Renaming a coordinate of a multi-index after stack fails

[atantet]

Code Sample, a copy-pastable example if possible

import numpy as np
import xarray as xr

 da = xr.DataArray(np.arange(np.prod(dims)).reshape(*dims), coords=[('dim0', np.arange(dims[0])), ('dim1', np.arange(dims[0]) + 2)]) 
daStacked = da.stack(dim0_dim1=['dim0', 'dim1'])

daStacked.rename(dim1='foo')

Problem description

'dim1' is indeed neither a variable nor a dimension, since the only dimension is now 'dim0_dim1'. Is there a good reason to limit the possibility to rename to dimensions rather than all coordinates?

Expected Output

ValueError: cannot rename 'dim1' because it is not a variable or dimension in this dataset

Output of xr.show_versions()

INSTALLED VERSIONS ------------------ commit: None python: 3.6.6.final.0 python-bits: 64 OS: Linux OS-release: 2.6.32-696.20.1.el6.x86_64 machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: fr_FR.UTF-8 LOCALE: fr_FR.UTF-8

xarray: 0.10.8
pandas: 0.23.4
numpy: 1.15.0
scipy: 1.1.0
netCDF4: 1.4.0
h5netcdf: None
h5py: None
Nio: None
zarr: None
bottleneck: 1.2.1
cyordereddict: None
dask: 0.18.2
distributed: None
matplotlib: 2.2.2
cartopy: None
seaborn: None
setuptools: 40.0.0
pip: 18.0
conda: None
pytest: None
IPython: 6.5.0
sphinx: None

[shoyer]

MultiIndex levels should really be xarray.Variable objects, but unfortunately that isn't the case right now. We have some special cases in indexing to dynamically create xarray.Variable objects, but it isn't done consistently in all functions.

The refactor envisioned in #1603 should eventually fix this.

[stale]

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If this issue remains relevant, please comment here or remove the stale label; otherwise it will be marked as closed automatically

[benbovy]

This should be fixed in #5692 now.