1 //===--- SemaCoroutines.cpp - Semantic Analysis for Coroutines ------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements semantic analysis for C++ Coroutines.
12 // This file contains references to sections of the Coroutines TS, which
13 // can be found at http://wg21.link/coroutines.
15 //===----------------------------------------------------------------------===//
17 #include "CoroutineStmtBuilder.h"
18 #include "clang/AST/ASTLambda.h"
19 #include "clang/AST/Decl.h"
20 #include "clang/AST/ExprCXX.h"
21 #include "clang/AST/StmtCXX.h"
22 #include "clang/Lex/Preprocessor.h"
23 #include "clang/Sema/Initialization.h"
24 #include "clang/Sema/Overload.h"
25 #include "clang/Sema/ScopeInfo.h"
26 #include "clang/Sema/SemaInternal.h"
28 using namespace clang;
31 static LookupResult lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
32 SourceLocation Loc, bool &Res) {
33 DeclarationName DN = S.PP.getIdentifierInfo(Name);
34 LookupResult LR(S, DN, Loc, Sema::LookupMemberName);
35 // Suppress diagnostics when a private member is selected. The same warnings
36 // will be produced again when building the call.
37 LR.suppressDiagnostics();
38 Res = S.LookupQualifiedName(LR, RD);
42 static bool lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
45 lookupMember(S, Name, RD, Loc, Res);
49 /// Look up the std::coroutine_traits<...>::promise_type for the given
51 static QualType lookupPromiseType(Sema &S, const FunctionDecl *FD,
52 SourceLocation KwLoc) {
53 const FunctionProtoType *FnType = FD->getType()->castAs<FunctionProtoType>();
54 const SourceLocation FuncLoc = FD->getLocation();
55 // FIXME: Cache std::coroutine_traits once we've found it.
56 NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace();
58 S.Diag(KwLoc, diag::err_implied_coroutine_type_not_found)
59 << "std::experimental::coroutine_traits";
63 ClassTemplateDecl *CoroTraits = S.lookupCoroutineTraits(KwLoc, FuncLoc);
68 // Form template argument list for coroutine_traits<R, P1, P2, ...> according
69 // to [dcl.fct.def.coroutine]3
70 TemplateArgumentListInfo Args(KwLoc, KwLoc);
71 auto AddArg = [&](QualType T) {
72 Args.addArgument(TemplateArgumentLoc(
73 TemplateArgument(T), S.Context.getTrivialTypeSourceInfo(T, KwLoc)));
75 AddArg(FnType->getReturnType());
76 // If the function is a non-static member function, add the type
77 // of the implicit object parameter before the formal parameters.
78 if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
79 if (MD->isInstance()) {
80 // [over.match.funcs]4
81 // For non-static member functions, the type of the implicit object
83 // -- "lvalue reference to cv X" for functions declared without a
84 // ref-qualifier or with the & ref-qualifier
85 // -- "rvalue reference to cv X" for functions declared with the &&
87 QualType T = MD->getThisType()->getAs<PointerType>()->getPointeeType();
88 T = FnType->getRefQualifier() == RQ_RValue
89 ? S.Context.getRValueReferenceType(T)
90 : S.Context.getLValueReferenceType(T, /*SpelledAsLValue*/ true);
94 for (QualType T : FnType->getParamTypes())
97 // Build the template-id.
99 S.CheckTemplateIdType(TemplateName(CoroTraits), KwLoc, Args);
100 if (CoroTrait.isNull())
102 if (S.RequireCompleteType(KwLoc, CoroTrait,
103 diag::err_coroutine_type_missing_specialization))
106 auto *RD = CoroTrait->getAsCXXRecordDecl();
107 assert(RD && "specialization of class template is not a class?");
109 // Look up the ::promise_type member.
110 LookupResult R(S, &S.PP.getIdentifierTable().get("promise_type"), KwLoc,
111 Sema::LookupOrdinaryName);
112 S.LookupQualifiedName(R, RD);
113 auto *Promise = R.getAsSingle<TypeDecl>();
116 diag::err_implied_std_coroutine_traits_promise_type_not_found)
120 // The promise type is required to be a class type.
121 QualType PromiseType = S.Context.getTypeDeclType(Promise);
123 auto buildElaboratedType = [&]() {
124 auto *NNS = NestedNameSpecifier::Create(S.Context, nullptr, StdExp);
125 NNS = NestedNameSpecifier::Create(S.Context, NNS, false,
126 CoroTrait.getTypePtr());
127 return S.Context.getElaboratedType(ETK_None, NNS, PromiseType);
130 if (!PromiseType->getAsCXXRecordDecl()) {
132 diag::err_implied_std_coroutine_traits_promise_type_not_class)
133 << buildElaboratedType();
136 if (S.RequireCompleteType(FuncLoc, buildElaboratedType(),
137 diag::err_coroutine_promise_type_incomplete))
143 /// Look up the std::experimental::coroutine_handle<PromiseType>.
144 static QualType lookupCoroutineHandleType(Sema &S, QualType PromiseType,
145 SourceLocation Loc) {
146 if (PromiseType.isNull())
149 NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace();
150 assert(StdExp && "Should already be diagnosed");
152 LookupResult Result(S, &S.PP.getIdentifierTable().get("coroutine_handle"),
153 Loc, Sema::LookupOrdinaryName);
154 if (!S.LookupQualifiedName(Result, StdExp)) {
155 S.Diag(Loc, diag::err_implied_coroutine_type_not_found)
156 << "std::experimental::coroutine_handle";
160 ClassTemplateDecl *CoroHandle = Result.getAsSingle<ClassTemplateDecl>();
162 Result.suppressDiagnostics();
163 // We found something weird. Complain about the first thing we found.
164 NamedDecl *Found = *Result.begin();
165 S.Diag(Found->getLocation(), diag::err_malformed_std_coroutine_handle);
169 // Form template argument list for coroutine_handle<Promise>.
170 TemplateArgumentListInfo Args(Loc, Loc);
171 Args.addArgument(TemplateArgumentLoc(
172 TemplateArgument(PromiseType),
173 S.Context.getTrivialTypeSourceInfo(PromiseType, Loc)));
175 // Build the template-id.
176 QualType CoroHandleType =
177 S.CheckTemplateIdType(TemplateName(CoroHandle), Loc, Args);
178 if (CoroHandleType.isNull())
180 if (S.RequireCompleteType(Loc, CoroHandleType,
181 diag::err_coroutine_type_missing_specialization))
184 return CoroHandleType;
187 static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
189 // 'co_await' and 'co_yield' are not permitted in unevaluated operands,
190 // such as subexpressions of \c sizeof.
192 // [expr.await]p2, emphasis added: "An await-expression shall appear only in
193 // a *potentially evaluated* expression within the compound-statement of a
194 // function-body outside of a handler [...] A context within a function where
195 // an await-expression can appear is called a suspension context of the
196 // function." And per [expr.yield]p1: "A yield-expression shall appear only
197 // within a suspension context of a function."
198 if (S.isUnevaluatedContext()) {
199 S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword;
203 // Per [expr.await]p2, any other usage must be within a function.
