Maya gains an extra microsecond when parsing dates after the year 2243

Consider the following program:

import datetime
import maya

d = datetime.datetime(2243, 1, 1, 0, 0, 0, 1)
print(d)
print(str(d))

parsed_d = maya.parse(str(d)).datetime()
print(parsed_d)
print(str(parsed_d))

assert d == parsed_d

2243-01-01 00:00:00.000001
2243-01-01 00:00:00.000001
2243-01-01 00:00:00.000002+00:00
2243-01-01 00:00:00.000002+00:00
Traceback (most recent call last):
  File "counterexample.py", line 15, in <module>
    assert d == parsed_d
AssertionError

This is a bug introduced somewhere in Maya – I see that Maya is using dateutil for the main machinery of its parse function, but if I try this with dateutil everything is fine:

import datetime
from dateutil import parser

d = datetime.datetime(2243, 1, 1, 0, 0, 0, 1)
print(d)
print(str(d))

parsed_d = parser.parse(str(d))
print(parsed_d)
print(str(parsed_d))

assert d == parsed_d

2243-01-01 00:00:00.000001
2243-01-01 00:00:00.000001
2243-01-01 00:00:00.000001
2243-01-01 00:00:00.000001

Environment details:

$ pip freeze
dateparser==0.5.0
humanize==0.5.1
iso8601==0.1.11
jdatetime==1.8.1
-e [e-mail]:kennethreitz/maya.git@6a4ddff215edbdce4a0f5b8bd5ba87710697b7f9#egg=maya-master
python-dateutil==2.6.0
pytz==2016.10
regex==2016.11.21
ruamel.yaml==0.13.4
six==1.10.0
tzlocal==1.3
umalqurra==0.2
wheel==0.24.0

I don’t actually care if you fix this (by 2243, I’ll either be dead, or hopefully have better things to do with my time), but having found it, I thought I’d share.

Yes, I know I’m a terrible person for finding this.

[mithrandi]

For those who care: the bug is caused by the float type having insufficient precision to represent the underlying POSIX timestamp correctly. The further away you get from the POSIX epoch (in either direction), the more precision you’ll lose in the timestamp.

[kennethreitz]

I think this is OK.