C++: Change Skylark API whitelisting to be part of flag.

This uses SkylarkSemantics now instead of the C++ configuration. The flag is:
--experimental_cc_skylark_api_enabled_packages

RELNOTES:none
PiperOrigin-RevId: 207235431

13 files changed, 87 insertions, 84 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/bazel/rules/cpp/BazelCcModule.java b/src/main/java/com/google/devtools/build/lib/bazel/rules/cpp/BazelCcModule.java
index 3b3d944e74..0195eda845 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/cpp/BazelCcModule.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/cpp/BazelCcModule.java
@@ -36,8 +36,8 @@ import com.google.devtools.build.lib.syntax.SkylarkList;
 /**
  * A module that contains Skylark utilities for C++ support.
  *
- * <p>This is a work in progress. The API is guarded behind --experimental_enable_cc_skylark_api.
- * The API is under development and unstable.
+ * <p>This is a work in progress. The API is guarded behind
+ * --experimental_cc_skylark_api_enabled_packages. The API is under development and unstable.
  */
 public class BazelCcModule extends CcModule
     implements BazelCcModuleApi<
diff --git a/src/main/java/com/google/devtools/build/lib/packages/SkylarkSemanticsOptions.java b/src/main/java/com/google/devtools/build/lib/packages/SkylarkSemanticsOptions.java
index e48c1be9fa..3277c38440 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/SkylarkSemanticsOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/SkylarkSemanticsOptions.java
@@ -15,12 +15,14 @@
 package com.google.devtools.build.lib.packages;
 
 import com.google.devtools.build.lib.syntax.SkylarkSemantics;
+import com.google.devtools.common.options.Converters.CommaSeparatedOptionListConverter;
 import com.google.devtools.common.options.Option;
 import com.google.devtools.common.options.OptionDocumentationCategory;
 import com.google.devtools.common.options.OptionEffectTag;
 import com.google.devtools.common.options.OptionMetadataTag;
 import com.google.devtools.common.options.OptionsBase;
 import java.io.Serializable;
+import java.util.List;
 
 /**
  * Contains options that affect Skylark's semantics.
@@ -41,9 +43,6 @@ import java.io.Serializable;
  *       should be that name written in snake_case. Add a line to set the new field in {@link
  *       #toSkylarkSemantics}.
  *
- *   <li>Add a line to read and write the new field in {@link SkylarkSemanticsCodec#serialize} and
- *       {@link SkylarkSemanticsCodec#deserialize}.
- *
  *   <li>Add a line to set the new field in both {@link
  *       SkylarkSemanticsConsistencyTest#buildRandomOptions} and {@link
  *       SkylarkSemanticsConsistencyTest#buildRandomSemantics}.
@@ -69,6 +68,18 @@ public class SkylarkSemanticsOptions extends OptionsBase implements Serializable
   public boolean experimentalEnableRepoMapping;
 
   @Option(
+      name = "experimental_cc_skylark_api_enabled_packages",
+      converter = CommaSeparatedOptionListConverter.class,
+      defaultValue = "",
+      documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
+      effectTags = {OptionEffectTag.LOADING_AND_ANALYSIS},
+      metadataTags = {OptionMetadataTag.EXPERIMENTAL},
+      help =
+          "Passes list of packages that can use the C++ Skylark API. Don't enable this flag yet, "
+              + "we will be making breaking changes.")
+  public List<String> experimentalCcSkylarkApiEnabledPackages;
+
+  @Option(
     name = "incompatible_bzl_disallow_load_after_statement",
     defaultValue = "false",
     documentationCategory = OptionDocumentationCategory.UNCATEGORIZED,
@@ -350,6 +361,7 @@ public class SkylarkSemanticsOptions extends OptionsBase implements Serializable
   public SkylarkSemantics toSkylarkSemantics() {
     return SkylarkSemantics.builder()
         // <== Add new options here in alphabetic order ==>
+        .experimentalCcSkylarkApiEnabledPackages(experimentalCcSkylarkApiEnabledPackages)
         .experimentalEnableRepoMapping(experimentalEnableRepoMapping)
         .incompatibleBzlDisallowLoadAfterStatement(incompatibleBzlDisallowLoadAfterStatement)
         .incompatibleDepsetIsNotIterable(incompatibleDepsetIsNotIterable)
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCommon.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCommon.java
index b6c55be56c..9fc2f5e029 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCommon.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCommon.java
@@ -57,6 +57,7 @@ import com.google.devtools.build.lib.shell.ShellUtils;
 import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
 import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec.VisibleForSerialization;
 import com.google.devtools.build.lib.syntax.EvalException;
+import com.google.devtools.build.lib.syntax.SkylarkSemantics;
 import com.google.devtools.build.lib.syntax.Type;
 import com.google.devtools.build.lib.util.FileType;
 import com.google.devtools.build.lib.util.Pair;
@@ -108,10 +109,6 @@ public final class CcCommon {
     }
   };
 
