[Bug c/50581] stdarg doesn't support array types

[joseph at codesourcery dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50581

--- Comment #5 from joseph at codesourcery dot com <joseph at codesourcery dot 
com> 2011-10-01 18:45:43 UTC ---
On Sat, 1 Oct 2011, Wolfgang at Solfrank dot net wrote:

> > Passing va_list as a function argument is generally hard, whether or not 
> > variadic, since you don't know whether it will be passed by reference or 
> > by value or what the type of the address of a va_list parameter will be.  
> > Portable code needs to pass a pointer to va_list or a structure containing 
> > va_list or use some other such means of avoiding dependence on whether 
> > va_list is an array.
> 
> Huh?  What about vprintf and friends?  They are defined to take a va_list as
> their last parameter.

There are some things you can do - for example, calling those functions in 
accordance with the rules given in the C standard.  There are various 
things that cause problems - for example, taking the address of a 
parameter declared as a va_list (because the parameter type may have been 
changed from va_list to pointer-to-element-of-va_list as part of the 
parameter type adjustment of parameters declared as arrays, so the type of 
&parameter may not be va_list *).