error[E0308]: mismatched types --> $DIR/issue-17033.rs:2:10 | LL | (*p)(()) | ---- ^^ expected `&mut ()`, found `()` | | | arguments to this function are incorrect | help: consider mutably borrowing here | LL | (*p)(&mut ()) | ++++ error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0308`.