Yes, let's merge.

I think it should stay required until typing has matured more, there's too much good stuff coming out each release not to make use of it immediately.

I feel having to do these kinds of workarounds is not nice and sucks out any willpower of improving typing: https://github.com/pydata/xarray/blob/e056cacdca55cc9d9118c830ca622ea965ebcdef/xarray/core/utils.py#L309-L336 (This Try Except is not necessary anymore if it stays a required dependency)

We also don't run mypy with minimum requirements so it's very likely we miss typing errors while going through these convoluted workaround paths.

Here's a few more examples from eariler PRs:

5678 - The necessary workaround if it's not required:

https://github.com/Illviljan/xarray/blob/c11aac2f00edf3584d1eec508fc850fb8f17e084/xarray/core/options.py#L4-L70+

5871 - Just a simple if check if it's required:

https://github.com/dcherian/xarray/blob/59f8586a747b1f0a7b5e42e0ee186a32a3a36819/xarray/core/_reductions.py#L10-L13

I think typing_extensions should remain available so we can immediately use the latest and greatest typing functions. For example TypeGuard https://www.python.org/dev/peps/pep-0647/ is a good one that I think we can make use of now. I've also been testing it in #5667.

Thanks, @mathause it seems indeed setuptools was the culprit, even for the weird dask errors as well. Now the tests are passing!

I don't get these, we haven't supported 2.7 or 3.6 for a while now why doesn't this happen on main then?

ubuntu-latest py38-bare-minimum ``` Run mamba env update -f $CONDA_ENV_FILE mamba env update -f $CONDA_ENV_FILE shell: /usr/bin/bash -l {0} env: CONDA_ENV_FILE: ci/requirements/py38-bare-minimum.yml CONDA_PKGS_DIR: /home/runner/conda_pkgs_dir conda-forge/linux-64 Using cache conda-forge/noarch Using cache

Looking for: ['python=3.8', 'coveralls', 'pip', 'pytest', 'pytest-cov', 'pytest-env', 'pytest-xdist', 'numpy=1.17', 'pandas=1.0', 'setuptools=40.4']

Encountered problems while solving: - package setuptools-40.4.0-py27_0 requires python >=2.7,<2.8.0a0, but none of the providers can be installed

Error: Process completed with exit code 1. ```

ubuntu-latest py38-min-all-deps ``` Run mamba env update -f $CONDA_ENV_FILE mamba env update -f $CONDA_ENV_FILE shell: /usr/bin/bash -l {0} env: CONDA_ENV_FILE: ci/requirements/py38-min-all-deps.yml CONDA_PKGS_DIR: /home/runner/conda_pkgs_dir conda-forge/linux-64 Using cache conda-forge/noarch Using cache

Looking for: ['python=3.8', 'boto3=1.13', 'bottleneck=1.3', 'cartopy=0.17', 'cdms2=3.1', 'cfgrib=0.9', 'cftime=1.1', 'coveralls', 'dask=2.24', 'distributed=2.24', 'h5netcdf=0.8', 'h5py=2.10', 'hdf5=1.10', 'hypothesis', 'iris=2.4', 'lxml=4.5', 'matplotlib-base=3.2', 'nc-time-axis=1.2', 'netcdf4=1.5.3', 'numba=0.49', 'numpy=1.17', 'pandas=1.0', 'pint=0.15', 'pip', 'pseudonetcdf=3.1', 'pydap=3.2', 'pynio=1.5', 'pytest', 'pytest-cov', 'pytest-env', 'pytest-xdist', 'rasterio=1.1', 'scipy=1.4', 'seaborn=0.10', 'setuptools=40.4', 'sparse=0.8', 'toolz=0.10', 'zarr=2.4']

Encountered problems while solving: - package distributed-2.24.0-py36h9f0ad1d_0 requires python_abi 3.6. _cp36m, but none of the providers can be installed ```