Introduce a wrapper around the ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>> set of Fragment classes that is part of the BuildConfigurationValue.Key. This class allows us to compute a fingerprint of the wrapped ImmutableSortedSet, making equality comparisons fast. The number of additional wrapper objects is the number of distinct sets of fragment classes, so 1. (In fact, we don't even need to compute a fingerprint, since reference equality does the job for us here, but we do it just to be conservative.)

This CL has a performance benefit for Bazel currently, but has a bigger performance benefit in the following changes, where there are more BuildConfigurationValue.Key objects to compare.

PiperOrigin-RevId: 183090122

11 files changed, 152 insertions, 45 deletions

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 ab9981b93d..4a1bd249f7 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
@@ -26,7 +26,6 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableMultimap;
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Multimap;
@@ -45,6 +44,7 @@ import com.google.devtools.build.lib.analysis.config.BuildConfigurationCollectio
 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.ConfigurationResolver;
+import com.google.devtools.build.lib.analysis.config.FragmentClassSet;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
 import com.google.devtools.build.lib.analysis.config.transitions.NoTransition;
 import com.google.devtools.build.lib.analysis.config.transitions.PatchTransition;
@@ -954,9 +954,12 @@ public class BuildView {
 
       @Override
       protected List<BuildConfiguration> getConfigurations(
-          ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>> fragments,
-          Iterable<BuildOptions> buildOptions) {
-        Preconditions.checkArgument(ct.getConfiguration().fragmentClasses().equals(fragments));
+          FragmentClassSet fragments, Iterable<BuildOptions> buildOptions) {
+        Preconditions.checkArgument(
+            ct.getConfiguration().fragmentClasses().equals(fragments),
+            "Mismatch: %s %s",
+            ct,
+            fragments);
         Dependency asDep = Dependency.withTransitionAndAspects(ct.getLabel(),
             NoTransition.INSTANCE, AspectCollection.EMPTY);
         ImmutableList.Builder<BuildConfiguration> builder = ImmutableList.builder();
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 c87ca9b03a..ea542dfffa 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
@@ -18,12 +18,12 @@ import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.ImmutableSortedSet;
 import com.google.devtools.build.lib.analysis.AspectCollection.AspectCycleOnPathException;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 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.DynamicTransitionMapper;
+import com.google.devtools.build.lib.analysis.config.FragmentClassSet;
 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.TransitionResolver;
@@ -875,8 +875,7 @@ public abstract class DependencyResolver {
    */
   @Nullable
   protected abstract List<BuildConfiguration> getConfigurations(
-      ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>> fragments,
-      Iterable<BuildOptions> buildOptions)
+      FragmentClassSet fragments, Iterable<BuildOptions> buildOptions)
       throws InvalidConfigurationException, InterruptedException;
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
index 10daadda48..3b54a8b17c 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
@@ -26,7 +26,6 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableSortedMap;
-import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Interner;
 import com.google.common.collect.Interners;
 import com.google.common.collect.Iterables;
@@ -1112,6 +1111,7 @@ public class BuildConfiguration implements BuildEvent {
   private final String checksum;
 
   private final ImmutableSortedMap<Class<? extends Fragment>, Fragment> fragments;
+  private final FragmentClassSet fragmentClassSet;
 
   private final ImmutableMap<String, Class<? extends Fragment>> skylarkVisibleFragments;
   private final String repositoryName;
@@ -1390,6 +1390,7 @@ public class BuildConfiguration implements BuildEvent {
       String repositoryName) {
     this.directories = directories;
     this.fragments = makeFragmentsMap(fragmentsMap);
+    this.fragmentClassSet = FragmentClassSet.of(this.fragments.keySet());
 
     this.skylarkVisibleFragments = buildIndexOfSkylarkVisibleFragments();
     this.repositoryName = repositoryName;
@@ -1475,12 +1476,11 @@ public class BuildConfiguration implements BuildEvent {
    * configuration is assumed to have).
    */
   public BuildConfiguration clone(
-      Set<Class<? extends BuildConfiguration.Fragment>> fragmentClasses,
-      RuleClassProvider ruleClassProvider) {
+      FragmentClassSet fragmentClasses, RuleClassProvider ruleClassProvider) {
 
     ClassToInstanceMap<Fragment> fragmentsMap = MutableClassToInstanceMap.create();
     for (Fragment fragment : fragments.values()) {
-      if (fragmentClasses.contains(fragment.getClass())) {
+      if (fragmentClasses.fragmentClasses().contains(fragment.getClass())) {
         fragmentsMap.put(fragment.getClass(), fragment);
       }
     }
@@ -1847,8 +1847,8 @@ public class BuildConfiguration implements BuildEvent {
   }
 
