Fix a warning

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@42973 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Sema/format-strings.c b/test/Sema/format-strings.c
index 2222f79..e5bbd70 100644
--- a/test/Sema/format-strings.c
+++ b/test/Sema/format-strings.c
@@ -59,7 +59,7 @@
   va_start(ap,b);
 
   printf(L"foo %d",2); // expected-warning {{should not be a wide string}}
-  vasprintf(&b,L"bar %d",2); // expected-warning {{should not be a wide string}}
+  vasprintf(&b,L"bar %d",ap); // expected-warning {{should not be a wide string}}
 }
 
 void check_asterisk_precision_width(int x) {