Add a Constants.TOOLS_PREFIX constant that will serve to redirect the Bazel tools repository.

This is a no-op refactoring CL. The actual switch will be made once everything passes with the new setup.

As a side cleanup, change the awkward realAndroidSdk() / realAndroidCrosstoolTop() mechanism to a converter.

--
MOS_MIGRATED_REVID=104649067

26 files changed, 300 insertions, 143 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/Constants.java b/src/main/java/com/google/devtools/build/lib/Constants.java
index 176a9f4786..d4d643662f 100644
--- a/src/main/java/com/google/devtools/build/lib/Constants.java
+++ b/src/main/java/com/google/devtools/build/lib/Constants.java
@@ -38,6 +38,7 @@ public class Constants {
   public static final ImmutableList<String> ANDROID_DEFAULT_FAT_APK_CPUS =
       ImmutableList.<String>of("armeabi-v7a");
   public static final String ANDROID_DEP_PREFIX = "//external:android/".toString();
+  public static final String TOOLS_REPOSITORY = "".toString();
 
   /**
    * Whether C++ include scanning should be disabled no matter what the --cc_include_scanning flag
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/BaseRuleClasses.java b/src/main/java/com/google/devtools/build/lib/analysis/BaseRuleClasses.java
index 1ab037c167..154c41f595 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/BaseRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/BaseRuleClasses.java
@@ -28,6 +28,7 @@ import static com.google.devtools.build.lib.syntax.Type.STRING;
 import static com.google.devtools.build.lib.syntax.Type.STRING_LIST;
 
 import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.config.RunUnder;
 import com.google.devtools.build.lib.analysis.constraints.EnvironmentRule;
@@ -55,7 +56,7 @@ public class BaseRuleClasses {
    * for running tests in coverage mode.
    */
   private static final Label COVERAGE_SUPPORT_LABEL =
-      Label.parseAbsoluteUnchecked("//tools/defaults:coverage");
+      Label.parseAbsoluteUnchecked(Constants.TOOLS_REPOSITORY + "//tools/defaults:coverage");
 
   private static final Attribute.ComputedDefault testonlyDefault =
       new Attribute.ComputedDefault() {
@@ -162,7 +163,7 @@ public class BaseRuleClasses {
           .add(attr("args", STRING_LIST)
               .nonconfigurable("policy decision: should be consistent across configurations"))
           .add(attr("$test_runtime", LABEL_LIST).cfg(HOST).value(ImmutableList.of(
-              env.getLabel("//tools/test:runtime"))))
+              env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/test:runtime"))))
 
           // TODO(bazel-team): TestActions may need to be run with coverage, so all tests
           // implicitly depend on crosstool, which provides gcov.  We could add gcov to
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
index 52276512a8..c460e3dd84 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
@@ -280,23 +280,50 @@ public final class BuildConfiguration {
     }
   }
 
+  private static final Label convertLabel(String input) throws OptionsParsingException {
+    try {
+      // Check if the input starts with '/'. We don't check for "//" so that
+      // we get a better error message if the user accidentally tries to use
+      // an absolute path (starting with '/') for a label.
+      if (!input.startsWith("/") && !input.startsWith("@")) {
+        input = "//" + input;
+      }
+      return Label.parseAbsolute(input);
+    } catch (LabelSyntaxException e) {
+      throw new OptionsParsingException(e.getMessage());
+    }
+  }
+
   /**
    * A converter from strings to Labels.
    */
   public static class LabelConverter implements Converter<Label> {
     @Override
     public Label convert(String input) throws OptionsParsingException {
-      try {
-        // Check if the input starts with '/'. We don't check for "//" so that
-        // we get a better error message if the user accidentally tries to use
-        // an absolute path (starting with '/') for a label.
-        if (!input.startsWith("/") && !input.startsWith("@")) {
-          input = "//" + input;
-        }
-        return Label.parseAbsolute(input);
-      } catch (LabelSyntaxException e) {
-        throw new OptionsParsingException(e.getMessage());
-      }
+      return convertLabel(input);
+    }
+
+    @Override
+    public String getTypeDescription() {
+      return "a build target label";
+    }
+  }
+
+  /**
+   * A label converter that returns a default value if the input string is empty.
+   */
+  public static class DefaultLabelConverter implements Converter<Label> {
+    private final Label defaultValue;
+
+    protected DefaultLabelConverter(String defaultValue) {
+      this.defaultValue = defaultValue.equals("null")
+          ? null
+          : Label.parseAbsoluteUnchecked(defaultValue);
+    }
+
+    @Override
+    public Label convert(String input) throws OptionsParsingException {
+      return input.isEmpty() ? defaultValue : convertLabel(input);
     }
 
     @Override
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/commands/FetchCommand.java b/src/main/java/com/google/devtools/build/lib/bazel/commands/FetchCommand.java
index 1974a24085..c4a5dca0ef 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/commands/FetchCommand.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/commands/FetchCommand.java
@@ -93,7 +93,8 @@ public final class FetchCommand implements BlazeCommand {
     JavaOptions javaOptions = options.getOptions(JavaOptions.class);
     ImmutableList.Builder<String> labelsToLoad = new ImmutableList.Builder<String>()
         .addAll(options.getResidue());
-    if (String.valueOf(javaOptions.javaLangtoolsJar).equals(JavaOptions.DEFAULT_LANGTOOLS)) {
+    if (String.valueOf(javaOptions.javaLangtoolsJar).equals(
+        Constants.TOOLS_REPOSITORY + JavaOptions.DEFAULT_LANGTOOLS)) {
       labelsToLoad.add(javaOptions.javaBase);
     } else {
       // TODO(kchodroow): Remove this when OS X isn't as hacky about finding the JVM. Our test
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/android/AndroidRepositoryRules.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/android/AndroidRepositoryRules.java
index 732c48626c..582a5b14eb 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/android/AndroidRepositoryRules.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/android/AndroidRepositoryRules.java
@@ -62,8 +62,8 @@ public class AndroidRepositoryRules {
           public Map<String, Label> apply(Rule rule) {
             ImmutableMap.Builder<String, Label> result = ImmutableMap.builder();
             for (String tool : TOOLS) {
-              result.put("android/" + tool,
-                  Label.parseAbsoluteUnchecked("@" + rule.getName() + "//tools/android:" + tool));
+              result.put("android/" + tool, Label.parseAbsoluteUnchecked(
+                  "@" + rule.getName() + "//tools/android:" + tool));
             }
 
             return result.build();
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/cpp/BazelCppRuleClasses.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/cpp/BazelCppRuleClasses.java
index aa8bfead1f..60618ff18d 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/cpp/BazelCppRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/cpp/BazelCppRuleClasses.java
@@ -39,6 +39,7 @@ import static com.google.devtools.build.lib.syntax.Type.STRING;
 import static com.google.devtools.build.lib.syntax.Type.STRING_LIST;
 
