Add CcToolchainAttributesProvider

This provider encapsulates everything that is cc_toolchain-rule specific and
contributes to the construction of CcToolchainProvider. In the followup cl,
cc_toolchain will be modified to provide CcToolchainAttributesProvider, and
cc_toolchain_suite will get the provider and construct the CcToolchainProvider
from it.

#6072.

RELNOTES: None.
PiperOrigin-RevId: 214762144

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

@@ -17,20 +17,14 @@
 import com.google.devtools.build.lib.actions.MutableActionGraph.ActionConflictException;
 import com.google.devtools.build.lib.analysis.ConfiguredTarget;
 import com.google.devtools.build.lib.analysis.LicensesProvider;
-import com.google.devtools.build.lib.analysis.LicensesProvider.TargetLicense;
-import com.google.devtools.build.lib.analysis.LicensesProviderImpl;
 import com.google.devtools.build.lib.analysis.MiddlemanProvider;
 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.Runfiles;
 import com.google.devtools.build.lib.analysis.RunfilesProvider;
 import com.google.devtools.build.lib.analysis.TemplateVariableInfo;
-import com.google.devtools.build.lib.collect.nestedset.NestedSet;
-import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
-import com.google.devtools.build.lib.collect.nestedset.Order;
 import com.google.devtools.build.lib.events.Location;
-import com.google.devtools.build.lib.packages.License;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import java.util.HashMap;
 
@@ -48,10 +42,13 @@ public class CcToolchain implements RuleConfiguredTargetFactory {
   @Override
   public ConfiguredTarget create(RuleContext ruleContext)
       throws InterruptedException, RuleErrorException, ActionConflictException {
-    CcToolchainProvider ccToolchainProvider =
-        CcToolchainProviderHelper.getCcToolchainProvider(
+    CcToolchainAttributesProvider attributes =
+        new CcToolchainAttributesProvider(
             ruleContext, isAppleToolchain(), getAdditionalBuildVariables(ruleContext));
 
+    CcToolchainProvider ccToolchainProvider =
+        CcToolchainProviderHelper.getCcToolchainProvider(ruleContext, attributes);
+
     if (ccToolchainProvider == null) {
       return null;
     }
@@ -71,22 +68,8 @@ public ConfiguredTarget create(RuleContext ruleContext)
             .addProvider(RunfilesProvider.simple(Runfiles.EMPTY))
             .addProvider(new MiddlemanProvider(ccToolchainProvider.getCrosstoolMiddleman()));
 
-    // If output_license is specified on the cc_toolchain rule, override the transitive licenses
-    // with that one. This is necessary because cc_toolchain is used in the target configuration,
-    // but it is sort-of-kind-of a tool, but various parts of it are linked into the output...
-    // ...so we trust the judgment of the author of the cc_toolchain rule to figure out what
-    // licenses should be propagated to C++ targets.
-    // TODO(elenairina): Remove this and use Attribute.Builder.useOutputLicenses() on the
-    // :cc_toolchain attribute instead.
-    final License outputLicense =
-        ruleContext.getRule().getToolOutputLicense(ruleContext.attributes());
-    if (outputLicense != null && !outputLicense.equals(License.NO_LICENSE)) {
-      final NestedSet<TargetLicense> license = NestedSetBuilder.create(Order.STABLE_ORDER,
-          new TargetLicense(ruleContext.getLabel(), outputLicense));
-      LicensesProvider licensesProvider =
-          new LicensesProviderImpl(
-              license, new TargetLicense(ruleContext.getLabel(), outputLicense));
-      builder.add(LicensesProvider.class, licensesProvider);
+    if (attributes.getLicensesProvider() != null) {
+      builder.add(LicensesProvider.class, attributes.getLicensesProvider());
     }
 
     return builder.build();
@@ -118,8 +101,8 @@ private static TemplateVariableInfo createMakeVariableProvider(
 
   /**
    * Add local build variables from subclasses into {@link CcToolchainVariables} returned from
-   * {@link CcToolchainProviderHelper#getBuildVariables(RuleContext, PathFragment,
-   * CcToolchainVariables)}.
+   * {@link CcToolchainProviderHelper#getBuildVariables(RuleContext, CcToolchainAttributesProvider,
+   * PathFragment, CcToolchainVariables)}.
    *
    * <p>This method is meant to be overridden by subclasses of CcToolchain.
    */