Visual Studio generators for GN

tools/gn/visual_studio_writer.cc

Index: tools/gn/visual_studio_writer.cc
diff --git a/tools/gn/visual_studio_writer.cc b/tools/gn/visual_studio_writer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f2838531b6686759d4fc408edbe3b84149194d4d
--- /dev/null
+++ b/tools/gn/visual_studio_writer.cc
@@ -0,0 +1,603 @@
+// Copyright (c) 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 "tools/gn/visual_studio_writer.h"
+
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <utility>
+
+#include "base/logging.h"
+#include "base/md5.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/strings/string_util.h"
+#include "tools/gn/builder.h"
+#include "tools/gn/config.h"
+#include "tools/gn/config_values_extractors.h"
+#include "tools/gn/filesystem_utils.h"
+#include "tools/gn/parse_tree.h"
+#include "tools/gn/path_output.h"
+#include "tools/gn/source_file_type.h"
+#include "tools/gn/target.h"
+#include "tools/gn/variables.h"
+
+struct ProjectConfiguration {
+  bool is_debug;
+  std::string platform;
+};
+
+namespace {
+
+using XmlAttributes = std::vector<std::pair<std::string, std::string>>;
+
+class XmlElement {

[brettw, 2016/01/08 23:51:50]

I feel like this should be XMLElementOuptut or XMLElementWriter or something to
make it clear that this is something that writes XML to files rather than
representing some DOM node.

[Tomasz Moniuszko, 2016/01/21 10:50:02]

Done.

+ public:
+  XmlElement(std::ostream& out,
+             const std::string& tag,
+             const XmlAttributes& attributes);
+  XmlElement(std::ostream& out,
+             const std::string& tag,
+             const XmlAttributes& attributes,
+             int indent);
+  template <class Writer>
+  XmlElement(std::ostream& out,
+             const std::string& tag,
+             const std::string& attribute_name,
+             const Writer& attribute_value_writer,
+             int indent);
+  ~XmlElement();
+
+  void Text(const std::string& content);
+
+  scoped_ptr<XmlElement> SubElement(const std::string& tag);
+  scoped_ptr<XmlElement> SubElement(const std::string& tag,
+                                    const XmlAttributes& attributes);
+  template <class Writer>
+  scoped_ptr<XmlElement> SubElement(const std::string& tag,
+                                    const std::string& attribute_name,
+                                    const Writer& attribute_value_writer);
+
+ private:
+  std::ostream& out_;
+  std::string tag_;
+  int indent_;
+  bool one_line_;
+
+  DISALLOW_COPY_AND_ASSIGN(XmlElement);
+};
+
+XmlElement::XmlElement(std::ostream& out,
+                       const std::string& tag,
+                       const XmlAttributes& attributes)
+    : XmlElement(out, tag, attributes, 0) {}
+
+XmlElement::XmlElement(std::ostream& out,
+                       const std::string& tag,
+                       const XmlAttributes& attributes,
+                       int indent)
+    : out_(out), tag_(tag), indent_(indent), one_line_(true) {
+  out << std::string(indent, ' ') << '<' << tag;
+  for (auto attribute : attributes) {

[brettw, 2016/01/08 23:51:50]

I haven't been using {} for single-line stuff like this in GN.

[Tomasz Moniuszko, 2016/01/21 10:50:03]

Done.

