http://d.puremagic.com/issues/show_bug.cgi?id=2004

           Summary: no clean way to dynamically loop over va_args
           Product: DGCC aka GDC
           Version: unspecified
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: major
          Priority: P2
         Component: glue layer
        AssignedTo: dvdfrdmn@users.sf.net
        ReportedBy: fawzi@gmx.ch
OtherBugsDependingO 670,1968
             nThis:


due to the structure of va_list there is no easy way to loop over unknown arguments.

Skipping them based on their size is not easy even using tricks (a template generating a fake structure of the requested size), because also the alignment must be known and it is difficult to gather from typeinfo.

One possibility would be to re-implement

The cleanest thing would be either to either implement a function
void *dyn_va_arg(TypeInfo,va_list) that returns a pointer to the type, and
skips it.
Barring alignment issues of the arguments passed in the registers, this should
be easy for the compiler to implement.

If alignment issues are a problem then I think that a void*dyn_va_arg_tmp(TypeInfo,va_list,out bool) that gives a temporary pointer and says if the pointer is temporary could be considered, but only as last resort, if at all possible a clean re-implementation of va_arg for D should be considered.

Such a function would make boxer, tangos Layout and similar things possible in a clean way.


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=2004


Iain Buclaw <ibuclaw@ubuntu.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID


--- Comment #1 from Iain Buclaw <ibuclaw@ubuntu.com> 2011-01-31 09:39:09 PST ---
As per, bug1066, closing.

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