Enable -Wshift-negative-value.

sandbox/linux/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/features.gni")
 import("//build/config/nacl/config.gni")
 import("//sandbox/features.gni")
 import("//testing/test.gni")
 
 if (is_android) {
@@ skipping 128 matching lines @@
       "integration_tests/bpf_dsl_seccomp_unittest.cc",
       "integration_tests/seccomp_broker_process_unittest.cc",
       "seccomp-bpf-helpers/baseline_policy_unittest.cc",
       "seccomp-bpf-helpers/syscall_parameters_restrictions_unittests.cc",
       "seccomp-bpf/bpf_tests_unittest.cc",
       "seccomp-bpf/sandbox_bpf_unittest.cc",
       "seccomp-bpf/syscall_unittest.cc",
       "seccomp-bpf/trap_unittest.cc",
     ]
     deps += [ ":bpf_dsl_golden" ]
+
+    # syscall_parameters_restrictions_unittests.cc uses MAKE_PROCESS_CPUCLOCK,
+    # which shifts signed ints around, which has undefined behavior.
+    # TODO(thakis): Fix that in LSS, then remove this flag here.
+    cflags = [ "-Wno-shift-negative-value" ]
   }
   if (compile_credentials) {
     sources += [
       "integration_tests/namespace_unix_domain_socket_unittest.cc",
       "services/credentials_unittest.cc",
       "services/namespace_utils_unittest.cc",
     ]
 
     if (use_base_test_suite) {
       # Tests that use advanced features not available in stock GTest.
@@ skipping 273 matching lines @@
 
 if (is_android) {
   # TODO(GYP_GONE) Delete this after we've converted everything to GN.
   group("sandbox_linux_unittests_deps") {
     testonly = true
     deps = [
       ":sandbox_linux_unittests",
     ]
   }
 }