Make native declared providers type-safe.

RELNOTES: None. PiperOrigin-RevId: 161395570
author: dslomov <dslomov@google.com> 2017-07-10 17:15:27 +0200
committer: László Csomor <laszlocsomor@google.com> 2017-07-10 17:45:04 +0200
commit: 77baa4c372ae014db8e17f6d3c60bd88597853d9 (patch)
tree: 3ca2c63943782b506b0f19f5b7f7465909723590
parent: 45bd34e747d13fc2bebdc849a11b4b952da5d8a6 (diff)
59 files changed, 214 insertions, 280 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/ActionsProvider.java b/src/main/java/com/google/devtools/build/lib/analysis/ActionsProvider.java
index f34bc310d2..8eb0f2775c 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/ActionsProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/ActionsProvider.java
@@ -27,11 +27,9 @@ import java.util.Map;
  */
 public final class ActionsProvider {
 
-  /**
-   * The Actions provider type itself. 
-   */
-  public static final NativeClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor("Actions") { };
+  /** The Actions provider type itself. */
+  public static final NativeClassObjectConstructor<SkylarkClassObject> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<SkylarkClassObject>(SkylarkClassObject.class, "Actions") {};
 
   /**
    * Factory method for creating instances of the Actions provider.
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/AnalysisUtils.java b/src/main/java/com/google/devtools/build/lib/analysis/AnalysisUtils.java
index 209eb226ae..966471c37f 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/AnalysisUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/AnalysisUtils.java
@@ -25,7 +25,7 @@ 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.packages.BuildType;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
+import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import com.google.devtools.build.lib.packages.TriState;
 import com.google.devtools.build.lib.vfs.PathFragment;
@@ -82,15 +82,14 @@ public final class AnalysisUtils {
    * Returns the list of declared providers (native and Skylark) of the specified Skylark key from a
    * set of transitive info collections.
    */
-  public static <T extends SkylarkClassObject>  Iterable<T> getProviders(
+  public static <T extends SkylarkClassObject> Iterable<T> getProviders(
       Iterable<? extends TransitiveInfoCollection> prerequisites,
-      final ClassObjectConstructor.Key skylarkKey,
-      Class<T> resultClass) {
+      final NativeClassObjectConstructor<T> skylarkKey) {
     ImmutableList.Builder<T> result = ImmutableList.builder();
     for (TransitiveInfoCollection prerequisite : prerequisites) {
-      SkylarkClassObject prerequisiteProvider = prerequisite.get(skylarkKey);
+      T prerequisiteProvider = prerequisite.get(skylarkKey);
       if (prerequisiteProvider != null) {
-        result.add(resultClass.cast(prerequisiteProvider));
+        result.add(prerequisiteProvider);
       }
     }
     return result.build();
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/DefaultProvider.java b/src/main/java/com/google/devtools/build/lib/analysis/DefaultProvider.java
index 0f0b5569b5..ab0722c6b1 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/DefaultProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/DefaultProvider.java
@@ -48,7 +48,7 @@ public final class DefaultProvider extends SkylarkClassObject {
 
   public static final String SKYLARK_NAME = "DefaultInfo";
   public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor(SKYLARK_NAME) {
+      new NativeClassObjectConstructor<SkylarkClassObject>(SkylarkClassObject.class, SKYLARK_NAME) {
         @Override
         protected SkylarkClassObject createInstanceFromSkylark(Object[] args, Location loc) {
           @SuppressWarnings("unchecked")
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/OutputGroupProvider.java b/src/main/java/com/google/devtools/build/lib/analysis/OutputGroupProvider.java
index 06bbfdcee2..c4265763ec 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/OutputGroupProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/OutputGroupProvider.java
@@ -61,7 +61,8 @@ public final class OutputGroupProvider extends SkylarkClassObject
     implements TransitiveInfoProvider, SkylarkIndexable, Iterable<String> {
   public static final String SKYLARK_NAME = "output_groups";
 
-  public static NativeClassObjectConstructor SKYLARK_CONSTRUCTOR = new Constructor();
+  public static NativeClassObjectConstructor<OutputGroupProvider> SKYLARK_CONSTRUCTOR =
+      new Constructor();
 
   /**
    * Prefix for output groups that are not reported to the user on the terminal output of Blaze when
@@ -256,17 +257,15 @@ public final class OutputGroupProvider extends SkylarkClassObject
     return outputGroups.keySet();
   }
 
-  /**
-   * A constructor callable from Skylark for OutputGroupProvider.
-   */
-  private static class Constructor extends NativeClassObjectConstructor {
+  /** A constructor callable from Skylark for OutputGroupProvider. */
+  private static class Constructor extends NativeClassObjectConstructor<OutputGroupProvider> {
 
     private Constructor() {
-      super("OutputGroupInfo");
+      super(OutputGroupProvider.class, "OutputGroupInfo");
     }
 
     @Override
-    protected SkylarkClassObject createInstanceFromSkylark(Object[] args, Location loc)
+    protected OutputGroupProvider createInstanceFromSkylark(Object[] args, Location loc)
         throws EvalException {
 
       @SuppressWarnings("unchecked")
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
index d2999d3098..c159037231 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
@@ -66,6 +66,7 @@ import com.google.devtools.build.lib.packages.FileTarget;
 import com.google.devtools.build.lib.packages.FilesetEntry;
 import com.google.devtools.build.lib.packages.ImplicitOutputsFunction;
 import com.google.devtools.build.lib.packages.InputFile;
+import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.OutputFile;
 import com.google.devtools.build.lib.packages.PackageSpecification;
 import com.google.devtools.build.lib.packages.RawAttributeMapper;
@@ -851,10 +852,8 @@ public final class RuleContext extends TargetContext
    * specified attribute of this target in the BUILD file.
    */
   public <T extends SkylarkClassObject> Iterable<T> getPrerequisites(
-      String attributeName, Mode mode,
-      final ClassObjectConstructor.Key skylarkKey,
-      Class<T> result) {
-    return AnalysisUtils.getProviders(getPrerequisites(attributeName, mode), skylarkKey, result);
+      String attributeName, Mode mode, final NativeClassObjectConstructor<T> skylarkKey) {
+    return AnalysisUtils.getProviders(getPrerequisites(attributeName, mode), skylarkKey);
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/SkylarkProviderCollection.java b/src/main/java/com/google/devtools/build/lib/analysis/SkylarkProviderCollection.java
index 3289b49f85..cbe80a67d2 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/SkylarkProviderCollection.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/SkylarkProviderCollection.java
@@ -15,6 +15,7 @@
 package com.google.devtools.build.lib.analysis;
 
 import com.google.devtools.build.lib.packages.ClassObjectConstructor;
+import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import com.google.devtools.build.lib.packages.SkylarkProviderIdentifier;
 import javax.annotation.Nullable;
@@ -33,13 +34,24 @@ public interface SkylarkProviderCollection {
   Object get(String providerKey);
 
   /**
-   * Returns the declared provider requested, or null, if the information is not found. The
-   * transitive information has to have been added using the Skylark framework.
+   * Returns the declared provider requested, or null, if the information is not found.
+   *
+   * Use {@link #get(NativeClassObjectConstructor)} for native providers.
    */
   @Nullable
   SkylarkClassObject get(ClassObjectConstructor.Key providerKey);
 
   /**
+   * Returns the native declared provider requested, or null, if the information is not found.
+   *
+   * Type-safe version of {@link #get(ClassObjectConstructor.Key)} for native providers.
+   */
+  @Nullable
+  default <T extends SkylarkClassObject> T get(NativeClassObjectConstructor<T> provider) {
+    return provider.getValueClass().cast(get(provider.getKey()));
+  }
+
+  /**
    * Returns the provider defined in Skylark, or null, if the information is not found. The
    * transitive information has to have been added using the Skylark framework.
    *
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/platform/ConstraintSettingInfo.java b/src/main/java/com/google/devtools/build/lib/analysis/platform/ConstraintSettingInfo.java
index 0e12ba2597..6020817a48 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/platform/ConstraintSettingInfo.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/platform/ConstraintSettingInfo.java
@@ -19,10 +19,8 @@ import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.events.Location;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
-import com.google.devtools.build.lib.packages.SkylarkProviderIdentifier;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
@@ -55,8 +53,9 @@ public class ConstraintSettingInfo extends SkylarkClassObject {
           /*types=*/ ImmutableList.<SkylarkType>of(SkylarkType.of(Label.class)));
 
   /** Skylark constructor and identifier for this provider. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor(SKYLARK_NAME, SIGNATURE) {
+  public static final NativeClassObjectConstructor<ConstraintSettingInfo> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<ConstraintSettingInfo>(
+          ConstraintSettingInfo.class, SKYLARK_NAME, SIGNATURE) {
         @Override
         protected ConstraintSettingInfo createInstanceFromSkylark(Object[] args, Location loc)
             throws EvalException {
@@ -66,10 +65,6 @@ public class ConstraintSettingInfo extends SkylarkClassObject {
         }
       };
 
-  /** Identifier used to retrieve this provider from rules which export it. */
-  public static final SkylarkProviderIdentifier SKYLARK_IDENTIFIER =
-      SkylarkProviderIdentifier.forKey(SKYLARK_CONSTRUCTOR.getKey());
-
   private final Label label;
 
   private ConstraintSettingInfo(Label label, Location location) {
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/platform/ConstraintValueInfo.java b/src/main/java/com/google/devtools/build/lib/analysis/platform/ConstraintValueInfo.java
index be11feaba6..9cd1fac8ce 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/platform/ConstraintValueInfo.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/platform/ConstraintValueInfo.java
@@ -19,10 +19,8 @@ import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.events.Location;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
-import com.google.devtools.build.lib.packages.SkylarkProviderIdentifier;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
@@ -57,8 +55,9 @@ public class ConstraintValueInfo extends SkylarkClassObject {
               SkylarkType.of(Label.class), SkylarkType.of(ConstraintSettingInfo.class)));
 
   /** Skylark constructor and identifier for this provider. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor(SKYLARK_NAME, SIGNATURE) {
+  public static final NativeClassObjectConstructor<ConstraintValueInfo> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<ConstraintValueInfo>(
+          ConstraintValueInfo.class, SKYLARK_NAME, SIGNATURE) {
         @Override
         protected ConstraintValueInfo createInstanceFromSkylark(Object[] args, Location loc)
             throws EvalException {
@@ -69,10 +68,6 @@ public class ConstraintValueInfo extends SkylarkClassObject {
         }
       };
 
