mirror of https://github.com/bazelbuild/rules_cc
70 lines
2.7 KiB
Python
70 lines
2.7 KiB
Python
# pylint: disable=g-bad-file-header
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# Copyright 2016 The Bazel Authors. All rights reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""
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Returns the current `CcToolchainInfo`.
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* When https://github.com/bazelbuild/bazel/issues/7260 is **not** flipped, current
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C++ toolchain is selected using the legacy mechanism (`--crosstool_top`,
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`--cpu`, `--compiler`). For that to work the rule needs to declare an
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`_cc_toolchain` attribute, e.g.
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foo = rule(
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implementation = _foo_impl,
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attrs = {
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"_cc_toolchain": attr.label(default = Label("@bazel_tools//tools/cpp:current_cc_toolchain")),
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},
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)
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* When https://github.com/bazelbuild/bazel/issues/7260 **is** flipped, current
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C++ toolchain is selected using the toolchain resolution mechanism
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(`--platforms`). For that to work the rule needs to declare a dependency on
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C++ toolchain type:
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foo = rule(
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implementation = _foo_impl,
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toolchains = ["@rules_cc//cc:toolchain_type"],
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)
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We advise to depend on both `_cc_toolchain` attr and
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`@rules_cc//cc:toolchain_type` for the duration of the migration. After
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https://github.com/bazelbuild/bazel/issues/7260 is flipped (and support for old
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Bazel version is not needed), it's enough to only keep the
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`@rules_cc//cc:toolchain_type`.
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"""
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def find_cc_toolchain(ctx):
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"""
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Returns the current `CcToolchainInfo`.
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Args:
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ctx: The rule context for which to find a toolchain.
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Returns:
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A CcToolchainInfo.
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"""
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# Check the incompatible flag for toolchain resolution.
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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):
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if "//cc:toolchain_type" in ctx.toolchains:
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return ctx.toolchains["//cc:toolchain_type"]
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fail("In order to use find_cc_toolchain, you must include the '@rules_cc//cc:toolchain_type' in the toolchains argument to your rule.")
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# Fall back to the legacy implicit attribute lookup.
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if hasattr(ctx.attr, "_cc_toolchain"):
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return ctx.attr._cc_toolchain[cc_common.CcToolchainInfo]
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# We didn't find anything.
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fail("In order to use find_ccc_toolchain, you must define the '_cc_toolchain' attribute on your rule or aspect.")
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