src/main/java/com/google/devtools/build/lib/rules/objc/AppleBinary.java - bazel - Git at Google

 // 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.rules.objc.AppleBinaryRule.BUNDLE_LOADER_ATTR_NAME;
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.MULTI_ARCH_LINKED_BINARIES;
 import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.DylibDependingRule.DYLIBS_ATTR_NAME;
 import static com.google.devtools.build.lib.syntax.Type.STRING;

 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Functions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 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;
 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.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.rules.RuleConfiguredTargetFactory;
 import com.google.devtools.build.lib.rules.apple.AppleCommandLineOptions.AppleBitcodeMode;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.Platform;
 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.AppleDebugOutputsProvider.OutputType;
 import com.google.devtools.build.lib.rules.objc.CompilationSupport.ExtraLinkArgs;
 import java.util.Map;
 import java.util.Set;

 /** Implementation for the "apple_binary" rule. */
 public class AppleBinary implements RuleConfiguredTargetFactory {

   /** Type of linked binary that apple_binary may create. */
   enum BinaryType {

     /**
      * Binaries that can be loaded by other binaries at runtime, and which can't be directly
      * executed by the operating system. When linking, a bundle_loader binary may be passed which
      * signals the linker on where to look for unimplemented symbols, basically declaring that the
      * bundle should be loaded by that binary. Bundle binaries are usually found in Plugins, and one
      * common use case is tests. Tests are bundled into an .xctest bundle which contains the test
      * binary along with required resources. The test bundle is then loaded and run during test
      * execution.
      */
     LOADABLE_BUNDLE,

     /**
      * Binaries that can be run directly by the operating system. They implement the main method
      * that is the entry point to the program. In Apple apps, they are usually distributed in .app
      * bundles, which are directories that contain the executable along with required resources to
      * run.
      */
     EXECUTABLE,

     /**
      * Binaries meant to be loaded at load time (when the operating system is loading the binary
      * into memory), which cannot be unloaded. They are usually distributed in frameworks, which are
      * .framework bundles that contain the dylib as well as well as required resources to run.
      */
     DYLIB;

     @Override
     public String toString() {
       return name().toLowerCase();
     }

     /**
      * Returns the {@link BinaryType} with given name (case insensitive).
      *
      * @throws IllegalArgumentException if the name does not match a valid platform type.
      */
     public static BinaryType fromString(String name) {
       for (BinaryType binaryType : BinaryType.values()) {
         if (name.equalsIgnoreCase(binaryType.toString())) {
           return binaryType;
         }
       }
       throw new IllegalArgumentException(String.format("Unsupported binary type \"%s\"", name));
     }

     /** Returns the enum values as a list of strings for validation. */
     static Iterable<String> getValues() {
       return Iterables.transform(ImmutableList.copyOf(values()), Functions.toStringFunction());
     }
   }

   @VisibleForTesting
   static final String BUNDLE_LOADER_NOT_IN_BUNDLE_ERROR =
       "Can only use bundle_loader when binary_type is bundle.";

   @Override
   public final ConfiguredTarget create(RuleContext ruleContext)
       throws InterruptedException, RuleErrorException {
     PlatformType platformType = MultiArchSplitTransitionProvider.getPlatformType(ruleContext);
     AppleConfiguration appleConfiguration = ruleContext.getFragment(AppleConfiguration.class);

     Platform platform = appleConfiguration.getMultiArchPlatform(platformType);
     ImmutableListMultimap<BuildConfiguration, ObjcProvider> configurationToNonPropagatedObjcMap =
         ruleContext.getPrerequisitesByConfiguration(
             "non_propagated_deps", Mode.SPLIT, ObjcProvider.class);
     ImmutableListMultimap<BuildConfiguration, TransitiveInfoCollection> configToDepsCollectionMap =
         ruleContext.getPrerequisitesByConfiguration("deps", Mode.SPLIT);

     Set<BuildConfiguration> childConfigurations = getChildConfigurations(ruleContext);
     Artifact outputArtifact =
         ObjcRuleClasses.intermediateArtifacts(ruleContext).combinedArchitectureBinary();

