1 files changed, 5 insertions, 8 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/rules/extra/ExtraAction.java b/src/main/java/com/google/devtools/build/lib/rules/extra/ExtraAction.java
index 866e45e20a..9f07c98285 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/extra/ExtraAction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/extra/ExtraAction.java
@@ -114,18 +114,15 @@ public final class ExtraAction extends SpawnAction {
 
   @Nullable
   @Override
-  public Iterable<Artifact> discoverInputs(ActionExecutionContext actionExecutionContext)
+  public synchronized Iterable<Artifact> discoverInputs(
+      ActionExecutionContext actionExecutionContext)
       throws ActionExecutionException, InterruptedException {
     Preconditions.checkState(discoversInputs(), this);
     // We need to update our inputs to take account of any additional
     // inputs the shadowed action may need to do its work.
-    if (shadowedAction.discoversInputs() && shadowedAction instanceof AbstractAction) {
-      Iterable<Artifact> additionalInputs =
-          ((AbstractAction) shadowedAction).getInputFilesForExtraAction(actionExecutionContext);
-      updateInputs(createInputs(additionalInputs, extraActionInputs, runfilesSupplier));
-      return ImmutableSet.copyOf(additionalInputs);
-    }
-    return null;
+    Iterable<Artifact> additionalInputs = shadowedAction.discoverInputs(actionExecutionContext);
+    updateInputs(createInputs(additionalInputs, extraActionInputs, runfilesSupplier));
+    return additionalInputs;
   }
 
   @Override