Add a --fix option for dot-notation

[not-an-aardvark]

I'm using Node v6.4.0 and ESLint v3.4.0.

It would be useful to have an autofix option for the dot-notation rule. The rule currently reports cases where bracket notation can be safely replaced by dot notation; the fixer would go ahead and make that replacement.

var foo = bar["baz"];

// gets fixed to:

var foo = bar.baz;

The fixer could also replace invalid dot-notations (e.g. keywords when the {allowKeywords: false} option is set) with the bracket-notation counterpart.

/*eslint dot-notation: ["error", { "allowKeywords": false }]*/

var foo = bar.while;

// gets fixed to:

var foo = bar["while"];

If the brackets contain comments, I'm unsure of what the fixer should do. I suppose one option would be to extract the comment out:

var foo = bar[ /* AA */ "baz" /* BB */ ];

// gets fixed to:

var foo = bar /* AA */ .baz /* BB */ ;

...but that doesn't look very good. I think comments within bracketed properties are fairly rare anyway, so this might be okay. (Alternatively, we could refrain from fixing cases where the brackets contain a comment, but in that case it seems more consistent to not report those cases as errors either.)

---

I would be willing to add this if the issue is accepted.

edit: Added a section about fixing from dot-notation to bracket-notation with keywords.
edit: Added a section about what to do with comments.

[mysticatea]

Sounds very good to me.
👍

[pmcelhaney]

Is there a general guideline for what a fixer should do if comments interfere? That seems to be a common problem.

My preference would be to not automatically fix code that involves comments. It doesn't hurt anyone to require human intervention in those rare cases.

[vitorbal]

@pmcelhaney if i understood your question correctly, this might be related: #5958 (comment)
TL;DR we won't autofix when a comment interferes

[nzakas]

Seems reasonable. 👍

To echo what @vitorbal said, if we can't be 100% correct with the fix, we shouldn't attempt it. So in the case of comments, we should just skip that.

[platinumazure]

👍 from me, now we just need a champion.