1 files changed, 19 insertions, 0 deletions
diff --git a/src/test/ui/impl-trait/two_tait_defining_each_other.rs b/src/test/ui/impl-trait/two_tait_defining_each_other.rs
new file mode 100644
index 000000000..6eb2a11b2
--- /dev/null
+++ b/src/test/ui/impl-trait/two_tait_defining_each_other.rs
@@ -0,0 +1,19 @@
+#![feature(type_alias_impl_trait)]
+
+type A = impl Foo;
+type B = impl Foo;
+
+trait Foo {}
+
+fn muh(x: A) -> B {
+    if false {
+        return Bar; // B's hidden type is Bar
+    }
+    x // A's hidden type is `Bar`, because all the hidden types of `B` are compared with each other
+    //~^ ERROR opaque type's hidden type cannot be another opaque type
+}
+
+struct Bar;
+impl Foo for Bar {}
+
+fn main() {}