[React Native FB] dynamic feature flag for ref access warning (#25471)

Author: kassens

packages/shared/forks/ReactFeatureFlags.native-fb-dynamic.js

@@ -7,10 +7,8 @@
  * @flow strict
  */
 
-// NOTE: There are no flags, currently. Uncomment the stuff below if we add one.
-
-// import typeof * as ExportsType from './ReactFeatureFlags.native-fb-dynamic';
-// import typeof * as DynamicFlagsType from 'ReactNativeInternalFeatureFlags';
+import typeof * as ExportsType from './ReactFeatureFlags.native-fb-dynamic';
+import typeof * as DynamicFlagsType from 'ReactNativeInternalFeatureFlags';
 
 // In xplat, these flags are controlled by GKs. Because most GKs have some
 // population running in either mode, we should run our tests that way, too,
@@ -22,5 +20,7 @@
 // flag here but it won't be set to `true` in any of our test runs. Need to
 // update the test configuration.
 
-// // Flow magic to verify the exports of this file match the original version.
-// ((((null: any): ExportsType): FeatureFlagsType): ExportsType);
+export const enableUseRefAccessWarning = __VARIANT__;
+
+// Flow magic to verify the exports of this file match the original version.
+((((null: any): ExportsType): DynamicFlagsType): ExportsType);

packages/shared/forks/ReactFeatureFlags.native-fb.js

@@ -13,11 +13,11 @@ import typeof * as ExportsType from './ReactFeatureFlags.native-fb';
 // NOTE: There are no flags, currently. Uncomment the stuff below if we add one.
 // Re-export dynamic flags from the internal module. Intentionally using *
 // because this import is compiled to a `require` call.
-// import * as dynamicFlags from 'ReactNativeInternalFeatureFlags';
+import * as dynamicFlags from 'ReactNativeInternalFeatureFlags';
 
 // We destructure each value before re-exporting to avoid a dynamic look-up on
 // the exports object every time a flag is read.
-// export const {} = dynamicFlags;
+export const {enableUseRefAccessWarning} = dynamicFlags;
 
 // The rest of the flags are static for better dead code elimination.
 export const enableDebugTracing = false;
@@ -67,7 +67,6 @@ export const deferRenderPhaseUpdateToNextBatch = false;
 
 export const enableStrictEffects = __DEV__;
 export const createRootStrictEffectsByDefault = false;
-export const enableUseRefAccessWarning = false;
 
 export const disableSchedulerTimeoutInWorkLoop = false;
 export const enableLazyContextPropagation = false;

scripts/flow/xplat.js

@@ -8,4 +8,5 @@
  */
 
 declare module 'ReactNativeInternalFeatureFlags' {
+  declare export var enableUseRefAccessWarning: boolean;
 }