Rollup of 10 pull requests

Cargo.lock

@@ -4440,6 +4440,8 @@ dependencies = [
  "rustc_target",
  "smallvec",
  "tracing",
+ "tracing-subscriber",
+ "tracing-tree",
 ]
 
 [[package]]

compiler/rustc_ast_lowering/src/expr.rs

@@ -157,7 +157,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     hir::ExprKind::AddrOf(*k, *m, ohs)
                 }
                 ExprKind::Let(pat, scrutinee, span, is_recovered) => {
-                    hir::ExprKind::Let(self.arena.alloc(hir::Let {
+                    hir::ExprKind::Let(self.arena.alloc(hir::LetExpr {
                         span: self.lower_span(*span),
                         pat: self.lower_pat(pat),
                         ty: None,

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -434,10 +434,6 @@ fn check_opaque_type_parameter_valid(
     // Only check the parent generics, which will ignore any of the
     // duplicated lifetime args that come from reifying late-bounds.
     for (i, arg) in opaque_type_key.args.iter().take(parent_generics.count()).enumerate() {
-        if let Err(guar) = arg.error_reported() {
-            return Err(guar);
-        }
-
         let arg_is_param = match arg.unpack() {
             GenericArgKind::Type(ty) => matches!(ty.kind(), ty::Param(_)),
             GenericArgKind::Lifetime(lt) if is_ty_alias => {

compiler/rustc_hir/src/hir.rs

@@ -1259,7 +1259,7 @@ pub struct Arm<'hir> {
 /// In an `if let`, imagine it as `if (let <pat> = <expr>) { ... }`; in a let-else, it is part of
 /// the desugaring to if-let. Only let-else supports the type annotation at present.
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
-pub struct Let<'hir> {
+pub struct LetExpr<'hir> {
     pub span: Span,
     pub pat: &'hir Pat<'hir>,
     pub ty: Option<&'hir Ty<'hir>>,
@@ -1852,7 +1852,7 @@ pub enum ExprKind<'hir> {
     ///
     /// These are not `Local` and only occur as expressions.
     /// The `let Some(x) = foo()` in `if let Some(x) = foo()` is an example of `Let(..)`.
-    Let(&'hir Let<'hir>),
+    Let(&'hir LetExpr<'hir>),
     /// An `if` block, with an optional else block.
     ///
     /// I.e., `if <expr> { <expr> } else { <expr> }`.

compiler/rustc_hir/src/intravisit.rs

@@ -753,7 +753,7 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr<'v>)
         ExprKind::DropTemps(ref subexpression) => {
             try_visit!(visitor.visit_expr(subexpression));
         }
-        ExprKind::Let(Let { span: _, pat, ty, init, is_recovered: _ }) => {
+        ExprKind::Let(LetExpr { span: _, pat, ty, init, is_recovered: _ }) => {
             // match the visit order in walk_local
             try_visit!(visitor.visit_expr(init));
             try_visit!(visitor.visit_pat(pat));

compiler/rustc_hir_pretty/src/lib.rs

@@ -1387,7 +1387,7 @@ impl<'a> State<'a> {
                 // Print `}`:
                 self.bclose_maybe_open(expr.span, true);
             }
-            hir::ExprKind::Let(&hir::Let { pat, ty, init, .. }) => {
+            hir::ExprKind::Let(&hir::LetExpr { pat, ty, init, .. }) => {
                 self.print_let(pat, ty, init);
             }
             hir::ExprKind::If(test, blk, elseopt) => {

compiler/rustc_hir_typeck/src/_match.rs

@@ -317,7 +317,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         err.note("`if` expressions without `else` evaluate to `()`");
         err.help("consider adding an `else` block that evaluates to the expected type");
         *error = true;
-        if let ExprKind::Let(hir::Let { span, pat, init, .. }) = cond_expr.kind
+        if let ExprKind::Let(hir::LetExpr { span, pat, init, .. }) = cond_expr.kind
             && let ExprKind::Block(block, _) = then_expr.kind
             // Refutability checks occur on the MIR, so we approximate it here by checking
             // if we have an enum with a single variant or a struct in the pattern.

