K&R-style variadic functions

[Jacob Carlborg]

On 2012-07-18 11:41, Walter Bright wrote:

> Variadic functions, in order to work in C, need at least one parameter
> so that varargs can work.
>
>    int foo();
>
> declares a function with an unspecified parameter list, not a variadic
> one. It is specified by a definition somewhere:
>
>    int foo(a,b)
>    int a;
>    int b;
>    { ... }
>
> somewhere.

I think I understand now.

> If Dstep encounters the first declaration form, your options are to:
>
> 1. reject it (a perfectly reasonable approach)
>
> 2. treat it as:
>
>      int foo(void);
>
> I suggest option 2, which is what C++ does.

Sounds reasonable. I will also provide a flag specifying how this should 
be handled.

I actually found library that uses this style of declaration. It's used 
in several places in libruby. For example:

void rb_define_virtual_variable(const 
char*,VALUE(*)(ANYARGS),void(*)(ANYARGS));

ANYARGS is defined as:

#ifdef __cplusplus
#define ANYARGS ...
#else
#define ANYARGS
#endif

Does that mean that this C++ declaration:

void foo (...);

Is the same as this C declaration?

void foo ();

I'm wondering if the intention is to cast these function pointers to 
their correct signature before calling them.

-- 
/Jacob Carlborg