 import com.google.common.base.Predicates;
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
@@ -152,7 +153,8 @@ public class BazelCppRuleClasses {
    * Label of a pseudo-filegroup that contains all crosstool and libcfiles for
    * all configurations, as specified on the command-line.
    */
-  public static final String CROSSTOOL_LABEL = "//tools/defaults:crosstool";
+  public static final String CROSSTOOL_LABEL =
+      Constants.TOOLS_REPOSITORY + "//tools/defaults:crosstool";
 
   public static final LateBoundLabel<BuildConfiguration> CC_TOOLCHAIN =
       new LateBoundLabel<BuildConfiguration>(CROSSTOOL_LABEL) {
@@ -258,7 +260,8 @@ public class BazelCppRuleClasses {
           so be careful about header files included elsewhere.</p>
           <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
           .add(attr("copts", STRING_LIST))
-          .add(attr("$stl", LABEL).value(env.getLabel("//tools/cpp:stl")))
+          .add(attr("$stl", LABEL).value(
+              env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/cpp:stl")))
           .add(attr(":stl", LABEL).value(STL))
           .build();
     }
@@ -565,7 +568,7 @@ public class BazelCppRuleClasses {
               // Every cc_rule depends implicitly on STL to make
               // sure that the correct headers are used for inclusion. The only exception is
               // STL itself to avoid cycles in the dependency graph.
-              Label stl = env.getLabel("//tools/cpp:stl");
+              Label stl = env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/cpp:stl");
               return rule.getLabel().equals(stl) ? null : stl;
             }
           }))
@@ -600,7 +603,7 @@ public class BazelCppRuleClasses {
           </p>
           <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
           .add(attr("malloc", LABEL)
-              .value(env.getLabel("//tools/cpp:malloc"))
+              .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/cpp:malloc"))
               .allowedFileTypes()
               .allowedRuleClasses("cc_library"))
           .add(attr(":default_malloc", LABEL).value(DEFAULT_MALLOC))
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/genrule/BazelGenRuleRule.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/genrule/BazelGenRuleRule.java
index 3d6f3ea0fe..820d5d75b5 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/genrule/BazelGenRuleRule.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/genrule/BazelGenRuleRule.java
@@ -22,6 +22,7 @@ import static com.google.devtools.build.lib.packages.BuildType.OUTPUT_LIST;
 import static com.google.devtools.build.lib.syntax.Type.BOOLEAN;
 import static com.google.devtools.build.lib.syntax.Type.STRING;
 
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
@@ -35,7 +36,8 @@ import com.google.devtools.build.lib.packages.RuleClass.Builder;
  * Rule definition for the genrule rule.
  */
 public final class BazelGenRuleRule implements RuleDefinition {
-  public static final String GENRULE_SETUP_LABEL = "//tools/genrule:genrule-setup.sh";
+  public static final String GENRULE_SETUP_LABEL =
+      Constants.TOOLS_REPOSITORY + "//tools/genrule:genrule-setup.sh";
 
   @Override
   public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/java/BazelJavaRuleClasses.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/java/BazelJavaRuleClasses.java
index 46048876da..5cd576f567 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/java/BazelJavaRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/java/BazelJavaRuleClasses.java
@@ -25,6 +25,7 @@ import static com.google.devtools.build.lib.syntax.Type.STRING;
 import static com.google.devtools.build.lib.syntax.Type.STRING_LIST;
 
 import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
@@ -69,7 +70,8 @@ public class BazelJavaRuleClasses {
     @Override
     public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
       return builder
-          .add(attr("$ijar", LABEL).cfg(HOST).exec().value(env.getLabel("//tools/defaults:ijar")))
+          .add(attr("$ijar", LABEL).cfg(HOST).exec().value(env.getLabel(
+              Constants.TOOLS_REPOSITORY + "//tools/defaults:ijar")))
           .setPreferredDependencyPredicate(JavaSemantics.JAVA_SOURCE)
           .build();
     }
@@ -97,7 +99,7 @@ public class BazelJavaRuleClasses {
           .add(attr("$javac_extdir", LABEL).cfg(HOST)
               .value(env.getLabel(JavaSemantics.JAVAC_EXTDIR_LABEL)))
           .add(attr("$java_langtools", LABEL).cfg(HOST)
-              .value(env.getLabel("//tools/defaults:java_langtools")))
+              .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/defaults:java_langtools")))
           .add(attr("$javac_bootclasspath", LABEL).cfg(HOST)
               .value(env.getLabel(JavaSemantics.JAVAC_BOOTCLASSPATH_LABEL)))
           .add(attr("$javabuilder", LABEL).cfg(HOST)
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/objc/BazelIosTestRule.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/objc/BazelIosTestRule.java
index f263cf4318..0182a5370e 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/objc/BazelIosTestRule.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/objc/BazelIosTestRule.java
@@ -21,6 +21,7 @@ import static com.google.devtools.build.lib.packages.BuildType.LABEL_LIST;
 import static com.google.devtools.build.lib.syntax.Type.STRING_LIST;
 
 import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
@@ -64,7 +65,8 @@ public final class BazelIosTestRule implements RuleDefinition {
             attr(IosTest.TARGET_DEVICE, LABEL)
                 .allowedFileTypes()
                 .allowedRuleClasses("ios_device")
-                .value(env.getLabel("//tools/objc/sim_devices:default")))
+                .value(env.getLabel(
+                    Constants.TOOLS_REPOSITORY + "//tools/objc/sim_devices:default")))
         /* <!-- #BLAZE_RULE(ios_test).ATTRIBUTE(ios_test_target_device) -->
          The device against how to run the test. If this attribute is defined, the test will run on
          the lab device. Otherwise, the test will run on simulator.
@@ -87,8 +89,10 @@ public final class BazelIosTestRule implements RuleDefinition {
          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
         .add(attr("plugins", LABEL_LIST).allowedFileTypes(FileType.of("_deploy.jar")))
         .add(attr("$test_template", LABEL)
-            .value(env.getLabel("//tools/objc:ios_test.sh.bazel_template")))
-        .add(attr("$test_runner", LABEL).value(env.getLabel("//tools/objc:testrunner")))
+            .value(env.getLabel(
+                Constants.TOOLS_REPOSITORY + "//tools/objc:ios_test.sh.bazel_template")))
+        .add(attr("$test_runner", LABEL)
+            .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:testrunner")))
         .override(attr(":gcov", LABEL_LIST).cfg(HOST)
             .value(new LateBoundLabelList<BuildConfiguration>() {
               @Override
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/python/BazelPyRuleClasses.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/python/BazelPyRuleClasses.java
index f3889fbaea..7c1e06ecc5 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/python/BazelPyRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/python/BazelPyRuleClasses.java
@@ -21,6 +21,7 @@ import static com.google.devtools.build.lib.packages.BuildType.LABEL_LIST;
 import static com.google.devtools.build.lib.packages.BuildType.TRISTATE;
 import static com.google.devtools.build.lib.syntax.Type.STRING;
 
