Auto merge of #49091 - nikomatsakis:issue-49043-ty-infer-hash, r=michaelwoerister

extend stable hasher to support `CanonicalTy`

Fixes #49043

r? @michaelwoerister

src/librustc/ich/impls_ty.rs

@@ -902,13 +902,59 @@ for ty::TypeVariants<'gcx>
             TyForeign(def_id) => {
                 def_id.hash_stable(hcx, hasher);
             }
-            TyInfer(..) => {
-                bug!("ty::TypeVariants::hash_stable() - Unexpected variant {:?}.", *self)
+            TyInfer(infer_ty) => {
+                infer_ty.hash_stable(hcx, hasher);
             }
         }
     }
 }
 
+impl_stable_hash_for!(enum ty::InferTy {
+    TyVar(a),
+    IntVar(a),
+    FloatVar(a),
+    FreshTy(a),
+    FreshIntTy(a),
+    FreshFloatTy(a),
+    CanonicalTy(a),
+});
+
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
+for ty::TyVid
+{
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          _hcx: &mut StableHashingContext<'a>,
+                                          _hasher: &mut StableHasher<W>) {
+        // TyVid values are confined to an inference context and hence
+        // should not be hashed.
+        bug!("ty::TypeVariants::hash_stable() - can't hash a TyVid {:?}.", *self)
+    }
+}
+
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
+for ty::IntVid
+{
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          _hcx: &mut StableHashingContext<'a>,
+                                          _hasher: &mut StableHasher<W>) {
+        // IntVid values are confined to an inference context and hence
+        // should not be hashed.
+        bug!("ty::TypeVariants::hash_stable() - can't hash an IntVid {:?}.", *self)
+    }
+}
+
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>>
+for ty::FloatVid
+{
+    fn hash_stable<W: StableHasherResult>(&self,
+                                          _hcx: &mut StableHashingContext<'a>,
+                                          _hasher: &mut StableHasher<W>) {
+        // FloatVid values are confined to an inference context and hence
+        // should not be hashed.
+        bug!("ty::TypeVariants::hash_stable() - can't hash a FloatVid {:?}.", *self)
+    }
+}
+
 impl_stable_hash_for!(struct ty::ParamTy {
     idx,
     name

src/librustc/macros.rs

@@ -72,7 +72,7 @@ macro_rules! __impl_stable_hash_field {
 
 #[macro_export]
 macro_rules! impl_stable_hash_for {
-    (enum $enum_name:path { $( $variant:ident $( ( $($arg:ident),* ) )* ),* }) => {
+    (enum $enum_name:path { $( $variant:ident $( ( $($arg:ident),* ) )* ),* $(,)* }) => {
         impl<'a, 'tcx> ::rustc_data_structures::stable_hasher::HashStable<$crate::ich::StableHashingContext<'a>> for $enum_name {
             #[inline]
             fn hash_stable<W: ::rustc_data_structures::stable_hasher::StableHasherResult>(&self,

src/librustc/traits/query/dropck_outlives.rs

@@ -51,6 +51,7 @@ impl<'cx, 'gcx, 'tcx> At<'cx, 'gcx, 'tcx> {
         let gcx = tcx.global_tcx();
         let (c_ty, orig_values) = self.infcx.canonicalize_query(&self.param_env.and(ty));
         let span = self.cause.span;
+        debug!("c_ty = {:?}", c_ty);
         match &gcx.dropck_outlives(c_ty) {
             Ok(result) if result.is_proven() => {
                 match self.infcx.instantiate_query_result(

src/test/incremental/issue-49043.rs

@@ -0,0 +1,22 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Regression test for hashing involving canonical variables.  In this
+// test -- which has an intensional error -- the type of the value
+// being dropped winds up including a type variable. Canonicalization
+// would then produce a `?0` which -- in turn -- triggered an ICE in
+// hashing.
+
+// revisions:cfail1
+
+fn main() {
+    println!("Hello, world! {}",*thread_rng().choose(&[0, 1, 2, 3]).unwrap());
+    //[cfail1]~^ ERROR cannot find function `thread_rng`
+}