coroutines.cpp 49.7 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 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
// This file contains references to sections of the Coroutines TS, which can be
// found at http://wg21.link/coroutines.

// RUN: %clang_cc1 -std=c++14 -fcoroutines-ts -verify %s -fcxx-exceptions -fexceptions -Wunused-result

void no_coroutine_traits_bad_arg_await() {
  co_await a; // expected-error {{include <experimental/coroutine>}}
  // expected-error@-1 {{use of undeclared identifier 'a'}}
}

void no_coroutine_traits_bad_arg_yield() {
  co_yield a; // expected-error {{include <experimental/coroutine>}}
  // expected-error@-1 {{use of undeclared identifier 'a'}}
}


void no_coroutine_traits_bad_arg_return() {
  co_return a; // expected-error {{include <experimental/coroutine>}}
  // expected-error@-1 {{use of undeclared identifier 'a'}}
}

void no_coroutine_traits() {
  co_await 4; // expected-error {{std::experimental::coroutine_traits type was not found; include <experimental/coroutine>}}
}

namespace std {
namespace experimental {

template <class... Args>
struct void_t_imp {
  using type = void;
};
template <class... Args>
using void_t = typename void_t_imp<Args...>::type;

template <class T, class = void>
struct traits_sfinae_base {};

template <class T>
struct traits_sfinae_base<T, void_t<typename T::promise_type>> {
  using promise_type = typename T::promise_type;
};

template <class Ret, class... Args>
struct coroutine_traits : public traits_sfinae_base<Ret> {};
}}  // namespace std::experimental

template<typename Promise> struct coro {};
template <typename Promise, typename... Ps>
struct std::experimental::coroutine_traits<coro<Promise>, Ps...> {
  using promise_type = Promise;
};

struct awaitable {
  bool await_ready();
  template <typename F> void await_suspend(F);
  void await_resume();
} a;

struct suspend_always {
  bool await_ready() { return false; }
  template <typename F> void await_suspend(F);
  void await_resume() {}
};

struct suspend_never {
  bool await_ready() { return true; }
  template <typename F> void await_suspend(F);
  void await_resume() {}
};

struct auto_await_suspend {
  bool await_ready();
  template <typename F> auto await_suspend(F) {}
  void await_resume();
};

struct DummyVoidTag {};
DummyVoidTag no_specialization() { // expected-error {{this function cannot be a coroutine: 'std::experimental::coroutine_traits<DummyVoidTag>' has no member named 'promise_type'}}
  co_await a;
}

template <typename... T>
struct std::experimental::coroutine_traits<int, T...> {};

int no_promise_type() { // expected-error {{this function cannot be a coroutine: 'std::experimental::coroutine_traits<int>' has no member named 'promise_type'}}
  co_await a;
}

int no_promise_type_multiple_awaits(int) { // expected-error {{this function cannot be a coroutine: 'std::experimental::coroutine_traits<int, int>' has no member named 'promise_type'}}
  co_await a;
  co_await a;
}

template <>
struct std::experimental::coroutine_traits<double, double> { typedef int promise_type; };
double bad_promise_type(double) { // expected-error {{this function cannot be a coroutine: 'experimental::coroutine_traits<double, double>::promise_type' (aka 'int') is not a class}}
  co_await a;
}

template <>
struct std::experimental::coroutine_traits<double, int> {
  struct promise_type {};
};
double bad_promise_type_2(int) { // expected-error {{no member named 'initial_suspend'}}
  co_yield 0; // expected-error {{no member named 'yield_value' in 'std::experimental::coroutine_traits<double, int>::promise_type'}}
}

struct promise; // expected-note {{forward declaration}}
struct promise_void;
struct void_tag {};
template <typename... T>
struct std::experimental::coroutine_traits<void, T...> { using promise_type = promise; };
template <typename... T>
struct std::experimental::coroutine_traits<void, void_tag, T...>
{ using promise_type = promise_void; };

// FIXME: This diagnostic is terrible.
void undefined_promise() { // expected-error {{this function cannot be a coroutine: 'experimental::coroutine_traits<void>::promise_type' (aka 'promise') is an incomplete type}}
  co_await a;
}

struct yielded_thing { const char *p; short a, b; };

struct not_awaitable {};

struct promise {
  void get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  awaitable yield_value(int); // expected-note 2{{candidate}}
  awaitable yield_value(yielded_thing); // expected-note 2{{candidate}}
  not_awaitable yield_value(void()); // expected-note 2{{candidate}}
  void return_value(int); // expected-note 2{{here}}
  void unhandled_exception();
};

struct promise_void {
  void get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void return_void();
  void unhandled_exception();
};

void no_coroutine_handle() { // expected-error {{std::experimental::coroutine_handle type was not found; include <experimental/coroutine> before defining a coroutine}}
  //expected-note@-1 {{call to 'initial_suspend' implicitly required by the initial suspend point}}
  co_return 5; //expected-note {{function is a coroutine due to use of 'co_return' here}}
}

namespace std {
namespace experimental {
template <class PromiseType = void>
struct coroutine_handle {
  static coroutine_handle from_address(void *);
};
template <>
struct coroutine_handle<void> {
  template <class PromiseType>
  coroutine_handle(coroutine_handle<PromiseType>);
  static coroutine_handle from_address(void *);
};
}} // namespace std::experimental

void yield() {
  co_yield 0;
  co_yield {"foo", 1, 2};
  co_yield {1e100}; // expected-error {{cannot be narrowed}} expected-note {{explicit cast}} expected-warning {{implicit conversion}} expected-warning {{braces around scalar}}
  co_yield {"foo", __LONG_LONG_MAX__}; // expected-error {{cannot be narrowed}} expected-note {{explicit cast}} expected-warning {{changes value}}
  co_yield {"foo"};
  co_yield "foo"; // expected-error {{no matching}}
  co_yield 1.0;
  co_yield yield; // expected-error {{no member named 'await_ready' in 'not_awaitable'}}
}

void check_auto_await_suspend() {
  co_await auto_await_suspend{}; // Should compile successfully.
}

void coreturn(int n) {
  co_await a;
  if (n == 0)
    co_return 3;
  if (n == 1)
    co_return {4}; // expected-warning {{braces around scalar initializer}}
  if (n == 2)
    co_return "foo"; // expected-error {{cannot initialize a parameter of type 'int' with an lvalue of type 'const char [4]'}}
  co_return 42;
}

