1 files changed, 591 insertions, 0 deletions
diff --git a/test/std/utilities/variant/variant.variant/variant.swap/swap.pass.cpp b/test/std/utilities/variant/variant.variant/variant.swap/swap.pass.cpp
new file mode 100644
index 000000000000..416c6b4e334d
--- /dev/null
+++ b/test/std/utilities/variant/variant.variant/variant.swap/swap.pass.cpp
@@ -0,0 +1,591 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <variant>
+
+// template <class ...Types> class variant;
+
+// void swap(variant& rhs) noexcept(see below)
+
+#include <cassert>
+#include <string>
+#include <type_traits>
+#include <variant>
+
+#include "test_convertible.hpp"
+#include "test_macros.h"
+#include "variant_test_helpers.hpp"
+
+struct NotSwappable {};
+void swap(NotSwappable &, NotSwappable &) = delete;
+
+struct NotCopyable {
+  NotCopyable() = default;
+  NotCopyable(const NotCopyable &) = delete;
+  NotCopyable &operator=(const NotCopyable &) = delete;
+};
+
+struct NotCopyableWithSwap {
+  NotCopyableWithSwap() = default;
+  NotCopyableWithSwap(const NotCopyableWithSwap &) = delete;
+  NotCopyableWithSwap &operator=(const NotCopyableWithSwap &) = delete;
+};
+void swap(NotCopyableWithSwap &, NotCopyableWithSwap) {}
+
+struct NotMoveAssignable {
+  NotMoveAssignable() = default;
+  NotMoveAssignable(NotMoveAssignable &&) = default;
+  NotMoveAssignable &operator=(NotMoveAssignable &&) = delete;
+};
+
+struct NotMoveAssignableWithSwap {
+  NotMoveAssignableWithSwap() = default;
+  NotMoveAssignableWithSwap(NotMoveAssignableWithSwap &&) = default;
+  NotMoveAssignableWithSwap &operator=(NotMoveAssignableWithSwap &&) = delete;
+};
+void swap(NotMoveAssignableWithSwap &, NotMoveAssignableWithSwap &) noexcept {}
+
+template <bool Throws> void do_throw() {}
+
+template <> void do_throw<true>() {
+#ifndef TEST_HAS_NO_EXCEPTIONS
+  throw 42;
+#else
+  std::abort();
+#endif
+}
+
+template <bool NT_Copy, bool NT_Move, bool NT_CopyAssign, bool NT_MoveAssign,
+          bool NT_Swap, bool EnableSwap = true>
+struct NothrowTypeImp {
+  static int move_called;
+  static int move_assign_called;
+  static int swap_called;
+  static void reset() { move_called = move_assign_called = swap_called = 0; }
+  NothrowTypeImp() = default;
+  explicit NothrowTypeImp(int v) : value(v) {}
+  NothrowTypeImp(const NothrowTypeImp &o) noexcept(NT_Copy) : value(o.value) {
+    assert(false);
+  } // never called by test
+  NothrowTypeImp(NothrowTypeImp &&o) noexcept(NT_Move) : value(o.value) {
+    ++move_called;
+    do_throw<!NT_Move>();
+    o.value = -1;
+  }
+  NothrowTypeImp &operator=(const NothrowTypeImp &) noexcept(NT_CopyAssign) {
+    assert(false);
+    return *this;
+  } // never called by the tests
+  NothrowTypeImp &operator=(NothrowTypeImp &&o) noexcept(NT_MoveAssign) {
+    ++move_assign_called;
+    do_throw<!NT_MoveAssign>();
+    value = o.value;
+    o.value = -1;
+    return *this;
+  }
+  int value;
+};
+template <bool NT_Copy, bool NT_Move, bool NT_CopyAssign, bool NT_MoveAssign,
+          bool NT_Swap, bool EnableSwap>
+int NothrowTypeImp<NT_Copy, NT_Move, NT_CopyAssign, NT_MoveAssign, NT_Swap,
+                   EnableSwap>::move_called = 0;
+template <bool NT_Copy, bool NT_Move, bool NT_CopyAssign, bool NT_MoveAssign,
+          bool NT_Swap, bool EnableSwap>
+int NothrowTypeImp<NT_Copy, NT_Move, NT_CopyAssign, NT_MoveAssign, NT_Swap,
+                   EnableSwap>::move_assign_called = 0;
+template <bool NT_Copy, bool NT_Move, bool NT_CopyAssign, bool NT_MoveAssign,
+          bool NT_Swap, bool EnableSwap>
+int NothrowTypeImp<NT_Copy, NT_Move, NT_CopyAssign, NT_MoveAssign, NT_Swap,
+                   EnableSwap>::swap_called = 0;
+
+template <bool NT_Copy, bool NT_Move, bool NT_CopyAssign, bool NT_MoveAssign,
+          bool NT_Swap>
+void swap(NothrowTypeImp<NT_Copy, NT_Move, NT_CopyAssign, NT_MoveAssign,
