Function mountClassInstance

packages/react-reconciler/src/ReactFiberClassComponent.js:761–850

(
  workInProgress: Fiber,
  ctor: any,
  newProps: any,
  renderLanes: Lanes,
)

// Invokes the mount life-cycles on a previously never rendered instance.
function mountClassInstance(
  workInProgress: Fiber,
  ctor: any,
  newProps: any,
  renderLanes: Lanes,
): void {
  if (__DEV__) {
    checkClassInstance(workInProgress, ctor, newProps);
  }

  const instance = workInProgress.stateNode;
  instance.props = newProps;
  instance.state = workInProgress.memoizedState;
  instance.refs = {};

  initializeUpdateQueue(workInProgress);

  const contextType = ctor.contextType;
  if (typeof contextType === 'object' && contextType !== null) {
    instance.context = readContext(contextType);
  } else if (disableLegacyContext) {
    instance.context = emptyContextObject;
  } else {
    const unmaskedContext = getUnmaskedContext(workInProgress, ctor, true);
    instance.context = getMaskedContext(workInProgress, unmaskedContext);
  }

  if (__DEV__) {
    if (instance.state === newProps) {
      const componentName = getComponentNameFromType(ctor) || 'Component';
      if (!didWarnAboutDirectlyAssigningPropsToState.has(componentName)) {
        didWarnAboutDirectlyAssigningPropsToState.add(componentName);
        console.error(
          '%s: It is not recommended to assign props directly to state ' +
            "because updates to props won't be reflected in state. " +
            'In most cases, it is better to use props directly.',
          componentName,
        );
      }
    }

    if (workInProgress.mode & StrictLegacyMode) {
      ReactStrictModeWarnings.recordLegacyContextWarning(
        workInProgress,
        instance,
      );
    }

    ReactStrictModeWarnings.recordUnsafeLifecycleWarnings(
      workInProgress,
      instance,
    );
  }

  instance.state = workInProgress.memoizedState;

  const getDerivedStateFromProps = ctor.getDerivedStateFromProps;
  if (typeof getDerivedStateFromProps === 'function') {