     MultiArchBinarySupport multiArchBinarySupport = new MultiArchBinarySupport(ruleContext);

     Map<BuildConfiguration, ObjcProvider> objcProviderByDepConfiguration =
         multiArchBinarySupport.objcProviderByDepConfiguration(
             childConfigurations,
             configToDepsCollectionMap,
             configurationToNonPropagatedObjcMap,
             getDylibProviders(ruleContext),
             getDylibProtoProviders(ruleContext));

     multiArchBinarySupport.registerActions(
         platform,
         getExtraLinkArgs(ruleContext),
         objcProviderByDepConfiguration,
         getExtraLinkInputs(ruleContext),
         configToDepsCollectionMap,
         outputArtifact);

     NestedSetBuilder<Artifact> filesToBuild =
         NestedSetBuilder.<Artifact>stableOrder().add(outputArtifact);
     RuleConfiguredTargetBuilder targetBuilder =
         ObjcRuleClasses.ruleConfiguredTarget(ruleContext, filesToBuild.build());

     ObjcProvider.Builder objcProviderBuilder = new ObjcProvider.Builder();
     for (ObjcProvider objcProvider : objcProviderByDepConfiguration.values()) {
       objcProviderBuilder.addTransitiveAndPropagate(objcProvider);
     }
     objcProviderBuilder.add(MULTI_ARCH_LINKED_BINARIES, outputArtifact);

     ObjcProvider objcProvider = objcProviderBuilder.build();
     // TODO(cparsons): Stop propagating ObjcProvider directly from this rule.
     targetBuilder.addProvider(ObjcProvider.class, objcProvider);

     switch (getBinaryType(ruleContext)) {
       case EXECUTABLE:
         targetBuilder.addNativeDeclaredProvider(
             new AppleExecutableBinaryProvider(outputArtifact, objcProvider));
         break;
       case DYLIB:
         targetBuilder.addNativeDeclaredProvider(
             new AppleDylibBinaryProvider(outputArtifact, objcProvider));
         break;
       case LOADABLE_BUNDLE:
         targetBuilder.addNativeDeclaredProvider(
             new AppleLoadableBundleBinaryProvider(outputArtifact));
         break;
     }

     AppleDebugOutputsProvider.Builder builder = AppleDebugOutputsProvider.Builder.create();

     for (BuildConfiguration childConfig : childConfigurations) {
       AppleConfiguration childAppleConfig = childConfig.getFragment(AppleConfiguration.class);
       ObjcConfiguration childObjcConfig = childConfig.getFragment(ObjcConfiguration.class);
       IntermediateArtifacts intermediateArtifacts =
           new IntermediateArtifacts(
               ruleContext, /*archiveFileNameSuffix*/ "", /*outputPrefix*/ "", childConfig);
       String arch = childAppleConfig.getSingleArchitecture();

       if (childAppleConfig.getBitcodeMode() == AppleBitcodeMode.EMBEDDED) {
         Artifact bitcodeSymbol = intermediateArtifacts.bitcodeSymbolMap();
         builder.addOutput(arch, OutputType.BITCODE_SYMBOLS, bitcodeSymbol);
       }
       if (childObjcConfig.generateDsym()) {
         Artifact dsymBinary = intermediateArtifacts.dsymSymbol(DsymOutputType.APP);
         builder.addOutput(arch, OutputType.DSYM_BINARY, dsymBinary);
       }
       if (childObjcConfig.generateLinkmap()) {
         Artifact linkmap = intermediateArtifacts.linkmap();
         builder.addOutput(arch, OutputType.LINKMAP, linkmap);
       }
     }

     targetBuilder.addNativeDeclaredProvider(builder.build());

     return targetBuilder.build();
   }

   private static ExtraLinkArgs getExtraLinkArgs(RuleContext ruleContext) throws RuleErrorException {
     BinaryType binaryType = getBinaryType(ruleContext);