+                         NT_Swap, true> &lhs,
+          NothrowTypeImp<NT_Copy, NT_Move, NT_CopyAssign, NT_MoveAssign,
+                         NT_Swap, true> &rhs) noexcept(NT_Swap) {
+  lhs.swap_called++;
+  do_throw<!NT_Swap>();
+  int tmp = lhs.value;
+  lhs.value = rhs.value;
+  rhs.value = tmp;
+}
+
+// throwing copy, nothrow move ctor/assign, no swap provided
+using NothrowMoveable = NothrowTypeImp<false, true, false, true, false, false>;
+// throwing copy and move assign, nothrow move ctor, no swap provided
+using NothrowMoveCtor = NothrowTypeImp<false, true, false, false, false, false>;
+// nothrow move ctor, throwing move assignment, swap provided
+using NothrowMoveCtorWithThrowingSwap =
+    NothrowTypeImp<false, true, false, false, false, true>;
+// throwing move ctor, nothrow move assignment, no swap provided
+using ThrowingMoveCtor =
+    NothrowTypeImp<false, false, false, true, false, false>;
+// throwing special members, nothrowing swap
+using ThrowingTypeWithNothrowSwap =
+    NothrowTypeImp<false, false, false, false, true, true>;
+using NothrowTypeWithThrowingSwap =
+    NothrowTypeImp<true, true, true, true, false, true>;
+// throwing move assign with nothrow move and nothrow swap
+using ThrowingMoveAssignNothrowMoveCtorWithSwap =
+    NothrowTypeImp<false, true, false, false, true, true>;
+// throwing move assign with nothrow move but no swap.
+using ThrowingMoveAssignNothrowMoveCtor =
+    NothrowTypeImp<false, true, false, false, false, false>;
+
+struct NonThrowingNonNoexceptType {
+  static int move_called;
+  static void reset() { move_called = 0; }
+  NonThrowingNonNoexceptType() = default;
+  NonThrowingNonNoexceptType(int v) : value(v) {}
+  NonThrowingNonNoexceptType(NonThrowingNonNoexceptType &&o) noexcept(false)
+      : value(o.value) {
+    ++move_called;
+    o.value = -1;
+  }
+  NonThrowingNonNoexceptType &
+  operator=(NonThrowingNonNoexceptType &&) noexcept(false) {
+    assert(false); // never called by the tests.
+    return *this;
+  }
+  int value;
+};
+int NonThrowingNonNoexceptType::move_called = 0;
+
+struct ThrowsOnSecondMove {
+  int value;
+  int move_count;
+  ThrowsOnSecondMove(int v) : value(v), move_count(0) {}
+  ThrowsOnSecondMove(ThrowsOnSecondMove &&o) noexcept(false)
+      : value(o.value), move_count(o.move_count + 1) {
+    if (move_count == 2)
+      do_throw<true>();
+    o.value = -1;
+  }
+  ThrowsOnSecondMove &operator=(ThrowsOnSecondMove &&) {
+    assert(false); // not called by test
+    return *this;
+  }
+};
+
+void test_swap_valueless_by_exception() {
+#ifndef TEST_HAS_NO_EXCEPTIONS
+  using V = std::variant<int, MakeEmptyT>;
+  { // both empty
+    V v1;
+    makeEmpty(v1);
+    V v2;
+    makeEmpty(v2);
+    assert(MakeEmptyT::alive == 0);
+    { // member swap
+      v1.swap(v2);
+      assert(v1.valueless_by_exception());
+      assert(v2.valueless_by_exception());
+      assert(MakeEmptyT::alive == 0);
+    }
+    { // non-member swap
+      swap(v1, v2);
+      assert(v1.valueless_by_exception());
+      assert(v2.valueless_by_exception());
+      assert(MakeEmptyT::alive == 0);
+    }
+  }
+  { // only one empty
+    V v1(42);
+    V v2;
+    makeEmpty(v2);
+    { // member swap
+      v1.swap(v2);
+      assert(v1.valueless_by_exception());
+      assert(std::get<0>(v2) == 42);
+      // swap again
+      v2.swap(v1);
+      assert(v2.valueless_by_exception());
+      assert(std::get<0>(v1) == 42);
+    }
+    { // non-member swap
+      swap(v1, v2);
+      assert(v1.valueless_by_exception());
+      assert(std::get<0>(v2) == 42);
+      // swap again
+      swap(v1, v2);
+      assert(v2.valueless_by_exception());
+      assert(std::get<0>(v1) == 42);
+    }
+  }
+#endif
+}
+
+void test_swap_same_alternative() {
+  {
+    using T = ThrowingTypeWithNothrowSwap;
+    using V = std::variant<T, int>;
+    T::reset();
