Added an optional option --j2objc_dead_code_report

--j2objc_dead_cdoe_report accepts a label that can generate a dead code report as argument. If specified, Blaze should pass "--dead-code-report path/to/dead/code/report" to J2ObjC.

RELNOTES: None.
PiperOrigin-RevId: 152712841

3 files changed, 44 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java
index 7ad3ccdb23..4b22b03fca 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java
@@ -108,6 +108,14 @@ public class J2ObjcAspect extends NativeAspectClass implements ConfiguredAspectF
   protected static final ImmutableList<String> J2OBJC_PLUGIN_PARAMS =
       ImmutableList.of("file_dir_mapping", "generate_class_mappings");
 
+  private static final LateBoundLabel<BuildConfiguration> DEAD_CODE_REPORT =
+      new LateBoundLabel<BuildConfiguration>(J2ObjcConfiguration.class) {
+    @Override
+    public Label resolve(Rule rule, AttributeMap attributes, BuildConfiguration configuration) {
+      return configuration.getFragment(J2ObjcConfiguration.class).deadCodeReport().orNull();
+    }
+  };
+
   private static final LateBoundLabel<BuildConfiguration> JRE_LIB =
       new LateBoundLabel<BuildConfiguration>(JRE_CORE_LIB, J2ObjcConfiguration.class) {
     @Override
@@ -186,6 +194,10 @@ public class J2ObjcAspect extends NativeAspectClass implements ConfiguredAspectF
                 .value(
                     Label.parseAbsoluteUnchecked(
                         toolsRepository + "//third_party/java/j2objc:jre_emul.jar")))
+        .add(
+            attr(":dead_code_report", LABEL)
+                .cfg(HOST)
+                .value(DEAD_CODE_REPORT))
         .add(attr(":jre_lib", LABEL).value(JRE_LIB))
         .add(
             attr("$protobuf_lib", LABEL)
@@ -542,6 +554,11 @@ public class J2ObjcAspect extends NativeAspectClass implements ConfiguredAspectF
     Artifact bootclasspathJar = ruleContext.getPrerequisiteArtifact("$jre_emul_jar", Mode.HOST);
     argBuilder.add("-Xbootclasspath:" + bootclasspathJar.getExecPathString());
 
+    Artifact deadCodeReport = ruleContext.getPrerequisiteArtifact(":dead_code_report", Mode.HOST);
+    if (deadCodeReport != null) {
+      argBuilder.addExecPath("--dead-code-report", deadCodeReport);
+    }
+
     argBuilder.add("-d").addPath(j2ObjcSource.getObjcFilePath());
 
     NestedSet<Artifact> compileTimeJars =
@@ -580,6 +597,11 @@ public class J2ObjcAspect extends NativeAspectClass implements ConfiguredAspectF
             .addOutputs(j2ObjcSource.getObjcHdrs())
             .addOutput(outputDependencyMappingFile)
             .addOutput(archiveSourceMappingFile);
+
+    if (deadCodeReport != null) {
+      transpilationAction.addInput(deadCodeReport);
+    }
+
     if (!experimentalJ2ObjcHeaderMap) {
       transpilationAction.addOutput(outputHeaderMappingFile);
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcCommandLineOptions.java b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcCommandLineOptions.java
index 4c6a42c67a..14d513627b 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcCommandLineOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcCommandLineOptions.java
@@ -15,6 +15,7 @@
 package com.google.devtools.build.lib.rules.objc;
 
 import com.google.common.collect.Multimap;
+import com.google.devtools.build.lib.analysis.config.BuildConfiguration.LabelConverter;
 import com.google.devtools.build.lib.analysis.config.FragmentOptions;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.common.options.Converters;
@@ -44,6 +45,15 @@ public class J2ObjcCommandLineOptions extends FragmentOptions {
       )
   public boolean removeDeadCode;
 
+  @Option(name = "j2objc_dead_code_report",
+      defaultValue = "null",
+      category = "undocumented",
+      converter = LabelConverter.class,
+      help = "Allows J2ObjC to strip dead code reported by ProGuard. Takes a label that can "
+          + "generate a dead code report as argument."
+  )
+  public Label deadCodeReport;
+
   @Option(name = "explicit_jre_deps",
       defaultValue = "true",
       category = "flags",
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcConfiguration.java
index 0253f6e386..b03de747b3 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcConfiguration.java
@@ -15,6 +15,7 @@
 package com.google.devtools.build.lib.rules.objc;
 
 import com.google.common.base.Joiner;
+import com.google.common.base.Optional;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration.Fragment;
@@ -22,6 +23,7 @@ import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.analysis.config.ConfigurationEnvironment;
 import com.google.devtools.build.lib.analysis.config.ConfigurationFragmentFactory;
 import com.google.devtools.build.lib.analysis.config.FragmentOptions;
+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;
 import com.google.devtools.build.lib.events.EventHandler;
@@ -88,11 +90,13 @@ public class J2ObjcConfiguration extends Fragment {
   private final boolean removeDeadCode;
   private final boolean explicitJreDeps;
   private final boolean experimentalJ2ObjcHeaderMap;
+  private final Optional<Label> deadCodeReport;
 
   J2ObjcConfiguration(J2ObjcCommandLineOptions j2ObjcOptions) {
     this.removeDeadCode = j2ObjcOptions.removeDeadCode;
     this.explicitJreDeps = j2ObjcOptions.explicitJreDeps;
     this.experimentalJ2ObjcHeaderMap = j2ObjcOptions.experimentalJ2ObjcHeaderMap;
+    this.deadCodeReport = Optional.fromNullable(j2ObjcOptions.deadCodeReport);
     this.translationFlags = ImmutableList.<String>builder()
         .addAll(J2OBJC_DEFAULT_TRANSLATION_FLAGS)
         .addAll(j2ObjcOptions.translationFlags)
@@ -112,6 +116,14 @@ public class J2ObjcConfiguration extends Fragment {
   }
 
   /**
+   * Returns the label of the dead code report generated by ProGuard for J2ObjC to eliminate dead
+   * code. The dead Java code in the report will not be translated to Objective-C code.
+   */
+  public Optional<Label> deadCodeReport() {
+    return deadCodeReport;
+  }
+
+  /**
    * Returns whether to perform J2ObjC dead code removal. If true, the list of entry classes will be
    * collected transitively throuh "entry_classes" attribute on j2objc_library and used as entry
    * points to perform dead code analysis. Unused classes will then be removed from the final ObjC