730139 - Try making 'let' a reserved word

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, defect)

Description

[Jason Orendorff [:jorendorff]]

'let' is reserved in strict mode. JSCore currently reserves 'let' even in non-strict code (on an experimental basis).

We should join in the experiment.

Comment 1

[Mozilla RelEng Bot]

Try run for 32ea63fd558b is complete.
Detailed breakdown of the results available here:
    https://tbpl.mozilla.org/?tree=Try&rev=32ea63fd558b
Results (out of 2 total builds):
    exception: 2
Builds (or logs if builds failed) available at:
http://ftp.mozilla.org/pub/mozilla.org/firefox/try-builds/[e-mail]-32ea63fd558b

Comment 2

[Mozilla RelEng Bot]

Try run for 4d3dbe17bf5f is complete.
Detailed breakdown of the results available here:
    https://tbpl.mozilla.org/?tree=Try&rev=4d3dbe17bf5f
Results (out of 23 total builds):
    success: 10
    warnings: 13
Builds (or logs if builds failed) available at:
http://ftp.mozilla.org/pub/mozilla.org/firefox/try-builds/[e-mail]-4d3dbe17bf5f

Comment 3

[Mozilla RelEng Bot]

Try run for 52b550e6b0f7 is complete.
Detailed breakdown of the results available here:
    https://tbpl.mozilla.org/?tree=Try&rev=52b550e6b0f7
Results (out of 24 total builds):
    success: 22
    warnings: 2
Builds (or logs if builds failed) available at:
http://ftp.mozilla.org/pub/mozilla.org/firefox/try-builds/[e-mail]-52b550e6b0f7

Comment 4

[Jason Orendorff [:jorendorff]]

Attachment: v1

This is Adam's patch. I will be reviewing and pushing it in the next couple of hours.

Comment 5

[Jason Orendorff [:jorendorff]]

Comment on attachment 604038 [details] [diff] [review]
v1

Review of attachment 604038 [details] [diff] [review]:
-----------------------------------------------------------------

r=me with one change, noted below.

I'll make the change and push it in a few hours.

::: js/src/tests/ecma_5/misc/future-reserved-words.js
@@ -27,5 @@
>  var strictFutureReservedWords =
>    [
>     "implements",
>     "interface",
> -   "let", // enabled: this file doesn't execute as JS1.7

Looking at what this test actually does, I think "let" should be moved to futureReservedWords rather than simply deleted. And there should definitely be a comment noting that in doing so we're departing from ES5 (in an attempt to make ES6 better).

Comment 6

[Marco Bonardo [:mak]]

https://hg.mozilla.org/mozilla-central/rev/6d139ebc0f43

Comment 7

[Jeff Walden [:Waldo]]

Given this was backed out in bug 738908, I think there's nothing to document here.