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From: Antonin Houska <[email protected]>
To: Tomas Vondra <[email protected]>
Cc: Alvaro Herrera <[email protected]>
Cc: vignesh C <[email protected]>
Cc: Srinath Reddy Sadipiralla <[email protected]>
Cc: Amit Kapila <[email protected]>
Cc: Mihail Nikalayeu <[email protected]>
Cc: Matthias van de Meent <[email protected]>
Cc: Pg Hackers <[email protected]>
Cc: Robert Treat <[email protected]>
Subject: Re: Adding REPACK [concurrently]
Date: Wed, 08 Apr 2026 12:46:46 +0200
Message-ID: <19118.1775645206@localhost> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
	<[email protected]>

Tomas Vondra <[email protected]> wrote:

> while building on a rpi5 with a 32-bit system, I'm getting these warnings:
> 
> config.status: linking src/makefiles/Makefile.linux to src/Makefile.port
> In file included from ../../../src/include/access/tupmacs.h:20,
>                  from ../../../src/include/access/htup_details.h:20,
>                  from ../../../src/include/access/relscan.h:17,
>                  from ../../../src/include/access/heapam.h:19,
>                  from repack.c:36:
> In function ‘VARSIZE_ANY’,
>     inlined from ‘restore_tuple’ at repack.c:2731:15:
> ../../../src/include/varatt.h:243:51: warning: array subscript
> ‘varattrib_4b[0]’ is partly outside array bounds of ‘union
> <anonymous>[1]’ [-Warray-bounds=]
>   243 |         ((((const varattrib_4b *) (PTR))->va_4byte.va_header >>
> 2) & 0x3FFFFFFF)
>       |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~
> ../../../src/include/varatt.h:467:24: note: in expansion of macro
> ‘VARSIZE_4B’
>   467 |                 return VARSIZE_4B(PTR);
>       |                        ^~~~~~~~~~
> repack.c: In function ‘restore_tuple’:
> repack.c:2717:49: note: object ‘chunk_header’ of size 4
>  2717 |                         }                       chunk_header;
>       |                                                 ^~~~~~~~~~~~
> In function ‘VARSIZE_ANY’,
>     inlined from ‘restore_tuple’ at repack.c:2734:4:
> ../../../src/include/varatt.h:243:51: warning: array subscript
> ‘varattrib_4b[0]’ is partly outside array bounds of ‘union
> <anonymous>[1]’ [-Warray-bounds=]
>   243 |         ((((const varattrib_4b *) (PTR))->va_4byte.va_header >>
> 2) & 0x3FFFFFFF)
>       |           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~
> ../../../src/include/varatt.h:467:24: note: in expansion of macro
> ‘VARSIZE_4B’
>   467 |                 return VARSIZE_4B(PTR);
>       |                        ^~~~~~~~~~
> repack.c: In function ‘restore_tuple’:
> repack.c:2717:49: note: object ‘chunk_header’ of size 4
>  2717 |                         }                       chunk_header;
>       |                                                 ^~~~~~~~~~~~

> 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.

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) ...

Thanks.

-- 
Antonin Houska
Web: https://www.cybertec-postgresql.com





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