In writing some tests for the alternate date constructors as part of my PR forissue 32403 (https://bugs.python.org/issue32403), I noticed that for `datetime`, the `fromtimestamp` bypasses the `__new__` call on the subclass:    from datetime import datetime    args = (2003, 4, 14)    ts =1050292800.0           # Equivalent timestamp    d_ord = 731319              # Equivalent ordinal date    class DatetimeSubclass(datetime):        def __new__(cls, *args, **kwargs):            result = datetime.__new__(cls, *args, **kwargs)            result.extra = 7            return result    base_d = DatetimeSubclass(*args)    assert isinstance(base_d, DatetimeSubclass)         # Passes    assert base_d.extra == 7                            # Passes    ord_d = DatetimeSubclass.fromordinal(d_ord)    assert isinstance(ord_d, DatetimeSubclass)          # Passes    assert ord_d.extra == 7                             # Passes    ts_d = DatetimeSubclass.fromtimestamp(ts)    assert isinstance(ts_d, DatetimeSubclass)           # Passes    assert ts_d.extra == 7                              # FailsReplacing `datetime` with `date` in the above code we don't get a failure, but with `datetime`, it fails with:    AttributeError: 'DatetimeSubclass' object has no attribute 'extra'Regardless of the status of 32403, I think this should be fixed (though I can try to fix them both at the same time).

New changeset9f1b7b93f5f0ef589e7b272e127cacf4ce5d23f1 by Alexander Belopolsky (Paul Ganssle) in branch 'master':bpo-32403: Faster date and datetime constructors (#4993)https://github.com/python/cpython/commit/9f1b7b93f5f0ef589e7b272e127cacf4ce5d23f1