about summary refs log blame commit diff
path: root/absl/types/optional_test.cc
blob: 179bfd66d2fee0eb9321b0559b2b9dc18910dbb3 (plain) (tree)
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483

























                                                                           










                                                  



































































































































































































































                                                                                
                                     





                                                               







                                                                            

                                                                   
      













































                                                                                
                                                              

                                                                      
                                                          


                                                                           
                                                                      

      
                                                                              























                                                                               
                                                                




                                                                                
                                                          




















































































































































































































































































































































































































































































































































































                                                                                


























                                                                                








                                                         
                                                          


















































































































































































                                                                                   
                                        

                                                      
                                        

                                                      
                                         



































































































































































































































































































































                                                                                   










                                                                               







                                        



























                                                                                






























































































                                                                                
// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "absl/types/optional.h"

#include <string>
#include <type_traits>
#include <utility>

#include "gtest/gtest.h"
#include "absl/base/config.h"
#include "absl/base/internal/raw_logging.h"
#include "absl/meta/type_traits.h"
#include "absl/strings/string_view.h"

struct Hashable {};

namespace std {
template <>
struct hash<Hashable> {
  size_t operator()(const Hashable&) { return 0; }
};
}  // namespace std

struct NonHashable {};

namespace {

std::string TypeQuals(std::string&) { return "&"; }
std::string TypeQuals(std::string&&) { return "&&"; }
std::string TypeQuals(const std::string&) { return "c&"; }
std::string TypeQuals(const std::string&&) { return "c&&"; }

struct StructorListener {
  int construct0 = 0;
  int construct1 = 0;
  int construct2 = 0;
  int listinit = 0;
  int copy = 0;
  int move = 0;
  int copy_assign = 0;
  int move_assign = 0;
  int destruct = 0;
  int volatile_copy = 0;
  int volatile_move = 0;
  int volatile_copy_assign = 0;
  int volatile_move_assign = 0;
};

// Suppress MSVC warnings.
// 4521: multiple copy constructors specified
// 4522: multiple assignment operators specified
// We wrote multiple of them to test that the correct overloads are selected.
#ifdef _MSC_VER
#pragma warning( push )
#pragma warning( disable : 4521)
#pragma warning( disable : 4522)
#endif
struct Listenable {
  static StructorListener* listener;

  Listenable() { ++listener->construct0; }
  explicit Listenable(int /*unused*/) { ++listener->construct1; }
  Listenable(int /*unused*/, int /*unused*/) { ++listener->construct2; }
  Listenable(std::initializer_list<int> /*unused*/) { ++listener->listinit; }
  Listenable(const Listenable& /*unused*/) { ++listener->copy; }
  Listenable(const volatile Listenable& /*unused*/) {
    ++listener->volatile_copy;
  }
  Listenable(volatile Listenable&& /*unused*/) { ++listener->volatile_move; }
  Listenable(Listenable&& /*unused*/) { ++listener->move; }
  Listenable& operator=(const Listenable& /*unused*/) {
    ++listener->copy_assign;
    return *this;
  }
  Listenable& operator=(Listenable&& /*unused*/) {
    ++listener->move_assign;
    return *this;
  }
  // use void return type instead of volatile T& to work around GCC warning
  // when the assignment's returned reference is ignored.
  void operator=(const volatile Listenable& /*unused*/) volatile {
    ++listener->volatile_copy_assign;
  }
  void operator=(volatile Listenable&& /*unused*/) volatile {
    ++listener->volatile_move_assign;
  }
  ~Listenable() { ++listener->destruct; }
};
#ifdef _MSC_VER
#pragma warning( pop )
#endif

StructorListener* Listenable::listener = nullptr;

// ABSL_HAVE_NO_CONSTEXPR_INITIALIZER_LIST is defined to 1 when the standard
// library implementation doesn't marked initializer_list's default constructor
// constexpr. The C++11 standard doesn't specify constexpr on it, but C++14
// added it. However, libstdc++ 4.7 marked it constexpr.
#if defined(_LIBCPP_VERSION) && \
    (_LIBCPP_STD_VER <= 11 || defined(_LIBCPP_HAS_NO_CXX14_CONSTEXPR))
#define ABSL_HAVE_NO_CONSTEXPR_INITIALIZER_LIST 1
#endif

struct ConstexprType {
  enum CtorTypes {
    kCtorDefault,
    kCtorInt,
    kCtorInitializerList,
    kCtorConstChar
  };
  constexpr ConstexprType() : x(kCtorDefault) {}
  constexpr explicit ConstexprType(int i) : x(kCtorInt) {}
#ifndef ABSL_HAVE_NO_CONSTEXPR_INITIALIZER_LIST
  constexpr ConstexprType(std::initializer_list<int> il)
      : x(kCtorInitializerList) {}
#endif
  constexpr ConstexprType(const char*)  // NOLINT(runtime/explicit)
      : x(kCtorConstChar) {}
  int x;
};

struct Copyable {
  Copyable() {}
  Copyable(const Copyable&) {}
  Copyable& operator=(const Copyable&) { return *this; }
};

struct MoveableThrow {
  MoveableThrow() {}
  MoveableThrow(MoveableThrow&&) {}
  MoveableThrow& operator=(MoveableThrow&&) { return *this; }
};

struct MoveableNoThrow {
  MoveableNoThrow() {}
  MoveableNoThrow(MoveableNoThrow&&) noexcept {}
  MoveableNoThrow& operator=(MoveableNoThrow&&) noexcept { return *this; }
};

struct NonMovable {
  NonMovable() {}
  NonMovable(const NonMovable&) = delete;
  NonMovable& operator=(const NonMovable&) = delete;
  NonMovable(NonMovable&&) = delete;
  NonMovable& operator=(NonMovable&&) = delete;
};

TEST(optionalTest, DefaultConstructor) {
  absl::optional<int> empty;
  EXPECT_FALSE(empty);
  constexpr absl::optional<int> cempty;
  static_assert(!cempty.has_value(), "");
  EXPECT_TRUE(
      std::is_nothrow_default_constructible<absl::optional<int>>::value);
}

TEST(optionalTest, nulloptConstructor) {
  absl::optional<int> empty(absl::nullopt);
  EXPECT_FALSE(empty);

#ifdef ABSL_HAVE_STD_OPTIONAL
  constexpr absl::optional<int> cempty{absl::nullopt};
#else
  // Creating a temporary absl::nullopt_t object instead of using absl::nullopt
  // because absl::nullopt cannot be constexpr and have external linkage at the
  // same time.
  constexpr absl::optional<int> cempty{absl::nullopt_t(absl::nullopt_t::init)};
#endif
  static_assert(!cempty.has_value(), "");
  EXPECT_TRUE((std::is_nothrow_constructible<absl::optional<int>,
                                             absl::nullopt_t>::value));
}

TEST(optionalTest, CopyConstructor) {
  {
    absl::optional<int> empty, opt42 = 42;
    absl::optional<int> empty_copy(empty);
    EXPECT_FALSE(empty_copy);
    absl::optional<int> opt42_copy(opt42);
    EXPECT_TRUE(opt42_copy);
    EXPECT_EQ(42, *opt42_copy);
  }
  {
    absl::optional<const int> empty, opt42 = 42;
    absl::optional<const int> empty_copy(empty);
    EXPECT_FALSE(empty_copy);
    absl::optional<const int> opt42_copy(opt42);
    EXPECT_TRUE(opt42_copy);
    EXPECT_EQ(42, *opt42_copy);
  }
  {
    absl::optional<volatile int> empty, opt42 = 42;
    absl::optional<volatile int> empty_copy(empty);
    EXPECT_FALSE(empty_copy);
    absl::optional<volatile int> opt42_copy(opt42);
    EXPECT_TRUE(opt42_copy);
    EXPECT_EQ(42, *opt42_copy);
  }
  // test copyablility
  EXPECT_TRUE(std::is_copy_constructible<absl::optional<int>>::value);
  EXPECT_TRUE(std::is_copy_constructible<absl::optional<Copyable>>::value);
  EXPECT_FALSE(
      std::is_copy_constructible<absl::optional<MoveableThrow>>::value);
  EXPECT_FALSE(
      std::is_copy_constructible<absl::optional<MoveableNoThrow>>::value);
  EXPECT_FALSE(std::is_copy_constructible<absl::optional<NonMovable>>::value);

