From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:02:58 +0200 Subject: Adding upstream version 1.64.0+dfsg1. Signed-off-by: Daniel Baumann --- .../ordinary-bounds-pick-other.rs | 42 ++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-pick-other.rs (limited to 'src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-pick-other.rs') diff --git a/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-pick-other.rs b/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-pick-other.rs new file mode 100644 index 000000000..13ad1f721 --- /dev/null +++ b/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-pick-other.rs @@ -0,0 +1,42 @@ +// edition:2018 +// build-pass (FIXME(62277): could be check-pass?) + +trait Trait<'a, 'b> {} +impl Trait<'_, '_> for T {} + +// `Ordinary<'a> <: Ordinary<'b>` if `'a: 'b`, as with most types. +// +// I am purposefully avoiding the terms co- and contra-variant because +// their application to regions depends on how you interpreted Rust +// regions. -nikomatsakis +struct Ordinary<'a>(&'a u8); + +// Here we wind up selecting `'e` in the hidden type because +// we need something outlived by both `'a` and `'b` and only `'e` applies. + +fn upper_bounds<'a, 'b, 'c, 'd, 'e>(a: Ordinary<'a>, b: Ordinary<'b>) -> impl Trait<'d, 'e> +where + 'a: 'e, + 'b: 'e, + 'a: 'd, +{ + // We return a value: + // + // ``` + // 'a: '0 + // 'b: '1 + // '0 in ['d, 'e] + // ``` + // + // but we don't have it. + // + // We are forced to pick that '0 = 'e, because only 'e is outlived by *both* 'a and 'b. + let p = if condition() { a } else { b }; + p +} + +fn condition() -> bool { + true +} + +fn main() {} -- cgit v1.2.3