GN: Makes GN output deterministic

tools/gn/ninja_target_writer.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/ninja_target_writer.h"
 
 #include <sstream>
 
 #include "base/files/file_util.h"
 #include "base/strings/string_util.h"
+#include "tools/gn/dereference_comparator.h"
 #include "tools/gn/err.h"
 #include "tools/gn/escape.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/ninja_action_target_writer.h"
 #include "tools/gn/ninja_binary_target_writer.h"
 #include "tools/gn/ninja_copy_target_writer.h"
 #include "tools/gn/ninja_group_target_writer.h"
 #include "tools/gn/ninja_utils.h"
 #include "tools/gn/output_file.h"
 #include "tools/gn/scheduler.h"
@@ skipping 179 matching lines @@
     path_output_.WriteFile(out_, input);
   }
   if (list_sources_as_input_deps) {
     for (const auto& source : target_->sources()) {
       out_ << " ";
       path_output_.WriteFile(out_, source);
     }
   }
 
   // The different souces of input deps may duplicate some targets, so uniquify
-  // them (ordering doesn't matter for this case).
-  std::set<const Target*> unique_deps;
+  // them. Note that the order matters, or the output is non-deterministic.
+  PointerSet<const Target> unique_deps;
 
   // Hard dependencies that are direct or indirect dependencies.
-  const std::set<const Target*>& hard_deps = target_->recursive_hard_deps();
-  for (const auto& dep : hard_deps)
-    unique_deps.insert(dep);
+  const PointerSet<const Target>& hard_deps = target_->recursive_hard_deps();
 
+  unique_deps.insert(hard_deps.begin(), hard_deps.end());
   // Extra hard dependencies passed in.
   unique_deps.insert(extra_hard_deps.begin(), extra_hard_deps.end());
 
   // Toolchain dependencies. These must be resolved before doing anything.
   // This just writs all toolchain deps for simplicity. If we find that
   // toolchains often have more than one dependency, we could consider writing
   // a toolchain-specific stamp file and only include the stamp here.
   const LabelTargetVector& toolchain_deps = target_->toolchain()->deps();
   for (const auto& toolchain_dep : toolchain_deps)
     unique_deps.insert(toolchain_dep.ptr);
@@ skipping 27 matching lines @@
        << GetNinjaRulePrefixForToolchain(settings_)
        << Toolchain::ToolTypeToName(Toolchain::TYPE_STAMP);
   path_output_.WriteFiles(out_, files);
 
   if (!order_only_deps.empty()) {
     out_ << " ||";
     path_output_.WriteFiles(out_, order_only_deps);
   }
   out_ << std::endl;
 }