#![feature(fn_traits, unboxed_closures)]

use std::ops::{Fn, FnMut, FnOnce};

struct SFn {
    x: isize,
    y: isize,
}

impl Fn<(isize,)> for SFn {
    extern "rust-call" fn call(&self, (z,): (isize,)) -> isize {
        self.x * self.y * z
    }
}

impl FnMut<(isize,)> for SFn {
    extern "rust-call" fn call_mut(&mut self, args: (isize,)) -> isize { self.call(args) }
}

impl FnOnce<(isize,)> for SFn {
    type Output = isize;
    extern "rust-call" fn call_once(self, args: (isize,)) -> isize { self.call(args) }
}

struct SFnMut {
    x: isize,
    y: isize,
}

impl FnMut<(isize,)> for SFnMut {
    extern "rust-call" fn call_mut(&mut self, (z,): (isize,)) -> isize {
        self.x * self.y * z
    }
}

impl FnOnce<(isize,)> for SFnMut {
    type Output = isize;
    extern "rust-call" fn call_once(mut self, args: (isize,)) -> isize { self.call_mut(args) }
}

struct SFnOnce {
    x: String,
}

impl FnOnce<(String,)> for SFnOnce {
    type Output = usize;

    extern "rust-call" fn call_once(self, (z,): (String,)) -> usize {
        self.x.len() + z.len()
    }
}

fn f() {
    let mut s = SFn {
        x: 1,
        y: 2,
    };
    let sp = &mut s;
    s(3);   //~ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable
    use_mut(sp);
}
fn g() {
    let s = SFnMut {
        x: 1,
        y: 2,
    };
    s(3);   //~ ERROR cannot borrow `s` as mutable, as it is not declared as mutable
}

fn h() {
    let s = SFnOnce {
        x: "hello".to_string(),
    };
    s(" world".to_string());
    s(" world".to_string());    //~ ERROR use of moved value: `s`
}

fn main() {}

fn use_mut<T>(_: &mut T) { }