calling functions above their declaration

Question

void foo()
{
    bar();          // error: ‘bar’ has not been declared
}

void bar()
{
}

namespace N
{
    void foo()
    {
        N::bar();   // error: ‘bar’ is not a member of ‘N’
    }

    void bar()
    {
    }
}

class C
{
    static void foo()
    {
        C::bar();   // works just fine
    }

    static void bar()
    {
    }
};

What is the rationale behind this inconsistency of treating calls to functions above their declaration? How come I can do it inside a class, but not inside a namespace or at global scope?

Answer 1

You can define member functions either inside the class, or after the class declaration, or some of each.

To get some consistency here, the rules for a class with functions defined inline is that it still has to be compiled as if the functions were defined after the class.

Your code

class C {
     static void foo()
     {
         C::bar();   // works just fine 
     }

     static void bar()
     {     }
 }; 

compiles the same as

class C {
     static void foo();
     static void bar();
 }; 

 void C::foo()
 {  C::bar();  }

 void C::bar()
 {     }

and now there is no magic in the visibility, because the functions can all see everything declared in the class.