Redo FileType to reduce generated garbage.

* Change FileType to no longer assume it operates on just the base name (it can now be given a full path).

* Move the responsibility to specific classes (Artifact, Path, PathFragment) to decide how they want to offer up a string that includes the file name.

* Flip the order in which users are expected to check Artifact type, from FileType#matches(Artifact) to Artifact#isFileType(FileType). This looks natural and should encourage developers to use efficient file type checking methods.

* Change CppCompileAction to use the new API.

RELNOTES: None
PiperOrigin-RevId: 179903239

11 files changed, 309 insertions, 227 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/BUILD b/src/main/java/com/google/devtools/build/lib/BUILD
index 499c3b5114..c48d1efc27 100644
--- a/src/main/java/com/google/devtools/build/lib/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/BUILD
@@ -97,11 +97,10 @@ java_library(
 java_library(
     name = "base-util",
     srcs = [
-        "util/StringCanonicalizer.java",
         "util/VarInt.java",
     ],
+    exports = [":string_util"],
     deps = [
-        "//src/main/java/com/google/devtools/build/lib/concurrent",
         "//third_party:guava",
     ],
 )
@@ -161,19 +160,24 @@ java_library(
             "util/BlazeClock.java",
             "util/Clock.java",
             "util/ExitCode.java",
+            "util/FileType.java",
+            "util/FileTypeSet.java",
             "util/JavaClock.java",
             "util/OS.java",
             "util/ProcessUtils.java",
             "util/SingleLineFormatter.java",
             "util/StringCanonicalizer.java",
             "util/StringTrie.java",
+            "util/StringUtil.java",
             "util/VarInt.java",
         ],
     ),
     exports = [
         "//src/main/java/com/google/devtools/build/lib:base-util",
         "//src/main/java/com/google/devtools/build/lib:exitcode-external",
+        "//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:string_util",
         "//src/main/java/com/google/devtools/build/lib/clock",
         "//src/main/java/com/google/devtools/build/lib/collect",
     ],
@@ -196,6 +200,31 @@ java_library(
 )
 
 java_library(
+    name = "filetype",
+    srcs = [
+        "util/FileType.java",
+        "util/FileTypeSet.java",
+    ],
+    deps = [
+        ":string_util",
+        "//third_party:guava",
+        "//third_party:jsr305",
+    ],
+)
+
+java_library(
+    name = "string_util",
+    srcs = [
+        "util/StringCanonicalizer.java",
+        "util/StringUtil.java",
+    ],
+    deps = [
+        "//src/main/java/com/google/devtools/build/lib/concurrent",
+        "//third_party:guava",
+    ],
+)
+
+java_library(
     name = "exitcode-external",
     srcs = [
         "util/ExitCode.java",
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 e47d0e3bd6..7468de1759 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
@@ -38,6 +38,7 @@ import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 import com.google.devtools.build.lib.syntax.EvalUtils;
 import com.google.devtools.build.lib.syntax.EvalUtils.ComparisonException;
 import com.google.devtools.build.lib.util.FileType;
+import com.google.devtools.build.lib.util.FileTypeSet;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import java.util.ArrayList;
@@ -48,67 +49,73 @@ import java.util.Objects;
 import javax.annotation.Nullable;
 
