Rollup merge of #55199 - oli-obk:instance_printing, r=davidtwco

Impl items have generics

src/test/ui/issues/issue-21554.stderr

@@ -1,4 +1,4 @@
-error[E0606]: casting `fn(i32) -> Inches {Inches::{{constructor}}}` as `f32` is invalid
+error[E0606]: casting `fn(i32) -> Inches {Inches}` as `f32` is invalid
   --> $DIR/issue-21554.rs:14:5
    |
 LL |     Inches as f32;

src/test/ui/issues/issue-35241.stderr

@@ -9,7 +9,7 @@ LL | fn test() -> Foo { Foo } //~ ERROR mismatched types
    |              expected `Foo` because of return type
    |
    = note: expected type `Foo`
-              found type `fn(u32) -> Foo {Foo::{{constructor}}}`
+              found type `fn(u32) -> Foo {Foo}`
 
 error: aborting due to previous error