//@ compile-flags: -Zpolymorphize=on -Zinline-mir=yes -Zmir-opt-level=0

#![feature(fn_traits, unboxed_closures)]
struct Foo<T>(T);

impl<T: Copy> Fn<()> for Foo<T> {
    extern "C" fn call(&self, _: ()) -> T {
        //~^ ERROR method `call` has an incompatible type for trait
        match *self {
            Foo(t) => t,
        }
    }
}

impl<T: Copy> FnMut<()> for Foo<T> {
    extern "rust-call" fn call_mut(&mut self, _: ()) -> T {
        self.call(())
    }
}

impl<T: Copy> FnOnce<()> for Foo<T> {
    type Output = T;

    extern "rust-call" fn call_once(self, _: ()) -> T {
        self.call(())
    }
}

fn main() {
    let t: u8 = 1;
    println!("{}", Foo(t)());
}