Python provider is now available in Skylark

Using mandatoryProvidersList to validate python rules' dependency.
Added a SkylarkProvider named 'py' which is a SkylarkClassObject in Java and a
struct in Skylark. Native python rule and Skylark python rule should have this provider
so that they can depend on each other.

RELNOTES[NEW]: Native python rule can depend on skylark rule as long as skylark
rule provides 'py' provider.

--
MOS_MIGRATED_REVID=116241504

1 files changed, 70 insertions, 13 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/python/PyCommon.java b/src/main/java/com/google/devtools/build/lib/rules/python/PyCommon.java
index 9b6813fad5..eff1239649 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/python/PyCommon.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/python/PyCommon.java
@@ -15,6 +15,7 @@ package com.google.devtools.build.lib.rules.python;
 
 import com.google.common.base.Joiner;
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.actions.Action;
 import com.google.devtools.build.lib.actions.ActionOwner;
@@ -30,6 +31,7 @@ import com.google.devtools.build.lib.analysis.PseudoAction;
 import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
 import com.google.devtools.build.lib.analysis.RuleConfiguredTargetBuilder;
 import com.google.devtools.build.lib.analysis.RuleContext;
+import com.google.devtools.build.lib.analysis.SkylarkProviders;
 import com.google.devtools.build.lib.analysis.TransitiveInfoCollection;
 import com.google.devtools.build.lib.analysis.Util;
 import com.google.devtools.build.lib.analysis.actions.SpawnAction;
@@ -44,6 +46,11 @@ import com.google.devtools.build.lib.rules.cpp.CppFileTypes;
 import com.google.devtools.build.lib.rules.test.InstrumentedFilesCollector;
 import com.google.devtools.build.lib.rules.test.InstrumentedFilesCollector.LocalMetadataCollector;
 import com.google.devtools.build.lib.rules.test.InstrumentedFilesProvider;
+import com.google.devtools.build.lib.syntax.ClassObject.SkylarkClassObject;
+import com.google.devtools.build.lib.syntax.EvalException;
+import com.google.devtools.build.lib.syntax.EvalUtils;
+import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
+import com.google.devtools.build.lib.syntax.SkylarkType;
 import com.google.devtools.build.lib.syntax.Type;
 import com.google.devtools.build.lib.util.FileType;
 import com.google.devtools.build.lib.util.Preconditions;
@@ -61,6 +68,10 @@ import java.util.UUID;
  */
 public final class PyCommon {
 
+  public static final String PYTHON_SKYLARK_PROVIDER_NAME = "py";
+  public static final String TRANSITIVE_PYTHON_SRCS = "transitive_sources";
+  public static final String IS_USING_SHARED_LIBRARY = "uses_shared_libraries";
+
   private static final LocalMetadataCollector METADATA_COLLECTOR = new LocalMetadataCollector() {
     @Override
     public void collectMetadataArtifacts(Iterable<Artifact> artifacts,
@@ -125,13 +136,15 @@ public final class PyCommon {
 
   public void addCommonTransitiveInfoProviders(RuleConfiguredTargetBuilder builder,
       PythonSemantics semantics, NestedSet<Artifact> filesToBuild) {
-    PythonSourcesProvider sourcesProvider =
-        new PythonSourcesProvider(transitivePythonSources, usesSharedLibraries());
+
+    SkylarkClassObject sourcesProvider =
+        new SkylarkClassObject(ImmutableMap.<String, Object>of(
+            TRANSITIVE_PYTHON_SRCS, SkylarkNestedSet.of(Artifact.class, transitivePythonSources),
+            IS_USING_SHARED_LIBRARY, usesSharedLibraries()), "No such attribute '%s'");
     builder
         .add(InstrumentedFilesProvider.class, InstrumentedFilesCollector.collect(ruleContext,
             semantics.getCoverageInstrumentationSpec(), METADATA_COLLECTOR, filesToBuild))
-        .add(PythonSourcesProvider.class, sourcesProvider)
-        .addSkylarkTransitiveInfo(PythonSourcesProvider.SKYLARK_NAME, sourcesProvider)
+        .addSkylarkTransitiveInfo(PYTHON_SKYLARK_PROVIDER_NAME, sourcesProvider)
         // Python targets are not really compilable. The best we can do is make sure that all
         // generated source files are ready.
         .addOutputGroup(OutputGroupProvider.FILES_TO_COMPILE, transitivePythonSources)
@@ -260,12 +273,44 @@ public final class PyCommon {
     return ruleContext.getPrerequisites("deps", Mode.TARGET);
   }
 
