Revert "Remove outdated "output directory name" option."

This reverts commit af0e20f.

src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfigurationValue.java

@@ -36,6 +36,7 @@
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.concurrent.BlazeInterners;
+import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.skyframe.BuildConfigurationKey;
 import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
@@ -139,6 +140,12 @@ public void reportInvalidOptions(EventHandler reporter) {
     for (Fragment fragment : fragments.values()) {
       fragment.reportInvalidOptions(reporter, this.buildOptions);
     }
+
+    if (options.outputDirectoryName != null) {
+      reporter.handle(
+          Event.error(
+              "The internal '--output directory name' option cannot be used on the command line"));
+    }
   }
 
   /**

src/main/java/com/google/devtools/build/lib/analysis/config/CoreOptions.java

@@ -245,6 +245,23 @@ public class CoreOptions extends FragmentOptions implements Cloneable {
               + "'fastbuild', 'dbg', 'opt'.")
   public CompilationMode hostCompilationMode;
 
+  /**
+   * This option is used internally to set output directory name of the <i>host</i> configuration to
+   * a constant, so that the output files for the host are completely independent of those for the
+   * target, no matter what options are in force (k8/piii, opt/dbg, etc).
+   */
+  @Option(
+      name = "output directory name",
+      defaultValue = "null",
+      documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
+      effectTags = {
+        OptionEffectTag.LOSES_INCREMENTAL_STATE,
+        OptionEffectTag.AFFECTS_OUTPUTS,
+        OptionEffectTag.LOADING_AND_ANALYSIS
+      },
+      metadataTags = {OptionMetadataTag.INTERNAL})
+  public String outputDirectoryName;
+
   @Option(
       name = "experimental_enable_aspect_hints",
       defaultValue = "false",
@@ -919,6 +936,7 @@ public IncludeConfigFragmentsEnumConverter() {
   public FragmentOptions getHost() {
     CoreOptions host = (CoreOptions) getDefault();
 
+    host.outputDirectoryName = "host";
     host.affectedByStarlarkTransition = affectedByStarlarkTransition;
     host.outputDirectoryNamingScheme = outputDirectoryNamingScheme;
     host.compilationMode = hostCompilationMode;

src/main/java/com/google/devtools/build/lib/analysis/config/ExecutionTransitionFactory.java

@@ -128,8 +128,10 @@ private static BuildOptions transitionImpl(BuildOptionsView options, Label execu
       CoreOptions coreOptions = checkNotNull(execOptions.get(CoreOptions.class));
       coreOptions.isHost = false;
       coreOptions.isExec = true;
+
       // Disable extra actions
       coreOptions.actionListeners = null;
+      coreOptions.outputDirectoryName = null;
 
       // Then set the target to the saved execution platform if there is one.
       PlatformOptions platformOptions = execOptions.get(PlatformOptions.class);

src/main/java/com/google/devtools/build/lib/analysis/config/OutputDirectories.java

@@ -142,7 +142,8 @@ public ArtifactRoot getRoot(
     this.directories = directories;
     this.mnemonic =
         buildMnemonic(options, platformOptions, fragments, transitionDirectoryNameFragment);
-    this.outputDirName = options.isHost ? "host" : mnemonic;
+    this.outputDirName =
+        (options.outputDirectoryName != null) ? options.outputDirectoryName : (options.isHost ? "host" : mnemonic);
 
     this.outputDirectory =
         OutputDirectory.OUTPUT.getRoot(outputDirName, directories, mainRepositoryName);

src/test/java/com/google/devtools/build/lib/analysis/BuildViewTest.java

@@ -28,6 +28,7 @@
 import com.google.devtools.build.lib.actions.Actions;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.actions.FailAction;
+import com.google.devtools.build.lib.analysis.config.CoreOptions;
 import com.google.devtools.build.lib.analysis.config.transitions.NoTransition;
 import com.google.devtools.build.lib.analysis.config.transitions.NullTransition;
 import com.google.devtools.build.lib.analysis.configuredtargets.InputFileConfiguredTarget;
@@ -52,6 +53,8 @@
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import com.google.devtools.build.skyframe.NotifyingHelper.Listener;
+import com.google.devtools.common.options.Options;
+import com.google.devtools.common.options.OptionsParsingException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.LinkedHashSet;
@@ -542,6 +545,23 @@ reporter, top, getBuildConfigurationCollection(), /* toolchainContexts= */ null)
     assertThat(targets).containsExactly(innerDependency, fileDependency);
   }
 
+  /** Tests that the {@code --output directory name} option cannot be used on the command line. */
+  @Test
+  public void testConfigurationShortName() {
+    // Check that output directory name is still the name, otherwise this test is not testing what
+    // we expect.
+    CoreOptions options = Options.getDefaults(CoreOptions.class);
+    options.outputDirectoryName = "/home/wonkaw/wonka_chocolate/factory/out";
+    assertWithMessage("The flag's name may have been changed; this test may need to be updated.")
+        .that(options.asMap().get("output directory name"))
+        .isEqualTo("/home/wonkaw/wonka_chocolate/factory/out");
+
+    OptionsParsingException e =
+        assertThrows(
+            OptionsParsingException.class, () -> useConfiguration("--output directory name=foo"));
+    assertThat(e).hasMessageThat().isEqualTo("Unrecognized option: --output directory name=foo");
+  }
+
   // Regression test: "output_filter broken (but in a different way)"
   @Test
   @Ignore("b/182560362 Starlark java_library can't output warnings")

src/test/java/com/google/devtools/build/lib/skyframe/PlatformMappingFunctionTest.java

@@ -210,15 +210,16 @@ public void multiplePackagePathsFirstWins() throws Exception {
     assertThat(mapped.getOptions().get(CoreOptions.class).cpu).isEqualTo("one");
   }
 
-  // Internal flags (OptionMetadataTag.INTERNAL) cannot be set from the command-line, but
+  // Internal flags, such as "output directory name", cannot be set from the command-line, but
   // platform mapping needs to access them.
   @Test
   public void ableToChangeInternalOption() throws Exception {
     scratch.file(
         "my_mapping_file",
         "platforms:", // Force line break
         "  //platforms:one", // Force line break
-        "    --internal foo=something_new");
+        "    --internal foo=something_new",
+        "    --output directory name=updated_output_dir");
 
     PlatformMappingValue platformMappingValue =
         executeFunction(PlatformMappingValue.Key.create(PathFragment.create("my_mapping_file")));
@@ -230,6 +231,8 @@ public void ableToChangeInternalOption() throws Exception {
 
     assertThat(mapped.getOptions().get(DummyTestFragment.DummyTestOptions.class).internalFoo)
         .isEqualTo("something_new");
+    assertThat(mapped.getOptions().get(CoreOptions.class).outputDirectoryName)
+        .isEqualTo("updated_output_dir");
   }
 
   private PlatformMappingValue executeFunction(PlatformMappingValue.Key key) throws Exception {