  EXPECT_FALSE(
      absl::is_trivially_copy_constructible<absl::optional<Copyable>>::value);
#if defined(ABSL_HAVE_STD_OPTIONAL) && defined(__GLIBCXX__)
  // libstdc++ std::optional implementation (as of 7.2) has a bug: when T is
  // trivially copyable, optional<T> is not trivially copyable (due to one of
  // its base class is unconditionally nontrivial).
#define ABSL_GLIBCXX_OPTIONAL_TRIVIALITY_BUG 1
#endif
#ifndef ABSL_GLIBCXX_OPTIONAL_TRIVIALITY_BUG
  EXPECT_TRUE(
      absl::is_trivially_copy_constructible<absl::optional<int>>::value);
  EXPECT_TRUE(
      absl::is_trivially_copy_constructible<absl::optional<const int>>::value);
#ifndef _MSC_VER
  // See defect report "Trivial copy/move constructor for class with volatile
  // member" at
  // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#2094
  // A class with non-static data member of volatile-qualified type should still
  // have a trivial copy constructor if the data member is trivial.
  // Also a cv-qualified scalar type should be trivially copyable.
  EXPECT_TRUE(absl::is_trivially_copy_constructible<
              absl::optional<volatile int>>::value);
#endif  // _MSC_VER
#endif  // ABSL_GLIBCXX_OPTIONAL_TRIVIALITY_BUG

  // constexpr copy constructor for trivially copyable types
  {
    constexpr absl::optional<int> o1;
    constexpr absl::optional<int> o2 = o1;
    static_assert(!o2, "");
  }
  {
    constexpr absl::optional<int> o1 = 42;
    constexpr absl::optional<int> o2 = o1;
    static_assert(o2, "");
    static_assert(*o2 == 42, "");
  }
  {
    struct TrivialCopyable {
      constexpr TrivialCopyable() : x(0) {}
      constexpr explicit TrivialCopyable(int i) : x(i) {}
      int x;
    };
    constexpr absl::optional<TrivialCopyable> o1(42);
    constexpr absl::optional<TrivialCopyable> o2 = o1;
    static_assert(o2, "");
    static_assert((*o2).x == 42, "");
#ifndef ABSL_GLIBCXX_OPTIONAL_TRIVIALITY_BUG
    EXPECT_TRUE(absl::is_trivially_copy_constructible<
                absl::optional<TrivialCopyable>>::value);
    EXPECT_TRUE(absl::is_trivially_copy_constructible<
                absl::optional<const TrivialCopyable>>::value);
#endif
    // When testing with VS 2017 15.3, there seems to be a bug in MSVC
    // std::optional when T is volatile-qualified. So skipping this test.
    // Bug report:
    // https://connect.microsoft.com/VisualStudio/feedback/details/3142534
#if defined(ABSL_HAVE_STD_OPTIONAL) && defined(_MSC_VER) && _MSC_VER >= 1911
#define ABSL_MSVC_OPTIONAL_VOLATILE_COPY_BUG 1
#endif
#ifndef ABSL_MSVC_OPTIONAL_VOLATILE_COPY_BUG
    EXPECT_FALSE(std::is_copy_constructible<
                 absl::optional<volatile TrivialCopyable>>::value);
#endif
  }
}

TEST(optionalTest, MoveConstructor) {
  absl::optional<int> empty, opt42 = 42;
  absl::optional<int> empty_move(std::move(empty));
  EXPECT_FALSE(empty_move);
  absl::optional<int> opt42_move(std::move(opt42));
  EXPECT_TRUE(opt42_move);
  EXPECT_EQ(42, opt42_move);
  // test movability
  EXPECT_TRUE(std::is_move_constructible<absl::optional<int>>::value);
  EXPECT_TRUE(std::is_move_constructible<absl::optional<Copyable>>::value);
  EXPECT_TRUE(std::is_move_constructible<absl::optional<MoveableThrow>>::value);
  EXPECT_TRUE(
      std::is_move_constructible<absl::optional<MoveableNoThrow>>::value);
  EXPECT_FALSE(std::is_move_constructible<absl::optional<NonMovable>>::value);
  // test noexcept
  EXPECT_TRUE(std::is_nothrow_move_constructible<absl::optional<int>>::value);
#ifndef ABSL_HAVE_STD_OPTIONAL
  EXPECT_EQ(
      absl::default_allocator_is_nothrow::value,
      std::is_nothrow_move_constructible<absl::optional<MoveableThrow>>::value);
#endif
  EXPECT_TRUE(std::is_nothrow_move_constructible<
              absl::optional<MoveableNoThrow>>::value);
}

TEST(optionalTest, Destructor) {
  struct Trivial {};

  struct NonTrivial {
    NonTrivial(const NonTrivial&) {}
    NonTrivial& operator=(const NonTrivial&) { return *this; }
    ~NonTrivial() {}
  };

  EXPECT_TRUE(std::is_trivially_destructible<absl::optional<int>>::value);
  EXPECT_TRUE(std::is_trivially_destructible<absl::optional<Trivial>>::value);
  EXPECT_FALSE(
      std::is_trivially_destructible<absl::optional<NonTrivial>>::value);
}

TEST(optionalTest, InPlaceConstructor) {
  constexpr absl::optional<ConstexprType> opt0{absl::in_place_t()};
  static_assert(opt0, "");
  static_assert((*opt0).x == ConstexprType::kCtorDefault, "");
  constexpr absl::optional<ConstexprType> opt1{absl::in_place_t(), 1};
  static_assert(opt1, "");
  static_assert((*opt1).x == ConstexprType::kCtorInt, "");
#ifndef ABSL_HAVE_NO_CONSTEXPR_INITIALIZER_LIST
  constexpr absl::optional<ConstexprType> opt2{absl::in_place_t(), {1, 2}};
  static_assert(opt2, "");
  static_assert((*opt2).x == ConstexprType::kCtorInitializerList, "");
#endif

  // TODO(absl-team): uncomment these when std::is_constructible<T, Args&&...>
  // SFINAE is added to optional::optional(absl::in_place_t, Args&&...).
  // struct I {
  //   I(absl::in_place_t);
  // };

  // EXPECT_FALSE((std::is_constructible<absl::optional<I>,
  // absl::in_place_t>::value));
  // EXPECT_FALSE((std::is_constructible<absl::optional<I>, const
  // absl::in_place_t&>::value));
}

// template<U=T> optional(U&&);
TEST(optionalTest, ValueConstructor) {
  constexpr absl::optional<int> opt0(0);
  static_assert(opt0, "");
  static_assert(*opt0 == 0, "");
  EXPECT_TRUE((std::is_convertible<int, absl::optional<int>>::value));
  // Copy initialization ( = "abc") won't work due to optional(optional&&)
  // is not constexpr. Use list initialization instead. This invokes
  // absl::optional<ConstexprType>::absl::optional<U>(U&&), with U = const char
  // (&) [4], which direct-initializes the ConstexprType value held by the
  // optional via ConstexprType::ConstexprType(const char*).
  constexpr absl::optional<ConstexprType> opt1 = {"abc"};
  static_assert(opt1, "");
  static_assert(ConstexprType::kCtorConstChar == (*opt1).x, "");
  EXPECT_TRUE(
      (std::is_convertible<const char*, absl::optional<ConstexprType>>::value));
  // direct initialization
  constexpr absl::optional<ConstexprType> opt2{2};
  static_assert(opt2, "");
  static_assert(ConstexprType::kCtorInt == (*opt2).x, "");
  EXPECT_FALSE(
      (std::is_convertible<int, absl::optional<ConstexprType>>::value));

  // this invokes absl::optional<int>::optional(int&&)
  // NOTE: this has different behavior than assignment, e.g.
  // "opt3 = {};" clears the optional rather than setting the value to 0
  // According to C++17 standard N4659 [over.ics.list] 16.3.3.1.5, (9.2)- "if
  // the initializer list has no elements, the implicit conversion is the
  // identity conversion", so `optional(int&&)` should be a better match than
  // `optional(optional&&)` which is a user-defined conversion.
  // Note: GCC 7 has a bug with this overload selection when compiled with
  // `-std=c++17`.
#if defined(__GNUC__) && !defined(__clang__) && __GNUC__ == 7 && \
    __cplusplus == 201703L
#define ABSL_GCC7_OVER_ICS_LIST_BUG 1
#endif
#ifndef ABSL_GCC7_OVER_ICS_LIST_BUG
  constexpr absl::optional<int> opt3({});
  static_assert(opt3, "");
  static_assert(*opt3 == 0, "");
#endif

