Add an output_dir override to GN.

tools/gn/variables.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/variables.h"
 
 namespace variables {
 
 // Built-in variables ----------------------------------------------------------
 
@@ skipping 1101 matching lines @@
     "\n"
     "  # On Windows, generate a \"mysettings.cpl\" control panel applet.\n"
     "  # Control panel applets are actually special shared libraries.\n"
     "  if (is_win) {\n"
     "    shared_library(\"mysettings\") {\n"
     "      output_extension = \"cpl\"\n"
     "      ...\n"
     "    }\n"
     "  }\n";
 
+const char kOutputDir[] = "output_dir";
+const char kOutputDir_HelpShort[] =
+    "output_dir: [directory] Directory to put output file in.";
+const char kOutputDir_Help[] =
+    "output_dir: [directory] Directory to put output file in.\n"
+    "\n"
+    "  For library and executable targets, overrides the directory for the\n"
+    "  final output. This must be in the root_build_dir or a child thereof.\n"
+    "\n"
+    "  This should generally be in the root_out_dir or a subdirectory thereof\n"
+    "  (the root_out_dir will be the same as the root_build_dir for the\n"
+    "  default toolchain, and will be a subdirectory for other toolchains).\n"
+    "  Not putting the output in a subdirectory of root_out_dir can result\n"
+    "  in collisions between different toolchains, so you will need to take\n"
+    "  steps to ensure that your target is only present in one toolchain.\n"
+    "\n"
+    "  Normally the toolchain specifies the output directory for libraries\n"
+    "  and executables (see \"gn help tool\"). You will have to consult that\n"
+    "  for the default location. The default location will be used if\n"
+    "  output_dir is undefined or empty.\n"
+    "\n"
+    "Example\n"
+    "\n"
+    "  shared_library(\"doom_melon\") {\n"
+    "    output_dir = \"$root_out_dir/plugin_libs\"\n"
+    "    ...\n"
+    "  }\n";
+
 const char kOutputName[] = "output_name";
 const char kOutputName_HelpShort[] =
     "output_name: [string] Name for the output file other than the default.";
 const char kOutputName_Help[] =
     "output_name: Define a name for the output file other than the default.\n"
     "\n"
     "  Normally the output name of a target will be based on the target name,\n"
     "  so the target \"//foo/bar:bar_unittests\" will generate an output\n"
     "  file such as \"bar_unittests.exe\" (using Windows as an example).\n"
     "\n"
@@ skipping 497 matching lines @@
     INSERT_VARIABLE(Data)
     INSERT_VARIABLE(DataDeps)
     INSERT_VARIABLE(Defines)
     INSERT_VARIABLE(Depfile)
     INSERT_VARIABLE(Deps)
     INSERT_VARIABLE(IncludeDirs)
     INSERT_VARIABLE(Inputs)
     INSERT_VARIABLE(Ldflags)
     INSERT_VARIABLE(Libs)
     INSERT_VARIABLE(LibDirs)
+    INSERT_VARIABLE(OutputDir)
     INSERT_VARIABLE(OutputExtension)
     INSERT_VARIABLE(OutputName)
     INSERT_VARIABLE(OutputPrefixOverride)
     INSERT_VARIABLE(Outputs)
     INSERT_VARIABLE(PrecompiledHeader)
     INSERT_VARIABLE(PrecompiledSource)
     INSERT_VARIABLE(Public)
     INSERT_VARIABLE(PublicConfigs)
     INSERT_VARIABLE(PublicDeps)
     INSERT_VARIABLE(ResponseFileContents)
     INSERT_VARIABLE(Script)
     INSERT_VARIABLE(Sources)
     INSERT_VARIABLE(Testonly)
     INSERT_VARIABLE(Visibility)
     INSERT_VARIABLE(WriteRuntimeDeps)
   }
   return info_map;
 }
 
 #undef INSERT_VARIABLE
 
 }  // namespace variables