CoW: Enforce some deprecations on the block level (#57253)

Author: phofl

pandas/core/frame.py

@@ -10744,7 +10744,6 @@ def _series_round(ser: Series, decimals: int) -> Series:
             # type "Union[int, integer[Any]]"; expected "int"
             new_mgr = self._mgr.round(
                 decimals=decimals,  # type: ignore[arg-type]
-                using_cow=using_copy_on_write(),
             )
             return self._constructor_from_mgr(new_mgr, axes=new_mgr.axes).__finalize__(
                 self, method="round"

pandas/core/generic.py

@@ -6360,9 +6360,6 @@ def astype(
         2   2020-01-03
         dtype: datetime64[ns]
         """
-        if copy and using_copy_on_write():
-            copy = False
-
         if is_dict_like(dtype):
             if self.ndim == 1:  # i.e. Series
                 if len(dtype) > 1 or self.name not in dtype:
@@ -6371,7 +6368,7 @@ def astype(
                         "the key in Series dtype mappings."
                     )
                 new_type = dtype[self.name]
-                return self.astype(new_type, copy, errors)
+                return self.astype(new_type, errors=errors)
 
             # GH#44417 cast to Series so we can use .iat below, which will be
             #  robust in case we
@@ -6393,10 +6390,10 @@ def astype(
             for i, (col_name, col) in enumerate(self.items()):
                 cdt = dtype_ser.iat[i]
                 if isna(cdt):
-                    res_col = col.copy(deep=copy)
+                    res_col = col.copy(deep=False)
                 else:
                     try:
-                        res_col = col.astype(dtype=cdt, copy=copy, errors=errors)
+                        res_col = col.astype(dtype=cdt, errors=errors)
                     except ValueError as ex:
                         ex.args = (
                             f"{ex}: Error while type casting for column '{col_name}'",
@@ -6410,22 +6407,20 @@ def astype(
             if isinstance(dtype, ExtensionDtype) and all(
                 arr.dtype == dtype for arr in self._mgr.arrays
             ):
-                return self.copy(deep=copy)
+                return self.copy(deep=False)
             # GH 18099/22869: columnwise conversion to extension dtype
             # GH 24704: self.items handles duplicate column names
-            results = [
-                ser.astype(dtype, copy=copy, errors=errors) for _, ser in self.items()
-            ]
+            results = [ser.astype(dtype, errors=errors) for _, ser in self.items()]
 
         else:
             # else, only a single dtype is given
-            new_data = self._mgr.astype(dtype=dtype, copy=copy, errors=errors)
+            new_data = self._mgr.astype(dtype=dtype, errors=errors)
             res = self._constructor_from_mgr(new_data, axes=new_data.axes)
             return res.__finalize__(self, method="astype")
 
         # GH 33113: handle empty frame or series
         if not results:
-            return self.copy(deep=None)
+            return self.copy(deep=False)
 
         # GH 19920: retain column metadata after concat
         result = concat(results, axis=1, copy=False)