  // this invokes the move constructor with a default constructed optional
  // because non-template function is a better match than template function.
  absl::optional<ConstexprType> opt4({});
  EXPECT_FALSE(opt4);
}

struct Implicit {};

struct Explicit {};

struct Convert {
  Convert(const Implicit&)  // NOLINT(runtime/explicit)
      : implicit(true), move(false) {}
  Convert(Implicit&&)  // NOLINT(runtime/explicit)
      : implicit(true), move(true) {}
  explicit Convert(const Explicit&) : implicit(false), move(false) {}
  explicit Convert(Explicit&&) : implicit(false), move(true) {}

  bool implicit;
  bool move;
};

struct ConvertFromOptional {
  ConvertFromOptional(const Implicit&)  // NOLINT(runtime/explicit)
      : implicit(true), move(false), from_optional(false) {}
  ConvertFromOptional(Implicit&&)  // NOLINT(runtime/explicit)
      : implicit(true), move(true), from_optional(false) {}
  ConvertFromOptional(
      const absl::optional<Implicit>&)  // NOLINT(runtime/explicit)
      : implicit(true), move(false), from_optional(true) {}
  ConvertFromOptional(absl::optional<Implicit>&&)  // NOLINT(runtime/explicit)
      : implicit(true), move(true), from_optional(true) {}
  explicit ConvertFromOptional(const Explicit&)
      : implicit(false), move(false), from_optional(false) {}
  explicit ConvertFromOptional(Explicit&&)
      : implicit(false), move(true), from_optional(false) {}
  explicit ConvertFromOptional(const absl::optional<Explicit>&)
      : implicit(false), move(false), from_optional(true) {}
  explicit ConvertFromOptional(absl::optional<Explicit>&&)
      : implicit(false), move(true), from_optional(true) {}

  bool implicit;
  bool move;
  bool from_optional;
};

TEST(optionalTest, ConvertingConstructor) {
  absl::optional<Implicit> i_empty;
  absl::optional<Implicit> i(absl::in_place);
  absl::optional<Explicit> e_empty;
  absl::optional<Explicit> e(absl::in_place);
  {
    // implicitly constructing absl::optional<Convert> from
    // absl::optional<Implicit>
    absl::optional<Convert> empty = i_empty;
    EXPECT_FALSE(empty);
    absl::optional<Convert> opt_copy = i;
    EXPECT_TRUE(opt_copy);
    EXPECT_TRUE(opt_copy->implicit);
    EXPECT_FALSE(opt_copy->move);
    absl::optional<Convert> opt_move = absl::optional<Implicit>(absl::in_place);
    EXPECT_TRUE(opt_move);
    EXPECT_TRUE(opt_move->implicit);
    EXPECT_TRUE(opt_move->move);
  }
  {
    // explicitly constructing absl::optional<Convert> from
    // absl::optional<Explicit>
    absl::optional<Convert> empty(e_empty);
    EXPECT_FALSE(empty);
    absl::optional<Convert> opt_copy(e);
    EXPECT_TRUE(opt_copy);
    EXPECT_FALSE(opt_copy->implicit);
    EXPECT_FALSE(opt_copy->move);
    EXPECT_FALSE((std::is_convertible<const absl::optional<Explicit>&,
                                      absl::optional<Convert>>::value));
    absl::optional<Convert> opt_move{absl::optional<Explicit>(absl::in_place)};
    EXPECT_TRUE(opt_move);
    EXPECT_FALSE(opt_move->implicit);
    EXPECT_TRUE(opt_move->move);
    EXPECT_FALSE((std::is_convertible<absl::optional<Explicit>&&,
                                      absl::optional<Convert>>::value));
  }
  {
    // implicitly constructing absl::optional<ConvertFromOptional> from
    // absl::optional<Implicit> via
    // ConvertFromOptional(absl::optional<Implicit>&&) check that
    // ConvertFromOptional(Implicit&&) is NOT called
    static_assert(
        std::is_convertible<absl::optional<Implicit>,
                            absl::optional<ConvertFromOptional>>::value,
        "");
    absl::optional<ConvertFromOptional> opt0 = i_empty;
    EXPECT_TRUE(opt0);
    EXPECT_TRUE(opt0->implicit);
    EXPECT_FALSE(opt0->move);
    EXPECT_TRUE(opt0->from_optional);
    absl::optional<ConvertFromOptional> opt1 = absl::optional<Implicit>();
    EXPECT_TRUE(opt1);
    EXPECT_TRUE(opt1->implicit);
    EXPECT_TRUE(opt1->move);
    EXPECT_TRUE(opt1->from_optional);
  }
  {
    // implicitly constructing absl::optional<ConvertFromOptional> from
    // absl::optional<Explicit> via
    // ConvertFromOptional(absl::optional<Explicit>&&) check that
    // ConvertFromOptional(Explicit&&) is NOT called
    absl::optional<ConvertFromOptional> opt0(e_empty);
    EXPECT_TRUE(opt0);
    EXPECT_FALSE(opt0->implicit);
    EXPECT_FALSE(opt0->move);
    EXPECT_TRUE(opt0->from_optional);
    EXPECT_FALSE(
        (std::is_convertible<const absl::optional<Explicit>&,
                             absl::optional<ConvertFromOptional>>::value));
    absl::optional<ConvertFromOptional> opt1{absl::optional<Explicit>()};
    EXPECT_TRUE(opt1);
    EXPECT_FALSE(opt1->implicit);
    EXPECT_TRUE(opt1->move);
    EXPECT_TRUE(opt1->from_optional);
    EXPECT_FALSE(
        (std::is_convertible<absl::optional<Explicit>&&,
                             absl::optional<ConvertFromOptional>>::value));
  }
}

TEST(optionalTest, StructorBasic) {
  StructorListener listener;
  Listenable::listener = &listener;
  {
    absl::optional<Listenable> empty;
    EXPECT_FALSE(empty);
    absl::optional<Listenable> opt0(absl::in_place);
    EXPECT_TRUE(opt0);
    absl::optional<Listenable> opt1(absl::in_place, 1);
    EXPECT_TRUE(opt1);
    absl::optional<Listenable> opt2(absl::in_place, 1, 2);
    EXPECT_TRUE(opt2);
  }
  EXPECT_EQ(1, listener.construct0);
  EXPECT_EQ(1, listener.construct1);
  EXPECT_EQ(1, listener.construct2);
  EXPECT_EQ(3, listener.destruct);
}

TEST(optionalTest, CopyMoveStructor) {
  StructorListener listener;
  Listenable::listener = &listener;
  absl::optional<Listenable> original(absl::in_place);
  EXPECT_EQ(1, listener.construct0);
  EXPECT_EQ(0, listener.copy);
  EXPECT_EQ(0, listener.move);
  absl::optional<Listenable> copy(original);
  EXPECT_EQ(1, listener.construct0);
  EXPECT_EQ(1, listener.copy);
  EXPECT_EQ(0, listener.move);
  absl::optional<Listenable> move(std::move(original));
  EXPECT_EQ(1, listener.construct0);
  EXPECT_EQ(1, listener.copy);
  EXPECT_EQ(1, listener.move);
}

TEST(optionalTest, ListInit) {
  StructorListener listener;
  Listenable::listener = &listener;
  absl::optional<Listenable> listinit1(absl::in_place, {1});
  absl::optional<Listenable> listinit2(absl::in_place, {1, 2});
  EXPECT_EQ(2, listener.listinit);
}

TEST(optionalTest, AssignFromNullopt) {
  absl::optional<int> opt(1);
  opt = absl::nullopt;
  EXPECT_FALSE(opt);

  StructorListener listener;
  Listenable::listener = &listener;
  absl::optional<Listenable> opt1(absl::in_place);
  opt1 = absl::nullopt;
  EXPECT_FALSE(opt1);
  EXPECT_EQ(1, listener.construct0);
  EXPECT_EQ(1, listener.destruct);

  EXPECT_TRUE((
      std::is_nothrow_assignable<absl::optional<int>, absl::nullopt_t>::value));
  EXPECT_TRUE((std::is_nothrow_assignable<absl::optional<Listenable>,
                                          absl::nullopt_t>::value));
}

TEST(optionalTest, CopyAssignment) {
  const absl::optional<int> empty, opt1 = 1, opt2 = 2;
  absl::optional<int> empty_to_opt1, opt1_to_opt2, opt2_to_empty;

  EXPECT_FALSE(empty_to_opt1);
  empty_to_opt1 = empty;
  EXPECT_FALSE(empty_to_opt1);
  empty_to_opt1 = opt1;
  EXPECT_TRUE(empty_to_opt1);
  EXPECT_EQ(1, empty_to_opt1.value());

  EXPECT_FALSE(opt1_to_opt2);
  opt1_to_opt2 = opt1;
  EXPECT_TRUE(opt1_to_opt2);
  EXPECT_EQ(1, opt1_to_opt2.value());
  opt1_to_opt2 = opt2;
  EXPECT_TRUE(opt1_to_opt2);
  EXPECT_EQ(2, opt1_to_opt2.value());

