The constructor initialization list sets the order / distribution

Question

My question is simple, is the following code safe?

struct Parent {
    B* _a;
    Parent(B* a) : _a(a) {}
};

struct Child : public Parent {
    B _b;
    Child() : Parent(&_b),  _b(2){};
};

int main() {
    Child c;
    return 0;
}

Two more points:

• I'm interested in the part of passing a reference to a member object to the parent object.
• In safe, I mean that it _bwill be allocated (and its memory address) and that this code will work no matter which compiler I use.

Thanks in advance.

clarification
on safe I actually meant that the memory address was valid, since I already knew that it was not initialized.

other notes
In my actual code, I wanted to save the type object Bas a pointer to its base class A, for example:

struct Parent {
    A* _a;
    Parent(A* a) : _a(a) {}
};

struct Child : public Parent {
    B _b;
    Child() : Parent(&_b),  _b(2){};
};

int main() {
    Child c;
    return 0;
}

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Answer 1

, , , : , . Child::_b Child. - "". Child::Child , , .

, , ( 3.8, ), , , . . .

, , - (, B ), . ( , . 3.8).

Answer 2

:

// Base classes:
Parent(&_b)

// Members:
_b(2)

// Constructor Body:
Child() { }

, "". ( " ?" ), , . Child::_b , Child , , . , , _b, Parent .

Answer 3

, - . .

:

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