Properly expose R.class file to Skylark

Add the R.class to the provider, but keep it nullable in case no
resource/manifest attributes were specified, in which case the R.class would
not be generated.

A previous change tried to actually generate it in that case, but even though I
think that's probably the right strategy for the long term, it's substantially
different behavior and out of scope of this migration.

RELNOTES: none
PiperOrigin-RevId: 195682271

3 files changed, 40 insertions, 26 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourcesInfo.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourcesInfo.java
index 6f1d665be4..f08b2ceb91 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourcesInfo.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourcesInfo.java
@@ -22,6 +22,7 @@ import com.google.devtools.build.lib.packages.NativeProvider;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
+import javax.annotation.Nullable;
 
 /** A provider that supplies ResourceContainers from its transitive closure. */
 @SkylarkModule(
@@ -53,6 +54,23 @@ public class AndroidResourcesInfo extends NativeInfo {
   private final Artifact rTxt;
 
   /*
+   * An R.class file for this target that can be used to build Java source.
+   *
+   * This class file should not be used for any targets besides the one that exposes this provider
+   * instance - even similar targets can have very different R.class files. In particular, final
+   * R.class files (for android_binary and similar rules) are generated very differently than
+   * R.class files for android_library - the latter are meant to be thrown away after building local
+   * Java classes.
+   *
+   * An R.class file is exposed rather than an R.java file because generating the R.class from the
+   * R.txt file is quicker than compiling the R.java file.
+   *
+   * An R.class file will not be produced for android_library targets that do not specify a manifest
+   * or resource files.
+   */
+  @Nullable private final Artifact rClassJar;
+
+  /*
    * Transitive information used for resource processing
    */
 
@@ -71,6 +89,7 @@ public class AndroidResourcesInfo extends NativeInfo {
       Label label,
       ProcessedAndroidManifest manifest,
       Artifact rTxt,
+      @Nullable Artifact rClassJar,
       NestedSet<ValidatedAndroidData> transitiveAndroidResources,
       NestedSet<ValidatedAndroidData> directAndroidResources,
       NestedSet<Artifact> transitiveResources,
@@ -85,6 +104,7 @@ public class AndroidResourcesInfo extends NativeInfo {
     this.label = label;
     this.manifest = manifest;
     this.rTxt = rTxt;
+    this.rClassJar = rClassJar;
     this.transitiveAndroidResources = transitiveAndroidResources;
     this.directAndroidResources = directAndroidResources;
     this.transitiveResources = transitiveResources;
@@ -111,6 +131,19 @@ public class AndroidResourcesInfo extends NativeInfo {
     return rTxt;
   }
 
+  @SkylarkCallable(
+      name = "r_class_jar",
+      structField = true,
+      allowReturnNones = true,
+      doc =
+          "Returns a JAR of R.class files for this target, for use in compiling this target's Java"
+              + " code. This JAR is only accurate for this target, and should not be used in any"
+              + " way for other targets. The JAR will not be available for android_library targets"
+              + " that do not specify resources or manifest.")
+  public Artifact getRClassJar() {
+    return rClassJar;
+  }
+
   /** Returns the transitive ResourceContainers for the label. */
   @SkylarkCallable(
     name = "transitive_android_resources",
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/ResourceApk.java b/src/main/java/com/google/devtools/build/lib/rules/android/ResourceApk.java
index cc826a067c..d69254268b 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/ResourceApk.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/ResourceApk.java
@@ -219,7 +219,7 @@ public final class ResourceApk {
    */
   AndroidResourcesInfo toResourceInfo(Label label) {
     if (validatedResources == null) {
-      return resourceDeps.toInfo(label, manifest, rTxt);
+      return resourceDeps.toInfo(label, manifest, rTxt, resourceJavaClassJar);
     }
     return resourceDeps.toInfo(validatedResources);
   }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/ResourceDependencies.java b/src/main/java/com/google/devtools/build/lib/rules/android/ResourceDependencies.java
index 09ac5afbb3..1631db5992 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/ResourceDependencies.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/ResourceDependencies.java
@@ -137,28 +137,6 @@ public final class ResourceDependencies {
         transitiveRTxt.build());
   }
 
-  static ResourceDependencies wrapManifestInfo(Label label, AndroidManifestInfo manifestInfo) {
-    return new ResourceDependencies(
-        false,
-        NestedSetBuilder.emptySet(Order.NAIVE_LINK_ORDER),
-        NestedSetBuilder.create(
-            Order.NAIVE_LINK_ORDER,
-            ResourceContainer.builder()
-                .setManifest(manifestInfo.getManifest())
-                .setJavaPackage(manifestInfo.getPackage())
-                .setManifestExported(manifestInfo.exportsManifest())
-                .setLabel(label)
-                .build()),
-        NestedSetBuilder.emptySet(Order.NAIVE_LINK_ORDER),
-        NestedSetBuilder.emptySet(Order.NAIVE_LINK_ORDER),
-        NestedSetBuilder.create(Order.NAIVE_LINK_ORDER, manifestInfo.getManifest()),
-        NestedSetBuilder.emptySet(Order.NAIVE_LINK_ORDER),
-        NestedSetBuilder.emptySet(Order.NAIVE_LINK_ORDER),
-        NestedSetBuilder.emptySet(Order.NAIVE_LINK_ORDER),
-        NestedSetBuilder.emptySet(Order.NAIVE_LINK_ORDER),
-        NestedSetBuilder.emptySet(Order.NAIVE_LINK_ORDER));
-  }
-
   @Override
   public String toString() {
     return MoreObjects.toStringHelper(this)
@@ -276,12 +254,14 @@ public final class ResourceDependencies {
           .toInfo(
               newDirectResource.getLabel(),
               newDirectResource.getProcessedManifest(),
-              newDirectResource.getRTxt());
+              newDirectResource.getRTxt(),
+              newDirectResource.getJavaClassJar());
     }
     return new AndroidResourcesInfo(
         newDirectResource.getLabel(),
         newDirectResource.getProcessedManifest(),
         newDirectResource.getRTxt(),
+        newDirectResource.getJavaClassJar(),
         NestedSetBuilder.<ValidatedAndroidData>naiveLinkOrder()
             .addTransitive(transitiveResourceContainers)
             .addTransitive(directResourceContainers)
@@ -314,14 +294,15 @@ public final class ResourceDependencies {
    * @return A provider with the current resources and label.
    */
   public AndroidResourcesInfo toInfo(
-      Label label, ProcessedAndroidManifest manifest, Artifact rTxt) {
+      Label label, ProcessedAndroidManifest manifest, Artifact rTxt, @Nullable Artifact rClassJar) {
     if (neverlink) {
-      return ResourceDependencies.empty().toInfo(label, manifest, rTxt);
+      return ResourceDependencies.empty().toInfo(label, manifest, rTxt, rClassJar);
     }
     return new AndroidResourcesInfo(
         label,
         manifest,
         rTxt,
+        rClassJar,
         transitiveResourceContainers,
         directResourceContainers,
         transitiveResources,