gn: Make generation of main build.ninja file deterministic.

tools/gn/ninja_build_writer_unittest.cc

 // Copyright 2016 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 <sstream>
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/ninja_build_writer.h"
 #include "tools/gn/pool.h"
 #include "tools/gn/scheduler.h"
@@ skipping 30 matching lines @@
   other_pool.set_depth(42);
   Toolchain other_toolchain(setup.settings(), other_toolchain_label);
   TestWithScope::SetupToolchain(&other_toolchain);
   other_toolchain.GetTool(Toolchain::TYPE_LINK)->set_pool(
       LabelPtrPair<Pool>(&other_pool));
 
   // Settings to go with the other toolchain.
   Settings other_settings(setup.build_settings(), "toolchain/");
   other_settings.set_toolchain_label(other_toolchain_label);
 
-  std::map<const Settings*, const Toolchain*> used_toolchains;
+  std::unordered_map<const Settings*, const Toolchain*> used_toolchains;
   used_toolchains[setup.settings()] = setup.toolchain();
   used_toolchains[&other_settings] = &other_toolchain;
 
   std::vector<const Target*> targets = { &target_foo, &target_bar };
 
   std::ostringstream ninja_out;
   std::ostringstream depfile_out;
 
   NinjaBuildWriter writer(setup.build_settings(), used_toolchains,
                           setup.toolchain(), targets, ninja_out, depfile_out);
@@ skipping 48 matching lines @@
   ASSERT_TRUE(target_foo.OnResolved(&err));
 
   Target target_bar(setup.settings(), Label(SourceDir("//bar/"), "bar"));
   target_bar.set_output_type(Target::ACTION);
   target_bar.action_values().set_script(SourceFile("//bar/script.py"));
   target_bar.action_values().outputs() = SubstitutionList::MakeForTest(
       "//out/Debug/out3.out", "//out/Debug/out2.out");
   target_bar.SetToolchain(setup.toolchain());
   ASSERT_TRUE(target_bar.OnResolved(&err));
 
-  std::map<const Settings*, const Toolchain*> used_toolchains;
+  std::unordered_map<const Settings*, const Toolchain*> used_toolchains;
   used_toolchains[setup.settings()] = setup.toolchain();
   std::vector<const Target*> targets = { &target_foo, &target_bar };
   std::ostringstream ninja_out;
   std::ostringstream depfile_out;
   NinjaBuildWriter writer(setup.build_settings(), used_toolchains,
                           setup.toolchain(), targets, ninja_out, depfile_out);
   ASSERT_FALSE(writer.Run(&err));
 
   const char expected_help_test[] =
       "Two or more targets generate the same output:\n"
       "  out2.out\n"
       "\n"
       "This is can often be fixed by changing one of the target names, or by \n"
       "setting an output_name on one of them.\n"
       "\n"
       "Collisions:\n"
       "  //foo:bar\n"
       "  //bar:bar\n";
 
   EXPECT_EQ(expected_help_test, err.help_text());
 }