Why can I take the address of a register variable?

Question

Quoted from the book “Thinking in C ++” in the section on register variables: “There are restrictions on the use of register variables. You cannot accept or calculate the address of a register variable. A register variable can only be declared within a block (you cannot have global or static register variables).

So, I wrote this part of the program for testing:

int global = 2;
// error
// register int global2 = 3;

int main() {
    register int local2 = 2;
    cout << local2 << " " << &local2 << endl;
}

However, g ++ does not generate errors and the local2 address is issued. So why can I accept the address without errors?

Answer 1

True, historically you could not take the address of a variable register.

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Answer 2

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