WIP: use FWD() macro, wait for PR in stdx to finalise

Waiting for intel/cpp-std-extensions#45 to be
merged before we can proceed.

Author: AshleyRoll

include/msg/rle_indexed_handler.hpp

@@ -4,6 +4,14 @@
 #include <msg/detail/rle_codec.hpp>
 
 #include <stdx/compiler.hpp>
+#include <stdx/utility.hpp>
+
+#ifndef FWD
+// TODO: remove when stdx contains a FWD() macro
+#define FWD(x) std::forward<decltype(x)>(x)
+#else
+#error "Remove the FWD() declaration in favour of the one from stdx"
+#endif
 
 namespace msg {
 
@@ -14,13 +22,15 @@ struct rle_indices : IndicesT... {
 
     constexpr auto operator()(auto const &data) const {
         // proxy to allow intersection without materializing a full bitset.
-        return detail::rle_intersect{std::forward<decltype(storage.decode(
-            this->IndicesT::operator()(data)))>(
-            storage.decode(this->IndicesT::operator()(data)))...};
+        return detail::rle_intersect{
+            FWD(storage.decode(this->IndicesT::operator()(data)))...};
     }
 
     // index entries will map into this storage to decode RLE data
     RleStorageT storage;
 };
 
 } // namespace msg
+
+// TODO: remove when stdx contains a FWD() macro
+#undef FWD