Create a block to destroy an unresumed generators. This can only destroy upvars.
     let drop_clean = BasicBlock::new(body.basic_blocks().len());
     let term = TerminatorKind::Drop {
-        location: Place::from(self_arg()),
+        location: Place::from(SELF_ARG),
         target: return_block,
         unwind: None,
     };
@@ -1200,6 +1292,8 @@ impl<'tcx> MirPass<'tcx> for StateTransform {
         let (remap, layout, storage_liveness) =
             compute_layout(tcx, source, &upvars, interior, movable, body);
 
+        let can_return = can_return(tcx, body);
+
         // Run the transformation which converts Places from Local to generator struct
         // accesses for locals in `remap`.
         // It also rewrites `return x` and `yield y` as writing a new generator state and returning
@@ -1243,6 +1337,6 @@ impl<'tcx> MirPass<'tcx> for StateTransform {
         body.generator_drop = Some(box drop_shim);
 
         // Create the Generator::resume function
-        create_generator_resume_function(tcx, transform, def_id, source, body);
+        create_generator_resume_function(tcx, transform, def_id, source, body, can_return);
     }
 }
diff --git a/src/librustc_mir/transform/inline.rs b/src/librustc_mir/transform/inline.rs
index b6802505df73f..769f3fdcc013f 100644
--- a/src/librustc_mir/transform/inline.rs
+++ b/src/librustc_mir/transform/inline.rs
@@ -1,25 +1,22 @@
 //! Inlining pass for MIR functions
 
-use rustc_hir::def_id::DefId;
-
-use rustc_index::bit_set::BitSet;
-use rustc_index::vec::{Idx, IndexVec};
-
 use rustc::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc::mir::visit::*;
 use rustc::mir::*;
-use rustc::session::config::Sanitizer;
 use rustc::ty::subst::{InternalSubsts, Subst, SubstsRef};
 use rustc::ty::{self, Instance, InstanceDef, ParamEnv, Ty, TyCtxt, TypeFoldable};
+use rustc_attr as attr;
+use rustc_hir::def_id::DefId;
+use rustc_index::bit_set::BitSet;
+use rustc_index::vec::{Idx, IndexVec};
+use rustc_session::config::Sanitizer;
+use rustc_target::spec::abi::Abi;
 
 use super::simplify::{remove_dead_blocks, CfgSimplifier};
 use crate::transform::{MirPass, MirSource};
 use std::collections::VecDeque;
 use std::iter;
 
-use rustc_attr as attr;
-use rustc_target::spec::abi::Abi;
-
 const DEFAULT_THRESHOLD: usize = 50;
 const HINT_THRESHOLD: usize = 100;
 
diff --git a/src/librustc_mir/transform/mod.rs b/src/librustc_mir/transform/mod.rs
index d4a5966af4afe..3eb9d23a32a25 100644
--- a/src/librustc_mir/transform/mod.rs
+++ b/src/librustc_mir/transform/mod.rs
@@ -1,5 +1,4 @@
 use crate::{shim, util};
-use rustc::hir::map::Map;
 use rustc::mir::{BodyAndCache, ConstQualifs, MirPhase, Promoted};
 use rustc::ty::query::Providers;
 use rustc::ty::steal::Steal;
@@ -86,7 +85,7 @@ fn mir_keys(tcx: TyCtxt<'_>, krate: CrateNum) -> &DefIdSet {
             }
             intravisit::walk_struct_def(self, v)
         }
-        type Map = Map<'tcx>;
+        type Map = intravisit::ErasedMap<'tcx>;
         fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
             NestedVisitorMap::None
         }
diff --git a/src/librustc_mir_build/hair/pattern/_match.rs b/src/librustc_mir_build/hair/pattern/_match.rs
index 486dd3579d293..82810f356759d 100644
--- a/src/librustc_mir_build/hair/pattern/_match.rs
+++ b/src/librustc_mir_build/hair/pattern/_match.rs
@@ -235,17 +235,15 @@ use rustc_index::vec::Idx;
 use super::{compare_const_vals, PatternFoldable, PatternFolder};
 use super::{FieldPat, Pat, PatKind, PatRange};
 
-use rustc::ty::layout::{Integer, IntegerExt, Size, VariantIdx};
-use rustc::ty::{self, Const, Ty, TyCtxt, TypeFoldable, VariantDef};
-use rustc_hir::def_id::DefId;
-use rustc_hir::{HirId, RangeEnd};
-
-use rustc::lint;
 use rustc::mir::interpret::{truncate, AllocId, ConstValue, Pointer, Scalar};
 use rustc::mir::Field;
+use rustc::ty::layout::{Integer, IntegerExt, Size, VariantIdx};
+use rustc::ty::{self, Const, Ty, TyCtxt, TypeFoldable, VariantDef};
 use rustc::util::common::ErrorReported;
-
 use rustc_attr::{SignedInt, UnsignedInt};
+use rustc_hir::def_id::DefId;
+use rustc_hir::{HirId, RangeEnd};
+use rustc_session::lint;
 use rustc_span::{Span, DUMMY_SP};
 
 use arena::TypedArena;
diff --git a/src/librustc_mir_build/hair/pattern/check_match.rs b/src/librustc_mir_build/hair/pattern/check_match.rs
index 3691305181348..f71ec5e9ac000 100644
--- a/src/librustc_mir_build/hair/pattern/check_match.rs
+++ b/src/librustc_mir_build/hair/pattern/check_match.rs
@@ -4,7 +4,6 @@ use super::_match::{expand_pattern, is_useful, MatchCheckCtxt, Matrix, PatStack}
 
 use super::{PatCtxt, PatKind, PatternError};
 
-use rustc::hir::map::Map;
 use rustc::ty::{self, Ty, TyCtxt};
 use rustc_ast::ast::Mutability;
 use rustc_errors::{error_code, struct_span_err, Applicability, DiagnosticBuilder};
@@ -43,7 +42,7 @@ struct MatchVisitor<'a, 'tcx> {
 }
 
 impl<'tcx> Visitor<'tcx> for MatchVisitor<'_, 'tcx> {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
@@ -753,7 +752,7 @@ fn check_legality_of_bindings_in_at_patterns(cx: &MatchVisitor<'_, '_>, pat: &Pa
     }
 
     impl<'v> Visitor<'v> for AtBindingPatternVisitor<'_, '_, '_> {
-        type Map = Map<'v>;
+        type Map = intravisit::ErasedMap<'v>;
 
         fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
             NestedVisitorMap::None
diff --git a/src/librustc_mir_build/hair/pattern/const_to_pat.rs b/src/librustc_mir_build/hair/pattern/const_to_pat.rs
index 214e75fbdde43..ae951e810e32e 100644
--- a/src/librustc_mir_build/hair/pattern/const_to_pat.rs
+++ b/src/librustc_mir_build/hair/pattern/const_to_pat.rs
@@ -1,16 +1,14 @@
-use rustc::lint;
 use rustc::mir::Field;
 use rustc::ty::{self, Ty, TyCtxt};
 use rustc_hir as hir;
+use rustc_index::vec::Idx;
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
+use rustc_session::lint;
+use rustc_span::Span;
 use rustc_trait_selection::traits::predicate_for_trait_def;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use rustc_trait_selection::traits::{self, ObligationCause, PredicateObligation};
 
-use rustc_index::vec::Idx;
-
-use rustc_span::Span;
-
 use std::cell::Cell;
 
 use super::{FieldPat, Pat, PatCtxt, PatKind};
@@ -182,7 +180,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
         let kind = match cv.ty.kind {
             ty::Float(_) => {
                 tcx.struct_span_lint_hir(
-                    ::rustc::lint::builtin::ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
+                    lint::builtin::ILLEGAL_FLOATING_POINT_LITERAL_PATTERN,
                     id,
                     span,
                     |lint| lint.build("floating-point types cannot be used in patterns").emit(),
diff --git a/src/librustc_mir_build/lib.rs b/src/librustc_mir_build/lib.rs
index 3c35827d15d3e..5a8b5a329634d 100644
--- a/src/librustc_mir_build/lib.rs
+++ b/src/librustc_mir_build/lib.rs
@@ -4,6 +4,9 @@
 
 #![feature(box_patterns)]
 #![feature(box_syntax)]
+#![feature(const_if_match)]
+#![feature(const_fn)]
+#![feature(const_panic)]
 #![feature(crate_visibility_modifier)]
 #![feature(bool_to_option)]
 #![recursion_limit = "256"]
diff --git a/src/librustc_mir_build/lints.rs b/src/librustc_mir_build/lints.rs
index 0017f800de702..8b1ddf7461a76 100644
--- a/src/librustc_mir_build/lints.rs
+++ b/src/librustc_mir_build/lints.rs
@@ -1,11 +1,11 @@
 use rustc::hir::map::blocks::FnLikeNode;
-use rustc::lint::builtin::UNCONDITIONAL_RECURSION;
 use rustc::mir::{self, Body, TerminatorKind};
 use rustc::ty::subst::InternalSubsts;
 use rustc::ty::{self, AssocItem, AssocItemContainer, Instance, TyCtxt};
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::FnKind;
 use rustc_index::bit_set::BitSet;
+use rustc_session::lint::builtin::UNCONDITIONAL_RECURSION;
 
 crate fn check<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>, def_id: DefId) {
     let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
diff --git a/src/librustc_passes/check_const.rs b/src/librustc_passes/check_const.rs
index af06fc0c0026d..30737360b9c20 100644
--- a/src/librustc_passes/check_const.rs
+++ b/src/librustc_passes/check_const.rs
@@ -8,8 +8,6 @@
 //! through, but errors for structured control flow in a `const` should be emitted here.
 
 use rustc::hir::map::Map;
-use rustc::session::config::nightly_options;
-use rustc::session::parse::feature_err;
 use rustc::ty::query::Providers;
 use rustc::ty::TyCtxt;
 use rustc_ast::ast::Mutability;
@@ -17,6 +15,8 @@ use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
+use rustc_session::config::nightly_options;
+use rustc_session::parse::feature_err;
 use rustc_span::{sym, Span, Symbol};
 
 use std::fmt;
diff --git a/src/librustc_passes/dead.rs b/src/librustc_passes/dead.rs
index 587b57eb3225c..4466dea89b0c1 100644
--- a/src/librustc_passes/dead.rs
+++ b/src/librustc_passes/dead.rs
@@ -210,7 +210,7 @@ impl<'a, 'tcx> MarkSymbolVisitor<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> Visitor<'tcx> for MarkSymbolVisitor<'a, 'tcx> {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
diff --git a/src/librustc_passes/entry.rs b/src/librustc_passes/entry.rs
index 2cabe786d0cda..598d6bb3c4831 100644
--- a/src/librustc_passes/entry.rs
+++ b/src/librustc_passes/entry.rs
@@ -1,6 +1,4 @@
 use rustc::hir::map::Map;
-use rustc::session::config::EntryFnType;
-use rustc::session::{config, Session};
 use rustc::ty::query::Providers;
 use rustc::ty::TyCtxt;
 use rustc_ast::attr;
@@ -9,6 +7,8 @@ use rustc_errors::struct_span_err;
 use rustc_hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_hir::itemlikevisit::ItemLikeVisitor;
 use rustc_hir::{HirId, ImplItem, Item, ItemKind, TraitItem};
+use rustc_session::config::EntryFnType;
+use rustc_session::{config, Session};
 use rustc_span::symbol::sym;
 use rustc_span::{Span, DUMMY_SP};
 
diff --git a/src/librustc_passes/intrinsicck.rs b/src/librustc_passes/intrinsicck.rs
index 5cf9666797ebb..1b46aaeefcb18 100644
--- a/src/librustc_passes/intrinsicck.rs
+++ b/src/librustc_passes/intrinsicck.rs
@@ -1,4 +1,3 @@
-use rustc::hir::map::Map;
 use rustc::ty::layout::{LayoutError, Pointer, SizeSkeleton, VariantIdx};
 use rustc::ty::query::Providers;
 use rustc::ty::{self, Ty, TyCtxt};
@@ -122,7 +121,7 @@ impl ExprVisitor<'tcx> {
 }
 
 impl Visitor<'tcx> for ItemVisitor<'tcx> {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
@@ -139,7 +138,7 @@ impl Visitor<'tcx> for ItemVisitor<'tcx> {
 }
 
 impl Visitor<'tcx> for ExprVisitor<'tcx> {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
diff --git a/src/librustc_passes/liveness.rs b/src/librustc_passes/liveness.rs
index d7208a00e0938..556d6b40db466 100644
--- a/src/librustc_passes/liveness.rs
+++ b/src/librustc_passes/liveness.rs
@@ -97,7 +97,6 @@ use self::LiveNodeKind::*;
 use self::VarKind::*;
 
 use rustc::hir::map::Map;
-use rustc::lint;
 use rustc::ty::query::Providers;
 use rustc::ty::{self, TyCtxt};
 use rustc_ast::ast;
@@ -108,6 +107,7 @@ use rustc_hir::def::*;
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::{self, FnKind, NestedVisitorMap, Visitor};
 use rustc_hir::{Expr, HirId, HirIdMap, HirIdSet, Node};
+use rustc_session::lint;
 use rustc_span::symbol::sym;
 use rustc_span::Span;
 
@@ -1370,7 +1370,7 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
 // Checking for error conditions
 
 impl<'a, 'tcx> Visitor<'tcx> for Liveness<'a, 'tcx> {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
diff --git a/src/librustc_passes/reachable.rs b/src/librustc_passes/reachable.rs
index 4643add5ac3fd..121e03680396c 100644
--- a/src/librustc_passes/reachable.rs
+++ b/src/librustc_passes/reachable.rs
@@ -5,10 +5,8 @@
 // makes all other generics or inline functions that it references
 // reachable as well.
 
-use rustc::hir::map::Map;
 use rustc::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
 use rustc::middle::privacy;
-use rustc::session::config;
 use rustc::ty::query::Providers;
 use rustc::ty::{self, TyCtxt};
 use rustc_data_structures::fx::FxHashSet;
@@ -17,10 +15,10 @@ use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_hir::def_id::{CrateNum, DefId};
-use rustc_hir::intravisit;
-use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
+use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::itemlikevisit::ItemLikeVisitor;
 use rustc_hir::{HirIdSet, Node};
+use rustc_session::config;
 use rustc_target::spec::abi::Abi;
 
 // Returns true if the given item must be inlined because it may be
@@ -83,7 +81,7 @@ struct ReachableContext<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> Visitor<'tcx> for ReachableContext<'a, 'tcx> {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
diff --git a/src/librustc_passes/region.rs b/src/librustc_passes/region.rs
index 640a3a35aa032..e771696a5b6bf 100644
--- a/src/librustc_passes/region.rs
+++ b/src/librustc_passes/region.rs
@@ -6,7 +6,6 @@
 //!
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/borrow_check.html
 
-use rustc::hir::map::Map;
 use rustc::middle::region::*;
 use rustc::ty::query::Providers;
 use rustc::ty::TyCtxt;
@@ -696,7 +695,7 @@ impl<'tcx> RegionResolutionVisitor<'tcx> {
 }
 
 impl<'tcx> Visitor<'tcx> for RegionResolutionVisitor<'tcx> {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
diff --git a/src/librustc_passes/stability.rs b/src/librustc_passes/stability.rs
index 6cf4132141b13..11311a3e8aa68 100644
--- a/src/librustc_passes/stability.rs
+++ b/src/librustc_passes/stability.rs
@@ -2,11 +2,8 @@
 //! propagating default levels lexically from parent to children ast nodes.
 
 use rustc::hir::map::Map;
-use rustc::lint;
 use rustc::middle::privacy::AccessLevels;
 use rustc::middle::stability::{DeprecationEntry, Index};
-use rustc::session::parse::feature_err;
-use rustc::session::Session;
 use rustc::ty::query::Providers;
 use rustc::ty::TyCtxt;
 use rustc_ast::ast::Attribute;
@@ -18,6 +15,9 @@ use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::{Generics, HirId, Item, StructField, Variant};
+use rustc_session::lint;
+use rustc_session::parse::feature_err;
+use rustc_session::Session;
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::Span;
 use rustc_trait_selection::traits::misc::can_type_implement_copy;
diff --git a/src/librustc_passes/upvars.rs b/src/librustc_passes/upvars.rs
index d20237a22d99d..43f39e6c610c8 100644
--- a/src/librustc_passes/upvars.rs
+++ b/src/librustc_passes/upvars.rs
@@ -1,6 +1,5 @@
 //! Upvar (closure capture) collection from cross-body HIR uses of `Res::Local`s.
 
-use rustc::hir::map::Map;
 use rustc::ty::query::Providers;
 use rustc::ty::TyCtxt;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
@@ -44,7 +43,7 @@ struct LocalCollector {
 }
 
 impl Visitor<'tcx> for LocalCollector {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
@@ -73,7 +72,7 @@ impl CaptureCollector<'_, '_> {
 }
 
 impl Visitor<'tcx> for CaptureCollector<'a, 'tcx> {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
diff --git a/src/librustc_passes/weak_lang_items.rs b/src/librustc_passes/weak_lang_items.rs
index d85c7d8c6de04..cde489e8d2c1e 100644
--- a/src/librustc_passes/weak_lang_items.rs
+++ b/src/librustc_passes/weak_lang_items.rs
@@ -2,15 +2,13 @@
 
 use rustc::middle::lang_items;
 use rustc::middle::lang_items::whitelisted;
-use rustc::session::config;
-
-use rustc::hir::map::Map;
 use rustc::ty::TyCtxt;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::weak_lang_items::WEAK_ITEMS_REFS;
+use rustc_session::config;
 use rustc_span::symbol::Symbol;
 use rustc_span::Span;
 
@@ -85,9 +83,9 @@ impl<'a, 'tcx> Context<'a, 'tcx> {
 }
 
 impl<'a, 'tcx, 'v> Visitor<'v> for Context<'a, 'tcx> {
-    type Map = Map<'v>;
+    type Map = intravisit::ErasedMap<'v>;
 
-    fn nested_visit_map(&mut self) -> NestedVisitorMap<Map<'v>> {
+    fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
     }
 
diff --git a/src/librustc_plugin_impl/Cargo.toml b/src/librustc_plugin_impl/Cargo.toml
index 8931307259021..372d6a534c8d4 100644
--- a/src/librustc_plugin_impl/Cargo.toml
+++ b/src/librustc_plugin_impl/Cargo.toml
@@ -17,4 +17,5 @@ rustc_hir = { path = "../librustc_hir" }
 rustc_lint = { path = "../librustc_lint" }
 rustc_metadata = { path = "../librustc_metadata" }
 rustc_ast = { path = "../librustc_ast" }
+rustc_session = { path = "../librustc_session" }
 rustc_span = { path = "../librustc_span" }
diff --git a/src/librustc_plugin_impl/load.rs b/src/librustc_plugin_impl/load.rs
index 9bd9bcb25ba88..0810cf56d1783 100644
--- a/src/librustc_plugin_impl/load.rs
+++ b/src/librustc_plugin_impl/load.rs
@@ -2,10 +2,10 @@
 
 use crate::Registry;
 use rustc::middle::cstore::MetadataLoader;
-use rustc::session::Session;
 use rustc_ast::ast::{Crate, Ident};
 use rustc_errors::struct_span_err;
 use rustc_metadata::locator;
+use rustc_session::Session;
 use rustc_span::symbol::sym;
 use rustc_span::Span;
 
diff --git a/src/librustc_privacy/Cargo.toml b/src/librustc_privacy/Cargo.toml
index 6d1272c117b4d..9854e0f6c53f3 100644
--- a/src/librustc_privacy/Cargo.toml
+++ b/src/librustc_privacy/Cargo.toml
@@ -14,6 +14,7 @@ rustc_attr = { path = "../librustc_attr" }
 rustc_errors = { path = "../librustc_errors" }
 rustc_hir = { path = "../librustc_hir" }
 rustc_typeck = { path = "../librustc_typeck" }
+rustc_session = { path = "../librustc_session" }
 rustc_ast = { path = "../librustc_ast" }
 rustc_span = { path = "../librustc_span" }
 rustc_data_structures = { path = "../librustc_data_structures" }
diff --git a/src/librustc_privacy/lib.rs b/src/librustc_privacy/lib.rs
index 108a8006409e1..f5b3de2512527 100644
--- a/src/librustc_privacy/lib.rs
+++ b/src/librustc_privacy/lib.rs
@@ -5,7 +5,6 @@
 
 use rustc::bug;
 use rustc::hir::map::Map;
-use rustc::lint;
 use rustc::middle::privacy::{AccessLevel, AccessLevels};
 use rustc::ty::fold::TypeVisitor;
 use rustc::ty::query::Providers;
@@ -20,6 +19,7 @@ use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{CrateNum, DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_hir::intravisit::{self, DeepVisitor, NestedVisitorMap, Visitor};
 use rustc_hir::{AssocItemKind, HirIdSet, Node, PatKind};
+use rustc_session::lint;
 use rustc_span::hygiene::Transparency;
 use rustc_span::symbol::{kw, sym};
 use rustc_span::Span;
@@ -1447,7 +1447,7 @@ impl<'a, 'tcx> ObsoleteVisiblePrivateTypesVisitor<'a, 'tcx> {
 }
 
 impl<'a, 'b, 'tcx, 'v> Visitor<'v> for ObsoleteCheckTypeForPrivatenessVisitor<'a, 'b, 'tcx> {
-    type Map = Map<'v>;
+    type Map = intravisit::ErasedMap<'v>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
diff --git a/src/librustc_resolve/check_unused.rs b/src/librustc_resolve/check_unused.rs
index 722f843ab6e7e..35876176e3e4b 100644
--- a/src/librustc_resolve/check_unused.rs
+++ b/src/librustc_resolve/check_unused.rs
@@ -26,12 +26,13 @@
 use crate::imports::ImportKind;
 use crate::Resolver;
 
-use rustc::{lint, ty};
+use rustc::ty;
 use rustc_ast::ast;
 use rustc_ast::node_id::NodeMap;
 use rustc_ast::visit::{self, Visitor};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::pluralize;
+use rustc_session::lint::builtin::{MACRO_USE_EXTERN_CRATE, UNUSED_IMPORTS};
 use rustc_session::lint::BuiltinLintDiagnostics;
 use rustc_span::{MultiSpan, Span, DUMMY_SP};
 
@@ -232,7 +233,7 @@ impl Resolver<'_> {
                     if let ImportKind::MacroUse = import.kind {
                         if !import.span.is_dummy() {
                             self.lint_buffer.buffer_lint(
-                                lint::builtin::MACRO_USE_EXTERN_CRATE,
+                                MACRO_USE_EXTERN_CRATE,
                                 import.id,
                                 import.span,
                                 "deprecated `#[macro_use]` attribute used to \
@@ -247,9 +248,8 @@ impl Resolver<'_> {
                     self.maybe_unused_extern_crates.push((import.id, import.span));
                 }
                 ImportKind::MacroUse => {
-                    let lint = lint::builtin::UNUSED_IMPORTS;
                     let msg = "unused `#[macro_use]` import";
-                    self.lint_buffer.buffer_lint(lint, import.id, import.span, msg);
+                    self.lint_buffer.buffer_lint(UNUSED_IMPORTS, import.id, import.span, msg);
                 }
                 _ => {}
             }
@@ -314,7 +314,7 @@ impl Resolver<'_> {
             };
 
             visitor.r.lint_buffer.buffer_lint_with_diagnostic(
-                lint::builtin::UNUSED_IMPORTS,
+                UNUSED_IMPORTS,
                 unused.use_tree_id,
                 ms,
                 &msg,
diff --git a/src/librustc_resolve/diagnostics.rs b/src/librustc_resolve/diagnostics.rs
index 7571dabcf7ef4..6f567ab65a70c 100644
--- a/src/librustc_resolve/diagnostics.rs
+++ b/src/librustc_resolve/diagnostics.rs
@@ -3,7 +3,6 @@ use std::ptr;
 
 use log::debug;
 use rustc::bug;
-use rustc::session::Session;
 use rustc::ty::{self, DefIdTree};
 use rustc_ast::ast::{self, Ident, Path};
 use rustc_ast::util::lev_distance::find_best_match_for_name;
@@ -14,6 +13,7 @@ use rustc_feature::BUILTIN_ATTRIBUTES;
 use rustc_hir::def::Namespace::{self, *};
 use rustc_hir::def::{self, CtorKind, CtorOf, DefKind, NonMacroAttrKind};
 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
+use rustc_session::Session;
 use rustc_span::hygiene::MacroKind;
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::{kw, Symbol};
diff --git a/src/librustc_resolve/imports.rs b/src/librustc_resolve/imports.rs
index 681c039211892..663e61ad2add4 100644
--- a/src/librustc_resolve/imports.rs
+++ b/src/librustc_resolve/imports.rs
@@ -10,7 +10,6 @@ use crate::{CrateLint, Module, ModuleOrUniformRoot, ParentScope, PerNS, ScopeSet
 use crate::{NameBinding, NameBindingKind, PathResult, PrivacyError, ToNameBinding};
 
 use rustc::hir::exports::Export;
-use rustc::lint::builtin::{PUB_USE_OF_PRIVATE_EXTERN_CRATE, UNUSED_IMPORTS};
 use rustc::ty;
 use rustc::{bug, span_bug};
 use rustc_ast::ast::{Ident, Name, NodeId};
@@ -21,6 +20,7 @@ use rustc_data_structures::ptr_key::PtrKey;
 use rustc_errors::{pluralize, struct_span_err, Applicability};
 use rustc_hir::def::{self, PartialRes};
 use rustc_hir::def_id::DefId;
+use rustc_session::lint::builtin::{PUB_USE_OF_PRIVATE_EXTERN_CRATE, UNUSED_IMPORTS};
 use rustc_session::lint::BuiltinLintDiagnostics;
 use rustc_session::DiagnosticMessageId;
 use rustc_span::hygiene::ExpnId;
diff --git a/src/librustc_resolve/late.rs b/src/librustc_resolve/late.rs
index 867aa8c632168..4a3c9f338d903 100644
--- a/src/librustc_resolve/late.rs
+++ b/src/librustc_resolve/late.rs
@@ -11,7 +11,7 @@ use crate::{path_names_to_string, BindingError, CrateLint, LexicalScopeBinding};
 use crate::{Module, ModuleOrUniformRoot, NameBindingKind, ParentScope, PathResult};
 use crate::{ResolutionError, Resolver, Segment, UseError};
 
