1 #![feature(unboxed_closures, tuple_trait)]
3 // Tests that we can't assign to or mutably borrow upvars from `Fn`
4 // closures (issue #17780)
6 fn set(x: &mut usize) {
10 fn to_fn<A: std::marker::Tuple, F: Fn<A>>(f: F) -> F {
13 fn to_fn_mut<A: std::marker::Tuple, F: FnMut<A>>(f: F) -> F {
21 let _f = to_fn(|| x = 42); //~ ERROR cannot assign
24 let _g = to_fn(|| set(&mut y)); //~ ERROR cannot borrow
27 let _h = to_fn_mut(|| {
29 to_fn(|| z = 42); //~ ERROR cannot assign
36 let _f = to_fn(move || x = 42); //~ ERROR cannot assign
39 let _g = to_fn(move || set(&mut y)); //~ ERROR cannot borrow
42 let _h = to_fn_mut(move || {
44 to_fn(move || z = 42);
45 //~^ ERROR cannot assign
50 fn foo() -> Box<dyn Fn() -> usize> {
53 x += 1; //~ ERROR cannot assign