-Wunused don't warn for exit

-Wunused don't warn for exit

[Gabriel Linder]

Hello all,

I have a strange behaviour I can't explain with GCC (3.2.2), considering 
the following piece of code (exit.c) :

/* snip */
#include <stdlib.h>
#include <stdio.h>

int main(void)
{
        0;
        printf;
        exit;
        exit(1);
        return 0;
}
/* snip */

When compiled with gcc -Wunused -Wunreachable-code exit.c I get these 
warnings :
exit.c: In function `main':
exit.c:6: warning: statement with no effect
exit.c:7: warning: statement with no effect

So GCC detects lines 6 and 7, that's ok. But why didn't it print a 
warning for lines 8 (exit with no args, equal to the value of exit 
function pointer, useless) and 10 (return 0 after exit, will never be 
executed) ?

This is the declaration of exit function (stdlib.h) :
__BEGIN_NAMESPACE_STD
extern void exit (int __status) __THROW __attribute__ ((__noreturn__));
__END_NAMESPACE_STD

Re: -Wunused don't warn for exit

[Ian Lance Taylor]

Gabriel Linder <linder@jeuxvideo.com> writes:

> I have a strange behaviour I can't explain with GCC (3.2.2),

3.2.2 is pretty old.  The current version is 4.1.1.

> When compiled with gcc -Wunused -Wunreachable-code exit.c I get these
> warnings :
> exit.c: In function `main':
> exit.c:6: warning: statement with no effect
> exit.c:7: warning: statement with no effect

I get these warnings with current gcc:

foo5.c: In function ‘main’:
foo5.c:6: warning: statement with no effect
foo5.c:7: warning: statement with no effect
foo5.c:8: warning: statement with no effect
foo5.c:10: warning: will never be executed

which looks OK to me.

gcc 3.2.2 is no longer supported, so the bug will not be fixed in that
old release.

Ian