fix warn-xparser test

for https://reviews.llvm.org/D140224

diff --git a/clang/test/Driver/warn-Xparser.c b/clang/test/Driver/warn-Xparser.c
index 191826a..d20db97 100644 (file)
--- a/clang/test/Driver/warn-Xparser.c
+++ b/clang/test/Driver/warn-Xparser.c
@@ -1,5 +1,5 @@
 /// Some macOS projects use -Xparser.
-// RUN: %clang -c -Xparser %s 2>&1 | FileCheck %s
+// RUN: %clang -c -o /dev/null -Xparser %s 2>&1 | FileCheck %s
 
 // CHECK: warning: argument unused during compilation: '-Xparser' [-Wunused-command-line-argument]