 /**
- * An Artifact represents a file used by the build system, whether it's a source
- * file or a derived (output) file. Not all Artifacts have a corresponding
- * FileTarget object in the <code>build.lib.packages</code> API: for example,
- * low-level intermediaries internal to a given rule, such as a Java class files
- * or C++ object files. However all FileTargets have a corresponding Artifact.
+ * An Artifact represents a file used by the build system, whether it's a source file or a derived
+ * (output) file. Not all Artifacts have a corresponding FileTarget object in the <code>
+ * build.lib.packages</code> API: for example, low-level intermediaries internal to a given rule,
+ * such as a Java class files or C++ object files. However all FileTargets have a corresponding
+ * Artifact.
  *
- * <p>In any given call to SkyframeExecutor#buildArtifacts(), no two Artifacts in the
- * action graph may refer to the same path.
+ * <p>In any given call to SkyframeExecutor#buildArtifacts(), no two Artifacts in the action graph
+ * may refer to the same path.
+ *
+ * <p>Artifacts generally fall into two classifications, source and derived, but there exist a few
+ * other cases that are fuzzy and difficult to classify. The following cases exist:
  *
- * <p>Artifacts generally fall into two classifications, source and derived, but
- * there exist a few other cases that are fuzzy and difficult to classify. The
- * following cases exist:
  * <ul>
- * <li>Well-formed source Artifacts will have null generating Actions and a root
- * that is orthogonal to execRoot. (With the root coming from the package path.)
- * <li>Well-formed derived Artifacts will have non-null generating Actions, and
- * a root that is below execRoot.
- * <li>Symlinked include source Artifacts under the output/include tree will
- * appear to be derived artifacts with null generating Actions.
- * <li>Some derived Artifacts, mostly in the genfiles tree and mostly discovered
- * during include validation, will also have null generating Actions.
+ *   <li>Well-formed source Artifacts will have null generating Actions and a root that is
+ *       orthogonal to execRoot. (With the root coming from the package path.)
+ *   <li>Well-formed derived Artifacts will have non-null generating Actions, and a root that is
+ *       below execRoot.
+ *   <li>Symlinked include source Artifacts under the output/include tree will appear to be derived
+ *       artifacts with null generating Actions.
+ *   <li>Some derived Artifacts, mostly in the genfiles tree and mostly discovered during include
+ *       validation, will also have null generating Actions.
  * </ul>
  *
- * In the usual case, an Artifact represents a single file. However, an Artifact may
- * also represent the following:
+ * In the usual case, an Artifact represents a single file. However, an Artifact may also represent
+ * the following:
+ *
  * <ul>
- * <li>A TreeArtifact, which is a directory containing a tree of unknown {@link Artifact}s.
- * In the future, Actions will be able to examine these files as inputs and declare them as outputs
- * at execution time, but this is not yet implemented. This is used for Actions where
- * the inputs and/or outputs might not be discoverable except during Action execution.
- * <li>A directory of unknown contents, but not a TreeArtifact.
- * This is a legacy facility and should not be used by any new rule implementations.
- * In particular, the file system cache integrity checks fail for directories.
- * <li>An 'aggregating middleman' special Artifact, which may be expanded using a
- * {@link ArtifactExpander} at Action execution time. This is used by a handful of rules to save
- * memory.
- * <li>A 'constant metadata' special Artifact. These represent real files, changes to which are
- * ignored by the build system. They are useful for files which change frequently but do not affect
- * the result of a build, such as timestamp files.
- * <li>A 'Fileset' special Artifact. This is a legacy type of Artifact and should not be used
- * by new rule implementations.
+ *   <li>A TreeArtifact, which is a directory containing a tree of unknown {@link Artifact}s. In the
+ *       future, Actions will be able to examine these files as inputs and declare them as outputs
+ *       at execution time, but this is not yet implemented. This is used for Actions where the
+ *       inputs and/or outputs might not be discoverable except during Action execution.
+ *   <li>A directory of unknown contents, but not a TreeArtifact. This is a legacy facility and
+ *       should not be used by any new rule implementations. In particular, the file system cache
+ *       integrity checks fail for directories.
+ *   <li>An 'aggregating middleman' special Artifact, which may be expanded using a {@link
+ *       ArtifactExpander} at Action execution time. This is used by a handful of rules to save
+ *       memory.
+ *   <li>A 'constant metadata' special Artifact. These represent real files, changes to which are
+ *       ignored by the build system. They are useful for files which change frequently but do not
+ *       affect the result of a build, such as timestamp files.
+ *   <li>A 'Fileset' special Artifact. This is a legacy type of Artifact and should not be used by
+ *       new rule implementations.
  * </ul>
- * <p>This class is "theoretically" final; it should not be subclassed except by
- * {@link SpecialArtifact}.
+ *
+ * <p>This class is "theoretically" final; it should not be subclassed except by {@link
+ * SpecialArtifact}.
  */
 @Immutable
-@SkylarkModule(name = "File",
-    category = SkylarkModuleCategory.BUILTIN,
-    doc = "<p>This type represents a file or directory used by the build system. It can be "
-        + "either a source file or a derived file produced by a rule.</p>"
-        + "<p>The File constructor is private, so you cannot call it directly to create new "
-        + "Files. If you have a Skylark rule that needs to create a new File, you have two options:"
-        + "<ul>"
-        + "<li>use <a href='actions.html#declare_file'>ctx.actions.declare_file</a> "
-        + "or <a href='actions.html#declare_directory'>ctx.actions.declare_directory</a> to "
-        + "declare a new file in the rule implementation.</li>"
-        + "<li>add the label to the attrs (if it's an input) or the outputs (if it's an output)."
-        + " Then you can access the File through the rule's "
-        + "<a href='ctx.html#outputs'>ctx.outputs</a>.")
+@SkylarkModule(
+  name = "File",
+  category = SkylarkModuleCategory.BUILTIN,
+  doc =
+      "<p>This type represents a file or directory used by the build system. It can be "
+          + "either a source file or a derived file produced by a rule.</p>"
+          + "<p>The File constructor is private, so you cannot call it directly to create new "
+          + "Files. If you have a Skylark rule that needs to create a new File, "
+          + "you have two options:"
+          + "<ul>"
+          + "<li>use <a href='actions.html#declare_file'>ctx.actions.declare_file</a> "
+          + "or <a href='actions.html#declare_directory'>ctx.actions.declare_directory</a> to "
+          + "declare a new file in the rule implementation.</li>"
+          + "<li>add the label to the attrs (if it's an input) or the outputs (if it's an output)."
+          + " Then you can access the File through the rule's "
+          + "<a href='ctx.html#outputs'>ctx.outputs</a>."
+)
 public class Artifact
-    implements FileType.HasFilename, ActionInput, SkylarkValue, Comparable<Object> {
+    implements FileType.HasFileType, ActionInput, SkylarkValue, Comparable<Object> {
 
   /** Compares artifact according to their exec paths. Sorts null values first. */
   @SuppressWarnings("ReferenceEquality")  // "a == b" is an optimization
@@ -281,7 +288,6 @@ public class Artifact
   /**
    * Returns the base file name of this artifact, similar to basename(1).
    */
-  @Override
   @SkylarkCallable(name = "basename", structField = true,
       doc = "The base name of this file. This is the name of the file inside the directory.")
   public final String getFilename() {
@@ -294,6 +300,27 @@ public class Artifact
   }
 
