It is. It breaks vararg cross-platform compatibility (e.g. Linux x86 vs. Linux x86_64) and GDC/LDC will never need it. It's something that we really to be fixed sooner than later. The only reason why the current situation is bearable is that C varargs are rarely ever used in D-only code.
Do you know how to fix it in dmd? I don't know why it's there in the first place.
