Add the config_feature_flag rule.

This rule allows users to define flags as part of the Bazel configuration.
These flags will be select-able through a new attribute on config_setting,
and settable through transitions within certain special rules.

This rule is currently not supported by any other rules, not even
config_setting, and its values cannot be set; accordingly, it's not very
useful yet.

RELNOTES: None.

PiperOrigin-RevId: 151746523

7 files changed, 403 insertions, 5 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/BUILD b/src/test/java/com/google/devtools/build/lib/BUILD
index f43bd9d56d..a6ce260446 100644
--- a/src/test/java/com/google/devtools/build/lib/BUILD
+++ b/src/test/java/com/google/devtools/build/lib/BUILD
@@ -357,6 +357,7 @@ java_library(
         "//src/main/java/com/google/devtools/build/lib/query2:query-output",
         "//src/main/java/com/google/devtools/build/lib/rules/apple",
         "//src/main/java/com/google/devtools/build/lib/rules/apple/swift",
+        "//src/main/java/com/google/devtools/build/lib/rules/config",
         "//src/main/java/com/google/devtools/build/lib/rules/cpp",
         "//src/main/java/com/google/devtools/build/lib/rules/genquery",
         "//src/main/java/com/google/devtools/build/lib/rules/objc",
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/mock/BazelAnalysisMock.java b/src/test/java/com/google/devtools/build/lib/analysis/mock/BazelAnalysisMock.java
index c2c75afad9..f54d7d20b2 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/mock/BazelAnalysisMock.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/mock/BazelAnalysisMock.java
@@ -30,6 +30,7 @@ import com.google.devtools.build.lib.packages.util.MockToolsConfig;
 import com.google.devtools.build.lib.rules.android.AndroidConfiguration;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.swift.SwiftConfiguration;
+import com.google.devtools.build.lib.rules.config.ConfigFeatureFlagConfiguration;
 import com.google.devtools.build.lib.rules.cpp.CppConfigurationLoader;
 import com.google.devtools.build.lib.rules.cpp.FdoSupportFunction;
 import com.google.devtools.build.lib.rules.cpp.FdoSupportValue;
@@ -255,6 +256,7 @@ public final class BazelAnalysisMock extends AnalysisMock {
         new SwiftConfiguration.Loader(),
         new J2ObjcConfiguration.Loader(),
         new ProtoConfiguration.Loader(),
+        new ConfigFeatureFlagConfiguration.Loader(),
         new AndroidConfiguration.Loader());
   }
 
diff --git a/src/test/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProviderTest.java b/src/test/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProviderTest.java
index 2cdcd093c1..5766dd8d15 100644
--- a/src/test/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProviderTest.java
+++ b/src/test/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProviderTest.java
@@ -90,8 +90,13 @@ public class BazelRuleClassProviderTest {
   }
 
   @Test
-  public void basicConsistency() {
-    checkModule(BazelRuleClassProvider.BASIC_RULES);
+  public void genericConsistency() {
+    checkModule(BazelRuleClassProvider.GENERIC_RULES);
+  }
+
+  @Test
+  public void configConsistency() {
+    checkModule(BazelRuleClassProvider.CONFIG_RULES);
   }
 
