1 files changed, 25 insertions, 0 deletions
diff --git a/tests/ui/coherence/negative-coherence-placeholder-region-constraints-on-unification.rs b/tests/ui/coherence/negative-coherence-placeholder-region-constraints-on-unification.rs
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index 000000000..26d9d84d8
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+++ b/tests/ui/coherence/negative-coherence-placeholder-region-constraints-on-unification.rs
@@ -0,0 +1,25 @@
+// revisions: explicit implicit
+//[implicit] check-pass
+
+#![forbid(coherence_leak_check)]
+#![feature(negative_impls, with_negative_coherence)]
+
+pub trait Marker {}
+
+#[cfg(implicit)]
+impl<T: ?Sized> !Marker for &T {}
+
+#[cfg(explicit)]
+impl<'a, T: ?Sized + 'a> !Marker for &'a T {}
+
+trait FnMarker {}
+
+// Unifying these two impls below results in a `T: '!0` obligation
+// that we shouldn't need to care about. Ideally, we'd treat that
+// as an assumption when proving `&'!0 T: Marker`...
+impl<T: ?Sized + Marker> FnMarker for fn(T) {}
+impl<T: ?Sized> FnMarker for fn(&T) {}
+//[explicit]~^ ERROR conflicting implementations of trait `FnMarker` for type `fn(&_)`
+//[explicit]~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+fn main() {}