blob: 9bf5bc4ecc980a42a79eb4bc878c9997130038fb [file] [log] [blame]
# pylint: disable=g-bad-file-header
# Copyright 2016 The Bazel Authors. All rights reserved.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.
Utilities to help work with c++ toolchains.
CPP_TOOLCHAIN_TYPE = "@bazel_tools//tools/cpp:toolchain_type"
def find_cpp_toolchain(ctx, *, mandatory = True):
Finds the c++ toolchain.
If the c++ toolchain is in use, returns it. Otherwise, returns a c++
toolchain derived from legacy toolchain selection, constructed from
the CppConfiguration.
ctx: The rule context for which to find a toolchain.
mandatory: If this is set to False, this function will return None rather
than fail if no toolchain is found. To use this parameter, the calling
rule should have a `_cc_toolchain` label attribute with default
A CcToolchainProvider, or None if the c++ toolchain is declared as
optional, mandatory is False and no toolchain has been found.
# Check the incompatible flag for toolchain resolution.
if hasattr(cc_common, "is_cc_toolchain_resolution_enabled_do_not_use") and cc_common.is_cc_toolchain_resolution_enabled_do_not_use(ctx = ctx):
if not CPP_TOOLCHAIN_TYPE in ctx.toolchains:
fail("In order to use find_cpp_toolchain, you must include the '%s' in the toolchains argument to your rule." % CPP_TOOLCHAIN_TYPE)
toolchain_info = ctx.toolchains[CPP_TOOLCHAIN_TYPE]
if toolchain_info == None:
if not mandatory:
return None
# No cpp toolchain was found, so report an error.
fail("Unable to find a CC toolchain using toolchain resolution. Target: %s, Platform: %s, Exec platform: %s" %
(ctx.label, ctx.fragments.platform.platform, ctx.fragments.platform.host_platform))
if hasattr(toolchain_info, "cc_provider_in_toolchain") and hasattr(toolchain_info, "cc"):
return toolchain_info
# Fall back to the legacy implicit attribute lookup.
if hasattr(ctx.attr, "_cc_toolchain"):
return ctx.attr._cc_toolchain[cc_common.CcToolchainInfo]
# We didn't find anything.
fail("In order to use find_cpp_toolchain, you must define the '_cc_toolchain' attribute on your rule or aspect.")
def use_cpp_toolchain(mandatory = False):
Helper to depend on the c++ toolchain.
my_rule = rule(
toolchains = [other toolchain types] + use_cpp_toolchain(),
mandatory: Whether or not it should be an error if the toolchain cannot be resolved.
A list that can be used as the value for `rule.toolchains`.
return [config_common.toolchain_type(CPP_TOOLCHAIN_TYPE, mandatory = mandatory)]