1 files changed, 22 insertions, 2 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/actions/AbstractAction.java b/src/main/java/com/google/devtools/build/lib/actions/AbstractAction.java
index a8b460e823..7919529da0 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/AbstractAction.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/AbstractAction.java
@@ -174,8 +174,7 @@ public abstract class AbstractAction implements Action, SkylarkValue {
   }
 
   @Override
-  public synchronized Iterable<Artifact> discoverInputs(
-      ActionExecutionContext actionExecutionContext)
+  public Iterable<Artifact> discoverInputs(ActionExecutionContext actionExecutionContext)
       throws ActionExecutionException, InterruptedException {
     throw new IllegalStateException("discoverInputs cannot be called for " + this.prettyPrint()
         + " since it does not discover inputs");
@@ -496,6 +495,27 @@ public abstract class AbstractAction implements Action, SkylarkValue {
     return ImmutableSet.of();
   }
 
+  /**
+   * Returns input files that need to be present to allow extra_action rules to shadow this action
+   * correctly when run remotely. This is at least the normal inputs of the action, but may include
+   * other files as well. For example C(++) compilation may perform include file header scanning.
+   * This needs to be mirrored by the extra_action rule. Called by
+   * {@link com.google.devtools.build.lib.rules.extra.ExtraAction} at execution time.
+   *
+   * <p>As this method is called from the ExtraAction, make sure it is ok to call
+   * this method from a different thread than the one this action is executed on.
+   *
+   * @param actionExecutionContext Services in the scope of the action, like the Out/Err streams.
+   * @throws ActionExecutionException only when code called from this method
+   *     throws that exception.
+   * @throws InterruptedException if interrupted
+   */
+  public Iterable<Artifact> getInputFilesForExtraAction(
+      ActionExecutionContext actionExecutionContext)
+      throws ActionExecutionException, InterruptedException {
+    return getInputs();
+  }
+
   @SkylarkCallable(
       name = "inputs",
       doc = "A set of the input files of this action.",