tools/gn/command_gen.cc - gn.git - Git at Google

 // 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 "base/bind.h"
 #include "base/command_line.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "base/timer/elapsed_timer.h"
 #include "tools/gn/build_settings.h"
 #include "tools/gn/commands.h"
 #include "tools/gn/eclipse_writer.h"
 #include "tools/gn/json_project_writer.h"
 #include "tools/gn/ninja_target_writer.h"
 #include "tools/gn/ninja_writer.h"
 #include "tools/gn/qt_creator_writer.h"
 #include "tools/gn/runtime_deps.h"
 #include "tools/gn/scheduler.h"
 #include "tools/gn/setup.h"
 #include "tools/gn/standard_out.h"
 #include "tools/gn/switches.h"
 #include "tools/gn/target.h"
 #include "tools/gn/visual_studio_writer.h"
 #include "tools/gn/xcode_writer.h"

 namespace commands {

 namespace {

 const char kSwitchCheck[] = "check";
 const char kSwitchFilters[] = "filters";
 const char kSwitchIde[] = "ide";
 const char kSwitchIdeValueEclipse[] = "eclipse";
 const char kSwitchIdeValueQtCreator[] = "qtcreator";
 const char kSwitchIdeValueVs[] = "vs";
 const char kSwitchIdeValueVs2013[] = "vs2013";
 const char kSwitchIdeValueVs2015[] = "vs2015";
 const char kSwitchIdeValueVs2017[] = "vs2017";
 const char kSwitchIdeValueWinSdk[] = "winsdk";
 const char kSwitchIdeValueXcode[] = "xcode";
 const char kSwitchIdeValueJson[] = "json";
 const char kSwitchNinjaExtraArgs[] = "ninja-extra-args";
 const char kSwitchNoDeps[] = "no-deps";
 const char kSwitchRootTarget[] = "root-target";
 const char kSwitchSln[] = "sln";
 const char kSwitchWorkspace[] = "workspace";
 const char kSwitchJsonFileName[] = "json-file-name";
 const char kSwitchJsonIdeScript[] = "json-ide-script";
 const char kSwitchJsonIdeScriptArgs[] = "json-ide-script-args";

 // Collects Ninja rules for each toolchain. The lock protectes the rules.
 struct TargetWriteInfo {
   base::Lock lock;
   NinjaWriter::PerToolchainRules rules;
 };

 // Called on worker thread to write the ninja file.
 void BackgroundDoWrite(TargetWriteInfo* write_info, const Target* target) {
   std::string rule = NinjaTargetWriter::RunAndWriteFile(target);
   DCHECK(!rule.empty());

   {
     base::AutoLock lock(write_info->lock);
     write_info->rules[target->toolchain()].emplace_back(
         target, std::move(rule));
   }
 }

 // Called on the main thread.
 void ItemResolvedAndGeneratedCallback(TargetWriteInfo* write_info,
                                       const BuilderRecord* record) {
   const Item* item = record->item();
   const Target* target = item->AsTarget();
   if (target) {
     g_scheduler->ScheduleWork(
         base::Bind(&BackgroundDoWrite, write_info, target));
   }
 }

 // Returns a pointer to the target with the given file as an output, or null
 // if no targets generate the file. This is brute force since this is an
 // error condition and performance shouldn't matter.
 const Target* FindTargetThatGeneratesFile(const Builder& builder,
                                           const SourceFile& file) {
   std::vector<const Target*> targets = builder.GetAllResolvedTargets();
   if (targets.empty())
     return nullptr;

   OutputFile output_file(targets[0]->settings()->build_settings(), file);
   for (const Target* target : targets) {
     for (const auto& cur_output : target->computed_outputs()) {
       if (cur_output == output_file)
         return target;
     }
   }
   return nullptr;
 }

 // Prints an error that the given file was present as a source or input in
 // the given target(s) but was not generated by any of its dependencies.
 void PrintInvalidGeneratedInput(const Builder& builder,
                                 const SourceFile& file,
                                 const std::vector<const Target*>& targets) {
   std::string err;

