1 error[E0308]: mismatched types
2 --> $DIR/issue-91450-inner-ty-error.rs:4:13
4 LL | fn foo() -> Option<_> {}
5 | --- ^^^^^^^^^ expected enum `Option`, found `()`
7 | implicitly returns `()` as its body has no tail or `return` expression
9 = note: expected enum `Option<_>`
12 error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
13 --> $DIR/issue-91450-inner-ty-error.rs:4:20
15 LL | fn foo() -> Option<_> {}
16 | ^ not allowed in type signatures
18 error: aborting due to 2 previous errors
20 Some errors have detailed explanations: E0121, E0308.
21 For more information about an error, try `rustc --explain E0121`.