1 files changed, 18 insertions, 0 deletions
diff --git a/tests/ui/regions/regions-infer-reborrow-ref-mut-recurse.rs b/tests/ui/regions/regions-infer-reborrow-ref-mut-recurse.rs
new file mode 100644
index 000000000..31a48b4ad
--- /dev/null
+++ b/tests/ui/regions/regions-infer-reborrow-ref-mut-recurse.rs
@@ -0,0 +1,18 @@
+// run-pass
+#![allow(dead_code)]
+// Test an edge case in region inference: the lifetime of the borrow
+// of `*x` must be extended to at least 'a.
+
+// pretty-expanded FIXME #23616
+
+fn foo<'a,'b>(x: &'a &'b mut isize) -> &'a isize {
+    let y = &*x; // should be inferred to have type &'a &'b mut isize...
+
+    // ...because if we inferred, say, &'x &'b mut isize where 'x <= 'a,
+    // this reborrow would be illegal:
+    &**y
+}
+
+pub fn main() {
+    /* Just want to know that it compiles. */
+}