need for flag for incompatible-changes

[Paul Koning]

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

 >> I wonder about the comment that even GNU ld often would only be
 >> able to say "sorry, incompatible object files".  Some things, like
 >> naming (namespace support) clearly aren't like that.

 Joe> We not only plan to add namespace support to the compiler, but
 Joe> we then need to redo libstdc++ to put the whole standard library
 Joe> in the std namespace.  That's what breaks compatibility, and it
 Joe> doesn't show up at the level of object file version -- it is a
 Joe> change in the API.  

Then maybe you need more version numbers.

Clearly, if the names of the functions change (due to namespaces) but
their calling conventions did not (same argument types etc.) then the
linker can map old names to new names if it is told to do so.

	paul