Re: [PATCH 1/6] Fix some "printf format" warnings.

From: Junio C Hamano <junkio@cox.net>
Date: Mar 12, 2007, 19:40 UTC
Message-ID: <7vfy8as129.fsf@assigned-by-dhcp.cox.net>
In-Reply-To: <45F55DC5.8060702@fs.ei.tum.de>

Simon 'corecode' Schubert <corecode@fs.ei.tum.de> writes:

Show 21 quoted lines

> Ramsay Jones wrote:
>>>> -        printf("%s%06o %s %d\t",
>>>> +        printf("%s%06lo %s %d\t",
>>>>                 tag,
>>>>                 ntohl(ce->ce_mode),
>>> I think we should do this instead:
>>>
>>>     printf("%s%06o %s %d\t", tag, (unsigned) ntohl(ce->ce_mode), ...
>>
>> Oops, yes you are right.
>> (cygwin typedef's uint32_t as unsigned long.)
>>
>> However, I would hate to add all those casts! Casts are not always
>> evil, but should be avoided if possible. Having said that, I don't
>> see another solution ...
>
> shouldn't it be something like this?
>
> printf("%s%06"PRIo32" %s %d\t", tag, ntohl(ce->ce_mode), ...)
>
> that's the correct and allegedly portable way I guess.

Yes, except that that is only portable across platforms with inttypes.h, and we would need a compatibility definition in git-compat-util.h next to PRIuMAX definition we already have.

But I wonder if this is really worth it.  The thing is,

    printf("%s%06o %s %d\t", tag, (unsigned) ntohl(ce->ce_mode), ...

is perfectly readable for even old timers about git, as long as they know traditional C and what ntohl() is. And ce->ce_mode even fits in 16-bit, so while we are _not_ supporting platforms whose unsigned int is 16-bit, the above cast is not losing any useful precision either.