"unable to detect exception model"

[Benjamin Kosnik]

> What I'm doing wrong?? It is really impossible to build a working
> libstdc++-v3 without the new exception model?? In other terms: it is
> presently impossible to test a new incarnation of libstdc++-v3 by using
> "only" Gcc3.0 ??

Short answer: yes.

Long answer: not easily.

The libsupc++ bits are pretty tied to gcc-3.1 (CVS head) until the 
call-frame exception handling bits get merged in. 

What you can try is using the old libsupc++ (in libstdc++-v3/libsupc++) 
on the gcc-3 branch with the rest of the libstdc++-v3 from gcc-3.1 or 
libstdc++-2.92.

Sounds kind of frankenstein-ish, and it is. We need to merge in to gcc-3 
branch with this stuff. 

-benjamin