Refactor apple multi-arch platform-specific split transition and rule classes to be reusable for apple_static_library and apple_dynamic_library

--
MOS_MIGRATED_REVID=132066681

6 files changed, 238 insertions, 176 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProvider.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProvider.java
index 20a01ada1b..f2678a6a8b 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProvider.java
@@ -439,6 +439,7 @@ public class BazelRuleClassProvider {
     builder.addRuleDefinition(new ObjcRuleClasses.SimulatorRule());
     builder.addRuleDefinition(new ObjcRuleClasses.CompilingRule());
     builder.addRuleDefinition(new ObjcRuleClasses.LinkingRule(objcProtoAspect));
+    builder.addRuleDefinition(new ObjcRuleClasses.MultiArchPlatformRule());
     builder.addRuleDefinition(new ObjcRuleClasses.ResourcesRule());
     builder.addRuleDefinition(new ObjcRuleClasses.XcodegenRule());
     builder.addRuleDefinition(new ObjcRuleClasses.AlwaysLinkRule());
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleBinary.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleBinary.java
index b5855192c3..0764430efa 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleBinary.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleBinary.java
@@ -15,14 +15,11 @@
 package com.google.devtools.build.lib.rules.objc;
 
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.MULTI_ARCH_LINKED_BINARIES;
-import static com.google.devtools.build.lib.syntax.Type.STRING;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Optional;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableListMultimap;
-import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.ConfiguredTarget;
 import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
@@ -30,16 +27,9 @@ import com.google.devtools.build.lib.analysis.RuleConfiguredTargetBuilder;
 import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.analysis.TransitiveInfoCollection;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
-import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
-import com.google.devtools.build.lib.packages.Attribute.SplitTransition;
-import com.google.devtools.build.lib.packages.Attribute.SplitTransitionProvider;
-import com.google.devtools.build.lib.packages.NonconfigurableAttributeMapper;
-import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.rules.RuleConfiguredTargetFactory;
-import com.google.devtools.build.lib.rules.apple.AppleCommandLineOptions;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
-import com.google.devtools.build.lib.rules.apple.AppleConfiguration.ConfigurationDistinguisher;
 import com.google.devtools.build.lib.rules.apple.Platform.PlatformType;
 import com.google.devtools.build.lib.rules.cpp.CcToolchainProvider;
 import com.google.devtools.build.lib.rules.objc.CompilationSupport.ExtraLinkArgs;
@@ -52,28 +42,14 @@ import java.util.Set;
  */
 public class AppleBinary implements RuleConfiguredTargetFactory {
 
-  /**
-   * {@link SplitTransitionProvider} instance for the apple binary rule. (This is exposed for
-   * convenience as a single static instance as it possesses no internal state.)
-   */
-  public static final AppleBinaryTransitionProvider SPLIT_TRANSITION_PROVIDER =
-      new AppleBinaryTransitionProvider();
-
   @VisibleForTesting
   static final String REQUIRES_AT_LEAST_ONE_SOURCE_FILE =
       "At least one source file is required (srcs, non_arc_srcs, or precompiled_srcs).";
 
-  @VisibleForTesting
-  static final String UNSUPPORTED_PLATFORM_TYPE_ERROR_FORMAT =
-      "Unsupported platform type \"%s\"";
-
-  private static final ImmutableSet<PlatformType> SUPPORTED_APPLE_BINARY_PLATFORM_TYPES =
-      ImmutableSet.of(PlatformType.IOS, PlatformType.WATCHOS);
-
   @Override
   public final ConfiguredTarget create(RuleContext ruleContext)
       throws InterruptedException, RuleErrorException {
-    PlatformType platformType = getPlatformType(ruleContext);
+    PlatformType platformType = MultiArchSplitTransitionProvider.getPlatformType(ruleContext);
     ImmutableListMultimap<BuildConfiguration, ObjcProvider> configurationToNonPropagatedObjcMap =
         ruleContext.getPrerequisitesByConfiguration("non_propagated_deps", Mode.SPLIT,
             ObjcProvider.class);
@@ -211,123 +187,4 @@ public class AppleBinary implements RuleConfiguredTargetFactory {
 
