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

5 files changed, 92 insertions, 19 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchainFeatures.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchainFeatures.java
index ca464d2a1b..bf9e7c5367 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchainFeatures.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchainFeatures.java
@@ -1150,7 +1150,7 @@ public class CcToolchainFeatures implements Serializable {
        * Add a variable that expands a flag group containing a reference to {@code name} for each
        * entry in {@code values}.
        */
-      public Builder addSequenceVariable(String name, Collection<String> values) {
+      public Builder addSequenceVariable(String name, Iterable<String> values) {
         StringSequence.Builder sequenceBuilder = new StringSequence.Builder();
         for (String value : values) {
           sequenceBuilder.addValue(value);
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkAction.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkAction.java
index 44004745a0..04dc86895e 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkAction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkAction.java
@@ -95,6 +95,7 @@ public final class CppLinkAction extends AbstractAction
   private static final String LINK_GUID = "58ec78bd-1176-4e36-8143-439f656b181d";
   private static final String FAKE_LINK_GUID = "da36f819-5a15-43a9-8a45-e01b60e10c8b";
   
+  @Nullable private final String mnemonic;
   private final CppConfiguration cppConfiguration;
   private final LibraryToLink outputLibrary;
   private final Artifact linkOutput;
@@ -138,6 +139,7 @@ public final class CppLinkAction extends AbstractAction
    */
   CppLinkAction(
       ActionOwner owner,
+      String mnemonic,
       Iterable<Artifact> inputs,
       ImmutableList<Artifact> outputs,
       CppConfiguration cppConfiguration,
@@ -151,6 +153,11 @@ public final class CppLinkAction extends AbstractAction
       Map<String, String> toolchainEnv,
       ImmutableSet<String> executionRequirements) {
     super(owner, inputs, outputs);
+    if (mnemonic == null) {
+      this.mnemonic = (isLTOIndexing) ? "CppLTOIndexing" : "CppLink";
+    } else {
+      this.mnemonic = mnemonic;
+    }
     this.mandatoryInputs = inputs;
     this.cppConfiguration = cppConfiguration;
     this.outputLibrary = outputLibrary;
@@ -457,7 +464,7 @@ public final class CppLinkAction extends AbstractAction
 
   @Override
   public String getMnemonic() {
-    return (isLTOIndexing) ? "CppLTOIndexing" : "CppLink";
+    return mnemonic;
   }
 
   @Override
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkActionBuilder.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkActionBuilder.java
index f2690c6062..9fe8673389 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkActionBuilder.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkActionBuilder.java
@@ -124,6 +124,7 @@ public class CppLinkActionBuilder {
   @Nullable private final RuleContext ruleContext;
   private final AnalysisEnvironment analysisEnvironment;
   private final Artifact output;
+  @Nullable private String mnemonic;
 
   // can be null for CppLinkAction.createTestBuilder()
   @Nullable private final CcToolchainProvider toolchain;
@@ -162,7 +163,7 @@ public class CppLinkActionBuilder {
   private Iterable<LTOBackendArtifacts> allLTOArtifacts = null;
   
   private final List<VariablesExtension> variablesExtensions = new ArrayList<>();
-  private final List<Artifact> linkActionInputs = new ArrayList<>();
+  private final NestedSetBuilder<Artifact> linkActionInputs = NestedSetBuilder.stableOrder();
 
   /**
    * Creates a builder that builds {@link CppLinkAction} instances.
@@ -442,8 +443,11 @@ public class CppLinkActionBuilder {
 
   /** Builds the Action as configured and returns it. */
   public CppLinkAction build() throws InterruptedException {
-    Preconditions.checkState(
-        (libraryIdentifier == null) == (linkType == LinkTargetType.EXECUTABLE));
+    // Executable links do not have library identifiers.
+    boolean hasIdentifier = (libraryIdentifier != null);
+    boolean isExecutable = linkType.isExecutable();
+    Preconditions.checkState(hasIdentifier != isExecutable);    
+
     if (interfaceOutput != null && (fake || linkType != LinkTargetType.DYNAMIC_LIBRARY)) {
       throw new RuntimeException(
           "Interface output can only be used " + "with non-fake DYNAMIC_LIBRARY targets");
@@ -485,7 +489,7 @@ public class CppLinkActionBuilder {
       }
     }
 