     ImmutableList.Builder<String> extraLinkArgs = new ImmutableList.Builder<>();

     boolean didProvideBundleLoader =
         ruleContext.attributes().isAttributeValueExplicitlySpecified(BUNDLE_LOADER_ATTR_NAME);

     if (didProvideBundleLoader && binaryType != BinaryType.LOADABLE_BUNDLE) {
       ruleContext.throwWithRuleError(BUNDLE_LOADER_NOT_IN_BUNDLE_ERROR);
     }

     switch (binaryType) {
       case LOADABLE_BUNDLE:
         extraLinkArgs.add("-bundle");
         if (didProvideBundleLoader) {
           AppleExecutableBinaryProvider executableProvider =
               (AppleExecutableBinaryProvider) ruleContext.getPrerequisite(
                   BUNDLE_LOADER_ATTR_NAME, Mode.TARGET,
                   AppleExecutableBinaryProvider.SKYLARK_CONSTRUCTOR.getKey());
           extraLinkArgs.add(
               "-bundle_loader", executableProvider.getAppleExecutableBinary().getExecPathString());
           extraLinkArgs.add("-Xlinker", "-rpath", "-Xlinker", "@loader_path/Frameworks");
         }
         break;
       case DYLIB:
         extraLinkArgs.add("-dynamiclib");
         break;
       case EXECUTABLE:
         break;
     }

     return new ExtraLinkArgs(extraLinkArgs.build());
   }

   private static Iterable<ObjcProvider> getDylibProviders(RuleContext ruleContext) {
     Iterable<ObjcProvider> dylibProviders =
         ruleContext.getPrerequisites(DYLIBS_ATTR_NAME, Mode.TARGET, ObjcProvider.class);

     ObjcProvider bundleLoaderObjcProvider =
         ruleContext.getPrerequisite(BUNDLE_LOADER_ATTR_NAME, Mode.TARGET, ObjcProvider.class);

     if (bundleLoaderObjcProvider != null) {
       dylibProviders = Iterables.concat(dylibProviders, ImmutableList.of(bundleLoaderObjcProvider));
     }
     return dylibProviders;
   }

   private static Iterable<ObjcProtoProvider> getDylibProtoProviders(RuleContext ruleContext) {
     Iterable<ObjcProtoProvider> dylibProtoProviders =
         ruleContext.getPrerequisites(DYLIBS_ATTR_NAME, Mode.TARGET, ObjcProtoProvider.class);

     ObjcProtoProvider bundleLoaderObjcProtoProvider =
         ruleContext.getPrerequisite(BUNDLE_LOADER_ATTR_NAME, Mode.TARGET, ObjcProtoProvider.class);

     if (bundleLoaderObjcProtoProvider != null) {
       dylibProtoProviders =
           Iterables.concat(dylibProtoProviders, ImmutableList.of(bundleLoaderObjcProtoProvider));
     }
     return dylibProtoProviders;
   }

   private static Iterable<Artifact> getExtraLinkInputs(RuleContext ruleContext) {
     AppleExecutableBinaryProvider executableProvider =
         (AppleExecutableBinaryProvider) ruleContext.getPrerequisite(
             BUNDLE_LOADER_ATTR_NAME, Mode.TARGET,
             AppleExecutableBinaryProvider.SKYLARK_CONSTRUCTOR.getKey());
     if (executableProvider != null) {
       return ImmutableSet.<Artifact>of(executableProvider.getAppleExecutableBinary());
     }
     return ImmutableSet.<Artifact>of();
   }

   private Set<BuildConfiguration> getChildConfigurations(RuleContext ruleContext) {
     // 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. b/28403953 tracks cc toolchain usage.
     ImmutableListMultimap<BuildConfiguration, CcToolchainProvider> configToProvider =
         ruleContext.getPrerequisitesByConfiguration(
             ObjcRuleClasses.CHILD_CONFIG_ATTR, Mode.SPLIT, CcToolchainProvider.class);

     return configToProvider.keySet();
   }

   private static BinaryType getBinaryType(RuleContext ruleContext) {
     String binaryTypeString =
         ruleContext.attributes().get(AppleBinaryRule.BINARY_TYPE_ATTR, STRING);
     return BinaryType.fromString(binaryTypeString);
   }
 }
	// 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.rules.objc.AppleBinaryRule.BUNDLE_LOADER_ATTR_NAME;
	import static com.google.devtools.build.lib.rules.objc.ObjcProvider.MULTI_ARCH_LINKED_BINARIES;
	import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.DylibDependingRule.DYLIBS_ATTR_NAME;
	import static com.google.devtools.build.lib.syntax.Type.STRING;

