/
SemaCoroutine.cpp
1592 lines (1364 loc) · 57.8 KB
/
SemaCoroutine.cpp
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
//===-- SemaCoroutine.cpp - Semantic Analysis for Coroutines --------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for C++ Coroutines.
//
// This file contains references to sections of the Coroutines TS, which
// can be found at http://wg21.link/coroutines.
//
//===----------------------------------------------------------------------===//
#include "CoroutineStmtBuilder.h"
#include "clang/AST/ASTLambda.h"
#include "clang/AST/Decl.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/StmtCXX.h"
#include "clang/Basic/Builtins.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Overload.h"
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/SemaInternal.h"
using namespace clang;
using namespace sema;
static LookupResult lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
SourceLocation Loc, bool &Res) {
DeclarationName DN = S.PP.getIdentifierInfo(Name);
LookupResult LR(S, DN, Loc, Sema::LookupMemberName);
// Suppress diagnostics when a private member is selected. The same warnings
// will be produced again when building the call.
LR.suppressDiagnostics();
Res = S.LookupQualifiedName(LR, RD);
return LR;
}
static bool lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
SourceLocation Loc) {
bool Res;
lookupMember(S, Name, RD, Loc, Res);
return Res;
}
/// Look up the std::coroutine_traits<...>::promise_type for the given
/// function type.
static QualType lookupPromiseType(Sema &S, const FunctionDecl *FD,
SourceLocation KwLoc) {
const FunctionProtoType *FnType = FD->getType()->castAs<FunctionProtoType>();
const SourceLocation FuncLoc = FD->getLocation();
// FIXME: Cache std::coroutine_traits once we've found it.
NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace();
if (!StdExp) {
S.Diag(KwLoc, diag::err_implied_coroutine_type_not_found)
<< "std::experimental::coroutine_traits";
return QualType();
}
ClassTemplateDecl *CoroTraits = S.lookupCoroutineTraits(KwLoc, FuncLoc);
if (!CoroTraits) {
return QualType();
}
// Form template argument list for coroutine_traits<R, P1, P2, ...> according
// to [dcl.fct.def.coroutine]3
TemplateArgumentListInfo Args(KwLoc, KwLoc);
auto AddArg = [&](QualType T) {
Args.addArgument(TemplateArgumentLoc(
TemplateArgument(T), S.Context.getTrivialTypeSourceInfo(T, KwLoc)));
};
AddArg(FnType->getReturnType());
// If the function is a non-static member function, add the type
// of the implicit object parameter before the formal parameters.
if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
if (MD->isInstance()) {
// [over.match.funcs]4
// For non-static member functions, the type of the implicit object
// parameter is
// -- "lvalue reference to cv X" for functions declared without a
// ref-qualifier or with the & ref-qualifier
// -- "rvalue reference to cv X" for functions declared with the &&
// ref-qualifier
QualType T = MD->getThisType()->castAs<PointerType>()->getPointeeType();
T = FnType->getRefQualifier() == RQ_RValue
? S.Context.getRValueReferenceType(T)
: S.Context.getLValueReferenceType(T, /*SpelledAsLValue*/ true);
AddArg(T);
}
}
for (QualType T : FnType->getParamTypes())
AddArg(T);
// Build the template-id.
QualType CoroTrait =
S.CheckTemplateIdType(TemplateName(CoroTraits), KwLoc, Args);
if (CoroTrait.isNull())
return QualType();
if (S.RequireCompleteType(KwLoc, CoroTrait,
diag::err_coroutine_type_missing_specialization))
return QualType();
auto *RD = CoroTrait->getAsCXXRecordDecl();
assert(RD && "specialization of class template is not a class?");
// Look up the ::promise_type member.
LookupResult R(S, &S.PP.getIdentifierTable().get("promise_type"), KwLoc,
Sema::LookupOrdinaryName);
S.LookupQualifiedName(R, RD);
auto *Promise = R.getAsSingle<TypeDecl>();
if (!Promise) {
S.Diag(FuncLoc,
diag::err_implied_std_coroutine_traits_promise_type_not_found)
<< RD;
return QualType();
}
// The promise type is required to be a class type.
