From:  Alex Webster <awebsterspc@gmail.com>
Date:  29 Dec 2016 01:51:36 Hong Kong Time
Newsgroup:  news.mozilla.org/mozilla.dev.tech.js-engine.internals
Subject:  

Re: Value::isGCThing now does what you'd expect

NNTP-Posting-Host:  63.245.214.181

Thanks,
Tom

On Tue, Dec 27, 2016 at 4:12 AM, Jan de Mooij  wrote:

> Hey all,
>
> I landed a JS::Value change that might affect some embedders. JS::Value
> used to have the following methods:
>
> * isMarkable(): returned true iff the Value was a GC thing (object, string,
> symbol, private GC thing).
> * isGCThing(): returned true if isMarkable() *or NullValue*.
>
> Unsurprisingly, most callers of isGCThing actually wanted isMarkable (we
> had some DOM code for instance where we took a slower path if isGCThing()
> returned true).
>
> Bug 1325075 [0] (in Firefox/SpiderMonkey 53) fixed this footgun. Now
> there's just isGCThing and it returns true iff the Value is a GC thing. The
> isMarkable and toMarkablePointer methods are gone.
>
> Thanks,
> Jan
>
> [0] https://bugzilla.mozilla.org/show_bug.cgi?id=1325075
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