Add CommandLineItem interface.

This interface makes it clearer in the type system exactly how items that go into a CustomCommandLine are turned into strings.

It is a preparatory change to allow command line fingerprints to be more cheaply calculated, but it is valuable in itself from a code quality standpoint.

PiperOrigin-RevId: 183274022

17 files changed, 131 insertions, 71 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/BUILD b/src/main/java/com/google/devtools/build/lib/BUILD
index 82fc8d6ba6..745623bd4f 100644
--- a/src/main/java/com/google/devtools/build/lib/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/BUILD
@@ -468,6 +468,7 @@ java_library(
         ],
         exclude = [
             "analysis/BuildInfo.java",
+            "analysis/actions/CommandLineItem.java",
             "analysis/TransitiveInfoProvider.java",
             "analysis/config/BuildConfigurationOptionDetails.java",
             "rules/repository/CoreWorkspaceRules.java",
@@ -482,6 +483,7 @@ java_library(
     deps = [
         ":build-request-options",
         "//src/main/java/com/google/devtools/build/lib:base-util",
+        "//src/main/java/com/google/devtools/build/lib:commandline_item",
         "//src/main/java/com/google/devtools/build/lib:events",
         "//src/main/java/com/google/devtools/build/lib:exitcode-external",
         "//src/main/java/com/google/devtools/build/lib:io",
@@ -527,6 +529,11 @@ java_library(
 )
 
 java_library(
+    name = "commandline_item",
+    srcs = ["analysis/actions/CommandLineItem.java"],
+)
+
+java_library(
     name = "bazel-rules",
     srcs = glob(
         [
@@ -973,6 +980,7 @@ java_library(
         "rules/android/test_suite_property_name.txt",
     ],
     deps = [
+        ":commandline_item",
         "//src/main/java/com/google/devtools/build/lib:build-base",
         "//src/main/java/com/google/devtools/build/lib:events",
         "//src/main/java/com/google/devtools/build/lib:java-compilation",
diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionKeyContext.java b/src/main/java/com/google/devtools/build/lib/actions/ActionKeyContext.java
index 6ba29a7655..6378675147 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionKeyContext.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionKeyContext.java
@@ -20,22 +20,15 @@ import com.google.devtools.build.lib.util.Fingerprint;
 
 /** Contains state that aids in action key computation via {@link AbstractAction#computeKey}. */
 public class ActionKeyContext {
-  private static final class ArtifactNestedSetFingerprintCache
-      extends NestedSetFingerprintCache<Artifact> {
-    @Override
-    protected void addItemFingerprint(Fingerprint fingerprint, Artifact item) {
-      fingerprint.addPath(item.getExecPath());
-    }
-  }
 
-  private final ArtifactNestedSetFingerprintCache artifactNestedSetFingerprintCache =
-      new ArtifactNestedSetFingerprintCache();
+  private final NestedSetFingerprintCache nestedSetFingerprintCache =
+      new NestedSetFingerprintCache();
 
-  public void addArtifactsToFingerprint(Fingerprint fingerprint, NestedSet<Artifact> artifacts) {
-    artifactNestedSetFingerprintCache.addNestedSetToFingerprint(fingerprint, artifacts);
+  public <T> void addNestedSetToFingerprint(Fingerprint fingerprint, NestedSet<T> nestedSet) {
+    nestedSetFingerprintCache.addNestedSetToFingerprint(fingerprint, nestedSet);
   }
 
   public void clear() {
-    artifactNestedSetFingerprintCache.clear();
+    nestedSetFingerprintCache.clear();
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/actions/Artifact.java b/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
index e371ec1670..d45d16d587 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
@@ -27,6 +27,7 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Streams;
 import com.google.devtools.build.lib.actions.ActionAnalysisMetadata.MiddlemanType;
+import com.google.devtools.build.lib.analysis.actions.CommandLineItem;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.shell.ShellUtils;
@@ -115,7 +116,11 @@ import javax.annotation.Nullable;
           + "<a href='ctx.html#outputs'>ctx.outputs</a>."
 )
 public class Artifact
-    implements FileType.HasFileType, ActionInput, SkylarkValue, Comparable<Object> {
+    implements FileType.HasFileType,
+        ActionInput,
+        SkylarkValue,
+        Comparable<Object>,
+        CommandLineItem {
 
   /** Compares artifact according to their exec paths. Sorts null values first. */
   @SuppressWarnings("ReferenceEquality")  // "a == b" is an optimization
@@ -328,6 +333,11 @@ public class Artifact
     return getExecPath().filePathForFileTypeMatcher();
   }
 
