TYP: fix some of the __hash__ methods (pandas-dev#47654)

Author: twoertwein

pandas/core/arrays/arrow/_arrow_utils.py

@@ -92,7 +92,7 @@ def __eq__(self, other):
         else:
             return NotImplemented
 
-    def __hash__(self):
+    def __hash__(self) -> int:
         return hash((str(self), self.freq))
 
     def to_pandas_dtype(self):
@@ -158,7 +158,7 @@ def __eq__(self, other):
         else:
             return NotImplemented
 
-    def __hash__(self):
+    def __hash__(self) -> int:
         return hash((str(self), str(self.subtype), self.inclusive))
 
     def to_pandas_dtype(self):

pandas/core/arrays/base.py

@@ -14,6 +14,7 @@
     TYPE_CHECKING,
     Any,
     Callable,
+    ClassVar,
     Iterator,
     Literal,
     Sequence,
@@ -1442,7 +1443,7 @@ def _reduce(self, name: str, *, skipna: bool = True, **kwargs):
     # https://github.com/python/typeshed/issues/2148#issuecomment-520783318
     # Incompatible types in assignment (expression has type "None", base class
     # "object" defined the type as "Callable[[object], int]")
-    __hash__: None  # type: ignore[assignment]
+    __hash__: ClassVar[None]  # type: ignore[assignment]
 
     # ------------------------------------------------------------------------
     # Non-Optimized Default Methods; in the case of the private methods here,

pandas/core/arrays/sparse/dtype.py

@@ -99,7 +99,7 @@ def __init__(self, dtype: Dtype = np.float64, fill_value: Any = None) -> None:
         self._fill_value = fill_value
         self._check_fill_value()
 
-    def __hash__(self):
+    def __hash__(self) -> int:
         # Python3 doesn't inherit __hash__ when a base class overrides
         # __eq__, so we explicitly do it here.
         return super().__hash__()

pandas/core/generic.py

@@ -13,6 +13,7 @@
     TYPE_CHECKING,
     Any,
     Callable,
+    ClassVar,
     Hashable,
     Literal,
     Mapping,
@@ -1882,7 +1883,7 @@ def _drop_labels_or_levels(self, keys, axis: int = 0):
     # https://github.com/python/typeshed/issues/2148#issuecomment-520783318
     # Incompatible types in assignment (expression has type "None", base class
     # "object" defined the type as "Callable[[object], int]")
-    __hash__: None  # type: ignore[assignment]
+    __hash__: ClassVar[None]  # type: ignore[assignment]
 
     def __iter__(self):
         """

pandas/core/indexes/base.py

@@ -8,6 +8,7 @@
     TYPE_CHECKING,
     Any,
     Callable,
+    ClassVar,
     Hashable,
     Iterable,
     Literal,
@@ -5296,7 +5297,7 @@ def __contains__(self, key: Any) -> bool:
     # https://github.com/python/typeshed/issues/2148#issuecomment-520783318
     # Incompatible types in assignment (expression has type "None", base class
     # "object" defined the type as "Callable[[object], int]")
-    __hash__: None  # type: ignore[assignment]
+    __hash__: ClassVar[None]  # type: ignore[assignment]
 
     @final
     def __setitem__(self, key, value):

pandas/core/indexes/frozen.py

@@ -89,7 +89,8 @@ def __mul__(self, other):
     def __reduce__(self):
         return type(self), (list(self),)
 
-    def __hash__(self):
+    # error: Signature of "__hash__" incompatible with supertype "list"
+    def __hash__(self) -> int:  # type: ignore[override]
         return hash(tuple(self))
 
     def _disabled(self, *args, **kwargs):