TMP to echo a compile time constant during compilation as a warning

ourputCompileTimeConstant

//output a compile time constant
template<size_t size>
struct overflow{ operator char() { return size + 999999; } }; //always overflow
template<int VALUE>
void echoCompileTimeConstant()
{
    char(overflow<VALUE>());
}

Usage:

enum{
val = 4
}
msf_tmp::echoCompileTimeConstant<val>();

Outputs:

warning: overflow in implicit constant conversion [-Woverflow]
instantiated from ‘void msf_tmp::echoCompileTimeConstant() [with int VALUE = 4]’