1 files changed, 36 insertions, 0 deletions

diff --git a/tests/ui/impl-trait/issues/issue-70877.rs b/tests/ui/impl-trait/issues/issue-70877.rs
new file mode 100644
index 00000000000..8169cfafac7
--- /dev/null
+++ b/tests/ui/impl-trait/issues/issue-70877.rs
@@ -0,0 +1,36 @@
+#![feature(type_alias_impl_trait)]
+
+type FooArg<'a> = &'a dyn ToString;
+type FooRet = impl std::fmt::Debug;
+
+type FooItem = Box<dyn Fn(FooArg) -> FooRet>;
+type Foo = impl Iterator<Item = FooItem>;
+
+#[repr(C)]
+struct Bar(u8);
+
+impl Iterator for Bar {
+    type Item = FooItem;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        Some(Box::new(quux))
+    }
+}
+
+fn quux(st: FooArg) -> FooRet {
+    Some(st.to_string())
+}
+
+fn ham() -> Foo {
+    Bar(1)
+}
+
+fn oof() -> impl std::fmt::Debug {
+    let mut bar = ham();
+    let func = bar.next().unwrap();
+    return func(&"oof"); //~ ERROR opaque type's hidden type cannot be another opaque type
+}
+
+fn main() {
+    let _ = oof();
+}