Add test for issue rust-lang#79949

Author: marmeladema

src/test/ui/associated-type-bounds/issue-79949.rs

@@ -0,0 +1,26 @@
+// check-pass
+
+#![allow(incomplete_features)]
+#![feature(associated_type_bounds)]
+#![feature(generic_associated_types)]
+
+trait MP {
+    type T<'a>;
+}
+struct S(String);
+impl MP for S {
+    type T<'a> = &'a str;
+}
+
+trait SR: MP {
+    fn sr<IM>(&self) -> i32
+    where
+        for<'a> IM: T<T: U<<Self as MP>::T<'a>>>;
+}
+
+trait T {
+    type T;
+}
+trait U<X> {}
+
+fn main() {}