Re: Bogus (intptr_t) casts

[Chet Ramey]

On 8/6/24 9:36 AM, Martin D Kealey wrote:
> Why just those ones? Mainly:
> (a) I'm looking at patching that area of the code for other reasons, so 
> they're the ones that I happened to encounter; and
> (b) I didn't want to over-cook it, so I only included the ones where I 
> could see that it was actually a pointer (casting a number to an intptr_t 
> doesn't result in UB).
>
> Other cases that involve casting a pointer to an intptr_t or uintptr_t, and 
> then comparing against a *numeric* zero should be similarly updated.

You didn't address the other part of my message. Since the pointers that
are in unwind-protects are the result of byte copies, not assignments, the
compiler's representation of NULL pointers isn't relevant.

> To my knowledge all current compilers use a numeric zero to represent 
> NULL,  but this is not guaranteed, and might change in the future.

It doesn't matter. The four (or eight) bytes in the (void *) that is cast
to an intptr_t are the result of copying the original four (or eight) bytes
in the int that's being saved.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/