-  /** Identifier used to retrieve this provider from rules which export it. */
-  public static final SkylarkProviderIdentifier SKYLARK_IDENTIFIER =
-      SkylarkProviderIdentifier.forKey(SKYLARK_CONSTRUCTOR.getKey());
-
   private final ConstraintSettingInfo constraint;
   private final Label label;
 
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/platform/PlatformInfo.java b/src/main/java/com/google/devtools/build/lib/analysis/platform/PlatformInfo.java
index 003896d055..1d1092a9a3 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/platform/PlatformInfo.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/platform/PlatformInfo.java
@@ -22,10 +22,8 @@ import com.google.common.collect.Multimap;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.events.Location;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
-import com.google.devtools.build.lib.packages.SkylarkProviderIdentifier;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
@@ -67,8 +65,8 @@ public class PlatformInfo extends SkylarkClassObject {
                   SkylarkType.LIST, SkylarkType.of(ConstraintValueInfo.class))));
 
   /** Skylark constructor and identifier for this provider. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor(SKYLARK_NAME, SIGNATURE) {
+  public static final NativeClassObjectConstructor<PlatformInfo> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<PlatformInfo>(PlatformInfo.class, SKYLARK_NAME, SIGNATURE) {
         @Override
         protected PlatformInfo createInstanceFromSkylark(Object[] args, Location loc)
             throws EvalException {
@@ -91,10 +89,6 @@ public class PlatformInfo extends SkylarkClassObject {
         }
       };
 
-  /** Identifier used to retrieve this provider from rules which export it. */
-  public static final SkylarkProviderIdentifier SKYLARK_IDENTIFIER =
-      SkylarkProviderIdentifier.forKey(SKYLARK_CONSTRUCTOR.getKey());
-
   private final Label label;
   private final ImmutableList<ConstraintValueInfo> constraints;
   private final ImmutableMap<String, String> remoteExecutionProperties;
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/platform/PlatformProviderUtils.java b/src/main/java/com/google/devtools/build/lib/analysis/platform/PlatformProviderUtils.java
index 56443af320..148fea7ab3 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/platform/PlatformProviderUtils.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/platform/PlatformProviderUtils.java
@@ -16,19 +16,13 @@ package com.google.devtools.build.lib.analysis.platform;
 
 import com.google.common.collect.Iterables;
 import com.google.devtools.build.lib.analysis.SkylarkProviderCollection;
-import com.google.devtools.build.lib.util.Preconditions;
 
 /** Utility methods to help locate platform-related providers. */
 public class PlatformProviderUtils {
 
   /** Retrieves and casts the {@link PlatformInfo} provider from the given target. */
   public static PlatformInfo platform(SkylarkProviderCollection target) {
-    Object provider = target.get(PlatformInfo.SKYLARK_IDENTIFIER);
-    if (provider == null) {
-      return null;
-    }
-    Preconditions.checkState(provider instanceof PlatformInfo);
-    return (PlatformInfo) provider;
+    return target.get(PlatformInfo.SKYLARK_CONSTRUCTOR);
   }
 
   /** Retrieves and casts {@link PlatformInfo} providers from the given targets. */
@@ -39,12 +33,7 @@ public class PlatformProviderUtils {
 
   /** Retrieves and casts the {@link ConstraintSettingInfo} provider from the given target. */
   public static ConstraintSettingInfo constraintSetting(SkylarkProviderCollection target) {
-    Object provider = target.get(ConstraintSettingInfo.SKYLARK_IDENTIFIER);
-    if (provider == null) {
-      return null;
-    }
-    Preconditions.checkState(provider instanceof ConstraintSettingInfo);
-    return (ConstraintSettingInfo) provider;
+    return target.get(ConstraintSettingInfo.SKYLARK_CONSTRUCTOR);
   }
 
   /** Retrieves and casts {@link ConstraintSettingInfo} providers from the given targets. */
@@ -55,12 +44,7 @@ public class PlatformProviderUtils {
 
   /** Retrieves and casts the {@link ConstraintValueInfo} provider from the given target. */
   public static ConstraintValueInfo constraintValue(SkylarkProviderCollection target) {
-    Object provider = target.get(ConstraintValueInfo.SKYLARK_IDENTIFIER);
-    if (provider == null) {
-      return null;
-    }
-    Preconditions.checkState(provider instanceof ConstraintValueInfo);
-    return (ConstraintValueInfo) provider;
+    return target.get(ConstraintValueInfo.SKYLARK_CONSTRUCTOR);
   }
 
   /** Retrieves and casts {@link ConstraintValueInfo} providers from the given targets. */
@@ -71,11 +55,6 @@ public class PlatformProviderUtils {
 
   /** Retrieves and casts the {@link ToolchainInfo} provider from the given target. */
   public static ToolchainInfo toolchain(SkylarkProviderCollection target) {
-    Object provider = target.get(ToolchainInfo.SKYLARK_IDENTIFIER);
-    if (provider == null) {
-      return null;
-    }
-    Preconditions.checkState(provider instanceof ToolchainInfo);
-    return (ToolchainInfo) provider;
+    return target.get(ToolchainInfo.SKYLARK_CONSTRUCTOR);
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/platform/ToolchainInfo.java b/src/main/java/com/google/devtools/build/lib/analysis/platform/ToolchainInfo.java
index 0a3c6a4639..16e5a857ac 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/platform/ToolchainInfo.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/platform/ToolchainInfo.java
@@ -19,10 +19,8 @@ import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.events.Location;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
-import com.google.devtools.build.lib.packages.SkylarkProviderIdentifier;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModuleCategory;
 import com.google.devtools.build.lib.syntax.EvalException;
@@ -60,8 +58,9 @@ public class ToolchainInfo extends SkylarkClassObject {
           /*types=*/ ImmutableList.<SkylarkType>of(SkylarkType.of(Label.class), SkylarkType.DICT));
 
   /** Skylark constructor and identifier for this provider. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor(SKYLARK_NAME, SIGNATURE) {
+  public static final NativeClassObjectConstructor<ToolchainInfo> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<ToolchainInfo>(
+          ToolchainInfo.class, SKYLARK_NAME, SIGNATURE) {
         @Override
         protected ToolchainInfo createInstanceFromSkylark(Object[] args, Location loc)
             throws EvalException {
@@ -73,10 +72,6 @@ public class ToolchainInfo extends SkylarkClassObject {
         }
       };
 
-  /** Identifier used to retrieve this provider from rules which export it. */
-  public static final SkylarkProviderIdentifier SKYLARK_IDENTIFIER =
-      SkylarkProviderIdentifier.forKey(SKYLARK_CONSTRUCTOR.getKey());
-
   private final Label type;
 
   private ToolchainInfo(Label type, Map<String, Object> toolchainData, Location loc) {
diff --git a/src/main/java/com/google/devtools/build/lib/packages/Attribute.java b/src/main/java/com/google/devtools/build/lib/packages/Attribute.java
index ee2f8ac88f..a312aeff95 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/Attribute.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/Attribute.java
@@ -998,6 +998,11 @@ public final class Attribute implements Comparable<Attribute> {
       return this;
     }
 
+    public Builder<TYPE> mandatoryProviders(SkylarkProviderIdentifier... providers) {
+      mandatoryProviders(Arrays.asList(providers));
+      return this;
+    }
+
     /**
      * Asserts that a particular parameterized aspect probably needs to be computed for all direct
      * dependencies through this attribute.
diff --git a/src/main/java/com/google/devtools/build/lib/packages/ClassObjectConstructor.java b/src/main/java/com/google/devtools/build/lib/packages/ClassObjectConstructor.java
index 9bce718d38..de48d2c41b 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/ClassObjectConstructor.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/ClassObjectConstructor.java
@@ -92,6 +92,9 @@ public abstract class ClassObjectConstructor extends BaseFunction {
    */
   public abstract String getErrorMessageFormatForInstances();
 
+  public SkylarkProviderIdentifier id() {
+    return SkylarkProviderIdentifier.forKey(getKey());
+  }
 
   @Override
   protected Object call(Object[] args, @Nullable FuncallExpression ast, @Nullable Environment env)
diff --git a/src/main/java/com/google/devtools/build/lib/packages/NativeClassObjectConstructor.java b/src/main/java/com/google/devtools/build/lib/packages/NativeClassObjectConstructor.java
index b3fd87e73f..2ed7e51b81 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/NativeClassObjectConstructor.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/NativeClassObjectConstructor.java
@@ -23,24 +23,25 @@ import java.util.Map;
 import javax.annotation.Nullable;
 
 /**
- * Base class for declared providers {@see ClassObjectConstructor} defined
- * in native code.
+ * Base class for declared providers {@see ClassObjectConstructor} defined in native code.
  *
- * Every non-abstract derived class of {@link NativeClassObjectConstructor}
- * corresponds to a single declared provider. This is enforced by final
- * {@link #equals(Object)} and {@link #hashCode()}.
+ * <p>Every non-abstract derived class of {@link NativeClassObjectConstructor} corresponds to a
+ * single declared provider. This is enforced by final {@link #equals(Object)} and {@link
+ * #hashCode()}.
+ *
+ * <p>Typical implementation of a non-constructable from Skylark declared provider is as follows:
  *
- * Typical implementation of a non-constructable from Skylark declared provider is as follows:
  * <pre>
  *     public static final ClassObjectConstructor CC_LINK_PARAMS =
  *       new NativeClassObjectConstructor("link_params") { };
  * </pre>
  *
- * To allow construction from Skylark and custom construction logic, override
- * {@link #createInstanceFromSkylark(Object[], Location)} (see {@link #STRUCT} for an example.
+ * To allow construction from Skylark and custom construction logic, override {@link
+ * #createInstanceFromSkylark(Object[], Location)} (see {@link #STRUCT} for an example.
  */
 @Immutable
-public abstract class NativeClassObjectConstructor extends ClassObjectConstructor {
+public abstract class NativeClassObjectConstructor<VALUE extends SkylarkClassObject>
+    extends ClassObjectConstructor {
   private final NativeKey key;
   private final String errorMessageForInstances;
 
@@ -49,14 +50,21 @@ public abstract class NativeClassObjectConstructor extends ClassObjectConstructo
    */
   public static final StructConstructor STRUCT = new StructConstructor();
 
