Add toolchains data to RuleClass and RuleContext.

Also expose both sides to Skylark.
Part of bazelbuild#2219.

Change-Id: I4d749dd9981fe33f75310acb0ec3927cff6f28fe
PiperOrigin-RevId: 156340638

src/main/java/com/google/devtools/build/lib/BUILD

@@ -591,6 +591,7 @@ java_library(
         ":util",
         ":vfs",
         "//src/main/java/com/google/devtools/build/lib/actions",
+        "//src/main/java/com/google/devtools/build/lib/analysis/platform",
         "//src/main/java/com/google/devtools/build/lib/buildeventstream/proto:build_event_stream_java_proto",
         "//src/main/java/com/google/devtools/build/lib/causes",
         "//src/main/java/com/google/devtools/build/lib/cmdline",

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

@@ -167,6 +167,7 @@ public ImmutableList<TransitiveInfoCollection> getFiles() {
   private final ErrorReporter reporter;
   private final ImmutableBiMap<String, Class<? extends TransitiveInfoProvider>>
       skylarkProviderRegistry;
+  private final ToolchainContext toolchainContext;
 
   private ActionOwner actionOwner;
 
@@ -197,6 +198,8 @@ private RuleContext(
     this.skylarkProviderRegistry = builder.skylarkProviderRegistry;
     this.hostConfiguration = builder.hostConfiguration;
     reporter = builder.reporter;
+    // TODO(katre): Populate the actual selected toolchains.
+    this.toolchainContext = new ToolchainContext(null);
   }
 
   private ImmutableSet<String> getEnabledFeatures() {
@@ -1121,6 +1124,10 @@ public String expandSingleMakeVariable(String attrName, String expression) {
     }
   }
 
+  public ToolchainContext getToolchainContext() {
+    return toolchainContext;
+  }
+
   private void checkAttribute(String attributeName, Mode mode) {
     Attribute attributeDefinition = attributes.getAttributeDefinition(attributeName);
     if (attributeDefinition == null) {

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

@@ -0,0 +1,38 @@
+// 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.analysis;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.devtools.build.lib.analysis.platform.ToolchainInfo;
+import com.google.devtools.build.lib.packages.ClassObjectConstructor;
+import com.google.devtools.build.lib.syntax.SkylarkDict;
+import java.util.Map;
+import javax.annotation.Nullable;
+
+/** Contains toolchain-related information needed for a {@link RuleContext}. */
+public class ToolchainContext {
+  private final ImmutableMap<ClassObjectConstructor.Key, ToolchainInfo> toolchains;
+
+  public ToolchainContext(@Nullable Map<ClassObjectConstructor.Key, ToolchainInfo> toolchains) {
+    this.toolchains =
+        toolchains == null
+            ? ImmutableMap.<ClassObjectConstructor.Key, ToolchainInfo>of()
+            : ImmutableMap.copyOf(toolchains);
+  }
+
+  public SkylarkDict<ClassObjectConstructor.Key, ToolchainInfo> collectToolchains() {
+    return SkylarkDict.<ClassObjectConstructor.Key, ToolchainInfo>copyOf(null, toolchains);
+  }
+}

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

@@ -508,6 +508,7 @@ public Transition buildTransitionFor(Rule rule) {
     private boolean supportsConstraintChecking = true;
 
     private final Map<String, Attribute> attributes = new LinkedHashMap<>();
+    private final List<ClassObjectConstructor.Key> requiredToolchains = new ArrayList<>();
 
     /**
      * Constructs a new {@code RuleClassBuilder} using all attributes from all
@@ -618,6 +619,7 @@ public RuleClass build(String name) {
           ruleDefinitionEnvironmentHashCode,
           configurationFragmentPolicy.build(),
           supportsConstraintChecking,
+          requiredToolchains,
           attributes.values().toArray(new Attribute[0]));
     }
 
@@ -998,6 +1000,11 @@ public Builder setOptionReferenceFunctionForConfigSettingOnly(
       return this;
     }
 
