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  1. #include <iostream>
  2.  
  3. class X
  4. {
  5.     int value;
  6.  
  7. public:
  8.  
  9.     X() : value(0) {};
  10.  
  11.     X(int v) : value(v) {};
  12.  
  13.     X(const X& x) {     // Does not help!
  14.         this->value = x.value;
  15.     }
  16.  
  17.     X(const X&& x) noexcept { // Does not help!
  18.         this->value = x.value;
  19.     }
  20.  
  21.     X& operator=(const X& left) { // Does not help!
  22.         value = left.value;
  23.         return *this;
  24.     };
  25.  
  26.  
  27.     bool operator==(const X& right) const {
  28.         return this->value == right.value;
  29.     };
  30.  
  31. };
  32.  
  33. class Y
  34. {
  35.     int value;
  36. public:
  37.  
  38.     operator X() const {
  39.  
  40.         return X(this->value);
  41.  
  42.     };  // Y objects may be converted to X
  43. };
  44.  
  45. int main() {
  46.  
  47. X x1, x2;
  48. Y y1;
  49.  
  50. x1 == x2;   // Compiles 
  51.  
  52. auto newv = (X)y1; // Compiles 
  53.  
  54. x1 == newv;   // Accepted!
  55.  
  56. x1 == (X)y1;   // Error!!!
  57.  
  58. } // END: main()
Success #stdin #stdout 0s 4516KB
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https://ideone.com/tN1w8T
language:
C++14 (clang 8.0)
created:
4 years ago
visibility:
secret

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