1 files changed, 38 insertions, 0 deletions
diff --git a/src/test/ui/nll/issue-57642-higher-ranked-subtype.rs b/src/test/ui/nll/issue-57642-higher-ranked-subtype.rs
new file mode 100644
index 000000000..eba859cde
--- /dev/null
+++ b/src/test/ui/nll/issue-57642-higher-ranked-subtype.rs
@@ -0,0 +1,38 @@
+// Regression test for issue #57642
+// Tests that we reject a bad higher-ranked subtype
+
+trait X {
+    type G;
+    fn make_g() -> Self::G;
+}
+
+impl<'a> X for fn(&'a ()) {
+    type G = &'a ();
+
+    fn make_g() -> Self::G {
+        &()
+    }
+}
+
+trait Y {
+    type F;
+    fn make_f() -> Self::F;
+}
+
+impl<T> Y for fn(T) {
+    type F = fn(T);
+
+    fn make_f() -> Self::F {
+        |_| {}
+    }
+}
+
+fn higher_ranked_region_has_lost_its_binder() {
+    let x = <fn (&())>::make_g(); //~ ERROR the function
+}
+
+fn magical() {
+    let x = <fn (&())>::make_f(); //~ ERROR no function
+}
+
+fn main() {}