Add regression test

src/test/ui/closures/2229_closure_analysis/issue-89606.rs

@@ -0,0 +1,40 @@
+// Regression test for #89606. Used to ICE.
+//
+// check-pass
+// revisions: twenty_eighteen twenty_twentyone
+// [twenty_eighteen]compile-flags: --edition 2018
+// [twenty_twentyone]compile-flags: --edition 2021
+
+struct S<'a>(Option<&'a mut i32>);
+
+fn by_ref(s: &mut S<'_>) {
+    (|| {
+        let S(_o) = s;
+        s.0 = None;
+    })();
+}
+
+fn by_value(s: S<'_>) {
+    (|| {
+        let S(ref _o) = s;
+        let _g = s.0;
+    })();
+}
+
+struct V<'a>((Option<&'a mut i32>,));
+
+fn nested(v: &mut V<'_>) {
+    (|| {
+        let V((_o,)) = v;
+        v.0 = (None, );
+    })();
+}
+
+fn main() {
+    let mut s = S(None);
+    by_ref(&mut s);
+    by_value(s);
+
+    let mut v = V((None, ));
+    nested(&mut v);
+}