Auto merge of #43743 - michaelwoerister:gcx-tcx-switcheroo, r=eddyb

Some assorted region hashing fixes.

This PR contains three changes.
1. It changes what we implement `HashStable` for. Previously, the trait was implemented for things in the local `TyCtxt`. That was OK, since we only invoked hashing with a `TyCtxt<'_,  'tcx, 'tcx>` where there is no difference. With query result hashing this becomes a problem though. So we now implement `HashStable` for things in `'gcx`.
2. The PR makes the regular `HashStable` implementation *not* anonymize late-bound regions anymore. It's a waste of computing resources and it's not clear that it would always be correct to do so.
3. The PR adds an option for stable hashing to treat all regions as erased and uses this new option when computing the `TypeId`. This should help with https://github.com/rust-lang/rust/issues/41875.

I did not add a test case for (3) since that's not possible yet. But it looks like @zackmdavis has something in the pipeline there `:)`.

r? @eddyb

6 files changed, 50 insertions, 34 deletions

diff --git a/src/librustc/ich/impls_mir.rs b/src/librustc/ich/impls_mir.rs
index c20864183f4..faf579186e5 100644
--- a/src/librustc/ich/impls_mir.rs
+++ b/src/librustc/ich/impls_mir.rs
@@ -33,7 +33,7 @@ impl_stable_hash_for!(struct mir::UpvarDecl { debug_name, by_ref });
 impl_stable_hash_for!(struct mir::BasicBlockData<'tcx> { statements, terminator, is_cleanup });
 
 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for mir::Terminator<'tcx> {
+for mir::Terminator<'gcx> {
     #[inline]
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
@@ -125,7 +125,7 @@ impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for mir::P
 }
 
 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for mir::TerminatorKind<'tcx> {
+for mir::TerminatorKind<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -186,7 +186,7 @@ for mir::TerminatorKind<'tcx> {
 }
 
 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for mir::AssertMessage<'tcx> {
+for mir::AssertMessage<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -207,7 +207,7 @@ for mir::AssertMessage<'tcx> {
 impl_stable_hash_for!(struct mir::Statement<'tcx> { source_info, kind });
 
 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for mir::StatementKind<'tcx> {
+for mir::StatementKind<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -244,7 +244,7 @@ for mir::StatementKind<'tcx> {
 }
 
 impl<'a, 'gcx, 'tcx, T> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-    for mir::ValidationOperand<'tcx, T>
+    for mir::ValidationOperand<'gcx, T>
     where T: HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
 {
     fn hash_stable<W: StableHasherResult>(&self,
@@ -260,7 +260,7 @@ impl<'a, 'gcx, 'tcx, T> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
 
 impl_stable_hash_for!(enum mir::ValidationOp { Acquire, Release, Suspend(extent) });
 
-impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for mir::Lvalue<'tcx> {
+impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for mir::Lvalue<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -280,7 +280,7 @@ impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for mir::L
 }
 
 impl<'a, 'gcx, 'tcx, B, V, T> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for mir::Projection<'tcx, B, V, T>
+for mir::Projection<'gcx, B, V, T>
     where B: HashStable<StableHashingContext<'a, 'gcx, 'tcx>>,
           V: HashStable<StableHashingContext<'a, 'gcx, 'tcx>>,
           T: HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
@@ -299,7 +299,7 @@ for mir::Projection<'tcx, B, V, T>
 }
 
 impl<'a, 'gcx, 'tcx, V, T> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for mir::ProjectionElem<'tcx, V, T>
+for mir::ProjectionElem<'gcx, V, T>
     where V: HashStable<StableHashingContext<'a, 'gcx, 'tcx>>,
           T: HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
 {
@@ -335,7 +335,7 @@ for mir::ProjectionElem<'tcx, V, T>
 
 impl_stable_hash_for!(struct mir::VisibilityScopeData { span, parent_scope });
 
-impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for mir::Operand<'tcx> {
+impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for mir::Operand<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -352,7 +352,7 @@ impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for mir::O
     }
 }
 
-impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for mir::Rvalue<'tcx> {
+impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for mir::Rvalue<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -413,7 +413,7 @@ impl_stable_hash_for!(enum mir::CastKind {
 });
 
 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for mir::AggregateKind<'tcx> {
+for mir::AggregateKind<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -469,7 +469,7 @@ impl_stable_hash_for!(enum mir::NullOp {
 
 impl_stable_hash_for!(struct mir::Constant<'tcx> { span, ty, literal });
 
-impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for mir::Literal<'tcx> {
+impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for mir::Literal<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
diff --git a/src/librustc/ich/impls_ty.rs b/src/librustc/ich/impls_ty.rs
index cd64348044f..8a37d7bab44 100644
--- a/src/librustc/ich/impls_ty.rs
+++ b/src/librustc/ich/impls_ty.rs
@@ -20,7 +20,7 @@ use syntax_pos::symbol::InternedString;
 use ty;
 
 impl<'a, 'gcx, 'tcx, T> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for &'tcx ty::Slice<T>
+for &'gcx ty::Slice<T>
     where T: HashStable<StableHashingContext<'a, 'gcx, 'tcx>> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
@@ -30,7 +30,7 @@ for &'tcx ty::Slice<T>
 }
 
 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for ty::subst::Kind<'tcx> {
+for ty::subst::Kind<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -55,6 +55,11 @@ for ty::RegionKind {
                 db.depth.hash_stable(hcx, hasher);
                 i.hash_stable(hcx, hasher);
             }
+            ty::ReLateBound(db, ty::BrNamed(def_id, name)) => {
+                db.depth.hash_stable(hcx, hasher);
+                def_id.hash_stable(hcx, hasher);
+                name.hash_stable(hcx, hasher);
+            }
             ty::ReEarlyBound(ty::EarlyBoundRegion { def_id, index, name }) => {
                 def_id.hash_stable(hcx, hasher);
                 index.hash_stable(hcx, hasher);
@@ -76,7 +81,7 @@ for ty::RegionKind {
 }
 
 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for ty::adjustment::AutoBorrow<'tcx> {
+for ty::adjustment::AutoBorrow<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -94,7 +99,7 @@ for ty::adjustment::AutoBorrow<'tcx> {
 }
 
 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for ty::adjustment::Adjust<'tcx> {
+for ty::adjustment::Adjust<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -128,7 +133,7 @@ impl_stable_hash_for!(enum ty::BorrowKind {
 });
 
 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for ty::UpvarCapture<'tcx> {
+for ty::UpvarCapture<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -150,12 +155,13 @@ impl_stable_hash_for!(struct ty::FnSig<'tcx> {
 });
 
 impl<'a, 'gcx, 'tcx, T> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for ty::Binder<T>
-    where T: HashStable<StableHashingContext<'a, 'gcx, 'tcx>> + ty::fold::TypeFoldable<'tcx>
+    where T: HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
 {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
-        hcx.tcx().anonymize_late_bound_regions(self).0.hash_stable(hcx, hasher);
+        let ty::Binder(ref inner) = *self;
+        inner.hash_stable(hcx, hasher);
     }
 }
 
@@ -190,7 +196,7 @@ impl_stable_hash_for!(struct ty::ProjectionPredicate<'tcx> { projection_ty, ty }
 impl_stable_hash_for!(struct ty::ProjectionTy<'tcx> { substs, item_def_id });
 
 
-impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for ty::Predicate<'tcx> {
+impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for ty::Predicate<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -256,7 +262,7 @@ impl_stable_hash_for!(struct ty::FieldDef {
 });
 
 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for ::middle::const_val::ConstVal<'tcx> {
+for ::middle::const_val::ConstVal<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -483,7 +489,7 @@ impl_stable_hash_for!(enum ty::BoundRegion {
 });
 
 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for ty::TypeVariants<'tcx>
+for ty::TypeVariants<'gcx>
 {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
@@ -574,7 +580,7 @@ impl_stable_hash_for!(struct ty::TypeAndMut<'tcx> {
 });
 
 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for ty::ExistentialPredicate<'tcx>
+for ty::ExistentialPredicate<'gcx>
 {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
@@ -607,7 +613,7 @@ impl_stable_hash_for!(struct ty::ExistentialProjection<'tcx> {
 
 
 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
-for ty::TypeckTables<'tcx> {
+for ty::TypeckTables<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
@@ -687,7 +693,7 @@ impl_stable_hash_for!(struct ty::Instance<'tcx> {
     substs
 });
 
-impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for ty::InstanceDef<'tcx> {
+impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for ty::InstanceDef<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
diff --git a/src/librustc/macros.rs b/src/librustc/macros.rs
index f814f941b06..f3d66b49de5 100644
--- a/src/librustc/macros.rs
+++ b/src/librustc/macros.rs
@@ -73,10 +73,10 @@ macro_rules! __impl_stable_hash_field {
 #[macro_export]
 macro_rules! impl_stable_hash_for {
     (enum $enum_name:path { $( $variant:ident $( ( $($arg:ident),* ) )* ),* }) => {
-        impl<'a, 'gcx, 'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a, 'gcx, 'tcx>> for $enum_name {
+        impl<'a, 'tcx, 'lcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a, 'tcx, 'lcx>> for $enum_name {
             #[inline]
             fn hash_stable<W: ::rustc_data_structures::stable_hasher::StableHasherResult>(&self,
-                                                  __ctx: &mut $crate::ich::StableHashingContext<'a, 'gcx, 'tcx>,
+                                                  __ctx: &mut $crate::ich::StableHashingContext<'a, 'tcx, 'lcx>,
                                                   __hasher: &mut ::rustc_data_structures::stable_hasher::StableHasher<W>) {
                 use $enum_name::*;
                 ::std::mem::discriminant(self).hash_stable(__ctx, __hasher);
@@ -92,10 +92,10 @@ macro_rules! impl_stable_hash_for {
         }
     };
     (struct $struct_name:path { $($field:ident),* }) => {
-        impl<'a, 'gcx, 'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a, 'gcx, 'tcx>> for $struct_name {
+        impl<'a, 'tcx, 'lcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a, 'tcx, 'lcx>> for $struct_name {
             #[inline]
             fn hash_stable<W: ::rustc_data_structures::stable_hasher::StableHasherResult>(&self,
-                                                  __ctx: &mut $crate::ich::StableHashingContext<'a, 'gcx, 'tcx>,
+                                                  __ctx: &mut $crate::ich::StableHashingContext<'a, 'tcx, 'lcx>,
                                                   __hasher: &mut ::rustc_data_structures::stable_hasher::StableHasher<W>) {
                 let $struct_name {
                     $(ref $field),*
@@ -106,10 +106,10 @@ macro_rules! impl_stable_hash_for {
         }
     };
     (tuple_struct $struct_name:path { $($field:ident),* }) => {
-        impl<'a, 'gcx, 'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a, 'gcx, 'tcx>> for $struct_name {
+        impl<'a, 'tcx, 'lcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a, 'tcx, 'lcx>> for $struct_name {
             #[inline]
             fn hash_stable<W: ::rustc_data_structures::stable_hasher::StableHasherResult>(&self,
-                                                  __ctx: &mut $crate::ich::StableHashingContext<'a, 'gcx, 'tcx>,
+                                                  __ctx: &mut $crate::ich::StableHashingContext<'a, 'tcx, 'lcx>,
                                                   __hasher: &mut ::rustc_data_structures::stable_hasher::StableHasher<W>) {
                 let $struct_name (
                     $(ref $field),*
@@ -125,11 +125,11 @@ macro_rules! impl_stable_hash_for {
 macro_rules! impl_stable_hash_for_spanned {
     ($T:path) => (
 
-        impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for ::syntax::codemap::Spanned<$T>
+        impl<'a, 'tcx, 'lcx> HashStable<StableHashingContext<'a, 'tcx, 'lcx>> for ::syntax::codemap::Spanned<$T>
         {
             #[inline]
             fn hash_stable<W: StableHasherResult>(&self,
-                                                  hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
+                                                  hcx: &mut StableHashingContext<'a, 'tcx, 'lcx>,
                                                   hasher: &mut StableHasher<W>) {
                 self.node.hash_stable(hcx, hasher);
                 self.span.hash_stable(hcx, hasher);
diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs
index b44fb982f8a..28a73f4a4d3 100644
--- a/src/librustc/ty/mod.rs
+++ b/src/librustc/ty/mod.rs
@@ -498,7 +498,7 @@ impl<'tcx> TyS<'tcx> {
     }
 }
 
-impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for ty::TyS<'tcx> {
+impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for ty::TyS<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
                                           hasher: &mut StableHasher<W>) {
diff --git a/src/librustc/ty/util.rs b/src/librustc/ty/util.rs
index d1c73831545..9cd6aa21118 100644
--- a/src/librustc/ty/util.rs
+++ b/src/librustc/ty/util.rs
@@ -214,6 +214,11 @@ impl<'a, 'tcx> TyCtxt<'a, 'tcx, 'tcx> {
         let mut hasher = StableHasher::new();
         let mut hcx = StableHashingContext::new(self);
 
+        // We want the type_id be independent of the types free regions, so we
+        // erase them. The erase_regions() call will also anonymize bound
+        // regions, which is desirable too.
+        let ty = self.erase_regions(&ty);
+
         hcx.while_hashing_spans(false, |hcx| {
             hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
                 ty.hash_stable(hcx, &mut hasher);
diff --git a/src/test/run-pass/type-id-higher-rank.rs b/src/test/run-pass/type-id-higher-rank.rs
index 827b05c0801..2865b5d04e5 100644
--- a/src/test/run-pass/type-id-higher-rank.rs
+++ b/src/test/run-pass/type-id-higher-rank.rs
@@ -45,6 +45,11 @@ fn main() {
         assert!(g != h);
         assert!(g != i);
         assert!(h != i);
+
+        // Make sure lifetime anonymization handles nesting correctly
+        let j = TypeId::of::<fn(for<'a> fn(&'a isize) -> &'a usize)>();
+        let k = TypeId::of::<fn(for<'b> fn(&'b isize) -> &'b usize)>();
+        assert_eq!(j, k);
     }
     // Boxed unboxed closures
     {