+  private final Class<VALUE> valueClass;
+
+  public Class<VALUE> getValueClass() {
+    return valueClass;
+  }
+
   /**
    * A constructor for default {@code struct}s.
    *
-   * Singleton, instance is {@link #STRUCT}.
+   * <p>Singleton, instance is {@link #STRUCT}.
    */
-  public static final class StructConstructor extends NativeClassObjectConstructor {
+  public static final class StructConstructor
+      extends NativeClassObjectConstructor<SkylarkClassObject> {
     private StructConstructor() {
-      super("struct");
+      super(SkylarkClassObject.class, "struct");
     }
 
     @Override
@@ -74,16 +82,18 @@ public abstract class NativeClassObjectConstructor extends ClassObjectConstructo
   private static final FunctionSignature.WithValues<Object, SkylarkType> SIGNATURE =
       FunctionSignature.WithValues.create(FunctionSignature.KWARGS);
 
-  protected NativeClassObjectConstructor(String name) {
-    this(name, SIGNATURE);
+  protected NativeClassObjectConstructor(Class<VALUE> clazz, String name) {
+    this(clazz, name, SIGNATURE);
   }
 
-  protected NativeClassObjectConstructor(String name,
+  protected NativeClassObjectConstructor(
+      Class<VALUE> valueClass,
+      String name,
       FunctionSignature.WithValues<Object, SkylarkType> signature) {
     super(name, signature, Location.BUILTIN);
     key = new NativeKey(name, getClass());
+    this.valueClass = valueClass;
     errorMessageForInstances = String.format("'%s' object has no attribute '%%s'", name);
-
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/rules/MakeVariableProvider.java b/src/main/java/com/google/devtools/build/lib/rules/MakeVariableProvider.java
index 15d4998c7f..46ad5446b5 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/MakeVariableProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/MakeVariableProvider.java
@@ -31,7 +31,8 @@ public final class MakeVariableProvider extends SkylarkClassObject
   public static final String SKYLARK_NAME = "MakeVariableInfo";
 
   public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor(SKYLARK_NAME) {};
+      new NativeClassObjectConstructor<MakeVariableProvider>(
+          MakeVariableProvider.class, SKYLARK_NAME) {};
 
   private final ImmutableMap<String, String> makeVariables;
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidCommon.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidCommon.java
index dafdb335a6..4fefee34f5 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidCommon.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidCommon.java
@@ -38,9 +38,9 @@ import com.google.devtools.build.lib.collect.nestedset.Order;
 import com.google.devtools.build.lib.packages.AggregatingAttributeMapper;
 import com.google.devtools.build.lib.packages.AttributeMap;
 import com.google.devtools.build.lib.packages.BuildType;
+import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.Rule;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
-import com.google.devtools.build.lib.packages.SkylarkClassObjectConstructor;
 import com.google.devtools.build.lib.packages.TriState;
 import com.google.devtools.build.lib.rules.android.ResourceContainer.ResourceType;
 import com.google.devtools.build.lib.rules.cpp.CcLinkParams;
@@ -100,13 +100,12 @@ public class AndroidCommon {
   }
 
   public static final <T extends SkylarkClassObject> Iterable<T> getTransitivePrerequisites(
-      RuleContext ruleContext, Mode mode, SkylarkClassObjectConstructor.Key key,
-      final Class<T> classType) {
+      RuleContext ruleContext, Mode mode, NativeClassObjectConstructor<T> key) {
     IterablesChain.Builder<T> builder = IterablesChain.builder();
     AttributeMap attributes = ruleContext.attributes();
     for (String attr : TRANSITIVE_ATTRIBUTES) {
       if (attributes.has(attr, BuildType.LABEL_LIST)) {
-        builder.add(ruleContext.getPrerequisites(attr, mode, key, classType));
+        builder.add(ruleContext.getPrerequisites(attr, mode, key));
       }
     }
     return builder.build();
@@ -938,9 +937,8 @@ public class AndroidCommon {
   private NestedSet<Artifact> collectHiddenTopLevelArtifacts(RuleContext ruleContext) {
     NestedSetBuilder<Artifact> builder = NestedSetBuilder.stableOrder();
     for (OutputGroupProvider provider :
-        getTransitivePrerequisites(ruleContext, Mode.TARGET,
-            OutputGroupProvider.SKYLARK_CONSTRUCTOR.getKey(),
-            OutputGroupProvider.class)) {
+        getTransitivePrerequisites(
+            ruleContext, Mode.TARGET, OutputGroupProvider.SKYLARK_CONSTRUCTOR)) {
       builder.addTransitive(provider.getOutputGroup(OutputGroupProvider.HIDDEN_TOP_LEVEL));
     }
     return builder.build();
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidDeviceScriptFixtureInfoProvider.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidDeviceScriptFixtureInfoProvider.java
index 42b7b11a70..8d44854a39 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidDeviceScriptFixtureInfoProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidDeviceScriptFixtureInfoProvider.java
@@ -30,8 +30,10 @@ public class AndroidDeviceScriptFixtureInfoProvider extends SkylarkClassObject
     implements TransitiveInfoProvider {
 
   private static final String SKYLARK_NAME = "DeviceScriptFixtureInfo";
-  public static final NativeClassObjectConstructor ANDROID_DEVICE_SCRIPT_FIXTURE_INFO =
-      new NativeClassObjectConstructor(SKYLARK_NAME) {};
+  public static final NativeClassObjectConstructor<AndroidDeviceScriptFixtureInfoProvider>
+      ANDROID_DEVICE_SCRIPT_FIXTURE_INFO =
+          new NativeClassObjectConstructor<AndroidDeviceScriptFixtureInfoProvider>(
+              AndroidDeviceScriptFixtureInfoProvider.class, SKYLARK_NAME) {};
 
   private final Artifact fixtureScript;
   private final NestedSet<Artifact> supportApks;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidHostServiceFixtureInfoProvider.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidHostServiceFixtureInfoProvider.java
index 3acd378695..a554a39b3d 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidHostServiceFixtureInfoProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidHostServiceFixtureInfoProvider.java
@@ -31,8 +31,10 @@ public class AndroidHostServiceFixtureInfoProvider extends SkylarkClassObject
     implements TransitiveInfoProvider {
 
   private static final String SKYLARK_NAME = "HostServiceFixtureInfo";
-  static final NativeClassObjectConstructor ANDROID_HOST_SERVICE_FIXTURE_INFO =
-      new NativeClassObjectConstructor(SKYLARK_NAME) {};
+  static final NativeClassObjectConstructor<AndroidHostServiceFixtureInfoProvider>
+      ANDROID_HOST_SERVICE_FIXTURE_INFO =
+          new NativeClassObjectConstructor<AndroidHostServiceFixtureInfoProvider>(
+              AndroidHostServiceFixtureInfoProvider.class, SKYLARK_NAME) {};
 
   private final Artifact executable;
   private final ImmutableList<String> serviceNames;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationInfoProvider.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationInfoProvider.java
index 63a8fb353e..e151be796b 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationInfoProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationInfoProvider.java
@@ -29,9 +29,10 @@ public class AndroidInstrumentationInfoProvider extends SkylarkClassObject
     implements TransitiveInfoProvider {
 
   private static final String SKYLARK_NAME = "AndroidInstrumentationInfo";
-  static final NativeClassObjectConstructor ANDROID_INSTRUMENTATION_INFO =
-      new NativeClassObjectConstructor(SKYLARK_NAME) {
-      };
+  static final NativeClassObjectConstructor<AndroidInstrumentationInfoProvider>
+      ANDROID_INSTRUMENTATION_INFO =
+          new NativeClassObjectConstructor<AndroidInstrumentationInfoProvider>(
+              AndroidInstrumentationInfoProvider.class, SKYLARK_NAME) {};
 
   private final Artifact targetApk;
   private final Artifact instrumentationApk;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationTest.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationTest.java
index 20066b36c3..92a9cdd538 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationTest.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationTest.java
@@ -184,8 +184,7 @@ public class AndroidInstrumentationTest implements RuleConfiguredTargetFactory {
         ruleContext.getPrerequisites(
             "instrumentations",
             Mode.TARGET,
-            AndroidInstrumentationInfoProvider.ANDROID_INSTRUMENTATION_INFO.getKey(),
-            AndroidInstrumentationInfoProvider.class),
+            AndroidInstrumentationInfoProvider.ANDROID_INSTRUMENTATION_INFO),
         AndroidInstrumentationInfoProvider::getTargetApk);
   }
 
@@ -198,8 +197,7 @@ public class AndroidInstrumentationTest implements RuleConfiguredTargetFactory {
         ruleContext.getPrerequisites(
             "instrumentations",
             Mode.TARGET,
-            AndroidInstrumentationInfoProvider.ANDROID_INSTRUMENTATION_INFO.getKey(),
-            AndroidInstrumentationInfoProvider.class),
+            AndroidInstrumentationInfoProvider.ANDROID_INSTRUMENTATION_INFO),
         AndroidInstrumentationInfoProvider::getInstrumentationApk);
   }
 
