Delete native CcToolchainAlias rule since it is already Starlarkified.

PiperOrigin-RevId: 527571232
Change-Id: Ic6383beb645507c6c9efe89dcc81c5c0952ecdea

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

@@ -14,88 +14,29 @@
 
 package com.google.devtools.build.lib.rules.cpp;
 
-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.NODEP_LABEL;
 
-import com.google.common.collect.ImmutableMap;
-import com.google.devtools.build.lib.actions.MutableActionGraph.ActionConflictException;
 import com.google.devtools.build.lib.analysis.BaseRuleClasses;
-import com.google.devtools.build.lib.analysis.ConfiguredTarget;
-import com.google.devtools.build.lib.analysis.PlatformConfiguration;
-import com.google.devtools.build.lib.analysis.RuleConfiguredTargetBuilder;
-import com.google.devtools.build.lib.analysis.RuleConfiguredTargetFactory;
-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.Runfiles;
-import com.google.devtools.build.lib.analysis.RunfilesProvider;
-import com.google.devtools.build.lib.analysis.TemplateVariableInfo;
-import com.google.devtools.build.lib.analysis.platform.ToolchainInfo;
 import com.google.devtools.build.lib.packages.RuleClass;
-import com.google.devtools.build.lib.packages.Type;
-import javax.annotation.Nullable;
 
-/** Implementation of the {@code cc_toolchain_alias} rule. */
+/**
+ * Dummy rule definition for cc_toolchain_alias rule. To make sure that the rule can be overridden
+ * from Starlark builtins.
+ */
 public class CcToolchainAliasRule implements RuleDefinition {
   @Override
   public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env) {
     return builder
-        .requiresConfigurationFragments(CppConfiguration.class)
-        .removeAttribute("licenses")
-        .removeAttribute("distribs")
-        .add(
-            attr(CcToolchain.CC_TOOLCHAIN_DEFAULT_ATTRIBUTE_NAME, LABEL)
-                .mandatoryProviders(CcToolchainProvider.PROVIDER.id())
-                .value(CppRuleClasses.ccToolchainAttribute(env)))
-        .add(
-            attr(CcToolchain.CC_TOOLCHAIN_TYPE_ATTRIBUTE_NAME, NODEP_LABEL)
-                .value(CppRuleClasses.ccToolchainTypeAttribute(env)))
-        .add(attr("mandatory", Type.BOOLEAN).value(true))
-        .requiresConfigurationFragments(PlatformConfiguration.class)
-        .addToolchainTypes(CppRuleClasses.ccToolchainTypeRequirement(env))
         .build();
   }
 
   @Override
   public Metadata getMetadata() {
     return Metadata.builder()
         .name("cc_toolchain_alias")
+        .factoryClass(BaseRuleClasses.EmptyRuleConfiguredTargetFactory.class)
         .ancestors(BaseRuleClasses.NativeBuildRule.class)
-        .factoryClass(CcToolchainAlias.class)
         .build();
   }
-
-  /** Implementation of cc_toolchain_alias. */
-  public static class CcToolchainAlias implements RuleConfiguredTargetFactory {
-    @Override
-    @Nullable
-    public ConfiguredTarget create(RuleContext ruleContext)
-        throws InterruptedException, RuleErrorException, ActionConflictException {
-
-      CcToolchainProvider ccToolchainProvider =
-          CppHelper.getToolchainUsingDefaultCcToolchainAttribute(ruleContext);
-
-      TemplateVariableInfo templateVariableInfo =
-          CcToolchain.createMakeVariableProvider(
-              ccToolchainProvider, ruleContext.getRule().getLocation());
-
-      ToolchainInfo toolchain =
-          new ToolchainInfo(
-              ImmutableMap.<String, Object>builder()
-                  .put("cc", ccToolchainProvider)
-                  // Add a clear signal that this is a CcToolchainProvider, since just "cc" is
-                  // generic enough to possibly be re-used.
-                  .put("cc_provider_in_toolchain", true)
-                  .build());
-
-      return new RuleConfiguredTargetBuilder(ruleContext)
-          .addProvider(RunfilesProvider.simple(Runfiles.EMPTY))
-          .addNativeDeclaredProvider(ccToolchainProvider)
-          .addNativeDeclaredProvider(toolchain)
-          .addNativeDeclaredProvider(templateVariableInfo)
-          .setFilesToBuild(ccToolchainProvider.getAllFilesIncludingLibc())
-          .build();
-    }
-  }
 }