   @Test
diff --git a/src/test/java/com/google/devtools/build/lib/rules/config/BUILD b/src/test/java/com/google/devtools/build/lib/rules/config/BUILD
index 0083a4d85b..34c5cadbd7 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/config/BUILD
+++ b/src/test/java/com/google/devtools/build/lib/rules/config/BUILD
@@ -11,3 +11,36 @@ filegroup(
     testonly = 0,  # All srcs should be not test only, overwrite package default.
     srcs = glob(["**"]),
 )
+
+java_library(
+    name = "ConfigRulesTests_lib",
+    srcs = glob(["*.java"]),
+    deps = [
+        "//src/main/java/com/google/devtools/build/lib:build-base",
+        "//src/main/java/com/google/devtools/build/lib:collect",
+        "//src/main/java/com/google/devtools/build/lib:packages-internal",
+        "//src/main/java/com/google/devtools/build/lib/actions",
+        "//src/main/java/com/google/devtools/build/lib/cmdline",
+        "//src/main/java/com/google/devtools/build/lib/rules/config",
+        "//src/main/java/com/google/devtools/common/options",
+        "//src/test/java/com/google/devtools/build/lib:actions_testutil",
+        "//src/test/java/com/google/devtools/build/lib:analysis_testutil",
+        "//src/test/java/com/google/devtools/build/lib:testutil",
+        "//src/test/java/com/google/devtools/build/lib/skylark:testutil",
+        "//third_party:guava",
+        "//third_party:guava-testlib",
+        "//third_party:jsr305",
+        "//third_party:junit4",
+        "//third_party:truth",
+    ],
+)
+
+java_test(
+    name = "ConfigRulesTests",
+    test_class = "com.google.devtools.build.lib.AllTests",
+    runtime_deps = [
+        ":ConfigRulesTests_lib",
+        "//src/test/java/com/google/devtools/build/lib:test_runner",
+        "//src/test/java/com/google/devtools/build/lib:testutil",
+    ],
+)
diff --git a/src/test/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagConfigurationTest.java b/src/test/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagConfigurationTest.java
index 610ce2d357..a0de77dfdf 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagConfigurationTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagConfigurationTest.java
@@ -93,7 +93,7 @@ public final class ConfigFeatureFlagConfigurationTest {
   public void options_equals_forEquivalentMaps() throws Exception {
     new EqualsTester()
         .addEqualityGroup(
-            getOptionsWith(ImmutableMap.of()),
+            getOptionsWith(ImmutableMap.<Label, String>of()),
             new ConfigFeatureFlagConfiguration.Options(),
             new ConfigFeatureFlagConfiguration.Options().getDefault(),
             new ConfigFeatureFlagConfiguration.Options().getHost(false),
@@ -161,7 +161,8 @@ public final class ConfigFeatureFlagConfigurationTest {
 
   @Test
   public void getOutputDirectoryName_returnsNullWhenFlagMapIsEmpty() throws Exception {
-    assertThat(getConfigurationWithFlags(ImmutableMap.of()).getOutputDirectoryName()).isNull();
+    assertThat(getConfigurationWithFlags(ImmutableMap.<Label, String>of()).getOutputDirectoryName())
+        .isNull();
   }
 
