// ---------------------
// InstanceVariables.c++
// ---------------------

#include <cassert>  // assert
#include <iostream> // cout, endl

template <typename T>
struct A {
          T v;
    const T cv;};

template <typename T>
struct B {
    T v;
    T w;};

int main () {
    using namespace std;
    cout << "InstanceVariables.c++" << endl;

    {
//  A<int> x;                // error: structure "x" with uninitialized const members
//  A<int> x = {2};          // error: uninitialized const member "A<int>::cv"
    A<int> x = {2, 3};
    assert(x.v  == 2);
    assert(x.cv == 3);

    {
    const A<int> y = x;      // const A<int> y(x);
    assert(y.v  == 2);
    assert(y.cv == 3);
    assert(&x.v  != &y.v);
    assert(&x.cv != &y.cv);
    }

    {
    A<int> y = {5, 6};
    assert(y.v  == 5);
    assert(y.cv == 6);
//  y = x;                   // error: non-static const member "const int A<int>::cv", can't use default assignment operator
    }
    }

    {
    const B<int> x = {2, 3};
    assert(x.v == 2);
    assert(x.w == 3);

    B<int> y = {4, 5};
    assert(y.v == 4);
    assert(y.w == 5);

    y = x;
    assert(y.v == 2);
    assert(y.w == 3);

    assert(&x.v != &y.v);
    assert(&x.w != &y.w);
    }

    cout << "Done." << endl;
    return 0;}