   // Only show the toolchain labels (which can be confusing) if something
   // isn't the default.
   bool show_toolchains = false;
   const Label& default_toolchain =
       targets[0]->settings()->default_toolchain_label();
   for (const Target* target : targets) {
     if (target->settings()->toolchain_label() != default_toolchain) {
       show_toolchains = true;
       break;
     }
   }

   const Target* generator = FindTargetThatGeneratesFile(builder, file);
   if (generator &&
       generator->settings()->toolchain_label() != default_toolchain)
     show_toolchains = true;

   const std::string target_str = targets.size() > 1 ? "targets" : "target";
   err += "The file:\n";
   err += "  " + file.value() + "\n";
   err += "is listed as an input or source for the " + target_str + ":\n";
   for (const Target* target : targets)
     err += "  " + target->label().GetUserVisibleName(show_toolchains) + "\n";

   if (generator) {
     err += "but this file was not generated by any dependencies of the " +
            target_str + ". The target\nthat generates the file is:\n  ";
     err += generator->label().GetUserVisibleName(show_toolchains);
   } else {
     err += "but no targets in the build generate that file.";
   }

   Err(Location(), "Input to " + target_str + " not generated by a dependency.",
       err).PrintToStdout();
 }

 bool CheckForInvalidGeneratedInputs(Setup* setup) {
   std::multimap<SourceFile, const Target*> unknown_inputs =
       g_scheduler->GetUnknownGeneratedInputs();
   if (unknown_inputs.empty())
     return true;  // No bad files.

   int errors_found = 0;
   auto cur = unknown_inputs.begin();
   while (cur != unknown_inputs.end()) {
     errors_found++;
     auto end_of_range = unknown_inputs.upper_bound(cur->first);

     // Package the values more conveniently for printing.
     SourceFile bad_input = cur->first;
     std::vector<const Target*> targets;
     while (cur != end_of_range)
       targets.push_back((cur++)->second);

     PrintInvalidGeneratedInput(setup->builder(), bad_input, targets);
     OutputString("\n");
   }

   OutputString(
       "If you have generated inputs, there needs to be a dependency path "
       "between the\ntwo targets in addition to just listing the files. For "
       "indirect dependencies,\nthe intermediate ones must be public_deps. "
       "data_deps don't count since they're\nonly runtime dependencies. If "
       "you think a dependency chain exists, it might be\nbecause the chain "
       "is private. Try \"gn path\" to analyze.\n");

   if (errors_found > 1) {
     OutputString(base::StringPrintf("\n%d generated input errors found.\n",
                                     errors_found), DECORATION_YELLOW);
   }
   return false;
 }

 bool RunIdeWriter(const std::string& ide,
                   const BuildSettings* build_settings,
                   const Builder& builder,
                   Err* err) {
   const base::CommandLine* command_line =
       base::CommandLine::ForCurrentProcess();
   bool quiet = command_line->HasSwitch(switches::kQuiet);
   base::ElapsedTimer timer;

   if (ide == kSwitchIdeValueEclipse) {
     bool res = EclipseWriter::RunAndWriteFile(build_settings, builder, err);
     if (res && !quiet) {
       OutputString("Generating Eclipse settings took " +
                    base::Int64ToString(timer.Elapsed().InMilliseconds()) +
                    "ms\n");
     }
     return res;
   } else if (ide == kSwitchIdeValueVs || ide == kSwitchIdeValueVs2013 ||
              ide == kSwitchIdeValueVs2015 || ide == kSwitchIdeValueVs2017) {
     VisualStudioWriter::Version version = VisualStudioWriter::Version::Vs2017;
     if (ide == kSwitchIdeValueVs2013)
       version = VisualStudioWriter::Version::Vs2013;
     else if (ide == kSwitchIdeValueVs2015)
       version = VisualStudioWriter::Version::Vs2015;