@@ -217,8 +215,7 @@ public class AndroidInstrumentationTest implements RuleConfiguredTargetFactory {
         ruleContext.getPrerequisites(
             "fixtures",
             Mode.TARGET,
-            AndroidInstrumentationInfoProvider.ANDROID_INSTRUMENTATION_INFO.getKey(),
-            AndroidHostServiceFixtureInfoProvider.class)) {
+            AndroidHostServiceFixtureInfoProvider.ANDROID_HOST_SERVICE_FIXTURE_INFO)) {
       allSupportApks.addTransitive(fixture.getSupportApks());
     }
     return allSupportApks.build();
@@ -271,8 +268,7 @@ public class AndroidInstrumentationTest implements RuleConfiguredTargetFactory {
             ruleContext.getPrerequisites(
                 "fixtures",
                 Mode.TARGET,
-                AndroidHostServiceFixtureInfoProvider.ANDROID_HOST_SERVICE_FIXTURE_INFO.getKey(),
-                AndroidHostServiceFixtureInfoProvider.class));
+                AndroidHostServiceFixtureInfoProvider.ANDROID_HOST_SERVICE_FIXTURE_INFO));
     if (hostServiceFixtures.size() > 1) {
       ruleContext.ruleError(
           "android_instrumentation_test accepts at most one android_host_service_fixture");
@@ -285,8 +281,7 @@ public class AndroidInstrumentationTest implements RuleConfiguredTargetFactory {
     return ruleContext.getPrerequisites(
         "fixtures",
         Mode.TARGET,
-        AndroidDeviceScriptFixtureInfoProvider.ANDROID_DEVICE_SCRIPT_FIXTURE_INFO.getKey(),
-        AndroidDeviceScriptFixtureInfoProvider.class);
+        AndroidDeviceScriptFixtureInfoProvider.ANDROID_DEVICE_SCRIPT_FIXTURE_INFO);
   }
 
   private static String getDeviceBrokerType(RuleContext ruleContext) {
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java
index ac9fb18fe5..052e0c170f 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java
@@ -904,7 +904,7 @@ public final class AndroidRuleClasses {
                   .allowedFileTypes()
                   .nonconfigurable("defines an aspect of configuration")
                   .mandatoryProviders(
-                      ImmutableList.of(ConfigFeatureFlagProvider.SKYLARK_IDENTIFIER)))
+                      ImmutableList.of(ConfigFeatureFlagProvider.SKYLARK_CONSTRUCTOR.id())))
           // The resource extractor is used at the binary level to extract java resources from the
           // deploy jar so that they can be added to the APK.
           .add(
diff --git a/src/main/java/com/google/devtools/build/lib/rules/apple/ApplePlatform.java b/src/main/java/com/google/devtools/build/lib/rules/apple/ApplePlatform.java
index eebde008e7..8e047c31c0 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/apple/ApplePlatform.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/apple/ApplePlatform.java
@@ -186,7 +186,9 @@ public enum ApplePlatform {
 
   /** Returns a Skylark struct that contains the instances of this enum. */
   public static SkylarkClassObject getSkylarkStruct() {
-    ClassObjectConstructor constructor = new NativeClassObjectConstructor("platforms") { };
+    ClassObjectConstructor constructor =
+        new NativeClassObjectConstructor<SkylarkClassObject>(
+            SkylarkClassObject.class, "platforms") {};
     HashMap<String, Object> fields = new HashMap<>();
     for (ApplePlatform type : values()) {
       fields.put(type.skylarkKey, type);
@@ -242,7 +244,9 @@ public enum ApplePlatform {
 
     /** Returns a Skylark struct that contains the instances of this enum. */
     public static SkylarkClassObject getSkylarkStruct() {
-      ClassObjectConstructor constructor = new NativeClassObjectConstructor("platform_types") { };
+      ClassObjectConstructor constructor =
+          new NativeClassObjectConstructor<SkylarkClassObject>(
+              SkylarkClassObject.class, "platform_types") {};
       HashMap<String, Object> fields = new HashMap<>();
       for (PlatformType type : values()) {
         fields.put(type.skylarkKey, type);
diff --git a/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeVersionProperties.java b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeVersionProperties.java
index e52726f454..0e872c5e74 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeVersionProperties.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/apple/XcodeVersionProperties.java
@@ -20,7 +20,6 @@ import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import java.util.Map;
@@ -34,8 +33,9 @@ public class XcodeVersionProperties extends SkylarkClassObject implements Transi
   public static final String SKYLARK_NAME = "XcodeProperties";
 
   /** Skylark constructor and identifier for XcodeVersionProperties provider. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor(SKYLARK_NAME) { };
+  public static final NativeClassObjectConstructor<XcodeVersionProperties> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<XcodeVersionProperties>(
+          XcodeVersionProperties.class, SKYLARK_NAME) {};
 
   @VisibleForTesting public static final String DEFAULT_IOS_SDK_VERSION = "8.4";
   @VisibleForTesting public static final String DEFAULT_WATCHOS_SDK_VERSION = "2.0";
diff --git a/src/main/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagProvider.java b/src/main/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagProvider.java
index 9f6e919fbd..13ba415d34 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/config/ConfigFeatureFlagProvider.java
@@ -19,14 +19,11 @@ import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.analysis.TransitiveInfoCollection;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
-import com.google.devtools.build.lib.packages.SkylarkProviderIdentifier;
 import com.google.devtools.build.lib.skylarkinterface.Param;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
-import com.google.devtools.build.lib.util.Preconditions;
 
 /** Provider for exporting value and valid value predicate of feature flags to consuming targets. */
 @SkylarkModule(
@@ -41,17 +38,9 @@ public class ConfigFeatureFlagProvider extends SkylarkClassObject
   static final String SKYLARK_NAME = "FeatureFlagInfo";
 
   /** Skylark constructor and identifier for ConfigFeatureFlagProvider. */
-  static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor(SKYLARK_NAME) {};
-
-  /**
-   * Identifier used to retrieve this provider from rules which export it.
-   *
-   * <p>Prefer to use {@link #fromTarget(TransitiveInfoCollection)} for the purposes of getting this
-   * provider from a TransitiveInfoCollection; this should be used for mandatoryProviders only.
-   */
-  public static final SkylarkProviderIdentifier SKYLARK_IDENTIFIER =
-      SkylarkProviderIdentifier.forKey(SKYLARK_CONSTRUCTOR.getKey());
+  public static final NativeClassObjectConstructor<ConfigFeatureFlagProvider> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<ConfigFeatureFlagProvider>(
+          ConfigFeatureFlagProvider.class, SKYLARK_NAME) {};
 
   private final String value;
   private final Predicate<String> validityPredicate;
@@ -70,12 +59,7 @@ public class ConfigFeatureFlagProvider extends SkylarkClassObject
 
   /** Retrieves and casts the provider from the given target. */
   public static ConfigFeatureFlagProvider fromTarget(TransitiveInfoCollection target) {
-    Object provider = target.get(SKYLARK_IDENTIFIER);
-    if (provider == null) {
-      return null;
-    }
-    Preconditions.checkState(provider instanceof ConfigFeatureFlagProvider);
-    return (ConfigFeatureFlagProvider) provider;
+    return target.get(SKYLARK_CONSTRUCTOR);
   }
 
   /** Gets the current value of the flag in the flag's current configuration. */
diff --git a/src/main/java/com/google/devtools/build/lib/rules/config/ConfigRuleClasses.java b/src/main/java/com/google/devtools/build/lib/rules/config/ConfigRuleClasses.java
index dcfe505a61..4bd368415a 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/config/ConfigRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/config/ConfigRuleClasses.java
@@ -154,7 +154,7 @@ public class ConfigRuleClasses {
                   .undocumented("the feature flag feature has not yet been launched")
                   .allowedFileTypes()
                   .mandatoryProviders(
-                      ImmutableList.of(ConfigFeatureFlagProvider.SKYLARK_IDENTIFIER))
+                      ImmutableList.of(ConfigFeatureFlagProvider.SKYLARK_CONSTRUCTOR.id()))
                   .nonconfigurable(NONCONFIGURABLE_ATTRIBUTE_REASON))
           .requiresConfigurationFragments(FeaturePolicyConfiguration.class)
           .setIsConfigMatcherForConfigSettingOnly()
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLibrary.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLibrary.java
index 7b7906a529..f081075e03 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLibrary.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLibrary.java
@@ -312,9 +312,8 @@ public abstract class CcLibrary implements RuleConfiguredTargetFactory {
         ccCompilationOutputs.getFilesToCompile(
             isLipoCollector, processHeadersInDependencies, usePic));
     for (OutputGroupProvider dep :
-        ruleContext.getPrerequisites("deps", Mode.TARGET,
-            OutputGroupProvider.SKYLARK_CONSTRUCTOR.getKey(),
-            OutputGroupProvider.class)) {
+        ruleContext.getPrerequisites(
+            "deps", Mode.TARGET, OutputGroupProvider.SKYLARK_CONSTRUCTOR)) {
       artifactsToForceBuilder.addTransitive(
           dep.getOutputGroup(OutputGroupProvider.HIDDEN_TOP_LEVEL));
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLibraryHelper.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLibraryHelper.java
index 3c7aa425c2..2618fee2d8 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLibraryHelper.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLibraryHelper.java
@@ -1487,8 +1487,8 @@ public final class CcLibraryHelper {
       RuleContext ruleContext, CcCompilationOutputs ccCompilationOutputs) {
     NestedSetBuilder<Artifact> headerTokens = NestedSetBuilder.stableOrder();
     for (OutputGroupProvider dep :
-        ruleContext.getPrerequisites("deps", Mode.TARGET,
-            OutputGroupProvider.SKYLARK_CONSTRUCTOR.getKey(), OutputGroupProvider.class)) {
+        ruleContext.getPrerequisites(
+            "deps", Mode.TARGET, OutputGroupProvider.SKYLARK_CONSTRUCTOR)) {
       headerTokens.addTransitive(dep.getOutputGroup(CcLibraryHelper.HIDDEN_HEADER_TOKENS));
     }
     if (ruleContext.getFragment(CppConfiguration.class).processHeadersInDependencies()) {
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLinkParamsProvider.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLinkParamsProvider.java
index 76a6c768f3..1ed8d6f169 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLinkParamsProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcLinkParamsProvider.java
@@ -19,7 +19,6 @@ import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.analysis.TransitiveInfoCollection;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import com.google.devtools.build.lib.rules.cpp.CcLinkParamsStore.CcLinkParamsStoreImpl;
@@ -28,8 +27,9 @@ import com.google.devtools.build.lib.rules.cpp.CcLinkParamsStore.CcLinkParamsSto
 @Immutable
 public final class CcLinkParamsProvider extends SkylarkClassObject
     implements TransitiveInfoProvider {
-  public static final ClassObjectConstructor CC_LINK_PARAMS =
-      new NativeClassObjectConstructor("link_params") { };
+  public static final NativeClassObjectConstructor<CcLinkParamsProvider> CC_LINK_PARAMS =
+      new NativeClassObjectConstructor<CcLinkParamsProvider>(
+          CcLinkParamsProvider.class, "link_params") {};
   public static final Function<TransitiveInfoCollection, CcLinkParamsStore> TO_LINK_PARAMS =
       input -> {
 
@@ -40,7 +40,7 @@ public final class CcLinkParamsProvider extends SkylarkClassObject
         }
 
         // ... then try Skylark.
-        provider = (CcLinkParamsProvider) input.get(CC_LINK_PARAMS.getKey());
+        provider = input.get(CC_LINK_PARAMS);
         if (provider != null) {
           return provider.getCcLinkParamsStore();
         }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchainProvider.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchainProvider.java
index 89beafe21d..29715a7d78 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchainProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcToolchainProvider.java
@@ -22,7 +22,6 @@ 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.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
@@ -45,8 +44,9 @@ public final class CcToolchainProvider
     extends SkylarkClassObject implements TransitiveInfoProvider {
   public static final String SKYLARK_NAME = "CcToolchainInfo";
 
