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			C++
		
	
			
		
		
	
	
			604 lines
		
	
	
		
			17 KiB
		
	
	
	
		
			C++
		
	
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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//                     The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++98, c++03, c++11, c++14
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// The following compilers don't generate constexpr special members correctly.
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// XFAIL: clang-3.5, clang-3.6, clang-3.7, clang-3.8
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// XFAIL: apple-clang-6, apple-clang-7, apple-clang-8.0
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// XFAIL: availability=macosx10.13
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// XFAIL: availability=macosx10.12
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// XFAIL: availability=macosx10.11
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// XFAIL: availability=macosx10.10
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// XFAIL: availability=macosx10.9
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// XFAIL: availability=macosx10.8
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// XFAIL: availability=macosx10.7
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// <variant>
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// template <class ...Types> class variant;
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// variant& operator=(variant const&); // constexpr in C++20
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#include <cassert>
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#include <string>
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#include <type_traits>
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#include <variant>
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#include "test_macros.h"
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struct NoCopy {
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  NoCopy(const NoCopy &) = delete;
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  NoCopy &operator=(const NoCopy &) = default;
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};
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struct CopyOnly {
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  CopyOnly(const CopyOnly &) = default;
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  CopyOnly(CopyOnly &&) = delete;
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  CopyOnly &operator=(const CopyOnly &) = default;
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  CopyOnly &operator=(CopyOnly &&) = delete;
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};
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struct MoveOnly {
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  MoveOnly(const MoveOnly &) = delete;
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  MoveOnly(MoveOnly &&) = default;
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  MoveOnly &operator=(const MoveOnly &) = default;
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};
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struct MoveOnlyNT {
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  MoveOnlyNT(const MoveOnlyNT &) = delete;
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  MoveOnlyNT(MoveOnlyNT &&) {}
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  MoveOnlyNT &operator=(const MoveOnlyNT &) = default;
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};
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struct CopyAssign {
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  static int alive;
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  static int copy_construct;
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  static int copy_assign;
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  static int move_construct;
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  static int move_assign;
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  static void reset() {
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    copy_construct = copy_assign = move_construct = move_assign = alive = 0;
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  }
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  CopyAssign(int v) : value(v) { ++alive; }
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  CopyAssign(const CopyAssign &o) : value(o.value) {
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    ++alive;
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    ++copy_construct;
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  }
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  CopyAssign(CopyAssign &&o) noexcept : value(o.value) {
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    o.value = -1;
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    ++alive;
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    ++move_construct;
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  }
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  CopyAssign &operator=(const CopyAssign &o) {
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    value = o.value;
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    ++copy_assign;
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    return *this;
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  }
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  CopyAssign &operator=(CopyAssign &&o) noexcept {
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    value = o.value;
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    o.value = -1;
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    ++move_assign;
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    return *this;
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  }
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  ~CopyAssign() { --alive; }
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  int value;
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};
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int CopyAssign::alive = 0;
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int CopyAssign::copy_construct = 0;
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int CopyAssign::copy_assign = 0;
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int CopyAssign::move_construct = 0;
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int CopyAssign::move_assign = 0;
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struct CopyMaybeThrows {
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  CopyMaybeThrows(const CopyMaybeThrows &);
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  CopyMaybeThrows &operator=(const CopyMaybeThrows &);
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};
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struct CopyDoesThrow {
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  CopyDoesThrow(const CopyDoesThrow &) noexcept(false);
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  CopyDoesThrow &operator=(const CopyDoesThrow &) noexcept(false);
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};
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struct NTCopyAssign {
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  constexpr NTCopyAssign(int v) : value(v) {}
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  NTCopyAssign(const NTCopyAssign &) = default;
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  NTCopyAssign(NTCopyAssign &&) = default;
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  NTCopyAssign &operator=(const NTCopyAssign &that) {
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    value = that.value;
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    return *this;
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  };
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  NTCopyAssign &operator=(NTCopyAssign &&) = delete;
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  int value;
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};
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static_assert(!std::is_trivially_copy_assignable<NTCopyAssign>::value, "");
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static_assert(std::is_copy_assignable<NTCopyAssign>::value, "");
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struct TCopyAssign {
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  constexpr TCopyAssign(int v) : value(v) {}
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  TCopyAssign(const TCopyAssign &) = default;