   /** Which fragments does this configuration contain? */
-  public ImmutableSortedSet<Class<? extends Fragment>> fragmentClasses() {
-    return fragments.keySet();
+  public FragmentClassSet fragmentClasses() {
+    return fragmentClassSet;
   }
 
   /**
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 249ac0c5e4..57cf02b1f1 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
@@ -19,7 +19,6 @@ import com.google.common.base.Joiner;
 import com.google.common.base.Verify;
 import com.google.common.base.VerifyException;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.LinkedHashMultimap;
 import com.google.common.collect.LinkedListMultimap;
@@ -123,8 +122,7 @@ public final class ConfigurationResolver {
     Map<FragmentsAndTransition, List<BuildOptions>> transitionsMap = new LinkedHashMap<>();
 
     // The fragments used by the current target's configuration.
-    ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>> ctgFragments =
-        ctgValue.getConfiguration().fragmentClasses();
+    FragmentClassSet ctgFragments = ctgValue.getConfiguration().fragmentClasses();
     BuildOptions ctgOptions = ctgValue.getConfiguration().getOptions();
 
     // Stores the configuration-resolved versions of each dependency. This method must preserve the
@@ -183,7 +181,7 @@ public final class ConfigurationResolver {
             depFragments);
       }
 
-      boolean sameFragments = depFragments.equals(ctgFragments);
+      boolean sameFragments = depFragments.equals(ctgFragments.fragmentClasses());
       Transition transition = dep.getTransition();
 
       if (sameFragments) {
@@ -233,9 +231,12 @@ public final class ConfigurationResolver {
 
       // If we get here, we have to get the configuration from Skyframe.
       for (BuildOptions options : toOptions) {
-        keysToEntries.put(
-            BuildConfigurationValue.key(sameFragments ? ctgFragments : depFragments, options),
-            depsEntry);
+        if (sameFragments) {
+          keysToEntries.put(BuildConfigurationValue.key(ctgFragments, options), depsEntry);
+
+        } else {
+          keysToEntries.put(BuildConfigurationValue.key(depFragments, options), depsEntry);
+        }
       }
     }
 
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/FragmentClassSet.java b/src/main/java/com/google/devtools/build/lib/analysis/config/FragmentClassSet.java
new file mode 100644
index 0000000000..a419224b7e
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/FragmentClassSet.java
@@ -0,0 +1,98 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.analysis.config;
+
+import com.google.common.collect.ImmutableSortedSet;
+import com.google.common.collect.Interner;
+import com.google.devtools.build.lib.concurrent.BlazeInterners;
+import com.google.devtools.build.lib.util.Fingerprint;
+import java.util.Arrays;
+import javax.annotation.Nullable;
+
+/**
+ * A wrapper class for an {@code ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>>}
+ * object. Interning these objects allows us to do cheap reference equality checks when these sets
+ * are in frequently used keys. For good measure, we also compute a fingerprint.
+ */
+public class FragmentClassSet {
+  private final ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>> fragments;
+
+  // Lazily initialized.
+  @Nullable private volatile byte[] fingerprint;
+  private volatile int hashCode;
+
+  private FragmentClassSet(
+      ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>> fragments) {
+    this.fragments = fragments;
+  }
+
+  private static final Interner<FragmentClassSet> interner = BlazeInterners.newWeakInterner();
+
+  public static FragmentClassSet of(
+      ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>> fragments) {
+    return interner.intern(new FragmentClassSet(fragments));
+  }
+
+  public ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>> fragmentClasses() {
+    return fragments;
+  }
+
+  /**
+   * Lazily initialize {@link #fingerprint} and {@link #hashCode}. Keeps computation off critical
+   * path of build, while still avoiding expensive computation for equality and hash code each time.
+   *
+   * <p>We check for nullity of {@link #fingerprint} to see if this method has already been called.
+   * Using {@link #hashCode} after this method is called is safe because it is set here before
+   * {@link #fingerprint} is set, so if {@link #fingerprint} is non-null then {@link #hashCode} is
+   * definitely set.
+   */
+  private void maybeInitializeFingerprintAndHashCode() {
+    if (fingerprint != null) {
+      return;
+    }
+    synchronized (this) {
+      if (fingerprint != null) {
+        return;
+      }
+      Fingerprint fingerprint = new Fingerprint();
+      for (Class<? extends BuildConfiguration.Fragment> fragment : fragments) {
+        fingerprint.addString(fragment.getName());
+      }
+      byte[] computedFingerprint = fingerprint.digestAndReset();
+      hashCode = Arrays.hashCode(computedFingerprint);
+      this.fingerprint = computedFingerprint;
+    }
+  }
+
+  @Override
+  public boolean equals(Object other) {
+    if (this == other) {
+      return true;
+    } else if (!(other instanceof FragmentClassSet)) {
+      return false;
+    } else {
+      maybeInitializeFingerprintAndHashCode();
+      FragmentClassSet that = (FragmentClassSet) other;
+      that.maybeInitializeFingerprintAndHashCode();
+      return Arrays.equals(this.fingerprint, that.fingerprint);
+    }
+  }
+
+  @Override
+  public int hashCode() {
+    maybeInitializeFingerprintAndHashCode();
+    return hashCode;
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/BuildConfigurationValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/BuildConfigurationValue.java
index c42539aace..df86614495 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/BuildConfigurationValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/BuildConfigurationValue.java
@@ -17,8 +17,8 @@ import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Interner;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
-import com.google.devtools.build.lib.analysis.config.BuildConfiguration.Fragment;
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
+import com.google.devtools.build.lib.analysis.config.FragmentClassSet;
 import com.google.devtools.build.lib.concurrent.BlazeInterners;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
 import com.google.devtools.build.lib.skyframe.serialization.InjectingObjectCodec;
@@ -67,28 +67,29 @@ public class BuildConfigurationValue implements SkyValue {
   @ThreadSafe
   public static Key key(
       Set<Class<? extends BuildConfiguration.Fragment>> fragments, BuildOptions buildOptions) {
-    return keyInterner.intern(
-        new Key(
-            ImmutableSortedSet.copyOf(BuildConfiguration.lexicalFragmentSorter, fragments),
-            buildOptions));
+    return key(
+        FragmentClassSet.of(
+            ImmutableSortedSet.copyOf(BuildConfiguration.lexicalFragmentSorter, fragments)),
+        buildOptions);
   }
 