-  private static final ImmutableList<PathFragment> WHITELISTED_PACKAGES =
-      ImmutableList.of(
-          PathFragment.create("tools/build_defs"), PathFragment.create("experimental"));
-
   public static final ImmutableSet<String> ALL_COMPILE_ACTIONS =
       ImmutableSet.of(
           CppActionNames.C_COMPILE,
@@ -209,40 +206,44 @@ public final class CcCommon {
       throws EvalException {
     RuleContext context = skylarkRuleContext.getRuleContext();
     Rule rule = context.getRule();
-    if (!context.getFragment(CppConfiguration.class).getEnableCcSkylarkApi()) {
-      throw new EvalException(
-          rule.getLocation(),
-          "Pass --experimental_enable_cc_skylark_api in "
-              + "order to use the C++ API. Beware that we will be making breaking "
-              + "changes to this API without prior warning.");
-    }
+
     RuleClass ruleClass = rule.getRuleClassObject();
     Label label = ruleClass.getRuleDefinitionEnvironmentLabel();
-    if (label != null
-        && WHITELISTED_PACKAGES
-            .stream()
-            .noneMatch(path -> label.getPackageFragment().startsWith(path))) {
-      throwWhiteListError(rule.getLocation(), label.getPackageFragment().toString());
+    try {
+      if (label != null) {
+        checkLocationWhitelisted(
+            context.getAnalysisEnvironment().getSkylarkSemantics(),
+            rule.getLocation(),
+            label.getPackageFragment().toString());
+      }
+    } catch (InterruptedException e) {
+      throw new EvalException(rule.getLocation(), e);
     }
   }
 
-  public static void checkLocationWhitelisted(Location location) throws EvalException {
-    String bzlPath = location.getPath().toString();
-    if (WHITELISTED_PACKAGES.stream().noneMatch(path -> bzlPath.contains(path.toString()))) {
-      throwWhiteListError(location, bzlPath);
+  public static void checkLocationWhitelisted(
+      SkylarkSemantics semantics, Location location, String callPath) throws EvalException {
+    List<String> whitelistedPackagesList = semantics.experimentalCcSkylarkApiEnabledPackages();
+    if (whitelistedPackagesList
+        .stream()
+        .noneMatch(
+            path -> callPath.startsWith(path) || callPath.startsWith("/workspace/" + path))) {
+      throwWhiteListError(location, callPath, whitelistedPackagesList);
     }
   }
 
