Add runtime dependency extraction for GN.

tools/gn/switches.cc

 // Copyright 2014 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/switches.h"
 
 namespace switches {
 
 const char kArgs[] = "args";
 const char kArgs_HelpShort[] =
@@ skipping 40 matching lines @@
     "  gn gen out/Default --color\n"\
     "\n"\
     "  gn gen out/Default --nocolor\n"
 const char kColor[] = "color";
 const char kColor_HelpShort[] =
     "--color: Force colored output.";
 const char kColor_Help[] = COLOR_HELP_LONG;
 
 const char kDotfile[] = "dotfile";
 const char kDotfile_HelpShort[] =
-    "--dotfile: override the name of the \".gn\" file.";
+    "--dotfile: Override the name of the \".gn\" file.";
 const char kDotfile_Help[] =
-    "--dotfile: override the name of the \".gn\" file.\n"
+    "--dotfile: Override the name of the \".gn\" file.\n"
     "\n"
     "  Normally GN loads the \".gn\"file  from the source root for some basic\n"
     "  configuration (see \"gn help dotfile\"). This flag allows you to\n"
     "  use a different file.\n"
     "\n"
     "  Note that this interacts with \"--root\" in a possibly incorrect way.\n"
     "  It would be nice to test the edge cases and document or fix.\n";
 
 const char kMarkdown[] = "markdown";
 const char kMarkdown_HelpShort[] =
@@ skipping 27 matching lines @@
     "\n"
     "  Specifying --root allows GN to do builds in a specific directory\n"
     "  regardless of the current directory.\n"
     "\n"
     "Examples\n"
     "\n"
     "  gn gen //out/Default --root=/home/baracko/src\n"
     "\n"
     "  gn desc //out/Default --root=\"C:\\Users\\BObama\\My Documents\\foo\"\n";
 
+const char kRuntimeDepsListFile[] = "runtime-deps-list-file";
+const char kRuntimeDepsListFile_HelpShort[] =
+    "--runtime-deps-list-file: Save runtime dependencies for targets in file.";
+const char kRuntimeDepsListFile_Help[] =
+    "--runtime-deps-list-file: Save runtime dependencies for targets in file.\n"
+    "\n"
+    "  --runtime-deps-list-file=<filename>\n"
+    "\n"
+    "  Where <filename> is a text file consisting of the labels, one per\n"
+    "  line, of the targets for which runtime dependencies are desired.\n"
+    "\n"
+    "  See \"gn help runtime_deps\" for a description of how runtime\n"
+    "  dependencies are computed.\n"
+    "\n"
+    "Runtime deps output file\n"
+    "\n"
+    "  For each target requested, GN will write a separate runtime dependency\n"
+    "  file. The runtime dependency file will be in the output directory\n"
+    "  alongside the output file of the target, with a \".runtime_deps\"\n"
+    "  extension. For example, if the target \"//foo:bar\" is listed in the\n"
+    "  input file, and that target produces an output file \"bar.so\", GN\n"
+    "  will create a file \"bar.so.runtime_deps\" in the build directory.\n"
+    "\n"
+    "  If a source set, action, copy, or group is listed, the runtime deps\n"
+    "  file will correspond to the .stamp file corresponding to that target.\n"
+    "  This is probably not useful; the use-case for this feature is\n"
+    "  generally executable targets.\n"
+    "\n"
+    "  The runtime dependency file will list one file per line, with no\n"
+    "  escaping. The files will be relative to the root_build_dir. The first\n"
+    "  line of the file will be the main output file of the target itself\n"
+    "  (in the above example, \"bar.so\").\n";
+
 const char kThreads[] = "threads";
 const char kThreads_HelpShort[] =
     "--threads: Specify number of worker threads.";
 const char kThreads_Help[] =
     "--threads: Specify number of worker threads.\n"
     "\n"
     "  GN runs many threads to load and run build files. This can make\n"
     "  debugging challenging. Or you may want to experiment with different\n"
     "  values to see how it affects performance.\n"
     "\n"
@@ skipping 66 matching lines @@
 const SwitchInfoMap& GetSwitches() {
   static SwitchInfoMap info_map;
   if (info_map.empty()) {
     INSERT_VARIABLE(Args)
     INSERT_VARIABLE(Color)
     INSERT_VARIABLE(Dotfile)
     INSERT_VARIABLE(Markdown)
     INSERT_VARIABLE(NoColor)
     INSERT_VARIABLE(Root)
     INSERT_VARIABLE(Quiet)
+    INSERT_VARIABLE(RuntimeDepsListFile)
     INSERT_VARIABLE(Time)
     INSERT_VARIABLE(Tracelog)
     INSERT_VARIABLE(Verbose)
     INSERT_VARIABLE(Version)
   }
   return info_map;
 }
 
 #undef INSERT_VARIABLE
 
 }  // namespace switches