Add exports attribute to proto_library.

Note that it is currently only used by the java_proto_library family of rules (if enabled per flag).

RELNOTES: None
PiperOrigin-RevId: 208601730

10 files changed, 314 insertions, 88 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaConfiguration.java
index 6bc1ed10d7..97cb73987f 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaConfiguration.java
@@ -154,6 +154,7 @@ public final class JavaConfiguration extends Fragment implements JavaConfigurati
   private final boolean generateJavaDeps;
   private final boolean strictDepsJavaProtos;
   private final boolean protoGeneratedStrictDeps;
+  private final boolean isJavaProtoExportsEnabled;
   private final OneVersionEnforcementLevel enforceOneVersion;
   private final boolean enforceOneVersionOnJavaTests;
   private final ImportDepsCheckingLevel importDepsCheckingLevel;
@@ -204,6 +205,7 @@ public final class JavaConfiguration extends Fragment implements JavaConfigurati
     this.useLegacyBazelJavaTest = javaOptions.legacyBazelJavaTest;
     this.strictDepsJavaProtos = javaOptions.strictDepsJavaProtos;
     this.protoGeneratedStrictDeps = javaOptions.protoGeneratedStrictDeps;
+    this.isJavaProtoExportsEnabled = javaOptions.isJavaProtoExportsEnabled;
     this.enforceOneVersion = javaOptions.enforceOneVersion;
     this.enforceOneVersionOnJavaTests = javaOptions.enforceOneVersionOnJavaTests;
     this.importDepsCheckingLevel = javaOptions.importDepsCheckingLevel;
@@ -246,6 +248,7 @@ public final class JavaConfiguration extends Fragment implements JavaConfigurati
       boolean generateJavaDeps,
       boolean strictDepsJavaProtos,
       boolean protoGeneratedStrictDeps,
+      boolean isJavaProtoExportsEnabled,
       OneVersionEnforcementLevel enforceOneVersion,
       boolean enforceOneVersionOnJavaTests,
       ImportDepsCheckingLevel importDepsCheckingLevel,
@@ -276,6 +279,7 @@ public final class JavaConfiguration extends Fragment implements JavaConfigurati
     this.generateJavaDeps = generateJavaDeps;
     this.strictDepsJavaProtos = strictDepsJavaProtos;
     this.protoGeneratedStrictDeps = protoGeneratedStrictDeps;
+    this.isJavaProtoExportsEnabled = isJavaProtoExportsEnabled;
     this.enforceOneVersion = enforceOneVersion;
     this.enforceOneVersionOnJavaTests = enforceOneVersionOnJavaTests;
     this.importDepsCheckingLevel = importDepsCheckingLevel;
@@ -512,6 +516,10 @@ public final class JavaConfiguration extends Fragment implements JavaConfigurati
     return protoGeneratedStrictDeps;
   }
 
+  public boolean isJavaProtoExportsEnabled() {
+    return isJavaProtoExportsEnabled;
+  }
+
   public boolean jplPropagateCcLinkParamsStore() {
     return jplPropagateCcLinkParamsStore;
   }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaOptions.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaOptions.java
index 5bb7e08106..2b9cbecf05 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaOptions.java
@@ -467,6 +467,16 @@ public class JavaOptions extends FragmentOptions {
   public boolean protoGeneratedStrictDeps;
 
   @Option(
+      name = "experimental_enable_java_proto_exports",
+      defaultValue = "false",
+      documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
+      effectTags = {OptionEffectTag.BUILD_FILE_SEMANTICS, OptionEffectTag.EAGERNESS_TO_EXIT},
+      help =
+          "Enables exports forwarding for proto_library targets depended on by "
+              + "java_proto_library targets.")
+  public boolean isJavaProtoExportsEnabled;
+
+  @Option(
     name = "experimental_java_header_compilation_disable_javac_fallback",
     defaultValue = "false",
     documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/proto/JavaLiteProtoAspect.java b/src/main/java/com/google/devtools/build/lib/rules/java/proto/JavaLiteProtoAspect.java
index 09cf02d0d1..a2649622d5 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/proto/JavaLiteProtoAspect.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/proto/JavaLiteProtoAspect.java
@@ -113,6 +113,7 @@ public class JavaLiteProtoAspect extends NativeAspectClass implements Configured
     AspectDefinition.Builder result =
         new AspectDefinition.Builder(this)
             .propagateAlongAttribute("deps")
+            .propagateAlongAttribute("exports")
             .requiresConfigurationFragments(JavaConfiguration.class, ProtoConfiguration.class)
             .requireProviders(ProtoSourcesProvider.class)
             .advertiseProvider(JavaProtoLibraryAspectProvider.class)
@@ -154,9 +155,14 @@ public class JavaLiteProtoAspect extends NativeAspectClass implements Configured
      */
     private final JavaCompilationArgsProvider dependencyCompilationArgs;
 
+    // Compilation-args from all exports, merged together.
+    private final JavaCompilationArgsProvider exportsCompilationArgs;
+
     private final JavaProtoAspectCommon aspectCommon;
     private final Iterable<JavaProtoLibraryAspectProvider> javaProtoLibraryAspectProviders;
 