QualType PromiseType = S.Context.getTypeDeclType(Promise);
auto buildElaboratedType = [&]() {
auto *NNS = NestedNameSpecifier::Create(S.Context, nullptr, StdExp);
NNS = NestedNameSpecifier::Create(S.Context, NNS, false,
CoroTrait.getTypePtr());
return S.Context.getElaboratedType(ETK_None, NNS, PromiseType);
};
if (!PromiseType->getAsCXXRecordDecl()) {
S.Diag(FuncLoc,
diag::err_implied_std_coroutine_traits_promise_type_not_class)
<< buildElaboratedType();
return QualType();
}
if (S.RequireCompleteType(FuncLoc, buildElaboratedType(),
diag::err_coroutine_promise_type_incomplete))
return QualType();
return PromiseType;
}
/// Look up the std::experimental::coroutine_handle<PromiseType>.
static QualType lookupCoroutineHandleType(Sema &S, QualType PromiseType,
SourceLocation Loc) {
if (PromiseType.isNull())
return QualType();
NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace();
assert(StdExp && "Should already be diagnosed");
LookupResult Result(S, &S.PP.getIdentifierTable().get("coroutine_handle"),
Loc, Sema::LookupOrdinaryName);
if (!S.LookupQualifiedName(Result, StdExp)) {
S.Diag(Loc, diag::err_implied_coroutine_type_not_found)
<< "std::experimental::coroutine_handle";
return QualType();
}
ClassTemplateDecl *CoroHandle = Result.getAsSingle<ClassTemplateDecl>();
if (!CoroHandle) {
Result.suppressDiagnostics();
// We found something weird. Complain about the first thing we found.
NamedDecl *Found = *Result.begin();
S.Diag(Found->getLocation(), diag::err_malformed_std_coroutine_handle);
return QualType();
}
// Form template argument list for coroutine_handle<Promise>.
TemplateArgumentListInfo Args(Loc, Loc);
Args.addArgument(TemplateArgumentLoc(
TemplateArgument(PromiseType),
S.Context.getTrivialTypeSourceInfo(PromiseType, Loc)));
// Build the template-id.
QualType CoroHandleType =
S.CheckTemplateIdType(TemplateName(CoroHandle), Loc, Args);
if (CoroHandleType.isNull())
return QualType();
if (S.RequireCompleteType(Loc, CoroHandleType,
diag::err_coroutine_type_missing_specialization))
return QualType();
return CoroHandleType;
}
static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
StringRef Keyword) {
// [expr.await]p2 dictates that 'co_await' and 'co_yield' must be used within
// a function body.
// FIXME: This also covers [expr.await]p2: "An await-expression shall not
// appear in a default argument." But the diagnostic QoI here could be
// improved to inform the user that default arguments specifically are not
// allowed.
auto *FD = dyn_cast<FunctionDecl>(S.CurContext);
if (!FD) {
S.Diag(Loc, isa<ObjCMethodDecl>(S.CurContext)
? diag::err_coroutine_objc_method
: diag::err_coroutine_outside_function) << Keyword;
return false;
}
// An enumeration for mapping the diagnostic type to the correct diagnostic
// selection index.
enum InvalidFuncDiag {
DiagCtor = 0,
DiagDtor,
DiagMain,
DiagConstexpr,
DiagAutoRet,
DiagVarargs,
DiagConsteval,
};
bool Diagnosed = false;
auto DiagInvalid = [&](InvalidFuncDiag ID) {
S.Diag(Loc, diag::err_coroutine_invalid_func_context) << ID << Keyword;
Diagnosed = true;
return false;
};
// Diagnose when a constructor, destructor
// or the function 'main' are declared as a coroutine.
auto *MD = dyn_cast<CXXMethodDecl>(FD);
// [class.ctor]p11: "A constructor shall not be a coroutine."
if (MD && isa<CXXConstructorDecl>(MD))
return DiagInvalid(DiagCtor);
// [class.dtor]p17: "A destructor shall not be a coroutine."
else if (MD && isa<CXXDestructorDecl>(MD))
return DiagInvalid(DiagDtor);
// [basic.start.main]p3: "The function main shall not be a coroutine."
else if (FD->isMain())
return DiagInvalid(DiagMain);
// Emit a diagnostics for each of the following conditions which is not met.
// [expr.const]p2: "An expression e is a core constant expression unless the
// evaluation of e [...] would evaluate one of the following expressions:
// [...] an await-expression [...] a yield-expression."
if (FD->isConstexpr())
DiagInvalid(FD->isConsteval() ? DiagConsteval : DiagConstexpr);
// [dcl.spec.auto]p15: "A function declared with a return type that uses a
// placeholder type shall not be a coroutine."
if (FD->getReturnType()->isUndeducedType())
DiagInvalid(DiagAutoRet);
// [dcl.fct.def.coroutine]p1: "The parameter-declaration-clause of the
// coroutine shall not terminate with an ellipsis that is not part of a
// parameter-declaration."
