1 files changed, 64 insertions, 0 deletions
diff --git a/libcxx/include/__expected/bad_expected_access.h b/libcxx/include/__expected/bad_expected_access.h
new file mode 100644
index 000000000000..361eab4b6018
--- /dev/null
+++ b/libcxx/include/__expected/bad_expected_access.h
@@ -0,0 +1,64 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// 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___EXPECTED_BAD_EXPECTED_ACCESS_H
+#define _LIBCPP___EXPECTED_BAD_EXPECTED_ACCESS_H
+
+#include <__config>
+#include <__utility/move.h>
+
+#include <exception>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER >= 23
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Err>
+class bad_expected_access;
+
+template <>
+class bad_expected_access<void> : public exception {
+protected:
+  _LIBCPP_HIDE_FROM_ABI bad_expected_access() noexcept                             = default;
+  _LIBCPP_HIDE_FROM_ABI bad_expected_access(const bad_expected_access&)            = default;
+  _LIBCPP_HIDE_FROM_ABI bad_expected_access(bad_expected_access&&)                 = default;
+  _LIBCPP_HIDE_FROM_ABI bad_expected_access& operator=(const bad_expected_access&) = default;
+  _LIBCPP_HIDE_FROM_ABI bad_expected_access& operator=(bad_expected_access&&)      = default;
+  ~bad_expected_access() override                                                  = default;
+
+public:
+  // The way this has been designed (by using a class template below) means that we'll already
+  // have a profusion of these vtables in TUs, and the dynamic linker will already have a bunch
+  // of work to do. So it is not worth hiding the <void> specialization in the dylib, given that
+  // it adds deployment target restrictions.
+  const char* what() const noexcept override { return "bad access to std::expected"; }
+};
+
+template <class _Err>
+class bad_expected_access : public bad_expected_access<void> {
+public:
+  _LIBCPP_HIDE_FROM_ABI explicit bad_expected_access(_Err __e) : __unex_(std::move(__e)) {}
+
+  _LIBCPP_HIDE_FROM_ABI _Err& error() & noexcept { return __unex_; }
+  _LIBCPP_HIDE_FROM_ABI const _Err& error() const& noexcept { return __unex_; }
+  _LIBCPP_HIDE_FROM_ABI _Err&& error() && noexcept { return std::move(__unex_); }
+  _LIBCPP_HIDE_FROM_ABI const _Err&& error() const&& noexcept { return std::move(__unex_); }
+
+private:
+  _Err __unex_;
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER >= 23
+
+#endif // _LIBCPP___EXPECTED_BAD_EXPECTED_ACCESS_H