introduce universes to NLL type check

src/Cargo.lock

@@ -87,7 +87,7 @@ dependencies = [
 
 [[package]]
 name = "atty"
-version = "0.2.11"
+version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "libc 0.2.42 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -187,7 +187,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 name = "cargo"
 version = "0.30.0"
 dependencies = [
- "atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "atty 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "bufstream 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "clap 2.32.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "core-foundation 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -303,7 +303,7 @@ version = "2.32.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "ansi_term 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "atty 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "bitflags 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "strsim 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "textwrap 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -622,7 +622,7 @@ name = "env_logger"
 version = "0.5.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "atty 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "humantime 1.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1844,7 +1844,7 @@ name = "rustc-ap-rustc_errors"
 version = "182.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "atty 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-ap-rustc_data_structures 182.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-ap-serialize 182.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-ap-syntax_pos 182.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2097,7 +2097,7 @@ dependencies = [
 name = "rustc_errors"
 version = "0.0.0"
 dependencies = [
- "atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "atty 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_data_structures 0.0.0",
  "serialize 0.0.0",
  "syntax_pos 0.0.0",
@@ -3056,7 +3056,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum ansi_term 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ee49baf6cb617b853aa8d93bf420db2383fab46d314482ca2803b40d5fde979b"
 "checksum arrayvec 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)" = "a1e964f9e24d588183fcb43503abda40d288c8657dfc27311516ce2f05675aef"
 "checksum assert_cli 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)" = "98589b0e465a6c510d95fceebd365bb79bedece7f6e18a480897f2015f85ec51"
-"checksum atty 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "9a7d5b8723950951411ee34d271d99dddcc2035a16ab25310ea2c8cfd4369652"
+"checksum atty 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)" = "2fc4a1aa4c24c0718a250f0681885c1af91419d242f29eb8f2ab28502d80dbd1"
 "checksum backtrace 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)" = "89a47830402e9981c5c41223151efcced65a0510c13097c769cede7efb34782a"
 "checksum backtrace-sys 0.1.23 (registry+https://github.com/rust-lang/crates.io-index)" = "bff67d0c06556c0b8e6b5f090f0eac52d950d9dfd1d35ba04e4ca3543eaf6a7e"
 "checksum bitflags 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "aad18937a628ec6abcd26d1489012cc0e18c21798210f491af69ded9b881106d"

src/librustc/dep_graph/graph.rs

@@ -39,7 +39,6 @@ pub struct DepGraph {
     fingerprints: Lrc<Lock<IndexVec<DepNodeIndex, Fingerprint>>>
 }
 
-
 newtype_index!(DepNodeIndex);
 
 impl DepNodeIndex {

src/librustc/infer/higher_ranked/mod.rs

@@ -617,6 +617,18 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         debug!("leak_check: skol_map={:?}",
                skol_map);
 
+        // If the user gave `-Zno-leak-check`, then skip the leak
+        // check completely. This is wildly unsound and also not
+        // unlikely to cause an ICE or two. It is intended for use
+        // only during a transition period, in which the MIR typeck
+        // uses the "universe-style" check, and the rest of typeck
+        // uses the more conservative leak check.  Since the leak
+        // check is more conservative, we can't test the
+        // universe-style check without disabling it.
+        if self.tcx.sess.opts.debugging_opts.no_leak_check {
+            return Ok(());
+        }
+
         let new_vars = self.region_vars_confined_to_snapshot(snapshot);
         for (&skol_br, &skol) in skol_map {
             // The inputs to a skolemized variable can only

src/librustc/infer/mod.rs

@@ -377,7 +377,23 @@ pub enum NLLRegionVariableOrigin {
     // elsewhere. This origin indices we've got one of those.
     FreeRegion,
 
-    Inferred(::mir::visit::TyContext),
+    BoundRegion(ty::UniverseIndex),
+
+    Existential,
+}
+
+impl NLLRegionVariableOrigin {
+    pub fn is_universal(self) -> bool {
+        match self {
+            NLLRegionVariableOrigin::FreeRegion => true,
+            NLLRegionVariableOrigin::BoundRegion(..) => true,
+            NLLRegionVariableOrigin::Existential => false,
+        }
+    }
+
+    pub fn is_existential(self) -> bool {
+        !self.is_universal()
+    }
 }
 
 #[derive(Copy, Clone, Debug)]
@@ -1381,6 +1397,17 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
     fn universe(&self) -> ty::UniverseIndex {
         self.universe.get()
     }
+
+    /// Create and return a new subunivese of the current universe;
+    /// update `self.universe` to that new subuniverse. At present,
+    /// used only in the NLL subtyping code, which uses the new
+    /// universe-based scheme instead of the more limited leak-check
+    /// scheme.
+    pub fn create_subuniverse(&self) -> ty::UniverseIndex {
+        let u = self.universe.get().subuniverse();
+        self.universe.set(u);
+        u
+    }
 }
 
 impl<'a, 'gcx, 'tcx> TypeTrace<'tcx> {

src/librustc/lib.rs

@@ -69,6 +69,7 @@
 #![feature(trusted_len)]
 #![feature(vec_remove_item)]
 #![feature(catch_expr)]
+#![feature(step_trait)]
 #![feature(integer_atomics)]
 #![feature(test)]
 #![feature(in_band_lifetimes)]

src/librustc/mir/traversal.rs

@@ -9,7 +9,6 @@
 // except according to those terms.
 
