Clean up the confusing distinction between "BaseRule" and "RuleBase".

Summary:
 - RootRule -> <removed>. The most basic rule definition, just adds the
     "name" attribute. Moved directly to RuleClass.Builder.
 - BaseRule -> NativeBuildRule = all non-Starlark BUILD rules. Includes rules
     that create actions (like compilation) and all other purposes (like aliases,
     filegroups, toolchain definitions that only provide metadata to other rules)
 - RuleBase -> NativeActionCreatingRule = all non-Starlark BUILD rules that
     create actions

Starlark rule classes are defined in StarlarkRuleClassFunctions. These remain unchanged.

This is a best-effort attempt. There seem to be some exceptions to every case,
but this covers the overarching themes as clearly as I can see them (code search
for "RuleBase.class)" and "BaseRule.class)").

Even if not 100% accurate, this communicates a standard to aspire to and make
adjustments around. This alone is a good step up from the current wording.

** See BaseRuleClasses.java for the main change. **

PiperOrigin-RevId: 353944214

src/main/java/com/google/devtools/build/lib/analysis/BaseRuleClasses.java

@@ -29,7 +29,6 @@
 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.analysis.config.BuildConfiguration;
 import com.google.devtools.build.lib.analysis.config.HostTransition;
 import com.google.devtools.build.lib.analysis.config.RunUnder;
@@ -248,7 +247,7 @@ public Metadata getMetadata() {
       return RuleDefinition.Metadata.builder()
           .name("$test_base_rule")
           .type(RuleClassType.ABSTRACT)
-          .ancestors(RootRule.class, MakeVariableExpandingRule.class)
+          .ancestors(MakeVariableExpandingRule.class)
           .build();
     }
   }
@@ -275,6 +274,9 @@ public static synchronized ImmutableList<Label> getTestRuntimeLabelList(
   public static final String TAGGED_TRIMMING_ATTR = "transitive_configs";
 
   /** Share common attributes across both base and Starlark base rules. */
+  // TODO(bazel-team): replace this with a common RuleDefinition ancestor of NativeBuildRule
+  // and StarlarkRuleClassFunctions.baseRule. This requires refactoring StarlarkRuleClassFunctions
+  // to instantiate its RuleClasses through RuleDefinition.
   public static RuleClass.Builder commonCoreAndStarlarkAttributes(RuleClass.Builder builder) {
     return builder
         // The visibility attribute is special: it is a nodep label, and loading the
@@ -349,41 +351,24 @@ public static RuleClass.Builder commonCoreAndStarlarkAttributes(RuleClass.Builde
                 .nonconfigurable("applicable_licenses is not configurable"));
   }
 
-  public static RuleClass.Builder nameAttribute(RuleClass.Builder builder) {
-    return builder.add(attr("name", STRING).nonconfigurable("Rule name"));
-  }
-
   public static RuleClass.Builder execPropertiesAttribute(RuleClass.Builder builder)
       throws ConversionException {
     return builder.add(
         attr(RuleClass.EXEC_PROPERTIES, STRING_DICT).defaultValue(ImmutableMap.of()));
   }
 
   /**
-   * Ancestor of every rule.
+   * Ancestor of every native rule in BUILD files (not WORKSPACE files).
    *
-   * <p>Adds the name attribute to every rule.
-   */
-  public static final class RootRule implements RuleDefinition {
-
-    @Override
-    public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment environment) {
-        return nameAttribute(builder).build();
-    }
-
-    @Override
-    public Metadata getMetadata() {
-      return RuleDefinition.Metadata.builder()
-          .name("$root_rule")
-          .type(RuleClassType.ABSTRACT)
-          .build();
-    }
-  }
-
-  /**
-   * Common parts of some rules.
+   * <p>This includes:
+   *
+   * <ul>
+   *   <li>rules that create actions ({@link NativeActionCreatingRule})
+   *   <li>rules that encapsulate toolchain and build environment context
+   *   <li>rules that aggregate other rules (like file groups, test suites, or aliases)
+   * </ul>
    */
-  public static final class BaseRule implements RuleDefinition {
+  public static final class NativeBuildRule implements RuleDefinition {
     @Override
     public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env) {
       return commonCoreAndStarlarkAttributes(builder)
@@ -399,9 +384,8 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env)
     @Override
     public Metadata getMetadata() {
       return RuleDefinition.Metadata.builder()
-          .name("$base_rule")
+          .name("$native_build_rule")
           .type(RuleClassType.ABSTRACT)
-          .ancestors(RootRule.class)
           .build();
     }
   }
@@ -433,9 +417,13 @@ public Metadata getMetadata() {
   }
 
