Clean up enableLazyContextPropagation (facebook#31810)

This flag has shipped everywhere, let's clean it up.

packages/react-dom/src/__tests__/ReactLegacyContextDisabled-test.internal.js

@@ -233,15 +233,7 @@ describe('ReactLegacyContextDisabled', () => {
       );
     });
     expect(container.textContent).toBe('bbb');
-    if (gate(flags => flags.enableLazyContextPropagation)) {
-      // In the lazy propagation implementation, we don't check if context
-      // changed until after shouldComponentUpdate is run.
-      expect(lifecycleContextLog).toEqual(['b', 'b', 'b']);
-    } else {
-      // In the eager implementation, a dirty flag was set when the parent
-      // changed, so we skipped sCU.
-      expect(lifecycleContextLog).toEqual(['b', 'b']);
-    }
+    expect(lifecycleContextLog).toEqual(['b', 'b', 'b']);
     root.unmount();
   });
 });

packages/react-reconciler/src/ReactFiberBeginWork.js

@@ -37,8 +37,6 @@ import type {
 import type {UpdateQueue} from './ReactFiberClassUpdateQueue';
 import type {RootState} from './ReactFiberRoot';
 import type {TracingMarkerInstance} from './ReactFiberTracingMarkerComponent';
-import type {TransitionStatus} from './ReactFiberConfig';
-import type {Hook} from './ReactFiberHooks';
 
 import {
   markComponentRenderStarted,
@@ -100,7 +98,6 @@ import {
   enableProfilerCommitHooks,
   enableProfilerTimer,
   enableScopeAPI,
-  enableLazyContextPropagation,
   enableSchedulingProfiler,
   enableTransitionTracing,
   enableLegacyHidden,
@@ -272,7 +269,6 @@ import {
   createClassErrorUpdate,
   initializeClassErrorUpdate,
 } from './ReactFiberThrow';
-import is from 'shared/objectIs';
 import {
   getForksAtLevel,
   isForkedChild,
@@ -843,7 +839,7 @@ function deferHiddenOffscreenComponent(
 
   pushOffscreenSuspenseHandler(workInProgress);
 
-  if (enableLazyContextPropagation && current !== null) {
+  if (current !== null) {
     // Since this tree will resume rendering in a separate render, we need
     // to propagate parent contexts now so we don't lose track of which
     // ones changed.
@@ -1636,26 +1632,6 @@ function updateHostComponent(
     } else {
       HostTransitionContext._currentValue2 = newState;
     }
-    if (enableLazyContextPropagation) {
-      // In the lazy propagation implementation, we don't scan for matching
-      // consumers until something bails out.
-    } else {
-      if (didReceiveUpdate) {
-        if (current !== null) {
-          const oldStateHook: Hook = current.memoizedState;
-          const oldState: TransitionStatus = oldStateHook.memoizedState;
-          // This uses regular equality instead of Object.is because we assume
-          // that host transition state doesn't include NaN as a valid type.
-          if (oldState !== newState) {
-            propagateContextChange(
-              workInProgress,
-              HostTransitionContext,
-              renderLanes,
-            );
-          }
-        }
-      }
-    }
   }
 
   markRef(current, workInProgress);
@@ -2706,10 +2682,7 @@ function updateDehydratedSuspenseComponent(
     }
 
     if (
-      enableLazyContextPropagation &&
       // TODO: Factoring is a little weird, since we check this right below, too.
-      // But don't want to re-arrange the if-else chain until/unless this
-      // feature lands.
       !didReceiveUpdate
     ) {
       // We need to check if any children have context before we decide to bail
@@ -3300,8 +3273,6 @@ function updateContextProvider(
     context = workInProgress.type._context;
   }
   const newProps = workInProgress.pendingProps;
-  const oldProps = workInProgress.memoizedProps;
-
   const newValue = newProps.value;
 
   if (__DEV__) {
@@ -3317,34 +3288,6 @@ function updateContextProvider(
 
   pushProvider(workInProgress, context, newValue);
 
-  if (enableLazyContextPropagation) {
-    // In the lazy propagation implementation, we don't scan for matching
-    // consumers until something bails out, because until something bails out
-    // we're going to visit those nodes, anyway. The trade-off is that it shifts
-    // responsibility to the consumer to track whether something has changed.
-  } else {
-    if (oldProps !== null) {
-      const oldValue = oldProps.value;
-      if (is(oldValue, newValue)) {
-        // No change. Bailout early if children are the same.
-        if (
-          oldProps.children === newProps.children &&
-          !hasLegacyContextChanged()
-        ) {
-          return bailoutOnAlreadyFinishedWork(
-            current,
-            workInProgress,
-            renderLanes,
-          );
-        }
-      } else {
-        // The context value changed. Search for matching consumers and schedule
-        // them to update.
-        propagateContextChange(workInProgress, context, renderLanes);
-      }
-    }
-  }
-
   const newChildren = newProps.children;
   reconcileChildren(current, workInProgress, newChildren, renderLanes);
   return workInProgress.child;
@@ -3463,7 +3406,7 @@ function bailoutOnAlreadyFinishedWork(
     // TODO: Once we add back resuming, we should check if the children are
     // a work-in-progress set. If so, we need to transfer their effects.
 
