libcxx/test/std/utilities/expected/expected.void/ctor/ctor.copy.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, c++17, c++20
  10
  11 // constexpr expected(const expected& rhs);
  12 //
  13 // Effects: If rhs.has_value() is false, direct-non-list-initializes unex with rhs.error().
  14 //
  15 // Postconditions: rhs.has_value() == this->has_value().
  16 //
  17 // Throws: Any exception thrown by the initialization of unex.
  18 //
  19 // Remarks:
  20 // - This constructor is defined as deleted unless is_copy_constructible_v<E> is true.
  21 // - This constructor is trivial if is_trivially_copy_constructible_v<E> is true.
  22
  23 #include <cassert>
  24 #include <expected>
  25 #include <type_traits>
  26 #include <utility>
  27
  28 #include "test_macros.h"
  29 #include "../../types.h"
  30
  31 struct NonCopyable {
  32   NonCopyable(const NonCopyable&) = delete;
  33 };
  34
  35 struct CopyableNonTrivial {
  36   int i;
  37   constexpr CopyableNonTrivial(int ii) : i(ii) {}
  38   constexpr CopyableNonTrivial(const CopyableNonTrivial& o) { i = o.i; }
  39   friend constexpr bool operator==(const CopyableNonTrivial&, const CopyableNonTrivial&) = default;
  40 };
  41
  42 // Test: This constructor is defined as deleted unless is_copy_constructible_v<E> is true.
  43 static_assert(std::is_copy_constructible_v<std::expected<void, int>>);
  44 static_assert(std::is_copy_constructible_v<std::expected<void, CopyableNonTrivial>>);
  45 static_assert(!std::is_copy_constructible_v<std::expected<void, NonCopyable>>);
  46
  47 // Test: This constructor is trivial if is_trivially_copy_constructible_v<E> is true.
  48 static_assert(std::is_trivially_copy_constructible_v<std::expected<void, int>>);
  49 static_assert(!std::is_trivially_copy_constructible_v<std::expected<void, CopyableNonTrivial>>);
  50
  51 constexpr bool test() {
  52   // copy the error non-trivial
  53   {
  54     const std::expected<void, CopyableNonTrivial> e1(std::unexpect, 5);
  55     auto e2 = e1;
  56     assert(!e2.has_value());
  57     assert(e2.error().i == 5);
  58   }
  59
  60   // copy the error trivial
  61   {
  62     const std::expected<void, int> e1(std::unexpect, 5);
  63     auto e2 = e1;
  64     assert(!e2.has_value());
  65     assert(e2.error() == 5);
  66   }
  67
  68   // copy TailClobberer as error
  69   {
  70     const std::expected<void, TailClobberer<1>> e1(std::unexpect);
  71     auto e2 = e1;
  72     assert(!e2.has_value());
  73   }
  74
  75   return true;
  76 }
  77
  78 void testException() {
  79 #ifndef TEST_HAS_NO_EXCEPTIONS
  80   struct Throwing {
  81     Throwing() = default;
  82     Throwing(const Throwing&) { throw Except{}; }
  83   };
  84
  85   // throw on copying error
  86   {
  87     const std::expected<void, Throwing> e1(std::unexpect);
  88     try {
  89       [[maybe_unused]] auto e2 = e1;
  90       assert(false);
  91     } catch (Except) {
  92     }
  93   }
  94
  95 #endif // TEST_HAS_NO_EXCEPTIONS
  96 }
  97
  98 int main(int, char**) {
  99   test();
 100   static_assert(test());
 101   testException();
 102   return 0;
 103 }