Tweak wording

Author: estebank

compiler/rustc_hir_analysis/src/astconv/errors.rs

@@ -191,10 +191,11 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 .collect::<Vec<_>>()[..]
             {
                 let trait_name = self.tcx().def_path_str(*best_trait);
+                let an = if suggested_name != assoc_name.name { "a similarly named" } else { "an" };
                 err.span_label(
                     assoc_name.span,
                     format!(
-                        "there is a similarly named associated type `{suggested_name}` in the \
+                        "there is {an} associated type `{suggested_name}` in the \
                          trait `{trait_name}`",
                     ),
                 );

tests/rustdoc-ui/issues/issue-96287.stderr

@@ -2,7 +2,7 @@ error[E0220]: associated type `Assoc` not found for `V`
   --> $DIR/issue-96287.rs:7:33
    |
 LL | pub type Foo<V> = impl Trait<V::Assoc>;
-   |                                 ^^^^^ there is a similarly named associated type `Assoc` in the trait `TraitWithAssoc`
+   |                                 ^^^^^ there is an associated type `Assoc` in the trait `TraitWithAssoc`
    |
 help: consider restricting type parameter `V`
    |

tests/ui/traits/issue-59029-1.stderr

@@ -2,13 +2,13 @@ error[E0220]: associated type `Res` not found for `Self`
   --> $DIR/issue-59029-1.rs:5:52
    |
 LL | trait MkSvc<Target, Req> = Svc<Target> where Self::Res: Svc<Req>;
-   |                                                    ^^^ there is a similarly named associated type `Res` in the trait `Svc`
+   |                                                    ^^^ there is an associated type `Res` in the trait `Svc`
 
 error[E0220]: associated type `Res` not found for `Self`
   --> $DIR/issue-59029-1.rs:5:52
    |
 LL | trait MkSvc<Target, Req> = Svc<Target> where Self::Res: Svc<Req>;
-   |                                                    ^^^ there is a similarly named associated type `Res` in the trait `Svc`
+   |                                                    ^^^ there is an associated type `Res` in the trait `Svc`
    |
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 

tests/ui/type-alias-impl-trait/not_well_formed.stderr

@@ -2,7 +2,7 @@ error[E0220]: associated type `Assoc` not found for `V`
   --> $DIR/not_well_formed.rs:11:29
    |
 LL | type Foo<V> = impl Trait<V::Assoc>;
-   |                             ^^^^^ there is a similarly named associated type `Assoc` in the trait `TraitWithAssoc`
+   |                             ^^^^^ there is an associated type `Assoc` in the trait `TraitWithAssoc`
    |
 help: consider restricting type parameter `V`
    |