Function prepareToReadContext

packages/react-reconciler/src/ReactFiberNewContext.js:488–500

(
  workInProgress: Fiber,
  renderLanes: Lanes,
)

}

export function prepareToReadContext(
  workInProgress: Fiber,
  renderLanes: Lanes,
): void {
  currentlyRenderingFiber = workInProgress;
  lastContextDependency = null;

  const dependencies = workInProgress.dependencies;
  if (dependencies !== null) {
    // Reset the work-in-progress list
    dependencies.firstContext = null;
  }
}

export function readContext<T>(context: ReactContext<T>): T {
  if (__DEV__) {