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
@@ -84,7 +85,7 @@ public final class BazelPyRuleClasses {
           // do not depend on lib2to3:2to3 rule, because it creates circular dependencies
           // 2to3 is itself written in Python and depends on many libraries.
           .add(attr("$python2to3", LABEL).cfg(HOST).exec()
-              .value(env.getLabel("//tools/python:2to3")))
+              .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/python:2to3")))
           .setPreferredDependencyPredicate(PyRuleClasses.PYTHON_SOURCE)
           .build();
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleClassFunctions.java b/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleClassFunctions.java
index b083cbf835..87b570318c 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleClassFunctions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/SkylarkRuleClassFunctions.java
@@ -35,6 +35,7 @@ import com.google.common.cache.LoadingCache;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.config.RunUnder;
@@ -167,7 +168,7 @@ public class SkylarkRuleClassFunctions {
           .add(attr("args", STRING_LIST)
               .nonconfigurable("policy decision: should be consistent across configurations"))
           .add(attr("$test_runtime", LABEL_LIST).cfg(HOST).value(ImmutableList.of(
-              labelCache.getUnchecked("//tools/test:runtime"))))
+              labelCache.getUnchecked(Constants.TOOLS_REPOSITORY + "//tools/test:runtime"))))
           .add(attr(":run_under", LABEL).cfg(DATA).value(RUN_UNDER))
           .build();
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidConfiguration.java
index 7f63829480..79bf08a98e 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidConfiguration.java
@@ -19,6 +19,7 @@ import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Multimap;
 import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
+import com.google.devtools.build.lib.analysis.config.BuildConfiguration.DefaultLabelConverter;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration.Fragment;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration.LabelConverter;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration.StrictDepsConverter;
@@ -40,6 +41,21 @@ import java.util.List;
  * Configuration fragment for Android rules.
  */
 public class AndroidConfiguration extends BuildConfiguration.Fragment {
+
+  /** Converter for --android_crosstool_top. */
+  public static class AndroidCrosstoolTopConverter extends DefaultLabelConverter {
+    public AndroidCrosstoolTopConverter() {
+      super(Constants.ANDROID_DEFAULT_CROSSTOOL);
+    }
+  }
+
+  /** Converter for --android_sdk. */
+  public static class AndroidSdkConverter extends DefaultLabelConverter {
+    public AndroidSdkConverter() {
+      super(Constants.ANDROID_DEFAULT_SDK);
+    }
+  }
+
   /**
    * Value used to avoid multiple configurations from conflicting.
    *
@@ -92,9 +108,9 @@ public class AndroidConfiguration extends BuildConfiguration.Fragment {
     public boolean incrementalNativeLibs;
 
     @Option(name = "android_crosstool_top",
-        defaultValue = "null",
+        defaultValue = "",
         category = "semantics",
-        converter = LabelConverter.class,
+        converter = AndroidCrosstoolTopConverter.class,
         help = "The location of the C++ compiler used for Android builds.")
     public Label androidCrosstoolTop;
 
@@ -116,9 +132,9 @@ public class AndroidConfiguration extends BuildConfiguration.Fragment {
     // Label of filegroup combining all Android tools used as implicit dependencies of
     // android_* rules
     @Option(name = "android_sdk",
-            defaultValue = "null",
+            defaultValue = "",
             category = "version",
-            converter = LabelConverter.class,
+            converter = AndroidSdkConverter.class,
             help = "Specifies Android SDK/platform that is used to build Android applications.")
     public Label sdk;
 
@@ -177,37 +193,16 @@ public class AndroidConfiguration extends BuildConfiguration.Fragment {
         labelMap.put("android_proguard", proguard);
       }
 
-      if (realAndroidCrosstoolTop() != null) {
-        labelMap.put("android_crosstool_top", realAndroidCrosstoolTop());
-      }
-
-      labelMap.put("android_sdk", realSdk());
-    }
-
-    // This method is here because Constants.ANDROID_DEFAULT_SDK cannot be a constant, because we
-    // replace the class file in the .jar after compilation. However, that means that we cannot use
-    // it as an attribute value in an annotation.
-    private Label realSdk() {
-      return sdk == null
-          ? Label.parseAbsoluteUnchecked(Constants.ANDROID_DEFAULT_SDK)
-          : sdk;
-    }
-
-    // This method is here because Constants.ANDROID_DEFAULT_CROSSTOOL cannot be a constant, because
-    // we replace the class file in the .jar after compilation. However, that means that we cannot
-    // use it as an attribute value in an annotation.
-    public Label realAndroidCrosstoolTop() {
       if (androidCrosstoolTop != null) {
-        return androidCrosstoolTop;
-      }
-
-      if (Constants.ANDROID_DEFAULT_CROSSTOOL.equals("null")) {
-        return null;
+        labelMap.put("android_crosstool_top", androidCrosstoolTop);
       }
 
-      return Label.parseAbsoluteUnchecked(Constants.ANDROID_DEFAULT_CROSSTOOL);
+      labelMap.put("android_sdk", sdk);
     }
 
+    // This method is here because Constants.ANDROID_DEFAULT_FAT_APK_CPUS cannot be a constant
+    // because we replace the class file in the .jar after compilation. However, that means that we
+    // cannot use it as an attribute value in an annotation.
     public List<String> realFatApkCpus() {
       if (fatApkCpus.isEmpty()) {
         return Constants.ANDROID_DEFAULT_FAT_APK_CPUS;
@@ -260,7 +255,7 @@ public class AndroidConfiguration extends BuildConfiguration.Fragment {
   private final boolean jackSanityChecks;
 
   AndroidConfiguration(Options options) {
-    this.sdk = options.realSdk();
+    this.sdk = options.sdk;
     this.incrementalNativeLibs = options.incrementalNativeLibs;
     this.strictDeps = options.strictDeps;
     this.legacyNativeSupport = options.legacyNativeSupport;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java
index c1e14989a3..3a1a376f02 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java
@@ -180,12 +180,12 @@ public final class AndroidRuleClasses {
           output.get(AndroidConfiguration.Options.class);
 