+    out << ' ' << attribute.first << "=\"" << attribute.second << '"';
+  }
+  out << '>';
+}
+
+template <class Writer>
+XmlElement::XmlElement(std::ostream& out,
+                       const std::string& tag,
+                       const std::string& attribute_name,
+                       const Writer& attribute_value_writer,
+                       int indent)
+    : out_(out), tag_(tag), indent_(indent), one_line_(true) {
+  out << std::string(indent, ' ') << '<' << tag;
+  out << ' ' << attribute_name << "=\"";
+  attribute_value_writer(out);
+  out << "\">";
+}
+
+XmlElement::~XmlElement() {
+  if (!one_line_)
+    out_ << std::string(indent_, ' ');
+  out_ << "</" << tag_ << '>' << std::endl;
+}
+
+void XmlElement::Text(const std::string& content) {
+  out_ << content;
+}
+
+scoped_ptr<XmlElement> XmlElement::SubElement(const std::string& tag) {
+  return SubElement(tag, XmlAttributes());
+}
+
+scoped_ptr<XmlElement> XmlElement::SubElement(const std::string& tag,
+                                              const XmlAttributes& attributes) {
+  if (one_line_) {
+    out_ << std::endl;
+    one_line_ = false;
+  }
+  return make_scoped_ptr(new XmlElement(out_, tag, attributes, indent_ + 2));
+}
+
+template <class Writer>
+scoped_ptr<XmlElement> XmlElement::SubElement(
+    const std::string& tag,
+    const std::string& attribute_name,
+    const Writer& attribute_value_writer) {
+  if (one_line_) {
+    out_ << std::endl;
+    one_line_ = false;
+  }
+  return make_scoped_ptr(new XmlElement(out_, tag, attribute_name,
+                                        attribute_value_writer, indent_ + 2));
+}
+
+struct SemicolonSeparatedWriter {
+  void operator()(const std::string& value, std::ostream& out) const {
+    out << value + ';';
+  }
+};
+
+struct IncludeDirWriter {
+  explicit IncludeDirWriter(PathOutput& path_output)
+      : path_output_(path_output) {}
+  ~IncludeDirWriter() = default;
+
+  void operator()(const SourceDir& dir, std::ostream& out) const {
+    path_output_.WriteDir(out, dir, PathOutput::DIR_NO_LAST_SLASH);
+    out << ";";
+  }
+
+  PathOutput& path_output_;
+};
+
+struct SourceFileWriter {
+  SourceFileWriter(PathOutput& path_output, const SourceFile& source_file)
+      : path_output_(path_output), source_file_(source_file) {}
+  ~SourceFileWriter() = default;
+
+  void operator()(std::ostream& out) const {
+    path_output_.WriteFile(out, source_file_);
+  }
+
+  PathOutput& path_output_;
+  const SourceFile& source_file_;
+};
+
+// Some compiler options which will be written to project file. We don't need to
+// specify all options because generated project file is going to be used only
+// for compilation of single file. For real build ninja files are used.
+struct CompilerOptions {
+  std::string additional_options;
+  std::string buffer_security_check;
+  std::string forced_include_files;
+  std::string disable_specific_warnings;
+  std::string optimization;
+  std::string runtime_library;
+  std::string treat_warning_as_error;
+  std::string warning_level;
+};
+
+const char kToolsetVersion[] = "v140";                     // Visual Studio 2015
+const char kVisualStudioVersion[] = "14.0";                // Visual Studio 2015
+const char kWindowsKitsVersion[] = "10";                   // Windows 10 SDK
+const char kWindowsKitsIncludeVersion[] = "10.0.10240.0";  // Windows 10 SDK
+
+std::string GetWindowsKitsIncludeDirs() {
+  // TODO(tmoniuszko): This should be taken from GN args or system environment.

[brettw, 2016/01/08 23:51:50]

I think we should be able to extract these from the include_dirs for a target. I
bet there's a simple pattern we can use to find them.

[Tomasz Moniuszko, 2016/01/21 10:50:03]

It's not available in include_dirs. In GYP build it's added by generator. I
think we have to do the same.

+  std::string kits_path =
+      std::string("C:\\Program Files (x86)\\Windows Kits\\") +
+      kWindowsKitsVersion + "\\";
+  return kits_path + "Include\\" + kWindowsKitsIncludeVersion + "\\shared;" +
+         kits_path + "Include\\" + kWindowsKitsIncludeVersion + "\\um;" +
+         kits_path + "Include\\" + kWindowsKitsIncludeVersion + "\\winrt;";
+}
+
+std::string MakeProjectGuid(std::string target_name) {
+  std::string str = base::MD5String(target_name);
+  return '{' + str.substr(0, 8) + '-' + str.substr(8, 4) + '-' +
+         str.substr(12, 4) + '-' + str.substr(16, 4) + '-' +
+         str.substr(20, 12) + '}';
+}
+
+std::string GetConfigurationType(const Target* target, Err* err) {
+  switch (target->output_type()) {
+    case Target::EXECUTABLE:
+      return "Application";
+    case Target::SHARED_LIBRARY:
+    case Target::LOADABLE_MODULE:
+      return "DynamicLibrary";
+    case Target::STATIC_LIBRARY:
+    case Target::SOURCE_SET:
+      return "StaticLibrary";
+  }
+
+  *err = Err(Location(),
+             "Visual Studio doesn't support '" + target->label().name() +
+                 "' target output type: " +
+                 Target::GetStringForOutputType(target->output_type()));
+  return "";

[brettw, 2016/01/08 23:51:50]

return std::string();
instead. More semantically correct and the current one actually constructs a
string with a constant which is less efficient than just zero-initializing
everything.

