Re: Adding REPACK [concurrently]

Tomas Vondra <tomas(at)vondra(dot)me> 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