+    V v1(std::in_place_index<0>, 42);
+    V v2(std::in_place_index<0>, 100);
+    v1.swap(v2);
+    assert(T::swap_called == 1);
+    assert(std::get<0>(v1).value == 100);
+    assert(std::get<0>(v2).value == 42);
+    swap(v1, v2);
+    assert(T::swap_called == 2);
+    assert(std::get<0>(v1).value == 42);
+    assert(std::get<0>(v2).value == 100);
+  }
+  {
+    using T = NothrowMoveable;
+    using V = std::variant<T, int>;
+    T::reset();
+    V v1(std::in_place_index<0>, 42);
+    V v2(std::in_place_index<0>, 100);
+    v1.swap(v2);
+    assert(T::swap_called == 0);
+    assert(T::move_called == 1);
+    assert(T::move_assign_called == 2);
+    assert(std::get<0>(v1).value == 100);
+    assert(std::get<0>(v2).value == 42);
+    T::reset();
+    swap(v1, v2);
+    assert(T::swap_called == 0);
+    assert(T::move_called == 1);
+    assert(T::move_assign_called == 2);
+    assert(std::get<0>(v1).value == 42);
+    assert(std::get<0>(v2).value == 100);
+  }
+#ifndef TEST_HAS_NO_EXCEPTIONS
+  {
+    using T = NothrowTypeWithThrowingSwap;
+    using V = std::variant<T, int>;
+    T::reset();
+    V v1(std::in_place_index<0>, 42);
+    V v2(std::in_place_index<0>, 100);
+    try {
+      v1.swap(v2);
+      assert(false);
+    } catch (int) {
+    }
+    assert(T::swap_called == 1);
+    assert(T::move_called == 0);
+    assert(T::move_assign_called == 0);
+    assert(std::get<0>(v1).value == 42);
+    assert(std::get<0>(v2).value == 100);
+  }
+  {
+    using T = ThrowingMoveCtor;
+    using V = std::variant<T, int>;
+    T::reset();
+    V v1(std::in_place_index<0>, 42);
+    V v2(std::in_place_index<0>, 100);
+    try {
+      v1.swap(v2);
+      assert(false);
+    } catch (int) {
+    }
+    assert(T::move_called == 1); // call threw
+    assert(T::move_assign_called == 0);
+    assert(std::get<0>(v1).value ==
+           42); // throw happened before v1 was moved from
+    assert(std::get<0>(v2).value == 100);
+  }
+  {
+    using T = ThrowingMoveAssignNothrowMoveCtor;
+    using V = std::variant<T, int>;
+    T::reset();
+    V v1(std::in_place_index<0>, 42);
+    V v2(std::in_place_index<0>, 100);
+    try {
+      v1.swap(v2);
+      assert(false);
+    } catch (int) {
+    }
+    assert(T::move_called == 1);
+    assert(T::move_assign_called == 1);  // call threw and didn't complete
+    assert(std::get<0>(v1).value == -1); // v1 was moved from
+    assert(std::get<0>(v2).value == 100);
+  }
+#endif
+}
+
+void test_swap_different_alternatives() {
+  {
+    using T = NothrowMoveCtorWithThrowingSwap;
+    using V = std::variant<T, int>;
+    T::reset();
+    V v1(std::in_place_index<0>, 42);
+    V v2(std::in_place_index<1>, 100);
+    v1.swap(v2);
+    assert(T::swap_called == 0);
+    // The libc++ implementation double copies the argument, and not
+    // the variant swap is called on.
+    LIBCPP_ASSERT(T::move_called == 1);
+    assert(T::move_called <= 2);
+    assert(T::move_assign_called == 0);
+    assert(std::get<1>(v1) == 100);
+    assert(std::get<0>(v2).value == 42);
+    T::reset();
+    swap(v1, v2);
+    assert(T::swap_called == 0);
+    LIBCPP_ASSERT(T::move_called == 2);
+    assert(T::move_called <= 2);
+    assert(T::move_assign_called == 0);
+    assert(std::get<0>(v1).value == 42);
+    assert(std::get<1>(v2) == 100);
+  }
+#ifndef TEST_HAS_NO_EXCEPTIONS
+  {
+    using T1 = ThrowingTypeWithNothrowSwap;
+    using T2 = NonThrowingNonNoexceptType;
+    using V = std::variant<T1, T2>;
+    T1::reset();
+    T2::reset();
+    V v1(std::in_place_index<0>, 42);
+    V v2(std::in_place_index<1>, 100);
+    try {
+      v1.swap(v2);
+      assert(false);
+    } catch (int) {
+    }
+    assert(T1::swap_called == 0);
+    assert(T1::move_called == 1); // throws
+    assert(T1::move_assign_called == 0);
+    // FIXME: libc++ shouldn't move from T2 here.
