.gn

# Copyright 2015 The Chromium Authors. All rights reserved.
#
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# modification, are permitted provided that the following conditions are
# met:
#
#    * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#    * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
#    * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# Copyright (C) <2018> Intel Corporation
#
# SPDX-License-Identifier: Apache-2.0

# This file is borrowed from Chromium with modifications.

# This file is used by the GN meta build system to find the root of the source
# tree and to set startup options. For documentation on the values set in this
# file, run "gn help dotfile" at the command line.

import("//build/dotfile_settings.gni")

# The location of the build configuration file.
buildconfig = "//build/config/BUILDCONFIG.gn"

# The secondary source root is a parallel directory tree where
# GN build files are placed when they can not be placed directly
# in the source tree, e.g. for third party source trees.
secondary_source = "//build/secondary/"

# These arguments override the default values for items in a declare_args
# block. "gn args" in turn can override these.
#
# In general the value for a build arg in the declare_args block should be the
# default. In some cases, a DEPS-ed in project will want different defaults for
# being built as part of Chrome vs. being built standalone. In this case, the
# Chrome defaults should go here. There should be no overrides here for
# values declared in the main Chrome repository.
#
# Important note for defining defaults: This file is executed before the
# BUILDCONFIG.gn file. That file sets up the global variables like "is_ios".
# This means that the default_args can not depend on the platform,
# architecture, or other build parameters. If you really need that, the other
# repo should define a flag that toggles on a behavior that implements the
# additional logic required by Chrome to set the variables.
default_args = {}

# These are the targets to check headers for by default. The files in targets
# matching these patterns (see "gn help label_pattern" for format) will have
# their includes checked for proper dependencies when you run either
# "gn check" or "gn gen --check".
check_targets = []

# These are the list of GN files that run exec_script. This whitelist exists
# to force additional review for new uses of exec_script, which is strongly
# discouraged.
#
# GYPI_TO_GN
#
# Some of these entries are for legacy gypi_to_gn calls. We should not be
# adding new calls to this script in the build (see //build/gypi_to_gn.py for
# detailed advice). The only time you should be editing this list for
# gypi_to_gn purposes is when moving an existing call to a different place.
#
# PLEASE READ
#
# You should almost never need to add new exec_script calls. exec_script is
# slow, especially on Windows, and can cause confusing effects. Although
# individually each call isn't slow or necessarily very confusing, at the scale
# of our repo things get out of hand quickly. By strongly pushing back on all
# additions, we keep the build fast and clean. If you think you need to add a
# new call, please consider:
#
# - Do not use a script to check for the existance of a file or directory to
#   enable a different mode. Instead, use GN build args to enable or disable
#   functionality and set options. An example is checking for a file in the
#   src-internal repo to see if the corresponding src-internal feature should
#   be enabled. There are several things that can go wrong with this:
#
#    - It's mysterious what causes some things to happen. Although in many cases
#      such behavior can be conveniently automatic, GN optimizes for explicit
#      and obvious behavior so people can more easily diagnose problems.
#
#    - The user can't enable a mode for one build and not another. With GN build
#      args, the user can choose the exact configuration of multiple builds
#      using one checkout. But implicitly basing flags on the state of the
#      checkout, this functionality is broken.
#
#    - It's easy to get stale files. If for example the user edits the gclient
#      to stop checking out src-internal (or any other optional thing), it's
#      easy to end up with stale files still mysteriously triggering build
#      conditions that are no longer appropriate (yes, this happens in real
#      life).
#
# - Do not use a script to iterate files in a directory (glob):
#
#    - This has the same "stale file" problem as the above discussion. Various
#      operations can leave untracked files in the source tree which can cause
#      surprising effects.
#
#    - It becomes impossible to use "git grep" to find where a certain file is
#      referenced. This operation is very common and people really do get
#      confused when things aren't listed.
#
#    - It's easy to screw up. One common case is a build-time script that packs
#      up a directory. The author notices that the script isn't re-run when the
#      directory is updated, so adds a glob so all the files are listed as
#      inputs. This seems to work great... until a file is deleted. When a
#      file is deleted, all the inputs the glob lists will still be up to date
#      and no command-lines will have been changed. The action will not be
#      re-run and the build will be broken. It is possible to get this correct
#      using glob, and it's possible to mess it up without glob, but globs make
#      this situation much easier to create. if the build always lists the
#      files and passes them to a script, it will always be correct.

exec_script_whitelist =
    build_dotfile_settings.exec_script_whitelist + [
      # Whitelist entries for //build should go into
      # //build/dotfile_settings.gni instead, so that they can be shared
      # with other repos. The entries in this list should be only for files
      # in the Chromium repo outside of //build.
      "//build_overrides/build.gni",
    ]