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// Regression test for #84533 involving higher-ranked regions
// in the return type.
use std::marker::PhantomData;
fn foo<'c, 'b, 'a>(_: &'c ()) -> (&'c (), PhantomData<&'b &'a ()>) {
(&(), PhantomData)
}
fn extend_lifetime<'a, 'b, T: ?Sized>(x: &'a T) -> &'b T {
let f = foo;
f.baz(x)
//~^ ERROR lifetime may not live long enough
}
trait Foo<'a, 'b, T: ?Sized> {
fn baz(self, s: &'a T) -> &'b T;
}
impl<'a, 'b, R, F, T: ?Sized> Foo<'a, 'b, T> for F
where
F: for<'c> Fn(&'c ()) -> (&'c (), R),
R: ProofForConversion<'a, 'b, T>,
{
fn baz(self, s: &'a T) -> &'b T {
self(&()).1.convert(s)
}
}
trait ProofForConversion<'a, 'b, T: ?Sized> {
fn convert(self, s: &'a T) -> &'b T;
}
impl<'a, 'b, T: ?Sized> ProofForConversion<'a, 'b, T> for PhantomData<&'b &'a ()> {
fn convert(self, s: &'a T) -> &'b T {
s
}
}
fn main() {
let d;
{
let x = "Hello World".to_string();
d = extend_lifetime(&x);
}
println!("{}", d);
}
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