Check for GN args using the union of all rather than individually.

tools/gn/setup.cc

 // Copyright (c) 2013 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.
 
 #include "tools/gn/setup.h"
 
 #include <stdlib.h>
 
 #include <algorithm>
 
@@ skipping 107 matching lines @@
 }
 
 }  // namespace
 
 // CommonSetup -----------------------------------------------------------------
 
 CommonSetup::CommonSetup()
     : build_settings_(),
       loader_(new LoaderImpl(&build_settings_)),
       builder_(new Builder(loader_.get())),
-      check_for_bad_items_(true) {
+      check_for_bad_items_(true),
+      check_for_unused_overrides_(true) {
   loader_->set_complete_callback(base::Bind(&DecrementWorkCount));
 }
 
 CommonSetup::CommonSetup(const CommonSetup& other)
     : build_settings_(other.build_settings_),
       loader_(new LoaderImpl(&build_settings_)),
       builder_(new Builder(loader_.get())),
-      check_for_bad_items_(other.check_for_bad_items_) {
+      check_for_bad_items_(other.check_for_bad_items_),
+      check_for_unused_overrides_(other.check_for_unused_overrides_) {
   loader_->set_complete_callback(base::Bind(&DecrementWorkCount));
 }
 
 CommonSetup::~CommonSetup() {
 }
 
 void CommonSetup::RunPreMessageLoop() {
   // Load the root build file.
   loader_->Load(SourceFile("//BUILD.gn"), Label());
 
   // Will be decremented with the loader is drained.
   g_scheduler->IncrementWorkCount();
 }
 
 bool CommonSetup::RunPostMessageLoop() {
   Err err;
   if (check_for_bad_items_) {
     if (!builder_->CheckForBadItems(&err)) {
       err.PrintToStdout();
       return false;
     }
   }
 
-  if (!build_settings_.build_args().VerifyAllOverridesUsed(&err)) {
-    err.PrintToStdout();
-    return false;
+  if (check_for_unused_overrides_) {
+    if (!build_settings_.build_args().VerifyAllOverridesUsed(&err)) {
+      // TODO(brettw) implement a system of warnings. Until we have a better
+      // system, print the error but don't return failure.
+      err.PrintToStdout();
+      return true;
+    }
   }
 
   // Write out tracing and timing if requested.
   const CommandLine* cmdline = CommandLine::ForCurrentProcess();
   if (cmdline->HasSwitch(kTimeSwitch))
     PrintLongHelp(SummarizeTraces());
   if (cmdline->HasSwitch(kTracelogSwitch))
     SaveTraces(cmdline->GetSwitchValuePath(kTracelogSwitch));
 
   return true;
@@ skipping 253 matching lines @@
 }
 
 void DependentSetup::RunPreMessageLoop() {
   CommonSetup::RunPreMessageLoop();
 }
 
 bool DependentSetup::RunPostMessageLoop() {
   return CommonSetup::RunPostMessageLoop();
 }