+  @Override
+  public String expandToCommandLine() {
+    return getExecPathString();
+  }
+
   /**
    * Returns the artifact owner. May be null.
    */
diff --git a/src/main/java/com/google/devtools/build/lib/actions/BUILD b/src/main/java/com/google/devtools/build/lib/actions/BUILD
index 2c3f3abb0e..f936712ffb 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/actions/BUILD
@@ -17,6 +17,7 @@ java_library(
         "cache/*.java",
     ]),
     deps = [
+        "//src/main/java/com/google/devtools/build/lib:commandline_item",
         "//src/main/java/com/google/devtools/build/lib:events",
         "//src/main/java/com/google/devtools/build/lib:io",
         "//src/main/java/com/google/devtools/build/lib:packages-internal",
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/actions/CommandLineItem.java b/src/main/java/com/google/devtools/build/lib/analysis/actions/CommandLineItem.java
new file mode 100644
index 0000000000..c228226e19
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/analysis/actions/CommandLineItem.java
@@ -0,0 +1,43 @@
+// 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.actions;
+
+/** An interface for an object that customizes how it is expanded into a command line. */
+public interface CommandLineItem {
+  /**
+   * A map function that allows caller customization how a type is expanded into the command line.
+   */
+  interface MapFn<T> {
+    MapFn<Object> DEFAULT = CommandLineItem::expandToCommandLine;
+
+    String expandToCommandLine(T object);
+  }
+
+  /** Expands the object into the command line as a string. */
+  String expandToCommandLine();
+
+  /**
+   * The default method of expanding types.
+   *
+   * <p>If the object is a {@link CommandLineItem} we use its {@link
+   * CommandLineItem#expandToCommandLine} method, else we call {@link Object#toString()}.
+   */
+  static String expandToCommandLine(Object object) {
+    if (object instanceof CommandLineItem) {
+      return ((CommandLineItem) object).expandToCommandLine();
+    } else {
+      return object.toString();
+    }
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/actions/CustomCommandLine.java b/src/main/java/com/google/devtools/build/lib/analysis/actions/CustomCommandLine.java
index f86d5603fc..a987c99917 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/actions/CustomCommandLine.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/actions/CustomCommandLine.java
@@ -42,7 +42,6 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeSet;
-import java.util.function.Function;
 import javax.annotation.Nullable;
 
 /** A customizable, serializable class for building memory efficient command lines. */
@@ -77,10 +76,8 @@ public final class CustomCommandLine extends CommandLine {
     abstract void eval(ImmutableList.Builder<String> builder);
   }
 
-  // TODO(bazel-team): CustomMultiArgv is  going to be difficult to expose
-  // in Skylark. Maybe we can get rid of them by refactoring JavaCompileAction. It also
-  // raises immutability / serialization issues.
-  /** Custom Java code producing a List of String arguments. */
+  /** Deprecated. Do not use. TODO(b/64841073): Remove this */
+  @Deprecated
   public abstract static class CustomMultiArgv extends StandardArgvFragment {
 
     @Override
@@ -179,17 +176,17 @@ public final class CustomCommandLine extends CommandLine {
       }
 
       /** Each argument is mapped using the supplied map function */
-      public MappedVectorArg<T> mapped(Function<T, String> mapFn) {
+      public MappedVectorArg<T> mapped(CommandLineItem.MapFn<T> mapFn) {
         return new MappedVectorArg<>(this, mapFn);
       }
     }
 
     /** A vector arg that maps some type T to strings. */
-    public static class MappedVectorArg<T> extends VectorArg<String> {
+    static class MappedVectorArg<T> extends VectorArg<String> {
       private final Iterable<T> values;
-      private final Function<T, String> mapFn;
+      private final CommandLineItem.MapFn<T> mapFn;
 
