Add an xcode_config_alias rule that is an alias to the current xcode_config rule in use and expose data in XcodeConfigProvider to Skylark.

This gives us a way to discover Xcode version information from Skylark in a way other than by AppleConfiguration, which in turn makes it possible to remove said data (and thus dependencies on BUILD files) from AppleConfiguration.

Work towards https://github.com/bazelbuild/bazel/issues/3424 .

RELNOTES: None.
PiperOrigin-RevId: 166311454

1 files changed, 85 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfigAlias.java b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfigAlias.java
new file mode 100644
index 0000000000..f3b56a5238
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfigAlias.java
@@ -0,0 +1,85 @@
+// 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.
+
+package com.google.devtools.build.lib.rules.apple;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.analysis.AliasProvider;
+import com.google.devtools.build.lib.analysis.BaseRuleClasses;
+import com.google.devtools.build.lib.analysis.ConfiguredTarget;
+import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
+import com.google.devtools.build.lib.analysis.RuleConfiguredTargetFactory;
+import com.google.devtools.build.lib.analysis.RuleContext;
+import com.google.devtools.build.lib.analysis.RuleDefinition;
+import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
+import com.google.devtools.build.lib.analysis.VisibilityProvider;
+import com.google.devtools.build.lib.analysis.VisibilityProviderImpl;
+import com.google.devtools.build.lib.packages.RuleClass;
+import com.google.devtools.build.lib.rules.AliasConfiguredTarget;
+
+/**
+ * Implementation of the {@code xcode_config_alias} rule.
+ *
+ * <p>This rule is an alias to the {@code xcode_config} rule currently in use, which is in turn
+ * depends on the current configuration, in particular, the value of the {@code --xcode_config}
+ * flag.
+ */
+public class XcodeConfigAlias implements RuleConfiguredTargetFactory {
+  @Override
+  public ConfiguredTarget create(RuleContext ruleContext)
+      throws InterruptedException, RuleErrorException {
+    ConfiguredTarget actual = (ConfiguredTarget) ruleContext.getPrerequisite(
+        XcodeConfigRule.XCODE_CONFIG_ATTR_NAME, Mode.TARGET);
+    return new AliasConfiguredTarget(
+        ruleContext,
+        actual,
+        ImmutableMap.of(
+            AliasProvider.class,
+            AliasProvider.fromAliasRule(ruleContext.getLabel(), actual),
+            VisibilityProvider.class,
+            new VisibilityProviderImpl(ruleContext.getVisibility())));
+  }
+
+  /**
+   * Rule definition for the {@code xcode_config_alias} rule.
+   *
+   * <p>This rule is an alias to the {@code xcode_config} rule currently in use, which is in turn
+   * depends on the current configuration, in particular, the value of the {@code --xcode_config}
+   * flag.
+   *
+   * <p>This is intentionally undocumented for users; the workspace is expected to contain exactly
+   * one instance of this rule under {@code @bazel_tools//tools/osx} and people who want to get
+   * data this rule provides should depend on that one.
+   */
+  public static class XcodeConfigAliasRule implements RuleDefinition {
+
+    @Override
+    public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment environment) {
+      return builder
+          .requiresConfigurationFragments(AppleConfiguration.class)
+          .removeAttribute("licenses")
+          .removeAttribute("distribs")
+          .build();
+    }
+
+    @Override
+    public Metadata getMetadata() {
+      return Metadata.builder()
+          .name("xcode_config_alias")
+          .ancestors(BaseRuleClasses.BaseRule.class, AppleToolchain.RequiresXcodeConfigRule.class)
+          .factoryClass(XcodeConfigAlias.class)
+          .build();
+    }
+  }
+}