   /**
+   * Checks whether this artifact is of the supplied file type.
+   *
+   * <p>Prefer this method to pulling out strings from the Artifact and passing to {@link
+   * FileType#matches(String)} manually. This method has been optimized to generate a minimum of
+   * garbage.
+   */
+  public boolean isFileType(FileType fileType) {
+    return fileType.matches(this);
+  }
+
+  /** Checks whether this artifact is any of the supplied file types. */
+  public boolean isAnyFileType(FileTypeSet fileTypeSet) {
+    return fileTypeSet.matches(filePathForFileTypeMatcher());
+  }
+
+  @Override
+  public String filePathForFileTypeMatcher() {
+    return getExecPath().filePathForFileTypeMatcher();
+  }
+
+  /**
    * Returns the artifact owner. May be null.
    */
   @Nullable public final Label getOwner() {
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/configuredtargets/FileConfiguredTarget.java b/src/main/java/com/google/devtools/build/lib/analysis/configuredtargets/FileConfiguredTarget.java
index 4a009fe326..30e9f2f203 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/configuredtargets/FileConfiguredTarget.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/configuredtargets/FileConfiguredTarget.java
@@ -35,11 +35,11 @@ import com.google.devtools.build.lib.packages.Provider;
 import com.google.devtools.build.lib.util.FileType;
 
 /**
- * A ConfiguredTarget for a source FileTarget.  (Generated files use a
- * subclass, OutputFileConfiguredTarget.)
+ * A ConfiguredTarget for a source FileTarget. (Generated files use a subclass,
+ * OutputFileConfiguredTarget.)
  */
 public abstract class FileConfiguredTarget extends AbstractConfiguredTarget
-    implements FileType.HasFilename, LicensesProvider {
+    implements FileType.HasFileType, LicensesProvider {
 
   private final Artifact artifact;
   private final TransitiveInfoProviderMap providers;
@@ -78,12 +78,16 @@ public abstract class FileConfiguredTarget extends AbstractConfiguredTarget
   /**
    *  Returns the file name of this file target.
    */
-  @Override
   public String getFilename() {
     return getTarget().getFilename();
   }
 
   @Override
+  public String filePathForFileTypeMatcher() {
+    return getFilename();
+  }
+
+  @Override
   public <P extends TransitiveInfoProvider> P getProvider(Class<P> provider) {
     AnalysisUtils.checkProvider(provider);
     return providers.getProvider(provider);
diff --git a/src/main/java/com/google/devtools/build/lib/packages/FileTarget.java b/src/main/java/com/google/devtools/build/lib/packages/FileTarget.java
index a488eff5bc..51cdb1afa0 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/FileTarget.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/FileTarget.java
@@ -17,14 +17,14 @@ package com.google.devtools.build.lib.packages;
 import com.google.common.base.Preconditions;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.packages.License.DistributionType;
-import com.google.devtools.build.lib.util.FileType.HasFilename;
+import com.google.devtools.build.lib.util.FileType;
 import java.util.Set;
 
 /**
- * Common superclass for InputFile and OutputFile which provides implementation
- * for the file operations in common.
+ * Common superclass for InputFile and OutputFile which provides implementation for the file
+ * operations in common.
  */
-public abstract class FileTarget implements Target, HasFilename {
+public abstract class FileTarget implements Target, FileType.HasFileType {
   protected final Package pkg;
   protected final Label label;
 
@@ -37,7 +37,6 @@ public abstract class FileTarget implements Target, HasFilename {
     this.label = label;
   }
 
-  @Override
   public String getFilename() {
     return label.getName();
   }
@@ -58,6 +57,11 @@ public abstract class FileTarget implements Target, HasFilename {
   }
 
   @Override
+  public String filePathForFileTypeMatcher() {
+    return getFilename();
+  }
+
+  @Override
   public String toString() {
     return getTargetKind() + "(" + getLabel() + ")"; // Just for debugging
   }
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 4a97d11181..4f7bce06a0 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
@@ -381,7 +381,7 @@ public class CppCompileAction extends AbstractAction
     // discarded as orphans.
     // This is strictly better than marking all transitive modules as inputs, which would also
     // effectively disable orphan detection for .pcm files.
-    if (CppFileTypes.CPP_MODULE.matches(outputFile.getFilename())) {
+    if (outputFile.isFileType(CppFileTypes.CPP_MODULE)) {
       return ImmutableSet.of(outputFile);
     }
     return super.getMandatoryOutputs();
@@ -447,7 +447,7 @@ public class CppCompileAction extends AbstractAction
 
     if (shouldPruneModules) {
       Set<Artifact> initialResultSet = Sets.newLinkedHashSet(initialResult);
-      if (CppFileTypes.CPP_MODULE.matches(sourceFile.getFilename())) {
+      if (sourceFile.isFileType(CppFileTypes.CPP_MODULE)) {
         usedModules = ImmutableSet.of(sourceFile);
         initialResultSet.add(sourceFile);
       } else {
@@ -485,7 +485,7 @@ public class CppCompileAction extends AbstractAction
           value, "Owner %s of %s not in graph %s", artifact.getArtifactOwner(), artifact, skyKey);
       // We can get the generating action here because #canRemoveAfterExecution is overridden.
       Preconditions.checkState(
-          CppFileTypes.CPP_MODULE.matches(artifact.getFilename()),
+          artifact.isFileType(CppFileTypes.CPP_MODULE),
           "Non-module? %s (%s %s)",
           artifact,
           this,
@@ -493,7 +493,7 @@ public class CppCompileAction extends AbstractAction
       CppCompileAction action =
           (CppCompileAction) value.getGeneratingActionDangerousReadJavadoc(artifact);
       for (Artifact input : action.getInputs()) {
-        if (CppFileTypes.CPP_MODULE.matches(input.getFilename())) {
+        if (input.isFileType(CppFileTypes.CPP_MODULE)) {
           additionalModules.add(input);
         }
       }
@@ -631,7 +631,7 @@ public class CppCompileAction extends AbstractAction
 
