[rustc.git] / src / test / ui / never_type / fallback-closure-wrap.rs

// This is a minified example from Crater breakage observed when attempting to
// stabilize never type, nstoddard/webgl-gui @ 22f0169f.
//
// This particular test case currently fails as the inference to `()` rather
// than `!` happens as a result of an `as` cast, which is not currently tracked.
// Crater did not find many cases of this occurring, but it is included for
// awareness.
//
// revisions: nofallback fallback
//[nofallback] check-pass
//[fallback] check-fail

#![cfg_attr(fallback, feature(never_type_fallback))]

use std::marker::PhantomData;

fn main() {
    let error = Closure::wrap(Box::new(move || {
        //[fallback]~^ to be a closure that returns `()`, but it returns `!`
        panic!("Can't connect to server.");
    }) as Box<dyn FnMut()>);
}

struct Closure<T: ?Sized>(PhantomData<T>);

impl<T: ?Sized> Closure<T> {
    fn wrap(data: Box<T>) -> Closure<T> {
        todo!()
    }
}
Commit	Line	Data
c295e0f8 XL	1	// This is a minified example from Crater breakage observed when attempting to
	2	// stabilize never type, nstoddard/webgl-gui @ 22f0169f.
	3	//
	4	// This particular test case currently fails as the inference to `()` rather
	5	// than `!` happens as a result of an `as` cast, which is not currently tracked.
f2b60f7d	6	// Crater did not find many cases of this occurring, but it is included for
c295e0f8 XL	7	// awareness.
	8	//
	9	// revisions: nofallback fallback
	10	//[nofallback] check-pass
	11	//[fallback] check-fail
	12
	13	#![cfg_attr(fallback, feature(never_type_fallback))]
	14
	15	use std::marker::PhantomData;
	16
	17	fn main() {
	18	let error = Closure::wrap(Box::new(move \|\| {
f2b60f7d	19	//[fallback]~^ to be a closure that returns `()`, but it returns `!`
c295e0f8 XL	20	panic!("Can't connect to server.");
	21	}) as Box<dyn FnMut()>);
	22	}
	23
	24	struct Closure<T: ?Sized>(PhantomData<T>);
	25
	26	impl<T: ?Sized> Closure<T> {
	27	fn wrap(data: Box<T>) -> Closure<T> {
	28	todo!()
	29	}
	30	}