     std::string sln_name;
     if (command_line->HasSwitch(kSwitchSln))
       sln_name = command_line->GetSwitchValueASCII(kSwitchSln);
     std::string filters;
     if (command_line->HasSwitch(kSwitchFilters))
       filters = command_line->GetSwitchValueASCII(kSwitchFilters);
     std::string win_kit;
     if (command_line->HasSwitch(kSwitchIdeValueWinSdk))
       win_kit = command_line->GetSwitchValueASCII(kSwitchIdeValueWinSdk);
     std::string ninja_extra_args;
     if (command_line->HasSwitch(kSwitchNinjaExtraArgs))
       ninja_extra_args =
           command_line->GetSwitchValueASCII(kSwitchNinjaExtraArgs);
     bool no_deps = command_line->HasSwitch(kSwitchNoDeps);
     bool res = VisualStudioWriter::RunAndWriteFiles(
         build_settings, builder, version, sln_name, filters, win_kit,
         ninja_extra_args, no_deps, err);
     if (res && !quiet) {
       OutputString("Generating Visual Studio projects took " +
                    base::Int64ToString(timer.Elapsed().InMilliseconds()) +
                    "ms\n");
     }
     return res;
   } else if (ide == kSwitchIdeValueXcode) {
     bool res = XcodeWriter::RunAndWriteFiles(
         command_line->GetSwitchValueASCII(kSwitchWorkspace),
         command_line->GetSwitchValueASCII(kSwitchRootTarget),
         command_line->GetSwitchValueASCII(kSwitchNinjaExtraArgs),
         command_line->GetSwitchValueASCII(kSwitchFilters), build_settings,
         builder, err);
     if (res && !quiet) {
       OutputString("Generating Xcode projects took " +
                    base::Int64ToString(timer.Elapsed().InMilliseconds()) +
                    "ms\n");
     }
     return res;
   } else if (ide == kSwitchIdeValueQtCreator) {
     std::string root_target;
     if (command_line->HasSwitch(kSwitchRootTarget))
       root_target = command_line->GetSwitchValueASCII(kSwitchRootTarget);
     bool res = QtCreatorWriter::RunAndWriteFile(build_settings, builder, err,
                                                 root_target);
     if (res && !quiet) {
       OutputString("Generating QtCreator projects took " +
                    base::Int64ToString(timer.Elapsed().InMilliseconds()) +
                    "ms\n");
     }
     return res;
   } else if (ide == kSwitchIdeValueJson) {
     std::string file_name =
         command_line->GetSwitchValueASCII(kSwitchJsonFileName);
     if (file_name.empty())
       file_name = "project.json";
     std::string exec_script =
         command_line->GetSwitchValueASCII(kSwitchJsonIdeScript);
     std::string exec_script_extra_args =
         command_line->GetSwitchValueASCII(kSwitchJsonIdeScriptArgs);
     std::string filters = command_line->GetSwitchValueASCII(kSwitchFilters);

     bool res = JSONProjectWriter::RunAndWriteFiles(
         build_settings, builder, file_name, exec_script, exec_script_extra_args,
         filters, quiet, err);
     if (res && !quiet) {
       OutputString("Generating JSON projects took " +
                    base::Int64ToString(timer.Elapsed().InMilliseconds()) +
                    "ms\n");
     }
     return res;
   }

   *err = Err(Location(), "Unknown IDE: " + ide);
   return false;
 }

 }  // namespace

 const char kGen[] = "gen";
 const char kGen_HelpShort[] = "gen: Generate ninja files.";
 const char kGen_Help[] =
     R"(gn gen [--check] [<ide options>] <out_dir>

   Generates ninja files from the current tree and puts them in the given output
   directory.

   The output directory can be a source-repo-absolute path name such as:
       //out/foo
   Or it can be a directory relative to the current directory such as:
       out/foo

   "gn gen --check" is the same as running "gn check". See "gn help check"
   for documentation on that mode.

   See "gn help switches" for the common command-line switches.

 IDE options

   GN optionally generates files for IDE. Possibilities for <ide options>

   --ide=<ide_name>
       Generate files for an IDE. Currently supported values:
       "eclipse" - Eclipse CDT settings file.
       "vs" - Visual Studio project/solution files.
              (default Visual Studio version: 2017)
       "vs2013" - Visual Studio 2013 project/solution files.
       "vs2015" - Visual Studio 2015 project/solution files.
       "vs2017" - Visual Studio 2017 project/solution files.
       "xcode" - Xcode workspace/solution files.
       "qtcreator" - QtCreator project files.
       "json" - JSON file containing target information

   --filters=<path_prefixes>
       Semicolon-separated list of label patterns used to limit the set of
       generated projects (see "gn help label_pattern"). Only matching targets
       and their dependencies will be included in the solution. Only used for
       Visual Studio, Xcode and JSON.

 Visual Studio Flags

   --sln=<file_name>
       Override default sln file name ("all"). Solution file is written to the
       root build directory.

   --no-deps
       Don't include targets dependencies to the solution. Changes the way how
       --filters option works. Only directly matching targets are included.

   --winsdk=<sdk_version>
       Use the specified Windows 10 SDK version to generate project files.
       As an example, "10.0.15063.0" can be specified to use Creators Update SDK
       instead of the default one.

   --ninja-extra-args=<string>
       This string is passed without any quoting to the ninja invocation
       command-line. Can be used to configure ninja flags, like "-j".

 Xcode Flags

   --workspace=<file_name>
       Override defaut workspace file name ("all"). The workspace file is
       written to the root build directory.

