Is the “lazy man's enable_if” legal C++?

Question

I frequently use a technique I call the \"lazy man\'s enable_if,\" where I use decltype and the comma operator to enable a function based on some templ

Answer 1

This is a feature called "Expression SFINAE." It is not yet fully supported by Visual C++ (see "C++11/14/17 Features In VS 2015 Preview" for the latest conformance update as of the time of this answer).