+    private final boolean isJavaProtoExportsEnabled;
+
     Impl(
         RuleContext ruleContext,
         SupportData supportData,
@@ -172,6 +178,22 @@ public class JavaLiteProtoAspect extends NativeAspectClass implements Configured
           JavaCompilationArgsProvider.merge(
               WrappingProvider.Helper.unwrapProviders(
                   javaProtoLibraryAspectProviders, JavaCompilationArgsProvider.class));
+
+      this.isJavaProtoExportsEnabled =
+          ruleContext.getFragment(JavaConfiguration.class).isJavaProtoExportsEnabled();
+
+      if (this.isJavaProtoExportsEnabled) {
+        this.exportsCompilationArgs =
+            JavaCompilationArgsProvider.merge(
+                WrappingProvider.Helper.unwrapProviders(
+                    ruleContext.getPrerequisites(
+                        "exports",
+                        RuleConfiguredTarget.Mode.TARGET,
+                        JavaProtoLibraryAspectProvider.class),
+                    JavaCompilationArgsProvider.class));
+      } else {
+        this.exportsCompilationArgs = null;
+      }
     }
 
     void addProviders(ConfiguredAspect.Builder aspect) {
@@ -225,6 +247,12 @@ public class JavaLiteProtoAspect extends NativeAspectClass implements Configured
         javaProvidersBuilder.add(JavaRuleOutputJarsProvider.EMPTY);
       }
 
+      if (isJavaProtoExportsEnabled) {
+        generatedCompilationArgsProvider =
+            JavaCompilationArgsProvider.merge(
+                ImmutableList.of(generatedCompilationArgsProvider, exportsCompilationArgs));
+      }
+
       javaProvidersBuilder.add(generatedCompilationArgsProvider);
       javaProvidersBuilder.add(createCcLinkParamsStore(
           ruleContext, aspectCommon.getProtoRuntimeDeps()));
@@ -260,7 +288,9 @@ public class JavaLiteProtoAspect extends NativeAspectClass implements Configured
           ruleContext.getLabel(),
           ImmutableList.of(sourceJar),
           "JavaLite",
-          /* allowServices= */ true);
+          /* allowServices= */ true,
+          supportData.getProtosInExports(),
+          supportData.getExportedProtoSourceRoots());
     }
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/proto/JavaProtoAspect.java b/src/main/java/com/google/devtools/build/lib/rules/java/proto/JavaProtoAspect.java
index a86f703e9b..131c617650 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/proto/JavaProtoAspect.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/proto/JavaProtoAspect.java
@@ -121,6 +121,7 @@ public class JavaProtoAspect extends NativeAspectClass implements ConfiguredAspe
     AspectDefinition.Builder result =
         new AspectDefinition.Builder(this)
             .propagateAlongAttribute("deps")
+            .propagateAlongAttribute("exports")
             .requiresConfigurationFragments(JavaConfiguration.class, ProtoConfiguration.class)
             .requireProviders(ProtoSourcesProvider.class)
             .advertiseProvider(JavaProtoLibraryAspectProvider.class)
@@ -163,8 +164,13 @@ public class JavaProtoAspect extends NativeAspectClass implements ConfiguredAspe
      */
     private final JavaCompilationArgsProvider dependencyCompilationArgs;
 
+    // Compilation-args from all exports, merged together.
+    private final JavaCompilationArgsProvider exportsCompilationArgs;
+
     private final Iterable<JavaProtoLibraryAspectProvider> javaProtoLibraryAspectProviders;
 
+    private final boolean isJavaProtoExportsEnabled;
+
     Impl(
         RuleContext ruleContext,
         SupportData supportData,
@@ -178,10 +184,27 @@ public class JavaProtoAspect extends NativeAspectClass implements ConfiguredAspe
           ruleContext.getPrerequisites(
               "deps", RuleConfiguredTarget.Mode.TARGET, JavaProtoLibraryAspectProvider.class);
 
-      dependencyCompilationArgs =
+      this.dependencyCompilationArgs =
           JavaCompilationArgsProvider.merge(
               WrappingProvider.Helper.unwrapProviders(
                   javaProtoLibraryAspectProviders, JavaCompilationArgsProvider.class));
+
+      this.isJavaProtoExportsEnabled =
+          ruleContext.getFragment(JavaConfiguration.class).isJavaProtoExportsEnabled();
+
+      if (this.isJavaProtoExportsEnabled) {
+        this.exportsCompilationArgs =
+            JavaCompilationArgsProvider.merge(
+                WrappingProvider.Helper.unwrapProviders(
+                    ruleContext.getPrerequisites(
+                        "exports",
+                        RuleConfiguredTarget.Mode.TARGET,
+                        JavaProtoLibraryAspectProvider.class),
+                    JavaCompilationArgsProvider.class));
+      } else {
+        this.exportsCompilationArgs = null;
+      }
+
     }
 
     void addProviders(ConfiguredAspect.Builder aspect) {
@@ -235,6 +258,12 @@ public class JavaProtoAspect extends NativeAspectClass implements ConfiguredAspe
         javaProvidersBuilder.add(JavaRuleOutputJarsProvider.EMPTY);
       }
 