-      private MappedVectorArg(SimpleVectorArg<T> other, Function<T, String> mapFn) {
+      private MappedVectorArg(SimpleVectorArg<T> other, CommandLineItem.MapFn<T> mapFn) {
         super(
             other.isNestedSet,
             other.isEmpty,
@@ -263,7 +260,7 @@ public final class CustomCommandLine extends CommandLine {
     @SuppressWarnings("unchecked")
     private static void push(List<Object> arguments, VectorArg<?> vectorArg) {
       final Iterable<?> values;
-      final Function<?, String> mapFn;
+      final CommandLineItem.MapFn<?> mapFn;
       if (vectorArg instanceof SimpleVectorArg) {
         values = ((SimpleVectorArg) vectorArg).values;
         mapFn = null;
@@ -342,14 +339,12 @@ public final class CustomCommandLine extends CommandLine {
             mutatedValues.add(arguments.get(argi++));
           }
         }
-        if (hasMapEach) {
-          Function<Object, String> mapFn = (Function<Object, String>) arguments.get(argi++);
-          for (int i = 0; i < count; ++i) {
-            mutatedValues.set(i, mapFn.apply(mutatedValues.get(i)));
-          }
-        }
+        CommandLineItem.MapFn<Object> mapFn =
+            hasMapEach
+                ? (CommandLineItem.MapFn<Object>) arguments.get(argi++)
+                : CommandLineItem.MapFn.DEFAULT;
         for (int i = 0; i < count; ++i) {
-          mutatedValues.set(i, valueToString(mutatedValues.get(i)));
+          mutatedValues.set(i, mapFn.expandToCommandLine(mutatedValues.get(i)));
         }
         if (hasFormatEach) {
           String formatStr = (String) arguments.get(argi++);
@@ -413,7 +408,7 @@ public final class CustomCommandLine extends CommandLine {
       String formatStr = (String) arguments.get(argi++);
       Object[] args = new Object[argCount];
       for (int i = 0; i < argCount; ++i) {
-        args[i] = valueToString(arguments.get(argi++));
+        args[i] = CommandLineItem.expandToCommandLine(arguments.get(argi++));
       }
       builder.add(String.format(formatStr, args));
       return argi;
@@ -433,7 +428,7 @@ public final class CustomCommandLine extends CommandLine {
     public int eval(List<Object> arguments, int argi, ImmutableList.Builder<String> builder) {
       String before = (String) arguments.get(argi++);
       Object arg = arguments.get(argi++);
-      builder.add(before + valueToString(arg));
+      builder.add(before + CommandLineItem.expandToCommandLine(arg));
       return argi;
     }
   }
@@ -1074,7 +1069,7 @@ public final class CustomCommandLine extends CommandLine {
           i = ((ArgvFragment) substitutedArg).eval(arguments, i, builder);
         }
       } else {
-        builder.add(valueToString(substitutedArg));
+        builder.add(CommandLineItem.expandToCommandLine(substitutedArg));
       }
     }
     return builder.build();
@@ -1082,7 +1077,7 @@ public final class CustomCommandLine extends CommandLine {
 
   private void evalSimpleVectorArg(Iterable<?> arg, ImmutableList.Builder<String> builder) {
     for (Object value : arg) {
-      builder.add(valueToString(value));
+      builder.add(CommandLineItem.expandToCommandLine(value));
     }
   }
 
@@ -1101,10 +1096,4 @@ public final class CustomCommandLine extends CommandLine {
       return arg;
     }
   }
-
-  private static String valueToString(Object value) {
-    return value instanceof Artifact
-        ? ((Artifact) value).getExecPath().getPathString()
-        : value.toString();
-  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkCustomCommandLine.java b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkCustomCommandLine.java
index 7c9d5e249e..e67ff39f09 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkCustomCommandLine.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/skylark/SkylarkCustomCommandLine.java
@@ -19,9 +19,9 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Interner;
 import com.google.common.collect.Lists;
-import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.actions.CommandLineExpansionException;
 import com.google.devtools.build.lib.analysis.actions.CommandLine;
+import com.google.devtools.build.lib.analysis.actions.CommandLineItem;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
 import com.google.devtools.build.lib.concurrent.BlazeInterners;
 import com.google.devtools.build.lib.events.EventHandler;
@@ -148,7 +148,7 @@ class SkylarkCustomCommandLine extends CommandLine {
         mutatedValues.addAll(resultAsList);
       }
       for (int i = 0; i < count; ++i) {
-        mutatedValues.set(i, valueToString(mutatedValues.get(i)));
+        mutatedValues.set(i, CommandLineItem.expandToCommandLine(mutatedValues.get(i)));
       }
       if (hasFormat) {
         String formatStr = (String) arguments.get(argi++);
@@ -291,7 +291,7 @@ class SkylarkCustomCommandLine extends CommandLine {
         BaseFunction mapFn = (BaseFunction) arguments.get(argi++);
         object = applyMapFn(mapFn, object, location, skylarkSemantics, eventHandler);
       }
-      object = valueToString(object);
+      object = CommandLineItem.expandToCommandLine(object);
       if (hasFormat) {
         String formatStr = (String) arguments.get(argi++);
         Formatter formatter = new Formatter(formatStr, location);
@@ -390,20 +390,12 @@ class SkylarkCustomCommandLine extends CommandLine {
       } else if (arg instanceof ScalarArg) {
         argi = ((ScalarArg) arg).eval(arguments, argi, result, skylarkSemantics, eventHandler);
       } else {
-        result.add(valueToString(arg));
+        result.add(CommandLineItem.expandToCommandLine(arg));
       }
     }
     return result.build();
   }
 
