error[E0308]: mismatched types
  --> $DIR/itiat-allow-nested-closures.rs:21:22
   |
LL |     type Assoc = impl Sized;
   |                  ---------- the found opaque type
...
LL |         let _: i32 = closure();
   |                ---   ^^^^^^^^^ expected `i32`, found opaque type
   |                |
   |                expected due to this
   |
   = note:     expected type `i32`
           found opaque type `<() as Foo>::Assoc`

error[E0308]: mismatched types
  --> $DIR/itiat-allow-nested-closures.rs:22:9
   |
LL |     fn bar() -> Self::Assoc {
   |                 ----------- expected `()` because of return type
...
LL |         1i32
   |         ^^^^ expected `()`, found `i32`

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0308`.