Proposal: context.version

[mysticatea]

What is the purpose of this pull request? (put an "X" next to item)

[X] Add something to the core

I request to add version to the rule context.

exports.create = (context) => {
    console.log(context.version) // → 4.7.0
    return {}
}

The context.version is useful in many cases. Below cases are examples, though this is too late.

Check the behavior of directive comments

Since 4.7.0, eslint-enable's behavior was changed a bit (#9216 (comment)).
eslint-plugin-eslint-comments plugin want to follow the change. It wants to detect the actual behavior on the ESLint which is running, but cannot know without the context.version.

Check the behavior of auto-fixing.

Since 4.1.0, fix functions which are passed to context.report can return an iterable object (includes an array) (#8101).
I want to use it and to avoid critical error on <4.1.0, but rules cannot know whether the fix functions can return an iterable object or not without the context.version.

Check the behavior of the location of problems.

Since 3.1.0, loc properties which are passed to context.report can be {start: object, end: object} to express the range of the problem (#6640).
I had wanted to use it and to avoid critical error on <3.1.0, but rules could not know whether the context.report accepts the range or not without context.version.

What changes did you make? (Give an overview)

This PR adds the version property into rule contexts.

Is there anything you'd like reviewers to focus on?

Direction.

[mention-bot]

@mysticatea, thanks for your PR! By analyzing the history of the files in this pull request, we identified @not-an-aardvark, @nzakas and @gyandeeps to be potential reviewers.

[eslintbot]

LGTM

[ilyavolodin]

On one hand, this is a small enhancement that I have no issue with adding, on the other, I really don't think it's a good idea for rules to know anything about the core, since that could lead to unpredictable behavior based on the version of ESLint you have installed. To me, a better solution is to mark a given version of ESLint as required in a plugin, and drop support for older version.

[not-an-aardvark]

We should probably create an issue for this since it's a core change (see here)

[mysticatea]

Closing since I don't have enough time.