Function processChildContext

code/new-context-api/public/app.js:11742–11785

(fiber, parentContext)

  }

  function processChildContext(fiber, parentContext) {
    var instance = fiber.stateNode;
    var childContextTypes = fiber.type.childContextTypes;

    // TODO (bvaughn) Replace this behavior with an invariant() in the future.
    // It has only been added in Fiber to match the (unintentional) behavior in Stack.
    if (typeof instance.getChildContext !== 'function') {
      {
        var componentName = getComponentName(fiber) || 'Unknown';

        if (!warnedAboutMissingGetChildContext[componentName]) {
          warnedAboutMissingGetChildContext[componentName] = true;
          warning(false, '%s.childContextTypes is specified but there is no getChildContext() method ' + 'on the instance. You can either define getChildContext() on %s or remove ' + 'childContextTypes from it.', componentName, componentName);
        }
      }
      return parentContext;
    }

    var childContext = void 0;
    {
      ReactDebugCurrentFiber.setCurrentPhase('getChildContext');
    }
    startPhaseTimer(fiber, 'getChildContext');
    childContext = instance.getChildContext();
    stopPhaseTimer();
    {
      ReactDebugCurrentFiber.setCurrentPhase(null);
    }
    for (var contextKey in childContext) {
      !(contextKey in childContextTypes) ? invariant(false, '%s.getChildContext(): key "%s" is not defined in childContextTypes.', getComponentName(fiber) || 'Unknown', contextKey) : void 0;
    }
    {
      var name = getComponentName(fiber) || 'Unknown';
      checkPropTypes(childContextTypes, childContext, 'child context', name,
      // In practice, there is one case in which we won't get a stack. It's when
      // somebody calls unstable_renderSubtreeIntoContainer() and we process
      // context from the parent component instance. The stack will be missing
      // because it's outside of the reconciliation, and so the pointer has not
      // been set. This is rare and doesn't matter. We'll also remove that API.
      ReactDebugCurrentFiber.getCurrentFiberStackAddendum);
    }

    return _assign({}, parentContext, childContext);
  }

  function pushContextProvider(workInProgress) {
    if (!isContextProvider(workInProgress)) {