rust/src/test/compile-fail/pure-subtyping.rs

// Test rules governing higher-order pure fns.

fn take<T>(_v: T) {}

fn assign_to_pure(x: pure fn(), y: fn(), z: unsafe fn()) {
    take::<pure fn()>(x);
    take::<pure fn()>(y); //~ ERROR expected pure fn but found impure fn
    take::<pure fn()>(z); //~ ERROR expected pure fn but found unsafe fn
}

fn assign_to_impure(x: pure fn(), y: fn(), z: unsafe fn()) {
    take::<fn()>(x);
    take::<fn()>(y);
    take::<fn()>(z); //~ ERROR expected impure fn but found unsafe fn
}

fn assign_to_unsafe(x: pure fn(), y: fn(), z: unsafe fn()) {
    take::<unsafe fn()>(x);
    take::<unsafe fn()>(y);
    take::<unsafe fn()>(z);
}

fn assign_to_pure2(x: pure fn@(), y: fn@(), z: unsafe fn@()) {
    take::<pure fn()>(x);
    take::<pure fn()>(y); //~ ERROR expected pure fn but found impure fn
    take::<pure fn()>(z); //~ ERROR expected pure fn but found unsafe fn

    take::<pure fn~()>(x); //~ ERROR expected ~ closure, found @ closure
    take::<pure fn~()>(y); //~ ERROR expected ~ closure, found @ closure
    take::<pure fn~()>(z); //~ ERROR expected ~ closure, found @ closure

    take::<unsafe fn~()>(x); //~ ERROR expected ~ closure, found @ closure
    take::<unsafe fn~()>(y); //~ ERROR expected ~ closure, found @ closure
    take::<unsafe fn~()>(z); //~ ERROR expected ~ closure, found @ closure
}

fn main() {
}