[PATCH] malloc: fix undefined behavior in obstack.h [BZ #32393]

[Sam James]

Paul Eggert <eggert@cs.ucla.edu> writes:

> On 2025-04-28 20:39, Collin Funk wrote:
>
>> +# define PTR_UINT_TYPE __UINTPTR_TYPE__
>
> Let's call this new macro __PTR_UINT_TYPE instead, to avoid namespace
> pollution.
>
>
>> +#define __PTR_ALIGN(B, P, A) \
>> +  (sizeof (PTR_INT_TYPE) < sizeof (void *) \
>> +   ? (B) + (((P) - (B) + (A)) & ~(A))      \
>> +   : (P) + ((- (PTR_UINT_TYPE) (P)) & (A)))
>
> This collides with Gnulib, which needs to do this a different way to
> avoid a compiler error with Oracle Developer Studio. Although
> admittedly it'll take a bit of work to merge with Gnulib, let's not
> make merging harder.
>
> How about the attached patch instead?

I have something similar in a local copy of a sync for gcc I haven't
finished off:

Reviewed-by: Sam James <sam@gentoo.org>

(but I think Collin's was fine too, just your point is fair about not
making it harder to sync.)

>
> [2. text/x-patch; 0001-malloc-fix-undefined-behavior-in-obstack.h-BZ-32393.patch]...