   @Override
   public Artifact getMainIncludeScannerSource() {
-    return CppFileTypes.CPP_MODULE_MAP.matches(getSourceFile().getPath())
+    return getSourceFile().isFileType(CppFileTypes.CPP_MODULE_MAP)
         ? Iterables.getFirst(context.getHeaderModuleSrcs(), null)
         : getSourceFile();
   }
@@ -639,7 +639,7 @@ public class CppCompileAction extends AbstractAction
   @Override
   public Collection<Artifact> getIncludeScannerSources() {
     NestedSetBuilder<Artifact> builder = NestedSetBuilder.stableOrder();
-    if (CppFileTypes.CPP_MODULE_MAP.matches(getSourceFile().getPath())) {
+    if (getSourceFile().isFileType(CppFileTypes.CPP_MODULE_MAP)) {
       // If this is an action that compiles the header module itself, the source we build is the
       // module map, and we need to include-scan all headers that are referenced in the module map.
       // We need to do include scanning as long as we want to support building code bases that are
@@ -702,7 +702,7 @@ public class CppCompileAction extends AbstractAction
   public boolean canRemoveAfterExecution() {
     // Module-generating actions are needed because the action may be retrieved in
     // #discoverInputsStage2.
-    return !CppFileTypes.CPP_MODULE.matches(getPrimaryOutput().getFilename());
+    return !getPrimaryOutput().isFileType(CppFileTypes.CPP_MODULE);
   }
 
   @Override
@@ -962,7 +962,7 @@ public class CppCompileAction extends AbstractAction
       Iterable<Artifact> potentialModules) {
     ImmutableList.Builder<String> usedModulePaths = ImmutableList.builder();
     for (Artifact input : potentialModules) {
-      if (CppFileTypes.CPP_MODULE.matches(input.getFilename())) {
+      if (input.isFileType(CppFileTypes.CPP_MODULE)) {
         usedModulePaths.add(input.getExecPathString());
       }
     }
@@ -1242,7 +1242,7 @@ public class CppCompileAction extends AbstractAction
    */
   private void ensureCoverageNotesFilesExist() throws ActionExecutionException {
     for (Artifact output : getOutputs()) {
-      if (CppFileTypes.COVERAGE_NOTES.matches(output.getFilename()) // ".gcno"
+      if (output.isFileType(CppFileTypes.COVERAGE_NOTES) // ".gcno"
           && !output.getPath().exists()) {
         try {
           FileSystemUtils.createEmptyFile(output.getPath());
@@ -1281,8 +1281,8 @@ public class CppCompileAction extends AbstractAction
 
   @Override
   public String getMnemonic() {
-    if (CppFileTypes.OBJC_SOURCE.matches(sourceFile.getExecPath())
-        || CppFileTypes.OBJCPP_SOURCE.matches(sourceFile.getExecPath())) {
+    if (sourceFile.isFileType(CppFileTypes.OBJC_SOURCE)
+        || sourceFile.isFileType(CppFileTypes.OBJCPP_SOURCE)) {
       return "ObjcCompile";
     } else {
       return "CppCompile";
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppFileTypes.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppFileTypes.java
index c63f7d8e00..0c7fa7d795 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppFileTypes.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppFileTypes.java
@@ -42,44 +42,52 @@ public final class CppFileTypes {
   public static final FileType CPP_TEXTUAL_INCLUDE = FileType.of(".inc");
 
   public static final FileType PIC_PREPROCESSED_C = FileType.of(".pic.i");
-  public static final FileType PREPROCESSED_C = new FileType() {
-      final String ext = ".i";
-      @Override
-      public boolean apply(String filename) {
-        return filename.endsWith(ext) && !PIC_PREPROCESSED_C.matches(filename);
-      }
-      @Override
-      public List<String> getExtensions() {
-        return ImmutableList.of(ext);
-      }
-    };
+  public static final FileType PREPROCESSED_C =
+      new FileType() {
+        final String ext = ".i";
+
+        @Override
+        public boolean apply(String path) {
+          return path.endsWith(ext) && !PIC_PREPROCESSED_C.matches(path);
+        }
+
+        @Override
+        public List<String> getExtensions() {
+          return ImmutableList.of(ext);
+        }
+      };
   public static final FileType PIC_PREPROCESSED_CPP = FileType.of(".pic.ii");
-  public static final FileType PREPROCESSED_CPP = new FileType() {
-      final String ext = ".ii";
-      @Override
-      public boolean apply(String filename) {
-        return filename.endsWith(ext) && !PIC_PREPROCESSED_CPP.matches(filename);
-      }
-      @Override
-      public List<String> getExtensions() {
-        return ImmutableList.of(ext);
-      }
-    };
+  public static final FileType PREPROCESSED_CPP =
+      new FileType() {
+        final String ext = ".ii";
+
+        @Override
+        public boolean apply(String path) {
+          return path.endsWith(ext) && !PIC_PREPROCESSED_CPP.matches(path);
+        }
+
+        @Override
+        public List<String> getExtensions() {
+          return ImmutableList.of(ext);
+        }
+      };
 
