Re: E 0.9.3 release?

On Sun, Jan 02, 2011 at 04:07:59PM -0800, Mark Miller wrote:
> On Sun, Jan 2, 2011 at 11:36 AM, Bill Frantz <[email protected]> wrote:
> 
> > On 1/1/11 at 10:12 PM, [email protected] (Mark Miller) wrote:
> >
> > >* New warning: "warning: array subscript has type `char'"
> > >for C code in byacc/j that seems innocent to me. And in any case is old
> > >third party code.
> >
> > Since C supports signed chars (an abomination on the world), a C
> > compiler which actually defaults to signed could cause array
> > underflow problems. YMMV. VWP. Caveat emptor.
> >
> > I would change their declarations to include "unsigned".
> >
> 
> If I saw something that looked like indexing, I would understand. However,
> the warning complains, for example, about the last line of the following
> program fragment. This only happens to me using cygwin gcc on Windows.
> Compiling the same code on my Mac using regular gcc emits no warning.
> 
> 
> void print_pos(char *st_line,char *st_cptr)
> {
> char *s;
> 
>   if (st_line == 0) return;
>   for (s = st_line; *s != '\n'; ++s)
>     {
>          if (isprint(*s) || *s == '\t')

The problem is likely to be the implementation of isprint:  It is frequently
implemented as a (lightly protected) lookup in an array.  The warning would
likely go away if *s were declared or cast unsigned char.

Probably a bug in the isprint implementation, but still a real warning.

Jon Leonard