remove default value for raise_on_upcast

Author: MarcoGorelli

pandas/core/internals/blocks.py

@@ -428,7 +428,7 @@ def split_and_operate(self, func, *args, **kwargs) -> list[Block]:
     # Up/Down-casting
 
     @final
-    def coerce_to_target_dtype(self, other, raise_on_upcast: bool = False) -> Block:
+    def coerce_to_target_dtype(self, other, raise_on_upcast: bool) -> Block:
         """
         coerce the current block to a dtype compat for other
         we will return a block, possibly object, and not raise
@@ -713,7 +713,7 @@ def replace(
             if value is None or value is NA:
                 blk = self.astype(np.dtype(object))
             else:
-                blk = self.coerce_to_target_dtype(value)
+                blk = self.coerce_to_target_dtype(value, raise_on_upcast=False)
             return blk.replace(
                 to_replace=to_replace,
                 value=value,
@@ -1237,7 +1237,7 @@ def where(self, other, cond) -> list[Block]:
             if self.ndim == 1 or self.shape[0] == 1:
                 # no need to split columns
 
-                block = self.coerce_to_target_dtype(other)
+                block = self.coerce_to_target_dtype(other, raise_on_upcast=False)
                 return block.where(orig_other, cond)
 
             else:
@@ -1431,7 +1431,7 @@ def shift(self, periods: int, fill_value: Any = None) -> list[Block]:
                 fill_value,
             )
         except LossySetitemError:
-            nb = self.coerce_to_target_dtype(fill_value)
+            nb = self.coerce_to_target_dtype(fill_value, raise_on_upcast=False)
             return nb.shift(periods, fill_value=fill_value)
 
         else:
@@ -1669,13 +1669,13 @@ def where(self, other, cond) -> list[Block]:
             if self.ndim == 1 or self.shape[0] == 1:
                 if isinstance(self.dtype, IntervalDtype):
                     # TestSetitemFloatIntervalWithIntIntervalValues
-                    blk = self.coerce_to_target_dtype(orig_other)
+                    blk = self.coerce_to_target_dtype(orig_other, raise_on_upcast=False)
                     return blk.where(orig_other, orig_cond)
 
                 elif isinstance(self, NDArrayBackedExtensionBlock):
                     # NB: not (yet) the same as
                     #  isinstance(values, NDArrayBackedExtensionArray)
-                    blk = self.coerce_to_target_dtype(orig_other)
+                    blk = self.coerce_to_target_dtype(orig_other, raise_on_upcast=False)
                     return blk.where(orig_other, orig_cond)
 
                 else:

web/pandas/pdeps/0006-ban-upcasting.md

@@ -1,7 +1,7 @@
 # PDEP-6: Ban upcasting in setitem-like operations
 
 - Created: 23 December 2022
-- Status: Accepted
+- Status: Implemented
 - Discussion: [#39584](https://github.com/pandas-dev/pandas/pull/50402)
 - Author: [Marco Gorelli](https://github.com/MarcoGorelli) ([original issue](https://github.com/pandas-dev/pandas/issues/39584) by [Joris Van den Bossche](https://github.com/jorisvandenbossche))
 - Revision: 1
@@ -244,3 +244,4 @@ Deprecate sometime in the 2.x releases (after 2.0.0 has already been released),
 ### PDEP History
 
 - 23 December 2022: Initial draft
+- 4 July 2024: Change status to "implemented"