+    public Builder addRequiredToolchain(ClassObjectConstructor.Key toolchain) {
+      this.requiredToolchains.add(toolchain);
+      return this;
+    }
+
     /**
      * Returns an Attribute.Builder object which contains a replica of the
      * same attribute in the parent rule if exists.
@@ -1118,26 +1125,27 @@ public Attribute.Builder<?> copy(String name) {
    */
   private final boolean supportsConstraintChecking;
 
+  private final ImmutableList<ClassObjectConstructor.Key> requiredToolchains;
+
   /**
-   * Constructs an instance of RuleClass whose name is 'name', attributes
-   * are 'attributes'. The {@code srcsAllowedFiles} determines which types of
-   * files are allowed as parameters to the "srcs" attribute; rules are always
-   * allowed. For the "deps" attribute, there are four cases:
+   * Constructs an instance of RuleClass whose name is 'name', attributes are 'attributes'. The
+   * {@code srcsAllowedFiles} determines which types of files are allowed as parameters to the
+   * "srcs" attribute; rules are always allowed. For the "deps" attribute, there are four cases:
+   *
    * <ul>
-   *   <li>if the parameter is a file, it is allowed if its file type is given
-   *       in {@code depsAllowedFiles},
-   *   <li>if the parameter is a rule and the rule class is accepted by
-   *       {@code depsAllowedRules}, then it is allowed,
-   *   <li>if the parameter is a rule and the rule class is not accepted by
-   *       {@code depsAllowedRules}, but accepted by
-   *       {@code depsAllowedRulesWithWarning}, then it is allowed, but
-   *       triggers a warning;
+   *   <li>if the parameter is a file, it is allowed if its file type is given in {@code
+   *       depsAllowedFiles},
+   *   <li>if the parameter is a rule and the rule class is accepted by {@code depsAllowedRules},
+   *       then it is allowed,
+   *   <li>if the parameter is a rule and the rule class is not accepted by {@code
+   *       depsAllowedRules}, but accepted by {@code depsAllowedRulesWithWarning}, then it is
+   *       allowed, but triggers a warning;
    *   <li>all other parameters trigger an error.
    * </ul>
    *
-   * <p>The {@code depsAllowedRules} predicate should have a {@code toString}
-   * method which returns a plain English enumeration of the allowed rule class
-   * names, if it does not allow all rule classes.
+   * <p>The {@code depsAllowedRules} predicate should have a {@code toString} method which returns a
+   * plain English enumeration of the allowed rule class names, if it does not allow all rule
+   * classes.
    */
   @VisibleForTesting
   RuleClass(
@@ -1165,6 +1173,7 @@ public Attribute.Builder<?> copy(String name) {
       String ruleDefinitionEnvironmentHashCode,
       ConfigurationFragmentPolicy configurationFragmentPolicy,
       boolean supportsConstraintChecking,
+      List<ClassObjectConstructor.Key> requiredToolchains,
       Attribute... attributes) {
     this.name = name;
     this.isSkylark = isSkylark;
@@ -1193,6 +1202,7 @@ public Attribute.Builder<?> copy(String name) {
     this.outputsDefaultExecutable = outputsDefaultExecutable;
     this.configurationFragmentPolicy = configurationFragmentPolicy;
     this.supportsConstraintChecking = supportsConstraintChecking;
+    this.requiredToolchains = ImmutableList.copyOf(requiredToolchains);
 
     // Create the index and collect non-configurable attributes.
     int index = 0;
@@ -2002,6 +2012,10 @@ public boolean outputsDefaultExecutable() {
     return outputsDefaultExecutable;
   }
 
+  public ImmutableList<ClassObjectConstructor.Key> getRequiredToolchains() {
+    return requiredToolchains;
+  }
+
   public static boolean isThirdPartyPackage(PackageIdentifier packageIdentifier) {
     if (!packageIdentifier.getRepository().isMain()) {
       return false;

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

@@ -14,13 +14,14 @@
 package com.google.devtools.build.lib.packages;
 
 import com.google.devtools.build.lib.packages.ClassObjectConstructor.Key;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
 
 /**
  * Constructor that can be used to generate toolchains. The key returned by {@link #getKey()} is a
  * serializable representation of the constructor and serves to identify toolchains of the same
  * type.
  */
-public interface ToolchainConstructor {
+public interface ToolchainConstructor extends SkylarkValue {
 
   Key getKey();
 }