Implement basic objc executable linking in the CROSSTOOL.

The following link features are *not* implemented yet:
1) Objc++ linking semantics
2) Dead stripping
3) --should_prioritize_static_libs
4) DSYM generation
5) Coverage support
6) Swift interop
7) Linkmap

--
MOS_MIGRATED_REVID=139232434

1 files changed, 184 insertions, 5 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcVariablesExtension.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcVariablesExtension.java
index e14be86eba..851af8d32e 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcVariablesExtension.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcVariablesExtension.java
@@ -15,17 +15,22 @@
 package com.google.devtools.build.lib.rules.objc;
 
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.IMPORTED_LIBRARY;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.LINKOPT;
 
+import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
 import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
+import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 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.cpp.CcToolchainFeatures;
 import com.google.devtools.build.lib.rules.cpp.CcToolchainFeatures.Variables.StringSequence;
 import com.google.devtools.build.lib.rules.cpp.CcToolchainFeatures.Variables.VariablesExtension;
+import java.util.Set;
 
 /** Build variable extensions for templating a toolchain for objc builds. */
 class ObjcVariablesExtension implements VariablesExtension {
@@ -43,22 +48,41 @@ class ObjcVariablesExtension implements VariablesExtension {
   static final String CC_LIBRARY_EXEC_PATHS_VARIABLE_NAME = "cc_library_exec_paths";
   static final String IMPORTED_LIBRARY_EXEC_PATHS_VARIABLE_NAME = "imported_library_exec_paths";
 
+  // executable linking variables
+  static final String FRAMEWORK_NAMES_VARIABLE_NAME = "framework_names";
+  static final String WEAK_FRAMEWORK_NAMES_VARIABLE_NAME = "weak_framework_names";
+  static final String LIBRARY_NAMES_VARIABLE_NAME = "library_names";
+  static final String FILELIST_VARIABLE_NAME = "filelist";
+  static final String LINKED_BINARY_VARIABLE_NAME = "linked_binary";
+  static final String FORCE_LOAD_EXEC_PATHS_VARIABLE_NAME = "force_load_exec_paths";
+  static final String DEP_LINKOPTS_VARIABLE_NAME = "dep_linkopts";
+  static final String ATTR_LINKOPTS_VARIABLE_NAME = "attr_linkopts";
+  
   private final RuleContext ruleContext;
   private final ObjcProvider objcProvider;
   private final CompilationArtifacts compilationArtifacts;
   private final Artifact fullyLinkArchive;
   private final IntermediateArtifacts intermediateArtifacts;
-
   private final BuildConfiguration buildConfiguration;
   private final AppleConfiguration appleConfiguration;
+  private final Set<String> frameworkNames;
+  private final ImmutableList<String> libraryNames;
+  private final ImmutableSet<Artifact> forceLoadArtifacts;
+  private final NestedSet<String> attributeLinkopts;
+  private final ImmutableSet<VariableCategory> activeVariableCategories;
 
-  public ObjcVariablesExtension(
+  private ObjcVariablesExtension(
       RuleContext ruleContext,
       ObjcProvider objcProvider,
       CompilationArtifacts compilationArtifacts,
       Artifact fullyLinkArchive,
       IntermediateArtifacts intermediateArtifacts,
-      BuildConfiguration buildConfiguration) {
+      BuildConfiguration buildConfiguration,
+      Set<String> frameworkNames,
+      ImmutableList<String> libraryNames,
+      ImmutableSet<Artifact> forceLoadArtifacts,
+      NestedSet<String> attributeLinkopts,
+      ImmutableSet<VariableCategory> activeVariableCategories) {
     this.ruleContext = ruleContext;
     this.objcProvider = objcProvider;
     this.compilationArtifacts = compilationArtifacts;
@@ -66,6 +90,16 @@ class ObjcVariablesExtension implements VariablesExtension {
     this.intermediateArtifacts = intermediateArtifacts;
     this.buildConfiguration = buildConfiguration;
     this.appleConfiguration = buildConfiguration.getFragment(AppleConfiguration.class);
+    this.frameworkNames = frameworkNames;
+    this.libraryNames = libraryNames;
+    this.forceLoadArtifacts = forceLoadArtifacts;
+    this.attributeLinkopts = attributeLinkopts;
+    this.activeVariableCategories = activeVariableCategories;
+  }
+
+  /** Type of build variable that can optionally exported by this extension. */
+  public enum VariableCategory {
+    ARCHIVE_VARIABLES, FULLY_LINK_VARIABLES, EXECUTABLE_LINKING_VARIABLES;
   }
 
