error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types --> $DIR/E0121.rs:1:13 | LL | fn foo() -> _ { 5 } | ^ | | | not allowed in type signatures | help: replace with the correct return type: `i32` error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables --> $DIR/E0121.rs:3:13 | LL | static BAR: _ = "test"; | ^ | | | not allowed in type signatures | help: replace with the correct type: `&str` error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0121`.