1 files changed, 38 insertions, 0 deletions
diff --git a/libcxx/include/__fwd/subrange.h b/libcxx/include/__fwd/subrange.h
new file mode 100644
index 000000000000..8f7239247eff
--- /dev/null
+++ b/libcxx/include/__fwd/subrange.h
@@ -0,0 +1,38 @@
+//===---------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===---------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___FWD_SUBRANGE_H
+#define _LIBCPP___FWD_SUBRANGE_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER >= 20
+
+#include <__iterator/concepts.h>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace ranges {
+
+enum class _LIBCPP_ENUM_VIS subrange_kind : bool { unsized, sized };
+
+template <input_or_output_iterator _Iter, sentinel_for<_Iter> _Sent, subrange_kind _Kind>
+  requires(_Kind == subrange_kind::sized || !sized_sentinel_for<_Sent, _Iter>)
+class _LIBCPP_TEMPLATE_VIS subrange;
+
+} // namespace ranges
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER >= 20
+
+#endif // _LIBCPP___FWD_SUBRANGE_H