Re: Compile warnings in dbcommands.c building with meson

On Wed, Jan 10, 2024 at 1:16 PM Aleksander Alekseev
<aleksander(at)timescale(dot)com> wrote:
>
> Hi,
>
> > When building current head on debian bullseye I get this compile warning:
> >
> > In file included from ../src/backend/commands/dbcommands.c:20:
> > ../src/backend/commands/dbcommands.c: In function ‘createdb’:
> > ../src/include/postgres.h:104:9: warning: ‘src_hasloginevt’ may be
> > used uninitialized in this function [-Wmaybe-uninitialized]
> > 104 | return (Datum) (X ? 1 : 0);
> > | ^~~~~~~~~~~~~~~~~~~
> > ../src/backend/commands/dbcommands.c:683:8: note: ‘src_hasloginevt’
> > was declared here
> > 683 | bool src_hasloginevt;
> > | ^~~~~~~~~~~~~~~
> >
> >
> > I only get this when building with meson, not when building with
> > autotools. AFAICT, I have the same config:
> >
> > ./configure --enable-debug --enable-depend --with-python
> > --enable-cassert --with-openssl --enable-tap-tests --with-icu
> >
> > vs
> >
> > meson setup build -Ddebug=true -Dpython=true -Dcassert=true
> > -Dssl=openssl -Dtap-test=true -Dicu=enabled -Dnls=disabled
> >
> >
> > in both cases the compiler is:
> > gcc (Debian 10.2.1-6) 10.2.1 20210110
>
> Seems to me that the compiler is not smart enough to process:
>
> ```
> if (!get_db_info(dbtemplate, ShareLock,
> &src_dboid, &src_owner, &src_encoding,
> &src_istemplate, &src_allowconn, &src_hasloginevt,
> &src_frozenxid, &src_minmxid, &src_deftablespace,
> &src_collate, &src_ctype, &src_iculocale,
> &src_icurules, &src_locprovider,
> &src_collversion))
> ereport(ERROR, ...
> ```
>
> Should we just silence the warning like this - see attachment? I don't
> think createdb() is called that often to worry about slight
> performance change, if there is any.

Certainly looks that way, but I'm curious as to why nobody else has seen this..

That said, it appears to be gone in current master. Even though
nothing changed in that file. Must've been some transient effect,
that somehow didn't get blown away by doing a clean....

--
Magnus Hagander
Me: https://www.hagander.net/
Work: https://www.redpill-linpro.com/