1 files changed, 16 insertions, 0 deletions
diff --git a/src/test/ui/match/match-ref-mut-let-invariance.rs b/src/test/ui/match/match-ref-mut-let-invariance.rs
new file mode 100644
index 000000000..a33be09ac
--- /dev/null
+++ b/src/test/ui/match/match-ref-mut-let-invariance.rs
@@ -0,0 +1,16 @@
+// Check that when making a ref mut binding with type `&mut T`, the
+// type `T` must match precisely the type `U` of the value being
+// matched, and in particular cannot be some supertype of `U`. Issue
+// #23116. This test focuses on a `let`.
+
+#![allow(dead_code)]
+struct S<'b>(&'b i32);
+impl<'b> S<'b> {
+    fn bar<'a>(&'a mut self) -> &'a mut &'a i32 {
+        let ref mut x = self.0;
+        x
+        //~^ ERROR lifetime may not live long enough
+    }
+}
+
+fn main() {}