       CppOptions cppOptions = output.get(CppOptions.class);
-      if (inputAndroidOptions.realAndroidCrosstoolTop() != null
-          && !cppOptions.crosstoolTop.equals(inputAndroidOptions.realAndroidCrosstoolTop())) {
+      if (inputAndroidOptions.androidCrosstoolTop != null
+          && !cppOptions.crosstoolTop().equals(inputAndroidOptions.androidCrosstoolTop)) {
         if (cppOptions.hostCrosstoolTop == null) {
           cppOptions.hostCrosstoolTop = cppOptions.crosstoolTop;
         }
-        cppOptions.crosstoolTop = inputAndroidOptions.realAndroidCrosstoolTop();
+        cppOptions.crosstoolTop = inputAndroidOptions.androidCrosstoolTop;
       }
 
       outputAndroidOptions.configurationDistinguisher = ConfigurationDistinguisher.ANDROID;
@@ -196,9 +196,10 @@ public final class AndroidRuleClasses {
       AndroidConfiguration.Options androidOptions =
           buildOptions.get(AndroidConfiguration.Options.class);
       CppOptions cppOptions = buildOptions.get(CppOptions.class);
-      Label androidCrosstoolTop = androidOptions.realAndroidCrosstoolTop();
+      Label androidCrosstoolTop = androidOptions.androidCrosstoolTop;
       if (androidOptions.realFatApkCpus().isEmpty()
-          && (androidCrosstoolTop == null || androidCrosstoolTop.equals(cppOptions.crosstoolTop))) {
+          && (androidCrosstoolTop == null
+          || androidCrosstoolTop.equals(cppOptions.crosstoolTop()))) {
         return ImmutableList.of();
       }
 
@@ -330,7 +331,8 @@ public final class AndroidRuleClasses {
                   .allowedFileTypes(ANY_FILE)
                   // TODO(bazel-team): Remove defaults and make mandatory when android_sdk targets
                   // have been updated to include manually specified Jack attributes.
-                  .value(environment.getLabel("//tools/android/jack:android_jack")))
+                  .value(environment.getLabel(
+                      Constants.TOOLS_REPOSITORY + "//tools/android/jack:android_jack")))
           .add(attr("annotations_jar", LABEL).mandatory().cfg(HOST).allowedFileTypes(ANY_FILE))
           .add(attr("main_dex_classes", LABEL).mandatory().cfg(HOST).allowedFileTypes(ANY_FILE))
           .add(attr("apkbuilder", LABEL).mandatory().cfg(HOST).allowedFileTypes(ANY_FILE).exec())
@@ -340,19 +342,22 @@ public final class AndroidRuleClasses {
                   .cfg(HOST)
                   .allowedFileTypes(ANY_FILE)
                   .exec()
-                  .value(environment.getLabel("//tools/android/jack:jack")))
+                  .value(environment.getLabel(
+                      Constants.TOOLS_REPOSITORY + "//tools/android/jack:jack")))
           .add(
               attr("jill", LABEL)
                   .cfg(HOST)
                   .allowedFileTypes(ANY_FILE)
                   .exec()
-                  .value(environment.getLabel("//tools/android/jack:jill")))
+                  .value(environment.getLabel(
+                      Constants.TOOLS_REPOSITORY + "//tools/android/jack:jill")))
           .add(
               attr("resource_extractor", LABEL)
                   .cfg(HOST)
                   .allowedFileTypes(ANY_FILE)
                   .exec()
-                  .value(environment.getLabel("//tools/android/jack:resource_extractor")))
+                  .value(environment.getLabel(
+                      Constants.TOOLS_REPOSITORY + "//tools/android/jack:resource_extractor")))
           .build();
     }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfigurationLoader.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfigurationLoader.java
index a68b800bd4..3604f58115 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfigurationLoader.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfigurationLoader.java
@@ -119,7 +119,7 @@ public class CppConfigurationLoader implements ConfigurationFragmentFactory {
       return null;
     }
     Label crosstoolTopLabel = RedirectChaser.followRedirects(env,
-        options.get(CppOptions.class).crosstoolTop, "crosstool_top");
+        options.get(CppOptions.class).crosstoolTop(), "crosstool_top");
     if (crosstoolTopLabel == null) {
       return null;
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java
index 6c550d0f9c..e76fb265bb 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java
@@ -19,6 +19,7 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Multimap;
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration.LabelConverter;
 import com.google.devtools.build.lib.analysis.config.CompilationMode;
@@ -170,7 +171,7 @@ public class CppOptions extends FragmentOptions {
   public boolean lipoCollector;
 
   @Option(name = "crosstool_top",
-          defaultValue = CppOptions.DEFAULT_CROSSTOOL_TARGET,
+          defaultValue = "null",
           category = "version",
           converter = LabelConverter.class,
           help = "The label of the crosstool package to be used for compiling C++ code.")
@@ -502,6 +503,12 @@ public class CppOptions extends FragmentOptions {
           + "will be shared among different targets")
   public boolean shareNativeDeps;
 
+  public Label crosstoolTop() {
+    return crosstoolTop == null
+        ? Label.parseAbsoluteUnchecked(Constants.TOOLS_REPOSITORY + DEFAULT_CROSSTOOL_TARGET)
+        : crosstoolTop;
+  }
+
   @Override
   public FragmentOptions getHost(boolean fallback) {
     CppOptions host = (CppOptions) getDefault();
@@ -544,7 +551,7 @@ public class CppOptions extends FragmentOptions {
 
   @Override
   public void addAllLabels(Multimap<String, Label> labelMap) {
-    labelMap.put("crosstool", crosstoolTop);
+    labelMap.put("crosstool", crosstoolTop());
     if (hostCrosstoolTop != null) {
       labelMap.put("crosstool", hostCrosstoolTop);
     }
@@ -573,7 +580,7 @@ public class CppOptions extends FragmentOptions {
   @Override
   public Map<String, Set<Label>> getDefaultsLabels(BuildConfiguration.Options commonOptions) {
     Set<Label> crosstoolLabels = new LinkedHashSet<>();
-    crosstoolLabels.add(crosstoolTop);
+    crosstoolLabels.add(crosstoolTop());
     if (hostCrosstoolTop != null) {
       crosstoolLabels.add(hostCrosstoolTop);
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaOptions.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaOptions.java
index 361e95f505..633439d4d5 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaOptions.java
@@ -16,7 +16,9 @@ package com.google.devtools.build.lib.rules.java;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Multimap;
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration;
+import com.google.devtools.build.lib.analysis.config.BuildConfiguration.DefaultLabelConverter;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration.LabelConverter;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration.StrictDepsConverter;
 import com.google.devtools.build.lib.analysis.config.BuildConfiguration.StrictDepsMode;
@@ -25,9 +27,11 @@ import com.google.devtools.build.lib.analysis.config.FragmentOptions;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.rules.java.JavaConfiguration.JavaClasspathMode;
+import com.google.devtools.common.options.Converter;
 import com.google.devtools.common.options.Converters.StringSetConverter;
 import com.google.devtools.common.options.EnumConverter;
 import com.google.devtools.common.options.Option;
+import com.google.devtools.common.options.OptionsParsingException;
 import com.google.devtools.common.options.TriState;
 