+      if (isJavaProtoExportsEnabled) {
+        generatedCompilationArgsProvider =
+            JavaCompilationArgsProvider.merge(
+                ImmutableList.of(generatedCompilationArgsProvider, exportsCompilationArgs));
+      }
+
       javaProvidersBuilder.add(generatedCompilationArgsProvider);
       javaProvidersBuilder.add(createCcLinkParamsStore(
           ruleContext, aspectCommon.getProtoRuntimeDeps()));
@@ -289,7 +318,9 @@ public class JavaProtoAspect extends NativeAspectClass implements ConfiguredAspe
           ruleContext.getLabel(),
           ImmutableList.of(sourceJar),
           "Java (Immutable)",
-          rpcSupport.allowServices(ruleContext));
+          rpcSupport.allowServices(ruleContext),
+          supportData.getProtosInExports(),
+          supportData.getExportedProtoSourceRoots());
     }
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/proto/BazelProtoLibrary.java b/src/main/java/com/google/devtools/build/lib/rules/proto/BazelProtoLibrary.java
index 000aa5ec53..ac8fcc8a85 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/proto/BazelProtoLibrary.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/proto/BazelProtoLibrary.java
@@ -62,7 +62,9 @@ public class BazelProtoLibrary implements RuleConfiguredTargetFactory {
             protoPathFlags,
             protoSourceRoot,
             directProtoSourceRoots,
-            !protoSources.isEmpty());
+            !protoSources.isEmpty(),
+            /* protosInExports= */ null,
+            /* exportedProtoSourceRoots= */ null);
 
     Artifact descriptorSetOutput =
         ruleContext.getGenfilesArtifact(
diff --git a/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoCommon.java b/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoCommon.java
index f3cc3d6751..cb9dbb6818 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoCommon.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoCommon.java
@@ -140,19 +140,19 @@ public class ProtoCommon {
 
   /**
    * Returns a set of the {@code proto_source_root} collected from the current library and the
-   * direct dependencies.
+   * specified attribute.
    *
    * <p>Assumes {@code currentProtoSourceRoot} is the same as the package name.
    */
-  public static NestedSet<String> getProtoSourceRootsOfDirectDependencies(
-      RuleContext ruleContext, String currentProtoSourceRoot) {
+  private static NestedSet<String> getProtoSourceRootsOfAttribute(
+      RuleContext ruleContext, String currentProtoSourceRoot, String attributeName) {
     NestedSetBuilder<String> protoSourceRoots = NestedSetBuilder.stableOrder();
     if (currentProtoSourceRoot != null && !currentProtoSourceRoot.isEmpty()) {
       protoSourceRoots.add(currentProtoSourceRoot);
     }
 
     for (ProtoSourcesProvider provider :
-        ruleContext.getPrerequisites("deps", Mode.TARGET, ProtoSourcesProvider.class)) {
+        ruleContext.getPrerequisites(attributeName, Mode.TARGET, ProtoSourcesProvider.class)) {
       String protoSourceRoot = provider.getProtoSourceRoot();
       if (protoSourceRoot != null && !protoSourceRoot.isEmpty()) {
         protoSourceRoots.add(provider.getProtoSourceRoot());
@@ -162,6 +162,28 @@ public class ProtoCommon {
     return protoSourceRoots.build();
   }
 
+  /**
+   * Returns a set of the {@code proto_source_root} collected from the current library and the
+   * direct dependencies.
+   *
+   * <p>Assumes {@code currentProtoSourceRoot} is the same as the package name.
+   */
+  public static NestedSet<String> getProtoSourceRootsOfDirectDependencies(
+      RuleContext ruleContext, String currentProtoSourceRoot) {
+    return getProtoSourceRootsOfAttribute(ruleContext, currentProtoSourceRoot, "deps");
+  }
+
+  /**
+   * Returns a set of the {@code proto_source_root} collected from the current library and the
+   * exported dependencies.
+   *
+   * <p>Assumes {@code currentProtoSourceRoot} is the same as the package name.
+   */
+  public static NestedSet<String> getProtoSourceRootsOfExportedDependencies(
+      RuleContext ruleContext, String currentProtoSourceRoot) {
+    return getProtoSourceRootsOfAttribute(ruleContext, currentProtoSourceRoot, "exports");
+  }
+
   private static void checkProtoSourceRootIsTheSameAsPackage(
       String protoSourceRoot, RuleContext ruleContext) {
     if (!ruleContext.getLabel().getPackageName().equals(protoSourceRoot)) {
@@ -272,6 +294,19 @@ public class ProtoCommon {
   }
 
