Replace Attribute.ConfigurationTransition with config.transitions.ConfigurationTransitionProxy.

The "proxy" part is to dissuade people from writing:

 void myfunc(ConfigurationTransition transition)

signatures casually.

Maybe that's actually a better name than "Transition". But I'd rather
rename Transition to ConfigurationTransition in its own change if we
want to do that.

PiperOrigin-RevId: 180285321

18 files changed, 77 insertions, 96 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/analysis/BaseRuleClasses.java b/src/main/java/com/google/devtools/build/lib/analysis/BaseRuleClasses.java
index 35ed29b55b..aec52e1233 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/BaseRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/BaseRuleClasses.java
@@ -14,7 +14,7 @@
 
 package com.google.devtools.build.lib.analysis;
 
-import static com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition.DATA;
+import static com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy.DATA;
 import static com.google.devtools.build.lib.packages.Attribute.attr;
 import static com.google.devtools.build.lib.packages.BuildType.DISTRIBUTIONS;
 import static com.google.devtools.build.lib.packages.BuildType.LABEL;
@@ -35,6 +35,7 @@ import com.google.devtools.build.lib.analysis.config.DynamicTransitionMapper;
 import com.google.devtools.build.lib.analysis.config.HostTransition;
 import com.google.devtools.build.lib.analysis.config.PatchTransition;
 import com.google.devtools.build.lib.analysis.config.RunUnder;
+import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy;
 import com.google.devtools.build.lib.analysis.config.transitions.Transition;
 import com.google.devtools.build.lib.analysis.constraints.EnvironmentRule;
 import com.google.devtools.build.lib.analysis.test.TestConfiguration;
@@ -393,7 +394,7 @@ public class BaseRuleClasses {
   }
 
   /**
-   * Declares the implementations for {@link Attribute.ConfigurationTransition} enums.
+   * Declares the implementations for {@link ConfigurationTransitionProxy} enums.
    *
    * <p>We can't put this in {@link Attribute} because that's in the {@code lib.packages} package,
    * which has no access to configuration classes.
@@ -402,9 +403,9 @@ public class BaseRuleClasses {
    */
   public static final ImmutableMap<Transition, Transition> DYNAMIC_TRANSITIONS_MAP =
       ImmutableMap.of(
-          Attribute.ConfigurationTransition.NONE, DynamicTransitionMapper.SELF,
-          Attribute.ConfigurationTransition.NULL, DynamicTransitionMapper.SELF
-          // Attribute.ConfigurationTransition.DATA is skipped because it's C++-specific.
+          ConfigurationTransitionProxy.NONE, DynamicTransitionMapper.SELF,
+          ConfigurationTransitionProxy.NULL, DynamicTransitionMapper.SELF
+          // ConfigurationTransitionProxy.DATA is skipped because it's C++-specific.
           // The C++ rule definitions handle its mapping.
       );
 }
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/BuildView.java b/src/main/java/com/google/devtools/build/lib/analysis/BuildView.java
index 222a250b4e..8beac6213c 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/BuildView.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/BuildView.java
@@ -45,6 +45,7 @@ import com.google.devtools.build.lib.analysis.config.ConfigMatchingProvider;
 import com.google.devtools.build.lib.analysis.config.ConfigurationResolver;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
 import com.google.devtools.build.lib.analysis.config.PatchTransition;
+import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy;
 import com.google.devtools.build.lib.analysis.config.transitions.Transition;
 import com.google.devtools.build.lib.analysis.constraints.TopLevelConstraintSemantics;
 import com.google.devtools.build.lib.analysis.test.CoverageReportActionFactory;
@@ -62,7 +63,6 @@ import com.google.devtools.build.lib.packages.AspectClass;
 import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.AspectParameters;
 import com.google.devtools.build.lib.packages.Attribute;
-import com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition;
 import com.google.devtools.build.lib.packages.BuildType;
 import com.google.devtools.build.lib.packages.NativeAspectClass;
 import com.google.devtools.build.lib.packages.NoSuchPackageException;
@@ -941,7 +941,7 @@ public class BuildView {
           Iterable<BuildOptions> buildOptions) {
         Preconditions.checkArgument(ct.getConfiguration().fragmentClasses().equals(fragments));
         Dependency asDep = Dependency.withTransitionAndAspects(ct.getLabel(),
-            Attribute.ConfigurationTransition.NONE, AspectCollection.EMPTY);
+            ConfigurationTransitionProxy.NONE, AspectCollection.EMPTY);
         ImmutableList.Builder<BuildConfiguration> builder = ImmutableList.builder();
         for (BuildOptions options : buildOptions) {
           builder.add(Iterables.getOnlyElement(
@@ -1020,27 +1020,27 @@ public class BuildView {
           .getTarget(handler, label)
           .getAssociatedRule();
     } catch (NoSuchPackageException | NoSuchTargetException e) {
-      return ConfigurationTransition.NONE;
+      return ConfigurationTransitionProxy.NONE;
     } catch (InterruptedException e) {
       Thread.currentThread().interrupt();
       throw new AssertionError("Configuration of " + label + " interrupted");
     }
     if (rule == null) {
-      return ConfigurationTransition.NONE;
+      return ConfigurationTransitionProxy.NONE;
     }
     RuleTransitionFactory factory = rule
         .getRuleClassObject()
         .getTransitionFactory();
     if (factory == null) {
-      return ConfigurationTransition.NONE;
+      return ConfigurationTransitionProxy.NONE;
     }
 
