Can a compilation error be forced if a string argument is not a string literal?

Question

Let\'s say I have these two overloads:

void Log(const wchar_t* message)
{
    // Do something
}

void Log(const std::wstring& message)
{
    // Do someth         


        

Answer 1

I don't think you can enforce to pass only a string literal to a function, but literals are character arrays, what you can enforce:

#include 

template
void log(T) = delete; //Disable everything

template 
void log(const wchar_t (&message)[Size]) //... but const wchar_t arrays
{
    std::cout << "yay" << std::endl;
}

const wchar_t * get_str() { return L"meow"; }

int main() {
    log(L"foo"); //OK

    wchar_t arr[] = { 'b', 'a', 'r', '0' };
    log(arr); //Meh..

//    log(get_str()); //compile error
}

Downside is that if you have a runtime character array, it will work as well, but won't work for the usual runtime c-style strings.

But, if you can work with a slightly different syntax, then the answer is YES:

#include 
#include 

void operator"" _log ( const wchar_t* str, size_t size ) {
  std::cout << "yay" << std::endl;
}

int main() {
  L"Message"_log;
}

Of course, both solution needs a C++11-compatible compiler (example tested with G++ 4.7.3).