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Diffstat (limited to 'src/test/ui/coherence/coherence-fn-covariant-bound-vs-static.rs')
| -rw-r--r-- | src/test/ui/coherence/coherence-fn-covariant-bound-vs-static.rs | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/src/test/ui/coherence/coherence-fn-covariant-bound-vs-static.rs b/src/test/ui/coherence/coherence-fn-covariant-bound-vs-static.rs new file mode 100644 index 000000000..99f805f7f --- /dev/null +++ b/src/test/ui/coherence/coherence-fn-covariant-bound-vs-static.rs @@ -0,0 +1,26 @@ +// Test that impls for these two types are considered ovelapping: +// +// * `for<'r> fn(fn(&'r u32))` +// * `fn(fn(&'a u32)` where `'a` is free +// +// This is because, for `'a = 'static`, the two types overlap. +// Effectively for them to be equal to you get: +// +// * `for<'r> fn(fn(&'r u32)) <: fn(fn(&'static u32))` +// * true if `exists<'r> { 'r: 'static }` (obviously true) +// * `fn(fn(&'static u32)) <: for<'r> fn(fn(&'r u32))` +// * true if `forall<'r> { 'static: 'r }` (also true) + +trait Trait {} + +impl Trait for for<'r> fn(fn(&'r ())) {} +impl<'a> Trait for fn(fn(&'a ())) {} +//~^ ERROR conflicting implementations +// +// Note in particular that we do NOT get a future-compatibility warning +// here. This is because the new leak-check proposed in [MCP 295] does not +// "error" when these two types are equated. +// +// [MCP 295]: https://github.com/rust-lang/compiler-team/issues/295 + +fn main() {} |