libcxx/test/std/utilities/optional/optional.object/optional.object.mod/reset.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03, c++11, c++14
  10
  11 // <optional>
  12
  13 // void reset() noexcept;
  14
  15 #include <optional>
  16 #include <type_traits>
  17 #include <cassert>
  18
  19 #include "test_macros.h"
  20
  21 using std::optional;
  22
  23 struct X
  24 {
  25     static bool dtor_called;
  26     X() = default;
  27     X(const X&) = default;
  28     X& operator=(const X&) = default;
  29     ~X() {dtor_called = true;}
  30 };
  31
  32 bool X::dtor_called = false;
  33
  34 constexpr bool check_reset()
  35 {
  36     {
  37         optional<int> opt;
  38         static_assert(noexcept(opt.reset()) == true, "");
  39         opt.reset();
  40         assert(static_cast<bool>(opt) == false);
  41     }
  42     {
  43         optional<int> opt(3);
  44         opt.reset();
  45         assert(static_cast<bool>(opt) == false);
  46     }
  47     return true;
  48 }
  49
  50 int main(int, char**)
  51 {
  52     check_reset();
  53 #if TEST_STD_VER >= 20
  54     static_assert(check_reset());
  55 #endif
  56     {
  57         optional<X> opt;
  58         static_assert(noexcept(opt.reset()) == true, "");
  59         assert(X::dtor_called == false);
  60         opt.reset();
  61         assert(X::dtor_called == false);
  62         assert(static_cast<bool>(opt) == false);
  63     }
  64     {
  65         optional<X> opt(X{});
  66         X::dtor_called = false;
  67         opt.reset();
  68         assert(X::dtor_called == true);
  69         assert(static_cast<bool>(opt) == false);
  70         X::dtor_called = false;
  71     }
  72
  73   return 0;
  74 }