Expose apple_common.link_multi_arch_binary to Skylark.

This API mimics the linking logic of apple_binary, and is a step to migrating apple_binary to skylark.
This API is *highly experimental* and subject to change.

RELNOTES: None.
PiperOrigin-RevId: 181215275

4 files changed, 174 insertions, 41 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
index b1099467b1..bf53bd53c4 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
@@ -32,6 +32,7 @@ import com.google.devtools.build.lib.analysis.config.CompilationMode;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
 import com.google.devtools.build.lib.analysis.config.PerLabelOptions;
 import com.google.devtools.build.lib.analysis.config.transitions.PatchTransition;
+import com.google.devtools.build.lib.analysis.skylark.SkylarkConfigurationField;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.events.Event;
@@ -466,6 +467,12 @@ public class CppConfiguration extends BuildConfiguration.Fragment {
   /**
    * Returns the label of the <code>cc_compiler</code> rule for the C++ configuration.
    */
+  @SkylarkConfigurationField(
+      name = "cc_toolchain",
+      doc = "The label of the target describing the C++ toolchain",
+      defaultLabel = "//tools/defaults:crosstool",
+      defaultInToolRepository = false
+  )
   public Label getCcToolchainRuleLabel() {
     return ccToolchainLabel;
   }
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 cf2fc9109d..8a6215bbb6 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
@@ -38,6 +38,7 @@ import com.google.devtools.build.lib.analysis.test.InstrumentedFilesCollector;
 import com.google.devtools.build.lib.analysis.test.InstrumentedFilesProvider;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
+import com.google.devtools.build.lib.packages.NativeInfo;
 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.ApplePlatform;
@@ -46,7 +47,6 @@ 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 com.google.devtools.build.lib.rules.objc.MultiArchBinarySupport.DependencySpecificConfiguration;
-
 import java.util.Map;
 import java.util.TreeMap;
 
@@ -114,6 +114,23 @@ public class AppleBinary implements RuleConfiguredTargetFactory {
   @Override
   public final ConfiguredTarget create(RuleContext ruleContext)
       throws InterruptedException, RuleErrorException {
+    AppleBinaryOutput appleBinaryOutput = linkMultiArchBinary(ruleContext);
+
+    return ruleConfiguredTargetFromProvider(ruleContext, appleBinaryOutput);
+  }
+
+  /**
+   * Links a (potentially multi-architecture) binary targeting Apple platforms.
+   *
+   * <p>This method comprises a bulk of the logic of the {@code apple_binary} rule, and is
+   * statically available so that it may be referenced by Skylark APIs that replicate its
+   * functionality.
+   *
+   * @param ruleContext the current rule context
+   * @return a tuple containing all necessary information about the linked binary
+   */
+  public static AppleBinaryOutput linkMultiArchBinary(RuleContext ruleContext)
+      throws InterruptedException, RuleErrorException {
     MultiArchSplitTransitionProvider.validateMinimumOs(ruleContext);
     PlatformType platformType = MultiArchSplitTransitionProvider.getPlatformType(ruleContext);
 
@@ -141,19 +158,20 @@ public class AppleBinary implements RuleConfiguredTargetFactory {
             getDylibProviderTargets(ruleContext));
 
     Map<String, NestedSet<Artifact>> outputGroupCollector = new TreeMap<>();
-    multiArchBinarySupport.registerActions(
-        platform,
-        getExtraLinkArgs(ruleContext),
-        dependencySpecificConfigurations,
-        getExtraLinkInputs(ruleContext),
-        configToDepsCollectionMap,
-        outputArtifact,
-        outputGroupCollector);
+    NestedSet<Artifact> binariesToLipo =
+        multiArchBinarySupport.registerActions(
+            platform,
+            getExtraLinkArgs(ruleContext),
+            dependencySpecificConfigurations,
+            getExtraLinkInputs(ruleContext),
+            configToDepsCollectionMap,
+            outputGroupCollector);
 
-    NestedSetBuilder<Artifact> filesToBuild =
-        NestedSetBuilder.<Artifact>stableOrder().add(outputArtifact);
-    RuleConfiguredTargetBuilder targetBuilder =
-        ObjcRuleClasses.ruleConfiguredTarget(ruleContext, filesToBuild.build());
+    new LipoSupport(ruleContext)
+        .registerCombineArchitecturesAction(
+            binariesToLipo,
+            outputArtifact,
+            platform);
 
