[no-sequences]: allowInParentheses ain't work with arrows

[bricss]

• ESLint Version: 7.23 + @babel/eslint-parser
• Node Version: 15.12.0
• npm Version: 7.6.3
• Operating System: win10_x64

It looks like newly added allowInParentheses option of no-sequences rule won't work with arrow functions.

const wat = (op) => (console.log('wat'), op);

What did you expect to happen?
Expect it to pass validation

What actually happened?
Validation error: Unexpected use of comma operator

[mdjermanovic]

Hi @bricss, thanks for the issue!

It looks like newly added allowInParentheses option of no-sequences rule won't work with arrow functions.

const wat = (op) => (console.log('wat'), op);

This works as expected. allowInParentheses: true (default) retains the previous behavior of this rule, which is to allow sequence expressions that are explicitly wrapped in parentheses. For arrow function's body, "explicitly" was considered as being parenthesized twice (ref #6082):

/* eslint no-sequences: ["error", { "allowInParentheses": true } ] */

const wat1 = (op) => (console.log('wat'), op); // error

const wat2 = (op) => ((console.log('wat'), op)); // ok

Online Demo

I've verified that ESLint v7.22.0 with the provided example gives the same result.

Marked as accepted issue to improve documentation. We should add some examples with arrow functions to clarify this.

[bricss]

Isn't it like a buttery butter 🧈 to wrap 🌯 it twice in parentheses?
It's obviously looks already wrapped in first example.
Don't see a reason to do it twice 🤔

[zcqno1]

It's commonly conflict with the prettier format rule. The extra parentheses would be removed.