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[] =
    "--args: Specifies build arguments overrides.";
const char kArgs_Help[] =
    R"(--args: Specifies build arguments overrides.

  See "gn help buildargs" for an overview of how build arguments work.

  Most operations take a build directory. The build arguments are taken from
  the previous build done in that directory. If a command specifies --args, it
  will override the previous arguments stored in the build directory, and use
  the specified ones.

  The args specified will be saved to the build directory for subsequent
  commands. Specifying --args="" will clear all build arguments.

Formatting

  The value of the switch is interpreted in GN syntax. For typical usage of
  string arguments, you will need to be careful about escaping of quotes.

Examples

  gn gen out/Default --args="foo=\"bar\""

  gn gen out/Default --args='foo="bar" enable=true blah=7'

  gn check out/Default --args=""
    Clears existing build args from the directory.

  gn desc out/Default --args="some_list=[1, false, \"foo\"]"
)";

#define COLOR_HELP_LONG \
    "--[no]color: Forces colored output on or off.\n"\
    "\n"\
    "  Normally GN will try to detect whether it is outputting to a terminal\n"\
    "  and will enable or disable color accordingly. Use of these switches\n"\
    "  will override the default.\n"\
    "\n"\
    "Examples\n"\
    "\n"\
    "  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.";
const char kDotfile_Help[] =
    R"(--dotfile: Override the name of the ".gn" file.

  Normally GN loads the ".gn"file  from the source root for some basic
  configuration (see "gn help dotfile"). This flag allows you to
  use a different file.

  Note that this interacts with "--root" in a possibly incorrect way.
  It would be nice to test the edge cases and document or fix.
)";

const char kFailOnUnusedArgs[] = "fail-on-unused-args";
const char kFailOnUnusedArgs_HelpShort[] =
    "--fail-on-unused-args: Treat unused build args as fatal errors.";
const char kFailOnUnusedArgs_Help[] =
    R"(--fail-on-unused-args: Treat unused build args as fatal errors.

  If you set a value in a build's "gn args" and never use it in the build (in
  a declare_args() block), GN will normally print an error but not fail the
  build.

  In many cases engineers would use build args to enable or disable features
  that would sometimes get removed. It would by annoying to block work for
  typically benign problems. In Chrome in particular, flags might be configured
  for build bots in a separate infrastructure repository, or a declare_args
  block might be changed in a third party repository. Treating these errors as
  blocking forced complex multi- way patches to land what would otherwise be
  simple changes.

  In some cases, such concerns are not as important, and a mismatch in build
  flags between the invoker of the build and the build files represents a
  critical mismatch that should be immediately fixed. Such users can set this
  flag to force GN to fail in that case.
)";

const char kMarkdown[] = "markdown";
const char kMarkdown_HelpShort[] =
    "--markdown: Write help output in the Markdown format.";
const char kMarkdown_Help[] =
    "--markdown: Write help output in the Markdown format.\n";

const char kNoColor[] = "nocolor";
const char kNoColor_HelpShort[] =
    "--nocolor: Force non-colored output.";
const char kNoColor_Help[] = COLOR_HELP_LONG;

const char kScriptExecutable[] = "script-executable";
const char kScriptExecutable_HelpShort[] =
    "--script-executable: Set the executable used to execute scripts.";
const char kScriptExecutable_Help[] =
    R"(--script-executable: Set the executable used to execute scripts.

  By default GN searches the PATH for Python to execute scripts in action
  targets and exec_script calls. This flag allows the specification of a
  specific Python executable or potentially a different language
  interpreter.
)";

const char kQuiet[] = "q";
const char kQuiet_HelpShort[] =
    "-q: Quiet mode. Don't print output on success.";
const char kQuiet_Help[] =
    R"(-q: Quiet mode. Don't print output on success.

  This is useful when running as a part of another script.
)";

const char kRoot[] = "root";
const char kRoot_HelpShort[] =
    "--root: Explicitly specify source root.";
const char kRoot_Help[] =
    R"(--root: Explicitly specify source root.

  Normally GN will look up in the directory tree from the current directory to
  find a ".gn" file. The source root directory specifies the meaning of "//"
  beginning with paths, and the BUILD.gn file in that directory will be the
  first thing loaded.

  Specifying --root allows GN to do builds in a specific directory regardless
  of the current directory.

