K&R-style variadic functions

[Regan Heath]

On Tue, 17 Jul 2012 15:02:44 +0100, Jacob Carlborg <doob at me.com> wrote:

> On 2012-07-17 14:32, Regan Heath wrote:
>
>>
>> After a bit of googling and a test with my local MSVC9 I think old-style
>> variadics look like this:
>>
>> #include <varargs.h>
>> #include <stdio.h>
>>
>> void foo(va_alist)
>>      va_dcl
>> {
>>      va_list p;
>>      va_start(p);
>>      vprintf("%d %d %d\n", p);
>> }
>>
>> void main()
>> {
>>      foo(1, 2, 3);
>> }
>>
>> (the above runs and outputs "1 2 3" on the console)
>>
>> The same syntax is/was supported by GNU C, see:
>> http://ftp.gnu.org/old-gnu/Manuals/glibc-2.2.3/html_chapter/libc_34.html#SEC676
>>
>>
>>
>> I believe, if you see an "old-style" function declaration in a header
>> file like:
>>
>>      int foo ();
>>
>> that you can't actually assume anything about it's parameters, it may
>> have /any/ number of parameters, and may or may not be variadic.
>
> Clang seems to interpret it as a variadic function. Then if that is  
> correct or not I don't know.

All my googling for "old style" "variadic" etc returned the use of  
va_alist and va_dcl so I can't see where/why Clang would do what it's  
doing.

R

-- 
Using Opera's revolutionary email client: http://www.opera.com/mail/