Re: building with gcc 4.4

Yup, that works too, will use it in Fedora packages...

Thanks for fast cooperation,
Milos

Sam Varshavchik wrote:
> Milos Jakubicek writes:
> 
>> Hi Sam,
>>
>> Sam Varshavchik wrote:
>>> Milos Jakubicek writes:
>>>
>>>> Hi all,
>>>>
>>>> I'm attaching a tiny patch to make cone building with gcc 4.4, 
>>>> please merge it.
>>>
>>> Although this looks very straightforward, I do have some questions. 
>>> AFAIK, SUSv2 explicitly defines strchr as taking a const char * arg. 
>>> The cast should not be necessary.
>>
>> Yes, the problem is that starting with gcc 4.4, if strchr takes const 
>> char*, it also returns const char*, therefore the cast.
>> See http://gcc.gnu.org/gcc-4.4/porting_to.html
> 
> I see. In that case, the correct fix is really to redeclare the "p" 
> pointer as a const char *, rather than casting it.
> 
>> Furthermore, a quick search of the code finds several other
>>> instances where both strchr() and memcpy() are used with the same 
>>> parameter types, so if these two instances need this kind of a patch, 
>>> how come the other instances don't?
>>
>> What places, aren't they in an #ifdef so that they do not evaluate?
>> Remember that the problem is again the same: you give const char* to 
>> strchr => it returns const char*. I'm not sure whether the standard 
>> says you can cast any pointer type, even const type, to void*.
> 
> That actually explains it. The memcpy in question takes the return value 
> from strrchr() with itself takes a const char * parameter, which now 
> makes the memcpy parameter a const char *.
> 
> The correct fix there, then, would be to const_cast the strrchr() 
> parameter to a char *.
> 
> Can you verify that the following will make gcc 4.4 happy.
> 
> Index: libmail/maildiradd.C
> ===================================================================
> RCS file: /cvsroot/courier/libs/libmail/maildiradd.C,v
> retrieving revision 1.6
> diff -U3 -r1.6 maildiradd.C
> --- libmail/maildiradd.C    24 May 2008 17:57:42 -0000    1.6
> +++ libmail/maildiradd.C    19 Apr 2009 11:54:45 -0000
> @@ -165,7 +165,8 @@
>     if (flags.size() > 0)
>     {
>         newname = newname + MDIRSEP "2," + flags;
> -        memcpy(strrchr(newname.c_str(), '/')-3, "cur", 3);
> +        memcpy(strrchr(const_cast<char *>(newname.c_str()), '/')-3,
> +               "cur", 3);
>         // We go into the cur directory, now
>     }
> 
> Index: libmail/qp.C
> ===================================================================
> RCS file: /cvsroot/courier/libs/libmail/qp.C,v
> retrieving revision 1.1
> diff -U3 -r1.1 qp.C
> --- libmail/qp.C    27 May 2003 14:09:08 -0000    1.1
> +++ libmail/qp.C    19 Apr 2009 11:54:46 -0000
> @@ -16,7 +16,7 @@
> {
>     static const char xdigits[]="0123456789ABCDEFabcdef";
> 
> -    char *p=strchr(xdigits, c);
> +    const char *p=strchr(xdigits, c);
> 
>     if (p == NULL)
>         return -1;
> 
> 
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