move to unified feature flag system for new state reconciliation algorithm (#44022)

Summary: Pull Request resolved: https://github.com/facebook/react-native/pull/44022 changelog: [internal] move the new state reconciliation algorithm to the unified feature flag system. Reviewed By: rubennorte Differential Revision: D55965530 fbshipit-source-id: 3edde0858a670e86dc2d1cb561f03f584ff21896
2025-11-01 09:14:26 +00:00 · 2024-04-12 02:47:01 -07:00
parent 4d9b11b45d
commit 2ef59c988d
27 changed files with 148 additions and 36 deletions
@@ -264,10 +264,6 @@ static BackgroundExecutor RCTGetBackgroundExecutor()
    CoreFeatures::enableGranularScrollViewStateUpdatesIOS = true;
  }

-  if (reactNativeConfig && reactNativeConfig->getBool("react_fabric:enable_cloneless_state_progression")) {
-    CoreFeatures::enableClonelessStateProgression = true;
-  }
-
  auto componentRegistryFactory =
      [factory = wrapManagedObject(_mountingManager.componentViewRegistry.componentViewFactory)](
          const EventDispatcher::Weak &eventDispatcher, const ContextContainer::Shared &contextContainer) {
@@ -1962,7 +1962,6 @@ public class com/facebook/react/config/ReactFeatureFlags {
 	public static field dispatchPointerEvents Z
 	public static field enableBridgelessArchitecture Z
 	public static field enableBridgelessArchitectureNewCreateReloadDestroy Z
-	public static field enableClonelessStateProgression Z
 	public static field enableCppPropsIteratorSetter Z
 	public static field enableEagerRootViewAttachment Z
 	public static field enableFabricLogs Z
@@ -101,9 +101,6 @@ public class ReactFeatureFlags {
   */
  public static boolean enableRemoveDeleteTreeInstruction = false;

-  /** When enabled, Fabric will avoid cloning notes to perform state progression. */
-  public static boolean enableClonelessStateProgression = false;
-
  /** When enabled, rawProps in Props will not include Yoga specific props. */
  public static boolean excludeYogaFromRawProps = false;

@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<a9793334f77cea07b88a74103da09f72>>
+ * @generated SignedSource<<7c2d825e15fc7e442034a598eebb6e25>>
 */

 /**
@@ -118,6 +118,12 @@ public object ReactNativeFeatureFlags {
  @JvmStatic
  public fun useNativeViewConfigsInBridgelessMode(): Boolean = accessor.useNativeViewConfigsInBridgelessMode()

+  /**
+   * When enabled, it uses optimised state reconciliation algorithm.
+   */
+  @JvmStatic
+  public fun useStateAlignmentMechanism(): Boolean = accessor.useStateAlignmentMechanism()
+
  /**
   * Overrides the feature flags with the ones provided by the given provider
   * (generally one that extends `ReactNativeFeatureFlagsDefaults`).
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<51d66e841a09638375b1849043c9886a>>
+ * @generated SignedSource<<eb3ae68166b3ec7f797a0db4b2ec1f5b>>
 */

 /**
@@ -35,6 +35,7 @@ public class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAccesso
  private var inspectorEnableModernCDPRegistryCache: Boolean? = null
  private var useModernRuntimeSchedulerCache: Boolean? = null
  private var useNativeViewConfigsInBridgelessModeCache: Boolean? = null
+  private var useStateAlignmentMechanismCache: Boolean? = null

  override fun commonTestFlag(): Boolean {
    var cached = commonTestFlagCache
@@ -171,6 +172,15 @@ public class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAccesso
    return cached
  }

+  override fun useStateAlignmentMechanism(): Boolean {
+    var cached = useStateAlignmentMechanismCache
+    if (cached == null) {
+      cached = ReactNativeFeatureFlagsCxxInterop.useStateAlignmentMechanism()
+      useStateAlignmentMechanismCache = cached
+    }
+    return cached
+  }
+
  override fun override(provider: ReactNativeFeatureFlagsProvider): Unit =
      ReactNativeFeatureFlagsCxxInterop.override(provider as Any)

@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<4422f7984f27638cc2fb18230a6d042e>>
+ * @generated SignedSource<<0b1377acc1a7a2bed8bd6448a54ec91a>>
 */

