What happened?

I'm struggling whether this is a bug or not. At least I faced a very unexpected behaviour.

For two given data arrays a and b with same dimensions and equal coordinates, c for c = a.where(b) should have equal dimensions and coordinates.

However if the coordinates of a have dtype of float32 and those of b are float64, then the dimension sizes of c will always be two. Of course, this way the coordinates of a and b are no longer exactly equal, but from a user perspective they represent the same labels.

The behaviour is likely caused by the fact that the indexes generated for the coordinates are no longer strictly equal, therefore where() picks only the two outer cells of each dimension. Allowing to explicitly pass indexes may help here, see #6392.

What did you expect to happen?

In the case described above, the dimensions and coordinates of c should be equal to a (and b).

Minimal Complete Verifiable Example

```Python import numpy as np import xarray as xr

c32 = xr.DataArray(np.linspace(0, 1, 10, dtype=np.float32), dims='x') c64 = xr.DataArray(np.linspace(0, 1, 10, dtype=np.float64), dims='x')

c3 = c32.where(c64 > 0.5) assert len(c32) == len(c3)

v32 = xr.DataArray(np.random.random(10), dims='x', coords=dict(x=c32)) v64 = xr.DataArray(np.random.random(10), dims='x', coords=dict(x=c64))

v3 = v32.where(v64 > 0.5) assert len(v32) == len(v3)

--> Assertion error, Expected :10, Actual :2

```

MVCE confirmation

• [X] Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
• [X] Complete example — the example is self-contained, including all data and the text of any traceback.
• [X] Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
• [X] New issue — a search of GitHub Issues suggests this is not a duplicate.

Relevant log output

No response

Anything else we need to know?

No response

Environment

INSTALLED VERSIONS ------------------ commit: None python: 3.9.12 | packaged by conda-forge | (main, Mar 24 2022, 23:17:03) [MSC v.1929 64 bit (AMD64)] python-bits: 64 OS: Windows OS-release: 10 machine: AMD64 processor: AMD64 Family 25 Model 80 Stepping 0, AuthenticAMD byteorder: little LC_ALL: None LANG: None LOCALE: ('de_DE', 'cp1252') libhdf5: 1.12.1 libnetcdf: 4.8.1 xarray: 2022.3.0 pandas: 1.4.2 numpy: 1.21.6 scipy: 1.8.0 netCDF4: 1.5.8 pydap: None h5netcdf: None h5py: None Nio: None zarr: 2.11.3 cftime: 1.6.0 nc_time_axis: None PseudoNetCDF: None rasterio: 1.2.10 cfgrib: None iris: None bottleneck: None dask: 2022.04.1 distributed: 2022.4.1 matplotlib: 3.5.1 cartopy: None seaborn: None numbagg: None fsspec: 2022.3.0 cupy: None pint: None sparse: None setuptools: 62.1.0 pip: 22.0.4 conda: None pytest: 7.1.2 IPython: 8.2.0 sphinx: None