1140854 - Function.prototype.toString throws when called on Proxy

Status: RESOLVED INVALID

(Core :: JavaScript Engine, defect)

Description

[vladsv88]

User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/40.0.2214.115 Safari/537.36

Steps to reproduce:

This code throws a exception on Firefox 38a2:

var f1 = function() { };
var f2 = new Proxy(f1, { });
f2.toString(); // throws exception


Actual results:

TypeError: Function.prototype.toString called on incompatible object


Expected results:

function() { }

Comment 1

[Loic]

regression range:
good=2015-01-31
bad=2015-02-01
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=d7e156a7a0a6&tochange=c2359a6a6958

Tom Schuster — Bug 1100936 - Handle various operations on revoked proxies. r=efaust

Not sure if it's a valid regression anyway. CC'ed Tom.

Comment 2

[Tom S. (please needinfo tschuster)]

This was a conscious decision, the ES6 spec doesn't allow this kind of unwrapping behavior.
https://people.mozilla.org/~jorendorff/es6-draft.html#sec-function.prototype.tostring: Proxies are neither a bound function nor do they have an [[ECMAScriptCode]] internal slot. They just have [[Call]].