Incomplete diagnostic notes when closure returns conflicting instantiations of generic type

[eggyal]

Given the following code (playground):

struct Foo<T>(T);

fn main() {
    || {
        if false {
            return Foo(0);
        }

        Foo(())
    };
}

The current output is:

error[E0308]: mismatched types
 --> src/main.rs:9:13
  |
9 |         Foo(())
  |             ^^ expected integer, found `()`

Ideally the output should look like:

error[E0308]: mismatched types
 --> src/main.rs:9:13
  |
9 |         Foo(())
  |             ^^ expected integer, found `()`
  |
note: return type inferred to be `Foo<{integer}>` here
 --> src/main.rs:6:20
  |
6 |             return Foo(0);
  |                    ^^^^^^

Since #78235, notes have been provided when the returned types are entirely different—but they do not appear when they are the same base type with different generic type parameters. cc @Aaron1011

@rustbot label: A-closures A-diagnostics A-inference C-enhancement D-papercut

[khrj]

Reference

[ABouttefeux]

@rustbot claim