1133298 - 'arguments' is allowed even with rest-parameters

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[ziyunfei]

js> (function(...args){return arguments})(1,2,3)
SyntaxError: 'arguments' object may not be used in conjunction with a rest parameter // should be { "0": 1, "1": 2, "2": 3 }

Comment 1

[Jeff Walden [:Waldo]]

This is what the spec says, but I still have hopes of arguing people away from this.  There's no good reason to have this doubling of work (...in the cases that can't be optimized away, at least), and at least a few reasons against -- particularly, that with a rest parameter the aliasing of parameters and arguments[i] indexes (when at least that many arguments are passed) becomes somewhat non-obvious (although I don't know if the spec handles it unambiguously or not).  So I think we should hold the fire on this one for at least a moment.

Comment 2

[Jan de Mooij [:jandem]]

Fixed by bug 889158. There's still bug 1175394 though but that's a separate issue.

Comment 3

[Florian Scholz (Open Web Docs)]

Review appreciated.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/arguments#Rest_default_and_destructured_parameters
https://developer.mozilla.org/en-US/Firefox/Releases/43#JavaScript

Comment 4

[Jan de Mooij [:jandem]]

(In reply to Florian Scholz [:fscholz] from comment #3)
> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/
> arguments#Rest_default_and_destructured_parameters
> https://developer.mozilla.org/en-US/Firefox/Releases/43#JavaScript

Thanks for updating the docs for all those bugs.