From ec5ba54ed2f0db8dae06f0f89b183bbfd0306238 Mon Sep 17 00:00:00 2001
From: Dylan MacKenzie <ecstaticmorse@gmail.com>
Date: Wed, 6 Nov 2019 07:09:16 -0800
Subject: [PATCH] Add test for promotability in `let`

The old const-checker conservatively reset qualifs when
`IsNotPromotable` was in the return place. Unfortunately, named
variables have `IsNotPromotable`, so this could cause promotion to fail.
This should work now.
---
 src/test/ui/consts/const_let_promote.rs | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 src/test/ui/consts/const_let_promote.rs

diff --git a/src/test/ui/consts/const_let_promote.rs b/src/test/ui/consts/const_let_promote.rs
new file mode 100644
index 0000000000000..f4661e9e425ba
--- /dev/null
+++ b/src/test/ui/consts/const_let_promote.rs
@@ -0,0 +1,17 @@
+// run-pass
+
+use std::cell::Cell;
+
+const X: Option<Cell<i32>> = None;
+
+const Y: Option<Cell<i32>> = {
+    let x = None;
+    x
+};
+
+// Ensure that binding the final value of a `const` to a variable does not affect promotion.
+#[allow(unused)]
+fn main() {
+    let x: &'static _ = &X;
+    let y: &'static _ = &Y;
+}