	import com.google.common.annotations.VisibleForTesting;
	import com.google.common.base.Functions;
	import com.google.common.collect.ImmutableList;
	import com.google.common.collect.ImmutableListMultimap;
	import com.google.common.collect.ImmutableSet;
	import com.google.common.collect.Iterables;
	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;
	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.collect.nestedset.NestedSetBuilder;
	import com.google.devtools.build.lib.rules.RuleConfiguredTargetFactory;
	import com.google.devtools.build.lib.rules.apple.AppleCommandLineOptions.AppleBitcodeMode;
	import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
	import com.google.devtools.build.lib.rules.apple.Platform;
	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.AppleDebugOutputsProvider.OutputType;
	import com.google.devtools.build.lib.rules.objc.CompilationSupport.ExtraLinkArgs;
	import java.util.Map;
	import java.util.Set;

	/** Implementation for the "apple_binary" rule. */
	public class AppleBinary implements RuleConfiguredTargetFactory {

	/** Type of linked binary that apple_binary may create. */
	enum BinaryType {

	/**
	* Binaries that can be loaded by other binaries at runtime, and which can't be directly
	* executed by the operating system. When linking, a bundle_loader binary may be passed which
	* signals the linker on where to look for unimplemented symbols, basically declaring that the
	* bundle should be loaded by that binary. Bundle binaries are usually found in Plugins, and one
	* common use case is tests. Tests are bundled into an .xctest bundle which contains the test
	* binary along with required resources. The test bundle is then loaded and run during test
	* execution.
	*/
	LOADABLE_BUNDLE,

	/**
	* Binaries that can be run directly by the operating system. They implement the main method
	* that is the entry point to the program. In Apple apps, they are usually distributed in .app
	* bundles, which are directories that contain the executable along with required resources to
	* run.
	*/
	EXECUTABLE,

	/**
	* Binaries meant to be loaded at load time (when the operating system is loading the binary
	* into memory), which cannot be unloaded. They are usually distributed in frameworks, which are
	* .framework bundles that contain the dylib as well as well as required resources to run.
	*/
	DYLIB;

	@Override
	public String toString() {
	return name().toLowerCase();
	}

	/**
	* Returns the {@link BinaryType} with given name (case insensitive).
	*
	* @throws IllegalArgumentException if the name does not match a valid platform type.
	*/
	public static BinaryType fromString(String name) {
	for (BinaryType binaryType : BinaryType.values()) {
	if (name.equalsIgnoreCase(binaryType.toString())) {
	return binaryType;
	}
	}
	throw new IllegalArgumentException(String.format("Unsupported binary type \"%s\"", name));
	}

	/** Returns the enum values as a list of strings for validation. */
	static Iterable<String> getValues() {
	return Iterables.transform(ImmutableList.copyOf(values()), Functions.toStringFunction());
	}
	}

	@VisibleForTesting
	static final String BUNDLE_LOADER_NOT_IN_BUNDLE_ERROR =
	"Can only use bundle_loader when binary_type is bundle.";

	@Override
	public final ConfiguredTarget create(RuleContext ruleContext)
	throws InterruptedException, RuleErrorException {
	PlatformType platformType = MultiArchSplitTransitionProvider.getPlatformType(ruleContext);
	AppleConfiguration appleConfiguration = ruleContext.getFragment(AppleConfiguration.class);

	Platform platform = appleConfiguration.getMultiArchPlatform(platformType);
	ImmutableListMultimap<BuildConfiguration, ObjcProvider> configurationToNonPropagatedObjcMap =
	ruleContext.getPrerequisitesByConfiguration(
	"non_propagated_deps", Mode.SPLIT, ObjcProvider.class);
	ImmutableListMultimap<BuildConfiguration, TransitiveInfoCollection> configToDepsCollectionMap =
	ruleContext.getPrerequisitesByConfiguration("deps", Mode.SPLIT);

