Enhance GN's "desc" command to support configs.

tools/gn/command_refs.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 <stddef.h>
 
 #include <map>
 #include <set>
 
 #include "base/command_line.h"
 #include "base/files/file_util.h"
 #include "base/strings/string_split.h"
 #include "tools/gn/commands.h"
 #include "tools/gn/deps_iterator.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/input_file.h"
 #include "tools/gn/item.h"
 #include "tools/gn/setup.h"
 #include "tools/gn/standard_out.h"
+#include "tools/gn/switches.h"
 #include "tools/gn/target.h"
 
 namespace commands {
 
 namespace {
 
 typedef std::set<const Target*> TargetSet;
 typedef std::vector<const Target*> TargetVector;
 
 // Maps targets to the list of targets that depend on them.
@@ skipping 278 matching lines @@
     "\n"
     "  --all\n"
     "      When used without --tree, will recurse and display all unique\n"
     "      dependencies of the given targets. For example, if the input is\n"
     "      a target, this will output all targets that depend directly or\n"
     "      indirectly on the input. If the input is a file, this will output\n"
     "      all targets that depend directly or indirectly on that file.\n"
     "\n"
     "      When used with --tree, turns off eliding to show a complete tree.\n"
     "\n"
-    "  --all-toolchains\n"
-    "      Normally only inputs in the default toolchain will be included.\n"
-    "      This switch will turn on matching all toolchains.\n"
-    "\n"
-    "      For example, a file is in a target might be compiled twice:\n"
-    "      once in the default toolchain and once in a secondary one. Without\n"
-    "      this flag, only the default toolchain one will be matched and\n"
-    "      printed (potentially with its recursive dependencies, depending on\n"
-    "      the other options). With this flag, both will be printed\n"
-    "      (potentially with both of their recursive dependencies).\n"
+    ALL_TOOLCHAINS_SWITCH_HELP
     "\n"
     TARGET_PRINTING_MODE_COMMAND_LINE_HELP
     "\n"
     "  -q\n"
     "     Quiet. If nothing matches, don't print any output. Without this\n"
     "     option, if there are no matches there will be an informational\n"
     "     message printed which might interfere with scripts processing the\n"
     "     output.\n"
     "\n"
     TARGET_TESTONLY_FILTER_COMMAND_LINE_HELP
@@ skipping 52 matching lines @@
   if (args.size() <= 1) {
     Err(Location(), "You're holding it wrong.",
         "Usage: \"gn refs <out_dir> (<label_pattern>|<file>)*\"")
         .PrintToStdout();
     return 1;
   }
 
   const base::CommandLine* cmdline = base::CommandLine::ForCurrentProcess();
   bool tree = cmdline->HasSwitch("tree");
   bool all = cmdline->HasSwitch("all");
-  bool all_toolchains = cmdline->HasSwitch("all-toolchains");
+  bool all_toolchains = cmdline->HasSwitch(switches::kAllToolchains);
 
   Setup* setup = new Setup;
   setup->build_settings().set_check_for_bad_items(false);
   if (!setup->DoSetup(args[0], false) || !setup->Run())
     return 1;
 
   // The inputs are everything but the first arg (which is the build dir).
   std::vector<std::string> inputs;
   for (size_t i = 1; i < args.size(); i++) {
     if (args[i][0] == '@') {
@@ skipping 71 matching lines @@
 
   // If you ask for the references of a valid target, but that target has
   // nothing referencing it, we'll get here without having printed anything.
   if (!quiet && cnt == 0)
     OutputString("Nothing references this.\n", DECORATION_YELLOW);
 
   return 0;
 }
 
 }  // namespace commands