-    final LibraryToLink outputLibrary = linkType == LinkTargetType.EXECUTABLE
+    final LibraryToLink outputLibrary = linkType.isExecutable()
         ? null
         : LinkerInputs.newInputLibrary(output,
             linkType.getLinkerOutput(),
@@ -651,7 +655,7 @@ public class CppLinkActionBuilder {
     NestedSetBuilder<Artifact> dependencyInputsBuilder = NestedSetBuilder.stableOrder();
     dependencyInputsBuilder.addTransitive(crosstoolInputs);
     dependencyInputsBuilder.add(toolchain.getLinkDynamicLibraryTool());
-    dependencyInputsBuilder.addAll(linkActionInputs);
+    dependencyInputsBuilder.addTransitive(linkActionInputs.build());
     if (runtimeMiddleman != null) {
       dependencyInputsBuilder.add(runtimeMiddleman);
     }
@@ -737,6 +741,7 @@ public class CppLinkActionBuilder {
 
     return new CppLinkAction(
         getOwner(),
+        mnemonic,
         inputsBuilder.deduplicate().build(),
         actionOutputs,
         cppConfiguration,
@@ -840,6 +845,12 @@ public class CppLinkActionBuilder {
   protected ActionOwner getOwner() {
     return ruleContext.getActionOwner();
   }
+  
+  /** Sets the mnemonic for the link action. */
+  public CppLinkActionBuilder setMnemonic(String mnemonic) {
+    this.mnemonic = mnemonic;
+    return this;
+  }
 
   /** Set the crosstool inputs required for the action. */
   public CppLinkActionBuilder setCrosstoolInputs(NestedSet<Artifact> inputs) {
@@ -1143,12 +1154,28 @@ public class CppLinkActionBuilder {
   }
   
   /**
-   * Sets extra input artifacts to the link action.
+   * Adds an extra input artifact to the link action.
+   */
+  public CppLinkActionBuilder addActionInput(Artifact input) {
+    this.linkActionInputs.add(input);
+    return this;
+  }
+  
+  /**
+   * Adds extra input artifacts to the link action.
    */
-  public CppLinkActionBuilder addActionInputs(Collection<Artifact> inputs) {
+  public CppLinkActionBuilder addActionInputs(Iterable<Artifact> inputs) {
     this.linkActionInputs.addAll(inputs);
     return this;
   }
+  
+  /**
+   * Adds extra input artifacts to the link actions.
+   */
+  public CppLinkActionBuilder addTransitiveActionInputs(NestedSet<Artifact> inputs) {
+    this.linkActionInputs.addTransitive(inputs);
+    return this;
+  }
 
   private static class LinkArgCollector {
     String rpathRoot;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/Link.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/Link.java
index ec51c8413f..74f33ab913 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/Link.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/Link.java
@@ -103,6 +103,14 @@ public abstract class Link {
     STATIC,
     DYNAMIC
   }
+  
+  /**
+   * Whether a particular link target is executable.
+   */
+  public enum Executable {
+    EXECUTABLE,
+    NOT_EXECUTABLE
+  }
 
   /**
    * Types of ELF files that can be created by the linker (.a, .so, .lo,
@@ -115,7 +123,8 @@ public abstract class Link {
         Staticness.STATIC,
         "c++-link-static-library",
         Picness.NOPIC,
-        ArtifactCategory.STATIC_LIBRARY),
+        ArtifactCategory.STATIC_LIBRARY,
+        Executable.NOT_EXECUTABLE),
     
     /** An objc static archive. */
     OBJC_ARCHIVE(
@@ -123,19 +132,35 @@ public abstract class Link {
         Staticness.STATIC, 
         "objc-archive", 
         Picness.NOPIC,
-        ArtifactCategory.STATIC_LIBRARY),
+        ArtifactCategory.STATIC_LIBRARY,
+        Executable.NOT_EXECUTABLE),
     
     /** An objc fully linked static archive. */
     OBJC_FULLY_LINKED_ARCHIVE(
-        ".a", Staticness.STATIC, "objc-fully-link", Picness.NOPIC, ArtifactCategory.STATIC_LIBRARY),
+        ".a",
+        Staticness.STATIC,
+        "objc-fully-link",
+        Picness.NOPIC,
+        ArtifactCategory.STATIC_LIBRARY,
+        Executable.NOT_EXECUTABLE),
 
