BUG: Cannot convert pd.NA to Timestamp

[gusutabopb]

Pandas version checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

import pandas as pd
import numpy as np

print(f"{pd.__version__=}")
for v in [None, np.nan, pd.NA]:
    print(v, pd.Timestamp(v), sep="\t")

Issue Description

pd.Timestamp constructor fails to handle pd.NA properly on the latest version and main branch (1.5.0.dev0+128.g91d3f0b246).

This works fine (on both main branch and 1.3.5) using pd.to_datetime (seems to have been fixed in #32213):

In [5]: pd.to_datetime([np.nan, None, pd.NA])
Out[5]: DatetimeIndex(['NaT', 'NaT', 'NaT'], dtype='datetime64[ns]', freq=None)

Expected Behavior

I expect the Timestamp constructor to handle pd.NA the same way as it handles None and np.nan, i.e. pd.Timestamp(pd.NA) should return NaT.

Installed Versions

INSTALLED VERSIONS
------------------
commit           : 91d3f0b2467e045523358b493789b73b405967e9
python           : 3.10.0.final.0
python-bits      : 64
OS               : Linux
OS-release       : 4.4.0-18362-Microsoft
Version          : #1049-Microsoft Thu Aug 14 12:01:00 PST 2020
machine          : x86_64
processor        : x86_64
byteorder        : little
LC_ALL           : en_US.UTF-8
LANG             : en_US.UTF-8
LOCALE           : en_US.UTF-8
pandas           : 1.5.0.dev0+128.g91d3f0b246
numpy            : 1.21.2
pytz             : 2021.3
dateutil         : 2.8.2
pip              : 21.2.4
setuptools       : 58.0.4
Cython           : 0.29.25
pytest           : None
hypothesis       : None
sphinx           : None
blosc            : None
feather          : None
xlsxwriter       : None
lxml.etree       : None
html5lib         : None
pymysql          : None
psycopg2         : None
jinja2           : None
IPython          : 7.29.0
pandas_datareader: None
bs4              : None
bottleneck       : None
fastparquet      : None
fsspec           : None
gcsfs            : None
matplotlib       : None
numba            : None
numexpr          : None
odfpy            : None
openpyxl         : None
pandas_gbq       : None
pyarrow          : None
pyreadstat       : None
pyxlsb           : None
s3fs             : None
scipy            : None
sqlalchemy       : None
tables           : None
tabulate         : None
xarray           : None
xlrd             : None
xlwt             : None
zstandard        : None

[gusutabopb]

Just for the record, this issue is still present in version 2.0.0.

[MarcoGorelli]

looks fine to me

In [12]: pd.__version__
Out[12]: '2.0.0'

In [13]: pd.to_datetime([np.nan, None, pd.NA])
Out[13]: DatetimeIndex(['NaT', 'NaT', 'NaT'], dtype='datetime64[ns]', freq=None)

what's your expected output?

[jorisvandenbossche]

Using to_datetime already worked fine before as well, but it is about the Timestamp constructor:

In [3]: pd.__version__
Out[3]: '2.0.0'

In [4]: pd.Timestamp(None)
Out[4]: NaT

In [5]: pd.Timestamp(pd.NA)
...
TypeError: Cannot convert input [<NA>] of type <class 'pandas._libs.missing.NAType'> to Timestamp