Mark variables captured by reference as mutable correctly

src/test/ui/nll/extra-unused-mut.rs

@@ -1,6 +1,6 @@
 // extra unused mut lint tests for #51918
 
-// run-pass
+// compile-pass
 
 #![feature(generators, nll)]
 #![deny(unused_mut)]
@@ -53,11 +53,14 @@ fn if_guard(x: Result<i32, i32>) {
     }
 }
 
-fn main() {
-    ref_argument(0);
-    mutable_upvar();
-    generator_mutable_upvar();
-    ref_closure_argument();
-    parse_dot_or_call_expr_with(Vec::new());
-    if_guard(Ok(0));
+// #59620
+fn nested_closures() {
+    let mut i = 0;
+    [].iter().for_each(|_: &i32| {
+        [].iter().for_each(move |_: &i32| {
+            i += 1;
+        });
+    });
 }
+
+fn main() {}