 import java.util.HashMap;
@@ -40,16 +44,77 @@ import java.util.Set;
  * Command-line options for building Java targets
  */
 public class JavaOptions extends FragmentOptions {
-  // Defaults value for options
   public static final String DEFAULT_LANGTOOLS = "//tools/jdk:langtools";
-  static final String DEFAULT_LANGTOOLS_BOOTCLASSPATH = "//tools/jdk:bootclasspath";
-  static final String DEFAULT_LANGTOOLS_EXTDIR = "//tools/jdk:extdir";
-  static final String DEFAULT_JAVABUILDER = "//tools/jdk:JavaBuilder_deploy.jar";
-  static final String DEFAULT_SINGLEJAR = "//tools/jdk:SingleJar_deploy.jar";
-  static final String DEFAULT_GENCLASS = "//tools/jdk:GenClass_deploy.jar";
-  static final String DEFAULT_JAVABASE = "//tools/jdk:jdk";
-  static final String DEFAULT_IJAR = "//tools/jdk:ijar";
-  static final String DEFAULT_TOOLCHAIN = "//tools/jdk:toolchain";
+
+  /** Converter for --javabase and --host_javabase. */
+  public static class JavabaseConverter implements Converter<String> {
+    @Override
+    public String convert(String input) throws OptionsParsingException {
+      return input.isEmpty() ? Constants.TOOLS_REPOSITORY + "//tools/jdk:jdk" : input;
+    }
+
+    @Override
+    public String getTypeDescription() {
+      return "a string";
+    }
+  }
+
+  /** Converter for --java_langtools. */
+  public static class LangtoolsConverter extends DefaultLabelConverter {
+    public LangtoolsConverter() {
+      super(Constants.TOOLS_REPOSITORY + DEFAULT_LANGTOOLS);
+    }
+  }
+
+  /** Converter for --javac_bootclasspath. */
+  public static class BootclasspathConverter extends DefaultLabelConverter {
+    public BootclasspathConverter() {
+      super(Constants.TOOLS_REPOSITORY + "//tools/jdk:bootclasspath");
+    }
+  }
+
+  /** Converter for --javac_extdir. */
+  public static class ExtdirConverter extends DefaultLabelConverter {
+    public ExtdirConverter() {
+      super(Constants.TOOLS_REPOSITORY + "//tools/jdk:extdir");
+    }
+  }
+
+  /** Converter for --javabuilder_top. */
+  public static class JavaBuilderConverter extends DefaultLabelConverter {
+    public JavaBuilderConverter() {
+      super(Constants.TOOLS_REPOSITORY + "//tools/jdk:JavaBuilder_deploy.jar");
+    }
+  }
+
+
+  /** Converter for --singlejar_top. */
+  public static class SingleJarConverter extends DefaultLabelConverter {
+    public SingleJarConverter() {
+      super(Constants.TOOLS_REPOSITORY + "//tools/jdk:SingleJar_deploy.jar");
+    }
+  }
+
+  /** Converter for --genclass_top. */
+  public static class GenClassConverter extends DefaultLabelConverter {
+    public GenClassConverter() {
+      super(Constants.TOOLS_REPOSITORY + "//tools/jdk:GenClass_deploy.jar");
+    }
+  }
+
+  /** Converter for --ijar_top. */
+  public static class IjarConverter extends DefaultLabelConverter {
+    public IjarConverter() {
+      super(Constants.TOOLS_REPOSITORY + "//tools/jdk:ijar");
+    }
+  }
+
+  /** Converter for --java_toolchain. */
+  public static class JavaToolchainConverter extends DefaultLabelConverter {
+    public JavaToolchainConverter() {
+      super(Constants.TOOLS_REPOSITORY + "//tools/jdk:toolchain");
+    }
+  }
 
   /**
    * Converter for the --javawarn option.
@@ -98,7 +163,8 @@ public class JavaOptions extends FragmentOptions {
   }
 
   @Option(name = "javabase",
-      defaultValue = DEFAULT_JAVABASE,
+      defaultValue = "",
+      converter = JavabaseConverter.class,
       category = "version",
       help = "JAVABASE used for the JDK invoked by Blaze. This is the "
           + "JAVABASE which will be used to execute external Java "
@@ -106,17 +172,18 @@ public class JavaOptions extends FragmentOptions {
   public String javaBase;
 
   @Option(name = "java_toolchain",
-      defaultValue = DEFAULT_TOOLCHAIN,
+      defaultValue = "",
       category = "version",
-      converter = LabelConverter.class,
-      help = "The name of the toolchain rule for Java. Default is " + DEFAULT_TOOLCHAIN)
+      converter = JavaToolchainConverter.class,
+      help = "The name of the toolchain rule for Java.")
   public Label javaToolchain;
 
   @Option(name = "host_javabase",
-    defaultValue = DEFAULT_JAVABASE,
-    category = "version",
-    help = "JAVABASE used for the host JDK. This is the JAVABASE which is used to execute "
-         + " tools during a build.")
+      defaultValue = "",
+      converter = JavabaseConverter.class,
+      category = "version",
+      help = "JAVABASE used for the host JDK. This is the JAVABASE which is used to execute "
+           + " tools during a build.")
   public String hostJavaBase;
 
   @Option(name = "javacopt",
@@ -206,9 +273,9 @@ public class JavaOptions extends FragmentOptions {
   public StrictDepsMode strictJavaDeps;
 
   @Option(name = "javabuilder_top",
-      defaultValue = DEFAULT_JAVABUILDER,
+      defaultValue = "",
       category = "version",
-      converter = LabelConverter.class,
+      converter = JavaBuilderConverter.class,
       help = "Label of the filegroup that contains the JavaBuilder jar.")
   public Label javaBuilderTop;
 
@@ -220,44 +287,44 @@ public class JavaOptions extends FragmentOptions {
   public List<String> javaBuilderJvmOpts;
 
   @Option(name = "singlejar_top",
-      defaultValue = DEFAULT_SINGLEJAR,
+      defaultValue = "",
       category = "version",
-      converter = LabelConverter.class,
+      converter = SingleJarConverter.class,
       help = "Label of the filegroup that contains the SingleJar jar.")
   public Label singleJarTop;
 
   @Option(name = "genclass_top",
-      defaultValue = DEFAULT_GENCLASS,
+      defaultValue = "",
       category = "version",
-      converter = LabelConverter.class,
+      converter = GenClassConverter.class,
       help = "Label of the filegroup that contains the GenClass jar.")
   public Label genClassTop;
 
   @Option(name = "ijar_top",
-      defaultValue = DEFAULT_IJAR,
+      defaultValue = "",
       category = "version",
-      converter = LabelConverter.class,
+      converter = IjarConverter.class,
       help = "Label of the filegroup that contains the ijar binary.")
   public Label iJarTop;
 
   @Option(name = "java_langtools",
-      defaultValue = DEFAULT_LANGTOOLS,
+      defaultValue = "",
       category = "version",
-      converter = LabelConverter.class,
+      converter = LangtoolsConverter.class,
       help = "Label of the rule that produces the Java langtools jar.")
   public Label javaLangtoolsJar;
 