   /**
-   * Common ancestor class for some rules.
+   * Ancestor of every native BUILD rule that creates actions.
+   *
+   * <p>This is a subset of all BUILD rules. Filegroups and aliases, for example, simply encapsulate
+   * other rules. Toolchain rules provide metadata for actions of other rules. See {@link
+   * NativeBuildRule} for these.
    */
-  public static final class RuleBase implements RuleDefinition {
+  public static final class NativeActionCreatingRule implements RuleDefinition {
     @Override
     public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env) {
       return builder
@@ -461,16 +449,13 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env)
     @Override
     public Metadata getMetadata() {
       return RuleDefinition.Metadata.builder()
-          .name("$rule")
+          .name("$native_buildable_rule")
           .type(RuleClassType.ABSTRACT)
-          .ancestors(BaseRule.class)
+          .ancestors(BaseRuleClasses.NativeBuildRule.class)
           .build();
     }
   }
 
-  public static final ImmutableSet<String> ALLOWED_RULE_CLASSES =
-      ImmutableSet.of("filegroup", "genrule", "Fileset");
-
   /** A base rule for all binary rules. */
   public static final class BinaryBaseRule implements RuleDefinition {
     @Override
@@ -491,7 +476,7 @@ public Metadata getMetadata() {
       return RuleDefinition.Metadata.builder()
           .name("$binary_base_rule")
           .type(RuleClassType.ABSTRACT)
-          .ancestors(RootRule.class, MakeVariableExpandingRule.class)
+          .ancestors(MakeVariableExpandingRule.class)
           .build();
     }
   }

src/main/java/com/google/devtools/build/lib/analysis/constraints/EnvironmentRule.java

@@ -70,7 +70,7 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env)
   public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name(ConstraintConstants.ENVIRONMENT_RULE)
-        .ancestors(BaseRuleClasses.BaseRule.class)
+        .ancestors(BaseRuleClasses.NativeBuildRule.class)
         .factoryClass(Environment.class)
         .build();
   }

src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkRuleClassFunctions.java

@@ -135,8 +135,7 @@ public Label load(String from) throws Exception {
   /** Parent rule class for non-executable non-test Starlark rules. */
   public static final RuleClass baseRule =
       BaseRuleClasses.commonCoreAndStarlarkAttributes(
-              BaseRuleClasses.nameAttribute(
-                      new RuleClass.Builder("$base_rule", RuleClassType.ABSTRACT, true))
+              new RuleClass.Builder("$base_rule", RuleClassType.ABSTRACT, true)
                   .add(attr("expect_failure", STRING)))
           // TODO(skylark-team): Allow Starlark rules to extend native rules and remove duplication.
           .add(

src/main/java/com/google/devtools/build/lib/bazel/repository/starlark/StarlarkRepositoryModule.java

@@ -86,7 +86,6 @@ public StarlarkCallable repositoryRule(
       BaseRuleClasses.execPropertiesAttribute(builder);
     }
     builder.addAttribute(attr("$environ", STRING_LIST).defaultValue(environ).build());
-    BaseRuleClasses.nameAttribute(builder);
     BaseRuleClasses.commonCoreAndStarlarkAttributes(builder);
     builder.add(attr("expect_failure", STRING));
     if (attrs != Starlark.NONE) {

src/main/java/com/google/devtools/build/lib/bazel/rules/android/BazelAndroidSdkRule.java

