604971 - array.sort compare-function gets incorrect this

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Tom S. (please needinfo tschuster)]

Since the es5 and strict mode, "null" and "undefined" this is observable.
As defined by es5 compare function should get "null" as their |this| value;

Test:
[1, 2].sort(function () {
  "use strict";
  if (this === undefined)
    throw;
});

Comment 1

[Luke Wagner [:luke]]

Did you mean that the compare function should be passed undefined as |this|?  That's what I'm reading in 15.4.4.11:
 "Return the result of calling the [[Call]] internal method of comparefn passing undefined as the this value and with arguments x and y."

Regardless, the bug summary is correct: we are currently passing null instead of undefined.

Comment 2

[Tom S. (please needinfo tschuster)]

Right totally messed it up, but i originally meant the right thing.
Currently the compare-function gets "null" but it should be "undefined".

Comment 3

[Tom S. (please needinfo tschuster)]

Attachment: tescase

Comment 4

[Tom S. (please needinfo tschuster)]

Attachment: micro fix

Comment 5

[Jeff Walden [:Waldo]]

Comment on attachment 483856 [details] [diff] [review]
micro fix

Stealing, this micro-fix is easy enough.  Looks like I forgot about this instance of this-passing when I wrote the strict-this patches...

I'll push this into TM tomorrow morning.  I can imagine we might want this for the beta release, on the principle of avoiding pointless dups for a very obvious mistake in new functionality for anyone looking, but I'm not going to push it.

Comment 6

[Jeff Walden [:Waldo]]

http://hg.mozilla.org/tracemonkey/rev/eca897723e48

Comment 7

[Jeff Walden [:Waldo]]

(Thanks for the patch!)

Comment 8

[Robert Sayre]

http://hg.mozilla.org/mozilla-central/rev/eca897723e48