Bug#751569: iceweasel: crashes on mcl-samar.com

[Mike Hommey]

On Sun, Jun 15, 2014 at 09:21:30AM +0900, Mike Hommey wrote:
> On Sun, Jun 15, 2014 at 02:02:44AM +0200, Vincent Lefevre wrote:
> > Control: tags -1 upstream
> > 
> > On 2014-06-15 08:16:12 +0900, Mike Hommey wrote:
> > > So, I was able to reproduce this crash... but not with 30.0-1. I
> > > reproduced with both 31.0~b1-1 and 32.0~a2+20140613004003-1.
> > > I did *not* reproduce with 31.0~b1-1~bpo70+1 from mozilla.debian.net,
> > > or with upstream Firefox, and that may be indicating a compiler bug \o/
> > 
> > I could reproduce it with upstream Firefox 30.0, still on mcl-samar.com,
> > but not at Firefox startup, it was a bit later. Here's the crash report:
> > 
> > https://crash-stats.mozilla.com/report/index/d429af40-44c8-4b9a-acfe-62f9f2140614
> 
> That's not the same crash at all. The one with the debian build is
> because somehow there are no pointers to destructors in the vtable for
> TSymbol, which causes a crash in TSymbolTableLevel::~TSymbolTableLevel.

And the reason it does so is because TSymbol is an abstract class, and
gcc 4.9 stops emitting destructors in the vtable of abstract classes.
That shifts the question to why an object has that type.

Mike