   --ninja-extra-args=<string>
       This string is passed without any quoting to the ninja invocation
       command-line. Can be used to configure ninja flags, like "-j".

   --root-target=<target_name>
       Name of the target corresponding to "All" target in Xcode. If unset,
       "All" invokes ninja without any target and builds everything.

 QtCreator Flags

   --root-target=<target_name>
       Name of the root target for which the QtCreator project will be generated
       to contain files of it and its dependencies. If unset, the whole build
       graph will be emitted.


 Eclipse IDE Support

   GN DOES NOT generate Eclipse CDT projects. Instead, it generates a settings
   file which can be imported into an Eclipse CDT project. The XML file contains
   a list of include paths and defines. Because GN does not generate a full
   .cproject definition, it is not possible to properly define includes/defines
   for each file individually. Instead, one set of includes/defines is generated
   for the entire project. This works fairly well but may still result in a few
   indexer issues here and there.

 Generic JSON Output

   Dumps target information to a JSON file and optionally invokes a
   python script on the generated file. See the comments at the beginning
   of json_project_writer.cc and desc_builder.cc for an overview of the JSON
   file format.

   --json-file-name=<json_file_name>
       Overrides default file name (project.json) of generated JSON file.

   --json-ide-script=<path_to_python_script>
       Executes python script after the JSON file is generated. Path can be
       project absolute (//), system absolute (/) or relative, in which case the
       output directory will be base. Path to generated JSON file will be first
       argument when invoking script.

   --json-ide-script-args=<argument>
       Optional second argument that will passed to executed script.
 )";

 int RunGen(const std::vector<std::string>& args) {
   base::ElapsedTimer timer;

   if (args.size() != 1) {
     Err(Location(), "Need exactly one build directory to generate.",
         "I expected something more like \"gn gen out/foo\"\n"
         "You can also see \"gn help gen\".").PrintToStdout();
     return 1;
   }

   // Deliberately leaked to avoid expensive process teardown.
   Setup* setup = new Setup();
   if (!setup->DoSetup(args[0], true))
     return 1;

   const base::CommandLine* command_line =
       base::CommandLine::ForCurrentProcess();
   if (command_line->HasSwitch(kSwitchCheck))
     setup->set_check_public_headers(true);

   // Cause the load to also generate the ninja files for each target.
   TargetWriteInfo write_info;
   setup->builder().set_resolved_and_generated_callback(
       base::Bind(&ItemResolvedAndGeneratedCallback, &write_info));

   // Do the actual load. This will also write out the target ninja files.
   if (!setup->Run())
     return 1;

   // Sort the targets in each toolchain according to their label. This makes
   // the ninja files have deterministic content.
   for (auto& cur_toolchain : write_info.rules) {
     std::sort(cur_toolchain.second.begin(), cur_toolchain.second.end(),
               [](const NinjaWriter::TargetRulePair& a,
                  const NinjaWriter::TargetRulePair& b) {
                 return a.first->label() < b.first->label();
               });
   }

   Err err;
   // Write the root ninja files.
   if (!NinjaWriter::RunAndWriteFiles(&setup->build_settings(),
                                      setup->builder(),
                                      write_info.rules,
                                      &err)) {
     err.PrintToStdout();
     return 1;
   }

   if (!WriteRuntimeDepsFilesIfNecessary(setup->builder(), &err)) {
     err.PrintToStdout();
     return 1;
   }

   if (!CheckForInvalidGeneratedInputs(setup))
     return 1;

   if (command_line->HasSwitch(kSwitchIde) &&
       !RunIdeWriter(command_line->GetSwitchValueASCII(kSwitchIde),
                     &setup->build_settings(), setup->builder(), &err)) {
     err.PrintToStdout();
     return 1;
   }

   base::TimeDelta elapsed_time = timer.Elapsed();

   if (!command_line->HasSwitch(switches::kQuiet)) {
     OutputString("Done. ", DECORATION_GREEN);

     size_t targets_collected = 0;
     for (const auto& rules : write_info.rules)
       targets_collected += rules.second.size();

     std::string stats =
         "Made " + base::NumberToString(targets_collected) + " targets from " +
         base::IntToString(
             setup->scheduler().input_file_manager()->GetInputFileCount()) +
         " files in " + base::Int64ToString(elapsed_time.InMilliseconds()) +
         "ms\n";
     OutputString(stats);
   }