   /**
+   * Returns the .proto files that are the direct srcs of the exported dependencies of this rule.
+   */
+  @Nullable
+  public static NestedSet<Artifact> computeProtosInExportedDeps(RuleContext ruleContext) {
+    NestedSetBuilder<Artifact> result = NestedSetBuilder.stableOrder();
+    for (ProtoSupportDataProvider provider :
+        ruleContext.getPrerequisites("exports", TARGET, ProtoSupportDataProvider.class)) {
+      result.addTransitive(provider.getSupportData().getProtosInDirectDeps());
+    }
+    return result.build();
+  }
+
+  /**
    * Decides whether this proto_library should check for strict proto deps.
    *
    * <p>Takes into account command-line flags, package-level attributes and rule attributes.
diff --git a/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoCompileActionBuilder.java b/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoCompileActionBuilder.java
index da43b6a2a4..9f2217cd62 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoCompileActionBuilder.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoCompileActionBuilder.java
@@ -351,8 +351,10 @@ public class ProtoCompileActionBuilder {
             protosToCompile,
             transitiveSources,
             protosInDirectDeps,
+            /* protosInExports= */ null,
             protoSourceRoots,
             directProtoSourceRoots,
+            /* exportedProtoSourceRoots= */ null,
             ruleContext.getLabel(),
             ImmutableList.of(output),
             "Descriptor Set",
@@ -381,6 +383,34 @@ public class ProtoCompileActionBuilder {
         outReplacement);
   }
 
+  public static void registerActions(
+      RuleContext ruleContext,
+      List<ToolchainInvocation> toolchainInvocations,
+      Iterable<Artifact> protosToCompile,
+      NestedSet<Artifact> transitiveSources,
+      NestedSet<Artifact> protosInDirectDeps,
+      NestedSet<String> protoSourceRoots,
+      NestedSet<String> directProtoSourceRoots,
+      Label ruleLabel,
+      Iterable<Artifact> outputs,
+      String flavorName,
+      boolean allowServices) {
+    registerActions(
+        ruleContext,
+        toolchainInvocations,
+        protosToCompile,
+        transitiveSources,
+        protosInDirectDeps,
+        protoSourceRoots,
+        directProtoSourceRoots,
+        ruleLabel,
+        outputs,
+        flavorName,
+        allowServices,
+        /* protosInExports= */ null,
+        /* exportedProtoSourceRoots= */ null);
+  }
+
   /**
    * Registers actions to generate code from .proto files.
    *
@@ -404,7 +434,9 @@ public class ProtoCompileActionBuilder {
       Label ruleLabel,
       Iterable<Artifact> outputs,
       String flavorName,
-      boolean allowServices) {
+      boolean allowServices,
+      NestedSet<Artifact> protosInExports,
+      NestedSet<String> exportedProtoSourceRoots) {
     SpawnAction.Builder actions =
         createActions(
             ruleContext,
@@ -412,8 +444,10 @@ public class ProtoCompileActionBuilder {
             protosToCompile,
             transitiveSources,
             protosInDirectDeps,
+            protosInExports,
             protoSourceRoots,
             directProtoSourceRoots,
+            exportedProtoSourceRoots,
             ruleLabel,
             outputs,
             flavorName,
@@ -430,8 +464,10 @@ public class ProtoCompileActionBuilder {
       Iterable<Artifact> protosToCompile,
       NestedSet<Artifact> transitiveSources,
       @Nullable NestedSet<Artifact> protosInDirectDeps,
+      @Nullable NestedSet<Artifact> protosInExports,
       NestedSet<String> protoSourceRoots,
       NestedSet<String> directProtoSourceRoots,
+      @Nullable NestedSet<String> exportedProtoSourceRoots,
       Label ruleLabel,
       Iterable<Artifact> outputs,
       String flavorName,
@@ -468,7 +504,9 @@ public class ProtoCompileActionBuilder {
                 transitiveSources,
                 protoSourceRoots,
                 directProtoSourceRoots,
+                exportedProtoSourceRoots,
                 areDepsStrict(ruleContext) ? protosInDirectDeps : null,
+                arePublicImportsStrict(ruleContext) ? protosInExports : null,
                 ruleLabel,
                 allowServices,
                 ruleContext.getFragment(ProtoConfiguration.class).protocOpts()),
@@ -479,6 +517,10 @@ public class ProtoCompileActionBuilder {
     return result;
   }
 
+  public static boolean arePublicImportsStrict(RuleContext ruleContext) {
+    return ruleContext.getFragment(ProtoConfiguration.class).strictPublicImports();
+  }
+
   /**
    * Constructs command-line arguments to execute proto-compiler.
    *
@@ -506,7 +548,9 @@ public class ProtoCompileActionBuilder {
       NestedSet<Artifact> transitiveSources,
       NestedSet<String> transitiveProtoPathFlags,
       NestedSet<String> directProtoSourceRoots,
+      NestedSet<String> exportedProtoSourceRoots,
       @Nullable NestedSet<Artifact> protosInDirectDeps,
+      @Nullable NestedSet<Artifact> protosInExports,
       Label ruleLabel,
       boolean allowServices,
       ImmutableList<String> protocOpts) {
@@ -554,6 +598,19 @@ public class ProtoCompileActionBuilder {
       cmdLine.addFormatted(STRICT_DEPS_FLAG_TEMPLATE, ruleLabel);
     }
 
