rust/tests/ui/unboxed-closures/unboxed-closures-fnmut-as-fnonce.rs
2024-02-16 20:02:50 +00:00

34 lines
692 B
Rust

//@ run-pass
// Checks that the Fn trait hierarchy rules permit
// FnMut or FnOnce to be used where FnMut is implemented.
#![feature(unboxed_closures, fn_traits)]
struct S;
impl FnMut<(i32,)> for S {
extern "rust-call" fn call_mut(&mut self, (x,): (i32,)) -> i32 {
x * x
}
}
impl FnOnce<(i32,)> for S {
type Output = i32;
extern "rust-call" fn call_once(mut self, args: (i32,)) -> i32 { self.call_mut(args) }
}
fn call_it_mut<F:FnMut(i32)->i32>(f: &mut F, x: i32) -> i32 {
f(x)
}
fn call_it_once<F:FnOnce(i32)->i32>(f: F, x: i32) -> i32 {
f(x)
}
fn main() {
let y = call_it_mut(&mut S, 22);
let z = call_it_once(S, 22);
assert_eq!(y, z);
}