Use old kwarg values within map_blocks, concat dataarray

xarray/core/alignment.py

@@ -439,19 +439,16 @@ def align_indexes(self) -> None:
                             stacklevel=2,
                         )
                     if self.join == "exact":
-                        new_default_warning = (
-                            " Failure might be related to new default (join='exact'). "
-                            "Previously the default was join='outer'. "
-                            "The recommendation is to set join explicitly for this case."
-                        )
                         raise ValueError(
                             "cannot align objects with join='exact' where "
                             "index/labels/sizes are not equal along "
                             "these coordinates (dimensions): "
                             + ", ".join(f"{name!r} {dims!r}" for name, dims in key[0])
-                            + new_default_warning
-                            if isinstance(self.join, CombineKwargDefault)
-                            else ""
+                            + (
+                                self.join.error_message()
+                                if isinstance(self.join, CombineKwargDefault)
+                                else ""
+                            )
                         )
                     joiner = self._get_index_joiner(index_cls)
                     joined_index = joiner(matching_indexes)

xarray/core/concat.py

@@ -368,12 +368,10 @@ def process_subset_opt(opt, subset):
         if isinstance(opt, str | CombineKwargDefault):
             if opt == "different":
                 if isinstance(compat, CombineKwargDefault) and compat != "override":
-                    if subset == "data_vars" or not isinstance(
-                        opt, CombineKwargDefault
-                    ):
+                    if not isinstance(opt, CombineKwargDefault):
                         warnings.warn(
                             compat.warning_message(
-                                "This change will result in the following ValueError:"
+                                "This change will result in the following ValueError: "
                                 f"Cannot specify both {subset}='different' and compat='override'.",
                                 recommend_set_options=False,
                             ),
@@ -382,16 +380,13 @@ def process_subset_opt(opt, subset):
                         )
 
                 if compat == "override":
-                    new_default_warning = (
-                        " Failure might be related to new default (compat='override'). "
-                        "Previously the default was compat='equals' or compat='no_conflicts'. "
-                        "The recommendation is to set compat explicitly for this case."
-                    )
                     raise ValueError(
                         f"Cannot specify both {subset}='different' and compat='override'."
-                        + new_default_warning
-                        if isinstance(compat, CombineKwargDefault)
-                        else ""
+                        + (
+                            compat.error_message()
+                            if isinstance(compat, CombineKwargDefault)
+                            else ""
+                        )
                     )
                 # all nonindexes that are not the same in each dataset
                 for k in getattr(datasets[0], subset):
@@ -469,7 +464,7 @@ def process_subset_opt(opt, subset):
             ):
                 warnings.warn(
                     opt.warning_message(
-                        "This is likely to lead to different results when multiple datasets"
+                        "This is likely to lead to different results when multiple datasets "
                         "have matching variables with overlapping values.",
                     ),
                     category=FutureWarning,
@@ -800,7 +795,10 @@ def _dataarray_concat(
             "The elements in the input list need to be either all 'Dataset's or all 'DataArray's"
         )
 
-    if not isinstance(data_vars, CombineKwargDefault) and data_vars != "all":
+    if not isinstance(data_vars, CombineKwargDefault) and data_vars not in [
+        "all",
+        "minimal",
+    ]:
         raise ValueError(
             "data_vars is not a valid argument when concatenating DataArray objects"
         )
@@ -819,7 +817,7 @@ def _dataarray_concat(
     ds = _dataset_concat(
         datasets,
         dim=dim,
-        data_vars=data_vars,
+        data_vars="all",
         coords=coords,
         compat=compat,
         positions=positions,

xarray/core/merge.py

@@ -308,7 +308,7 @@ def merge_collected(
                     ):
                         warnings.warn(
                             compat.warning_message(
-                                "This is likely to lead to different results when"
+                                "This is likely to lead to different results when "
                                 "combining overlapping variables with the same name.",
                             ),
                             category=FutureWarning,

xarray/core/options.py

@@ -86,7 +86,7 @@ class T_Options(TypedDict):
     "warn_for_unclosed_files": False,
     "use_bottleneck": True,
     "use_flox": True,
-    "use_new_combine_kwarg_defaults": False,
+    "use_new_combine_kwarg_defaults": True,
     "use_numbagg": True,
     "use_opt_einsum": True,
 }
@@ -255,7 +255,14 @@ class set_options:
         Whether to use ``numpy_groupies`` and `flox`` to
         accelerate groupby and resampling reductions.
     use_new_combine_kwarg_defaults : bool, default False
-        Whether to use new default kwarg values for open_mfdataset.
+        Whether to use new kwarg default values for combine functions:
+        :py:func:`~xarray.concat`, :py:func:`~xarray.merge`,
+        :py:func:`~xarray.open_mfdataset`. New values are:
+
+        * ``data_vars``: "minimal"
+        * ``coords``: "minimal"
+        * ``compat``: "override"
+        * ``join``: "exact"
     use_numbagg : bool, default: True
         Whether to use ``numbagg`` to accelerate reductions.
         Takes precedence over ``use_bottleneck`` when both are True.

xarray/core/parallel.py

@@ -351,7 +351,9 @@ def _wrapper(
         result = func(*converted_args, **kwargs)
 
         merged_coordinates = merge(
-            [arg.coords for arg in args if isinstance(arg, Dataset | DataArray)]
+            [arg.coords for arg in args if isinstance(arg, Dataset | DataArray)],
+            join="outer",
+            compat="no_conflicts",
         ).coords
 
         # check all dims are present
@@ -439,7 +441,9 @@ def _wrapper(
     # rechunk any numpy variables appropriately
     xarray_objs = tuple(arg.chunk(arg.chunksizes) for arg in xarray_objs)
 
-    merged_coordinates = merge([arg.coords for arg in aligned]).coords
+    merged_coordinates = merge(
+        [arg.coords for arg in aligned], join="outer", compat="no_conflicts"
+    ).coords
 
     _, npargs = unzip(
         sorted(
@@ -472,7 +476,9 @@ def _wrapper(
         )
 
         coordinates = merge(
-            (preserved_coords, template.coords.to_dataset()[new_coord_vars])
+            (preserved_coords, template.coords.to_dataset()[new_coord_vars]),
+            join="outer",
+            compat="no_conflicts",
         ).coords
         output_chunks: Mapping[Hashable, tuple[int, ...]] = {
             dim: input_chunks[dim] for dim in template.dims if dim in input_chunks

xarray/util/deprecation_helpers.py

@@ -194,6 +194,13 @@ def warning_message(self, message: str, recommend_set_options: bool = True):
             + recommendation
         )
 
+    def error_message(self):
+        return (
+            f" Error might be related to new default ({self._name}={self._new!r}). "
+            f"Previously the default was {self._name}={self._old!r}. "
+            f"The recommendation is to set {self._name} explicitly for this case."
+        )
+
 
 _DATA_VARS_DEFAULT = CombineKwargDefault(name="data_vars", old="all", new="minimal")
 _COORDS_DEFAULT = CombineKwargDefault(name="coords", old="different", new="minimal")