Function pushTreeFork

packages/react-reconciler/src/ReactFiberTreeContext.js:106–132

(
  workInProgress: Fiber,
  totalChildren: number,
)

}

export function pushTreeFork(
  workInProgress: Fiber,
  totalChildren: number,
): void {
  // This is called right after we reconcile an array (or iterator) of child
  // fibers, because that's the only place where we know how many children in
  // the whole set without doing extra work later, or storing addtional
  // information on the fiber.
  //
  // That's why this function is separate from pushTreeId — it's called during
  // the render phase of the fork parent, not the child, which is where we push
  // the other context values.
  //
  // In the Fizz implementation this is much simpler because the child is
  // rendered in the same callstack as the parent.
  //
  // It might be better to just add a `forks` field to the Fiber type. It would
  // make this module simpler.

  warnIfNotHydrating();

  forkStack[forkStackIndex++] = treeForkCount;
  forkStack[forkStackIndex++] = treeForkProvider;

  treeForkProvider = workInProgress;
  treeForkCount = totalChildren;
}

export function pushTreeId(
  workInProgress: Fiber,