[Tomasz Moniuszko, 2016/01/21 10:50:03]

Done.

+}
+
+#define SetOption(condition, member, value) \
+  if (condition) {                          \
+    options->member = value;                \
+    return;                                 \
+  }
+
+#define AppendOption(condition, member, value, separator) \
+  if (condition) {                                        \
+    options->member += value + separator;                 \
+    return;                                               \
+  }
+
+void ParseCompilerOption(const std::string& cflag, CompilerOptions* options) {

[brettw, 2016/01/08 23:51:50]

You can do this in a follow-up, but I would suggest separating out the visual
studio information extraction (this stuff and the include directory finding)
into a separate source file, and we should also get some good unit tests for the
functions there.

[brettw, 2016/01/08 23:51:50]

Just checking that we really need to do this. I might have hoped that specifying
the flags in "other options" would be sufficient for it to work.

[Tomasz Moniuszko, 2016/01/21 10:50:02]

It doesn't work properly because project properties are set to default values
but different values are set in "Additional Options". I'm not sure what values
are passed to intellisense in this case. Also I'm getting warnings while trying
to compile:
1>cl : Command line warning D9025: overriding '/W1' with '/W4'
1>     1>
1>cl : Command line warning D9025: overriding '/WX-' with '/WX'
1>     1>
1>cl : Command line warning D9025: overriding '/O2' with '/Od'
1>     1>
1>cl : Command line warning D9025: overriding '/MD' with '/MDd'

+  if (cflag.size() > 2 && cflag[0] == '/') {
+    switch (cflag[1]) {
+      case 'F':
+        AppendOption(cflag.size() > 3 && cflag[2] == 'I', forced_include_files,
+                     cflag.substr(3), ';')
+        break;
+
+      case 'G':
+        if (cflag[2] == 'S') {
+          SetOption(cflag.size() == 3, buffer_security_check, "true")
+          SetOption(cflag.size() == 4 && cflag[3] == '-', buffer_security_check,
+                    "false")
+        }
+        break;
+
+      case 'M':
+        switch (cflag[2]) {
+          case 'D':
+            SetOption(cflag.size() == 3, runtime_library, "MultiThreadedDLL")
+            SetOption(cflag.size() == 4 && cflag[3] == 'd', runtime_library,
+                      "MultiThreadedDebugDLL")
+            break;
+
+          case 'T':
+            SetOption(cflag.size() == 3, runtime_library, "MultiThreaded")
+            SetOption(cflag.size() == 4 && cflag[3] == 'd', runtime_library,
+                      "MultiThreadedDebug")
+            break;
+        }
+        break;
+
+      case 'O':
+        switch (cflag[2]) {
+          case '2':
+            SetOption(cflag.size() == 3, optimization, "MaxSpeed")
+            break;
+
+          case 'd':
+            SetOption(cflag.size() == 3, optimization, "Disabled")
+            break;
+        }
+        break;
+
+      case 'T':
+        // Skip flags that cause treating all source files as C and C++ files.
+        if (cflag.size() == 3 && (cflag[2] == 'C' || cflag[2] == 'P'))
+          return;
+        break;
+
+      case 'W':
+        switch (cflag[2]) {
+          case '0':
+          case '1':
+          case '2':
+          case '3':
+          case '4':
+            SetOption(cflag.size() == 3, warning_level,
+                      std::string("Level") + cflag[2])
+            break;
+
+          case 'X':
+            SetOption(cflag.size() == 3, treat_warning_as_error, "true")
+            break;
+        }
+        break;
+
+       case 'w':
+         AppendOption(cflag.size() > 3 && cflag[2] == 'd',
+                      disable_specific_warnings, cflag.substr(3), ';')
+         break;
+    }
+  }
+
+  // Put everything else into additional_options.
+  options->additional_options += cflag + ' ';
+}
+
+#undef SetOption
+#undef AppendOption
+
+void ParseCompilerOptions(const std::vector<std::string>& cflags,
+                          CompilerOptions* options) {
+  for (const std::string& flag : cflags) {

[brettw, 2016/01/08 23:51:50]

No {}

[Tomasz Moniuszko, 2016/01/21 10:50:03]

Done.