compiler/rustc_hir_typeck/src/expr.rs

@@ -1261,7 +1261,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
-    pub(super) fn check_expr_let(&self, let_expr: &'tcx hir::Let<'tcx>, hir_id: HirId) -> Ty<'tcx> {
+    pub(super) fn check_expr_let(
+        &self,
+        let_expr: &'tcx hir::LetExpr<'tcx>,
+        hir_id: HirId,
+    ) -> Ty<'tcx> {
         // for let statements, this is done in check_stmt
         let init = let_expr.init;
         self.warn_if_unreachable(init.hir_id, init.span, "block in `let` expression");

compiler/rustc_hir_typeck/src/expr_use_visitor.rs

@@ -245,7 +245,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
                 }
             }
 
-            hir::ExprKind::Let(hir::Let { pat, init, .. }) => {
+            hir::ExprKind::Let(hir::LetExpr { pat, init, .. }) => {
                 self.walk_local(init, pat, None, |t| t.borrow_expr(init, ty::ImmBorrow))
             }
 

compiler/rustc_hir_typeck/src/gather_locals.rs

@@ -29,7 +29,7 @@ impl<'a> DeclOrigin<'a> {
     }
 }
 
-/// A declaration is an abstraction of [hir::Local] and [hir::Let].
+/// A declaration is an abstraction of [hir::Local] and [hir::LetExpr].
 ///
 /// It must have a hir_id, as this is how we connect gather_locals to the check functions.
 pub(super) struct Declaration<'a> {
@@ -48,9 +48,9 @@ impl<'a> From<&'a hir::Local<'a>> for Declaration<'a> {
     }
 }
 
-impl<'a> From<(&'a hir::Let<'a>, hir::HirId)> for Declaration<'a> {
-    fn from((let_expr, hir_id): (&'a hir::Let<'a>, hir::HirId)) -> Self {
-        let hir::Let { pat, ty, span, init, is_recovered: _ } = *let_expr;
+impl<'a> From<(&'a hir::LetExpr<'a>, hir::HirId)> for Declaration<'a> {
+    fn from((let_expr, hir_id): (&'a hir::LetExpr<'a>, hir::HirId)) -> Self {
+        let hir::LetExpr { pat, ty, span, init, is_recovered: _ } = *let_expr;
         Declaration { hir_id, pat, ty, span, init: Some(init), origin: DeclOrigin::LetExpr }
     }
 }

compiler/rustc_infer/src/infer/opaque_types/mod.rs

@@ -94,9 +94,6 @@ impl<'tcx> InferCtxt<'tcx> {
         cause: &ObligationCause<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> InferResult<'tcx, ()> {
-        if a.references_error() || b.references_error() {
-            return Ok(InferOk { value: (), obligations: vec![] });
-        }
         let process = |a: Ty<'tcx>, b: Ty<'tcx>| match *a.kind() {
             ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) if def_id.is_local() => {
                 let def_id = def_id.expect_local();

compiler/rustc_middle/src/ty/region.rs

@@ -251,6 +251,7 @@ impl<'tcx> Region<'tcx> {
             }
             ty::ReError(_) => {
                 flags = flags | TypeFlags::HAS_FREE_REGIONS;
+                flags = flags | TypeFlags::HAS_ERROR;
             }
         }
 

compiler/rustc_mir_transform/src/coverage/counters.rs

@@ -1,13 +1,12 @@
+use std::fmt::{self, Debug};
+
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::graph::WithNumNodes;
-use rustc_index::bit_set::BitSet;
 use rustc_index::IndexVec;
-use rustc_middle::mir::coverage::*;
+use rustc_middle::mir::coverage::{CounterId, CovTerm, Expression, ExpressionId, Op};
 
-use super::graph::{BasicCoverageBlock, CoverageGraph, TraverseCoverageGraphWithLoops};
-
-use std::fmt::{self, Debug};
+use crate::coverage::graph::{BasicCoverageBlock, CoverageGraph, TraverseCoverageGraphWithLoops};
 