+  private NestedSet<Artifact> getTransitivePythonSourcesFromSkylarkProvider(
+          TransitiveInfoCollection dep) {
+    SkylarkClassObject pythonSkylarkProvider = null;
+    SkylarkProviders skylarkProviders = dep.getProvider(SkylarkProviders.class);
+    try {
+      if (skylarkProviders != null) {
+        pythonSkylarkProvider = skylarkProviders.getValue(PYTHON_SKYLARK_PROVIDER_NAME,
+                SkylarkClassObject.class);
+      }
+
+      if (pythonSkylarkProvider != null) {
+        Object sourceFiles = pythonSkylarkProvider.getValue(TRANSITIVE_PYTHON_SRCS);
+        String errorType;
+        if (sourceFiles == null) {
+          errorType = "null";
+        } else {
+          errorType = EvalUtils.getDataTypeNameFromClass(sourceFiles.getClass());
+        }
+        String errorMsg = "Illegal Argument: attribute '%s' in provider '%s' is "
+                + "of unexpected type. Should be a set, but got a '%s'";
+        NestedSet<Artifact> pythonSourceFiles = SkylarkType.cast(
+                sourceFiles, SkylarkNestedSet.class, Artifact.class, null,
+                errorMsg, TRANSITIVE_PYTHON_SRCS, PYTHON_SKYLARK_PROVIDER_NAME, errorType)
+                .getSet(Artifact.class);
+        return pythonSourceFiles;
+      }
+    } catch (EvalException e) {
+      ruleContext.ruleError(e.getMessage());
+    }
+    return null;
+  }
+
   private void collectTransitivePythonSourcesFrom(
       Iterable<? extends TransitiveInfoCollection> deps, NestedSetBuilder<Artifact> builder) {
     for (TransitiveInfoCollection dep : deps) {
-      if (dep.getProvider(PythonSourcesProvider.class) != null) {
-        PythonSourcesProvider provider = dep.getProvider(PythonSourcesProvider.class);
-        builder.addTransitive(provider.getTransitivePythonSources());
+      NestedSet<Artifact> pythonSourceFiles = getTransitivePythonSourcesFromSkylarkProvider(dep);
+      if (pythonSourceFiles != null) {
+        builder.addTransitive(pythonSourceFiles);
       } else {
         // TODO(bazel-team): We also collect .py source files from deps (e.g. for proto_library
         // rules). Rules should implement PythonSourcesProvider instead.
@@ -381,9 +426,14 @@ public final class PyCommon {
   }
 
   public boolean usesSharedLibraries() {
-    return checkForSharedLibraries(Iterables.concat(
-        ruleContext.getPrerequisites("deps", Mode.TARGET),
-        ruleContext.getPrerequisites("data", Mode.DATA)));
+    try {
+      return checkForSharedLibraries(Iterables.concat(
+              ruleContext.getPrerequisites("deps", Mode.TARGET),
+              ruleContext.getPrerequisites("data", Mode.DATA)));
+    } catch (EvalException e) {
+      ruleContext.ruleError(e.getMessage());
+      return false;
+    }
   }
 
   protected static final ResourceSet PY_COMPILE_RESOURCE_SET =
@@ -453,11 +503,18 @@ public final class PyCommon {
   /**
    * Returns true if this target has an .so file in its transitive dependency closure.
    */
-  public static boolean checkForSharedLibraries(Iterable<TransitiveInfoCollection> deps) {
+  public static boolean checkForSharedLibraries(Iterable<TransitiveInfoCollection> deps)
+          throws EvalException{
     for (TransitiveInfoCollection dep : deps) {
-      PythonSourcesProvider provider = dep.getProvider(PythonSourcesProvider.class);
+      SkylarkProviders providers = dep.getProvider(SkylarkProviders.class);
+      SkylarkClassObject provider = null;
+      if (providers != null) {
+        provider = providers.getValue(PYTHON_SKYLARK_PROVIDER_NAME,
+                SkylarkClassObject.class);
+      }
       if (provider != null) {
-        if (provider.usesSharedLibraries()) {
+        Boolean isUsingSharedLibrary = provider.getValue(IS_USING_SHARED_LIBRARY, Boolean.class);
+        if (Boolean.TRUE.equals(isUsingSharedLibrary)) {
           return true;
         }
       } else if (FileType.contains(