Examples

  gn gen //out/Default --root=/home/baracko/src

  gn desc //out/Default --root="C:\Users\BObama\My Documents\foo"
)";

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[] =
    R"(--runtime-deps-list-file: Save runtime dependencies for targets in file.

  --runtime-deps-list-file=<filename>

  Where <filename> is a text file consisting of the labels, one per line, of
  the targets for which runtime dependencies are desired.

  See "gn help runtime_deps" for a description of how runtime dependencies are
  computed.

Runtime deps output file

  For each target requested, GN will write a separate runtime dependency file.
  The runtime dependency file will be in the output directory alongside the
  output file of the target, with a ".runtime_deps" extension. For example, if
  the target "//foo:bar" is listed in the input file, and that target produces
  an output file "bar.so", GN will create a file "bar.so.runtime_deps" in the
  build directory.

  If a source set, action, copy, or group is listed, the runtime deps file will
  correspond to the .stamp file corresponding to that target. This is probably
  not useful; the use-case for this feature is generally executable targets.

  The runtime dependency file will list one file per line, with no escaping.
  The files will be relative to the root_build_dir. The first line of the file
  will be the main output file of the target itself (in the above example,
  "bar.so").
)";

const char kThreads[] = "threads";
const char kThreads_HelpShort[] =
    "--threads: Specify number of worker threads.";
const char kThreads_Help[] =
    R"(--threads: Specify number of worker threads.

  GN runs many threads to load and run build files. This can make debugging
  challenging. Or you may want to experiment with different values to see how
  it affects performance.

  The parameter is the number of worker threads. This does not count the main
  thread (so there are always at least two).

Examples

  gen gen out/Default --threads=1
)";

const char kTime[] = "time";
const char kTime_HelpShort[] =
    "--time: Outputs a summary of how long everything took.";
const char kTime_Help[] =
    R"(--time: Outputs a summary of how long everything took.

  Hopefully self-explanatory.

Examples

  gn gen out/Default --time
)";

const char kTracelog[] = "tracelog";
const char kTracelog_HelpShort[] =
    "--tracelog: Writes a Chrome-compatible trace log to the given file.";
const char kTracelog_Help[] =
    R"(--tracelog: Writes a Chrome-compatible trace log to the given file.

  The trace log will show file loads, executions, scripts, and writes. This
  allows performance analysis of the generation step.

  To view the trace, open Chrome and navigate to "chrome://tracing/", then
  press "Load" and specify the file you passed to this parameter.

Examples

  gn gen out/Default --tracelog=mytrace.trace
)";

const char kVerbose[] = "v";
const char kVerbose_HelpShort[] =
    "-v: Verbose logging.";
const char kVerbose_Help[] =
    R"(-v: Verbose logging.

  This will spew logging events to the console for debugging issues.

  Good luck!
)";

const char kVersion[] = "version";
const char kVersion_HelpShort[] =
    "--version: Prints the GN version number and exits.";
// It's impossible to see this since gn_main prints the version and exits
// immediately if this switch is used.
const char kVersion_Help[] = "";

const char kAllToolchains[] = "all-toolchains";

// -----------------------------------------------------------------------------

SwitchInfo::SwitchInfo()
    : short_help(""),
      long_help("") {
}

SwitchInfo::SwitchInfo(const char* short_help, const char* long_help)
    : short_help(short_help),
      long_help(long_help) {
}

#define INSERT_VARIABLE(var) \
    info_map[k##var] = SwitchInfo(k##var##_HelpShort, k##var##_Help);

const SwitchInfoMap& GetSwitches() {
  static SwitchInfoMap info_map;
  if (info_map.empty()) {
    INSERT_VARIABLE(Args)
    INSERT_VARIABLE(Color)
    INSERT_VARIABLE(Dotfile)
    INSERT_VARIABLE(FailOnUnusedArgs)
    INSERT_VARIABLE(Markdown)
    INSERT_VARIABLE(NoColor)
    INSERT_VARIABLE(Root)
    INSERT_VARIABLE(Quiet)
    INSERT_VARIABLE(RuntimeDepsListFile)
    INSERT_VARIABLE(ScriptExecutable)
    INSERT_VARIABLE(Threads)
    INSERT_VARIABLE(Time)
    INSERT_VARIABLE(Tracelog)
    INSERT_VARIABLE(Verbose)
    INSERT_VARIABLE(Version)
  }
  return info_map;
}

#undef INSERT_VARIABLE

}  // namespace switches