 /// The coverage counter or counter expression associated with a particular
 /// BCB node or BCB edge.
@@ -18,10 +17,6 @@ pub(super) enum BcbCounter {
 }
 
 impl BcbCounter {
-    fn is_expression(&self) -> bool {
-        matches!(self, Self::Expression { .. })
-    }
-
     pub(super) fn as_term(&self) -> CovTerm {
         match *self {
             BcbCounter::Counter { id, .. } => CovTerm::Counter(id),
@@ -60,10 +55,6 @@ pub(super) struct CoverageCounters {
     /// We currently don't iterate over this map, but if we do in the future,
     /// switch it back to `FxIndexMap` to avoid query stability hazards.
     bcb_edge_counters: FxHashMap<(BasicCoverageBlock, BasicCoverageBlock), BcbCounter>,
-    /// Tracks which BCBs have a counter associated with some incoming edge.
-    /// Only used by assertions, to verify that BCBs with incoming edge
-    /// counters do not have their own physical counters (expressions are allowed).
-    bcb_has_incoming_edge_counters: BitSet<BasicCoverageBlock>,
     /// Table of expression data, associating each expression ID with its
     /// corresponding operator (+ or -) and its LHS/RHS operands.
     expressions: IndexVec<ExpressionId, Expression>,
@@ -83,7 +74,6 @@ impl CoverageCounters {
             counter_increment_sites: IndexVec::new(),
             bcb_counters: IndexVec::from_elem_n(None, num_bcbs),
             bcb_edge_counters: FxHashMap::default(),
-            bcb_has_incoming_edge_counters: BitSet::new_empty(num_bcbs),
             expressions: IndexVec::new(),
         };
 
@@ -122,14 +112,6 @@ impl CoverageCounters {
     }
 
     fn set_bcb_counter(&mut self, bcb: BasicCoverageBlock, counter_kind: BcbCounter) -> BcbCounter {
-        assert!(
-            // If the BCB has an edge counter (to be injected into a new `BasicBlock`), it can also
-            // have an expression (to be injected into an existing `BasicBlock` represented by this
-            // `BasicCoverageBlock`).
-            counter_kind.is_expression() || !self.bcb_has_incoming_edge_counters.contains(bcb),
-            "attempt to add a `Counter` to a BCB target with existing incoming edge counters"
-        );
-
         if let Some(replaced) = self.bcb_counters[bcb].replace(counter_kind) {
             bug!(
                 "attempt to set a BasicCoverageBlock coverage counter more than once; \
@@ -146,19 +128,6 @@ impl CoverageCounters {
         to_bcb: BasicCoverageBlock,
         counter_kind: BcbCounter,
     ) -> BcbCounter {
-        // If the BCB has an edge counter (to be injected into a new `BasicBlock`), it can also
-        // have an expression (to be injected into an existing `BasicBlock` represented by this
-        // `BasicCoverageBlock`).
-        if let Some(node_counter) = self.bcb_counter(to_bcb)
-            && !node_counter.is_expression()
-        {
-            bug!(
-                "attempt to add an incoming edge counter from {from_bcb:?} \
-                when the target BCB already has {node_counter:?}"
-            );
-        }
-
-        self.bcb_has_incoming_edge_counters.insert(to_bcb);
         if let Some(replaced) = self.bcb_edge_counters.insert((from_bcb, to_bcb), counter_kind) {
             bug!(
                 "attempt to set an edge counter more than once; from_bcb: \

compiler/rustc_pattern_analysis/Cargo.toml

@@ -22,6 +22,10 @@ smallvec = { version = "1.8.1", features = ["union"] }
 tracing = "0.1"
 # tidy-alphabetical-end
 
