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Diffstat (limited to 'tests/ui/impl-trait/auto-trait-coherence.rs')
-rw-r--r-- | tests/ui/impl-trait/auto-trait-coherence.rs | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/tests/ui/impl-trait/auto-trait-coherence.rs b/tests/ui/impl-trait/auto-trait-coherence.rs new file mode 100644 index 000000000..a5cd01a87 --- /dev/null +++ b/tests/ui/impl-trait/auto-trait-coherence.rs @@ -0,0 +1,28 @@ +// revisions: old next +//[next] compile-flags: -Ztrait-solver=next + +// Tests that type alias impls traits do not leak auto-traits for +// the purposes of coherence checking +#![feature(type_alias_impl_trait)] + +trait OpaqueTrait {} +impl<T> OpaqueTrait for T {} +type OpaqueType = impl OpaqueTrait; +fn mk_opaque() -> OpaqueType { + () +} + +#[derive(Debug)] +struct D<T>(T); + +trait AnotherTrait {} +impl<T: Send> AnotherTrait for T {} + +// This is in error, because we cannot assume that `OpaqueType: !Send`. +// (We treat opaque types as "foreign types" that could grow more impls +// in the future.) +impl AnotherTrait for D<OpaqueType> { + //~^ ERROR conflicting implementations of trait `AnotherTrait` for type `D<OpaqueType>` +} + +fn main() {} |