     ObjcProvider.Builder objcProviderBuilder = new ObjcProvider.Builder();
     for (DependencySpecificConfiguration dependencySpecificConfiguration :
@@ -164,24 +182,24 @@ public class AppleBinary implements RuleConfiguredTargetFactory {
     objcProviderBuilder.add(MULTI_ARCH_LINKED_BINARIES, outputArtifact);
 
     ObjcProvider objcProvider = objcProviderBuilder.build();
-
-    if (appleConfiguration.shouldLinkingRulesPropagateObjc()) {
-      targetBuilder.addNativeDeclaredProvider(objcProvider);
-    }
+    NativeInfo binaryInfoProvider;
 
     switch (getBinaryType(ruleContext)) {
       case EXECUTABLE:
-        targetBuilder.addNativeDeclaredProvider(
-            new AppleExecutableBinaryProvider(outputArtifact, objcProvider));
+        binaryInfoProvider =
+            new AppleExecutableBinaryProvider(outputArtifact, objcProvider);
         break;
       case DYLIB:
-        targetBuilder.addNativeDeclaredProvider(
-            new AppleDylibBinaryProvider(outputArtifact, objcProvider));
+        binaryInfoProvider =
+            new AppleDylibBinaryProvider(outputArtifact, objcProvider);
         break;
       case LOADABLE_BUNDLE:
-        targetBuilder.addNativeDeclaredProvider(
-            new AppleLoadableBundleBinaryProvider(outputArtifact, objcProvider));
+        binaryInfoProvider =
+            new AppleLoadableBundleBinaryProvider(outputArtifact, objcProvider);
         break;
+      default:
+        ruleContext.ruleError("Unhandled binary type " + getBinaryType(ruleContext));
+        throw new RuleErrorException();
     }
 
     AppleDebugOutputsProvider.Builder builder = AppleDebugOutputsProvider.Builder.create();
@@ -214,13 +232,7 @@ public class AppleBinary implements RuleConfiguredTargetFactory {
       }
     }
 
-    targetBuilder.addNativeDeclaredProvider(builder.build()).addOutputGroups(outputGroupCollector);
-
-    InstrumentedFilesProvider instrumentedFilesProvider =
-        InstrumentedFilesCollector.forward(ruleContext, "deps", "bundle_loader");
-    targetBuilder.addProvider(InstrumentedFilesProvider.class, instrumentedFilesProvider);
-
-    return targetBuilder.build();
+    return new AppleBinaryOutput(binaryInfoProvider, builder.build(), outputGroupCollector);
   }
 