+    ParseCompilerOption(flag, options);
+  }
+}
+
+void ParseCompilerOptions(const Target* target, CompilerOptions* options) {
+  for (ConfigValuesIterator iter(target); !iter.done(); iter.Next()) {
+    ParseCompilerOptions(iter.cur().cflags(), options);
+    ParseCompilerOptions(iter.cur().cflags_c(), options);
+    ParseCompilerOptions(iter.cur().cflags_cc(), options);
+  }
+}
+
+bool WriteMsBuildProject(const BuildSettings* build_settings,
+                         std::ostream& out,
+                         const Target* target,
+                         const ProjectConfiguration& config,
+                         Err* err) {
+  PathOutput path_output(target->label().dir(),
+                         build_settings->root_path_utf8(),
+                         EscapingMode::ESCAPE_NONE);
+
+  out << "<?xml version=\"1.0\" encoding=\"utf-8\"?>" << std::endl;
+  XmlElement project(
+      out, "Project",
+      {{"DefaultTargets", "Build"},
+       {"ToolsVersion", kVisualStudioVersion},
+       {"xmlns", "http://schemas.microsoft.com/developer/msbuild/2003"}});
+
+  {
+    scoped_ptr<XmlElement> configurations =
+        project.SubElement("ItemGroup", {{"Label", "ProjectConfigurations"}});
+    std::string config_name = config.is_debug ? "Debug" : "Release";
+    scoped_ptr<XmlElement> project_config = configurations->SubElement(
+        "ProjectConfiguration",
+        {{"Include", config_name + '|' + config.platform}});
+    project_config->SubElement("Configuration")->Text(config_name);
+    project_config->SubElement("Platform")->Text(config.platform);
+  }
+
+  {
+    scoped_ptr<XmlElement> globals =
+        project.SubElement("PropertyGroup", {{"Label", "Globals"}});
+    globals->SubElement("ProjectGuid")
+        ->Text(MakeProjectGuid(target->label().name()));
+    globals->SubElement("Keyword")->Text("Win32Proj");
+    globals->SubElement("RootNamespace")->Text(target->label().name());
+    globals->SubElement("IgnoreWarnCompileDuplicatedFilename")->Text("true");
+    globals->SubElement("PreferredToolArchitecture")->Text("x64");
+  }
+
+  project.SubElement(
+      "Import", {{"Project", "$(VCTargetsPath)\\Microsoft.Cpp.Default.props"}});
+
+  {
+    scoped_ptr<XmlElement> configuration =
+        project.SubElement("PropertyGroup", {{"Label", "Configuration"}});
+    configuration->SubElement("CharacterSet")->Text("Unicode");
+    std::string configuration_type = GetConfigurationType(target, err);
+    if (configuration_type.empty())
+      return false;
+    configuration->SubElement("ConfigurationType")->Text(configuration_type);
+  }
+
+  {
+    scoped_ptr<XmlElement> locals =
+        project.SubElement("PropertyGroup", {{"Label", "Locals"}});
+    locals->SubElement("PlatformToolset")->Text(kToolsetVersion);
+  }
+
+  project.SubElement("Import",
+                     {{"Project", "$(VCTargetsPath)\\Microsoft.Cpp.props"}});
+  project.SubElement(
+      "Import",
+      {{"Project", "$(VCTargetsPath)\\BuildCustomizations\\masm.props"}});
+  project.SubElement("ImportGroup", {{"Label", "ExtensionSettings"}});
+
+  {
+    scoped_ptr<XmlElement> property_sheets =
+        project.SubElement("ImportGroup", {{"Label", "PropertySheets"}});
+    property_sheets->SubElement(
+        "Import",
+        {
+            {"Condition",
+             "exists('$(UserRootDir)\\Microsoft.Cpp.$(Platform).user.props')"},
+            {"Label", "LocalAppDataPlatform"},
+            {"Project", "$(UserRootDir)\\Microsoft.Cpp.$(Platform).user.props"},
+        });
+  }
+
+  project.SubElement("PropertyGroup", {{"Label", "UserMacros"}});
+
+  {
+    scoped_ptr<XmlElement> properties = project.SubElement("PropertyGroup");
+    {
+      scoped_ptr<XmlElement> out_dir = properties->SubElement("OutDir");
+      path_output.WriteDir(out, build_settings->build_dir(),
+                           PathOutput::DIR_INCLUDE_LAST_SLASH);
+    }
+    properties->SubElement("LinkIncremental")

[Daniel Bratell, 2016/01/14 12:08:56]

LinkIncremental really needed? VS will not do any linking, only ninja will, I
believe.