     return configToProvider.keySet();
   }
-
-  private static PlatformType getPlatformType(RuleContext ruleContext) throws RuleErrorException {
-    try {
-      return getPlatformType(
-          ruleContext.attributes().get(AppleBinaryRule.PLATFORM_TYPE_ATTR_NAME, STRING));
-    } catch (IllegalArgumentException exception) {
-      throw ruleContext.throwWithAttributeError(AppleBinaryRule.PLATFORM_TYPE_ATTR_NAME,
-          String.format(UNSUPPORTED_PLATFORM_TYPE_ERROR_FORMAT,
-              ruleContext.attributes().get(AppleBinaryRule.PLATFORM_TYPE_ATTR_NAME, STRING)));
-    }
-  }
-
-  private static PlatformType getPlatformType(String platformTypeString) {
-    PlatformType platformType = PlatformType.fromString(platformTypeString);
-
-    if (!SUPPORTED_APPLE_BINARY_PLATFORM_TYPES.contains(platformType)) {
-      throw new IllegalArgumentException(
-          String.format(UNSUPPORTED_PLATFORM_TYPE_ERROR_FORMAT, platformTypeString));
-    } else {
-      return platformType;
-    }
-  }
-
-  /**
-   * {@link SplitTransitionProvider} implementation for the apple binary rule.
-   */
-  public static class AppleBinaryTransitionProvider implements SplitTransitionProvider {
-
-    private static final ImmutableMap<PlatformType, AppleBinaryTransition>
-        SPLIT_TRANSITIONS_BY_TYPE = ImmutableMap.<PlatformType, AppleBinaryTransition>builder()
-            .put(PlatformType.IOS, new AppleBinaryTransition(PlatformType.IOS))
-            .put(PlatformType.WATCHOS, new AppleBinaryTransition(PlatformType.WATCHOS))
-            .build();
-
-    @Override
-    public SplitTransition<?> apply(Rule fromRule) {
-      String platformTypeString = NonconfigurableAttributeMapper.of(fromRule)
-          .get(AppleBinaryRule.PLATFORM_TYPE_ATTR_NAME, STRING);
-      PlatformType platformType;
-      try {
-        platformType = getPlatformType(platformTypeString);
-      } catch (IllegalArgumentException exception) {
-        // There's no opportunity to propagate exception information up cleanly at the transition
-        // provider level. This will later be registered as a rule error during the initialization
-        // of the apple_binary target.
-        platformType = PlatformType.IOS;
-      }
-
-      return SPLIT_TRANSITIONS_BY_TYPE.get(platformType);
-    }
-
-    public List<SplitTransition<BuildOptions>> getPotentialSplitTransitions() {
-      return ImmutableList.<SplitTransition<BuildOptions>>copyOf(
-          SPLIT_TRANSITIONS_BY_TYPE.values());
-    }
-  }
-
-  /**
-   * Transition that results in one configured target per architecture specified in {@code
-   * --ios_multi_cpus}.
-   */
-  protected static class AppleBinaryTransition implements SplitTransition<BuildOptions> {
-
-    private final PlatformType platformType;
-
-    public AppleBinaryTransition(PlatformType platformType) {
-      this.platformType = platformType;
-    }
-
-    @Override
-    public final List<BuildOptions> split(BuildOptions buildOptions) {
-      List<String> cpus;
-      ConfigurationDistinguisher configurationDistinguisher;
-      switch (platformType) {
-        case IOS:
-          cpus = buildOptions.get(AppleCommandLineOptions.class).iosMultiCpus;
-          configurationDistinguisher = ConfigurationDistinguisher.APPLEBIN_IOS;
-          break;
-        case WATCHOS:
-          cpus = buildOptions.get(AppleCommandLineOptions.class).watchosCpus;
-          if (cpus.isEmpty()) {
-            cpus = ImmutableList.of(AppleCommandLineOptions.DEFAULT_WATCHOS_CPU);
-          }
-          configurationDistinguisher = ConfigurationDistinguisher.APPLEBIN_WATCHOS;
-          break;
-        default:
-          throw new IllegalArgumentException("Unsupported platform type " + platformType);
-      }
-
-      ImmutableList.Builder<BuildOptions> splitBuildOptions = ImmutableList.builder();
-      for (String cpu : cpus) {
-        BuildOptions splitOptions = buildOptions.clone();
-
-        splitOptions.get(AppleCommandLineOptions.class).applePlatformType = platformType;
-        splitOptions.get(AppleCommandLineOptions.class).appleSplitCpu = cpu;
-        // Set for backwards compatibility with rules that depend on this flag, even when
-        // ios is not the platform type.
-        // TODO(b/28958783): Clean this up.
-        splitOptions.get(AppleCommandLineOptions.class).iosCpu = cpu;
-        if (splitOptions.get(ObjcCommandLineOptions.class).enableCcDeps) {
-          // Only set the (CC-compilation) CPU for dependencies if explicitly required by the user.
-          // This helps users of the iOS rules who do not depend on CC rules as these CPU values
-          // require additional flags to work (e.g. a custom crosstool) which now only need to be
-          // set if this feature is explicitly requested.
-          splitOptions.get(BuildConfiguration.Options.class).cpu =
-              String.format("%s_%s", platformType, cpu);
-        }
-        splitOptions.get(AppleCommandLineOptions.class).configurationDistinguisher =
-            configurationDistinguisher;
-        splitBuildOptions.add(splitOptions);
-      }
-      return splitBuildOptions.build();
-    }
-
-    @Override
-    public boolean defaultsToSelf() {
-      return true;
-    }
-  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleBinaryRule.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleBinaryRule.java
index f6b5c141e2..d09c494322 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleBinaryRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleBinaryRule.java
@@ -15,10 +15,8 @@
 package com.google.devtools.build.lib.rules.objc;
 
