From c963fce3046b0a6f4df5421fc0ba80bc43eff28d Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Mon, 7 Feb 2022 12:14:24 +1000
Subject: [PATCH] endian: prefer bit_cast over union type punning

---
 endian.hpp | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/endian.hpp b/endian.hpp
index 0e3c02a9..f86e108d 100644
--- a/endian.hpp
+++ b/endian.hpp
@@ -9,6 +9,7 @@
 #pragma once
 
 #include "std.hpp"
+#include "cast.hpp"
 #include "types/sized.hpp"
 
 #include <compare>
@@ -48,21 +49,18 @@ namespace cruft {
     constexpr uint64_t bswap (uint64_t v) noexcept { return __builtin_bswap64 (v); }
 
 
-    // use a type-punning union to punt the byte swapping operation to the
-    // unsigned integer code.
-    //
-    // this is debatably safe under production compilers like gcc + clang
-    // despite what the standard may say about unions.
-    constexpr float
-    bswap (float v) noexcept
+    //-------------------------------------------------------------------------
+    constexpr f32
+    bswap (f32 v) noexcept
     {
-        union {
-            float f;
-            uint32_t u;
-        } temp { .f = v };
+        return cruft::cast::bit<f32> (bswap (cruft::cast::bit<u32> (v)));
+    }
 
-        temp.u = bswap (temp.u);
-        return temp.f;
+
+    constexpr f64
+    bswap (f64 v) noexcept
+    {
+        return cruft::cast::bit<f64> (bswap (cruft::cast::bit<u64> (v)));
     }