Deprecate windowslinetermination CSV option

cpp/benchmarks/io/csv/csv_reader_options.cpp

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: Copyright (c) 2022-2026, NVIDIA CORPORATION.
+ * SPDX-FileCopyrightText: Copyright (c) 2022-2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
  * SPDX-License-Identifier: Apache-2.0
  */
 
@@ -51,7 +51,6 @@ void BM_csv_read_varying_options(
       .compression(cudf::io::compression_type::NONE)
       .use_cols_indexes(cols_to_read)
       .thousands('\'')
-      .windowslinetermination(true)
       .comment('#')
       .prefix("BM_");
 

cpp/include/cudf/io/csv.hpp

@@ -325,9 +325,16 @@ class csv_reader_options {
   /**
    * @brief Whether to treat `\r\n` as line terminator.
    *
+   * @deprecated Deprecated in 26.10 and will be removed in 26.12+. CRLF input is supported using
+   * the default `\n` line terminator.
+   *
    * @return `true` if `\r\n` is treated as line terminator
    */
-  [[nodiscard]] bool is_enabled_windowslinetermination() const { return _windowslinetermination; }
+  [[nodiscard]] [[deprecated("CRLF input is supported using the default `\\n` line terminator.")]]
+  bool is_enabled_windowslinetermination() const
+  {
+    return _windowslinetermination;
+  }
 
   /**
    * @brief Whether to treat whitespace as field delimiter.
@@ -657,9 +664,16 @@ class csv_reader_options {
   /**
    * @brief Sets whether to treat `\r\n` as line terminator.
    *
+   * @deprecated Deprecated in 26.10 and will be removed in 26.12+. CRLF input is supported using
+   * the default `\n` line terminator.
+   *
    * @param val Boolean value to enable/disable
    */
-  void enable_windowslinetermination(bool val) { _windowslinetermination = val; }
+  [[deprecated("CRLF input is supported using the default `\\n` line terminator.")]]
+  void enable_windowslinetermination(bool val)
+  {
+    _windowslinetermination = val;
+  }
 
   /**
    * @brief Sets whether to treat whitespace as field delimiter.
@@ -1065,12 +1079,16 @@ class csv_reader_options_builder {
   /**
    * @brief Sets whether to treat `\r\n` as line terminator.
    *
+   * @deprecated Deprecated in 26.10 and will be removed in 26.12+. CRLF input is supported using
+   * the default `\n` line terminator.
+   *
    * @param val Boolean value to enable/disable
    * @return this for chaining
    */
+  [[deprecated("CRLF input is supported using the default `\\n` line terminator.")]]
   csv_reader_options_builder& windowslinetermination(bool val)
   {
-    options.enable_windowslinetermination(val);
+    options._windowslinetermination = val;
     return *this;
   }
 

cpp/tests/io/csv_test.cpp

@@ -946,6 +946,24 @@ TEST_F(CsvReaderTest, Strings)
     view.column(1));
 }
 
+TEST_F(CsvReaderTest, WindowsLineTerminators)
+{
+  std::string const buffer{"1,alpha\r\n2,beta\r\n"};
+  auto options =
+    cudf::io::csv_reader_options::builder(
+      cudf::io::source_info{cudf::host_span<std::byte const>{
+        reinterpret_cast<std::byte const*>(buffer.data()), buffer.size()}})
+      .dtypes(std::vector<data_type>{data_type{type_id::INT64}, data_type{type_id::STRING}})
+      .header(-1);
+
+  auto const result = cudf::io::read_csv(options);
+
+  cudf::test::fixed_width_column_wrapper<int64_t> const expected_values{1, 2};
+  cudf::test::strings_column_wrapper const expected_names{"alpha", "beta"};
+  table_view const expected{{expected_values, expected_names}};
+  CUDF_TEST_EXPECT_TABLES_EQUIVALENT(expected, result.tbl->view());
+}
+
 TEST_F(CsvReaderTest, StringsQuotes)
 {
   std::vector<std::string> names{"line", "verse"};