+    /** An objc executable. */
+    OBJC_EXECUTABLE(
+        "",
+        Staticness.STATIC,
+        "objc-executable",
+        Picness.NOPIC,
+        ArtifactCategory.EXECUTABLE,
+        Executable.EXECUTABLE),
+    
     /** A static archive with .pic.o object files (compiled with -fPIC). */
     PIC_STATIC_LIBRARY(
         ".pic.a",
         Staticness.STATIC,
         "c++-link-pic-static-library",
         Picness.PIC,
-        ArtifactCategory.STATIC_LIBRARY),
+        ArtifactCategory.STATIC_LIBRARY,
+        Executable.NOT_EXECUTABLE),
 
     /** An interface dynamic library. */
     INTERFACE_DYNAMIC_LIBRARY(
@@ -143,7 +168,8 @@ public abstract class Link {
         Staticness.DYNAMIC,
         "c++-link-interface-dynamic-library",
         Picness.NOPIC,  // Actually PIC but it's not indicated in the file name
-        ArtifactCategory.INTERFACE_LIBRARY),
+        ArtifactCategory.INTERFACE_LIBRARY,
+        Executable.NOT_EXECUTABLE),
 
     /** A dynamic library. */
     DYNAMIC_LIBRARY(
@@ -151,7 +177,8 @@ public abstract class Link {
         Staticness.DYNAMIC,
         "c++-link-dynamic-library",
         Picness.NOPIC,  // Actually PIC but it's not indicated in the file name
-        ArtifactCategory.DYNAMIC_LIBRARY),
+        ArtifactCategory.DYNAMIC_LIBRARY,
+        Executable.NOT_EXECUTABLE),
 
     /** A static archive without removal of unused object files. */
     ALWAYS_LINK_STATIC_LIBRARY(
@@ -159,7 +186,8 @@ public abstract class Link {
         Staticness.STATIC,
         "c++-link-alwayslink-static-library",
         Picness.NOPIC,
-        ArtifactCategory.ALWAYSLINK_STATIC_LIBRARY),
+        ArtifactCategory.ALWAYSLINK_STATIC_LIBRARY,
+        Executable.NOT_EXECUTABLE),
 
     /** A PIC static archive without removal of unused object files. */
     ALWAYS_LINK_PIC_STATIC_LIBRARY(
@@ -167,7 +195,8 @@ public abstract class Link {
         Staticness.STATIC,
         "c++-link-alwayslink-pic-static-library",
         Picness.PIC,
-        ArtifactCategory.ALWAYSLINK_STATIC_LIBRARY),
+        ArtifactCategory.ALWAYSLINK_STATIC_LIBRARY,
+        Executable.NOT_EXECUTABLE),
 
     /** An executable binary. */
     EXECUTABLE(
@@ -175,25 +204,29 @@ public abstract class Link {
         Staticness.DYNAMIC,
         "c++-link-executable",
         Picness.NOPIC,  // Picness is not indicate in the file name
-        ArtifactCategory.EXECUTABLE);
+        ArtifactCategory.EXECUTABLE,
+        Executable.EXECUTABLE);
 
     private final String extension;
     private final Staticness staticness;
     private final String actionName;
     private final ArtifactCategory linkerOutput;
     private final Picness picness;
+    private final Executable executable;
 
     LinkTargetType(
         String extension,
         Staticness staticness,
         String actionName,
         Picness picness,
-        ArtifactCategory linkerOutput) {
+        ArtifactCategory linkerOutput,
+        Executable executable) {
       this.extension = extension;
       this.staticness = staticness;
       this.actionName = actionName;
       this.linkerOutput = linkerOutput;
       this.picness = picness;
+      this.executable = executable;
     }
 
     /**
@@ -223,6 +256,11 @@ public abstract class Link {
     public String getActionName() {
       return actionName;
     }
+    
+    /** Returns true iff this link type is executable */
+    public boolean isExecutable() {
+      return (executable == Executable.EXECUTABLE);
+    }
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkCommandLine.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkCommandLine.java
index 27e3e4db99..6a95202423 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkCommandLine.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkCommandLine.java
@@ -408,6 +408,7 @@ public final class LinkCommandLine extends CommandLine {
         // TODO(b/30109612): make this pattern the case for all link variants.
       case OBJC_ARCHIVE:
       case OBJC_FULLY_LINKED_ARCHIVE:
+      case OBJC_EXECUTABLE:
         argv.add(toolPath);
         argv.addAll(featureConfiguration.getCommandLine(actionName, variables));
         break;