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

2 files changed, 12 insertions, 1 deletions

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();