From 52de679c193c249d771d84fdaa1cce0bf70404a4 Mon Sep 17 00:00:00 2001
From: Oli Scherer <git-spam-no-reply9815368754983@oli-obk.de>
Date: Tue, 3 May 2022 09:50:17 +0000
Subject: [PATCH] Add regression test

---
 .../auxiliary/collect_hidden_types.rs         | 21 ++++++++++++++++++
 .../collect_hidden_types.rs                   | 22 +++++++++++++++++++
 2 files changed, 43 insertions(+)
 create mode 100644 src/test/ui/type-alias-impl-trait/auxiliary/collect_hidden_types.rs
 create mode 100644 src/test/ui/type-alias-impl-trait/collect_hidden_types.rs

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 0000000000000..75d20a6fef9fe
--- /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() }
+    }
+}
diff --git a/src/test/ui/type-alias-impl-trait/collect_hidden_types.rs b/src/test/ui/type-alias-impl-trait/collect_hidden_types.rs
new file mode 100644
index 0000000000000..e78f178e464eb
--- /dev/null
+++ b/src/test/ui/type-alias-impl-trait/collect_hidden_types.rs
@@ -0,0 +1,22 @@
+// aux-build:collect_hidden_types.rs
+use collect_hidden_types::Service;
+use std::future::Future;
+use std::pin::Pin;
+use std::task::Context;
+
+// build-pass
+
+// edition:2018
+
+extern crate collect_hidden_types;
+
+fn broken(mut a: collect_hidden_types::A, cx: &mut Context<'_>) {
+    let mut fut = a.call(());
+    let _ = unsafe { Pin::new_unchecked(&mut fut) }.poll(cx);
+}
+
+pub async fn meeb(cx: &mut Context<'_>) {
+    broken(collect_hidden_types::A, cx);
+}
+
+fn main() {}