  EXPECT_FALSE(opt2_to_empty);
  opt2_to_empty = opt2;
  EXPECT_TRUE(opt2_to_empty);
  EXPECT_EQ(2, opt2_to_empty.value());
  opt2_to_empty = empty;
  EXPECT_FALSE(opt2_to_empty);

  EXPECT_FALSE(std::is_copy_assignable<absl::optional<const int>>::value);
  EXPECT_TRUE(std::is_copy_assignable<absl::optional<Copyable>>::value);
  EXPECT_FALSE(std::is_copy_assignable<absl::optional<MoveableThrow>>::value);
  EXPECT_FALSE(std::is_copy_assignable<absl::optional<MoveableNoThrow>>::value);
  EXPECT_FALSE(std::is_copy_assignable<absl::optional<NonMovable>>::value);

  EXPECT_TRUE(absl::is_trivially_copy_assignable<int>::value);
  EXPECT_TRUE(absl::is_trivially_copy_assignable<volatile int>::value);

  struct Trivial {
    int i;
  };
  struct NonTrivial {
    NonTrivial& operator=(const NonTrivial&) { return *this; }
    int i;
  };

  EXPECT_TRUE(absl::is_trivially_copy_assignable<Trivial>::value);
  EXPECT_FALSE(std::is_copy_assignable<const Trivial>::value);
  EXPECT_FALSE(std::is_copy_assignable<volatile Trivial>::value);
  EXPECT_TRUE(std::is_copy_assignable<NonTrivial>::value);
  EXPECT_FALSE(absl::is_trivially_copy_assignable<NonTrivial>::value);

  // std::optional doesn't support volatile nontrivial types.
#ifndef ABSL_HAVE_STD_OPTIONAL
  {
    StructorListener listener;
    Listenable::listener = &listener;

    absl::optional<volatile Listenable> empty, set(absl::in_place);
    EXPECT_EQ(1, listener.construct0);
    absl::optional<volatile Listenable> empty_to_empty, empty_to_set,
        set_to_empty(absl::in_place), set_to_set(absl::in_place);
    EXPECT_EQ(3, listener.construct0);
    empty_to_empty = empty;  // no effect
    empty_to_set = set;      // copy construct
    set_to_empty = empty;    // destruct
    set_to_set = set;        // copy assign
    EXPECT_EQ(1, listener.volatile_copy);
    EXPECT_EQ(0, listener.volatile_move);
    EXPECT_EQ(1, listener.destruct);
    EXPECT_EQ(1, listener.volatile_copy_assign);
  }
#endif  // ABSL_HAVE_STD_OPTIONAL
}

TEST(optionalTest, MoveAssignment) {
  {
    StructorListener listener;
    Listenable::listener = &listener;

    absl::optional<Listenable> empty1, empty2, set1(absl::in_place),
        set2(absl::in_place);
    EXPECT_EQ(2, listener.construct0);
    absl::optional<Listenable> empty_to_empty, empty_to_set,
        set_to_empty(absl::in_place), set_to_set(absl::in_place);
    EXPECT_EQ(4, listener.construct0);
    empty_to_empty = std::move(empty1);
    empty_to_set = std::move(set1);
    set_to_empty = std::move(empty2);
    set_to_set = std::move(set2);
    EXPECT_EQ(0, listener.copy);
    EXPECT_EQ(1, listener.move);
    EXPECT_EQ(1, listener.destruct);
    EXPECT_EQ(1, listener.move_assign);
  }
  // std::optional doesn't support volatile nontrivial types.
#ifndef ABSL_HAVE_STD_OPTIONAL
  {
    StructorListener listener;
    Listenable::listener = &listener;

    absl::optional<volatile Listenable> empty1, empty2, set1(absl::in_place),
        set2(absl::in_place);
    EXPECT_EQ(2, listener.construct0);
    absl::optional<volatile Listenable> empty_to_empty, empty_to_set,
        set_to_empty(absl::in_place), set_to_set(absl::in_place);
    EXPECT_EQ(4, listener.construct0);
    empty_to_empty = std::move(empty1);  // no effect
    empty_to_set = std::move(set1);      // move construct
    set_to_empty = std::move(empty2);    // destruct
    set_to_set = std::move(set2);        // move assign
    EXPECT_EQ(0, listener.volatile_copy);
    EXPECT_EQ(1, listener.volatile_move);
    EXPECT_EQ(1, listener.destruct);
    EXPECT_EQ(1, listener.volatile_move_assign);
  }
#endif  // ABSL_HAVE_STD_OPTIONAL
  EXPECT_FALSE(std::is_move_assignable<absl::optional<const int>>::value);
  EXPECT_TRUE(std::is_move_assignable<absl::optional<Copyable>>::value);
  EXPECT_TRUE(std::is_move_assignable<absl::optional<MoveableThrow>>::value);
  EXPECT_TRUE(std::is_move_assignable<absl::optional<MoveableNoThrow>>::value);
  EXPECT_FALSE(std::is_move_assignable<absl::optional<NonMovable>>::value);

  EXPECT_FALSE(
      std::is_nothrow_move_assignable<absl::optional<MoveableThrow>>::value);
  EXPECT_TRUE(
      std::is_nothrow_move_assignable<absl::optional<MoveableNoThrow>>::value);
}

struct NoConvertToOptional {
  // disable implicit conversion from const NoConvertToOptional&
  // to absl::optional<NoConvertToOptional>.
  NoConvertToOptional(const NoConvertToOptional&) = delete;
};

struct CopyConvert {
  CopyConvert(const NoConvertToOptional&);
  CopyConvert& operator=(const CopyConvert&) = delete;
  CopyConvert& operator=(const NoConvertToOptional&);
};

struct CopyConvertFromOptional {
  CopyConvertFromOptional(const NoConvertToOptional&);
  CopyConvertFromOptional(const absl::optional<NoConvertToOptional>&);
  CopyConvertFromOptional& operator=(const CopyConvertFromOptional&) = delete;
  CopyConvertFromOptional& operator=(const NoConvertToOptional&);
  CopyConvertFromOptional& operator=(
      const absl::optional<NoConvertToOptional>&);
};

struct MoveConvert {
  MoveConvert(NoConvertToOptional&&);
  MoveConvert& operator=(const MoveConvert&) = delete;
  MoveConvert& operator=(NoConvertToOptional&&);
};

struct MoveConvertFromOptional {
  MoveConvertFromOptional(NoConvertToOptional&&);
  MoveConvertFromOptional(absl::optional<NoConvertToOptional>&&);
  MoveConvertFromOptional& operator=(const MoveConvertFromOptional&) = delete;
  MoveConvertFromOptional& operator=(NoConvertToOptional&&);
  MoveConvertFromOptional& operator=(absl::optional<NoConvertToOptional>&&);
};

// template <typename U = T> absl::optional<T>& operator=(U&& v);
TEST(optionalTest, ValueAssignment) {
  absl::optional<int> opt;
  EXPECT_FALSE(opt);
  opt = 42;
  EXPECT_TRUE(opt);
  EXPECT_EQ(42, opt.value());
  opt = absl::nullopt;
  EXPECT_FALSE(opt);
  opt = 42;
  EXPECT_TRUE(opt);
  EXPECT_EQ(42, opt.value());
  opt = 43;
  EXPECT_TRUE(opt);
  EXPECT_EQ(43, opt.value());
  opt = {};  // this should clear optional
  EXPECT_FALSE(opt);

  opt = {44};
  EXPECT_TRUE(opt);
  EXPECT_EQ(44, opt.value());

  // U = const NoConvertToOptional&
  EXPECT_TRUE((std::is_assignable<absl::optional<CopyConvert>&,
                                  const NoConvertToOptional&>::value));
  // U = const absl::optional<NoConvertToOptional>&
  EXPECT_TRUE((std::is_assignable<absl::optional<CopyConvertFromOptional>&,
                                  const NoConvertToOptional&>::value));
  // U = const NoConvertToOptional& triggers SFINAE because
  // std::is_constructible_v<MoveConvert, const NoConvertToOptional&> is false
  EXPECT_FALSE((std::is_assignable<absl::optional<MoveConvert>&,
                                   const NoConvertToOptional&>::value));
  // U = NoConvertToOptional
  EXPECT_TRUE((std::is_assignable<absl::optional<MoveConvert>&,
                                  NoConvertToOptional&&>::value));
  // U = const NoConvertToOptional& triggers SFINAE because
  // std::is_constructible_v<MoveConvertFromOptional, const
  // NoConvertToOptional&> is false
  EXPECT_FALSE((std::is_assignable<absl::optional<MoveConvertFromOptional>&,
                                   const NoConvertToOptional&>::value));
  // U = NoConvertToOptional
  EXPECT_TRUE((std::is_assignable<absl::optional<MoveConvertFromOptional>&,
                                  NoConvertToOptional&&>::value));
  // U = const absl::optional<NoConvertToOptional>&
  EXPECT_TRUE(
      (std::is_assignable<absl::optional<CopyConvertFromOptional>&,
                          const absl::optional<NoConvertToOptional>&>::value));
  // U = absl::optional<NoConvertToOptional>
  EXPECT_TRUE(
      (std::is_assignable<absl::optional<MoveConvertFromOptional>&,
                          absl::optional<NoConvertToOptional>&&>::value));
}

