rust/tests/ui/unboxed-closures/unboxed-closures-fnmut-as-fn.rs
2023-01-11 09:32:08 +00:00

30 lines
613 B
Rust

// Checks that the Fn trait hierarchy rules do not permit
// Fn to be used where FnMut is implemented.
#![feature(fn_traits, unboxed_closures)]
use std::ops::{Fn,FnMut,FnOnce};
struct S;
impl FnMut<(isize,)> for S {
extern "rust-call" fn call_mut(&mut self, (x,): (isize,)) -> isize {
x * x
}
}
impl FnOnce<(isize,)> for S {
type Output = isize;
extern "rust-call" fn call_once(mut self, args: (isize,)) -> isize { self.call_mut(args) }
}
fn call_it<F:Fn(isize)->isize>(f: &F, x: isize) -> isize {
f.call((x,))
}
fn main() {
let x = call_it(&S, 22);
//~^ ERROR E0277
}