template <class T>
void co_await_non_dependent_arg(T) {
  co_await a;
}
template void co_await_non_dependent_arg(int);

void mixed_yield() {
  co_yield 0; // expected-note {{use of 'co_yield'}}
  return; // expected-error {{not allowed in coroutine}}
}

void mixed_yield_invalid() {
  co_yield blah; // expected-error {{use of undeclared identifier}}
  // expected-note@-1 {{function is a coroutine due to use of 'co_yield'}}
  return; // expected-error {{return statement not allowed in coroutine}}
}

template <class T>
void mixed_yield_template(T) {
  co_yield blah; // expected-error {{use of undeclared identifier}}
  // expected-note@-1 {{function is a coroutine due to use of 'co_yield'}}
  return; // expected-error {{return statement not allowed in coroutine}}
}

template <class T>
void mixed_yield_template2(T) {
  co_yield 42;
  // expected-note@-1 {{function is a coroutine due to use of 'co_yield'}}
  return; // expected-error {{return statement not allowed in coroutine}}
}

template <class T>
void mixed_yield_template3(T v) {
  co_yield blah(v);
  // expected-note@-1 {{function is a coroutine due to use of 'co_yield'}}
  return; // expected-error {{return statement not allowed in coroutine}}
}

void mixed_await() {
  co_await a; // expected-note {{use of 'co_await'}}
  return; // expected-error {{not allowed in coroutine}}
}

void mixed_await_invalid() {
  co_await 42; // expected-error {{'int' is not a structure or union}}
  // expected-note@-1 {{function is a coroutine due to use of 'co_await'}}
  return; // expected-error {{not allowed in coroutine}}
}

template <class T>
void mixed_await_template(T) {
  co_await 42;
  // expected-note@-1 {{function is a coroutine due to use of 'co_await'}}
  return; // expected-error {{not allowed in coroutine}}
}

template <class T>
void mixed_await_template2(T v) {
  co_await v; // expected-error {{'long' is not a structure or union}}
  // expected-note@-1 {{function is a coroutine due to use of 'co_await'}}
  return; // expected-error {{not allowed in coroutine}}
}
template void mixed_await_template2(long); // expected-note {{requested here}}

void only_coreturn(void_tag) {
  co_return; // OK
}

void mixed_coreturn(void_tag, bool b) {
  if (b)
    co_return; // expected-note {{use of 'co_return'}}
  else
    return; // expected-error {{not allowed in coroutine}}
}

void mixed_coreturn_invalid(bool b) {
  if (b)
    co_return; // expected-note {{use of 'co_return'}}
    // expected-error@-1 {{no member named 'return_void' in 'promise'}}
  else
    return; // expected-error {{not allowed in coroutine}}
}

template <class T>
void mixed_coreturn_template(void_tag, bool b, T v) {
  if (b)
    co_return v; // expected-note {{use of 'co_return'}}
    // expected-error@-1 {{no member named 'return_value' in 'promise_void'}}
  else
    return; // expected-error {{not allowed in coroutine}}
}
template void mixed_coreturn_template(void_tag, bool, int); // expected-note {{requested here}}

template <class T>
void mixed_coreturn_template2(bool b, T) {
  if (b)
    co_return v; // expected-note {{use of 'co_return'}}
    // expected-error@-1 {{use of undeclared identifier 'v'}}
  else
    return; // expected-error {{not allowed in coroutine}}
}

struct CtorDtor {
  CtorDtor() {
    co_yield 0; // expected-error {{'co_yield' cannot be used in a constructor}}
  }
  CtorDtor(awaitable a) {
    // The spec doesn't say this is ill-formed, but it must be.
    co_await a; // expected-error {{'co_await' cannot be used in a constructor}}
  }
  ~CtorDtor() {
    co_return 0; // expected-error {{'co_return' cannot be used in a destructor}}
  }
  void operator=(CtorDtor&) {
    co_yield 0; // OK.
  }
  void operator=(CtorDtor const &) {
    co_yield 0; // OK.
  }
  void operator=(CtorDtor &&) {
    co_await a; // OK.
  }
  void operator=(CtorDtor const &&) {
    co_await a; // OK.
  }
  void operator=(int) {
    co_await a; // OK. Not a special member
  }
};

namespace std { class type_info; }

void unevaluated() {
  decltype(co_await a); // expected-error {{'co_await' cannot be used in an unevaluated context}}
                        // expected-warning@-1 {{declaration does not declare anything}}
  sizeof(co_await a); // expected-error {{'co_await' cannot be used in an unevaluated context}}
                      // expected-error@-1 {{invalid application of 'sizeof' to an incomplete type 'void'}}
  typeid(co_await a); // expected-error {{'co_await' cannot be used in an unevaluated context}}
                      // expected-warning@-1 {{expression with side effects has no effect in an unevaluated context}}
                      // expected-warning@-2 {{expression result unused}}
  decltype(co_yield 1); // expected-error {{'co_yield' cannot be used in an unevaluated context}}
                        // expected-warning@-1 {{declaration does not declare anything}}
  sizeof(co_yield 2); // expected-error {{'co_yield' cannot be used in an unevaluated context}}
                      // expected-error@-1 {{invalid application of 'sizeof' to an incomplete type 'void'}}
  typeid(co_yield 3); // expected-error {{'co_yield' cannot be used in an unevaluated context}}
                      // expected-warning@-1 {{expression with side effects has no effect in an unevaluated context}}
                      // expected-warning@-2 {{expression result unused}}
}

