use built-in non-hashable message

Author: MarcoGorelli

pandas/core/generic.py

@@ -1872,16 +1872,10 @@ def _drop_labels_or_levels(self, keys, axis: int = 0):
     # ----------------------------------------------------------------------
     # Iteration
 
-    def _hash(self) -> int:
-        raise TypeError(
-            f"{repr(type(self).__name__)} objects are mutable, "
-            f"thus they cannot be hashed"
-        )
-
     # 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 = _hash  # type: ignore[assignment]
+    __hash__: None  # type: ignore[assignment]
 
     def __iter__(self):
         """

pandas/tests/frame/test_api.py

@@ -91,7 +91,7 @@ def test_not_hashable(self):
         empty_frame = DataFrame()
 
         df = DataFrame([1])
-        msg = "'DataFrame' objects are mutable, thus they cannot be hashed"
+        msg = "unhashable type: 'DataFrame'"
         with pytest.raises(TypeError, match=msg):
             hash(df)
         with pytest.raises(TypeError, match=msg):

pandas/tests/series/test_api.py

@@ -101,7 +101,7 @@ def test_index_tab_completion(self, index):
     def test_not_hashable(self):
         s_empty = Series(dtype=object)
         s = Series([1])
-        msg = "'Series' objects are mutable, thus they cannot be hashed"
+        msg = "unhashable type: 'Series'"
         with pytest.raises(TypeError, match=msg):
             hash(s_empty)
         with pytest.raises(TypeError, match=msg):