Move cudf::lists::detail::make_empty_lists_column to public API

cpp/include/cudf/column/column_factories.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019-2024, NVIDIA CORPORATION.
+ * Copyright (c) 2019-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -516,6 +516,21 @@ std::unique_ptr<cudf::column> make_lists_column(
   rmm::cuda_stream_view stream      = cudf::get_default_stream(),
   rmm::device_async_resource_ref mr = cudf::get_current_device_resource_ref());
 
+/**
+ * @brief Create an empty LIST column
+ *
+ * A list column requires a child type and so cannot be created with `make_empty_column`.
+ *
+ * @param child_type The type used for the empty child column
+ * @param stream CUDA stream used for device memory operations and kernel launches
+ * @param mr Device memory resource used to allocate the returned column's device memory
+ * @return New empty lists column
+ */
+std::unique_ptr<column> make_empty_lists_column(
+  data_type child_type,
+  rmm::cuda_stream_view stream      = cudf::get_default_stream(),
+  rmm::device_async_resource_ref mr = cudf::get_current_device_resource_ref());
+
 /**
  * @brief Construct a STRUCT column using specified child columns as members.
  *

cpp/src/lists/lists_column_factories.cu

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020-2024, NVIDIA CORPORATION.
+ * Copyright (c) 2020-2025, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -112,6 +112,13 @@ std::unique_ptr<column> make_all_nulls_lists_column(size_type size,
 }  // namespace detail
 }  // namespace lists
 
+std::unique_ptr<column> make_empty_lists_column(data_type child_type,
+                                                rmm::cuda_stream_view stream,
+                                                rmm::device_async_resource_ref mr)
+{
+  return lists::detail::make_empty_lists_column(child_type, stream, mr);
+}
+
 /**
  * @copydoc cudf::make_lists_column
  */
@@ -144,6 +151,8 @@ std::unique_ptr<column> make_lists_column(size_type num_rows,
                                          null_count,
                                          std::move(children));
 
+  if (num_rows == 0) { return output; }
+
   // We need to enforce all null lists to be empty.
   // `has_nonempty_nulls` is less expensive than `purge_nonempty_nulls` and can save some
   // run time if we don't have any non-empty nulls.

cpp/src/lists/sequences.cu

@@ -156,7 +156,7 @@ std::unique_ptr<column> sequences(column_view const& starts,
   }
 
   auto const n_lists = starts.size();
-  if (n_lists == 0) { return make_empty_lists_column(starts.type(), stream, mr); }
+  if (n_lists == 0) { return cudf::make_empty_lists_column(starts.type(), stream, mr); }
 
   // Generate list offsets for the output.
   auto list_offsets = make_numeric_column(