NSInvocation

[David Chisnall]

Hi,

I'm looking at lines 1032--1038 of NSInvocation.m:

                struct {
                  char  x[size];
                } dummy;
                dummy = va_arg(ap, typeof(dummy));
                memcpy(datum, dummy.x, size);

This will only work in cases where the arguments are all passed on the  
stack, so won't work for structures containing floating point, vector,  
or integer arguments where there is still space in the registers, and  
will cause stack corruption in the case where this is not what  
happens.  I am trying to work out why this code exists at all, since  
ffi and ffcall contain routines for doing this safely.

My current issue is that this relies on a GCC extension which clang is  
never going to support (specifically, variable length structure  
members).  Is there any reason for this code to exist?  Throwing an  
exception here seems like more sane behaviour; at least that will  
always fail, rather than fail nondeterministically.

David