Library major version changes

[Jim Hatfield]

This seems to be one of the few nightmare areas for
upgrading. I see in /usr/ports/UPDATING:

>portupgrade -rf textproc/expat2

This little phrase hides a lot of potential anguish!
Apart from the time involved (2 days for a machine with
not much grunt and a lot of packages installed) there
are all the knock-on effects.

I've just tried this on a Web server which has PHP4
and freetds installed. It appears that libsybdb has
also had a major version change, from libsybdb.so.3
to libsybdb.so.4, though the package version has
only changed from freetds-0.61.2 to freetds-0.62_1.

Sadly, it does not build (on 5.1):

>===>  Configuring for freetds-0.62_1
>configure.in:40: error: possibly undefined macro: AC_GNU_SOURCE
>*** Error code 1
>
>Stop in /usr/ports/databases/freetds.

Which leaves me with (potentially) installed applications
which depend on libexpat.so.4, which no longer exists.

I'm afraid to do *anything* to this machine now, in case 
stopping, say, the apache server means it won't start again.

jim