Folks, I think I'm looking to add a new C++11 defect macro, but don't know what the feature is called, nor can I see a way of detecting it with clang's __has_feature function. The code I want to enable involves function overloading based on a decltype return type as in: auto integrate(args...) -> decltype(expression1); auto integrate(args...) -> decltype(expression2); where expression1 and expression2 are two mutually exclusive options (the conceptual requirements of args means that only one of these 2 will ever be satisfied). This works fine in msvc-14 and later and gcc-4.8 and later, but I don't see any current config macros which cover this case, nor can I figure out what this trick should be called. Alternatively, if anyone has a better way of differentiating between unary and binary functions I'm happy to hear about it ;) Thanks, John. --- This email has been checked for viruses by AVG. http://www.avg.com