Re: warn if GUC set to an invalid shared library

Maciek Sakrejda <m.sakrejda@gmail.com> writes:
> In v4, the message looks fine to me for shared_preload_libraries
> (except there is a doubled "is"). However, I also get the message for
> a simple SET with local_preload_libraries:

> postgres=# set local_preload_libraries=xyz;
> WARNING:  could not access file "xyz"
> HINT:  The server will fail to start with the existing configuration.
> If it is is shut down, it will be necessary to manually edit the
> postgresql.auto.conf file to allow it to start.
> SET

I agree with Maciek's concerns about these HINTs being emitted
inappropriately, but I also have a stylistic gripe: they're only
halfway hints.  Given that we fix things so they only print when they
should, the complaint about the server not starting is not a hint,
it's a fact, which per style guidelines means it should be errdetail.
So I think this ought to look more like

WARNING:  could not access file "xyz"
DETAIL:  The server will fail to start with this setting.
HINT:  If the server is shut down, it will be necessary to manually edit the
postgresql.auto.conf file to allow it to start again.

I adjusted the wording a bit too --- YMMV, but I think my text is clearer.

            regards, tom lane