I've tried to use __PRETTY_FUNCTION__ directly a year or two ago. Some compilers allowed that, some not.
Could you try to compile that code on Clang? If that works, try to mark detail::ctti<T>::n() with constexpr and use in your code:
Clang 3.8 does compile with the example code.
template<std::size_t Index> constexpr static char step() { return detail::ctti<T>::n()[Index]; }
If that works, then it would be a really great addition to type_index!
That probably won't work. Constexpr [] on a const char* seems not to work, while "xyz"[1] works. That's why I use the __PRETTY_FUNC__ directly. Can be implemented that way though.
That won't help. I need a way to make conversion of T type to some non-templated class and back: T -> int -> T
TypeIndex allows only the first part of that: T -> type_index, but does not allow type_index -> T
Ah sure. Yeah then you can't get around some form of a macro. But maybe you could remove the index number, so adding a new class would work without that. That would allow me to add types at several places, because elsewise it might crash when different libraries do that. Though that would be a tweak later on.