-use rustc::{bug, lint, span_bug};
+use rustc::{bug, span_bug};
 use rustc_ast::ast::*;
 use rustc_ast::ptr::P;
 use rustc_ast::util::lev_distance::find_best_match_for_name;
@@ -23,6 +23,7 @@ use rustc_hir::def::Namespace::{self, *};
 use rustc_hir::def::{self, CtorKind, DefKind, PartialRes, PerNS};
 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
 use rustc_hir::TraitCandidate;
+use rustc_session::lint;
 use rustc_span::symbol::{kw, sym};
 use rustc_span::Span;
 use smallvec::{smallvec, SmallVec};
diff --git a/src/librustc_resolve/late/diagnostics.rs b/src/librustc_resolve/late/diagnostics.rs
index 13d433052809d..41380b2a4b78a 100644
--- a/src/librustc_resolve/late/diagnostics.rs
+++ b/src/librustc_resolve/late/diagnostics.rs
@@ -5,7 +5,6 @@ use crate::path_names_to_string;
 use crate::{CrateLint, Module, ModuleKind, ModuleOrUniformRoot};
 use crate::{PathResult, PathSource, Segment};
 
-use rustc::session::config::nightly_options;
 use rustc_ast::ast::{self, Expr, ExprKind, Ident, Item, ItemKind, NodeId, Path, Ty, TyKind};
 use rustc_ast::util::lev_distance::find_best_match_for_name;
 use rustc_data_structures::fx::FxHashSet;
@@ -15,6 +14,7 @@ use rustc_hir::def::Namespace::{self, *};
 use rustc_hir::def::{self, CtorKind, DefKind};
 use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
 use rustc_hir::PrimTy;
+use rustc_session::config::nightly_options;
 use rustc_span::hygiene::MacroKind;
 use rustc_span::symbol::{kw, sym};
 use rustc_span::Span;
diff --git a/src/librustc_resolve/late/lifetimes.rs b/src/librustc_resolve/late/lifetimes.rs
index c015841cdc52b..47d04964842e4 100644
--- a/src/librustc_resolve/late/lifetimes.rs
+++ b/src/librustc_resolve/late/lifetimes.rs
@@ -7,7 +7,6 @@
 
 use crate::late::diagnostics::{ForLifetimeSpanType, MissingLifetimeSpot};
 use rustc::hir::map::Map;
-use rustc::lint;
 use rustc::middle::resolve_lifetime::*;
 use rustc::ty::{self, DefIdTree, GenericParamDefKind, TyCtxt};
 use rustc::{bug, span_bug};
@@ -22,6 +21,7 @@ use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, LOCAL_CRATE};
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::{GenericArg, GenericParam, LifetimeName, Node, ParamName, QPath};
 use rustc_hir::{GenericParamKind, HirIdMap, HirIdSet, LifetimeParamKind};
+use rustc_session::lint;
 use rustc_span::symbol::{kw, sym};
 use rustc_span::Span;
 use std::borrow::Cow;
@@ -1123,7 +1123,7 @@ fn extract_labels(ctxt: &mut LifetimeContext<'_, '_>, body: &hir::Body<'_>) {
     gather.visit_body(body);
 
     impl<'v, 'a, 'tcx> Visitor<'v> for GatherLabels<'a, 'tcx> {
-        type Map = Map<'v>;
+        type Map = intravisit::ErasedMap<'v>;
 
         fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
             NestedVisitorMap::None
@@ -2173,7 +2173,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
             }
 
             impl<'a> Visitor<'a> for SelfVisitor<'a> {
-                type Map = Map<'a>;
+                type Map = intravisit::ErasedMap<'a>;
 
                 fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
                     NestedVisitorMap::None
@@ -2264,7 +2264,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
         }
 
         impl<'v, 'a> Visitor<'v> for GatherLifetimes<'a> {
-            type Map = Map<'v>;
+            type Map = intravisit::ErasedMap<'v>;
 
             fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
                 NestedVisitorMap::None
@@ -2855,7 +2855,7 @@ fn insert_late_bound_lifetimes(
     }
 
     impl<'v> Visitor<'v> for ConstrainedCollector {
-        type Map = Map<'v>;
+        type Map = intravisit::ErasedMap<'v>;
 
         fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
             NestedVisitorMap::None
@@ -2898,7 +2898,7 @@ fn insert_late_bound_lifetimes(
     }
 
     impl<'v> Visitor<'v> for AllCollector {
-        type Map = Map<'v>;
+        type Map = intravisit::ErasedMap<'v>;
 
         fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
             NestedVisitorMap::None
diff --git a/src/librustc_resolve/lib.rs b/src/librustc_resolve/lib.rs
index 1ad4fb78e0820..8164998d55fd7 100644
--- a/src/librustc_resolve/lib.rs
+++ b/src/librustc_resolve/lib.rs
@@ -18,7 +18,6 @@ use Determinacy::*;
 
 use rustc::hir::exports::ExportMap;
 use rustc::hir::map::{DefKey, Definitions};
-use rustc::lint;
 use rustc::middle::cstore::{CrateStore, MetadataLoaderDyn};
 use rustc::span_bug;
 use rustc::ty::query::Providers;
@@ -42,6 +41,7 @@ use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, CRATE_DEF_INDEX, LOCAL_CRATE}
 use rustc_hir::PrimTy::{self, Bool, Char, Float, Int, Str, Uint};
 use rustc_hir::{GlobMap, TraitMap};
 use rustc_metadata::creader::{CStore, CrateLoader};
+use rustc_session::lint;
 use rustc_session::lint::{BuiltinLintDiagnostics, LintBuffer};
 use rustc_session::Session;
 use rustc_span::hygiene::{ExpnId, ExpnKind, MacroKind, SyntaxContext, Transparency};
diff --git a/src/librustc_resolve/macros.rs b/src/librustc_resolve/macros.rs
index 6c2a9cd8b10d9..6f2e0bce3acaf 100644
--- a/src/librustc_resolve/macros.rs
+++ b/src/librustc_resolve/macros.rs
@@ -7,9 +7,7 @@ use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind, Determinacy};
 use crate::{CrateLint, ParentScope, ResolutionError, Resolver, Scope, ScopeSet, Weak};
 use crate::{ModuleKind, ModuleOrUniformRoot, NameBinding, PathResult, Segment, ToNameBinding};
 use rustc::middle::stability;
-use rustc::session::parse::feature_err;
-use rustc::session::Session;
-use rustc::{lint, span_bug, ty};
+use rustc::{span_bug, ty};
 use rustc_ast::ast::{self, Ident, NodeId};
 use rustc_ast_pretty::pprust;
 use rustc_attr::{self as attr, StabilityLevel};
@@ -21,6 +19,9 @@ use rustc_expand::expand::{AstFragment, AstFragmentKind, Invocation, InvocationK
 use rustc_feature::is_builtin_attr_name;
 use rustc_hir::def::{self, DefKind, NonMacroAttrKind};
 use rustc_hir::def_id;
+use rustc_session::lint::builtin::UNUSED_MACROS;
+use rustc_session::parse::feature_err;
+use rustc_session::Session;
 use rustc_span::edition::Edition;
 use rustc_span::hygiene::{self, ExpnData, ExpnId, ExpnKind};
 use rustc_span::symbol::{kw, sym, Symbol};
@@ -329,12 +330,7 @@ impl<'a> base::Resolver for Resolver<'a> {
 
     fn check_unused_macros(&mut self) {
         for (&node_id, &span) in self.unused_macros.iter() {
-            self.lint_buffer.buffer_lint(
-                lint::builtin::UNUSED_MACROS,
-                node_id,
-                span,
-                "unused macro definition",
-            );
+            self.lint_buffer.buffer_lint(UNUSED_MACROS, node_id, span, "unused macro definition");
         }
     }
 
diff --git a/src/librustc_save_analysis/Cargo.toml b/src/librustc_save_analysis/Cargo.toml
index 0f4cc4192b626..4717664b6ba80 100644
--- a/src/librustc_save_analysis/Cargo.toml
+++ b/src/librustc_save_analysis/Cargo.toml
@@ -18,6 +18,7 @@ rustc_hir = { path = "../librustc_hir" }
 rustc_parse = { path = "../librustc_parse" }
 serde_json = "1"
 rustc_ast = { path = "../librustc_ast" }
+rustc_session = { path = "../librustc_session" }
 rustc_span = { path = "../librustc_span" }
 rls-data = "0.19"
 rls-span = "0.5"
diff --git a/src/librustc_save_analysis/dump_visitor.rs b/src/librustc_save_analysis/dump_visitor.rs
index cf4a9e947be94..8d1a39eab89d8 100644
--- a/src/librustc_save_analysis/dump_visitor.rs
+++ b/src/librustc_save_analysis/dump_visitor.rs
@@ -13,7 +13,6 @@
 //! DumpVisitor walks the AST and processes it, and Dumper is used for
 //! recording the output.
 
-use rustc::session::config::Input;
 use rustc::span_bug;
 use rustc::ty::{self, DefIdTree, TyCtxt};
 use rustc_ast::ast::{self, Attribute, NodeId, PatKind};
@@ -25,6 +24,7 @@ use rustc_ast_pretty::pprust::{bounds_to_string, generic_params_to_string, ty_to
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir::def::{DefKind as HirDefKind, Res};
 use rustc_hir::def_id::DefId;
+use rustc_session::config::Input;
 use rustc_span::source_map::{respan, DUMMY_SP};
 use rustc_span::*;
 
diff --git a/src/librustc_save_analysis/lib.rs b/src/librustc_save_analysis/lib.rs
index 8b0120c34e03b..98d81c6252242 100644
--- a/src/librustc_save_analysis/lib.rs
+++ b/src/librustc_save_analysis/lib.rs
@@ -10,7 +10,6 @@ mod sig;
 
 use rustc::middle::cstore::ExternCrate;
 use rustc::middle::privacy::AccessLevels;
-use rustc::session::config::{CrateType, Input, OutputType};
 use rustc::ty::{self, DefIdTree, TyCtxt};
 use rustc::{bug, span_bug};
 use rustc_ast::ast::{self, Attribute, NodeId, PatKind, DUMMY_NODE_ID};
@@ -22,6 +21,7 @@ use rustc_hir as hir;
 use rustc_hir::def::{CtorOf, DefKind as HirDefKind, Res};
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_hir::Node;
+use rustc_session::config::{CrateType, Input, OutputType};
 use rustc_span::source_map::Spanned;
 use rustc_span::*;
 
diff --git a/src/librustc_save_analysis/span_utils.rs b/src/librustc_save_analysis/span_utils.rs
index 152435206fec4..6620941c44046 100644
--- a/src/librustc_save_analysis/span_utils.rs
+++ b/src/librustc_save_analysis/span_utils.rs
@@ -1,7 +1,7 @@
 use crate::generated_code;
-use rustc::session::Session;
 use rustc_ast::token::{self, TokenKind};
 use rustc_parse::lexer::{self, StringReader};
+use rustc_session::Session;
 use rustc_span::*;
 
 #[derive(Clone)]
diff --git a/src/librustc_span/def_id.rs b/src/librustc_span/def_id.rs
index a2944782e91d4..af8d5ce09b52d 100644
--- a/src/librustc_span/def_id.rs
+++ b/src/librustc_span/def_id.rs
@@ -25,7 +25,7 @@ pub enum CrateNum {
 
 /// Item definitions in the currently-compiled crate would have the `CrateNum`
 /// `LOCAL_CRATE` in their `DefId`.
-pub const LOCAL_CRATE: CrateNum = CrateNum::Index(CrateId::from_u32_const(0));
+pub const LOCAL_CRATE: CrateNum = CrateNum::Index(CrateId::from_u32(0));
 
 impl Idx for CrateNum {
     #[inline]
diff --git a/src/librustc_span/lib.rs b/src/librustc_span/lib.rs
index caa50e9a41c0c..1f6d10f4e8f6a 100644
--- a/src/librustc_span/lib.rs
+++ b/src/librustc_span/lib.rs
@@ -6,6 +6,9 @@
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![feature(crate_visibility_modifier)]
+#![feature(const_if_match)]
+#![feature(const_fn)]
+#![feature(const_panic)]
 #![feature(nll)]
 #![feature(optin_builtin_traits)]
 #![feature(specialization)]
diff --git a/src/librustc_span/symbol.rs b/src/librustc_span/symbol.rs
index 19754c83038e2..5685505f6948d 100644
--- a/src/librustc_span/symbol.rs
+++ b/src/librustc_span/symbol.rs
@@ -1026,7 +1026,7 @@ rustc_index::newtype_index! {
 
 impl Symbol {
     const fn new(n: u32) -> Self {
-        Symbol(SymbolIndex::from_u32_const(n))
+        Symbol(SymbolIndex::from_u32(n))
     }
 
     /// Maps a string to its interned representation.
diff --git a/src/librustc_target/lib.rs b/src/librustc_target/lib.rs
index 3c397eb444d1d..98190867d493f 100644
--- a/src/librustc_target/lib.rs
+++ b/src/librustc_target/lib.rs
@@ -9,6 +9,9 @@
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![feature(bool_to_option)]
+#![feature(const_if_match)]
+#![feature(const_fn)]
+#![feature(const_panic)]
 #![feature(nll)]
 #![feature(never_type)]
 #![feature(associated_type_bounds)]
diff --git a/src/librustc_trait_selection/opaque_types.rs b/src/librustc_trait_selection/opaque_types.rs
index 6cf1302783c0b..785d8b892bee5 100644
--- a/src/librustc_trait_selection/opaque_types.rs
+++ b/src/librustc_trait_selection/opaque_types.rs
@@ -1,6 +1,5 @@
 use crate::infer::InferCtxtExt as _;
 use crate::traits::{self, PredicateObligation};
-use rustc::session::config::nightly_options;
 use rustc::ty::fold::{BottomUpFolder, TypeFoldable, TypeFolder, TypeVisitor};
 use rustc::ty::free_region_map::FreeRegionRelations;
 use rustc::ty::subst::{GenericArg, GenericArgKind, InternalSubsts, SubstsRef};
@@ -13,6 +12,7 @@ use rustc_hir::Node;
 use rustc_infer::infer::error_reporting::unexpected_hidden_region_diagnostic;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::{self, InferCtxt, InferOk};
+use rustc_session::config::nightly_options;
 use rustc_span::Span;
 
 pub type OpaqueTypeMap<'tcx> = DefIdMap<OpaqueTypeDecl<'tcx>>;
diff --git a/src/librustc_trait_selection/traits/error_reporting/mod.rs b/src/librustc_trait_selection/traits/error_reporting/mod.rs
index 46654a4e8b4ae..ef62958a3f7d0 100644
--- a/src/librustc_trait_selection/traits/error_reporting/mod.rs
+++ b/src/librustc_trait_selection/traits/error_reporting/mod.rs
@@ -12,7 +12,6 @@ use crate::infer::error_reporting::{TyCategory, TypeAnnotationNeeded as ErrorCod
 use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use crate::infer::{self, InferCtxt, TyCtxtInferExt};
 use rustc::mir::interpret::ErrorHandled;
-use rustc::session::DiagnosticMessageId;
 use rustc::ty::error::ExpectedFound;
 use rustc::ty::fast_reject;
 use rustc::ty::fold::TypeFolder;
@@ -25,6 +24,7 @@ use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder}
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_hir::{Node, QPath, TyKind, WhereBoundPredicate, WherePredicate};
+use rustc_session::DiagnosticMessageId;
 use rustc_span::source_map::SourceMap;
 use rustc_span::{ExpnKind, Span, DUMMY_SP};
 use std::fmt;
diff --git a/src/librustc_trait_selection/traits/error_reporting/suggestions.rs b/src/librustc_trait_selection/traits/error_reporting/suggestions.rs
index 6fe6d7aab2832..dd03f9358c819 100644
--- a/src/librustc_trait_selection/traits/error_reporting/suggestions.rs
+++ b/src/librustc_trait_selection/traits/error_reporting/suggestions.rs
@@ -1567,7 +1567,7 @@ struct ReturnsVisitor<'v> {
 }
 
 impl<'v> Visitor<'v> for ReturnsVisitor<'v> {
-    type Map = rustc::hir::map::Map<'v>;
+    type Map = hir::intravisit::ErasedMap<'v>;
 
     fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
         hir::intravisit::NestedVisitorMap::None
diff --git a/src/librustc_trait_selection/traits/mod.rs b/src/librustc_trait_selection/traits/mod.rs
index 7b93982db974b..43a90c4a6c164 100644
--- a/src/librustc_trait_selection/traits/mod.rs
+++ b/src/librustc_trait_selection/traits/mod.rs
@@ -21,7 +21,7 @@ mod util;
 pub mod wf;
 
 use crate::infer::outlives::env::OutlivesEnvironment;
-use crate::infer::{InferCtxt, SuppressRegionErrors, TyCtxtInferExt};
+use crate::infer::{InferCtxt, RegionckMode, TyCtxtInferExt};
 use crate::traits::error_reporting::InferCtxtExt as _;
 use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
 use rustc::middle::region;
@@ -244,7 +244,7 @@ fn do_normalize_predicates<'tcx>(
             region_context,
             &region_scope_tree,
             &outlives_env,
-            SuppressRegionErrors::default(),
+            RegionckMode::default(),
         );
 
         let predicates = match infcx.fully_resolve(&predicates) {
diff --git a/src/librustc_ty/Cargo.toml b/src/librustc_ty/Cargo.toml
index 3c790bc4cb13d..cf0b4b82eea72 100644
--- a/src/librustc_ty/Cargo.toml
+++ b/src/librustc_ty/Cargo.toml
@@ -15,5 +15,6 @@ rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_hir = { path = "../librustc_hir" }
 rustc_infer = { path = "../librustc_infer" }
 rustc_span = { path = "../librustc_span" }
+rustc_session = { path = "../librustc_session" }
 rustc_target = { path = "../librustc_target" }
 rustc_trait_selection = { path = "../librustc_trait_selection" }
diff --git a/src/librustc_ty/ty.rs b/src/librustc_ty/ty.rs
index 387d1d9923da2..4b522997537b7 100644
--- a/src/librustc_ty/ty.rs
+++ b/src/librustc_ty/ty.rs
@@ -1,10 +1,10 @@
 use rustc::hir::map as hir_map;
-use rustc::session::CrateDisambiguator;
 use rustc::ty::subst::Subst;
 use rustc::ty::{self, ToPredicate, Ty, TyCtxt, WithConstness};
 use rustc_data_structures::svh::Svh;
 use rustc_hir as hir;
 use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
+use rustc_session::CrateDisambiguator;
 use rustc_span::symbol::Symbol;
 use rustc_span::Span;
 use rustc_trait_selection::traits;
diff --git a/src/librustc_typeck/Cargo.toml b/src/librustc_typeck/Cargo.toml
index 83a48ee3995ac..e61a36f844f87 100644
--- a/src/librustc_typeck/Cargo.toml
+++ b/src/librustc_typeck/Cargo.toml
@@ -19,6 +19,7 @@ rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_errors = { path = "../librustc_errors" }
 rustc_hir = { path = "../librustc_hir" }
 rustc_target = { path = "../librustc_target" }
+rustc_session = { path = "../librustc_session" }
 smallvec = { version = "1.0", features = ["union", "may_dangle"] }
 rustc_ast = { path = "../librustc_ast" }
 rustc_span = { path = "../librustc_span" }
diff --git a/src/librustc_typeck/astconv.rs b/src/librustc_typeck/astconv.rs
index b273efa78276d..9a8d161572bcf 100644
--- a/src/librustc_typeck/astconv.rs
+++ b/src/librustc_typeck/astconv.rs
@@ -6,13 +6,10 @@
 // ignore-tidy-filelength
 
 use crate::collect::PlaceholderHirTyCollector;
-use crate::lint;
 use crate::middle::lang_items::SizedTraitLangItem;
 use crate::middle::resolve_lifetime as rl;
 use crate::require_c_abi_if_c_variadic;
 use crate::util::common::ErrorReported;
-use rustc::lint::builtin::AMBIGUOUS_ASSOCIATED_ITEMS;
-use rustc::session::{parse::feature_err, Session};
 use rustc::ty::subst::{self, InternalSubsts, Subst, SubstsRef};
 use rustc::ty::{self, Const, DefIdTree, ToPredicate, Ty, TyCtxt, TypeFoldable, WithConstness};
 use rustc::ty::{GenericParamDef, GenericParamDefKind};
@@ -26,6 +23,9 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::Visitor;
 use rustc_hir::print;
 use rustc_hir::{Constness, ExprKind, GenericArg, GenericArgs};
+use rustc_session::lint::builtin::{AMBIGUOUS_ASSOCIATED_ITEMS, LATE_BOUND_LIFETIME_ARGUMENTS};
+use rustc_session::parse::feature_err;
+use rustc_session::Session;
 use rustc_span::symbol::sym;
 use rustc_span::{MultiSpan, Span, DUMMY_SP};
 use rustc_target::spec::abi;
@@ -33,8 +33,8 @@ use rustc_trait_selection::traits;
 use rustc_trait_selection::traits::astconv_object_safety_violations;
 use rustc_trait_selection::traits::error_reporting::report_object_safety_error;
 use rustc_trait_selection::traits::wf::object_region_bounds;
-use smallvec::SmallVec;
 
+use smallvec::SmallVec;
 use std::collections::BTreeSet;
 use std::iter;
 use std::slice;
@@ -340,7 +340,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     let mut multispan = MultiSpan::from_span(span);
                     multispan.push_span_label(span_late, note.to_string());
                     tcx.struct_span_lint_hir(
-                        lint::builtin::LATE_BOUND_LIFETIME_ARGUMENTS,
+                        LATE_BOUND_LIFETIME_ARGUMENTS,
                         args.args[0].id(),
                         multispan,
                         |lint| lint.build(msg).emit(),
diff --git a/src/librustc_typeck/check/autoderef.rs b/src/librustc_typeck/check/autoderef.rs
index 991347714e841..2315b42aec54c 100644
--- a/src/librustc_typeck/check/autoderef.rs
+++ b/src/librustc_typeck/check/autoderef.rs
@@ -1,19 +1,18 @@
 use super::method::MethodCallee;
 use super::{FnCtxt, Needs, PlaceOp};
 
-use rustc::session::DiagnosticMessageId;
 use rustc::ty::adjustment::{Adjust, Adjustment, OverloadedDeref};
 use rustc::ty::{self, TraitRef, Ty, TyCtxt, WithConstness};
 use rustc::ty::{ToPredicate, TypeFoldable};
+use rustc_ast::ast::Ident;
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_infer::infer::{InferCtxt, InferOk};
+use rustc_session::DiagnosticMessageId;
+use rustc_span::Span;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use rustc_trait_selection::traits::{self, TraitEngine};
 
-use rustc_ast::ast::Ident;
-use rustc_span::Span;
-
 use std::iter;
 
