Re: [PATCH] bms_prev_member() can read beyond the end of the array of allocated words

On Fri, 15 Aug 2025 at 15:24, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> David Rowley <dgrowleyml(at)gmail(dot)com> writes:
> > I'm happy to push Greg's v5 patch if you have no counterarguments.
>
> In the end this isn't something I find worth arguing about. If
> you prefer v5, sure. I do suggest though that if we're installing
> Asserts at all, defending against prevbit < -1 is worth doing.

Agreed about defending against prevbit < -1. I added an Assert for
that. Technically, that Assert could be up above the if (a == NULL)
check, but I didn't think it mattered that much and opted to keep both
Asserts together. The difference being that bms_prev_member(NULL, -2)
will return -2 rather than Assert fail. I'm not too worried about
that, but if you feel strongly differently, I can adjust what I just
pushed.

David