// [expr.await]p2: "An await-expression shall not appear in a default argument."
// FIXME: A better diagnostic would explicitly state that default arguments are
// not allowed. A user may not understand that this is "outside a function."
void default_argument(int arg = co_await 0) {} // expected-error {{'co_await' cannot be used outside a function}}

void await_in_catch_coroutine() {
  try {
  } catch (...) { // FIXME: Emit a note diagnostic pointing out the try handler on this line.
    []() -> void { co_await a; }(); // OK
    co_await a; // expected-error {{'co_await' cannot be used in the handler of a try block}}
  }
}

void await_nested_in_catch_coroutine() {
  try {
  } catch (...) { // FIXME: Emit a note diagnostic pointing out the try handler on this line.
    try {
      co_await a; // expected-error {{'co_await' cannot be used in the handler of a try block}}
      []() -> void { co_await a; }(); // OK
    } catch (...) {
      co_return 123;
    }
  }
}

void await_in_lambda_in_catch_coroutine() {
  try {
  } catch (...) {
    []() -> void { co_await a; }(); // OK
  }
}

void yield_in_catch_coroutine() {
  try {
  } catch (...) {
    co_yield 1; // expected-error {{'co_yield' cannot be used in the handler of a try block}}
  }
}

void return_in_catch_coroutine() {
  try {
  } catch (...) {
    co_return 123; // OK
  }
}

constexpr auto constexpr_deduced_return_coroutine() {
  co_yield 0; // expected-error {{'co_yield' cannot be used in a constexpr function}}
  // expected-error@-1 {{'co_yield' cannot be used in a function with a deduced return type}}
}

void varargs_coroutine(const char *, ...) {
  co_await a; // expected-error {{'co_await' cannot be used in a varargs function}}
}

auto deduced_return_coroutine() {
  co_await a; // expected-error {{'co_await' cannot be used in a function with a deduced return type}}
}

struct outer {};
struct await_arg_1 {};
struct await_arg_2 {};

namespace adl_ns {
struct coawait_arg_type {};
awaitable operator co_await(coawait_arg_type);
}

namespace dependent_operator_co_await_lookup {
  template<typename T> void await_template(T t) {
    // no unqualified lookup results
    co_await t; // expected-error {{no member named 'await_ready' in 'dependent_operator_co_await_lookup::not_awaitable'}}
    // expected-error@-1 {{call to function 'operator co_await' that is neither visible in the template definition nor found by argument-dependent lookup}}
  };
  template void await_template(awaitable);

  struct indirectly_awaitable { indirectly_awaitable(outer); };
  awaitable operator co_await(indirectly_awaitable); // expected-note {{should be declared prior to}}
  template void await_template(indirectly_awaitable);

  struct not_awaitable {};
  template void await_template(not_awaitable); // expected-note {{instantiation}}

  template<typename T> void await_template_2(T t) {
    // one unqualified lookup result
    co_await t;
  };
  template void await_template(outer); // expected-note {{instantiation}}
  template void await_template_2(outer);

  struct transform_awaitable {};
  struct transformed {};

  struct transform_promise {
    typedef transform_awaitable await_arg;
    coro<transform_promise> get_return_object();
    transformed initial_suspend();
    ::adl_ns::coawait_arg_type final_suspend();
    transformed await_transform(transform_awaitable);
    void unhandled_exception();
    void return_void();
  };
  template <class AwaitArg>
  struct basic_promise {
    typedef AwaitArg await_arg;
    coro<basic_promise> get_return_object();
    awaitable initial_suspend();
    awaitable final_suspend();
    void unhandled_exception();
    void return_void();
  };

  awaitable operator co_await(await_arg_1);

  template <typename T, typename U>
  coro<T> await_template_3(U t) {
    co_await t;
  }

  template coro<basic_promise<await_arg_1>> await_template_3<basic_promise<await_arg_1>>(await_arg_1);

  template <class T, int I = 0>
  struct dependent_member {
    coro<T> mem_fn() const {
      co_await typename T::await_arg{}; // expected-error {{call to function 'operator co_await'}}}
    }
    template <class U>
    coro<T> dep_mem_fn(U t) {
      co_await t;
    }
  };

  template <>
  struct dependent_member<long> {
    // FIXME this diagnostic is terrible
    coro<transform_promise> mem_fn() const { // expected-error {{no member named 'await_ready' in 'dependent_operator_co_await_lookup::transformed'}}
      // expected-note@-1 {{call to 'initial_suspend' implicitly required by the initial suspend point}}
      // expected-note@+1 {{function is a coroutine due to use of 'co_await' here}}
      co_await transform_awaitable{};
      // expected-error@-1 {{no member named 'await_ready'}}
    }
    template <class R, class U>
    coro<R> dep_mem_fn(U u) { co_await u; }
  };

  awaitable operator co_await(await_arg_2); // expected-note {{'operator co_await' should be declared prior to the call site}}

  template struct dependent_member<basic_promise<await_arg_1>, 0>;
  template struct dependent_member<basic_promise<await_arg_2>, 0>; // expected-note {{in instantiation}}

  template <>
  coro<transform_promise>
      // FIXME this diagnostic is terrible
      dependent_member<long>::dep_mem_fn<transform_promise>(int) { // expected-error {{no member named 'await_ready' in 'dependent_operator_co_await_lookup::transformed'}}
    //expected-note@-1 {{call to 'initial_suspend' implicitly required by the initial suspend point}}
    //expected-note@+1 {{function is a coroutine due to use of 'co_await' here}}
    co_await transform_awaitable{};
    // expected-error@-1 {{no member named 'await_ready'}}
  }

  void operator co_await(transform_awaitable) = delete;
  awaitable operator co_await(transformed);

  template coro<transform_promise>
      dependent_member<long>::dep_mem_fn<transform_promise>(transform_awaitable);

  template <>
  coro<transform_promise> dependent_member<long>::dep_mem_fn<transform_promise>(long) {
    co_await transform_awaitable{};
  }

  template <>
  struct dependent_member<int> {
    coro<transform_promise> mem_fn() const {
      co_await transform_awaitable{};
    }
  };

  template coro<transform_promise> await_template_3<transform_promise>(transform_awaitable);
  template struct dependent_member<transform_promise>;
  template coro<transform_promise> dependent_member<transform_promise>::dep_mem_fn(transform_awaitable);
}

struct yield_fn_tag {};
template <>
struct std::experimental::coroutine_traits<void, yield_fn_tag> {
  struct promise_type {
    // FIXME: add an await_transform overload for functions
    awaitable yield_value(int());
    void return_value(int());

    suspend_never initial_suspend();
    suspend_never final_suspend();
    void get_return_object();
    void unhandled_exception();
  };
};

namespace placeholder {
  awaitable f(), f(int); // expected-note 4{{possible target}}
  int g(), g(int); // expected-note 2{{candidate}}
  void x() {
    co_await f; // expected-error {{reference to overloaded function}}
  }
  void y() {
    co_yield g; // expected-error {{no matching member function for call to 'yield_value'}}
  }
  void z() {
    co_await a;
    co_return g; // expected-error {{address of overloaded function 'g' does not match required type 'int'}}
  }