   private static ExtraLinkArgs getExtraLinkArgs(RuleContext ruleContext) throws RuleErrorException {
@@ -282,4 +294,98 @@ public class AppleBinary implements RuleConfiguredTargetFactory {
         ruleContext.attributes().get(AppleBinaryRule.BINARY_TYPE_ATTR, STRING);
     return BinaryType.fromString(binaryTypeString);
   }
+
+  private static ConfiguredTarget ruleConfiguredTargetFromProvider(
+      RuleContext ruleContext, AppleBinaryOutput appleBinaryOutput) throws RuleErrorException {
+    NativeInfo nativeInfo = appleBinaryOutput.getBinaryInfoProvider();
+    AppleConfiguration appleConfiguration = ruleContext.getFragment(AppleConfiguration.class);
+
+    ObjcProvider objcProvider = null;
+    Artifact outputArtifact;
+
+    switch (getBinaryType(ruleContext)) {
+      case EXECUTABLE:
+        AppleExecutableBinaryProvider executableProvider =
+            (AppleExecutableBinaryProvider) nativeInfo;
+        objcProvider = executableProvider.getDepsObjcProvider();
+        outputArtifact = executableProvider.getAppleExecutableBinary();
+        break;
+      case DYLIB:
+        AppleDylibBinaryProvider dylibProvider = (AppleDylibBinaryProvider) nativeInfo;
+        objcProvider = dylibProvider.getDepsObjcProvider();
+        outputArtifact = dylibProvider.getAppleDylibBinary();
+        break;
+      case LOADABLE_BUNDLE:
+        AppleLoadableBundleBinaryProvider loadableBundleProvider =
+            (AppleLoadableBundleBinaryProvider) nativeInfo;
+        outputArtifact = loadableBundleProvider.getAppleLoadableBundleBinary();
+        break;
+      default:
+        ruleContext.ruleError("Unhandled binary type " + getBinaryType(ruleContext));
+        throw new RuleErrorException();
+    }
+
+    NestedSetBuilder<Artifact> filesToBuild =
+        NestedSetBuilder.<Artifact>stableOrder().add(outputArtifact);
+
+    RuleConfiguredTargetBuilder targetBuilder =
+        ObjcRuleClasses.ruleConfiguredTarget(ruleContext, filesToBuild.build());
+
+    if (appleConfiguration.shouldLinkingRulesPropagateObjc() && objcProvider != null) {
+      targetBuilder.addNativeDeclaredProvider(objcProvider);
+    }
+
+    InstrumentedFilesProvider instrumentedFilesProvider =
+        InstrumentedFilesCollector.forward(ruleContext, "deps", "bundle_loader");
+
+    return targetBuilder.addProvider(InstrumentedFilesProvider.class, instrumentedFilesProvider)
+        .addNativeDeclaredProvider(nativeInfo)
+        .addNativeDeclaredProvider(appleBinaryOutput.getDebugOutputsProvider())
+        .addOutputGroups(appleBinaryOutput.getOutputGroups())
+        .build();
+
+  }
+
+  /**
+   * The set of rule outputs propagated by the {@code apple_binary} rule.
+   */
+  public static class AppleBinaryOutput {
+    private final NativeInfo binaryInfoProvider;
+    private final AppleDebugOutputsProvider debugOutputsProvider;
+    private final Map<String, NestedSet<Artifact>> outputGroups;
+
+    private AppleBinaryOutput(NativeInfo binaryInfoProvider,
+        AppleDebugOutputsProvider debugOutputsProvider,
+        Map<String, NestedSet<Artifact>> outputGroups) {
+      this.binaryInfoProvider = binaryInfoProvider;
+      this.debugOutputsProvider = debugOutputsProvider;
+      this.outputGroups = outputGroups;
+    }
+
+    /**
+     * Returns a {@link NativeInfo} possessing information about the linked binary. Depending
+     * on the type of binary, this may be either a {@link AppleExecutableBinaryProvider}, a
+     * {@link AppleDylibBinaryProvider}, or a {@link AppleLoadableBundleBinaryProvider}.
+     */
+    public NativeInfo getBinaryInfoProvider() {
+      return binaryInfoProvider;
+    }
+
+    /**
+     * Returns a {@link AppleDebugOutputsProvider} containing debug information about the linked
+     * binary.
+     */
+    public AppleDebugOutputsProvider getDebugOutputsProvider() {
+      return debugOutputsProvider;
+    }
+
+    /**
+     * Returns a map from output group name to set of artifacts belonging to this output group.
+     * This should be added to configured target information using
+     * {@link RuleConfiguredTargetBuilder#addOutputGroups(Map)}.
+     */
+    public Map<String, NestedSet<Artifact>> getOutputGroups() {
+      return outputGroups;
+    }
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleSkylarkCommon.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleSkylarkCommon.java
index b679558aae..6dec5fe3d2 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleSkylarkCommon.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleSkylarkCommon.java
@@ -18,12 +18,16 @@ import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.analysis.RuleContext;
+import com.google.devtools.build.lib.analysis.skylark.SkylarkRuleContext;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.collect.nestedset.Order;
 import com.google.devtools.build.lib.packages.Attribute.SplitTransitionProvider;
 import com.google.devtools.build.lib.packages.Info;
+import com.google.devtools.build.lib.packages.NativeInfo;
 import com.google.devtools.build.lib.packages.Provider;
+import com.google.devtools.build.lib.packages.RuleClass.ConfiguredTargetFactory.RuleErrorException;
 import com.google.devtools.build.lib.packages.SkylarkAspect;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.ApplePlatform;
@@ -32,12 +36,14 @@ import com.google.devtools.build.lib.rules.apple.AppleToolchain;
 import com.google.devtools.build.lib.rules.apple.DottedVersion;
 import com.google.devtools.build.lib.rules.apple.XcodeConfigProvider;
 import com.google.devtools.build.lib.rules.apple.XcodeVersionProperties;
+import com.google.devtools.build.lib.rules.objc.AppleBinary.AppleBinaryOutput;
 import com.google.devtools.build.lib.rules.objc.ObjcProvider.Key;
 import com.google.devtools.build.lib.skylarkinterface.Param;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkSignature;
 import com.google.devtools.build.lib.syntax.BuiltinFunction;
+import com.google.devtools.build.lib.syntax.EvalException;
 import com.google.devtools.build.lib.syntax.Runtime;
 import com.google.devtools.build.lib.syntax.SkylarkDict;
 import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
@@ -54,7 +60,7 @@ import javax.annotation.Nullable;
   doc = "Functions for skylark to access internals of the apple rule implementations."
 )
 public class AppleSkylarkCommon {
- 
+
   @VisibleForTesting
   public static final String BAD_KEY_ERROR = "Argument %s not a recognized key, 'providers',"
       + " or 'direct_dep_providers'.";
@@ -519,6 +525,27 @@ public class AppleSkylarkCommon {
         }
       };
 
