Cherry-pick upstream r238083

test/Sema/atomic-compare.c

Index: test/Sema/atomic-compare.c
diff --git a/test/Sema/atomic-compare.c b/test/Sema/atomic-compare.c
index 2eed091260267d3002d490ac695a3b2bfe5d383b..01eb8200472560fe24e0bffe8736e9cd92628ae1 100644
--- a/test/Sema/atomic-compare.c
+++ b/test/Sema/atomic-compare.c
@@ -19,3 +19,8 @@ void f(_Atomic(int) a, _Atomic(int) b) {
   if (!a > b)     {} // no warning
   if (!a > -1)    {} // expected-warning {{comparison of constant -1 with boolean expression is always true}}
 }
+
+typedef _Atomic(int) Ty;
+void PR23638(Ty *a) {
+  if (*a == 1) {} // no warning
+}