Babel 7

[GeoffreyBooth]

Revised version of #5102, closes #5102.

[GeoffreyBooth]

@rdeforest care to review this?

[rdeforest]

I took a look and didn't see anything I found surprising. I also searched the source for missed instances of babel- and didn't find any.

I have questions which I can probably find answers to on my own tomorrow but am posting here anyway:

• Is the babel- to @babel/ change the only one in Babel's v6 -> v7 transition which impacts CoffeeScript?
• Is there a mechanism to ensure the release which publishes this change is in sync with the docs at coffeescript.org/#transpilation?

If I find the answers before anyone responds I'll update this comment accordingly.

[GeoffreyBooth]

Is there a mechanism to ensure the release which publishes this change is in sync with the docs at coffeescript.org/#transpilation?

Good point! One way is for me to just update those docs now 😄
https://rawgit.com/geoffreybooth/coffeescript/babel-7/docs/v2/index.html
I’ll add the changelog when we actually do the release.

Is the babel- to @babel/ change the only one in Babel’s v6 -> v7 transition which impacts CoffeeScript?

This I don’t know. Within the CoffeeScript repo itself, we only use Babel to generate the browser compiler, which still gets generated and transpiled without error; and when I open the docs’ test.html in my browser and those tests are run using the browser compiler, they still all pass. But beyond the borders of this repo . . . probably not? At that point it’s just whatever differences between Babel 6 and 7 are relevant to the user’s code that they’re transpiling, which I think is a separate matter from CoffeeScript? Unless there are any common patterns that the compiler generates (like results arrays or executable class bodies) that are suddenly transpiled differently in Babel 7, but I can’t think of any that would be. But I encourage other voices to answer this, it’s a great question.

[rdeforest]

Neat, I was useful! :)

I looked over https://babeljs.io/docs/en/v7-migration and didn't see anything that sounded problematic, so I'm fully on-board for this PR.