 /**
@@ -58,6 +58,8 @@ public object ReactNativeFeatureFlagsCxxInterop {

  @DoNotStrip @JvmStatic public external fun useNativeViewConfigsInBridgelessMode(): Boolean

+  @DoNotStrip @JvmStatic public external fun useStateAlignmentMechanism(): Boolean
+
  @DoNotStrip @JvmStatic public external fun override(provider: Any)

  @DoNotStrip @JvmStatic public external fun dangerouslyReset()
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<acf4e79f18c3b33bcca452a99265dfcf>>
+ * @generated SignedSource<<545ef5d7c16c2d6599f15a747c53cf3f>>
 */

 /**
@@ -52,4 +52,6 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
  override fun useModernRuntimeScheduler(): Boolean = false

  override fun useNativeViewConfigsInBridgelessMode(): Boolean = false
+
+  override fun useStateAlignmentMechanism(): Boolean = false
 }
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<46793ec55ed15661090a9b9998806bcc>>
+ * @generated SignedSource<<aa359470a22488b45abfa18b0edadb18>>
 */

 /**
@@ -39,6 +39,7 @@ public class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcces
  private var inspectorEnableModernCDPRegistryCache: Boolean? = null
  private var useModernRuntimeSchedulerCache: Boolean? = null
  private var useNativeViewConfigsInBridgelessModeCache: Boolean? = null
+  private var useStateAlignmentMechanismCache: Boolean? = null

  override fun commonTestFlag(): Boolean {
    var cached = commonTestFlagCache
@@ -190,6 +191,16 @@ public class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcces
    return cached
  }

+  override fun useStateAlignmentMechanism(): Boolean {
+    var cached = useStateAlignmentMechanismCache
+    if (cached == null) {
+      cached = currentProvider.useStateAlignmentMechanism()
+      accessedFeatureFlags.add("useStateAlignmentMechanism")
+      useStateAlignmentMechanismCache = cached
+    }
+    return cached
+  }
+
  override fun override(provider: ReactNativeFeatureFlagsProvider) {
    if (accessedFeatureFlags.isNotEmpty()) {
      val accessedFeatureFlagsStr = accessedFeatureFlags.joinToString(separator = ", ") { it }
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<dd6d7b39eb1dc066dd6801b22846e431>>
+ * @generated SignedSource<<e2eef1313051abddc31e4a3340e72c1c>>
 */

 /**
@@ -52,4 +52,6 @@ public interface ReactNativeFeatureFlagsProvider {
  @DoNotStrip public fun useModernRuntimeScheduler(): Boolean

  @DoNotStrip public fun useNativeViewConfigsInBridgelessMode(): Boolean
+
+  @DoNotStrip public fun useStateAlignmentMechanism(): Boolean
 }
@@ -406,8 +406,6 @@ void Binding::installFabricUIManager(

  CoreFeatures::enablePropIteratorSetter =
      getFeatureFlagValue("enableCppPropsIteratorSetter");
-  CoreFeatures::enableClonelessStateProgression =
-      getFeatureFlagValue("enableClonelessStateProgression");
  CoreFeatures::excludeYogaFromRawProps =
      getFeatureFlagValue("excludeYogaFromRawProps");

@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<3a7d633de9e6fd6862864c202d56523a>>
+ * @generated SignedSource<<82163a04d1e3cb54d6c5125173ab807f>>
 */

 /**
@@ -129,6 +129,12 @@ class ReactNativeFeatureFlagsProviderHolder
    return method(javaProvider_);
  }

+  bool useStateAlignmentMechanism() override {
+    static const auto method =
+        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("useStateAlignmentMechanism");
+    return method(javaProvider_);
+  }
+
 private:
  jni::global_ref<jobject> javaProvider_;
 };
@@ -208,6 +214,11 @@ bool JReactNativeFeatureFlagsCxxInterop::useNativeViewConfigsInBridgelessMode(
  return ReactNativeFeatureFlags::useNativeViewConfigsInBridgelessMode();
 }

+bool JReactNativeFeatureFlagsCxxInterop::useStateAlignmentMechanism(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
+  return ReactNativeFeatureFlags::useStateAlignmentMechanism();
+}
+
 void JReactNativeFeatureFlagsCxxInterop::override(
    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/,
    jni::alias_ref<jobject> provider) {
@@ -270,6 +281,9 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
      makeNativeMethod(
        "useNativeViewConfigsInBridgelessMode",
        JReactNativeFeatureFlagsCxxInterop::useNativeViewConfigsInBridgelessMode),
+      makeNativeMethod(
+        "useStateAlignmentMechanism",
+        JReactNativeFeatureFlagsCxxInterop::useStateAlignmentMechanism),
  });
 }

