1 files changed, 22 insertions, 0 deletions
diff --git a/tests/ui/traits/new-solver/specialization-unconstrained.rs b/tests/ui/traits/new-solver/specialization-unconstrained.rs
new file mode 100644
index 000000000..02150689e
--- /dev/null
+++ b/tests/ui/traits/new-solver/specialization-unconstrained.rs
@@ -0,0 +1,22 @@
+// compile-flags: -Ztrait-solver=next
+
+#![feature(specialization)]
+//~^ WARN the feature `specialization` is incomplete
+
+// Do not treat the RHS of a projection-goal as an unconstrained `Certainty::Yes` response
+// if the impl is still further specializable.
+
+trait Default {
+   type Id;
+}
+
+impl<T> Default for T {
+   default type Id = T;
+}
+
+fn test<T: Default<Id = U>, U>() {}
+
+fn main() {
+    test::<u32, ()>();
+    //~^ ERROR cannot satisfy `<u32 as Default>::Id == ()`
+}