[Bug c++/61421] Invalid -O2 optimization breaks program

[mimamer at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61421

--- Comment #5 from mimamer at gmail dot com ---
T is derived from list2<T>::node, and yes, I'm "up"casting from node to T.
There is no other way around it in the implementation, and if this causes a
problem with aliasing then I don't know what it's good for. Any input
appreciated.