Late-bound split attribute configs weren't being properly propagated to deps with

dynamic configs.

The old code incorrectly applied a no-op instead of hard-setting a specific config.

Testing: This is a prereq piece for the main change adding dynamic split transitions. Once
we have that change, standard Bazel tests over implemented late-bound split attributes 
(e.g. AppleBinaryRule: ":cc_toolchain") will provide proper coverage.  There's no easy way
to test this directly since the affected code won't really work until the dynamic split change is in.

--
MOS_MIGRATED_REVID=129278253

2 files changed, 16 insertions, 4 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/analysis/DependencyResolver.java b/src/main/java/com/google/devtools/build/lib/analysis/DependencyResolver.java
index ec52681412..66360f4828 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/DependencyResolver.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/DependencyResolver.java
@@ -616,11 +616,23 @@ public abstract class DependencyResolver {
         return; // Skip this round: this is either a loading error or unevaluated Skyframe dep.
       }
       BuildConfiguration.TransitionApplier transitionApplier = config.getTransitionApplier();
+      boolean applyNullTransition = false;
       if (BuildConfiguration.usesNullConfiguration(toTarget)) {
         transitionApplier.applyTransition(Attribute.ConfigurationTransition.NULL);
+        applyNullTransition = true;
       }
-      Dependency dep = Iterables.getOnlyElement(transitionApplier.getDependencies(depLabel,
-          requiredAspects(aspect, attribute, toTarget, rule)));
+
+      ImmutableSet<AspectDescriptor> aspects = requiredAspects(aspect, attribute, toTarget, rule);
+      Dependency dep;
+      if (config.useDynamicConfigurations() && !applyNullTransition) {
+        // Since we feed a pre-prepared configuration directly to the dep, it won't get trimmed to
+        // the dep's fragments.
+        // TODO(gregce): properly trim this configuration, too.
+        dep = Dependency.withConfigurationAndAspects(depLabel, config, aspects);
+      } else {
+        dep = Iterables.getOnlyElement(transitionApplier.getDependencies(depLabel, aspects));
+      }
+
       outgoingEdges.put(attribute, dep);
     }
   }
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ConfiguredTargetFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ConfiguredTargetFunction.java
index 22955612a1..b9f839c977 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ConfiguredTargetFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ConfiguredTargetFunction.java
@@ -453,8 +453,8 @@ final class ConfiguredTargetFunction implements SkyFunction {
           new AttributeAndLabel(depsEntry.getKey(), dep.getLabel());
 
       if (dep.hasStaticConfiguration()) {
-        // Certain targets (like output files) trivially pass their configurations to their deps.
-        // So no need to transform them in any way.
+        // Certain targets (like output files and late-bound splits) trivially pass their
+        // configurations to their deps. So no need to transform them in any way.
         putOnlyEntry(trimmedDeps, attributeAndLabel, dep);
         continue;
       } else if (dep.getTransition() == Attribute.ConfigurationTransition.NULL) {