204 // FIXME: This also covers [expr.await]p2: "An await-expression shall not
205 // appear in a default argument." But the diagnostic QoI here could be
206 // improved to inform the user that default arguments specifically are not
208 auto *FD = dyn_cast<FunctionDecl>(S.CurContext);
210 S.Diag(Loc, isa<ObjCMethodDecl>(S.CurContext)
211 ? diag::err_coroutine_objc_method
212 : diag::err_coroutine_outside_function) << Keyword;
216 // An enumeration for mapping the diagnostic type to the correct diagnostic
218 enum InvalidFuncDiag {
228 bool Diagnosed = false;
229 auto DiagInvalid = [&](InvalidFuncDiag ID) {
230 S.Diag(Loc, diag::err_coroutine_invalid_func_context) << ID << Keyword;
235 // Diagnose when a constructor, destructor, copy/move assignment operator,
236 // or the function 'main' are declared as a coroutine.
237 auto *MD = dyn_cast<CXXMethodDecl>(FD);
238 // [class.ctor]p6: "A constructor shall not be a coroutine."
239 if (MD && isa<CXXConstructorDecl>(MD))
240 return DiagInvalid(DiagCtor);
241 // [class.dtor]p17: "A destructor shall not be a coroutine."
242 else if (MD && isa<CXXDestructorDecl>(MD))
243 return DiagInvalid(DiagDtor);
244 // N4499 [special]p6: "A special member function shall not be a coroutine."
245 // Per C++ [special]p1, special member functions are the "default constructor,
246 // copy constructor and copy assignment operator, move constructor and move
247 // assignment operator, and destructor."
248 else if (MD && MD->isCopyAssignmentOperator())
249 return DiagInvalid(DiagCopyAssign);
250 else if (MD && MD->isMoveAssignmentOperator())
251 return DiagInvalid(DiagMoveAssign);
252 // [basic.start.main]p3: "The function main shall not be a coroutine."
253 else if (FD->isMain())
254 return DiagInvalid(DiagMain);
256 // Emit a diagnostics for each of the following conditions which is not met.
257 // [expr.const]p2: "An expression e is a core constant expression unless the
258 // evaluation of e [...] would evaluate one of the following expressions:
259 // [...] an await-expression [...] a yield-expression."
260 if (FD->isConstexpr())
261 DiagInvalid(DiagConstexpr);
262 // [dcl.spec.auto]p15: "A function declared with a return type that uses a
263 // placeholder type shall not be a coroutine."
264 if (FD->getReturnType()->isUndeducedType())
265 DiagInvalid(DiagAutoRet);
266 // [dcl.fct.def.coroutine]p1: "The parameter-declaration-clause of the
267 // coroutine shall not terminate with an ellipsis that is not part of a
268 // parameter-declaration."
269 if (FD->isVariadic())
270 DiagInvalid(DiagVarargs);
275 static ExprResult buildOperatorCoawaitLookupExpr(Sema &SemaRef, Scope *S,
276 SourceLocation Loc) {
277 DeclarationName OpName =
278 SemaRef.Context.DeclarationNames.getCXXOperatorName(OO_Coawait);
279 LookupResult Operators(SemaRef, OpName, SourceLocation(),
280 Sema::LookupOperatorName);
281 SemaRef.LookupName(Operators, S);
283 assert(!Operators.isAmbiguous() && "Operator lookup cannot be ambiguous");
284 const auto &Functions = Operators.asUnresolvedSet();
286 Functions.size() > 1 ||
287 (Functions.size() == 1 && isa<FunctionTemplateDecl>(*Functions.begin()));
288 Expr *CoawaitOp = UnresolvedLookupExpr::Create(
289 SemaRef.Context, /*NamingClass*/ nullptr, NestedNameSpecifierLoc(),
290 DeclarationNameInfo(OpName, Loc), /*RequiresADL*/ true, IsOverloaded,
291 Functions.begin(), Functions.end());
296 /// Build a call to 'operator co_await' if there is a suitable operator for
297 /// the given expression.
298 static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, SourceLocation Loc,
300 UnresolvedLookupExpr *Lookup) {
301 UnresolvedSet<16> Functions;
302 Functions.append(Lookup->decls_begin(), Lookup->decls_end());
303 return SemaRef.CreateOverloadedUnaryOp(Loc, UO_Coawait, Functions, E);
306 static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, Scope *S,
307 SourceLocation Loc, Expr *E) {
308 ExprResult R = buildOperatorCoawaitLookupExpr(SemaRef, S, Loc);
311 return buildOperatorCoawaitCall(SemaRef, Loc, E,
312 cast<UnresolvedLookupExpr>(R.get()));
315 static Expr *buildBuiltinCall(Sema &S, SourceLocation Loc, Builtin::ID Id,
316 MultiExprArg CallArgs) {
317 StringRef Name = S.Context.BuiltinInfo.getName(Id);
318 LookupResult R(S, &S.Context.Idents.get(Name), Loc, Sema::LookupOrdinaryName);
319 S.LookupName(R, S.TUScope, /*AllowBuiltinCreation=*/true);
321 auto *BuiltInDecl = R.getAsSingle<FunctionDecl>();
322 assert(BuiltInDecl && "failed to find builtin declaration");
325 S.BuildDeclRefExpr(BuiltInDecl, BuiltInDecl->getType(), VK_LValue, Loc);
326 assert(DeclRef.isUsable() && "Builtin reference cannot fail");
329 S.ActOnCallExpr(/*Scope=*/nullptr, DeclRef.get(), Loc, CallArgs, Loc);
331 assert(!Call.isInvalid() && "Call to builtin cannot fail!");
335 static ExprResult buildCoroutineHandle(Sema &S, QualType PromiseType,
336 SourceLocation Loc) {
337 QualType CoroHandleType = lookupCoroutineHandleType(S, PromiseType, Loc);
338 if (CoroHandleType.isNull())
341 DeclContext *LookupCtx = S.computeDeclContext(CoroHandleType);
342 LookupResult Found(S, &S.PP.getIdentifierTable().get("from_address"), Loc,
343 Sema::LookupOrdinaryName);
344 if (!S.LookupQualifiedName(Found, LookupCtx)) {
345 S.Diag(Loc, diag::err_coroutine_handle_missing_member)
351 buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_frame, {});
354 ExprResult FromAddr =
355 S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
356 if (FromAddr.isInvalid())
359 return S.ActOnCallExpr(nullptr, FromAddr.get(), Loc, FramePtr, Loc);
362 struct ReadySuspendResumeResult {
363 enum AwaitCallType { ACT_Ready, ACT_Suspend, ACT_Resume };
365 OpaqueValueExpr *OpaqueValue;
369 static ExprResult buildMemberCall(Sema &S, Expr *Base, SourceLocation Loc,
370 StringRef Name, MultiExprArg Args) {
371 DeclarationNameInfo NameInfo(&S.PP.getIdentifierTable().get(Name), Loc);
373 // FIXME: Fix BuildMemberReferenceExpr to take a const CXXScopeSpec&.
375 ExprResult Result = S.BuildMemberReferenceExpr(
376 Base, Base->getType(), Loc, /*IsPtr=*/false, SS,
377 SourceLocation(), nullptr, NameInfo, /*TemplateArgs=*/nullptr,
379 if (Result.isInvalid())
382 // We meant exactly what we asked for. No need for typo correction.
