[PATCH] readline_simple: Fix compiler warning

[Jules Maselbas]

FYI,

On Wed, May 12, 2021 at 03:04:30PM +0200, Sascha Hauer wrote:
> On Wed, May 12, 2021 at 01:25:14PM +0200, Michael Olbrich wrote:
> > On Wed, May 12, 2021 at 07:44:40AM +0200, Sascha Hauer wrote:
> > > char is an unsigned type.
> > 
> > That's incorrect. In the C standard it is explicitly undefined whether char
> > is signed or unsigned. gcc implements this differently depending on the
> > architecture. I think ARM and x86 differ here.
> 
> Ok. I already reworded this to "char can be an unsigned type".
You can use "singed char" if you really need it.

    There are five standard signed integer types, designated as signed char,
    short int, int, long int, and long long int.

from ISO/IEC 9899:TC2 - 6.2.5 Types

Best,
Jules