Remove DepsContext from CppCompilationContext. This simplifies the

CppCompilationContext as well as preparing it for further refactorings.

DepsContext was introduced before NestedSets were available and is superfluous
in a NestedSet world.

--
MOS_MIGRATED_REVID=123653478

1 files changed, 152 insertions, 265 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompilationContext.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompilationContext.java
index 691deb8c12..b3b293bfb1 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompilationContext.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompilationContext.java
@@ -33,7 +33,6 @@ import com.google.devtools.build.lib.util.Preconditions;
 import com.google.devtools.build.lib.vfs.PathFragment;
 
 import java.util.LinkedHashSet;
-import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
@@ -48,7 +47,41 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
   public static final CppCompilationContext EMPTY = new Builder(null).build();
 
   private final CommandLineContext commandLineContext;
-  private final ImmutableList<DepsContext> depsContexts;
+  
+  private final NestedSet<PathFragment> declaredIncludeDirs;
+  private final NestedSet<PathFragment> declaredIncludeWarnDirs;
+  private final NestedSet<Artifact> declaredIncludeSrcs;
+  
+  /**
+   * Module maps from direct dependencies.
+   */
+  private final NestedSet<Artifact> directModuleMaps;
+
+  /**
+   * All declared headers of the current module, if compiled as a header module.
+   */
+  private final NestedSet<Artifact> headerModuleSrcs;
+
+  /**
+   * All header modules in the transitive closure of {@code topLevelHeaderModules}.
+   */
+  private final NestedSet<Artifact> impliedHeaderModules;
+  private final NestedSet<Artifact> picImpliedHeaderModules;
+
+  private final NestedSet<Pair<Artifact, Artifact>> pregreppedHdrs;
+
+  /**
+   * All header modules in our transitive closure that are not in the transitive closure of
+   * another header module in our transitive closure.
+   */
+  private final NestedSet<Artifact> topLevelHeaderModules;
+  private final NestedSet<Artifact> picTopLevelHeaderModules;
+
+  /**
+   * The module maps from all targets the current target depends on transitively.
+   */
+  private final NestedSet<Artifact> transitiveModuleMaps;
+
   private final CppModuleMap cppModuleMap;
   private final Artifact headerModule;
   private final Artifact picHeaderModule;
@@ -64,37 +97,42 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
 
   private CppCompilationContext(
       CommandLineContext commandLineContext,
-      List<DepsContext> depsContexts,
+      ImmutableSet<Artifact> compilationPrerequisites,
+      NestedSet<PathFragment> declaredIncludeDirs,
+      NestedSet<PathFragment> declaredIncludeWarnDirs,
+      NestedSet<Artifact> declaredIncludeSrcs,
+      NestedSet<Pair<Artifact, Artifact>> pregreppedHdrs,
+      NestedSet<Artifact> headerModuleSrcs,
+      NestedSet<Artifact> topLevelHeaderModules,
+      NestedSet<Artifact> picTopLevelHeaderModules,
+      NestedSet<Artifact> impliedHeaderModules,
+      NestedSet<Artifact> picImpliedHeaderModules,
+      NestedSet<Artifact> transitiveModuleMaps,
+      NestedSet<Artifact> directModuleMaps,
       CppModuleMap cppModuleMap,
       Artifact headerModule,
       Artifact picHeaderModule,
       boolean provideTransitiveModuleMaps,
       boolean useHeaderModules) {
     Preconditions.checkNotNull(commandLineContext);
-    Preconditions.checkArgument(!depsContexts.isEmpty());
     this.commandLineContext = commandLineContext;
-    this.depsContexts = ImmutableList.copyOf(depsContexts);
+    this.declaredIncludeDirs = declaredIncludeDirs;
+    this.declaredIncludeWarnDirs = declaredIncludeWarnDirs;
+    this.declaredIncludeSrcs = declaredIncludeSrcs;
+    this.directModuleMaps = directModuleMaps;
+    this.headerModuleSrcs = headerModuleSrcs;
+    this.impliedHeaderModules = impliedHeaderModules;
+    this.picImpliedHeaderModules = picImpliedHeaderModules;
+    this.pregreppedHdrs = pregreppedHdrs;
+    this.topLevelHeaderModules = topLevelHeaderModules;
+    this.picTopLevelHeaderModules = picTopLevelHeaderModules;
+    this.transitiveModuleMaps = transitiveModuleMaps;
     this.cppModuleMap = cppModuleMap;
     this.headerModule = headerModule;
     this.picHeaderModule = picHeaderModule;
     this.provideTransitiveModuleMaps = provideTransitiveModuleMaps;
     this.useHeaderModules = useHeaderModules;
-
-    if (depsContexts.size() == 1) {
-      // Only LIPO targets have more than one DepsContexts. This codepath avoids creating
-      // an ImmutableSet.Builder for the vast majority of the cases.
-      compilationPrerequisites = (depsContexts.get(0).compilationPrerequisiteStampFile != null)
-          ? ImmutableSet.<Artifact>of(depsContexts.get(0).compilationPrerequisiteStampFile)
-          : ImmutableSet.<Artifact>of();
-    } else {
-      ImmutableSet.Builder<Artifact> prerequisites = ImmutableSet.builder();
-      for (DepsContext depsContext : depsContexts) {
-        if (depsContext.compilationPrerequisiteStampFile != null) {
-          prerequisites.add(depsContext.compilationPrerequisiteStampFile);
-        }
-      }
-      compilationPrerequisites = prerequisites.build();
-    }
+    this.compilationPrerequisites = compilationPrerequisites;
   }
 
