1 files changed, 29 insertions, 0 deletions
diff --git a/src/test/ui/generic-associated-types/bugs/issue-91762.rs b/src/test/ui/generic-associated-types/bugs/issue-91762.rs
new file mode 100644
index 000000000..796935cc0
--- /dev/null
+++ b/src/test/ui/generic-associated-types/bugs/issue-91762.rs
@@ -0,0 +1,29 @@
+// check-fail
+// known-bug
+
+// We almost certaintly want this to pass, but
+// it's particularly difficult currently, because we need a way of specifying
+// that `<Self::Base as Functor>::With<T> = Self` without using that when we have
+// a `U`. See `https://github.com/rust-lang/rust/pull/92728` for a (hacky)
+// solution. This might be better to just wait for Chalk.
+
+pub trait Functor {
+    type With<T>;
+
+    fn fmap<T, U>(this: Self::With<T>) -> Self::With<U>;
+}
+
+pub trait FunctorExt<T>: Sized {
+    type Base: Functor<With<T> = Self>;
+
+    fn fmap<U>(self) {
+        let arg: <Self::Base as Functor>::With<T>;
+        let ret: <Self::Base as Functor>::With<U>;
+
+        arg = self;
+        ret = <Self::Base as Functor>::fmap(arg);
+        //~^ type annotations needed
+    }
+}
+
+fn main() {}