Re: CVS commit: src/share/mk

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

On Thu, Aug 03, 2023 at 13:33:27 +0000, Rin Okuyama wrote:

> -Wuse-after-free for GCC 12 is premature. It fires on a common idiom:
> 
> 	newbuf = realloc(buf, size);
> 	p = newbuf + (p - buf);
>
> Let shut this up for GCC 12 (with hoping it gets improved for 13!).

C99 says

       J.2  Undefined behavior

       [#1]   The   behavior   is   undefined   in   the  following
       circumstances:
[...]
         -- The  value of a pointer to an object whose lifetime has
            ended is used (6.2.4).


Yes, for the "obvious" implementation of pointers as addresses the
above idiom happens to work, but it doesn't make that idiom any less
UB.

-uwe