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 | LL - fn foo() -> _ { 5 } LL + fn foo() -> i32 { 5 } | 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 this with a fully-specified type | LL - static BAR: _ = "test"; LL + static BAR: &str = "test"; | error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0121`.