Reviews

Author: BoxyUwU

compiler/rustc_type_ir/src/fast_reject.rs

@@ -241,9 +241,6 @@ impl<I: Interner, const INSTANTIATE_LHS_WITH_INFER: bool, const INSTANTIATE_RHS_
     }
 
     pub fn types_may_unify_with_depth(self, lhs: I::Ty, rhs: I::Ty, depth_limit: usize) -> bool {
-        if lhs == rhs {
-            return true;
-        }
         self.types_may_unify_inner(lhs, rhs, depth_limit)
     }
 

tests/ui/associated-inherent-types/bound_vars_in_args.rs

@@ -1,8 +1,8 @@
 #![feature(non_lifetime_binders, inherent_associated_types)]
 #![expect(incomplete_features)]
 
-// Test that we can resolve to the right IAT when the self type
-// contains a bound type.
+// Test whether we can resolve to the right IAT when the self type
+// contains a bound type. This should ideally use the second impl.
 
 struct Foo<T: ?Sized>(T);
 

tests/ui/associated-inherent-types/candidate-with-alias-2.rs

@@ -1,6 +1,9 @@
 #![feature(inherent_associated_types)]
 #![expect(incomplete_features)]
 
+// A behaviour test showcasing that we do not normalize associated types in
+// the impl self ty when assembling IAT candidates
+
 trait Identity {
     type Assoc;
 }

tests/ui/associated-inherent-types/candidate-with-alias-2.stderr

@@ -1,16 +1,16 @@
 error[E0034]: multiple applicable items in scope
-  --> $DIR/candidate-with-alias-2.rs:20:23
+  --> $DIR/candidate-with-alias-2.rs:23:23
    |
 LL |     field: <Foo<u8>>::Inherent,
    |                       ^^^^^^^^ multiple `Inherent` found
    |
 note: candidate #1 is defined in an impl for the type `Foo<<u8 as Identity>::Assoc>`
-  --> $DIR/candidate-with-alias-2.rs:13:5
+  --> $DIR/candidate-with-alias-2.rs:16:5
    |
 LL |     type Inherent = u8;
    |     ^^^^^^^^^^^^^
 note: candidate #2 is defined in an impl for the type `Foo<<u16 as Identity>::Assoc>`
-  --> $DIR/candidate-with-alias-2.rs:16:5
+  --> $DIR/candidate-with-alias-2.rs:19:5
    |
 LL |     type Inherent = u32;
    |     ^^^^^^^^^^^^^

tests/ui/associated-inherent-types/candidate-with-alias.rs

@@ -3,6 +3,9 @@
 #![feature(inherent_associated_types)]
 #![expect(incomplete_features)]
 
+// A behaviour test showcasing that IAT resolution can pick the right
+// candidate even if it has an alias, if it's the only candidate.
+
 trait Identity {
     type Assoc;
 }

tests/ui/associated-inherent-types/multiple-candidates-in-adt-field-2.rs

@@ -1,8 +1,8 @@
 #![feature(inherent_associated_types)]
 #![expect(incomplete_features)]
 
-// Test that when we have an unnormalized projection we don't normalize it
-// to determine which IAT to resolve to.
+// Test that when we have an unnormalized projection in the IAT self ty
+// we don't normalize it to determine which IAT to resolve to.
 
 struct Foo<T>(T);
 impl Foo<u8> {