+    LIBCPP_ASSERT(T2::move_called == 1);
+    assert(T2::move_called <= 1);
+    assert(std::get<0>(v1).value == 42);
+    if (T2::move_called != 0)
+      assert(v2.valueless_by_exception());
+    else
+      assert(std::get<1>(v2).value == 100);
+  }
+  {
+    using T1 = NonThrowingNonNoexceptType;
+    using T2 = ThrowingTypeWithNothrowSwap;
+    using V = std::variant<T1, T2>;
+    T1::reset();
+    T2::reset();
+    V v1(std::in_place_index<0>, 42);
+    V v2(std::in_place_index<1>, 100);
+    try {
+      v1.swap(v2);
+      assert(false);
+    } catch (int) {
+    }
+    LIBCPP_ASSERT(T1::move_called == 0);
+    assert(T1::move_called <= 1);
+    assert(T2::swap_called == 0);
+    assert(T2::move_called == 1); // throws
+    assert(T2::move_assign_called == 0);
+    if (T1::move_called != 0)
+      assert(v1.valueless_by_exception());
+    else
+      assert(std::get<0>(v1).value == 42);
+    assert(std::get<1>(v2).value == 100);
+  }
+// FIXME: The tests below are just very libc++ specific
+#ifdef _LIBCPP_VERSION
+  {
+    using T1 = ThrowsOnSecondMove;
+    using T2 = NonThrowingNonNoexceptType;
+    using V = std::variant<T1, T2>;
+    T2::reset();
+    V v1(std::in_place_index<0>, 42);
+    V v2(std::in_place_index<1>, 100);
+    v1.swap(v2);
+    assert(T2::move_called == 2);
+    assert(std::get<1>(v1).value == 100);
+    assert(std::get<0>(v2).value == 42);
+    assert(std::get<0>(v2).move_count == 1);
+  }
+  {
+    using T1 = NonThrowingNonNoexceptType;
+    using T2 = ThrowsOnSecondMove;
+    using V = std::variant<T1, T2>;
+    T1::reset();
+    V v1(std::in_place_index<0>, 42);
+    V v2(std::in_place_index<1>, 100);
+    try {
+      v1.swap(v2);
+      assert(false);
+    } catch (int) {
+    }
+    assert(T1::move_called == 1);
+    assert(v1.valueless_by_exception());
+    assert(std::get<0>(v2).value == 42);
+  }
+#endif
+// testing libc++ extension. If either variant stores a nothrow move
+// constructible type v1.swap(v2) provides the strong exception safety
+// guarantee.
+#ifdef _LIBCPP_VERSION
+  {
+
+    using T1 = ThrowingTypeWithNothrowSwap;
+    using T2 = NothrowMoveable;
+    using V = std::variant<T1, T2>;
+    T1::reset();
+    T2::reset();
+    V v1(std::in_place_index<0>, 42);
+    V v2(std::in_place_index<1>, 100);
+    try {
+      v1.swap(v2);
+      assert(false);
+    } catch (int) {
+    }
+    assert(T1::swap_called == 0);
+    assert(T1::move_called == 1);
+    assert(T1::move_assign_called == 0);
+    assert(T2::swap_called == 0);
+    assert(T2::move_called == 2);
+    assert(T2::move_assign_called == 0);
+    assert(std::get<0>(v1).value == 42);
+    assert(std::get<1>(v2).value == 100);
+    // swap again, but call v2's swap.