+    if (protosInExports != null) {
+      if (protosInExports.isEmpty()) {
+        // This line is necessary to trigger the check.
+        cmdLine.add("--allowed_public_imports=");
+      } else {
+        cmdLine.addAll(
+            "--allowed_public_imports",
+            VectorArg.join(":")
+                .each(protosInExports)
+                .mapped(new ExpandToPathFn(exportedProtoSourceRoots)));
+      }
+    }
+
     for (Artifact src : protosToCompile) {
       cmdLine.addPath(src.getExecPath());
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoConfiguration.java
index 3d19e8c7e7..8731315b51 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoConfiguration.java
@@ -146,6 +146,15 @@ public class ProtoConfiguration extends Fragment implements ProtoConfigurationAp
     )
     public List<String> ccProtoLibrarySourceSuffixes;
 
+    @Option(
+        name = "experimental_java_proto_add_allowed_public_imports",
+        defaultValue = "false",
+        documentationCategory = OptionDocumentationCategory.INPUT_STRICTNESS,
+        effectTags = {OptionEffectTag.AFFECTS_OUTPUTS, OptionEffectTag.LOADING_AND_ANALYSIS},
+        metadataTags = {OptionMetadataTag.EXPERIMENTAL},
+        help = "If true, add --allowed_public_imports to the java compile actions.")
+    public boolean experimentalJavaProtoAddAllowedPublicImports;
+
     @Override
     public FragmentOptions getHost() {
       Options host = (Options) super.getHost();
@@ -160,6 +169,8 @@ public class ProtoConfiguration extends Fragment implements ProtoConfigurationAp
       host.strictProtoDeps = strictProtoDeps;
       host.ccProtoLibraryHeaderSuffixes = ccProtoLibraryHeaderSuffixes;
       host.ccProtoLibrarySourceSuffixes = ccProtoLibrarySourceSuffixes;
+      host.experimentalJavaProtoAddAllowedPublicImports =
+          experimentalJavaProtoAddAllowedPublicImports;
       return host;
     }
   }
@@ -242,4 +253,8 @@ public class ProtoConfiguration extends Fragment implements ProtoConfigurationAp
   public List<String> ccProtoLibrarySourceSuffixes() {
     return ccProtoLibrarySourceSuffixes;
   }
+
+  public boolean strictPublicImports() {
+    return options.experimentalJavaProtoAddAllowedPublicImports;
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/proto/SupportData.java b/src/main/java/com/google/devtools/build/lib/rules/proto/SupportData.java
index b3644d4c17..35c0cee485 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/proto/SupportData.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/proto/SupportData.java
@@ -22,6 +22,7 @@ import com.google.devtools.build.lib.analysis.TransitiveInfoCollection;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
+import javax.annotation.Nullable;
 
 /** A helper class for the *Support classes containing some data from ProtoLibrary. */
 @AutoCodec
@@ -37,7 +38,9 @@ public abstract class SupportData {
       NestedSet<String> transitiveProtoPathFlags,
       String protoSourceRoot,
       NestedSet<String> directProtoSourceRoots,
-      boolean hasProtoSources) {
+      boolean hasProtoSources,
+      @Nullable NestedSet<Artifact> protosInExports,
+      @Nullable NestedSet<String> exportedProtoSourceRoots) {
     return new AutoValue_SupportData(
         nonWeakDepsPredicate,
         directProtoSources,
@@ -46,7 +49,9 @@ public abstract class SupportData {
         transitiveProtoPathFlags,
         protoSourceRoot,
         directProtoSourceRoots,
-        hasProtoSources);
+        hasProtoSources,
+        protosInExports,
+        exportedProtoSourceRoots);
   }
 
   public abstract Predicate<TransitiveInfoCollection> getNonWeakDepsPredicate();
@@ -76,5 +81,14 @@ public abstract class SupportData {
 
   public abstract boolean hasProtoSources();
 
+  /** .proto files in the exported dependencies of this proto_library. */
+  public abstract @Nullable NestedSet<Artifact> getProtosInExports();
+
+  /**
+   * The {@code proto_source_root}'s collected from the current library and the exported
+   * dependencies.
+   */
+  public abstract @Nullable NestedSet<String> getExportedProtoSourceRoots();
+
   SupportData() {}
 }
diff --git a/src/test/java/com/google/devtools/build/lib/rules/proto/ProtoCompileActionBuilderTest.java b/src/test/java/com/google/devtools/build/lib/rules/proto/ProtoCompileActionBuilderTest.java
index 2044f279ad..e992960a72 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/proto/ProtoCompileActionBuilderTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/proto/ProtoCompileActionBuilderTest.java
@@ -55,7 +55,7 @@ public class ProtoCompileActionBuilderTest {
   public void commandLine_basic() throws Exception {
     FilesToRunProvider plugin =
         new FilesToRunProvider(
-            NestedSetBuilder.<Artifact>emptySet(Order.STABLE_ORDER),
+            NestedSetBuilder.emptySet(Order.STABLE_ORDER),
             null /* runfilesSupport */,
             artifact("//:dont-care", "protoc-gen-javalite.exe"));
 