if (FD->isVariadic())
DiagInvalid(DiagVarargs);
return !Diagnosed;
}
static ExprResult buildOperatorCoawaitLookupExpr(Sema &SemaRef, Scope *S,
SourceLocation Loc) {
DeclarationName OpName =
SemaRef.Context.DeclarationNames.getCXXOperatorName(OO_Coawait);
LookupResult Operators(SemaRef, OpName, SourceLocation(),
Sema::LookupOperatorName);
SemaRef.LookupName(Operators, S);
assert(!Operators.isAmbiguous() && "Operator lookup cannot be ambiguous");
const auto &Functions = Operators.asUnresolvedSet();
bool IsOverloaded =
Functions.size() > 1 ||
(Functions.size() == 1 && isa<FunctionTemplateDecl>(*Functions.begin()));
Expr *CoawaitOp = UnresolvedLookupExpr::Create(
SemaRef.Context, /*NamingClass*/ nullptr, NestedNameSpecifierLoc(),
DeclarationNameInfo(OpName, Loc), /*RequiresADL*/ true, IsOverloaded,
Functions.begin(), Functions.end());
assert(CoawaitOp);
return CoawaitOp;
}
/// Build a call to 'operator co_await' if there is a suitable operator for
/// the given expression.
static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, SourceLocation Loc,
Expr *E,
UnresolvedLookupExpr *Lookup) {
UnresolvedSet<16> Functions;
Functions.append(Lookup->decls_begin(), Lookup->decls_end());
return SemaRef.CreateOverloadedUnaryOp(Loc, UO_Coawait, Functions, E);
}
static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, Scope *S,
SourceLocation Loc, Expr *E) {
ExprResult R = buildOperatorCoawaitLookupExpr(SemaRef, S, Loc);
if (R.isInvalid())
return ExprError();
return buildOperatorCoawaitCall(SemaRef, Loc, E,
cast<UnresolvedLookupExpr>(R.get()));
}
static Expr *buildBuiltinCall(Sema &S, SourceLocation Loc, Builtin::ID Id,
MultiExprArg CallArgs) {
StringRef Name = S.Context.BuiltinInfo.getName(Id);
LookupResult R(S, &S.Context.Idents.get(Name), Loc, Sema::LookupOrdinaryName);
S.LookupName(R, S.TUScope, /*AllowBuiltinCreation=*/true);
auto *BuiltInDecl = R.getAsSingle<FunctionDecl>();
assert(BuiltInDecl && "failed to find builtin declaration");
ExprResult DeclRef =
S.BuildDeclRefExpr(BuiltInDecl, BuiltInDecl->getType(), VK_LValue, Loc);
assert(DeclRef.isUsable() && "Builtin reference cannot fail");
ExprResult Call =
S.BuildCallExpr(/*Scope=*/nullptr, DeclRef.get(), Loc, CallArgs, Loc);
assert(!Call.isInvalid() && "Call to builtin cannot fail!");
return Call.get();
}
static ExprResult buildCoroutineHandle(Sema &S, QualType PromiseType,
SourceLocation Loc) {
QualType CoroHandleType = lookupCoroutineHandleType(S, PromiseType, Loc);
if (CoroHandleType.isNull())
return ExprError();
DeclContext *LookupCtx = S.computeDeclContext(CoroHandleType);
LookupResult Found(S, &S.PP.getIdentifierTable().get("from_address"), Loc,
Sema::LookupOrdinaryName);
if (!S.LookupQualifiedName(Found, LookupCtx)) {
S.Diag(Loc, diag::err_coroutine_handle_missing_member)
<< "from_address";
return ExprError();
}
Expr *FramePtr =
buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_frame, {});
CXXScopeSpec SS;
ExprResult FromAddr =
S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
if (FromAddr.isInvalid())
return ExprError();
return S.BuildCallExpr(nullptr, FromAddr.get(), Loc, FramePtr, Loc);
}
struct ReadySuspendResumeResult {
enum AwaitCallType { ACT_Ready, ACT_Suspend, ACT_Resume };
Expr *Results[3];
OpaqueValueExpr *OpaqueValue;
bool IsInvalid;
};
static ExprResult buildMemberCall(Sema &S, Expr *Base, SourceLocation Loc,
StringRef Name, MultiExprArg Args) {
DeclarationNameInfo NameInfo(&S.PP.getIdentifierTable().get(Name), Loc);
// FIXME: Fix BuildMemberReferenceExpr to take a const CXXScopeSpec&.
CXXScopeSpec SS;
ExprResult Result = S.BuildMemberReferenceExpr(
Base, Base->getType(), Loc, /*IsPtr=*/false, SS,
SourceLocation(), nullptr, NameInfo, /*TemplateArgs=*/nullptr,
/*Scope=*/nullptr);
if (Result.isInvalid())
return ExprError();
// We meant exactly what we asked for. No need for typo correction.
if (auto *TE = dyn_cast<TypoExpr>(Result.get())) {
S.clearDelayedTypo(TE);
S.Diag(Loc, diag::err_no_member)
<< NameInfo.getName() << Base->getType()->getAsCXXRecordDecl()
<< Base->getSourceRange();
return ExprError();
}
return S.BuildCallExpr(nullptr, Result.get(), Loc, Args, Loc, nullptr);
}
// See if return type is coroutine-handle and if so, invoke builtin coro-resume
// on its address. This is to enable experimental support for coroutine-handle
// returning await_suspend that results in a guaranteed tail call to the target
// coroutine.
