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#![feature(generic_const_exprs)]
#![allow(incomplete_features)]
use std::marker::PhantomData;
trait SadBee {
const ASSOC: usize;
}
// fn(&'static ())` is a supertype of `for<'a> fn(&'a ())` while
// we allow two different impls for these types, leading
// to different const eval results.
impl SadBee for for<'a> fn(&'a ()) {
const ASSOC: usize = 0;
}
impl SadBee for fn(&'static ()) {
//~^ WARNING conflicting implementations of trait
//~| WARNING this was previously accepted
const ASSOC: usize = 100;
}
struct Foo<T: SadBee>([u8; <T as SadBee>::ASSOC], PhantomData<T>)
where
[(); <T as SadBee>::ASSOC]: ;
fn covariant(
v: &'static Foo<for<'a> fn(&'a ())>
) -> &'static Foo<fn(&'static ())> {
v
//~^ ERROR mismatched types
}
fn main() {
let y = covariant(&Foo([], PhantomData));
println!("{:?}", y.0);
}
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