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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Melanie Plageman <melanieplageman@gmail.com>
cc: Andres Freund <andres@anarazel.de>,
        Kyotaro Horiguchi <horikyota.ntt@gmail.com>, vignesh21@gmail.com,
        pryzby@telsasoft.com, lukas@fittl.com, alvherre@alvh.no-ip.org,
        magnus@hagander.net, pgsql-hackers@postgresql.org,
        thomas.munro@gmail.com, m.sakrejda@gmail.com
Subject: Re: pg_stat_bgwriter.buffers_backend is pretty meaningless (and more?)
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Comments: In-reply-to Melanie Plageman <melanieplageman@gmail.com>
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Date: Mon, 27 Feb 2023 14:58:30 -0500
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Melanie Plageman <melanieplageman@gmail.com> writes:
> On Mon, Feb 27, 2023 at 10:30=E2=80=AFAM Tom Lane <tgl@sss.pgh.pa.us> wr=
ote:
>> The risk of needing to cast when using the "int" loop variable
>> as an enum is obviously the downside of that approach, but we have
>> not seen any indication that any compilers actually do warn.
>> It's interesting that you did see such a warning ... I wonder which
>> compiler you were using at the time?

> so, pretty much any version of clang I tried with
> -Wsign-conversion produces a warning.

> <source>:35:32: warning: implicit conversion changes signedness: 'int'
> to 'IOOp' (aka 'enum IOOp') [-Wsign-conversion]

Oh, interesting --- so it's not about the implicit conversion to enum
but just about signedness.  I bet we could silence that by making the
loop variables be "unsigned int".  I doubt it's worth any extra keystrokes
though, because we are not at all clean about sign-conversion warnings.
I tried enabling -Wsign-conversion on Apple's clang 14.0.0 just now,
and counted 13462 such warnings just in the core build :-(.  I don't
foresee anybody trying to clean that up.

> I didn't do the casts in the attached patch since they aren't done elsew=
here.

Agreed.  I'll push this along with the earlier patch if there are
not objections.

			regards, tom lane