   public static final FileType ASSEMBLER_WITH_C_PREPROCESSOR = FileType.of(".S");
   public static final FileType PIC_ASSEMBLER = FileType.of(".pic.s");
-  public static final FileType ASSEMBLER = new FileType() {
-      final String ext = ".s";
-      @Override
-      public boolean apply(String filename) {
-        return (filename.endsWith(ext) && !PIC_ASSEMBLER.matches(filename))
-               || filename.endsWith(".asm");
-      }
-      @Override
-      public List<String> getExtensions() {
-        return ImmutableList.of(ext, ".asm");
-      }
-    };
+  public static final FileType ASSEMBLER =
+      new FileType() {
+        final String ext = ".s";
+
+        @Override
+        public boolean apply(String path) {
+          return (path.endsWith(ext) && !PIC_ASSEMBLER.matches(path)) || path.endsWith(".asm");
+        }
+
+        @Override
+        public List<String> getExtensions() {
+          return ImmutableList.of(ext, ".asm");
+        }
+      };
 
   public static final FileType PIC_ARCHIVE = FileType.of(".pic.a");
   public static final FileType ARCHIVE =
@@ -87,9 +95,9 @@ public final class CppFileTypes {
         final List<String> extensions = ImmutableList.of(".a", ".lib");
 
         @Override
-        public boolean apply(String filename) {
+        public boolean apply(String path) {
           for (String ext : extensions) {
-            if (filename.endsWith(ext) && !PIC_ARCHIVE.matches(filename)) {
+            if (path.endsWith(ext) && !PIC_ARCHIVE.matches(path)) {
               return true;
             }
           }
@@ -103,30 +111,36 @@ public final class CppFileTypes {
       };
 
   public static final FileType ALWAYS_LINK_PIC_LIBRARY = FileType.of(".pic.lo");
-  public static final FileType ALWAYS_LINK_LIBRARY = new FileType() {
-      final String ext = ".lo";
-      @Override
-      public boolean apply(String filename) {
-        return filename.endsWith(ext) && !ALWAYS_LINK_PIC_LIBRARY.matches(filename);
-      }
-      @Override
-      public List<String> getExtensions() {
-        return ImmutableList.of(ext);
-      }
-    };
+  public static final FileType ALWAYS_LINK_LIBRARY =
+      new FileType() {
+        final String ext = ".lo";
+
+        @Override
+        public boolean apply(String path) {
+          return path.endsWith(ext) && !ALWAYS_LINK_PIC_LIBRARY.matches(path);
+        }
+
+        @Override
+        public List<String> getExtensions() {
+          return ImmutableList.of(ext);
+        }
+      };
 
   public static final FileType PIC_OBJECT_FILE = FileType.of(".pic.o");
-  public static final FileType OBJECT_FILE = new FileType() {
-      final String ext = ".o";
-      @Override
-      public boolean apply(String filename) {
-        return filename.endsWith(ext) && !PIC_OBJECT_FILE.matches(filename);
-      }
-      @Override
-      public List<String> getExtensions() {
-        return ImmutableList.of(ext);
-      }
-    };
+  public static final FileType OBJECT_FILE =
+      new FileType() {
+        final String ext = ".o";
+
+        @Override
+        public boolean apply(String path) {
+          return path.endsWith(ext) && !PIC_OBJECT_FILE.matches(path);
+        }
+
+        @Override
+        public List<String> getExtensions() {
+          return ImmutableList.of(ext);
+        }
+      };
 
   // Minimized bitcode file emitted by the ThinLTO compile step and used just for LTO indexing.
   public static final FileType LTO_INDEXING_OBJECT_FILE = FileType.of(".indexing.o");
@@ -144,19 +158,20 @@ public final class CppFileTypes {
   // libmylib.so.2 or libmylib.so.2.10.
   private static final Pattern VERSIONED_SHARED_LIBRARY_PATTERN =
      Pattern.compile("^.+\\.so(\\.\\d+)+$");
-  public static final FileType VERSIONED_SHARED_LIBRARY = new FileType() {
-      @Override
-      public boolean apply(String filename) {
-        // Because regex matching can be slow, we first do a quick digit check on the final
-        // character before risking the full-on regex match. This should eliminate the performance
-        // hit on practically every non-qualifying file type.
-        if (Character.isDigit(filename.charAt(filename.length() - 1))) {
-          return VERSIONED_SHARED_LIBRARY_PATTERN.matcher(filename).matches();
-        } else {
-          return false;
+  public static final FileType VERSIONED_SHARED_LIBRARY =
+      new FileType() {
+        @Override
+        public boolean apply(String path) {
+          // Because regex matching can be slow, we first do a quick digit check on the final
+          // character before risking the full-on regex match. This should eliminate the performance
+          // hit on practically every non-qualifying file type.
+          if (Character.isDigit(path.charAt(path.length() - 1))) {
+            return VERSIONED_SHARED_LIBRARY_PATTERN.matcher(path).matches();
+          } else {
+            return false;
+          }
         }
-      }
-    };
+      };
 
