libcxx/test/std/utilities/optional/optional.object/special_members.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 // Make sure we properly generate special member functions for optional<T>
  14 // based on the properties of T itself.
  15
  16 #include <optional>
  17 #include <type_traits>
  18
  19 #include "archetypes.h"
  20
  21 #include "test_macros.h"
  22
  23
  24 template <class T>
  25 struct SpecialMemberTest {
  26     using O = std::optional<T>;
  27
  28     static_assert(std::is_default_constructible_v<O>,
  29         "optional is always default constructible.");
  30
  31     static_assert(std::is_copy_constructible_v<O> == std::is_copy_constructible_v<T>,
  32         "optional<T> is copy constructible if and only if T is copy constructible.");
  33
  34     static_assert(std::is_move_constructible_v<O> ==
  35         (std::is_copy_constructible_v<T> || std::is_move_constructible_v<T>),
  36         "optional<T> is move constructible if and only if T is copy or move constructible.");
  37
  38     static_assert(std::is_copy_assignable_v<O> ==
  39         (std::is_copy_constructible_v<T> && std::is_copy_assignable_v<T>),
  40         "optional<T> is copy assignable if and only if T is both copy "
  41         "constructible and copy assignable.");
  42
  43     static_assert(std::is_move_assignable_v<O> ==
  44         ((std::is_move_constructible_v<T> && std::is_move_assignable_v<T>) ||
  45          (std::is_copy_constructible_v<T> && std::is_copy_assignable_v<T>)),
  46         "optional<T> is move assignable if and only if T is both move constructible and "
  47         "move assignable, or both copy constructible and copy assignable.");
  48 };
  49
  50 template <class ...Args> static void sink(Args&&...) {}
  51
  52 template <class ...TestTypes>
  53 struct DoTestsMetafunction {
  54     DoTestsMetafunction() { sink(SpecialMemberTest<TestTypes>{}...); }
  55 };
  56
  57 int main(int, char**) {
  58     sink(
  59         ImplicitTypes::ApplyTypes<DoTestsMetafunction>{},
  60         ExplicitTypes::ApplyTypes<DoTestsMetafunction>{},
  61         NonLiteralTypes::ApplyTypes<DoTestsMetafunction>{},
  62         NonTrivialTypes::ApplyTypes<DoTestsMetafunction>{}
  63     );
  64     return 0;
  65 }