Re: [PATCH] vasnprintf: avoid a warning from gcc -Wsign-compare

[Jim Meyering]

Jim Meyering wrote:

> Paul Eggert wrote:
>> On 06/15/11 08:17, Jim Meyering wrote:
>>
>>> +   vasnprintf: avoid a warning from gcc -Wsign-compare
>>> +   * lib/vasnprintf.c (VASNPRINTF): Cast a known-positive quantity to
>>> +   size_t in order to avoid a warning from gcc -Wsign-compare.
>>
>> Given that the context is this:
>>
>>                     if (count >= 0)
>>                       {
>>                         /* Verify that snprintf() has NUL-terminated its
>>                            result.  */
>>                         if (count < maxlen
>>                             && ((TCHAR_T *) (result + length)) [count] != 
>> '\0')
>>                           abort ();
>>
>> wouldn't it be better to send the GCC maintainers a bug report?
>> Since maxlen is unsigned, and since it is obvious to
>> the compiler that count is nonnegative, there is no reason for
>> a sign-compare warning here.
>
> Yes, but that takes longer...
> Thanks for the prod.
> I've done it:
>
>   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49426

That has been marked as a duplicate of this report from 2008-12-10:

    http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38470

The comments there suggest that this will not be fixed any time soon,
so I re-propose the cast-adding patch.

If you prefer, I'll be happy to add a FIXME comment suggesting to
reexamine this case (hopefully removing the cast) in a year or two.