Re: pgsql: Remove pqsignal() from libpq's official exports list.

Re: Tom Lane 2018-09-28 <E1g5vmT-0003K1-6S(at)gemulon(dot)postgresql(dot)org>
> Remove pqsignal() from libpq's official exports list.
>
> Client applications should get this function, if they need it, from
> libpgport.
>
> The fact that it's exported from libpq is a hack left over from before
> we set up libpgport. It's never been documented, and there's no good
> reason for non-PG code to be calling it anyway, so hopefully this won't
> cause any problems. Moreover, with the previous setup it was not real
> clear whether our clients that use the function were getting it from
> libpgport or libpq, so this might actually prevent problems.
>
> The reason for changing it now is that in the wake of commit ea53100d5,
> some linkers won't export the symbol, apparently because it's coming from
> a .a library instead of a .o file. We could get around that by continuing
> to symlink pqsignal.c into libpq as before; but unless somebody complains
> very hard, I don't want to adopt such a kluge.

This is starting to hurt in several places:

04 11:41 <magnush> mha(at)xindi:~$ psql
04 11:41 <magnush> /usr/lib/postgresql/9.2/bin/psql: symbol lookup error:
/usr/lib/postgresql/9.2/bin/psql: undefined symbol: pqsignal

pg_repack linked against libpq5 11 breaks with libpq5 12:

--- /tmp/autopkgtest-lxc.evololie/downtmp/build.XvF/src/regress/expected/repack-run.out 2018-10-18 11:30:46.000000000 +0000
+++ /tmp/autopkgtest-lxc.evololie/downtmp/build.XvF/src/regress/results/repack-run.out 2019-10-03 21:24:29.049576631 +0000
@@ -2,19 +2,8 @@
-- do repack
--
\! pg_repack --dbname=contrib_regression --table=tbl_cluster
-INFO: repacking table "public.tbl_cluster"
+pg_repack: symbol lookup error: pg_repack: undefined symbol: pqsignal

https://ci.debian.net/data/autopkgtest/testing/amd64/p/pg-repack/3070831/log.gz

Christoph