Core/Misc: Modernize comparison operators

(cherry picked from commit f0a862e71bc12d86a898901ef773475a7c964832)

1 files changed, 29 insertions, 0 deletions

diff --git a/src/common/Utilities/advstd.h b/src/common/Utilities/advstd.h
index ff2717c9755..4a26e00df52 100644
--- a/src/common/Utilities/advstd.h
+++ b/src/common/Utilities/advstd.h
@@ -18,9 +18,38 @@
 #ifndef TRINITY_ADVSTD_H
 #define TRINITY_ADVSTD_H
 
+#include <version>
+
+#ifdef __cpp_lib_bit_cast
+#include <bit>
+#else
+#include <cstring> // for memcpy
+#endif
+#include <compare>
+
 // this namespace holds implementations of upcoming stdlib features that our c++ version doesn't have yet
 namespace advstd
 {
+// libc++ is missing these two
+[[nodiscard]] constexpr bool is_eq(std::partial_ordering cmp) noexcept { return cmp == 0; }
+[[nodiscard]] constexpr bool is_neq(std::partial_ordering cmp) noexcept { return cmp != 0; }
+
+#ifdef __cpp_lib_bit_cast
+using std::bit_cast;
+#else
+// libstdc++ v10 is missing this
+template <typename To, typename From,
+    std::enable_if_t<std::conjunction_v<
+    std::bool_constant<sizeof(To) == sizeof(From)>,
+    std::is_trivially_copyable<To>,
+    std::is_trivially_copyable<From>>, int> = 0>
+    [[nodiscard]] constexpr To bit_cast(From const& from) noexcept
+{
+    To to;
+    std::memcpy(&to, &from, sizeof(To));
+    return to;
+}
+#endif
 }
 
 #endif