1 files changed, 36 insertions, 0 deletions
diff --git a/src/test/ui/associated-types/normalization-debruijn-1.rs b/src/test/ui/associated-types/normalization-debruijn-1.rs
new file mode 100644
index 000000000..a5abf1ba9
--- /dev/null
+++ b/src/test/ui/associated-types/normalization-debruijn-1.rs
@@ -0,0 +1,36 @@
+// build-pass
+// edition:2018
+
+// Regression test to ensure we handle debruijn indices correctly in projection
+// normalization under binders. Found in crater run for #85499
+
+use std::future::Future;
+use std::pin::Pin;
+pub enum Outcome<S, E> {
+    Success((S, E)),
+}
+pub struct Request<'r> {
+    _marker: std::marker::PhantomData<&'r ()>,
+}
+pub trait FromRequest<'r>: Sized {
+    type Error;
+    fn from_request<'life0>(
+        request: &'r Request<'life0>,
+    ) -> Pin<Box<dyn Future<Output = Outcome<Self, Self::Error>>>>;
+}
+impl<'r, T: FromRequest<'r>> FromRequest<'r> for Option<T> {
+    type Error = ();
+    fn from_request<'life0>(
+        request: &'r Request<'life0>,
+    ) -> Pin<Box<dyn Future<Output = Outcome<Self, Self::Error>>>> {
+        Box::pin(async move {
+            let request = request;
+            match T::from_request(request).await {
+                _ => todo!(),
+            }
+        });
+        todo!()
+    }
+}
+
+fn main() {}