move kwarg's output_sizes and meta to dask_gufunc_kwargs for in… (#4391)

* move kwarg's `output_sizes` and `meta` to `dask_gufunc_kwargs` for internal use of `apply_ufunc` (follow-up to #4060, fixes #4385)

* add pull request referenz to `whats-new.rst`

Author: kmuehlbauer

doc/whats-new.rst

@@ -94,7 +94,7 @@ Documentation
 Internal Changes
 ~~~~~~~~~~~~~~~~
 - Use :py:func:`dask.array.apply_gufunc` instead of :py:func:`dask.array.blockwise` in
-  :py:func:`xarray.apply_ufunc` when using ``dask='parallelized'``. (:pull:`4060`)
+  :py:func:`xarray.apply_ufunc` when using ``dask='parallelized'``. (:pull:`4060`, :pull:`4391`)
 - Fix ``pip install .`` when no ``.git`` directory exists; namely when the xarray source
   directory has been rsync'ed by PyCharm Professional for a remote deployment over SSH.
   By `Guido Imperiale <https://github.com/crusaderky>`_

xarray/core/variable.py

@@ -1859,7 +1859,7 @@ def _wrapper(npa, **kwargs):
             exclude_dims=set(dim),
             output_core_dims=[["quantile"]],
             output_dtypes=[np.float64],
-            output_sizes={"quantile": len(q)},
+            dask_gufunc_kwargs=dict(output_sizes={"quantile": len(q)}),
             dask="parallelized",
             kwargs={"q": q, "axis": axis, "interpolation": interpolation},
         )

xarray/tests/test_computation.py

@@ -785,7 +785,7 @@ def func(x):
             output_core_dims=[["sign"]],
             dask="parallelized",
             output_dtypes=[obj.dtype],
-            output_sizes={"sign": 2},
+            dask_gufunc_kwargs=dict(output_sizes={"sign": 2}),
         )
 
     expected = stack_negative(data_array.compute())
@@ -897,7 +897,7 @@ def test_vectorize_dask_dtype_meta():
         vectorize=True,
         dask="parallelized",
         output_dtypes=[int],
-        meta=np.ndarray((0, 0), dtype=np.float),
+        dask_gufunc_kwargs=dict(meta=np.ndarray((0, 0), dtype=np.float)),
     )
 
     assert_identical(expected, actual)
@@ -1129,7 +1129,7 @@ def test_vectorize_dask_new_output_dims():
         vectorize=True,
         dask="parallelized",
         output_dtypes=[float],
-        output_sizes={"z": 1},
+        dask_gufunc_kwargs=dict(output_sizes={"z": 1}),
     ).transpose(*expected.dims)
     assert_identical(expected, actual)
 
@@ -1141,7 +1141,7 @@ def test_vectorize_dask_new_output_dims():
             vectorize=True,
             dask="parallelized",
             output_dtypes=[float],
-            output_sizes={"z1": 1},
+            dask_gufunc_kwargs=dict(output_sizes={"z1": 1}),
         )
 
     with raises_regex(