	Set<BuildConfiguration> childConfigurations = getChildConfigurations(ruleContext);
	Artifact outputArtifact =
	ObjcRuleClasses.intermediateArtifacts(ruleContext).combinedArchitectureBinary();

	MultiArchBinarySupport multiArchBinarySupport = new MultiArchBinarySupport(ruleContext);

	Map<BuildConfiguration, ObjcProvider> objcProviderByDepConfiguration =
	multiArchBinarySupport.objcProviderByDepConfiguration(
	childConfigurations,
	configToDepsCollectionMap,
	configurationToNonPropagatedObjcMap,
	getDylibProviders(ruleContext),
	getDylibProtoProviders(ruleContext));

	multiArchBinarySupport.registerActions(
	platform,
	getExtraLinkArgs(ruleContext),
	objcProviderByDepConfiguration,
	getExtraLinkInputs(ruleContext),
	configToDepsCollectionMap,
	outputArtifact);

	NestedSetBuilder<Artifact> filesToBuild =
	NestedSetBuilder.<Artifact>stableOrder().add(outputArtifact);
	RuleConfiguredTargetBuilder targetBuilder =
	ObjcRuleClasses.ruleConfiguredTarget(ruleContext, filesToBuild.build());

	ObjcProvider.Builder objcProviderBuilder = new ObjcProvider.Builder();
	for (ObjcProvider objcProvider : objcProviderByDepConfiguration.values()) {
	objcProviderBuilder.addTransitiveAndPropagate(objcProvider);
	}
	objcProviderBuilder.add(MULTI_ARCH_LINKED_BINARIES, outputArtifact);

	ObjcProvider objcProvider = objcProviderBuilder.build();
	// TODO(cparsons): Stop propagating ObjcProvider directly from this rule.
	targetBuilder.addProvider(ObjcProvider.class, objcProvider);

	switch (getBinaryType(ruleContext)) {
	case EXECUTABLE:
	targetBuilder.addNativeDeclaredProvider(
	new AppleExecutableBinaryProvider(outputArtifact, objcProvider));
	break;
	case DYLIB:
	targetBuilder.addNativeDeclaredProvider(
	new AppleDylibBinaryProvider(outputArtifact, objcProvider));
	break;
	case LOADABLE_BUNDLE:
	targetBuilder.addNativeDeclaredProvider(
	new AppleLoadableBundleBinaryProvider(outputArtifact));
	break;
	}

	AppleDebugOutputsProvider.Builder builder = AppleDebugOutputsProvider.Builder.create();

	for (BuildConfiguration childConfig : childConfigurations) {
	AppleConfiguration childAppleConfig = childConfig.getFragment(AppleConfiguration.class);
	ObjcConfiguration childObjcConfig = childConfig.getFragment(ObjcConfiguration.class);
	IntermediateArtifacts intermediateArtifacts =
	new IntermediateArtifacts(
	ruleContext, /archiveFileNameSuffix/ "", /outputPrefix/ "", childConfig);
	String arch = childAppleConfig.getSingleArchitecture();

	if (childAppleConfig.getBitcodeMode() == AppleBitcodeMode.EMBEDDED) {
	Artifact bitcodeSymbol = intermediateArtifacts.bitcodeSymbolMap();
	builder.addOutput(arch, OutputType.BITCODE_SYMBOLS, bitcodeSymbol);
	}
	if (childObjcConfig.generateDsym()) {
	Artifact dsymBinary = intermediateArtifacts.dsymSymbol(DsymOutputType.APP);
	builder.addOutput(arch, OutputType.DSYM_BINARY, dsymBinary);
	}
	if (childObjcConfig.generateLinkmap()) {
	Artifact linkmap = intermediateArtifacts.linkmap();
	builder.addOutput(arch, OutputType.LINKMAP, linkmap);
	}
	}

	targetBuilder.addNativeDeclaredProvider(builder.build());

	return targetBuilder.build();
	}

	private static ExtraLinkArgs getExtraLinkArgs(RuleContext ruleContext) throws RuleErrorException {
	BinaryType binaryType = getBinaryType(ruleContext);

