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#include <algorithm>
#include <vector>

class A {
  int m;
  
public:
  A() : m(0) {}
  explicit A(int m) : m(m) {}
  
  A(const A &other) : m(other.m) {}
  A(A &&other) : m(other.m) { other.m = 0; }
  
  A& operator=(const A &other) {
    if (&other != this) {
      m = other.m;
    }
    return *this;
  }
 
  A& operator=(A &&other) {
    m = other.m;
    other.m = 0;
    return *this;
  }
  
  int get_m() const { return m; }
};

void f() {
  std::vector<A> v{10};
  A obj(12);
  std::fill(v.begin(), v.end(), obj);
}

Exceptions

OOP58-CPP-EX0 : Reference counting, and implementations such as std::shared_ptr<> constitute an exception to this rule. Any copy or assignment operation of a reference-counted object requires the reference count to be incremented. The semantics of reference counting are well-understood, and it can be argued that the reference count is not a salient part of the shared_pointer object.

Risk Assessment

Copy operations that mutate the source operand or global state can lead to unexpected program behavior. Using such a type in a Standard Template Library container or algorithm can also lead to undefined behavior.

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