@@ -31,7 +31,7 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment envi
   public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("android_sdk")
-        .ancestors(AndroidSdkBaseRule.class, BaseRuleClasses.BaseRule.class)
+        .ancestors(AndroidSdkBaseRule.class, BaseRuleClasses.NativeBuildRule.class)
         .factoryClass(BazelAndroidSdk.class)
         .build();
   }

src/main/java/com/google/devtools/build/lib/bazel/rules/common/BazelFilegroupRule.java

@@ -83,7 +83,7 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env)
   public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("filegroup")
-        .ancestors(BaseRuleClasses.BaseRule.class)
+        .ancestors(BaseRuleClasses.NativeBuildRule.class)
         .factoryClass(Filegroup.class)
         .build();
   }

src/main/java/com/google/devtools/build/lib/bazel/rules/cpp/BazelCcImportRule.java

@@ -48,7 +48,7 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env)
   public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("cc_import")
-        .ancestors(BaseRuleClasses.BaseRule.class, CcImportRule.class)
+        .ancestors(BaseRuleClasses.NativeBuildRule.class, CcImportRule.class)
         .factoryClass(BazelCcImport.class)
         .build();
   }

src/main/java/com/google/devtools/build/lib/bazel/rules/cpp/BazelCppRuleClasses.java

@@ -210,7 +210,7 @@ public Metadata getMetadata() {
       return RuleDefinition.Metadata.builder()
           .name("$cc_decl_rule")
           .type(RuleClassType.ABSTRACT)
-          .ancestors(BaseRuleClasses.RuleBase.class)
+          .ancestors(BaseRuleClasses.NativeActionCreatingRule.class)
           .build();
     }
   }

src/main/java/com/google/devtools/build/lib/bazel/rules/java/BazelJavaRuleClasses.java

@@ -262,7 +262,7 @@ public Metadata getMetadata() {
       return RuleDefinition.Metadata.builder()
           .name("$java_rule")
           .type(RuleClassType.ABSTRACT)
-          .ancestors(BaseRuleClasses.RuleBase.class, JavaBaseRule.class)
+          .ancestors(BaseRuleClasses.NativeActionCreatingRule.class, JavaBaseRule.class)
           .build();
     }
   }

src/main/java/com/google/devtools/build/lib/bazel/rules/java/proto/BazelJavaLiteProtoLibraryRule.java

@@ -73,7 +73,7 @@ public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("java_lite_proto_library")
         .factoryClass(JavaLiteProtoLibrary.class)
-        .ancestors(BaseRuleClasses.RuleBase.class, JavaToolchainBaseRule.class)
+        .ancestors(BaseRuleClasses.NativeActionCreatingRule.class, JavaToolchainBaseRule.class)
         .build();
   }
 }

src/main/java/com/google/devtools/build/lib/bazel/rules/java/proto/BazelJavaProtoLibraryRule.java

@@ -60,7 +60,7 @@ public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("java_proto_library")
         .factoryClass(JavaProtoLibrary.class)
-        .ancestors(BaseRuleClasses.RuleBase.class)
+        .ancestors(BaseRuleClasses.NativeActionCreatingRule.class)
         .build();
   }
 }

src/main/java/com/google/devtools/build/lib/bazel/rules/ninja/actions/NinjaBuildRule.java

@@ -75,7 +75,7 @@ public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("ninja_build")
         .type(RuleClassType.NORMAL)
-        .ancestors(BaseRuleClasses.BaseRule.class)
+        .ancestors(BaseRuleClasses.NativeBuildRule.class)
         .factoryClass(NinjaBuild.class)
         .build();
   }

src/main/java/com/google/devtools/build/lib/bazel/rules/ninja/actions/NinjaGraphRule.java

