html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/5738#issuecomment-906201836,https://api.github.com/repos/pydata/xarray/issues/5738,906201836,IC_kwDOAMm_X842A4rs,4160723,2021-08-26T08:25:47Z,2021-08-26T08:25:47Z,MEMBER,"My initial thoughts was to opt for D because it is easier to maintain (less special cases, less complexity, internally we could get rid of `assert_unique_multiindex_level_names` after dropping multi-index virtual variables) and also because an error is raised when there's actually an issue, e.g., we could do `stack` and never plan to do `unstack` later so in that case multi-index level vs. dimension name conflict is not an issue?

I was thinking about this kind of behavior (even though reverting previous changes is not ideal):

```python
ds = xr.Dataset(coords={'dim0': ['a', 'b'], 'dim1': [0, 1]})
ds = ds.stack(dim_stacked=['dim0', 'dim1'])

# This works: dim0 is not a dimension in b
ds['c'] = (('dim0',), [10, 11, 12, 13, 14, 15])

# raise a nice error message here: conflicting sizes for dimension 'dim0'
ds.unstack(dim_stacked)

# raise a nice error message here: conflicting sizes for dimension 'dim0'
ds.sel(dim1=0)
```

However, this may be confusing in the case of integer-based vs. label based indexing:

```python
# label-based selection along `dim_stacked` dimension (length=4)
ds.sel(dim0='a')

# integer-based selection along `dim0` dimension (length=6)
ds.isel(dim0=0)
```

So a more general rule like option C is not that silly after all?

If a dimension name matches the name of a coordinate:

- Ok if this coordinate is a ""dimension"" coordinate (coordinate name == dimension name)
- (maybe ok if this this coordinate is not indexed?) 
- Error otherwise","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,979316661
https://github.com/pydata/xarray/issues/5738#issuecomment-906159715,https://api.github.com/repos/pydata/xarray/issues/5738,906159715,IC_kwDOAMm_X842AuZj,4160723,2021-08-26T07:21:07Z,2021-08-26T07:21:07Z,MEMBER,@fujiisoup @shoyer @aseyboldt,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,979316661