383 if (auto *TE = dyn_cast<TypoExpr>(Result.get())) {
384 S.clearDelayedTypo(TE);
385 S.Diag(Loc, diag::err_no_member)
386 << NameInfo.getName() << Base->getType()->getAsCXXRecordDecl()
387 << Base->getSourceRange();
391 return S.ActOnCallExpr(nullptr, Result.get(), Loc, Args, Loc, nullptr);
394 // See if return type is coroutine-handle and if so, invoke builtin coro-resume
395 // on its address. This is to enable experimental support for coroutine-handle
396 // returning await_suspend that results in a guaranteed tail call to the target
398 static Expr *maybeTailCall(Sema &S, QualType RetType, Expr *E,
399 SourceLocation Loc) {
400 if (RetType->isReferenceType())
402 Type const *T = RetType.getTypePtr();
403 if (!T->isClassType() && !T->isStructureType())
406 // FIXME: Add convertability check to coroutine_handle<>. Possibly via
407 // EvaluateBinaryTypeTrait(BTT_IsConvertible, ...) which is at the moment
408 // a private function in SemaExprCXX.cpp
410 ExprResult AddressExpr = buildMemberCall(S, E, Loc, "address", None);
411 if (AddressExpr.isInvalid())
414 Expr *JustAddress = AddressExpr.get();
415 // FIXME: Check that the type of AddressExpr is void*
416 return buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_resume,
420 /// Build calls to await_ready, await_suspend, and await_resume for a co_await
422 static ReadySuspendResumeResult buildCoawaitCalls(Sema &S, VarDecl *CoroPromise,
423 SourceLocation Loc, Expr *E) {
424 OpaqueValueExpr *Operand = new (S.Context)
425 OpaqueValueExpr(Loc, E->getType(), VK_LValue, E->getObjectKind(), E);
427 // Assume invalid until we see otherwise.
428 ReadySuspendResumeResult Calls = {{}, Operand, /*IsInvalid=*/true};
430 ExprResult CoroHandleRes = buildCoroutineHandle(S, CoroPromise->getType(), Loc);
431 if (CoroHandleRes.isInvalid())
433 Expr *CoroHandle = CoroHandleRes.get();
435 const StringRef Funcs[] = {"await_ready", "await_suspend", "await_resume"};
436 MultiExprArg Args[] = {None, CoroHandle, None};
437 for (size_t I = 0, N = llvm::array_lengthof(Funcs); I != N; ++I) {
438 ExprResult Result = buildMemberCall(S, Operand, Loc, Funcs[I], Args[I]);
439 if (Result.isInvalid())
441 Calls.Results[I] = Result.get();
444 // Assume the calls are valid; all further checking should make them invalid.
445 Calls.IsInvalid = false;
447 using ACT = ReadySuspendResumeResult::AwaitCallType;
448 CallExpr *AwaitReady = cast<CallExpr>(Calls.Results[ACT::ACT_Ready]);
449 if (!AwaitReady->getType()->isDependentType()) {
450 // [expr.await]p3 [...]
451 // — await-ready is the expression e.await_ready(), contextually converted
453 ExprResult Conv = S.PerformContextuallyConvertToBool(AwaitReady);
454 if (Conv.isInvalid()) {
455 S.Diag(AwaitReady->getDirectCallee()->getBeginLoc(),
456 diag::note_await_ready_no_bool_conversion);
457 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
458 << AwaitReady->getDirectCallee() << E->getSourceRange();
459 Calls.IsInvalid = true;
461 Calls.Results[ACT::ACT_Ready] = Conv.get();
463 CallExpr *AwaitSuspend = cast<CallExpr>(Calls.Results[ACT::ACT_Suspend]);
464 if (!AwaitSuspend->getType()->isDependentType()) {
465 // [expr.await]p3 [...]
466 // - await-suspend is the expression e.await_suspend(h), which shall be
467 // a prvalue of type void or bool.
468 QualType RetType = AwaitSuspend->getCallReturnType(S.Context);
470 // Experimental support for coroutine_handle returning await_suspend.
471 if (Expr *TailCallSuspend = maybeTailCall(S, RetType, AwaitSuspend, Loc))
472 Calls.Results[ACT::ACT_Suspend] = TailCallSuspend;
474 // non-class prvalues always have cv-unqualified types
475 if (RetType->isReferenceType() ||
476 (!RetType->isBooleanType() && !RetType->isVoidType())) {
477 S.Diag(AwaitSuspend->getCalleeDecl()->getLocation(),
478 diag::err_await_suspend_invalid_return_type)
480 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
481 << AwaitSuspend->getDirectCallee();
482 Calls.IsInvalid = true;
490 static ExprResult buildPromiseCall(Sema &S, VarDecl *Promise,
491 SourceLocation Loc, StringRef Name,
494 // Form a reference to the promise.
495 ExprResult PromiseRef = S.BuildDeclRefExpr(
496 Promise, Promise->getType().getNonReferenceType(), VK_LValue, Loc);
497 if (PromiseRef.isInvalid())
500 return buildMemberCall(S, PromiseRef.get(), Loc, Name, Args);
503 VarDecl *Sema::buildCoroutinePromise(SourceLocation Loc) {
504 assert(isa<FunctionDecl>(CurContext) && "not in a function scope");
505 auto *FD = cast<FunctionDecl>(CurContext);
506 bool IsThisDependentType = [&] {
507 if (auto *MD = dyn_cast_or_null<CXXMethodDecl>(FD))
508 return MD->isInstance() && MD->getThisType()->isDependentType();
513 QualType T = FD->getType()->isDependentType() || IsThisDependentType
514 ? Context.DependentTy
515 : lookupPromiseType(*this, FD, Loc);
519 auto *VD = VarDecl::Create(Context, FD, FD->getLocation(), FD->getLocation(),
520 &PP.getIdentifierTable().get("__promise"), T,
521 Context.getTrivialTypeSourceInfo(T, Loc), SC_None);
522 CheckVariableDeclarationType(VD);
523 if (VD->isInvalidDecl())
526 auto *ScopeInfo = getCurFunction();
527 // Build a list of arguments, based on the coroutine functions arguments,
528 // that will be passed to the promise type's constructor.
529 llvm::SmallVector<Expr *, 4> CtorArgExprs;
531 // Add implicit object parameter.
532 if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
533 if (MD->isInstance() && !isLambdaCallOperator(MD)) {
534 ExprResult ThisExpr = ActOnCXXThis(Loc);
535 if (ThisExpr.isInvalid())
537 ThisExpr = CreateBuiltinUnaryOp(Loc, UO_Deref, ThisExpr.get());
538 if (ThisExpr.isInvalid())
540 CtorArgExprs.push_back(ThisExpr.get());
544 auto &Moves = ScopeInfo->CoroutineParameterMoves;
545 for (auto *PD : FD->parameters()) {
546 if (PD->getType()->isDependentType())
549 auto RefExpr = ExprEmpty();
550 auto Move = Moves.find(PD);
551 assert(Move != Moves.end() &&
552 "Coroutine function parameter not inserted into move map");
553 // If a reference to the function parameter exists in the coroutine
554 // frame, use that reference.
556 cast<VarDecl>(cast<DeclStmt>(Move->second)->getSingleDecl());
558 BuildDeclRefExpr(MoveDecl, MoveDecl->getType().getNonReferenceType(),
559 ExprValueKind::VK_LValue, FD->getLocation());
560 if (RefExpr.isInvalid())
562 CtorArgExprs.push_back(RefExpr.get());
565 // Create an initialization sequence for the promise type using the
566 // constructor arguments, wrapped in a parenthesized list expression.
567 Expr *PLE = ParenListExpr::Create(Context, FD->getLocation(),
568 CtorArgExprs, FD->getLocation());
569 InitializedEntity Entity = InitializedEntity::InitializeVariable(VD);
570 InitializationKind Kind = InitializationKind::CreateForInit(
571 VD->getLocation(), /*DirectInit=*/true, PLE);
572 InitializationSequence InitSeq(*this, Entity, Kind, CtorArgExprs,
573 /*TopLevelOfInitList=*/false,
574 /*TreatUnavailableAsInvalid=*/false);
576 // Attempt to initialize the promise type with the arguments.
