On Monday 04 January 2010 01:36:45 am Gennadiy Rozental wrote:
Bjørn Roald wrote:
On Friday 01 January 2010 10:15:29 pm Steven Watanabe wrote:
AMDG
Boost.Test is still failing on some compilers that don't support va_copy. Is va_copy always a macro? Would it be possible to use #ifdef va_copy?
If it helps, that is what is done here: http://svn.apache.org/repos/asf/stdcxx/branches/4.1.3/src/exception.cpp
I'd rather stay away from ifdef va_copy. Does it required by standard for the va_copy to be a macro?
Latest C++0x drafts say: Other runtime support [support.runtime] Table 21 — Header <cstdarg> synopsis Type Name(s) Macros: va_arg va_end va_start va_copy Type: va_list And state that <cstdarg> provide same features as C99 stdarg.h with some C++ adjustments.
The commit in trunk adding va_copy is also missing the va_end call and possibly one more call of va_copy to be correct according to the manpage.
You mean I need va_end after va_copy?
Yes - the Linux manual page says. va_copy() An obvious implementation would have a va_list be a pointer to the stack frame of the variadic func‐ tion. In such a setup (by far the most common) there seems nothing against an assignment va_list aq = ap; Unfortunately, there are also systems that make it an array of pointers (of length 1), and there one needs va_list aq; *aq = *ap; Finally, on systems where arguments are passed in registers, it may be necessary for va_start() to allocate memory, store the arguments there, and also an indication of which argument is next, so that va_arg() can step through the list. Now va_end() can free the allocated memory again. To accommodate this situation, C99 adds a macro va_copy(), so that the above assignment can be replaced by va_list aq; va_copy(aq, ap); ... va_end(aq); Each invocation of va_copy() must be matched by a corresponding invocation of va_end() in the same function. Some systems that do not supply va_copy() have __va_copy instead, since that was the name used in the draft proposal. === end manual quote
Where is another va_copy?
A bit further down the same function: if( tl != PASS ) { args = args_copy; <===== Looks a lot like a va_list assignment. But I have no clear understanding of the code, or va_list HOWTOs for that sake. -- Bjørn