   @Option(name = "javac_bootclasspath",
-      defaultValue = DEFAULT_LANGTOOLS_BOOTCLASSPATH,
+      defaultValue = "",
       category = "version",
-      converter = LabelConverter.class,
+      converter = BootclasspathConverter.class,
       help = "Label of the rule that produces the bootclasspath jars for javac to use.")
   public Label javacBootclasspath;
 
   @Option(name = "javac_extdir",
-      defaultValue = DEFAULT_LANGTOOLS_EXTDIR,
+      defaultValue = "",
       category = "version",
-      converter = LabelConverter.class,
+      converter = ExtdirConverter.class,
       help = "Label of the rule that produces the extdir for javac to use.")
   public Label javacExtdir;
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaSemantics.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaSemantics.java
index d616d2af66..a75b414ef1 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaSemantics.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaSemantics.java
@@ -18,6 +18,7 @@ import static com.google.devtools.build.lib.packages.ImplicitOutputsFunction.fro
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.LanguageDependentFragment.LibraryLanguage;
 import com.google.devtools.build.lib.analysis.OutputGroupProvider;
@@ -79,7 +80,8 @@ public interface JavaSemantics {
   /**
    * Label to the Java Toolchain rule. It is resolved from a label given in the java options.
    */
-  static final String JAVA_TOOLCHAIN_LABEL = "//tools/defaults:java_toolchain";
+  static final String JAVA_TOOLCHAIN_LABEL =
+      Constants.TOOLS_REPOSITORY + "//tools/defaults:java_toolchain";
 
   public static final LateBoundLabel<BuildConfiguration> JAVA_TOOLCHAIN =
       new LateBoundLabel<BuildConfiguration>(JAVA_TOOLCHAIN_LABEL, JavaConfiguration.class) {
@@ -106,33 +108,39 @@ public interface JavaSemantics {
    * Label of a pseudo-filegroup that contains all jdk files for all
    * configurations, as specified on the command-line.
    */
-  public static final String JDK_LABEL = "//tools/defaults:jdk";
+  public static final String JDK_LABEL =
+      Constants.TOOLS_REPOSITORY + "//tools/defaults:jdk";
 
   /**
    * Label of a pseudo-filegroup that contains the boot-classpath entries.
    */
-  public static final String JAVAC_BOOTCLASSPATH_LABEL = "//tools/defaults:javac_bootclasspath";
+  public static final String JAVAC_BOOTCLASSPATH_LABEL =
+      Constants.TOOLS_REPOSITORY + "//tools/defaults:javac_bootclasspath";
 
   /**
    * Label of the javac extdir used for compiling Java source code.
    */
-  public static final String JAVAC_EXTDIR_LABEL = "//tools/defaults:javac_extdir";
+  public static final String JAVAC_EXTDIR_LABEL =
+      Constants.TOOLS_REPOSITORY + "//tools/defaults:javac_extdir";
 
   /**
    * Label of the JavaBuilder JAR used for compiling Java source code.
    */
-  public static final String JAVABUILDER_LABEL = "//tools/defaults:javabuilder";
+  public static final String JAVABUILDER_LABEL =
+      Constants.TOOLS_REPOSITORY + "//tools/defaults:javabuilder";
 
   /**
    * Label of the SingleJar JAR used for creating deploy jars.
    */
-  public static final String SINGLEJAR_LABEL = "//tools/defaults:singlejar";
+  public static final String SINGLEJAR_LABEL =
+      Constants.TOOLS_REPOSITORY + "//tools/defaults:singlejar";
 
   /**
    * Label of the GenClass JAR used for creating the jar for classes from sources generated from
    * annotation processors.
    */
-  public static final String GENCLASS_LABEL = "//tools/defaults:genclass";
+  public static final String GENCLASS_LABEL =
+      Constants.TOOLS_REPOSITORY + "//tools/defaults:genclass";
 
   /**
    * Label of pseudo-cc_binary that tells Blaze a java target's JAVABIN is never to be replaced by
@@ -188,7 +196,7 @@ public interface JavaSemantics {
         }
       };
 
-  public static final String IJAR_LABEL = "//tools/defaults:ijar";
+  public static final String IJAR_LABEL = Constants.TOOLS_REPOSITORY + "//tools/defaults:ijar";
 
   /**
    * Verifies if the rule contains and errors.
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/BazelJ2ObjcProtoAspect.java b/src/main/java/com/google/devtools/build/lib/rules/objc/BazelJ2ObjcProtoAspect.java
index 8d692e562c..2da029c7ad 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/BazelJ2ObjcProtoAspect.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/BazelJ2ObjcProtoAspect.java
@@ -19,6 +19,7 @@ import static com.google.devtools.build.lib.packages.Attribute.attr;
 import static com.google.devtools.build.lib.packages.BuildType.LABEL;
 
 import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.ConfiguredTarget;
 import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
@@ -42,11 +43,11 @@ public class BazelJ2ObjcProtoAspect extends AbstractJ2ObjcProtoAspect {
         .add(attr("$protoc_darwin", LABEL)
             .cfg(HOST)
             .exec()
-            .value(parseLabel("//tools/objc:compile_protos")))
+            .value(parseLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:compile_protos")))
         .add(attr("$protoc_support_darwin", LABEL)
             .cfg(HOST)
             .exec()
-            .value(parseLabel("//tools/objc:proto_support")))
+            .value(parseLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:proto_support")))
         .add(attr("$j2objc_plugin", LABEL)
             .cfg(HOST)
             .exec()
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ExperimentalIosTestRule.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ExperimentalIosTestRule.java
index a7b81dcc07..1769a9c05b 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ExperimentalIosTestRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ExperimentalIosTestRule.java
@@ -21,6 +21,7 @@ import static com.google.devtools.build.lib.packages.BuildType.LABEL_LIST;
 import static com.google.devtools.build.lib.syntax.Type.STRING_LIST;
 
 import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
@@ -62,7 +63,8 @@ public final class ExperimentalIosTestRule implements RuleDefinition {
             attr(IosTest.TARGET_DEVICE, LABEL)
                 .allowedFileTypes()
                 .allowedRuleClasses("ios_device")
-                .value(env.getLabel("//tools/objc/sim_devices:default")))
+                .value(env.getLabel(
+                    Constants.TOOLS_REPOSITORY + "//tools/objc/sim_devices:default")))
         /* <!-- #BLAZE_RULE(experimental_ios_test).ATTRIBUTE(ios_test_target_device) -->
          The device against how to run the test. If this attribute is defined, the test will run on
          the lab device. Otherwise, the test will run on simulator.
@@ -85,8 +87,10 @@ public final class ExperimentalIosTestRule implements RuleDefinition {
          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
         .add(attr("plugins", LABEL_LIST).allowedFileTypes(FileType.of("_deploy.jar")))
         .add(attr("$test_template", LABEL)
-            .value(env.getLabel("//tools/objc:ios_test.sh.bazel_template")))
-        .add(attr("$test_runner", LABEL).value(env.getLabel("//tools/objc:testrunner")))
+            .value(env.getLabel(
+                Constants.TOOLS_REPOSITORY + "//tools/objc:ios_test.sh.bazel_template")))
+        .add(attr("$test_runner", LABEL).value(env.getLabel(
+            Constants.TOOLS_REPOSITORY + "//tools/objc:testrunner")))
         .override(attr(":gcov", LABEL_LIST).cfg(HOST)
             .value(new LateBoundLabelList<BuildConfiguration>() {
               @Override
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/IosApplicationRule.java b/src/main/java/com/google/devtools/build/lib/rules/objc/IosApplicationRule.java
index 363219f0f8..f25d457176 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/IosApplicationRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/IosApplicationRule.java
@@ -20,6 +20,7 @@ import static com.google.devtools.build.lib.packages.BuildType.LABEL;
 import static com.google.devtools.build.lib.packages.BuildType.LABEL_LIST;
 import static com.google.devtools.build.lib.syntax.Type.BOOLEAN;
 