  void x(yield_fn_tag) {
    co_await f; // expected-error {{reference to overloaded function}}
  }
  void y(yield_fn_tag) {
    co_yield g;
  }
  void z(yield_fn_tag) {
    co_await a;
    co_return g;
  }
}

struct bad_promise_1 {
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void unhandled_exception();
  void return_void();
};
coro<bad_promise_1> missing_get_return_object() { // expected-error {{no member named 'get_return_object' in 'bad_promise_1'}}
  co_await a;
}

struct bad_promise_2 {
  coro<bad_promise_2> get_return_object();
  suspend_always final_suspend();
  void unhandled_exception();
  void return_void();
};
// FIXME: This shouldn't happen twice
coro<bad_promise_2> missing_initial_suspend() { // expected-error {{no member named 'initial_suspend' in 'bad_promise_2'}}
  co_await a;
}

struct bad_promise_3 {
  coro<bad_promise_3> get_return_object();
  suspend_always initial_suspend();
  void unhandled_exception();
  void return_void();
};
coro<bad_promise_3> missing_final_suspend() { // expected-error {{no member named 'final_suspend' in 'bad_promise_3'}}
  co_await a;
}

struct bad_promise_4 {
  coro<bad_promise_4> get_return_object();
  not_awaitable initial_suspend();
  suspend_always final_suspend();
  void return_void();
};
// FIXME: This diagnostic is terrible.
coro<bad_promise_4> bad_initial_suspend() { // expected-error {{no member named 'await_ready' in 'not_awaitable'}}
  // expected-note@-1 {{call to 'initial_suspend' implicitly required by the initial suspend point}}
  co_await a; // expected-note {{function is a coroutine due to use of 'co_await' here}}
}

struct bad_promise_5 {
  coro<bad_promise_5> get_return_object();
  suspend_always initial_suspend();
  not_awaitable final_suspend();
  void return_void();
};
// FIXME: This diagnostic is terrible.
coro<bad_promise_5> bad_final_suspend() { // expected-error {{no member named 'await_ready' in 'not_awaitable'}}
  // expected-note@-1 {{call to 'final_suspend' implicitly required by the final suspend point}}
  co_await a; // expected-note {{function is a coroutine due to use of 'co_await' here}}
}

struct bad_promise_6 {
  coro<bad_promise_6> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void unhandled_exception();
  void return_void();           // expected-note 2 {{member 'return_void' first declared here}}
  void return_value(int) const; // expected-note 2 {{member 'return_value' first declared here}}
  void return_value(int);
};
coro<bad_promise_6> bad_implicit_return() { // expected-error {{'bad_promise_6' declares both 'return_value' and 'return_void'}}
  co_await a;
}

template <class T>
coro<T> bad_implicit_return_dependent(T) { // expected-error {{'bad_promise_6' declares both 'return_value' and 'return_void'}}
  co_await a;
}
template coro<bad_promise_6> bad_implicit_return_dependent(bad_promise_6); // expected-note {{in instantiation}}

struct bad_promise_7 { // expected-note 2 {{defined here}}
  coro<bad_promise_7> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void return_void();
};
coro<bad_promise_7> no_unhandled_exception() { // expected-error {{'bad_promise_7' is required to declare the member 'unhandled_exception()'}}
  co_await a;
}

template <class T>
coro<T> no_unhandled_exception_dependent(T) { // expected-error {{'bad_promise_7' is required to declare the member 'unhandled_exception()'}}
  co_await a;
}
template coro<bad_promise_7> no_unhandled_exception_dependent(bad_promise_7); // expected-note {{in instantiation}}

struct bad_promise_base {
private:
  void return_void(); // expected-note 2 {{declared private here}}
};
struct bad_promise_8 : bad_promise_base {
  coro<bad_promise_8> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void unhandled_exception() __attribute__((unavailable)); // expected-note 2 {{marked unavailable here}}
  void unhandled_exception() const;
  void unhandled_exception(void *) const;
};
coro<bad_promise_8> calls_unhandled_exception() {
  // expected-error@-1 {{'unhandled_exception' is unavailable}}
  // expected-error@-2 {{'return_void' is a private member}}
  co_await a;
}

template <class T>
coro<T> calls_unhandled_exception_dependent(T) {
  // expected-error@-1 {{'unhandled_exception' is unavailable}}
  // expected-error@-2 {{'return_void' is a private member}}
  co_await a;
}
template coro<bad_promise_8> calls_unhandled_exception_dependent(bad_promise_8); // expected-note {{in instantiation}}

struct bad_promise_9 {
  coro<bad_promise_9> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void await_transform(void *);
  awaitable await_transform(int) __attribute__((unavailable)); // expected-note {{explicitly marked unavailable}}
  void return_void();
  void unhandled_exception();
};
coro<bad_promise_9> calls_await_transform() {
  co_await 42; // expected-error {{'await_transform' is unavailable}}
}

struct bad_promise_10 {
  coro<bad_promise_10> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  int await_transform;
  void return_void();
  void unhandled_exception();
};
coro<bad_promise_10> bad_coawait() {
  // FIXME this diagnostic is terrible
  co_await 42; // expected-error {{called object type 'int' is not a function or function pointer}}
  // expected-note@-1 {{call to 'await_transform' implicitly required by 'co_await' here}}
}

struct call_operator {
  template <class... Args>
  awaitable operator()(Args...) const { return a; }
};
void ret_void();
struct good_promise_1 {
  coro<good_promise_1> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void unhandled_exception();
  static const call_operator await_transform;
  using Fn = void (*)();
  Fn return_void = ret_void;
};
const call_operator good_promise_1::await_transform;
coro<good_promise_1> ok_static_coawait() {
  // FIXME this diagnostic is terrible
  co_await 42;
}

template<typename T> void ok_generic_lambda_coawait_PR41909() {
  [](auto& arg) -> coro<good_promise_1> { // expected-warning {{expression result unused}}
    co_await 12;
  };
  [](auto &arg) -> coro<good_promise_1> {
    co_await 24;
  }("argument");
  [](auto &arg) ->coro<good_promise_1> { // expected-warning {{expression result unused}}
    []() -> coro<good_promise_1> {
      co_await 36;
    };
    co_await 48;
  };
}
template void ok_generic_lambda_coawait_PR41909<int>(); // expected-note {{in instantiation of function template specialization 'ok_generic_lambda_coawait_PR41909<int>' requested here}}