static Expr *maybeTailCall(Sema &S, QualType RetType, Expr *E,
SourceLocation Loc) {
if (RetType->isReferenceType())
return nullptr;
Type const *T = RetType.getTypePtr();
if (!T->isClassType() && !T->isStructureType())
return nullptr;
// FIXME: Add convertability check to coroutine_handle<>. Possibly via
// EvaluateBinaryTypeTrait(BTT_IsConvertible, ...) which is at the moment
// a private function in SemaExprCXX.cpp
ExprResult AddressExpr = buildMemberCall(S, E, Loc, "address", None);
if (AddressExpr.isInvalid())
return nullptr;
Expr *JustAddress = AddressExpr.get();
// FIXME: Check that the type of AddressExpr is void*
return buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_resume,
JustAddress);
}
/// Build calls to await_ready, await_suspend, and await_resume for a co_await
/// expression.
static ReadySuspendResumeResult buildCoawaitCalls(Sema &S, VarDecl *CoroPromise,
SourceLocation Loc, Expr *E) {
OpaqueValueExpr *Operand = new (S.Context)
OpaqueValueExpr(Loc, E->getType(), VK_LValue, E->getObjectKind(), E);
// Assume invalid until we see otherwise.
ReadySuspendResumeResult Calls = {{}, Operand, /*IsInvalid=*/true};
ExprResult CoroHandleRes = buildCoroutineHandle(S, CoroPromise->getType(), Loc);
if (CoroHandleRes.isInvalid())
return Calls;
Expr *CoroHandle = CoroHandleRes.get();
const StringRef Funcs[] = {"await_ready", "await_suspend", "await_resume"};
MultiExprArg Args[] = {None, CoroHandle, None};
for (size_t I = 0, N = llvm::array_lengthof(Funcs); I != N; ++I) {
ExprResult Result = buildMemberCall(S, Operand, Loc, Funcs[I], Args[I]);
if (Result.isInvalid())
return Calls;
Calls.Results[I] = Result.get();
}
// Assume the calls are valid; all further checking should make them invalid.
Calls.IsInvalid = false;
using ACT = ReadySuspendResumeResult::AwaitCallType;
CallExpr *AwaitReady = cast<CallExpr>(Calls.Results[ACT::ACT_Ready]);
if (!AwaitReady->getType()->isDependentType()) {
// [expr.await]p3 [...]
// — await-ready is the expression e.await_ready(), contextually converted
// to bool.
ExprResult Conv = S.PerformContextuallyConvertToBool(AwaitReady);
if (Conv.isInvalid()) {
S.Diag(AwaitReady->getDirectCallee()->getBeginLoc(),
diag::note_await_ready_no_bool_conversion);
S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
<< AwaitReady->getDirectCallee() << E->getSourceRange();
Calls.IsInvalid = true;
}
Calls.Results[ACT::ACT_Ready] = Conv.get();
}
CallExpr *AwaitSuspend = cast<CallExpr>(Calls.Results[ACT::ACT_Suspend]);
if (!AwaitSuspend->getType()->isDependentType()) {
// [expr.await]p3 [...]
// - await-suspend is the expression e.await_suspend(h), which shall be
// a prvalue of type void or bool.
QualType RetType = AwaitSuspend->getCallReturnType(S.Context);
// Experimental support for coroutine_handle returning await_suspend.
if (Expr *TailCallSuspend = maybeTailCall(S, RetType, AwaitSuspend, Loc))
Calls.Results[ACT::ACT_Suspend] = TailCallSuspend;
else {
// non-class prvalues always have cv-unqualified types
if (RetType->isReferenceType() ||
(!RetType->isBooleanType() && !RetType->isVoidType())) {
S.Diag(AwaitSuspend->getCalleeDecl()->getLocation(),
diag::err_await_suspend_invalid_return_type)
<< RetType;
S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
<< AwaitSuspend->getDirectCallee();
Calls.IsInvalid = true;
}
}
}
return Calls;
}
static ExprResult buildPromiseCall(Sema &S, VarDecl *Promise,
SourceLocation Loc, StringRef Name,
MultiExprArg Args) {
// Form a reference to the promise.