   /**
@@ -164,20 +202,7 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
    * used by consumers.
    */
   public NestedSet<PathFragment> getDeclaredIncludeDirs() {
-    if (depsContexts.isEmpty()) {
-      return NestedSetBuilder.emptySet(Order.STABLE_ORDER);
-    }
-
-    if (depsContexts.size() == 1) {
-      return depsContexts.get(0).declaredIncludeDirs;
-    }
-
-    NestedSetBuilder<PathFragment> builder = NestedSetBuilder.stableOrder();
-    for (DepsContext depsContext : depsContexts) {
-      builder.addTransitive(depsContext.declaredIncludeDirs);
-    }
-
-    return builder.build();
+    return declaredIncludeDirs;
   }
 
   /**
@@ -191,20 +216,7 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
    * used by consumers.
    */
   public NestedSet<PathFragment> getDeclaredIncludeWarnDirs() {
-    if (depsContexts.isEmpty()) {
-      return NestedSetBuilder.emptySet(Order.STABLE_ORDER);
-    }
-
-    if (depsContexts.size() == 1) {
-      return depsContexts.get(0).declaredIncludeWarnDirs;
-    }
-
-    NestedSetBuilder<PathFragment> builder = NestedSetBuilder.stableOrder();
-    for (DepsContext depsContext : depsContexts) {
-      builder.addTransitive(depsContext.declaredIncludeWarnDirs);
-    }
-
-    return builder.build();
+    return declaredIncludeWarnDirs;
   }
 
   /**
@@ -217,20 +229,7 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
    * used by consumers.
    */
   public NestedSet<Artifact> getDeclaredIncludeSrcs() {
-    if (depsContexts.isEmpty()) {
-      return NestedSetBuilder.emptySet(Order.STABLE_ORDER);
-    }
-
-    if (depsContexts.size() == 1) {
-      return depsContexts.get(0).declaredIncludeSrcs;
-    }
-
-    NestedSetBuilder<Artifact> builder = NestedSetBuilder.stableOrder();
-    for (DepsContext depsContext : depsContexts) {
-      builder.addTransitive(depsContext.declaredIncludeSrcs);
-    }
-
-    return builder.build();
+    return declaredIncludeSrcs;
   }
 
   /**
@@ -238,20 +237,7 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
    * (pregrepped header file) are generated by {@link ExtractInclusionAction}.
    */
   NestedSet<Pair<Artifact, Artifact>> getPregreppedHeaders() {
-    if (depsContexts.isEmpty()) {
-      return NestedSetBuilder.emptySet(Order.STABLE_ORDER);
-    }
-
-    if (depsContexts.size() == 1) {
-      return depsContexts.get(0).pregreppedHdrs;
-    }
-
-    NestedSetBuilder<Pair<Artifact, Artifact>> builder = NestedSetBuilder.stableOrder();
-    for (DepsContext depsContext : depsContexts) {
-      builder.addTransitive(depsContext.pregreppedHdrs);
-    }
-
-    return builder.build();
+    return pregreppedHdrs;
   }
 