-  static final class Key implements SkyKey, Serializable {
-    static final ObjectCodec<Key> CODEC = new Codec();
+  public static Key key(FragmentClassSet fragmentClassSet, BuildOptions buildOptions) {
+    return keyInterner.intern(new Key(fragmentClassSet, buildOptions));
+  }
 
-    private final ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>> fragments;
+  static final class Key implements SkyKey, Serializable {
+    private final FragmentClassSet fragments;
     private final BuildOptions buildOptions;
     // If hashCode really is -1, we'll recompute it from scratch each time. Oh well.
     private volatile int hashCode = -1;
 
-    private Key(
-        ImmutableSortedSet<Class<? extends Fragment>> fragments, BuildOptions buildOptions) {
+    private Key(FragmentClassSet fragments, BuildOptions buildOptions) {
       this.fragments = fragments;
       this.buildOptions = Preconditions.checkNotNull(buildOptions);
     }
 
     ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>> getFragments() {
-      return fragments;
+      return fragments.fragmentClasses();
     }
 
     BuildOptions getBuildOptions() {
@@ -131,8 +132,9 @@ public class BuildConfigurationValue implements SkyValue {
       public void serialize(Key obj, CodedOutputStream codedOut)
           throws SerializationException, IOException {
         BuildOptions.CODEC.serialize(obj.buildOptions, codedOut);
-        codedOut.writeInt32NoTag(obj.fragments.size());
-        for (Class<? extends BuildConfiguration.Fragment> fragment : obj.fragments) {
+        codedOut.writeInt32NoTag(obj.fragments.fragmentClasses().size());
+        for (Class<? extends BuildConfiguration.Fragment> fragment :
+            obj.fragments.fragmentClasses()) {
           StringCodecs.asciiOptimized().serialize(fragment.getName(), codedOut);
         }
       }
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeBuildView.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeBuildView.java
index 5d4e24aad7..118a636294 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeBuildView.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeBuildView.java
@@ -47,6 +47,7 @@ import com.google.devtools.build.lib.analysis.buildinfo.BuildInfoFactory.BuildIn
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.config.BuildConfigurationCollection;
 import com.google.devtools.build.lib.analysis.config.ConfigMatchingProvider;
+import com.google.devtools.build.lib.analysis.config.FragmentClassSet;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.events.Event;
@@ -112,8 +113,8 @@ public final class SkyframeBuildView {
   private BuildConfiguration topLevelHostConfiguration;
   // Fragment-limited versions of the host configuration. It's faster to create/cache these here
   // than to store them in Skyframe.
-  private Map<Set<Class<? extends BuildConfiguration.Fragment>>, BuildConfiguration>
-      hostConfigurationCache = Maps.newConcurrentMap();
+  private Map<FragmentClassSet, BuildConfiguration> hostConfigurationCache =
+      Maps.newConcurrentMap();
 
   private BuildConfigurationCollection configurations;
 
