Collect mapping file from shrinking desugared library

Shrinking of desugared library can produce a mapping file. This
mapping file is now collected and merged with the mapping file
for the app.

RELNOTES: None
PiperOrigin-RevId: 420957173

src/main/java/com/google/devtools/build/lib/bazel/rules/android/BazelAndroidSemantics.java

@@ -91,12 +91,18 @@ public Artifact getProguardOutputMap(RuleContext ruleContext) throws Interrupted
   }
 
   /** Bazel does not currently support any dex postprocessing. */
+  @Override
+  public boolean postprocessClassesRewritesMap(RuleContext ruleContext) {
+    return false;
+  }
+
   @Override
   public AndroidBinary.DexPostprocessingOutput postprocessClassesDexZip(
       RuleContext ruleContext,
       NestedSetBuilder<Artifact> filesBuilder,
       Artifact classesDexZip,
-      ProguardOutput proguardOutput)
+      ProguardOutput proguardOutput,
+      Artifact proguardMapOutput)
       throws InterruptedException {
     return AndroidBinary.DexPostprocessingOutput.create(classesDexZip, proguardOutput.getMapping());
   }

src/main/java/com/google/devtools/build/lib/rules/android/AndroidBinary.java

@@ -448,9 +448,31 @@ public static RuleConfiguredTargetBuilder createAndroidBinary(
     // TODO(bazel-team): Verify that proguard spec files don't contain -printmapping directions
     // which this -printmapping command line flag will override.
     Artifact proguardOutputMap = null;
-    if (ProguardHelper.genProguardMapping(ruleContext.attributes())
-        || dataContext.isResourceShrinkingEnabled()) {
-      proguardOutputMap = androidSemantics.getProguardOutputMap(ruleContext);
+    boolean generateProguardMap =
+        ProguardHelper.genProguardMapping(ruleContext.attributes())
+            || dataContext.isResourceShrinkingEnabled();
+    boolean postprocessingRewritesMap = androidSemantics.postprocessClassesRewritesMap(ruleContext);
+    boolean desugarJava8LibsGeneratesMap =
+        AndroidCommon.getAndroidConfig(ruleContext).desugarJava8Libs();
+    if (generateProguardMap) {
+      // Determine the output of the Proguard map from shrinking the app. This depends on the
+      // additional steps which can process the map before the final Proguard map artifact is
+      // generated.
+      if (!hasProguardSpecs && !postprocessingRewritesMap) {
+        // When no shrinking happens a generating rule for the output map artifact is still needed.
+        proguardOutputMap = androidSemantics.getProguardOutputMap(ruleContext);
+      } else if (postprocessingRewritesMap) {
+        // Proguard map from shrinking goes to postprocessing.
+        proguardOutputMap =
+            ProguardHelper.getProguardTempArtifact(ruleContext, "proguard_output_for_rex.map");
+      } else if (desugarJava8LibsGeneratesMap) {
+        // Proguard map from shrinking will be merged with desugared library proguard map.
+        proguardOutputMap =
+            getDxArtifact(ruleContext, "_proguard_output_for_desugared_library.map");
+      } else {
+        // Proguard map from shrinking is the final output.
+        proguardOutputMap = androidSemantics.getProguardOutputMap(ruleContext);
+      }
     }
 
     ProguardOutput proguardOutput =
@@ -463,6 +485,36 @@ public static RuleConfiguredTargetBuilder createAndroidBinary(
             proguardMapping,
             proguardOutputMap);
 
