toolchains/fail_rule.bzl

# Copyright 2020 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
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"""A rule than fails during analysis."""

def _fail_rule_impl(ctx):
    if ctx.attr.header:
        fail("%s %s" % (ctx.attr.header, ctx.attr.message))
    else:
        fail(ctx.attr.message)

fail_rule = rule(
    doc = "A rule that fails during analysis.",
    implementation = _fail_rule_impl,
    attrs = {
        "header": attr.string(
            doc = "Header of the message.",
        ),
        "message": attr.string(
            mandatory = True,
            doc = "Message to display.",
        ),
    },
)