Why must we do this:

// concept C

template <C ...T >

decltype(auto) func (T ...args)

{

          return args + ...;

}

So unnecessary!

Why not:

decltype(auto) func (C ...args)

{

          Return args + ...;

}

??

Not hard to implement, as auto in param list is already implemented.

This would help lots, & would speed up coding, making it more maintainable too!