 #[derive(Copy, Clone, Debug)]
diff --git a/src/librustc_typeck/check/cast.rs b/src/librustc_typeck/check/cast.rs
index d52b6c39ab58d..2875d38a996a0 100644
--- a/src/librustc_typeck/check/cast.rs
+++ b/src/librustc_typeck/check/cast.rs
@@ -31,11 +31,9 @@
 use super::FnCtxt;
 
 use crate::hir::def_id::DefId;
-use crate::lint;
 use crate::type_error_struct;
 use crate::util::common::ErrorReported;
 use rustc::middle::lang_items;
-use rustc::session::Session;
 use rustc::ty::adjustment::AllowTwoPhase;
 use rustc::ty::cast::{CastKind, CastTy};
 use rustc::ty::error::TypeError;
@@ -44,6 +42,8 @@ use rustc::ty::{self, Ty, TypeAndMut, TypeFoldable};
 use rustc_ast::ast;
 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
 use rustc_hir as hir;
+use rustc_session::lint;
+use rustc_session::Session;
 use rustc_span::Span;
 use rustc_trait_selection::traits;
 use rustc_trait_selection::traits::error_reporting::report_object_safety_error;
diff --git a/src/librustc_typeck/check/coercion.rs b/src/librustc_typeck/check/coercion.rs
index d74623a063f8f..b0d74651847a9 100644
--- a/src/librustc_typeck/check/coercion.rs
+++ b/src/librustc_typeck/check/coercion.rs
@@ -52,7 +52,6 @@
 
 use crate::astconv::AstConv;
 use crate::check::{FnCtxt, Needs};
-use rustc::session::parse::feature_err;
 use rustc::ty::adjustment::{
     Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability, PointerCast,
 };
@@ -66,11 +65,13 @@ use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::{Coercion, InferOk, InferResult};
+use rustc_session::parse::feature_err;
 use rustc_span::symbol::sym;
 use rustc_span::{self, Span};
 use rustc_target::spec::abi::Abi;
 use rustc_trait_selection::traits::error_reporting::InferCtxtExt;
 use rustc_trait_selection::traits::{self, ObligationCause, ObligationCauseCode};
+
 use smallvec::{smallvec, SmallVec};
 use std::ops::Deref;
 
diff --git a/src/librustc_typeck/check/compare_method.rs b/src/librustc_typeck/check/compare_method.rs
index 779b87f662375..a2832d92d4aeb 100644
--- a/src/librustc_typeck/check/compare_method.rs
+++ b/src/librustc_typeck/check/compare_method.rs
@@ -1,4 +1,3 @@
-use rustc::hir::map::Map;
 use rustc::ty::error::{ExpectedFound, TypeError};
 use rustc::ty::subst::{InternalSubsts, Subst};
 use rustc::ty::util::ExplicitSelf;
@@ -890,7 +889,7 @@ fn compare_synthetic_generics<'tcx>(
                                     }
                                 }
                             }
-                            type Map = Map<'v>;
+                            type Map = intravisit::ErasedMap<'v>;
                             fn nested_visit_map(
                                 &mut self,
                             ) -> intravisit::NestedVisitorMap<Self::Map>
diff --git a/src/librustc_typeck/check/dropck.rs b/src/librustc_typeck/check/dropck.rs
index dca4f9e7cbe08..e48ebbbb23514 100644
--- a/src/librustc_typeck/check/dropck.rs
+++ b/src/librustc_typeck/check/dropck.rs
@@ -9,7 +9,7 @@ use rustc::ty::subst::{Subst, SubstsRef};
 use rustc::ty::{self, Predicate, Ty, TyCtxt};
 use rustc_errors::struct_span_err;
 use rustc_infer::infer::outlives::env::OutlivesEnvironment;
-use rustc_infer::infer::{InferOk, SuppressRegionErrors, TyCtxtInferExt};
+use rustc_infer::infer::{InferOk, RegionckMode, TyCtxtInferExt};
 use rustc_infer::traits::TraitEngineExt as _;
 use rustc_span::Span;
 use rustc_trait_selection::traits::error_reporting::InferCtxtExt;
@@ -139,7 +139,7 @@ fn ensure_drop_params_and_item_params_correspond<'tcx>(
             drop_impl_did,
             &region_scope_tree,
             &outlives_env,
-            SuppressRegionErrors::default(),
+            RegionckMode::default(),
         );
         Ok(())
     })
diff --git a/src/librustc_typeck/check/generator_interior.rs b/src/librustc_typeck/check/generator_interior.rs
index 5208e2f56a5c2..cdf68256a7a88 100644
--- a/src/librustc_typeck/check/generator_interior.rs
+++ b/src/librustc_typeck/check/generator_interior.rs
@@ -4,7 +4,6 @@
 //! types computed here.
 
 use super::FnCtxt;
-use rustc::hir::map::Map;
 use rustc::middle::region::{self, YieldData};
 use rustc::ty::{self, Ty};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
@@ -209,7 +208,7 @@ pub fn resolve_interior<'a, 'tcx>(
 // librustc/middle/region.rs since `expr_count` is compared against the results
 // there.
 impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
diff --git a/src/librustc_typeck/check/method/probe.rs b/src/librustc_typeck/check/method/probe.rs
index 16bab09feeef0..45b1c7d6ea740 100644
--- a/src/librustc_typeck/check/method/probe.rs
+++ b/src/librustc_typeck/check/method/probe.rs
@@ -8,9 +8,7 @@ use crate::check::FnCtxt;
 use crate::hir::def::DefKind;
 use crate::hir::def_id::DefId;
 
-use rustc::lint;
 use rustc::middle::stability;
-use rustc::session::config::nightly_options;
 use rustc::ty::subst::{InternalSubsts, Subst, SubstsRef};
 use rustc::ty::GenericParamDefKind;
 use rustc::ty::{
@@ -28,6 +26,8 @@ use rustc_infer::infer::canonical::{Canonical, QueryResponse};
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
 use rustc_infer::infer::{self, InferOk, TyCtxtInferExt};
+use rustc_session::config::nightly_options;
+use rustc_session::lint;
 use rustc_span::{symbol::Symbol, Span, DUMMY_SP};
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use rustc_trait_selection::traits::query::method_autoderef::MethodAutoderefBadTy;
diff --git a/src/librustc_typeck/check/method/suggest.rs b/src/librustc_typeck/check/method/suggest.rs
index 3eb3624a29665..94a582dfcfe80 100644
--- a/src/librustc_typeck/check/method/suggest.rs
+++ b/src/librustc_typeck/check/method/suggest.rs
@@ -4,7 +4,6 @@
 use crate::check::FnCtxt;
 use crate::middle::lang_items::FnOnceTraitLangItem;
 use rustc::hir::map as hir_map;
-use rustc::hir::map::Map;
 use rustc::ty::print::with_crate_prefix;
 use rustc::ty::{self, ToPolyTraitRef, ToPredicate, Ty, TyCtxt, TypeFoldable, WithConstness};
 use rustc_ast::ast;
@@ -1347,7 +1346,7 @@ impl intravisit::Visitor<'tcx> for UsePlacementFinder<'tcx> {
         }
     }
 
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
         intravisit::NestedVisitorMap::None
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 1766b688468f1..bfb0d25dea208 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -90,10 +90,8 @@ pub mod writeback;
 use crate::astconv::{AstConv, GenericArgCountMismatch, PathSeg};
 use crate::middle::lang_items;
 use rustc::hir::map::blocks::FnLikeNode;
-use rustc::hir::map::Map;
 use rustc::middle::region;
 use rustc::mir::interpret::ConstValue;
-use rustc::session::parse::feature_err;
 use rustc::ty::adjustment::{
     Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability, PointerCast,
 };
@@ -124,6 +122,10 @@ use rustc_infer::infer::error_reporting::TypeAnnotationNeeded::E0282;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
 use rustc_infer::infer::{self, InferCtxt, InferOk, InferResult, TyCtxtInferExt};
+use rustc_session::config::{self, EntryFnType};
+use rustc_session::lint;
+use rustc_session::parse::feature_err;
+use rustc_session::Session;
 use rustc_span::hygiene::DesugaringKind;
 use rustc_span::source_map::{original_sp, DUMMY_SP};
 use rustc_span::symbol::{kw, sym, Ident};
@@ -146,10 +148,7 @@ use std::mem::replace;
 use std::ops::{self, Deref};
 use std::slice;
 
-use crate::lint;
 use crate::require_c_abi_if_c_variadic;
-use crate::session::config::EntryFnType;
-use crate::session::Session;
 use crate::util::common::{indenter, ErrorReported};
 use crate::TypeAndSubsts;
 
@@ -1177,7 +1176,7 @@ impl<'a, 'tcx> GatherLocalsVisitor<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> Visitor<'tcx> for GatherLocalsVisitor<'a, 'tcx> {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
@@ -5790,7 +5789,7 @@ fn fatally_break_rust(sess: &Session) {
     handler.note_without_error(&format!(
         "rustc {} running on {}",
         option_env!("CFG_VERSION").unwrap_or("unknown_version"),
-        crate::session::config::host_triple(),
+        config::host_triple(),
     ));
 }
 
diff --git a/src/librustc_typeck/check/regionck.rs b/src/librustc_typeck/check/regionck.rs
index 975c6e101a691..57a89614eb18c 100644
--- a/src/librustc_typeck/check/regionck.rs
+++ b/src/librustc_typeck/check/regionck.rs
@@ -76,7 +76,6 @@ use crate::check::dropck;
 use crate::check::FnCtxt;
 use crate::mem_categorization as mc;
 use crate::middle::region;
-use rustc::hir::map::Map;
 use rustc::ty::adjustment;
 use rustc::ty::subst::{GenericArgKind, SubstsRef};
 use rustc::ty::{self, Ty};
@@ -85,7 +84,7 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::PatKind;
 use rustc_infer::infer::outlives::env::OutlivesEnvironment;
-use rustc_infer::infer::{self, RegionObligation, SuppressRegionErrors};
+use rustc_infer::infer::{self, RegionObligation, RegionckMode};
 use rustc_span::Span;
 use rustc_trait_selection::infer::OutlivesEnvironmentExt;
 use rustc_trait_selection::opaque_types::InferCtxtExt;
@@ -124,10 +123,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             rcx.visit_body(body);
             rcx.visit_region_obligations(id);
         }
-        rcx.resolve_regions_and_report_errors(SuppressRegionErrors::when_nll_is_enabled(self.tcx));
-
-        assert!(self.tables.borrow().free_region_map.is_empty());
-        self.tables.borrow_mut().free_region_map = rcx.outlives_environment.into_free_region_map();
+        rcx.resolve_regions_and_report_errors(RegionckMode::for_item_body(self.tcx));
     }
 
     /// Region checking during the WF phase for items. `wf_tys` are the
@@ -145,7 +141,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         rcx.outlives_environment.add_implied_bounds(self, wf_tys, item_id, span);
         rcx.outlives_environment.save_implied_bounds(item_id);
         rcx.visit_region_obligations(item_id);
-        rcx.resolve_regions_and_report_errors(SuppressRegionErrors::default());
+        rcx.resolve_regions_and_report_errors(RegionckMode::default());
     }
 
     /// Region check a function body. Not invoked on closures, but
@@ -168,13 +164,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             rcx.visit_fn_body(fn_id, body, self.tcx.hir().span(fn_id));
         }
 
-        rcx.resolve_regions_and_report_errors(SuppressRegionErrors::when_nll_is_enabled(self.tcx));
-
-        // In this mode, we also copy the free-region-map into the
-        // tables of the enclosing fcx. In the other regionck modes
-        // (e.g., `regionck_item`), we don't have an enclosing tables.
-        assert!(self.tables.borrow().free_region_map.is_empty());
-        self.tables.borrow_mut().free_region_map = rcx.outlives_environment.into_free_region_map();
+        rcx.resolve_regions_and_report_errors(RegionckMode::for_item_body(self.tcx));
     }
 }
 
@@ -355,7 +345,7 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
         self.select_all_obligations_or_error();
     }
 
-    fn resolve_regions_and_report_errors(&self, suppress: SuppressRegionErrors) {
+    fn resolve_regions_and_report_errors(&self, mode: RegionckMode) {
         self.infcx.process_registered_region_obligations(
             self.outlives_environment.region_bound_pairs_map(),
             self.implicit_region_bound,
@@ -366,7 +356,7 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
             self.subject_def_id,
             &self.region_scope_tree,
             &self.outlives_environment,
-            suppress,
+            mode,
         );
     }
 
@@ -417,7 +407,7 @@ impl<'a, 'tcx> Visitor<'tcx> for RegionCtxt<'a, 'tcx> {
     // hierarchy, and in particular the relationships between free
     // regions, until regionck, as described in #3238.
 
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
diff --git a/src/librustc_typeck/check/upvar.rs b/src/librustc_typeck/check/upvar.rs
index 7bc121733a4e6..44b960ad22bff 100644
--- a/src/librustc_typeck/check/upvar.rs
+++ b/src/librustc_typeck/check/upvar.rs
@@ -35,7 +35,6 @@ use super::FnCtxt;
 use crate::expr_use_visitor as euv;
 use crate::mem_categorization as mc;
 use crate::mem_categorization::PlaceBase;
-use rustc::hir::map::Map;
 use rustc::ty::{self, Ty, TyCtxt, UpvarSubsts};
 use rustc_ast::ast;
 use rustc_data_structures::fx::FxIndexMap;
@@ -60,7 +59,7 @@ struct InferBorrowKindVisitor<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> Visitor<'tcx> for InferBorrowKindVisitor<'a, 'tcx> {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
diff --git a/src/librustc_typeck/check/wfcheck.rs b/src/librustc_typeck/check/wfcheck.rs
index e4a57f6619628..3255d7b435c8f 100644
--- a/src/librustc_typeck/check/wfcheck.rs
+++ b/src/librustc_typeck/check/wfcheck.rs
@@ -2,7 +2,6 @@ use crate::check::{FnCtxt, Inherited};
 use crate::constrained_generic_params::{identify_constrained_generic_params, Parameter};
 
 use rustc::middle::lang_items;
-use rustc::session::parse::feature_err;
 use rustc::ty::subst::{InternalSubsts, Subst};
 use rustc::ty::trait_def::TraitSpecializationKind;
 use rustc::ty::{
@@ -11,17 +10,17 @@ use rustc::ty::{
 use rustc_ast::ast;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
+use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
+use rustc_hir::itemlikevisit::ParItemLikeVisitor;
 use rustc_hir::ItemKind;
+use rustc_session::parse::feature_err;
 use rustc_span::symbol::sym;
 use rustc_span::Span;
 use rustc_trait_selection::opaque_types::may_define_opaque_type;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use rustc_trait_selection::traits::{self, ObligationCause, ObligationCauseCode};
 
-use rustc_hir as hir;
-use rustc_hir::itemlikevisit::ParItemLikeVisitor;
-
 /// Helper type of a temporary returned by `.for_item(...)`.
 /// This is necessary because we can't write the following bound:
 ///
diff --git a/src/librustc_typeck/check/writeback.rs b/src/librustc_typeck/check/writeback.rs
index b8f8030e3cdd7..9d574ee50a4c5 100644
--- a/src/librustc_typeck/check/writeback.rs
+++ b/src/librustc_typeck/check/writeback.rs
@@ -4,7 +4,6 @@
 
 use crate::check::FnCtxt;
 
-use rustc::hir::map::Map;
 use rustc::ty::adjustment::{Adjust, Adjustment, PointerCast};
 use rustc::ty::fold::{TypeFoldable, TypeFolder};
 use rustc::ty::{self, Ty, TyCtxt};
@@ -62,7 +61,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         wbcx.visit_fru_field_types();
         wbcx.visit_opaque_types(body.value.span);
         wbcx.visit_coercion_casts();
-        wbcx.visit_free_region_map();
         wbcx.visit_user_provided_tys();
         wbcx.visit_user_provided_sigs();
         wbcx.visit_generator_interior_types();
@@ -125,7 +123,7 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
 
     fn write_ty_to_tables(&mut self, hir_id: hir::HirId, ty: Ty<'tcx>) {
         debug!("write_ty_to_tables({:?}, {:?})", hir_id, ty);
-        assert!(!ty.needs_infer() && !ty.has_placeholders());
+        assert!(!ty.needs_infer() && !ty.has_placeholders() && !ty.has_free_regions());
         self.tables.node_types_mut().insert(hir_id, ty);
     }
 
@@ -244,7 +242,7 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
 // traffic in node-ids or update tables in the type context etc.
 
 impl<'cx, 'tcx> Visitor<'tcx> for WritebackCx<'cx, 'tcx> {
-    type Map = Map<'tcx>;
+    type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
@@ -327,9 +325,10 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
             let new_upvar_capture = match *upvar_capture {
                 ty::UpvarCapture::ByValue => ty::UpvarCapture::ByValue,
                 ty::UpvarCapture::ByRef(ref upvar_borrow) => {
-                    let r = upvar_borrow.region;
-                    let r = self.resolve(&r, &upvar_id.var_path.hir_id);
-                    ty::UpvarCapture::ByRef(ty::UpvarBorrow { kind: upvar_borrow.kind, region: r })
+                    ty::UpvarCapture::ByRef(ty::UpvarBorrow {
+                        kind: upvar_borrow.kind,
+                        region: self.tcx().lifetimes.re_erased,
+                    })
                 }
             };
             debug!("Upvar capture for {:?} resolved to {:?}", upvar_id, new_upvar_capture);
@@ -358,11 +357,6 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
         }
     }
 
-    fn visit_free_region_map(&mut self) {
-        self.tables.free_region_map = self.fcx.tables.borrow().free_region_map.clone();
-        debug_assert!(!self.tables.free_region_map.elements().any(|r| r.has_local_value()));
-    }
-
     fn visit_user_provided_tys(&mut self) {
         let fcx_tables = self.fcx.tables.borrow();
         debug_assert_eq!(fcx_tables.local_id_root, self.tables.local_id_root);
@@ -427,8 +421,7 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
     fn visit_opaque_types(&mut self, span: Span) {
         for (&def_id, opaque_defn) in self.fcx.opaque_types.borrow().iter() {
             let hir_id = self.tcx().hir().as_local_hir_id(def_id).unwrap();
-            let instantiated_ty =
-                self.tcx().erase_regions(&self.resolve(&opaque_defn.concrete_ty, &hir_id));
+            let instantiated_ty = self.resolve(&opaque_defn.concrete_ty, &hir_id);
 
             debug_assert!(!instantiated_ty.has_escaping_bound_vars());
 
@@ -617,10 +610,8 @@ impl Locatable for hir::HirId {
     }
 }
 
-///////////////////////////////////////////////////////////////////////////
-// The Resolver. This is the type folding engine that detects
-// unresolved types and so forth.
-
+/// The Resolver. This is the type folding engine that detects
+/// unresolved types and so forth.
 struct Resolver<'cx, 'tcx> {
     tcx: TyCtxt<'tcx>,
     infcx: &'cx InferCtxt<'cx, 'tcx>,
@@ -653,7 +644,7 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for Resolver<'cx, 'tcx> {
 
     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
         match self.infcx.fully_resolve(&t) {
-            Ok(t) => t,
+            Ok(t) => self.infcx.tcx.erase_regions(&t),
             Err(_) => {
                 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable", t);
                 self.report_error(t);
@@ -662,15 +653,14 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for Resolver<'cx, 'tcx> {
         }
     }
 
-    // FIXME This should be carefully checked
-    // We could use `self.report_error` but it doesn't accept a ty::Region, right now.
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
-        self.infcx.fully_resolve(&r).unwrap_or(self.tcx.lifetimes.re_static)
+        debug_assert!(!r.is_late_bound(), "Should not be resolving bound region.");
+        self.tcx.lifetimes.re_erased
     }
 
     fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
         match self.infcx.fully_resolve(&ct) {
-            Ok(ct) => ct,
+            Ok(ct) => self.infcx.tcx.erase_regions(&ct),
             Err(_) => {
                 debug!("Resolver::fold_const: input const `{:?}` not fully resolvable", ct);
                 // FIXME: we'd like to use `self.report_error`, but it doesn't yet
diff --git a/src/librustc_typeck/check_unused.rs b/src/librustc_typeck/check_unused.rs
index 3517e09133c28..d0414af5b2138 100644
--- a/src/librustc_typeck/check_unused.rs
+++ b/src/librustc_typeck/check_unused.rs
@@ -1,4 +1,3 @@
-use crate::lint;
 use rustc::ty::TyCtxt;
 use rustc_ast::ast;
 use rustc_data_structures::fx::FxHashMap;
@@ -7,6 +6,7 @@ use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, DefIdSet, LOCAL_CRATE};
 use rustc_hir::itemlikevisit::ItemLikeVisitor;
 use rustc_hir::print::visibility_qualified;
+use rustc_session::lint;
 use rustc_span::Span;
 
 pub fn check_crate(tcx: TyCtxt<'_>) {
diff --git a/src/librustc_typeck/coherence/builtin.rs b/src/librustc_typeck/coherence/builtin.rs
index 2ea7601ae6538..e24d9bebf657f 100644
--- a/src/librustc_typeck/coherence/builtin.rs
+++ b/src/librustc_typeck/coherence/builtin.rs
@@ -12,7 +12,7 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::ItemKind;
 use rustc_infer::infer;
 use rustc_infer::infer::outlives::env::OutlivesEnvironment;
-use rustc_infer::infer::{SuppressRegionErrors, TyCtxtInferExt};
+use rustc_infer::infer::{RegionckMode, TyCtxtInferExt};
 use rustc_trait_selection::traits::error_reporting::InferCtxtExt;
 use rustc_trait_selection::traits::misc::{can_type_implement_copy, CopyImplementationError};
 use rustc_trait_selection::traits::predicate_for_trait_def;
@@ -307,7 +307,7 @@ fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: DefId) {
                             impl_did,
                             &region_scope_tree,
                             &outlives_env,
-                            SuppressRegionErrors::default(),
+                            RegionckMode::default(),
                         );
                     }
                 }
@@ -568,7 +568,7 @@ pub fn coerce_unsized_info(tcx: TyCtxt<'tcx>, impl_did: DefId) -> CoerceUnsizedI
             impl_did,
             &region_scope_tree,
             &outlives_env,
-            SuppressRegionErrors::default(),
+            RegionckMode::default(),
         );
 
         CoerceUnsizedInfo { custom_kind: kind }
diff --git a/src/librustc_typeck/collect.rs b/src/librustc_typeck/collect.rs
index 8e60bd2a4b3e8..7145b948f2f5a 100644
--- a/src/librustc_typeck/collect.rs
+++ b/src/librustc_typeck/collect.rs
@@ -17,14 +17,12 @@
 use crate::astconv::{AstConv, Bounds, SizedByDefault};
 use crate::check::intrinsic::intrinsic_operation_unsafety;
 use crate::constrained_generic_params as cgp;
-use crate::lint;
 use crate::middle::lang_items;
 use crate::middle::resolve_lifetime as rl;
 use rustc::hir::map::blocks::FnLikeNode;
 use rustc::hir::map::Map;
 use rustc::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
 use rustc::mir::mono::Linkage;
-use rustc::session::parse::feature_err;
 use rustc::ty::query::Providers;
 use rustc::ty::subst::{InternalSubsts, Subst};
 use rustc::ty::util::Discr;
@@ -42,6 +40,8 @@ use rustc_hir::def::{CtorKind, DefKind, Res};
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::{GenericParamKind, Node, Unsafety};
+use rustc_session::lint;
+use rustc_session::parse::feature_err;
 use rustc_span::symbol::{kw, sym, Symbol};
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::spec::abi;
@@ -105,7 +105,7 @@ pub struct ItemCtxt<'tcx> {
 crate struct PlaceholderHirTyCollector(crate Vec<Span>);
 
 impl<'v> Visitor<'v> for PlaceholderHirTyCollector {
-    type Map = Map<'v>;
+    type Map = intravisit::ErasedMap<'v>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
         NestedVisitorMap::None
@@ -1060,7 +1060,7 @@ fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<S
     }
 
     impl Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
-        type Map = Map<'tcx>;
+        type Map = intravisit::ErasedMap<'tcx>;
 
         fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
             NestedVisitorMap::None
diff --git a/src/librustc_typeck/collect/type_of.rs b/src/librustc_typeck/collect/type_of.rs
index c5d3d276721ff..41c205bc11b35 100644
--- a/src/librustc_typeck/collect/type_of.rs
+++ b/src/librustc_typeck/collect/type_of.rs
@@ -1,5 +1,4 @@
 use rustc::hir::map::Map;
-use rustc::session::parse::feature_err;
 use rustc::ty::subst::{GenericArgKind, InternalSubsts, Subst};
 use rustc::ty::util::IntTypeExt;
 use rustc::ty::{self, DefIdTree, Ty, TyCtxt, TypeFoldable};
@@ -11,6 +10,7 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit;
 use rustc_hir::intravisit::Visitor;
 use rustc_hir::Node;
+use rustc_session::parse::feature_err;
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::{Span, DUMMY_SP};
 use rustc_trait_selection::traits;
diff --git a/src/librustc_typeck/impl_wf_check/min_specialization.rs b/src/librustc_typeck/impl_wf_check/min_specialization.rs
index e96a8c454b8c7..cae8837611846 100644
--- a/src/librustc_typeck/impl_wf_check/min_specialization.rs
+++ b/src/librustc_typeck/impl_wf_check/min_specialization.rs
@@ -75,7 +75,7 @@ use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_infer::infer::outlives::env::OutlivesEnvironment;
-use rustc_infer::infer::{InferCtxt, SuppressRegionErrors, TyCtxtInferExt};
+use rustc_infer::infer::{InferCtxt, RegionckMode, TyCtxtInferExt};
 use rustc_infer::traits::specialization_graph::Node;
 use rustc_span::Span;
 use rustc_trait_selection::traits::{self, translate_substs, wf};
@@ -162,7 +162,7 @@ fn get_impl_substs<'tcx>(
         impl1_def_id,
         &ScopeTree::default(),
         &outlives_env,
-        SuppressRegionErrors::default(),
+        RegionckMode::default(),
     );
     let impl2_substs = match infcx.fully_resolve(&impl2_substs) {
         Ok(s) => s,
diff --git a/src/librustc_typeck/lib.rs b/src/librustc_typeck/lib.rs
index bab354cff7c9c..e487e0d265c3e 100644
--- a/src/librustc_typeck/lib.rs
+++ b/src/librustc_typeck/lib.rs
@@ -88,10 +88,7 @@ mod outlives;
 mod structured_errors;
 mod variance;
 
