Re: Why AC_C_CHAR_UNSIGNED?

[Richard Ash]

Hallvard B Furuseth wrote:
> What's the point of the AC_C_CHAR_UNSIGNED macro?
>     "If the C type `char' is unsigned, define `__CHAR_UNSIGNED__',
>     unless the C compiler predefines it."
>
> This is what <limits.h> is for.  If you want to know if char is
> unsigned, try #if CHAR_MIN == 0.  I would suggest at least mentioning
> that option in the doc for AC_C_CHAR_UNSIGNED.
That assumes you have a correct limits.h on the system, which is an
assumption you can't necessarily make on an old enough system. It also
assumes that the compiler matches the headers, which again might be wrong
if someone has messed up a third party compiler install.