1083498 - Remove SpiderMonkey support for destructuring for-in (JS1.7-only language extension)

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Comment 1

[Chris Peterson [:cpeterson]]

Attachment: remove-js17-destructuring-for-in.patch

- Remove SpiderMonkey's nonstandard behavior for destructuring for…in loops in JS1.7.
- Stop collecting telemetry for destructuring for…in loops.
- Change js1_7 tests to expect JS1.8's destructuring for…in behavior.
- Also add two reportCompare() calls to js1_7/geniter/regress-345736.js that were presumably forgotten in https://hg.mozilla.org/mozilla-central/rev/b23162a81291.

Comment 2

[Jason Orendorff [:jorendorff]]

Comment on attachment 8582211 [details] [diff] [review]
remove-js17-destructuring-for-in.patch

Review of attachment 8582211 [details] [diff] [review]:
-----------------------------------------------------------------

Thank you!

::: js/src/tests/js1_7/geniter/regress-347593.js
@@ +21,5 @@
>    printStatus (summary);
> +
> +  // Before JS1.7's destructuring for…in was fixed to match JS1.8,
> +  // the expected result was simply '23'.
> +  expect = 'TypeError: (intermediate value)[Symbol.iterator](...).next(...).value is undefined';

It's better not to check exact error messages here. Just checking ex.name is fine.

Comment 3

[Chris Peterson [:cpeterson]]

Thanks!

https://hg.mozilla.org/integration/mozilla-inbound/rev/129deced715e

Comment 4

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/129deced715e

Comment 5

[Tooru Fujisawa [:arai]]

Updated following documents:
  https://developer.mozilla.org/en-US/Firefox/Releases/40
  https://developer.mozilla.org/en-US/docs/Web/JavaScript/New_in_JavaScript/1.7

Comment 6

[Florian Scholz (Open Web Docs)]

Also noted on https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment#Firefox-specific_notes