[pypy-issue] Issue #2987: cpyext datetime bindings missing support for fold in Python 3.6 (pypy/pypy)

[Paul G]

New issue 2987: cpyext datetime bindings missing support for fold in Python 3.6
https://bitbucket.org/pypy/pypy/issues/2987/cpyext-datetime-bindings-missing-support

Paul G:

Part of CPython's [PEP 495](https://www.python.org/dev/peps/pep-0495/) implementation was to add [two new constructors to the `PyDateTime_CAPI` struct](https://github.com/python/cpython/blob/3.6/Include/datetime.h#L169):

- `DateTime_FromDateAndTimeAndFold`
- `Time_FromTimeAndFold`

This also has corresponding macros:

- [`PyDateTime_FromDateAndTimeAndFold`](https://github.com/python/cpython/blob/3.6/Include/datetime.h#L229)
- [`PyTime_FromTimeAndFold`](https://github.com/python/cpython/blob/3.6/Include/datetime.h#L237)

The current implementation of [`cdatetime.py`](https://bitbucket.org/pypy/pypy/src/default/pypy/module/cpyext/cdatetime.py) and [`cpyext_datetime.h`](https://bitbucket.org/pypy/pypy/src/default/pypy/module/cpyext/parse/cpyext_datetime.h) should be updated to include these.

This came up when [adding PyPy support to PyO3](https://github.com/PyO3/pyo3/pull/393#issuecomment-477755187).