template<> struct std::experimental::coroutine_traits<int, int, const char**>
{ using promise_type = promise; };

int main(int, const char**) {
  co_await a; // expected-error {{'co_await' cannot be used in the 'main' function}}
}

struct good_promise_2 {
  float get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void return_void();
  void unhandled_exception();
};
template<> struct std::experimental::coroutine_handle<good_promise_2> {};

template<> struct std::experimental::coroutine_traits<float>
{ using promise_type = good_promise_2; };

float badly_specialized_coro_handle() { // expected-error {{std::experimental::coroutine_handle missing a member named 'from_address'}}
  //expected-note@-1 {{call to 'initial_suspend' implicitly required by the initial suspend point}}
  co_return; //expected-note {{function is a coroutine due to use of 'co_return' here}}
}

namespace std {
  struct nothrow_t {};
  constexpr nothrow_t nothrow = {};
}

using SizeT = decltype(sizeof(int));

void* operator new(SizeT __sz, const std::nothrow_t&) noexcept;
void  operator delete(void* __p, const std::nothrow_t&) noexcept;



struct promise_on_alloc_failure_tag {};

template<>
struct std::experimental::coroutine_traits<int, promise_on_alloc_failure_tag> {
  struct promise_type {
    int get_return_object() {}
    suspend_always initial_suspend() { return {}; }
    suspend_always final_suspend() { return {}; }
    void return_void() {}
    int get_return_object_on_allocation_failure(); // expected-error{{'promise_type': 'get_return_object_on_allocation_failure()' must be a static member function}}
    void unhandled_exception();
  };
};

extern "C" int f(promise_on_alloc_failure_tag) {
  co_return; //expected-note {{function is a coroutine due to use of 'co_return' here}}
}

struct bad_promise_11 {
  coro<bad_promise_11> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void unhandled_exception();
  void return_void();

private:
  static coro<bad_promise_11> get_return_object_on_allocation_failure(); // expected-note 2 {{declared private here}}
};
coro<bad_promise_11> private_alloc_failure_handler() {
  // expected-error@-1 {{'get_return_object_on_allocation_failure' is a private member of 'bad_promise_11'}}
  co_return; // FIXME: Add a "declared coroutine here" note.
}

template <class T>
coro<T> dependent_private_alloc_failure_handler(T) {
  // expected-error@-1 {{'get_return_object_on_allocation_failure' is a private member of 'bad_promise_11'}}
  co_return; // FIXME: Add a "declared coroutine here" note.
}
template coro<bad_promise_11> dependent_private_alloc_failure_handler(bad_promise_11);
// expected-note@-1 {{requested here}}

struct bad_promise_12 {
  coro<bad_promise_12> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void unhandled_exception();
  void return_void();
  static coro<bad_promise_12> get_return_object_on_allocation_failure();

  static void* operator new(SizeT);
  // expected-error@-1 2 {{'operator new' is required to have a non-throwing noexcept specification when the promise type declares 'get_return_object_on_allocation_failure()'}}
};
coro<bad_promise_12> throwing_in_class_new() { // expected-note {{call to 'operator new' implicitly required by coroutine function here}}
  co_return;
}

template <class T>
coro<T> dependent_throwing_in_class_new(T) { // expected-note {{call to 'operator new' implicitly required by coroutine function here}}
   co_return;
}
template coro<bad_promise_12> dependent_throwing_in_class_new(bad_promise_12); // expected-note {{requested here}}


struct good_promise_13 {
  coro<good_promise_13> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void unhandled_exception();
  void return_void();
  static coro<good_promise_13> get_return_object_on_allocation_failure();
};
coro<good_promise_13> uses_nothrow_new() {
  co_return;
}

template <class T>
coro<T> dependent_uses_nothrow_new(T) {
   co_return;
}
template coro<good_promise_13> dependent_uses_nothrow_new(good_promise_13);

struct good_promise_custom_new_operator {
  coro<good_promise_custom_new_operator> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void return_void();
  void unhandled_exception();
  void *operator new(SizeT, double, float, int);
};

coro<good_promise_custom_new_operator>
good_coroutine_calls_custom_new_operator(double, float, int) {
  co_return;
}

struct coroutine_nonstatic_member_struct;

struct good_promise_nonstatic_member_custom_new_operator {
  coro<good_promise_nonstatic_member_custom_new_operator> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void return_void();
  void unhandled_exception();
  void *operator new(SizeT, coroutine_nonstatic_member_struct &, double);
};

struct good_promise_noexcept_custom_new_operator {
  static coro<good_promise_noexcept_custom_new_operator> get_return_object_on_allocation_failure();
  coro<good_promise_noexcept_custom_new_operator> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void return_void();
  void unhandled_exception();
  void *operator new(SizeT, double, float, int) noexcept;
};

coro<good_promise_noexcept_custom_new_operator>
good_coroutine_calls_noexcept_custom_new_operator(double, float, int) {
  co_return;
}

struct mismatch_gro_type_tag1 {};
template<>
struct std::experimental::coroutine_traits<int, mismatch_gro_type_tag1> {
  struct promise_type {
    void get_return_object() {} //expected-note {{member 'get_return_object' declared here}}
    suspend_always initial_suspend() { return {}; }
    suspend_always final_suspend() { return {}; }
    void return_void() {}
    void unhandled_exception();
  };
};

extern "C" int f(mismatch_gro_type_tag1) {
  // expected-error@-1 {{cannot initialize return object of type 'int' with an rvalue of type 'void'}}
  co_return; //expected-note {{function is a coroutine due to use of 'co_return' here}}
}

struct mismatch_gro_type_tag2 {};
template<>
struct std::experimental::coroutine_traits<int, mismatch_gro_type_tag2> {
  struct promise_type {
    void *get_return_object() {} //expected-note {{member 'get_return_object' declared here}}
    suspend_always initial_suspend() { return {}; }
    suspend_always final_suspend() { return {}; }
    void return_void() {}
    void unhandled_exception();
  };
};

extern "C" int f(mismatch_gro_type_tag2) {
  // expected-error@-1 {{cannot initialize return object of type 'int' with an lvalue of type 'void *'}}
  co_return; //expected-note {{function is a coroutine due to use of 'co_return' here}}
}