-  private static void throwWhiteListError(Location location, String bzlPath) throws EvalException {
-    String whitelistedPackages =
-        WHITELISTED_PACKAGES.stream().map(p -> p.toString()).collect(Collectors.joining(", "));
+  private static void throwWhiteListError(
+      Location location, String callPath, List<String> whitelistedPackagesList)
+      throws EvalException {
+    String whitelistedPackages = whitelistedPackagesList.stream().collect(Collectors.joining(", "));
     throw new EvalException(
         location,
         String.format(
-            "the C++ Skylark API is for the time being only allowed for rules in in '//%s/...'; "
-                + "but this is defined in '//%s'. Contact blaze-rules@google.com for more "
-                + "information.",
-            whitelistedPackages, bzlPath));
+            "the C++ Skylark API is for the time being only allowed for rules in '%s'; "
+                + "but this is defined in '%s'. You can try it out by passing "
+                + "--experimental_cc_skylark_api_enabled_packages=<list of packages>. Beware that "
+                + "we will be making breaking changes to this API without prior warning.",
+            whitelistedPackages, callPath));
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationInfo.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationInfo.java
index d6806ad487..ca3a3d0733 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationInfo.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationInfo.java
@@ -78,7 +78,7 @@ public final class CcCompilationInfo extends NativeInfo implements CcCompilation
         @SuppressWarnings("unchecked")
         protected CcCompilationInfo createInstanceFromSkylark(
             Object[] args, Environment env, Location loc) throws EvalException {
-          CcCommon.checkLocationWhitelisted(loc);
+          CcCommon.checkLocationWhitelisted(env.getSemantics(), loc, loc.getPath().toString());
           CcCompilationInfo.Builder ccCompilationInfoBuilder = CcCompilationInfo.Builder.create();
           CcCompilationContext.Builder ccCompilationContext =
               new CcCompilationContext.Builder(/* ruleContext= */ null);
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLinkingInfo.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLinkingInfo.java
index a8a27515af..4157930c5c 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLinkingInfo.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLinkingInfo.java
@@ -78,7 +78,7 @@ public final class CcLinkingInfo extends NativeInfo implements CcLinkingInfoApi
         @SuppressWarnings("unchecked")
         protected CcLinkingInfo createInstanceFromSkylark(
             Object[] args, Environment env, Location loc) throws EvalException {
-          CcCommon.checkLocationWhitelisted(loc);
+          CcCommon.checkLocationWhitelisted(env.getSemantics(), loc, loc.getPath().toString());
           int i = 0;
           CcLinkParams staticModeParamsForDynamicLibrary = (CcLinkParams) nullIfNone(args[i++]);
           CcLinkParams staticModeParamsForExecutable = (CcLinkParams) nullIfNone(args[i++]);
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
index 300a4c9886..df698edc8f 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppConfiguration.java
@@ -982,10 +982,6 @@ public final class CppConfiguration extends BuildConfiguration.Fragment
     return cppOptions.useInterfaceSharedObjects;
   }
 
-  public boolean getEnableCcSkylarkApi() {
-    return cppOptions.enableCcSkylarkApi;
-  }
-
   /**
    * Returns the path to the GNU binutils 'objcopy' binary to use for this build. (Corresponds to
    * $(OBJCOPY) in make-dbg.) Relative paths are relative to the execution root.
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 4e4e863b29..e403f3320d 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
@@ -784,17 +784,6 @@ public class CppOptions extends FragmentOptions {
   public boolean enableLegacyToolchainSkylarkApi;
 
   @Option(
-      name = "experimental_enable_cc_skylark_api",
-      defaultValue = "false",
-      documentationCategory = OptionDocumentationCategory.UNDOCUMENTED,
-      effectTags = {OptionEffectTag.LOADING_AND_ANALYSIS},
-      metadataTags = {OptionMetadataTag.EXPERIMENTAL},
-      help =
-          "If true, the C++ Skylark API can be used. Don't enable this flag yet, we will be making "
-              + "breaking changes.")
-  public boolean enableCcSkylarkApi;
-
-  @Option(
       name = "experimental_disable_legacy_cc_linking_api",
       defaultValue = "false",
       documentationCategory = OptionDocumentationCategory.TOOLCHAIN,
@@ -875,8 +864,6 @@ public class CppOptions extends FragmentOptions {
   public FragmentOptions getHost() {
     CppOptions host = (CppOptions) getDefault();
 
-    host.enableCcSkylarkApi = enableCcSkylarkApi;
-
     // The crosstool options are partially copied from the target configuration.
     if (hostCrosstoolTop == null) {
       host.cppCompiler = cppCompiler;
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java
index 814a847081..5893ac49ab 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemantics.java
@@ -15,6 +15,8 @@
 package com.google.devtools.build.lib.syntax;
 
 import com.google.auto.value.AutoValue;
+import com.google.common.collect.ImmutableList;
+import java.util.List;
 