   @Override
@@ -74,10 +108,15 @@ class ObjcVariablesExtension implements VariablesExtension {
     addFrameworkVariables(builder);
     addArchVariables(builder);
     addModuleMapVariables(builder);
-    if (compilationArtifacts.getArchive().isPresent()) {
+    if (activeVariableCategories.contains(VariableCategory.ARCHIVE_VARIABLES)) {
       addArchiveVariables(builder);
     }
-    addFullyLinkArchiveVariables(builder);
+    if (activeVariableCategories.contains(VariableCategory.FULLY_LINK_VARIABLES)) {
+      addFullyLinkArchiveVariables(builder);
+    }
+    if (activeVariableCategories.contains(VariableCategory.EXECUTABLE_LINKING_VARIABLES)) {
+      addExecutableLinkVariables(builder);
+    }
   }
 
   private void addPchVariables(CcToolchainFeatures.Variables.Builder builder) {
@@ -138,4 +177,144 @@ class ObjcVariablesExtension implements VariablesExtension {
         IMPORTED_LIBRARY_EXEC_PATHS_VARIABLE_NAME,
         ImmutableList.copyOf(Artifact.toExecPaths(objcProvider.get(IMPORTED_LIBRARY))));
   }
+
+  private void addExecutableLinkVariables(CcToolchainFeatures.Variables.Builder builder) {
+    builder.addSequenceVariable(FRAMEWORK_NAMES_VARIABLE_NAME, frameworkNames);
+    builder.addSequenceVariable(
+        WEAK_FRAMEWORK_NAMES_VARIABLE_NAME,
+        SdkFramework.names(objcProvider.get(ObjcProvider.WEAK_SDK_FRAMEWORK)));
+    builder.addSequenceVariable(LIBRARY_NAMES_VARIABLE_NAME, libraryNames);
+    builder.addVariable(
+        FILELIST_VARIABLE_NAME, intermediateArtifacts.linkerObjList().getExecPathString());
+    builder.addVariable(
+        LINKED_BINARY_VARIABLE_NAME,
+        ruleContext.getFragment(ObjcConfiguration.class).shouldStripBinary()
+            ? intermediateArtifacts.unstrippedSingleArchitectureBinary().getExecPathString()
+            : intermediateArtifacts.strippedSingleArchitectureBinary().getExecPathString());
+
+    builder.addSequenceVariable(
+        FORCE_LOAD_EXEC_PATHS_VARIABLE_NAME,
+        Artifact.toExecPaths(forceLoadArtifacts));
+    builder.addSequenceVariable(DEP_LINKOPTS_VARIABLE_NAME, objcProvider.get(LINKOPT));
+    builder.addSequenceVariable(ATTR_LINKOPTS_VARIABLE_NAME, attributeLinkopts);
+  }
+
+  /** A Builder for {@link ObjcVariablesExtension}. */
+  static class Builder {
+    private RuleContext ruleContext;
+    private ObjcProvider objcProvider;
+    private CompilationArtifacts compilationArtifacts;
+    private Artifact fullyLinkArchive;
+    private IntermediateArtifacts intermediateArtifacts;
+    private BuildConfiguration buildConfiguration;
+    private Set<String> frameworkNames;
+    private ImmutableSet<Artifact> forceLoadArtifacts;
+    private ImmutableList<String> libraryNames;
+    private NestedSet<String> attributeLinkopts;
+    
+    private final ImmutableSet.Builder<VariableCategory> activeVariableCategoriesBuilder =
+        ImmutableSet.builder();
+
+    /** Sets the {@link RuleContext} for this extension. */
+    public Builder setRuleContext(RuleContext ruleContext) {
+      this.ruleContext = Preconditions.checkNotNull(ruleContext);
+      return this;
+    }
+
+    /** Sets the {@link ObjcProvider} for this extension. */
+    public Builder setObjcProvider(ObjcProvider objcProvider) {
+      this.objcProvider = Preconditions.checkNotNull(objcProvider);
+      return this;
+    }
+
+    /** Sets the {@link CompilationArtifacts} for this extension. */
+    public Builder setCompilationArtifacts(CompilationArtifacts compilationArtifacts) {
+      this.compilationArtifacts = Preconditions.checkNotNull(compilationArtifacts);
+      return this;
+    }
+
+    /** Sets the output of the fully link action. */