+[dev-dependencies]
+tracing-subscriber = { version = "0.3.3", default-features = false, features = ["fmt", "env-filter", "ansi"] }
+tracing-tree = "0.2.0"
+
 [features]
 default = ["rustc"]
 rustc = [

compiler/rustc_pattern_analysis/src/constructor.rs

@@ -819,6 +819,81 @@ impl<Cx: PatCx> Constructor<Cx> {
             }
         })
     }
+
+    pub(crate) fn fmt_fields(
+        &self,
+        f: &mut fmt::Formatter<'_>,
+        ty: &Cx::Ty,
+        mut fields: impl Iterator<Item = impl fmt::Debug>,
+    ) -> fmt::Result {
+        let mut first = true;
+        let mut start_or_continue = |s| {
+            if first {
+                first = false;
+                ""
+            } else {
+                s
+            }
+        };
+        let mut start_or_comma = || start_or_continue(", ");
+
+        match self {
+            Struct | Variant(_) | UnionField => {
+                Cx::write_variant_name(f, self, ty)?;
+                // Without `cx`, we can't know which field corresponds to which, so we can't
+                // get the names of the fields. Instead we just display everything as a tuple
+                // struct, which should be good enough.
+                write!(f, "(")?;
+                for p in fields {
+                    write!(f, "{}{:?}", start_or_comma(), p)?;
+                }
+                write!(f, ")")?;
+            }
+            // Note: given the expansion of `&str` patterns done in `expand_pattern`, we should
+            // be careful to detect strings here. However a string literal pattern will never
+            // be reported as a non-exhaustiveness witness, so we can ignore this issue.
+            Ref => {
+                write!(f, "&{:?}", &fields.next().unwrap())?;
+            }
+            Slice(slice) => {
+                write!(f, "[")?;
+                match slice.kind {
+                    SliceKind::FixedLen(_) => {
+                        for p in fields {
+                            write!(f, "{}{:?}", start_or_comma(), p)?;
+                        }
+                    }
+                    SliceKind::VarLen(prefix_len, _) => {
+                        for p in fields.by_ref().take(prefix_len) {
+                            write!(f, "{}{:?}", start_or_comma(), p)?;
+                        }
+                        write!(f, "{}..", start_or_comma())?;
+                        for p in fields {
+                            write!(f, "{}{:?}", start_or_comma(), p)?;
+                        }
+                    }
+                }
+                write!(f, "]")?;
+            }
+            Bool(b) => write!(f, "{b}")?,
+            // Best-effort, will render signed ranges incorrectly
+            IntRange(range) => write!(f, "{range:?}")?,
+            F32Range(lo, hi, end) => write!(f, "{lo}{end}{hi}")?,
+            F64Range(lo, hi, end) => write!(f, "{lo}{end}{hi}")?,
+            Str(value) => write!(f, "{value:?}")?,
+            Opaque(..) => write!(f, "<constant pattern>")?,
+            Or => {
+                for pat in fields {
+                    write!(f, "{}{:?}", start_or_continue(" | "), pat)?;
+                }
+            }
+            Never => write!(f, "!")?,
+            Wildcard | Missing | NonExhaustive | Hidden | PrivateUninhabited => {
+                write!(f, "_ : {:?}", ty)?
+            }
+        }
+        Ok(())
+    }
 }
 
 #[derive(Debug, Clone, Copy)]

compiler/rustc_pattern_analysis/src/lib.rs

@@ -49,6 +49,12 @@ pub mod index {
         }
     }
 
+    impl<V> FromIterator<V> for IdxContainer<usize, V> {
+        fn from_iter<T: IntoIterator<Item = V>>(iter: T) -> Self {
+            Self(iter.into_iter().enumerate().collect())
+        }
+    }
+
     #[derive(Debug)]
     pub struct IdxSet<T>(pub rustc_hash::FxHashSet<T>);
     impl<T: Idx> IdxSet<T> {
@@ -120,7 +126,8 @@ pub trait PatCx: Sized + fmt::Debug {
     /// `DeconstructedPat`. Only invoqued when `pat.ctor()` is `Struct | Variant(_) | UnionField`.
     fn write_variant_name(
         f: &mut fmt::Formatter<'_>,
-        pat: &crate::pat::DeconstructedPat<Self>,
+        ctor: &crate::constructor::Constructor<Self>,
+        ty: &Self::Ty,
     ) -> fmt::Result;
 
     /// Raise a bug.