 /**
  * Options that affect Skylark semantics.
@@ -39,6 +41,8 @@ public abstract class SkylarkSemantics {
       AutoValue_SkylarkSemantics.class;
 
   // <== Add new options here in alphabetic order ==>
+  public abstract List<String> experimentalCcSkylarkApiEnabledPackages();
+
   public abstract boolean experimentalEnableRepoMapping();
 
   public abstract boolean incompatibleBzlDisallowLoadAfterStatement();
@@ -96,6 +100,7 @@ public abstract class SkylarkSemantics {
   public static final SkylarkSemantics DEFAULT_SEMANTICS =
       builder()
           // <== Add new options here in alphabetic order ==>
+          .experimentalCcSkylarkApiEnabledPackages(ImmutableList.of())
           .experimentalEnableRepoMapping(false)
           .incompatibleBzlDisallowLoadAfterStatement(false)
           .incompatibleDepsetIsNotIterable(false)
@@ -124,6 +129,8 @@ public abstract class SkylarkSemantics {
   public abstract static class Builder {
 
     // <== Add new options here in alphabetic order ==>
+    public abstract Builder experimentalCcSkylarkApiEnabledPackages(List<String> value);
+
     public abstract Builder experimentalEnableRepoMapping(boolean value);
 
     public abstract Builder incompatibleBzlDisallowLoadAfterStatement(boolean value);
diff --git a/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java b/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java
index ed22d1e380..21328c8ff1 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java
@@ -16,6 +16,7 @@ package com.google.devtools.build.lib.packages;
 
 import static com.google.common.truth.Truth.assertThat;
 
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.skyframe.serialization.DeserializationContext;
 import com.google.devtools.build.lib.skyframe.serialization.DynamicCodec;
@@ -36,26 +37,22 @@ import org.junit.runners.JUnit4;
  *
  * <p>When adding a new option, it is trivial to make a transposition error or a copy/paste error.
  * These tests guard against such errors. The following possible bugs are considered:
+ *
  * <ul>
  *   <li>If a new option is added to {@code SkylarkSemantics} but not to {@code
  *       SkylarkSemanticsOptions}, or vice versa, then the programmer will either be unable to
  *       implement its behavior, or unable to test it from the command line and add user
  *       documentation. We hope that the programmer notices this on their own.
- *
- *   <li>If {@link SkylarkSemanticsOptions#toSkylarkSemantics} or {@link
- *       SkylarkSemanticsCodec#deserialize} is not updated to set all fields of {@code
- *       SkylarkSemantics}, then it will fail immediately because all fields of {@link
+ *   <li>If {@link SkylarkSemanticsOptions#toSkylarkSemantics} is not updated to set all fields of
+ *       {@code SkylarkSemantics}, then it will fail immediately because all fields of {@link
  *       SkylarkSemantics.Builder} are mandatory.
- *
  *   <li>To catch a copy/paste error where the wrong field's data is threaded through {@code
  *       toSkylarkSemantics()} or {@code deserialize(...)}, we repeatedly generate matching random
  *       instances of the input and expected output objects.
- *
  *   <li>The {@link #checkDefaultsMatch} test ensures that there is no divergence between the
  *       default values of the two classes.
- *
- *   <li>There is no test coverage for failing to update the non-generated webpage documentation.
- *       So don't forget that!
+ *   <li>There is no test coverage for failing to update the non-generated webpage documentation. So
+ *       don't forget that!
  * </ul>
  */
 @RunWith(JUnit4.class)
@@ -121,6 +118,10 @@ public class SkylarkSemanticsConsistencyTest {
   private static SkylarkSemanticsOptions buildRandomOptions(Random rand) throws Exception {
     return parseOptions(
         // <== Add new options here in alphabetic order ==>
+        "--experimental_cc_skylark_api_enabled_packages="
+            + rand.nextDouble()
+            + ","
+            + rand.nextDouble(),
         "--experimental_enable_repo_mapping=" + rand.nextBoolean(),
         "--incompatible_bzl_disallow_load_after_statement=" + rand.nextBoolean(),
         "--incompatible_depset_is_not_iterable=" + rand.nextBoolean(),
@@ -151,6 +152,8 @@ public class SkylarkSemanticsConsistencyTest {
   private static SkylarkSemantics buildRandomSemantics(Random rand) {
     return SkylarkSemantics.builder()
         // <== Add new options here in alphabetic order ==>
+        .experimentalCcSkylarkApiEnabledPackages(
+            ImmutableList.of(String.valueOf(rand.nextDouble()), String.valueOf(rand.nextDouble())))
         .experimentalEnableRepoMapping(rand.nextBoolean())
         .incompatibleBzlDisallowLoadAfterStatement(rand.nextBoolean())
         .incompatibleDepsetIsNotIterable(rand.nextBoolean())
diff --git a/src/test/java/com/google/devtools/build/lib/rules/cpp/BUILD b/src/test/java/com/google/devtools/build/lib/rules/cpp/BUILD
index e15d4584cd..71cfffb053 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/cpp/BUILD
+++ b/src/test/java/com/google/devtools/build/lib/rules/cpp/BUILD
@@ -96,6 +96,7 @@ java_library(
     name = "CcImportBaseConfiguredTargetTest",
     srcs = ["CcImportBaseConfiguredTargetTest.java"],
     deps = [
+        ":SkylarkCcCommonTestHelper",
         "//src/main/java/com/google/devtools/build/lib:build-base",
         "//src/main/java/com/google/devtools/build/lib/actions",
         "//src/main/java/com/google/devtools/build/lib/rules/cpp",
diff --git a/src/test/java/com/google/devtools/build/lib/rules/cpp/CcImportBaseConfiguredTargetTest.java b/src/test/java/com/google/devtools/build/lib/rules/cpp/CcImportBaseConfiguredTargetTest.java
index 548bf8e09f..41bdb5679d 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/cpp/CcImportBaseConfiguredTargetTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/cpp/CcImportBaseConfiguredTargetTest.java
@@ -34,7 +34,9 @@ public abstract class CcImportBaseConfiguredTargetTest extends BuildViewTestCase
   protected String skylarkImplementationLoadStatement = "";
 