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor(SKYLARK_NAME) {};
+  public static final NativeClassObjectConstructor<CcToolchainProvider> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<CcToolchainProvider>(
+          CcToolchainProvider.class, SKYLARK_NAME) {};
 
   /** An empty toolchain to be returned in the error case (instead of null). */
   public static final CcToolchainProvider EMPTY_TOOLCHAIN_IS_ERROR =
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaCommon.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaCommon.java
index 5779e65cfc..bb6fe7e905 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaCommon.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaCommon.java
@@ -40,7 +40,7 @@ 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.packages.BuildType;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
+import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import com.google.devtools.build.lib.packages.Target;
 import com.google.devtools.build.lib.packages.TargetUtils;
@@ -880,12 +880,10 @@ public class JavaCommon {
     return AnalysisUtils.getProviders(getDependencies(), provider);
   }
 
-  /**
-   * Gets all the deps that implement a particular provider.
-   */
+  /** Gets all the deps that implement a particular provider. */
   public final <P extends SkylarkClassObject> Iterable<P> getDependencies(
-      ClassObjectConstructor.Key provider, Class<P> resultClass) {
-    return AnalysisUtils.getProviders(getDependencies(), provider, resultClass);
+      NativeClassObjectConstructor<P> provider) {
+    return AnalysisUtils.getProviders(getDependencies(), provider);
   }
 
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaProvider.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaProvider.java
index 4e7ed9f11a..4599ceeb58 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaProvider.java
@@ -24,7 +24,6 @@ import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProviderMap;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProviderMapBuilder;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import com.google.devtools.build.lib.syntax.SkylarkNestedSet;
@@ -37,8 +36,8 @@ import javax.annotation.Nullable;
 @Immutable
 public final class JavaProvider extends SkylarkClassObject implements TransitiveInfoProvider {
 
-  public static final ClassObjectConstructor JAVA_PROVIDER =
-      new NativeClassObjectConstructor("java_common.provider") { };
+  public static final NativeClassObjectConstructor<JavaProvider> JAVA_PROVIDER =
+      new NativeClassObjectConstructor<JavaProvider>(JavaProvider.class, "java_common.provider") {};
 
   private static final ImmutableSet<Class<? extends TransitiveInfoProvider>> ALLOWED_PROVIDERS =
       ImmutableSet.of(
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleBinary.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleBinary.java
index 40eaeb8421..6bbfc3bbac 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleBinary.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleBinary.java
@@ -259,9 +259,8 @@ public class AppleBinary implements RuleConfiguredTargetFactory {
   private static Iterable<ObjcProvider> getDylibProviders(RuleContext ruleContext) {
     ImmutableList.Builder<ObjcProvider> dylibProviders = ImmutableList.builder();
     Iterable<AppleDynamicFrameworkProvider> frameworkProviders =
-        ruleContext.getPrerequisites(DYLIBS_ATTR_NAME, Mode.TARGET,
-            AppleDynamicFrameworkProvider.SKYLARK_CONSTRUCTOR.getKey(),
-            AppleDynamicFrameworkProvider.class);
+        ruleContext.getPrerequisites(
+            DYLIBS_ATTR_NAME, Mode.TARGET, AppleDynamicFrameworkProvider.SKYLARK_CONSTRUCTOR);
     for (AppleDynamicFrameworkProvider frameworkProvider : frameworkProviders) {
       dylibProviders.add(frameworkProvider.getDepsObjcProvider());
     }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleDebugOutputsProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleDebugOutputsProvider.java
index eadabb9c57..10ff0d389d 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleDebugOutputsProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleDebugOutputsProvider.java
@@ -18,7 +18,6 @@ import com.google.common.collect.Maps;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import java.util.HashMap;
@@ -64,8 +63,9 @@ public final class AppleDebugOutputsProvider extends SkylarkClassObject
   public static final String SKYLARK_NAME = "AppleDebugOutputs";
 
   /** Skylark constructor and identifier for AppleDebugOutputsProvider. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor(SKYLARK_NAME) { };
+  public static final NativeClassObjectConstructor<AppleDebugOutputsProvider> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<AppleDebugOutputsProvider>(
+          AppleDebugOutputsProvider.class, SKYLARK_NAME) {};
 
   /**
    * Creates a new provider instance.
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleDylibBinaryProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleDylibBinaryProvider.java
index 76e04d684f..7afae2ef62 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleDylibBinaryProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleDylibBinaryProvider.java
@@ -17,7 +17,6 @@ package com.google.devtools.build.lib.rules.objc;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 
@@ -37,9 +36,10 @@ public final class AppleDylibBinaryProvider extends SkylarkClassObject
   /** Skylark name for the AppleDylibBinaryProvider. */
   public static final String SKYLARK_NAME = "AppleDylibBinary";
 
- /** Skylark constructor and identifier for AppleDylibBinaryProvider. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-     new NativeClassObjectConstructor(SKYLARK_NAME) { };
+  /** Skylark constructor and identifier for AppleDylibBinaryProvider. */
+  public static final NativeClassObjectConstructor<AppleDylibBinaryProvider> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<AppleDylibBinaryProvider>(
+          AppleDylibBinaryProvider.class, SKYLARK_NAME) {};
 
   private final Artifact dylibBinary;
   private final ObjcProvider depsObjcProvider;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleDynamicFrameworkProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleDynamicFrameworkProvider.java
index 848058efc4..2ab05d6dac 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleDynamicFrameworkProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleDynamicFrameworkProvider.java
@@ -18,7 +18,6 @@ import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
 import com.google.devtools.build.lib.collect.nestedset.NestedSet;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import com.google.devtools.build.lib.vfs.PathFragment;
@@ -43,9 +42,11 @@ public final class AppleDynamicFrameworkProvider extends SkylarkClassObject
   /** Skylark name for the AppleDynamicFrameworkProvider. */
   public static final String SKYLARK_NAME = "AppleDynamicFramework";
 
- /** Skylark constructor and identifier for AppleDynamicFrameworkProvider. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor(SKYLARK_NAME) {};
+  /** Skylark constructor and identifier for AppleDynamicFrameworkProvider. */
+  public static final NativeClassObjectConstructor<AppleDynamicFrameworkProvider>
+      SKYLARK_CONSTRUCTOR =
+          new NativeClassObjectConstructor<AppleDynamicFrameworkProvider>(
+              AppleDynamicFrameworkProvider.class, SKYLARK_NAME) {};
 
   /** Field name for the dylib binary artifact of the dynamic framework. */
   public static final String DYLIB_BINARY_FIELD_NAME = "binary";
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleExecutableBinaryProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleExecutableBinaryProvider.java
index 24002a4736..347b1111d3 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleExecutableBinaryProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleExecutableBinaryProvider.java
@@ -17,7 +17,6 @@ package com.google.devtools.build.lib.rules.objc;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 
@@ -37,9 +36,11 @@ public final class AppleExecutableBinaryProvider extends SkylarkClassObject
   /** Skylark name for the AppleExecutableBinaryProvider. */
   public static final String SKYLARK_NAME = "AppleExecutableBinary";
 
- /** Skylark constructor and identifier for AppleExecutableBinaryProvider. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-     new NativeClassObjectConstructor(SKYLARK_NAME) { };
+  /** Skylark constructor and identifier for AppleExecutableBinaryProvider. */
+  public static final NativeClassObjectConstructor<AppleExecutableBinaryProvider>
+      SKYLARK_CONSTRUCTOR =
+          new NativeClassObjectConstructor<AppleExecutableBinaryProvider>(
+              AppleExecutableBinaryProvider.class, SKYLARK_NAME) {};
 
   private final Artifact appleExecutableBinary;
   private final ObjcProvider depsObjcProvider;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleLoadableBundleBinaryProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleLoadableBundleBinaryProvider.java
index f271b73617..cd014bcf43 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleLoadableBundleBinaryProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleLoadableBundleBinaryProvider.java
@@ -17,7 +17,6 @@ package com.google.devtools.build.lib.rules.objc;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 
@@ -34,9 +33,11 @@ public final class AppleLoadableBundleBinaryProvider extends SkylarkClassObject
   /** Skylark name for the AppleLoadableBundleBinary. */
   public static final String SKYLARK_NAME = "AppleLoadableBundleBinary";
 
- /** Skylark constructor and identifier for AppleLoadableBundleBinary. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-     new NativeClassObjectConstructor(SKYLARK_NAME) { };
+  /** Skylark constructor and identifier for AppleLoadableBundleBinary. */
+  public static final NativeClassObjectConstructor<AppleLoadableBundleBinaryProvider>
+      SKYLARK_CONSTRUCTOR =
+          new NativeClassObjectConstructor<AppleLoadableBundleBinaryProvider>(
+              AppleLoadableBundleBinaryProvider.class, SKYLARK_NAME) {};
 
   private final Artifact appleLoadableBundleBinary;
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleStaticLibraryProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleStaticLibraryProvider.java
index e4c477fb53..6cb613f973 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleStaticLibraryProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleStaticLibraryProvider.java
@@ -17,7 +17,6 @@ package com.google.devtools.build.lib.rules.objc;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 
@@ -38,9 +37,10 @@ public final class AppleStaticLibraryProvider extends SkylarkClassObject
   /** Skylark name for the AppleStaticLibraryProvider. */
   public static final String SKYLARK_NAME = "AppleStaticLibrary";
 
- /** Skylark constructor and identifier for AppleStaticLibraryProvider. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-     new NativeClassObjectConstructor(SKYLARK_NAME) { };
+  /** Skylark constructor and identifier for AppleStaticLibraryProvider. */
+  public static final NativeClassObjectConstructor<AppleStaticLibraryProvider> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<AppleStaticLibraryProvider>(
+          AppleStaticLibraryProvider.class, SKYLARK_NAME) {};
 
   private final Artifact multiArchArchive;
   private final ObjcProvider depsObjcProvider;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/IosDeviceProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/IosDeviceProvider.java
index 79e62b8064..d22fdca486 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/IosDeviceProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/IosDeviceProvider.java
@@ -19,7 +19,6 @@ import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
 import com.google.devtools.build.lib.analysis.actions.TemplateExpansionAction.Substitution;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import com.google.devtools.build.lib.rules.apple.DottedVersion;
@@ -78,8 +77,8 @@ public final class IosDeviceProvider extends SkylarkClassObject implements Trans
   public static final String SKYLARK_NAME = "IosDevice";
 