@@ -101,7 +101,7 @@ public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("ninja_graph")
         .type(RuleClassType.NORMAL)
-        .ancestors(BaseRuleClasses.BaseRule.class)
+        .ancestors(BaseRuleClasses.NativeBuildRule.class)
         .factoryClass(NinjaGraph.class)
         .build();
   }

src/main/java/com/google/devtools/build/lib/bazel/rules/python/BazelPyRuleClasses.java

@@ -144,7 +144,7 @@ public Metadata getMetadata() {
       return RuleDefinition.Metadata.builder()
           .name("$base_py")
           .type(RuleClassType.ABSTRACT)
-          .ancestors(BaseRuleClasses.RuleBase.class)
+          .ancestors(BaseRuleClasses.NativeActionCreatingRule.class)
           .build();
     }
   }

src/main/java/com/google/devtools/build/lib/bazel/rules/sh/BazelShRuleClasses.java

@@ -79,7 +79,7 @@ public Metadata getMetadata() {
       return RuleDefinition.Metadata.builder()
           .name("$sh_target")
           .type(RuleClassType.ABSTRACT)
-          .ancestors(BaseRuleClasses.RuleBase.class)
+          .ancestors(BaseRuleClasses.NativeActionCreatingRule.class)
           .build();
     }
   }

src/main/java/com/google/devtools/build/lib/packages/RuleClass.java

@@ -19,6 +19,7 @@
 import static com.google.devtools.build.lib.packages.BuildType.LABEL_LIST;
 import static com.google.devtools.build.lib.packages.ExecGroup.COPY_FROM_RULE_EXEC_GROUP;
 import static com.google.devtools.build.lib.packages.Type.BOOLEAN;
+import static com.google.devtools.build.lib.packages.Type.STRING;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Function;
@@ -749,6 +750,9 @@ public Builder(String name, RuleClassType type, boolean starlark, RuleClass... p
       this.type = type;
       Preconditions.checkState(starlark || type != RuleClassType.PLACEHOLDER, name);
       this.documented = type != RuleClassType.ABSTRACT;
+      add(
+          attr("name", STRING)
+              .nonconfigurable("All rules have a non-customizable \"name\" attribute"));
       for (RuleClass parent : parents) {
         if (parent.getValidityPredicate() != PredicatesWithMessage.<Rule>alwaysTrue()) {
           setValidityPredicate(parent.getValidityPredicate());

src/main/java/com/google/devtools/build/lib/rules/Alias.java

@@ -101,7 +101,7 @@ public Metadata getMetadata() {
       return Metadata.builder()
           .name(RULE_NAME)
           .factoryClass(Alias.class)
-          .ancestors(BaseRuleClasses.BaseRule.class)
+          .ancestors(BaseRuleClasses.NativeBuildRule.class)
           .build();
     }
   }

src/main/java/com/google/devtools/build/lib/rules/LateBoundAlias.java

@@ -123,7 +123,7 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment envi
     public Metadata getMetadata() {
       return Metadata.builder()
           .name(ruleName)
-          .ancestors(BaseRuleClasses.BaseRule.class)
+          .ancestors(BaseRuleClasses.NativeBuildRule.class)
           .factoryClass(LateBoundAlias.class)
           .build();
     }

src/main/java/com/google/devtools/build/lib/rules/ToolchainType.java

@@ -61,7 +61,7 @@ public Metadata getMetadata() {
       return Metadata.builder()
           .name("toolchain_type")
           .factoryClass(ToolchainType.class)
-          .ancestors(BaseRuleClasses.BaseRule.class)
+          .ancestors(BaseRuleClasses.NativeBuildRule.class)
           .build();
     }
   }

src/main/java/com/google/devtools/build/lib/rules/android/AndroidDeviceRule.java

@@ -181,7 +181,7 @@ a real device (In particular controlling its UserAgent strings and other
   public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("android_device")
-        .ancestors(BaseRuleClasses.RuleBase.class)
+        .ancestors(BaseRuleClasses.NativeActionCreatingRule.class)
         .factoryClass(factoryClass)
         .build();
   }

src/main/java/com/google/devtools/build/lib/rules/android/AndroidDeviceScriptFixtureRule.java

