blob: 8a0b1427ea361ba7a9234df26376503ae6b7c89b [file] [log] [blame]
"""
THIS IS THE EXTERNAL-ONLY VERSION OF THIS FILE. G3 HAS ITS OWN.
This file contains helpers for defining build flags and options that are used to
configure the Skia build.
"""
load("@bazel_skylib//lib:selects.bzl", _selects = "selects")
# https://github.com/bazelbuild/bazel-skylib/blob/main/rules/common_settings.bzl
load("@bazel_skylib//rules:common_settings.bzl", "string_flag", skylib_bool_flag = "bool_flag")
# Re-export other symbols from bazel_skylib for convenience
selects = _selects
# Forked from https://github.com/bazelbuild/bazel-skylib/blob/main/rules/common_settings.bzl
BuildSettingInfo = provider(
doc = "A singleton provider that contains the raw value of a multi-string build setting",
fields = ["values"],
)
def _multi_string_impl(ctx):
allowed_values = ctx.attr.values
values = ctx.build_setting_value
for v in values:
if v not in ctx.attr.values:
fail("Error setting " + str(ctx.label) + ": invalid value '" + v + "'. Allowed values are " + str(allowed_values))
return BuildSettingInfo(values = values)
multi_string_flag = rule(
implementation = _multi_string_impl,
# https://bazel.build/rules/lib/config#string_list
build_setting = config.string_list(flag = True, repeatable = True),
attrs = {
"values": attr.string_list(
doc = "The list of allowed values for this setting. An error is raised if any other values are given.",
),
},
doc = "A string-typed build setting that can be set multiple times on the command line",
)
def string_flag_with_values(name, values, default = "", multiple = False):
"""Create a string flag and corresponding config_settings.
string_flag_with_values is a Bazel Macro that defines a flag with the given name and a set
of valid values for that flag. For each value, a config_setting is defined with the name
of the value, associated with the created flag.
This is defined to make the BUILD.bazel file easier to read w/o the boilerplate of defining
a string_flag rule and n config_settings
https://docs.bazel.build/versions/main/skylark/macros.html
Args:
name: string, the name of the flag to create and use for the config_settings
values: list of strings, the valid values for this flag to be set to.
default: string, whatever the default value should be if the flag is not set. Can be
empty string for both a string_flag and a multi_string flag.
multiple: boolean, True if the flag should be able to be set multiple times on the CLI.
"""
if multiple:
multi_string_flag(
name = name,
# We have to specify a default value, even if that value is empty string.
# https://docs.bazel.build/versions/main/skylark/config.html#instantiating-build-settings
build_setting_default = [default],
# We need to make sure empty string (the default) is in the list of acceptable values.
values = values + [""],
)
else:
string_flag(
name = name,
# We have to specify a default value, even if that value is empty string.
# https://docs.bazel.build/versions/main/skylark/config.html#instantiating-build-settings
build_setting_default = default,
# We need to make sure empty string (the default) is in the list of acceptable values.
values = values + [""],
)
# For each of the values given, we define a config_setting. This allows us to use
# select statements, on the given setting, e.g. referencing
# //bazel/common_config_settings:some_valid_value_for_a_flag
for v in values:
native.config_setting(
name = v,
flag_values = {
":" + name: v,
},
visibility = ["//:__subpackages__"],
)
def bool_flag(name, default):
"""Create a boolean flag and corresponding config_settings.
bool_flag is a Bazel Macro that defines a boolean flag with the given name two config_settings,
one for True, one for False. Reminder that Bazel has special syntax for unsetting boolean flags,
but this does not work well with aliases.
https://docs.bazel.build/versions/main/skylark/config.html#using-build-settings-on-the-command-line
Thus it is best to define both an "enabled" alias and a "disabled" alias.
Args:
name: string, the name of the flag to create and use for the config_settings
default: boolean, if the flag should default to on or off.
"""
skylib_bool_flag(name = name, build_setting_default = default)
vis = ["//:__subpackages__"]
native.config_setting(
name = name + "_true",
flag_values = {
# The value must be a string, but it will be parsed to a boolean
# https://docs.bazel.build/versions/main/skylark/config.html#build-settings-and-select
":" + name: "True",
},
visibility = vis,
)
native.config_setting(
name = name + "_false",
flag_values = {
":" + name: "False",
},
visibility = vis,
)