 import static com.google.devtools.build.lib.packages.Attribute.attr;
-import static com.google.devtools.build.lib.packages.BuildType.LABEL;
 import static com.google.devtools.build.lib.packages.ImplicitOutputsFunction.fromTemplates;
 import static com.google.devtools.build.lib.syntax.Type.BOOLEAN;
-import static com.google.devtools.build.lib.syntax.Type.STRING;
 
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.RuleDefinition;
@@ -28,7 +26,6 @@ import com.google.devtools.build.lib.packages.ImplicitOutputsFunction.SafeImplic
 import com.google.devtools.build.lib.packages.RuleClass;
 import com.google.devtools.build.lib.packages.RuleClass.Builder;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
-import com.google.devtools.build.lib.rules.apple.Platform.PlatformType;
 
 /**
  * Rule definition for apple_binary.
@@ -49,37 +46,15 @@ public class AppleBinaryRule implements RuleDefinition {
 
   @Override
   public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
+    MultiArchSplitTransitionProvider splitTransitionProvider =
+        new MultiArchSplitTransitionProvider();
     return builder
         .requiresConfigurationFragments(
             ObjcConfiguration.class, J2ObjcConfiguration.class, AppleConfiguration.class)
         .add(attr("$is_executable", BOOLEAN).value(true)
             .nonconfigurable("Called from RunCommand.isExecutable, which takes a Target"))
-        .override(builder.copy("deps").cfg(AppleBinary.SPLIT_TRANSITION_PROVIDER))
-        .override(builder.copy("non_propagated_deps").cfg(AppleBinary.SPLIT_TRANSITION_PROVIDER))
-        // This is currently a hack to obtain all child configurations regardless of the attribute
-        // values of this rule -- this rule does not currently use the actual info provided by
-        // this attribute.
-        .add(attr(":cc_toolchain", LABEL)
-            .cfg(AppleBinary.SPLIT_TRANSITION_PROVIDER)
-            .value(ObjcRuleClasses.APPLE_TOOLCHAIN))
-        /* <!-- #BLAZE_RULE(apple_binary).ATTRIBUTE(platform_type) -->
-        The type of platform for which to create multi-architecture "fat" binaries in this rule.
-        For example, if <code>ios</code> is selected, then fat binaries will be created 
-        combining all architectures specified in <code>--ios_multi_cpus</code>.
-
-        Options are:
-        <ul>
-          <li>
-            <code>ios</code> (default): architectures gathered from <code>--ios_multi_cpus</code>.
-          </li>
-          <li>
-            <code>watchos</code>: architectures gathered from <code>--watchos_multi_cpus</code>
-          </li>
-        </ul>
-        <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
-        .add(attr(PLATFORM_TYPE_ATTR_NAME, STRING)
-            .value(PlatformType.IOS.toString())
-            .nonconfigurable("Determines the configuration transition on deps"))
+        .override(builder.copy("deps").cfg(splitTransitionProvider))
+        .override(builder.copy("non_propagated_deps").cfg(splitTransitionProvider))
         /*<!-- #BLAZE_RULE(apple_binary).IMPLICIT_OUTPUTS -->
         <ul>
          <li><code><var>name</var>_lipobin</code>: the 'lipo'ed potentially multi-architecture
@@ -97,7 +72,7 @@ public class AppleBinaryRule implements RuleDefinition {
         .name("apple_binary")
         .factoryClass(AppleBinary.class)
         .ancestors(BaseRuleClasses.BaseRule.class, ObjcRuleClasses.LinkingRule.class,
-            ObjcRuleClasses.SimulatorRule.class)
+            ObjcRuleClasses.MultiArchPlatformRule.class, ObjcRuleClasses.SimulatorRule.class)
         .build();
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/MultiArchSplitTransitionProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/MultiArchSplitTransitionProvider.java
new file mode 100644
index 0000000000..35026f38a5
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/MultiArchSplitTransitionProvider.java