-    // dynamicTransitionMapper is only needed because of Attribute.ConfigurationTransition.DATA:
+    // dynamicTransitionMapper is only needed because of ConfigurationTransitionProxy.DATA:
     // this is C++-specific but non-C++ rules declare it. So they can't directly provide the
     // C++-specific patch transition that implements it.
     PatchTransition transition = (PatchTransition)
         ruleClassProvider.getDynamicTransitionMapper().map(factory.buildTransitionFor(rule));
-    return (transition == null) ? ConfigurationTransition.NONE : transition;
+    return (transition == null) ? ConfigurationTransitionProxy.NONE : transition;
   }
 
   /**
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 d268e7d2b3..87145f86c6 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
@@ -27,6 +27,7 @@ import com.google.devtools.build.lib.analysis.config.HostTransition;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
 import com.google.devtools.build.lib.analysis.config.PatchTransition;
 import com.google.devtools.build.lib.analysis.config.TransitionResolver;
+import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy;
 import com.google.devtools.build.lib.analysis.config.transitions.SplitTransition;
 import com.google.devtools.build.lib.analysis.config.transitions.Transition;
 import com.google.devtools.build.lib.cmdline.Label;
@@ -727,7 +728,7 @@ public abstract class DependencyResolver {
           ruleConfig, rule, attributeAndOwner.attribute, toTarget, attributeMap);
       outgoingEdges.put(
           attributeAndOwner.attribute,
-          transition == Attribute.ConfigurationTransition.NULL
+          transition == ConfigurationTransitionProxy.NULL
               ? Dependency.withNullConfiguration(depLabel)
               : Dependency.withTransitionAndAspects(depLabel, transition,
                     requiredAspects(attributeAndOwner, toTarget)));
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
index ce2569a1a6..25a0cf3381 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
@@ -47,6 +47,7 @@ import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.analysis.config.ConfigMatchingProvider;
 import com.google.devtools.build.lib.analysis.config.FragmentCollection;
 import com.google.devtools.build.lib.analysis.config.PatchTransition;
+import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy;
 import com.google.devtools.build.lib.analysis.config.transitions.SplitTransition;
 import com.google.devtools.build.lib.analysis.config.transitions.Transition;
 import com.google.devtools.build.lib.analysis.configuredtargets.RuleConfiguredTarget.Mode;
@@ -65,7 +66,6 @@ import com.google.devtools.build.lib.packages.AbstractRuleErrorConsumer;
 import com.google.devtools.build.lib.packages.Aspect;
 import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.Attribute;
-import com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition;
 import com.google.devtools.build.lib.packages.AttributeMap;
 import com.google.devtools.build.lib.packages.BuildType;
 import com.google.devtools.build.lib.packages.ConfigurationFragmentPolicy;
@@ -410,7 +410,7 @@ public final class RuleContext extends TargetContext
   @Nullable
   public <T extends Fragment> T getFragment(Class<T> fragment) {
     // NONE means target configuration.
-    return getFragment(fragment, ConfigurationTransition.NONE);
+    return getFragment(fragment, ConfigurationTransitionProxy.NONE);
   }
 
   @Nullable
@@ -441,7 +441,7 @@ public final class RuleContext extends TargetContext
 
   public <T extends Fragment> boolean isLegalFragment(Class<T> fragment) {
     // NONE means target configuration.
-    return isLegalFragment(fragment, ConfigurationTransition.NONE);
+    return isLegalFragment(fragment, ConfigurationTransitionProxy.NONE);
   }
 
