A reference can not be NULL or it can be NULL?

Question

I have read from the Wikipedia that:

“References cannot be null, whereas pointers can; every reference refers to some object, although it may or may n

Answer 1

gcc8 will give a warning about it:

warning: the compiler can assume that the address of 'object1' will never be NULL [-Waddress]

A small demo:

#include 

class person
{
    public:
        virtual void setage()=0;
};

int main()
{
    person *object=NULL;
    person &object1=*object;

    if (&object1 == NULL) {
        std::cout << "NULL object1" << std::endl;
    }

    if (!(&object1)) {
        std::cout << "NULL object1 " << std::endl;
    }
}

Compile and running output:

g++ -std=c++2a -pthread -fgnu-tm -O2 -Wall -Wextra -pedantic -pthread -pedantic-errors main.cpp -lm -latomic -lstdc++fs && ./a.out

main.cpp: In function 'int main()':

main.cpp:14:18: warning: the compiler can assume that the address of 'object1' will never be NULL [-Waddress]

 if (&object1 == NULL) {

              ^

main.cpp:18:19: warning: the compiler can assume that the address of 'object1' will never be NULL [-Waddress]

 if (!(&object1)) {

               ^

NULL object1

NULL object1