-    if (enableLazyContextPropagation && current !== null) {
+    if (current !== null) {
       // Before bailing out, check if there are any context changes in
       // the children.
       lazilyPropagateParentContextChanges(current, workInProgress, renderLanes);
@@ -3564,11 +3507,9 @@ function checkScheduledUpdateOrContext(
   }
   // No pending update, but because context is propagated lazily, we need
   // to check for a context change before we bail out.
-  if (enableLazyContextPropagation) {
-    const dependencies = current.dependencies;
-    if (dependencies !== null && checkIfContextChanged(dependencies)) {
-      return true;
-    }
+  const dependencies = current.dependencies;
+  if (dependencies !== null && checkIfContextChanged(dependencies)) {
+    return true;
   }
   return false;
 }
@@ -3706,7 +3647,7 @@ function attemptEarlyBailoutIfNoScheduledUpdate(
         workInProgress.childLanes,
       );
 
-      if (enableLazyContextPropagation && !hasChildWork) {
+      if (!hasChildWork) {
         // Context changes may not have been propagated yet. We need to do
         // that now, before we can decide whether to bail out.
         // TODO: We use `childLanes` as a heuristic for whether there is

packages/react-reconciler/src/ReactFiberClassComponent.js

@@ -21,7 +21,6 @@ import {
   debugRenderPhaseSideEffectsForStrictMode,
   disableLegacyContext,
   enableSchedulingProfiler,
-  enableLazyContextPropagation,
   disableDefaultPropsExceptForClasses,
 } from 'shared/ReactFeatureFlags';
 import ReactStrictModeWarnings from './ReactStrictModeWarnings';
@@ -1092,7 +1091,6 @@ function updateClassInstance(
     !hasContextChanged() &&
     !checkHasForceUpdateAfterProcessing() &&
     !(
-      enableLazyContextPropagation &&
       current !== null &&
       current.dependencies !== null &&
       checkIfContextChanged(current.dependencies)
@@ -1144,8 +1142,7 @@ function updateClassInstance(
     // both before and after `shouldComponentUpdate` has been called. Not ideal,
     // but I'm loath to refactor this function. This only happens for memoized
     // components so it's not that common.
-    (enableLazyContextPropagation &&
-      current !== null &&
+    (current !== null &&
       current.dependencies !== null &&
       checkIfContextChanged(current.dependencies));
 

packages/react-reconciler/src/ReactFiberHooks.js

@@ -36,7 +36,6 @@ import {
 import ReactSharedInternals from 'shared/ReactSharedInternals';
 import {
   enableSchedulingProfiler,
-  enableLazyContextPropagation,
   enableTransitionTracing,
   enableUseEffectEventHook,
   enableUseResourceEffectHook,
@@ -743,23 +742,21 @@ function finishRenderingHooks<Props, SecondArg>(
     );
   }
 
-  if (enableLazyContextPropagation) {
-    if (current !== null) {
-      if (!checkIfWorkInProgressReceivedUpdate()) {
-        // If there were no changes to props or state, we need to check if there
-        // was a context change. We didn't already do this because there's no
-        // 1:1 correspondence between dependencies and hooks. Although, because
-        // there almost always is in the common case (`readContext` is an
-        // internal API), we could compare in there. OTOH, we only hit this case
-        // if everything else bails out, so on the whole it might be better to
-        // keep the comparison out of the common path.
-        const currentDependencies = current.dependencies;
-        if (
-          currentDependencies !== null &&
-          checkIfContextChanged(currentDependencies)
-        ) {
-          markWorkInProgressReceivedUpdate();
-        }
+  if (current !== null) {
+    if (!checkIfWorkInProgressReceivedUpdate()) {
+      // If there were no changes to props or state, we need to check if there
+      // was a context change. We didn't already do this because there's no
+      // 1:1 correspondence between dependencies and hooks. Although, because
+      // there almost always is in the common case (`readContext` is an
+      // internal API), we could compare in there. OTOH, we only hit this case
+      // if everything else bails out, so on the whole it might be better to
+      // keep the comparison out of the common path.
+      const currentDependencies = current.dependencies;
+      if (
+        currentDependencies !== null &&
+        checkIfContextChanged(currentDependencies)
+      ) {
+        markWorkInProgressReceivedUpdate();
       }
     }
   }