diff options
Diffstat (limited to 'tests/ui/type-alias-impl-trait/underconstrained_lifetime.rs')
-rw-r--r-- | tests/ui/type-alias-impl-trait/underconstrained_lifetime.rs | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/tests/ui/type-alias-impl-trait/underconstrained_lifetime.rs b/tests/ui/type-alias-impl-trait/underconstrained_lifetime.rs new file mode 100644 index 000000000..c5b2e8a1c --- /dev/null +++ b/tests/ui/type-alias-impl-trait/underconstrained_lifetime.rs @@ -0,0 +1,34 @@ +#![feature(type_alias_impl_trait)] + +use std::marker::PhantomData; + +trait ProofForConversion<'a, 'b> { + fn convert<T: ?Sized>(_: PhantomData<Self>, r: &'a T) -> &'b T; +} + +impl<'a, 'b> ProofForConversion<'a, 'b> for &'b &'a () { + fn convert<T: ?Sized>(_: PhantomData<Self>, r: &'a T) -> &'b T { + r + } +} + +type Converter<'a, 'b> = impl ProofForConversion<'a, 'b>; +//~^ ERROR reference has a longer lifetime than the data it references + +// Even _defining_use with an explicit `'a: 'b` compiles fine, too. +fn _defining_use<'a, 'b>(x: &'b &'a ()) -> Converter<'a, 'b> { + x +} + +fn extend_lifetime<'a, 'b, T: ?Sized>(x: &'a T) -> &'b T { + Converter::<'a, 'b>::convert(PhantomData, x) +} + +fn main() { + let d; + { + let x = "Hello World".to_string(); + d = extend_lifetime(&x); + } + println!("{}", d); +} |