Allow ecmaVersion to be 'latest'?

[fisker]

I'm not sure if this make sense to change here, but parsers like @babel/eslint-parser pass ecmaVesion from eslintrc directly to eslint-scope, we need to make change in the parser or eslint-scope to understand 'latest'.

RR in babel codebase babel/babel#13638, review comment

[nzakas]

ESLint doesn't pass "latest" around. It is normalized to the latest ecmaVersion.

Honestly, eslint-scope doesn't really need ecmaVersion. The only difference is between 5 and 6+, for let and const. Even then we probably don't need the setting because an ES5 AST won't have let or const.

[nzakas]

@fisker any other points I’m missing here?

[fisker]

ESLint doesn't pass "latest" around.

I think @babel/eslint-parser pass it to eslint-scope, so the real question is should we handle "latest" here or @babel/eslint-parser.

[nzakas]

Ah I see. I’d suggest you normalize “latest” to a version number. But as I mentioned, the only thing that matters is 5 vs 6. You can probably just pass 6 all the time.

[fisker]

Thank you, I'll try to make the change in babel then.

[nzakas]

Sounds good.