+    // Determine the outputs for the proguard map transition through post-processing and adding of
+    // desugared library map.
+    Artifact postProcessingOutputMap = null;
+    Artifact finalProguardOutputMap = null;
+    if (proguardOutput.hasMapping()) {
+      // Determine the Proguard map artifacts for the additional steps (if any) if shrinking of
+      // the app is enabled.
+      if (postprocessingRewritesMap && desugarJava8LibsGeneratesMap) {
+        // Proguard map from preprocessing will be merged with Proguard map for desugared
+        // library.
+        postProcessingOutputMap =
+            getDxArtifact(ruleContext, "_proguard_output_for_desugared_library.map");
+        finalProguardOutputMap = androidSemantics.getProguardOutputMap(ruleContext);
+      } else if (postprocessingRewritesMap) {
+        // No desugared library, Proguard map from preprocessing is the final Proguard map.
+        postProcessingOutputMap = androidSemantics.getProguardOutputMap(ruleContext);
+        finalProguardOutputMap = postProcessingOutputMap;
+      } else if (desugarJava8LibsGeneratesMap) {
+        // No postprocessing, Proguard map from merging with the desugared library map is the
+        // final Proguard map.
+        postProcessingOutputMap = proguardOutputMap;
+        finalProguardOutputMap = androidSemantics.getProguardOutputMap(ruleContext);
+      } else {
+        // No postprocessing, no desugared library, the final Proguard map is the Proguard map
+        // from shrinking
+        postProcessingOutputMap = proguardOutputMap;
+        finalProguardOutputMap = proguardOutputMap;
+      }
+    }
+
     if (dataContext.useResourceShrinking(hasProguardSpecs)) {
       resourceApk =
           shrinkResources(
@@ -506,54 +558,45 @@ public static RuleConfiguredTargetBuilder createAndroidBinary(
 
     DexPostprocessingOutput dexPostprocessingOutput =
         androidSemantics.postprocessClassesDexZip(
-            ruleContext, filesBuilder, dexingOutput.classesDexZip, proguardOutput);
-
-    if (!proguardSpecs.isEmpty()) {
-      proguardOutput.addAllToSet(filesBuilder, dexPostprocessingOutput.proguardMap());
-    }
-
-    Artifact unsignedApk =
-        ruleContext.getImplicitOutputArtifact(AndroidRuleClasses.ANDROID_BINARY_UNSIGNED_APK);
-    Artifact zipAlignedApk =
-        ruleContext.getImplicitOutputArtifact(AndroidRuleClasses.ANDROID_BINARY_APK);
-    Artifact v4Signature =
-        (dataContext.getAndroidConfig().apkSigningMethodV4() != null
-                && dataContext.getAndroidConfig().apkSigningMethodV4())
-            ? ruleContext.getImplicitOutputArtifact(AndroidRuleClasses.ANDROID_BINARY_V4_SIGNATURE)
-            : null;
-    ImmutableList<Artifact> signingKeys = AndroidCommon.getApkDebugSigningKeys(ruleContext);
-    Artifact signingLineage = ruleContext.getPrerequisiteArtifact("debug_signing_lineage_file");
-    String keyRotationMinSdk = ruleContext.attributes().get("key_rotation_min_sdk", Type.STRING);
-    FilesToRunProvider resourceExtractor =
-        ruleContext.getExecutablePrerequisite("$resource_extractor");
+            ruleContext,
+            filesBuilder,
+            dexingOutput.classesDexZip,
+            proguardOutput,
+            postProcessingOutputMap);
 