   return 0;
 }

 }  // namespace commands
	// 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 "base/bind.h"
	#include "base/command_line.h"
	#include "base/strings/string_number_conversions.h"
	#include "base/strings/stringprintf.h"
	#include "base/timer/elapsed_timer.h"
	#include "tools/gn/build_settings.h"
	#include "tools/gn/commands.h"
	#include "tools/gn/eclipse_writer.h"
	#include "tools/gn/json_project_writer.h"
	#include "tools/gn/ninja_target_writer.h"
	#include "tools/gn/ninja_writer.h"
	#include "tools/gn/qt_creator_writer.h"
	#include "tools/gn/runtime_deps.h"
	#include "tools/gn/scheduler.h"
	#include "tools/gn/setup.h"
	#include "tools/gn/standard_out.h"
	#include "tools/gn/switches.h"
	#include "tools/gn/target.h"
	#include "tools/gn/visual_studio_writer.h"
	#include "tools/gn/xcode_writer.h"

	namespace commands {

	namespace {

	const char kSwitchCheck[] = "check";
	const char kSwitchFilters[] = "filters";
	const char kSwitchIde[] = "ide";
	const char kSwitchIdeValueEclipse[] = "eclipse";
	const char kSwitchIdeValueQtCreator[] = "qtcreator";
	const char kSwitchIdeValueVs[] = "vs";
	const char kSwitchIdeValueVs2013[] = "vs2013";
	const char kSwitchIdeValueVs2015[] = "vs2015";
	const char kSwitchIdeValueVs2017[] = "vs2017";
	const char kSwitchIdeValueWinSdk[] = "winsdk";
	const char kSwitchIdeValueXcode[] = "xcode";
	const char kSwitchIdeValueJson[] = "json";
	const char kSwitchNinjaExtraArgs[] = "ninja-extra-args";
	const char kSwitchNoDeps[] = "no-deps";
	const char kSwitchRootTarget[] = "root-target";
	const char kSwitchSln[] = "sln";
	const char kSwitchWorkspace[] = "workspace";
	const char kSwitchJsonFileName[] = "json-file-name";
	const char kSwitchJsonIdeScript[] = "json-ide-script";
	const char kSwitchJsonIdeScriptArgs[] = "json-ide-script-args";

	// Collects Ninja rules for each toolchain. The lock protectes the rules.
	struct TargetWriteInfo {
	base::Lock lock;
	NinjaWriter::PerToolchainRules rules;
	};

	// Called on worker thread to write the ninja file.
	void BackgroundDoWrite(TargetWriteInfo* write_info, const Target* target) {
	std::string rule = NinjaTargetWriter::RunAndWriteFile(target);
	DCHECK(!rule.empty());

	{
	base::AutoLock lock(write_info->lock);
	write_info->rules[target->toolchain()].emplace_back(
	target, std::move(rule));
	}
	}

	// Called on the main thread.
	void ItemResolvedAndGeneratedCallback(TargetWriteInfo* write_info,
	const BuilderRecord* record) {
	const Item* item = record->item();
	const Target* target = item->AsTarget();
	if (target) {
	g_scheduler->ScheduleWork(
	base::Bind(&BackgroundDoWrite, write_info, target));
	}
	}

	// Returns a pointer to the target with the given file as an output, or null
	// if no targets generate the file. This is brute force since this is an
	// error condition and performance shouldn't matter.
	const Target* FindTargetThatGeneratesFile(const Builder& builder,
	const SourceFile& file) {
	std::vector<const Target*> targets = builder.GetAllResolvedTargets();
	if (targets.empty())
	return nullptr;

	OutputFile output_file(targets[0]->settings()->build_settings(), file);
	for (const Target* target : targets) {
	for (const auto& cur_output : target->computed_outputs()) {
	if (cur_output == output_file)
	return target;
	}
	}
	return nullptr;
	}

	// Prints an error that the given file was present as a source or input in
	// the given target(s) but was not generated by any of its dependencies.
	void PrintInvalidGeneratedInput(const Builder& builder,
	const SourceFile& file,
	const std::vector<const Target*>& targets) {
	std::string err;

