tricky behaviour of `define-flow-type` rule

[petersolopov]

Hi there! I found some tricky behaviour with define-flow-type rule:

type A = {foo: Foo};
Foo();

no-undef with define-flow-type rules will not pay attention to Foo variable. It starts to be global. Yeah, Flow checks it, but see real code that cause of issue:

type Props = {children: React.Node};

export default React.memo(({ children }: Props) => children)

Flow and eslint were not give the error. But in runtime error was thrown "React is not defined" because it does have react import.

I suggest making the option for this rule like ignoreTypes. It will be array with all types that will not were global.

What do you think about it? Thanks!

[petersolopov]

adding ignoreTypes option in #509 as PoC. It has tests as well