If I read you correctly, you want to protest if type does not strictly match
format directive.
This is something even gcc does NOT ensure by default:
#include <stdio.h>
#include <stdlib.h>
int
main() {
int i = 256;
const char* s = "Hello";
const void* p = s;
printf("%x\n", i);
printf("%u %s\n", i, p);
}
$ gcc -std=c11 foo.c
$ => Ok
Only -Wformat (or -Wall) shows a warning on the 2nd printf, printf of i (a
signed) is always Ok.
$ gcc -std=c11 -Wall foo.c
foo.c: In function 'main':
foo.c:11:21: warning: format '%s' expects argument of type 'char *', but
argument 3 has type 'const void *' [-Wformat=]
printf("%u %s\n", i, p);
~^
%p
-----Original Message-----
From: Pascal Cuoq [mailto:c...@trust-in-soft.com]
Sent: Friday, June 21, 2019 15:17
To: jull...@eligis.com; tinycc-devel@nongnu.org
Subject: Re: [Tinycc-devel] match formats and arguments exactly
> On 21 Jun 2019, at 14:56, Christian Jullien <eli...@orange.fr> wrote:
>
> This is a valuable check but IMHO, it should be controlled by -Wformat (as
> GNU gcc) and set of false by default.
> Otherwise, I suspect tcc users will have a lot a new warnings.
I'm not implementing a new warning in TCC. I am only ensuring, by following
C11 7.21.6.1:8 to the letter, that the TCC source code passes the strictest
such checks that a C compiler could have, and also that a very exotic C
compiler does not produce a non-functional binary when compiling TCC.
Considering the amount of code that good warnings represent, I think that a
C compiler can either be tiny, or provide helpful warnings. The patches I
have been sending, including the last one, only make TCC not exhibit
undefined behavior, a more manageable goal that only requires small changes
and do not make TCC significantly larger.
Pascal
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