   /**
@@ -259,26 +245,20 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
    * compilation, like C++ module map artifacts.
    */
   public NestedSet<Artifact> getAdditionalInputs(boolean usePic) {
-    if (depsContexts.isEmpty()) {
-      return NestedSetBuilder.emptySet(Order.STABLE_ORDER);
-    }
-
     NestedSetBuilder<Artifact> builder = NestedSetBuilder.stableOrder();
-    for (DepsContext depsContext : depsContexts) {
-      if (useHeaderModules) {
-        if (usePic) {
-          builder.addTransitive(depsContext.picTopLevelHeaderModules);
-          builder.addTransitive(depsContext.picImpliedHeaderModules);
-        } else {
-          builder.addTransitive(depsContext.topLevelHeaderModules);
-          builder.addTransitive(depsContext.impliedHeaderModules);
-        }
-      }
-      builder.addTransitive(depsContext.directModuleMaps);
-      if (provideTransitiveModuleMaps) {
-        builder.addTransitive(depsContext.transitiveModuleMaps);
+    if (useHeaderModules) {
+      if (usePic) {
+        builder.addTransitive(picTopLevelHeaderModules);
+        builder.addTransitive(picImpliedHeaderModules);
+      } else {
+        builder.addTransitive(topLevelHeaderModules);
+        builder.addTransitive(impliedHeaderModules);
       }
     }
+    builder.addTransitive(directModuleMaps);
+    if (provideTransitiveModuleMaps) {
+      builder.addTransitive(transitiveModuleMaps);
+    }
     if (cppModuleMap != null) {
       builder.add(cppModuleMap.getArtifact());
     }
@@ -290,22 +270,14 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
    * @return modules maps from direct dependencies.
    */
   public NestedSet<Artifact> getDirectModuleMaps() {
-    NestedSetBuilder<Artifact> builder = NestedSetBuilder.stableOrder();
-    for (DepsContext depsContext : depsContexts) {
-      builder.addTransitive(depsContext.directModuleMaps);
-    }
-    return builder.build();
+    return directModuleMaps;
   }
 
   /**
    * @return modules maps in the transitive closure that are not from direct dependencies.
    */
   private NestedSet<Artifact> getTransitiveModuleMaps() {
-    NestedSetBuilder<Artifact> builder = NestedSetBuilder.stableOrder();
-    for (DepsContext depsContext : depsContexts) {
-      builder.addTransitive(depsContext.transitiveModuleMaps);
-    }
-    return builder.build();
+    return transitiveModuleMaps;
   }
 
   /**
@@ -313,11 +285,7 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
    * is compiled as a module.
    */
   protected NestedSet<Artifact> getHeaderModuleSrcs() {
-    NestedSetBuilder<Artifact> builder = NestedSetBuilder.stableOrder();
-    for (DepsContext depsContext : depsContexts) {
-      builder.addTransitive(depsContext.headerModuleSrcs);
-    }
-    return builder.build();
+    return headerModuleSrcs;
   }
 
   /**
@@ -325,24 +293,14 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
    * of another header module in our transitive closure.
    */
   protected NestedSet<Artifact> getTopLevelHeaderModules(boolean usePic) {
-    NestedSetBuilder<Artifact> builder = NestedSetBuilder.stableOrder();
-    for (DepsContext depsContext : depsContexts) {
-      builder.addTransitive(
-          usePic ? depsContext.picTopLevelHeaderModules : depsContext.topLevelHeaderModules);
-    }
-    return builder.build();
+    return usePic ? picTopLevelHeaderModules : topLevelHeaderModules;
   }
 
   /**
    * @return all header modules in the transitive closure of {@code getTopLevelHeaderModules()}.
    */
   protected NestedSet<Artifact> getImpliedHeaderModules(boolean usePic) {
-    NestedSetBuilder<Artifact> builder = NestedSetBuilder.stableOrder();
-    for (DepsContext depsContext : depsContexts) {
-      builder.addTransitive(
-          usePic ? depsContext.picImpliedHeaderModules : depsContext.impliedHeaderModules);
-    }
-    return builder.build();
+    return usePic ? picImpliedHeaderModules : impliedHeaderModules;
   }
 