   public static final FileType COVERAGE_NOTES = FileType.of(".gcno");
   public static final FileType COVERAGE_DATA = FileType.of(".gcda");
diff --git a/src/main/java/com/google/devtools/build/lib/util/FileType.java b/src/main/java/com/google/devtools/build/lib/util/FileType.java
index b4cc4b6bc3..e2f9eb390a 100644
--- a/src/main/java/com/google/devtools/build/lib/util/FileType.java
+++ b/src/main/java/com/google/devtools/build/lib/util/FileType.java
@@ -19,8 +19,6 @@ import com.google.common.base.Predicate;
 import com.google.common.base.Predicates;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
-import com.google.devtools.build.lib.vfs.Path;
-import com.google.devtools.build.lib.vfs.PathFragment;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -32,19 +30,22 @@ import javax.annotation.concurrent.Immutable;
 @Immutable
 public abstract class FileType implements Predicate<String> {
   // A special file type
-  public static final FileType NO_EXTENSION = new FileType() {
-      @Override
-      public boolean apply(String filename) {
-        return filename.lastIndexOf('.') == -1;
-      }
-  };
+  public static final FileType NO_EXTENSION =
+      new FileType() {
+        @Override
+        public boolean apply(String path) {
+          int lastSlashIndex = path.lastIndexOf('/');
+          return path.indexOf('.', lastSlashIndex + 1) == -1;
+        }
+      };
 
   public static FileType of(final String ext) {
     return new FileType() {
       @Override
-      public boolean apply(String filename) {
-        return filename.endsWith(ext);
+      public boolean apply(String path) {
+        return path.endsWith(ext);
       }
+
       @Override
       public List<String> getExtensions() {
         return ImmutableList.of(ext);
@@ -55,14 +56,15 @@ public abstract class FileType implements Predicate<String> {
   public static FileType of(final Iterable<String> extensions) {
     return new FileType() {
       @Override
-      public boolean apply(String filename) {
+      public boolean apply(String path) {
         for (String ext : extensions) {
-          if (filename.endsWith(ext)) {
+          if (path.endsWith(ext)) {
             return true;
           }
         }
         return false;
       }
+
       @Override
       public List<String> getExtensions() {
         return ImmutableList.copyOf(extensions);
@@ -79,12 +81,9 @@ public abstract class FileType implements Predicate<String> {
     return getExtensions().toString();
   }
 
-  /**
-   * Returns true if the the filename matches. The filename should be a basename (the filename
-   * component without a path) for performance reasons.
-   */
+  /** Returns true if the file matches. Subclasses are expected to handle a full path. */
   @Override
-  public abstract boolean apply(String filename);
+  public abstract boolean apply(String path);
 
   /**
    * Get a list of filename extensions this matcher handles. The first entry in the list (if
@@ -97,35 +96,29 @@ public abstract class FileType implements Predicate<String> {
     return ImmutableList.of();
   }
 
-  /** Return true if a file name is matched by the FileType */
-  public boolean matches(String filename) {
-    int slashIndex = filename.lastIndexOf('/');
-    if (slashIndex != -1) {
-      filename = filename.substring(slashIndex + 1);
-    }
-    return apply(filename);
-  }
-
-  /** Return true if a file referred by path is matched by the FileType */
-  public boolean matches(Path path) {
-    return apply(path.getBaseName());
+  /** Return true if a file path is matched by this FileType */
+  @Deprecated
+  public boolean matches(String path) {
+    return apply(path);
   }
 
-  /** Return true if a file referred by fragment is matched by the FileType */
-  public boolean matches(PathFragment fragment) {
-    return apply(fragment.getBaseName());
+  /** Return true if the item is matched by this FileType */
+  public boolean matches(HasFileType item) {
+    return apply(item.filePathForFileTypeMatcher());
   }
 
   // Check FileTypes
 
-  /**
-   * An interface for entities that have a filename.
-   */
-  public interface HasFilename {
+  /** An interface for entities that have a file type. */
+  public interface HasFileType {
     /**
-     * Returns the filename of this entity.
+     * Return a file path that ends with the file name.
+     *
+     * <p>The path will be used by {@link FileType} for matching. An example valid implementation
+     * could return the full path of the file, or just the file name, depending on what can
+     * efficiently be provided.
      */
-    String getFilename();
+    String filePathForFileTypeMatcher();
   }
 
   /**
@@ -133,12 +126,12 @@ public abstract class FileType implements Predicate<String> {
    *
    * <p>At least one FileType must be specified.
    */
-  public static <T extends HasFilename> boolean contains(final Iterable<T> items,
-      FileType... fileTypes) {
+  public static <T extends HasFileType> boolean contains(
+      final Iterable<T> items, FileType... fileTypes) {
     Preconditions.checkState(fileTypes.length > 0, "Must specify at least one file type");
     final FileTypeSet fileTypeSet = FileTypeSet.of(fileTypes);
     for (T item : items)  {
-      if (fileTypeSet.matches(item.getFilename())) {
+      if (fileTypeSet.matches(item.filePathForFileTypeMatcher())) {
         return true;
       }
     }
@@ -150,32 +143,31 @@ public abstract class FileType implements Predicate<String> {
    *
    * <p>At least one FileType must be specified.
    */
-  public static <T extends HasFilename> boolean contains(T item, FileType... fileTypes) {
-    return FileTypeSet.of(fileTypes).matches(item.getFilename());
+  public static <T extends HasFileType> boolean contains(T item, FileType... fileTypes) {
+    return FileTypeSet.of(fileTypes).matches(item.filePathForFileTypeMatcher());
   }
 
-
-  private static <T extends HasFilename> Predicate<T> typeMatchingPredicateFor(
+  private static <T extends HasFileType> Predicate<T> typeMatchingPredicateFor(
       final FileType matchingType) {
-    return item -> matchingType.matches(item.getFilename());
+    return item -> matchingType.matches(item.filePathForFileTypeMatcher());
   }
 
