整理

include/boost/pfr/detail/core17.hpp

@@ -0,0 +1,72 @@
+// Copyright (c) 2016-2025 Antony Polukhin
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+
+#ifndef BOOST_PFR_DETAIL_CORE17_HPP
+#define BOOST_PFR_DETAIL_CORE17_HPP
+#pragma once
+
+#include <boost/pfr/detail/core17_generated.hpp>
+#include <boost/pfr/detail/fields_count.hpp>
+#include <boost/pfr/detail/for_each_field_impl.hpp>
+#include <boost/pfr/detail/rvalue_t.hpp>
+
+namespace boost { namespace pfr { namespace detail {
+
+#ifndef _MSC_VER // MSVC fails to compile the following code, but compiles the structured bindings in core17_generated.hpp
+struct do_not_define_std_tuple_size_for_me {
+    bool test1 = true;
+};
+
+template <class T>
+constexpr bool do_structured_bindings_work() noexcept { // ******************************************* IN CASE OF ERROR READ THE FOLLOWING LINES IN boost/pfr/detail/core17.hpp FILE:
+    T val{};
+    auto& [a] = val; // ******************************************* IN CASE OF ERROR READ THE FOLLOWING LINES IN boost/pfr/detail/core17.hpp FILE:
+
+    /****************************************************************************
+    *
+    * It looks like your compiler or Standard Library can not handle C++17
+    * structured bindings.
+    *
+    * Workaround: Define BOOST_PFR_USE_CPP17 to 0
+    * It will disable the C++17 features for Boost.PFR library.
+    *
+    * Sorry for the inconvenience caused.
+    *
+    ****************************************************************************/
+
+    return a;
+}
+
+static_assert(
+    do_structured_bindings_work<do_not_define_std_tuple_size_for_me>(),
+    "====================> Boost.PFR: Your compiler can not handle C++17 structured bindings. Read the above comments for workarounds."
+);
+#endif // #ifndef _MSC_VER
+
+template <class T>
+constexpr auto tie_as_tuple(T& val) noexcept {
+  static_assert(
+    !std::is_union<T>::value,
+    "====================> Boost.PFR: For safety reasons it is forbidden to reflect unions. See `Reflection of unions` section in the docs for more info."
+  );
+  typedef size_t_<boost::pfr::detail::fields_count<T>()> fields_count_tag;
+  return boost::pfr::detail::tie_as_tuple(val, fields_count_tag{});
+}
+
+template <class T, class F, std::size_t... I>
+constexpr void for_each_field_dispatcher(T& t, F&& f, std::index_sequence<I...>) {
+    static_assert(
+        !std::is_union<T>::value,
+        "====================> Boost.PFR: For safety reasons it is forbidden to reflect unions. See `Reflection of unions` section in the docs for more info."
+    );
+    std::forward<F>(f)(
+        detail::tie_as_tuple(t)
+    );
+}
+
+}}} // namespace boost::pfr::detail
+
+#endif // BOOST_PFR_DETAIL_CORE17_HPP