+    public Builder setFullyLinkArchive(Artifact fullyLinkArchive) {
+      this.fullyLinkArchive = Preconditions.checkNotNull(fullyLinkArchive);
+      return this;
+    }
+
+    /** Sets the {@link IntermediateArtifacts} for this extension. */
+    public Builder setIntermediateArtifacts(IntermediateArtifacts intermediateArtifacts) {
+      this.intermediateArtifacts = Preconditions.checkNotNull(intermediateArtifacts);
+      return this;
+    }
+
+    /** Sets the configuration for this extension. */
+    public Builder setConfiguration(BuildConfiguration buildConfiguration) {
+      this.buildConfiguration = Preconditions.checkNotNull(buildConfiguration);
+      return this;
+    }
+
+    /** Sets the framework names to be passed to the linker using {@code -framework}. */
+    public Builder setFrameworkNames(Set<String> frameworkNames) {
+      this.frameworkNames = Preconditions.checkNotNull(frameworkNames);
+      return this;
+    }
+    
+    /** Sets binary input files to be passed to the linker with "-l" flags. */
+    public Builder setLibraryNames(ImmutableList<String> libraryNames) {
+      this.libraryNames = Preconditions.checkNotNull(libraryNames);
+      return this;
+    }
+    
+    /** Sets artifacts to be passed to the linker with {@code -force_load}. */
+    public Builder setForceLoadArtifacts(ImmutableSet<Artifact> forceLoadArtifacts) {
+      this.forceLoadArtifacts = Preconditions.checkNotNull(forceLoadArtifacts);
+      return this;
+    }
+    
+    /** Sets linkopts arising from rule attributes. */
+    public Builder setAttributeLinkopts(NestedSet<String> attributeLinkopts) {
+      this.attributeLinkopts = Preconditions.checkNotNull(attributeLinkopts);
+      return this;
+    }
+    
+    /** Sets the given {@link VariableCategory} as active for this extension. */
+    public Builder addVariableCategory(VariableCategory variableCategory) {
+      this.activeVariableCategoriesBuilder.add(Preconditions.checkNotNull(variableCategory));
+      return this;
+    }
+
+    public ObjcVariablesExtension build() {
+      
+      ImmutableSet<VariableCategory> activeVariableCategories =
+          activeVariableCategoriesBuilder.build();
+      
+      Preconditions.checkNotNull(ruleContext, "missing RuleContext");
+      Preconditions.checkNotNull(objcProvider, "missing ObjcProvider");
+      Preconditions.checkNotNull(buildConfiguration, "missing BuildConfiguration");
+      Preconditions.checkNotNull(intermediateArtifacts, "missing IntermediateArtifacts");
+      if (activeVariableCategories.contains(VariableCategory.ARCHIVE_VARIABLES)) {
+        Preconditions.checkNotNull(compilationArtifacts, "missing CompilationArtifacts");
+      }
+      if (activeVariableCategories.contains(VariableCategory.FULLY_LINK_VARIABLES)) {
+        Preconditions.checkNotNull(fullyLinkArchive, "missing fully-link archive");
+      }
+      if (activeVariableCategories.contains(VariableCategory.EXECUTABLE_LINKING_VARIABLES)) {
+        Preconditions.checkNotNull(frameworkNames, "missing framework names");
+        Preconditions.checkNotNull(libraryNames, "missing library names");
+        Preconditions.checkNotNull(forceLoadArtifacts, "missing force-load artifacts");
+        Preconditions.checkNotNull(attributeLinkopts, "missing attribute linkopts");
+      }
+      
+      return new ObjcVariablesExtension(
+          ruleContext,
+          objcProvider,
+          compilationArtifacts,
+          fullyLinkArchive,
+          intermediateArtifacts,
+          buildConfiguration,
+          frameworkNames,
+          libraryNames,
+          forceLoadArtifacts,
+          attributeLinkopts,
+          activeVariableCategories);
+    }
+  }
 }