+    T1::reset();
+    T2::reset();
+    try {
+      v2.swap(v1);
+      assert(false);
+    } catch (int) {
+    }
+    assert(T1::swap_called == 0);
+    assert(T1::move_called == 1);
+    assert(T1::move_assign_called == 0);
+    assert(T2::swap_called == 0);
+    assert(T2::move_called == 2);
+    assert(T2::move_assign_called == 0);
+    assert(std::get<0>(v1).value == 42);
+    assert(std::get<1>(v2).value == 100);
+  }
+#endif // _LIBCPP_VERSION
+#endif
+}
+
+template <class Var>
+constexpr auto has_swap_member_imp(int)
+    -> decltype(std::declval<Var &>().swap(std::declval<Var &>()), true) {
+  return true;
+}
+
+template <class Var> constexpr auto has_swap_member_imp(long) -> bool {
+  return false;
+}
+
+template <class Var> constexpr bool has_swap_member() {
+  return has_swap_member_imp<Var>(0);
+}
+
+void test_swap_sfinae() {
+  {
+    // This variant type does not provide either a member or non-member swap
+    // but is still swappable via the generic swap algorithm, since the
+    // variant is move constructible and move assignable.
+    using V = std::variant<int, NotSwappable>;
+    LIBCPP_STATIC_ASSERT(!has_swap_member<V>());
+    static_assert(std::is_swappable_v<V>, "");
+  }
+  {
+    using V = std::variant<int, NotCopyable>;
+    LIBCPP_STATIC_ASSERT(!has_swap_member<V>(), "");
+    static_assert(!std::is_swappable_v<V>, "");
+  }
+  {
+    using V = std::variant<int, NotCopyableWithSwap>;
+    LIBCPP_STATIC_ASSERT(!has_swap_member<V>(), "");
+    static_assert(!std::is_swappable_v<V>, "");
+  }
+  {
+    using V = std::variant<int, NotMoveAssignable>;
+    LIBCPP_STATIC_ASSERT(!has_swap_member<V>(), "");
+    static_assert(!std::is_swappable_v<V>, "");
+  }
+}
+
+void test_swap_noexcept() {
+  {
+    using V = std::variant<int, NothrowMoveable>;
+    static_assert(std::is_swappable_v<V> && has_swap_member<V>(), "");
+    static_assert(std::is_nothrow_swappable_v<V>, "");
+    // instantiate swap
+    V v1, v2;
+    v1.swap(v2);
+    swap(v1, v2);
+  }
+  {
+    using V = std::variant<int, NothrowMoveCtor>;
+    static_assert(std::is_swappable_v<V> && has_swap_member<V>(), "");
+    static_assert(!std::is_nothrow_swappable_v<V>, "");
+    // instantiate swap
+    V v1, v2;
+    v1.swap(v2);
+    swap(v1, v2);
+  }
+  {
+    using V = std::variant<int, ThrowingTypeWithNothrowSwap>;
+    static_assert(std::is_swappable_v<V> && has_swap_member<V>(), "");
+    static_assert(!std::is_nothrow_swappable_v<V>, "");
+    // instantiate swap
+    V v1, v2;
+    v1.swap(v2);
+    swap(v1, v2);
+  }
+  {
+    using V = std::variant<int, ThrowingMoveAssignNothrowMoveCtor>;
+    static_assert(std::is_swappable_v<V> && has_swap_member<V>(), "");
+    static_assert(!std::is_nothrow_swappable_v<V>, "");
+    // instantiate swap
+    V v1, v2;
+    v1.swap(v2);
+    swap(v1, v2);
+  }
+  {
+    using V = std::variant<int, ThrowingMoveAssignNothrowMoveCtorWithSwap>;
+    static_assert(std::is_swappable_v<V> && has_swap_member<V>(), "");
+    static_assert(std::is_nothrow_swappable_v<V>, "");
+    // instantiate swap
+    V v1, v2;
+    v1.swap(v2);
+    swap(v1, v2);
+  }
+  {
+    using V = std::variant<int, NotMoveAssignableWithSwap>;
+    static_assert(std::is_swappable_v<V> && has_swap_member<V>(), "");
+    static_assert(std::is_nothrow_swappable_v<V>, "");
+    // instantiate swap
+    V v1, v2;
+    v1.swap(v2);
+    swap(v1, v2);
+  }
+  {
+    // This variant type does not provide either a member or non-member swap
+    // but is still swappable via the generic swap algorithm, since the
+    // variant is move constructible and move assignable.
+    using V = std::variant<int, NotSwappable>;
+    LIBCPP_STATIC_ASSERT(!has_swap_member<V>());
+    static_assert(std::is_swappable_v<V>, "");
+    static_assert(std::is_nothrow_swappable_v<V>, "");
+    V v1, v2;
+    swap(v1, v2);
+  }
+}
+
+#ifdef _LIBCPP_VERSION
+// This is why variant should SFINAE member swap. :-)
+template class std::variant<int, NotSwappable>;
+#endif
+
+int main() {
+  test_swap_valueless_by_exception();
+  test_swap_same_alternative();
+  test_swap_different_alternatives();
+  test_swap_sfinae();
+  test_swap_noexcept();
+}