1 files changed, 32 insertions, 0 deletions

diff --git a/tests/ui/impl-trait/issues/issue-83919.rs b/tests/ui/impl-trait/issues/issue-83919.rs
new file mode 100644
index 00000000000..e76443a65db
--- /dev/null
+++ b/tests/ui/impl-trait/issues/issue-83919.rs
@@ -0,0 +1,32 @@
+#![feature(type_alias_impl_trait)]
+
+// edition:2021
+
+use std::future::Future;
+
+trait Foo {
+    type T;
+    type Fut2: Future<Output=Self::T>; // ICE got triggered with traits other than Future here
+    type Fut: Future<Output=Self::Fut2>;
+    fn get_fut(&self) -> Self::Fut;
+}
+
+struct Implementor;
+
+impl Foo for Implementor {
+    type T = u64;
+    type Fut2 = impl Future<Output=u64>;
+    type Fut = impl Future<Output=Self::Fut2>;
+
+    fn get_fut(&self) -> Self::Fut {
+    //~^ ERROR `{integer}` is not a future
+        async move {
+            42
+            // 42 does not impl Future and rustc does actually point out the error,
+            // but rustc used to panic.
+            // Putting a valid Future here always worked fine.
+        }
+    }
+}
+
+fn main() {}