-  private static <T extends HasFilename> Predicate<T> typeMatchingPredicateFor(
+  private static <T extends HasFileType> Predicate<T> typeMatchingPredicateFor(
       final FileTypeSet matchingTypes) {
-    return item -> matchingTypes.matches(item.getFilename());
+    return item -> matchingTypes.matches(item.filePathForFileTypeMatcher());
   }
 
-  private static <T extends HasFilename> Predicate<T> typeMatchingPredicateFrom(
+  private static <T extends HasFileType> Predicate<T> typeMatchingPredicateFrom(
       final Predicate<String> fileTypePredicate) {
-    return item -> fileTypePredicate.apply(item.getFilename());
+    return item -> fileTypePredicate.apply(item.filePathForFileTypeMatcher());
   }
 
   /**
    * A filter for Iterable<? extends HasFileType> that returns only those whose FileType matches the
    * specified Predicate.
    */
-  public static <T extends HasFilename> Iterable<T> filter(final Iterable<T> items,
-      final Predicate<String> predicate) {
+  public static <T extends HasFileType> Iterable<T> filter(
+      final Iterable<T> items, final Predicate<String> predicate) {
     return Iterables.filter(items, typeMatchingPredicateFrom(predicate));
   }
 
@@ -183,8 +175,8 @@ public abstract class FileType implements Predicate<String> {
    * A filter for Iterable<? extends HasFileType> that returns only those of the specified file
    * types.
    */
-  public static <T extends HasFilename> Iterable<T> filter(final Iterable<T> items,
-      FileType... fileTypes) {
+  public static <T extends HasFileType> Iterable<T> filter(
+      final Iterable<T> items, FileType... fileTypes) {
     return filter(items, FileTypeSet.of(fileTypes));
   }
 
@@ -192,8 +184,8 @@ public abstract class FileType implements Predicate<String> {
    * A filter for Iterable<? extends HasFileType> that returns only those of the specified file
    * types.
    */
-  public static <T extends HasFilename> Iterable<T> filter(final Iterable<T> items,
-      FileTypeSet fileTypes) {
+  public static <T extends HasFileType> Iterable<T> filter(
+      final Iterable<T> items, FileTypeSet fileTypes) {
     return Iterables.filter(items, typeMatchingPredicateFor(fileTypes));
   }
 
@@ -201,8 +193,8 @@ public abstract class FileType implements Predicate<String> {
    * A filter for Iterable<? extends HasFileType> that returns only those of the specified file
    * type.
    */
-  public static <T extends HasFilename> Iterable<T> filter(final Iterable<T> items,
-      FileType fileType) {
+  public static <T extends HasFileType> Iterable<T> filter(
+      final Iterable<T> items, FileType fileType) {
     return Iterables.filter(items, typeMatchingPredicateFor(fileType));
   }
 
@@ -210,18 +202,17 @@ public abstract class FileType implements Predicate<String> {
    * A filter for Iterable<? extends HasFileType> that returns everything except the specified file
    * type.
    */
-  public static <T extends HasFilename> Iterable<T> except(final Iterable<T> items,
-      FileType fileType) {
+  public static <T extends HasFileType> Iterable<T> except(
+      final Iterable<T> items, FileType fileType) {
     return Iterables.filter(items, Predicates.not(typeMatchingPredicateFor(fileType)));
   }
 
-
   /**
    * A filter for List<? extends HasFileType> that returns only those of the specified file types.
    * The result is a mutable list, computed eagerly; see {@link #filter} for a lazy variant.
    */
-  public static <T extends HasFilename> List<T> filterList(final Iterable<T> items,
-      FileType... fileTypes) {
+  public static <T extends HasFileType> List<T> filterList(
+      final Iterable<T> items, FileType... fileTypes) {
     if (fileTypes.length > 0) {
       return filterList(items, FileTypeSet.of(fileTypes));
     } else {
@@ -233,11 +224,11 @@ public abstract class FileType implements Predicate<String> {
    * A filter for List<? extends HasFileType> that returns only those of the specified file type.
    * The result is a mutable list, computed eagerly.
    */
-  public static <T extends HasFilename> List<T> filterList(final Iterable<T> items,
-      final FileType fileType) {
+  public static <T extends HasFileType> List<T> filterList(
+      final Iterable<T> items, final FileType fileType) {
     List<T> result = new ArrayList<>();
     for (T item : items)  {
-      if (fileType.matches(item.getFilename())) {
+      if (fileType.matches(item.filePathForFileTypeMatcher())) {
         result.add(item);
       }
     }
@@ -248,11 +239,11 @@ public abstract class FileType implements Predicate<String> {
    * A filter for List<? extends HasFileType> that returns only those of the specified file types.
    * The result is a mutable list, computed eagerly.
    */
-  public static <T extends HasFilename> List<T> filterList(final Iterable<T> items,
-      final FileTypeSet fileTypeSet) {
+  public static <T extends HasFileType> List<T> filterList(
+      final Iterable<T> items, final FileTypeSet fileTypeSet) {
     List<T> result = new ArrayList<>();
     for (T item : items)  {
-      if (fileTypeSet.matches(item.getFilename())) {
+      if (fileTypeSet.matches(item.filePathForFileTypeMatcher())) {
         result.add(item);
       }
     }
diff --git a/src/main/java/com/google/devtools/build/lib/util/FileTypeSet.java b/src/main/java/com/google/devtools/build/lib/util/FileTypeSet.java
index d708526387..9b3b2e46fe 100644
--- a/src/main/java/com/google/devtools/build/lib/util/FileTypeSet.java
+++ b/src/main/java/com/google/devtools/build/lib/util/FileTypeSet.java
@@ -17,11 +17,9 @@ import com.google.common.base.Predicate;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
-
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
-
 import javax.annotation.concurrent.Immutable;
 