// template <typename U> absl::optional<T>& operator=(const absl::optional<U>&
// rhs); template <typename U> absl::optional<T>& operator=(absl::optional<U>&&
// rhs);
TEST(optionalTest, ConvertingAssignment) {
  absl::optional<int> opt_i;
  absl::optional<char> opt_c('c');
  opt_i = opt_c;
  EXPECT_TRUE(opt_i);
  EXPECT_EQ(*opt_c, *opt_i);
  opt_i = absl::optional<char>();
  EXPECT_FALSE(opt_i);
  opt_i = absl::optional<char>('d');
  EXPECT_TRUE(opt_i);
  EXPECT_EQ('d', *opt_i);

  absl::optional<std::string> opt_str;
  absl::optional<const char*> opt_cstr("abc");
  opt_str = opt_cstr;
  EXPECT_TRUE(opt_str);
  EXPECT_EQ(std::string("abc"), *opt_str);
  opt_str = absl::optional<const char*>();
  EXPECT_FALSE(opt_str);
  opt_str = absl::optional<const char*>("def");
  EXPECT_TRUE(opt_str);
  EXPECT_EQ(std::string("def"), *opt_str);

  // operator=(const absl::optional<U>&) with U = NoConvertToOptional
  EXPECT_TRUE(
      (std::is_assignable<absl::optional<CopyConvert>,
                          const absl::optional<NoConvertToOptional>&>::value));
  // operator=(const absl::optional<U>&) with U = NoConvertToOptional
  // triggers SFINAE because
  // std::is_constructible_v<MoveConvert, const NoConvertToOptional&> is false
  EXPECT_FALSE(
      (std::is_assignable<absl::optional<MoveConvert>&,
                          const absl::optional<NoConvertToOptional>&>::value));
  // operator=(absl::optional<U>&&) with U = NoConvertToOptional
  EXPECT_TRUE(
      (std::is_assignable<absl::optional<MoveConvert>&,
                          absl::optional<NoConvertToOptional>&&>::value));
  // operator=(const absl::optional<U>&) with U = NoConvertToOptional triggers
  // SFINAE because std::is_constructible_v<MoveConvertFromOptional, const
  // NoConvertToOptional&> is false. operator=(U&&) with U = const
  // absl::optional<NoConverToOptional>& triggers SFINAE because
  // std::is_constructible<MoveConvertFromOptional,
  // absl::optional<NoConvertToOptional>&&> is true.
  EXPECT_FALSE(
      (std::is_assignable<absl::optional<MoveConvertFromOptional>&,
                          const absl::optional<NoConvertToOptional>&>::value));
}

TEST(optionalTest, ResetAndHasValue) {
  StructorListener listener;
  Listenable::listener = &listener;
  absl::optional<Listenable> opt;
  EXPECT_FALSE(opt);
  EXPECT_FALSE(opt.has_value());
  opt.emplace();
  EXPECT_TRUE(opt);
  EXPECT_TRUE(opt.has_value());
  opt.reset();
  EXPECT_FALSE(opt);
  EXPECT_FALSE(opt.has_value());
  EXPECT_EQ(1, listener.destruct);
  opt.reset();
  EXPECT_FALSE(opt);
  EXPECT_FALSE(opt.has_value());

  constexpr absl::optional<int> empty;
  static_assert(!empty.has_value(), "");
  constexpr absl::optional<int> nonempty(1);
  static_assert(nonempty.has_value(), "");
}

TEST(optionalTest, Emplace) {
  StructorListener listener;
  Listenable::listener = &listener;
  absl::optional<Listenable> opt;
  EXPECT_FALSE(opt);
  opt.emplace(1);
  EXPECT_TRUE(opt);
  opt.emplace(1, 2);
  EXPECT_EQ(1, listener.construct1);
  EXPECT_EQ(1, listener.construct2);
  EXPECT_EQ(1, listener.destruct);

  absl::optional<std::string> o;
  EXPECT_TRUE((std::is_same<std::string&, decltype(o.emplace("abc"))>::value));
  std::string& ref = o.emplace("abc");
  EXPECT_EQ(&ref, &o.value());
}

TEST(optionalTest, ListEmplace) {
  StructorListener listener;
  Listenable::listener = &listener;
  absl::optional<Listenable> opt;
  EXPECT_FALSE(opt);
  opt.emplace({1});
  EXPECT_TRUE(opt);
  opt.emplace({1, 2});
  EXPECT_EQ(2, listener.listinit);
  EXPECT_EQ(1, listener.destruct);

  absl::optional<Listenable> o;
  EXPECT_TRUE((std::is_same<Listenable&, decltype(o.emplace({1}))>::value));
  Listenable& ref = o.emplace({1});
  EXPECT_EQ(&ref, &o.value());
}

TEST(optionalTest, Swap) {
  absl::optional<int> opt_empty, opt1 = 1, opt2 = 2;
  EXPECT_FALSE(opt_empty);
  EXPECT_TRUE(opt1);
  EXPECT_EQ(1, opt1.value());
  EXPECT_TRUE(opt2);
  EXPECT_EQ(2, opt2.value());
  swap(opt_empty, opt1);
  EXPECT_FALSE(opt1);
  EXPECT_TRUE(opt_empty);
  EXPECT_EQ(1, opt_empty.value());
  EXPECT_TRUE(opt2);
  EXPECT_EQ(2, opt2.value());
  swap(opt_empty, opt1);
  EXPECT_FALSE(opt_empty);
  EXPECT_TRUE(opt1);
  EXPECT_EQ(1, opt1.value());
  EXPECT_TRUE(opt2);
  EXPECT_EQ(2, opt2.value());
  swap(opt1, opt2);
  EXPECT_FALSE(opt_empty);
  EXPECT_TRUE(opt1);
  EXPECT_EQ(2, opt1.value());
  EXPECT_TRUE(opt2);
  EXPECT_EQ(1, opt2.value());

  EXPECT_TRUE(noexcept(opt1.swap(opt2)));
  EXPECT_TRUE(noexcept(swap(opt1, opt2)));
}

template <int v>
struct DeletedOpAddr {
  constexpr static const int value = v;
  constexpr DeletedOpAddr() = default;
  constexpr const DeletedOpAddr<v>* operator&() const = delete;  // NOLINT
  DeletedOpAddr<v>* operator&() = delete;                        // NOLINT
};

// The static_assert featuring a constexpr call to operator->() is commented out
// to document the fact that the current implementation of absl::optional<T>
// expects such usecases to be malformed and not compile.
TEST(optionalTest, OperatorAddr) {
  constexpr const int v = -1;
  {  // constexpr
    constexpr const absl::optional<DeletedOpAddr<v>> opt(absl::in_place_t{});
    static_assert(opt.has_value(), "");
    // static_assert(opt->value == v, "");
    static_assert((*opt).value == v, "");
  }
  {  // non-constexpr
    const absl::optional<DeletedOpAddr<v>> opt(absl::in_place_t{});
    EXPECT_TRUE(opt.has_value());
    EXPECT_TRUE(opt->value == v);
    EXPECT_TRUE((*opt).value == v);
  }
}

TEST(optionalTest, PointerStuff) {
  absl::optional<std::string> opt(absl::in_place, "foo");
  EXPECT_EQ("foo", *opt);
  const auto& opt_const = opt;
  EXPECT_EQ("foo", *opt_const);
  EXPECT_EQ(opt->size(), 3);
  EXPECT_EQ(opt_const->size(), 3);

  constexpr absl::optional<ConstexprType> opt1(1);
  static_assert((*opt1).x == ConstexprType::kCtorInt, "");
}

// gcc has a bug pre 4.9.1 where it doesn't do correct overload resolution
// when overloads are const-qualified and *this is an raluve.
// Skip that test to make the build green again when using the old compiler.
// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59296 is fixed in 4.9.1.
#if defined(__GNUC__) && !defined(__clang__)
#define GCC_VERSION (__GNUC__ * 10000 \
                     + __GNUC_MINOR__ * 100 \
                     + __GNUC_PATCHLEVEL__)
#if GCC_VERSION < 40901
#define ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG
#endif
#endif

