TYP: overload tz_to_dtype (#56260)

Author: jbrockmendel

pandas/core/arrays/datetimes.py

@@ -8,6 +8,7 @@
 from typing import (
     TYPE_CHECKING,
     cast,
+    overload,
 )
 import warnings
 
@@ -93,6 +94,16 @@
 _ITER_CHUNKSIZE = 10_000
 
 
+@overload
+def tz_to_dtype(tz: tzinfo, unit: str = ...) -> DatetimeTZDtype:
+    ...
+
+
+@overload
+def tz_to_dtype(tz: None, unit: str = ...) -> np.dtype[np.datetime64]:
+    ...
+
+
 def tz_to_dtype(
     tz: tzinfo | None, unit: str = "ns"
 ) -> np.dtype[np.datetime64] | DatetimeTZDtype: