980181 - Rooting analysis false positive in TryPreserveWrapper

Status: RESOLVED WORKSFORME

(Core :: JavaScript: GC, defect)

Description

[Kyle Huey (Exited; not receiving bugmail, old account, do not use)]

The analysis is getting confused by the QI here, I think.  bz says you can annotate this away somehow.

Comment 1

[Steve Fink [:sfink] [:s:]]

The stack is:

GC Function: _ZN7mozilla3dom18TryPreserveWrapperEP8JSObject|uint8 mozilla::dom::TryPreserveWrapper(JSObject*)
void nsWrapperCache::PreserveWrapper(nsISupports*)
FieldCall: nsISupports.QueryInterface 

I can't really whitelist QI. Nor do I want to detect the specific interface you're QI'ing to and start whitelisting individual interfaces.

I could whitelist nsWrapperCache::PreserveWrapper. But I know nothing about it, and when I do a dxr search, it comes up with lots and lots of hits for PreserveWrapper (including a scary-looking PreserveWrapperCallback thing). Maybe they're unrelated.

You're sure it's ok? If so, I'm still inclined to do it via an AutoAssertNoGC RAII helper -- then I won't need to modify the analysis, and it'll assert if you lied to me.

Comment 2

[Jon Coppeard (:jonco)]

I guess this got fixed one way or another.