-  private static String valueToString(Object value) {
-    if (value instanceof Artifact) {
-      Artifact artifact = (Artifact) value;
-      return artifact.getExecPath().getPathString();
-    }
-    return value.toString();
-  }
-
   private static class Formatter {
     private final String formatStr;
     @Nullable private final Location location;
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/BUILD b/src/main/java/com/google/devtools/build/lib/cmdline/BUILD
index 2883d4277a..5ce3b757be 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/BUILD
@@ -18,6 +18,7 @@ java_library(
     visibility = ["//src:__subpackages__"],
     deps = [
         "//src/main/java/com/google/devtools/build/lib:base-util",
+        "//src/main/java/com/google/devtools/build/lib:commandline_item",
         "//src/main/java/com/google/devtools/build/lib:skylarkinterface",
         "//src/main/java/com/google/devtools/build/lib:util",
         "//src/main/java/com/google/devtools/build/lib/concurrent",
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/Label.java b/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
index 47a7d7bc17..2fbb2a4217 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
@@ -17,6 +17,7 @@ import com.google.common.base.Preconditions;
 import com.google.common.collect.ComparisonChain;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Interner;
+import com.google.devtools.build.lib.analysis.actions.CommandLineItem;
 import com.google.devtools.build.lib.cmdline.LabelValidator.BadLabelException;
 import com.google.devtools.build.lib.concurrent.BlazeInterners;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
@@ -53,7 +54,8 @@ import javax.annotation.Nullable;
 )
 @Immutable
 @ThreadSafe
-public final class Label implements Comparable<Label>, Serializable, SkylarkValue, SkyKey {
+public final class Label
+    implements Comparable<Label>, Serializable, SkylarkValue, SkyKey, CommandLineItem {
   public static final PathFragment EXTERNAL_PACKAGE_NAME = PathFragment.create("external");
   public static final PathFragment WORKSPACE_FILE_NAME = PathFragment.create("WORKSPACE");
   public static final String DEFAULT_REPOSITORY_DIRECTORY = "__main__";
@@ -573,6 +575,11 @@ public final class Label implements Comparable<Label>, Serializable, SkylarkValu
     printer.append(getCanonicalForm());
   }
 
+  @Override
+  public String expandToCommandLine() {
+    return getCanonicalForm();
+  }
+
   /**
    * Specialization of {@link Arrays#hashCode()} that does not require constructing a 2-element
    * array.
diff --git a/src/main/java/com/google/devtools/build/lib/collect/nestedset/BUILD b/src/main/java/com/google/devtools/build/lib/collect/nestedset/BUILD
index 4de005985c..8e3b861b9d 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/nestedset/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/collect/nestedset/BUILD
@@ -40,6 +40,8 @@ java_library(
     srcs = ["NestedSetFingerprintCache.java"],
     deps = [
         ":nestedset",
+        "//src/main/java/com/google/devtools/build/lib:commandline_item",
         "//src/main/java/com/google/devtools/build/lib:util",
+        "//third_party:guava",
     ],
 )
diff --git a/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetFingerprintCache.java b/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetFingerprintCache.java
index 8e56d5548a..c19b67e0cd 100644
--- a/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetFingerprintCache.java
+++ b/src/main/java/com/google/devtools/build/lib/collect/nestedset/NestedSetFingerprintCache.java
@@ -14,16 +14,18 @@
 
 package com.google.devtools.build.lib.collect.nestedset;
 
+import com.google.common.annotations.VisibleForTesting;
+import com.google.devtools.build.lib.analysis.actions.CommandLineItem;
 import com.google.devtools.build.lib.util.Fingerprint;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
 /** Computes fingerprints for nested sets, reusing sub-computations from children. */
-public abstract class NestedSetFingerprintCache<T> {
+public class NestedSetFingerprintCache {
   private static final byte[] EMPTY_SET_BYTES = new byte[] {};
   private Map<Object, byte[]> fingerprints = createMap();
 
