Is it legal to use the address of a member to initialize a base-class?

Question

Is this code legal?:

class BaseClass
{
  public:
    BaseClass (int *p) : p_ (p) { }

  private:
    int *p_;
};

class SubClass : public BaseClass
{
  public:
    SubClass () : BaseClass (&i_), i_ (123) {}

  private:
    int i_;
};

It is well-known that the base-class gets constructed before the members of the sub-class, which is why I'm wondering.

As long as the base class does not dereference the pointer before the derived class is initialized I believe it is valid. — Jesper Juhl, Jun 03 '18 at 13:54
Almost a variant of this https://stackoverflow.com/questions/50020255/in-the-member-initializer-list-can-i-create-a-reference-to-a-member-variable-no — StoryTeller - Unslander Monica, Jun 03 '18 at 13:54

score 1 · Answer 1 · answered Jun 03 '18 at 17:00

1

Yes, this is fine: while the lifetime of (the relevant instance of) SubClass::i has yet to begin, its storage exists, and a pointer to it may be formed (though not used for much yet).

answered Jun 03 '18 at 17:00

Davis Herring

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Is it legal to use the address of a member to initialize a base-class?

1 Answers1