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  TCopyAssign(TCopyAssign &&) = default;
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  TCopyAssign &operator=(const TCopyAssign &) = default;
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  TCopyAssign &operator=(TCopyAssign &&) = delete;
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  int value;
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};
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static_assert(std::is_trivially_copy_assignable<TCopyAssign>::value, "");
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struct TCopyAssignNTMoveAssign {
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  constexpr TCopyAssignNTMoveAssign(int v) : value(v) {}
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  TCopyAssignNTMoveAssign(const TCopyAssignNTMoveAssign &) = default;
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  TCopyAssignNTMoveAssign(TCopyAssignNTMoveAssign &&) = default;
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  TCopyAssignNTMoveAssign &operator=(const TCopyAssignNTMoveAssign &) = default;
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  TCopyAssignNTMoveAssign &operator=(TCopyAssignNTMoveAssign &&that) {
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    value = that.value;
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    that.value = -1;
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    return *this;
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  }
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  int value;
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};
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static_assert(std::is_trivially_copy_assignable_v<TCopyAssignNTMoveAssign>, "");
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#ifndef TEST_HAS_NO_EXCEPTIONS
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struct CopyThrows {
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  CopyThrows() = default;
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  CopyThrows(const CopyThrows &) { throw 42; }
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  CopyThrows &operator=(const CopyThrows &) { throw 42; }
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};
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struct CopyCannotThrow {
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  static int alive;
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  CopyCannotThrow() { ++alive; }
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  CopyCannotThrow(const CopyCannotThrow &) noexcept { ++alive; }
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  CopyCannotThrow(CopyCannotThrow &&) noexcept { assert(false); }
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  CopyCannotThrow &operator=(const CopyCannotThrow &) noexcept = default;
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  CopyCannotThrow &operator=(CopyCannotThrow &&) noexcept { assert(false); return *this; }
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};
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int CopyCannotThrow::alive = 0;
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struct MoveThrows {
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  static int alive;
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  MoveThrows() { ++alive; }
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  MoveThrows(const MoveThrows &) { ++alive; }
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  MoveThrows(MoveThrows &&) { throw 42; }
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  MoveThrows &operator=(const MoveThrows &) { return *this; }
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  MoveThrows &operator=(MoveThrows &&) { throw 42; }
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  ~MoveThrows() { --alive; }
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};
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int MoveThrows::alive = 0;
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struct MakeEmptyT {
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  static int alive;
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  MakeEmptyT() { ++alive; }
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  MakeEmptyT(const MakeEmptyT &) {
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    ++alive;
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    // Don't throw from the copy constructor since variant's assignment
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    // operator performs a copy before committing to the assignment.
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  }
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  MakeEmptyT(MakeEmptyT &&) { throw 42; }
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  MakeEmptyT &operator=(const MakeEmptyT &) { throw 42; }
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  MakeEmptyT &operator=(MakeEmptyT &&) { throw 42; }
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  ~MakeEmptyT() { --alive; }
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};
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int MakeEmptyT::alive = 0;
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template <class Variant> void makeEmpty(Variant &v) {
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  Variant v2(std::in_place_type<MakeEmptyT>);
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  try {
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    v = std::move(v2);
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    assert(false);
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  } catch (...) {
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    assert(v.valueless_by_exception());
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  }
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}
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#endif // TEST_HAS_NO_EXCEPTIONS
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void test_copy_assignment_not_noexcept() {
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  {
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    using V = std::variant<CopyMaybeThrows>;
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    static_assert(!std::is_nothrow_copy_assignable<V>::value, "");
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  }
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  {
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    using V = std::variant<int, CopyDoesThrow>;
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    static_assert(!std::is_nothrow_copy_assignable<V>::value, "");
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  }
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}
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void test_copy_assignment_sfinae() {
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  {
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    using V = std::variant<int, long>;
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    static_assert(std::is_copy_assignable<V>::value, "");
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  }
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  {
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    using V = std::variant<int, CopyOnly>;
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    static_assert(std::is_copy_assignable<V>::value, "");
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  }
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  {
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    using V = std::variant<int, NoCopy>;
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    static_assert(!std::is_copy_assignable<V>::value, "");
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  }
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  {
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    using V = std::variant<int, MoveOnly>;
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    static_assert(!std::is_copy_assignable<V>::value, "");
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  }
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  {
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    using V = std::variant<int, MoveOnlyNT>;
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    static_assert(!std::is_copy_assignable<V>::value, "");
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  }
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  // Make sure we properly propagate triviality (see P0602R4).
