1 files changed, 7 insertions, 1 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/packages/AggregatingAttributeMapper.java b/src/main/java/com/google/devtools/build/lib/packages/AggregatingAttributeMapper.java
index 9de8ce4914..f57b83b79e 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/AggregatingAttributeMapper.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/AggregatingAttributeMapper.java
@@ -373,7 +373,13 @@ public class AggregatingAttributeMapper extends AbstractAttributeMapper {
     // have no impact on the dependency structure.
 
     if (selectors.isEmpty()) {
-      valuesBuilder.add(Preconditions.checkNotNull(currentValueSoFar));
+      if (currentValueSoFar != null) {
+        // Null values arise when a None is used as the value of a Selector for a type without a
+        // default value.
+        // TODO(gregce): visitAttribute should probably convey that an unset attribute is possible.
+        // Therefore we need to actually handle null values here.
+        valuesBuilder.add(currentValueSoFar);
+      }
     } else {
       Selector<T> firstSelector = selectors.get(0);
       List<Selector<T>> remainingSelectors = selectors.subList(1, selectors.size());