Ticket #5483: initialized-assignment-test.cpp

/*
This is gcc's output with all #defines (below) defined, showing the error
caused by using an object of type boost::initialized<int> as lvalue.
This can be fixed by implementing the method
 boost::initialized<T>& boost::initialized<T>::operator=(T const&)
for the initialized<T> class.

File                            Line    Message
main.cpp                                In function 'int main(int, char**)':
main.cpp                        57      error: no match for 'operator=' in 'b = 39'
boost/utility/value_init.hpp    120     note: candidates are: boost::initialized<T>& boost::initialized<T>::operator=(const boost::initialized<T>&) [with T = int]
*/

#define INITIALIZED_FAILURE
#define FOO_FAILURE
#define FOO_ASSIGNMENT_OPERATOR_FROM_INT

#include <iostream>
using std::cout;
using std::endl;

#include <boost/utility/value_init.hpp>
using boost::initialized;
using boost::get;

class foo {
public:
    int x;

    foo() : x(38) {}

    operator int& () {
        return x;
    }

    operator int const& () const {
        return x;
    }

#ifdef FOO_ASSIGNMENT_OPERATOR_FROM_INT
    foo& operator=(int const& o) {
        x = o;
        return *this;
    }
#endif

    foo& operator=(foo const& o) {  // if foo& foo::operator=(int const&) is undefined, this one is considered a "candidate" for the lvalue but not used
        x = o;
        return *this;
    }
};

int main(int, char**) {
    foo f;
    cout << endl << f;
#ifdef FOO_FAILURE
    f = 39;                         // succeeds if foo& foo::operator(int const&) defined, fails otherwise
    cout << endl << f;
#endif
    f.operator int&() = 40;         // succeeds
    cout << endl << f;
    cout << endl;

    initialized<int> b;
    cout << endl << b;
#ifdef INITIALIZED_FAILURE
    b = 39;                         // fails (with initialized<int>& initialized<int>::operator=(initialized<int> const&) considered as above)
    cout << endl << b;
#endif
    b.operator int&() = 40;         // succeeds
    cout << endl << b;
    get(b) = 41;                    // succeeds
    cout << endl << b;
    cout << endl;

    return 0;
}