SIZE_MAX could be defined as -1 promoted to an unsigned type, meaning that
the unsigned comparison would always yield false. Or am I missing something?
In any case, if the promotion is what is intended, 'nbytes' should be
probably replaced with '(size_t) nbytes' to silence the warning and to make
it explicit.
Am So., 4. Apr. 2021 um 08:24 Uhr schrieb Jeffrey Walton <noloa...@gmail.com
>:
> On Sun, Apr 4, 2021 at 2:17 AM Marc Nieper-Wißkirchen
> <marc.nieper+...@gmail.com> wrote:
> >
> > GCC prints the following warning when compiling the new code:
> >
> > lib/xmalloc.c: In function 'xpalloc':
> > lib/xmalloc.c:132:64: warning: comparison of integer expressions of
> different signedness: 'long unsigned int' and 'idx_t' {aka 'long int'}
> [-Wsign-compare]
> > 132 | = ((INT_MULTIPLY_WRAPV (n, item_size, &nbytes) || SIZE_MAX <
> nbytes)
> >
> > If I understand the error message correctly, it is because 'nbytes' is a
> signed type while SIZE_MAX is unsigned.
> >
> > Does the comparison make any sense, by the way?
>
> Only for positive integers.
>
> If idx_t is negative, like -1, then -1 will be promoted to an unsigned
> type and then -1 > 0.
>
> Jeff
>