   protected BuildConfiguration getConfiguration(Transition transition) {
@@ -1063,13 +1063,15 @@ public final class RuleContext extends TargetContext
             + " is not configured for the host configuration");
       }
     } else if (mode == Mode.TARGET) {
-      if (!(transition instanceof PatchTransition) && transition != ConfigurationTransition.NONE) {
+      if (!(transition instanceof PatchTransition)
+          && transition != ConfigurationTransitionProxy.NONE) {
         throw new IllegalStateException(getRule().getLocation() + ": "
             + getRuleClassNameForLogging() + " attribute " + attributeName
             + " is not configured for the target configuration");
       }
     } else if (mode == Mode.DATA) {
-      if (!(transition instanceof PatchTransition) && transition != ConfigurationTransition.DATA) {
+      if (!(transition instanceof PatchTransition)
+          && transition != ConfigurationTransitionProxy.DATA) {
         throw new IllegalStateException(getRule().getLocation() + ": "
             + getRuleClassNameForLogging() + " attribute " + attributeName
             + " is not configured for the data configuration");
@@ -1099,9 +1101,11 @@ public final class RuleContext extends TargetContext
     }
     if (attributeDefinition.getConfigurationTransition().isHostTransition()) {
       return Mode.HOST;
-    } else if (attributeDefinition.getConfigurationTransition() == ConfigurationTransition.NONE) {
+    } else if (attributeDefinition.getConfigurationTransition()
+        == ConfigurationTransitionProxy.NONE) {
       return Mode.TARGET;
-    } else if (attributeDefinition.getConfigurationTransition() == ConfigurationTransition.DATA) {
+    } else if (attributeDefinition.getConfigurationTransition()
+        == ConfigurationTransitionProxy.DATA) {
       return Mode.DATA;
     } else if (attributeDefinition.hasSplitConfigurationTransition()) {
       return Mode.SPLIT;
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/ComposingSplitTransition.java b/src/main/java/com/google/devtools/build/lib/analysis/config/ComposingSplitTransition.java
index 41cb44d3c0..e0f40f88ec 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/ComposingSplitTransition.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/ComposingSplitTransition.java
@@ -16,9 +16,9 @@ package com.google.devtools.build.lib.analysis.config;
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy;
 import com.google.devtools.build.lib.analysis.config.transitions.SplitTransition;
 import com.google.devtools.build.lib.analysis.config.transitions.Transition;
-import com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition;
 import java.util.List;
 
 /**
@@ -72,7 +72,7 @@ public class ComposingSplitTransition implements SplitTransition {
    */
   // TODO(gregce): move this somewhere more general. This isn't intrinsic to composed splits.
   static List<BuildOptions> apply(BuildOptions fromOptions, Transition transition) {
-    if (transition == ConfigurationTransition.NONE) {
+    if (transition == ConfigurationTransitionProxy.NONE) {
       return ImmutableList.<BuildOptions>of(fromOptions);
     } else if (transition instanceof PatchTransition) {
       return ImmutableList.<BuildOptions>of(((PatchTransition) transition).apply(fromOptions));
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/ConfigurationResolver.java b/src/main/java/com/google/devtools/build/lib/analysis/config/ConfigurationResolver.java
index d09219eaee..c10e265399 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/ConfigurationResolver.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/ConfigurationResolver.java
@@ -26,6 +26,7 @@ import com.google.common.collect.Multimap;
 import com.google.common.collect.Sets;
 import com.google.devtools.build.lib.analysis.Dependency;
 import com.google.devtools.build.lib.analysis.TargetAndConfiguration;
+import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy;
 import com.google.devtools.build.lib.analysis.config.transitions.SplitTransition;
 import com.google.devtools.build.lib.analysis.config.transitions.Transition;
 import com.google.devtools.build.lib.cmdline.Label;
@@ -184,7 +185,7 @@ public final class ConfigurationResolver {
       Transition transition = dep.getTransition();
 
