Fix incorrect propType warning inside .map

[dustinsoftware]

Opening this PR for discussion. This PR fixes this false error:

'one' PropType is defined but prop is never used

Caused by this test case:

const Inner = (props) => <span>{props.innerOne} {props.innerTwo}</span>;
const Outer = (props) => {
    let team = props.names.map(() => (
        <Inner innerOne={props.one} innerTwo={props.two} />
    ));
    return <ul>{team}</ul>;
};
Outer.propTypes = {
    names: PropTypes.array,
    one: PropTypes.string,
    two: PropTypes.string
};

However, looks like my fix caused a few other tests to fail. I intend to push an update once I do some more investigation.

[ljharb]

I'd prefer to avoid for..of in favor of .forEach or .map

[ljharb]

nothing about this test case should require babel-eslint; can it use the default parser instead?

[ljharb]

Are there any tests for this change, btw?

[dustinsoftware]

I didn't see a good place to put a test for this specific change, and the logic behind get changes, the test I did add will fail.

[dustinsoftware]

Updated

[ljharb]

Your fix LGTM. I'm not stoked on the findParent arg, but I'll let other collabs weigh in.

[EvHaus]

This function is used very heavily across many rules.

I would not recommend adding this new argument here and instead handling the findParent logic inside the no-unused-prop-types rule directly.

[EvHaus]

I'm guessing that this would only happen address direct map() calls. So if you have a nested map, it would still throw a false positive right? eg.

'const Outer = (props) => {',
'  let team = props.names.map(() => (',
'      ["anotherThing"].map(() => {',
'            <Inner innerOne={props.one} innerTwo={props.two} />',
'      });',
'    ));',
'  return <ul>{team}</ul>;',
'};'

[dustinsoftware]

@DianaSuvorova had a better fix in #1322 😄 This PR isn't needed anymore.