Qt build with gcc 4.6 in Qt Declarative seems to lead to a crash. No issue with gcc 4.5

In ubuntu Oneiric, we have our default compiler to gcc 4.6.
We are using the same compiler flag than in natty: https://wiki.ubuntu.com/CompilerFlags

Here is a stacktrace we get with unity-2d (with the dash view using qml)
https://bugs.launchpad.net/ubuntu/oneiric/+source/qt4-x11/+bug/791213
I've attached the retrace to this bug as well.

Rebuilding in oneiric with gcc 4.5 doesn't get the crash, any hint on where gcc (or maybe Qt) fails on the compiled version with gcc 4.6 only?

If you need any other information, do not hesitate to ask for them