struct mismatch_gro_type_tag3 {};
template<>
struct std::experimental::coroutine_traits<int, mismatch_gro_type_tag3> {
  struct promise_type {
    int get_return_object() {}
    static void get_return_object_on_allocation_failure() {} //expected-note {{member 'get_return_object_on_allocation_failure' declared here}}
    suspend_always initial_suspend() { return {}; }
    suspend_always final_suspend() { return {}; }
    void return_void() {}
    void unhandled_exception();
  };
};

extern "C" int f(mismatch_gro_type_tag3) {
  // expected-error@-1 {{cannot initialize return object of type 'int' with an rvalue of type 'void'}}
  co_return; //expected-note {{function is a coroutine due to use of 'co_return' here}}
}


struct mismatch_gro_type_tag4 {};
template<>
struct std::experimental::coroutine_traits<int, mismatch_gro_type_tag4> {
  struct promise_type {
    int get_return_object() {}
    static char *get_return_object_on_allocation_failure() {} //expected-note {{member 'get_return_object_on_allocation_failure' declared}}
    suspend_always initial_suspend() { return {}; }
    suspend_always final_suspend() { return {}; }
    void return_void() {}
    void unhandled_exception();
  };
};

extern "C" int f(mismatch_gro_type_tag4) {
  // expected-error@-1 {{cannot initialize return object of type 'int' with an rvalue of type 'char *'}}
  co_return; //expected-note {{function is a coroutine due to use of 'co_return' here}}
}

struct bad_promise_no_return_func { // expected-note {{'bad_promise_no_return_func' defined here}}
  coro<bad_promise_no_return_func> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void unhandled_exception();
};
// FIXME: The PDTS currently specifies this as UB, technically forbidding a
// diagnostic.
coro<bad_promise_no_return_func> no_return_value_or_return_void() {
  // expected-error@-1 {{'bad_promise_no_return_func' must declare either 'return_value' or 'return_void'}}
  co_await a;
}

struct bad_await_suspend_return {
  bool await_ready();
  // expected-error@+1 {{return type of 'await_suspend' is required to be 'void' or 'bool' (have 'char')}}
  char await_suspend(std::experimental::coroutine_handle<>);
  void await_resume();
};
struct bad_await_ready_return {
  // expected-note@+1 {{return type of 'await_ready' is required to be contextually convertible to 'bool'}}
  void await_ready();
  bool await_suspend(std::experimental::coroutine_handle<>);
  void await_resume();
};
struct await_ready_explicit_bool {
  struct BoolT {
    explicit operator bool() const;
  };
  BoolT await_ready();
  void await_suspend(std::experimental::coroutine_handle<>);
  void await_resume();
};
template <class SuspendTy>
struct await_suspend_type_test {
  bool await_ready();
  // expected-error@+2 {{return type of 'await_suspend' is required to be 'void' or 'bool' (have 'bool &')}}
  // expected-error@+1 {{return type of 'await_suspend' is required to be 'void' or 'bool' (have 'bool &&')}}
  SuspendTy await_suspend(std::experimental::coroutine_handle<>);
  void await_resume();
};
void test_bad_suspend() {
  {
    // FIXME: The actual error emitted here is terrible, and no number of notes can save it.
    bad_await_ready_return a;
    // expected-error@+1 {{value of type 'void' is not contextually convertible to 'bool'}}
    co_await a; // expected-note {{call to 'await_ready' implicitly required by coroutine function here}}
  }
  {
    bad_await_suspend_return b;
    co_await b; // expected-note {{call to 'await_suspend' implicitly required by coroutine function here}}
  }
  {
    await_ready_explicit_bool c;
    co_await c; // OK
  }
  {
    await_suspend_type_test<bool &&> a;
    await_suspend_type_test<bool &> b;
    await_suspend_type_test<const void> c;
    await_suspend_type_test<const volatile bool> d;
    co_await a; // expected-note {{call to 'await_suspend' implicitly required by coroutine function here}}
    co_await b; // expected-note {{call to 'await_suspend' implicitly required by coroutine function here}}
    co_await c; // OK
    co_await d; // OK
  }
}

template <int ID = 0>
struct NoCopy {
  NoCopy(NoCopy const&) = delete; // expected-note 2 {{deleted here}}
};
template <class T, class U>
void test_dependent_param(T t, U) {
  // expected-error@-1 {{call to deleted constructor of 'NoCopy<0>'}}
  // expected-error@-2 {{call to deleted constructor of 'NoCopy<1>'}}
  ((void)t);
  co_return 42;
}
template void test_dependent_param(NoCopy<0>, NoCopy<1>); // expected-note {{requested here}}

namespace CoroHandleMemberFunctionTest {
struct CoroMemberTag {};
struct BadCoroMemberTag {};

template <class T, class U>
constexpr bool IsSameV = false;
template <class T>
constexpr bool IsSameV<T, T> = true;

template <class T>
struct TypeTest {
  template <class U>
  static constexpr bool IsSame = IsSameV<T, U>;

  template <class... Args>
  static constexpr bool MatchesArgs = IsSameV<T,
                                              std::experimental::coroutine_traits<CoroMemberTag, Args...>>;
};

template <class T>
struct AwaitReturnsType {
  bool await_ready() const;
  void await_suspend(...) const;
  T await_resume() const;
};

template <class... CoroTraitsArgs>
struct CoroMemberPromise {
  using TraitsT = std::experimental::coroutine_traits<CoroTraitsArgs...>;
  using TypeTestT = TypeTest<TraitsT>;
  using AwaitTestT = AwaitReturnsType<TypeTestT>;

  CoroMemberTag get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();

  AwaitTestT yield_value(int);

  void return_void();
  void unhandled_exception();
};

} // namespace CoroHandleMemberFunctionTest

template <class... Args>
struct ::std::experimental::coroutine_traits<CoroHandleMemberFunctionTest::CoroMemberTag, Args...> {
  using promise_type = CoroHandleMemberFunctionTest::CoroMemberPromise<CoroHandleMemberFunctionTest::CoroMemberTag, Args...>;
};

namespace CoroHandleMemberFunctionTest {
struct TestType {

  CoroMemberTag test_qual() {
    auto TC = co_yield 0;
    static_assert(TC.MatchesArgs<TestType &>, "");
    static_assert(!TC.MatchesArgs<TestType>, "");
    static_assert(!TC.MatchesArgs<TestType *>, "");
  }