[Tomasz Moniuszko, 2016/01/21 10:50:02]

I thought it may conflict with command-line options. But it seems it doesn't. I
removed it.

+        ->Text(config.is_debug ? "true" : "false");
+    properties->SubElement("TargetName")->Text("$(ProjectName)");
+    properties->SubElement("TargetPath")
+        ->Text("$(OutDir)\\$(ProjectName)$(TargetExt)");
+  }
+
+  {
+    scoped_ptr<XmlElement> item_definitions =
+        project.SubElement("ItemDefinitionGroup");
+    {
+      scoped_ptr<XmlElement> cl_compile =
+          item_definitions->SubElement("ClCompile");
+      {
+        scoped_ptr<XmlElement> include_dirs =
+            cl_compile->SubElement("AdditionalIncludeDirectories");
+        RecursiveTargetConfigToStream<SourceDir>(
+            target, &ConfigValues::include_dirs, IncludeDirWriter(path_output),
+            out);
+        include_dirs->Text(GetWindowsKitsIncludeDirs() +
+                           "$(VSInstallDir)\\VC\\atlmfc\\include;" +
+                           "%(AdditionalIncludeDirectories)");
+      }
+      CompilerOptions options;
+      ParseCompilerOptions(target, &options);
+      if (!options.additional_options.empty()) {
+        cl_compile->SubElement("AdditionalOptions")
+            ->Text(options.additional_options + "%(AdditionalOptions)");
+      }
+      if (!options.buffer_security_check.empty()) {
+        cl_compile->SubElement("BufferSecurityCheck")
+            ->Text(options.buffer_security_check);
+      }
+      cl_compile->SubElement("CompileAsWinRT")->Text("false");
+      cl_compile->SubElement("DebugInformationFormat")->Text("ProgramDatabase");
+      if (!options.disable_specific_warnings.empty()) {
+        cl_compile->SubElement("DisableSpecificWarnings")
+            ->Text(options.disable_specific_warnings +
+                   "%(DisableSpecificWarnings)");
+      }
+      cl_compile->SubElement("ExceptionHandling")->Text("false");
+      if (!options.forced_include_files.empty()) {
+        cl_compile->SubElement("ForcedIncludeFiles")
+            ->Text(options.forced_include_files);
+      }
+      cl_compile->SubElement("MinimalRebuild")->Text("false");
+      if (!options.optimization.empty())
+        cl_compile->SubElement("Optimization")->Text(options.optimization);
+      if (target->config_values().has_precompiled_headers()) {
+        cl_compile->SubElement("PrecompiledHeader")->Text("Use");
+        cl_compile->SubElement("PrecompiledHeaderFile")
+            ->Text(target->config_values().precompiled_header());
+      } else {
+        cl_compile->SubElement("PrecompiledHeader")->Text("NotUsing");
+      }
+      {
+        scoped_ptr<XmlElement> preprocessor_definitions =
+            cl_compile->SubElement("PreprocessorDefinitions");
+        RecursiveTargetConfigToStream<std::string>(
+            target, &ConfigValues::defines, SemicolonSeparatedWriter(), out);
+        preprocessor_definitions->Text("%(PreprocessorDefinitions)");
+      }
+      if (!options.runtime_library.empty())
+        cl_compile->SubElement("RuntimeLibrary")->Text(options.runtime_library);
+      if (!options.treat_warning_as_error.empty()) {
+        cl_compile->SubElement("TreatWarningAsError")
+            ->Text(options.treat_warning_as_error);
+      }
+      if (!options.warning_level.empty())
+        cl_compile->SubElement("WarningLevel")->Text(options.warning_level);
+    }
+
+    // We don't include resource compilation and link options as ninja files
+    // are used to generate real build.
+  }
+
+  {
+    scoped_ptr<XmlElement> group = project.SubElement("ItemGroup");
+    if (!target->config_values().precompiled_source().is_null()) {
+      group->SubElement(
+               "ClCompile", "Include",
+               SourceFileWriter(path_output,
+                                target->config_values().precompiled_source()))
+          ->SubElement("PrecompiledHeader")
+          ->Text("Create");
+    }
+
+    for (const SourceFile& file : target->sources()) {
+      SourceFileType type = GetSourceFileType(file);
+      if (type == SOURCE_H || type == SOURCE_CPP || type == SOURCE_C) {
+        group->SubElement("ClCompile", "Include",
+                          SourceFileWriter(path_output, file));
+      }
+    }
+  }
+
+  project.SubElement("Import",
+                     {{"Project", "$(VCTargetsPath)\\Microsoft.Cpp.targets"}});
+  project.SubElement(
+      "Import",
+      {{"Project", "$(VCTargetsPath)\\BuildCustomizations\\masm.targets"}});
+  project.SubElement("ImportGroup", {{"Label", "ExtensionTargets"}});
+
+  {
+    scoped_ptr<XmlElement> build =
+        project.SubElement("Target", {{"Name", "Build"}});

