linux libio solution

[Per Bothner]

> Only on linux that is not possible. 
> You are always forced to upgrade libc.

That should not be true, and I don't think it really is.
It is just that people have not put the effort needed
to make it easy to upgrade libstdc++ without also
upgrading libc.  H.J.Lu, who has made the Linux libc and
g++ releases in the past has not seen that as a priority.
Ulrich (who is making current glibc releases), also seems
to not see it as a priority.  I tend to think that it is
important to get this to work for egcs releases.  It is not
necessarily a show-stopper (it is OK to require people to
upgrade libc if the alternative is too much work), but if
there is a reasonable solution (and there seems to be), we
should make it work.

> Upgrading libc even between minor levels has
> caused much problems in the past.
> All libg++ releases did not work unmodified for Linux. 

I agree this is not good.  The basic general solution is some variant
of what Richard Henderson proposed:  Provide a way to install iostreams,
with its private working copy of the libio code.  In some cases,
we can do better than that, which is what H.J.Lu is working on.

	--Per Bothner
Cygnus Solutions     bothner@cygnus.com     http://www.cygnus.com/~bothner