577 // If that fails, fall back to the promise type's default constructor.
579 ExprResult Result = InitSeq.Perform(*this, Entity, Kind, CtorArgExprs);
580 if (Result.isInvalid()) {
581 VD->setInvalidDecl();
582 } else if (Result.get()) {
583 VD->setInit(MaybeCreateExprWithCleanups(Result.get()));
584 VD->setInitStyle(VarDecl::CallInit);
585 CheckCompleteVariableDeclaration(VD);
588 ActOnUninitializedDecl(VD);
594 /// Check that this is a context in which a coroutine suspension can appear.
595 static FunctionScopeInfo *checkCoroutineContext(Sema &S, SourceLocation Loc,
597 bool IsImplicit = false) {
598 if (!isValidCoroutineContext(S, Loc, Keyword))
601 assert(isa<FunctionDecl>(S.CurContext) && "not in a function scope");
603 auto *ScopeInfo = S.getCurFunction();
604 assert(ScopeInfo && "missing function scope for function");
606 if (ScopeInfo->FirstCoroutineStmtLoc.isInvalid() && !IsImplicit)
607 ScopeInfo->setFirstCoroutineStmt(Loc, Keyword);
609 if (ScopeInfo->CoroutinePromise)
612 if (!S.buildCoroutineParameterMoves(Loc))
615 ScopeInfo->CoroutinePromise = S.buildCoroutinePromise(Loc);
616 if (!ScopeInfo->CoroutinePromise)
622 bool Sema::ActOnCoroutineBodyStart(Scope *SC, SourceLocation KWLoc,
624 if (!checkCoroutineContext(*this, KWLoc, Keyword))
626 auto *ScopeInfo = getCurFunction();
627 assert(ScopeInfo->CoroutinePromise);
629 // If we have existing coroutine statements then we have already built
630 // the initial and final suspend points.
631 if (!ScopeInfo->NeedsCoroutineSuspends)
634 ScopeInfo->setNeedsCoroutineSuspends(false);
636 auto *Fn = cast<FunctionDecl>(CurContext);
637 SourceLocation Loc = Fn->getLocation();
638 // Build the initial suspend point
639 auto buildSuspends = [&](StringRef Name) mutable -> StmtResult {
641 buildPromiseCall(*this, ScopeInfo->CoroutinePromise, Loc, Name, None);
642 if (Suspend.isInvalid())
644 Suspend = buildOperatorCoawaitCall(*this, SC, Loc, Suspend.get());
645 if (Suspend.isInvalid())
647 Suspend = BuildResolvedCoawaitExpr(Loc, Suspend.get(),
648 /*IsImplicit*/ true);
649 Suspend = ActOnFinishFullExpr(Suspend.get(), /*DiscardedValue*/ false);
650 if (Suspend.isInvalid()) {
651 Diag(Loc, diag::note_coroutine_promise_suspend_implicitly_required)
652 << ((Name == "initial_suspend") ? 0 : 1);
653 Diag(KWLoc, diag::note_declared_coroutine_here) << Keyword;
656 return cast<Stmt>(Suspend.get());
659 StmtResult InitSuspend = buildSuspends("initial_suspend");
660 if (InitSuspend.isInvalid())
663 StmtResult FinalSuspend = buildSuspends("final_suspend");
664 if (FinalSuspend.isInvalid())
667 ScopeInfo->setCoroutineSuspends(InitSuspend.get(), FinalSuspend.get());
672 ExprResult Sema::ActOnCoawaitExpr(Scope *S, SourceLocation Loc, Expr *E) {
673 if (!ActOnCoroutineBodyStart(S, Loc, "co_await")) {
674 CorrectDelayedTyposInExpr(E);
678 if (E->getType()->isPlaceholderType()) {
679 ExprResult R = CheckPlaceholderExpr(E);
680 if (R.isInvalid()) return ExprError();
683 ExprResult Lookup = buildOperatorCoawaitLookupExpr(*this, S, Loc);
684 if (Lookup.isInvalid())
686 return BuildUnresolvedCoawaitExpr(Loc, E,
687 cast<UnresolvedLookupExpr>(Lookup.get()));
690 ExprResult Sema::BuildUnresolvedCoawaitExpr(SourceLocation Loc, Expr *E,
691 UnresolvedLookupExpr *Lookup) {
692 auto *FSI = checkCoroutineContext(*this, Loc, "co_await");
696 if (E->getType()->isPlaceholderType()) {
697 ExprResult R = CheckPlaceholderExpr(E);
703 auto *Promise = FSI->CoroutinePromise;
704 if (Promise->getType()->isDependentType()) {
706 new (Context) DependentCoawaitExpr(Loc, Context.DependentTy, E, Lookup);
710 auto *RD = Promise->getType()->getAsCXXRecordDecl();
711 if (lookupMember(*this, "await_transform", RD, Loc)) {
712 ExprResult R = buildPromiseCall(*this, Promise, Loc, "await_transform", E);
715 diag::note_coroutine_promise_implicit_await_transform_required_here)
716 << E->getSourceRange();
721 ExprResult Awaitable = buildOperatorCoawaitCall(*this, Loc, E, Lookup);
722 if (Awaitable.isInvalid())
725 return BuildResolvedCoawaitExpr(Loc, Awaitable.get());
728 ExprResult Sema::BuildResolvedCoawaitExpr(SourceLocation Loc, Expr *E,
730 auto *Coroutine = checkCoroutineContext(*this, Loc, "co_await", IsImplicit);
734 if (E->getType()->isPlaceholderType()) {
735 ExprResult R = CheckPlaceholderExpr(E);
736 if (R.isInvalid()) return ExprError();
740 if (E->getType()->isDependentType()) {
741 Expr *Res = new (Context)
742 CoawaitExpr(Loc, Context.DependentTy, E, IsImplicit);
746 // If the expression is a temporary, materialize it as an lvalue so that we
747 // can use it multiple times.
748 if (E->getValueKind() == VK_RValue)
749 E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
751 // The location of the `co_await` token cannot be used when constructing
752 // the member call expressions since it's before the location of `Expr`, which
753 // is used as the start of the member call expression.
754 SourceLocation CallLoc = E->getExprLoc();
756 // Build the await_ready, await_suspend, await_resume calls.
757 ReadySuspendResumeResult RSS =
758 buildCoawaitCalls(*this, Coroutine->CoroutinePromise, CallLoc, E);
763 new (Context) CoawaitExpr(Loc, E, RSS.Results[0], RSS.Results[1],
764 RSS.Results[2], RSS.OpaqueValue, IsImplicit);
769 ExprResult Sema::ActOnCoyieldExpr(Scope *S, SourceLocation Loc, Expr *E) {
770 if (!ActOnCoroutineBodyStart(S, Loc, "co_yield")) {
771 CorrectDelayedTyposInExpr(E);
775 // Build yield_value call.
776 ExprResult Awaitable = buildPromiseCall(
777 *this, getCurFunction()->CoroutinePromise, Loc, "yield_value", E);
778 if (Awaitable.isInvalid())
781 // Build 'operator co_await' call.
782 Awaitable = buildOperatorCoawaitCall(*this, S, Loc, Awaitable.get());
783 if (Awaitable.isInvalid())
786 return BuildCoyieldExpr(Loc, Awaitable.get());
788 ExprResult Sema::BuildCoyieldExpr(SourceLocation Loc, Expr *E) {
789 auto *Coroutine = checkCoroutineContext(*this, Loc, "co_yield");
793 if (E->getType()->isPlaceholderType()) {
794 ExprResult R = CheckPlaceholderExpr(E);
795 if (R.isInvalid()) return ExprError();
799 if (E->getType()->isDependentType()) {
800 Expr *Res = new (Context) CoyieldExpr(Loc, Context.DependentTy, E);
804 // If the expression is a temporary, materialize it as an lvalue so that we
805 // can use it multiple times.
