1 files changed, 42 insertions, 0 deletions
diff --git a/src/test/ui/impl-trait/hidden-type-is-opaque.rs b/src/test/ui/impl-trait/hidden-type-is-opaque.rs
new file mode 100644
index 000000000..72b4028d8
--- /dev/null
+++ b/src/test/ui/impl-trait/hidden-type-is-opaque.rs
@@ -0,0 +1,42 @@
+// check-pass
+#![feature(type_alias_impl_trait)]
+
+fn reify_as() -> Thunk<impl ContFn> {
+    Thunk::new(|mut cont| {
+        cont.reify_as();
+        cont
+    })
+}
+
+type Tait = impl ContFn;
+
+fn reify_as_tait() -> Thunk<Tait> {
+    Thunk::new(|mut cont| {
+        cont.reify_as();
+        cont
+    })
+}
+
+#[must_use]
+struct Thunk<F>(F);
+
+impl<F> Thunk<F> {
+    fn new(f: F) -> Self
+    where
+        F: FnOnce(Continuation) -> Continuation,
+    {
+        Thunk(f)
+    }
+}
+
+trait ContFn {}
+
+impl<F: FnOnce(Continuation) -> Continuation> ContFn for F {}
+
+struct Continuation;
+
+impl Continuation {
+    fn reify_as(&mut self) {}
+}
+
+fn main() {}