-  public void addNestedSetToFingerprint(Fingerprint fingerprint, NestedSet<T> nestedSet) {
+  public <T> void addNestedSetToFingerprint(Fingerprint fingerprint, NestedSet<T> nestedSet) {
     fingerprint.addInt(nestedSet.getOrder().ordinal());
     Object children = nestedSet.rawChildren();
     byte[] bytes = getBytes(children);
@@ -34,6 +36,7 @@ public abstract class NestedSetFingerprintCache<T> {
     fingerprints = createMap();
   }
 
+  @SuppressWarnings("unchecked")
   private byte[] getBytes(Object children) {
     byte[] bytes = fingerprints.get(children);
     if (bytes == null) {
@@ -43,7 +46,7 @@ public abstract class NestedSetFingerprintCache<T> {
           if (child instanceof Object[]) {
             fingerprint.addBytes(getBytes(child));
           } else {
-            addItemFingerprint(fingerprint, cast(child));
+            addToFingerprint(fingerprint, child);
           }
         }
         bytes = fingerprint.digestAndReset();
@@ -55,7 +58,7 @@ public abstract class NestedSetFingerprintCache<T> {
       } else if (children != NestedSet.EMPTY_CHILDREN) {
         // Single item
         Fingerprint fingerprint = new Fingerprint();
-        addItemFingerprint(fingerprint, cast(children));
+        addToFingerprint(fingerprint, children);
         bytes = fingerprint.digestAndReset();
       } else {
         // Empty nested set
@@ -65,14 +68,12 @@ public abstract class NestedSetFingerprintCache<T> {
     return bytes;
   }
 
-  @SuppressWarnings("unchecked")
-  private T cast(Object item) {
-    return (T) item;
+  @VisibleForTesting
+  <T> void addToFingerprint(Fingerprint fingerprint, T object) {
+    fingerprint.addString(CommandLineItem.expandToCommandLine(object));
   }
 
   private static Map<Object, byte[]> createMap() {
     return new ConcurrentHashMap<>();
   }
-
-  protected abstract void addItemFingerprint(Fingerprint fingerprint, T item);
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourceMergingActionBuilder.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourceMergingActionBuilder.java
index 14635e626a..6dbab850f3 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourceMergingActionBuilder.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourceMergingActionBuilder.java
@@ -166,7 +166,8 @@ public class AndroidResourceMergingActionBuilder {
     NestedSetBuilder<Artifact> inputs = createInputsForBuilder(builder);
 
     Preconditions.checkNotNull(primary);
-    builder.add("--primaryData", RESOURCE_CONTAINER_TO_ARG_FOR_COMPILED.apply(primary));
+    builder.add(
+        "--primaryData", RESOURCE_CONTAINER_TO_ARG_FOR_COMPILED.expandToCommandLine(primary));
     inputs.addAll(primary.getArtifacts());
     inputs.add(primary.getCompiledSymbols());
 
@@ -202,7 +203,7 @@ public class AndroidResourceMergingActionBuilder {
     NestedSetBuilder<Artifact> inputs = createInputsForBuilder(builder);
 
     Preconditions.checkNotNull(primary);
-    builder.add("--primaryData", RESOURCE_CONTAINER_TO_ARG.apply(primary));
+    builder.add("--primaryData", RESOURCE_CONTAINER_TO_ARG.expandToCommandLine(primary));
     inputs.addAll(primary.getArtifacts());
     inputs.add(primary.getSymbols());
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourcesProcessorBuilder.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourcesProcessorBuilder.java
index 80e80ec85e..275af451a8 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourcesProcessorBuilder.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourcesProcessorBuilder.java
@@ -441,7 +441,7 @@ public class AndroidResourcesProcessorBuilder {
       List<Artifact> outs, NestedSetBuilder<Artifact> inputs, Builder builder) {
 