	// Only show the toolchain labels (which can be confusing) if something
	// isn't the default.
	bool show_toolchains = false;
	const Label& default_toolchain =
	targets[0]->settings()->default_toolchain_label();
	for (const Target* target : targets) {
	if (target->settings()->toolchain_label() != default_toolchain) {
	show_toolchains = true;
	break;
	}
	}

	const Target* generator = FindTargetThatGeneratesFile(builder, file);
	if (generator &&
	generator->settings()->toolchain_label() != default_toolchain)
	show_toolchains = true;

	const std::string target_str = targets.size() > 1 ? "targets" : "target";
	err += "The file:\n";
	err += " " + file.value() + "\n";
	err += "is listed as an input or source for the " + target_str + ":\n";
	for (const Target* target : targets)
	err += " " + target->label().GetUserVisibleName(show_toolchains) + "\n";

	if (generator) {
	err += "but this file was not generated by any dependencies of the " +
	target_str + ". The target\nthat generates the file is:\n ";
	err += generator->label().GetUserVisibleName(show_toolchains);
	} else {
	err += "but no targets in the build generate that file.";
	}

	Err(Location(), "Input to " + target_str + " not generated by a dependency.",
	err).PrintToStdout();
	}

	bool CheckForInvalidGeneratedInputs(Setup* setup) {
	std::multimap<SourceFile, const Target*> unknown_inputs =
	g_scheduler->GetUnknownGeneratedInputs();
	if (unknown_inputs.empty())
	return true; // No bad files.

	int errors_found = 0;
	auto cur = unknown_inputs.begin();
	while (cur != unknown_inputs.end()) {
	errors_found++;
	auto end_of_range = unknown_inputs.upper_bound(cur->first);

	// Package the values more conveniently for printing.
	SourceFile bad_input = cur->first;
	std::vector<const Target*> targets;
	while (cur != end_of_range)
	targets.push_back((cur++)->second);

	PrintInvalidGeneratedInput(setup->builder(), bad_input, targets);
	OutputString("\n");
	}

	OutputString(
	"If you have generated inputs, there needs to be a dependency path "
	"between the\ntwo targets in addition to just listing the files. For "
	"indirect dependencies,\nthe intermediate ones must be public_deps. "
	"data_deps don't count since they're\nonly runtime dependencies. If "
	"you think a dependency chain exists, it might be\nbecause the chain "
	"is private. Try \"gn path\" to analyze.\n");

	if (errors_found > 1) {
	OutputString(base::StringPrintf("\n%d generated input errors found.\n",
	errors_found), DECORATION_YELLOW);
	}
	return false;
	}

	bool RunIdeWriter(const std::string& ide,
	const BuildSettings* build_settings,
	const Builder& builder,
	Err* err) {
	const base::CommandLine* command_line =
	base::CommandLine::ForCurrentProcess();
	bool quiet = command_line->HasSwitch(switches::kQuiet);
	base::ElapsedTimer timer;

	if (ide == kSwitchIdeValueEclipse) {
	bool res = EclipseWriter::RunAndWriteFile(build_settings, builder, err);
	if (res && !quiet) {
	OutputString("Generating Eclipse settings took " +
	base::Int64ToString(timer.Elapsed().InMilliseconds()) +
	"ms\n");
	}
	return res;
	} else if (ide == kSwitchIdeValueVs \|\| ide == kSwitchIdeValueVs2013 \|\|
	ide == kSwitchIdeValueVs2015 \|\| ide == kSwitchIdeValueVs2017) {
	VisualStudioWriter::Version version = VisualStudioWriter::Version::Vs2017;
	if (ide == kSwitchIdeValueVs2013)
	version = VisualStudioWriter::Version::Vs2013;
	else if (ide == kSwitchIdeValueVs2015)
	version = VisualStudioWriter::Version::Vs2015;