@@ -64,28 +64,30 @@ public class ProtoCompileActionBuilderTest {
             "--java_out=param1,param2:$(OUT)",
             /* pluginExecutable= */ null,
             /* runtime= */ mock(TransitiveInfoCollection.class),
-            /* blacklistedProtos= */ NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER));
+            /* blacklistedProtos= */ NestedSetBuilder.emptySet(STABLE_ORDER));
 
     ProtoLangToolchainProvider toolchainWithPlugin =
         ProtoLangToolchainProvider.create(
             "--$(PLUGIN_OUT)=param3,param4:$(OUT)",
             plugin,
             /* runtime= */ mock(TransitiveInfoCollection.class),
-            /* blacklistedProtos= */ NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER));
+            /* blacklistedProtos= */ NestedSetBuilder.emptySet(STABLE_ORDER));
 
     SupportData supportData =
         SupportData.create(
-            Predicates.<TransitiveInfoCollection>alwaysFalse(),
+            Predicates.alwaysFalse(),
             ImmutableList.of(artifact("//:dont-care", "source_file.proto")),
-            /* protosInDirectDeps= */ NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER),
+            /* protosInDirectDeps= */ NestedSetBuilder.emptySet(STABLE_ORDER),
             NestedSetBuilder.create(
                 STABLE_ORDER,
                 artifact("//:dont-care", "import1.proto"),
                 artifact("//:dont-care", "import2.proto")),
-            /*transitiveProtoPathFlags=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
-            /*protoSourceRoot=*/ "",
-            /*directProtoSourceRoots=*/ NestedSetBuilder.<String>stableOrder().build(),
-            /* hasProtoSources= */ true);
+            /* transitiveProtoPathFlags= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* protoSourceRoot= */ "",
+            /* directProtoSourceRoots= */ NestedSetBuilder.<String>stableOrder().build(),
+            /* hasProtoSources= */ true,
+            /* protosInExports= */ null,
+            /* exportedProtoSourceRoots= */ null);
 
     CustomCommandLine cmdLine =
         createCommandLineFromToolchains(
@@ -95,12 +97,14 @@ public class ProtoCompileActionBuilderTest {
                 new ToolchainInvocation("pluginName", toolchainWithPlugin, "bar.srcjar")),
             supportData.getDirectProtoSources(),
             supportData.getTransitiveImports(),
-            /*transitiveProtoPathFlags=*/ NestedSetBuilder.<String>stableOrder().build(),
-            /*directProtoSourceRoots=*/ NestedSetBuilder.<String>stableOrder().build(),
-            null /* protosInDirectDeps */,
+            /* transitiveProtoPathFlags= */ NestedSetBuilder.<String>stableOrder().build(),
+            /* directProtoSourceRoots= */ NestedSetBuilder.<String>stableOrder().build(),
+            /* exportedProtoSourceRoots= */ null,
+            /* protosInDirectDeps= */ null,
+            /* protosInExports= */ null,
             Label.parseAbsoluteUnchecked("//foo:bar"),
-            true /* allowServices */,
-            ImmutableList.<String>of() /* protocOpts */);
+            /* allowServices= */ true,
+            /* protocOpts= */ ImmutableList.of());
 
     assertThat(cmdLine.arguments())
         .containsExactly(
@@ -118,26 +122,30 @@ public class ProtoCompileActionBuilderTest {
     // Verify that the command line contains the correct path to a generated protocol buffers.
     SupportData supportData =
         SupportData.create(
-            Predicates.<TransitiveInfoCollection>alwaysFalse(),
+            Predicates.alwaysFalse(),
             ImmutableList.of(derivedArtifact("//:dont-care", "source_file.proto")),
-            /* protosInDirectDeps= */ NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER),
-            /* transitiveImports= */ NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER),
-            /*transitiveProtoPathFlags=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
-            /*protoSourceRoot=*/ "",
-            /*directProtoSourceRoots=*/ NestedSetBuilder.<String>stableOrder().build(),
-            /* hasProtoSources= */ true);
+            /* protosInDirectDeps= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* transitiveImports= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* transitiveProtoPathFlags= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* protoSourceRoot= */ "",
+            /* directProtoSourceRoots= */ NestedSetBuilder.<String>stableOrder().build(),
+            /* hasProtoSources= */ true,
+            /* protosInExports= */ null,
+            /* exportedProtoSourceRoots= */ null);
 
