BUG: Creating a MultiIndex using pd.Index and the name argument is now broken (worked in 1.2.5 with names)

[Dr-Irv]

• 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 master branch of pandas.

Reproducible Example

In [1]: import pandas as pd

In [2]: pd.__version__
Out[2]: '1.4.0.dev0+905.gdace93d694'

In [3]: pd.Index([(1,0), (1,1)], names=["foo", "bar"])
<ipython-input-3-99fe0b033485>:1: FutureWarning: Passing keywords other than 'data', 'dtype', 'copy', 'name', 'tupleize_cols' is deprecated and will raise TypeError in a future version.  Use the specific Index subclass directly instead.
  pd.Index([(1,0), (1,1)], names=["foo", "bar"])
Out[3]:
MultiIndex([(1, 0),
            (1, 1)],
           names=['foo', 'bar'])

In [4]: pd.Index([(1,0), (1,1)], name=["foo", "bar"])
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-4-138c3fe61553> in <module>
----> 1 pd.Index([(1,0), (1,1)], name=["foo", "bar"])

c:\Code\pandas_dev\pandas\pandas\core\indexes\base.py in __new__(cls, data, dtype, copy, name, tupleize_cols, **kwargs)
    403         from pandas.core.indexes.range import RangeIndex
    404
--> 405         name = maybe_extract_name(name, data, cls)
    406
    407         if dtype is not None:

c:\Code\pandas_dev\pandas\pandas\core\indexes\base.py in maybe_extract_name(name, obj, cls)
   6876     # GH#29069
   6877     if not is_hashable(name):
-> 6878         raise TypeError(f"{cls.__name__}.name must be a hashable type")
   6879
   6880     return name

TypeError: Index.name must be a hashable type

Issue Description

In pandas 1.2.5, you could create a MultiIndex using pd.Index with the names argument:

In [1]: import pandas as pd

In [2]: pd.__version__
Out[2]: '1.2.5'

In [3]: pd.Index([(1,0), (1,1)], names=["foo", "bar"])
Out[3]:
MultiIndex([(1, 0),
            (1, 1)],
           names=['foo', 'bar'])

With names being removed as an argument in the future, the user then has to be explicit about using the pd.MultiIndex() constructor.

See discussion with @jreback starting here: #35292 (comment)

Expected Behavior

Unclear. Should we accept names in pd.Index() ? Because you can create a MultiIndex without names via

In [5]: pd.Index([(1,0), (1,1)])
Out[5]:
MultiIndex([(1, 0),
            (1, 1)],
           )

Installed Versions

INSTALLED VERSIONS

commit : dace93d
python : 3.8.6.final.0
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.19041
machine : AMD64
processor : Intel64 Family 6 Model 158 Stepping 13, GenuineIntel
byteorder : little
LC_ALL : None
LANG : None
LOCALE : English_United States.1252

pandas : 1.4.0.dev0+905.gdace93d694
numpy : 1.21.2
pytz : 2021.1
dateutil : 2.8.2
pip : 21.2.4
setuptools : 49.6.0.post20210108
Cython : 0.29.24
pytest : 6.2.5
hypothesis : 6.19.0
sphinx : 4.1.2
blosc : None
feather : None
xlsxwriter : 3.0.1
lxml.etree : 4.6.3
html5lib : 1.1
pymysql : None
psycopg2 : None
jinja2 : 3.0.1
IPython : 7.27.0
pandas_datareader: None
bs4 : 4.10.0
bottleneck : 1.3.2
fsspec : 2021.05.0
fastparquet : 0.7.1
gcsfs : 2021.05.0
matplotlib : 3.4.2
numexpr : 2.7.3
odfpy : None
openpyxl : 3.0.7
pandas_gbq : None
pyarrow : 4.0.0
pyxlsb : 1.0.6
s3fs : 2021.05.0
scipy : 1.7.1
sqlalchemy : 1.4.23
tables : 3.6.1
tabulate : 0.8.9
xarray : 0.18.2
xlrd : 2.0.1
xlwt : 1.3.0
numba : 0.53.1

[erfannariman]

Could you elaborate what the bug is here exactly? TypeError: Index.name must be a hashable type makes sense, although it is confusing there is both a name and names argument (with the latter being removed in the future).

[Dr-Irv]

although it is confusing there is both a name and names argument (with the latter being removed in the future).

That's the point. With 1.2.5 and earlier, you could create a MultiIndex using pd.Index() and names= to specify the names. Since there was a decision to deprecate names, there isn't a path forward for people to create a MultiIndex using pd.Index() .

So we either do not deprecate names or we allow name to include multiple names when pd.Index() is used. We need to fix the inconsistency in the API.

[jreback]

this is really for an internal change - i think the external api is fine