[BUG] DataFrame.columns need to be RangeIndex instead of empty column in pandas compatibility mode

[galipremsagar]

Describe the bug
In pandas comaptibility mode, empty dataframe columns need to be a RangeIndex.

Steps/Code to reproduce bug

In [1]: import pandas as pd

In [2]: df = pd.DataFrame()

In [3]: df.columns
Out[3]: RangeIndex(start=0, stop=0, step=1)

In [4]: import cudf

In [5]: cudf.DataFrame().columns
Out[5]: Index([], dtype='object')

In [6]: cudf.set_option("mode.pandas_compatible", True)

In [7]: cudf.DataFrame().columns
Out[7]: Index([], dtype='object')

[mroeschke]

IMO we should make cudf.DataFrame().columns return RangeIndex regardless of pandas compatible mode

[galipremsagar]

IMO we should make cudf.DataFrame().columns return RangeIndex regardless of pandas compatible mode

Agreed 👍 Will do.