function definition without prototype

Question

when function definition is below, and there is no function prototype.

int main(void)
{
        func();
        void (*pFunc)(void) = func;
}

void func(void)
{
}

main.c:3:2: warning: implicit declaration of function 'func' is invalid in C99 [-Wimplicit-function-declaration]
        func();
        ^
main.c:4:9: error: incompatible function pointer types initializing 'void (*)(void)' with an expression of type 'int ()' [-Werror,-Wincompatible-function-pointer-types]
        void (*pFunc)(void) = func;
               ^              ~~~~
main.c:4:9: warning: unused variable 'pFunc' [-Wunused-variable]
main.c:7:6: error: conflicting types for 'func'
void func(void)
     ^
main.c:3:2: note: previous implicit declaration is here
        func();
        ^
2 warnings and 2 errors generated.

I can call a function without function prototpype(ignoring implicit function declaration), but why I can't get the adress of the function?