From 16ddfbc4e04e3dc6315ac66bce0ff773623ed906 Mon Sep 17 00:00:00 2001
From: Benoit Blanchon <github@benoitblanchon.fr>
Date: Thu, 28 Feb 2019 15:37:42 +0100
Subject: [PATCH] Fixed strict-aliasing warning in FloatTraits.hpp

---
 src/ArduinoJson/Numbers/FloatTraits.hpp  |  6 ++---
 src/ArduinoJson/Polyfills/alias_cast.hpp | 28 ++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 3 deletions(-)
 create mode 100644 src/ArduinoJson/Polyfills/alias_cast.hpp

diff --git a/src/ArduinoJson/Numbers/FloatTraits.hpp b/src/ArduinoJson/Numbers/FloatTraits.hpp
index 051a682e..73c8bbd8 100644
--- a/src/ArduinoJson/Numbers/FloatTraits.hpp
+++ b/src/ArduinoJson/Numbers/FloatTraits.hpp
@@ -7,6 +7,7 @@
 #include <stddef.h>  // for size_t
 #include <stdint.h>
 #include "../Configuration.hpp"
+#include "../Polyfills/alias_cast.hpp"
 #include "../Polyfills/math.hpp"
 
 namespace ARDUINOJSON_NAMESPACE {
@@ -98,8 +99,7 @@ struct FloatTraits<T, 8 /*64bits*/> {
   // we use this function to workaround platforms with single precision literals
   // (for example, when -fsingle-precision-constant is passed to GCC)
   static T forge(uint32_t msb, uint32_t lsb) {
-    uint64_t bits = (uint64_t(msb) << 32) | lsb;
-    return *reinterpret_cast<T*>(&bits);
+    return alias_cast<T>((uint64_t(msb) << 32) | lsb);
   }
 };
 
@@ -146,7 +146,7 @@ struct FloatTraits<T, 4 /*32bits*/> {
   }
 
   static T forge(uint32_t bits) {
-    return *reinterpret_cast<T*>(&bits);
+    return alias_cast<T>(bits);
   }
 
   static T nan() {
diff --git a/src/ArduinoJson/Polyfills/alias_cast.hpp b/src/ArduinoJson/Polyfills/alias_cast.hpp
new file mode 100644
index 00000000..41c04a76
--- /dev/null
+++ b/src/ArduinoJson/Polyfills/alias_cast.hpp
@@ -0,0 +1,28 @@
+// ArduinoJson - arduinojson.org
+// Copyright Benoit Blanchon 2014-2019
+// MIT License
+
+#pragma once
+
+#include <stdint.h>
+#include <stdlib.h>  // for size_t
+#include "../Configuration.hpp"
+#include "../Polyfills/math.hpp"
+
+namespace ARDUINOJSON_NAMESPACE {
+
+template <typename T, typename F>
+struct alias_cast_t {
+  union {
+    F raw;
+    T data;
+  };
+};
+
+template <typename T, typename F>
+T alias_cast(F raw_data) {
+  alias_cast_t<T, F> ac;
+  ac.raw = raw_data;
+  return ac.data;
+}
+}  // namespace ARDUINOJSON_NAMESPACE