False `Missing "key" prop for element in iterator` from jsx-key

[lencioni]

First of all, great work on the jsx-key rule. I think this will save people a lot of time.

Now, I have the following code:

<TransitionMotion
  styles={this._getStyles()}
  willEnter={this._willEnter}
  willLeave={this._willLeave}
  >
  {styles =>
    <div>
      {Object.keys(styles).map(key =>
        <Toast
          action={styles[key].action}
          key={key}
          message={styles[key].message}
          opacity={styles[key].opacity}
          translateY={`${styles[key].translateY}%`}
        />
      )}
    </div>
  }
</TransitionMotion>

using the jsx-key rule, I am getting the missing key prop on the line that has the opening <div>. I might be misunderstanding when key should be used, but I don't think I need one here. And, if I do, then the error message that this rule outputs is misleading since it claims that I am in an iterator when I am not.

I noticed in the documentation:

Also, if you have some prevalent situation where you use arrow functions to return JSX that will not be held in an iterable, you may want to disable this rule.

which I believe is referring to this situation, but I figured I'd open an issue for this anyway in case there happens to be a solution lurking.

[lencioni]

I am also noticing that this gives false errors on pure functional stateless components that are now available as of React 0.14:

const MyComponent = () =>
  <div>
    ...
  </div>;

[silvenon]

eslint-plugin-react naively checks just if the element is a part of an arrow expression. I'm setting up a PR…