toolchains/java_toolchain_alias.bzl

# Copyright 2019 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.

"""Experimental re-implementations of Java toolchain aliases using toolchain resolution."""

def _java_runtime_alias(ctx):
    """An experimental implementation of java_runtime_alias using toolchain resolution."""
    toolchain_info = ctx.toolchains["@bazel_tools//tools/jdk:runtime_toolchain_type"]
    toolchain = toolchain_info.java_runtime
    return [
        toolchain_info,
        toolchain,
        platform_common.TemplateVariableInfo({
            "JAVA": str(toolchain.java_executable_exec_path),
            "JAVABASE": str(toolchain.java_home),
        }),
        # See b/65239471 for related discussion of handling toolchain runfiles/data.
        DefaultInfo(
            runfiles = ctx.runfiles(transitive_files = toolchain.files),
            files = toolchain.files,
        ),
    ]

java_runtime_alias = rule(
    implementation = _java_runtime_alias,
    toolchains = ["@bazel_tools//tools/jdk:runtime_toolchain_type"],
)

def _java_host_runtime_alias(ctx):
    """An experimental implementation of java_host_runtime_alias using toolchain resolution."""
    runtime = ctx.attr._runtime
    java_runtime = runtime[java_common.JavaRuntimeInfo]
    template_variable_info = runtime[platform_common.TemplateVariableInfo]
    toolchain_info = platform_common.ToolchainInfo(java_runtime = java_runtime)
    return [
        java_runtime,
        template_variable_info,
        toolchain_info,
        runtime[DefaultInfo],
    ]

java_host_runtime_alias = rule(
    implementation = _java_host_runtime_alias,
    attrs = {
        "_runtime": attr.label(
            default = Label("//toolchains:current_java_runtime"),
            providers = [
                java_common.JavaRuntimeInfo,
                platform_common.TemplateVariableInfo,
            ],
            cfg = "exec",
        ),
    },
    provides = [
        java_common.JavaRuntimeInfo,
        platform_common.TemplateVariableInfo,
        platform_common.ToolchainInfo,
    ],
)

def _java_runtime_transition_impl(_settings, attr):
    return {"//command_line_option:java_runtime_version": attr.runtime_version}

_java_runtime_transition = transition(
    implementation = _java_runtime_transition_impl,
    inputs = [],
    outputs = ["//command_line_option:java_runtime_version"],
)

java_runtime_version_alias = rule(
    implementation = _java_runtime_alias,
    toolchains = ["@bazel_tools//tools/jdk:runtime_toolchain_type"],
    attrs = {
        "runtime_version": attr.string(mandatory = True),
    },
    cfg = _java_runtime_transition,
)

def _java_toolchain_alias(ctx):
    """An experimental implementation of java_toolchain_alias using toolchain resolution."""
    toolchain_info = ctx.toolchains["@bazel_tools//tools/jdk:toolchain_type"]
    toolchain = toolchain_info.java

    # buildifier: disable=rule-impl-return
    return struct(
        providers = [
            toolchain_info,
            toolchain,
        ],
        # Use the legacy provider syntax for compatibility with the native rules.
        java_toolchain = toolchain,
    )

java_toolchain_alias = rule(
    implementation = _java_toolchain_alias,
    toolchains = ["@bazel_tools//tools/jdk:toolchain_type"],
)