@@ -0,0 +1,178 @@
+// Copyright 2016 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 static com.google.devtools.build.lib.syntax.Type.STRING;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.analysis.RuleContext;
+import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
+import com.google.devtools.build.lib.analysis.config.BuildOptions;
+import com.google.devtools.build.lib.packages.Attribute.SplitTransition;
+import com.google.devtools.build.lib.packages.Attribute.SplitTransitionProvider;
+import com.google.devtools.build.lib.packages.NonconfigurableAttributeMapper;
+import com.google.devtools.build.lib.packages.Rule;
+import com.google.devtools.build.lib.packages.RuleClass.ConfiguredTargetFactory.RuleErrorException;
+import com.google.devtools.build.lib.rules.apple.AppleCommandLineOptions;
+import com.google.devtools.build.lib.rules.apple.AppleConfiguration.ConfigurationDistinguisher;
+import com.google.devtools.build.lib.rules.apple.Platform.PlatformType;
+import java.util.List;
+
+/**
+ * {@link SplitTransitionProvider} implementation for multi-architecture apple rules which can
+ * accept different apple platform types (such as ios or watchos).
+ */
+public class MultiArchSplitTransitionProvider implements SplitTransitionProvider {
+  
+  @VisibleForTesting
+  static final String UNSUPPORTED_PLATFORM_TYPE_ERROR_FORMAT =
+      "Unsupported platform type \"%s\"";
+  
+  private static final ImmutableSet<PlatformType> SUPPORTED_PLATFORM_TYPES =
+      ImmutableSet.of(PlatformType.IOS, PlatformType.WATCHOS);
+
+  /**
+   * Returns the apple platform type in the current rule context.
+   * 
+   * @throws RuleErrorException if the platform type attribute in the current rulecontext is
+   *     an invalid value
+   */
+  public static PlatformType getPlatformType(RuleContext ruleContext) throws RuleErrorException {
+    String attributeValue =
+        ruleContext.attributes().get(AppleBinaryRule.PLATFORM_TYPE_ATTR_NAME, STRING);
+    try {
+      return getPlatformType(attributeValue);
+    } catch (IllegalArgumentException exception) {
+      throw ruleContext.throwWithAttributeError(AppleBinaryRule.PLATFORM_TYPE_ATTR_NAME,
+          String.format(UNSUPPORTED_PLATFORM_TYPE_ERROR_FORMAT, attributeValue));
+    }
+  }
+
+  /**
+   * Returns the apple platform type for the given platform type string (corresponding directly
+   * with platform type attribute value).
+   * 
+   * @throws IllegalArgumentException if the given platform type string is not a valid type
+   */
+  public static PlatformType getPlatformType(String platformTypeString) {
+    PlatformType platformType = PlatformType.fromString(platformTypeString);
+
+    if (!SUPPORTED_PLATFORM_TYPES.contains(platformType)) {
+      throw new IllegalArgumentException(
+          String.format(UNSUPPORTED_PLATFORM_TYPE_ERROR_FORMAT, platformTypeString));
+    } else {
+      return platformType;
+    }
+  }
+
+  private static final ImmutableMap<PlatformType, AppleBinaryTransition>
+      SPLIT_TRANSITIONS_BY_TYPE = ImmutableMap.<PlatformType, AppleBinaryTransition>builder()
+          .put(PlatformType.IOS, new AppleBinaryTransition(PlatformType.IOS))
+          .put(PlatformType.WATCHOS, new AppleBinaryTransition(PlatformType.WATCHOS))
+          .build();
+
+  @Override
+  public SplitTransition<?> apply(Rule fromRule) {
+    String platformTypeString = NonconfigurableAttributeMapper.of(fromRule)
+        .get(AppleBinaryRule.PLATFORM_TYPE_ATTR_NAME, STRING);
+    PlatformType platformType;
+    try {
+      platformType = getPlatformType(platformTypeString);
+    } catch (IllegalArgumentException exception) {
+      // There's no opportunity to propagate exception information up cleanly at the transition
+      // provider level. This should later be registered as a rule error during the initialization
+      // of the rule.
+      platformType = PlatformType.IOS;
