BUG: Reset index regression

[znicholls]

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

from pandas import DataFrame, Index
import xarray

df = DataFrame(
    [[1, 2], [3, 4]],
    columns=xarray.cftime_range("0001", periods=2),
    index=Index(["hi", "bye"], name="string"),
)
# currently fails with TypeError
res = df.reset_index()

Issue Description

The above leads to a type error.

Expected Behavior

Reset index. I would guess that the columns should be downcast from CFTimeIndex to Index with object type but maybe there's a better option.

Installed Versions

miniconda3/envs/pandas-dev/lib/python3.8/site-packages/_distutils_hack/init.py:30: UserWarning: Setuptools is replacing distutils.
warnings.warn("Setuptools is replacing distutils.")

INSTALLED VERSIONS

commit : 1def8d9
python : 3.8.13.final.0
python-bits : 64
OS : Darwin
OS-release : 19.6.0
Version : Darwin Kernel Version 19.6.0: Mon Apr 18 21:50:40 PDT 2022; root:xnu-6153.141.62~1/RELEASE_X86_64
machine : x86_64
processor : i386
byteorder : little
LC_ALL : None
LANG : en_AU.UTF-8
LOCALE : en_AU.UTF-8

pandas : 1.5.0.dev0+798.g1def8d9f3f
numpy : 1.22.3
pytz : 2022.1
dateutil : 2.8.2
pip : 22.0.4
setuptools : 62.3.2
Cython : 0.29.30
pytest : 7.1.2
hypothesis : 6.46.7
sphinx : 4.5.0
blosc : None
feather : None
xlsxwriter : 3.0.3
lxml.etree : 4.8.0
html5lib : 1.1
pymysql : None
psycopg2 : None
jinja2 : 3.0.3
IPython : 8.3.0
pandas_datareader: None
bs4 : 4.11.1
bottleneck : 1.3.4
brotli :
fastparquet : 0.8.1
fsspec : 2021.11.0
gcsfs : 2021.11.0
matplotlib : 3.5.2
numba : 0.53.1
numexpr : 2.8.0
odfpy : None
openpyxl : 3.0.9
pandas_gbq : None
pyarrow : 8.0.0
pyreadstat : 1.1.6
pyxlsb : None
s3fs : 2021.11.0
scipy : 1.8.0
snappy :
sqlalchemy : 1.4.36
tables : 3.7.0
tabulate : 0.8.9
xarray : 2022.3.0
xlrd : 2.0.1
xlwt : 1.3.0
zstandard : None

[znicholls]

Looks like this was caused as a result of #43933

6821872 is the first bad commit
commit 6821872
Author: jbrockmendel [email protected]
Date: Fri Oct 8 17:17:40 2021 -0700

BUG: NumericIndex.insert (#43933)

pandas/core/indexes/base.py | 7 ++++---
pandas/tests/indexes/common.py | 19 +++++++++++++++++++
2 files changed, 23 insertions(+), 3 deletions(-)
bisect run success

[znicholls]

The xarray version is 2022.3.0

[simonjayhawkins]

cc @jbrockmendel

[jbrockmendel]

Looks like CFTImeIndex.__new__ is getting called in a place it shouldn't be. IIUC the use of self._constructor in Index.insert will be unnecessary in 2.0 at which point this might start working again on its own

[simonjayhawkins]

moving to 1.4.4

[jorisvandenbossche]

This should be an easy fix to keep using Index(..) instead of _constructor for non-NumericIndex cases. Opened a PR at #48058