GN: Makes GN output deterministic

tools/gn/target.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/target.h"
 
 #include "base/bind.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "tools/gn/config_values_extractors.h"
 #include "tools/gn/deps_iterator.h"
 #include "tools/gn/filesystem_utils.h"
+#include "tools/gn/pointer_set.h"
 #include "tools/gn/scheduler.h"
 #include "tools/gn/substitution_writer.h"
 #include "tools/gn/trace.h"
 
 namespace {
 
 typedef std::set<const Config*> ConfigSet;
 
 // Merges the public configs from the given target to the given config list.
 void MergePublicConfigsFrom(const Target* from_target,
@@ skipping 40 matching lines @@
 
 // Set check_private_deps to true for the first invocation since a target
 // can see all of its dependencies. For recursive invocations this will be set
 // to false to follow only public dependency paths.
 //
 // Pass a pointer to an empty set for the first invocation. This will be used
 // to avoid duplicate checking.
 bool EnsureFileIsGeneratedByDependency(const Target* target,
                                        const OutputFile& file,
                                        bool check_private_deps,
-                                       std::set<const Target*>* seen_targets) {
+                                       PointerSet<const Target>* seen_targets) {
   if (seen_targets->find(target) != seen_targets->end())
     return false;  // Already checked this one and it's not found.
   seen_targets->insert(target);
 
   // Assume that we have relatively few generated inputs so brute-force
   // searching here is OK. If this becomes a bottleneck, consider storing
   // computed_outputs as a hash set.
   for (const OutputFile& cur : target->computed_outputs()) {
     if (file == cur)
       return true;
@@ skipping 457 matching lines @@
 
 void Target::CheckSourceGenerated(const SourceFile& source) const {
   if (!IsStringInOutputDir(settings()->build_settings()->build_dir(),
                            source.value()))
     return;  // Not in output dir, this is OK.
 
   // Tell the scheduler about unknown files. This will be noted for later so
   // the list of files written by the GN build itself (often response files)
   // can be filtered out of this list.
   OutputFile out_file(settings()->build_settings(), source);
-  std::set<const Target*> seen_targets;
+  PointerSet<const Target> seen_targets;
   if (!EnsureFileIsGeneratedByDependency(this, out_file, true, &seen_targets))
     g_scheduler->AddUnknownGeneratedInput(this, source);
 }
+
+bool Target::operator<(const Target& other) const {

[mithro-old, 2015/12/03 05:20:31]

I'm unsure if we want an implicit less than operator. Check with the gn
developers if they are okay with this.

[Zachary Forman, 2015/12/03 07:27:02]

Acknowledged.

I'll leave this for the GN developers to comment on - my thought is that a
target (or perhaps, rather, an item) has
a natural ordering based on the label.

+  return label() < other.label();
+}