       if (sameFragments) {
-        if (transition == Attribute.ConfigurationTransition.NONE) {
+        if (transition == ConfigurationTransitionProxy.NONE) {
           // The dep uses the same exact configuration.
           putOnlyEntry(
               resolvedDeps,
@@ -413,7 +414,7 @@ public final class ConfigurationResolver {
       Iterable<Class<? extends BuildConfiguration.Fragment>> requiredFragments,
       RuleClassProvider ruleClassProvider, boolean trimResults) {
     List<BuildOptions> result;
-    if (transition == Attribute.ConfigurationTransition.NONE) {
+    if (transition == ConfigurationTransitionProxy.NONE) {
       result = ImmutableList.<BuildOptions>of(fromOptions);
     } else if (transition instanceof PatchTransition) {
       // TODO(bazel-team): safety-check that this never mutates fromOptions.
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/DynamicTransitionMapper.java b/src/main/java/com/google/devtools/build/lib/analysis/config/DynamicTransitionMapper.java
index 4c492017c7..96316ebce5 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/DynamicTransitionMapper.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/DynamicTransitionMapper.java
@@ -24,7 +24,7 @@ import com.google.devtools.build.lib.packages.RuleClass;
  *
  * <p>Blaze applies configuration transitions by executing {@link PatchTransition} instances. But
  * for legacy reasons, not every transition declaration is a {@link PatchTransition}. The most
- * prominent example is {@link Attribute.ConfigurationTransition}, which defines its transitions as
+ * prominent example is {@link ConfigurationTransitionProxy}, which defines its transitions as
  * enums. These transitions are used all over the place. So we need a way to continue to support
  * them.
  *
@@ -36,7 +36,7 @@ import com.google.devtools.build.lib.packages.RuleClass;
  * {@link RuleClass.Builder#cfg(PatchTransition)}. That way, transition declarations "just work",
  * with no extra fuss. But this is a migration that will take some time to complete.
  *
- * {@link Attribute.ConfigurationTransition#DATA} provides the most complicated challenge. This is
+ * {@link ConfigurationTransitionProxy#DATA} provides the most complicated challenge. This is
  * C++/LIPO logic, and the implementation is in C++ rule code
  * ({@link com.google.devtools.build.lib.rules.cpp.transitions.DisableLipoTransition}). But the enum
  * is defined in {@link Attribute}, which is in {@code lib.packages}, which has access to neither
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/TransitionResolver.java b/src/main/java/com/google/devtools/build/lib/analysis/config/TransitionResolver.java
index 27c3548a2c..fe1a0f8f10 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/TransitionResolver.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/TransitionResolver.java
@@ -17,10 +17,10 @@ package com.google.devtools.build.lib.analysis.config;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 import com.google.devtools.build.lib.analysis.TargetAndConfiguration;
+import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy;
 import com.google.devtools.build.lib.analysis.config.transitions.SplitTransition;
 import com.google.devtools.build.lib.analysis.config.transitions.Transition;
 import com.google.devtools.build.lib.packages.Attribute;
-import com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition;
 import com.google.devtools.build.lib.packages.ConfiguredAttributeMapper;
 import com.google.devtools.build.lib.packages.InputFile;
 import com.google.devtools.build.lib.packages.PackageGroup;
@@ -61,20 +61,20 @@ public final class TransitionResolver {
    *
    * @return the child's configuration, expressed as a diff from the parent's configuration. This
    *     is usually a {@PatchTransition} but exceptions apply (e.g.
-   *     {@link Attribute.ConfigurationTransition}).
+   *     {@link ConfigurationTransitionProxy}).
    */
   public Transition evaluateTransition(BuildConfiguration fromConfig, final Rule fromRule,
       final Attribute attribute, final Target toTarget, ConfiguredAttributeMapper attributeMap) {
 
     // I. Input files and package groups have no configurations. We don't want to duplicate them.
     if (usesNullConfiguration(toTarget)) {
-      return Attribute.ConfigurationTransition.NULL;
+      return ConfigurationTransitionProxy.NULL;
     }
 
     // II. Host configurations never switch to another. All prerequisites of host targets have the
     // same host configuration.
     if (fromConfig.isHostConfiguration()) {
-      return Attribute.ConfigurationTransition.NONE;
+      return ConfigurationTransitionProxy.NONE;
     }
 
     // Make sure config_setting dependencies are resolved in the referencing rule's configuration,
@@ -91,13 +91,13 @@ public final class TransitionResolver {
     // TODO(bazel-team): don't require special casing here. This is far too hackish.
     if (toTarget instanceof Rule && ((Rule) toTarget).getRuleClassObject().isConfigMatcher()) {
       // TODO(gregce): see if this actually gets called
-      return Attribute.ConfigurationTransition.NONE;
+      return ConfigurationTransitionProxy.NONE;
     }
 
     // The current transition to apply. When multiple transitions are requested, this is a
     // ComposingSplitTransition, which encapsulates them into a single object so calling code
     // doesn't need special logic for combinations.
-    Transition currentTransition = Attribute.ConfigurationTransition.NONE;
+    Transition currentTransition = ConfigurationTransitionProxy.NONE;
 
     // Apply the parent rule's outgoing transition if it has one.
     RuleTransitionFactory transitionFactory =
@@ -137,7 +137,7 @@ public final class TransitionResolver {
     // Top-level transitions (chosen by configuration fragments):
     Transition topLevelTransition = fromConfig.topLevelConfigurationHook(target);
     if (topLevelTransition == null) {
-      topLevelTransition = ConfigurationTransition.NONE;
+      topLevelTransition = ConfigurationTransitionProxy.NONE;
     }
 
     // Rule class transitions (chosen by rule class definitions):
@@ -162,11 +162,11 @@ public final class TransitionResolver {
   public Transition composeTransitions(Transition transition1, Transition transition2) {
     if (isFinal(transition1)) {
       return transition1;
-    } else if (transition2 == Attribute.ConfigurationTransition.NONE) {
+    } else if (transition2 == ConfigurationTransitionProxy.NONE) {
       return transition1;
-    } else if (transition2 == Attribute.ConfigurationTransition.NULL) {
+    } else if (transition2 == ConfigurationTransitionProxy.NULL) {
       // A NULL transition can just replace earlier transitions: no need to compose them.
-      return Attribute.ConfigurationTransition.NULL;
+      return ConfigurationTransitionProxy.NULL;
     } else if (transition2.isHostTransition()) {
       // A HOST transition can just replace earlier transitions: no need to compose them.
       // But it also improves performance: host transitions are common, and
@@ -177,7 +177,7 @@ public final class TransitionResolver {
 
