libcxx/test/support/variant_test_helpers.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9 #ifndef SUPPORT_VARIANT_TEST_HELPERS_H
  10 #define SUPPORT_VARIANT_TEST_HELPERS_H
  11
  12 #include <type_traits>
  13 #include <utility>
  14 #include <cassert>
  15
  16 #include "test_macros.h"
  17
  18 #if TEST_STD_VER <= 14
  19 #error This file requires C++17
  20 #endif
  21
  22 // FIXME: Currently the variant<T&> tests are disabled using this macro.
  23 #define TEST_VARIANT_HAS_NO_REFERENCES
  24 #ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
  25 # define TEST_VARIANT_ALLOWS_NARROWING_CONVERSIONS
  26 #endif
  27
  28 #ifdef TEST_VARIANT_ALLOWS_NARROWING_CONVERSIONS
  29 constexpr bool VariantAllowsNarrowingConversions = true;
  30 #else
  31 constexpr bool VariantAllowsNarrowingConversions = false;
  32 #endif
  33
  34 #ifndef TEST_HAS_NO_EXCEPTIONS
  35 struct CopyThrows {
  36   CopyThrows() = default;
  37   CopyThrows(CopyThrows const&) { throw 42; }
  38   CopyThrows& operator=(CopyThrows const&) { throw 42; }
  39 };
  40
  41 struct MoveThrows {
  42   static int alive;
  43   MoveThrows() { ++alive; }
  44   MoveThrows(MoveThrows const&) {++alive;}
  45   MoveThrows(MoveThrows&&) {  throw 42; }
  46   MoveThrows& operator=(MoveThrows const&) { return *this; }
  47   MoveThrows& operator=(MoveThrows&&) { throw 42; }
  48   ~MoveThrows() { --alive; }
  49 };
  50
  51 int MoveThrows::alive = 0;
  52
  53 struct MakeEmptyT {
  54   static int alive;
  55   MakeEmptyT() { ++alive; }
  56   MakeEmptyT(MakeEmptyT const&) {
  57       ++alive;
  58       // Don't throw from the copy constructor since variant's assignment
  59       // operator performs a copy before committing to the assignment.
  60   }
  61   MakeEmptyT(MakeEmptyT &&) {
  62       throw 42;
  63   }
  64   MakeEmptyT& operator=(MakeEmptyT const&) {
  65       throw 42;
  66   }
  67   MakeEmptyT& operator=(MakeEmptyT&&) {
  68       throw 42;
  69   }
  70    ~MakeEmptyT() { --alive; }
  71 };
  72 static_assert(std::is_swappable_v<MakeEmptyT>, ""); // required for test
  73
  74 int MakeEmptyT::alive = 0;
  75
  76 template <class Variant>
  77 void makeEmpty(Variant& v) {
  78     Variant v2(std::in_place_type<MakeEmptyT>);
  79     try {
  80         v = std::move(v2);
  81         assert(false);
  82     } catch (...) {
  83         assert(v.valueless_by_exception());
  84     }
  85 }
  86 #endif // TEST_HAS_NO_EXCEPTIONS
  87
  88
  89 #endif // SUPPORT_VARIANT_TEST_HELPERS_H