806 if (E->getValueKind() == VK_RValue)
807 E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
809 // Build the await_ready, await_suspend, await_resume calls.
810 ReadySuspendResumeResult RSS =
811 buildCoawaitCalls(*this, Coroutine->CoroutinePromise, Loc, E);
816 new (Context) CoyieldExpr(Loc, E, RSS.Results[0], RSS.Results[1],
817 RSS.Results[2], RSS.OpaqueValue);
822 StmtResult Sema::ActOnCoreturnStmt(Scope *S, SourceLocation Loc, Expr *E) {
823 if (!ActOnCoroutineBodyStart(S, Loc, "co_return")) {
824 CorrectDelayedTyposInExpr(E);
827 return BuildCoreturnStmt(Loc, E);
830 StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E,
832 auto *FSI = checkCoroutineContext(*this, Loc, "co_return", IsImplicit);
836 if (E && E->getType()->isPlaceholderType() &&
837 !E->getType()->isSpecificPlaceholderType(BuiltinType::Overload)) {
838 ExprResult R = CheckPlaceholderExpr(E);
839 if (R.isInvalid()) return StmtError();
843 // Move the return value if we can
845 auto NRVOCandidate = this->getCopyElisionCandidate(E->getType(), E, CES_AsIfByStdMove);
847 InitializedEntity Entity =
848 InitializedEntity::InitializeResult(Loc, E->getType(), NRVOCandidate);
849 ExprResult MoveResult = this->PerformMoveOrCopyInitialization(
850 Entity, NRVOCandidate, E->getType(), E);
851 if (MoveResult.get())
852 E = MoveResult.get();
856 // FIXME: If the operand is a reference to a variable that's about to go out
857 // of scope, we should treat the operand as an xvalue for this overload
859 VarDecl *Promise = FSI->CoroutinePromise;
861 if (E && (isa<InitListExpr>(E) || !E->getType()->isVoidType())) {
862 PC = buildPromiseCall(*this, Promise, Loc, "return_value", E);
864 E = MakeFullDiscardedValueExpr(E).get();
865 PC = buildPromiseCall(*this, Promise, Loc, "return_void", None);
870 Expr *PCE = ActOnFinishFullExpr(PC.get(), /*DiscardedValue*/ false).get();
872 Stmt *Res = new (Context) CoreturnStmt(Loc, E, PCE, IsImplicit);
876 /// Look up the std::nothrow object.
877 static Expr *buildStdNoThrowDeclRef(Sema &S, SourceLocation Loc) {
878 NamespaceDecl *Std = S.getStdNamespace();
879 assert(Std && "Should already be diagnosed");
881 LookupResult Result(S, &S.PP.getIdentifierTable().get("nothrow"), Loc,
882 Sema::LookupOrdinaryName);
883 if (!S.LookupQualifiedName(Result, Std)) {
884 // FIXME: <experimental/coroutine> should have been included already.
885 // If we require it to include <new> then this diagnostic is no longer
887 S.Diag(Loc, diag::err_implicit_coroutine_std_nothrow_type_not_found);
891 auto *VD = Result.getAsSingle<VarDecl>();
893 Result.suppressDiagnostics();
894 // We found something weird. Complain about the first thing we found.
895 NamedDecl *Found = *Result.begin();
896 S.Diag(Found->getLocation(), diag::err_malformed_std_nothrow);
900 ExprResult DR = S.BuildDeclRefExpr(VD, VD->getType(), VK_LValue, Loc);
907 // Find an appropriate delete for the promise.
908 static FunctionDecl *findDeleteForPromise(Sema &S, SourceLocation Loc,
909 QualType PromiseType) {
910 FunctionDecl *OperatorDelete = nullptr;
912 DeclarationName DeleteName =
913 S.Context.DeclarationNames.getCXXOperatorName(OO_Delete);
915 auto *PointeeRD = PromiseType->getAsCXXRecordDecl();
916 assert(PointeeRD && "PromiseType must be a CxxRecordDecl type");
918 if (S.FindDeallocationFunction(Loc, PointeeRD, DeleteName, OperatorDelete))
921 if (!OperatorDelete) {
922 // Look for a global declaration.
923 const bool CanProvideSize = S.isCompleteType(Loc, PromiseType);
924 const bool Overaligned = false;
925 OperatorDelete = S.FindUsualDeallocationFunction(Loc, CanProvideSize,
926 Overaligned, DeleteName);
928 S.MarkFunctionReferenced(Loc, OperatorDelete);
929 return OperatorDelete;
933 void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body) {
934 FunctionScopeInfo *Fn = getCurFunction();
935 assert(Fn && Fn->isCoroutine() && "not a coroutine");
937 assert(FD->isInvalidDecl() &&
938 "a null body is only allowed for invalid declarations");
941 // We have a function that uses coroutine keywords, but we failed to build
943 if (!Fn->CoroutinePromise)
944 return FD->setInvalidDecl();
946 if (isa<CoroutineBodyStmt>(Body)) {
947 // Nothing todo. the body is already a transformed coroutine body statement.
951 // Coroutines [stmt.return]p1:
952 // A return statement shall not appear in a coroutine.
953 if (Fn->FirstReturnLoc.isValid()) {
954 assert(Fn->FirstCoroutineStmtLoc.isValid() &&
955 "first coroutine location not set");
956 Diag(Fn->FirstReturnLoc, diag::err_return_in_coroutine);
957 Diag(Fn->FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
958 << Fn->getFirstCoroutineStmtKeyword();
960 CoroutineStmtBuilder Builder(*this, *FD, *Fn, Body);
961 if (Builder.isInvalid() || !Builder.buildStatements())
962 return FD->setInvalidDecl();
964 // Build body for the coroutine wrapper statement.
965 Body = CoroutineBodyStmt::Create(Context, Builder);
968 CoroutineStmtBuilder::CoroutineStmtBuilder(Sema &S, FunctionDecl &FD,
969 sema::FunctionScopeInfo &Fn,
971 : S(S), FD(FD), Fn(Fn), Loc(FD.getLocation()),
972 IsPromiseDependentType(
973 !Fn.CoroutinePromise ||
974 Fn.CoroutinePromise->getType()->isDependentType()) {
977 for (auto KV : Fn.CoroutineParameterMoves)
978 this->ParamMovesVector.push_back(KV.second);
979 this->ParamMoves = this->ParamMovesVector;
981 if (!IsPromiseDependentType) {
982 PromiseRecordDecl = Fn.CoroutinePromise->getType()->getAsCXXRecordDecl();
983 assert(PromiseRecordDecl && "Type should have already been checked");
985 this->IsValid = makePromiseStmt() && makeInitialAndFinalSuspend();
988 bool CoroutineStmtBuilder::buildStatements() {
989 assert(this->IsValid && "coroutine already invalid");
990 this->IsValid = makeReturnObject();
991 if (this->IsValid && !IsPromiseDependentType)
992 buildDependentStatements();
993 return this->IsValid;
996 bool CoroutineStmtBuilder::buildDependentStatements() {
997 assert(this->IsValid && "coroutine already invalid");
998 assert(!this->IsPromiseDependentType &&
999 "coroutine cannot have a dependent promise type");
1000 this->IsValid = makeOnException() && makeOnFallthrough() &&
1001 makeGroDeclAndReturnStmt() && makeReturnOnAllocFailure() &&
1002 makeNewAndDeleteExpr();
1003 return this->IsValid;
1006 bool CoroutineStmtBuilder::makePromiseStmt() {
1007 // Form a declaration statement for the promise declaration, so that AST
1008 // visitors can more easily find it.