   /** Skylark constructor and identifier for the IosDeviceProvider. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor(SKYLARK_NAME) { };
+  public static final NativeClassObjectConstructor<IosDeviceProvider> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<IosDeviceProvider>(IosDeviceProvider.class, SKYLARK_NAME) {};
 
   private final String type;
   private final DottedVersion iosVersion;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProvider.java
index e918abb94a..b040c629ff 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProvider.java
@@ -30,7 +30,6 @@ 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.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import com.google.devtools.build.lib.rules.cpp.CcLinkParamsProvider;
@@ -507,8 +506,8 @@ public final class ObjcProvider extends SkylarkClassObject
   // Items which should be passed to strictly direct dependers, but not transitive dependers.
   private final ImmutableMap<Key<?>, NestedSet<?>> strictDependencyItems;
 
-  private static final ClassObjectConstructor OBJC_PROVIDER =
-      new NativeClassObjectConstructor("objc_provider") {
+  private static final NativeClassObjectConstructor<ObjcProvider> OBJC_PROVIDER =
+      new NativeClassObjectConstructor<ObjcProvider>(ObjcProvider.class, "objc_provider") {
         @Override
         public String getErrorMessageFormatForInstances() {
           return "ObjcProvider field %s could not be instantiated";
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/Watch2ExtensionSupport.java b/src/main/java/com/google/devtools/build/lib/rules/objc/Watch2ExtensionSupport.java
index f50580ce6f..a73ecaeafb 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/Watch2ExtensionSupport.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/Watch2ExtensionSupport.java
@@ -180,8 +180,7 @@ public class Watch2ExtensionSupport {
     Iterable<ObjcProvider> binaryDependencies() {
       TransitiveInfoCollection info = ruleContext.getPrerequisite("binary", Mode.TARGET);
       AppleExecutableBinaryProvider binaryProvider =
-          (AppleExecutableBinaryProvider) info.get(
-              AppleExecutableBinaryProvider.SKYLARK_CONSTRUCTOR.getKey());
+          info.get(AppleExecutableBinaryProvider.SKYLARK_CONSTRUCTOR);
       return ImmutableList.of(binaryProvider.getDepsObjcProvider());
     }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/XcTestAppProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/XcTestAppProvider.java
index e25c88c154..df27f2e0b0 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/XcTestAppProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/XcTestAppProvider.java
@@ -18,7 +18,6 @@ import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
@@ -44,8 +43,9 @@ public final class XcTestAppProvider extends SkylarkClassObject
     return XCTEST_APP_SKYLARK_PROVIDER_NAME;
   }
 
-  private static final ClassObjectConstructor XCTEST_APP_PROVIDER =
-      new NativeClassObjectConstructor("xctest_app_provider") {
+  private static final NativeClassObjectConstructor<XcTestAppProvider> XCTEST_APP_PROVIDER =
+      new NativeClassObjectConstructor<XcTestAppProvider>(
+          XcTestAppProvider.class, "xctest_app_provider") {
         @Override
         public String getErrorMessageFormatForInstances() {
           return "XcTestAppProvider field %s could not be instantiated";
diff --git a/src/main/java/com/google/devtools/build/lib/rules/platform/ConstraintValueRule.java b/src/main/java/com/google/devtools/build/lib/rules/platform/ConstraintValueRule.java
index 0976c01dcd..ca95be913a 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/platform/ConstraintValueRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/platform/ConstraintValueRule.java
@@ -48,7 +48,8 @@ public class ConstraintValueRule implements RuleDefinition {
                 .mandatory()
                 .allowedRuleClasses(ConstraintSettingRule.RULE_NAME)
                 .allowedFileTypes(FileTypeSet.NO_FILE)
-                .mandatoryProviders(ImmutableList.of(ConstraintSettingInfo.SKYLARK_IDENTIFIER)))
+                .mandatoryProviders(
+                    ImmutableList.of(ConstraintSettingInfo.SKYLARK_CONSTRUCTOR.id())))
         .removeAttribute("deps")
         .removeAttribute("data")
         .exemptFromConstraintChecking("this rule *defines* a constraint")
diff --git a/src/main/java/com/google/devtools/build/lib/rules/platform/PlatformRule.java b/src/main/java/com/google/devtools/build/lib/rules/platform/PlatformRule.java
index 10344bb6ea..aef9d42377 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/platform/PlatformRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/platform/PlatformRule.java
@@ -52,7 +52,7 @@ public class PlatformRule implements RuleDefinition {
         .add(
             attr(CONSTRAINT_VALUES_ATTR, BuildType.LABEL_LIST)
                 .allowedFileTypes(FileTypeSet.NO_FILE)
-                .mandatoryProviders(ImmutableList.of(ConstraintValueInfo.SKYLARK_IDENTIFIER)))
+                .mandatoryProviders(ImmutableList.of(ConstraintValueInfo.SKYLARK_CONSTRUCTOR.id())))
 
         /* <!-- #BLAZE_RULE(platform).ATTRIBUTE(remote_execution_properties) -->
         A key/value dict of values that will be sent to a remote execution platform.
@@ -76,14 +76,14 @@ public class PlatformRule implements RuleDefinition {
         .add(
             attr(CPU_CONSTRAINTS_ATTR, BuildType.LABEL_LIST)
                 .allowedFileTypes(FileTypeSet.NO_FILE)
-                .mandatoryProviders(ImmutableList.of(ConstraintValueInfo.SKYLARK_IDENTIFIER))
+                .mandatoryProviders(ImmutableList.of(ConstraintValueInfo.SKYLARK_CONSTRUCTOR.id()))
                 .undocumented("Should only be used by internal packages."))
         // Undocumented. Indicates to the rule which constraint_values to use for automatic CPU
         // mapping.
         .add(
             attr(OS_CONSTRAINTS_ATTR, BuildType.LABEL_LIST)
                 .allowedFileTypes(FileTypeSet.NO_FILE)
-                .mandatoryProviders(ImmutableList.of(ConstraintValueInfo.SKYLARK_IDENTIFIER))
+                .mandatoryProviders(ImmutableList.of(ConstraintValueInfo.SKYLARK_CONSTRUCTOR.id()))
                 .undocumented("Should only be used by internal packages."))
         .removeAttribute("deps")
         .removeAttribute("data")
diff --git a/src/main/java/com/google/devtools/build/lib/rules/platform/ToolchainRule.java b/src/main/java/com/google/devtools/build/lib/rules/platform/ToolchainRule.java
index 8065d35909..3c393e2269 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/platform/ToolchainRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/platform/ToolchainRule.java
@@ -59,7 +59,7 @@ public class ToolchainRule implements RuleDefinition {
         <!-- #END_BLAZE_RULE.ATTRIBUTE --> */
         .add(
             attr(EXEC_COMPATIBLE_WITH_ATTR, BuildType.LABEL_LIST)
-                .mandatoryProviders(ImmutableList.of(ConstraintValueInfo.SKYLARK_IDENTIFIER))
+                .mandatoryProviders(ConstraintValueInfo.SKYLARK_CONSTRUCTOR.id())
                 .allowedFileTypes()
                 .nonconfigurable("part of toolchain configuration"))
         /* <!-- #BLAZE_RULE(toolchain).ATTRIBUTE(target_compatible_with) -->
@@ -68,7 +68,7 @@ public class ToolchainRule implements RuleDefinition {
         <!-- #END_BLAZE_RULE.ATTRIBUTE --> */
         .add(
             attr(TARGET_COMPATIBLE_WITH_ATTR, BuildType.LABEL_LIST)
-                .mandatoryProviders(ImmutableList.of(ConstraintValueInfo.SKYLARK_IDENTIFIER))
+                .mandatoryProviders(ConstraintValueInfo.SKYLARK_CONSTRUCTOR.id())
                 .allowedFileTypes()
                 .nonconfigurable("part of toolchain configuration"))
         /* <!-- #BLAZE_RULE(toolchain).ATTRIBUTE(toolchain) -->
diff --git a/src/main/java/com/google/devtools/build/lib/rules/test/ExecutionInfoProvider.java b/src/main/java/com/google/devtools/build/lib/rules/test/ExecutionInfoProvider.java
index 5567f2719a..4f17ec199c 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/test/ExecutionInfoProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/test/ExecutionInfoProvider.java
@@ -16,7 +16,6 @@ package com.google.devtools.build.lib.rules.test;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import java.util.Map;
@@ -30,9 +29,9 @@ public final class ExecutionInfoProvider extends SkylarkClassObject
     implements TransitiveInfoProvider {
 
   /** Skylark constructor and identifier for ExecutionInfoProvider. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor("ExecutionInfo") {
-      };
+  public static final NativeClassObjectConstructor<ExecutionInfoProvider> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<ExecutionInfoProvider>(
+          ExecutionInfoProvider.class, "ExecutionInfo") {};
 
   private final ImmutableMap<String, String> executionInfo;
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/test/TestEnvironmentProvider.java b/src/main/java/com/google/devtools/build/lib/rules/test/TestEnvironmentProvider.java
index e2b5fc8510..240738dde5 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/test/TestEnvironmentProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/test/TestEnvironmentProvider.java
@@ -18,7 +18,6 @@ import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.analysis.TransitiveInfoProvider;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
-import com.google.devtools.build.lib.packages.ClassObjectConstructor;
 import com.google.devtools.build.lib.packages.NativeClassObjectConstructor;
 import com.google.devtools.build.lib.packages.SkylarkClassObject;
 import java.util.Map;
@@ -29,8 +28,9 @@ public final class TestEnvironmentProvider extends SkylarkClassObject
     implements TransitiveInfoProvider {
 
