Add toolchain_rule to enable rule authors to define toolchains.

Change-Id: I407240708f4aacc89ec5c00bf3e8ff46a1d6d6d6
PiperOrigin-RevId: 152692981

src/create_embedded_tools.sh

@@ -42,6 +42,7 @@ for i in $*; do
   case "$i" in
     *tools/jdk/BUILD*) OUTPUT_PATH=tools/jdk/BUILD ;;
     *tools/platforms/platforms.BUILD) OUTPUT_PATH=platforms/BUILD ;;
+    *tools/platforms/*) OUTPUT_PATH=platforms/${i##*/} ;;
     *JavaBuilder*_deploy.jar) OUTPUT_PATH=tools/jdk/${i##*/} ;;
     *JacocoCoverage*_deploy.jar) OUTPUT_PATH=tools/jdk/JacocoCoverage_deploy.jar ;;
     *turbine_deploy.jar) OUTPUT_PATH=tools/jdk/turbine_deploy.jar ;;

src/main/java/com/google/devtools/build/lib/rules/platform/PlatformCommon.java

@@ -62,7 +62,7 @@ public ClassObjectConstructor getConstraintSettingInfoConstructor() {
   public ClassObjectConstructor getConstraintValueInfoConstructor() {
     return ConstraintValueInfo.SKYLARK_CONSTRUCTOR;
   }
-
+  
   @SkylarkCallable(
       name = ToolchainInfo.SKYLARK_NAME,
       doc = "The key used to retrieve the provider containing toolchain data.",

src/test/shell/bazel/BUILD

@@ -434,6 +434,13 @@ sh_test(
     data = [":test-deps"],
 )
 
+sh_test(
+    name = "toolchain_test",
+    size = "small",
+    srcs = ["toolchain_test.sh"],
+    data = [":test-deps"],
+)
+
 test_suite(
     name = "all_tests",
     visibility = ["//visibility:public"],

src/test/shell/bazel/toolchain_test.sh

@@ -0,0 +1,150 @@
+#!/bin/bash
+#
+# Copyright 2017 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.
+#
+# Test the providers and rules related to toolchains.
+#
+
+# Load the test setup defined in the parent directory
+CURRENT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "${CURRENT_DIR}/../integration_test_setup.sh" \
+  || { echo "integration_test_setup.sh not found!" >&2; exit 1; }
+
+function set_up() {
+  create_new_workspace
+
+  # Create shared constraints.
+  mkdir -p constraints
+  cat >>constraints/BUILD <<EOF
+package(default_visibility = ['//visibility:public'])
+constraint_setting(name = 'os')
+constraint_value(name = 'linux',
+    constraint_setting = ':os')
+constraint_value(name = 'mac',
+    constraint_setting = ':os')
+EOF
+
+  # Create shared report rule for printing info.
+  mkdir report
+  touch report/BUILD
+  cat >>report/report.bzl <<EOF
+def _report_impl(ctx):
+  toolchain = ctx.attr.toolchain[platform_common.ToolchainInfo]
+  for field in ctx.attr.fields:
+    value = getattr(toolchain, field)
+    if type(value) == 'Target':
+      value = value.label
+    print('%s = "%s"' % (field, value))
+
+report_toolchain = rule(
+  _report_impl,
+  attrs = {
+    'fields': attr.string_list(),
+    'toolchain': attr.label(providers = [platform_common.ToolchainInfo]),
+  }
+)
+EOF
+}
+
+function test_toolchain_rule() {
+
+  mkdir -p toolchain
+  cat >> toolchain/toolchain.bzl <<EOF
+load('@bazel_tools//platforms:toolchains.bzl', 'toolchain_rule')
+test_toolchain = toolchain_rule(
+    extra_attrs = {
+       'extra_label': attr.label(),
+       'extra_str': attr.string(),
+    }
+)
+EOF
+
+  cat >> toolchain/BUILD <<EOF
+load('//report:report.bzl', 'report_toolchain')
+load(':toolchain.bzl', 'test_toolchain')
+filegroup(name = 'dep_rule')
+test_toolchain(
+    name = 'linux_toolchain',
+    exec_compatible_with = [
+      '//constraints:linux',
+    ],
+    target_compatible_with = [
+      '//constraints:mac',
+    ],
+    extra_label = ':dep_rule',
+    extra_str = 'bar',
+)
+report_toolchain(
+  name = 'report',
+  fields = ['extra_label', 'extra_str'],
+  toolchain = ':linux_toolchain',
+)
+EOF
+
+  bazel build //toolchain:report &> $TEST_log || fail "Build failed"
+  expect_log 'extra_label = "//toolchain:dep_rule"'
+  expect_log 'extra_str = "bar"'
+}
+
+function test_toolchain_rule_override_impl() {
+
+  mkdir -p toolchain
+  cat >> toolchain/toolchain.bzl <<EOF
+load('@bazel_tools//platforms:toolchains.bzl', 'toolchain_rule', 'default_toolchain_rule_impl')
+def _impl(ctx):
+  overridde_attrs = {
+    'extra_label': 'override:' + ctx.attr.extra_str,
+    'extra_str': 'foo',
+  }
+  return default_toolchain_rule_impl(ctx, overridde_attrs)
+
+test_toolchain = toolchain_rule(
+    implementation = _impl,
+    extra_attrs = {
+       'extra_label': attr.label(),
+       'extra_str': attr.string(),
+    }
+)
+
+EOF
+
+  cat >> toolchain/BUILD <<EOF
+load('//report:report.bzl', 'report_toolchain')
+load(':toolchain.bzl', 'test_toolchain')
+filegroup(name = 'dep_rule')
+test_toolchain(
+    name = 'linux_toolchain',
+    exec_compatible_with = [
+      '//constraints:linux',
+    ],
+    target_compatible_with = [
+      '//constraints:mac',
+    ],
+    extra_label = ':dep_rule',
+    extra_str = 'bar',
+)
+report_toolchain(
+  name = 'report',
+  fields = ['extra_label', 'extra_str'],
+  toolchain = ':linux_toolchain',
+)
+EOF
+
+  bazel build //toolchain:report &> $TEST_log || fail "Build failed"
+  expect_log 'extra_label = "override:bar"'
+  expect_log 'extra_str = "foo"'
+}
+
+run_suite "toolchain tests"