-use rustc::lint;
 use rustc::middle;
-use rustc::session;
-use rustc::session::config::EntryFnType;
 use rustc::ty::query::Providers;
 use rustc::ty::subst::SubstsRef;
 use rustc::ty::{self, Ty, TyCtxt};
@@ -103,6 +100,7 @@ use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_hir::Node;
 use rustc_infer::infer::{InferOk, TyCtxtInferExt};
 use rustc_infer::traits::TraitEngineExt as _;
+use rustc_session::config::EntryFnType;
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::spec::abi::Abi;
 use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
diff --git a/src/librustc_typeck/structured_errors.rs b/src/librustc_typeck/structured_errors.rs
index 99b7b2001a9e9..a4f8472ae2891 100644
--- a/src/librustc_typeck/structured_errors.rs
+++ b/src/librustc_typeck/structured_errors.rs
@@ -1,6 +1,6 @@
-use rustc::session::Session;
 use rustc::ty::{Ty, TypeFoldable};
 use rustc_errors::{Applicability, DiagnosticBuilder, DiagnosticId};
+use rustc_session::Session;
 use rustc_span::Span;
 
 pub trait StructuredDiagnostic<'tcx> {
diff --git a/src/librustdoc/config.rs b/src/librustdoc/config.rs
index 58c8a7d82bfb5..179c5bfacf32e 100644
--- a/src/librustdoc/config.rs
+++ b/src/librustdoc/config.rs
@@ -4,15 +4,14 @@ use std::ffi::OsStr;
 use std::fmt;
 use std::path::PathBuf;
 
-use rustc::lint::Level;
-use rustc::session;
-use rustc::session::config::{
+use rustc_session::config::{self, parse_crate_types_from_list, parse_externs, CrateType};
+use rustc_session::config::{
     build_codegen_options, build_debugging_options, get_cmd_lint_options, host_triple,
     nightly_options,
 };
-use rustc::session::config::{parse_crate_types_from_list, parse_externs, CrateType};
-use rustc::session::config::{CodegenOptions, DebuggingOptions, ErrorOutputType, Externs};
-use rustc::session::search_paths::SearchPath;
+use rustc_session::config::{CodegenOptions, DebuggingOptions, ErrorOutputType, Externs};
+use rustc_session::lint::Level;
+use rustc_session::search_paths::SearchPath;
 use rustc_span::edition::{Edition, DEFAULT_EDITION};
 use rustc_target::spec::TargetTriple;
 
@@ -299,9 +298,9 @@ impl Options {
             return Err(0);
         }
 
-        let color = session::config::parse_color(&matches);
-        let (json_rendered, _artifacts) = session::config::parse_json(&matches);
-        let error_format = session::config::parse_error_format(&matches, color, json_rendered);
+        let color = config::parse_color(&matches);
+        let (json_rendered, _artifacts) = config::parse_json(&matches);
+        let error_format = config::parse_error_format(&matches, color, json_rendered);
 
         let codegen_options = build_codegen_options(matches, error_format);
         let debugging_options = build_debugging_options(matches, error_format);
diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
index b9ae3d53afc04..f0b9ad2852f51 100644
--- a/src/librustdoc/core.rs
+++ b/src/librustdoc/core.rs
@@ -1,23 +1,22 @@
 use rustc::middle::cstore::CrateStore;
 use rustc::middle::privacy::AccessLevels;
-use rustc::session::config::ErrorOutputType;
-use rustc::session::DiagnosticOutput;
-use rustc::session::{self, config};
 use rustc::ty::{Ty, TyCtxt};
+use rustc_ast::ast::CRATE_NODE_ID;
+use rustc_attr as attr;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_driver::abort_on_err;
+use rustc_errors::emitter::{Emitter, EmitterWriter};
+use rustc_errors::json::JsonEmitter;
 use rustc_feature::UnstableFeatures;
 use rustc_hir::def::Namespace::TypeNS;
 use rustc_hir::def_id::{CrateNum, DefId, DefIndex, LOCAL_CRATE};
 use rustc_hir::HirId;
 use rustc_interface::interface;
 use rustc_resolve as resolve;
+use rustc_session::config::ErrorOutputType;
 use rustc_session::lint;
-
-use rustc_ast::ast::CRATE_NODE_ID;
-use rustc_attr as attr;
-use rustc_errors::emitter::{Emitter, EmitterWriter};
-use rustc_errors::json::JsonEmitter;
+use rustc_session::DiagnosticOutput;
+use rustc_session::{config, Session};
 use rustc_span::source_map;
 use rustc_span::symbol::sym;
 use rustc_span::DUMMY_SP;
@@ -34,8 +33,8 @@ use crate::html::render::RenderInfo;
 
 use crate::passes::{self, Condition::*, ConditionalPass};
 
-pub use rustc::session::config::{CodegenOptions, DebuggingOptions, Input, Options};
-pub use rustc::session::search_paths::SearchPath;
+pub use rustc_session::config::{CodegenOptions, DebuggingOptions, Input, Options};
+pub use rustc_session::search_paths::SearchPath;
 
 pub type ExternalPaths = FxHashMap<DefId, (Vec<String>, clean::TypeKind)>;
 
@@ -68,7 +67,7 @@ pub struct DocContext<'tcx> {
 }
 
 impl<'tcx> DocContext<'tcx> {
-    pub fn sess(&self) -> &session::Session {
+    pub fn sess(&self) -> &Session {
         &self.tcx.sess
     }
 
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 2e90d6082bac9..3c1f0509bba4d 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -49,8 +49,8 @@ use std::env;
 use std::panic;
 use std::process;
 
-use rustc::session::config::{make_crate_type_option, ErrorOutputType, RustcOptGroup};
-use rustc::session::{early_error, early_warn};
+use rustc_session::config::{make_crate_type_option, ErrorOutputType, RustcOptGroup};
+use rustc_session::{early_error, early_warn};
 
 #[macro_use]
 mod externalfiles;
diff --git a/src/librustdoc/passes/collect_intra_doc_links.rs b/src/librustdoc/passes/collect_intra_doc_links.rs
index 75355b84fee83..72106afbe0e75 100644
--- a/src/librustdoc/passes/collect_intra_doc_links.rs
+++ b/src/librustdoc/passes/collect_intra_doc_links.rs
@@ -1,4 +1,3 @@
-use rustc::lint;
 use rustc::ty;
 use rustc_ast::ast::{self, Ident};
 use rustc_errors::Applicability;
@@ -12,6 +11,7 @@ use rustc_hir::def::{
 };
 use rustc_hir::def_id::DefId;
 use rustc_resolve::ParentScope;
+use rustc_session::lint;
 use rustc_span::symbol::Symbol;
 use rustc_span::DUMMY_SP;
 
diff --git a/src/librustdoc/passes/mod.rs b/src/librustdoc/passes/mod.rs
index 71cff637c1272..38f371783e994 100644
--- a/src/librustdoc/passes/mod.rs
+++ b/src/librustdoc/passes/mod.rs
@@ -1,9 +1,9 @@
 //! Contains information about "passes", used to modify crate information during the documentation
 //! process.
 
-use rustc::lint;
 use rustc::middle::privacy::AccessLevels;
 use rustc_hir::def_id::{DefId, DefIdSet};
+use rustc_session::lint;
 use rustc_span::{InnerSpan, Span, DUMMY_SP};
 use std::mem;
 use std::ops::Range;
diff --git a/src/librustdoc/test.rs b/src/librustdoc/test.rs
index b1a60e2746fc1..c5aa4677d5659 100644
--- a/src/librustdoc/test.rs
+++ b/src/librustdoc/test.rs
@@ -1,5 +1,4 @@
 use rustc::hir::map::Map;
-use rustc::session::{self, config, DiagnosticOutput};
 use rustc::util::common::ErrorReported;
 use rustc_ast::ast;
 use rustc_ast::with_globals;
@@ -8,6 +7,7 @@ use rustc_feature::UnstableFeatures;
 use rustc_hir as hir;
 use rustc_hir::intravisit;
 use rustc_interface::interface;
+use rustc_session::{self, config, DiagnosticOutput, Session};
 use rustc_span::edition::Edition;
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::sym;
@@ -52,7 +52,7 @@ pub fn run(options: Options) -> i32 {
         cg: options.codegen_options.clone(),
         externs: options.externs.clone(),
         unstable_features: UnstableFeatures::from_environment(),
-        lint_cap: Some(::rustc::lint::Level::Allow),
+        lint_cap: Some(rustc_session::lint::Level::Allow),
         actually_rustdoc: true,
         debugging_opts: config::DebuggingOptions { ..config::basic_debugging_options() },
         edition: options.edition,
@@ -854,7 +854,7 @@ impl Tester for Collector {
 }
 
 struct HirCollector<'a, 'hir> {
-    sess: &'a session::Session,
+    sess: &'a Session,
     collector: &'a mut Collector,
     map: Map<'hir>,
     codes: ErrorCodes,
diff --git a/src/libstd/keyword_docs.rs b/src/libstd/keyword_docs.rs
index 2702de15b858a..314424631fcbf 100644
--- a/src/libstd/keyword_docs.rs
+++ b/src/libstd/keyword_docs.rs
@@ -234,12 +234,55 @@ mod crate_keyword {}
 
 #[doc(keyword = "else")]
 //
-/// What to do when an [`if`] condition does not hold.
+/// What expression to evaluate when an [`if`] condition evaluates to [`false`].
 ///
-/// The documentation for this keyword is [not yet complete]. Pull requests welcome!
+/// `else` expressions are optional. When no else expressions are supplied it is assumed to evaluate
+/// to the unit type `()`.
+///
+/// The type that the `else` blocks evaluate to must be compatible with the type that the `if` block
+/// evaluates to.
+///
+/// As can be seen below, `else` must be followed by either: `if`, `if let`, or a block `{}` and it
+/// will return the value of that expression.
 ///
+/// ```rust
+/// let result = if true == false {
+///     "oh no"
+/// } else if "something" == "other thing" {
+///     "oh dear"
+/// } else if let Some(200) = "blarg".parse::<i32>().ok() {
+///     "uh oh"
+/// } else {
+///     println!("Sneaky side effect.");
+///     "phew, nothing's broken"
+/// };
+/// ```
+///
+/// Here's another example but here we do not try and return an expression:
+///
+/// ```rust
+/// if true == false {
+///     println!("oh no");
+/// } else if "something" == "other thing" {
+///     println!("oh dear");
+/// } else if let Some(200) = "blarg".parse::<i32>().ok() {
+///     println!("uh oh");
+/// } else {
+///     println!("phew, nothing's broken");
+/// }
+/// ```
+///
+/// The above is _still_ an expression but it will always evaluate to `()`.
+///
+/// There is possibly no limit to the number of `else` blocks that could follow an `if` expression
+/// however if you have several then a [`match`] expression might be preferable.
+///
+/// Read more about control flow in the [Rust Book].
+///
+/// [Rust Book]: ../book/ch03-05-control-flow.html#handling-multiple-conditions-with-else-if
+/// [`match`]: keyword.match.html
+/// [`false`]: keyword.false.html
 /// [`if`]: keyword.if.html
-/// [not yet complete]: https://github.com/rust-lang/rust/issues/34601
 mod else_keyword {}
 
 #[doc(keyword = "enum")]
@@ -637,10 +680,18 @@ mod impl_keyword {}
 //
 /// Iterate over a series of values with [`for`].
 ///
-/// The documentation for this keyword is [not yet complete]. Pull requests welcome!
+/// The expression immediately following `in` must implement the [`Iterator`] trait.
 ///
+/// ## Literal Examples:
+///
+///    * `for _ **in** 1..3 {}` - Iterate over an exclusive range up to but excluding 3.
+///    * `for _ **in** 1..=3 {}` - Iterate over an inclusive range up to and includeing 3.
+///
+/// (Read more about [range patterns])
+///
+/// [`Iterator`]: ../book/ch13-04-performance.html
+/// [`range patterns`]: ../reference/patterns.html?highlight=range#range-patterns
 /// [`for`]: keyword.for.html
-/// [not yet complete]: https://github.com/rust-lang/rust/issues/34601
 mod in_keyword {}
 
 #[doc(keyword = "let")]
diff --git a/src/test/incremental/hashes/closure_expressions.rs b/src/test/incremental/hashes/closure_expressions.rs
index 3d9db340f6375..8edece2c8d361 100644
--- a/src/test/incremental/hashes/closure_expressions.rs
+++ b/src/test/incremental/hashes/closure_expressions.rs
@@ -84,8 +84,8 @@ pub fn add_type_ascription_to_parameter() {
 }
 
 #[cfg(not(cfail1))]
-#[rustc_clean(cfg="cfail2", except="hir_owner_items, mir_built, typeck_tables_of")]
-#[rustc_clean(cfg="cfail3")]
+#[rustc_clean(cfg = "cfail2", except = "hir_owner_items, typeck_tables_of")]
+#[rustc_clean(cfg = "cfail3")]
 pub fn add_type_ascription_to_parameter() {
     let closure = |x: u32| x + 1u32;
     let _: u32 = closure(1);
diff --git a/src/test/incremental/hashes/inherent_impls.rs b/src/test/incremental/hashes/inherent_impls.rs
index c0b80a92df6ee..139c265164bc5 100644
--- a/src/test/incremental/hashes/inherent_impls.rs
+++ b/src/test/incremental/hashes/inherent_impls.rs
@@ -360,7 +360,7 @@ impl Foo {
 impl Foo {
     #[rustc_clean(
         cfg="cfail2",
-        except="hir_owner,hir_owner_items,generics_of,predicates_of,type_of,typeck_tables_of"
+        except="hir_owner,hir_owner_items,generics_of,predicates_of,type_of"
     )]
     #[rustc_clean(cfg="cfail3")]
     pub fn add_lifetime_bound_to_lifetime_param_of_method<'a, 'b: 'a>(&self) { }
diff --git a/src/test/incremental/hashes/unary_and_binary_exprs.rs b/src/test/incremental/hashes/unary_and_binary_exprs.rs
index 9b63003482fe5..89aa0b1a58baa 100644
--- a/src/test/incremental/hashes/unary_and_binary_exprs.rs
+++ b/src/test/incremental/hashes/unary_and_binary_exprs.rs
@@ -81,7 +81,7 @@ pub fn var_deref(x: &i32, y: &i32) -> i32 {
 }
 
 #[cfg(not(cfail1))]
-#[rustc_clean(except="hir_owner_items,optimized_mir,mir_built,typeck_tables_of", cfg="cfail2")]
+#[rustc_clean(except="hir_owner_items,optimized_mir,mir_built", cfg="cfail2")]
 #[rustc_clean(cfg="cfail3")]
 pub fn var_deref(x: &i32, y: &i32) -> i32 {
     *y
diff --git a/src/test/mir-opt/const-promotion-extern-static.rs b/src/test/mir-opt/const-promotion-extern-static.rs
index 0d4a6d1bafdd2..c858a4c5ee7c6 100644
--- a/src/test/mir-opt/const-promotion-extern-static.rs
+++ b/src/test/mir-opt/const-promotion-extern-static.rs
@@ -4,9 +4,9 @@ extern "C" {
 
 static Y: i32 = 42;
 
-static mut BAR: *const &'static i32 = [&Y].as_ptr();
+static mut BAR: *const &i32 = [&Y].as_ptr();
 
-static mut FOO: *const &'static i32 = [unsafe { &X }].as_ptr();
+static mut FOO: *const &i32 = [unsafe { &X }].as_ptr();
 
 fn main() {}
 
@@ -18,8 +18,8 @@ fn main() {}
 //     _4 = &(*_5);
 //     _3 = [move _4];
 //     _2 = &_3;
-//     _1 = move _2 as &[&'static i32] (Pointer(Unsize));
-//     _0 = const core::slice::<impl [&'static i32]>::as_ptr(move _1) -> [return: bb2, unwind: bb1];
+//     _1 = move _2 as &[&i32] (Pointer(Unsize));
+//     _0 = const core::slice::<impl [&i32]>::as_ptr(move _1) -> [return: bb2, unwind: bb1];
 // }
 // ...
 // bb2: {
@@ -35,8 +35,8 @@ fn main() {}
 //     _4 = &(*_5);
 //     _3 = [move _4];
 //     _2 = &_3;
-//     _1 = move _2 as &[&'static i32] (Pointer(Unsize));
-//     _0 = const core::slice::<impl [&'static i32]>::as_ptr(move _1) -> [return: bb2, unwind: bb1];
+//     _1 = move _2 as &[&i32] (Pointer(Unsize));
+//     _0 = const core::slice::<impl [&i32]>::as_ptr(move _1) -> [return: bb2, unwind: bb1];
 // }
 // ...
 // bb2: {
@@ -50,8 +50,8 @@ fn main() {}
 // ...
 //     _6 = const BAR::promoted[0];
 //     _2 = &(*_6);
-//     _1 = move _2 as &[&'static i32] (Pointer(Unsize));
-//     _0 = const core::slice::<impl [&'static i32]>::as_ptr(move _1) -> [return: bb2, unwind: bb1];
+//     _1 = move _2 as &[&i32] (Pointer(Unsize));
+//     _0 = const core::slice::<impl [&i32]>::as_ptr(move _1) -> [return: bb2, unwind: bb1];
 // }
 // ...
 // bb2: {
@@ -63,8 +63,8 @@ fn main() {}
 // ...
 //     _6 = const FOO::promoted[0];
 //     _2 = &(*_6);
-//     _1 = move _2 as &[&'static i32] (Pointer(Unsize));
-//     _0 = const core::slice::<impl [&'static i32]>::as_ptr(move _1) -> [return: bb2, unwind: bb1];
+//     _1 = move _2 as &[&i32] (Pointer(Unsize));
+//     _0 = const core::slice::<impl [&i32]>::as_ptr(move _1) -> [return: bb2, unwind: bb1];
 // }
 // ...
 // bb2: {
diff --git a/src/test/mir-opt/generator-tiny.rs b/src/test/mir-opt/generator-tiny.rs
new file mode 100644
index 0000000000000..09e943bd962e6
--- /dev/null
+++ b/src/test/mir-opt/generator-tiny.rs
@@ -0,0 +1,34 @@
+//! Tests that generators that cannot return or unwind don't have unnecessary
+//! panic branches.
+
+// compile-flags: -Zno-landing-pads
+
+#![feature(generators, generator_trait)]
+
+struct HasDrop;
+
+impl Drop for HasDrop {
+    fn drop(&mut self) {}
+}
+
+fn callee() {}
+
+fn main() {
+    let _gen = |_x: u8| {
+        let _d = HasDrop;
+        loop {
+            yield;
+            callee();
+        }
+    };
+}
+
+// END RUST SOURCE
+
+// START rustc.main-{{closure}}.generator_resume.0.mir
+// bb0: {
+//     ...
+//     switchInt(move _11) -> [0u32: bb1, 3u32: bb5, otherwise: bb6];
+// }
+// ...
+// END rustc.main-{{closure}}.generator_resume.0.mir
diff --git a/src/test/mir-opt/no-drop-for-inactive-variant.rs b/src/test/mir-opt/no-drop-for-inactive-variant.rs
index f906761684526..74a606af28fc1 100644
--- a/src/test/mir-opt/no-drop-for-inactive-variant.rs
+++ b/src/test/mir-opt/no-drop-for-inactive-variant.rs
@@ -27,7 +27,7 @@ fn main() {
 //     }
 //     bb2: {
 //         ...
-//         const std::rt::begin_panic::<&'static str>(const "explicit panic") -> bb5;
+//         const std::rt::begin_panic::<&str>(const "explicit panic") -> bb5;
 //     }
 //     bb3: {
 //         unreachable;
diff --git a/src/test/mir-opt/remove_fake_borrows.rs b/src/test/mir-opt/remove_fake_borrows.rs
index 294fe247c38be..ea106eaf59529 100644
--- a/src/test/mir-opt/remove_fake_borrows.rs
+++ b/src/test/mir-opt/remove_fake_borrows.rs
@@ -26,16 +26,16 @@ fn main() {
 //     goto -> bb7;
 // }
 // bb2: {
-//     switchInt((*(*((_1 as Some).0: &'<empty> &'<empty> i32)))) -> [0i32: bb3, otherwise: bb1];
+//     switchInt((*(*((_1 as Some).0: &&i32)))) -> [0i32: bb3, otherwise: bb1];
 // }
 // bb3: {
 //     goto -> bb4;
 // }
 // bb4: {
 //     _4 = &shallow _1;
-//     _5 = &shallow ((_1 as Some).0: &'<empty> &'<empty> i32);
-//     _6 = &shallow (*((_1 as Some).0: &'<empty> &'<empty> i32));
-//     _7 = &shallow (*(*((_1 as Some).0: &'<empty> &'<empty> i32)));
+//     _5 = &shallow ((_1 as Some).0: &&i32);
+//     _6 = &shallow (*((_1 as Some).0: &&i32));
+//     _7 = &shallow (*(*((_1 as Some).0: &&i32)));
 //     StorageLive(_8);
 //     _8 = _2;
 //     switchInt(move _8) -> [false: bb6, otherwise: bb5];
@@ -72,7 +72,7 @@ fn main() {
 //     goto -> bb7;
 // }
 // bb2: {
-//     switchInt((*(*((_1 as Some).0: &'<empty> &'<empty> i32)))) -> [0i32: bb3, otherwise: bb1];
+//     switchInt((*(*((_1 as Some).0: &&i32)))) -> [0i32: bb3, otherwise: bb1];
 // }
 // bb3: {
 //     goto -> bb4;
diff --git a/src/test/mir-opt/storage_live_dead_in_statics.rs b/src/test/mir-opt/storage_live_dead_in_statics.rs
index 5dc15286bab50..1c98766b9685c 100644
--- a/src/test/mir-opt/storage_live_dead_in_statics.rs
+++ b/src/test/mir-opt/storage_live_dead_in_statics.rs
@@ -35,12 +35,12 @@ fn main() {
 
 // END RUST SOURCE
 // START rustc.XXX.mir_map.0.mir
-//    let mut _0: &'static Foo;
-//    let _1: &'static Foo;
+//    let mut _0: &Foo;
+//    let _1: &Foo;
 //    let _2: Foo;
-//    let mut _3: &'static [(u32, u32)];
-//    let mut _4: &'static [(u32, u32); 42];
-//    let _5: &'static [(u32, u32); 42];
+//    let mut _3: &[(u32, u32)];
+//    let mut _4: &[(u32, u32); 42];
+//    let _5: &[(u32, u32); 42];
 //    let _6: [(u32, u32); 42];
 //    let mut _7: (u32, u32);
 //    let mut _8: (u32, u32);
@@ -178,7 +178,7 @@ fn main() {
 //        _6 = [move _7, move _8, move _9, move _10, move _11, move _12, move _13, move _14, move _15, move _16, move _17, move _18, move _19, move _20, move _21, move _22, move _23, move _24, move _25, move _26, move _27, move _28, move _29, move _30, move _31, move _32, move _33, move _34, move _35, move _36, move _37, move _38, move _39, move _40, move _41, move _42, move _43, move _44, move _45, move _46, move _47, move _48];
 //        _5 = &_6;
 //        _4 = &(*_5);
-//        _3 = move _4 as &'static [(u32, u32)] (Pointer(Unsize));
+//        _3 = move _4 as &[(u32, u32)] (Pointer(Unsize));
 //        _2 = Foo { tup: const "hi", data: move _3 };
 //        _1 = &_2;
 //        _0 = &(*_1);
diff --git a/src/test/pretty/issue-4264.pp b/src/test/pretty/issue-4264.pp
index 8aa4cdeb5394e..ee7586bae820a 100644
--- a/src/test/pretty/issue-4264.pp
+++ b/src/test/pretty/issue-4264.pp
@@ -34,29 +34,29 @@
                            ((::alloc::fmt::format as
                                 for<'r> fn(std::fmt::Arguments<'r>) -> std::string::String {std::fmt::format})(((::core::fmt::Arguments::new_v1
                                                                                                                     as
-                                                                                                                    fn(&[&str], &[std::fmt::ArgumentV1<'_>]) -> std::fmt::Arguments<'_> {std::fmt::Arguments::<'_>::new_v1})((&([("test"
-                                                                                                                                                                                                                                     as
-                                                                                                                                                                                                                                     &'static str)]
-                                                                                                                                                                                                                                   as
-                                                                                                                                                                                                                                   [&str; 1])
-                                                                                                                                                                                                                                 as
-                                                                                                                                                                                                                                 &[&str; 1]),
-                                                                                                                                                                                                                             (&(match (()
-                                                                                                                                                                                                                                          as
-                                                                                                                                                                                                                                          ())
-                                                                                                                                                                                                                                    {
-                                                                                                                                                                                                                                    ()
-                                                                                                                                                                                                                                    =>
-                                                                                                                                                                                                                                    ([]
-                                                                                                                                                                                                                                        as
-                                                                                                                                                                                                                                        [std::fmt::ArgumentV1<'_>; 0]),
-                                                                                                                                                                                                                                }
-                                                                                                                                                                                                                                   as
-                                                                                                                                                                                                                                   [std::fmt::ArgumentV1<'_>; 0])
-                                                                                                                                                                                                                                 as
-                                                                                                                                                                                                                                 &[std::fmt::ArgumentV1<'_>; 0]))
+                                                                                                                    fn(&[&str], &[std::fmt::ArgumentV1]) -> std::fmt::Arguments {std::fmt::Arguments::new_v1})((&([("test"
+                                                                                                                                                                                                                       as
+                                                                                                                                                                                                                       &str)]
+                                                                                                                                                                                                                     as
+                                                                                                                                                                                                                     [&str; 1])
+                                                                                                                                                                                                                   as
+                                                                                                                                                                                                                   &[&str; 1]),
+                                                                                                                                                                                                               (&(match (()
+                                                                                                                                                                                                                            as
+                                                                                                                                                                                                                            ())
+                                                                                                                                                                                                                      {
+                                                                                                                                                                                                                      ()
+                                                                                                                                                                                                                      =>
+                                                                                                                                                                                                                      ([]
+                                                                                                                                                                                                                          as
+                                                                                                                                                                                                                          [std::fmt::ArgumentV1; 0]),
+                                                                                                                                                                                                                  }
+                                                                                                                                                                                                                     as
+                                                                                                                                                                                                                     [std::fmt::ArgumentV1; 0])
+                                                                                                                                                                                                                   as
+                                                                                                                                                                                                                   &[std::fmt::ArgumentV1; 0]))
                                                                                                                    as
-                                                                                                                   std::fmt::Arguments<'_>))
+                                                                                                                   std::fmt::Arguments))
                                as std::string::String);
                        (res as std::string::String)
                    } as std::string::String);
diff --git a/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs b/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs
index 07ef2424cc880..d975af52f5bb8 100644
--- a/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs
+++ b/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs
@@ -7,14 +7,12 @@ extern crate rustc_data_structures;
 extern crate rustc_hir;
 extern crate rustc_target;
 extern crate rustc_driver;
+extern crate rustc_session;
 extern crate rustc_span;
 
 use std::any::Any;
 use std::sync::Arc;
 use std::path::Path;
-use rustc_span::symbol::Symbol;
-use rustc::session::Session;
-use rustc::session::config::OutputFilenames;
 use rustc::ty::TyCtxt;
 use rustc::ty::query::Providers;
 use rustc::middle::cstore::{EncodedMetadata, MetadataLoader, MetadataLoaderDyn};
@@ -23,6 +21,9 @@ use rustc::util::common::ErrorReported;
 use rustc_codegen_utils::codegen_backend::CodegenBackend;
 use rustc_data_structures::sync::MetadataRef;
 use rustc_data_structures::owning_ref::OwningRef;
+use rustc_session::Session;
+use rustc_session::config::OutputFilenames;
+use rustc_span::symbol::Symbol;
 use rustc_target::spec::Target;
 
 pub struct NoLlvmMetadataLoader;
@@ -89,7 +90,7 @@ impl CodegenBackend for TheBackend {
         outputs: &OutputFilenames,
     ) -> Result<(), ErrorReported> {
         use std::io::Write;
-        use rustc::session::config::CrateType;
+        use rustc_session::config::CrateType;
         use rustc_codegen_utils::link::out_filename;
         let crate_name = codegen_results.downcast::<Symbol>()
             .expect("in link: codegen_results is not a Symbol");
diff --git a/src/test/run-make-fulldeps/issue-19371/foo.rs b/src/test/run-make-fulldeps/issue-19371/foo.rs
index 12da64fc88f18..af84faa7511c6 100644
--- a/src/test/run-make-fulldeps/issue-19371/foo.rs
+++ b/src/test/run-make-fulldeps/issue-19371/foo.rs
@@ -1,13 +1,12 @@
 #![feature(rustc_private)]
 
