Merge pull request #560 from rustbot/triagebot-ice-79636

ICE - rust-lang/rust#79636

ices/79636.rs

@@ -0,0 +1,22 @@
+#![feature(generic_associated_types)]
+
+trait Monad {
+    type Unwrapped;
+    type Wrapped<B>;
+
+    fn bind<B, F>(self, f: F) -> Self::Wrapped<B> {
+        todo!()
+    }
+}
+
+fn join<MOuter, MInner, A>(outer: MOuter) -> MOuter::Wrapped<A>
+where
+    MOuter: Monad<Unwrapped = MInner>,
+    MInner: Monad<Unwrapped = A, Wrapped = MOuter::Wrapped<A>>,
+{
+    outer.bind(|inner| inner)
+}
+
+fn main() {
+    assert_eq!(join(Some(Some(true))), Some(true));
+}