How to initialize member-struct with unnamed structure in initializer list of C++ class?

Question

I have a structure with unnamed structure inside. I want to initialize whole structure and it's member structure in class initializer list.

struct Foo {
  int z;
  struct {
    double upper;
    double lower;
  } x, y;
};

class Bar {
  Bar();

  Foo foo;
};

Can this be done?

Also can this structure be initialized "old fashion" way providing a constructor without uniform initialization syntax?

struct Foo {
    Foo() : z(2), x(/*?*/), y(/*?*/) {}
    Foo() : z(2), x.lower(2) {} // doesn't compile
    int z;
    struct {
      double upper;
      double lower;
    } x, y;
};

Answer 1

If I understand you correctly you want to initialize the struct Foo, which contains an unnamed struct, in the initializer list of Bar:

#include <iostream>

struct Foo {
  int z;
  struct {
    double upper;
    double lower;
  } x, y;
};

class Bar {
public:
  Bar();

  Foo foo;
};

Bar::Bar()
: foo { 1, { 2.2, 3.3}, {4.4, 5.5} }
{

}

int main()
{
    Bar b;

    std::cout << b.foo.z << std::endl;
    std::cout << b.foo.x.upper << std::endl;
    std::cout << b.foo.y.lower << std::endl;
}