+    }
+
+    return SPLIT_TRANSITIONS_BY_TYPE.get(platformType);
+  }
+
+  /**
+   * Returns the full list of potential split transitions this split transition provider may
+   * produce.
+   */
+  public static List<SplitTransition<BuildOptions>> getPotentialSplitTransitions() {
+    return ImmutableList.<SplitTransition<BuildOptions>>copyOf(
+        SPLIT_TRANSITIONS_BY_TYPE.values());
+  }
+
+  /**
+   * Transition that results in one configured target per architecture specified in the
+   * platform-specific cpu flag for a particular platform type (for example, --watchos_cpus
+   * for watchos platform type).
+   */
+  protected static class AppleBinaryTransition implements SplitTransition<BuildOptions> {
+
+    private final PlatformType platformType;
+
+    public AppleBinaryTransition(PlatformType platformType) {
+      this.platformType = platformType;
+    }
+
+    @Override
+    public final List<BuildOptions> split(BuildOptions buildOptions) {
+      List<String> cpus;
+      ConfigurationDistinguisher configurationDistinguisher;
+      switch (platformType) {
+        case IOS:
+          cpus = buildOptions.get(AppleCommandLineOptions.class).iosMultiCpus;
+          configurationDistinguisher = ConfigurationDistinguisher.APPLEBIN_IOS;
+          break;
+        case WATCHOS:
+          cpus = buildOptions.get(AppleCommandLineOptions.class).watchosCpus;
+          if (cpus.isEmpty()) {
+            cpus = ImmutableList.of(AppleCommandLineOptions.DEFAULT_WATCHOS_CPU);
+          }
+          configurationDistinguisher = ConfigurationDistinguisher.APPLEBIN_WATCHOS;
+          break;
+        default:
+          throw new IllegalArgumentException("Unsupported platform type " + platformType);
+      }
+
+      ImmutableList.Builder<BuildOptions> splitBuildOptions = ImmutableList.builder();
+      for (String cpu : cpus) {
+        BuildOptions splitOptions = buildOptions.clone();
+
+        splitOptions.get(AppleCommandLineOptions.class).applePlatformType = platformType;
+        splitOptions.get(AppleCommandLineOptions.class).appleSplitCpu = cpu;
+        // Set for backwards compatibility with rules that depend on this flag, even when
+        // ios is not the platform type.
+        // TODO(b/28958783): Clean this up.
+        splitOptions.get(AppleCommandLineOptions.class).iosCpu = cpu;
+        if (splitOptions.get(ObjcCommandLineOptions.class).enableCcDeps) {
+          // Only set the (CC-compilation) CPU for dependencies if explicitly required by the user.
+          // This helps users of the iOS rules who do not depend on CC rules as these CPU values
+          // require additional flags to work (e.g. a custom crosstool) which now only need to be
+          // set if this feature is explicitly requested.
+          splitOptions.get(BuildConfiguration.Options.class).cpu =
+              String.format("%s_%s", platformType, cpu);
+        }
+        splitOptions.get(AppleCommandLineOptions.class).configurationDistinguisher =
+            configurationDistinguisher;
+        splitBuildOptions.add(splitOptions);
+      }
+      return splitBuildOptions.build();
+    }
+
+    @Override
+    public boolean defaultsToSelf() {
+      return true;
+    }
+  }
+}
\ No newline at end of file
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommandLineOptions.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommandLineOptions.java
index bd6e6723aa..2d305ca0d9 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommandLineOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommandLineOptions.java
@@ -25,7 +25,6 @@ import com.google.devtools.build.lib.rules.apple.DottedVersion;
 import com.google.devtools.build.lib.rules.apple.DottedVersionConverter;
 import com.google.devtools.common.options.Converters.CommaSeparatedOptionListConverter;
 import com.google.devtools.common.options.Option;
-
 import java.util.List;
 