     CustomCommandLine cmdLine =
         createCommandLineFromToolchains(
-            ImmutableList.<ToolchainInvocation>of() /* toolchainInvocations */,
+            /* toolchainInvocations= */ ImmutableList.of(),
             supportData.getDirectProtoSources(),
             supportData.getTransitiveImports(),
-            /*transitiveProtoPathFlags=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
-            /*directProtoSourceRoots=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
-            null /* protosInDirectDeps */,
+            /* transitiveProtoPathFlags= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* directProtoSourceRoots= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* exportedProtoSourceRoots= */ null,
+            /* protosInDirectDeps= */ null,
+            /* protosInExports= */ null,
             Label.parseAbsoluteUnchecked("//foo:bar"),
-            true /* allowServices */,
-            ImmutableList.<String>of() /* protocOpts */);
+            /* allowServices= */ true,
+            /* protocOpts= */ ImmutableList.of());
 
     assertThat(cmdLine.arguments()).containsExactly("out/source_file.proto");
   }
@@ -149,33 +157,37 @@ public class ProtoCompileActionBuilderTest {
             "--java_out=param1,param2:$(OUT)",
             /* pluginExecutable= */ null,
             /* runtime= */ mock(TransitiveInfoCollection.class),
-            /* blacklistedProtos= */ NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER));
+            /* blacklistedProtos= */ NestedSetBuilder.emptySet(STABLE_ORDER));
 
     SupportData supportData =
         SupportData.create(
-            Predicates.<TransitiveInfoCollection>alwaysFalse(),
+            Predicates.alwaysFalse(),
             ImmutableList.of(artifact("//:dont-care", "source_file.proto")),
             NestedSetBuilder.create(STABLE_ORDER, artifact("//:dont-care", "import1.proto")),
             NestedSetBuilder.create(
                 STABLE_ORDER,
                 artifact("//:dont-care", "import1.proto"),
                 artifact("//:dont-care", "import2.proto")),
-            /*transitiveProtoPathFlags=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
-            /*protoSourceRoot=*/ "",
-            /*directProtoSourceRoots=*/ NestedSetBuilder.<String>stableOrder().build(),
-            /* hasProtoSources= */ true);
+            /* transitiveProtoPathFlags= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* protoSourceRoot= */ "",
+            /* directProtoSourceRoots= */ NestedSetBuilder.<String>stableOrder().build(),
+            /* hasProtoSources= */ true,
+            /* protosInExports= */ null,
+            /* exportedProtoSourceRoots= */ null);
 
     CustomCommandLine cmdLine =
         createCommandLineFromToolchains(
             ImmutableList.of(new ToolchainInvocation("dontcare", toolchain, "foo.srcjar")),
             supportData.getDirectProtoSources(),
             supportData.getTransitiveImports(),
-            /*transitiveProtoPathFlags=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
-            /*directProtoSourceRoots=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
+            /* transitiveProtoPathFlags= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* directProtoSourceRoots= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* exportedProtoSourceRoots= */ null,
             supportData.getProtosInDirectDeps(),
+            /* protosInExports= */ null,
             Label.parseAbsoluteUnchecked("//foo:bar"),
-            true /* allowServices */,
-            ImmutableList.<String>of() /* protocOpts */);
+            /* allowServices= */ true,
+            /* protocOpts= */ ImmutableList.of());
 
     assertThat(cmdLine.arguments())
         .containsExactly(
@@ -193,26 +205,30 @@ public class ProtoCompileActionBuilderTest {
   public void otherParameters() throws Exception {
     SupportData supportData =
         SupportData.create(
-            Predicates.<TransitiveInfoCollection>alwaysFalse(),
-            ImmutableList.<Artifact>of(),
-            /* protosInDirectDeps= */ NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER),
-            NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER),
-            /*transitiveProtoPathFlags=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
-            /*protoSourceRoot=*/ "",
-            /*directProtoSourceRoots=*/ NestedSetBuilder.<String>stableOrder().build(),
-            /* hasProtoSources= */ true);
+            Predicates.alwaysFalse(),
+            ImmutableList.of(),
+            /* protosInDirectDeps= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* transitiveProtoPathFlags= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* protoSourceRoot= */ "",
+            /* directProtoSourceRoots= */ NestedSetBuilder.<String>stableOrder().build(),
+            /* hasProtoSources= */ true,
+            /* protosInExports= */ null,
+            /* exportedProtoSourceRoots= */ null);
 
     CustomCommandLine cmdLine =
         createCommandLineFromToolchains(
-            ImmutableList.<ToolchainInvocation>of(),
+            ImmutableList.of(),
             supportData.getDirectProtoSources(),
             supportData.getTransitiveImports(),
-            /*transitiveProtoPathFlags=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
-            /*directProtoSourceRoots=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
+            /* transitiveProtoPathFlags= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* directProtoSourceRoots= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* exportedProtoSourceRoots= */ null,
             supportData.getProtosInDirectDeps(),
+            /* protosInExports= */ null,
             Label.parseAbsoluteUnchecked("//foo:bar"),
-            false /* allowServices */,
-            ImmutableList.of("--foo", "--bar") /* protocOpts */);
+            /* allowServices= */ false,
+            /* protocOpts= */ ImmutableList.of("--foo", "--bar"));
 
     assertThat(cmdLine.arguments()).containsAllOf("--disallow_services", "--foo", "--bar");
   }
@@ -236,30 +252,34 @@ public class ProtoCompileActionBuilderTest {
             "--java_out=param1,param2:$(OUT)",
             /* pluginExecutable= */ null,
             /* runtime= */ mock(TransitiveInfoCollection.class),
-            /* blacklistedProtos= */ NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER));
+            /* blacklistedProtos= */ NestedSetBuilder.emptySet(STABLE_ORDER));
 