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#if TEST_STD_VER > 17
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  {
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    using V = std::variant<int, long>;
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    static_assert(std::is_trivially_copy_assignable<V>::value, "");
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  }
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  {
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    using V = std::variant<int, NTCopyAssign>;
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    static_assert(!std::is_trivially_copy_assignable<V>::value, "");
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    static_assert(std::is_copy_assignable<V>::value, "");
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  }
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  {
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    using V = std::variant<int, TCopyAssign>;
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    static_assert(std::is_trivially_copy_assignable<V>::value, "");
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  }
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  {
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    using V = std::variant<int, TCopyAssignNTMoveAssign>;
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    static_assert(std::is_trivially_copy_assignable<V>::value, "");
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  }
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  {
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    using V = std::variant<int, CopyOnly>;
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    static_assert(std::is_trivially_copy_assignable<V>::value, "");
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  }
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#endif // > C++17
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}
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void test_copy_assignment_empty_empty() {
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#ifndef TEST_HAS_NO_EXCEPTIONS
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  using MET = MakeEmptyT;
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  {
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    using V = std::variant<int, long, MET>;
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    V v1(std::in_place_index<0>);
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    makeEmpty(v1);
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    V v2(std::in_place_index<0>);
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    makeEmpty(v2);
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    V &vref = (v1 = v2);
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    assert(&vref == &v1);
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    assert(v1.valueless_by_exception());
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    assert(v1.index() == std::variant_npos);
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  }
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#endif // TEST_HAS_NO_EXCEPTIONS
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}
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void test_copy_assignment_non_empty_empty() {
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#ifndef TEST_HAS_NO_EXCEPTIONS
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  using MET = MakeEmptyT;
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  {
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    using V = std::variant<int, MET>;
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    V v1(std::in_place_index<0>, 42);
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    V v2(std::in_place_index<0>);
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    makeEmpty(v2);
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    V &vref = (v1 = v2);
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    assert(&vref == &v1);
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    assert(v1.valueless_by_exception());
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    assert(v1.index() == std::variant_npos);
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  }
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  {
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    using V = std::variant<int, MET, std::string>;
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    V v1(std::in_place_index<2>, "hello");
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    V v2(std::in_place_index<0>);
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    makeEmpty(v2);
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    V &vref = (v1 = v2);
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    assert(&vref == &v1);
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    assert(v1.valueless_by_exception());
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    assert(v1.index() == std::variant_npos);
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  }
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#endif // TEST_HAS_NO_EXCEPTIONS
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}
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void test_copy_assignment_empty_non_empty() {
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#ifndef TEST_HAS_NO_EXCEPTIONS
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  using MET = MakeEmptyT;
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  {
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    using V = std::variant<int, MET>;
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    V v1(std::in_place_index<0>);
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    makeEmpty(v1);
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    V v2(std::in_place_index<0>, 42);
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    V &vref = (v1 = v2);
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    assert(&vref == &v1);
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    assert(v1.index() == 0);
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    assert(std::get<0>(v1) == 42);
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  }
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  {
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    using V = std::variant<int, MET, std::string>;
