From: Tom Lane <tgl@sss.pgh.pa.us>
To: Antonin Houska <ah@cybertec.at>
cc: Tomas Vondra <tomas@vondra.me>, Alvaro Herrera <alvherre@alvh.no-ip.org>,
        vignesh C <vignesh21@gmail.com>,
        Srinath Reddy Sadipiralla <srinath2133@gmail.com>,
        Amit Kapila <amit.kapila16@gmail.com>,
        Mihail Nikalayeu <mihailnikalayeu@gmail.com>,
        Matthias van de Meent <boekewurm+postgres@gmail.com>,
        Pg Hackers <pgsql-hackers@lists.postgresql.org>,
        Robert Treat <rob@xzilla.net>
Subject: Re: Adding REPACK [concurrently]
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Comments: In-reply-to Antonin Houska <ah@cybertec.at>
	message dated "Wed, 08 Apr 2026 12:46:46 +0200"
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Date: Wed, 08 Apr 2026 12:47:33 -0400
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Antonin Houska <ah@cybertec.at> writes:
> Tomas Vondra <tomas@vondra.me> wrote:
>> while building on a rpi5 with a 32-bit system, I'm getting these warnings:
>> ...
>> I'm not sure if it's just the compiler (gcc 14.2) being pesky, or if
>> it's an actual issue. The repack tests seem to pass fine.

Several 32-bit BF animals are showing these too (so far: dodo,
grison, and turaco).

> We already introduced this definition above in the function to suppress this
> kind of warning

>     union
>     {
> 	    alignas(int32) varlena hdr;
> 	    char		data[sizeof(void *)];
>     }			chunk_header;

> The problem on a 32-bit system probably is that sizeof(void *) is 4. We need
> some other constant. Maybe (sizeof(varlena) + 1) ...

This seems unnecessarily Rube Goldberg-ish already.  Why not just

	uint64	chunk_header;

It will not hurt anything if the variable has more-than-required
alignment.  And it'd be better if it were the same size everywhere.

			regards, tom lane