// MSVC has a bug with "cv-qualifiers in class construction", fixed in 2017. See
// https://docs.microsoft.com/en-us/cpp/cpp-conformance-improvements-2017#bug-fixes
// The compiler some incorrectly ingores the cv-qualifier when generating a
// class object via a constructor call. For example:
//
// class optional {
//   constexpr T&& value() &&;
//   constexpr const T&& value() const &&;
// }
//
// using COI = const absl::optional<int>;
// static_assert(2 == COI(2).value(), "");  // const &&
//
// This should invoke the "const &&" overload but since it ignores the const
// qualifier it finds the "&&" overload the best candidate.
#if defined(_MSC_VER) && _MSC_VER < 1910
#define ABSL_SKIP_OVERLOAD_TEST_DUE_TO_MSVC_BUG
#endif

TEST(optionalTest, Value) {
  using O = absl::optional<std::string>;
  using CO = const absl::optional<std::string>;
  using OC = absl::optional<const std::string>;
  O lvalue(absl::in_place, "lvalue");
  CO clvalue(absl::in_place, "clvalue");
  OC lvalue_c(absl::in_place, "lvalue_c");
  EXPECT_EQ("lvalue", lvalue.value());
  EXPECT_EQ("clvalue", clvalue.value());
  EXPECT_EQ("lvalue_c", lvalue_c.value());
  EXPECT_EQ("xvalue", O(absl::in_place, "xvalue").value());
  EXPECT_EQ("xvalue_c", OC(absl::in_place, "xvalue_c").value());
#ifndef ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG
  EXPECT_EQ("cxvalue", CO(absl::in_place, "cxvalue").value());
#endif
  EXPECT_EQ("&", TypeQuals(lvalue.value()));
  EXPECT_EQ("c&", TypeQuals(clvalue.value()));
  EXPECT_EQ("c&", TypeQuals(lvalue_c.value()));
  EXPECT_EQ("&&", TypeQuals(O(absl::in_place, "xvalue").value()));
#if !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_MSVC_BUG) && \
    !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG)
  EXPECT_EQ("c&&", TypeQuals(CO(absl::in_place, "cxvalue").value()));
#endif
  EXPECT_EQ("c&&", TypeQuals(OC(absl::in_place, "xvalue_c").value()));

  // test on volatile type
  using OV = absl::optional<volatile int>;
  OV lvalue_v(absl::in_place, 42);
  EXPECT_EQ(42, lvalue_v.value());
  EXPECT_EQ(42, OV(42).value());
  EXPECT_TRUE((std::is_same<volatile int&, decltype(lvalue_v.value())>::value));
  EXPECT_TRUE((std::is_same<volatile int&&, decltype(OV(42).value())>::value));

  // test exception throw on value()
  absl::optional<int> empty;
#ifdef ABSL_HAVE_EXCEPTIONS
  EXPECT_THROW(empty.value(), absl::bad_optional_access);
#else
  EXPECT_DEATH(empty.value(), "Bad optional access");
#endif

  // test constexpr value()
  constexpr absl::optional<int> o1(1);
  static_assert(1 == o1.value(), "");  // const &
#if !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_MSVC_BUG) && \
    !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG)
  using COI = const absl::optional<int>;
  static_assert(2 == COI(2).value(), "");  // const &&
#endif
}

TEST(optionalTest, DerefOperator) {
  using O = absl::optional<std::string>;
  using CO = const absl::optional<std::string>;
  using OC = absl::optional<const std::string>;
  O lvalue(absl::in_place, "lvalue");
  CO clvalue(absl::in_place, "clvalue");
  OC lvalue_c(absl::in_place, "lvalue_c");
  EXPECT_EQ("lvalue", *lvalue);
  EXPECT_EQ("clvalue", *clvalue);
  EXPECT_EQ("lvalue_c", *lvalue_c);
  EXPECT_EQ("xvalue", *O(absl::in_place, "xvalue"));
  EXPECT_EQ("xvalue_c", *OC(absl::in_place, "xvalue_c"));
#ifndef ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG
  EXPECT_EQ("cxvalue", *CO(absl::in_place, "cxvalue"));
#endif
  EXPECT_EQ("&", TypeQuals(*lvalue));
  EXPECT_EQ("c&", TypeQuals(*clvalue));
  EXPECT_EQ("&&", TypeQuals(*O(absl::in_place, "xvalue")));
#if !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_MSVC_BUG) && \
    !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG)
  EXPECT_EQ("c&&", TypeQuals(*CO(absl::in_place, "cxvalue")));
#endif
  EXPECT_EQ("c&&", TypeQuals(*OC(absl::in_place, "xvalue_c")));

  // test on volatile type
  using OV = absl::optional<volatile int>;
  OV lvalue_v(absl::in_place, 42);
  EXPECT_EQ(42, *lvalue_v);
  EXPECT_EQ(42, *OV(42));
  EXPECT_TRUE((std::is_same<volatile int&, decltype(*lvalue_v)>::value));
  EXPECT_TRUE((std::is_same<volatile int&&, decltype(*OV(42))>::value));

  constexpr absl::optional<int> opt1(1);
  static_assert(*opt1 == 1, "");
#if !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_MSVC_BUG) && \
    !defined(ABSL_SKIP_OVERLOAD_TEST_DUE_TO_GCC_BUG)
  using COI = const absl::optional<int>;
  static_assert(*COI(2) == 2, "");
#endif
}

TEST(optionalTest, ValueOr) {
  absl::optional<double> opt_empty, opt_set = 1.2;
  EXPECT_EQ(42.0, opt_empty.value_or(42));
  EXPECT_EQ(1.2, opt_set.value_or(42));
  EXPECT_EQ(42.0, absl::optional<double>().value_or(42));
  EXPECT_EQ(1.2, absl::optional<double>(1.2).value_or(42));

  constexpr absl::optional<double> copt_empty, copt_set = {1.2};
  static_assert(42.0 == copt_empty.value_or(42), "");
  static_assert(1.2 == copt_set.value_or(42), "");
#ifndef ABSL_SKIP_OVERLOAD_TEST_DUE_TO_MSVC_BUG
  using COD = const absl::optional<double>;
  static_assert(42.0 == COD().value_or(42), "");
  static_assert(1.2 == COD(1.2).value_or(42), "");
#endif
}

// make_optional cannot be constexpr until C++17
TEST(optionalTest, make_optional) {
  auto opt_int = absl::make_optional(42);
  EXPECT_TRUE((std::is_same<decltype(opt_int), absl::optional<int>>::value));
  EXPECT_EQ(42, opt_int);

  StructorListener listener;
  Listenable::listener = &listener;

  absl::optional<Listenable> opt0 = absl::make_optional<Listenable>();
  EXPECT_EQ(1, listener.construct0);
  absl::optional<Listenable> opt1 = absl::make_optional<Listenable>(1);
  EXPECT_EQ(1, listener.construct1);
  absl::optional<Listenable> opt2 = absl::make_optional<Listenable>(1, 2);
  EXPECT_EQ(1, listener.construct2);
  absl::optional<Listenable> opt3 = absl::make_optional<Listenable>({1});
  absl::optional<Listenable> opt4 = absl::make_optional<Listenable>({1, 2});
  EXPECT_EQ(2, listener.listinit);

  // Constexpr tests on trivially copyable types
  // optional<T> has trivial copy/move ctors when T is trivially copyable.
  // For nontrivial types with constexpr constructors, we need copy elision in
  // C++17 for make_optional to be constexpr.
  {
    constexpr absl::optional<int> c_opt = absl::make_optional(42);
    static_assert(c_opt.value() == 42, "");
  }
  {
    struct TrivialCopyable {
      constexpr TrivialCopyable() : x(0) {}
      constexpr explicit TrivialCopyable(int i) : x(i) {}
      int x;
    };

    constexpr TrivialCopyable v;
    constexpr absl::optional<TrivialCopyable> c_opt0 = absl::make_optional(v);
    static_assert((*c_opt0).x == 0, "");
    constexpr absl::optional<TrivialCopyable> c_opt1 =
        absl::make_optional<TrivialCopyable>();
    static_assert((*c_opt1).x == 0, "");
    constexpr absl::optional<TrivialCopyable> c_opt2 =
        absl::make_optional<TrivialCopyable>(42);
    static_assert((*c_opt2).x == 42, "");
  }
}

template <typename T, typename U>
void optionalTest_Comparisons_EXPECT_LESS(T x, U y) {
  EXPECT_FALSE(x == y);
  EXPECT_TRUE(x != y);
  EXPECT_TRUE(x < y);
  EXPECT_FALSE(x > y);
  EXPECT_TRUE(x <= y);
  EXPECT_FALSE(x >= y);
}

template <typename T, typename U>
void optionalTest_Comparisons_EXPECT_SAME(T x, U y) {
  EXPECT_TRUE(x == y);
  EXPECT_FALSE(x != y);
  EXPECT_FALSE(x < y);
  EXPECT_FALSE(x > y);
  EXPECT_TRUE(x <= y);
  EXPECT_TRUE(x >= y);
}

template <typename T, typename U>
void optionalTest_Comparisons_EXPECT_GREATER(T x, U y) {
  EXPECT_FALSE(x == y);
  EXPECT_TRUE(x != y);
  EXPECT_FALSE(x < y);
  EXPECT_TRUE(x > y);
  EXPECT_FALSE(x <= y);
  EXPECT_TRUE(x >= y);
}


template <typename T, typename U, typename V>
void TestComparisons() {
  absl::optional<T> ae, a2{2}, a4{4};
  absl::optional<U> be, b2{2}, b4{4};
  V v3 = 3;