@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<7237412cb02dad9468f144a050bd78e3>>
+ * @generated SignedSource<<48e337d37416ab988ea747050bf207f3>>
 */

 /**
@@ -75,6 +75,9 @@ class JReactNativeFeatureFlagsCxxInterop
  static bool useNativeViewConfigsInBridgelessMode(
    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);

+  static bool useStateAlignmentMechanism(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
+
  static void override(
      facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>,
      jni::alias_ref<jobject> provider);
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<e589683db0f9a9fbf812fefd4a1c3f96>>
+ * @generated SignedSource<<ddb65722ccc0d584d105b07a621e6871>>
 */

 /**
@@ -81,6 +81,10 @@ bool ReactNativeFeatureFlags::useNativeViewConfigsInBridgelessMode() {
  return getAccessor().useNativeViewConfigsInBridgelessMode();
 }

+bool ReactNativeFeatureFlags::useStateAlignmentMechanism() {
+  return getAccessor().useStateAlignmentMechanism();
+}
+
 void ReactNativeFeatureFlags::override(
    std::unique_ptr<ReactNativeFeatureFlagsProvider> provider) {
  getAccessor().override(std::move(provider));
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<38881afec04f45eff46edd99ce9443da>>
+ * @generated SignedSource<<8804fc52ad516ba82c0db6fcdea5f110>>
 */

 /**
@@ -112,6 +112,11 @@ class ReactNativeFeatureFlags {
   */
  RN_EXPORT static bool useNativeViewConfigsInBridgelessMode();

+  /**
+   * When enabled, it uses optimised state reconciliation algorithm.
+   */
+  RN_EXPORT static bool useStateAlignmentMechanism();
+
  /**
   * Overrides the feature flags with the ones provided by the given provider
   * (generally one that extends `ReactNativeFeatureFlagsDefaults`).
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<21980ab4688bc93c5573012a228e3997>>
+ * @generated SignedSource<<9f5c5313e139b450449e2716735c26e7>>
 */

 /**
@@ -299,6 +299,24 @@ bool ReactNativeFeatureFlagsAccessor::useNativeViewConfigsInBridgelessMode() {
  return flagValue.value();
 }

+bool ReactNativeFeatureFlagsAccessor::useStateAlignmentMechanism() {
+  auto flagValue = useStateAlignmentMechanism_.load();
+
+  if (!flagValue.has_value()) {
+    // This block is not exclusive but it is not necessary.
+    // If multiple threads try to initialize the feature flag, we would only
+    // be accessing the provider multiple times but the end state of this
+    // instance and the returned flag value would be the same.
+
+    markFlagAsAccessed(15, "useStateAlignmentMechanism");
+
+    flagValue = currentProvider_->useStateAlignmentMechanism();
+    useStateAlignmentMechanism_ = flagValue;
+  }
+
+  return flagValue.value();
+}
+
 void ReactNativeFeatureFlagsAccessor::override(
    std::unique_ptr<ReactNativeFeatureFlagsProvider> provider) {
  if (wasOverridden_) {
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<fe45466cd2b60fe856aa811ccc2365bd>>
+ * @generated SignedSource<<de8d2a8416c3ad914df01b765c8df907>>
 */

 /**
@@ -46,6 +46,7 @@ class ReactNativeFeatureFlagsAccessor {
  bool inspectorEnableModernCDPRegistry();
  bool useModernRuntimeScheduler();
  bool useNativeViewConfigsInBridgelessMode();
+  bool useStateAlignmentMechanism();

  void override(std::unique_ptr<ReactNativeFeatureFlagsProvider> provider);

@@ -56,7 +57,7 @@ class ReactNativeFeatureFlagsAccessor {
  std::unique_ptr<ReactNativeFeatureFlagsProvider> currentProvider_;
  bool wasOverridden_;