   @Test
diff --git a/src/test/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagTest.java b/src/test/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagTest.java
new file mode 100644
index 0000000000..9fe164bd65
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagTest.java
@@ -0,0 +1,356 @@
+// Copyright 2017 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License
+
+package com.google.devtools.build.lib.rules.config;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.devtools.build.lib.collect.nestedset.Order.STABLE_ORDER;
+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.packages.BuildType.LABEL_KEYED_STRING_DICT;
+import static com.google.devtools.build.lib.packages.BuildType.LABEL_LIST;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.Iterables;
+import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.analysis.BaseRuleClasses;
+import com.google.devtools.build.lib.analysis.ConfiguredRuleClassProvider;
+import com.google.devtools.build.lib.analysis.ConfiguredTarget;
+import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
+import com.google.devtools.build.lib.analysis.RuleConfiguredTargetBuilder;
+import com.google.devtools.build.lib.analysis.RuleContext;
+import com.google.devtools.build.lib.analysis.RuleDefinition;
+import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
+import com.google.devtools.build.lib.analysis.RunfilesProvider;
+import com.google.devtools.build.lib.analysis.TransitiveInfoCollection;
+import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
+import com.google.devtools.build.lib.packages.RuleClass;
+import com.google.devtools.build.lib.packages.RuleClass.Builder;
+import com.google.devtools.build.lib.rules.RuleConfiguredTargetFactory;
+import com.google.devtools.build.lib.rules.SkylarkRuleContext;
+import com.google.devtools.build.lib.skylark.util.SkylarkTestCase;
+import com.google.devtools.build.lib.testutil.TestRuleClassProvider;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Tests for the config_feature_flag rule. */
+@RunWith(JUnit4.class)
+public final class ConfigFeatureFlagTest extends SkylarkTestCase {
+
+  /** Rule introducing a transition to set feature flags for dependencies. */
+  public static final class FeatureFlagSetter
+      implements RuleDefinition, RuleConfiguredTargetFactory {
+
+    @Override
+    public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
+      return builder
+          .requiresConfigurationFragments(ConfigFeatureFlagConfiguration.class)
+          .cfg(new ConfigFeatureFlagTransitionFactory("flag_values"))
+          .add(attr("deps", LABEL_LIST).allowedFileTypes())
+          .add(
+              attr("exports_flag", LABEL)
+                  .allowedRuleClasses("config_feature_flag")
+                  .allowedFileTypes())
+          .add(
+              attr("flag_values", LABEL_KEYED_STRING_DICT)
+                  .allowedRuleClasses("config_feature_flag")
+                  .allowedFileTypes()
+                  .nonconfigurable("used in RuleTransitionFactory")
+                  .value(ImmutableMap.<Label, String>of()))
+          .build();
+    }
+
+    @Override
+    public Metadata getMetadata() {
+      return RuleDefinition.Metadata.builder()
+          .name("feature_flag_setter")
+          .ancestors(BaseRuleClasses.BaseRule.class)
+          .factoryClass(FeatureFlagSetter.class)
+          .build();
+    }
+
+    @Override
+    public ConfiguredTarget create(RuleContext ruleContext)
+        throws InterruptedException, RuleErrorException {
+      TransitiveInfoCollection dep = ruleContext.getPrerequisite("exports_flag", Mode.TARGET);
+      ConfigFeatureFlagProvider exportedProvider =
+          dep != null ? ConfigFeatureFlagProvider.fromTarget(dep) : null;
+      RuleConfiguredTargetBuilder builder =
+          new RuleConfiguredTargetBuilder(ruleContext)
+              .setFilesToBuild(NestedSetBuilder.<Artifact>emptySet(STABLE_ORDER))
+              .addProvider(RunfilesProvider.class, RunfilesProvider.EMPTY);
+      if (exportedProvider != null) {
+        builder.addNativeDeclaredProvider(exportedProvider);
+      }
+      return builder.build();
+    }
+  }
+
+  @Before
+  public void useDynamicConfigurations() throws Exception {
+    useConfiguration("--experimental_dynamic_configs=on");
+  }
+
+  @Override
+  protected ConfiguredRuleClassProvider getRuleClassProvider() {
+    ConfiguredRuleClassProvider.Builder builder =
+        new ConfiguredRuleClassProvider.Builder().addRuleDefinition(new FeatureFlagSetter());
+    TestRuleClassProvider.addStandardRules(builder);
+    return builder.build();
+  }
+
+  @Test
+  public void configFeatureFlagProvider_fromTargetReturnsNullIfTargetDoesNotExportProvider()
+      throws Exception {
+    scratch.file(
+        "test/BUILD",
+        "feature_flag_setter(",
+        "    name = 'top',",
+        "    flag_values = {",
+        "    },",
