Compat and encoding deprecation to 0.14

doc/whats-new.rst

@@ -45,8 +45,8 @@ Breaking changes
   - Any user code that defines custom subclasses of xarray classes must now explicitly
     define ``__slots__`` itself. Subclasses that don't add any attributes must state so
     by defining ``__slots__ = ()`` right after the class header.
-    Omitting ``__slots__`` will now cause a ``FutureWarning`` to be logged, and a hard
-    crash in a later release.
+    Omitting ``__slots__`` will now cause a ``FutureWarning`` to be logged, and will raise an
+    error in a later release.
 
   (:issue:`3250`) by `Guido Imperiale <https://github.com/crusaderky>`_.
 - :py:meth:`~Dataset.to_dataset` requires ``name`` to be passed as a kwarg (previously ambiguous 
@@ -56,6 +56,8 @@ Breaking changes
   :py:func:`~xarray.broadcast`)
 - :py:meth:`~Variable.expand_dims` is removed (previously deprecated in favor of 
   :py:meth:`~Variable.set_dims`)
+- :py:func:`~xarray.concat` now requries the ``dim`` argument (using ``'concat_dim'`` as a default
+  was previouly deprecated)
 
 New functions/methods
 ~~~~~~~~~~~~~~~~~~~~~

xarray/core/concat.py

@@ -112,14 +112,7 @@ def concat(
         raise ValueError("must supply at least one object to concatenate")
 
     if dim is None:
-        warnings.warn(
-            "the `dim` argument to `concat` will be required "
-            "in a future version of xarray; for now, setting it to "
-            "the old default of 'concat_dim'",
-            FutureWarning,
-            stacklevel=2,
-        )
-        dim = "concat_dims"
+        raise TypeError("the `dim` argument to `concat` is required")
 
     if indexers is not None:  # pragma: no cover
         warnings.warn(

xarray/core/dataarray.py

@@ -315,7 +315,7 @@ def __init__(
         if encoding is not None:
             warnings.warn(
                 "The `encoding` argument to `DataArray` is deprecated, and . "
-                "will be removed in 0.13. "
+                "will be removed in 0.14. "
                 "Instead, specify the encoding when writing to disk or "
                 "set the `encoding` attribute directly.",
                 FutureWarning,

xarray/core/dataset.py

@@ -489,7 +489,7 @@ def __init__(
         if compat is not None:
             warnings.warn(
                 "The `compat` argument to Dataset is deprecated and will be "
-                "removed in 0.13."
+                "removed in 0.14."
                 "Instead, use `merge` to control how variables are combined",
                 FutureWarning,
                 stacklevel=2,