When a node rerenders due to new context api update, its siblings rerender

Do you want to request a feature or report a bug?

Bug

What is the current behavior?

Nodes that use new context api force siblings nodes to rerender

What is the expected behavior?

Siblings should not rererender when a node updates due to context updates

Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?

16.3.1

Background:

i use react-navigation with react-native. react-navigation uses the new context-api. withNavigationFocus-HOC wraps the component with a NavigationConsumer, a context consumer.

In this example i get unexpected rerenders:

const SomethingThatHasNavigation = withNavigationFocus(
  class extends React.Component {
    render() { 
      // i should rerender whenever navigation changes. That's fine. Its value is from context
      return null
    }
  },
)

const ShouldNotRerender = class extends React.Component {
  render() {
    console.log('i should not rerender when my sibiling updates')
    return null
  }
}

const Test = class extends React.PureComponent {
  render() {
    console.log('test renders once')
    return (
      <View>
        <SomethingThatHasNavigation />
        <ShouldNotRerender />
      </View>
    )
  }
}

What’s wrong? is this by design?

[gaearon]

I think the fix would be in 0.56.

[jacobpdq]

I’m running 16.4.

I have two independent dom nodes, far off from each other and not children/parents of either - not even siblings in a parent.

Any update to one forces an update to another, leading me to believe this feature is a singleton for a global context. Please advise @gaearon