   /**
@@ -367,7 +325,17 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
         && Objects.equals(cppModuleMap, other.cppModuleMap)
         && Objects.equals(picHeaderModule, other.picHeaderModule)
         && commandLineContext.equals(other.commandLineContext)
-        && depsContexts.equals(other.depsContexts)
+        && Objects.equals(declaredIncludeDirs, other.declaredIncludeDirs)
+        && Objects.equals(declaredIncludeWarnDirs, other.declaredIncludeWarnDirs)
+        && Objects.equals(declaredIncludeSrcs, other.declaredIncludeSrcs)
+        && Objects.equals(directModuleMaps, other.directModuleMaps)
+        && Objects.equals(headerModuleSrcs, other.headerModuleSrcs)
+        && Objects.equals(impliedHeaderModules, other.impliedHeaderModules)
+        && Objects.equals(picImpliedHeaderModules, other.picImpliedHeaderModules)
+        && Objects.equals(topLevelHeaderModules, other.topLevelHeaderModules)
+        && Objects.equals(picTopLevelHeaderModules, other.picTopLevelHeaderModules)
+        && Objects.equals(transitiveModuleMaps, other.transitiveModuleMaps)
+        && Objects.equals(compilationPrerequisites, other.compilationPrerequisites)
         && (provideTransitiveModuleMaps == other.provideTransitiveModuleMaps)
         && (useHeaderModules == other.useHeaderModules);
   }
@@ -378,7 +346,17 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
         headerModule,
         picHeaderModule,
         commandLineContext,
-        depsContexts,
+        declaredIncludeDirs,
+        declaredIncludeWarnDirs,
+        declaredIncludeSrcs,
+        directModuleMaps,
+        headerModuleSrcs,
+        impliedHeaderModules,
+        picImpliedHeaderModules,
+        transitiveModuleMaps,
+        topLevelHeaderModules,
+        picTopLevelHeaderModules,
+        compilationPrerequisites,
         cppModuleMap,
         provideTransitiveModuleMaps,
         useHeaderModules);
@@ -389,26 +367,20 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
    * for {@link #getDeclaredIncludeDirs()} and {@link #getDeclaredIncludeWarnDirs()}.
    */
   public static CppCompilationContext disallowUndeclaredHeaders(CppCompilationContext context) {
-    ImmutableList.Builder<DepsContext> builder = ImmutableList.builder();
-    for (DepsContext depsContext : context.depsContexts) {
-      builder.add(
-          new DepsContext(
-              depsContext.compilationPrerequisiteStampFile,
-              NestedSetBuilder.<PathFragment>emptySet(Order.STABLE_ORDER),
-              NestedSetBuilder.<PathFragment>emptySet(Order.STABLE_ORDER),
-              depsContext.declaredIncludeSrcs,
-              depsContext.pregreppedHdrs,
-              depsContext.headerModuleSrcs,
-              depsContext.topLevelHeaderModules,
-              depsContext.picTopLevelHeaderModules,
-              depsContext.impliedHeaderModules,
-              depsContext.picImpliedHeaderModules,
-              depsContext.transitiveModuleMaps,
-              depsContext.directModuleMaps));
-    }
     return new CppCompilationContext(
         context.commandLineContext,
-        builder.build(),
+        context.compilationPrerequisites,
+        NestedSetBuilder.<PathFragment>emptySet(Order.STABLE_ORDER),
+        NestedSetBuilder.<PathFragment>emptySet(Order.STABLE_ORDER),
+        context.declaredIncludeSrcs,
+        context.pregreppedHdrs,
+        context.headerModuleSrcs,
+        context.topLevelHeaderModules,
+        context.picTopLevelHeaderModules,
+        context.impliedHeaderModules,
+        context.picImpliedHeaderModules,
+        context.transitiveModuleMaps,
+        context.directModuleMaps,
         context.cppModuleMap,
         context.headerModule,
         context.picHeaderModule,
@@ -443,15 +415,39 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
    */
   public static CppCompilationContext mergeForLipo(CppCompilationContext ownerContext,
       CppCompilationContext libContext) {
+    ImmutableSet.Builder<Artifact> prerequisites = ImmutableSet.builder();
+    prerequisites.addAll(ownerContext.compilationPrerequisites);
+    prerequisites.addAll(libContext.compilationPrerequisites);
     return new CppCompilationContext(
         libContext.commandLineContext,
-        ImmutableList.copyOf(Iterables.concat(ownerContext.depsContexts, libContext.depsContexts)),
+        prerequisites.build(),
+        mergeSets(ownerContext.declaredIncludeDirs, libContext.declaredIncludeDirs),
+        mergeSets(ownerContext.declaredIncludeWarnDirs, libContext.declaredIncludeWarnDirs),
+        mergeSets(ownerContext.declaredIncludeSrcs, libContext.declaredIncludeSrcs),
+        mergeSets(ownerContext.pregreppedHdrs, libContext.pregreppedHdrs),
+        mergeSets(ownerContext.headerModuleSrcs, libContext.headerModuleSrcs),
+        mergeSets(ownerContext.topLevelHeaderModules, libContext.topLevelHeaderModules),
+        mergeSets(ownerContext.picTopLevelHeaderModules, libContext.picTopLevelHeaderModules),
+        mergeSets(ownerContext.impliedHeaderModules, libContext.impliedHeaderModules),
+        mergeSets(ownerContext.picImpliedHeaderModules, libContext.picImpliedHeaderModules),
+        mergeSets(ownerContext.transitiveModuleMaps, libContext.transitiveModuleMaps),
+        mergeSets(ownerContext.directModuleMaps, libContext.directModuleMaps),
         libContext.cppModuleMap,
         libContext.headerModule,
         libContext.picHeaderModule,
         libContext.provideTransitiveModuleMaps,
         libContext.useHeaderModules);
   }
+  
+  /**
+   * Return a nested set containing all elements from {@code s1} and {@code s2}.
+   */
+  private static <T> NestedSet<T> mergeSets(NestedSet<T> s1, NestedSet<T> s2) {
+    NestedSetBuilder<T> builder = NestedSetBuilder.stableOrder();
+    builder.addTransitive(s1);
+    builder.addTransitive(s2);
+    return builder.build();
+  }
 