@@ -545,10 +546,10 @@ public final class SkyframeBuildView {
     // trims a host configuration to the same scope as a target configuration. Since their options
     // are different, the host instance may actually be able to produce the fragment. So it's
     // wrong and potentially dangerous to unilaterally exclude it.
-    Set<Class<? extends BuildConfiguration.Fragment>> fragmentClasses =
+    FragmentClassSet fragmentClasses =
         config.trimConfigurations()
             ? config.fragmentClasses()
-            : ruleClassProvider.getAllFragments();
+            : FragmentClassSet.of(ruleClassProvider.getAllFragments());
     BuildConfiguration hostConfig = hostConfigurationCache.get(fragmentClasses);
     if (hostConfig != null) {
       return hostConfig;
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeDependencyResolver.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeDependencyResolver.java
index 4c5a674f33..e627332dab 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeDependencyResolver.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeDependencyResolver.java
@@ -14,12 +14,12 @@
 package com.google.devtools.build.lib.skyframe;
 
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableSortedSet;
 import com.google.devtools.build.lib.analysis.DependencyResolver;
 import com.google.devtools.build.lib.analysis.TargetAndConfiguration;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.analysis.config.DynamicTransitionMapper;
+import com.google.devtools.build.lib.analysis.config.FragmentClassSet;
 import com.google.devtools.build.lib.analysis.config.InvalidConfigurationException;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
@@ -126,8 +126,7 @@ public final class SkyframeDependencyResolver extends DependencyResolver {
   @Nullable
   @Override
   protected List<BuildConfiguration> getConfigurations(
-      ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>> fragments,
-      Iterable<BuildOptions> buildOptions)
+      FragmentClassSet fragments, Iterable<BuildOptions> buildOptions)
       throws InvalidConfigurationException, InterruptedException {
     List<SkyKey> keys = new ArrayList<>();
     for (BuildOptions options : buildOptions) {
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 cca618a403..d7da8c0778 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
@@ -71,6 +71,7 @@ import com.google.devtools.build.lib.analysis.config.BuildConfigurationCollectio
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.analysis.config.ConfigurationFragmentFactory;
 import com.google.devtools.build.lib.analysis.config.ConfigurationResolver;
+import com.google.devtools.build.lib.analysis.config.FragmentClassSet;
 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.transitions.ConfigurationTransitionProxy;
@@ -1623,7 +1624,7 @@ public abstract class SkyframeExecutor implements WalkableGraphFactory {
   @VisibleForTesting
   public BuildConfiguration getConfigurationForTesting(
       ExtendedEventHandler eventHandler,
-      ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>> fragments,
+      FragmentClassSet fragments,
       BuildOptions options)
       throws InterruptedException {
     SkyKey key = BuildConfigurationValue.key(fragments, options);
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/DependencyResolverTest.java b/src/test/java/com/google/devtools/build/lib/analysis/DependencyResolverTest.java
index 4251210d95..fc44c70cbd 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/DependencyResolverTest.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/DependencyResolverTest.java
@@ -17,10 +17,10 @@ import static com.google.common.truth.Truth.assertThat;
 import static com.google.common.truth.Truth.assertWithMessage;
 
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.ImmutableSortedSet;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 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.FragmentClassSet;
 import com.google.devtools.build.lib.analysis.util.AnalysisTestCase;
 import com.google.devtools.build.lib.analysis.util.TestAspects;
 import com.google.devtools.build.lib.cmdline.Label;
@@ -91,8 +91,7 @@ public class DependencyResolverTest extends AnalysisTestCase {
           @Nullable
           @Override
           protected List<BuildConfiguration> getConfigurations(
-              ImmutableSortedSet<Class<? extends BuildConfiguration.Fragment>> fragments,
-              Iterable<BuildOptions> buildOptions) {
+              FragmentClassSet fragments, Iterable<BuildOptions> buildOptions) {
             throw new UnsupportedOperationException(
                 "this functionality is covered by analysis-phase integration tests");
           }
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/config/BuildConfigurationTest.java b/src/test/java/com/google/devtools/build/lib/analysis/config/BuildConfigurationTest.java
index 8501af640c..2bc20c343a 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/config/BuildConfigurationTest.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/config/BuildConfigurationTest.java
@@ -18,6 +18,7 @@ import static org.junit.Assert.fail;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration.Fragment;
 import com.google.devtools.build.lib.analysis.util.ConfigurationTestCase;
@@ -283,7 +284,10 @@ public class BuildConfigurationTest extends ConfigurationTestCase {
     BuildConfiguration config = create();
     BuildConfiguration trimmedConfig =
         config.clone(
-            ImmutableSet.<Class<? extends Fragment>>of(CppConfiguration.class),
+            FragmentClassSet.of(
+                ImmutableSortedSet.orderedBy(BuildConfiguration.lexicalFragmentSorter)
+                    .add(CppConfiguration.class)
+                    .build()),
             analysisMock.createRuleClassProvider());
     BuildConfiguration hostConfig = createHost();