[Refactor Xcode Objects] Enable generating per file '--help' compiler flag

tools/gn/xcode_object.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 "tools/gn/xcode_object.h"
 
 #include <iomanip>
 #include <sstream>
 #include <utility>
 
@@ skipping 347 matching lines @@
   PrintProperty(out, rules, "buildPhases", build_phases_);
   PrintProperty(out, rules, "dependencies", EmptyPBXObjectVector());
   PrintProperty(out, rules, "name", name_);
   PrintProperty(out, rules, "productName", name_);
   out << indent_str << "};\n";
 }
 
 // PBXBuildFile ---------------------------------------------------------------
 
 PBXBuildFile::PBXBuildFile(const PBXFileReference* file_reference,
-                           const PBXSourcesBuildPhase* build_phase)
-    : file_reference_(file_reference), build_phase_(build_phase) {
+                           const PBXSourcesBuildPhase* build_phase,
+                           const CompilerFlags compiler_flag)
+    : file_reference_(file_reference),
+      build_phase_(build_phase),
+      compiler_flag_(compiler_flag) {
   DCHECK(file_reference_);
   DCHECK(build_phase_);
 }
 
 PBXBuildFile::~PBXBuildFile() {}
 
 PBXObjectClass PBXBuildFile::Class() const {
   return PBXBuildFileClass;
 }
 
 std::string PBXBuildFile::Name() const {
   return file_reference_->Name() + " in " + build_phase_->Name();
 }
 
 void PBXBuildFile::Print(std::ostream& out, unsigned indent) const {
   const std::string indent_str(indent, '\t');
   const IndentRules rules = {true, 0};
   out << indent_str << Reference() << " = {";
   PrintProperty(out, rules, "isa", ToString(Class()));
   PrintProperty(out, rules, "fileRef", file_reference_);
+  if (compiler_flag_ == CompilerFlags::HELP) {
+    std::map<std::string, std::string> settings = {
+        {"COMPILER_FLAGS", "--help"},
+    };
+    PrintProperty(out, rules, "settings", settings);
+  }
   out << "};\n";
 }
 
 // PBXFileReference -----------------------------------------------------------
 
 PBXFileReference::PBXFileReference(const std::string& name,
                                    const std::string& path,
                                    const std::string& type)
     : name_(name), path_(path), type_(type) {}
 
@@ skipping 156 matching lines @@
   DCHECK(product_reference_);
   build_phases_.push_back(base::WrapUnique(new PBXSourcesBuildPhase));
   source_build_phase_ =
       static_cast<PBXSourcesBuildPhase*>(build_phases_.back().get());
 
   build_phases_.push_back(base::WrapUnique(new PBXFrameworksBuildPhase));
 }
 
 PBXNativeTarget::~PBXNativeTarget() {}
 
-void PBXNativeTarget::AddFileForIndexing(
-    const PBXFileReference* file_reference) {
+void PBXNativeTarget::AddFileForIndexing(const PBXFileReference* file_reference,
+                                         const CompilerFlags compiler_flag) {
   DCHECK(file_reference);
-  source_build_phase_->AddBuildFile(
-      base::MakeUnique<PBXBuildFile>(file_reference, source_build_phase_));
+  source_build_phase_->AddBuildFile(base::MakeUnique<PBXBuildFile>(
+      file_reference, source_build_phase_, compiler_flag));
 }
 
 PBXObjectClass PBXNativeTarget::Class() const {
   return PBXNativeTargetClass;
 }
 
 void PBXNativeTarget::Print(std::ostream& out, unsigned indent) const {
   const std::string indent_str(indent, '\t');
   const IndentRules rules = {false, indent + 1};
   out << indent_str << Reference() << " = {\n";
@@ skipping 26 matching lines @@
       base::MakeUnique<PBXGroup>(std::string(), "Product")));
   main_group_->AddChild(base::MakeUnique<PBXGroup>(std::string(), "Build"));
 
   configurations_.reset(new XCConfigurationList(config_name, attributes, this));
 }
 
 PBXProject::~PBXProject() {}
 
 void PBXProject::AddSourceFileToIndexingTarget(
     const std::string& navigator_path,
-    const std::string& source_path) {
+    const std::string& source_path,
+    const CompilerFlags compiler_flag) {
   if (!target_for_indexing_) {
     AddIndexingTarget();
   }
-  AddSourceFile(navigator_path, source_path, target_for_indexing_);
+  AddSourceFile(navigator_path, source_path, compiler_flag,
+                target_for_indexing_);
 }
 
 void PBXProject::AddSourceFile(const std::string& navigator_path,
                                const std::string& source_path,
+                               const CompilerFlags compiler_flag,
                                PBXNativeTarget* target) {
   PBXFileReference* file_reference =
       sources_->AddSourceFile(navigator_path, source_path);
   base::StringPiece ext = FindExtension(&source_path);
   if (!IsSourceFileForIndexing(ext))
     return;
 
   DCHECK(target);
-  target->AddFileForIndexing(file_reference);
+  target->AddFileForIndexing(file_reference, compiler_flag);
 }
 
 void PBXProject::AddAggregateTarget(const std::string& name,
                                     const std::string& shell_script) {
   PBXAttributes attributes;
   attributes["CODE_SIGNING_REQUIRED"] = "NO";
   attributes["CONFIGURATION_BUILD_DIR"] = ".";
   attributes["PRODUCT_NAME"] = name;
 
   targets_.push_back(base::MakeUnique<PBXAggregateTarget>(
@@ skipping 232 matching lines @@
   const std::string indent_str(indent, '\t');
   const IndentRules rules = {false, indent + 1};
   out << indent_str << Reference() << " = {\n";
   PrintProperty(out, rules, "isa", ToString(Class()));
   PrintProperty(out, rules, "buildConfigurations", configurations_);
   PrintProperty(out, rules, "defaultConfigurationIsVisible", 1u);
   PrintProperty(out, rules, "defaultConfigurationName",
                 configurations_[0]->Name());
   out << indent_str << "};\n";
 }