virtual inheritance: optimization for empty objects

[Martin v. Loewis]

> Which libstdc++ is better to use? The newest broken one or the oldest
> incompatible one?  Or even something in between?

That very much depends on what you want to use it for. If you want to
develop applications, use the one that comes with the compiler. 

If you want to check standards-compliance, report bugs, and provide
fixes, by any means, please use the newest broken one :-)

Regards,
Martin