1009 StmtResult PromiseStmt =
1010 S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(Fn.CoroutinePromise), Loc, Loc);
1011 if (PromiseStmt.isInvalid())
1014 this->Promise = PromiseStmt.get();
1018 bool CoroutineStmtBuilder::makeInitialAndFinalSuspend() {
1019 if (Fn.hasInvalidCoroutineSuspends())
1021 this->InitialSuspend = cast<Expr>(Fn.CoroutineSuspends.first);
1022 this->FinalSuspend = cast<Expr>(Fn.CoroutineSuspends.second);
1026 static bool diagReturnOnAllocFailure(Sema &S, Expr *E,
1027 CXXRecordDecl *PromiseRecordDecl,
1028 FunctionScopeInfo &Fn) {
1029 auto Loc = E->getExprLoc();
1030 if (auto *DeclRef = dyn_cast_or_null<DeclRefExpr>(E)) {
1031 auto *Decl = DeclRef->getDecl();
1032 if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(Decl)) {
1033 if (Method->isStatic())
1036 Loc = Decl->getLocation();
1042 diag::err_coroutine_promise_get_return_object_on_allocation_failure)
1043 << PromiseRecordDecl;
1044 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1045 << Fn.getFirstCoroutineStmtKeyword();
1049 bool CoroutineStmtBuilder::makeReturnOnAllocFailure() {
1050 assert(!IsPromiseDependentType &&
1051 "cannot make statement while the promise type is dependent");
1053 // [dcl.fct.def.coroutine]/8
1054 // The unqualified-id get_return_object_on_allocation_failure is looked up in
1055 // the scope of class P by class member access lookup (3.4.5). ...
1056 // If an allocation function returns nullptr, ... the coroutine return value
1057 // is obtained by a call to ... get_return_object_on_allocation_failure().
1059 DeclarationName DN =
1060 S.PP.getIdentifierInfo("get_return_object_on_allocation_failure");
1061 LookupResult Found(S, DN, Loc, Sema::LookupMemberName);
1062 if (!S.LookupQualifiedName(Found, PromiseRecordDecl))
1066 ExprResult DeclNameExpr =
1067 S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
1068 if (DeclNameExpr.isInvalid())
1071 if (!diagReturnOnAllocFailure(S, DeclNameExpr.get(), PromiseRecordDecl, Fn))
1074 ExprResult ReturnObjectOnAllocationFailure =
1075 S.ActOnCallExpr(nullptr, DeclNameExpr.get(), Loc, {}, Loc);
1076 if (ReturnObjectOnAllocationFailure.isInvalid())
1079 StmtResult ReturnStmt =
1080 S.BuildReturnStmt(Loc, ReturnObjectOnAllocationFailure.get());
1081 if (ReturnStmt.isInvalid()) {
1082 S.Diag(Found.getFoundDecl()->getLocation(), diag::note_member_declared_here)
1084 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1085 << Fn.getFirstCoroutineStmtKeyword();
1089 this->ReturnStmtOnAllocFailure = ReturnStmt.get();
1093 bool CoroutineStmtBuilder::makeNewAndDeleteExpr() {
1094 // Form and check allocation and deallocation calls.
1095 assert(!IsPromiseDependentType &&
1096 "cannot make statement while the promise type is dependent");
1097 QualType PromiseType = Fn.CoroutinePromise->getType();
1099 if (S.RequireCompleteType(Loc, PromiseType, diag::err_incomplete_type))
1102 const bool RequiresNoThrowAlloc = ReturnStmtOnAllocFailure != nullptr;
1104 // [dcl.fct.def.coroutine]/7
1105 // Lookup allocation functions using a parameter list composed of the
1106 // requested size of the coroutine state being allocated, followed by
1107 // the coroutine function's arguments. If a matching allocation function
1108 // exists, use it. Otherwise, use an allocation function that just takes
1109 // the requested size.
1111 FunctionDecl *OperatorNew = nullptr;
1112 FunctionDecl *OperatorDelete = nullptr;
1113 FunctionDecl *UnusedResult = nullptr;
1114 bool PassAlignment = false;
1115 SmallVector<Expr *, 1> PlacementArgs;
1117 // [dcl.fct.def.coroutine]/7
1118 // "The allocation function’s name is looked up in the scope of P.
1119 // [...] If the lookup finds an allocation function in the scope of P,
1120 // overload resolution is performed on a function call created by assembling
1121 // an argument list. The first argument is the amount of space requested,
1122 // and has type std::size_t. The lvalues p1 ... pn are the succeeding
1125 // ...where "p1 ... pn" are defined earlier as:
1127 // [dcl.fct.def.coroutine]/3
1128 // "For a coroutine f that is a non-static member function, let P1 denote the
1129 // type of the implicit object parameter (13.3.1) and P2 ... Pn be the types
1130 // of the function parameters; otherwise let P1 ... Pn be the types of the
1131 // function parameters. Let p1 ... pn be lvalues denoting those objects."
1132 if (auto *MD = dyn_cast<CXXMethodDecl>(&FD)) {
1133 if (MD->isInstance() && !isLambdaCallOperator(MD)) {
1134 ExprResult ThisExpr = S.ActOnCXXThis(Loc);
1135 if (ThisExpr.isInvalid())
1137 ThisExpr = S.CreateBuiltinUnaryOp(Loc, UO_Deref, ThisExpr.get());
1138 if (ThisExpr.isInvalid())
1140 PlacementArgs.push_back(ThisExpr.get());
1143 for (auto *PD : FD.parameters()) {
1144 if (PD->getType()->isDependentType())
1147 // Build a reference to the parameter.
1148 auto PDLoc = PD->getLocation();
1149 ExprResult PDRefExpr =
1150 S.BuildDeclRefExpr(PD, PD->getOriginalType().getNonReferenceType(),
1151 ExprValueKind::VK_LValue, PDLoc);
1152 if (PDRefExpr.isInvalid())
1155 PlacementArgs.push_back(PDRefExpr.get());
1157 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Class,
1158 /*DeleteScope*/ Sema::AFS_Both, PromiseType,
1159 /*isArray*/ false, PassAlignment, PlacementArgs,
1160 OperatorNew, UnusedResult, /*Diagnose*/ false);
1162 // [dcl.fct.def.coroutine]/7
1163 // "If no matching function is found, overload resolution is performed again
1164 // on a function call created by passing just the amount of space required as
1165 // an argument of type std::size_t."
