Split strict effects warning into two flags

This lets us (a) can enable it for 100% of Facebook engineers¹² and (b) provide a simple opt-out mechanism for engineers who know about the mode and no longer want to see the warning.

¹ This warning will not be logged for legacy applications that aren't in strict effects mode.
² GKs within Facebook can't be enabled for 100% of a population.

Author: Brian Vaughn

packages/react-reconciler/src/ReactFiberWorkLoop.new.js

@@ -35,6 +35,7 @@ import {
   enableDoubleInvokingEffects,
   skipUnmountedBoundaries,
   enableStrictEffectsModeDevWarningForFacebookOnly,
+  bypassStrictEffectsModeDevWarningForFacebookOnly,
 } from 'shared/ReactFeatureFlags';
 import ReactSharedInternals from 'shared/ReactSharedInternals';
 import invariant from 'shared/invariant';
@@ -2591,7 +2592,11 @@ function commitDoubleInvokeEffectsInDEV(
       return;
     }
 
-    if (__DEV__ && enableStrictEffectsModeDevWarningForFacebookOnly) {
+    if (
+      __DEV__ &&
+      enableStrictEffectsModeDevWarningForFacebookOnly &&
+      !bypassStrictEffectsModeDevWarningForFacebookOnly
+    ) {
       if (!didWarnAboutStrictEffectsMode) {
         didWarnAboutStrictEffectsMode = true;
 

packages/react-reconciler/src/ReactFiberWorkLoop.old.js

@@ -36,6 +36,7 @@ import {
   skipUnmountedBoundaries,
   enableDiscreteEventMicroTasks,
   enableStrictEffectsModeDevWarningForFacebookOnly,
+  bypassStrictEffectsModeDevWarningForFacebookOnly,
 } from 'shared/ReactFeatureFlags';
 import ReactSharedInternals from 'shared/ReactSharedInternals';
 import invariant from 'shared/invariant';
@@ -2571,7 +2572,11 @@ function commitDoubleInvokeEffectsInDEV(
       return;
     }
 
-    if (__DEV__ && enableStrictEffectsModeDevWarningForFacebookOnly) {
+    if (
+      __DEV__ &&
+      enableStrictEffectsModeDevWarningForFacebookOnly &&
+      !bypassStrictEffectsModeDevWarningForFacebookOnly
+    ) {
       if (!didWarnAboutStrictEffectsMode) {
         didWarnAboutStrictEffectsMode = true;
 

packages/react-reconciler/src/__tests__/ReactDoubleInvokeEvents-test.internal.js

@@ -82,6 +82,23 @@ describe('ReactDoubleInvokeEvents', () => {
         );
       });
     });
+
+    it('should not log if bypass flag has been enabled (by GK allowlist)', () => {
+      ReactFeatureFlags.bypassStrictEffectsModeDevWarningForFacebookOnly = true;
+
+      function Component() {
+        React.useLayoutEffect(() => {}, []);
+        return null;
+      }
+
+      ReactNoop.act(() => {
+        ReactNoop.render(
+          <React.StrictMode>
+            <Component />
+          </React.StrictMode>,
+        );
+      });
+    });
   });
 
   it('should not double invoke effects in legacy mode', () => {

packages/shared/ReactFeatureFlags.js

@@ -160,4 +160,12 @@ export const enableDiscreteEventMicroTasks = false;
 // Facebook specific instructions for how to disable it (using a GK blocklist).
 // If we decide to add a similar warning for OSS we'll need to revisit both the
 // wording and the opt-out mechansim.
+//
+// This warning is controlled by two flags so that (a) we can enable it for 100%
+// of Facebook engineers¹² only and (b) provide a simple opt-out mechanism for engineers
+// who know about the mode and no longer want to see the warning.
+//
+// ¹ This warning will not be logged for legacy applications that aren't in strict effects mode.
+// ² GKs within Facebook can't be enabled for 100% of a population.
 export const enableStrictEffectsModeDevWarningForFacebookOnly = false;
+export const bypassStrictEffectsModeDevWarningForFacebookOnly = false;

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

@@ -61,6 +61,7 @@ export const disableSchedulerTimeoutInWorkLoop = false;
 export const enableTransitionEntanglement = false;
 export const enableDiscreteEventMicroTasks = false;
 export const enableStrictEffectsModeDevWarningForFacebookOnly = false;
+export const bypassStrictEffectsModeDevWarningForFacebookOnly = false;
 
 // Flow magic to verify the exports of this file match the original version.
 // eslint-disable-next-line no-unused-vars

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

@@ -60,6 +60,7 @@ export const disableSchedulerTimeoutInWorkLoop = false;
 export const enableTransitionEntanglement = false;
 export const enableDiscreteEventMicroTasks = false;
 export const enableStrictEffectsModeDevWarningForFacebookOnly = false;
+export const bypassStrictEffectsModeDevWarningForFacebookOnly = false;
 
 // Flow magic to verify the exports of this file match the original version.
 // eslint-disable-next-line no-unused-vars

packages/shared/forks/ReactFeatureFlags.test-renderer.js

@@ -60,6 +60,7 @@ export const disableSchedulerTimeoutInWorkLoop = false;
 export const enableTransitionEntanglement = false;
 export const enableDiscreteEventMicroTasks = false;
 export const enableStrictEffectsModeDevWarningForFacebookOnly = false;
+export const bypassStrictEffectsModeDevWarningForFacebookOnly = false;
 
 // Flow magic to verify the exports of this file match the original version.
 // eslint-disable-next-line no-unused-vars

packages/shared/forks/ReactFeatureFlags.test-renderer.native.js

@@ -47,6 +47,7 @@ export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = false;
 export const enableStrictEffectsModeDevWarningForFacebookOnly = false;
+export const bypassStrictEffectsModeDevWarningForFacebookOnly = false;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;

packages/shared/forks/ReactFeatureFlags.test-renderer.www.js

@@ -60,6 +60,7 @@ export const disableSchedulerTimeoutInWorkLoop = false;
 export const enableTransitionEntanglement = false;
 export const enableDiscreteEventMicroTasks = false;
 export const enableStrictEffectsModeDevWarningForFacebookOnly = false;
+export const bypassStrictEffectsModeDevWarningForFacebookOnly = false;
 
 // Flow magic to verify the exports of this file match the original version.
 // eslint-disable-next-line no-unused-vars

packages/shared/forks/ReactFeatureFlags.testing.js

@@ -60,6 +60,7 @@ export const disableSchedulerTimeoutInWorkLoop = false;
 export const enableTransitionEntanglement = false;
 export const enableDiscreteEventMicroTasks = false;
 export const enableStrictEffectsModeDevWarningForFacebookOnly = false;
+export const bypassStrictEffectsModeDevWarningForFacebookOnly = false;
 
 // Flow magic to verify the exports of this file match the original version.
 // eslint-disable-next-line no-unused-vars