utils.isReturningJSX is returning false all the time

[zachguo]

I found this when I was working on a new rule. #736

All following SFC nodes are considered not returning JSX by utils.isReturningJSX(node). utils.isReturningJSX(node.parent) & utils.isReturningJSX(node.body) are both returning false too.

const Hello = (props, context) => {
  return <div>Hello {context.name}</div>;
};

const Hello = function(props, context) {
  return <div>Hello {context.name}</div>;
};

const Hello = (props, {name}) => {
  return <div>Hello {name}</div>;
};

[zachguo]

A new util function like isStatelessFunctionalComponent to handle SFC detection may be needed. SFC detection has been discussed and requested many times: #512 #578 #672
And the util function should be unit tested.

[ljharb]

Certainly isReturningJSX should be fixed.

Separately, an isSFC function should be added, but that doesn't have to be done at the same time.

[mjackson]

As I suggested here I believe the only way to create an accurate isStatelessFunctionalComponent method would be to check if a function is ever actually used as the first argument in React.createElement. Otherwise you're going to get a bunch of false positives with methods that return some JSX but aren't intended to be SFCs.

[ljharb]

We've done lots of improvements here, and I believe this original issue is fixed.

If there's further bugs, please open a new issue (or better, a PR with failing tests), and we'll address it.