From e93f6a22703249f0ebfff25302147c64965d5907 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@pdimov.com>
Date: Sat, 23 Dec 2017 18:40:09 +0200
Subject: [PATCH] Fix unaligned loads and stores

---
 include/boost/endian/buffers.hpp | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/include/boost/endian/buffers.hpp b/include/boost/endian/buffers.hpp
index 081aee8..258bbec 100644
--- a/include/boost/endian/buffers.hpp
+++ b/include/boost/endian/buffers.hpp
@@ -47,6 +47,7 @@
 #include <boost/core/scoped_enum.hpp>
 #include <iosfwd>
 #include <climits>
+#include <cstring>
 
 # if CHAR_BIT != 8
 #   error Platforms with CHAR_BIT != 8 are not supported
@@ -295,7 +296,12 @@ namespace endian
                                  // case since sizeof(T) and n_bytes are known at compile
                                  // time.
       {
-        return *reinterpret_cast<T const *>(bytes);
+        // Avoids -fsanitize=undefined violations due to unaligned loads
+        // All major x86 compilers optimize a short-sized memcpy into a single instruction
+
+        T t;
+        std::memcpy( &t, bytes, sizeof(T) );
+        return t;
       }
 #   endif
       return unrolled_byte_loops<T, n_bytes>::load_little
@@ -321,7 +327,10 @@ namespace endian
                                  // case since sizeof(T) and n_bytes are known at compile
                                  // time.
       {
-        *reinterpret_cast<T *>(bytes) = value;
+        // Avoids -fsanitize=undefined violations due to unaligned stores
+        // All major x86 compilers optimize a short-sized memcpy into a single instruction
+
+        std::memcpy( bytes, &value, sizeof(T) );
         return;
       }
 #     endif