1 files changed, 13 insertions, 0 deletions
diff --git a/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use4.rs b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use4.rs
new file mode 100644
index 000000000..d1e5a0f01
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/generic_duplicate_param_use4.rs
@@ -0,0 +1,13 @@
+#![feature(type_alias_impl_trait)]
+
+use std::fmt::Debug;
+
+fn main() {}
+
+// test that unused generic parameters are ok
+type Two<T, U> = impl Debug;
+
+fn three<T, U: Debug>(_: T, u: U) -> Two<T, U> {
+    u
+    //~^ ERROR `U` doesn't implement `Debug`
+}