-extern crate rustc;
 extern crate rustc_interface;
 extern crate rustc_driver;
+extern crate rustc_session;
 extern crate rustc_span;
 
-use rustc::session::DiagnosticOutput;
-use rustc::session::config::{Input, Options,
-                             OutputType, OutputTypes};
+use rustc_session::DiagnosticOutput;
+use rustc_session::config::{Input, Options, OutputType, OutputTypes};
 use rustc_interface::interface;
 use rustc_span::source_map::FileName;
 
diff --git a/src/test/ui/consts/const-eval/const-pointer-values-in-various-types.stderr b/src/test/ui/consts/const-eval/const-pointer-values-in-various-types.stderr
index e0df787f80a44..305f259eac22d 100644
--- a/src/test/ui/consts/const-eval/const-pointer-values-in-various-types.stderr
+++ b/src/test/ui/consts/const-eval/const-pointer-values-in-various-types.stderr
@@ -12,7 +12,7 @@ error: any use of this value will cause an error
 LL |     const I32_REF_U8_UNION: u8 = unsafe { Nonsense { int_32_ref: &3 }.uint_8 };
    |     --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                           |
-   |                                           a raw memory access tried to access part of a pointer value as raw bytes
+   |                                           unable to turn pointer into raw bytes
    |
    = note: `#[deny(const_err)]` on by default
 
@@ -22,7 +22,7 @@ error: any use of this value will cause an error
 LL |     const I32_REF_U16_UNION: u16 = unsafe { Nonsense { int_32_ref: &3 }.uint_16 };
    |     ----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                             |
-   |                                             a raw memory access tried to access part of a pointer value as raw bytes
+   |                                             unable to turn pointer into raw bytes
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:34:45
@@ -30,7 +30,7 @@ error: any use of this value will cause an error
 LL |     const I32_REF_U32_UNION: u32 = unsafe { Nonsense { int_32_ref: &3 }.uint_32 };
    |     ----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                             |
-   |                                             a raw memory access tried to access part of a pointer value as raw bytes
+   |                                             unable to turn pointer into raw bytes
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/const-pointer-values-in-various-types.rs:37:5
@@ -54,7 +54,7 @@ error: any use of this value will cause an error
 LL |     const I32_REF_I8_UNION: i8 = unsafe { Nonsense { int_32_ref: &3 }.int_8 };
    |     --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                           |
-   |                                           a raw memory access tried to access part of a pointer value as raw bytes
+   |                                           unable to turn pointer into raw bytes
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:46:45
@@ -62,7 +62,7 @@ error: any use of this value will cause an error
 LL |     const I32_REF_I16_UNION: i16 = unsafe { Nonsense { int_32_ref: &3 }.int_16 };
    |     ----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                             |
-   |                                             a raw memory access tried to access part of a pointer value as raw bytes
+   |                                             unable to turn pointer into raw bytes
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:49:45
@@ -70,7 +70,7 @@ error: any use of this value will cause an error
 LL |     const I32_REF_I32_UNION: i32 = unsafe { Nonsense { int_32_ref: &3 }.int_32 };
    |     ----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                             |
-   |                                             a raw memory access tried to access part of a pointer value as raw bytes
+   |                                             unable to turn pointer into raw bytes
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/const-pointer-values-in-various-types.rs:52:5
@@ -94,7 +94,7 @@ error: any use of this value will cause an error
 LL |     const I32_REF_F32_UNION: f32 = unsafe { Nonsense { int_32_ref: &3 }.float_32 };
    |     ----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                             |
-   |                                             a raw memory access tried to access part of a pointer value as raw bytes
+   |                                             unable to turn pointer into raw bytes
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/const-pointer-values-in-various-types.rs:61:5
@@ -110,7 +110,7 @@ error: any use of this value will cause an error
 LL |     const I32_REF_BOOL_UNION: bool = unsafe { Nonsense { int_32_ref: &3 }.truthy_falsey };
    |     ------------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                               |
-   |                                               a raw memory access tried to access part of a pointer value as raw bytes
+   |                                               unable to turn pointer into raw bytes
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:67:47
@@ -118,7 +118,7 @@ error: any use of this value will cause an error
 LL |     const I32_REF_CHAR_UNION: char = unsafe { Nonsense { int_32_ref: &3 }.character };
    |     ------------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                               |
-   |                                               a raw memory access tried to access part of a pointer value as raw bytes
+   |                                               unable to turn pointer into raw bytes
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:70:39
@@ -126,7 +126,7 @@ error: any use of this value will cause an error
 LL |     const STR_U8_UNION: u8 = unsafe { Nonsense { stringy: "3" }.uint_8 };
    |     ----------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                       |
-   |                                       a raw memory access tried to access part of a pointer value as raw bytes
+   |                                       unable to turn pointer into raw bytes
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:73:41
@@ -134,7 +134,7 @@ error: any use of this value will cause an error
 LL |     const STR_U16_UNION: u16 = unsafe { Nonsense { stringy: "3" }.uint_16 };
    |     ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                         |
-   |                                         a raw memory access tried to access part of a pointer value as raw bytes
+   |                                         unable to turn pointer into raw bytes
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:76:41
@@ -142,7 +142,7 @@ error: any use of this value will cause an error
 LL |     const STR_U32_UNION: u32 = unsafe { Nonsense { stringy: "3" }.uint_32 };
    |     ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                         |
-   |                                         a raw memory access tried to access part of a pointer value as raw bytes
+   |                                         unable to turn pointer into raw bytes
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/const-pointer-values-in-various-types.rs:79:5
@@ -158,7 +158,7 @@ error: any use of this value will cause an error
 LL |     const STR_U128_UNION: u128 = unsafe { Nonsense { stringy: "3" }.uint_128 };
    |     --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                           |
-   |                                           a raw memory access tried to access part of a pointer value as raw bytes
+   |                                           unable to turn pointer into raw bytes
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:85:39
@@ -166,7 +166,7 @@ error: any use of this value will cause an error
 LL |     const STR_I8_UNION: i8 = unsafe { Nonsense { stringy: "3" }.int_8 };
    |     ----------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                       |
-   |                                       a raw memory access tried to access part of a pointer value as raw bytes
+   |                                       unable to turn pointer into raw bytes
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:88:41
@@ -174,7 +174,7 @@ error: any use of this value will cause an error
 LL |     const STR_I16_UNION: i16 = unsafe { Nonsense { stringy: "3" }.int_16 };
    |     ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                         |
-   |                                         a raw memory access tried to access part of a pointer value as raw bytes
+   |                                         unable to turn pointer into raw bytes
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:91:41
@@ -182,7 +182,7 @@ error: any use of this value will cause an error
 LL |     const STR_I32_UNION: i32 = unsafe { Nonsense { stringy: "3" }.int_32 };
    |     ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                         |
-   |                                         a raw memory access tried to access part of a pointer value as raw bytes
+   |                                         unable to turn pointer into raw bytes
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/const-pointer-values-in-various-types.rs:94:5
@@ -198,7 +198,7 @@ error: any use of this value will cause an error
 LL |     const STR_I128_UNION: i128 = unsafe { Nonsense { stringy: "3" }.int_128 };
    |     --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                           |
-   |                                           a raw memory access tried to access part of a pointer value as raw bytes
+   |                                           unable to turn pointer into raw bytes
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:100:41
@@ -206,7 +206,7 @@ error: any use of this value will cause an error
 LL |     const STR_F32_UNION: f32 = unsafe { Nonsense { stringy: "3" }.float_32 };
    |     ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                         |
-   |                                         a raw memory access tried to access part of a pointer value as raw bytes
+   |                                         unable to turn pointer into raw bytes
 
 error[E0080]: it is undefined behavior to use this value
   --> $DIR/const-pointer-values-in-various-types.rs:103:5
@@ -222,7 +222,7 @@ error: any use of this value will cause an error
 LL |     const STR_BOOL_UNION: bool = unsafe { Nonsense { stringy: "3" }.truthy_falsey };
    |     --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                           |
-   |                                           a raw memory access tried to access part of a pointer value as raw bytes
+   |                                           unable to turn pointer into raw bytes
 
 error: any use of this value will cause an error
   --> $DIR/const-pointer-values-in-various-types.rs:109:43
@@ -230,7 +230,7 @@ error: any use of this value will cause an error
 LL |     const STR_CHAR_UNION: char = unsafe { Nonsense { stringy: "3" }.character };
    |     --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                           |
-   |                                           a raw memory access tried to access part of a pointer value as raw bytes
+   |                                           unable to turn pointer into raw bytes
 
 error: aborting due to 29 previous errors
 
diff --git a/src/test/ui/consts/const-eval/const_raw_ptr_ops.stderr b/src/test/ui/consts/const-eval/const_raw_ptr_ops.stderr
index 2cba833a74896..cc40728e6b574 100644
--- a/src/test/ui/consts/const-eval/const_raw_ptr_ops.stderr
+++ b/src/test/ui/consts/const-eval/const_raw_ptr_ops.stderr
@@ -30,7 +30,7 @@ error: any use of this value will cause an error
 LL | const Z2: i32 = unsafe { *(42 as *const i32) };
    | -------------------------^^^^^^^^^^^^^^^^^^^---
    |                          |
-   |                          a memory access tried to interpret some bytes as a pointer
+   |                          unable to turn bytes into a pointer
 
 error: any use of this value will cause an error
   --> $DIR/const_raw_ptr_ops.rs:17:26
@@ -38,7 +38,7 @@ error: any use of this value will cause an error
 LL | const Z3: i32 = unsafe { *(44 as *const i32) };
    | -------------------------^^^^^^^^^^^^^^^^^^^---
    |                          |
-   |                          a memory access tried to interpret some bytes as a pointer
+   |                          unable to turn bytes into a pointer
 
 error: aborting due to 5 previous errors
 
diff --git a/src/test/ui/consts/const-eval/issue-49296.stderr b/src/test/ui/consts/const-eval/issue-49296.stderr
index 48809e0ae649c..798f130a4baf6 100644
--- a/src/test/ui/consts/const-eval/issue-49296.stderr
+++ b/src/test/ui/consts/const-eval/issue-49296.stderr
@@ -4,7 +4,7 @@ error: any use of this value will cause an error
 LL | const X: u64 = *wat(42);
    | ---------------^^^^^^^^-
    |                |
-   |                dangling pointer was dereferenced
+   |                pointer to alloc2 was dereferenced after this allocation got freed
    |
    = note: `#[deny(const_err)]` on by default
 
diff --git a/src/test/ui/consts/const-eval/ub-nonnull.stderr b/src/test/ui/consts/const-eval/ub-nonnull.stderr
index edfc7ac837fc7..adad1b4f7fafe 100644
--- a/src/test/ui/consts/const-eval/ub-nonnull.stderr
+++ b/src/test/ui/consts/const-eval/ub-nonnull.stderr
@@ -13,7 +13,7 @@ LL | / const OUT_OF_BOUNDS_PTR: NonNull<u8> = { unsafe {
 LL | |     let ptr: &[u8; 256] = mem::transmute(&0u8); // &0 gets promoted so it does not dangle
 LL | |     // Use address-of-element for pointer arithmetic. This could wrap around to NULL!
 LL | |     let out_of_bounds_ptr = &ptr[255];
-   | |                             ^^^^^^^^^ Memory access failed: pointer must be in-bounds at offset 256, but is outside bounds of allocation 8 which has size 1
+   | |                             ^^^^^^^^^ Memory access failed: pointer must be in-bounds at offset 256, but is outside bounds of alloc8 which has size 1
 LL | |     mem::transmute(out_of_bounds_ptr)
 LL | | } };
    | |____-
diff --git a/src/test/ui/consts/const-eval/ub-wide-ptr.rs b/src/test/ui/consts/const-eval/ub-wide-ptr.rs
index 2d48309b72722..0200bfe9f08f8 100644
--- a/src/test/ui/consts/const-eval/ub-wide-ptr.rs
+++ b/src/test/ui/consts/const-eval/ub-wide-ptr.rs
@@ -6,7 +6,7 @@
 use std::mem;
 
 // normalize-stderr-test "offset \d+" -> "offset N"
-// normalize-stderr-test "allocation \d+" -> "allocation N"
+// normalize-stderr-test "alloc\d+" -> "allocN"
 // normalize-stderr-test "size \d+" -> "size N"
 
 #[repr(C)]
diff --git a/src/test/ui/consts/const-eval/ub-wide-ptr.stderr b/src/test/ui/consts/const-eval/ub-wide-ptr.stderr
index a562c64b124f9..80e60dbb58a5d 100644
--- a/src/test/ui/consts/const-eval/ub-wide-ptr.stderr
+++ b/src/test/ui/consts/const-eval/ub-wide-ptr.stderr
@@ -2,7 +2,7 @@ error[E0080]: it is undefined behavior to use this value
   --> $DIR/ub-wide-ptr.rs:32:1
    |
 LL | const STR_TOO_LONG: &str = unsafe { mem::transmute((&42u8, 999usize)) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a dangling reference (not entirely in bounds)
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a dangling reference (going beyond the bounds of its allocation)
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
 
@@ -70,7 +70,7 @@ error[E0080]: it is undefined behavior to use this value
   --> $DIR/ub-wide-ptr.rs:62:1
    |
 LL | const SLICE_TOO_LONG: &[u8] = unsafe { mem::transmute((&42u8, 999usize)) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a dangling reference (not entirely in bounds)
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a dangling reference (going beyond the bounds of its allocation)
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
 
@@ -86,7 +86,7 @@ error[E0080]: it is undefined behavior to use this value
   --> $DIR/ub-wide-ptr.rs:68:1
    |
 LL | const SLICE_TOO_LONG_BOX: Box<[u8]> = unsafe { mem::transmute((&42u8, 999usize)) };
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a dangling box (not entirely in bounds)
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered a dangling box (going beyond the bounds of its allocation)
    |
    = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
 
@@ -192,7 +192,7 @@ error[E0080]: could not evaluate static initializer
   --> $DIR/ub-wide-ptr.rs:125:5
    |
 LL |     mem::transmute::<_, &dyn Trait>((&92u8, &3u64))
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Memory access failed: pointer must be in-bounds at offset N, but is outside bounds of allocation N which has size N
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Memory access failed: pointer must be in-bounds at offset N, but is outside bounds of allocN which has size N
 
 error: aborting due to 24 previous errors
 
diff --git a/src/test/ui/consts/const-int-unchecked.stderr b/src/test/ui/consts/const-int-unchecked.stderr
index bf31e0b0732d8..cf70454b6bf9e 100644
--- a/src/test/ui/consts/const-int-unchecked.stderr
+++ b/src/test/ui/consts/const-int-unchecked.stderr
@@ -4,7 +4,7 @@ error: any use of this value will cause an error
 LL | const SHL_U8: u8 = unsafe { intrinsics::unchecked_shl(5_u8, 8) };
    | ----------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                             |
-   |                             Overflowing shift by 8 in `unchecked_shl`
+   |                             overflowing shift by 8 in `unchecked_shl`
    |
    = note: `#[deny(const_err)]` on by default
 
