From 9418f54ebc58fc3b2c98920a0f83afabf9a7f63f Mon Sep 17 00:00:00 2001
From: Gary Talent <gary@drinkingtea.net>
Date: Sat, 24 Jul 2021 20:39:40 -0500
Subject: [PATCH] [ox/std] Add support for proper std::bit_cast with C++20
 enabled

---
 deps/ox/src/ox/std/bit.hpp    | 26 +++++++++++++++++++++++++-
 deps/ox/src/ox/std/memops.hpp |  6 +++---
 deps/ox/src/ox/std/types.hpp  |  1 +
 3 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/deps/ox/src/ox/std/bit.hpp b/deps/ox/src/ox/std/bit.hpp
index fd6b61b6..6f7c06f0 100644
--- a/deps/ox/src/ox/std/bit.hpp
+++ b/deps/ox/src/ox/std/bit.hpp
@@ -8,6 +8,10 @@
 
 #pragma once
 
+#if __cplusplus >= 202002L && defined(OX_USE_STDLIB)
+#include <bit>
+#endif
+
 #include "memops.hpp"
 #include "types.hpp"
 #include "typetraits.hpp"
@@ -16,7 +20,7 @@ namespace ox {
 
 template<typename To, typename From>
 constexpr typename enable_if<sizeof(To) == sizeof(From), To>::type cbit_cast(From src) noexcept {
-	To dst;
+	To dst = {};
 	ox_memcpy(&dst, &src, sizeof(src));
 	return dst;
 }
@@ -52,3 +56,23 @@ static_assert(onMask<int>(3) == 7);
 static_assert(onMask<int>(4) == 15);
 
 }
+
+namespace std {
+#if __cplusplus >= 202002L && !defined(OX_USE_STDLIB)
+
+template<typename To, typename From>
+constexpr typename ox::enable_if<sizeof(To) == sizeof(From), To>::type bit_cast(From src) noexcept {
+	return __builtin_bitcast(src);
+}
+
+#elif __cplusplus < 202002L
+
+template<typename To, typename From>
+typename ox::enable_if<sizeof(To) == sizeof(From), To>::type bit_cast(From src) noexcept {
+	To dst = {};
+	memcpy(&dst, &src, sizeof(src));
+	return dst;
+}
+
+#endif
+}
diff --git a/deps/ox/src/ox/std/memops.hpp b/deps/ox/src/ox/std/memops.hpp
index b361942e..3c9bd4a6 100644
--- a/deps/ox/src/ox/std/memops.hpp
+++ b/deps/ox/src/ox/std/memops.hpp
@@ -29,7 +29,7 @@ int ox_memcmp(const void *ptr1, const void *ptr2, std::size_t size) noexcept;
 constexpr void *ox_memcpy(void *dest, const void *src, std::size_t size) noexcept {
 	auto srcBuf = static_cast<const char*>(src);
 	auto dstBuf = static_cast<char*>(dest);
-	for (std::size_t i = 0; i < size; i++) {
+	for (std::size_t i = 0; i < size; ++i) {
 		dstBuf[i] = static_cast<char>(srcBuf[i]);
 	}
 	return dest;
@@ -38,7 +38,7 @@ constexpr void *ox_memcpy(void *dest, const void *src, std::size_t size) noexcep
 constexpr void *ox_memmove(void *dest, const void *src, std::size_t size) noexcept {
 	auto srcBuf = static_cast<const char*>(src);
 	auto dstBuf = static_cast<char*>(dest);
-	for (std::size_t i = 0; i < size; i++) {
+	for (std::size_t i = 0; i < size; ++i) {
 		dstBuf[i] = static_cast<char>(srcBuf[i]);
 	}
 	return dest;
@@ -46,7 +46,7 @@ constexpr void *ox_memmove(void *dest, const void *src, std::size_t size) noexce
 
 constexpr void *ox_memset(void *ptr, int val, std::size_t size) noexcept {
 	auto buf = static_cast<uint8_t*>(ptr);
-	for (std::size_t i = 0; i < size; i++) {
+	for (std::size_t i = 0; i < size; ++i) {
 		buf[i] = static_cast<uint8_t>(val);
 	}
 	return ptr;
diff --git a/deps/ox/src/ox/std/types.hpp b/deps/ox/src/ox/std/types.hpp
index d182429e..d64baada 100644
--- a/deps/ox/src/ox/std/types.hpp
+++ b/deps/ox/src/ox/std/types.hpp
@@ -64,6 +64,7 @@ namespace ox {
 template<typename T, std::size_t sz = sizeof(T)>
 struct alignas(alignof(T)) AllocAlias {
 	char buff[sz];
+	constexpr AllocAlias() noexcept = default;
 };