   /**
    * @return the C++ module map of the owner.
@@ -517,115 +513,6 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
   }
 
   /**
-   * The parts of the compilation context that defined the dependencies of
-   * actions of scheduling and inclusion validity checking.
-   */
-  @Immutable
-  private static class DepsContext {
-    private final Artifact compilationPrerequisiteStampFile;
-    private final NestedSet<PathFragment> declaredIncludeDirs;
-    private final NestedSet<PathFragment> declaredIncludeWarnDirs;
-    private final NestedSet<Artifact> declaredIncludeSrcs;
-    /**
-     * Module maps from direct dependencies.
-     */
-    private final NestedSet<Artifact> directModuleMaps;
-
-    /**
-     * All declared headers of the current module, if compiled as a header module.
-     */
-    private final NestedSet<Artifact> headerModuleSrcs;
-
-    /**
-     * All header modules in the transitive closure of {@code topLevelHeaderModules}.
-     */
-    private final NestedSet<Artifact> impliedHeaderModules;
-    private final NestedSet<Artifact> picImpliedHeaderModules;
-
-    private final NestedSet<Pair<Artifact, Artifact>> pregreppedHdrs;
-
-    /**
-     * All header modules in our transitive closure that are not in the transitive closure of
-     * another header module in our transitive closure.
-     */
-    private final NestedSet<Artifact> topLevelHeaderModules;
-    private final NestedSet<Artifact> picTopLevelHeaderModules;
-
-    /**
-     * The module maps from all targets the current target depends on transitively.
-     */
-    private final NestedSet<Artifact> transitiveModuleMaps;
-
-    DepsContext(
-        Artifact compilationPrerequisiteStampFile,
-        NestedSet<PathFragment> declaredIncludeDirs,
-        NestedSet<PathFragment> declaredIncludeWarnDirs,
-        NestedSet<Artifact> declaredIncludeSrcs,
-        NestedSet<Pair<Artifact, Artifact>> pregreppedHdrs,
-        NestedSet<Artifact> headerModuleSrcs,
-        NestedSet<Artifact> topLevelHeaderModules,
-        NestedSet<Artifact> picTopLevelHeaderModules,
-        NestedSet<Artifact> impliedHeaderModules,
-        NestedSet<Artifact> picImpliedHeaderModules,
-        NestedSet<Artifact> transitiveModuleMaps,
-        NestedSet<Artifact> directModuleMaps) {
-      this.compilationPrerequisiteStampFile = compilationPrerequisiteStampFile;
-      this.declaredIncludeDirs = declaredIncludeDirs;
-      this.declaredIncludeWarnDirs = declaredIncludeWarnDirs;
-      this.declaredIncludeSrcs = declaredIncludeSrcs;
-      this.directModuleMaps = directModuleMaps;
-      this.headerModuleSrcs = headerModuleSrcs;
-      this.impliedHeaderModules = impliedHeaderModules;
-      this.picImpliedHeaderModules = picImpliedHeaderModules;
-      this.pregreppedHdrs = pregreppedHdrs;
-      this.topLevelHeaderModules = topLevelHeaderModules;
-      this.picTopLevelHeaderModules = picTopLevelHeaderModules;
-      this.transitiveModuleMaps = transitiveModuleMaps;
-    }
-
-    @Override
-    public boolean equals(Object obj) {
-      if (obj == this) {
-        return true;
-      }
-      if (!(obj instanceof DepsContext)) {
