trailingComma: 'all' does not work when using rest operator in destructuring assignment

[aquilae]

Prettier 1.10.2
Playground link

--print-width 30
--trailing-comma all

Input:

function test(arg) {
	const { prop1, prop2, ...otherProps } = arg;
}

Output:

function test(arg) {
  const {
    prop1,
    prop2,
    ...otherProps
  } = arg;
}

Expected behavior:
Should add trailing comma to ...otherProps.
Saw some discussion about it here, but the fact is it's definitely inconsistent as it is as removing the rest operator results in comma being there.

[j-f1]

This is intentional: tc39/proposal-object-rest-spread#47. The trailing comma is forbidden after the rest property.

[aquilae]

Isn't the whole point of all option is to add commas everywhere even if it's not supported by spec?
If that's not the case then the difference between all and es5 seems pretty vague.
And what's the difference between this and function parameters comma which is, as I understand, forbidden as well?

[j-f1]

Isn't the whole point of all option is to add commas everywhere even if it's not supported by spec?

No, because we strive to always output valid JS.

If that's not the case then the difference between all and es5 seems pretty vague.

es5 outputs commas where they’re allowed by the (9-year-old) ECMAScript 5 spec, whereas all outputs commas where they’re allowed by the current spec, including in syntax proposals.

And what's the difference between this and function parameters comma which is, as I understand, forbidden as well?

Not in the latest edition of ECMAScript.

[aquilae]

OK, I see, thanks for extensive answer.
Guess we'll have to tweak our lint config instead.