+    // Compute the final DEX files by appending Java 8 legacy .dex if used.
     Artifact finalClassesDex;
+    Java8LegacyDexOutput java8LegacyDexOutput;
     ImmutableList<Artifact> finalShardDexZips = dexingOutput.shardDexZips;
     if (AndroidCommon.getAndroidConfig(ruleContext).desugarJava8Libs()
         && dexPostprocessingOutput.classesDexZip().getFilename().endsWith(".zip")) {
-      Artifact java8LegacyDex;
       if (binaryJar.equals(jarToDex)) {
-        // No Proguard: use canned Java 8 legacy .dex file
-        java8LegacyDex = ruleContext.getPrerequisiteArtifact("$java8_legacy_dex");
+        // No shrinking: use canned Java 8 legacy .dex file
+        java8LegacyDexOutput = Java8LegacyDexOutput.getCanned(ruleContext);
       } else {
-        // Proguard is used: build custom Java 8 legacy .dex file
-        java8LegacyDex = getDxArtifact(ruleContext, "_java8_legacy.dex.zip");
-        Artifact androidJar = AndroidSdkProvider.fromRuleContext(ruleContext).getAndroidJar();
-        ruleContext.registerAction(
-            createSpawnActionBuilder(ruleContext)
-                .setExecutable(ruleContext.getExecutablePrerequisite("$build_java8_legacy_dex"))
-                .addInput(jarToDex)
-                .addInput(androidJar)
-                .addOutput(java8LegacyDex)
-                .addCommandLine(
-                    CustomCommandLine.builder()
-                        .addExecPath("--binary", jarToDex)
-                        .addExecPath("--android_jar", androidJar)
-                        .addExecPath("--output", java8LegacyDex)
-                        .build())
-                .setMnemonic("BuildLegacyDex")
-                .setProgressMessage("Building Java 8 legacy library for %s", ruleContext.getLabel())
-                .build(ruleContext));
+        // Shrinking is used: build custom Java 8 legacy .dex file
+        java8LegacyDexOutput = buildJava8LegacyDex(ruleContext, jarToDex);
+
+        // Merge the mapping files from shrinking the program and Java 8 legacy .dex file.
+        if (finalProguardOutputMap != null) {
+          ruleContext.registerAction(
+              createSpawnActionBuilder(ruleContext)
+                  .useDefaultShellEnvironment()
+                  .setExecutable(ruleContext.getExecutablePrerequisite("$merge_proguard_maps"))
+                  .addInput(dexPostprocessingOutput.proguardMap())
+                  .addInput(java8LegacyDexOutput.getMap())
+                  .addOutput(finalProguardOutputMap)
+                  .addCommandLine(
+                      CustomCommandLine.builder()
+                          .addExecPath("--pg-map", dexPostprocessingOutput.proguardMap())
+                          .addExecPath("--pg-map", java8LegacyDexOutput.getMap())
+                          .addExecPath("--pg-map-output", finalProguardOutputMap)
+                          .build())
+                  .setMnemonic("MergeProguardMaps")
+                  .setProgressMessage(
+                      "Merging app and desugared library Proguard maps for %{label}")
+                  .build(ruleContext));
+        }
       }
 
       // Append legacy .dex library to app's .dex files
@@ -565,22 +608,45 @@ public static RuleConfiguredTargetBuilder createAndroidBinary(
               .setProgressMessage("Adding Java 8 legacy library for %s", ruleContext.getLabel())
               .setExecutable(ruleContext.getExecutablePrerequisite("$merge_dexzips"))
               .addInput(dexPostprocessingOutput.classesDexZip())
-              .addInput(java8LegacyDex)
+              .addInput(java8LegacyDexOutput.getDex())
               .addOutput(finalClassesDex)
               // Order matters here: we want java8LegacyDex to be the highest-numbered classesN.dex
               .addCommandLine(
                   CustomCommandLine.builder()
                       .addExecPath("--input_zip", dexPostprocessingOutput.classesDexZip())
-                      .addExecPath("--input_zip", java8LegacyDex)
+                      .addExecPath("--input_zip", java8LegacyDexOutput.getDex())
                       .addExecPath("--output_zip", finalClassesDex)
                       .build())
               .build(ruleContext));
       finalShardDexZips =
-          ImmutableList.<Artifact>builder().addAll(finalShardDexZips).add(java8LegacyDex).build();
+          ImmutableList.<Artifact>builder()
+              .addAll(finalShardDexZips)
+              .add(java8LegacyDexOutput.getDex())
+              .build();
+
     } else {
       finalClassesDex = dexPostprocessingOutput.classesDexZip();
     }
 
