Re: Compile warnings in dbcommands.c building with meson

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.

--
Best regards,
Aleksander Alekseev