ExprResult PromiseRef = S.BuildDeclRefExpr(
Promise, Promise->getType().getNonReferenceType(), VK_LValue, Loc);
if (PromiseRef.isInvalid())
return ExprError();
return buildMemberCall(S, PromiseRef.get(), Loc, Name, Args);
}
VarDecl *Sema::buildCoroutinePromise(SourceLocation Loc) {
assert(isa<FunctionDecl>(CurContext) && "not in a function scope");
auto *FD = cast<FunctionDecl>(CurContext);
bool IsThisDependentType = [&] {
if (auto *MD = dyn_cast_or_null<CXXMethodDecl>(FD))
return MD->isInstance() && MD->getThisType()->isDependentType();
else
return false;
}();
QualType T = FD->getType()->isDependentType() || IsThisDependentType
? Context.DependentTy
: lookupPromiseType(*this, FD, Loc);
if (T.isNull())
return nullptr;
auto *VD = VarDecl::Create(Context, FD, FD->getLocation(), FD->getLocation(),
&PP.getIdentifierTable().get("__promise"), T,
Context.getTrivialTypeSourceInfo(T, Loc), SC_None);
CheckVariableDeclarationType(VD);
if (VD->isInvalidDecl())
return nullptr;
auto *ScopeInfo = getCurFunction();
// Build a list of arguments, based on the coroutine functions arguments,
// that will be passed to the promise type's constructor.
llvm::SmallVector<Expr *, 4> CtorArgExprs;
// Add implicit object parameter.
if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
if (MD->isInstance() && !isLambdaCallOperator(MD)) {
ExprResult ThisExpr = ActOnCXXThis(Loc);
if (ThisExpr.isInvalid())
return nullptr;
ThisExpr = CreateBuiltinUnaryOp(Loc, UO_Deref, ThisExpr.get());
if (ThisExpr.isInvalid())
return nullptr;
CtorArgExprs.push_back(ThisExpr.get());
}
}
auto &Moves = ScopeInfo->CoroutineParameterMoves;
for (auto *PD : FD->parameters()) {
if (PD->getType()->isDependentType())
continue;
auto RefExpr = ExprEmpty();
auto Move = Moves.find(PD);
assert(Move != Moves.end() &&
"Coroutine function parameter not inserted into move map");
// If a reference to the function parameter exists in the coroutine
// frame, use that reference.
auto *MoveDecl =
cast<VarDecl>(cast<DeclStmt>(Move->second)->getSingleDecl());
RefExpr =
BuildDeclRefExpr(MoveDecl, MoveDecl->getType().getNonReferenceType(),
ExprValueKind::VK_LValue, FD->getLocation());
if (RefExpr.isInvalid())
return nullptr;
CtorArgExprs.push_back(RefExpr.get());
}
// Create an initialization sequence for the promise type using the
// constructor arguments, wrapped in a parenthesized list expression.
Expr *PLE = ParenListExpr::Create(Context, FD->getLocation(),
CtorArgExprs, FD->getLocation());
InitializedEntity Entity = InitializedEntity::InitializeVariable(VD);
InitializationKind Kind = InitializationKind::CreateForInit(
VD->getLocation(), /*DirectInit=*/true, PLE);
InitializationSequence InitSeq(*this, Entity, Kind, CtorArgExprs,
/*TopLevelOfInitList=*/false,
/*TreatUnavailableAsInvalid=*/false);
// Attempt to initialize the promise type with the arguments.
// If that fails, fall back to the promise type's default constructor.
if (InitSeq) {
ExprResult Result = InitSeq.Perform(*this, Entity, Kind, CtorArgExprs);
if (Result.isInvalid()) {
VD->setInvalidDecl();
} else if (Result.get()) {
VD->setInit(MaybeCreateExprWithCleanups(Result.get()));
VD->setInitStyle(VarDecl::CallInit);
CheckCompleteVariableDeclaration(VD);
}
} else
ActOnUninitializedDecl(VD);
FD->addDecl(VD);
return VD;
}
/// Check that this is a context in which a coroutine suspension can appear.
static FunctionScopeInfo *checkCoroutineContext(Sema &S, SourceLocation Loc,
StringRef Keyword,
bool IsImplicit = false) {
if (!isValidCoroutineContext(S, Loc, Keyword))
return nullptr;
assert(isa<FunctionDecl>(S.CurContext) && "not in a function scope");
auto *ScopeInfo = S.getCurFunction();
assert(ScopeInfo && "missing function scope for function");
if (ScopeInfo->FirstCoroutineStmtLoc.isInvalid() && !IsImplicit)
ScopeInfo->setFirstCoroutineStmt(Loc, Keyword);
if (ScopeInfo->CoroutinePromise)
return ScopeInfo;
if (!S.buildCoroutineParameterMoves(Loc))
return nullptr;
ScopeInfo->CoroutinePromise = S.buildCoroutinePromise(Loc);
if (!ScopeInfo->CoroutinePromise)
return nullptr;
return ScopeInfo;
}
bool Sema::ActOnCoroutineBodyStart(Scope *SC, SourceLocation KWLoc,
StringRef Keyword) {
if (!checkCoroutineContext(*this, KWLoc, Keyword))
return false;
auto *ScopeInfo = getCurFunction();
assert(ScopeInfo->CoroutinePromise);
// If we have existing coroutine statements then we have already built
// the initial and final suspend points.