  CoroMemberTag test_sanity(int *) const {
    auto TC = co_yield 0;
    static_assert(TC.MatchesArgs<const TestType &>, ""); // expected-error {{static_assert failed}}
    static_assert(TC.MatchesArgs<const TestType &>, ""); // expected-error {{static_assert failed}}
    static_assert(TC.MatchesArgs<const TestType &, int *>, "");
  }

  CoroMemberTag test_qual(int *, const float &&, volatile void *volatile) const {
    auto TC = co_yield 0;
    static_assert(TC.MatchesArgs<const TestType &, int *, const float &&, volatile void *volatile>, "");
  }

  CoroMemberTag test_qual() const volatile {
    auto TC = co_yield 0;
    static_assert(TC.MatchesArgs<const volatile TestType &>, "");
  }

  CoroMemberTag test_ref_qual() & {
    auto TC = co_yield 0;
    static_assert(TC.MatchesArgs<TestType &>, "");
  }
  CoroMemberTag test_ref_qual() const & {
    auto TC = co_yield 0;
    static_assert(TC.MatchesArgs<TestType const &>, "");
  }
  CoroMemberTag test_ref_qual() && {
    auto TC = co_yield 0;
    static_assert(TC.MatchesArgs<TestType &&>, "");
  }
  CoroMemberTag test_ref_qual(const char *&) const volatile && {
    auto TC = co_yield 0;
    static_assert(TC.MatchesArgs<TestType const volatile &&, const char *&>, "");
  }

  CoroMemberTag test_args(int) {
    auto TC = co_yield 0;
    static_assert(TC.MatchesArgs<TestType &, int>, "");
  }
  CoroMemberTag test_args(int, long &, void *) const {
    auto TC = co_yield 0;
    static_assert(TC.MatchesArgs<TestType const &, int, long &, void *>, "");
  }

  template <class... Args>
  CoroMemberTag test_member_template(Args...) const && {
    auto TC = co_yield 0;
    static_assert(TC.template MatchesArgs<TestType const &&, Args...>, "");
  }

  static CoroMemberTag test_static() {
    auto TC = co_yield 0;
    static_assert(TC.MatchesArgs<>, "");
    static_assert(!TC.MatchesArgs<TestType>, "");
    static_assert(!TC.MatchesArgs<TestType &>, "");
    static_assert(!TC.MatchesArgs<TestType *>, "");
  }

  static CoroMemberTag test_static(volatile void *const, char &&) {
    auto TC = co_yield 0;
    static_assert(TC.MatchesArgs<volatile void *const, char &&>, "");
  }

  template <class Dummy>
  static CoroMemberTag test_static_template(const char *volatile &, unsigned) {
    auto TC = co_yield 0;
    using TCT = decltype(TC);
    static_assert(TCT::MatchesArgs<const char *volatile &, unsigned>, "");
    static_assert(!TCT::MatchesArgs<TestType &, const char *volatile &, unsigned>, "");
  }

  BadCoroMemberTag test_diagnostics() {
    // expected-error@-1 {{this function cannot be a coroutine: 'std::experimental::coroutine_traits<CoroHandleMemberFunctionTest::BadCoroMemberTag, CoroHandleMemberFunctionTest::TestType &>' has no member named 'promise_type'}}
    co_return;
  }
  BadCoroMemberTag test_diagnostics(int) const && {
    // expected-error@-1 {{this function cannot be a coroutine: 'std::experimental::coroutine_traits<CoroHandleMemberFunctionTest::BadCoroMemberTag, const CoroHandleMemberFunctionTest::TestType &&, int>' has no member named 'promise_type'}}
    co_return;
  }

  static BadCoroMemberTag test_static_diagnostics(long *) {
    // expected-error@-1 {{this function cannot be a coroutine: 'std::experimental::coroutine_traits<CoroHandleMemberFunctionTest::BadCoroMemberTag, long *>' has no member named 'promise_type'}}
    co_return;
  }
};

template CoroMemberTag TestType::test_member_template(long, const char *) const &&;
template CoroMemberTag TestType::test_static_template<void>(const char *volatile &, unsigned);

template <class... Args>
struct DepTestType {

  CoroMemberTag test_sanity(int *) const {
    auto TC = co_yield 0;
    static_assert(TC.template MatchesArgs<const DepTestType &>, ""); // expected-error {{static_assert failed}}
    static_assert(TC.template MatchesArgs<>, ""); // expected-error {{static_assert failed}}
    static_assert(TC.template MatchesArgs<const DepTestType &, int *>, "");
  }

  CoroMemberTag test_qual() {
    auto TC = co_yield 0;
    static_assert(TC.template MatchesArgs<DepTestType &>, "");
    static_assert(!TC.template MatchesArgs<DepTestType>, "");
    static_assert(!TC.template MatchesArgs<DepTestType *>, "");
  }

  CoroMemberTag test_qual(int *, const float &&, volatile void *volatile) const {
    auto TC = co_yield 0;
    static_assert(TC.template MatchesArgs<const DepTestType &, int *, const float &&, volatile void *volatile>, "");
  }

  CoroMemberTag test_qual() const volatile {
    auto TC = co_yield 0;
    static_assert(TC.template MatchesArgs<const volatile DepTestType &>, "");
  }

  CoroMemberTag test_ref_qual() & {
    auto TC = co_yield 0;
    static_assert(TC.template MatchesArgs<DepTestType &>, "");
  }
  CoroMemberTag test_ref_qual() const & {
    auto TC = co_yield 0;
    static_assert(TC.template MatchesArgs<DepTestType const &>, "");
  }
  CoroMemberTag test_ref_qual() && {
    auto TC = co_yield 0;
    static_assert(TC.template MatchesArgs<DepTestType &&>, "");
  }
  CoroMemberTag test_ref_qual(const char *&) const volatile && {
    auto TC = co_yield 0;
    static_assert(TC.template MatchesArgs<DepTestType const volatile &&, const char *&>, "");
  }

  CoroMemberTag test_args(int) {
    auto TC = co_yield 0;
    static_assert(TC.template MatchesArgs<DepTestType &, int>, "");
  }
  CoroMemberTag test_args(int, long &, void *) const {
    auto TC = co_yield 0;
    static_assert(TC.template MatchesArgs<DepTestType const &, int, long &, void *>, "");
  }

  template <class... UArgs>
  CoroMemberTag test_member_template(UArgs...) const && {
    auto TC = co_yield 0;
    static_assert(TC.template MatchesArgs<DepTestType const &&, UArgs...>, "");
  }

  static CoroMemberTag test_static() {
    auto TC = co_yield 0;
    using TCT = decltype(TC);
    static_assert(TCT::MatchesArgs<>, "");
    static_assert(!TCT::MatchesArgs<DepTestType>, "");
    static_assert(!TCT::MatchesArgs<DepTestType &>, "");
    static_assert(!TCT::MatchesArgs<DepTestType *>, "");