-  std::array<std::atomic<const char*>, 15> accessedFeatureFlags_;
+  std::array<std::atomic<const char*>, 16> accessedFeatureFlags_;

  std::atomic<std::optional<bool>> commonTestFlag_;
  std::atomic<std::optional<bool>> batchRenderingUpdatesInEventLoop_;
@@ -73,6 +74,7 @@ class ReactNativeFeatureFlagsAccessor {
  std::atomic<std::optional<bool>> inspectorEnableModernCDPRegistry_;
  std::atomic<std::optional<bool>> useModernRuntimeScheduler_;
  std::atomic<std::optional<bool>> useNativeViewConfigsInBridgelessMode_;
+  std::atomic<std::optional<bool>> useStateAlignmentMechanism_;
 };

 } // namespace facebook::react
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<72058f22fd21f03e66136929306d5974>>
+ * @generated SignedSource<<008818e7f2d8b9e295704cccc33758e7>>
 */

 /**
@@ -86,6 +86,10 @@ class ReactNativeFeatureFlagsDefaults : public ReactNativeFeatureFlagsProvider {
  bool useNativeViewConfigsInBridgelessMode() override {
    return false;
  }
+
+  bool useStateAlignmentMechanism() override {
+    return false;
+  }
 };

 } // namespace facebook::react
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<21fb3f2ea9db49ea4710a13807c7512a>>
+ * @generated SignedSource<<270291da73cb3e4eddc7bd5cdc9a9470>>
 */

 /**
@@ -40,6 +40,7 @@ class ReactNativeFeatureFlagsProvider {
  virtual bool inspectorEnableModernCDPRegistry() = 0;
  virtual bool useModernRuntimeScheduler() = 0;
  virtual bool useNativeViewConfigsInBridgelessMode() = 0;
+  virtual bool useStateAlignmentMechanism() = 0;
 };

 } // namespace facebook::react
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<55ee96b1902071c987c70b5f07f670e4>>
+ * @generated SignedSource<<1abf19f9d1352105511e86c0f217de7a>>
 */

 /**
@@ -112,4 +112,9 @@ bool NativeReactNativeFeatureFlags::useNativeViewConfigsInBridgelessMode(
  return ReactNativeFeatureFlags::useNativeViewConfigsInBridgelessMode();
 }

+bool NativeReactNativeFeatureFlags::useStateAlignmentMechanism(
+    jsi::Runtime& /*runtime*/) {
+  return ReactNativeFeatureFlags::useStateAlignmentMechanism();
+}
+
 } // namespace facebook::react
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<f8f1ff1a05b772b861856d027659848a>>
+ * @generated SignedSource<<7a2a41f80549322a7f4255d193dc0b7b>>
 */

 /**
@@ -64,6 +64,8 @@ class NativeReactNativeFeatureFlags
  bool useModernRuntimeScheduler(jsi::Runtime& runtime);

  bool useNativeViewConfigsInBridgelessMode(jsi::Runtime& runtime);
+
+  bool useStateAlignmentMechanism(jsi::Runtime& runtime);
 };

 } // namespace facebook::react
@@ -8,6 +8,7 @@
 #include "ShadowTree.h"

 #include <react/debug/react_native_assert.h>
+#include <react/featureflags/ReactNativeFeatureFlags.h>
 #include <react/renderer/components/root/RootComponentDescriptor.h>
 #include <react/renderer/components/view/ViewShadowNode.h>
 #include <react/renderer/core/LayoutContext.h>
@@ -453,7 +454,7 @@ CommitStatus ShadowTree::tryCommit(
  }

  if (commitOptions.enableStateReconciliation) {
-    if (CoreFeatures::enableClonelessStateProgression) {
+    if (ReactNativeFeatureFlags::useStateAlignmentMechanism()) {
      progressStateIfNecessary(*newRootShadowNode, *oldRootShadowNode);
    } else {
      auto updatedNewRootShadowNode =
@@ -9,6 +9,8 @@

 #include <gtest/gtest.h>

+#include <react/featureflags/ReactNativeFeatureFlags.h>
+#include <react/featureflags/ReactNativeFeatureFlagsDefaults.h>
 #include <react/renderer/componentregistry/ComponentDescriptorProviderRegistry.h>
 #include <react/renderer/components/view/ViewComponentDescriptor.h>
 #include <react/renderer/core/PropsParserContext.h>
@@ -22,6 +24,20 @@

 using namespace facebook::react;

