What does your code look like that detects void types? I use the following EXPR_IS_VOID macro myself (which is not originally mine, but I think I have modified it from the original after some testing); feel free to pilfer. The double comma operator thingy is intended to work even if the type of ( Expr ) has an overloaded comma operator, but I've found that GCC has issues with this construct, hence the two versions.
#define EXPR_IS_VOID( Expr ) \ EXPR_IS_CONVERTIBLE( \ ( ( Expr ), ::detail_expr_is_void::void_detector_t() ), \ ::detail_expr_is_void::void_detector_t \ )
Interesting: I do not have a series of 2 operator, but instead have non_void_t operator,(const T&, void_detector_t) declared. I will check if your implementation gives something better. Thanks a lot for your contribution. Frédéric