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From: Jonathan Wakely <jwakely.gcc@gmail.com>
Date: Wed, 27 Apr 2022 17:19:21 +0100
Message-ID: <CAH6eHdRN8a09+ivse7JRPDSG73hRFUbWnofLpwTJ9+Gd+BzdMQ@mail.gmail.com>
Subject: Re: No type checking in ctype builtins
To: Andrea Monaco <andrea.monaco@autistici.org>
Cc: "gcc@gcc.gnu.org" <gcc@gcc.gnu.org>
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On Wed, 27 Apr 2022 at 16:29, Andrea Monaco via Gcc <gcc@gcc.gnu.org> wrote:
>
>
> This program
>
>   #include <ctype.h>
>
>   int main ()
>   {
>     char *s;
>     isspace (s);
>   }
>
> compiles with no warning in gcc 8.3.0, even though there's a type
> mistake; the correct call would be isspace (*s).

N.B. The correct call would be isspace((unsigned char)*s) because
isspace has undefined behaviour if you pass it a char with a negative
value.

It would be nice if GCC warned about *that*.