 use rustc_data_structures::bitvec::BitVector;
-use rustc_data_structures::indexed_vec::Idx;
 
 use super::*;
 
@@ -33,7 +32,7 @@ use super::*;
 #[derive(Clone)]
 pub struct Preorder<'a, 'tcx: 'a> {
     mir: &'a Mir<'tcx>,
-    visited: BitVector,
+    visited: BitVector<BasicBlock>,
     worklist: Vec<BasicBlock>,
 }
 
@@ -58,7 +57,7 @@ impl<'a, 'tcx> Iterator for Preorder<'a, 'tcx> {
 
     fn next(&mut self) -> Option<(BasicBlock, &'a BasicBlockData<'tcx>)> {
         while let Some(idx) = self.worklist.pop() {
-            if !self.visited.insert(idx.index()) {
+            if !self.visited.insert(idx) {
                 continue;
             }
 
@@ -107,7 +106,7 @@ impl<'a, 'tcx> ExactSizeIterator for Preorder<'a, 'tcx> {}
 /// A Postorder traversal of this graph is `D B C A` or `D C B A`
 pub struct Postorder<'a, 'tcx: 'a> {
     mir: &'a Mir<'tcx>,
-    visited: BitVector,
+    visited: BitVector<BasicBlock>,
     visit_stack: Vec<(BasicBlock, Successors<'a>)>
 }
 
@@ -123,7 +122,7 @@ impl<'a, 'tcx> Postorder<'a, 'tcx> {
         let data = &po.mir[root];
 
         if let Some(ref term) = data.terminator {
-            po.visited.insert(root.index());
+            po.visited.insert(root);
             po.visit_stack.push((root, term.successors()));
             po.traverse_successor();
         }
@@ -190,8 +189,8 @@ impl<'a, 'tcx> Postorder<'a, 'tcx> {
                 break;
             };
 
-            if self.visited.insert(bb.index()) {
-                if let Some(ref term) = self.mir[bb].terminator {
+            if self.visited.insert(bb) {
+                if let Some(term) = &self.mir[bb].terminator {
                     self.visit_stack.push((bb, term.successors()));
                 }
             }

src/librustc/session/config.rs

@@ -1353,6 +1353,8 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
           "generate build artifacts that are compatible with linker-based LTO."),
     no_parallel_llvm: bool = (false, parse_bool, [UNTRACKED],
           "don't run LLVM in parallel (while keeping codegen-units and ThinLTO)"),
+    no_leak_check: bool = (false, parse_bool, [UNTRACKED],
+        "disables the 'leak check' for subtyping; unsound, but useful for tests"),
 }
 
 pub fn default_lib_output() -> CrateType {

src/librustc/ty/mod.rs

@@ -1481,14 +1481,27 @@ impl<'tcx> InstantiatedPredicates<'tcx> {
 /// type name in a non-zero universe is a skolemized type -- an
 /// idealized representative of "types in general" that we use for
 /// checking generic functions.
-#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
 pub struct UniverseIndex(u32);
 
 impl UniverseIndex {
     /// The root universe, where things that the user defined are
     /// visible.
     pub const ROOT: Self = UniverseIndex(0);
 
+    /// The "max universe" -- this isn't really a valid universe, but
+    /// it's useful sometimes as a "starting value" when you are
+    /// taking the minimum of a (non-empty!) set of universes.
+    pub const MAX: Self = UniverseIndex(::std::u32::MAX);
+
+    /// Creates a universe index from the given integer.  Not to be
+    /// used lightly lest you pick a bad value. But sometimes we
+    /// convert universe indicies into integers and back for various
+    /// reasons.
+    pub fn from_u32(index: u32) -> Self {
+        UniverseIndex(index)
+    }
+
     /// A "subuniverse" corresponds to being inside a `forall` quantifier.
     /// So, for example, suppose we have this type in universe `U`:
     ///
@@ -1504,6 +1517,11 @@ impl UniverseIndex {
         UniverseIndex(self.0.checked_add(1).unwrap())
     }
 
+    /// True if the names in this universe are a subset of the names in `other`.
+    pub fn is_subset_of(self, other: UniverseIndex) -> bool {
+        self.0 <= other.0
+    }
+
     pub fn as_u32(&self) -> u32 {
         self.0
     }
@@ -1513,6 +1531,12 @@ impl UniverseIndex {
     }
 }
 
+impl fmt::Debug for UniverseIndex {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "U{}", self.as_u32())
+    }
+}
+
 impl From<u32> for UniverseIndex {
     fn from(index: u32) -> Self {
         UniverseIndex(index)

src/librustc_codegen_llvm/debuginfo/create_scope_map.rs

@@ -65,7 +65,7 @@ pub fn create_mir_scopes(cx: &CodegenCx, mir: &Mir, debug_context: &FunctionDebu
     let mut has_variables = BitVector::new(mir.source_scopes.len());
     for var in mir.vars_iter() {
         let decl = &mir.local_decls[var];
-        has_variables.insert(decl.visibility_scope.index());
+        has_variables.insert(decl.visibility_scope);
     }
 
