Re: Cleaning up multiply-defined-symbol warnings on OS X

Martijn van Oosterhout <kleptog@svana.org> writes:
> Eh? It stops a program expecting libpq4 being linked to libpq3 for any
> reason, so the above situation can't happen. You don't need to version
> any structs, only the functions using them.

If we have an existing app built against an unversioned libpq, what
happens if we roll in a versioned libpq?  Does it break completely?
That is, is the introduction of versioning by itself an incompatible
ABI break?

            regards, tom lane