isascii(3) macros and casts

[Alejandro Colomar]

Hi Paul,

On Wed, Dec 11, 2024 at 09:50:30PM +0100, Alejandro Colomar wrote:
> On Wed, Dec 11, 2024 at 12:42:13PM -0800, Paul Eggert wrote:
> > On 2024-12-11 12:38, Paul Eggert wrote:
> > >    #define isdigit(x) ((int) {x} - '0' <= 9u)
> > 
> > Oh, that should be
> > 
> >   #define isdigit(x) ((unsigned int) (int) {x} - '0' <= 9)
> 
> LGTM.
> 
> > 
> > to avoid problems with signed integer overflow.

On the other hand, calling isdigit() with anything that's not a valid
char or EOF (-1) is already UB (and IMO, should stay as UB), so the
first approach should be enough, no?

Cheers,
Alex


-- 
<https://www.alejandro-colomar.es/>
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