@@ -14,7 +14,7 @@ error: any use of this value will cause an error
 LL | const SHL_U16: u16 = unsafe { intrinsics::unchecked_shl(5_u16, 16) };
    | ------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                               |
-   |                               Overflowing shift by 16 in `unchecked_shl`
+   |                               overflowing shift by 16 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:19:31
@@ -22,7 +22,7 @@ error: any use of this value will cause an error
 LL | const SHL_U32: u32 = unsafe { intrinsics::unchecked_shl(5_u32, 32) };
    | ------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                               |
-   |                               Overflowing shift by 32 in `unchecked_shl`
+   |                               overflowing shift by 32 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:21:31
@@ -30,7 +30,7 @@ error: any use of this value will cause an error
 LL | const SHL_U64: u64 = unsafe { intrinsics::unchecked_shl(5_u64, 64) };
    | ------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                               |
-   |                               Overflowing shift by 64 in `unchecked_shl`
+   |                               overflowing shift by 64 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:23:33
@@ -38,7 +38,7 @@ error: any use of this value will cause an error
 LL | const SHL_U128: u128 = unsafe { intrinsics::unchecked_shl(5_u128, 128) };
    | --------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                 |
-   |                                 Overflowing shift by 128 in `unchecked_shl`
+   |                                 overflowing shift by 128 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:28:29
@@ -46,7 +46,7 @@ error: any use of this value will cause an error
 LL | const SHL_I8: i8 = unsafe { intrinsics::unchecked_shl(5_i8, 8) };
    | ----------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                             |
-   |                             Overflowing shift by 8 in `unchecked_shl`
+   |                             overflowing shift by 8 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:30:31
@@ -54,7 +54,7 @@ error: any use of this value will cause an error
 LL | const SHL_I16: i16 = unsafe { intrinsics::unchecked_shl(5_16, 16) };
    | ------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                               |
-   |                               Overflowing shift by 16 in `unchecked_shl`
+   |                               overflowing shift by 16 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:32:31
@@ -62,7 +62,7 @@ error: any use of this value will cause an error
 LL | const SHL_I32: i32 = unsafe { intrinsics::unchecked_shl(5_i32, 32) };
    | ------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                               |
-   |                               Overflowing shift by 32 in `unchecked_shl`
+   |                               overflowing shift by 32 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:34:31
@@ -70,7 +70,7 @@ error: any use of this value will cause an error
 LL | const SHL_I64: i64 = unsafe { intrinsics::unchecked_shl(5_i64, 64) };
    | ------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                               |
-   |                               Overflowing shift by 64 in `unchecked_shl`
+   |                               overflowing shift by 64 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:36:33
@@ -78,7 +78,7 @@ error: any use of this value will cause an error
 LL | const SHL_I128: i128 = unsafe { intrinsics::unchecked_shl(5_i128, 128) };
    | --------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                 |
-   |                                 Overflowing shift by 128 in `unchecked_shl`
+   |                                 overflowing shift by 128 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:41:33
@@ -86,7 +86,7 @@ error: any use of this value will cause an error
 LL | const SHL_I8_NEG: i8 = unsafe { intrinsics::unchecked_shl(5_i8, -1) };
    | --------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                 |
-   |                                 Overflowing shift by 255 in `unchecked_shl`
+   |                                 overflowing shift by 255 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:43:35
@@ -94,7 +94,7 @@ error: any use of this value will cause an error
 LL | const SHL_I16_NEG: i16 = unsafe { intrinsics::unchecked_shl(5_16, -1) };
    | ----------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                   |
-   |                                   Overflowing shift by 65535 in `unchecked_shl`
+   |                                   overflowing shift by 65535 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:45:35
@@ -102,7 +102,7 @@ error: any use of this value will cause an error
 LL | const SHL_I32_NEG: i32 = unsafe { intrinsics::unchecked_shl(5_i32, -1) };
    | ----------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                   |
-   |                                   Overflowing shift by 4294967295 in `unchecked_shl`
+   |                                   overflowing shift by 4294967295 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:47:35
@@ -110,7 +110,7 @@ error: any use of this value will cause an error
 LL | const SHL_I64_NEG: i64 = unsafe { intrinsics::unchecked_shl(5_i64, -1) };
    | ----------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                   |
-   |                                   Overflowing shift by 18446744073709551615 in `unchecked_shl`
+   |                                   overflowing shift by 18446744073709551615 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:49:37
@@ -118,7 +118,7 @@ error: any use of this value will cause an error
 LL | const SHL_I128_NEG: i128 = unsafe { intrinsics::unchecked_shl(5_i128, -1) };
    | ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                     |
-   |                                     Overflowing shift by 340282366920938463463374607431768211455 in `unchecked_shl`
+   |                                     overflowing shift by 340282366920938463463374607431768211455 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:55:40
@@ -126,7 +126,7 @@ error: any use of this value will cause an error
 LL | const SHL_I8_NEG_RANDOM: i8 = unsafe { intrinsics::unchecked_shl(5_i8, -6) };
    | ---------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                        |
-   |                                        Overflowing shift by 250 in `unchecked_shl`
+   |                                        overflowing shift by 250 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:57:42
@@ -134,7 +134,7 @@ error: any use of this value will cause an error
 LL | const SHL_I16_NEG_RANDOM: i16 = unsafe { intrinsics::unchecked_shl(5_16, -13) };
    | -----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                          |
-   |                                          Overflowing shift by 65523 in `unchecked_shl`
+   |                                          overflowing shift by 65523 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:59:42
@@ -142,7 +142,7 @@ error: any use of this value will cause an error
 LL | const SHL_I32_NEG_RANDOM: i32 = unsafe { intrinsics::unchecked_shl(5_i32, -25) };
    | -----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                          |
-   |                                          Overflowing shift by 4294967271 in `unchecked_shl`
+   |                                          overflowing shift by 4294967271 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:61:42
@@ -150,7 +150,7 @@ error: any use of this value will cause an error
 LL | const SHL_I64_NEG_RANDOM: i64 = unsafe { intrinsics::unchecked_shl(5_i64, -30) };
    | -----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                          |
-   |                                          Overflowing shift by 18446744073709551586 in `unchecked_shl`
+   |                                          overflowing shift by 18446744073709551586 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:63:44
@@ -158,7 +158,7 @@ error: any use of this value will cause an error
 LL | const SHL_I128_NEG_RANDOM: i128 = unsafe { intrinsics::unchecked_shl(5_i128, -93) };
    | -------------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                            |
-   |                                            Overflowing shift by 340282366920938463463374607431768211363 in `unchecked_shl`
+   |                                            overflowing shift by 340282366920938463463374607431768211363 in `unchecked_shl`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:70:29
@@ -166,7 +166,7 @@ error: any use of this value will cause an error
 LL | const SHR_U8: u8 = unsafe { intrinsics::unchecked_shr(5_u8, 8) };
    | ----------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                             |
-   |                             Overflowing shift by 8 in `unchecked_shr`
+   |                             overflowing shift by 8 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:72:31
@@ -174,7 +174,7 @@ error: any use of this value will cause an error
 LL | const SHR_U16: u16 = unsafe { intrinsics::unchecked_shr(5_u16, 16) };
    | ------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                               |
-   |                               Overflowing shift by 16 in `unchecked_shr`
+   |                               overflowing shift by 16 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:74:31
@@ -182,7 +182,7 @@ error: any use of this value will cause an error
 LL | const SHR_U32: u32 = unsafe { intrinsics::unchecked_shr(5_u32, 32) };
    | ------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                               |
-   |                               Overflowing shift by 32 in `unchecked_shr`
+   |                               overflowing shift by 32 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:76:31
@@ -190,7 +190,7 @@ error: any use of this value will cause an error
 LL | const SHR_U64: u64 = unsafe { intrinsics::unchecked_shr(5_u64, 64) };
    | ------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                               |
-   |                               Overflowing shift by 64 in `unchecked_shr`
+   |                               overflowing shift by 64 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:78:33
@@ -198,7 +198,7 @@ error: any use of this value will cause an error
 LL | const SHR_U128: u128 = unsafe { intrinsics::unchecked_shr(5_u128, 128) };
    | --------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                 |
-   |                                 Overflowing shift by 128 in `unchecked_shr`
+   |                                 overflowing shift by 128 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:83:29
@@ -206,7 +206,7 @@ error: any use of this value will cause an error
 LL | const SHR_I8: i8 = unsafe { intrinsics::unchecked_shr(5_i8, 8) };
    | ----------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                             |
-   |                             Overflowing shift by 8 in `unchecked_shr`
+   |                             overflowing shift by 8 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:85:31
@@ -214,7 +214,7 @@ error: any use of this value will cause an error
 LL | const SHR_I16: i16 = unsafe { intrinsics::unchecked_shr(5_16, 16) };
    | ------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                               |
-   |                               Overflowing shift by 16 in `unchecked_shr`
+   |                               overflowing shift by 16 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:87:31
@@ -222,7 +222,7 @@ error: any use of this value will cause an error
 LL | const SHR_I32: i32 = unsafe { intrinsics::unchecked_shr(5_i32, 32) };
    | ------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                               |
-   |                               Overflowing shift by 32 in `unchecked_shr`
+   |                               overflowing shift by 32 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:89:31
@@ -230,7 +230,7 @@ error: any use of this value will cause an error
 LL | const SHR_I64: i64 = unsafe { intrinsics::unchecked_shr(5_i64, 64) };
    | ------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                               |
-   |                               Overflowing shift by 64 in `unchecked_shr`
+   |                               overflowing shift by 64 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:91:33
@@ -238,7 +238,7 @@ error: any use of this value will cause an error
 LL | const SHR_I128: i128 = unsafe { intrinsics::unchecked_shr(5_i128, 128) };
    | --------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                 |
-   |                                 Overflowing shift by 128 in `unchecked_shr`
+   |                                 overflowing shift by 128 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:96:33
@@ -246,7 +246,7 @@ error: any use of this value will cause an error
 LL | const SHR_I8_NEG: i8 = unsafe { intrinsics::unchecked_shr(5_i8, -1) };
    | --------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                 |
-   |                                 Overflowing shift by 255 in `unchecked_shr`
+   |                                 overflowing shift by 255 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:98:35
@@ -254,7 +254,7 @@ error: any use of this value will cause an error
 LL | const SHR_I16_NEG: i16 = unsafe { intrinsics::unchecked_shr(5_16, -1) };
    | ----------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                   |
-   |                                   Overflowing shift by 65535 in `unchecked_shr`
+   |                                   overflowing shift by 65535 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:100:35
@@ -262,7 +262,7 @@ error: any use of this value will cause an error
 LL | const SHR_I32_NEG: i32 = unsafe { intrinsics::unchecked_shr(5_i32, -1) };
    | ----------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                   |
-   |                                   Overflowing shift by 4294967295 in `unchecked_shr`
+   |                                   overflowing shift by 4294967295 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:102:35
@@ -270,7 +270,7 @@ error: any use of this value will cause an error
 LL | const SHR_I64_NEG: i64 = unsafe { intrinsics::unchecked_shr(5_i64, -1) };
    | ----------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                   |
-   |                                   Overflowing shift by 18446744073709551615 in `unchecked_shr`
+   |                                   overflowing shift by 18446744073709551615 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:104:37
@@ -278,7 +278,7 @@ error: any use of this value will cause an error
 LL | const SHR_I128_NEG: i128 = unsafe { intrinsics::unchecked_shr(5_i128, -1) };
    | ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                     |
-   |                                     Overflowing shift by 340282366920938463463374607431768211455 in `unchecked_shr`
+   |                                     overflowing shift by 340282366920938463463374607431768211455 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:110:40
@@ -286,7 +286,7 @@ error: any use of this value will cause an error
 LL | const SHR_I8_NEG_RANDOM: i8 = unsafe { intrinsics::unchecked_shr(5_i8, -6) };
    | ---------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                        |
-   |                                        Overflowing shift by 250 in `unchecked_shr`
+   |                                        overflowing shift by 250 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:112:42
@@ -294,7 +294,7 @@ error: any use of this value will cause an error
 LL | const SHR_I16_NEG_RANDOM: i16 = unsafe { intrinsics::unchecked_shr(5_16, -13) };
    | -----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                          |
-   |                                          Overflowing shift by 65523 in `unchecked_shr`
+   |                                          overflowing shift by 65523 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:114:42
@@ -302,7 +302,7 @@ error: any use of this value will cause an error
 LL | const SHR_I32_NEG_RANDOM: i32 = unsafe { intrinsics::unchecked_shr(5_i32, -25) };
    | -----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                          |
-   |                                          Overflowing shift by 4294967271 in `unchecked_shr`
+   |                                          overflowing shift by 4294967271 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:116:42
@@ -310,7 +310,7 @@ error: any use of this value will cause an error
 LL | const SHR_I64_NEG_RANDOM: i64 = unsafe { intrinsics::unchecked_shr(5_i64, -30) };
    | -----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                          |
-   |                                          Overflowing shift by 18446744073709551586 in `unchecked_shr`
+   |                                          overflowing shift by 18446744073709551586 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:118:44
@@ -318,7 +318,7 @@ error: any use of this value will cause an error
 LL | const SHR_I128_NEG_RANDOM: i128 = unsafe { intrinsics::unchecked_shr(5_i128, -93) };
    | -------------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                                            |
-   |                                            Overflowing shift by 340282366920938463463374607431768211363 in `unchecked_shr`
+   |                                            overflowing shift by 340282366920938463463374607431768211363 in `unchecked_shr`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:123:25
@@ -326,7 +326,7 @@ error: any use of this value will cause an error
 LL | const _: u16 = unsafe { std::intrinsics::unchecked_add(40000u16, 30000) };
    | ------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                         |
-   |                         Overflow executing `unchecked_add`
+   |                         overflow executing `unchecked_add`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:126:25
@@ -334,7 +334,7 @@ error: any use of this value will cause an error
 LL | const _: u32 = unsafe { std::intrinsics::unchecked_sub(14u32, 22) };
    | ------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                         |
-   |                         Overflow executing `unchecked_sub`
+   |                         overflow executing `unchecked_sub`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:129:25
@@ -342,7 +342,7 @@ error: any use of this value will cause an error
 LL | const _: u16 = unsafe { std::intrinsics::unchecked_mul(300u16, 250u16) };
    | ------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                         |
-   |                         Overflow executing `unchecked_mul`
+   |                         overflow executing `unchecked_mul`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:132:25
@@ -358,7 +358,7 @@ error: any use of this value will cause an error
 LL | const _: i32 = unsafe { std::intrinsics::unchecked_div(i32::min_value(), -1) };
    | ------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                         |
-   |                         Overflow executing `unchecked_div`
+   |                         overflow executing `unchecked_div`
 
 error: any use of this value will cause an error
   --> $DIR/const-int-unchecked.rs:137:25
@@ -374,7 +374,7 @@ error: any use of this value will cause an error
 LL | const _: i32 = unsafe { std::intrinsics::unchecked_rem(i32::min_value(), -1) };
    | ------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
    |                         |
-   |                         Overflow executing `unchecked_rem`
+   |                         overflow executing `unchecked_rem`
 
 error: aborting due to 47 previous errors
 
diff --git a/src/test/ui/consts/dangling-alloc-id-ice.stderr b/src/test/ui/consts/dangling-alloc-id-ice.stderr
index bac9f555d271b..0e213555052c8 100644
--- a/src/test/ui/consts/dangling-alloc-id-ice.stderr
+++ b/src/test/ui/consts/dangling-alloc-id-ice.stderr
@@ -5,7 +5,7 @@ LL | / const FOO: &() = {
 LL | |     let y = ();
 LL | |     unsafe { Foo { y: &y }.long_live_the_unit }
 LL | | };
-   | |__^ type validation failed: encountered dangling pointer in final constant
+   | |__^ encountered dangling pointer in final constant
    |
    = note: `#[deny(const_err)]` on by default
 
diff --git a/src/test/ui/consts/dangling_raw_ptr.stderr b/src/test/ui/consts/dangling_raw_ptr.stderr
index 4748be37dffcf..4d4c2876c4598 100644
--- a/src/test/ui/consts/dangling_raw_ptr.stderr
+++ b/src/test/ui/consts/dangling_raw_ptr.stderr
@@ -5,7 +5,7 @@ LL | / const FOO: *const u32 = {
 LL | |     let x = 42;
 LL | |     &x
 LL | | };
-   | |__^ type validation failed: encountered dangling pointer in final constant
+   | |__^ encountered dangling pointer in final constant
    |
    = note: `#[deny(const_err)]` on by default
 
diff --git a/src/test/ui/consts/miri_unleashed/abi-mismatch.stderr b/src/test/ui/consts/miri_unleashed/abi-mismatch.stderr
index da00c49963eec..c7e902132e91a 100644
--- a/src/test/ui/consts/miri_unleashed/abi-mismatch.stderr
+++ b/src/test/ui/consts/miri_unleashed/abi-mismatch.stderr
@@ -16,7 +16,7 @@ error: any use of this value will cause an error
 LL |     my_fn();
    |     ^^^^^^^
    |     |
-   |     tried to call a function with ABI C using caller ABI Rust
+   |     calling a function with ABI C using caller ABI Rust
    |     inside call to `call_rust_fn` at $DIR/abi-mismatch.rs:13:17
 ...
 LL | const VAL: () = call_rust_fn(unsafe { std::mem::transmute(c_fn as extern "C" fn()) });
diff --git a/src/test/ui/consts/miri_unleashed/mutable_const.stderr b/src/test/ui/consts/miri_unleashed/mutable_const.stderr
index 86f27784701c6..8456e8ec6870d 100644
--- a/src/test/ui/consts/miri_unleashed/mutable_const.stderr
+++ b/src/test/ui/consts/miri_unleashed/mutable_const.stderr
@@ -11,7 +11,7 @@ LL | / const MUTATING_BEHIND_RAW: () = {
 LL | |     // Test that `MUTABLE_BEHIND_RAW` is actually immutable, by doing this at const time.
 LL | |     unsafe {
 LL | |         *MUTABLE_BEHIND_RAW = 99
-   | |         ^^^^^^^^^^^^^^^^^^^^^^^^ tried to modify constant memory
+   | |         ^^^^^^^^^^^^^^^^^^^^^^^^ writing to alloc1 which is read-only
 LL | |     }
 LL | | };
    | |__-
diff --git a/src/test/ui/consts/offset_from_ub.stderr b/src/test/ui/consts/offset_from_ub.stderr
index bbe3344b412b3..217530740079f 100644
--- a/src/test/ui/consts/offset_from_ub.stderr
+++ b/src/test/ui/consts/offset_from_ub.stderr
@@ -26,7 +26,7 @@ error: any use of this value will cause an error
 LL |           intrinsics::ptr_offset_from(self, origin)
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |           |
-   |           a memory access tried to interpret some bytes as a pointer
+   |           unable to turn bytes into a pointer
    |           inside call to `std::ptr::const_ptr::<impl *const u8>::offset_from` at $DIR/offset_from_ub.rs:28:14
    | 
   ::: $DIR/offset_from_ub.rs:26:1
@@ -81,7 +81,7 @@ error: any use of this value will cause an error
 LL |           intrinsics::ptr_offset_from(self, origin)
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |           |
-   |           a memory access tried to interpret some bytes as a pointer
+   |           unable to turn bytes into a pointer
    |           inside call to `std::ptr::const_ptr::<impl *const u8>::offset_from` at $DIR/offset_from_ub.rs:49:14
    | 
   ::: $DIR/offset_from_ub.rs:45:1
diff --git a/src/test/ui/consts/transmute-size-mismatch-before-typeck.stderr b/src/test/ui/consts/transmute-size-mismatch-before-typeck.stderr
index 296a55ef16076..5a47771459625 100644
--- a/src/test/ui/consts/transmute-size-mismatch-before-typeck.stderr
+++ b/src/test/ui/consts/transmute-size-mismatch-before-typeck.stderr
@@ -21,7 +21,7 @@ LL | const ZST: &[u8] = unsafe { std::mem::transmute(1usize) };
    |                             ^^^^^^^^^^^^^^^^^^^
    |
    = note: source type: `usize` (word size)
-   = note: target type: `&'static [u8]` (2 * word size)
+   = note: target type: `&[u8]` (2 * word size)
 
 error: could not evaluate constant pattern
   --> $DIR/transmute-size-mismatch-before-typeck.rs:10:9
diff --git a/src/test/ui/editions/edition-keywords-2018-2015-parsing.rs b/src/test/ui/editions/edition-keywords-2018-2015-parsing.rs
index dbc0465b08e77..d5ed9fb9a285e 100644
--- a/src/test/ui/editions/edition-keywords-2018-2015-parsing.rs
+++ b/src/test/ui/editions/edition-keywords-2018-2015-parsing.rs
@@ -1,9 +1,17 @@
 // edition:2018
 // aux-build:edition-kw-macro-2015.rs
 
+#![feature(async_closure)]
+
+fn main() {}
+
 #[macro_use]
 extern crate edition_kw_macro_2015;
 
+mod module {
+    pub fn r#async() {}
+}
+
 pub fn check_async() {
     let mut async = 1; //~ ERROR expected identifier, found keyword `async`
     let mut r#async = 1; // OK
@@ -17,4 +25,6 @@ pub fn check_async() {
     if passes_ident!(r#async) == 1 {} // OK
     module::async(); //~ ERROR expected identifier, found keyword `async`
     module::r#async(); // OK
+
+    let _recovery_witness: () = 0; //~ ERROR mismatched types
 }
diff --git a/src/test/ui/editions/edition-keywords-2018-2015-parsing.stderr b/src/test/ui/editions/edition-keywords-2018-2015-parsing.stderr
index e12d1a48463d7..28663563c6ccd 100644
--- a/src/test/ui/editions/edition-keywords-2018-2015-parsing.stderr
+++ b/src/test/ui/editions/edition-keywords-2018-2015-parsing.stderr
@@ -1,5 +1,5 @@
 error: expected identifier, found keyword `async`
-  --> $DIR/edition-keywords-2018-2015-parsing.rs:8:13
+  --> $DIR/edition-keywords-2018-2015-parsing.rs:16:13
    |
 LL |     let mut async = 1;
    |             ^^^^^ expected identifier, found keyword
@@ -10,7 +10,7 @@ LL |     let mut r#async = 1;
    |             ^^^^^^^
 
 error: expected identifier, found keyword `async`
-  --> $DIR/edition-keywords-2018-2015-parsing.rs:18:13
+  --> $DIR/edition-keywords-2018-2015-parsing.rs:26:13
    |
 LL |     module::async();
    |             ^^^^^ expected identifier, found keyword
@@ -21,13 +21,13 @@ LL |     module::r#async();
    |             ^^^^^^^
 
 error: no rules expected the token `r#async`
-  --> $DIR/edition-keywords-2018-2015-parsing.rs:12:31
+  --> $DIR/edition-keywords-2018-2015-parsing.rs:20:31
    |
 LL |     r#async = consumes_async!(r#async);
    |                               ^^^^^^^ no rules expected this token in macro call
 
 error: no rules expected the token `async`
-  --> $DIR/edition-keywords-2018-2015-parsing.rs:13:35
+  --> $DIR/edition-keywords-2018-2015-parsing.rs:21:35
    |
 LL |     r#async = consumes_async_raw!(async);
    |                                   ^^^^^ no rules expected this token in macro call
@@ -38,10 +38,19 @@ error: macro expansion ends with an incomplete expression: expected one of `move
 LL |     ($i: ident) => ($i)
    |                       ^ expected one of `move`, `|`, or `||`
    | 
-  ::: $DIR/edition-keywords-2018-2015-parsing.rs:16:8
+  ::: $DIR/edition-keywords-2018-2015-parsing.rs:24:8
    |
 LL |     if passes_ident!(async) == 1 {}
    |        -------------------- in this macro invocation
 
-error: aborting due to 5 previous errors
+error[E0308]: mismatched types
+  --> $DIR/edition-keywords-2018-2015-parsing.rs:29:33
+   |
+LL |     let _recovery_witness: () = 0;
+   |                            --   ^ expected `()`, found integer
+   |                            |
+   |                            expected due to this
+
+error: aborting due to 6 previous errors
 
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/editions/edition-keywords-2018-2018-parsing.rs b/src/test/ui/editions/edition-keywords-2018-2018-parsing.rs
index 5aca0839f0f15..044ab249f2c26 100644
--- a/src/test/ui/editions/edition-keywords-2018-2018-parsing.rs
+++ b/src/test/ui/editions/edition-keywords-2018-2018-parsing.rs
@@ -1,9 +1,17 @@
 // edition:2018
 // aux-build:edition-kw-macro-2018.rs
 
+#![feature(async_closure)]
+
+fn main() {}
+
 #[macro_use]
 extern crate edition_kw_macro_2018;
 
+mod module {
+    pub fn r#async() {}
+}
+
 pub fn check_async() {
     let mut async = 1; //~ ERROR expected identifier, found keyword `async`
     let mut r#async = 1; // OK
@@ -17,4 +25,6 @@ pub fn check_async() {
     if passes_ident!(r#async) == 1 {} // OK
     module::async(); //~ ERROR expected identifier, found keyword `async`
     module::r#async(); // OK
+
+    let _recovery_witness: () = 0; //~ ERROR mismatched types
 }
diff --git a/src/test/ui/editions/edition-keywords-2018-2018-parsing.stderr b/src/test/ui/editions/edition-keywords-2018-2018-parsing.stderr
index 110165fc077ca..cda7e65e437e8 100644
--- a/src/test/ui/editions/edition-keywords-2018-2018-parsing.stderr
+++ b/src/test/ui/editions/edition-keywords-2018-2018-parsing.stderr
@@ -1,5 +1,5 @@
 error: expected identifier, found keyword `async`
-  --> $DIR/edition-keywords-2018-2018-parsing.rs:8:13
+  --> $DIR/edition-keywords-2018-2018-parsing.rs:16:13
    |
 LL |     let mut async = 1;
    |             ^^^^^ expected identifier, found keyword
@@ -10,7 +10,7 @@ LL |     let mut r#async = 1;
    |             ^^^^^^^
 
 error: expected identifier, found keyword `async`
-  --> $DIR/edition-keywords-2018-2018-parsing.rs:18:13
+  --> $DIR/edition-keywords-2018-2018-parsing.rs:26:13
    |
 LL |     module::async();
    |             ^^^^^ expected identifier, found keyword
@@ -21,13 +21,13 @@ LL |     module::r#async();
    |             ^^^^^^^
 
 error: no rules expected the token `r#async`
-  --> $DIR/edition-keywords-2018-2018-parsing.rs:12:31
+  --> $DIR/edition-keywords-2018-2018-parsing.rs:20:31
    |
 LL |     r#async = consumes_async!(r#async);
    |                               ^^^^^^^ no rules expected this token in macro call
 
 error: no rules expected the token `async`
-  --> $DIR/edition-keywords-2018-2018-parsing.rs:13:35
+  --> $DIR/edition-keywords-2018-2018-parsing.rs:21:35
    |
 LL |     r#async = consumes_async_raw!(async);
    |                                   ^^^^^ no rules expected this token in macro call
@@ -38,10 +38,19 @@ error: macro expansion ends with an incomplete expression: expected one of `move
 LL |     ($i: ident) => ($i)
    |                       ^ expected one of `move`, `|`, or `||`
    | 
-  ::: $DIR/edition-keywords-2018-2018-parsing.rs:16:8
+  ::: $DIR/edition-keywords-2018-2018-parsing.rs:24:8
    |
 LL |     if passes_ident!(async) == 1 {}
    |        -------------------- in this macro invocation
 
-error: aborting due to 5 previous errors
+error[E0308]: mismatched types
+  --> $DIR/edition-keywords-2018-2018-parsing.rs:29:33
+   |
+LL |     let _recovery_witness: () = 0;
+   |                            --   ^ expected `()`, found integer
+   |                            |
+   |                            expected due to this
+
+error: aborting due to 6 previous errors
 
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/error-codes/E0121.stderr b/src/test/ui/error-codes/E0121.stderr
index 5a5c6b40c5afe..ad854837ae5bd 100644
--- a/src/test/ui/error-codes/E0121.stderr
+++ b/src/test/ui/error-codes/E0121.stderr
@@ -14,7 +14,7 @@ LL | static BAR: _ = "test";
    |             ^
    |             |
    |             not allowed in type signatures
-   |             help: replace `_` with the correct type: `&'static str`
+   |             help: replace `_` with the correct type: `&str`
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/error-codes/E0396-fixed.stderr b/src/test/ui/error-codes/E0396-fixed.stderr
index 7222f87da248f..685055525627e 100644
--- a/src/test/ui/error-codes/E0396-fixed.stderr
+++ b/src/test/ui/error-codes/E0396-fixed.stderr
@@ -4,7 +4,7 @@ error: any use of this value will cause an error
 LL | const VALUE: u8 = unsafe { *REG_ADDR };
    | ---------------------------^^^^^^^^^---
    |                            |
-   |                            a memory access tried to interpret some bytes as a pointer
+   |                            unable to turn bytes into a pointer
    |
    = note: `#[deny(const_err)]` on by default
 
diff --git a/src/test/ui/issues/issue-21174.stderr b/src/test/ui/issues/issue-21174.stderr
index 5ac5a8665bc69..09402c3d81410 100644
--- a/src/test/ui/issues/issue-21174.stderr
+++ b/src/test/ui/issues/issue-21174.stderr
@@ -4,8 +4,8 @@ error[E0512]: cannot transmute between types of different sizes, or dependently-
 LL |     let new: T::B = unsafe { std::mem::transmute(value) };
    |                              ^^^^^^^^^^^^^^^^^^^
    |
-   = note: source type: `<T as Trait<'a>>::A` (size can vary because of <T as Trait>::A)
-   = note: target type: `<T as Trait<'a>>::B` (size can vary because of <T as Trait>::B)
+   = note: source type: `<T as Trait>::A` (this type does not have a fixed size)
+   = note: target type: `<T as Trait>::B` (this type does not have a fixed size)
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/json-bom-plus-crlf-multifile.stderr b/src/test/ui/json-bom-plus-crlf-multifile.stderr
index ab0feb3c451ad..026943669f828 100644
--- a/src/test/ui/json-bom-plus-crlf-multifile.stderr
+++ b/src/test/ui/json-bom-plus-crlf-multifile.stderr
@@ -1,10 +1,6 @@
-{"message":"mismatched types","code":{"code":"E0308","explanation":"This error occurs when the compiler was unable to infer the concrete type of a
-variable. It can occur for several cases, the most common of which is a
-mismatch in the expected type that the compiler inferred for a variable's
-initializing expression, and the actual type explicitly assigned to the
-variable.
+{"message":"mismatched types","code":{"code":"E0308","explanation":"Expected type did not match the received type.
 
-For example:
+Erroneous code example:
 
 ```compile_fail,E0308
 let x: i32 = \"I am not a number!\";
@@ -15,15 +11,17 @@ let x: i32 = \"I am not a number!\";
 //      |
 //    type `i32` assigned to variable `x`
 ```
-"},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":621,"byte_end":622,"line_start":17,"line_end":17,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":22,"highlight_end":23}],"label":"expected struct `std::string::String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":612,"byte_end":618,"line_start":17,"line_end":17,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":621,"byte_end":622,"line_start":17,"line_end":17,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":22,"highlight_end":23}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf-multifile-aux.rs:17:22: error[E0308]: mismatched types
-"}
-{"message":"mismatched types","code":{"code":"E0308","explanation":"This error occurs when the compiler was unable to infer the concrete type of a
+
+This error occurs when the compiler was unable to infer the concrete type of a
 variable. It can occur for several cases, the most common of which is a
 mismatch in the expected type that the compiler inferred for a variable's
 initializing expression, and the actual type explicitly assigned to the
 variable.
+"},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":621,"byte_end":622,"line_start":17,"line_end":17,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":22,"highlight_end":23}],"label":"expected struct `std::string::String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":612,"byte_end":618,"line_start":17,"line_end":17,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":621,"byte_end":622,"line_start":17,"line_end":17,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":22,"highlight_end":23}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf-multifile-aux.rs:17:22: error[E0308]: mismatched types
+"}
+{"message":"mismatched types","code":{"code":"E0308","explanation":"Expected type did not match the received type.
 