     // TODO(gregce): remove the below conversion when all transitions are patch transitions.
     Transition dynamicTransition = transitionMapper.map(transition2);
-    return transition1 == Attribute.ConfigurationTransition.NONE
+    return transition1 == ConfigurationTransitionProxy.NONE
         ? dynamicTransition
         : new ComposingSplitTransition(transition1, dynamicTransition);
   }
@@ -187,7 +187,7 @@ public final class TransitionResolver {
    * be composed after it.
    */
   private static boolean isFinal(Transition transition) {
-    return (transition == Attribute.ConfigurationTransition.NULL
+    return (transition == ConfigurationTransitionProxy.NULL
         || transition == HostTransition.INSTANCE);
   }
 
@@ -195,11 +195,11 @@ public final class TransitionResolver {
    * Applies the given split and composes it after an existing transition.
    */
   private static Transition split(Transition currentTransition, SplitTransition split) {
-    Preconditions.checkState(currentTransition != Attribute.ConfigurationTransition.NULL,
+    Preconditions.checkState(currentTransition != ConfigurationTransitionProxy.NULL,
         "cannot apply splits after null transitions (null transitions are expected to be final)");
     Preconditions.checkState(currentTransition != HostTransition.INSTANCE,
         "cannot apply splits after host transitions (host transitions are expected to be final)");
-    return currentTransition == Attribute.ConfigurationTransition.NONE
+    return currentTransition == ConfigurationTransitionProxy.NONE
         ? split
         : new ComposingSplitTransition(currentTransition, split);
   }
@@ -207,7 +207,7 @@ public final class TransitionResolver {
   /**
    * @param currentTransition a pre-existing transition to be composed with
    * @param toTarget rule to examine for transitions
-   * @param transitionMapper only needed because of Attribute.ConfigurationTransition.DATA: this is
+   * @param transitionMapper only needed because of ConfigurationTransitionProxy.DATA: this is
    *     C++-specific but non-C++ rules declare it. So they can't directly provide the C++-specific
    *     patch transition that implements it.
    */
@@ -223,7 +223,7 @@ public final class TransitionResolver {
       PatchTransition ruleClassTransition = (PatchTransition)
           transitionMapper.map(transitionFactory.buildTransitionFor(associatedRule));
       if (ruleClassTransition != null) {
-        if (currentTransition == ConfigurationTransition.NONE) {
+        if (currentTransition == ConfigurationTransitionProxy.NONE) {
           return ruleClassTransition;
         } else {
           return new ComposingSplitTransition(currentTransition, ruleClassTransition);
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/ConfigurationTransition.java b/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/ConfigurationTransitionProxy.java
index 6cee8d4509..1bf0f403ef 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/ConfigurationTransition.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/ConfigurationTransitionProxy.java
@@ -18,10 +18,11 @@ package com.google.devtools.build.lib.analysis.config.transitions;
  * Declaration how the configuration should change when following a label or label list attribute.
  *
  * <p>Do not add to this. This is a legacy interface from when Blaze had limited support for
- * transitions. Use {@link PatchTransition} or {@link SplitTransition} instead.
+ * transitions. Use {@link com.google.devtools.build.lib.analysis.config.PatchTransition} or
+ * {@link SplitTransition} instead.
  */
 @Deprecated
-public enum ConfigurationTransition implements Transition {
+public enum ConfigurationTransitionProxy implements Transition {
   /** No transition, i.e., the same configuration as the current. */
   NONE,
 
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkAttr.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkAttr.java
index 78e393fb51..9abc869ad9 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkAttr.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkAttr.java
@@ -20,12 +20,12 @@ import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.analysis.config.HostTransition;
+import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy;
 import com.google.devtools.build.lib.analysis.config.transitions.SplitTransition;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.Attribute.AllowedValueSet;
-import com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition;
 import com.google.devtools.build.lib.packages.Attribute.SkylarkComputedDefaultTemplate;
 import com.google.devtools.build.lib.packages.Attribute.SplitTransitionProvider;
 import com.google.devtools.build.lib.packages.AttributeValueSource;
@@ -295,7 +295,7 @@ public final class SkylarkAttr implements SkylarkValue {
     if (containsNonNoneKey(arguments, CONFIGURATION_ARG)) {
       Object trans = arguments.get(CONFIGURATION_ARG);
       if (trans.equals("data")) {
-        builder.cfg(ConfigurationTransition.DATA);
+        builder.cfg(ConfigurationTransitionProxy.DATA);
       } else if (trans.equals("host")) {
         builder.cfg(HostTransition.INSTANCE);
       } else if (trans instanceof SplitTransition) {
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleClassFunctions.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleClassFunctions.java
index e27d47963e..32a78c9ad2 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleClassFunctions.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleClassFunctions.java
@@ -15,7 +15,7 @@
 package com.google.devtools.build.lib.analysis.skylark;
 
