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Date: Fri, 4 Oct 2019 11:56:31 +0200
From: Christoph Berg <myon@debian.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: pgsql: Remove pqsignal() from libpq's official exports list.
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Re: Tom Lane 2018-09-28 <E1g5vmT-0003K1-6S@gemulon.postgresql.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@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