 /**
@@ -215,7 +214,7 @@ public class ObjcCommandLineOptions extends FragmentOptions {
     return ImmutableList.<SplitTransition<BuildOptions>>builder().add(
             IosApplication.SPLIT_ARCH_TRANSITION, IosExtension.MINIMUM_OS_AND_SPLIT_ARCH_TRANSITION,
             AppleWatch1Extension.MINIMUM_OS_AND_SPLIT_ARCH_TRANSITION)
-        .addAll(AppleBinary.SPLIT_TRANSITION_PROVIDER.getPotentialSplitTransitions())
+        .addAll(MultiArchSplitTransitionProvider.getPotentialSplitTransitions())
         .build();
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java
index ae038854b2..023b81ff80 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java
@@ -909,6 +909,58 @@ public class ObjcRuleClasses {
   }
 
   /**
+   * Attribute name for apple platform type (e.g. ios or watchos).
+   */
+  static final String PLATFORM_TYPE_ATTR_NAME = "platform_type";
+
+  /**
+   * Common attributes for apple rules that build multi-architecture outputs for a given platform
+   * type (such as ios or watchos).
+   */
+  public static class MultiArchPlatformRule implements RuleDefinition {
+
+    @Override
+    public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
+      MultiArchSplitTransitionProvider splitTransitionProvider =
+          new MultiArchSplitTransitionProvider();
+      return builder
+          // This is currently a hack to obtain all child configurations regardless of the attribute
+          // values of this rule -- this rule does not currently use the actual info provided by
+          // this attribute.
+          .add(attr(":cc_toolchain", LABEL)
+              .cfg(splitTransitionProvider)
+              .value(ObjcRuleClasses.APPLE_TOOLCHAIN))
+          /* <!-- #BLAZE_RULE($apple_multiarch_rule).ATTRIBUTE(platform_type) -->
+          The type of platform for which to create artifacts in this rule.
+          For example, if <code>ios</code> is selected, then the output binaries/libraries will
+          be created combining all architectures specified in <code>--ios_multi_cpus</code>.
+
+          Options are:
+          <ul>
+            <li>
+              <code>ios</code> (default): architectures gathered from <code>--ios_multi_cpus</code>.
+            </li>
+            <li>
+              <code>watchos</code>: architectures gathered from <code>--watchos_multi_cpus</code>
+            </li>
+          </ul>
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(PLATFORM_TYPE_ATTR_NAME, STRING)
+              .value(PlatformType.IOS.toString())
+              .nonconfigurable("Determines the configuration transition on deps"))
+          .build();
+    }
+
+    @Override
+    public Metadata getMetadata() {
+      return RuleDefinition.Metadata.builder()
+          .name("$apple_multiarch_rule")
+          .type(RuleClassType.ABSTRACT)
+          .build();
+    }
+  }
+
+  /**
    * Common attributes for {@code objc_*} rules that create a bundle. Specifically, for rules
    * which use the {@link Bundling} helper class.
    */