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    V v1(std::in_place_index<0>);
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    makeEmpty(v1);
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    V v2(std::in_place_type<std::string>, "hello");
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    V &vref = (v1 = v2);
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    assert(&vref == &v1);
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    assert(v1.index() == 2);
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    assert(std::get<2>(v1) == "hello");
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  }
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#endif // TEST_HAS_NO_EXCEPTIONS
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}
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template <typename T> struct Result { size_t index; T value; };
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void test_copy_assignment_same_index() {
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  {
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    using V = std::variant<int>;
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    V v1(43);
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    V v2(42);
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    V &vref = (v1 = v2);
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    assert(&vref == &v1);
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    assert(v1.index() == 0);
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    assert(std::get<0>(v1) == 42);
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  }
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  {
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    using V = std::variant<int, long, unsigned>;
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    V v1(43l);
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    V v2(42l);
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    V &vref = (v1 = v2);
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    assert(&vref == &v1);
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    assert(v1.index() == 1);
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    assert(std::get<1>(v1) == 42);
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  }
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  {
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    using V = std::variant<int, CopyAssign, unsigned>;
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    V v1(std::in_place_type<CopyAssign>, 43);
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    V v2(std::in_place_type<CopyAssign>, 42);
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    CopyAssign::reset();
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    V &vref = (v1 = v2);
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    assert(&vref == &v1);
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    assert(v1.index() == 1);
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    assert(std::get<1>(v1).value == 42);
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    assert(CopyAssign::copy_construct == 0);
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    assert(CopyAssign::move_construct == 0);
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    assert(CopyAssign::copy_assign == 1);
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  }
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#ifndef TEST_HAS_NO_EXCEPTIONS
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  using MET = MakeEmptyT;
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  {
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    using V = std::variant<int, MET, std::string>;
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    V v1(std::in_place_type<MET>);
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    MET &mref = std::get<1>(v1);
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    V v2(std::in_place_type<MET>);
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    try {
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      v1 = v2;
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      assert(false);
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    } catch (...) {
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    }
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    assert(v1.index() == 1);
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    assert(&std::get<1>(v1) == &mref);
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  }
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#endif // TEST_HAS_NO_EXCEPTIONS
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  // Make sure we properly propagate triviality, which implies constexpr-ness (see P0602R4).
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#if TEST_STD_VER > 17
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  {
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    struct {
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      constexpr Result<int> operator()() const {
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        using V = std::variant<int>;
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        V v(43);
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        V v2(42);
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        v = v2;
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        return {v.index(), std::get<0>(v)};
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      }
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    } test;
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    constexpr auto result = test();
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    static_assert(result.index == 0, "");
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    static_assert(result.value == 42, "");
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  }
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						|
  {
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    struct {
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      constexpr Result<long> operator()() const {
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        using V = std::variant<int, long, unsigned>;
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        V v(43l);