+    if (hasProguardSpecs) {
+      proguardOutput.addAllToSet(filesBuilder, finalProguardOutputMap);
+    }
+
+    Artifact unsignedApk =
+        ruleContext.getImplicitOutputArtifact(AndroidRuleClasses.ANDROID_BINARY_UNSIGNED_APK);
+    Artifact zipAlignedApk =
+        ruleContext.getImplicitOutputArtifact(AndroidRuleClasses.ANDROID_BINARY_APK);
+    Artifact v4Signature =
+        (dataContext.getAndroidConfig().apkSigningMethodV4() != null
+                && dataContext.getAndroidConfig().apkSigningMethodV4())
+            ? ruleContext.getImplicitOutputArtifact(AndroidRuleClasses.ANDROID_BINARY_V4_SIGNATURE)
+            : null;
+    ImmutableList<Artifact> signingKeys = AndroidCommon.getApkDebugSigningKeys(ruleContext);
+    Artifact signingLineage = ruleContext.getPrerequisiteArtifact("debug_signing_lineage_file");
+    String keyRotationMinSdk = ruleContext.attributes().get("key_rotation_min_sdk", Type.STRING);
+    FilesToRunProvider resourceExtractor =
+        ruleContext.getExecutablePrerequisite("$resource_extractor");
+
     ApkActionsBuilder.create("apk")
         .setClassesDex(finalClassesDex)
         .addInputZip(resourceApk.getArtifact())
@@ -759,6 +825,59 @@ public static RuleConfiguredTargetBuilder createAndroidBinary(
         .addOutputGroup("android_deploy_info", deployInfo);
   }
 
+  static class Java8LegacyDexOutput {
+    private final Artifact dex;
+    private final Artifact map;
+
+    private Java8LegacyDexOutput(Artifact dex, Artifact map) {
+      this.dex = dex;
+      this.map = map;
+    }
+
+    static Java8LegacyDexOutput getCanned(RuleContext ruleContext) {
+      return new Java8LegacyDexOutput(
+          ruleContext.getPrerequisiteArtifact("$java8_legacy_dex"), null);
+    }
+
+    boolean isEmpty() {
+      return dex == null;
+    }
+
+    public Artifact getDex() {
+      return dex;
+    }
+
+    public Artifact getMap() {
+      return map;
+    }
+  }
+
+  static Java8LegacyDexOutput buildJava8LegacyDex(RuleContext ruleContext, Artifact jarToDex) {
+    Artifact java8LegacyDexRules = getDxArtifact(ruleContext, "_java8_legacy.dex.pgcfg");
+    Artifact java8LegacyDex = getDxArtifact(ruleContext, "_java8_legacy.dex.zip");
+    Artifact java8LegacyDexMap = getDxArtifact(ruleContext, "_java8_legacy.dex.map");
+    Artifact androidJar = AndroidSdkProvider.fromRuleContext(ruleContext).getAndroidJar();
+    ruleContext.registerAction(
+        createSpawnActionBuilder(ruleContext)
+            .setExecutable(ruleContext.getExecutablePrerequisite("$build_java8_legacy_dex"))
+            .addInput(jarToDex)
+            .addInput(androidJar)
+            .addOutput(java8LegacyDexRules)
+            .addOutput(java8LegacyDex)
+            .addOutput(java8LegacyDexMap)
+            .addCommandLine(
+                CustomCommandLine.builder()
+                    .addExecPath("--rules", java8LegacyDexRules)
+                    .addExecPath("--binary", jarToDex)
+                    .addExecPath("--android_jar", androidJar)
+                    .addExecPath("--output", java8LegacyDex)
+                    .addExecPath("--output_map", java8LegacyDexMap)
+                    .build())
+            .setMnemonic("BuildLegacyDex")
+            .setProgressMessage("Building Java 8 legacy library for %{label}")
+            .build(ruleContext));
+    return new Java8LegacyDexOutput(java8LegacyDex, java8LegacyDexMap);
+  }
   /**
    * For coverage builds, this returns a Jar containing <b>un</b>instrumented bytecode for the
    * coverage reporter's consumption. This method simply returns the deploy Jar. Note the deploy Jar
@@ -902,7 +1021,7 @@ private static ProguardOutput createEmptyProguardAction(
             failures.build().toSet(),
             "Can't run Proguard without proguard_specs",
             Code.PROGUARD_SPECS_MISSING));
-    return new ProguardOutput(deployJarArtifact, null, null, null, null, null, null);
+    return ProguardOutput.createEmpty(deployJarArtifact);
   }
 