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
@@ -65,7 +66,8 @@ public class IosApplicationRule implements RuleDefinition {
             .allowedFileTypes()
             .direct_compile_time_input())
         .add(attr("$runner_script_template", LABEL).cfg(HOST)
-            .value(env.getLabel("//tools/objc:ios_runner.sh.mac_template")))
+            .value(env.getLabel(
+                Constants.TOOLS_REPOSITORY + "//tools/objc:ios_runner.sh.mac_template")))
         .add(attr("$is_executable", BOOLEAN).value(true)
             .nonconfigurable("Called from RunCommand.isExecutable, which takes a Target"))
         .build();
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java
index 4a6a7f182f..f6a527bde6 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/J2ObjcAspect.java
@@ -21,6 +21,7 @@ import static java.nio.charset.StandardCharsets.ISO_8859_1;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.actions.ParameterFile;
 import com.google.devtools.build.lib.analysis.Aspect;
@@ -70,13 +71,13 @@ public class J2ObjcAspect implements ConfiguredAspectFactory {
         .requireProvider(JavaSourceInfoProvider.class)
         .requireProvider(JavaCompilationArgsProvider.class)
         .add(attr("$j2objc", LABEL).cfg(HOST).exec()
-            .value(parseLabel("//tools/j2objc:j2objc_deploy.jar")))
+            .value(parseLabel(Constants.TOOLS_REPOSITORY + "//tools/j2objc:j2objc_deploy.jar")))
         .add(attr("$j2objc_wrapper", LABEL)
             .allowedFileTypes(FileType.of(".py"))
             .cfg(HOST)
             .exec()
             .singleArtifact()
-            .value(parseLabel("//tools/j2objc:j2objc_wrapper")))
+            .value(parseLabel(Constants.TOOLS_REPOSITORY + "//tools/j2objc:j2objc_wrapper")))
         .build();
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBinaryRule.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBinaryRule.java
index bb34419929..deeb5aca5f 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBinaryRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcBinaryRule.java
@@ -19,6 +19,7 @@ import static com.google.devtools.build.lib.packages.Attribute.attr;
 import static com.google.devtools.build.lib.packages.BuildType.LABEL;
 import static com.google.devtools.build.lib.syntax.Type.BOOLEAN;
 
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
@@ -49,7 +50,8 @@ public class ObjcBinaryRule implements RuleDefinition {
             ImplicitOutputsFunction.fromFunctions(ReleaseBundlingSupport.IPA, XcodeSupport.PBXPROJ))
         // TODO(bazel-team): Remove these when this rule no longer produces a bundle.
         .add(attr("$runner_script_template", LABEL).cfg(HOST)
-            .value(env.getLabel("//tools/objc:ios_runner.sh.mac_template")))
+            .value(env.getLabel(
+                Constants.TOOLS_REPOSITORY + "//tools/objc:ios_runner.sh.mac_template")))
         .add(attr("$is_executable", BOOLEAN).value(true)
             .nonconfigurable("Called from RunCommand.isExecutable, which takes a Target"))
         .build();
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommandLineOptions.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommandLineOptions.java
index f88ce4fbdb..d30cc92cdb 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommandLineOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommandLineOptions.java
@@ -17,7 +17,8 @@ package com.google.devtools.build.lib.rules.objc;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Multimap;
-import com.google.devtools.build.lib.analysis.config.BuildConfiguration.LabelConverter;
+import com.google.devtools.build.lib.Constants;
+import com.google.devtools.build.lib.analysis.config.BuildConfiguration.DefaultLabelConverter;
 import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.analysis.config.FragmentOptions;
 import com.google.devtools.build.lib.cmdline.Label;
@@ -33,6 +34,20 @@ import java.util.List;
  * Command-line options for building Objective-C targets.
  */
 public class ObjcCommandLineOptions extends FragmentOptions {
+  /** Converter for --objc_dump_syms_binary. */
+  public static class DumpSymsConverter extends DefaultLabelConverter {
+    public DumpSymsConverter() {
+      super(Constants.TOOLS_REPOSITORY + "//tools/objc:dump_syms");
+    }
+  }
+
+  /** Converter for --default_ios_provisioning_profile. */
+  public static class DefaultProvisioningProfileConverter extends DefaultLabelConverter {
+    public DefaultProvisioningProfileConverter() {
+      super(Constants.TOOLS_REPOSITORY + "//tools/objc:default_provisioning_profile");
+    }
+  }
+
   // TODO(cparsons): Validate version flag value.
   @Option(name = "xcode_version",
       defaultValue = "",
@@ -114,15 +129,15 @@ public class ObjcCommandLineOptions extends FragmentOptions {
   public String iosSplitCpu;
 
   @Option(name = "objc_dump_syms_binary",
-      defaultValue = "//tools/objc:dump_syms",
+      defaultValue = "",
       category = "undocumented",
-      converter = LabelConverter.class)
+      converter = DumpSymsConverter.class)
   public Label dumpSyms;
 
   @Option(name = "default_ios_provisiong_profile",
-      defaultValue = "//tools/objc:default_provisioning_profile",
+      defaultValue = "",
       category = "undocumented",
-      converter = LabelConverter.class)
+      converter = DefaultProvisioningProfileConverter.class)
   public Label defaultProvisioningProfile;
 
   @Option(name = "objc_per_proto_includes",
@@ -206,6 +221,7 @@ public class ObjcCommandLineOptions extends FragmentOptions {
         IosApplication.SPLIT_ARCH_TRANSITION, IosExtension.MINIMUM_OS_AND_SPLIT_ARCH_TRANSITION);
   }
 
+  /** Converter for the iOS configuration distinguisher. */
   public static final class ConfigurationDistinguisherConverter
       extends EnumConverter<ConfigurationDistinguisher> {
     public ConfigurationDistinguisherConverter() {
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProtoLibraryRule.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProtoLibraryRule.java
index 1374c35d79..03ea73d953 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProtoLibraryRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProtoLibraryRule.java
@@ -21,6 +21,7 @@ import static com.google.devtools.build.lib.packages.BuildType.LABEL;
 import static com.google.devtools.build.lib.packages.BuildType.LABEL_LIST;
 import static com.google.devtools.build.lib.syntax.Type.BOOLEAN;
 