 /**
@@ -38,23 +36,26 @@ public class FileTypeSet implements Predicate<String> {
         public String toString() {
           return "any files";
         }
+
         @Override
         public boolean matches(String filename) {
           return true;
         }
+
         @Override
         public List<String> getExtensions() {
-          return ImmutableList.<String>of();
+          return ImmutableList.of();
         }
       };
 
   /** A predicate that matches no files. */
   public static final FileTypeSet NO_FILE =
-      new FileTypeSet(ImmutableList.<FileType>of()) {
+      new FileTypeSet(ImmutableList.of()) {
         @Override
         public String toString() {
           return "no files";
         }
+
         @Override
         public boolean matches(String filename) {
           return false;
@@ -105,13 +106,9 @@ public class FileTypeSet implements Predicate<String> {
   }
 
   /** Returns true if the filename can be matched by any FileType in this set. */
-  public boolean matches(String filename) {
-    int slashIndex = filename.lastIndexOf('/');
-    if (slashIndex != -1) {
-      filename = filename.substring(slashIndex + 1);
-    }
+  public boolean matches(String path) {
     for (FileType type : types) {
-      if (type.apply(filename)) {
+      if (type.apply(path)) {
         return true;
       }
     }
@@ -124,8 +121,8 @@ public class FileTypeSet implements Predicate<String> {
   }
 
   @Override
-  public boolean apply(String filename) {
-    return matches(filename);
+  public boolean apply(String path) {
+    return matches(path);
   }
 
   /** Returns the list of possible file extensions for this file type. Can be empty. */
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 88c7c86490..f6d2eb427b 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:filetype",
         "//src/main/java/com/google/devtools/build/lib:os_util",
         "//src/main/java/com/google/devtools/build/lib:skylarkinterface",
         "//src/main/java/com/google/devtools/build/lib/concurrent",
@@ -44,6 +45,7 @@ java_library(
     deps = [
         ":pathfragment",
         "//src/main/java/com/google/devtools/build/lib:base-util",
+        "//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",
         "//src/main/java/com/google/devtools/build/lib/clock",
diff --git a/src/main/java/com/google/devtools/build/lib/vfs/Path.java b/src/main/java/com/google/devtools/build/lib/vfs/Path.java
index 06a884b4a9..1d6c57c730 100644
--- a/src/main/java/com/google/devtools/build/lib/vfs/Path.java
+++ b/src/main/java/com/google/devtools/build/lib/vfs/Path.java
@@ -18,6 +18,7 @@ import com.google.common.base.Predicate;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkPrintable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkPrinter;
+import com.google.devtools.build.lib.util.FileType;
 import com.google.devtools.build.lib.util.StringCanonicalizer;
 import com.google.devtools.build.lib.vfs.FileSystem.HashFunction;
 import java.io.File;
@@ -52,7 +53,8 @@ import java.util.Objects;
  * <p>{@link FileSystem} implementations maintain pointers into this graph.
  */
 @ThreadSafe
-public class Path implements Comparable<Path>, Serializable, SkylarkPrintable {
+public class Path
+    implements Comparable<Path>, Serializable, SkylarkPrintable, FileType.HasFileType {
 
   /** Filesystem-specific factory for {@link Path} objects. */
   public static interface PathFactory {
@@ -428,6 +430,11 @@ public class Path implements Comparable<Path>, Serializable, SkylarkPrintable {
     printer.append(getPathString());
   }
 
+  @Override
+  public String filePathForFileTypeMatcher() {
+    return name;
+  }
+
   /**
    * Returns the path as a string.
    */
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 05e4ee86c8..6f6dfbf819 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
@@ -26,6 +26,7 @@ import com.google.devtools.build.lib.skyframe.serialization.SerializationExcepti
 import com.google.devtools.build.lib.skyframe.serialization.strings.StringCodecs;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkPrintable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkPrinter;
+import com.google.devtools.build.lib.util.FileType;
 import com.google.devtools.build.lib.util.OS;
 import com.google.devtools.build.lib.util.StringCanonicalizer;
 import com.google.protobuf.CodedInputStream;
@@ -55,7 +56,7 @@ import java.util.Set;
 @javax.annotation.concurrent.Immutable
 @ThreadSafe
 public abstract class PathFragment
-    implements Comparable<PathFragment>, Serializable, SkylarkPrintable {
+    implements Comparable<PathFragment>, Serializable, SkylarkPrintable, FileType.HasFileType {
   private static final Helper HELPER =
       OS.getCurrent() == OS.WINDOWS ? WindowsPathFragment.HELPER : UnixPathFragment.HELPER;
 
@@ -751,6 +752,11 @@ public abstract class PathFragment
     printer.append(getPathString());
   }
 
+  @Override
+  public String filePathForFileTypeMatcher() {
+    return getBaseName();
+  }
+
   private static class PathFragmentCodec implements ObjectCodec<PathFragment> {
     private final ObjectCodec<String> stringCodec = StringCodecs.asciiOptimized();