Workaround missing std::bit_cast on some compilers

src/core/bit_cast.hpp

@@ -0,0 +1,35 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file bit_cast.hpp std::bit_cast fallback */
+
+#ifndef BIT_CAST_HPP
+#define BIT_CAST_HPP
+
+#ifdef __cpp_lib_bit_cast
+
+#include <bit>
+
+#else
+
+#include <type_traits>
+
+namespace std {
+template <typename To, typename From>
+constexpr To bit_cast(const From& from) noexcept
+{
+	static_assert(std::is_trivially_constructible_v<To>);
+
+	To to;
+	memcpy(&to, &from, sizeof(To));
+	return to;
+}
+}
+
+#endif
+
+#endif /* BIT_CAST_HPP */