-For example:
+Erroneous code example:
 
 ```compile_fail,E0308
 let x: i32 = \"I am not a number!\";
@@ -34,15 +32,17 @@ let x: i32 = \"I am not a number!\";
 //      |
 //    type `i32` assigned to variable `x`
 ```
-"},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":681,"byte_end":682,"line_start":19,"line_end":19,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1","highlight_start":22,"highlight_end":23}],"label":"expected struct `std::string::String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":672,"byte_end":678,"line_start":19,"line_end":19,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String = 1","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":681,"byte_end":682,"line_start":19,"line_end":19,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1","highlight_start":22,"highlight_end":23}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf-multifile-aux.rs:19:22: error[E0308]: mismatched types
-"}
-{"message":"mismatched types","code":{"code":"E0308","explanation":"This error occurs when the compiler was unable to infer the concrete type of a
+
+This error occurs when the compiler was unable to infer the concrete type of a
 variable. It can occur for several cases, the most common of which is a
 mismatch in the expected type that the compiler inferred for a variable's
 initializing expression, and the actual type explicitly assigned to the
 variable.
+"},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":681,"byte_end":682,"line_start":19,"line_end":19,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1","highlight_start":22,"highlight_end":23}],"label":"expected struct `std::string::String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":672,"byte_end":678,"line_start":19,"line_end":19,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String = 1","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":681,"byte_end":682,"line_start":19,"line_end":19,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1","highlight_start":22,"highlight_end":23}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf-multifile-aux.rs:19:22: error[E0308]: mismatched types
+"}
+{"message":"mismatched types","code":{"code":"E0308","explanation":"Expected type did not match the received type.
 
-For example:
+Erroneous code example:
 
 ```compile_fail,E0308
 let x: i32 = \"I am not a number!\";
@@ -53,15 +53,17 @@ let x: i32 = \"I am not a number!\";
 //      |
 //    type `i32` assigned to variable `x`
 ```
-"},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":745,"byte_end":746,"line_start":23,"line_end":23,"column_start":1,"column_end":2,"is_primary":true,"text":[{"text":"1;  // Error after the newline.","highlight_start":1,"highlight_end":2}],"label":"expected struct `std::string::String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":735,"byte_end":741,"line_start":22,"line_end":22,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String =","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":745,"byte_end":746,"line_start":23,"line_end":23,"column_start":1,"column_end":2,"is_primary":true,"text":[{"text":"1;  // Error after the newline.","highlight_start":1,"highlight_end":2}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf-multifile-aux.rs:23:1: error[E0308]: mismatched types
-"}
-{"message":"mismatched types","code":{"code":"E0308","explanation":"This error occurs when the compiler was unable to infer the concrete type of a
+
+This error occurs when the compiler was unable to infer the concrete type of a
 variable. It can occur for several cases, the most common of which is a
 mismatch in the expected type that the compiler inferred for a variable's
 initializing expression, and the actual type explicitly assigned to the
 variable.
+"},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":745,"byte_end":746,"line_start":23,"line_end":23,"column_start":1,"column_end":2,"is_primary":true,"text":[{"text":"1;  // Error after the newline.","highlight_start":1,"highlight_end":2}],"label":"expected struct `std::string::String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":735,"byte_end":741,"line_start":22,"line_end":22,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String =","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":745,"byte_end":746,"line_start":23,"line_end":23,"column_start":1,"column_end":2,"is_primary":true,"text":[{"text":"1;  // Error after the newline.","highlight_start":1,"highlight_end":2}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf-multifile-aux.rs:23:1: error[E0308]: mismatched types
+"}
+{"message":"mismatched types","code":{"code":"E0308","explanation":"Expected type did not match the received type.
 
-For example:
+Erroneous code example:
 
 ```compile_fail,E0308
 let x: i32 = \"I am not a number!\";
@@ -72,6 +74,12 @@ let x: i32 = \"I am not a number!\";
 //      |
 //    type `i32` assigned to variable `x`
 ```
+
+This error occurs when the compiler was unable to infer the concrete type of a
+variable. It can occur for several cases, the most common of which is a
+mismatch in the expected type that the compiler inferred for a variable's
+initializing expression, and the actual type explicitly assigned to the
+variable.
 "},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":801,"byte_end":809,"line_start":25,"line_end":26,"column_start":22,"column_end":6,"is_primary":true,"text":[{"text":"    let s : String = (","highlight_start":22,"highlight_end":23},{"text":"    );  // Error spanning the newline.","highlight_start":1,"highlight_end":6}],"label":"expected struct `std::string::String`, found `()`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf-multifile-aux.rs","byte_start":792,"byte_end":798,"line_start":25,"line_end":25,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String = (","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"$DIR/json-bom-plus-crlf-multifile-aux.rs:25:22: error[E0308]: mismatched types
 "}
 {"message":"aborting due to 4 previous errors","code":null,"level":"error","spans":[],"children":[],"rendered":"error: aborting due to 4 previous errors
diff --git a/src/test/ui/json-bom-plus-crlf.stderr b/src/test/ui/json-bom-plus-crlf.stderr
index 1dd898db3ad8c..735a46b8c875a 100644
--- a/src/test/ui/json-bom-plus-crlf.stderr
+++ b/src/test/ui/json-bom-plus-crlf.stderr
@@ -1,10 +1,6 @@
-{"message":"mismatched types","code":{"code":"E0308","explanation":"This error occurs when the compiler was unable to infer the concrete type of a
-variable. It can occur for several cases, the most common of which is a
-mismatch in the expected type that the compiler inferred for a variable's
-initializing expression, and the actual type explicitly assigned to the
-variable.
+{"message":"mismatched types","code":{"code":"E0308","explanation":"Expected type did not match the received type.
 
-For example:
+Erroneous code example:
 
 ```compile_fail,E0308
 let x: i32 = \"I am not a number!\";
@@ -15,15 +11,17 @@ let x: i32 = \"I am not a number!\";
 //      |
 //    type `i32` assigned to variable `x`
 ```
-"},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":606,"byte_end":607,"line_start":16,"line_end":16,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":22,"highlight_end":23}],"label":"expected struct `std::string::String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":597,"byte_end":603,"line_start":16,"line_end":16,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":606,"byte_end":607,"line_start":16,"line_end":16,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":22,"highlight_end":23}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf.rs:16:22: error[E0308]: mismatched types
-"}
-{"message":"mismatched types","code":{"code":"E0308","explanation":"This error occurs when the compiler was unable to infer the concrete type of a
+
+This error occurs when the compiler was unable to infer the concrete type of a
 variable. It can occur for several cases, the most common of which is a
 mismatch in the expected type that the compiler inferred for a variable's
 initializing expression, and the actual type explicitly assigned to the
 variable.
+"},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":606,"byte_end":607,"line_start":16,"line_end":16,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":22,"highlight_end":23}],"label":"expected struct `std::string::String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":597,"byte_end":603,"line_start":16,"line_end":16,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":606,"byte_end":607,"line_start":16,"line_end":16,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1;  // Error in the middle of line.","highlight_start":22,"highlight_end":23}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf.rs:16:22: error[E0308]: mismatched types
+"}
+{"message":"mismatched types","code":{"code":"E0308","explanation":"Expected type did not match the received type.
 
-For example:
+Erroneous code example:
 
 ```compile_fail,E0308
 let x: i32 = \"I am not a number!\";
@@ -34,15 +32,17 @@ let x: i32 = \"I am not a number!\";
 //      |
 //    type `i32` assigned to variable `x`
 ```
-"},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":666,"byte_end":667,"line_start":18,"line_end":18,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1","highlight_start":22,"highlight_end":23}],"label":"expected struct `std::string::String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":657,"byte_end":663,"line_start":18,"line_end":18,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String = 1","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":666,"byte_end":667,"line_start":18,"line_end":18,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1","highlight_start":22,"highlight_end":23}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf.rs:18:22: error[E0308]: mismatched types
-"}
-{"message":"mismatched types","code":{"code":"E0308","explanation":"This error occurs when the compiler was unable to infer the concrete type of a
+
+This error occurs when the compiler was unable to infer the concrete type of a
 variable. It can occur for several cases, the most common of which is a
 mismatch in the expected type that the compiler inferred for a variable's
 initializing expression, and the actual type explicitly assigned to the
 variable.
+"},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":666,"byte_end":667,"line_start":18,"line_end":18,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1","highlight_start":22,"highlight_end":23}],"label":"expected struct `std::string::String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":657,"byte_end":663,"line_start":18,"line_end":18,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String = 1","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":666,"byte_end":667,"line_start":18,"line_end":18,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"    let s : String = 1","highlight_start":22,"highlight_end":23}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf.rs:18:22: error[E0308]: mismatched types
+"}
+{"message":"mismatched types","code":{"code":"E0308","explanation":"Expected type did not match the received type.
 
-For example:
+Erroneous code example:
 
 ```compile_fail,E0308
 let x: i32 = \"I am not a number!\";
@@ -53,15 +53,17 @@ let x: i32 = \"I am not a number!\";
 //      |
 //    type `i32` assigned to variable `x`
 ```
-"},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":730,"byte_end":731,"line_start":22,"line_end":22,"column_start":1,"column_end":2,"is_primary":true,"text":[{"text":"1;  // Error after the newline.","highlight_start":1,"highlight_end":2}],"label":"expected struct `std::string::String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":720,"byte_end":726,"line_start":21,"line_end":21,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String =","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":730,"byte_end":731,"line_start":22,"line_end":22,"column_start":1,"column_end":2,"is_primary":true,"text":[{"text":"1;  // Error after the newline.","highlight_start":1,"highlight_end":2}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf.rs:22:1: error[E0308]: mismatched types
-"}
-{"message":"mismatched types","code":{"code":"E0308","explanation":"This error occurs when the compiler was unable to infer the concrete type of a
+
+This error occurs when the compiler was unable to infer the concrete type of a
 variable. It can occur for several cases, the most common of which is a
 mismatch in the expected type that the compiler inferred for a variable's
 initializing expression, and the actual type explicitly assigned to the
 variable.
+"},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":730,"byte_end":731,"line_start":22,"line_end":22,"column_start":1,"column_end":2,"is_primary":true,"text":[{"text":"1;  // Error after the newline.","highlight_start":1,"highlight_end":2}],"label":"expected struct `std::string::String`, found integer","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":720,"byte_end":726,"line_start":21,"line_end":21,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String =","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"try using a conversion method","code":null,"level":"help","spans":[{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":730,"byte_end":731,"line_start":22,"line_end":22,"column_start":1,"column_end":2,"is_primary":true,"text":[{"text":"1;  // Error after the newline.","highlight_start":1,"highlight_end":2}],"label":null,"suggested_replacement":"1.to_string()","suggestion_applicability":"MaybeIncorrect","expansion":null}],"children":[],"rendered":null}],"rendered":"$DIR/json-bom-plus-crlf.rs:22:1: error[E0308]: mismatched types
+"}
+{"message":"mismatched types","code":{"code":"E0308","explanation":"Expected type did not match the received type.
 
-For example:
+Erroneous code example:
 
 ```compile_fail,E0308
 let x: i32 = \"I am not a number!\";
@@ -72,6 +74,12 @@ let x: i32 = \"I am not a number!\";
 //      |
 //    type `i32` assigned to variable `x`
 ```
+
+This error occurs when the compiler was unable to infer the concrete type of a
+variable. It can occur for several cases, the most common of which is a
+mismatch in the expected type that the compiler inferred for a variable's
+initializing expression, and the actual type explicitly assigned to the
+variable.
 "},"level":"error","spans":[{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":786,"byte_end":794,"line_start":24,"line_end":25,"column_start":22,"column_end":6,"is_primary":true,"text":[{"text":"    let s : String = (","highlight_start":22,"highlight_end":23},{"text":"    );  // Error spanning the newline.","highlight_start":1,"highlight_end":6}],"label":"expected struct `std::string::String`, found `()`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"$DIR/json-bom-plus-crlf.rs","byte_start":777,"byte_end":783,"line_start":24,"line_end":24,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"    let s : String = (","highlight_start":13,"highlight_end":19}],"label":"expected due to this","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"$DIR/json-bom-plus-crlf.rs:24:22: error[E0308]: mismatched types
 "}
 {"message":"aborting due to 4 previous errors","code":null,"level":"error","spans":[],"children":[],"rendered":"error: aborting due to 4 previous errors
diff --git a/src/test/ui/lint/uninitialized-zeroed.stderr b/src/test/ui/lint/uninitialized-zeroed.stderr
index 6d669184deb3e..bf0562713a497 100644
--- a/src/test/ui/lint/uninitialized-zeroed.stderr
+++ b/src/test/ui/lint/uninitialized-zeroed.stderr
@@ -1,4 +1,4 @@
-error: the type `&'static T` does not permit zero-initialization
+error: the type `&T` does not permit zero-initialization
   --> $DIR/uninitialized-zeroed.rs:29:32
    |
 LL |         let _val: &'static T = mem::zeroed();
@@ -14,7 +14,7 @@ LL | #![deny(invalid_value)]
    |         ^^^^^^^^^^^^^
    = note: references must be non-null
 
-error: the type `&'static T` does not permit being left uninitialized
+error: the type `&T` does not permit being left uninitialized
   --> $DIR/uninitialized-zeroed.rs:30:32
    |
 LL |         let _val: &'static T = mem::uninitialized();
@@ -25,7 +25,7 @@ LL |         let _val: &'static T = mem::uninitialized();
    |
    = note: references must be non-null
 
-error: the type `Wrap<&'static T>` does not permit zero-initialization
+error: the type `Wrap<&T>` does not permit zero-initialization
   --> $DIR/uninitialized-zeroed.rs:32:38
    |
 LL |         let _val: Wrap<&'static T> = mem::zeroed();
@@ -40,7 +40,7 @@ note: references must be non-null (in this struct field)
 LL | struct Wrap<T> { wrapped: T }
    |                  ^^^^^^^^^^
 
-error: the type `Wrap<&'static T>` does not permit being left uninitialized
+error: the type `Wrap<&T>` does not permit being left uninitialized
   --> $DIR/uninitialized-zeroed.rs:33:38
    |
 LL |         let _val: Wrap<&'static T> = mem::uninitialized();
@@ -121,7 +121,7 @@ LL |         let _val: Void = mem::uninitialized();
    |
    = note: enums with no variants have no valid value
 
-error: the type `&'static i32` does not permit zero-initialization
+error: the type `&i32` does not permit zero-initialization
   --> $DIR/uninitialized-zeroed.rs:49:34
    |
 LL |         let _val: &'static i32 = mem::zeroed();
@@ -132,7 +132,7 @@ LL |         let _val: &'static i32 = mem::zeroed();
    |
    = note: references must be non-null
 
-error: the type `&'static i32` does not permit being left uninitialized
+error: the type `&i32` does not permit being left uninitialized
   --> $DIR/uninitialized-zeroed.rs:50:34
    |
 LL |         let _val: &'static i32 = mem::uninitialized();
@@ -366,7 +366,7 @@ LL |         let _val: NonBig = mem::uninitialized();
    |
    = note: `NonBig` must be initialized inside its custom valid range
 
-error: the type `&'static i32` does not permit zero-initialization
+error: the type `&i32` does not permit zero-initialization
   --> $DIR/uninitialized-zeroed.rs:84:34
    |
 LL |         let _val: &'static i32 = mem::transmute(0usize);
@@ -377,7 +377,7 @@ LL |         let _val: &'static i32 = mem::transmute(0usize);
    |
    = note: references must be non-null
 
-error: the type `&'static [i32]` does not permit zero-initialization
+error: the type `&[i32]` does not permit zero-initialization
   --> $DIR/uninitialized-zeroed.rs:85:36
    |
 LL |         let _val: &'static [i32] = mem::transmute((0usize, 0usize));
diff --git a/src/test/ui/macros/issue-61033-1.rs b/src/test/ui/macros/issue-61033-1.rs
index 8f85dec017f2a..18df3f6ee94c1 100644
--- a/src/test/ui/macros/issue-61033-1.rs
+++ b/src/test/ui/macros/issue-61033-1.rs
@@ -1,9 +1,10 @@
 // Regression test for issue #61033.
 
 macro_rules! test1 {
-    ($x:ident, $($tt:tt)*) => { $($tt)+ } //~ERROR this must repeat at least once
+    ($x:ident, $($tt:tt)*) => { $($tt)+ } //~ ERROR this must repeat at least once
 }
 
 fn main() {
     test1!(x,);
+    let _recovery_witness: () = 0; //~ ERROR mismatched types
 }
diff --git a/src/test/ui/macros/issue-61033-1.stderr b/src/test/ui/macros/issue-61033-1.stderr
index f3c68f4928dbb..18205c3436b0b 100644
--- a/src/test/ui/macros/issue-61033-1.stderr
+++ b/src/test/ui/macros/issue-61033-1.stderr
@@ -4,5 +4,14 @@ error: this must repeat at least once
 LL |     ($x:ident, $($tt:tt)*) => { $($tt)+ }
    |                                  ^^^^^
 
-error: aborting due to previous error
+error[E0308]: mismatched types
+  --> $DIR/issue-61033-1.rs:9:33
+   |
+LL |     let _recovery_witness: () = 0;
+   |                            --   ^ expected `()`, found integer
+   |                            |
+   |                            expected due to this
+
+error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/macros/issue-61033-2.rs b/src/test/ui/macros/issue-61033-2.rs
index 0799be10b96c7..1760ba1584d0b 100644
--- a/src/test/ui/macros/issue-61033-2.rs
+++ b/src/test/ui/macros/issue-61033-2.rs
@@ -5,7 +5,9 @@ macro_rules! test2 {
         $(* $id1:ident)*
         $(+ $id2:ident)*
     ) => {
-        $( //~ERROR meta-variable `id1` repeats 2 times
+        $(
+        //~^ ERROR meta-variable `id1` repeats 2 times
+        //~| ERROR meta-variable `id1` repeats 2 times
             $id1 + $id2 // $id1 and $id2 may repeat different numbers of times
         )*
     }
@@ -16,4 +18,8 @@ fn main() {
         * a * b
         + a + b + c
     }
+    test2! {
+        * a * b
+        + a + b + c + d
+    }
 }
diff --git a/src/test/ui/macros/issue-61033-2.stderr b/src/test/ui/macros/issue-61033-2.stderr
index bf502919cf794..cdfe7934a0cac 100644
--- a/src/test/ui/macros/issue-61033-2.stderr
+++ b/src/test/ui/macros/issue-61033-2.stderr
@@ -3,9 +3,22 @@ error: meta-variable `id1` repeats 2 times, but `id2` repeats 3 times
    |
 LL |           $(
    |  __________^
+LL | |
+LL | |
 LL | |             $id1 + $id2 // $id1 and $id2 may repeat different numbers of times
 LL | |         )*
    | |_________^
 
-error: aborting due to previous error
+error: meta-variable `id1` repeats 2 times, but `id2` repeats 4 times
+  --> $DIR/issue-61033-2.rs:8:10
+   |
+LL |           $(
+   |  __________^
+LL | |
+LL | |
+LL | |             $id1 + $id2 // $id1 and $id2 may repeat different numbers of times
+LL | |         )*
+   | |_________^
+
+error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/macros/local-ambiguity-multiple-parsing-options.rs b/src/test/ui/macros/local-ambiguity-multiple-parsing-options.rs
new file mode 100644
index 0000000000000..3967481098cff
--- /dev/null
+++ b/src/test/ui/macros/local-ambiguity-multiple-parsing-options.rs
@@ -0,0 +1,8 @@
+fn main() {}
+
+macro_rules! ambiguity {
+    ($($i:ident)* $j:ident) => {};
+}
+
+ambiguity!(error); //~ ERROR local ambiguity
+ambiguity!(error); //~ ERROR local ambiguity
diff --git a/src/test/ui/macros/local-ambiguity-multiple-parsing-options.stderr b/src/test/ui/macros/local-ambiguity-multiple-parsing-options.stderr
new file mode 100644
index 0000000000000..0ae56c422213c
--- /dev/null
+++ b/src/test/ui/macros/local-ambiguity-multiple-parsing-options.stderr
@@ -0,0 +1,14 @@
+error: local ambiguity: multiple parsing options: built-in NTs ident ('i') or ident ('j').
+  --> $DIR/local-ambiguity-multiple-parsing-options.rs:7:12
+   |
+LL | ambiguity!(error);
+   |            ^^^^^
+
+error: local ambiguity: multiple parsing options: built-in NTs ident ('i') or ident ('j').
+  --> $DIR/local-ambiguity-multiple-parsing-options.rs:8:12
+   |
+LL | ambiguity!(error);
+   |            ^^^^^
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/macros/macro-context.rs b/src/test/ui/macros/macro-context.rs
index 9130c3d921c52..13e179578ad01 100644
--- a/src/test/ui/macros/macro-context.rs
+++ b/src/test/ui/macros/macro-context.rs
@@ -4,6 +4,8 @@ macro_rules! m {
                             //~| ERROR macro expansion ignores token `typeof`
                             //~| ERROR macro expansion ignores token `;`
                             //~| ERROR macro expansion ignores token `;`
+                            //~| ERROR cannot find type `i` in this scope
+                            //~| ERROR cannot find value `i` in this scope
 }
 
 fn main() {
diff --git a/src/test/ui/macros/macro-context.stderr b/src/test/ui/macros/macro-context.stderr
index 2e712110689f8..17c7389812475 100644
--- a/src/test/ui/macros/macro-context.stderr
+++ b/src/test/ui/macros/macro-context.stderr
@@ -42,5 +42,29 @@ LL |     m!();
    |
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 4 previous errors
+error[E0412]: cannot find type `i` in this scope
+  --> $DIR/macro-context.rs:3:13
+   |
+LL |     () => ( i ; typeof );
+   |             ^ help: a builtin type with a similar name exists: `i8`
+...
+LL |     let a: m!();
+   |            ---- in this macro invocation
+   |
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0425]: cannot find value `i` in this scope
+  --> $DIR/macro-context.rs:3:13
+   |
+LL |     () => ( i ; typeof );
+   |             ^ help: a local variable with a similar name exists: `a`
+...
+LL |     let i = m!();
+   |             ---- in this macro invocation
+   |
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 6 previous errors
 
+Some errors have detailed explanations: E0412, E0425.
+For more information about an error, try `rustc --explain E0412`.
diff --git a/src/test/ui/macros/macro-match-nonterminal.rs b/src/test/ui/macros/macro-match-nonterminal.rs
index 6d4b32c9bc9a0..b23e5c71c03f0 100644
--- a/src/test/ui/macros/macro-match-nonterminal.rs
+++ b/src/test/ui/macros/macro-match-nonterminal.rs
@@ -1,4 +1,11 @@
-macro_rules! test { ($a, $b) => (()); } //~ ERROR missing fragment
+macro_rules! test {
+    ($a, $b) => {
+        //~^ ERROR missing fragment
+        //~| ERROR missing fragment
+        //~| WARN this was previously accepted
+        ()
+    };
+}
 
 fn main() {
     test!()
diff --git a/src/test/ui/macros/macro-match-nonterminal.stderr b/src/test/ui/macros/macro-match-nonterminal.stderr
index 1de8c5bd4b472..674ce3434aac6 100644
--- a/src/test/ui/macros/macro-match-nonterminal.stderr
+++ b/src/test/ui/macros/macro-match-nonterminal.stderr
@@ -1,8 +1,18 @@
 error: missing fragment specifier
-  --> $DIR/macro-match-nonterminal.rs:1:24
+  --> $DIR/macro-match-nonterminal.rs:2:8
    |
-LL | macro_rules! test { ($a, $b) => (()); }
-   |                        ^
+LL |     ($a, $b) => {
+   |        ^
 
-error: aborting due to previous error
+error: missing fragment specifier
+  --> $DIR/macro-match-nonterminal.rs:2:10
+   |
+LL |     ($a, $b) => {
+   |          ^^
+   |
+   = note: `#[deny(missing_fragment_specifier)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #40107 <https://github.com/rust-lang/rust/issues/40107>
+
+error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/macros/trace_faulty_macros.rs b/src/test/ui/macros/trace_faulty_macros.rs
index 627d58abf4ca2..a55f05414b206 100644
--- a/src/test/ui/macros/trace_faulty_macros.rs
+++ b/src/test/ui/macros/trace_faulty_macros.rs
@@ -13,7 +13,7 @@ macro_rules! pat_macro {
         pat_macro!(A{a:a, b:0, c:_, ..});
     };
     ($a:pat) => {
-        $a
+        $a //~ ERROR expected expression
     };
 }
 
diff --git a/src/test/ui/macros/trace_faulty_macros.stderr b/src/test/ui/macros/trace_faulty_macros.stderr
index a18e22e07f8bc..109b493b43717 100644
--- a/src/test/ui/macros/trace_faulty_macros.stderr
+++ b/src/test/ui/macros/trace_faulty_macros.stderr
@@ -49,5 +49,16 @@ LL |     my_recursive_macro!();
    = note: expanding `my_recursive_macro! {  }`
    = note: to `my_recursive_macro ! () ;`
 