@@ -59,7 +59,7 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment envi
   public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("android_device_script_fixture")
-        .ancestors(BaseRuleClasses.RuleBase.class)
+        .ancestors(BaseRuleClasses.NativeActionCreatingRule.class)
         .factoryClass(factoryClass)
         .build();
   }

src/main/java/com/google/devtools/build/lib/rules/android/AndroidHostServiceFixtureRule.java

@@ -58,7 +58,7 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env)
   public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("android_host_service_fixture")
-        .ancestors(BaseRuleClasses.RuleBase.class)
+        .ancestors(BaseRuleClasses.NativeActionCreatingRule.class)
         .factoryClass(factoryClass)
         .build();
   }

src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java

@@ -453,7 +453,7 @@ public Metadata getMetadata() {
       return RuleDefinition.Metadata.builder()
           .name("$android_base")
           .type(RuleClassType.ABSTRACT)
-          .ancestors(BaseRuleClasses.RuleBase.class)
+          .ancestors(BaseRuleClasses.NativeActionCreatingRule.class)
           .build();
     }
   }
@@ -949,7 +949,7 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment envi
     public Metadata getMetadata() {
       return Metadata.builder()
           .name("android_tools_defaults_jar")
-          .ancestors(BaseRuleClasses.BaseRule.class)
+          .ancestors(BaseRuleClasses.NativeBuildRule.class)
           .factoryClass(factoryClass)
           .build();
     }

src/main/java/com/google/devtools/build/lib/rules/apple/AvailableXcodesRule.java

@@ -59,7 +59,7 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env)
   public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("available_xcodes")
-        .ancestors(BaseRuleClasses.BaseRule.class)
+        .ancestors(BaseRuleClasses.NativeBuildRule.class)
         .factoryClass(AvailableXcodes.class)
         .build();
   }

src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfigAlias.java

@@ -77,7 +77,8 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment envi
     public Metadata getMetadata() {
       return Metadata.builder()
           .name("xcode_config_alias")
-          .ancestors(BaseRuleClasses.BaseRule.class, AppleToolchain.RequiresXcodeConfigRule.class)
+          .ancestors(
+              BaseRuleClasses.NativeBuildRule.class, AppleToolchain.RequiresXcodeConfigRule.class)
           .factoryClass(XcodeConfigAlias.class)
           .build();
     }

src/main/java/com/google/devtools/build/lib/rules/apple/XcodeConfigRule.java

@@ -91,7 +91,7 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env)
   public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("xcode_config")
-        .ancestors(BaseRuleClasses.BaseRule.class)
+        .ancestors(BaseRuleClasses.NativeBuildRule.class)
         .factoryClass(XcodeConfig.class)
         .build();
   }

src/main/java/com/google/devtools/build/lib/rules/apple/XcodeVersionRule.java

@@ -92,7 +92,7 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env)
   public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("xcode_version")
-        .ancestors(BaseRuleClasses.BaseRule.class)
+        .ancestors(BaseRuleClasses.NativeBuildRule.class)
         .factoryClass(XcodeVersion.class)
         .build();
   }

src/main/java/com/google/devtools/build/lib/rules/apple/cpp/AppleCcToolchainRule.java

@@ -35,7 +35,9 @@ public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment envi
   public Metadata getMetadata() {
     return RuleDefinition.Metadata.builder()
         .name("apple_cc_toolchain")
-        .ancestors(BaseRuleClasses.BaseRule.class, CcToolchainRule.class,
+        .ancestors(
+            BaseRuleClasses.NativeBuildRule.class,
+            CcToolchainRule.class,
             AppleToolchain.RequiresXcodeConfigRule.class)
         .factoryClass(AppleCcToolchain.class)
         .build();