1893492 - Function.prototype.toString should print set / get for accessor properties

Status: NEW

(Core :: JavaScript: Standard Library, defect, P3)

Description

[Thomas Wisniewski [:twisniewski][PTO until the 26th]]

WebKit just addressed this in this commit, citing https://tc39.es/ecma262/#sec-function.prototype.tostring

For instance, try Object.getOwnPropertyDescriptor(Map.prototype, "size").get.toString().
In Firefox:

function size() {
    [native code]
}

In WebKit 193:

function get size() {
    [native code]
}

Comment 1

[Jan de Mooij [:jandem]]

https://github.com/tc39/ecma262/pull/1948

We currently skip the get or set prefix explicitly. Just not doing that seems to be sufficient to fix this?

Comment 2

[Jan de Mooij [:jandem]]

Attachment: WIP: Bug 1893492 - Don't skip get/set prefix for Function.prototype.toString.

Comment 3

[André Bargull [:anba]]

(In reply to Jan de Mooij [:jandem] from comment #1)

https://github.com/tc39/ecma262/pull/1948

We currently skip the get or set prefix explicitly. Just not doing that seems to be sufficient to fix this?

The spec doesn't actually require that the accessor prefix is part of the output:

• Per Function.prototype.toString the output must contain func.[[InitialName]].
• Per SetFunctionName, [[InitialName]] of built-in functions can optionally include the accessor prefix:

Optionally, set F.[[InitialName]] to name.

Comment 4

[Dan Minor [:dminor]]

It looks Safari ran into repeated web compat problems by shipping this change: https://github.com/tc39/ecma262/issues/3652.

Comment 5

[Dan Minor [:dminor]]

It seems like we're currently compatible with the spec (setting the prefix is optional), but it sounds like the spec may change to require setting the prefix (possibly with the exception of a list of accessors provided in Annex B).

Given the problems Safari encountered, we should be careful about making changes here. On the TC39 call, Safari indicated it took 6 months for them to get broken site reports.