Re: [1003.1(2008)/Issue 7 0000074]: Pointer Types Problem

[David-Sarah Hopwood <david-sarah@xxxxxxxxxxxxx>]

Geoff Clare wrote:
> Wojtek Lerch <Wojtek@qnx.com> wrote, on 28 Aug 2009:
[...]
>> I also suggest removing the lie about the ISO C standard.  The above
>> conversion has undefined behaviour in ISO C but it does not "require a
>> warning".  ISO C does *allow* warnings (a.k.a. diagnostics) in this
>> situation, and some compilers may take advantage of it, but that's just
>> because ISO C allows compilers to generate diagnostics whenever they
>> feel like it.
> 
> The dlsym() issue was discussed extensively in 2002, and the end
> result was interpretation AI-003:
> 
> www.opengroup.org/austin/interps//uploads/40/1068/ai-003.txt
> 
> That's where the text about C99 requiring the warning is from.
> The interpretation response also includes this statement about the
> cast that used to be in the example (and is now being reinstated):
> 
>     "In this case, the 1999 C Standard does indeed require a warning
>     to be issued for the function call shown in the dlsym() examples
>     section on XSH P259, L8566."
> 
> I haven't re-read all of the 2002 discussion, but it seems to me
> that if anyone had made a convincing argument that C99 does not
> require the warning, then AI-003 would not have been approved with
> that statement.

Huh? Of course it is possible for an interpretation containing mistakes,
such as this one about C99, to be approved.

C99 *never* requires warnings. It sometimes requires "diagnostics"
(when "shall" conformance language is used in a constraint clause),
but it never distinguishes between warnings and errors.

-- 
David-Sarah Hopwood  ⚥  http://davidsarah.livejournal.com