1 files changed, 45 insertions, 0 deletions
diff --git a/src/test/ui/lub-glb/empty-binders.rs b/src/test/ui/lub-glb/empty-binders.rs
new file mode 100644
index 000000000..f9d07e79f
--- /dev/null
+++ b/src/test/ui/lub-glb/empty-binders.rs
@@ -0,0 +1,45 @@
+// check-pass
+//
+// Check that computing the lub works even for empty binders.
+fn lt<'a: 'a>() -> &'a () {
+    &()
+}
+
+fn lt_in_fn<'a: 'a>() -> fn(&'a ()) {
+    |_| ()
+}
+
+struct Contra<'a>(fn(&'a ()));
+fn lt_in_contra<'a: 'a>() -> Contra<'a> {
+    Contra(|_| ())
+}
+
+fn ok<'a, 'b, 'upper, 'lower>(v: bool)
+where
+    'upper: 'a,
+    'upper: 'b,
+    'a: 'lower,
+    'b: 'lower,
+
+{
+    let _: &'lower () = match v {
+        true => lt::<'a>(),
+        false => lt::<'b>(),
+    };
+
+    // This errored in the past because LUB and GLB always
+    // bailed out when encountering binders, even if they were
+    // empty.
+    let _: fn(&'upper ()) = match v {
+        true => lt_in_fn::<'a>(),
+        false => lt_in_fn::<'b>(),
+    };
+
+    // This was already accepted, as relate didn't encounter any binders.
+    let _: Contra<'upper> = match v {
+        true => lt_in_contra::<'a>(),
+        false => lt_in_contra::<'b>(),
+    };
+}
+
+fn main() {}