First of all, thank you Jeroen for writing nice PEPs.
When I read PEP 579, I think "6. METH_FASTCALL is private and undocumented"
should be solved first.
I don't have any idea about changing METH_FASTCALL more.
If Victor and Serhiy think so, and PyPy maintainers like it too, I want to
make it public
as soon as possible.
_PyObject_FastCall* APIs are private in Python 3.7.
But METH_FASTCALL is not completely private (start without underscore,
but not documented)
Can we call it as public, stable by adding document, if Ned allows?
It's used widely in Python internals already. I suppose that making it
doesn't make Python 3.7 unstable much.
If we can't at Python 3.7, I think we should do it at 3.8.
INADA Naoki <songofacandy(a)gmail.com>