	std::string sln_name;
	if (command_line->HasSwitch(kSwitchSln))
	sln_name = command_line->GetSwitchValueASCII(kSwitchSln);
	std::string filters;
	if (command_line->HasSwitch(kSwitchFilters))
	filters = command_line->GetSwitchValueASCII(kSwitchFilters);
	std::string win_kit;
	if (command_line->HasSwitch(kSwitchIdeValueWinSdk))
	win_kit = command_line->GetSwitchValueASCII(kSwitchIdeValueWinSdk);
	std::string ninja_extra_args;
	if (command_line->HasSwitch(kSwitchNinjaExtraArgs))
	ninja_extra_args =
	command_line->GetSwitchValueASCII(kSwitchNinjaExtraArgs);
	bool no_deps = command_line->HasSwitch(kSwitchNoDeps);
	bool res = VisualStudioWriter::RunAndWriteFiles(
	build_settings, builder, version, sln_name, filters, win_kit,
	ninja_extra_args, no_deps, err);
	if (res && !quiet) {
	OutputString("Generating Visual Studio projects took " +
	base::Int64ToString(timer.Elapsed().InMilliseconds()) +
	"ms\n");
	}
	return res;
	} else if (ide == kSwitchIdeValueXcode) {
	bool res = XcodeWriter::RunAndWriteFiles(
	command_line->GetSwitchValueASCII(kSwitchWorkspace),
	command_line->GetSwitchValueASCII(kSwitchRootTarget),
	command_line->GetSwitchValueASCII(kSwitchNinjaExtraArgs),
	command_line->GetSwitchValueASCII(kSwitchFilters), build_settings,
	builder, err);
	if (res && !quiet) {
	OutputString("Generating Xcode projects took " +
	base::Int64ToString(timer.Elapsed().InMilliseconds()) +
	"ms\n");
	}
	return res;
	} else if (ide == kSwitchIdeValueQtCreator) {
	std::string root_target;
	if (command_line->HasSwitch(kSwitchRootTarget))
	root_target = command_line->GetSwitchValueASCII(kSwitchRootTarget);
	bool res = QtCreatorWriter::RunAndWriteFile(build_settings, builder, err,
	root_target);
	if (res && !quiet) {
	OutputString("Generating QtCreator projects took " +
	base::Int64ToString(timer.Elapsed().InMilliseconds()) +
	"ms\n");
	}
	return res;
	} else if (ide == kSwitchIdeValueJson) {
	std::string file_name =
	command_line->GetSwitchValueASCII(kSwitchJsonFileName);
	if (file_name.empty())
	file_name = "project.json";
	std::string exec_script =
	command_line->GetSwitchValueASCII(kSwitchJsonIdeScript);
	std::string exec_script_extra_args =
	command_line->GetSwitchValueASCII(kSwitchJsonIdeScriptArgs);
	std::string filters = command_line->GetSwitchValueASCII(kSwitchFilters);

	bool res = JSONProjectWriter::RunAndWriteFiles(
	build_settings, builder, file_name, exec_script, exec_script_extra_args,
	filters, quiet, err);
	if (res && !quiet) {
	OutputString("Generating JSON projects took " +
	base::Int64ToString(timer.Elapsed().InMilliseconds()) +
	"ms\n");
	}
	return res;
	}

	*err = Err(Location(), "Unknown IDE: " + ide);
	return false;
	}

	} // namespace

	const char kGen[] = "gen";
	const char kGen_HelpShort[] = "gen: Generate ninja files.";
	const char kGen_Help[] =
	R"(gn gen [--check] [<ide options>] <out_dir>

	Generates ninja files from the current tree and puts them in the given output
	directory.

	The output directory can be a source-repo-absolute path name such as:
	//out/foo
	Or it can be a directory relative to the current directory such as:
	out/foo

	"gn gen --check" is the same as running "gn check". See "gn help check"
	for documentation on that mode.

	See "gn help switches" for the common command-line switches.

	IDE options

	GN optionally generates files for IDE. Possibilities for <ide options>

	--ide=<ide_name>
	Generate files for an IDE. Currently supported values:
	"eclipse" - Eclipse CDT settings file.
	"vs" - Visual Studio project/solution files.
	(default Visual Studio version: 2017)
	"vs2013" - Visual Studio 2013 project/solution files.
	"vs2015" - Visual Studio 2015 project/solution files.
	"vs2017" - Visual Studio 2017 project/solution files.
	"xcode" - Xcode workspace/solution files.
	"qtcreator" - QtCreator project files.
	"json" - JSON file containing target information

	--filters=<path_prefixes>
	Semicolon-separated list of label patterns used to limit the set of
	generated projects (see "gn help label_pattern"). Only matching targets
	and their dependencies will be included in the solution. Only used for
	Visual Studio, Xcode and JSON.

	Visual Studio Flags

	--sln=<file_name>
	Override default sln file name ("all"). Solution file is written to the
	root build directory.

	--no-deps
	Don't include targets dependencies to the solution. Changes the way how
	--filters option works. Only directly matching targets are included.

	--winsdk=<sdk_version>
	Use the specified Windows 10 SDK version to generate project files.
	As an example, "10.0.15063.0" can be specified to use Creators Update SDK
	instead of the default one.

	--ninja-extra-args=<string>
	This string is passed without any quoting to the ninja invocation
	command-line. Can be used to configure ninja flags, like "-j".