 import static com.google.devtools.build.lib.analysis.BaseRuleClasses.RUN_UNDER;
-import static com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition.DATA;
+import static com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy.DATA;
 import static com.google.devtools.build.lib.packages.Attribute.attr;
 import static com.google.devtools.build.lib.packages.BuildType.LABEL;
 import static com.google.devtools.build.lib.packages.BuildType.LABEL_LIST;
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleContext.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleContext.java
index 3f8a54a71b..8ce345fc7b 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleContext.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkRuleContext.java
@@ -37,6 +37,7 @@ import com.google.devtools.build.lib.analysis.TransitiveInfoCollection;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.config.FragmentCollection;
 import com.google.devtools.build.lib.analysis.config.HostTransition;
+import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy;
 import com.google.devtools.build.lib.analysis.configuredtargets.RuleConfiguredTarget.Mode;
 import com.google.devtools.build.lib.analysis.stringtemplate.ExpansionException;
 import com.google.devtools.build.lib.analysis.test.InstrumentedFilesCollector;
@@ -46,7 +47,6 @@ import com.google.devtools.build.lib.events.Location;
 import com.google.devtools.build.lib.packages.Aspect;
 import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.Attribute;
-import com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition;
 import com.google.devtools.build.lib.packages.BuildType;
 import com.google.devtools.build.lib.packages.ImplicitOutputsFunction;
 import com.google.devtools.build.lib.packages.ImplicitOutputsFunction.SkylarkImplicitOutputsFunction;
@@ -225,7 +225,7 @@ public final class SkylarkRuleContext implements SkylarkValue {
     this.actionFactory = new SkylarkActionFactory(this, skylarkSemantics, ruleContext);
     this.ruleContext = Preconditions.checkNotNull(ruleContext);
     this.ruleLabelCanonicalName = ruleContext.getLabel().getCanonicalForm();
-    this.fragments = new FragmentCollection(ruleContext, ConfigurationTransition.NONE);
+    this.fragments = new FragmentCollection(ruleContext, ConfigurationTransitionProxy.NONE);
     this.hostFragments = new FragmentCollection(ruleContext, HostTransition.INSTANCE);
     this.aspectDescriptor = aspectDescriptor;
     this.skylarkSemantics = skylarkSemantics;
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/common/BazelFilegroupRule.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/common/BazelFilegroupRule.java
index 0548b00581..68844815ba 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/common/BazelFilegroupRule.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/common/BazelFilegroupRule.java
@@ -13,7 +13,7 @@
 // limitations under the License.
 package com.google.devtools.build.lib.bazel.rules.common;
 
-import static com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition.DATA;
+import static com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy.DATA;
 import static com.google.devtools.build.lib.packages.Attribute.attr;
 import static com.google.devtools.build.lib.packages.BuildType.LABEL_LIST;
 import static com.google.devtools.build.lib.packages.BuildType.LICENSE;
diff --git a/src/main/java/com/google/devtools/build/lib/packages/Attribute.java b/src/main/java/com/google/devtools/build/lib/packages/Attribute.java
index 38fdda7317..0a368e1fc8 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/Attribute.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/Attribute.java
@@ -29,6 +29,7 @@ import com.google.common.collect.Iterables;
 import com.google.common.collect.Ordering;
 import com.google.common.collect.Sets;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
+import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy;
 import com.google.devtools.build.lib.analysis.config.transitions.SplitTransition;
 import com.google.devtools.build.lib.analysis.config.transitions.Transition;
 import com.google.devtools.build.lib.events.EventHandler;
@@ -147,32 +148,6 @@ public final class Attribute implements Comparable<Attribute> {
     }
   }
 
-  /**
-   * Declaration how the configuration should change when following a label or label list attribute.
-   *
-   * <p>Do not add to this. Use {@link
-   * com.google.devtools.build.lib.analysis.config.PatchTransition} or {@link SplitTransition}
-   * instead.
-   */
-  public enum ConfigurationTransition implements Transition {
-    /** No transition, i.e., the same configuration as the current. */
-    NONE,
-
-    /** Transition to a null configuration (applies to, e.g., input files). */
-    NULL,
-
-    /** Transition from the target configuration to the data configuration. */
-    // TODO(bazel-team): Move this elsewhere.
-    DATA,
-
-    /**
-     * Transition to one or more configurations. To obtain the actual child configurations,
-     * invoke {@link Attribute#getSplitTransition(AttributeMap)}.
-     * See {@link SplitTransition}.
-     **/
-    SPLIT
-  }
-
   private enum PropertyFlag {
     MANDATORY,
     EXECUTABLE,
@@ -384,7 +359,7 @@ public final class Attribute implements Comparable<Attribute> {
   public static class Builder <TYPE> {
     private final String name;
     private final Type<TYPE> type;
-    private Transition configTransition = ConfigurationTransition.NONE;
+    private Transition configTransition = ConfigurationTransitionProxy.NONE;
     private RuleClassNamePredicate allowedRuleClassesForLabels = ANY_RULE;
     private RuleClassNamePredicate allowedRuleClassesForLabelsWarning = NO_RULE;
     private SplitTransitionProvider splitTransitionProvider;
@@ -504,11 +479,11 @@ public final class Attribute implements Comparable<Attribute> {
      * Defines the configuration transition for this attribute.
      */
     public Builder<TYPE> cfg(SplitTransitionProvider splitTransitionProvider) {
-      Preconditions.checkState(this.configTransition == ConfigurationTransition.NONE,
+      Preconditions.checkState(this.configTransition == ConfigurationTransitionProxy.NONE,
           "the configuration transition is already set");
 
