1# Copyright 2024 The Bazel Authors. All rights reserved. 2# 3# Licensed under the Apache License, Version 2.0 (the "License"); 4# you may not use this file except in compliance with the License. 5# You may obtain a copy of the License at 6# 7# http://www.apache.org/licenses/LICENSE-2.0 8# 9# Unless required by applicable law or agreed to in writing, software 10# distributed under the License is distributed on an "AS IS" BASIS, 11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12# See the License for the specific language governing permissions and 13# limitations under the License. 14"""Implementation of the cc_feature_constraint rule.""" 15 16load( 17 "//cc/toolchains/impl:collect.bzl", 18 "collect_features", 19 "collect_provider", 20) 21load( 22 ":cc_toolchain_info.bzl", 23 "FeatureConstraintInfo", 24 "FeatureSetInfo", 25) 26 27def _cc_feature_constraint_impl(ctx): 28 if ctx.attr.features: 29 fail("Features is a reserved attribute in bazel. Use the attributes `all_of` and `none_of` for feature constraints") 30 all_of = collect_provider(ctx.attr.all_of, FeatureConstraintInfo) 31 none_of = [collect_features(ctx.attr.none_of)] 32 none_of.extend([fc.none_of for fc in all_of]) 33 return [FeatureConstraintInfo( 34 label = ctx.label, 35 all_of = depset(transitive = [fc.all_of for fc in all_of]), 36 none_of = depset(transitive = none_of), 37 )] 38 39cc_feature_constraint = rule( 40 implementation = _cc_feature_constraint_impl, 41 attrs = { 42 "all_of": attr.label_list( 43 providers = [FeatureConstraintInfo], 44 ), 45 "none_of": attr.label_list( 46 providers = [FeatureSetInfo], 47 ), 48 }, 49 provides = [FeatureConstraintInfo], 50 doc = """Defines a compound relationship between features. 51 52This rule can be used with [`cc_args.require_any_of`](#cc_args-require_any_of) to specify that a set 53of arguments are only enabled when a constraint is met. Both `all_of` and `none_of` must be 54satisfied simultaneously. 55 56This is basically a `cc_feature_set` that supports `none_of` expressions. This extra flexibility 57is why this rule may only be used by [`cc_args.require_any_of`](#cc_args-require_any_of). 58 59Example: 60``` 61load("//cc/toolchains:feature_constraint.bzl", "cc_feature_constraint") 62 63# A constraint that requires a `linker_supports_thinlto` feature to be enabled, 64# AND a `no_optimization` to be disabled. 65cc_feature_constraint( 66 name = "thinlto_constraint", 67 all_of = [":linker_supports_thinlto"], 68 none_of = [":no_optimization"], 69) 70``` 71""", 72) 73