+        ")");
+    assertThat(ConfigFeatureFlagProvider.fromTarget(getConfiguredTarget("//test:top"))).isNull();
+  }
+
+  @Test
+  public void configFeatureFlagProvider_containsValueFromConfiguration() throws Exception {
+    scratch.file(
+        "test/BUILD",
+        "feature_flag_setter(",
+        "    name = 'top',",
+        "    exports_flag = ':flag',",
+        "    flag_values = {",
+        "        ':flag': 'configured',",
+        "    },",
+        ")",
+        "config_feature_flag(",
+        "    name = 'flag',",
+        "    allowed_values = ['default', 'configured', 'other'],",
+        "    default_value = 'default',",
+        ")");
+    assertThat(ConfigFeatureFlagProvider.fromTarget(getConfiguredTarget("//test:top")).getValue())
+        .isEqualTo("configured");
+  }
+
+  @Test
+  public void configFeatureFlagProvider_valueIsAccessibleFromSkylark() throws Exception {
+    scratch.file(
+        "test/wrapper.bzl",
+        "def _flag_reading_wrapper_impl(ctx):",
+        "  pass",
+        "flag_reading_wrapper = rule(",
+        "  implementation = _flag_reading_wrapper_impl,",
+        "  attrs = {'flag': attr.label()},",
+        ")");
+    scratch.file(
+        "test/BUILD",
+        "load(':wrapper.bzl', 'flag_reading_wrapper')",
+        "feature_flag_setter(",
+        "    name = 'top',",
+        "    deps = [':wrapper'],",
+        "    flag_values = {",
+        "        ':flag': 'configured',",
+        "    },",
+        ")",
+        "flag_reading_wrapper(",
+        "    name = 'wrapper',",
+        "    flag = ':flag',",
+        ")",
+        "config_feature_flag(",
+        "    name = 'flag',",
+        "    allowed_values = ['default', 'configured', 'other'],",
+        "    default_value = 'default',",
+        ")");
+    ConfiguredTarget top = getConfiguredTarget("//test:top");
+    ConfiguredTarget wrapper =
+        (ConfiguredTarget) Iterables.getOnlyElement(getPrerequisites(top, "deps"));
+    SkylarkRuleContext ctx = new SkylarkRuleContext(getRuleContextForSkylark(wrapper), null);
+    update("ruleContext", ctx);
+    update("config_common", new ConfigSkylarkCommon());
+    String value = (String) eval("ruleContext.attr.flag[config_common.FeatureFlagInfo].value");
+    assertThat(value).isEqualTo("configured");
+  }
+
+  @Test
+  public void configFeatureFlagProvider_validatesValuesUsingAllowedValuesAttribute()
+      throws Exception {
+    scratch.file(
+        "test/BUILD",
+        "config_feature_flag(",
+        "    name = 'flag',",
+        "    allowed_values = ['default', 'configured', 'other'],",
+        "    default_value = 'default',",
+        ")");
+    ConfigFeatureFlagProvider provider =
+        ConfigFeatureFlagProvider.fromTarget(getConfiguredTarget("//test:flag"));
+    assertThat(provider.isValidValue("default")).isTrue();
+    assertThat(provider.isValidValue("configured")).isTrue();
+    assertThat(provider.isValidValue("other")).isTrue();
+
+    assertThat(provider.isValidValue("absent")).isFalse();
+    assertThat(provider.isValidValue("conFigured")).isFalse();
+    assertThat(provider.isValidValue("  other")).isFalse();
+  }
+
+  @Test
+  public void configFeatureFlagProvider_valueValidationIsPossibleFromSkylark() throws Exception {
+    scratch.file(
+        "test/wrapper.bzl",
+        "def _flag_reading_wrapper_impl(ctx):",
+        "  pass",
+        "flag_reading_wrapper = rule(",
+        "  implementation = _flag_reading_wrapper_impl,",
+        "  attrs = {'flag': attr.label()},",
+        ")");
+    scratch.file(
+        "test/BUILD",
+        "load(':wrapper.bzl', 'flag_reading_wrapper')",
+        "flag_reading_wrapper(",
+        "    name = 'wrapper',",
+        "    flag = ':flag',",
+        ")",
+        "config_feature_flag(",
+        "    name = 'flag',",
+        "    allowed_values = ['default', 'configured', 'other'],",
+        "    default_value = 'default',",
+        ")");
+    SkylarkRuleContext ctx = createRuleContext("//test:wrapper");
+    update("ruleContext", ctx);
+    update("config_common", new ConfigSkylarkCommon());
+    String provider = "ruleContext.attr.flag[config_common.FeatureFlagInfo]";
+    Boolean isDefaultValid = (Boolean) eval(provider + ".is_valid_value('default')");
+    Boolean isConfiguredValid = (Boolean) eval(provider + ".is_valid_value('configured')");
+    Boolean isOtherValid = (Boolean) eval(provider + ".is_valid_value('other')");
+    Boolean isAbsentValid = (Boolean) eval(provider + ".is_valid_value('absent')");
+    Boolean isIncorrectCapitalizationValid =
+        (Boolean) eval(provider + ".is_valid_value('conFigured')");
+    Boolean isIncorrectSpacingValid = (Boolean) eval(provider + ".is_valid_value('  other')");
+
+    assertThat(isDefaultValid).isTrue();
+    assertThat(isConfiguredValid).isTrue();
+    assertThat(isOtherValid).isTrue();
+
+    assertThat(isAbsentValid).isFalse();
