CLN: Cython Groupby unused argument removal (pandas-dev#53506)

Author: WillAyd

pandas/_libs/groupby.pyx

@@ -495,7 +495,6 @@ def group_fillna_indexer(
     ndarray[intp_t] labels,
     ndarray[intp_t] sorted_labels,
     ndarray[uint8_t] mask,
-    str direction,
     int64_t limit,
     bint dropna,
 ) -> None:
@@ -510,14 +509,11 @@ def group_fillna_indexer(
         Array containing unique label for each group, with its ordering
         matching up to the corresponding record in `values`.
     sorted_labels : np.ndarray[np.intp]
-        obtained by `np.argsort(labels, kind="mergesort")`; reversed if
-        direction == "bfill"
+        obtained by `np.argsort(labels, kind="mergesort")`
     values : np.ndarray[np.uint8]
         Containing the truth value of each element.
     mask : np.ndarray[np.uint8]
         Indicating whether a value is na or not.
-    direction : {'ffill', 'bfill'}
-        Direction for fill to be applied (forwards or backwards, respectively)
     limit : Consecutive values to fill before stopping, or -1 for no limit
     dropna : Flag to indicate if NaN groups should return all NaN values
 

pandas/core/groupby/groupby.py

@@ -2924,7 +2924,6 @@ def _fill(self, direction: Literal["ffill", "bfill"], limit: int | None = None):
             libgroupby.group_fillna_indexer,
             labels=ids,
             sorted_labels=sorted_labels,
-            direction=direction,
             limit=limit,
             dropna=self.dropna,
         )