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Try not. Do... or do not. Hydrate Suspense Boundaries. #32851

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Merged
merged 1 commit into from
Apr 11, 2025
+22 −30
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Try not. Do... or do not. Hydrate Suspense Boundaries. #32851

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29 changes: 9 additions & 20 deletions packages/react-reconciler/src/ReactFiberBeginWork.js
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Original file line number Diff line number Diff line change
Expand Up @@ -203,7 +203,6 @@ import {
pushFallbackTreeSuspenseHandler,
pushOffscreenSuspenseHandler,
reuseSuspenseHandlerOnStack,
popSuspenseHandler,
} from './ReactFiberSuspenseContext';
import {
pushHiddenContext,
Expand Down Expand Up @@ -245,7 +244,7 @@ import {
claimHydratableSingleton,
tryToClaimNextHydratableInstance,
tryToClaimNextHydratableTextInstance,
tryToClaimNextHydratableSuspenseInstance,
claimNextHydratableSuspenseInstance,
warnIfHydrating,
queueHydrationError,
} from './ReactFiberHydrationContext';
Expand Down Expand Up @@ -2151,24 +2150,14 @@ function updateSuspenseComponent(
} else {
pushFallbackTreeSuspenseHandler(workInProgress);
}
tryToClaimNextHydratableSuspenseInstance(workInProgress);
// This could've been a dehydrated suspense component.
const suspenseState: null | SuspenseState = workInProgress.memoizedState;
if (suspenseState !== null) {
const dehydrated = suspenseState.dehydrated;
if (dehydrated !== null) {
return mountDehydratedSuspenseComponent(
workInProgress,
dehydrated,
renderLanes,
);
}
}
// If hydration didn't succeed, fall through to the normal Suspense path.
// To avoid a stack mismatch we need to pop the Suspense handler that we
// pushed above. This will become less awkward when move the hydration
// logic to its own fiber.
popSuspenseHandler(workInProgress);
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This code path became unreachable once we started throwing for all hydration mismatches but we didn't know that due to the code structure.

// This throws if we fail to hydrate.
const dehydrated: SuspenseInstance =
claimNextHydratableSuspenseInstance(workInProgress);
return mountDehydratedSuspenseComponent(
workInProgress,
dehydrated,
renderLanes,
);
}

const nextPrimaryChildren = nextProps.children;
Expand Down
23 changes: 13 additions & 10 deletions packages/react-reconciler/src/ReactFiberHydrationContext.js
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Original file line number Diff line number Diff line change
Expand Up @@ -272,7 +272,10 @@ function tryHydrateText(fiber: Fiber, nextInstance: any) {
return false;
}

function tryHydrateSuspense(fiber: Fiber, nextInstance: any) {
function tryHydrateSuspense(
fiber: Fiber,
nextInstance: any,
): null | SuspenseInstance {
// fiber is a SuspenseComponent Fiber
const suspenseInstance = canHydrateSuspenseInstance(
nextInstance,
Expand All @@ -298,9 +301,8 @@ function tryHydrateSuspense(fiber: Fiber, nextInstance: any) {
// While a Suspense Instance does have children, we won't step into
// it during the first pass. Instead, we'll reenter it later.
nextHydratableInstance = null;
return true;
}
return false;
return suspenseInstance;
}

export const HydrationMismatchException: mixed = new Error(
Expand Down Expand Up @@ -423,15 +425,16 @@ function tryToClaimNextHydratableTextInstance(fiber: Fiber): void {
}
}

function tryToClaimNextHydratableSuspenseInstance(fiber: Fiber): void {
if (!isHydrating) {
return;
}
function claimNextHydratableSuspenseInstance(fiber: Fiber): SuspenseInstance {
const nextInstance = nextHydratableInstance;
if (!nextInstance || !tryHydrateSuspense(fiber, nextInstance)) {
const suspenseInstance = nextInstance
? tryHydrateSuspense(fiber, nextInstance)
: null;
if (suspenseInstance === null) {
warnNonHydratedInstance(fiber, nextInstance);
throwOnHydrationMismatch(fiber);
throw throwOnHydrationMismatch(fiber);
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Satisfies Flow. Does Flow not have something like never where this is asserted to always throw?

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@jbrown215 ?

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empty

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It didn't work

}
return suspenseInstance;
}

export function tryToClaimNextHydratableFormMarkerInstance(
Expand Down Expand Up @@ -790,7 +793,7 @@ export {
claimHydratableSingleton,
tryToClaimNextHydratableInstance,
tryToClaimNextHydratableTextInstance,
tryToClaimNextHydratableSuspenseInstance,
claimNextHydratableSuspenseInstance,
prepareToHydrateHostInstance,
prepareToHydrateHostTextInstance,
prepareToHydrateHostSuspenseInstance,
Expand Down
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