Would you like signs with those chars?

I was fortunate to get hit by this a few decades ago, when seeing that my old dirty code doing this:

char c;

while ((c = getchar()) != EOF) {
/* do something */
}

would turn to an infinite loop on PPC, because chars were unsigned there and would never match EOF(-1). Since then I've been insisting on building and running my code on various architectures, among which Arm, in part for unsigned chars.