+  @SkylarkCallable(
+      name = "link_multi_arch_binary",
+      doc = "Links a (potentially multi-architecture) binary targeting Apple platforms. This "
+          + "method comprises a bulk of the logic of the <code>apple_binary</code> rule, and is "
+          + "exposed as an API to iterate on migration of <code>apple_binary</code> to skylark.\n"
+          + "<p>This API is <b>highly experimental</b> and subject to change at any time. Do not "
+          + "depend on the stability of this function at this time.",
+      mandatoryPositionals = 1 // The SkylarkRuleContext.
+  )
+  // TODO(b/70937317): Iterate on, improve, and solidify this API.
+  public NativeInfo linkMultiArchBinary(SkylarkRuleContext skylarkRuleContext)
+      throws EvalException, InterruptedException {
+    try {
+      RuleContext ruleContext = skylarkRuleContext.getRuleContext();
+      AppleBinaryOutput appleBinaryOutput = AppleBinary.linkMultiArchBinary(ruleContext);
+      return appleBinaryOutput.getBinaryInfoProvider();
+    } catch (RuleErrorException exception) {
+      throw new EvalException(null, exception);
+    }
+  }
+
   @SkylarkSignature(
     name = "dotted_version",
     objectType = AppleSkylarkCommon.class,
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/MultiArchBinarySupport.java b/src/main/java/com/google/devtools/build/lib/rules/objc/MultiArchBinarySupport.java
index 71a8a7fb6f..dc5eb4f9d1 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/MultiArchBinarySupport.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/MultiArchBinarySupport.java
@@ -127,19 +127,17 @@ public class MultiArchBinarySupport {
    * @param extraLinkInputs the extra linker inputs to be made available during link actions
    * @param configToDepsCollectionMap a multimap from dependency configuration to the list of
    *     provider collections which are propagated from the dependencies of that configuration
-   * @param outputLipoBinary the artifact (lipo'ed binary) which should be output as a result of
-   *     this support
    * @param outputMapCollector a map to which output groups created by compile action generation are
    *     added
+   * @return a set containing all single-architecture binaries that are linked from this call
    * @throws RuleErrorException if there are attribute errors in the current rule context
    */
-  public void registerActions(
+  public NestedSet<Artifact> registerActions(
       ApplePlatform platform,
       ExtraLinkArgs extraLinkArgs,
       Set<DependencySpecificConfiguration> dependencySpecificConfigurations,
       Iterable<Artifact> extraLinkInputs,
       ImmutableListMultimap<BuildConfiguration, TransitiveInfoCollection> configToDepsCollectionMap,
-      Artifact outputLipoBinary,
       Map<String, NestedSet<Artifact>> outputMapCollector)
       throws RuleErrorException, InterruptedException {
 
@@ -190,12 +188,7 @@ public class MultiArchBinarySupport {
           .validateAttributes();
       ruleContext.assertNoErrors();
     }
-
-    new LipoSupport(ruleContext)
-        .registerCombineArchitecturesAction(
-            binariesToLipo.build(),
-            outputLipoBinary,
-            platform);
+    return binariesToLipo.build();
   }
 
   /**