On Wed, Feb 02, 2022 at 01:23:44PM -0700, Jeff Law via Gcc-patches wrote:
> Note that I think something similar may be needed to mark EOL for the
> pointer passed to realloc to fix a related set of false positives for code
> like this
>
> bool something = p != q;
> whatever = realloc (p, newsize)
> if (something)
>
> We forward propagate the p != q test generating something like this;
>
> whatever - realloc (p, newsize);
> if (p != q)
IMNSHO we shouldn't warn for pointer passed to realloc being used in
equality comparisons at all, it is just unnecessarily pedantic, it works
just fine and a lot of programs use it to find out if the memory was
actually reallocated or was just extended or shrunk in place; in the former
case they often need some extra work, such as adjust something in the memory
block.
Yes, one can probably do
uintptr_t pint = (uintptr_t) p;
whatever = realloc (p, newsize);
if ((uintptr_t) whatever != pint)
but I think most people don't bother.
Jakub
