582162 - assignment needs to ignore the setter's result

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Luke Wagner [:luke]]

Attachment: fix

This was regressed by fatval which passes &regs.sp[x] instead of passing the address of a copy to setProperty.

Comment 1

[Brendan Eich [:brendan]]

Comment on attachment 460437 [details] [diff] [review]
fix

Whew! Thanks to adrake for noticing, Waldo for escalating, and Luke for patching. A trace-test is enough in my book but a purist might want an ecma_1 jsreftest.

/be

Comment 2

[Brendan Eich [:brendan]]

This was covered (badly) by ACID3, before we optimized JSOP_LENGTH, Waldo says.

/be

Comment 3

[Jeff Walden [:Waldo]]

In fairness to Acid3, I'm not sure there's any other property native to ECMAScript-262, 3rd ed. which has this sort of magical coerc-y behavior upon setting (and ES5 was out because of the self-imposed restriction to long-standardized functionality).  From what I can tell only Array had a magical [[Put]] implementation which did anything other than set to the provided value.  /a/.lastIndex comes close, but ES3 underspecified it enough that it's better the exact spec language wasn't lawyered into something convolutedly semi-self-consistent.  The E4X examples here are out for obvious reasons.  And ES5 getters and setters using either literal or programmatic syntax didn't even exist at that point in a standard, or their semantics were yet far from being worked out.

It hadn't occurred to me that length wasn't optimized when bug 312354 was fixed -- an example for people writing tests of why tests should address both general (some random property name, in concert with our then-extension-land setters) and specific cases (like length as Acid3 exercised) rather than the narrow bit suggested by a testcase.

Comment 4

[Brendan Eich [:brendan]]

Hah! if Hixie could test SMIL in Acid3, then E4X was fair game too.

Good point about generalized or wide-field-of-fire tests.

/be

Comment 5

[Luke Wagner [:luke]]

http://hg.mozilla.org/tracemonkey/rev/8ad1738e14f5

Comment 6

[Robert Sayre]

http://hg.mozilla.org/mozilla-central/rev/8ad1738e14f5