[brettw, 2016/01/08 23:51:50]

This {{...}} is "uniform initialization syntax" right? I think this is currently
disallowed by the style guide:
https://chromium-cpp.appspot.com/

We may need to find an alternative for expressing this.

[Tomasz Moniuszko, 2016/01/21 10:50:03]

Done.

+    build->SubElement(
+        "Exec", {{"Command", "call ninja.exe -C $(OutDir) $(ProjectName)"}});
+  }
+
+  {
+    scoped_ptr<XmlElement> clean =
+        project.SubElement("Target", {{"Name", "Clean"}});
+    clean->SubElement(
+        "Exec",
+        {{"Command", "call ninja.exe -C $(OutDir) -tclean $(ProjectName)"}});
+  }
+
+  return true;
+}
+
+}  // namespace
+
+VisualStudioWriter::VisualStudioWriter(const BuildSettings* build_settings)
+    : build_settings_(build_settings) {}
+
+VisualStudioWriter::~VisualStudioWriter() {}
+
+// static
+bool VisualStudioWriter::RunAndWriteFiles(const BuildSettings* build_settings,
+                                          Builder* builder,
+                                          Err* err) {
+  std::vector<const Target*> targets = builder->GetAllResolvedTargets();
+
+  VisualStudioWriter writer(build_settings);
+
+  ProjectConfiguration config;
+  const Value* value = build_settings->build_args().GetArgOverride("is_debug");
+  config.is_debug = value == nullptr || value->boolean_value();
+  config.platform = "Win32";
+  value = build_settings->build_args().GetArgOverride(variables::kTargetCpu);
+  if (value != nullptr && value->string_value() == "x64")
+    config.platform = "x64";
+
+  for (const Target* target : targets) {
+    // Skip actions and groups.
+    if (target->output_type() == Target::GROUP ||
+        target->output_type() == Target::COPY_FILES ||
+        target->output_type() == Target::ACTION ||
+        target->output_type() == Target::ACTION_FOREACH) {
+      continue;
+    }
+
+    if (!writer.WriteProjectFile(target, config, err))
+      return false;
+  }
+
+  return writer.WriteSolutionFile(targets);
+}
+
+bool VisualStudioWriter::WriteProjectFile(const Target* target,
+                                          const ProjectConfiguration& config,
+                                          Err* err) const {
+  SourceFile target_file = target->label().dir().ResolveRelativeFile(
+      Value(nullptr, target->label().name() + ".vcxproj"), err);
+  if (target_file.is_null())
+    return false;
+
+  base::FilePath vcxproj_file(build_settings_->GetFullPath(target_file));
+
+  std::ofstream file;

[brettw, 2016/01/08 23:51:50]

In the other writers, you can see I made a stringstream and then write that to a
file. It turns out that's much much faster than using ofstream directly. I would
do that here.

[Daniel Bratell, 2016/01/14 15:41:14]

Just tested. Such a change changes the generation time from ~750 ms (fastest 684
ms) to ~600 ms (fastest 587 ms) so 20% less time.

Furthermore changing the code to only write the file if it has actually changed
cuts the time by another half for the common scenario.

+  file.open(FilePathToUTF8(vcxproj_file).c_str(),
+            std::ios_base::out | std::ios_base::binary);
+  if (file.fail()) {
+    *err = Err(Location(), "Couldn't open " + target->label().name() +
+                               ".vcxproj for writing");
+    return false;
+  }
+
+  return WriteMsBuildProject(build_settings_, file, target, config, err);
+}
+
+bool VisualStudioWriter::WriteSolutionFile(
+    const std::vector<const Target*>& targets) const {
+  return true;
+}