     SupportData supportData =
         SupportData.create(
-            Predicates.<TransitiveInfoCollection>alwaysFalse(),
-            ImmutableList.<Artifact>of(),
-            /* protosInDirectDeps= */ NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER),
-            NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER),
-            /*transitiveProtoPathFlags=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
-            /*protoSourceRoot=*/ "",
-            /*directProtoSourceRoots=*/ NestedSetBuilder.<String>stableOrder().build(),
-            /* hasProtoSources= */ true);
+            Predicates.alwaysFalse(),
+            ImmutableList.of(),
+            /* protosInDirectDeps= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* transitiveProtoPathFlags= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* protoSourceRoot= */ "",
+            /* directProtoSourceRoots= */ NestedSetBuilder.<String>stableOrder().build(),
+            /* hasProtoSources= */ true,
+            /* protosInExports= */ null,
+            /* exportedProtoSourceRoots= */ null);
 
     CustomCommandLine cmdLine =
         createCommandLineFromToolchains(
             ImmutableList.of(new ToolchainInvocation("pluginName", toolchain, outReplacement)),
             supportData.getDirectProtoSources(),
             supportData.getTransitiveImports(),
-            /*transitiveProtoPathFlags=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
-            /*directProtoSourceRoots=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
+            /* transitiveProtoPathFlags= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* directProtoSourceRoots= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* exportedProtoSourceRoots= */ null,
             supportData.getProtosInDirectDeps(),
+            /* protosInExports= */ null,
             Label.parseAbsoluteUnchecked("//foo:bar"),
-            true /* allowServices */,
-            ImmutableList.<String>of() /* protocOpts */);
+            /* allowServices= */ true,
+            /* protocOpts= */ ImmutableList.of());
 
     assertThat(hasBeenCalled[0]).isFalse();
     cmdLine.arguments();
@@ -274,28 +294,30 @@ public class ProtoCompileActionBuilderTest {
   public void exceptionIfSameName() throws Exception {
     SupportData supportData =
         SupportData.create(
-            Predicates.<TransitiveInfoCollection>alwaysFalse(),
-            ImmutableList.<Artifact>of(),
-            /* protosInDirectDeps= */ NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER),
-            NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER),
-            /*transitiveProtoPathFlags=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
-            /*protoSourceRoot=*/ "",
-            /*directProtoSourceRoots=*/ NestedSetBuilder.<String>stableOrder().build(),
-            /* hasProtoSources= */ true);
+            Predicates.alwaysFalse(),
+            ImmutableList.of(),
+            /* protosInDirectDeps= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* transitiveProtoPathFlags= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+            /* protoSourceRoot= */ "",
+            /* directProtoSourceRoots= */ NestedSetBuilder.<String>stableOrder().build(),
+            /* hasProtoSources= */ true,
+            /* protosInExports= */ null,
+            /* exportedProtoSourceRoots= */ null);
 
     ProtoLangToolchainProvider toolchain1 =
         ProtoLangToolchainProvider.create(
             "dontcare",
             /* pluginExecutable= */ null,
             /* runtime= */ mock(TransitiveInfoCollection.class),
-            /* blacklistedProtos= */ NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER));
+            /* blacklistedProtos= */ NestedSetBuilder.emptySet(STABLE_ORDER));
 
     ProtoLangToolchainProvider toolchain2 =
         ProtoLangToolchainProvider.create(
             "dontcare",
             /* pluginExecutable= */ null,
             /* runtime= */ mock(TransitiveInfoCollection.class),
-            /* blacklistedProtos= */ NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER));
+            /* blacklistedProtos= */ NestedSetBuilder.emptySet(STABLE_ORDER));
 
     try {
       createCommandLineFromToolchains(
@@ -304,12 +326,14 @@ public class ProtoCompileActionBuilderTest {
               new ToolchainInvocation("pluginName", toolchain2, "outReplacement")),
           supportData.getDirectProtoSources(),
           supportData.getTransitiveImports(),
-          /*transitiveProtoPathFlags=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
-          /*directProtoSourceRoots=*/ NestedSetBuilder.<String>emptySet(STABLE_ORDER),
+          /* transitiveProtoPathFlags= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+          /* directProtoSourceRoots= */ NestedSetBuilder.emptySet(STABLE_ORDER),
+          /* exportedProtoSourceRoots= */ null,
           supportData.getProtosInDirectDeps(),
+          /* protosInExports= */ null,
           Label.parseAbsoluteUnchecked("//foo:bar"),
-          true /* allowServices */,
-          ImmutableList.<String>of() /* protocOpts */);
+          /* allowServices= */ true,
+          /* protocOpts= */ ImmutableList.of());
       fail("Expected an exception");
     } catch (IllegalStateException e) {
       assertThat(e)