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
@@ -81,11 +82,11 @@ public class ObjcProtoLibraryRule implements RuleDefinition {
             .allowedFileTypes(FileType.of(".py"))
             .cfg(HOST)
             .singleArtifact()
-            .value(env.getLabel("//tools/objc:compile_protos")))
+            .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:compile_protos")))
         .add(attr(PROTO_SUPPORT_ATTR, LABEL)
             .legacyAllowAnyFileType()
             .cfg(HOST)
-            .value(env.getLabel("//tools/objc:proto_support")))
+            .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:proto_support")))
         .add(attr(USE_OBJC_HEADER_NAMES_ATTR, BOOLEAN).value(false))
         .add(attr(LIBPROTOBUF_ATTR, LABEL).allowedRuleClasses("objc_library")
             .value(new ComputedDefault(OUTPUT_CPP_ATTR) {
@@ -97,7 +98,7 @@ public class ObjcProtoLibraryRule implements RuleDefinition {
               }
             }))
         .add(attr("$xcodegen", LABEL).cfg(HOST).exec()
-            .value(env.getLabel("//tools/objc:xcodegen")))
+            .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:xcodegen")))
         .build();
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java
index e21a9755d5..082603d5a9 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java
@@ -26,6 +26,7 @@ import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.Constants;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
 import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
@@ -497,15 +498,15 @@ public class ObjcRuleClasses {
     public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
       return builder
           .add(attr("$plmerge", LABEL).cfg(HOST).exec()
-              .value(env.getLabel("//tools/objc:plmerge")))
+              .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:plmerge")))
           .add(attr("$actoolwrapper", LABEL).cfg(HOST).exec()
-              .value(env.getLabel("//tools/objc:actoolwrapper")))
+              .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:actoolwrapper")))
           .add(attr("$ibtoolwrapper", LABEL).cfg(HOST).exec()
-              .value(env.getLabel("//tools/objc:ibtoolwrapper")))
+              .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:ibtoolwrapper")))
           // TODO(dmaclach): Adding realpath here should not be required once
           // https://github.com/bazelbuild/bazel/issues/285 is fixed.
           .add(attr("$realpath", LABEL).cfg(HOST).exec()
-              .value(env.getLabel("//tools/objc:realpath")))
+              .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:realpath")))
           .build();
     }
     @Override
@@ -525,9 +526,9 @@ public class ObjcRuleClasses {
     public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
       return builder
           .add(attr("$xcodegen", LABEL).cfg(HOST).exec()
-              .value(env.getLabel("//tools/objc:xcodegen")))
+              .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:xcodegen")))
           .add(attr("$dummy_source", LABEL)
-              .value(env.getLabel("//tools/objc:dummy.c")))
+              .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:dummy.c")))
           .build();
     }
     @Override
@@ -771,7 +772,8 @@ public class ObjcRuleClasses {
               .cfg(HOST)
               .exec()
               .singleArtifact()
-              .value(env.getLabel("//tools/objc:j2objc_dead_code_pruner")))
+              .value(env.getLabel(
+                  Constants.TOOLS_REPOSITORY + "//tools/objc:j2objc_dead_code_pruner")))
         .build();
     }
     @Override
@@ -818,7 +820,7 @@ public class ObjcRuleClasses {
                         @Override
                         public Object getDefault(AttributeMap rule) {
                           return rule.get(IosTest.IS_XCTEST, Type.BOOLEAN)
-                              ? env.getLabel("//tools/objc:xctest_app")
+                              ? env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:xctest_app")
                               : null;
                         }
                       })
@@ -832,7 +834,8 @@ public class ObjcRuleClasses {
                         @Override
                         public Object getDefault(AttributeMap rule) {
                           return rule.get(IosTest.IS_XCTEST, Type.BOOLEAN)
-                              ? env.getLabel("//tools/objc:xctest_infoplist")
+                              ? env.getLabel(
+                                  Constants.TOOLS_REPOSITORY + "//tools/objc:xctest_infoplist")
                               : null;
                         }
                       })
@@ -890,9 +893,10 @@ public class ObjcRuleClasses {
         .add(attr("families", STRING_LIST)
              .value(ImmutableList.of(TargetDeviceFamily.IPHONE.getNameInRule())))
         .add(attr("$momcwrapper", LABEL).cfg(HOST).exec()
-            .value(env.getLabel("//tools/objc:momcwrapper")))
+            .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:momcwrapper")))
         .add(attr("$swiftstdlibtoolwrapper", LABEL).cfg(HOST).exec()
-            .value(env.getLabel("//tools/objc:swiftstdlibtoolwrapper")))
+            .value(env.getLabel(
+                Constants.TOOLS_REPOSITORY + "//tools/objc:swiftstdlibtoolwrapper")))
         .build();
     }
     @Override
@@ -997,9 +1001,10 @@ public class ObjcRuleClasses {
                 }
               }))
           .add(attr("$bundlemerge", LABEL).cfg(HOST).exec()
-              .value(env.getLabel("//tools/objc:bundlemerge")))
+              .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:bundlemerge")))
           .add(attr("$environment_plist_sh", LABEL).cfg(HOST)
-              .value(env.getLabel("//tools/objc:environment_plist.sh")))
+              .value(env.getLabel(
+                  Constants.TOOLS_REPOSITORY + "//tools/objc:environment_plist.sh")))
           .build();
     }
     @Override
@@ -1023,7 +1028,7 @@ public class ObjcRuleClasses {
           .add(attr("$iossim", LABEL).cfg(HOST).exec()
               .value(env.getLabel("//third_party/iossim:iossim")))
           .add(attr("$std_redirect_dylib", LABEL).cfg(HOST).exec()
-              .value(env.getLabel("//tools/objc:StdRedirect.dylib")))
+              .value(env.getLabel(Constants.TOOLS_REPOSITORY + "//tools/objc:StdRedirect.dylib")))
           .build();
     }
     @Override
diff --git a/src/main/java/com/google/devtools/build/lib/rules/python/PythonConfigurationLoader.java b/src/main/java/com/google/devtools/build/lib/rules/python/PythonConfigurationLoader.java
index 2599cb139d..917576d879 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/python/PythonConfigurationLoader.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/python/PythonConfigurationLoader.java
@@ -67,7 +67,7 @@ public class PythonConfigurationLoader implements ConfigurationFragmentFactory {
     }
 
     CrosstoolConfig.CToolchain toolchain = getToolchain(
-        env, buildOptions, buildOptions.get(CppOptions.class).crosstoolTop);
+        env, buildOptions, buildOptions.get(CppOptions.class).crosstoolTop());
     if (toolchain == null) {
       return null;
     }