  // LHS: absl::nullopt, ae, a2, v3, a4
  // RHS: absl::nullopt, be, b2, v3, b4

  // optionalTest_Comparisons_EXPECT_NOT_TO_WORK(absl::nullopt,absl::nullopt);
  optionalTest_Comparisons_EXPECT_SAME(absl::nullopt, be);
  optionalTest_Comparisons_EXPECT_LESS(absl::nullopt, b2);
  // optionalTest_Comparisons_EXPECT_NOT_TO_WORK(absl::nullopt,v3);
  optionalTest_Comparisons_EXPECT_LESS(absl::nullopt, b4);

  optionalTest_Comparisons_EXPECT_SAME(ae, absl::nullopt);
  optionalTest_Comparisons_EXPECT_SAME(ae, be);
  optionalTest_Comparisons_EXPECT_LESS(ae, b2);
  optionalTest_Comparisons_EXPECT_LESS(ae, v3);
  optionalTest_Comparisons_EXPECT_LESS(ae, b4);

  optionalTest_Comparisons_EXPECT_GREATER(a2, absl::nullopt);
  optionalTest_Comparisons_EXPECT_GREATER(a2, be);
  optionalTest_Comparisons_EXPECT_SAME(a2, b2);
  optionalTest_Comparisons_EXPECT_LESS(a2, v3);
  optionalTest_Comparisons_EXPECT_LESS(a2, b4);

  // optionalTest_Comparisons_EXPECT_NOT_TO_WORK(v3,absl::nullopt);
  optionalTest_Comparisons_EXPECT_GREATER(v3, be);
  optionalTest_Comparisons_EXPECT_GREATER(v3, b2);
  optionalTest_Comparisons_EXPECT_SAME(v3, v3);
  optionalTest_Comparisons_EXPECT_LESS(v3, b4);

  optionalTest_Comparisons_EXPECT_GREATER(a4, absl::nullopt);
  optionalTest_Comparisons_EXPECT_GREATER(a4, be);
  optionalTest_Comparisons_EXPECT_GREATER(a4, b2);
  optionalTest_Comparisons_EXPECT_GREATER(a4, v3);
  optionalTest_Comparisons_EXPECT_SAME(a4, b4);
}

struct Int1 {
  Int1() = default;
  Int1(int i) : i(i) {}  // NOLINT(runtime/explicit)
  int i;
};

struct Int2 {
  Int2() = default;
  Int2(int i) : i(i) {}  // NOLINT(runtime/explicit)
  int i;
};

// comparison between Int1 and Int2
constexpr bool operator==(const Int1& lhs, const Int2& rhs) {
  return lhs.i == rhs.i;
}
constexpr bool operator!=(const Int1& lhs, const Int2& rhs) {
  return !(lhs == rhs);
}
constexpr bool operator<(const Int1& lhs, const Int2& rhs) {
  return lhs.i < rhs.i;
}
constexpr bool operator<=(const Int1& lhs, const Int2& rhs) {
  return lhs < rhs || lhs == rhs;
}
constexpr bool operator>(const Int1& lhs, const Int2& rhs) {
  return !(lhs <= rhs);
}
constexpr bool operator>=(const Int1& lhs, const Int2& rhs) {
  return !(lhs < rhs);
}

TEST(optionalTest, Comparisons) {
  TestComparisons<int, int, int>();
  TestComparisons<const int, int, int>();
  TestComparisons<Int1, int, int>();
  TestComparisons<int, Int2, int>();
  TestComparisons<Int1, Int2, int>();

  // compare absl::optional<std::string> with const char*
  absl::optional<std::string> opt_str = "abc";
  const char* cstr = "abc";
  EXPECT_TRUE(opt_str == cstr);
  // compare absl::optional<std::string> with absl::optional<const char*>
  absl::optional<const char*> opt_cstr = cstr;
  EXPECT_TRUE(opt_str == opt_cstr);
  // compare absl::optional<std::string> with absl::optional<absl::string_view>
  absl::optional<absl::string_view> e1;
  absl::optional<std::string> e2;
  EXPECT_TRUE(e1 == e2);
}


TEST(optionalTest, SwapRegression) {
  StructorListener listener;
  Listenable::listener = &listener;

  {
    absl::optional<Listenable> a;
    absl::optional<Listenable> b(absl::in_place);
    a.swap(b);
  }

  EXPECT_EQ(1, listener.construct0);
  EXPECT_EQ(1, listener.move);
  EXPECT_EQ(2, listener.destruct);

  {
    absl::optional<Listenable> a(absl::in_place);
    absl::optional<Listenable> b;
    a.swap(b);
  }

  EXPECT_EQ(2, listener.construct0);
  EXPECT_EQ(2, listener.move);
  EXPECT_EQ(4, listener.destruct);
}

TEST(optionalTest, BigStringLeakCheck) {
  constexpr size_t n = 1 << 16;

  using OS = absl::optional<std::string>;

  OS a;
  OS b = absl::nullopt;
  OS c = std::string(n, 'c');
  std::string sd(n, 'd');
  OS d = sd;
  OS e(absl::in_place, n, 'e');
  OS f;
  f.emplace(n, 'f');

  OS ca(a);
  OS cb(b);
  OS cc(c);
  OS cd(d);
  OS ce(e);

  OS oa;
  OS ob = absl::nullopt;
  OS oc = std::string(n, 'c');
  std::string sod(n, 'd');
  OS od = sod;
  OS oe(absl::in_place, n, 'e');
  OS of;
  of.emplace(n, 'f');

  OS ma(std::move(oa));
  OS mb(std::move(ob));
  OS mc(std::move(oc));
  OS md(std::move(od));
  OS me(std::move(oe));
  OS mf(std::move(of));

  OS aa1;
  OS ab1 = absl::nullopt;
  OS ac1 = std::string(n, 'c');
  std::string sad1(n, 'd');
  OS ad1 = sad1;
  OS ae1(absl::in_place, n, 'e');
  OS af1;
  af1.emplace(n, 'f');

  OS aa2;
  OS ab2 = absl::nullopt;
  OS ac2 = std::string(n, 'c');
  std::string sad2(n, 'd');
  OS ad2 = sad2;
  OS ae2(absl::in_place, n, 'e');
  OS af2;
  af2.emplace(n, 'f');

  aa1 = af2;
  ab1 = ae2;
  ac1 = ad2;
  ad1 = ac2;
  ae1 = ab2;
  af1 = aa2;

  OS aa3;
  OS ab3 = absl::nullopt;
  OS ac3 = std::string(n, 'c');
  std::string sad3(n, 'd');
  OS ad3 = sad3;
  OS ae3(absl::in_place, n, 'e');
  OS af3;
  af3.emplace(n, 'f');

  aa3 = absl::nullopt;
  ab3 = absl::nullopt;
  ac3 = absl::nullopt;
  ad3 = absl::nullopt;
  ae3 = absl::nullopt;
  af3 = absl::nullopt;

  OS aa4;
  OS ab4 = absl::nullopt;
  OS ac4 = std::string(n, 'c');
  std::string sad4(n, 'd');
  OS ad4 = sad4;
  OS ae4(absl::in_place, n, 'e');
  OS af4;
  af4.emplace(n, 'f');

  aa4 = OS(absl::in_place, n, 'a');
  ab4 = OS(absl::in_place, n, 'b');
  ac4 = OS(absl::in_place, n, 'c');
  ad4 = OS(absl::in_place, n, 'd');
  ae4 = OS(absl::in_place, n, 'e');
  af4 = OS(absl::in_place, n, 'f');

