Different gettext domain needed for error context

I just noticed that we use the same gettext domain for all messages
attached to one error. That is wrong in case of context information,
where you have a stack of context lines, originating from different
modules. The result is that context lines don't always get translated.

For example:

postgres=# set lc_messages ='de_DE.utf8';
SET
postgres=# do $$
begin
select 1 / 0;
end
$$;
FEHLER: Division durch Null
CONTEXT: SQL-Anweisung »select 1 / 0«
PL/pgSQL function "inline_code_block" line 3 at SQL-Anweisung

Notice how the string "PL/pgSQL function ..." is not translated. The
ereport call that raises that error is in int4div, which is in the
backend gettext domain, "postgres". But the errcontext() call comes from
pl_exec.c.

If the error originates from src/pl/plpgsql, then it works:

postgres=# do $$
begin
raise;
end
$$;
FEHLER: RAISE ohne Parameter kann nicht außerhalb einer
Ausnahmebehandlung verwendet werden
CONTEXT: PL/pgSQL-Funktion »inline_code_block« Zeile 3 bei RAISE

In theory, I guess the other fields like errhint() potentially have the
same problem, but they're not currently used to provide extra
information to messages originating from another module, so I'm inclined
to leave them alone for now.

To fix this, we need to somehow pass the caller's text domain to
errcontext(). The most straightforward way is to pass it as an extra
argument. Ideally, errcontext() would be a macro that passes TEXTDOMAIN
to the underlying function, so that you don't need to change all the
callers of errcontext():

#define errcontext(...) errcontext_domain(TEXTDOMAIN, ...)

But that doesn't work, because it would require varags macros. Anyone
know a trick to make that work?

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com