-error: aborting due to 2 previous errors
+error: expected expression, found `A { a: a, b: 0, c: _, .. }`
+  --> $DIR/trace_faulty_macros.rs:16:9
+   |
+LL |         $a
+   |         ^^ expected expression
+...
+LL |     let a = pat_macro!();
+   |             ------------ in this macro invocation
+   |
+   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 3 previous errors
 
diff --git a/src/test/ui/parser/issue-62894.stderr b/src/test/ui/parser/issue-62894.stderr
index 6db380f7a7fe2..73e3552e3ec7a 100644
--- a/src/test/ui/parser/issue-62894.stderr
+++ b/src/test/ui/parser/issue-62894.stderr
@@ -42,6 +42,11 @@ LL | fn f() { assert_eq!(f(), (), assert_eq!(assert_eq!
 LL | 
 LL | fn main() {}
    | ^^ unexpected token
+   | 
+  ::: $SRC_DIR/libcore/macros/mod.rs:LL:COL
+   |
+LL |     ($left:expr, $right:expr) => ({
+   |      ---------- while parsing argument for this `expr` macro fragment
 
 error: aborting due to 4 previous errors
 
diff --git a/src/test/ui/parser/macro/issue-33569.rs b/src/test/ui/parser/macro/issue-33569.rs
index 9ed53519ceb31..80e2d7c6545ba 100644
--- a/src/test/ui/parser/macro/issue-33569.rs
+++ b/src/test/ui/parser/macro/issue-33569.rs
@@ -6,3 +6,5 @@ macro_rules! foo {
 }
 
 foo!();
+
+fn main() {}
diff --git a/src/test/ui/parser/macro/macro-repeat.rs b/src/test/ui/parser/macro/macro-repeat.rs
index 580a1daacbf31..3ffbea217e79e 100644
--- a/src/test/ui/parser/macro/macro-repeat.rs
+++ b/src/test/ui/parser/macro/macro-repeat.rs
@@ -1,9 +1,12 @@
 macro_rules! mac {
-    ( $($v:tt)* ) => (
-        $v  //~ ERROR still repeating at this depth
-    )
+    ( $($v:tt)* ) => {
+        $v
+        //~^ ERROR still repeating at this depth
+        //~| ERROR still repeating at this depth
+    };
 }
 
 fn main() {
     mac!(0);
+    mac!(1);
 }
diff --git a/src/test/ui/parser/macro/macro-repeat.stderr b/src/test/ui/parser/macro/macro-repeat.stderr
index c86684de74432..63554b197b91c 100644
--- a/src/test/ui/parser/macro/macro-repeat.stderr
+++ b/src/test/ui/parser/macro/macro-repeat.stderr
@@ -4,5 +4,11 @@ error: variable 'v' is still repeating at this depth
 LL |         $v
    |         ^^
 
-error: aborting due to previous error
+error: variable 'v' is still repeating at this depth
+  --> $DIR/macro-repeat.rs:3:9
+   |
+LL |         $v
+   |         ^^
+
+error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/parser/nt-parsing-has-recovery.rs b/src/test/ui/parser/nt-parsing-has-recovery.rs
new file mode 100644
index 0000000000000..ccbeb398af5ba
--- /dev/null
+++ b/src/test/ui/parser/nt-parsing-has-recovery.rs
@@ -0,0 +1,10 @@
+macro_rules! foo {
+    ($e:expr) => {}
+}
+
+foo!(1 + @); //~ ERROR expected expression, found `@`
+foo!(1 + @); //~ ERROR expected expression, found `@`
+
+fn main() {
+    let _recovery_witness: () = 0; //~ ERROR mismatched types
+}
diff --git a/src/test/ui/parser/nt-parsing-has-recovery.stderr b/src/test/ui/parser/nt-parsing-has-recovery.stderr
new file mode 100644
index 0000000000000..263c4ad53612e
--- /dev/null
+++ b/src/test/ui/parser/nt-parsing-has-recovery.stderr
@@ -0,0 +1,29 @@
+error: expected expression, found `@`
+  --> $DIR/nt-parsing-has-recovery.rs:5:10
+   |
+LL |     ($e:expr) => {}
+   |      ------- while parsing argument for this `expr` macro fragment
+...
+LL | foo!(1 + @);
+   |          ^ expected expression
+
+error: expected expression, found `@`
+  --> $DIR/nt-parsing-has-recovery.rs:6:10
+   |
+LL |     ($e:expr) => {}
+   |      ------- while parsing argument for this `expr` macro fragment
+...
+LL | foo!(1 + @);
+   |          ^ expected expression
+
+error[E0308]: mismatched types
+  --> $DIR/nt-parsing-has-recovery.rs:9:33
+   |
+LL |     let _recovery_witness: () = 0;
+   |                            --   ^ expected `()`, found integer
+   |                            |
+   |                            expected due to this
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/pattern/usefulness/always-inhabited-union-ref.rs b/src/test/ui/pattern/usefulness/always-inhabited-union-ref.rs
index 11eae2af9c95f..7d1cac8a442f5 100644
--- a/src/test/ui/pattern/usefulness/always-inhabited-union-ref.rs
+++ b/src/test/ui/pattern/usefulness/always-inhabited-union-ref.rs
@@ -21,7 +21,7 @@ fn uninhab_union() -> Foo {
 
 fn match_on_uninhab() {
     match uninhab_ref() {
-        //~^ ERROR non-exhaustive patterns: type `&'static !` is non-empty
+        //~^ ERROR non-exhaustive patterns: type `&!` is non-empty
     }
 
     match uninhab_union() {
diff --git a/src/test/ui/pattern/usefulness/always-inhabited-union-ref.stderr b/src/test/ui/pattern/usefulness/always-inhabited-union-ref.stderr
index 1b1096c977ad4..e1079f912d076 100644
--- a/src/test/ui/pattern/usefulness/always-inhabited-union-ref.stderr
+++ b/src/test/ui/pattern/usefulness/always-inhabited-union-ref.stderr
@@ -1,4 +1,4 @@
-error[E0004]: non-exhaustive patterns: type `&'static !` is non-empty
+error[E0004]: non-exhaustive patterns: type `&!` is non-empty
   --> $DIR/always-inhabited-union-ref.rs:23:11
    |
 LL |     match uninhab_ref() {
diff --git a/src/test/ui/proc-macro/derive-bad.rs b/src/test/ui/proc-macro/derive-bad.rs
index 62c0741b6697a..cb5188b5fb43f 100644
--- a/src/test/ui/proc-macro/derive-bad.rs
+++ b/src/test/ui/proc-macro/derive-bad.rs
@@ -3,11 +3,9 @@
 #[macro_use]
 extern crate derive_bad;
 
-#[derive(
-    A
-)]
-//~^^ ERROR proc-macro derive produced unparseable tokens
+#[derive(A)]
+//~^ ERROR proc-macro derive produced unparseable tokens
 //~| ERROR expected `:`, found `}`
-struct A;
+struct A; //~ ERROR the name `A` is defined multiple times
 
 fn main() {}
diff --git a/src/test/ui/proc-macro/derive-bad.stderr b/src/test/ui/proc-macro/derive-bad.stderr
index 8667396c98989..bc5ed9815238a 100644
--- a/src/test/ui/proc-macro/derive-bad.stderr
+++ b/src/test/ui/proc-macro/derive-bad.stderr
@@ -1,16 +1,28 @@
 error: expected `:`, found `}`
-  --> $DIR/derive-bad.rs:7:5
+  --> $DIR/derive-bad.rs:6:10
    |
-LL |     A
-   |     ^ expected `:`
+LL | #[derive(A)]
+   |          ^ expected `:`
    |
    = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: proc-macro derive produced unparseable tokens
-  --> $DIR/derive-bad.rs:7:5
+  --> $DIR/derive-bad.rs:6:10
    |
-LL |     A
-   |     ^
+LL | #[derive(A)]
+   |          ^
 
-error: aborting due to 2 previous errors
+error[E0428]: the name `A` is defined multiple times
+  --> $DIR/derive-bad.rs:9:1
+   |
+LL | #[derive(A)]
+   |          - previous definition of the type `A` here
+...
+LL | struct A;
+   | ^^^^^^^^^ `A` redefined here
+   |
+   = note: `A` must be defined only once in the type namespace of this module
+
+error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0428`.
diff --git a/src/test/ui/proc-macro/invalid-punct-ident-1.rs b/src/test/ui/proc-macro/invalid-punct-ident-1.rs
index 9de57da5af434..3f78dea917b19 100644
--- a/src/test/ui/proc-macro/invalid-punct-ident-1.rs
+++ b/src/test/ui/proc-macro/invalid-punct-ident-1.rs
@@ -14,3 +14,5 @@
 extern crate invalid_punct_ident;
 
 invalid_punct!(); //~ ERROR proc macro panicked
+
+fn main() {}
diff --git a/src/test/ui/proc-macro/invalid-punct-ident-2.rs b/src/test/ui/proc-macro/invalid-punct-ident-2.rs
index 79f72324b1d89..4e89e80ae7c41 100644
--- a/src/test/ui/proc-macro/invalid-punct-ident-2.rs
+++ b/src/test/ui/proc-macro/invalid-punct-ident-2.rs
@@ -14,3 +14,5 @@
 extern crate invalid_punct_ident;
 
 invalid_ident!(); //~ ERROR proc macro panicked
+
+fn main() {}
diff --git a/src/test/ui/proc-macro/invalid-punct-ident-3.rs b/src/test/ui/proc-macro/invalid-punct-ident-3.rs
index d01e9b699cac5..8d8ce8f932e71 100644
--- a/src/test/ui/proc-macro/invalid-punct-ident-3.rs
+++ b/src/test/ui/proc-macro/invalid-punct-ident-3.rs
@@ -14,3 +14,5 @@
 extern crate invalid_punct_ident;
 
 invalid_raw_ident!(); //~ ERROR proc macro panicked
+
+fn main() {}
diff --git a/src/test/ui/proc-macro/invalid-punct-ident-4.rs b/src/test/ui/proc-macro/invalid-punct-ident-4.rs
index e50f24deae343..59b347dac679c 100644
--- a/src/test/ui/proc-macro/invalid-punct-ident-4.rs
+++ b/src/test/ui/proc-macro/invalid-punct-ident-4.rs
@@ -3,5 +3,10 @@
 #[macro_use]
 extern crate invalid_punct_ident;
 
-lexer_failure!(); //~ ERROR proc macro panicked
-                  //~| ERROR unexpected closing delimiter: `)`
+lexer_failure!();
+//~^ ERROR proc macro panicked
+//~| ERROR unexpected closing delimiter: `)`
+
+fn main() {
+    let _recovery_witness: () = 0; //~ ERROR mismatched types
+}
diff --git a/src/test/ui/proc-macro/invalid-punct-ident-4.stderr b/src/test/ui/proc-macro/invalid-punct-ident-4.stderr
index fe3e55b31be5d..3b357aecea864 100644
--- a/src/test/ui/proc-macro/invalid-punct-ident-4.stderr
+++ b/src/test/ui/proc-macro/invalid-punct-ident-4.stderr
@@ -12,5 +12,14 @@ error: proc macro panicked
 LL | lexer_failure!();
    | ^^^^^^^^^^^^^^^^^
 
-error: aborting due to 2 previous errors
+error[E0308]: mismatched types
+  --> $DIR/invalid-punct-ident-4.rs:11:33
+   |
+LL |     let _recovery_witness: () = 0;
+   |                            --   ^ expected `()`, found integer
+   |                            |
+   |                            expected due to this
+
+error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/proc-macro/issue-36935.rs b/src/test/ui/proc-macro/issue-36935.rs
index f809592d5f449..5c43a564c00c2 100644
--- a/src/test/ui/proc-macro/issue-36935.rs
+++ b/src/test/ui/proc-macro/issue-36935.rs
@@ -5,6 +5,7 @@ extern crate test_macros;
 
 #[derive(Identity, Panic)] //~ ERROR proc-macro derive panicked
 struct Baz {
+    //~^ ERROR the name `Baz` is defined multiple times
     a: i32,
     b: i32,
 }
diff --git a/src/test/ui/proc-macro/issue-36935.stderr b/src/test/ui/proc-macro/issue-36935.stderr
index da4366eb668d6..2b2e28fdb2fda 100644
--- a/src/test/ui/proc-macro/issue-36935.stderr
+++ b/src/test/ui/proc-macro/issue-36935.stderr
@@ -6,5 +6,17 @@ LL | #[derive(Identity, Panic)]
    |
    = help: message: panic-derive
 
-error: aborting due to previous error
+error[E0428]: the name `Baz` is defined multiple times
+  --> $DIR/issue-36935.rs:7:1
+   |
+LL | struct Baz {
+   | ^^^^^^^^^^
+   | |
+   | `Baz` redefined here
+   | previous definition of the type `Baz` here
+   |
+   = note: `Baz` must be defined only once in the type namespace of this module
+
+error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0428`.
diff --git a/src/test/ui/regions/regions-free-region-ordering-caller.migrate.stderr b/src/test/ui/regions/regions-free-region-ordering-caller.migrate.stderr
index a33d3583552dc..06e1b0f1ac262 100644
--- a/src/test/ui/regions/regions-free-region-ordering-caller.migrate.stderr
+++ b/src/test/ui/regions/regions-free-region-ordering-caller.migrate.stderr
@@ -1,32 +1,54 @@
-error[E0623]: lifetime mismatch
+error[E0491]: in type `&'b &'a usize`, reference has a longer lifetime than the data it references
   --> $DIR/regions-free-region-ordering-caller.rs:11:12
    |
-LL | fn call2<'a, 'b>(a: &'a usize, b: &'b usize) {
-   |                     ---------     ---------
-   |                     |
-   |                     these two types are declared with different lifetimes...
 LL |     let z: Option<&'b &'a usize> = None;
-   |            ^^^^^^^^^^^^^^^^^^^^^ ...but data from `a` flows into `b` here
+   |            ^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the pointer is valid for the lifetime `'b` as defined on the function body at 10:14
+  --> $DIR/regions-free-region-ordering-caller.rs:10:14
+   |
+LL | fn call2<'a, 'b>(a: &'a usize, b: &'b usize) {
+   |              ^^
+note: but the referenced data is only valid for the lifetime `'a` as defined on the function body at 10:10
+  --> $DIR/regions-free-region-ordering-caller.rs:10:10
+   |
+LL | fn call2<'a, 'b>(a: &'a usize, b: &'b usize) {
+   |          ^^
 
-error[E0623]: lifetime mismatch
+error[E0491]: in type `&'b Paramd<'a>`, reference has a longer lifetime than the data it references
   --> $DIR/regions-free-region-ordering-caller.rs:17:12
    |
-LL | fn call3<'a, 'b>(a: &'a usize, b: &'b usize) {
-   |                     ---------     ---------
-   |                     |
-   |                     these two types are declared with different lifetimes...
-LL |     let y: Paramd<'a> = Paramd { x: a };
 LL |     let z: Option<&'b Paramd<'a>> = None;
-   |            ^^^^^^^^^^^^^^^^^^^^^^ ...but data from `a` flows into `b` here
+   |            ^^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the pointer is valid for the lifetime `'b` as defined on the function body at 15:14
+  --> $DIR/regions-free-region-ordering-caller.rs:15:14
+   |
+LL | fn call3<'a, 'b>(a: &'a usize, b: &'b usize) {
+   |              ^^
+note: but the referenced data is only valid for the lifetime `'a` as defined on the function body at 15:10
+  --> $DIR/regions-free-region-ordering-caller.rs:15:10
+   |
+LL | fn call3<'a, 'b>(a: &'a usize, b: &'b usize) {
+   |          ^^
 
-error[E0623]: lifetime mismatch
+error[E0491]: in type `&'a &'b usize`, reference has a longer lifetime than the data it references
   --> $DIR/regions-free-region-ordering-caller.rs:22:12
    |
-LL | fn call4<'a, 'b>(a: &'a usize, b: &'b usize) {
-   |                     ---------     --------- these two types are declared with different lifetimes...
 LL |     let z: Option<&'a &'b usize> = None;
-   |            ^^^^^^^^^^^^^^^^^^^^^ ...but data from `b` flows into `a` here
+   |            ^^^^^^^^^^^^^^^^^^^^^
+   |
+note: the pointer is valid for the lifetime `'a` as defined on the function body at 21:10
+  --> $DIR/regions-free-region-ordering-caller.rs:21:10
+   |
+LL | fn call4<'a, 'b>(a: &'a usize, b: &'b usize) {
+   |          ^^
+note: but the referenced data is only valid for the lifetime `'b` as defined on the function body at 21:14
+  --> $DIR/regions-free-region-ordering-caller.rs:21:14
+   |
+LL | fn call4<'a, 'b>(a: &'a usize, b: &'b usize) {
+   |              ^^
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0623`.
+For more information about this error, try `rustc --explain E0491`.
diff --git a/src/test/ui/regions/regions-free-region-ordering-caller.rs b/src/test/ui/regions/regions-free-region-ordering-caller.rs
index c0b12f23cdba7..2bf4734cf7380 100644
--- a/src/test/ui/regions/regions-free-region-ordering-caller.rs
+++ b/src/test/ui/regions/regions-free-region-ordering-caller.rs
@@ -8,18 +8,18 @@
 struct Paramd<'a> { x: &'a usize }
 
 fn call2<'a, 'b>(a: &'a usize, b: &'b usize) {
-    let z: Option<&'b &'a usize> = None;//[migrate]~ ERROR E0623
+    let z: Option<&'b &'a usize> = None;//[migrate]~ ERROR E0491
     //[nll]~^ ERROR lifetime may not live long enough
 }
 
 fn call3<'a, 'b>(a: &'a usize, b: &'b usize) {
     let y: Paramd<'a> = Paramd { x: a };
-    let z: Option<&'b Paramd<'a>> = None;//[migrate]~ ERROR E0623
+    let z: Option<&'b Paramd<'a>> = None;//[migrate]~ ERROR E0491
     //[nll]~^ ERROR lifetime may not live long enough
 }
 
 fn call4<'a, 'b>(a: &'a usize, b: &'b usize) {
-    let z: Option<&'a &'b usize> = None;//[migrate]~ ERROR E0623
+    let z: Option<&'a &'b usize> = None;//[migrate]~ ERROR E0491
     //[nll]~^ ERROR lifetime may not live long enough
 }
 
diff --git a/src/test/ui/suggestions/const-no-type.rs b/src/test/ui/suggestions/const-no-type.rs
index 99200a965dd21..6b79697e9839e 100644
--- a/src/test/ui/suggestions/const-no-type.rs
+++ b/src/test/ui/suggestions/const-no-type.rs
@@ -43,4 +43,4 @@ static S = Vec::<String>::new();
 static mut SM = "abc";
 //~^ ERROR missing type for `static mut` item
 //~| HELP provide a type for the item
-//~| SUGGESTION &'static str
+//~| SUGGESTION &str
diff --git a/src/test/ui/suggestions/const-no-type.stderr b/src/test/ui/suggestions/const-no-type.stderr
index c4f17109dc5c7..a7b5aa5e5b124 100644
--- a/src/test/ui/suggestions/const-no-type.stderr
+++ b/src/test/ui/suggestions/const-no-type.stderr
@@ -14,7 +14,7 @@ error: missing type for `static mut` item
   --> $DIR/const-no-type.rs:43:12
    |
 LL | static mut SM = "abc";
-   |            ^^ help: provide a type for the item: `SM: &'static str`
+   |            ^^ help: provide a type for the item: `SM: &str`
 
 error: missing type for `const` item
   --> $DIR/const-no-type.rs:14:7
diff --git a/src/test/ui/test-attrs/test-attr-non-associated-functions.rs b/src/test/ui/test-attrs/test-attr-non-associated-functions.rs
index e475f5b4a75a5..31e567c396067 100644
--- a/src/test/ui/test-attrs/test-attr-non-associated-functions.rs
+++ b/src/test/ui/test-attrs/test-attr-non-associated-functions.rs
@@ -6,7 +6,13 @@ struct A {}
 
 impl A {
     #[test]
-    fn new() -> A { //~ ERROR `#[test]` attribute is only allowed on non associated functions
+    fn new() -> A {
+        //~^ ERROR `#[test]` attribute is only allowed on non associated functions
+        A {}
+    }
+    #[test]
+    fn recovery_witness() -> A {
+        //~^ ERROR `#[test]` attribute is only allowed on non associated functions
         A {}
     }
 }
diff --git a/src/test/ui/test-attrs/test-attr-non-associated-functions.stderr b/src/test/ui/test-attrs/test-attr-non-associated-functions.stderr
index cb3ae51823e45..a81b8f3980c37 100644
--- a/src/test/ui/test-attrs/test-attr-non-associated-functions.stderr
+++ b/src/test/ui/test-attrs/test-attr-non-associated-functions.stderr
@@ -2,9 +2,19 @@ error: `#[test]` attribute is only allowed on non associated functions
   --> $DIR/test-attr-non-associated-functions.rs:9:5
    |
 LL | /     fn new() -> A {
+LL | |
 LL | |         A {}
 LL | |     }
    | |_____^
 
-error: aborting due to previous error
+error: `#[test]` attribute is only allowed on non associated functions
+  --> $DIR/test-attr-non-associated-functions.rs:14:5
+   |
+LL | /     fn recovery_witness() -> A {
+LL | |
+LL | |         A {}
+LL | |     }
+   | |_____^
+
+error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/transmute/main.stderr b/src/test/ui/transmute/main.stderr
index c72876e050f05..4e781318329bf 100644
--- a/src/test/ui/transmute/main.stderr
+++ b/src/test/ui/transmute/main.stderr
@@ -4,8 +4,7 @@ error[E0512]: cannot transmute between types of different sizes, or dependently-
 LL |     transmute(x)
    |     ^^^^^^^^^
    |
-   = note: source type: `<C as TypeConstructor<'a>>::T` (size can vary because of <C as TypeConstructor>::T)
-   = note: target type: `<C as TypeConstructor<'b>>::T` (size can vary because of <C as TypeConstructor>::T)
+   = note: `<C as TypeConstructor>::T` does not have a fixed size
 
 error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
   --> $DIR/main.rs:20:17
diff --git a/src/test/ui/type/ascription/issue-47666.rs b/src/test/ui/type/ascription/issue-47666.rs
index ceb1dd89daea9..8035de4a48a92 100644
--- a/src/test/ui/type/ascription/issue-47666.rs
+++ b/src/test/ui/type/ascription/issue-47666.rs
@@ -1,5 +1,7 @@
 fn main() {
     let _ = Option:Some(vec![0, 1]); //~ ERROR expected type, found
+    //~^ ERROR expected value, found enum `Option`
+    //~| ERROR expected type, found variant `Some`
 }
 
 // This case isn't currently being handled gracefully due to the macro invocation.
diff --git a/src/test/ui/type/ascription/issue-47666.stderr b/src/test/ui/type/ascription/issue-47666.stderr
index f4c9240ab5372..3cd3be70aa75b 100644
--- a/src/test/ui/type/ascription/issue-47666.stderr
+++ b/src/test/ui/type/ascription/issue-47666.stderr
@@ -13,5 +13,35 @@ LL |     let _ = Option:Some(vec![0, 1]);
    = note: see issue #23416 <https://github.com/rust-lang/rust/issues/23416> for more information
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to previous error
+error[E0423]: expected value, found enum `Option`
+  --> $DIR/issue-47666.rs:2:13
+   |
+LL |     let _ = Option:Some(vec![0, 1]);
+   |             ^^^^^^
+   |
+help: try using one of the enum's variants
+   |
+LL |     let _ = std::option::Option::None:Some(vec![0, 1]);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     let _ = std::option::Option::Some:Some(vec![0, 1]);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0573]: expected type, found variant `Some`
+  --> $DIR/issue-47666.rs:2:20
+   |
+LL |     let _ = Option:Some(vec![0, 1]);
+   |                    ^^^^^^^^^^^^^^^^ not a type
+   |
+help: try using the variant's enum
+   |
+LL |     let _ = Option:std::option::Option;
+   |                    ^^^^^^^^^^^^^^^^^^^
+help: maybe you meant to write a path separator here
+   |
+LL |     let _ = Option::Some(vec![0, 1]);
+   |                   ^^
+
+error: aborting due to 3 previous errors
 
+Some errors have detailed explanations: E0423, E0573.
+For more information about an error, try `rustc --explain E0423`.
diff --git a/src/test/ui/typeck/typeck_type_placeholder_item.stderr b/src/test/ui/typeck/typeck_type_placeholder_item.stderr
index f2d02f70f4a66..dc86ab30dfe41 100644
--- a/src/test/ui/typeck/typeck_type_placeholder_item.stderr
+++ b/src/test/ui/typeck/typeck_type_placeholder_item.stderr
@@ -70,7 +70,7 @@ LL | static TEST3: _ = "test";
    |               ^
    |               |
    |               not allowed in type signatures
-   |               help: replace `_` with the correct type: `&'static str`
+   |               help: replace `_` with the correct type: `&str`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
   --> $DIR/typeck_type_placeholder_item.rs:15:15
@@ -232,7 +232,7 @@ LL |     static FN_TEST3: _ = "test";
    |                      ^
    |                      |
    |                      not allowed in type signatures
-   |                      help: replace `_` with the correct type: `&'static str`
+   |                      help: replace `_` with the correct type: `&str`
 
 error[E0121]: the type placeholder `_` is not allowed within types on item signatures
   --> $DIR/typeck_type_placeholder_item.rs:88:22