tools/platforms/BUILD

@@ -6,6 +6,7 @@ filegroup(
     name = "package-srcs",
     srcs = [
         "platforms.BUILD",
+        "toolchains.bzl",
     ],
 )
 

tools/platforms/platforms.BUILD

@@ -4,6 +4,8 @@ package(
     default_visibility = ["//visibility:public"],
 )
 
+export_files = ["toolchains.bzl"]
+
 # These match values in //src/main/java/com/google/build/lib/util:CPU.java
 constraint_setting(name = "cpu")
 

tools/platforms/toolchains.bzl

@@ -0,0 +1,63 @@
+# Copyright 2017 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.
+"""Useful functions and rules for defining toolchains."""
+
+_default_toolchain_rule_attrs = {
+    "exec_compatible_with": attr.label_list(
+        providers = [platform_common.ConstraintValueInfo]),
+    "target_compatible_with": attr.label_list(
+        providers = [platform_common.ConstraintValueInfo]),
+}
+
+def default_toolchain_rule_impl(ctx, override_attrs = {}):
+  """A default implementation for toolchain_rule.
+  This implementation creates a toolchain provider and adds all extra
+  attributes.
+
+  Args:
+    ctx: The rule context.
+    override_attrs: Any data in this dict will override the corresponding
+      attribute from the context. toolchain_rule implementations can use this
+      to customize the values set in the provider.
+
+  Returns:
+    The created toolchain provider.
+  """
+  toolchain_data = {}
+
+  # Collect the extra_args from ctx.attrs.
+  attr_names = ctx.attr._extra_attr_names
+  for name in attr_names:
+    if name in override_attrs:
+      attr = override_attrs[name]
+    else:
+      attr = getattr(ctx.attr, name)
+    toolchain_data[name] = attr
+
+  toolchain = platform_common.toolchain(
+      exec_compatible_with = ctx.attr.exec_compatible_with,
+      target_compatible_with = ctx.attr.target_compatible_with,
+      **toolchain_data)
+
+  return [toolchain]
+
+def toolchain_rule(implementation = default_toolchain_rule_impl, fragments = [], extra_attrs = {}):
+  return rule(
+      implementation = implementation,
+      attrs = _default_toolchain_rule_attrs + extra_attrs + {
+          # default_toolchain_rule_impl needs this to know what attributes are extra args.
+          "_extra_attr_names": attr.string_list(default = extra_attrs.keys()),
+      },
+      fragments = fragments,
+  )