diff options
Diffstat (limited to 'tests/ui/impl-trait/multiple-lifetimes/ordinary-bounds-pick-original.rs')
-rw-r--r-- | tests/ui/impl-trait/multiple-lifetimes/ordinary-bounds-pick-original.rs | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/tests/ui/impl-trait/multiple-lifetimes/ordinary-bounds-pick-original.rs b/tests/ui/impl-trait/multiple-lifetimes/ordinary-bounds-pick-original.rs new file mode 100644 index 000000000..0f21dd5ff --- /dev/null +++ b/tests/ui/impl-trait/multiple-lifetimes/ordinary-bounds-pick-original.rs @@ -0,0 +1,25 @@ +// edition:2018 +// build-pass (FIXME(62277): could be check-pass?) + +trait Trait<'a, 'b> {} +impl<T> Trait<'_, '_> for T {} + +// Here we wind up selecting `'a` and `'b` in the hidden type because +// those are the types that appear in the original values. + +fn upper_bounds<'a, 'b>(a: &'a u8, b: &'b u8) -> impl Trait<'a, 'b> { + // In this simple case, you have a hidden type `(&'0 u8, &'1 u8)` and constraints like + // + // ``` + // 'a: '0 + // 'b: '1 + // '0 in ['a, 'b] + // '1 in ['a, 'b] + // ``` + // + // We use the fact that `'a: 0'` must hold (combined with the in + // constraint) to determine that `'0 = 'a` must be the answer. + (a, b) +} + +fn main() {} |