1023609 - Remove SpiderMonkey support for let expressions

Status: VERIFIED FIXED

(Core :: JavaScript Engine, defect)

Description

[Shu-yu Guo [:shu]]

ES6 does not spec let blocks and let expressions. We should remove them.

Comment 1

[Chris Peterson [:cpeterson]]

Attachment: part-1-remove-let-extension-tests.patch

Part 1: Remove SpiderMonkey tests for nonstandard let expressions.

This patch removes fuzz tests that use let expressions and updates functional tests to not use let expressions.

Comment 2

[Chris Peterson [:cpeterson]]

Attachment: part-2-remove-let-extension-code.patch

Part 2: Remove SpiderMonkey support for nonstandard let expressions.

This patch removes let expressions, but leaves let blocks for now. This work was easier to do in separate steps.

Comment 4

[Shu-yu Guo [:shu]]

Comment on attachment 8607350 [details] [diff] [review]
part-1-remove-let-extension-tests.patch

Review of attachment 8607350 [details] [diff] [review]:
-----------------------------------------------------------------

Wondrous removal

Comment 5

[Shu-yu Guo [:shu]]

Comment on attachment 8607351 [details] [diff] [review]
part-2-remove-let-extension-code.patch

Review of attachment 8607351 [details] [diff] [review]:
-----------------------------------------------------------------

Wondrous removal.

::: js/src/frontend/Parser.cpp
@@ +8106,2 @@
>           *   }
> +         *   array

Nit: could you change the pseudocode to

{
  let array = new Array, i, j;
  ...
  array
}

That is, add an extra pair of { } around everything. Otherwise it looks like we're introducing new bindings into an existing block scope.

Comment 6

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/fc18eefd9329

Comment 7

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/fc18eefd9329

Comment 8

[Tooru Fujisawa [:arai]]

Updated following documents:
  https://developer.mozilla.org/en-US/Firefox/Releases/41
  https://developer.mozilla.org/en-US/docs/Web/JavaScript/New_in_JavaScript/1.7
  https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let#let_expressions

Comment 9

[Chris Peterson [:cpeterson]]

(In reply to Tooru Fujisawa [:arai] from comment #8)
> Updated following documents:

Thanks, Tooru! :)

Comment 10

[Florian Scholz (Open Web Docs)]

Also in site-compat doc now. Thanks, everyone!
https://developer.mozilla.org/en-US/Firefox/Releases/41/Site_Compatibility#JavaScript

Comment 11

[Florian Bender]

Does this mean SM is now ES6-spec-compliant wrt let?

Comment 12

[Chris Peterson [:cpeterson]]

(In reply to Florian Bender from comment #11)
> Does this mean SM is now ES6-spec-compliant wrt let?

Not yet. There are some remaining let issues described in tracking bug 950547.

Comment 13

[Florian Bender]

Yeah, sorry, forgot about that one.