cast: add alignment cast

cast.hpp

@@ -152,6 +152,21 @@ namespace util::cast {
         CHECK_NOTHROW (dynamic_cast<T> (v));
         return static_cast<T> (v);
     }
+
+
+    ///////////////////////////////////////////////////////////////////////////
+    /// cast a pointer from one type to another, asserting that the required
+    /// alignment of the destination type has been satisfied.
+    template <typename DstT, typename SrcT>
+    DstT*
+    alignment (SrcT *src)
+    {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wcast-align"
+        CHECK_MOD (reinterpret_cast<uintptr_t> (src), alignof (DstT));
+        return reinterpret_cast<DstT*> (src);
+#pragma GCC diagnostic pop
+    }
 };
 
 #endif