884372 - Update default parameter implementation to match spec

Status: RESOLVED DUPLICATE of bug 1283482

(Core :: JavaScript Engine, defect)

Description

[Boris Zbarsky [:bzbarsky]]

It looks like bug 757676 implemented based on a document that was at that point 3 years out of date...  See http://lists.w3.org/Archives/Public/public-script-coord/2013AprJun/0732.html for more details.

Not sure whether we have an ES6 tracker that should track this.

Comment 1

[Jason Orendorff [:jorendorff]]

(In reply to Boris Zbarsky (:bz) from comment #0)
> It looks like bug 757676 implemented based on a document that was at that
> point 3 years out of date...

SpiderMonkey doesn't support non-trailing default parameters not because the wiki said it was banned but because at the time we thought the semantics might change or they might even end up being banned. (I asked dherman one or two pointed questions about them and got a definite "don't implement that".)

We haven't looked at it since, but should.

Comment 2

[Brandon Benvie [:benvie]]

Pretty sure this is a dupe of bug 777060.

Comment 3

[Boris Zbarsky [:bzbarsky]]

If that's the only difference we have, then yes.

Comment 4

[Brandon Benvie [:benvie]]

Good point; I think it's not. The following should be valid but isn't accepted by SpiderMonkey:

> function x({ a } = { a: 10 }){}
>> SyntaxError: missing ) after formal parameters

Comment 5

[Jason Orendorff [:jorendorff]]

The remaining stuff falls under bug 1283482, so I'm duping this forward.