Re: CVS commit: src/lib/libc/stdio

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

On Mar 28,  5:24am, uwe%stderr.spb.ru@localhost ("Valeriy E. Ushakov") wrote:
-- Subject: Re: CVS commit: src/lib/libc/stdio

| On Tue, Mar 27, 2012 at 22:53:47 +0000, Christos Zoulas wrote:
| 
| > In article <20120327202907.GT26108%bigmac.stderr.spb.ru@localhost>,
| > Valeriy E. Ushakov <uwe%stderr.spb.ru@localhost> wrote:
| > >
| > >But that is not what the code was.  The code was:
| > >
| > >    char c; if (c == CHAR_MAX) ...
| > >
| > >and *that* is portable.  As I said in another mail to thsi thread that
| > >went unanswered, it is literally schizophrenic of lint to complain
| > >about it.
| > 
| > How can lint know that if (c == 255) is portable? Because CHAR_MAX
| > gets expanded by cpp to 255 before lint parses the file.
| 
| And this is *precisely* why it's fundamentally wrong.  It's not 80s
| any more.  CHAR_MAX is there for a reason.

It does not really matter. It is the compilation environment that matters,
and for that we don't even do it right, so lint has every right to warn:
[demoed with CHAR_MIN, because of easy access to machine with signed chars,
 you can do the opposite test on a machine with unsigned chars]

[11:26am] 10018>cat char.c                                 
#include <stdio.h>
#include <limits.h>

int
main(int argc, char *argv[])
{
        char c = argv[0][0];
        if (c == CHAR_MIN)
                printf("yes\n");
        return 0;
}
[11:26am] 10019>cc -funsigned-char -Wall char.c
char.c: In function 'main':
char.c:8: warning: comparison is always false due to limited range of data type

In reality I would expect a program using CHAR_MIN/CHAR_MAX to work properly
with -fsigned-char or -funsigned-char in the default compilation environment.
Yet, it does not.

christos