3 fn foo<F: Fn()>(mut f: F) {
4 Fn::call(&f, ()); //~ ERROR use of unstable library feature 'fn_traits'
5 FnMut::call_mut(&mut f, ()); //~ ERROR use of unstable library feature 'fn_traits'
6 FnOnce::call_once(f, ()); //~ ERROR use of unstable library feature 'fn_traits'