1# Copyright 2024 The Pigweed Authors 2# 3# Licensed under the Apache License, Version 2.0 (the "License"); you may not 4# use this file except in compliance with the License. You may obtain a copy of 5# the License at 6# 7# https://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, WITHOUT 11# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 12# License for the specific language governing permissions and limitations under 13# the License. 14 15"""Defines the per_platform_alias rule.""" 16 17load("@local_config_platform//:constraints.bzl", "HOST_CONSTRAINTS") 18 19def _get_host_platform(): 20 """Return the <cpu>-<os> platform string (e.g. x86_64-linux).""" 21 22 # HACK: HOST_CONSTRAINTS is a list containing the CPU constraint 23 # followed by the OS constraint. We use this to figure out the 24 # current CPU+OS pair. 25 if len(HOST_CONSTRAINTS) != 2: 26 fail("Unexpected HOST_CONSTRAINTS: " + HOST_CONSTRAINTS) 27 cpu_constraint, os_constraint = HOST_CONSTRAINTS 28 cpu = cpu_constraint.removeprefix("@platforms//cpu:") 29 os = os_constraint.removeprefix("@platforms//os:") 30 return cpu + "-" + os 31 32def per_platform_alias(name, platform_to_label): 33 """Aliases to a different target depending on platform. 34 35 Args: 36 name: The name of the resulting target. 37 platform_to_label: A mapping from "<cpu>-<os>" platform string 38 (e.g. x86_64-linux") to label that you wish to alias. 39 """ 40 host_platform = _get_host_platform() 41 if not host_platform in platform_to_label: 42 fail("No alias provided for platform " + host_platform) 43 label = platform_to_label[host_platform] 44 native.alias(name = name, actual = label) 45