	Xcode Flags

	--workspace=<file_name>
	Override defaut workspace file name ("all"). The workspace file is
	written to the root build directory.

	--ninja-extra-args=<string>
	This string is passed without any quoting to the ninja invocation
	command-line. Can be used to configure ninja flags, like "-j".

	--root-target=<target_name>
	Name of the target corresponding to "All" target in Xcode. If unset,
	"All" invokes ninja without any target and builds everything.

	QtCreator Flags

	--root-target=<target_name>
	Name of the root target for which the QtCreator project will be generated
	to contain files of it and its dependencies. If unset, the whole build
	graph will be emitted.


	Eclipse IDE Support

	GN DOES NOT generate Eclipse CDT projects. Instead, it generates a settings
	file which can be imported into an Eclipse CDT project. The XML file contains
	a list of include paths and defines. Because GN does not generate a full
	.cproject definition, it is not possible to properly define includes/defines
	for each file individually. Instead, one set of includes/defines is generated
	for the entire project. This works fairly well but may still result in a few
	indexer issues here and there.

	Generic JSON Output

	Dumps target information to a JSON file and optionally invokes a
	python script on the generated file. See the comments at the beginning
	of json_project_writer.cc and desc_builder.cc for an overview of the JSON
	file format.

	--json-file-name=<json_file_name>
	Overrides default file name (project.json) of generated JSON file.

	--json-ide-script=<path_to_python_script>
	Executes python script after the JSON file is generated. Path can be
	project absolute (//), system absolute (/) or relative, in which case the
	output directory will be base. Path to generated JSON file will be first
	argument when invoking script.

	--json-ide-script-args=<argument>
	Optional second argument that will passed to executed script.
	)";

	int RunGen(const std::vector<std::string>& args) {
	base::ElapsedTimer timer;

	if (args.size() != 1) {
	Err(Location(), "Need exactly one build directory to generate.",
	"I expected something more like \"gn gen out/foo\"\n"
	"You can also see \"gn help gen\".").PrintToStdout();
	return 1;
	}

	// Deliberately leaked to avoid expensive process teardown.
	Setup* setup = new Setup();
	if (!setup->DoSetup(args[0], true))
	return 1;

	const base::CommandLine* command_line =
	base::CommandLine::ForCurrentProcess();
	if (command_line->HasSwitch(kSwitchCheck))
	setup->set_check_public_headers(true);

	// Cause the load to also generate the ninja files for each target.
	TargetWriteInfo write_info;
	setup->builder().set_resolved_and_generated_callback(
	base::Bind(&ItemResolvedAndGeneratedCallback, &write_info));

	// Do the actual load. This will also write out the target ninja files.
	if (!setup->Run())
	return 1;

	// Sort the targets in each toolchain according to their label. This makes
	// the ninja files have deterministic content.
	for (auto& cur_toolchain : write_info.rules) {
	std::sort(cur_toolchain.second.begin(), cur_toolchain.second.end(),
	[](const NinjaWriter::TargetRulePair& a,
	const NinjaWriter::TargetRulePair& b) {
	return a.first->label() < b.first->label();
	});
	}

	Err err;
	// Write the root ninja files.
	if (!NinjaWriter::RunAndWriteFiles(&setup->build_settings(),
	setup->builder(),
	write_info.rules,
	&err)) {
	err.PrintToStdout();
	return 1;
	}

	if (!WriteRuntimeDepsFilesIfNecessary(setup->builder(), &err)) {
	err.PrintToStdout();
	return 1;
	}

	if (!CheckForInvalidGeneratedInputs(setup))
	return 1;

	if (command_line->HasSwitch(kSwitchIde) &&
	!RunIdeWriter(command_line->GetSwitchValueASCII(kSwitchIde),
	&setup->build_settings(), setup->builder(), &err)) {
	err.PrintToStdout();
	return 1;
	}

	base::TimeDelta elapsed_time = timer.Elapsed();

	if (!command_line->HasSwitch(switches::kQuiet)) {
	OutputString("Done. ", DECORATION_GREEN);

	size_t targets_collected = 0;
	for (const auto& rules : write_info.rules)
	targets_collected += rules.second.size();

	std::string stats =
	"Made " + base::NumberToString(targets_collected) + " targets from " +
	base::IntToString(
	setup->scheduler().input_file_manager()->GetInputFileCount()) +
	" files in " + base::Int64ToString(elapsed_time.InMilliseconds()) +
	"ms\n";
	OutputString(stats);
	}

	return 0;
	}

	} // namespace commands