Minor fixes to pass a couple build tests.

Author: vijmeister

doc/source/whatsnew/v3.0.0.rst

@@ -1266,6 +1266,7 @@ Other
 - Fixed bug in the :meth:`Series.rank` with object dtype and extremely small float values (:issue:`62036`)
 - Fixed bug where the :class:`DataFrame` constructor misclassified array-like objects with a ``.name`` attribute as :class:`Series` or :class:`Index` (:issue:`61443`)
 - Fixed regression in :meth:`DataFrame.from_records` not initializing subclasses properly (:issue:`57008`)
+
 .. ***DO NOT USE THIS SECTION***
 
 -

pandas/core/frame.py

@@ -9109,13 +9109,17 @@ def combine(
 
         new_columns_out = self.columns.union(other_columns, sort=False)
         # Deduplicate column names if necessary
-        self_columns = Index(dedup_names(self_columns, False), dtype=self_columns.dtype)
+        self_columns = Index(
+            dedup_names(list(self_columns), False), dtype=self_columns.dtype
+        )
         other_columns = Index(
-            dedup_names(other_columns, False), dtype=other_columns.dtype
+            dedup_names(list(other_columns), False), dtype=other_columns.dtype
+        )
+        this.columns = Index(
+            dedup_names(list(this.columns), False), dtype=this.columns.dtype
         )
-        this.columns = Index(dedup_names(this.columns, False), dtype=this.columns.dtype)
         other.columns = Index(
-            dedup_names(other.columns, False), dtype=other.columns.dtype
+            dedup_names(list(other.columns), False), dtype=other.columns.dtype
         )
 
         # preserve column order