From 17d40c6057c88f4c432b0d7bac88e1b84cb7e67f Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:03:36 +0200 Subject: Adding upstream version 1.65.0+dfsg1. Signed-off-by: Daniel Baumann --- .../hrtb-exists-forall-trait-invariant.rs | 29 ++++++++++++++++++++++ 1 file changed, 29 insertions(+) create mode 100644 src/test/ui/higher-rank-trait-bounds/hrtb-exists-forall-trait-invariant.rs (limited to 'src/test/ui/higher-rank-trait-bounds/hrtb-exists-forall-trait-invariant.rs') diff --git a/src/test/ui/higher-rank-trait-bounds/hrtb-exists-forall-trait-invariant.rs b/src/test/ui/higher-rank-trait-bounds/hrtb-exists-forall-trait-invariant.rs new file mode 100644 index 000000000..9b9e4496a --- /dev/null +++ b/src/test/ui/higher-rank-trait-bounds/hrtb-exists-forall-trait-invariant.rs @@ -0,0 +1,29 @@ +// Test an `exists<'a> { forall<'b> { 'a = 'b } }` pattern -- which should not compile! +// +// In particular, we test this pattern in trait solving, where it is not connected +// to any part of the source code. + +use std::cell::Cell; + +trait Trait {} + +fn foo() +where + T: Trait fn(Cell<&'b u32>)>, +{ +} + +impl<'a> Trait)> for () {} + +fn main() { + // Here, proving that `(): Trait fn(&'b u32)>` uses the impl: + // + // - The impl provides the clause `forall<'a> { (): Trait }` + // - We instantiate `'a` existentially to get `(): Trait` + // - We unify `fn(&?a u32)` with `for<'b> fn(&'b u32)` + // - This requires (among other things) instantiating `'b` universally, + // yielding `fn(&!b u32)`, in a fresh universe U1 + // - So we get `?a = !b` but the universe U0 assigned to `?a` cannot name `!b`. + + foo::<()>(); //~ ERROR implementation of `Trait` is not general enough +} -- cgit v1.2.3