   /** Skylark constructor and identifier for TestEnvironmentProvider. */
-  public static final ClassObjectConstructor SKYLARK_CONSTRUCTOR =
-      new NativeClassObjectConstructor("TestEnvironment") { };
+  public static final NativeClassObjectConstructor<TestEnvironmentProvider> SKYLARK_CONSTRUCTOR =
+      new NativeClassObjectConstructor<TestEnvironmentProvider>(
+          TestEnvironmentProvider.class, "TestEnvironment") {};
 
   private final Map<String, String> environment;
 
diff --git a/src/test/java/com/google/devtools/build/lib/packages/RequiredProvidersTest.java b/src/test/java/com/google/devtools/build/lib/packages/RequiredProvidersTest.java
index abc3ec917d..03cc956b71 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/RequiredProvidersTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/RequiredProvidersTest.java
@@ -36,7 +36,7 @@ public class RequiredProvidersTest {
   private static final class P3 {}
 
   private static final ClassObjectConstructor P_NATIVE =
-      new NativeClassObjectConstructor("p_native") {};
+      new NativeClassObjectConstructor<SkylarkClassObject>(SkylarkClassObject.class, "p_native") {};
 
   private static final SkylarkClassObjectConstructor P_SKYLARK =
       new SkylarkClassObjectConstructor("p_skylark", Location.BUILTIN);
diff --git a/src/test/java/com/google/devtools/build/lib/rules/android/AndroidDeviceScriptFixtureTest.java b/src/test/java/com/google/devtools/build/lib/rules/android/AndroidDeviceScriptFixtureTest.java
index 6149580254..3f51d80979 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/android/AndroidDeviceScriptFixtureTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/android/AndroidDeviceScriptFixtureTest.java
@@ -60,9 +60,7 @@ public class AndroidDeviceScriptFixtureTest extends AndroidBuildViewTestCase {
     ConfiguredTarget fixture = getConfiguredTarget("//javatests/com/app:fixture");
     assertThat(fixture).isNotNull();
     AndroidDeviceScriptFixtureInfoProvider deviceScriptFixtureInfoProvider =
-        (AndroidDeviceScriptFixtureInfoProvider)
-            fixture.get(
-                AndroidDeviceScriptFixtureInfoProvider.ANDROID_DEVICE_SCRIPT_FIXTURE_INFO.getKey());
+        fixture.get(AndroidDeviceScriptFixtureInfoProvider.ANDROID_DEVICE_SCRIPT_FIXTURE_INFO);
     assertThat(deviceScriptFixtureInfoProvider).isNotNull();
     assertThat(deviceScriptFixtureInfoProvider.getFixtureScript()).isNotNull();
     assertThat(deviceScriptFixtureInfoProvider.getFixtureScript().prettyPrint())
@@ -80,9 +78,7 @@ public class AndroidDeviceScriptFixtureTest extends AndroidBuildViewTestCase {
     ConfiguredTarget fixture = getConfiguredTarget("//javatests/com/app:fixture");
     assertThat(fixture).isNotNull();
     AndroidDeviceScriptFixtureInfoProvider deviceScriptFixtureInfoProvider =
-        (AndroidDeviceScriptFixtureInfoProvider)
-            fixture.get(
-                AndroidDeviceScriptFixtureInfoProvider.ANDROID_DEVICE_SCRIPT_FIXTURE_INFO.getKey());
+        fixture.get(AndroidDeviceScriptFixtureInfoProvider.ANDROID_DEVICE_SCRIPT_FIXTURE_INFO);
     assertThat(deviceScriptFixtureInfoProvider).isNotNull();
     assertThat(deviceScriptFixtureInfoProvider.getFixtureScript()).isNotNull();
     assertThat(deviceScriptFixtureInfoProvider.getFixtureScript().prettyPrint())
@@ -133,9 +129,7 @@ public class AndroidDeviceScriptFixtureTest extends AndroidBuildViewTestCase {
     ConfiguredTarget fixture = getConfiguredTarget("//javatests/com/app:fixture");
     assertThat(fixture).isNotNull();
     AndroidDeviceScriptFixtureInfoProvider deviceScriptFixtureInfoProvider =
-        (AndroidDeviceScriptFixtureInfoProvider)
-            fixture.get(
-                AndroidDeviceScriptFixtureInfoProvider.ANDROID_DEVICE_SCRIPT_FIXTURE_INFO.getKey());
+        fixture.get(AndroidDeviceScriptFixtureInfoProvider.ANDROID_DEVICE_SCRIPT_FIXTURE_INFO);
     assertThat(deviceScriptFixtureInfoProvider).isNotNull();
 
     assertThat(
@@ -169,9 +163,7 @@ public class AndroidDeviceScriptFixtureTest extends AndroidBuildViewTestCase {
     ConfiguredTarget fixture = getConfiguredTarget("//javatests/com/app:fixture");
     assertThat(fixture).isNotNull();
     AndroidDeviceScriptFixtureInfoProvider deviceScriptFixtureInfoProvider =
-        (AndroidDeviceScriptFixtureInfoProvider)
-            fixture.get(
-                AndroidDeviceScriptFixtureInfoProvider.ANDROID_DEVICE_SCRIPT_FIXTURE_INFO.getKey());
+        fixture.get(AndroidDeviceScriptFixtureInfoProvider.ANDROID_DEVICE_SCRIPT_FIXTURE_INFO);
     assertThat(deviceScriptFixtureInfoProvider).isNotNull();
     assertThat(deviceScriptFixtureInfoProvider.getDaemon()).isTrue();
   }
@@ -188,9 +180,7 @@ public class AndroidDeviceScriptFixtureTest extends AndroidBuildViewTestCase {
     ConfiguredTarget fixture = getConfiguredTarget("//javatests/com/app:fixture");
     assertThat(fixture).isNotNull();
     AndroidDeviceScriptFixtureInfoProvider deviceScriptFixtureInfoProvider =
-        (AndroidDeviceScriptFixtureInfoProvider)
-            fixture.get(
-                AndroidDeviceScriptFixtureInfoProvider.ANDROID_DEVICE_SCRIPT_FIXTURE_INFO.getKey());
+        fixture.get(AndroidDeviceScriptFixtureInfoProvider.ANDROID_DEVICE_SCRIPT_FIXTURE_INFO);
     assertThat(deviceScriptFixtureInfoProvider).isNotNull();
     assertThat(deviceScriptFixtureInfoProvider.getStrictExit()).isTrue();
   }
diff --git a/src/test/java/com/google/devtools/build/lib/rules/android/AndroidDeviceTest.java b/src/test/java/com/google/devtools/build/lib/rules/android/AndroidDeviceTest.java
index a594abe3ee..ffd847c52e 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/android/AndroidDeviceTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/android/AndroidDeviceTest.java
@@ -169,7 +169,7 @@ public class AndroidDeviceTest extends BuildViewTestCase {
 
     assertThat(target.get(ExecutionInfoProvider.SKYLARK_CONSTRUCTOR.getKey())).isNotNull();
     ExecutionInfoProvider executionInfoProvider =
-        (ExecutionInfoProvider) target.get(ExecutionInfoProvider.SKYLARK_CONSTRUCTOR.getKey());
+        target.get(ExecutionInfoProvider.SKYLARK_CONSTRUCTOR);
     assertThat(executionInfoProvider.getExecutionInfo()).doesNotContainKey(REQUIRES_KVM);
     TemplateExpansionAction stubAction = (TemplateExpansionAction) getGeneratingAction(
         getExecutable(target));
@@ -228,9 +228,7 @@ public class AndroidDeviceTest extends BuildViewTestCase {
     assertThat(action.getExecutionInfo())
         .containsEntry(REQUIRES_KVM, "");
     assertThat(target.get(ExecutionInfoProvider.SKYLARK_CONSTRUCTOR.getKey())).isNotNull();
-    assertThat(
-            ((ExecutionInfoProvider) target.get(ExecutionInfoProvider.SKYLARK_CONSTRUCTOR.getKey()))
-                .getExecutionInfo())
+    assertThat(target.get(ExecutionInfoProvider.SKYLARK_CONSTRUCTOR).getExecutionInfo())
         .containsKey(REQUIRES_KVM);
   }
 
@@ -276,12 +274,7 @@ public class AndroidDeviceTest extends BuildViewTestCase {
     Iterable<String> biosFilesExecPathStrings =
         Iterables.transform(
             getToolDependency("//tools/android/emulator:emulator_x86_bios").getFilesToRun(),
-            new Function<Artifact, String>() {
-              @Override
-              public String apply(Artifact artifact) {
-                return artifact.getExecPathString();
-              }
-            });
+            Artifact::getExecPathString);
 
     assertWithMessage("Invalid boot commandline.")
         .that(action.getArguments())
diff --git a/src/test/java/com/google/devtools/build/lib/rules/android/AndroidHostServiceFixtureTest.java b/src/test/java/com/google/devtools/build/lib/rules/android/AndroidHostServiceFixtureTest.java
index e0954c0c51..55718d40ee 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/android/AndroidHostServiceFixtureTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/android/AndroidHostServiceFixtureTest.java
@@ -162,7 +162,6 @@ public class AndroidHostServiceFixtureTest extends AndroidBuildViewTestCase {
 
   private AndroidHostServiceFixtureInfoProvider getHostServiceFixtureInfoProvider(
       ConfiguredTarget ct) throws Exception {
-    return (AndroidHostServiceFixtureInfoProvider)
-        ct.get(AndroidHostServiceFixtureInfoProvider.ANDROID_HOST_SERVICE_FIXTURE_INFO.getKey());
+    return ct.get(AndroidHostServiceFixtureInfoProvider.ANDROID_HOST_SERVICE_FIXTURE_INFO);
   }
 }
diff --git a/src/test/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationRuleImplTest.java b/src/test/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationRuleImplTest.java
index e71be0a2bc..860082c483 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationRuleImplTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationRuleImplTest.java
@@ -72,9 +72,7 @@ public class AndroidInstrumentationRuleImplTest extends AndroidBuildViewTestCase
     ConfiguredTarget instrumentation = getConfiguredTarget("//javatests/com/app/instrumentation");
     assertThat(instrumentation).isNotNull();
     AndroidInstrumentationInfoProvider instrumentationProvider =
-        (AndroidInstrumentationInfoProvider)
-            instrumentation.get(
-                AndroidInstrumentationInfoProvider.ANDROID_INSTRUMENTATION_INFO.getKey());
+        instrumentation.get(AndroidInstrumentationInfoProvider.ANDROID_INSTRUMENTATION_INFO);
     assertThat(instrumentationProvider.getTargetApk()).isNotNull();
     assertThat(instrumentationProvider.getTargetApk().prettyPrint())
         .isEqualTo("javatests/com/app/instrumentation/instrumentation-target.apk");
@@ -98,9 +96,7 @@ public class AndroidInstrumentationRuleImplTest extends AndroidBuildViewTestCase
     ConfiguredTarget instrumentation = getConfiguredTarget("//javatests/com/app/instrumentation");
     assertThat(instrumentation).isNotNull();
     AndroidInstrumentationInfoProvider instrumentationProvider =
-        (AndroidInstrumentationInfoProvider)
-            instrumentation.get(
-                AndroidInstrumentationInfoProvider.ANDROID_INSTRUMENTATION_INFO.getKey());
+        instrumentation.get(AndroidInstrumentationInfoProvider.ANDROID_INSTRUMENTATION_INFO);
 
