[libcxx-commits] [libcxx] [libc++] Granularize `<optional>` (PR #206644)

[Nikolas Klauser via libcxx-commits]

================
@@ -0,0 +1,97 @@
+// -*- 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_OPTIONAL_COMMON_H
+#define _LIBCPP_OPTIONAL_COMMON_H
+
+#include <__assert>
+#include <__config>
+#include <__exception/exception.h>
+#include <__fwd/format.h>
+#include <__ranges/enable_borrowed_range.h>
+#include <__ranges/enable_view.h>
+#include <__type_traits/integral_constant.h>
+#include <__type_traits/is_object.h>
+#include <__type_traits/is_reference.h>
+
+#include <__fwd/optional.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+namespace std // purposefully not using versioning namespace
+{
+
+class _LIBCPP_EXPORTED_FROM_ABI bad_optional_access : public exception {
+public:
+  bad_optional_access() _NOEXCEPT                                      = default;
+  bad_optional_access(const bad_optional_access&) _NOEXCEPT            = default;
+  bad_optional_access& operator=(const bad_optional_access&) _NOEXCEPT = default;
+  // Get the key function ~bad_optional_access() into the dylib
+  ~bad_optional_access() _NOEXCEPT override;
+  [[__nodiscard__]] const char* what() const _NOEXCEPT override;
+};
+
+} // namespace std
+
+#if _LIBCPP_STD_VER >= 17
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+[[noreturn]] inline void __throw_bad_optional_access() {
+#  if _LIBCPP_HAS_EXCEPTIONS
+  throw bad_optional_access();
+#  else
+  _LIBCPP_VERBOSE_ABORT("bad_optional_access was thrown in -fno-exceptions mode");
+#  endif
+}
+
+struct __optional_construct_from_invoke_tag {};
+
+template <class _Tp>
+struct __is_std_optional : false_type {};
+
+template <class _Tp>
+struct __is_std_optional<optional<_Tp>> : true_type {};
+
+template <class _Tp, bool = is_reference_v<_Tp>>
+struct __optional_storage_base;
----------------
philnik777 wrote:

Can we remove this before splitting the headers? I don't think there is any reason we need a common base class for the two.

https://github.com/llvm/llvm-project/pull/206644