gn: Support build directories outside the source tree.

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 <fstream>
 #include <sstream>
 
 #include "base/files/file_util.h"
@@ skipping 10 matching lines @@
 #include "tools/gn/string_utils.h"
 #include "tools/gn/substitution_writer.h"
 #include "tools/gn/target.h"
 #include "tools/gn/trace.h"
 
 NinjaTargetWriter::NinjaTargetWriter(const Target* target,
                                      std::ostream& out)
     : settings_(target->settings()),
       target_(target),
       out_(out),
-      path_output_(settings_->build_settings()->build_dir(), ESCAPE_NINJA) {
+      path_output_(settings_->build_settings()->build_dir(),
+                   settings_->build_settings()->root_path(), ESCAPE_NINJA) {
 }
 
 NinjaTargetWriter::~NinjaTargetWriter() {
 }
 
 // static
 void NinjaTargetWriter::RunAndWriteFile(const Target* target) {
   const Settings* settings = target->settings();
 
   ScopedTrace trace(TraceItem::TRACE_FILE_WRITE,
@@ skipping 126 matching lines @@
 
   // One potential optimization is if there are few input dependencies (or
   // potentially few sources that depend on these) it's better to just write
   // all hard deps on each sources line than have this intermediate stamp. We
   // do the stamp file because duplicating all the order-only deps for each
   // source file can really explode the ninja file but this won't be the most
   // optimal thing in all cases.
 
   OutputFile input_stamp_file(
       RebaseSourceAbsolutePath(GetTargetOutputDir(target_).value(),
-                               settings_->build_settings()->build_dir()));
+                               settings_->build_settings()->build_dir(),
+                               settings_->build_settings()->root_path()));
   input_stamp_file.value().append(target_->label().name());
   input_stamp_file.value().append(".inputdeps.stamp");
 
   out_ << "build ";
   path_output_.WriteFile(out_, input_stamp_file);
   out_ << ": "
        << GetNinjaRulePrefixForToolchain(settings_)
        << Toolchain::ToolTypeToName(Toolchain::TYPE_STAMP);
 
   // Script file (if applicable).
@@ skipping 67 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;
 }