   static ImmutableList<Artifact> getProguardSpecs(

src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java

@@ -683,6 +683,10 @@ removed from the APK. This is only supported for rules using local resources (i.
           .add(
               attr("$desugared_java8_legacy_apis", LABEL)
                   .value(env.getToolsLabel("//tools/android:desugared_java8_legacy_apis")))
+          .add(
+              attr("$merge_proguard_maps", LABEL)
+                  .exec()
+                  .value(env.getToolsLabel("//tools/android:merge_proguard_maps")))
           /* <!-- #BLAZE_RULE($android_binary_base).ATTRIBUTE(dexopts) -->
           Additional command-line flags for the dx tool when generating classes.dex.
           Subject to <a href="${link make-variables}">"Make variable"</a> substitution and

src/main/java/com/google/devtools/build/lib/rules/android/AndroidSemantics.java

@@ -109,12 +109,15 @@ default void validateAndroidLibraryRuleContext(RuleContext ruleContext)
   /** The artifact for the map that proguard will output. */
   Artifact getProguardOutputMap(RuleContext ruleContext) throws InterruptedException;
 
+  boolean postprocessClassesRewritesMap(RuleContext ruleContext);
+
   /** Maybe post process the dex files and proguard output map. */
   AndroidBinary.DexPostprocessingOutput postprocessClassesDexZip(
       RuleContext ruleContext,
       NestedSetBuilder<Artifact> filesBuilder,
       Artifact classesDexZip,
-      ProguardOutput proguardOutput)
+      ProguardOutput proguardOutput,
+      Artifact proguardMapOutput)
       throws InterruptedException;
 
   default AndroidDataContext makeContextForNative(RuleContext ruleContext) {

src/main/java/com/google/devtools/build/lib/rules/android/ProguardHelper.java

@@ -81,10 +81,18 @@ public ProguardOutput(
       this.config = config;
     }
 
+    public static ProguardOutput createEmpty(Artifact outputJar) {
+      return new ProguardOutput(outputJar, null, null, null, null, null, null);
+    }
+
     public Artifact getOutputJar() {
       return outputJar;
     }
 
+    public boolean hasMapping() {
+      return mapping != null;
+    }
+
     @Nullable
     public Artifact getMapping() {
       return mapping;

src/test/java/com/google/devtools/build/lib/analysis/mock/BazelAnalysisMock.java

@@ -428,6 +428,7 @@ private ImmutableList<String> createAndroidBuildContents() {
         .add("filegroup(name = 'desugar_java8_extra_bootclasspath', srcs = ['fake.jar'])")
         .add("filegroup(name = 'java8_legacy_dex', srcs = ['java8_legacy.dex.zip'])")
         .add("sh_binary(name = 'build_java8_legacy_dex', srcs = ['empty.sh'])")
+        .add("sh_binary(name = 'merge_proguard_maps', srcs = ['empty.sh'])")
         .add("filegroup(name = 'desugared_java8_legacy_apis', srcs = ['fake.jar'])")
         .add("sh_binary(name = 'aar_native_libs_zip_creator', srcs = ['empty.sh'])")
         .add("sh_binary(name = 'resource_extractor', srcs = ['empty.sh'])")