   @Before
-  public void setSkylarkImplementationLoadStatement() {
+  public void setSkylarkImplementationLoadStatement() throws Exception {
+    setSkylarkSemanticsOptions(SkylarkCcCommonTestHelper.CC_SKYLARK_WHITELIST_FLAG);
+    invalidatePackages();
     setIsSkylarkImplementation();
   }
 
diff --git a/src/test/java/com/google/devtools/build/lib/rules/cpp/SkylarkCcCommonTest.java b/src/test/java/com/google/devtools/build/lib/rules/cpp/SkylarkCcCommonTest.java
index 61f2058fdb..6bd4f038b3 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/cpp/SkylarkCcCommonTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/cpp/SkylarkCcCommonTest.java
@@ -45,8 +45,9 @@ import org.junit.runners.JUnit4;
 public class SkylarkCcCommonTest extends BuildViewTestCase {
 
   @Before
-  public void setConfiguration() throws Exception {
-    useConfiguration("--experimental_enable_cc_skylark_api");
+  public void setSkylarkSemanticsOptions() throws Exception {
+    setSkylarkSemanticsOptions(SkylarkCcCommonTestHelper.CC_SKYLARK_WHITELIST_FLAG);
+    invalidatePackages();
   }
 
   @Test
@@ -134,7 +135,7 @@ public class SkylarkCcCommonTest extends BuildViewTestCase {
     AnalysisMock.get()
         .ccSupport()
         .setupCrosstool(mockToolsConfig, "feature { name: 'foo_feature' }");
-    useConfiguration("--features=foo_feature", "--experimental_enable_cc_skylark_api");
+    useConfiguration("--features=foo_feature");
     scratch.file(
         "a/BUILD",
         "load(':rule.bzl', 'crule')",
@@ -733,7 +734,7 @@ public class SkylarkCcCommonTest extends BuildViewTestCase {
 
