Auto merge of #57714 - matthewjasper:wellformed-unreachable, r=pnkfelix

[NLL] Clean up handling of type annotations

* Renames (Canonical)?UserTypeAnnotation -> (Canonical)?UserType so that the name CanonicalUserTypeAnnotation is free.
* Keep the inferred type associated to user type annotations in the MIR, so that it can be compared against the annotated type, even when the annotated expression gets removed from the MIR. (#54943)
* Use the inferred type to allow infallible handling of user type projections (#57531)
* Uses revisions for the tests in #56993
* Check the types of `Unevaluated` constants with no annotations (#46702)
* Some drive-by cleanup

Closes #46702
Closes #54943
Closes #57531
Closes #57731
cc #56993 leaving this open to track the underlying issue: we are not running tests with full NLL enabled on CI at the moment

r? @nikomatsakis

Author: bors

src/librustc/ich/impls_ty.rs

@@ -1240,16 +1240,22 @@ impl_stable_hash_for!(
     }
 );
 
-impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for ty::UserTypeAnnotation<'gcx> {
+impl_stable_hash_for!(
+    struct ty::CanonicalUserTypeAnnotation<'tcx> {
+        user_ty, span, inferred_ty
+    }
+);
+
+impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for ty::UserType<'gcx> {
     fn hash_stable<W: StableHasherResult>(&self,
                                           hcx: &mut StableHashingContext<'a>,
                                           hasher: &mut StableHasher<W>) {
         mem::discriminant(self).hash_stable(hcx, hasher);
         match *self {
-            ty::UserTypeAnnotation::Ty(ref ty) => {
+            ty::UserType::Ty(ref ty) => {
                 ty.hash_stable(hcx, hasher);
             }
-            ty::UserTypeAnnotation::TypeOf(ref def_id, ref substs) => {
+            ty::UserType::TypeOf(ref def_id, ref substs) => {
                 def_id.hash_stable(hcx, hasher);
                 substs.hash_stable(hcx, hasher);
             }

src/librustc/mir/mod.rs

@@ -31,7 +31,7 @@ use ty::subst::{Subst, Substs};
 use ty::layout::VariantIdx;
 use ty::{
     self, AdtDef, CanonicalUserTypeAnnotations, ClosureSubsts, GeneratorSubsts, Region, Ty, TyCtxt,
-    UserTypeAnnotationIndex, UserTypeAnnotation,
+    UserTypeAnnotationIndex,
 };
 use util::ppaux;