1 files changed, 61 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleCrosstoolSplitTransition.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleCrosstoolSplitTransition.java
new file mode 100644
index 0000000000..8e919c088a
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleCrosstoolSplitTransition.java
@@ -0,0 +1,61 @@
+// 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.objc;
+
+import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.analysis.config.BuildOptions;
+import com.google.devtools.build.lib.packages.Attribute.SplitTransition;
+import com.google.devtools.build.lib.rules.apple.AppleCommandLineOptions;
+import com.google.devtools.build.lib.rules.apple.AppleConfiguration.ConfigurationDistinguisher;
+import java.util.List;
+
+/**
+ * Transition that produces a configuration that causes c++ toolchain selection to use the
+ * CROSSTOOL given in apple_crosstool_top.
+ *
+ * <p>Duplicates {@link AppleCrosstoolTransition} as a {@link SplitTransition}.  This is necessary
+ * for the top level configuration hook, until the top level configuration hook is supported for
+ * dynamic configurations.
+ *
+ * <p>TODO(b/34241319): Use AppleCrosstoolTransition at the top level, and retire this class.
+ */
+public class AppleCrosstoolSplitTransition implements SplitTransition<BuildOptions> {
+
+  /**
+   * A singleton instance of {@link AppleCrosstoolSplitTransition}, since the class must be
+   * stateless.  Use in BuildConfigurationCollection.Transitions#topLevelConfigurationHook.
+   */
+  public static final AppleCrosstoolSplitTransition APPLE_CROSSTOOL_SPLIT_TRANSITION =
+      new AppleCrosstoolSplitTransition();
+
+  @Override
+  public boolean defaultsToSelf() {
+    return true;
+  }
+
+  @Override
+  public List<BuildOptions> split(BuildOptions buildOptions) {
+    BuildOptions result = buildOptions.clone();
+    result.get(AppleCommandLineOptions.class).configurationDistinguisher =
+        ConfigurationDistinguisher.APPLE_CROSSTOOL;
+
+    // TODO(b/29355778): Once ios_cpu is retired, introduce another top-level flag (perhaps
+    // --apple_cpu) for toolchain selection in top-level consuming rules.
+    String cpu = "ios_" + buildOptions.get(AppleCommandLineOptions.class).iosCpu;
+    AppleCrosstoolTransition.setAppleCrosstoolTransitionConfiguration(buildOptions, result, cpu);
+
+    return ImmutableList.of(result);
+  }
+}