Move the descriptorset output to the ProtoSourcesProvider and expose it to skylark.

This does mean that the type name 'ProtoSourcesProvider' is a little inaccurate, since descriptorSet() is an output.  Alternatively we could expose the DescriptorSetProvider to skylark.


RELNOTES: expose proto_library descriptor set to skylark via <dep>.proto.descriptor_set

--
PiperOrigin-RevId: 142680666
MOS_MIGRATED_REVID=142680666

3 files changed, 35 insertions, 48 deletions

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 3557c5f95c..c524829ce9 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
@@ -46,11 +46,6 @@ public class BazelProtoLibrary implements RuleConfiguredTargetFactory {
     NestedSet<Artifact> transitiveImports =
         ProtoCommon.collectTransitiveImports(ruleContext, protoSources);
 
-    // TODO(bazel-team): this second constructor argument is superfluous and should be removed.
-    ProtoSourcesProvider sourcesProvider =
-        ProtoSourcesProvider.create(
-            transitiveImports, transitiveImports, protoSources, checkDepsProtoSources);
-
     NestedSet<Artifact> protosInDirectDeps =
         areDepsStrict(ruleContext) ? ProtoCommon.computeProtosInDirectDeps(ruleContext) : null;
 
@@ -67,10 +62,11 @@ public class BazelProtoLibrary implements RuleConfiguredTargetFactory {
 
     RuleConfiguredTargetBuilder result = new RuleConfiguredTargetBuilder(ruleContext);
 
+    Artifact descriptorSetOutput = null;
     if (checkDepsProtoSources.isEmpty() || !outputDescriptorSetFlagEnabled(ruleContext)) {
       result.setFilesToBuild(NestedSetBuilder.<Artifact>create(STABLE_ORDER));
     } else {
-      Artifact descriptorSetOutput =
+      descriptorSetOutput =
           ruleContext.getGenfilesArtifact(
               ruleContext.getLabel().getName() + "-descriptor-set.proto.bin");
       ProtoCompileActionBuilder.writeDescriptorSet(
@@ -85,9 +81,17 @@ public class BazelProtoLibrary implements RuleConfiguredTargetFactory {
       dataRunfiles.addArtifact(descriptorSetOutput);
 
       result.setFilesToBuild(NestedSetBuilder.create(STABLE_ORDER, descriptorSetOutput));
-      result.addProvider(DescriptorSetProvider.create(descriptorSetOutput));
     }
 
+    // TODO(bazel-team): this second constructor argument is superfluous and should be removed.
+    ProtoSourcesProvider sourcesProvider =
+        ProtoSourcesProvider.create(
+            transitiveImports,
+            transitiveImports,
+            protoSources,
+            checkDepsProtoSources,
+            descriptorSetOutput);
+
     return result
         .addProvider(RunfilesProvider.withData(Runfiles.EMPTY, dataRunfiles.build()))
         .addProvider(ProtoSourcesProvider.class, sourcesProvider)
diff --git a/src/main/java/com/google/devtools/build/lib/rules/proto/DescriptorSetProvider.java b/src/main/java/com/google/devtools/build/lib/rules/proto/DescriptorSetProvider.java
deleted file mode 100644
index c1d323b3b2..0000000000
--- a/src/main/java/com/google/devtools/build/lib/rules/proto/DescriptorSetProvider.java
+++ /dev/null
@@ -1,39 +0,0 @@
-// Copyright 2016 The Bazel Authors. All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//    http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package com.google.devtools.build.lib.rules.proto;
-
-import com.google.auto.value.AutoValue;
-import com.google.devtools.build.lib.actions.Artifact;
-import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
-
-/**
- * A provider that exposes a compiled descriptor set from a proto_library.
- *
- * <p>Produced by passing --descriptor_set_out to the proto-compiler. See
- * https://developers.google.com/protocol-buffers/docs/techniques#self-description
- */
-@AutoValue
-public abstract class DescriptorSetProvider implements TransitiveInfoProvider {
-
-  /**
-   * Be careful while using this artifact - it is the parsing of the transitive set of .proto files.
-   * It's possible to cause a O(n^2) behavior, where n is the length of a proto chain-graph.
-   */
-  public abstract Artifact descriptorSet();
-
-  public static DescriptorSetProvider create(Artifact descriptorSet) {
-    return new AutoValue_DescriptorSetProvider(descriptorSet);
-  }
-}
diff --git a/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoSourcesProvider.java b/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoSourcesProvider.java
index d8624c40e1..5220e4c47e 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoSourcesProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/proto/ProtoSourcesProvider.java
@@ -22,7 +22,9 @@ import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+import javax.annotation.Nullable;
 
+// TODO(carmi): Rename the class to ProtoInfoProvider.
 /**
  * Configured target classes that implement this class can contribute .proto files to the
  * compilation of proto_library rules.
@@ -38,9 +40,14 @@ public abstract class ProtoSourcesProvider implements TransitiveInfoProvider {
       NestedSet<Artifact> transitiveImports,
       NestedSet<Artifact> transitiveProtoSources,
       ImmutableList<Artifact> protoSources,
-      ImmutableList<Artifact> checkDepsProtoSources) {
+      ImmutableList<Artifact> checkDepsProtoSources,
+      @Nullable Artifact descriptorSet) {
     return new AutoValue_ProtoSourcesProvider(
-        transitiveImports, transitiveProtoSources, protoSources, checkDepsProtoSources);
+        transitiveImports,
+        transitiveProtoSources,
+        protoSources,
+        checkDepsProtoSources,
+        descriptorSet);
   }
 
   /**
@@ -95,5 +102,20 @@ public abstract class ProtoSourcesProvider implements TransitiveInfoProvider {
   )
   public abstract ImmutableList<Artifact> getCheckDepsProtoSources();
 
+  /**
+   * Be careful while using this artifact - it is the parsing of the transitive set of .proto files.
+   * It's possible to cause a O(n^2) behavior, where n is the length of a proto chain-graph.
+   */
+  @SkylarkCallable(
+    name = "descriptor_set",
+    doc =
+        "The FileDescriptorSet of all transitive sources. Returns None if "
+            + "--output_descriptor_set isn't enabled or if there are no sources",
+    structField = true,
+    allowReturnNones = true
+  )
+  @Nullable
+  public abstract Artifact descriptorSet();
+
   ProtoSourcesProvider() {}
 }