C++ refactoring: Don't let ak.to_list act on v2 arrays (finishing #1201).

src/awkward/_v2/contents/content.py

@@ -477,7 +477,7 @@ def __getitem__(self, where):
                 and where._parameters is not None
                 and (where._parameters.get("__array__") in ("string", "bytestring"))
             ):
-                return self._getitem_fields(ak.to_list(where))
+                return self._getitem_fields(ak._v2.operations.convert.to_list(where))
 
             elif isinstance(where, ak._v2.contents.emptyarray.EmptyArray):
                 return where.toNumpyArray(np.int64)

src/awkward/operations/convert.py

@@ -1008,12 +1008,10 @@ def to_list(array):
             ak._v2.highlevel.Record,
             ak._v2.contents.Content,
             ak._v2.record.Record,
+            ak._v2.highlevel.ArrayBuilder,
         ),
     ):
-        return array.to_list()
-
-    elif isinstance(array, ak._v2.highlevel.ArrayBuilder):
-        return array.snapshot().to_list()
+        raise TypeError("use ak._v2.operations.convert.to_list for v2 arrays (for now)")
 
     elif isinstance(array, dict):
         return dict((n, to_list(x)) for n, x in array.items())

tests/v2/test_0111-jagged-and-masked-getitem.py

@@ -180,7 +180,9 @@ def test_array_slice_1():
         check_valid=True,
     ).layout
     array = v1_to_v2(array)
-    assert to_list(array[ak.from_iter(["y", "x"], highlevel=False)]) == [
+    assert to_list(
+        array[ak._v2.operations.convert.from_iter(["y", "x"], highlevel=False)]
+    ) == [
         {"y": 1.1, "x": 1},
         {"y": 2.2, "x": 2},
         {"y": 3.3, "x": 3},