need for flag for incompatible-changes

[Paul Koning]

>>>>> "Joe" == Joe Buck <jbuck@synopsys.com> writes:

 >> Keep in mind when you make abi changes in the compiler, that some
 >> things are distributed as binary-only (e.g. Motif) and thus
 >> *cannot* be recompiled by end users.  Motif is undoubtedly C code,
 >> so perhaps less of a problem, but there are undoubtedly a bunch of
 >> binary-only C++ libraries out there too.

 Joe> Up until now, we've made no effort to keep binary-only C++
 Joe> libraries running.  We will have to break them again, at least
 Joe> one more time, to implement namespaces.  We may want to attempt
 Joe> to figure out all the things we may break and try to do them
 Joe> only once; if we don't want a permanent fork that will have to
 Joe> be coordinated with gcc2.

If object files contained version numbers, you wouldn't have to break
anything.  (More precisely, you would only have to break things that
are older than the oldest version you want to continue supporting in
the linker.)

	paul