     Artifact targetApk = instrumentationProvider.getTargetApk();
     assertThat(targetApk).isNotNull();
diff --git a/src/test/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationTestTest.java b/src/test/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationTestTest.java
index 66f08f83c2..a80a221b87 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationTestTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/android/AndroidInstrumentationTestTest.java
@@ -239,16 +239,14 @@ public class AndroidInstrumentationTestTest extends AndroidBuildViewTestCase {
   }
 
   private static Artifact getInstrumentationApk(ConfiguredTarget instrumentation) {
-    return ((AndroidInstrumentationInfoProvider)
-            instrumentation.get(
-                AndroidInstrumentationInfoProvider.ANDROID_INSTRUMENTATION_INFO.getKey()))
+    return instrumentation
+        .get(AndroidInstrumentationInfoProvider.ANDROID_INSTRUMENTATION_INFO)
         .getInstrumentationApk();
   }
 
   private static Artifact getTargetApk(ConfiguredTarget instrumentation) {
-    return ((AndroidInstrumentationInfoProvider)
-            instrumentation.get(
-                AndroidInstrumentationInfoProvider.ANDROID_INSTRUMENTATION_INFO.getKey()))
+    return instrumentation
+        .get(AndroidInstrumentationInfoProvider.ANDROID_INSTRUMENTATION_INFO)
         .getTargetApk();
   }
 }
diff --git a/src/test/java/com/google/devtools/build/lib/rules/java/proto/SkylarkJavaLiteProtoLibraryTest.java b/src/test/java/com/google/devtools/build/lib/rules/java/proto/SkylarkJavaLiteProtoLibraryTest.java
index c42ef25391..be78678e13 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/java/proto/SkylarkJavaLiteProtoLibraryTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/java/proto/SkylarkJavaLiteProtoLibraryTest.java
@@ -586,8 +586,7 @@ public class SkylarkJavaLiteProtoLibraryTest extends BuildViewTestCase {
 
   private static <P extends TransitiveInfoProvider> P getProvider(
       Class<P> providerClass, ConfiguredTarget target) {
-    JavaProvider javaProvider =
-        (JavaProvider) target.get(JavaProvider.JAVA_PROVIDER.getKey());
+    JavaProvider javaProvider = target.get(JavaProvider.JAVA_PROVIDER);
     return javaProvider.getProvider(providerClass);
   }
 }
diff --git a/src/test/java/com/google/devtools/build/lib/rules/objc/AppleBinaryTest.java b/src/test/java/com/google/devtools/build/lib/rules/objc/AppleBinaryTest.java
index db30b9a0ac..d387743cc5 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/objc/AppleBinaryTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/objc/AppleBinaryTest.java
@@ -1360,8 +1360,7 @@ public class AppleBinaryTest extends ObjcRuleTestCase {
         ")");
     ConfiguredTarget binTarget = getConfiguredTarget("//bin:bin");
     AppleExecutableBinaryProvider executableBinaryProvider =
-        (AppleExecutableBinaryProvider) binTarget.get(
-            AppleExecutableBinaryProvider.SKYLARK_CONSTRUCTOR.getKey());
+        binTarget.get(AppleExecutableBinaryProvider.SKYLARK_CONSTRUCTOR);
     assertThat(executableBinaryProvider).isNotNull();
 
     CommandAction testLinkAction = linkAction("//test:test");
diff --git a/src/test/java/com/google/devtools/build/lib/rules/objc/AppleStaticLibraryTest.java b/src/test/java/com/google/devtools/build/lib/rules/objc/AppleStaticLibraryTest.java
index c410ce51cd..01f8b08d99 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/objc/AppleStaticLibraryTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/objc/AppleStaticLibraryTest.java
@@ -532,8 +532,7 @@ public class AppleStaticLibraryTest extends ObjcRuleTestCase {
         ")");
     ConfiguredTarget binTarget = getConfiguredTarget("//lib:applelib");
     AppleStaticLibraryProvider provider =
-        (AppleStaticLibraryProvider) binTarget.get(
-            AppleStaticLibraryProvider.SKYLARK_CONSTRUCTOR.getKey());
+        binTarget.get(AppleStaticLibraryProvider.SKYLARK_CONSTRUCTOR);
     assertThat(provider).isNotNull();
     assertThat(provider.getMultiArchArchive()).isNotNull();
     assertThat(provider.getDepsObjcProvider()).isNotNull();
diff --git a/src/test/java/com/google/devtools/build/lib/rules/objc/IosDeviceTest.java b/src/test/java/com/google/devtools/build/lib/rules/objc/IosDeviceTest.java
index 49b7540b69..273f51b497 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/objc/IosDeviceTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/objc/IosDeviceTest.java
@@ -104,8 +104,7 @@ public class IosDeviceTest extends BuildViewTestCase {
     assertThat(view.hasErrors(getConfiguredTarget("//test:foo"))).isFalse();
 
     ConfiguredTarget target = getConfiguredTarget("//test:foo");
-    IosDeviceProvider provider =
-        (IosDeviceProvider) target.get(IosDeviceProvider.SKYLARK_CONSTRUCTOR.getKey());
+    IosDeviceProvider provider = target.get(IosDeviceProvider.SKYLARK_CONSTRUCTOR);
     assertThat(provider.getType()).isEqualTo("IPHONE_6");
   }
 
@@ -156,8 +155,7 @@ public class IosDeviceTest extends BuildViewTestCase {
     assertThat(view.hasErrors(getConfiguredTarget(label))).isFalse();
 
     ConfiguredTarget target = getConfiguredTarget(label);
-    IosDeviceProvider provider =
-        (IosDeviceProvider) target.get(IosDeviceProvider.SKYLARK_CONSTRUCTOR.getKey());
+    IosDeviceProvider provider = target.get(IosDeviceProvider.SKYLARK_CONSTRUCTOR);
     assertThat(provider.getXcodeVersion()).isEqualTo(DottedVersion.fromString(version));
   }
 
@@ -165,8 +163,7 @@ public class IosDeviceTest extends BuildViewTestCase {
     assertThat(view.hasErrors(getConfiguredTarget(label))).isFalse();
 
     ConfiguredTarget target = getConfiguredTarget(label);
-    IosDeviceProvider provider =
-        (IosDeviceProvider) target.get(IosDeviceProvider.SKYLARK_CONSTRUCTOR.getKey());
+    IosDeviceProvider provider = target.get(IosDeviceProvider.SKYLARK_CONSTRUCTOR);
     assertThat(provider.getIosVersion()).isEqualTo(DottedVersion.fromString(version));
   }
 }
diff --git a/src/test/java/com/google/devtools/build/lib/rules/test/SkylarkTestingModuleTest.java b/src/test/java/com/google/devtools/build/lib/rules/test/SkylarkTestingModuleTest.java
index 7aecef07b4..0d6318f606 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/test/SkylarkTestingModuleTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/test/SkylarkTestingModuleTest.java
@@ -45,9 +45,7 @@ public class SkylarkTestingModuleTest extends BuildViewTestCase {
         ")");
 
     ConfiguredTarget skylarkTarget = getConfiguredTarget("//examples/apple_skylark:my_target");
-    ExecutionInfoProvider provider =
-        (ExecutionInfoProvider)
-            skylarkTarget.get(ExecutionInfoProvider.SKYLARK_CONSTRUCTOR.getKey());
+    ExecutionInfoProvider provider = skylarkTarget.get(ExecutionInfoProvider.SKYLARK_CONSTRUCTOR);
 
     assertThat(provider.getExecutionInfo().get("requires-darwin")).isEqualTo("1");
   }
@@ -73,8 +71,7 @@ public class SkylarkTestingModuleTest extends BuildViewTestCase {
 
     ConfiguredTarget skylarkTarget = getConfiguredTarget("//examples/apple_skylark:my_target");
     TestEnvironmentProvider provider =
-        (TestEnvironmentProvider)
-            skylarkTarget.get(TestEnvironmentProvider.SKYLARK_CONSTRUCTOR.getKey());
+        skylarkTarget.get(TestEnvironmentProvider.SKYLARK_CONSTRUCTOR);
 
     assertThat(provider.getEnvironment().get("XCODE_VERSION_OVERRIDE")).isEqualTo("7.3.1");
   }
diff --git a/src/test/java/com/google/devtools/build/lib/syntax/SkylarkEvaluationTest.java b/src/test/java/com/google/devtools/build/lib/syntax/SkylarkEvaluationTest.java
index 24c16e59c8..1cd8a98c62 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/SkylarkEvaluationTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/SkylarkEvaluationTest.java
@@ -1404,8 +1404,10 @@ public class SkylarkEvaluationTest extends EvaluationTest {
 
   @SkylarkModule(name = "SkylarkClassObjectWithSkylarkCallables", doc = "")
   static final class SkylarkClassObjectWithSkylarkCallables extends SkylarkClassObject {
-    private static final NativeClassObjectConstructor CONSTRUCTOR =
-        new NativeClassObjectConstructor("struct_with_skylark_callables") {};
+    private static final NativeClassObjectConstructor<SkylarkClassObjectWithSkylarkCallables>
+        CONSTRUCTOR =
+            new NativeClassObjectConstructor<SkylarkClassObjectWithSkylarkCallables>(
+                SkylarkClassObjectWithSkylarkCallables.class, "struct_with_skylark_callables") {};
 
     SkylarkClassObjectWithSkylarkCallables() {
       super(
author	dslomov <dslomov@google.com>	2017-07-10 17:15:27 +0200
committer	László Csomor <laszlocsomor@google.com>	2017-07-10 17:45:04 +0200
commit	77baa4c372ae014db8e17f6d3c60bd88597853d9 (patch)
tree	3ca2c63943782b506b0f19f5b7f7465909723590
parent	45bd34e747d13fc2bebdc849a11b4b952da5d8a6 (diff)