1 error: concrete type differs from previous defining existential type use
2 --> $DIR/issue-52843.rs:7:5
4 LL | fn _unused() -> Existential { String::new() }
5 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, got `std::string::String`
7 note: previous use here
8 --> $DIR/issue-52843.rs:5:1
11 LL | | existential type Existential: Debug;
12 LL | | fn _unused() -> Existential { String::new() }
14 LL | | let null = || -> Existential { 0 };
15 LL | | println!("{:?}", null());
19 error: aborting due to previous error