1166 if (!OperatorNew && !PlacementArgs.empty()) {
1167 PlacementArgs.clear();
1168 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Class,
1169 /*DeleteScope*/ Sema::AFS_Both, PromiseType,
1170 /*isArray*/ false, PassAlignment, PlacementArgs,
1171 OperatorNew, UnusedResult, /*Diagnose*/ false);
1174 // [dcl.fct.def.coroutine]/7
1175 // "The allocation function’s name is looked up in the scope of P. If this
1176 // lookup fails, the allocation function’s name is looked up in the global
1179 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Global,
1180 /*DeleteScope*/ Sema::AFS_Both, PromiseType,
1181 /*isArray*/ false, PassAlignment, PlacementArgs,
1182 OperatorNew, UnusedResult);
1185 bool IsGlobalOverload =
1186 OperatorNew && !isa<CXXRecordDecl>(OperatorNew->getDeclContext());
1187 // If we didn't find a class-local new declaration and non-throwing new
1188 // was is required then we need to lookup the non-throwing global operator
1190 if (RequiresNoThrowAlloc && (!OperatorNew || IsGlobalOverload)) {
1191 auto *StdNoThrow = buildStdNoThrowDeclRef(S, Loc);
1194 PlacementArgs = {StdNoThrow};
1195 OperatorNew = nullptr;
1196 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Both,
1197 /*DeleteScope*/ Sema::AFS_Both, PromiseType,
1198 /*isArray*/ false, PassAlignment, PlacementArgs,
1199 OperatorNew, UnusedResult);
1205 if (RequiresNoThrowAlloc) {
1206 const auto *FT = OperatorNew->getType()->getAs<FunctionProtoType>();
1207 if (!FT->isNothrow(/*ResultIfDependent*/ false)) {
1208 S.Diag(OperatorNew->getLocation(),
1209 diag::err_coroutine_promise_new_requires_nothrow)
1211 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
1217 if ((OperatorDelete = findDeleteForPromise(S, Loc, PromiseType)) == nullptr)
1221 buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_frame, {});
1224 buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_size, {});
1229 S.BuildDeclRefExpr(OperatorNew, OperatorNew->getType(), VK_LValue, Loc);
1230 if (NewRef.isInvalid())
1233 SmallVector<Expr *, 2> NewArgs(1, FrameSize);
1234 for (auto Arg : PlacementArgs)
1235 NewArgs.push_back(Arg);
1237 ExprResult NewExpr =
1238 S.ActOnCallExpr(S.getCurScope(), NewRef.get(), Loc, NewArgs, Loc);
1239 NewExpr = S.ActOnFinishFullExpr(NewExpr.get(), /*DiscardedValue*/ false);
1240 if (NewExpr.isInvalid())
1243 // Make delete call.
1245 QualType OpDeleteQualType = OperatorDelete->getType();
1247 ExprResult DeleteRef =
1248 S.BuildDeclRefExpr(OperatorDelete, OpDeleteQualType, VK_LValue, Loc);
1249 if (DeleteRef.isInvalid())
1253 buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_free, {FramePtr});
1255 SmallVector<Expr *, 2> DeleteArgs{CoroFree};
1257 // Check if we need to pass the size.
1258 const auto *OpDeleteType =
1259 OpDeleteQualType.getTypePtr()->getAs<FunctionProtoType>();
1260 if (OpDeleteType->getNumParams() > 1)
1261 DeleteArgs.push_back(FrameSize);
1263 ExprResult DeleteExpr =
1264 S.ActOnCallExpr(S.getCurScope(), DeleteRef.get(), Loc, DeleteArgs, Loc);
1266 S.ActOnFinishFullExpr(DeleteExpr.get(), /*DiscardedValue*/ false);
1267 if (DeleteExpr.isInvalid())
1270 this->Allocate = NewExpr.get();
1271 this->Deallocate = DeleteExpr.get();
1276 bool CoroutineStmtBuilder::makeOnFallthrough() {
1277 assert(!IsPromiseDependentType &&
1278 "cannot make statement while the promise type is dependent");
1280 // [dcl.fct.def.coroutine]/4
1281 // The unqualified-ids 'return_void' and 'return_value' are looked up in
1282 // the scope of class P. If both are found, the program is ill-formed.
1283 bool HasRVoid, HasRValue;
1284 LookupResult LRVoid =
1285 lookupMember(S, "return_void", PromiseRecordDecl, Loc, HasRVoid);
1286 LookupResult LRValue =
1287 lookupMember(S, "return_value", PromiseRecordDecl, Loc, HasRValue);
1289 StmtResult Fallthrough;
1290 if (HasRVoid && HasRValue) {
1291 // FIXME Improve this diagnostic
1292 S.Diag(FD.getLocation(),
1293 diag::err_coroutine_promise_incompatible_return_functions)
1294 << PromiseRecordDecl;
1295 S.Diag(LRVoid.getRepresentativeDecl()->getLocation(),
1296 diag::note_member_first_declared_here)
1297 << LRVoid.getLookupName();
1298 S.Diag(LRValue.getRepresentativeDecl()->getLocation(),
1299 diag::note_member_first_declared_here)
1300 << LRValue.getLookupName();
1302 } else if (!HasRVoid && !HasRValue) {
1303 // FIXME: The PDTS currently specifies this case as UB, not ill-formed.
1304 // However we still diagnose this as an error since until the PDTS is fixed.
1305 S.Diag(FD.getLocation(),
1306 diag::err_coroutine_promise_requires_return_function)
1307 << PromiseRecordDecl;
1308 S.Diag(PromiseRecordDecl->getLocation(), diag::note_defined_here)
1309 << PromiseRecordDecl;
1311 } else if (HasRVoid) {
1312 // If the unqualified-id return_void is found, flowing off the end of a
1313 // coroutine is equivalent to a co_return with no operand. Otherwise,
1314 // flowing off the end of a coroutine results in undefined behavior.
1315 Fallthrough = S.BuildCoreturnStmt(FD.getLocation(), nullptr,
1316 /*IsImplicit*/false);
1317 Fallthrough = S.ActOnFinishFullStmt(Fallthrough.get());
1318 if (Fallthrough.isInvalid())
1322 this->OnFallthrough = Fallthrough.get();
1326 bool CoroutineStmtBuilder::makeOnException() {
1327 // Try to form 'p.unhandled_exception();'
1328 assert(!IsPromiseDependentType &&
1329 "cannot make statement while the promise type is dependent");
1331 const bool RequireUnhandledException = S.getLangOpts().CXXExceptions;
1333 if (!lookupMember(S, "unhandled_exception", PromiseRecordDecl, Loc)) {
1335 RequireUnhandledException
1336 ? diag::err_coroutine_promise_unhandled_exception_required
1338 warn_coroutine_promise_unhandled_exception_required_with_exceptions;
1339 S.Diag(Loc, DiagID) << PromiseRecordDecl;
1340 S.Diag(PromiseRecordDecl->getLocation(), diag::note_defined_here)
1341 << PromiseRecordDecl;
1342 return !RequireUnhandledException;
1345 // If exceptions are disabled, don't try to build OnException.
1346 if (!S.getLangOpts().CXXExceptions)
1349 ExprResult UnhandledException = buildPromiseCall(S, Fn.CoroutinePromise, Loc,
1350 "unhandled_exception", None);
1351 UnhandledException = S.ActOnFinishFullExpr(UnhandledException.get(), Loc,
1352 /*DiscardedValue*/ false);
1353 if (UnhandledException.isInvalid())
1356 // Since the body of the coroutine will be wrapped in try-catch, it will
1357 // be incompatible with SEH __try if present in a function.
1358 if (!S.getLangOpts().Borland && Fn.FirstSEHTryLoc.isValid()) {
1359 S.Diag(Fn.FirstSEHTryLoc, diag::err_seh_in_a_coroutine_with_cxx_exceptions);
1360 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1361 << Fn.getFirstCoroutineStmtKeyword();
1365 this->OnException = UnhandledException.get();
1369 bool CoroutineStmtBuilder::makeReturnObject() {
1370 // Build implicit 'p.get_return_object()' expression and form initialization
1371 // of return type from it.