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        V v2(42l);
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        v = v2;
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        return {v.index(), std::get<1>(v)};
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      }
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    } test;
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    constexpr auto result = test();
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    static_assert(result.index == 1, "");
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    static_assert(result.value == 42l, "");
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  }
 | 
						|
  {
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    struct {
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      constexpr Result<int> operator()() const {
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        using V = std::variant<int, TCopyAssign, unsigned>;
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        V v(std::in_place_type<TCopyAssign>, 43);
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						|
        V v2(std::in_place_type<TCopyAssign>, 42);
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        v = v2;
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        return {v.index(), std::get<1>(v).value};
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      }
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    } test;
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    constexpr auto result = test();
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						|
    static_assert(result.index == 1, "");
 | 
						|
    static_assert(result.value == 42, "");
 | 
						|
  }
 | 
						|
  {
 | 
						|
    struct {
 | 
						|
      constexpr Result<int> operator()() const {
 | 
						|
        using V = std::variant<int, TCopyAssignNTMoveAssign, unsigned>;
 | 
						|
        V v(std::in_place_type<TCopyAssignNTMoveAssign>, 43);
 | 
						|
        V v2(std::in_place_type<TCopyAssignNTMoveAssign>, 42);
 | 
						|
        v = v2;
 | 
						|
        return {v.index(), std::get<1>(v).value};
 | 
						|
      }
 | 
						|
    } test;
 | 
						|
    constexpr auto result = test();
 | 
						|
    static_assert(result.index == 1, "");
 | 
						|
    static_assert(result.value == 42, "");
 | 
						|
  }
 | 
						|
#endif // > C++17
 | 
						|
}
 | 
						|
 | 
						|
void test_copy_assignment_different_index() {
 | 
						|
  {
 | 
						|
    using V = std::variant<int, long, unsigned>;
 | 
						|
    V v1(43);
 | 
						|
    V v2(42l);
 | 
						|
    V &vref = (v1 = v2);
 | 
						|
    assert(&vref == &v1);
 | 
						|
    assert(v1.index() == 1);
 | 
						|
    assert(std::get<1>(v1) == 42);
 | 
						|
  }
 | 
						|
  {
 | 
						|
    using V = std::variant<int, CopyAssign, unsigned>;
 | 
						|
    CopyAssign::reset();
 | 
						|
    V v1(std::in_place_type<unsigned>, 43);
 | 
						|
    V v2(std::in_place_type<CopyAssign>, 42);
 | 
						|
    assert(CopyAssign::copy_construct == 0);
 | 
						|
    assert(CopyAssign::move_construct == 0);
 | 
						|
    assert(CopyAssign::alive == 1);
 | 
						|
    V &vref = (v1 = v2);
 | 
						|
    assert(&vref == &v1);
 | 
						|
    assert(v1.index() == 1);
 | 
						|
    assert(std::get<1>(v1).value == 42);
 | 
						|
    assert(CopyAssign::alive == 2);
 | 
						|
    assert(CopyAssign::copy_construct == 1);
 | 
						|
    assert(CopyAssign::move_construct == 1);
 | 
						|
    assert(CopyAssign::copy_assign == 0);
 | 
						|
  }
 | 
						|
#ifndef TEST_HAS_NO_EXCEPTIONS
 | 
						|
  {
 | 
						|
    using V = std::variant<int, CopyThrows, std::string>;
 | 
						|
    V v1(std::in_place_type<std::string>, "hello");
 | 
						|
    V v2(std::in_place_type<CopyThrows>);
 | 
						|
    try {
 | 
						|
      v1 = v2;
 | 
						|
      assert(false);
 | 
						|
    } catch (...) { /* ... */
 | 
						|
    }
 | 
						|
    // Test that copy construction is used directly if move construction may throw,
 | 
						|
    // resulting in a valueless variant if copy throws.
 | 
						|
    assert(v1.valueless_by_exception());
 | 
						|
  }
 | 
						|
  {
 | 
						|
    using V = std::variant<int, MoveThrows, std::string>;
 | 
						|
    V v1(std::in_place_type<std::string>, "hello");
 | 
						|
    V v2(std::in_place_type<MoveThrows>);
 | 
						|
    assert(MoveThrows::alive == 1);
 | 
						|
    // Test that copy construction is used directly if move construction may throw.
 | 
						|
    v1 = v2;
 | 
						|
    assert(v1.index() == 1);
 | 
						|
    assert(v2.index() == 1);
 | 
						|
    assert(MoveThrows::alive == 2);
 | 
						|
  }
 | 
						|
  {
 | 
						|
    // Test that direct copy construction is preferred when it cannot throw.
 | 
						|
    using V = std::variant<int, CopyCannotThrow, std::string>;
 | 
						|
    V v1(std::in_place_type<std::string>, "hello");
 | 
						|
    V v2(std::in_place_type<CopyCannotThrow>);
 | 
						|
    assert(CopyCannotThrow::alive == 1);
 | 
						|
    v1 = v2;
 | 
						|
    assert(v1.index() == 1);
 | 
						|
    assert(v2.index() == 1);
 | 
						|
    assert(CopyCannotThrow::alive == 2);
 | 
						|
  }
 | 
						|
  {
 | 
						|
    using V = std::variant<int, CopyThrows, std::string>;
 | 
						|
    V v1(std::in_place_type<CopyThrows>);
 | 
						|
    V v2(std::in_place_type<std::string>, "hello");
 | 
						|
    V &vref = (v1 = v2);
 | 
						|
    assert(&vref == &v1);
 | 
						|
    assert(v1.index() == 2);
 | 
						|
    assert(std::get<2>(v1) == "hello");
 | 
						|
    assert(v2.index() == 2);
 | 
						|
    assert(std::get<2>(v2) == "hello");
 | 
						|
  }
 | 
						|
  {
 | 
						|
    using V = std::variant<int, MoveThrows, std::string>;
 | 
						|
    V v1(std::in_place_type<MoveThrows>);
 | 
						|
    V v2(std::in_place_type<std::string>, "hello");
 | 
						|
    V &vref = (v1 = v2);
 | 
						|
    assert(&vref == &v1);
 | 
						|
    assert(v1.index() == 2);
 | 
						|
    assert(std::get<2>(v1) == "hello");
 | 
						|
    assert(v2.index() == 2);
 | 
						|
    assert(std::get<2>(v2) == "hello");
 | 
						|
  }
 | 
						|
#endif // TEST_HAS_NO_EXCEPTIONS
 | 
						|
 | 
						|
  // Make sure we properly propagate triviality, which implies constexpr-ness (see P0602R4).