	ImmutableList.Builder<String> extraLinkArgs = new ImmutableList.Builder<>();

	boolean didProvideBundleLoader =
	ruleContext.attributes().isAttributeValueExplicitlySpecified(BUNDLE_LOADER_ATTR_NAME);

	if (didProvideBundleLoader && binaryType != BinaryType.LOADABLE_BUNDLE) {
	ruleContext.throwWithRuleError(BUNDLE_LOADER_NOT_IN_BUNDLE_ERROR);
	}

	switch (binaryType) {
	case LOADABLE_BUNDLE:
	extraLinkArgs.add("-bundle");
	if (didProvideBundleLoader) {
	AppleExecutableBinaryProvider executableProvider =
	(AppleExecutableBinaryProvider) ruleContext.getPrerequisite(
	BUNDLE_LOADER_ATTR_NAME, Mode.TARGET,
	AppleExecutableBinaryProvider.SKYLARK_CONSTRUCTOR.getKey());
	extraLinkArgs.add(
	"-bundle_loader", executableProvider.getAppleExecutableBinary().getExecPathString());
	extraLinkArgs.add("-Xlinker", "-rpath", "-Xlinker", "@loader_path/Frameworks");
	}
	break;
	case DYLIB:
	extraLinkArgs.add("-dynamiclib");
	break;
	case EXECUTABLE:
	break;
	}

	return new ExtraLinkArgs(extraLinkArgs.build());
	}

	private static Iterable<ObjcProvider> getDylibProviders(RuleContext ruleContext) {
	Iterable<ObjcProvider> dylibProviders =
	ruleContext.getPrerequisites(DYLIBS_ATTR_NAME, Mode.TARGET, ObjcProvider.class);

	ObjcProvider bundleLoaderObjcProvider =
	ruleContext.getPrerequisite(BUNDLE_LOADER_ATTR_NAME, Mode.TARGET, ObjcProvider.class);

	if (bundleLoaderObjcProvider != null) {
	dylibProviders = Iterables.concat(dylibProviders, ImmutableList.of(bundleLoaderObjcProvider));
	}
	return dylibProviders;
	}

	private static Iterable<ObjcProtoProvider> getDylibProtoProviders(RuleContext ruleContext) {
	Iterable<ObjcProtoProvider> dylibProtoProviders =
	ruleContext.getPrerequisites(DYLIBS_ATTR_NAME, Mode.TARGET, ObjcProtoProvider.class);

	ObjcProtoProvider bundleLoaderObjcProtoProvider =
	ruleContext.getPrerequisite(BUNDLE_LOADER_ATTR_NAME, Mode.TARGET, ObjcProtoProvider.class);

	if (bundleLoaderObjcProtoProvider != null) {
	dylibProtoProviders =
	Iterables.concat(dylibProtoProviders, ImmutableList.of(bundleLoaderObjcProtoProvider));
	}
	return dylibProtoProviders;
	}

	private static Iterable<Artifact> getExtraLinkInputs(RuleContext ruleContext) {
	AppleExecutableBinaryProvider executableProvider =
	(AppleExecutableBinaryProvider) ruleContext.getPrerequisite(
	BUNDLE_LOADER_ATTR_NAME, Mode.TARGET,
	AppleExecutableBinaryProvider.SKYLARK_CONSTRUCTOR.getKey());
	if (executableProvider != null) {
	return ImmutableSet.<Artifact>of(executableProvider.getAppleExecutableBinary());
	}
	return ImmutableSet.<Artifact>of();
	}

	private Set<BuildConfiguration> getChildConfigurations(RuleContext ruleContext) {
	// 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. b/28403953 tracks cc toolchain usage.
	ImmutableListMultimap<BuildConfiguration, CcToolchainProvider> configToProvider =
	ruleContext.getPrerequisitesByConfiguration(
	ObjcRuleClasses.CHILD_CONFIG_ATTR, Mode.SPLIT, CcToolchainProvider.class);

	return configToProvider.keySet();
	}

	private static BinaryType getBinaryType(RuleContext ruleContext) {
	String binaryTypeString =
	ruleContext.attributes().get(AppleBinaryRule.BINARY_TYPE_ATTR, STRING);
	return BinaryType.fromString(binaryTypeString);
	}
	}