React: Fiber cannot render to DocumentFragment/ShadowRoot

[Hotell]

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

What is the current behavior?
React 15.x was able to render within a DocumentFragment/shadowRoot, not possible with Fiber anymore

DEMO

https://www.webpackbin.com/bins/-KvPFG7-HGfQ34IgUxQt

import React, {Component} from 'react'
import {render} from 'react-dom'


class MyComponent extends Component{
  render(){
    return <div>Hello From React !</div>
  }
}

class MyElement extends HTMLElement {
  static is = 'my-element'
  constructor(){
    super()
    const shadowRoot = this.attachShadow({mode:'open'})
    try {
      // this fails 
      render(<MyComponent/>, shadowRoot)
    } catch (e){
      console.error(e)
      shadowRoot.innerHTML = `
        <div style="color:red;">${e}</div>
        <div>see console log for stack trace</div>
       `
    }
  }
  connectedCallback(){
    console.log('MyElement mounted!')
  }
}

customElements.define(MyElement.is, MyElement)

related -> https://github.com/skatejs/renderer-react/issues/3

What is the expected behavior?
be able to render to shadow root like previous versions of React

Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?
React 16
Chrome

[gaearon]

I have a fix in https://github.com/facebook/react/pull/11037.

[gaearon]

Note: there are more places in the source where we compare to DOCUMENT_NODE. Should we compare to DOCUMENT_FRAGMENT_NODE for them too? Do you want to do an audit and check all these cases?

[Hotell]

Fix looks good @gaearon ! thx for super fast response :)

Note: there are more places in the source where we compare to DOCUMENT_NODE. Should we compare to DOCUMENT_FRAGMENT_NODE for them too? Do you want to do an audit and check all these cases?

I think this check within getRootHostContext should be enough for WebComponents

[Hotell]

maybe also adding addition test for <template/> tag ?

const template = document.createElement('template')
template.innerHTML = `<div>Render here</div>`

const templateInstance = template.content.cloneNode(true)
ReactDOM.render(React.createElement(HelloWorld), templateInstance);

[gaearon]

Would you like to contribute to the fixture I added? You can send a PR against my fork branch. You know more about web components than I do :-)