    // Ensure diagnostics are actually being generated here
    static_assert(TCT::MatchesArgs<int>, ""); // expected-error {{static_assert failed}}
  }

  static CoroMemberTag test_static(volatile void *const, char &&) {
    auto TC = co_yield 0;
    using TCT = decltype(TC);
    static_assert(TCT::MatchesArgs<volatile void *const, char &&>, "");
  }

  template <class Dummy>
  static CoroMemberTag test_static_template(const char *volatile &, unsigned) {
    auto TC = co_yield 0;
    using TCT = decltype(TC);
    static_assert(TCT::MatchesArgs<const char *volatile &, unsigned>, "");
    static_assert(!TCT::MatchesArgs<DepTestType &, const char *volatile &, unsigned>, "");
  }
};

template struct DepTestType<int>; // expected-note {{requested here}}
template CoroMemberTag DepTestType<int>::test_member_template(long, const char *) const &&;

template CoroMemberTag DepTestType<int>::test_static_template<void>(const char *volatile &, unsigned);

struct bad_promise_deleted_constructor {
  // expected-note@+1 {{'bad_promise_deleted_constructor' has been explicitly marked deleted here}}
  bad_promise_deleted_constructor() = delete;
  coro<bad_promise_deleted_constructor> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void return_void();
  void unhandled_exception();
};

coro<bad_promise_deleted_constructor>
bad_coroutine_calls_deleted_promise_constructor() {
  // expected-error@-1 {{call to deleted constructor of 'std::experimental::coroutine_traits<coro<CoroHandleMemberFunctionTest::bad_promise_deleted_constructor>>::promise_type' (aka 'CoroHandleMemberFunctionTest::bad_promise_deleted_constructor')}}
  co_return;
}

// Test that, when the promise type has a constructor whose signature matches
// that of the coroutine function, that constructor is used. If no matching
// constructor exists, the default constructor is used as a fallback. If no
// matching constructors exist at all, an error is emitted. This is an
// experimental feature that will be proposed for the Coroutines TS.

struct good_promise_default_constructor {
  good_promise_default_constructor(double, float, int);
  good_promise_default_constructor() = default;
  coro<good_promise_default_constructor> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void return_void();
  void unhandled_exception();
};

coro<good_promise_default_constructor>
good_coroutine_calls_default_constructor() {
  co_return;
}

struct some_class;

struct good_promise_custom_constructor {
  good_promise_custom_constructor(some_class&, float, int);
  good_promise_custom_constructor(double, float, int);
  good_promise_custom_constructor() = delete;
  coro<good_promise_custom_constructor> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void return_void();
  void unhandled_exception();
};

coro<good_promise_custom_constructor>
good_coroutine_calls_custom_constructor(double, float, int) {
  co_return;
}

struct some_class {
  coro<good_promise_custom_constructor>
  good_coroutine_calls_custom_constructor(float, int) {
    co_return;
  }
  coro<good_promise_custom_constructor>
  static good_coroutine_calls_custom_constructor(double, float, int) {
    co_return;
  }
};

struct bad_promise_no_matching_constructor {
  bad_promise_no_matching_constructor(int, int, int);
  // expected-note@+1 2 {{'bad_promise_no_matching_constructor' has been explicitly marked deleted here}}
  bad_promise_no_matching_constructor() = delete;
  coro<bad_promise_no_matching_constructor> get_return_object();
  suspend_always initial_suspend();
  suspend_always final_suspend();
  void return_void();
  void unhandled_exception();
};

coro<bad_promise_no_matching_constructor>
bad_coroutine_calls_with_no_matching_constructor(int, int) {
  // expected-error@-1 {{call to deleted constructor of 'std::experimental::coroutine_traits<coro<CoroHandleMemberFunctionTest::bad_promise_no_matching_constructor>, int, int>::promise_type' (aka 'CoroHandleMemberFunctionTest::bad_promise_no_matching_constructor')}}
  co_return;
}

struct some_class2 {
coro<bad_promise_no_matching_constructor>
bad_coroutine_calls_with_no_matching_constructor(int, int, int) {
  // expected-error@-1 {{call to deleted constructor}}
  co_return;
}
};

} // namespace CoroHandleMemberFunctionTest

class awaitable_no_unused_warn {
public:
  using handle_type = std::experimental::coroutine_handle<>;
  constexpr bool await_ready()  { return false; }
  void await_suspend(handle_type) noexcept {}
  int await_resume() { return 1; }
};


class awaitable_unused_warn {
public:
  using handle_type = std::experimental::coroutine_handle<>;
  constexpr bool await_ready()  { return false; }
  void await_suspend(handle_type) noexcept {}
  [[nodiscard]]
  int await_resume() { return 1; }
};

template <class Await>
struct check_warning_promise {
  coro<check_warning_promise> get_return_object();
  Await initial_suspend();
  Await final_suspend();
  Await yield_value(int);
  void return_void();
  void unhandled_exception();
};


coro<check_warning_promise<awaitable_no_unused_warn>>
test_no_unused_warning() {
  co_await awaitable_no_unused_warn();
  co_yield 42;
}

coro<check_warning_promise<awaitable_unused_warn>>
test_unused_warning() {
  co_await awaitable_unused_warn(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
  co_yield 42; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
}

struct missing_await_ready {
  void await_suspend(std::experimental::coroutine_handle<>);
  void await_resume();
};
struct missing_await_suspend {
  bool await_ready();
  void await_resume();
};
struct missing_await_resume {
  bool await_ready();
  void await_suspend(std::experimental::coroutine_handle<>);
};

void test_missing_awaitable_members() {
  co_await missing_await_ready{}; // expected-error {{no member named 'await_ready' in 'missing_await_ready'}}
  co_await missing_await_suspend{}; // expected-error {{no member named 'await_suspend' in 'missing_await_suspend'}}
  co_await missing_await_resume{}; // expected-error {{no member named 'await_resume' in 'missing_await_resume'}}
}