[clang][NFC] Add a missing /dev/null in test/AST/ast-dump-lambda.cpp
diff --git a/clang/test/AST/ast-dump-lambda.cpp b/clang/test/AST/ast-dump-lambda.cpp
index a3ca4a8..37fb62e 100644
--- a/clang/test/AST/ast-dump-lambda.cpp
+++ b/clang/test/AST/ast-dump-lambda.cpp
@@ -7,7 +7,7 @@
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -Wno-unused-value -std=gnu++17 \
// RUN: -emit-pch -o %t %s
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -Wno-unused-value -std=gnu++17 \
-// RUN: -x c++ -include-pch %t -ast-dump-all -ast-dump-filter test \
+// RUN: -x c++ -include-pch %t -ast-dump-all -ast-dump-filter test /dev/null \
// RUN: | FileCheck -strict-whitespace --match-full-lines %s
