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      1 //===----------------------------------------------------------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is dual licensed under the MIT and the University of Illinois Open
      6 // Source Licenses. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 
     10 // <optional>
     11 
     12 // optional<T>& operator=(const optional<T>& rhs);
     13 
     14 #include <experimental/optional>
     15 #include <type_traits>
     16 #include <cassert>
     17 
     18 #if _LIBCPP_STD_VER > 11
     19 
     20 using std::experimental::optional;
     21 
     22 struct X
     23 {
     24     static bool throw_now;
     25 
     26     X() = default;
     27     X(const X&)
     28     {
     29         if (throw_now)
     30             throw 6;
     31     }
     32 };
     33 
     34 bool X::throw_now = false;
     35 
     36 #endif  // _LIBCPP_STD_VER > 11
     37 
     38 int main()
     39 {
     40 #if _LIBCPP_STD_VER > 11
     41     {
     42         optional<int> opt;
     43         constexpr optional<int> opt2;
     44         opt = opt2;
     45         static_assert(static_cast<bool>(opt2) == false, "");
     46         assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
     47     }
     48     {
     49         optional<int> opt;
     50         constexpr optional<int> opt2(2);
     51         opt = opt2;
     52         static_assert(static_cast<bool>(opt2) == true, "");
     53         static_assert(*opt2 == 2, "");
     54         assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
     55         assert(*opt == *opt2);
     56     }
     57     {
     58         optional<int> opt(3);
     59         constexpr optional<int> opt2;
     60         opt = opt2;
     61         static_assert(static_cast<bool>(opt2) == false, "");
     62         assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
     63     }
     64     {
     65         optional<int> opt(3);
     66         constexpr optional<int> opt2(2);
     67         opt = opt2;
     68         static_assert(static_cast<bool>(opt2) == true, "");
     69         static_assert(*opt2 == 2, "");
     70         assert(static_cast<bool>(opt) == static_cast<bool>(opt2));
     71         assert(*opt == *opt2);
     72     }
     73     {
     74         optional<X> opt;
     75         optional<X> opt2(X{});
     76         assert(static_cast<bool>(opt2) == true);
     77         try
     78         {
     79             X::throw_now = true;
     80             opt = opt2;
     81             assert(false);
     82         }
     83         catch (int i)
     84         {
     85             assert(i == 6);
     86             assert(static_cast<bool>(opt) == false);
     87         }
     88     }
     89 #endif  // _LIBCPP_STD_VER > 11
     90 }
     91