1 files changed, 17 insertions, 0 deletions
diff --git a/tests/ui/traits/next-solver/alias_eq_substs_eq_not_intercrate.rs b/tests/ui/traits/next-solver/alias_eq_substs_eq_not_intercrate.rs
new file mode 100644
index 000000000..4717aa804
--- /dev/null
+++ b/tests/ui/traits/next-solver/alias_eq_substs_eq_not_intercrate.rs
@@ -0,0 +1,17 @@
+// compile-flags: -Znext-solver
+
+// check that a `alias-eq(<?a as TraitB>::Assoc, <?b as TraitB>::Assoc)` goal fails
+// during coherence. We must not incorrectly constrain `?a` and `?b` to be
+// equal.
+
+trait TraitB {
+    type Assoc;
+}
+
+trait Overlaps<T> {}
+
+impl<T: TraitB> Overlaps<Box<T>> for <T as TraitB>::Assoc {}
+impl<U: TraitB> Overlaps<U> for <U as TraitB>::Assoc {}
+//~^ ERROR conflicting implementations of trait
+
+fn main() {}