 | 
						|
#if TEST_STD_VER > 17
 | 
						|
  {
 | 
						|
    struct {
 | 
						|
      constexpr Result<long> operator()() const {
 | 
						|
        using V = std::variant<int, long, unsigned>;
 | 
						|
        V v(43);
 | 
						|
        V v2(42l);
 | 
						|
        v = v2;
 | 
						|
        return {v.index(), std::get<1>(v)};
 | 
						|
      }
 | 
						|
    } test;
 | 
						|
    constexpr auto result = test();
 | 
						|
    static_assert(result.index == 1, "");
 | 
						|
    static_assert(result.value == 42l, "");
 | 
						|
  }
 | 
						|
  {
 | 
						|
    struct {
 | 
						|
      constexpr Result<int> operator()() const {
 | 
						|
        using V = std::variant<int, TCopyAssign, unsigned>;
 | 
						|
        V v(std::in_place_type<unsigned>, 43);
 | 
						|
        V v2(std::in_place_type<TCopyAssign>, 42);
 | 
						|
        v = v2;
 | 
						|
        return {v.index(), std::get<1>(v).value};
 | 
						|
      }
 | 
						|
    } test;
 | 
						|
    constexpr auto result = test();
 | 
						|
    static_assert(result.index == 1, "");
 | 
						|
    static_assert(result.value == 42, "");
 | 
						|
  }
 | 
						|
#endif // > C++17
 | 
						|
}
 | 
						|
 | 
						|
template <size_t NewIdx, class ValueType>
 | 
						|
constexpr bool test_constexpr_assign_imp(
 | 
						|
    std::variant<long, void*, int>&& v, ValueType&& new_value)
 | 
						|
{
 | 
						|
  const std::variant<long, void*, int> cp(
 | 
						|
      std::forward<ValueType>(new_value));
 | 
						|
  v = cp;
 | 
						|
  return v.index() == NewIdx &&
 | 
						|
        std::get<NewIdx>(v) == std::get<NewIdx>(cp);
 | 
						|
}
 | 
						|
 | 
						|
void test_constexpr_copy_assignment() {
 | 
						|
  // Make sure we properly propagate triviality, which implies constexpr-ness (see P0602R4).
 | 
						|
#if TEST_STD_VER > 17
 | 
						|
  using V = std::variant<long, void*, int>;
 | 
						|
  static_assert(std::is_trivially_copyable<V>::value, "");
 | 
						|
  static_assert(std::is_trivially_copy_assignable<V>::value, "");
 | 
						|
  static_assert(test_constexpr_assign_imp<0>(V(42l), 101l), "");
 | 
						|
  static_assert(test_constexpr_assign_imp<0>(V(nullptr), 101l), "");
 | 
						|
  static_assert(test_constexpr_assign_imp<1>(V(42l), nullptr), "");
 | 
						|
  static_assert(test_constexpr_assign_imp<2>(V(42l), 101), "");
 | 
						|
#endif // > C++17
 | 
						|
}
 | 
						|
 | 
						|
int main() {
 | 
						|
  test_copy_assignment_empty_empty();
 | 
						|
  test_copy_assignment_non_empty_empty();
 | 
						|
  test_copy_assignment_empty_non_empty();
 | 
						|
  test_copy_assignment_same_index();
 | 
						|
  test_copy_assignment_different_index();
 | 
						|
  test_copy_assignment_sfinae();
 | 
						|
  test_copy_assignment_not_noexcept();
 | 
						|
  test_constexpr_copy_assignment();
 | 
						|
}
 |