  OS aa5;
  OS ab5 = absl::nullopt;
  OS ac5 = std::string(n, 'c');
  std::string sad5(n, 'd');
  OS ad5 = sad5;
  OS ae5(absl::in_place, n, 'e');
  OS af5;
  af5.emplace(n, 'f');

  std::string saa5(n, 'a');
  std::string sab5(n, 'a');
  std::string sac5(n, 'a');
  std::string sad52(n, 'a');
  std::string sae5(n, 'a');
  std::string saf5(n, 'a');

  aa5 = saa5;
  ab5 = sab5;
  ac5 = sac5;
  ad5 = sad52;
  ae5 = sae5;
  af5 = saf5;

  OS aa6;
  OS ab6 = absl::nullopt;
  OS ac6 = std::string(n, 'c');
  std::string sad6(n, 'd');
  OS ad6 = sad6;
  OS ae6(absl::in_place, n, 'e');
  OS af6;
  af6.emplace(n, 'f');

  aa6 = std::string(n, 'a');
  ab6 = std::string(n, 'b');
  ac6 = std::string(n, 'c');
  ad6 = std::string(n, 'd');
  ae6 = std::string(n, 'e');
  af6 = std::string(n, 'f');

  OS aa7;
  OS ab7 = absl::nullopt;
  OS ac7 = std::string(n, 'c');
  std::string sad7(n, 'd');
  OS ad7 = sad7;
  OS ae7(absl::in_place, n, 'e');
  OS af7;
  af7.emplace(n, 'f');

  aa7.emplace(n, 'A');
  ab7.emplace(n, 'B');
  ac7.emplace(n, 'C');
  ad7.emplace(n, 'D');
  ae7.emplace(n, 'E');
  af7.emplace(n, 'F');
}

TEST(optionalTest, MoveAssignRegression) {
  StructorListener listener;
  Listenable::listener = &listener;

  {
    absl::optional<Listenable> a;
    Listenable b;
    a = std::move(b);
  }

  EXPECT_EQ(1, listener.construct0);
  EXPECT_EQ(1, listener.move);
  EXPECT_EQ(2, listener.destruct);
}

TEST(optionalTest, ValueType) {
  EXPECT_TRUE((std::is_same<absl::optional<int>::value_type, int>::value));
  EXPECT_TRUE(
      (std::is_same<absl::optional<std::string>::value_type, std::string>::value));
  EXPECT_FALSE(
      (std::is_same<absl::optional<int>::value_type, absl::nullopt_t>::value));
}

template <typename T>
struct is_hash_enabled_for {
  template <typename U, typename = decltype(std::hash<U>()(std::declval<U>()))>
  static std::true_type test(int);

  template <typename U>
  static std::false_type test(...);

  static constexpr bool value = decltype(test<T>(0))::value;
};

TEST(optionalTest, Hash) {
  std::hash<absl::optional<int>> hash;
  std::set<size_t> hashcodes;
  hashcodes.insert(hash(absl::nullopt));
  for (int i = 0; i < 100; ++i) {
    hashcodes.insert(hash(i));
  }
  EXPECT_GT(hashcodes.size(), 90);

  static_assert(is_hash_enabled_for<absl::optional<int>>::value, "");
  static_assert(is_hash_enabled_for<absl::optional<Hashable>>::value, "");

#if defined(_MSC_VER) || (defined(_LIBCPP_VERSION) && \
                          _LIBCPP_VERSION < 4000 && _LIBCPP_STD_VER > 11)
  // For MSVC and libc++ (< 4.0 and c++14), std::hash primary template has a
  // static_assert to catch any user-defined type that doesn't provide a hash
  // specialization. So instantiating std::hash<absl::optional<T>> will result
  // in a hard error which is not SFINAE friendly.
#define ABSL_STD_HASH_NOT_SFINAE_FRIENDLY 1
#endif

#ifndef ABSL_STD_HASH_NOT_SFINAE_FRIENDLY
  static_assert(!is_hash_enabled_for<absl::optional<NonHashable>>::value, "");
#endif

  // libstdc++ std::optional is missing remove_const_t, i.e. it's using
  // std::hash<T> rather than std::hash<std::remove_const_t<T>>.
  // Reference: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82262
#ifndef __GLIBCXX__
  static_assert(is_hash_enabled_for<absl::optional<const int>>::value, "");
  static_assert(is_hash_enabled_for<absl::optional<const Hashable>>::value, "");
  std::hash<absl::optional<const int>> c_hash;
  for (int i = 0; i < 100; ++i) {
    EXPECT_EQ(hash(i), c_hash(i));
  }
#endif
}

struct MoveMeNoThrow {
  MoveMeNoThrow() : x(0) {}
  [[noreturn]] MoveMeNoThrow(const MoveMeNoThrow& other) : x(other.x) {
    ABSL_RAW_LOG(FATAL, "Should not be called.");
    abort();
  }
  MoveMeNoThrow(MoveMeNoThrow&& other) noexcept : x(other.x) {}
  int x;
};

struct MoveMeThrow {
  MoveMeThrow() : x(0) {}
  MoveMeThrow(const MoveMeThrow& other) : x(other.x) {}
  MoveMeThrow(MoveMeThrow&& other) : x(other.x) {}
  int x;
};

TEST(optionalTest, NoExcept) {
  static_assert(
      std::is_nothrow_move_constructible<absl::optional<MoveMeNoThrow>>::value,
      "");
#ifndef ABSL_HAVE_STD_OPTIONAL
  static_assert(absl::default_allocator_is_nothrow::value ==
                    std::is_nothrow_move_constructible<
                        absl::optional<MoveMeThrow>>::value,
                "");
#endif
  std::vector<absl::optional<MoveMeNoThrow>> v;
  for (int i = 0; i < 10; ++i) v.emplace_back();
}

struct AnyLike {
  AnyLike(AnyLike&&) = default;
  AnyLike(const AnyLike&) = default;

  template <typename ValueType,
            typename T = typename std::decay<ValueType>::type,
            typename std::enable_if<
                !absl::disjunction<
                    std::is_same<AnyLike, T>,
                    absl::negation<std::is_copy_constructible<T>>>::value,
                int>::type = 0>
  AnyLike(ValueType&&) {}  // NOLINT(runtime/explicit)

  AnyLike& operator=(AnyLike&&) = default;
  AnyLike& operator=(const AnyLike&) = default;

  template <typename ValueType,
            typename T = typename std::decay<ValueType>::type>
  typename std::enable_if<
      absl::conjunction<absl::negation<std::is_same<AnyLike, T>>,
                        std::is_copy_constructible<T>>::value,
      AnyLike&>::type
  operator=(ValueType&& /* rhs */) {
    return *this;
  }
};

TEST(optionalTest, ConstructionConstraints) {
  EXPECT_TRUE((std::is_constructible<AnyLike, absl::optional<AnyLike>>::value));

  EXPECT_TRUE(
      (std::is_constructible<AnyLike, const absl::optional<AnyLike>&>::value));

  EXPECT_TRUE((std::is_constructible<absl::optional<AnyLike>, AnyLike>::value));
  EXPECT_TRUE(
      (std::is_constructible<absl::optional<AnyLike>, const AnyLike&>::value));

  EXPECT_TRUE((std::is_convertible<absl::optional<AnyLike>, AnyLike>::value));

  EXPECT_TRUE(
      (std::is_convertible<const absl::optional<AnyLike>&, AnyLike>::value));

  EXPECT_TRUE((std::is_convertible<AnyLike, absl::optional<AnyLike>>::value));
  EXPECT_TRUE(
      (std::is_convertible<const AnyLike&, absl::optional<AnyLike>>::value));

  EXPECT_TRUE(std::is_move_constructible<absl::optional<AnyLike>>::value);
  EXPECT_TRUE(std::is_copy_constructible<absl::optional<AnyLike>>::value);
}

TEST(optionalTest, AssignmentConstraints) {
  EXPECT_TRUE((std::is_assignable<AnyLike&, absl::optional<AnyLike>>::value));
  EXPECT_TRUE(
      (std::is_assignable<AnyLike&, const absl::optional<AnyLike>&>::value));
  EXPECT_TRUE((std::is_assignable<absl::optional<AnyLike>&, AnyLike>::value));
  EXPECT_TRUE(
      (std::is_assignable<absl::optional<AnyLike>&, const AnyLike&>::value));
  EXPECT_TRUE(std::is_move_assignable<absl::optional<AnyLike>>::value);
  EXPECT_TRUE(std::is_copy_assignable<absl::optional<AnyLike>>::value);
}

}  // namespace