error[E0308]: mismatched types --> $DIR/universe-violation.rs:13:31 | LL | let b: fn(&u32) -> &u32 = a; | ^ one type is more general than the other | = note: expected fn pointer `for<'a> fn(&'a u32) -> &'a u32` found fn pointer `fn(&u32) -> &u32` error: aborting due to previous error For more information about this error, try `rustc --explain E0308`.