Disable clang optimization on extract_list_front() for OSX

1 files changed, 10 insertions, 1 deletions

diff --git a/Rx/v2/src/rxcpp/rx-util.hpp b/Rx/v2/src/rxcpp/rx-util.hpp
index 7a83b7d..172720c 100644
--- a/Rx/v2/src/rxcpp/rx-util.hpp
+++ b/Rx/v2/src/rxcpp/rx-util.hpp
@@ -593,15 +593,24 @@ struct list_not_empty {
 };
 
 struct extract_list_front {
+    // Clang optimisation loses moved list.front() value after list.pop_front(), so optimization must be switched off.
     template<class T>
-#if defined(__clang__)
+#if defined(__clang__) && defined(__linux__)
+    // Clang on Linux has an attribute to forbid optimization
     __attribute__((optnone))
 #endif
     auto operator()(std::list<T>& list) const
         -> decltype(std::move(list.front())) {
+#if defined(__clang__) && !defined(__linux__)
+        // Clang on OSX doesn't support the attribute
+        volatile auto val = std::move(list.front());
+        list.pop_front();
+        return std::move(const_cast<T&>(val));
+#else
         auto val = std::move(list.front());
         list.pop_front();
         return std::move(val);
+#endif
     }
 };