Bob,
Some of us still use varargs interfaces (in my case, Fortran calling C stdarg subroutines).
The problem for us is that that sometimes using varargs made standard- conforming Fortran code like, in file a.f subroutine foo(a) print *,a end and in file main.f programme main call foo(1.0) end depend ABI details: The call to foo used to be called using the varargs convention, and the subroutine foo was compiled as a non-varargs function. This "worked" until PR 87689 showed that this breaks standard-conforming Fortran code on a primary gcc platform. I don't know if that makes a difference for the platform you work on. For the System V AMD64 ABI, I suspect it actually might not matter (at least from glancing at the corresponding Wikipedia article), but I am _not_ an expert in this field, so please take this with a chunk of rock salt of appropriate size. So, we cannot really keep this as a feature (note that varargs are also not C interoperable). Regards Thomas