WIP commit before merge

Underlying numba chnages has broken my local testing.  Preparing to resync with main branch to resolve.

Signed-off-by: Michael Tiemann <[email protected]>

pandas/core/arrays/base.py

@@ -292,14 +292,17 @@ def _from_sequence(cls, scalars, *, dtype: Dtype | None = None, copy: bool = Fal
         raise AbstractMethodError(cls)
 
     @classmethod
-    def _from_scalars(cls, scalars, *, dtype: DtypeObj) -> Self:
+    def _from_scalars(cls, scalars, *, dtype: DtypeObj | None = None) -> Self:
         """
         Strict analogue to _from_sequence, allowing only sequences of scalars
         that should be specifically inferred to the given dtype.
         Parameters
         ----------
         scalars : sequence
-        dtype : ExtensionDtype
+        dtype : ExtensionDtype, optional
+            This could be a Dtype competible with the ExtensionArray,
+            but it is up to _from_scalars to choose (from scalars,
+            dtype, or however) the ultimate dtype for the return value.
         Raises
         ------
         TypeError or ValueError

pandas/core/internals/managers.py

@@ -971,30 +971,22 @@ def fast_xs(self, loc: int) -> SingleBlockManager:
 
         if isinstance(dtype, ExtensionDtype) and not immutable_ea:
             cls = dtype.construct_array_type()
-        else:
-            cls = None
-
-        if hasattr(cls, "_from_scalars"):
-            obj = self.blocks[0].iget((slice(None), loc))
             result = cls._from_scalars(
                 [
                     blk.iget((i, loc))
                     for blk in self.blocks
-                    for i, rl in enumerate(blk.mgr_locs)
+                    for i, _ in enumerate(blk.mgr_locs)
                 ],
-                dtype=obj.dtype,
+                dtype=dtype,
             )
         else:
-            if cls is not None:
-                result = cls._empty((n,), dtype=dtype)
-            else:
-                # error: Argument "dtype" to "empty" has incompatible type
-                # "Union[Type[object], dtype[Any], ExtensionDtype, None]"; expected
-                # "None"
-                result = np.empty(
-                    n, dtype=object if immutable_ea else dtype  # type: ignore[arg-type]
-                )
-                result = ensure_wrapped_if_datetimelike(result)
+            # error: Argument "dtype" to "empty" has incompatible type
+            # "Union[Type[object], dtype[Any], ExtensionDtype, None]"; expected
+            # "None"
+            result = np.empty(
+                n, dtype=object if immutable_ea else dtype  # type: ignore[arg-type]
+            )
+            result = ensure_wrapped_if_datetimelike(result)
 
             for blk in self.blocks:
                 # Such assignment may incorrectly coerce NaT to None