1 error: concrete type differs from previous defining opaque type use
2 --> $DIR/issue-52843-closure-constrain.rs:10:16
4 LL | let null = || -> Opaque { 0 };
5 | ^^^^^^^^^^^^^^^^^^ expected `String`, got `i32`
7 note: previous use here
8 --> $DIR/issue-52843-closure-constrain.rs:9:5
10 LL | fn _unused() -> Opaque { String::new() }
11 | ^^^^^^^^^^^^^^^^^^^^^^
13 error: aborting due to previous error