Error messages when pass keyword arguments to some builtins that
don't support keyword arguments contained double parenthesis: "()()".
The regression was introduced by bpo-30534.
bltinmodule.c: Added in b744ba1 and no longer necessary since d64e8a7
posixmodule.c: Added in d1cd4d4 and no longer necessary since efb00c0
pythonrun.c: Added in 73d538b and no longer necessary since d600951
sysmodule.c: Added in 5467d4c and no longer necessary since a2c17c5
* Replace PyArg_ParseTupleAndKeywords() with _PyArg_ParseStackAndKeywords()
which is more efficient to parse keywords, since it decodes only keywords
(char*) from UTF-8 once, instead of decoding at each call.
* METH_FASTCALL avoids the creation of a temporary tuple to pass positional
arguments.
Patch written by INADA Naoki, pushed by Victor Stinner.
Issue #28870: Add a new _PY_FASTCALL_SMALL_STACK constant, size of "small
stacks" allocated on the C stack to pass positional arguments to
_PyObject_FastCall().
_PyObject_Call_Prepend() now uses a small stack of 5 arguments (40 bytes)
instead of 8 (64 bytes), since it is modified to use _PY_FASTCALL_SMALL_STACK.
Handling zero-argument super() in __init_subclass__ and
__set_name__ involved moving __class__ initialisation to
type.__new__. This requires cooperation from custom
metaclasses to ensure that the new __classcell__ entry
is passed along appropriately.
The initial implementation of that change resulted in abruptly
broken zero-argument super() support in metaclasses that didn't
adhere to the new requirements (such as Django's metaclass for
Model definitions).
The updated approach adopted here instead emits a deprecation
warning for those cases, and makes them work the same way they
did in Python 3.5.
This patch also improves the related class machinery documentation
to cover these details and to include more reader-friendly
cross-references and index entries.
Issue #28858: The change b9c9691c72c5 introduced a regression. It seems like
_PyObject_CallArg1() uses more stack memory than
PyObject_CallFunctionObjArgs().
