BUG: comparison of pandas NaT with datetime.date evaluating to True

[arc12]

Code Sample, a copy-pastable example

import pandas
import datetime
pandas.NaT < datetime.datetime.now().date()

Problem description

I understood the convention is for NA-types to evaluate to False in all inequalities. The above code evaluates to True.

These DO evaluate to False, as expected.
pandas.NaT < datetime.datetime.now()
pandas.NaT > datetime.datetime.now().date()

This seems to have been introduced with 1.2.0, and to not have been the behaviour under 1.1.5.

Output of pd.show_versions()

commit           : 3e89b4c4b1580aa890023fc550774e63d499da25
python           : 3.7.9.final.0
python-bits      : 64
OS               : Windows
OS-release       : 10
Version          : 10.0.18362
machine          : AMD64
processor        : Intel64 Family 6 Model 158 Stepping 9, GenuineIntel
byteorder        : little
LC_ALL           : None
LANG             : None
LOCALE           : None.None
pandas           : 1.2.0
numpy            : 1.19.2
pytz             : 2020.5
dateutil         : 2.8.1
pip              : 20.3.3
setuptools       : 51.1.2.post20210112
Cython           : None
pytest           : None
hypothesis       : None
sphinx           : None
blosc            : None
feather          : None
xlsxwriter       : 1.3.7
lxml.etree       : 4.6.2
html5lib         : None
pymysql          : None
psycopg2         : None
jinja2           : 2.11.2
IPython          : 7.19.0
pandas_datareader: None
bs4              : None
bottleneck       : 1.3.2
fsspec           : None
fastparquet      : None
gcsfs            : None
matplotlib       : 3.3.2
numexpr          : None
odfpy            : None
openpyxl         : None
pandas_gbq       : None
pyarrow          : None
pyxlsb           : None
s3fs             : None
scipy            : 1.5.2
sqlalchemy       : 1.3.22
tables           : None
tabulate         : None
xarray           : None
xlrd             : None
xlwt             : None
numba            : 0.52.0

[jorisvandenbossche]

@arc12 Thanks for the report! I can confirm the regression.

cc @jbrockmendel

[simonjayhawkins]

This seems to have been introduced with 1.2.0, and to not have been the behaviour under 1.1.5.

first bad commit: [d82e540] BUG: NaT.cmp(invalid) should raise TypeError (#35585)

[jbrockmendel]

Yah something similar came up for Timestamp. The solution is going to be to add in NaT.__richcmp__ something to the effect of

if PyDate_Check(other):
    if op == Py_EQ:
        return False
    if op == Py_NE:
        return True
     warn_that_this_is_deprecated_like_in_timestamp
     return False

[simonjayhawkins]

@jbrockmendel do you have time to fix this before Monday? otherwise I can look into it.

[jbrockmendel]

Yes, I'll do this right now

[simonjayhawkins]

Thanks @jbrockmendel