   @Test
   public void testIsLinkingDynamicLibraryLinkVariables() throws Exception {
-    useConfiguration("--linkopt=-pie", "--experimental_enable_cc_skylark_api");
+    useConfiguration("--linkopt=-pie");
     assertThat(
             commandLineForVariables(
                 CppActionNames.CPP_LINK_EXECUTABLE,
@@ -758,9 +759,7 @@ public class SkylarkCcCommonTest extends BuildViewTestCase {
 
   @Test
   public void testIsUsingLinkerLinkVariables() throws Exception {
-    useConfiguration(
-        "--linkopt=-i_dont_want_to_see_this_on_archiver_command_line",
-        "--experimental_enable_cc_skylark_api");
+    useConfiguration("--linkopt=-i_dont_want_to_see_this_on_archiver_command_line");
     assertThat(
             commandLineForVariables(
                 CppActionNames.CPP_LINK_EXECUTABLE,
@@ -1064,15 +1063,15 @@ public class SkylarkCcCommonTest extends BuildViewTestCase {
   }
 
   @Test
-  public void testCcLinkingProviderParamsWithoutFlag() throws Exception {
-    useConfiguration("--noexperimental_enable_cc_skylark_api");
-    setUpCcLinkingProviderParamsTest();
+  public void testFlagWhitelist() throws Exception {
+    setSkylarkSemanticsOptions("--experimental_cc_skylark_api_enabled_packages=\"\"");
+    SkylarkCcCommonTestHelper.createFiles(scratch, "foo/bar");
     reporter.removeHandler(failFastHandler);
-    getConfiguredTarget("//a:r");
+    getConfiguredTarget("//foo:bin");
     assertContainsEvent(
-        "Pass --experimental_enable_cc_skylark_api in order to "
-            + "use the C++ API. Beware that we will be making breaking changes to this API "
-            + "without prior warning.");
+        "You can try it out by passing "
+            + "--experimental_cc_skylark_api_enabled_packages=<list of packages>. Beware that we "
+            + "will be making breaking changes to this API without prior warning.");
   }
 
   @Test
@@ -1082,7 +1081,7 @@ public class SkylarkCcCommonTest extends BuildViewTestCase {
         .setupCrosstool(
             mockToolsConfig,
             "supports_interface_shared_objects: false");
-    useConfiguration("--experimental_enable_cc_skylark_api");
+    useConfiguration();
     setUpCcLinkingProviderParamsTest();
     ConfiguredTarget r = getConfiguredTarget("//a:r");
 
@@ -1251,14 +1250,6 @@ public class SkylarkCcCommonTest extends BuildViewTestCase {
   }
 
   @Test
-  public void testWhitelist() throws Exception {
-    SkylarkCcCommonTestHelper.createFiles(scratch, "foo/bar");
-    reporter.removeHandler(failFastHandler);
-    getConfiguredTarget("//foo:bin");
-    assertContainsEvent("C++ Skylark API is for the time being");
-  }
-
-  @Test
   public void testCopts() throws Exception {
     SkylarkCcCommonTestHelper.createFilesForTestingCompilation(
         scratch, "tools/build_defs/foo", "copts=depset(['-COMPILATION_OPTION'])");
diff --git a/src/test/java/com/google/devtools/build/lib/rules/cpp/SkylarkCcCommonTestHelper.java b/src/test/java/com/google/devtools/build/lib/rules/cpp/SkylarkCcCommonTestHelper.java
index 1aafab17b2..0a4dc6b95e 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/cpp/SkylarkCcCommonTestHelper.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/cpp/SkylarkCcCommonTestHelper.java
@@ -19,6 +19,9 @@ import com.google.devtools.build.lib.testutil.Scratch;
 /** Methods useful for tests testing the C++ Skylark API. */
 public final class SkylarkCcCommonTestHelper {
 
+  public static final String CC_SKYLARK_WHITELIST_FLAG =
+      "--experimental_cc_skylark_api_enabled_packages=tools/build_defs,experimental";
+
   public static void createFilesForTestingCompilation(
       Scratch scratch, String bzlFilePath, String compileProviderLines) throws Exception {
     createFiles(scratch, bzlFilePath, compileProviderLines, "");