       this.splitTransitionProvider = Preconditions.checkNotNull(splitTransitionProvider);
-      this.configTransition = ConfigurationTransition.SPLIT;
+      this.configTransition = ConfigurationTransitionProxy.SPLIT;
       return this;
     }
 
@@ -525,9 +500,9 @@ public final class Attribute implements Comparable<Attribute> {
      * {@code NONE}.
      */
     public Builder<TYPE> cfg(Transition configTransition) {
-      Preconditions.checkState(this.configTransition == ConfigurationTransition.NONE,
+      Preconditions.checkState(this.configTransition == ConfigurationTransitionProxy.NONE,
           "the configuration transition is already set");
-      Preconditions.checkArgument(configTransition != ConfigurationTransition.SPLIT,
+      Preconditions.checkArgument(configTransition != ConfigurationTransitionProxy.SPLIT,
           "split transitions must be defined using the SplitTransition object");
       if (configTransition instanceof SplitTransition) {
         return cfg((SplitTransition) configTransition);
@@ -1829,7 +1804,7 @@ public final class Attribute implements Comparable<Attribute> {
       ImmutableList<RuleAspect<?>> aspects) {
     Preconditions.checkNotNull(configTransition);
     Preconditions.checkArgument(
-        (configTransition == ConfigurationTransition.NONE)
+        (configTransition == ConfigurationTransitionProxy.NONE)
         || type.getLabelClass() == LabelClass.DEPENDENCY
         || type.getLabelClass() == LabelClass.NONDEP_REFERENCE,
         "Configuration transitions can only be specified for label or label list attributes");
diff --git a/src/main/java/com/google/devtools/build/lib/packages/ConfigurationFragmentPolicy.java b/src/main/java/com/google/devtools/build/lib/packages/ConfigurationFragmentPolicy.java
index fdc6061a99..6679f248b3 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/ConfigurationFragmentPolicy.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/ConfigurationFragmentPolicy.java
@@ -18,8 +18,8 @@ import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableSetMultimap;
 import com.google.common.collect.LinkedHashMultimap;
 import com.google.common.collect.SetMultimap;
+import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy;
 import com.google.devtools.build.lib.analysis.config.transitions.Transition;
-import com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import java.util.Collection;
 import java.util.Set;
@@ -82,7 +82,7 @@ public final class ConfigurationFragmentPolicy {
      * <p>The value is inherited by subclasses.
      */
     public Builder requiresConfigurationFragments(Collection<Class<?>> configurationFragments) {
-      requiresConfigurationFragments(ConfigurationTransition.NONE, configurationFragments);
+      requiresConfigurationFragments(ConfigurationTransitionProxy.NONE, configurationFragments);
       return this;
     }
 
@@ -98,7 +98,7 @@ public final class ConfigurationFragmentPolicy {
       // We can relax this assumption if needed. But it's already sketchy to let a rule see more
       // than its own configuration. So we don't want to casually proliferate this pattern.
       Preconditions.checkArgument(
-          transition == Attribute.ConfigurationTransition.NONE || transition.isHostTransition());
+          transition == ConfigurationTransitionProxy.NONE || transition.isHostTransition());
       requiredConfigurationFragments.putAll(transition, configurationFragments);
       return this;
     }
@@ -117,7 +117,7 @@ public final class ConfigurationFragmentPolicy {
         Collection<String> configurationFragmentNames) {
 
       requiresConfigurationFragmentsBySkylarkModuleName(
-          Attribute.ConfigurationTransition.NONE, configurationFragmentNames);
+          ConfigurationTransitionProxy.NONE, configurationFragmentNames);
       return this;
     }
 
@@ -136,7 +136,7 @@ public final class ConfigurationFragmentPolicy {
       // We can relax this assumption if needed. But it's already sketchy to let a rule see more
       // than its own configuration. So we don't want to casually proliferate this pattern.
       Preconditions.checkArgument(
-          transition == ConfigurationTransition.NONE || transition.isHostTransition());
+          transition == ConfigurationTransitionProxy.NONE || transition.isHostTransition());
       requiredConfigurationFragmentNames.putAll(transition, configurationFragmentNames);
       return this;
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcImportRule.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcImportRule.java
index 6529e5c4fb..9339a5b919 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcImportRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcImportRule.java
@@ -14,7 +14,7 @@
 
 package com.google.devtools.build.lib.rules.cpp;
 
