blob: 1583aedcc1873f3c0dcf76b8c04913b969c16b0f [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
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# 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.
Args:
ctx: The rule context for which to find a toolchain.
mandatory: This is currently a no-op. In future releases of Bazel, if this
is set to False, this function will return None rather than fail if no
toolchain is found.
Returns:
A CcToolchainProvider.
"""
# 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:
# 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.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.
Usage:
```
my_rule = rule(
toolchains = [other toolchain types] + use_cpp_toolchain(),
)
```
Args:
mandatory: Whether or not it should be an error if the toolchain cannot be resolved.
Returns:
A list that can be used as the value for `rule.toolchains`.
"""
return [config_common.toolchain_type(CPP_TOOLCHAIN_TYPE, mandatory = mandatory)]