1 files changed, 30 insertions, 0 deletions
diff --git a/tests/ui/regions/regions-fn-subtyping.rs b/tests/ui/regions/regions-fn-subtyping.rs
new file mode 100644
index 000000000..9570359c6
--- /dev/null
+++ b/tests/ui/regions/regions-fn-subtyping.rs
@@ -0,0 +1,30 @@
+// run-pass
+#![allow(dead_code)]
+#![allow(unused_assignments)]
+// Issue #2263.
+
+// pretty-expanded FIXME #23616
+
+#![allow(unused_variables)]
+
+// Should pass region checking.
+fn ok(f: Box<dyn FnMut(&usize)>) {
+    // Here, g is a function that can accept a usize pointer with
+    // lifetime r, and f is a function that can accept a usize pointer
+    // with any lifetime.  The assignment g = f should be OK (i.e.,
+    // f's type should be a subtype of g's type), because f can be
+    // used in any context that expects g's type.  But this currently
+    // fails.
+    let mut g: Box<dyn for<'r> FnMut(&'r usize)> = Box::new(|x| { });
+    g = f;
+}
+
+// This version is the same as above, except that here, g's type is
+// inferred.
+fn ok_inferred(f: Box<dyn FnMut(&usize)>) {
+    let mut g: Box<dyn for<'r> FnMut(&'r usize)> = Box::new(|_| {});
+    g = f;
+}
+
+pub fn main() {
+}