C++11 constexpr function's argument passed in template argument

Question

This used to work some weeks ago:

template 
T            tfunc()
{
    return t + 10;
}

template 
constexpr T               


        

Answer 1

Looks like it should give an error - it has no way of knowing that you passed in a constant value as t to func.

More generally, you can't use runtime values as template arguments. Templates are inherently a compile-time construct.