if (!ScopeInfo->NeedsCoroutineSuspends)
return true;
ScopeInfo->setNeedsCoroutineSuspends(false);
auto *Fn = cast<FunctionDecl>(CurContext);
SourceLocation Loc = Fn->getLocation();
// Build the initial suspend point
auto buildSuspends = [&](StringRef Name) mutable -> StmtResult {
ExprResult Suspend =
buildPromiseCall(*this, ScopeInfo->CoroutinePromise, Loc, Name, None);
if (Suspend.isInvalid())
return StmtError();
Suspend = buildOperatorCoawaitCall(*this, SC, Loc, Suspend.get());
if (Suspend.isInvalid())
return StmtError();
Suspend = BuildResolvedCoawaitExpr(Loc, Suspend.get(),
/*IsImplicit*/ true);
Suspend = ActOnFinishFullExpr(Suspend.get(), /*DiscardedValue*/ false);
if (Suspend.isInvalid()) {
Diag(Loc, diag::note_coroutine_promise_suspend_implicitly_required)
<< ((Name == "initial_suspend") ? 0 : 1);
Diag(KWLoc, diag::note_declared_coroutine_here) << Keyword;
return StmtError();
}
return cast<Stmt>(Suspend.get());
};
StmtResult InitSuspend = buildSuspends("initial_suspend");
if (InitSuspend.isInvalid())
return true;
StmtResult FinalSuspend = buildSuspends("final_suspend");
if (FinalSuspend.isInvalid())
return true;
ScopeInfo->setCoroutineSuspends(InitSuspend.get(), FinalSuspend.get());
return true;
}
// Recursively walks up the scope hierarchy until either a 'catch' or a function
// scope is found, whichever comes first.
static bool isWithinCatchScope(Scope *S) {
// 'co_await' and 'co_yield' keywords are disallowed within catch blocks, but
// lambdas that use 'co_await' are allowed. The loop below ends when a
// function scope is found in order to ensure the following behavior:
//
// void foo() { // <- function scope
// try { //
// co_await x; // <- 'co_await' is OK within a function scope
// } catch { // <- catch scope
// co_await x; // <- 'co_await' is not OK within a catch scope
// []() { // <- function scope
// co_await x; // <- 'co_await' is OK within a function scope
// }();
// }
// }
while (S && !(S->getFlags() & Scope::FnScope)) {
if (S->getFlags() & Scope::CatchScope)
return true;
S = S->getParent();
}
return false;
}
// [expr.await]p2, emphasis added: "An await-expression shall appear only in
// a *potentially evaluated* expression within the compound-statement of a
// function-body *outside of a handler* [...] A context within a function
// where an await-expression can appear is called a suspension context of the
// function."
static void checkSuspensionContext(Sema &S, SourceLocation Loc,
StringRef Keyword) {
// First emphasis of [expr.await]p2: must be a potentially evaluated context.
// That is, 'co_await' and 'co_yield' cannot appear in subexpressions of
// \c sizeof.
if (S.isUnevaluatedContext())
S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword;
// Second emphasis of [expr.await]p2: must be outside of an exception handler.
if (isWithinCatchScope(S.getCurScope()))
S.Diag(Loc, diag::err_coroutine_within_handler) << Keyword;
}
ExprResult Sema::ActOnCoawaitExpr(Scope *S, SourceLocation Loc, Expr *E) {
if (!ActOnCoroutineBodyStart(S, Loc, "co_await")) {
CorrectDelayedTyposInExpr(E);
return ExprError();
}
checkSuspensionContext(*this, Loc, "co_await");
if (E->getType()->isPlaceholderType()) {
ExprResult R = CheckPlaceholderExpr(E);
if (R.isInvalid()) return ExprError();
E = R.get();
}
ExprResult Lookup = buildOperatorCoawaitLookupExpr(*this, S, Loc);
if (Lookup.isInvalid())
return ExprError();
return BuildUnresolvedCoawaitExpr(Loc, E,
cast<UnresolvedLookupExpr>(Lookup.get()));
}
ExprResult Sema::BuildUnresolvedCoawaitExpr(SourceLocation Loc, Expr *E,
UnresolvedLookupExpr *Lookup) {
auto *FSI = checkCoroutineContext(*this, Loc, "co_await");
if (!FSI)
return ExprError();
if (E->getType()->isPlaceholderType()) {
ExprResult R = CheckPlaceholderExpr(E);
if (R.isInvalid())
return ExprError();
E = R.get();
}
auto *Promise = FSI->CoroutinePromise;
if (Promise->getType()->isDependentType()) {
Expr *Res =
new (Context) DependentCoawaitExpr(Loc, Context.DependentTy, E, Lookup);
return Res;
}
auto *RD = Promise->getType()->getAsCXXRecordDecl();
if (lookupMember(*this, "await_transform", RD, Loc)) {
ExprResult R = buildPromiseCall(*this, Promise, Loc, "await_transform", E);
if (R.isInvalid()) {
Diag(Loc,
diag::note_coroutine_promise_implicit_await_transform_required_here)
<< E->getSourceRange();
return ExprError();
}
E = R.get();
}
ExprResult Awaitable = buildOperatorCoawaitCall(*this, Loc, E, Lookup);
if (Awaitable.isInvalid())
return ExprError();
return BuildResolvedCoawaitExpr(Loc, Awaitable.get());
}
ExprResult Sema::BuildResolvedCoawaitExpr(SourceLocation Loc, Expr *E,
bool IsImplicit) {
auto *Coroutine = checkCoroutineContext(*this, Loc, "co_await", IsImplicit);
if (!Coroutine)
return ExprError();
if (E->getType()->isPlaceholderType()) {
ExprResult R = CheckPlaceholderExpr(E);
if (R.isInvalid()) return ExprError();
E = R.get();
}
if (E->getType()->isDependentType()) {
Expr *Res = new (Context)
CoawaitExpr(Loc, Context.DependentTy, E, IsImplicit);
return Res;
}
// If the expression is a temporary, materialize it as an lvalue so that we
// can use it multiple times.
