Function popToNearestCommonAncestor

packages/react-server/src/ReactFizzNewContext.js:57–86

(
  prev: ContextNode<any>,
  next: ContextNode<any>,
)

}

function popToNearestCommonAncestor(
  prev: ContextNode<any>,
  next: ContextNode<any>,
): void {
  if (prev === next) {
    // We've found a shared ancestor. We don't need to pop nor reapply this one or anything above.
  } else {
    popNode(prev);
    const parentPrev = prev.parent;
    const parentNext = next.parent;
    if (parentPrev === null) {
      if (parentNext !== null) {
        throw new Error(
          'The stacks must reach the root at the same time. This is a bug in React.',
        );
      }
    } else {
      if (parentNext === null) {
        throw new Error(
          'The stacks must reach the root at the same time. This is a bug in React.',
        );
      }

      popToNearestCommonAncestor(parentPrev, parentNext);
    }

    // On the way back, we push the new ones that weren't common.
    pushNode(next);
  }
}

function popAllPrevious(prev: ContextNode<any>): void {
  popNode(prev);