C++11 Uniform initialization (i.e. list initialization) doesn't compile with inheritance

Question

struct B { 
  int b; 
  B(int i = 0) : b(i) {};  // constructor
};

struct D : B  {
  int d;
};

int main () {
  D obj = {1};  // <-- error
  // D obj {1}; // <-- error (different)

}

Above code doesn't compiles, and gives:

error: could not convert ‘{1}’ from ‘<brace-enclosed initializer list>’ to ‘D’

The same is true, even if I remove the "constructor" line. If I remove = sign, i.e. D obj {1}; then it gives below:

error: no matching function for call to ‘D::D(<brace-enclosed initializer list>)’

What is the correct syntax to fix such issue?

Answer 1

D doesn't have a constructor taking an int. If you want it to inherit B's constructor, say so, like this:

struct D : B  {
  using B::B;
  int d;
};

You probably want to do more than that though, given that D has another int member.

A more complete D which initialises both B::b (by calling B::B) and D::d would probably look like this:

struct D : B  {
  D(int d_) : B(d_), d(d_) {}
  int d;
};

Either way, your code needs to say D has a constructor taking an int.

Link to working example using your code and my snippet: http://goo.gl/YbSSHn