if (E->getValueKind() == VK_RValue)
E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
// The location of the `co_await` token cannot be used when constructing
// the member call expressions since it's before the location of `Expr`, which
// is used as the start of the member call expression.
SourceLocation CallLoc = E->getExprLoc();
// Build the await_ready, await_suspend, await_resume calls.
ReadySuspendResumeResult RSS =
buildCoawaitCalls(*this, Coroutine->CoroutinePromise, CallLoc, E);
if (RSS.IsInvalid)
return ExprError();
Expr *Res =
new (Context) CoawaitExpr(Loc, E, RSS.Results[0], RSS.Results[1],
RSS.Results[2], RSS.OpaqueValue, IsImplicit);
return Res;
}
ExprResult Sema::ActOnCoyieldExpr(Scope *S, SourceLocation Loc, Expr *E) {
if (!ActOnCoroutineBodyStart(S, Loc, "co_yield")) {
CorrectDelayedTyposInExpr(E);
return ExprError();
}
checkSuspensionContext(*this, Loc, "co_yield");
// Build yield_value call.
ExprResult Awaitable = buildPromiseCall(
*this, getCurFunction()->CoroutinePromise, Loc, "yield_value", E);
if (Awaitable.isInvalid())
return ExprError();
// Build 'operator co_await' call.
Awaitable = buildOperatorCoawaitCall(*this, S, Loc, Awaitable.get());
if (Awaitable.isInvalid())
return ExprError();
return BuildCoyieldExpr(Loc, Awaitable.get());
}
ExprResult Sema::BuildCoyieldExpr(SourceLocation Loc, Expr *E) {
auto *Coroutine = checkCoroutineContext(*this, Loc, "co_yield");
if (!Coroutine)
return ExprError();
if (E->getType()->isPlaceholderType()) {
ExprResult R = CheckPlaceholderExpr(E);
if (R.isInvalid()) return ExprError();
E = R.get();
}
if (E->getType()->isDependentType()) {
Expr *Res = new (Context) CoyieldExpr(Loc, Context.DependentTy, E);
return Res;
}
// If the expression is a temporary, materialize it as an lvalue so that we
// can use it multiple times.
if (E->getValueKind() == VK_RValue)
E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
// Build the await_ready, await_suspend, await_resume calls.
ReadySuspendResumeResult RSS =
buildCoawaitCalls(*this, Coroutine->CoroutinePromise, Loc, E);
if (RSS.IsInvalid)
return ExprError();
Expr *Res =
new (Context) CoyieldExpr(Loc, E, RSS.Results[0], RSS.Results[1],
RSS.Results[2], RSS.OpaqueValue);
return Res;
}
StmtResult Sema::ActOnCoreturnStmt(Scope *S, SourceLocation Loc, Expr *E) {
if (!ActOnCoroutineBodyStart(S, Loc, "co_return")) {
CorrectDelayedTyposInExpr(E);
return StmtError();
}
return BuildCoreturnStmt(Loc, E);
}
StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E,
bool IsImplicit) {
auto *FSI = checkCoroutineContext(*this, Loc, "co_return", IsImplicit);
if (!FSI)
return StmtError();
if (E && E->getType()->isPlaceholderType() &&
!E->getType()->isSpecificPlaceholderType(BuiltinType::Overload)) {
ExprResult R = CheckPlaceholderExpr(E);
if (R.isInvalid()) return StmtError();
E = R.get();
}
// Move the return value if we can
if (E) {
auto NRVOCandidate = this->getCopyElisionCandidate(E->getType(), E, CES_AsIfByStdMove);
if (NRVOCandidate) {
InitializedEntity Entity =
InitializedEntity::InitializeResult(Loc, E->getType(), NRVOCandidate);
ExprResult MoveResult = this->PerformMoveOrCopyInitialization(
Entity, NRVOCandidate, E->getType(), E);
if (MoveResult.get())
E = MoveResult.get();
}
}
// FIXME: If the operand is a reference to a variable that's about to go out
// of scope, we should treat the operand as an xvalue for this overload
// resolution.