     // Instantiate all scopes.
@@ -79,7 +79,7 @@ pub fn create_mir_scopes(cx: &CodegenCx, mir: &Mir, debug_context: &FunctionDebu
 
 fn make_mir_scope(cx: &CodegenCx,
                   mir: &Mir,
-                  has_variables: &BitVector,
+                  has_variables: &BitVector<SourceScope>,
                   debug_context: &FunctionDebugContextData,
                   scope: SourceScope,
                   scopes: &mut IndexVec<SourceScope, MirDebugScope>) {
@@ -102,7 +102,7 @@ fn make_mir_scope(cx: &CodegenCx,
         return;
     };
 
-    if !has_variables.contains(scope.index()) {
+    if !has_variables.contains(scope) {
         // Do not create a DIScope if there are no variables
         // defined in this MIR Scope, to avoid debuginfo bloat.
 

src/librustc_codegen_llvm/mir/analyze.rs

@@ -22,7 +22,7 @@ use rustc::ty::layout::LayoutOf;
 use type_of::LayoutLlvmExt;
 use super::FunctionCx;
 
-pub fn non_ssa_locals<'a, 'tcx>(fx: &FunctionCx<'a, 'tcx>) -> BitVector {
+pub fn non_ssa_locals<'a, 'tcx>(fx: &FunctionCx<'a, 'tcx>) -> BitVector<mir::Local> {
     let mir = fx.mir;
     let mut analyzer = LocalAnalyzer::new(fx);
 
@@ -54,7 +54,7 @@ pub fn non_ssa_locals<'a, 'tcx>(fx: &FunctionCx<'a, 'tcx>) -> BitVector {
 struct LocalAnalyzer<'mir, 'a: 'mir, 'tcx: 'a> {
     fx: &'mir FunctionCx<'a, 'tcx>,
     dominators: Dominators<mir::BasicBlock>,
-    non_ssa_locals: BitVector,
+    non_ssa_locals: BitVector<mir::Local>,
     // The location of the first visited direct assignment to each
     // local, or an invalid location (out of bounds `block` index).
     first_assignment: IndexVec<mir::Local, Location>
@@ -90,7 +90,7 @@ impl<'mir, 'a, 'tcx> LocalAnalyzer<'mir, 'a, 'tcx> {
 
     fn not_ssa(&mut self, local: mir::Local) {
         debug!("marking {:?} as non-SSA", local);
-        self.non_ssa_locals.insert(local.index());
+        self.non_ssa_locals.insert(local);
     }
 
     fn assign(&mut self, local: mir::Local, location: Location) {

src/librustc_codegen_llvm/mir/mod.rs

@@ -268,7 +268,7 @@ pub fn codegen_mir<'a, 'tcx: 'a>(
                 let debug_scope = fx.scopes[decl.visibility_scope];
                 let dbg = debug_scope.is_valid() && bx.sess().opts.debuginfo == FullDebugInfo;
 
-                if !memory_locals.contains(local.index()) && !dbg {
+                if !memory_locals.contains(local) && !dbg {
                     debug!("alloc: {:?} ({}) -> operand", local, name);
                     return LocalRef::new_operand(bx.cx, layout);
                 }
@@ -291,7 +291,7 @@ pub fn codegen_mir<'a, 'tcx: 'a>(
                     debug!("alloc: {:?} (return place) -> place", local);
                     let llretptr = llvm::get_param(llfn, 0);
                     LocalRef::Place(PlaceRef::new_sized(llretptr, layout, layout.align))
-                } else if memory_locals.contains(local.index()) {
+                } else if memory_locals.contains(local) {
                     debug!("alloc: {:?} -> place", local);
                     LocalRef::Place(PlaceRef::alloca(&bx, layout, &format!("{:?}", local)))
                 } else {
@@ -415,7 +415,7 @@ fn create_funclets<'a, 'tcx>(
 fn arg_local_refs<'a, 'tcx>(bx: &Builder<'a, 'tcx>,
                             fx: &FunctionCx<'a, 'tcx>,
                             scopes: &IndexVec<mir::SourceScope, debuginfo::MirDebugScope>,
-                            memory_locals: &BitVector)
+                            memory_locals: &BitVector<mir::Local>)
                             -> Vec<LocalRef<'tcx>> {
     let mir = fx.mir;
     let tcx = bx.tcx();
@@ -487,7 +487,7 @@ fn arg_local_refs<'a, 'tcx>(bx: &Builder<'a, 'tcx>,
             llarg_idx += 1;
         }
 
-        if arg_scope.is_none() && !memory_locals.contains(local.index()) {
+        if arg_scope.is_none() && !memory_locals.contains(local) {
             // We don't have to cast or keep the argument in the alloca.
             // FIXME(eddyb): We should figure out how to use llvm.dbg.value instead
             // of putting everything in allocas just so we can use llvm.dbg.declare.