Modal render children is not sync which break getting ref in useEffect

[NE-SmallTown]

• I have searched the issues of this repository and believe that this is not a duplicate.

Reproduction link

Steps to reproduce

Open the codesandbox link , and then check the console output

What is expected?

Can successfully get the ref.current of Modal's children

What is actually happening?

It's null, so have to use a setTimeout

Environment	Info
antd	4.6.2
React	16.12.0
System	Windows 10
Browser	Google Chrome 84.0.4147.135

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This bug is because when the getContainer prop to Modal is not false, the Modal component will call createContainer in the cDM which will call getContainer to create a new DOM element and append it to the document.body. But, it will not render the children at that time, on the contrary, it will trigger the forceUpdate after that, and so, the useEffect in our component will be triggered before the children be mounted to the DOM because forceUpdate is not a "sync" operation(same as setState). So, when the useEffect fired, we cant get the children DOM instance

[NE-SmallTown]

friendly ping~

[zombieJ]

+ rc-util@5.3.1

Add forceRender in your code.

[NE-SmallTown]

ok，close for react-component/util#150

[mikedeng]

How to solve this , I got the same problem in the latest antd@4.23.6, it doesn't work after forceUpdate added