     // Add data
-    builder.add("--primaryData", RESOURCE_CONTAINER_TO_ARG.apply(primary));
+    builder.add("--primaryData", RESOURCE_CONTAINER_TO_ARG.expandToCommandLine(primary));
     inputs.addAll(primary.getArtifacts());
     inputs.add(primary.getManifest());
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/ResourceContainerConverter.java b/src/main/java/com/google/devtools/build/lib/rules/android/ResourceContainerConverter.java
index bb1ddc5510..fd9ba71a94 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/ResourceContainerConverter.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/ResourceContainerConverter.java
@@ -20,6 +20,7 @@ import com.google.common.base.Joiner;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterators;
+import com.google.devtools.build.lib.analysis.actions.CommandLineItem;
 import com.google.devtools.build.lib.analysis.actions.CustomCommandLine;
 import com.google.devtools.build.lib.analysis.actions.CustomCommandLine.VectorArg;
 import com.google.devtools.build.lib.rules.android.ResourceContainer.ResourceType;
@@ -36,7 +37,7 @@ public class ResourceContainerConverter {
     return new Builder();
   }
 
-  interface ToArg extends Function<ResourceContainer, String> {
+  interface ToArg extends CommandLineItem.MapFn<ResourceContainer> {
 
     String listSeparator();
   }
@@ -128,7 +129,7 @@ public class ResourceContainerConverter {
 
       return new ToArg() {
         @Override
-        public String apply(ResourceContainer container) {
+        public String expandToCommandLine(ResourceContainer container) {
           ImmutableList.Builder<String> cmdPieces = ImmutableList.builder();
           if (includeResourceRoots) {
             cmdPieces.add(convertRoots(container, ResourceType.RESOURCES));
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java
index 284be8cd10..7f520dcaaa 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppCompileAction.java
@@ -1081,11 +1081,11 @@ public class CppCompileAction extends AbstractAction
      */
     f.addPaths(context.getDeclaredIncludeDirs());
     f.addPaths(context.getDeclaredIncludeWarnDirs());
-    actionKeyContext.addArtifactsToFingerprint(f, context.getDeclaredIncludeSrcs());
+    actionKeyContext.addNestedSetToFingerprint(f, context.getDeclaredIncludeSrcs());
     f.addInt(0);  // mark the boundary between input types
-    actionKeyContext.addArtifactsToFingerprint(f, getMandatoryInputs());
+    actionKeyContext.addNestedSetToFingerprint(f, getMandatoryInputs());
     f.addInt(0);
-    actionKeyContext.addArtifactsToFingerprint(f, prunableInputs);
+    actionKeyContext.addNestedSetToFingerprint(f, prunableInputs);
     return f.hexDigestAndReset();
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/vfs/BUILD b/src/main/java/com/google/devtools/build/lib/vfs/BUILD
index f6d2eb427b..5eaf3116e2 100644
--- a/src/main/java/com/google/devtools/build/lib/vfs/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/vfs/BUILD
@@ -19,6 +19,7 @@ java_library(
     srcs = PATH_FRAGMENT_SOURCES,
     deps = [
         "//src/main/java/com/google/devtools/build/lib:base-util",
+        "//src/main/java/com/google/devtools/build/lib:commandline_item",
         "//src/main/java/com/google/devtools/build/lib:filetype",
         "//src/main/java/com/google/devtools/build/lib:os_util",
         "//src/main/java/com/google/devtools/build/lib:skylarkinterface",
diff --git a/src/main/java/com/google/devtools/build/lib/vfs/PathFragment.java b/src/main/java/com/google/devtools/build/lib/vfs/PathFragment.java
index 9db3aa3ada..572042a7d7 100644
--- a/src/main/java/com/google/devtools/build/lib/vfs/PathFragment.java
+++ b/src/main/java/com/google/devtools/build/lib/vfs/PathFragment.java
@@ -15,6 +15,7 @@ package com.google.devtools.build.lib.vfs;
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.analysis.actions.CommandLineItem;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
 import com.google.devtools.build.lib.skyframe.serialization.ObjectCodec;
@@ -52,7 +53,11 @@ import java.util.Set;
 @javax.annotation.concurrent.Immutable
 @ThreadSafe
 public abstract class PathFragment
-    implements Comparable<PathFragment>, Serializable, SkylarkPrintable, FileType.HasFileType {
+    implements Comparable<PathFragment>,
+        Serializable,
+        SkylarkPrintable,
+        FileType.HasFileType,
+        CommandLineItem {
   private static final Helper HELPER =
       OS.getCurrent() == OS.WINDOWS ? WindowsPathFragment.HELPER : UnixPathFragment.HELPER;
 
@@ -762,6 +767,11 @@ public abstract class PathFragment
     return getBaseName();
   }
 
+  @Override
+  public String expandToCommandLine() {
+    return getPathString();
+  }
+
   private static class PathFragmentCodec implements ObjectCodec<PathFragment> {
     private final ObjectCodec<String> stringCodec = StringCodecs.asciiOptimized();