Re: [PATCH] block-sha1/sha1.c: silence compiler complaints by casting void* to uintptr_t

From: Junio C Hamano <gitster@pobox.com>
Date: Aug 15, 2009, 01:46 UTC
Message-ID: <7v8whl7ss9.fsf@alter.siamese.dyndns.org>
In-Reply-To: <5HEgWEs64y4Ty7FnekstRP8Q71pNi_FTweLbMhYWc6zoZBA4jkJqpQ@cipher.nrlssc.navy.mil>

Brandon Casey <casey@nrlssc.navy.mil> writes:

Show 13 quoted lines

> Linus Torvalds wrote:
>> I suspect it might as well be cast to "const char *", and then 
>> hopefully you only need one cast.
>> 
>> So maybe it could be written as
>> 
>> 	data = (const char *) data + len;
>> 
>> instead, and avoid the second cast (because the assignment should be ok, 
>> since it's assigning back to a "const void *").
>
> Yep, that's enough.  It produces an identical binary on all platforms
> except Solaris x86 using SUNWspro compiler.

Casting to "const char *" to tell compilers that we are interested in byte address differences/increments makes sense to me, but I do not know how to interpret your last comment.

Do you mean that SUNWspro compiler misbehave with the "cast to char *" and do you meed your "casting to uintptr_t to explicitly compute byte addresses as int" to make it behave?