Re: ctype and gcc9

[christos%astron.com@localhost (Christos Zoulas)]

In article <20200921083148.GA17688@quantz>,
Patrick Welche  <prlw1%cam.ac.uk@localhost> wrote:
>Since gcc9, essentially every ctype using piece of software fails with
>
>   error: array subscript has type 'char' [-Werror=char-subscripts]
>
>which prompts a style question: cast every argument of every call to
>a ctype function in every piece of software to (unsigned char), or
>-Wno-error=char-subscripts], or something else?

cast to unsigned char. The ctype functions have undefined behavior for
negative values other than -1. The code is buggy.

christos