From: Omar Polo <op@omarpolo.com>
Subject: Re: got patch: add flag to ignore whitespace?
To: Christian Weisgerber <naddy@mips.inka.de>
Cc: gameoftrees@openbsd.org
Date: Sun, 03 Jul 2022 15:31:15 +0200

Christian Weisgerber <naddy@mips.inka.de> wrote:
> Stefan Sperling:
> 
> > Actually, all the ctype functions need a cast to unsigned char, like
> > this: isspace((unsigned char)ch);
> > 
> > I don't recall why, but there was a sweep throughout the entire
> > OpenBSD tree at some point to add such casts.
> 
> The is*() functions take an int argument, which may have the value
> of any char and additionally EOF.  The idea seems to be that you
> can feed the return value of, say, getchar() to is*().
> 
> On architectures like x86 where char is signed by default, passing
> a char to an int parameter will sign-extend the value.  In particular,
> a char with value 0xff will turn into 0xffffffff, which is -1, which
> is typically the value of EOF.  Oops.

woops, I see the issue now.  Thanks for the clarification! :)