1 #![feature(type_alias_impl_trait)]
3 use std::marker::PhantomData;
5 trait ProofForConversion<'a, 'b> {
6 fn convert<T: ?Sized>(_: PhantomData<Self>, r: &'a T) -> &'b T;
9 impl<'a, 'b> ProofForConversion<'a, 'b> for &'b &'a () {
10 fn convert<T: ?Sized>(_: PhantomData<Self>, r: &'a T) -> &'b T {
15 type Converter<'a, 'b> = impl ProofForConversion<'a, 'b>;
16 //~^ ERROR reference has a longer lifetime than the data it references
18 // Even _defining_use with an explicit `'a: 'b` compiles fine, too.
19 fn _defining_use<'a, 'b>(x: &'b &'a ()) -> Converter<'a, 'b> {
23 fn extend_lifetime<'a, 'b, T: ?Sized>(x: &'a T) -> &'b T {
24 Converter::<'a, 'b>::convert(PhantomData, x)
30 let x = "Hello World".to_string();
31 d = extend_lifetime(&x);