1 files changed, 21 insertions, 0 deletions
diff --git a/src/test/ui/type-alias-impl-trait/auxiliary/collect_hidden_types.rs b/src/test/ui/type-alias-impl-trait/auxiliary/collect_hidden_types.rs
new file mode 100644
index 000000000..75d20a6fe
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/auxiliary/collect_hidden_types.rs
@@ -0,0 +1,21 @@
+#![feature(type_alias_impl_trait)]
+
+// edition:2018
+
+use std::future::Future;
+
+pub trait Service<Request> {
+    type Future: Future<Output = ()>;
+    fn call(&mut self, req: Request) -> Self::Future;
+}
+
+// NOTE: the pub(crate) here is critical
+pub(crate) fn new() -> () {}
+
+pub struct A;
+impl Service<()> for A {
+    type Future = impl Future<Output = ()>;
+    fn call(&mut self, _: ()) -> Self::Future {
+        async { new() }
+    }
+}