VarDecl *Promise = FSI->CoroutinePromise;
ExprResult PC;
if (E && (isa<InitListExpr>(E) || !E->getType()->isVoidType())) {
PC = buildPromiseCall(*this, Promise, Loc, "return_value", E);
} else {
E = MakeFullDiscardedValueExpr(E).get();
PC = buildPromiseCall(*this, Promise, Loc, "return_void", None);
}
if (PC.isInvalid())
return StmtError();
Expr *PCE = ActOnFinishFullExpr(PC.get(), /*DiscardedValue*/ false).get();
Stmt *Res = new (Context) CoreturnStmt(Loc, E, PCE, IsImplicit);
return Res;
}
/// Look up the std::nothrow object.
static Expr *buildStdNoThrowDeclRef(Sema &S, SourceLocation Loc) {
NamespaceDecl *Std = S.getStdNamespace();
assert(Std && "Should already be diagnosed");
LookupResult Result(S, &S.PP.getIdentifierTable().get("nothrow"), Loc,
Sema::LookupOrdinaryName);
if (!S.LookupQualifiedName(Result, Std)) {
// FIXME: <experimental/coroutine> should have been included already.
// If we require it to include <new> then this diagnostic is no longer
// needed.
S.Diag(Loc, diag::err_implicit_coroutine_std_nothrow_type_not_found);
return nullptr;
}
auto *VD = Result.getAsSingle<VarDecl>();
if (!VD) {
Result.suppressDiagnostics();
// We found something weird. Complain about the first thing we found.
NamedDecl *Found = *Result.begin();
S.Diag(Found->getLocation(), diag::err_malformed_std_nothrow);
return nullptr;
}
ExprResult DR = S.BuildDeclRefExpr(VD, VD->getType(), VK_LValue, Loc);
if (DR.isInvalid())
return nullptr;
return DR.get();
}
// Find an appropriate delete for the promise.
static FunctionDecl *findDeleteForPromise(Sema &S, SourceLocation Loc,
QualType PromiseType) {
FunctionDecl *OperatorDelete = nullptr;
DeclarationName DeleteName =
S.Context.DeclarationNames.getCXXOperatorName(OO_Delete);
auto *PointeeRD = PromiseType->getAsCXXRecordDecl();
assert(PointeeRD && "PromiseType must be a CxxRecordDecl type");
if (S.FindDeallocationFunction(Loc, PointeeRD, DeleteName, OperatorDelete))
return nullptr;
if (!OperatorDelete) {
// Look for a global declaration.
const bool CanProvideSize = S.isCompleteType(Loc, PromiseType);
const bool Overaligned = false;
OperatorDelete = S.FindUsualDeallocationFunction(Loc, CanProvideSize,
Overaligned, DeleteName);
}
S.MarkFunctionReferenced(Loc, OperatorDelete);
return OperatorDelete;
}
void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body) {
FunctionScopeInfo *Fn = getCurFunction();
assert(Fn && Fn->isCoroutine() && "not a coroutine");
if (!Body) {
assert(FD->isInvalidDecl() &&
"a null body is only allowed for invalid declarations");
return;
}
// We have a function that uses coroutine keywords, but we failed to build
// the promise type.
if (!Fn->CoroutinePromise)
return FD->setInvalidDecl();
if (isa<CoroutineBodyStmt>(Body)) {
// Nothing todo. the body is already a transformed coroutine body statement.
return;
}
// Coroutines [stmt.return]p1:
// A return statement shall not appear in a coroutine.
if (Fn->FirstReturnLoc.isValid()) {
assert(Fn->FirstCoroutineStmtLoc.isValid() &&
"first coroutine location not set");
Diag(Fn->FirstReturnLoc, diag::err_return_in_coroutine);
Diag(Fn->FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
<< Fn->getFirstCoroutineStmtKeyword();
}
CoroutineStmtBuilder Builder(*this, *FD, *Fn, Body);
if (Builder.isInvalid() || !Builder.buildStatements())
return FD->setInvalidDecl();
// Build body for the coroutine wrapper statement.
Body = CoroutineBodyStmt::Create(Context, Builder);
}
CoroutineStmtBuilder::CoroutineStmtBuilder(Sema &S, FunctionDecl &FD,
sema::FunctionScopeInfo &Fn,
Stmt *Body)
: S(S), FD(FD), Fn(Fn), Loc(FD.getLocation()),
IsPromiseDependentType(
!Fn.CoroutinePromise ||
Fn.CoroutinePromise->getType()->isDependentType()) {
this->Body = Body;