-import static com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition.DATA;
+import static com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy.DATA;
 import static com.google.devtools.build.lib.packages.Attribute.attr;
 import static com.google.devtools.build.lib.packages.BuildType.LABEL;
 import static com.google.devtools.build.lib.packages.BuildType.LABEL_LIST;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppRuleClasses.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppRuleClasses.java
index 90cca62ef2..c46c30e00a 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppRuleClasses.java
@@ -34,10 +34,10 @@ import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.analysis.LanguageDependentFragment.LibraryLanguage;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
 import com.google.devtools.build.lib.analysis.config.PatchTransition;
+import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy;
 import com.google.devtools.build.lib.analysis.config.transitions.Transition;
 import com.google.devtools.build.lib.analysis.test.InstrumentedFilesCollector.InstrumentationSpec;
 import com.google.devtools.build.lib.cmdline.Label;
-import com.google.devtools.build.lib.packages.Attribute;
 import com.google.devtools.build.lib.packages.Attribute.LateBoundDefault;
 import com.google.devtools.build.lib.packages.ImplicitOutputsFunction.SafeImplicitOutputsFunction;
 import com.google.devtools.build.lib.packages.RuleTransitionFactory;
@@ -71,7 +71,7 @@ public class CppRuleClasses {
    */
   public static final ImmutableMap<Transition, Transition> DYNAMIC_TRANSITIONS_MAP =
       ImmutableMap.of(
-          Attribute.ConfigurationTransition.DATA, DisableLipoTransition.INSTANCE
+          ConfigurationTransitionProxy.DATA, DisableLipoTransition.INSTANCE
       );
 
 
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
index c2295c4b60..5504107d95 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
@@ -73,6 +73,7 @@ import com.google.devtools.build.lib.analysis.config.ConfigurationResolver;
 import com.google.devtools.build.lib.analysis.config.HostTransition;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
 import com.google.devtools.build.lib.analysis.config.PatchTransition;
+import com.google.devtools.build.lib.analysis.config.transitions.ConfigurationTransitionProxy;
 import com.google.devtools.build.lib.analysis.config.transitions.Transition;
 import com.google.devtools.build.lib.analysis.configuredtargets.MergedConfiguredTarget;
 import com.google.devtools.build.lib.analysis.configuredtargets.MergedConfiguredTarget.DuplicateException;
@@ -88,14 +89,11 @@ import com.google.devtools.build.lib.events.ExtendedEventHandler;
 import com.google.devtools.build.lib.events.Reporter;
 import com.google.devtools.build.lib.packages.AspectDescriptor;
 import com.google.devtools.build.lib.packages.AstParseResult;
-import com.google.devtools.build.lib.packages.Attribute;
-import com.google.devtools.build.lib.packages.Attribute.ConfigurationTransition;
 import com.google.devtools.build.lib.packages.BuildFileContainsErrorsException;
 import com.google.devtools.build.lib.packages.BuildFileName;
 import com.google.devtools.build.lib.packages.NoSuchPackageException;
 import com.google.devtools.build.lib.packages.NoSuchThingException;
 import com.google.devtools.build.lib.packages.Package;
-import com.google.devtools.build.lib.packages.Package.Builder;
 import com.google.devtools.build.lib.packages.PackageFactory;
 import com.google.devtools.build.lib.packages.RuleClassProvider;
 import com.google.devtools.build.lib.packages.RuleVisibility;
@@ -1124,8 +1122,8 @@ public abstract class SkyframeExecutor implements WalkableGraphFactory {
     Transition dataTransition =
         ((ConfiguredRuleClassProvider) ruleClassProvider)
             .getDynamicTransitionMapper()
-            .map(Attribute.ConfigurationTransition.DATA);
-    BuildOptions dataOptions = dataTransition != Attribute.ConfigurationTransition.NONE
+            .map(ConfigurationTransitionProxy.DATA);
+    BuildOptions dataOptions = dataTransition != ConfigurationTransitionProxy.NONE
         ? ((PatchTransition) dataTransition).apply(firstTargetConfig.getOptions())
         : firstTargetConfig.getOptions();
 
@@ -1593,7 +1591,7 @@ public abstract class SkyframeExecutor implements WalkableGraphFactory {
   public ConfiguredTarget getConfiguredTargetForTesting(
       ExtendedEventHandler eventHandler, Label label, BuildConfiguration configuration) {
     return getConfiguredTargetForTesting(
-        eventHandler, label, configuration, ConfigurationTransition.NONE);
+        eventHandler, label, configuration, ConfigurationTransitionProxy.NONE);
   }
 
   /**