+    assertThat(isIncorrectCapitalizationValid).isFalse();
+    assertThat(isIncorrectSpacingValid).isFalse();
+  }
+
+  @Test
+  public void configFeatureFlagProvider_usesDefaultValueIfConfigurationDoesntSetValue()
+      throws Exception {
+    scratch.file(
+        "test/BUILD",
+        "feature_flag_setter(",
+        "    name = 'top',",
+        "    exports_flag = ':flag',",
+        "    flag_values = {",
+        "        ':other': 'configured',",
+        "    },",
+        ")",
+        "config_feature_flag(",
+        "    name = 'flag',",
+        "    allowed_values = ['other', 'default', 'configured'],",
+        "    default_value = 'default',",
+        ")",
+        "config_feature_flag(",
+        "    name = 'other',",
+        "    allowed_values = ['default', 'configured', 'other'],",
+        "    default_value = 'default',",
+        ")");
+    assertThat(ConfigFeatureFlagProvider.fromTarget(getConfiguredTarget("//test:top")).getValue())
+        .isEqualTo("default");
+  }
+
+  @Test
+  public void allowedValuesAttribute_cannotBeEmpty() throws Exception {
+    reporter.removeHandler(failFastHandler); // expecting an error
+    scratch.file(
+        "test/BUILD",
+        "config_feature_flag(",
+        "    name = 'flag',",
+        "    allowed_values = [],",
+        "    default_value = 'default',",
+        ")");
+    assertThat(getConfiguredTarget("//test:flag")).isNull();
+    assertContainsEvent(
+        "in allowed_values attribute of config_feature_flag rule //test:flag: "
+            + "attribute must be non empty");
+  }
+
+  @Test
+  public void allowedValuesAttribute_cannotContainDuplicates() throws Exception {
+    reporter.removeHandler(failFastHandler); // expecting an error
+    scratch.file(
+        "test/BUILD",
+        "config_feature_flag(",
+        "    name = 'flag',",
+        "    allowed_values = ['double', 'double', 'toil', 'trouble'],",
+        "    default_value = 'trouble',",
+        ")");
+    assertThat(getConfiguredTarget("//test:flag")).isNull();
+    assertContainsEvent(
+        "in allowed_values attribute of config_feature_flag rule //test:flag: "
+            + "cannot contain duplicates, but contained multiple of ['double']");
+  }
+
+  @Test
+  public void defaultValueAttribute_mustBeMemberOfAllowedValues() throws Exception {
+    reporter.removeHandler(failFastHandler); // expecting an error
+    scratch.file(
+        "test/BUILD",
+        "feature_flag_setter(",
+        "    name = 'top',",
+        "    exports_flag = ':flag',",
+        "    flag_values = {",
+        "        ':flag': 'legal',",
+        "    },",
+        ")",
+        "config_feature_flag(",
+        "    name = 'flag',",
+        "    allowed_values = ['legal', 'eagle'],",
+        "    default_value = 'beagle',",
+        ")");
+    assertThat(getConfiguredTarget("//test:top")).isNull();
+    assertContainsEvent(
+        "in default_value attribute of config_feature_flag rule //test:flag: "
+            + "must be one of ['eagle', 'legal'], but was 'beagle'");
+  }
+
+  @Test
+  public void configurationValue_mustBeMemberOfAllowedValues() throws Exception {
+    reporter.removeHandler(failFastHandler); // expecting an error
+    scratch.file(
+        "test/BUILD",
+        "feature_flag_setter(",
+        "    name = 'top',",
+        "    exports_flag = ':flag',",
+        "    flag_values = {",
+        "        ':flag': 'invalid',",
+        "    },",
+        ")",
+        "config_feature_flag(",
+        "    name = 'flag',",
+        "    allowed_values = ['default', 'configured', 'other'],",
+        "    default_value = 'default',",
+        ")");
+    assertThat(getConfiguredTarget("//test:top")).isNull();
+    // TODO(mstaib): when configurationError is implemented, switch to testing for that
+    assertContainsEvent(
+        "in config_feature_flag rule //test:flag: "
+            + "value must be one of ['configured', 'default', 'other'], but was 'invalid'");
+  }
+}
diff --git a/src/test/java/com/google/devtools/build/lib/rules/cpp/CcCommonTest.java b/src/test/java/com/google/devtools/build/lib/rules/cpp/CcCommonTest.java
index 75b91c3c54..e0fc844f63 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/cpp/CcCommonTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/cpp/CcCommonTest.java
@@ -964,7 +964,7 @@ public class CcCommonTest extends BuildViewTestCase {
           BazelRuleClassProvider.BAZEL_SETUP.init(builder);
           BazelRuleClassProvider.CORE_RULES.init(builder);
           BazelRuleClassProvider.CORE_WORKSPACE_RULES.init(builder);
-          BazelRuleClassProvider.BASIC_RULES.init(builder);
+          BazelRuleClassProvider.GENERIC_RULES.init(builder);
           BazelRuleClassProvider.CPP_RULES.init(builder);
           builder.addRuleDefinition(new OnlyCppToolchainTypeRule());
           return builder.build();