Function updateContainerSync

packages/react-reconciler/src/ReactFiberReconciler.js:375–394

(
  element: ReactNodeList,
  container: OpaqueRoot,
  parentComponent: ?component(...props: any),
  callback: ?Function,
)

}

export function updateContainerSync(
  element: ReactNodeList,
  container: OpaqueRoot,
  parentComponent: ?component(...props: any),
  callback: ?Function,
): Lane {
  if (!disableLegacyMode && container.tag === LegacyRoot) {
    flushPendingEffects();
  }
  const current = container.current;
  updateContainerImpl(
    current,
    SyncLane,
    element,
    container,
    parentComponent,
    callback,
  );
  return SyncLane;
}

function updateContainerImpl(
  rootFiber: Fiber,