+class StateReconciliationTestFeatureFlags
+    : public ReactNativeFeatureFlagsDefaults {
+ public:
+  explicit StateReconciliationTestFeatureFlags(bool useStateAlignmentMechanism)
+      : useStateAlignmentMechanism_(useStateAlignmentMechanism) {}
+
+  bool useStateAlignmentMechanism() override {
+    return useStateAlignmentMechanism_;
+  }
+
+ private:
+  bool useStateAlignmentMechanism_;
+};
+
 class DummyShadowTreeDelegate : public ShadowTreeDelegate {
 public:
  RootShadowNode::Unshared shadowTreeWillCommit(
@@ -64,8 +80,15 @@ const ShadowNode* findDescendantNode(

 class StateReconciliationTest : public ::testing::TestWithParam<bool> {
 public:
-  StateReconciliationTest() : builder_(simpleComponentBuilder()) {
-    CoreFeatures::enableClonelessStateProgression = GetParam();
+  StateReconciliationTest() : builder_(simpleComponentBuilder()) {}
+
+  void SetUp() override {
+    ReactNativeFeatureFlags::override(
+        std::make_unique<StateReconciliationTestFeatureFlags>(GetParam()));
+  }
+
+  void TearDown() override {
+    ReactNativeFeatureFlags::dangerouslyReset();
  }

  ComponentBuilder builder_;
@@ -12,7 +12,6 @@ namespace facebook::react {
 bool CoreFeatures::enablePropIteratorSetter = false;
 bool CoreFeatures::enableGranularScrollViewStateUpdatesIOS = false;
 bool CoreFeatures::enableGranularShadowTreeStateReconciliation = false;
-bool CoreFeatures::enableClonelessStateProgression = false;
 bool CoreFeatures::excludeYogaFromRawProps = false;
 bool CoreFeatures::enableReportEventPaintTime = false;

@@ -27,9 +27,6 @@ class CoreFeatures {
  // state and the last commit that updated state changed before committing.
  static bool enableGranularShadowTreeStateReconciliation;

-  // When enabled, Fabric will avoid cloning notes to perform state progression.
-  static bool enableClonelessStateProgression;
-
  // When enabled, rawProps in Props will not include Yoga specific props.
  static bool excludeYogaFromRawProps;

@@ -101,6 +101,11 @@ const definitions: FeatureFlagDefinitions = {
      description:
        'When enabled, the native view configs are used in bridgeless mode.',
    },
+    useStateAlignmentMechanism: {
+      defaultValue: false,
+      description:
+        'When enabled, it uses optimised state reconciliation algorithm.',
+    },
  },

  jsOnly: {
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<45969617730126d45f35820ee3bd5853>>
+ * @generated SignedSource<<39fd96ed670e0acae857e7fce3377452>>
 * @flow strict-local
 */

@@ -55,6 +55,7 @@ export type ReactNativeFeatureFlags = {
  inspectorEnableModernCDPRegistry: Getter<boolean>,
  useModernRuntimeScheduler: Getter<boolean>,
  useNativeViewConfigsInBridgelessMode: Getter<boolean>,
+  useStateAlignmentMechanism: Getter<boolean>,
 }

 /**
@@ -157,6 +158,10 @@ export const useModernRuntimeScheduler: Getter<boolean> = createNativeFlagGetter
 * When enabled, the native view configs are used in bridgeless mode.
 */
 export const useNativeViewConfigsInBridgelessMode: Getter<boolean> = createNativeFlagGetter('useNativeViewConfigsInBridgelessMode', false);
+/**
+ * When enabled, it uses optimised state reconciliation algorithm.
+ */
+export const useStateAlignmentMechanism: Getter<boolean> = createNativeFlagGetter('useStateAlignmentMechanism', false);

 /**
 * Overrides the feature flags with the provided methods.
@@ -4,7 +4,7 @@
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
- * @generated SignedSource<<22dd9936df00ce7a53a5aa4a2c331279>>
+ * @generated SignedSource<<99ddb55dadff7adfb02c105984d47cbf>>
 * @flow strict-local
 */

@@ -38,6 +38,7 @@ export interface Spec extends TurboModule {
  +inspectorEnableModernCDPRegistry?: () => boolean;
  +useModernRuntimeScheduler?: () => boolean;
  +useNativeViewConfigsInBridgelessMode?: () => boolean;
+  +useStateAlignmentMechanism?: () => boolean;
 }

 const NativeReactNativeFeatureFlags: ?Spec = TurboModuleRegistry.get<Spec>(