Let select() "unset" values via: select({"//some:condition: None }).

This not only uses the default value when applicable, but also causes
ConfiguredAttributeMapper.isAttributeValueExplicitlySpecified to
return false.

Note the default value can come from two places: from the rule
definition if specified, otherwise from the type default.

RELNOTES[NEW]: select({"//some:condition: None }) is now possible (this "unsets" the attribute).

--
MOS_MIGRATED_REVID=121029815

1 files changed, 5 insertions, 2 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 96a20fb964..90d4656ca2 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
@@ -128,8 +128,11 @@ public class AggregatingAttributeMapper extends AbstractAttributeMapper {
             observer.acceptLabelAttribute(
                 getLabel().resolveRepositoryRelative(selectorEntry.getKey()), attribute);
           }
-          for (Label value : extractLabels(type, selectorEntry.getValue())) {
-            observer.acceptLabelAttribute(getLabel().resolveRepositoryRelative(value), attribute);
+          Object value = selector.isValueSet(selectorEntry.getKey())
+              ? selectorEntry.getValue()
+              : attribute.getDefaultValue(null);
+          for (Label label : extractLabels(type, value)) {
+            observer.acceptLabelAttribute(getLabel().resolveRepositoryRelative(label), attribute);
           }
         }
       }