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//@ check-pass
struct Foo<'a>(&'a ())
where
(): Trait<'a>;
trait Trait<'a> {
fn id<T>(value: &'a T) -> &'static T;
}
impl Trait<'static> for () {
fn id<T>(value: &'static T) -> &'static T {
value
}
}
fn could_use_implied_bounds<'a, T>(_: Foo<'a>, x: &'a T) -> &'static T
where
(): Trait<'a>, // This could be an implied bound
{
<()>::id(x)
}
fn main() {
let bar: for<'a, 'b> fn(Foo<'a>, &'b ()) = |_, _| {};
// If `could_use_implied_bounds` were to use implied bounds,
// keeping 'a late-bound, then we could assign that function
// to this variable.
let bar: for<'a> fn(Foo<'a>, &'a ()) = bar;
// In this case, the subtyping relation here would be unsound,
// allowing us to transmute lifetimes. This currently compiles
// because we incorrectly deal with implied bounds inside of binders.
let _bar: for<'a, 'b> fn(Foo<'a>, &'b ()) = bar;
}
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