Fixes bug where using portable_proto_filters along with proto files i…

…n deps (as oposed to proto_library targets) would result in a crash.

--
PiperOrigin-RevId: 145283582
MOS_MIGRATED_REVID=145283582

src/main/java/com/google/devtools/build/lib/rules/objc/ProtoAttributes.java

@@ -49,6 +49,11 @@ final class ProtoAttributes {
   private static final ImmutableSet<String> UPPERCASE_SEGMENTS =
       ImmutableSet.of("url", "http", "https");
 
+  @VisibleForTesting
+  static final String FILES_NOT_ALLOWED_ERROR =
+      "Using files and filegroups in objc_proto_library with portable_proto_filters is not "
+          + "allowed. Please wrap the files inside a proto_library target.";
+
   @VisibleForTesting
   static final String FILES_DEPRECATED_WARNING =
       "Using files and filegroups in objc_proto_library is deprecated";
@@ -104,13 +109,13 @@ public void validate() throws RuleErrorException {
     PrerequisiteArtifacts prerequisiteArtifacts =
         ruleContext.getPrerequisiteArtifacts("deps", Mode.TARGET);
     ImmutableList<Artifact> protos = prerequisiteArtifacts.filter(FileType.of(".proto")).list();
-    if (!protos.isEmpty()) {
-      ruleContext.attributeWarning("deps", FILES_DEPRECATED_WARNING);
-    }
 
     if (ruleContext
         .attributes()
         .isAttributeValueExplicitlySpecified(ObjcProtoLibraryRule.PORTABLE_PROTO_FILTERS_ATTR)) {
+      if (!protos.isEmpty()) {
+        ruleContext.throwWithAttributeError("deps", FILES_NOT_ALLOWED_ERROR);
+      }
       if (getProtoFiles().isEmpty() && !hasObjcProtoLibraryDependencies()) {
         ruleContext.throwWithRuleError(NO_PROTOS_ERROR);
       }
@@ -129,6 +134,9 @@ public void validate() throws RuleErrorException {
       }
 
     } else {
+      if (!protos.isEmpty()) {
+        ruleContext.attributeWarning("deps", FILES_DEPRECATED_WARNING);
+      }
       if (getProtoFiles().isEmpty()) {
         ruleContext.throwWithRuleError(NO_PROTOS_ERROR);
       }