Re: Musl git 0d......455eee8 and recent compilers

[Igmar Palsenberg <musl@palsenberg.com>]

> * Igmar Palsenberg <musl@palsenberg.com> [2011-06-06 10:48:08 +0200]:
>> I was using Musle as a test for..
> 
> musl

Sorry.... It's also the name of a cleaning substance here, so I usually het the name wrong :)
 
> 
>> 1) The struct dirent in include/dirent.h uses a 1 byte array for d_name. In reality, it's larger : We allocate more space than the struct. Since muscle requires a C99 compiler anyway, what's keeping use from using d_name[0] or d_name[] ? If a C89 compiler includes dirent.h, we're screwed anyway :). That will probably silence GCC 4.5 and clang, and severely reduce the warnings it gives in similar cases.
>> 
> 
> what kind of warnings do you get?

Array out of bounds :

src/misc/nftw.c:77:11: warning: array index of '1' indexes past the end of an array (that contains 1 elements) [-Warray-bounds]
                                 && (!de->d_name[1]

The compiler is strictly speaking right in this case.

> char foo[1] gives warning but a flexible array member char foo[] does not?

Correct. 

>> 2) The NULL pointer dereference in src/time/__asctime.c won't work with clang : It removes it. I suggest using either __builtin_trap() or an abort(). If you get to that point, you're in trouble anyway.
>> 
> 
> i guess __builtin_trap is compiler specific
> i don't think it's a big deal..
> there could be 0/0 as well i guess
> i wonder what
> main(){ return *(int*)0; }
> or even
> main(){ return ((int(*)())0)(); }
> does on clang..

Hmm.. Despite the warning :

int main(int argc, char **argv)                                                 
{                                                                               
    *(int*)0 = 0;                                                               
    printf("XXX\n");                                                            
    return 0;                                                                   
}

segfaults. Clang is allowed to remove the dereference, we might to use abort() in this case. With O3, it gives an illegal instruction (probably an ud2). I either misread the warning, or clang doesn't do what it says :).

> 
>> 3) Clang does't seem to grasp the weak_alias thingy. It need to check if those parts actually are correct
>> 
> 
> well it uses the alias __attribute__ extension of gcc

I need to check if the offending function / alias is there, or as clang says, isn't emitted.

>> 4) Is there a muscl testsuite somewhere ?
>> 
> 
> musl
> 
> http://git.etalabs.net/cgi-bin/gitweb.cgi

I'll try that.


Regards,


	Igmar