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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:19:03 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:19:03 +0000 |
commit | 64d98f8ee037282c35007b64c2649055c56af1db (patch) | |
tree | 5492bcf97fce41ee1c0b1cc2add283f3e66cdab0 /tests/ui/type-alias-impl-trait/implied_bounds.rs | |
parent | Adding debian version 1.67.1+dfsg1-1. (diff) | |
download | rustc-64d98f8ee037282c35007b64c2649055c56af1db.tar.xz rustc-64d98f8ee037282c35007b64c2649055c56af1db.zip |
Merging upstream version 1.68.2+dfsg1.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tests/ui/type-alias-impl-trait/implied_bounds.rs')
-rw-r--r-- | tests/ui/type-alias-impl-trait/implied_bounds.rs | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/tests/ui/type-alias-impl-trait/implied_bounds.rs b/tests/ui/type-alias-impl-trait/implied_bounds.rs new file mode 100644 index 000000000..53cbf8d22 --- /dev/null +++ b/tests/ui/type-alias-impl-trait/implied_bounds.rs @@ -0,0 +1,51 @@ +#![feature(type_alias_impl_trait)] + +type WithLifetime<'a> = impl Equals<SelfType = ()>; +fn _defining_use<'a>() -> WithLifetime<'a> {} + +trait Convert<'a> { + type Witness; + fn convert<'b, T: ?Sized>(_proof: &'b Self::Witness, x: &'a T) -> &'b T; +} + +impl<'a> Convert<'a> for () { + type Witness = WithLifetime<'a>; + + fn convert<'b, T: ?Sized>(_proof: &'b WithLifetime<'a>, x: &'a T) -> &'b T { + // compiler used to think it gets to assume 'a: 'b here because + // of the `&'b WithLifetime<'a>` argument + x + //~^ ERROR lifetime may not live long enough + } +} + +fn extend_lifetime<'a, 'b, T: ?Sized>(x: &'a T) -> &'b T { + WithLifetime::<'a>::convert_helper::<(), T>(&(), x) +} + +trait Equals { + type SelfType; + fn convert_helper<'a, 'b, W: Convert<'a, Witness = Self>, T: ?Sized>( + proof: &'b Self::SelfType, + x: &'a T, + ) -> &'b T; +} + +impl<S> Equals for S { + type SelfType = Self; + fn convert_helper<'a, 'b, W: Convert<'a, Witness = Self>, T: ?Sized>( + proof: &'b Self, + x: &'a T, + ) -> &'b T { + W::convert(proof, x) + } +} + +fn main() { + let r; + { + let x = String::from("Hello World?"); + r = extend_lifetime(&x); + } + println!("{}", r); +} |