From a843fd4e17bc88895a265136a775e73b4d44dd0a Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Wed, 12 Feb 2020 21:50:54 +0100
Subject: [PATCH] add test for layout optimizations

---
 tests/run-pass/stacked-borrows/refcell.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tests/run-pass/stacked-borrows/refcell.rs b/tests/run-pass/stacked-borrows/refcell.rs
index 0939a666193e..83db10577ceb 100644
--- a/tests/run-pass/stacked-borrows/refcell.rs
+++ b/tests/run-pass/stacked-borrows/refcell.rs
@@ -4,6 +4,7 @@ fn main() {
     basic();
     ref_protector();
     ref_mut_protector();
+    rust_issue_68303();
 }
 
 fn basic() {
@@ -66,3 +67,11 @@ fn ref_mut_protector() {
     let rc = RefCell::new(0);
     break_it(&rc, rc.borrow_mut())
 }
+
+/// Make sure we do not have bad enum layout optimizations.
+fn rust_issue_68303() {
+    let optional=Some(RefCell::new(false));
+    let mut handle=optional.as_ref().unwrap().borrow_mut();
+    assert!(optional.is_some());
+    *handle=true;
+}