-        return false;
-      }
-      DepsContext other = (DepsContext) obj;
-      return Objects.equals(
-              compilationPrerequisiteStampFile, other.compilationPrerequisiteStampFile)
-          && Objects.equals(declaredIncludeDirs, other.declaredIncludeDirs)
-          && Objects.equals(declaredIncludeWarnDirs, other.declaredIncludeWarnDirs)
-          && Objects.equals(declaredIncludeSrcs, other.declaredIncludeSrcs)
-          && Objects.equals(directModuleMaps, other.directModuleMaps)
-          && Objects.equals(headerModuleSrcs, other.headerModuleSrcs)
-          && Objects.equals(impliedHeaderModules, other.impliedHeaderModules)
-          && Objects.equals(picImpliedHeaderModules, other.picImpliedHeaderModules)
-          // TODO(bazel-team): add pregreppedHdrs?
-          && Objects.equals(topLevelHeaderModules, other.topLevelHeaderModules)
-          && Objects.equals(picTopLevelHeaderModules, other.picTopLevelHeaderModules)
-          && Objects.equals(transitiveModuleMaps, other.transitiveModuleMaps);
-    }
-
-    @Override
-    public int hashCode() {
-      return Objects.hash(
-          compilationPrerequisiteStampFile,
-          declaredIncludeDirs,
-          declaredIncludeWarnDirs,
-          declaredIncludeSrcs,
-          directModuleMaps,
-          headerModuleSrcs,
-          impliedHeaderModules,
-          picImpliedHeaderModules,
-          // pregreppedHdrs ?
-          transitiveModuleMaps,
-          topLevelHeaderModules,
-          picTopLevelHeaderModules);
-    }
-  }
-
-  /**
    * Builder class for {@link CppCompilationContext}.
    */
   public static class Builder {
@@ -967,20 +854,20 @@ public final class CppCompilationContext implements TransitiveInfoProvider {
               ImmutableList.copyOf(quoteIncludeDirs),
               ImmutableList.copyOf(systemIncludeDirs),
               ImmutableList.copyOf(defines)),
-          ImmutableList.of(
-              new DepsContext(
-                  prerequisiteStampFile,
-                  declaredIncludeDirs.build(),
-                  declaredIncludeWarnDirs.build(),
-                  declaredIncludeSrcs.build(),
-                  pregreppedHdrs.build(),
-                  headerModuleSrcs.build(),
-                  topLevelHeaderModules,
-                  picTopLevelHeaderModules,
-                  impliedHeaderModules,
-                  picImpliedHeaderModules,
-                  transitiveModuleMaps.build(),
-                  directModuleMaps.build())),
+          prerequisiteStampFile == null
+              ? ImmutableSet.<Artifact>of()
+              : ImmutableSet.of(prerequisiteStampFile),
+          declaredIncludeDirs.build(),
+          declaredIncludeWarnDirs.build(),
+          declaredIncludeSrcs.build(),
+          pregreppedHdrs.build(),
+          headerModuleSrcs.build(),
+          topLevelHeaderModules,
+          picTopLevelHeaderModules,
+          impliedHeaderModules,
+          picImpliedHeaderModules,
+          transitiveModuleMaps.build(),
+          directModuleMaps.build(),
           cppModuleMap,
           headerModule,
           picHeaderModule,