1372 ExprResult ReturnObject =
1373 buildPromiseCall(S, Fn.CoroutinePromise, Loc, "get_return_object", None);
1374 if (ReturnObject.isInvalid())
1377 this->ReturnValue = ReturnObject.get();
1381 static void noteMemberDeclaredHere(Sema &S, Expr *E, FunctionScopeInfo &Fn) {
1382 if (auto *MbrRef = dyn_cast<CXXMemberCallExpr>(E)) {
1383 auto *MethodDecl = MbrRef->getMethodDecl();
1384 S.Diag(MethodDecl->getLocation(), diag::note_member_declared_here)
1387 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1388 << Fn.getFirstCoroutineStmtKeyword();
1391 bool CoroutineStmtBuilder::makeGroDeclAndReturnStmt() {
1392 assert(!IsPromiseDependentType &&
1393 "cannot make statement while the promise type is dependent");
1394 assert(this->ReturnValue && "ReturnValue must be already formed");
1396 QualType const GroType = this->ReturnValue->getType();
1397 assert(!GroType->isDependentType() &&
1398 "get_return_object type must no longer be dependent");
1400 QualType const FnRetType = FD.getReturnType();
1401 assert(!FnRetType->isDependentType() &&
1402 "get_return_object type must no longer be dependent");
1404 if (FnRetType->isVoidType()) {
1406 S.ActOnFinishFullExpr(this->ReturnValue, Loc, /*DiscardedValue*/ false);
1407 if (Res.isInvalid())
1410 this->ResultDecl = Res.get();
1414 if (GroType->isVoidType()) {
1415 // Trigger a nice error message.
1416 InitializedEntity Entity =
1417 InitializedEntity::InitializeResult(Loc, FnRetType, false);
1418 S.PerformMoveOrCopyInitialization(Entity, nullptr, FnRetType, ReturnValue);
1419 noteMemberDeclaredHere(S, ReturnValue, Fn);
1423 auto *GroDecl = VarDecl::Create(
1424 S.Context, &FD, FD.getLocation(), FD.getLocation(),
1425 &S.PP.getIdentifierTable().get("__coro_gro"), GroType,
1426 S.Context.getTrivialTypeSourceInfo(GroType, Loc), SC_None);
1428 S.CheckVariableDeclarationType(GroDecl);
1429 if (GroDecl->isInvalidDecl())
1432 InitializedEntity Entity = InitializedEntity::InitializeVariable(GroDecl);
1433 ExprResult Res = S.PerformMoveOrCopyInitialization(Entity, nullptr, GroType,
1435 if (Res.isInvalid())
1438 Res = S.ActOnFinishFullExpr(Res.get(), /*DiscardedValue*/ false);
1439 if (Res.isInvalid())
1442 S.AddInitializerToDecl(GroDecl, Res.get(),
1443 /*DirectInit=*/false);
1445 S.FinalizeDeclaration(GroDecl);
1447 // Form a declaration statement for the return declaration, so that AST
1448 // visitors can more easily find it.
1449 StmtResult GroDeclStmt =
1450 S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(GroDecl), Loc, Loc);
1451 if (GroDeclStmt.isInvalid())
1454 this->ResultDecl = GroDeclStmt.get();
1456 ExprResult declRef = S.BuildDeclRefExpr(GroDecl, GroType, VK_LValue, Loc);
1457 if (declRef.isInvalid())
1460 StmtResult ReturnStmt = S.BuildReturnStmt(Loc, declRef.get());
1461 if (ReturnStmt.isInvalid()) {
1462 noteMemberDeclaredHere(S, ReturnValue, Fn);
1465 if (cast<clang::ReturnStmt>(ReturnStmt.get())->getNRVOCandidate() == GroDecl)
1466 GroDecl->setNRVOVariable(true);
1468 this->ReturnStmt = ReturnStmt.get();
1472 // Create a static_cast\<T&&>(expr).
1473 static Expr *castForMoving(Sema &S, Expr *E, QualType T = QualType()) {
1476 QualType TargetType = S.BuildReferenceType(
1477 T, /*SpelledAsLValue*/ false, SourceLocation(), DeclarationName());
1478 SourceLocation ExprLoc = E->getBeginLoc();
1479 TypeSourceInfo *TargetLoc =
1480 S.Context.getTrivialTypeSourceInfo(TargetType, ExprLoc);
1483 .BuildCXXNamedCast(ExprLoc, tok::kw_static_cast, TargetLoc, E,
1484 SourceRange(ExprLoc, ExprLoc), E->getSourceRange())
1488 /// Build a variable declaration for move parameter.
1489 static VarDecl *buildVarDecl(Sema &S, SourceLocation Loc, QualType Type,
1490 IdentifierInfo *II) {
1491 TypeSourceInfo *TInfo = S.Context.getTrivialTypeSourceInfo(Type, Loc);
1492 VarDecl *Decl = VarDecl::Create(S.Context, S.CurContext, Loc, Loc, II, Type,
1494 Decl->setImplicit();
1498 // Build statements that move coroutine function parameters to the coroutine
1499 // frame, and store them on the function scope info.
1500 bool Sema::buildCoroutineParameterMoves(SourceLocation Loc) {
1501 assert(isa<FunctionDecl>(CurContext) && "not in a function scope");
1502 auto *FD = cast<FunctionDecl>(CurContext);
1504 auto *ScopeInfo = getCurFunction();
1505 assert(ScopeInfo->CoroutineParameterMoves.empty() &&
1506 "Should not build parameter moves twice");
1508 for (auto *PD : FD->parameters()) {
1509 if (PD->getType()->isDependentType())
1512 ExprResult PDRefExpr =
1513 BuildDeclRefExpr(PD, PD->getType().getNonReferenceType(),
1514 ExprValueKind::VK_LValue, Loc); // FIXME: scope?
1515 if (PDRefExpr.isInvalid())
1518 Expr *CExpr = nullptr;
1519 if (PD->getType()->getAsCXXRecordDecl() ||
1520 PD->getType()->isRValueReferenceType())
1521 CExpr = castForMoving(*this, PDRefExpr.get());
1523 CExpr = PDRefExpr.get();
1525 auto D = buildVarDecl(*this, Loc, PD->getType(), PD->getIdentifier());
1526 AddInitializerToDecl(D, CExpr, /*DirectInit=*/true);
1528 // Convert decl to a statement.
1529 StmtResult Stmt = ActOnDeclStmt(ConvertDeclToDeclGroup(D), Loc, Loc);
1530 if (Stmt.isInvalid())
1533 ScopeInfo->CoroutineParameterMoves.insert(std::make_pair(PD, Stmt.get()));
1538 StmtResult Sema::BuildCoroutineBodyStmt(CoroutineBodyStmt::CtorArgs Args) {
1539 CoroutineBodyStmt *Res = CoroutineBodyStmt::Create(Context, Args);
1545 ClassTemplateDecl *Sema::lookupCoroutineTraits(SourceLocation KwLoc,
1546 SourceLocation FuncLoc) {
1547 if (!StdCoroutineTraitsCache) {
1548 if (auto StdExp = lookupStdExperimentalNamespace()) {
1549 LookupResult Result(*this,
1550 &PP.getIdentifierTable().get("coroutine_traits"),
1551 FuncLoc, LookupOrdinaryName);
1552 if (!LookupQualifiedName(Result, StdExp)) {
1553 Diag(KwLoc, diag::err_implied_coroutine_type_not_found)
1554 << "std::experimental::coroutine_traits";
1557 if (!(StdCoroutineTraitsCache =
1558 Result.getAsSingle<ClassTemplateDecl>())) {
1559 Result.suppressDiagnostics();
1560 NamedDecl *Found = *Result.begin();
1561 Diag(Found->getLocation(), diag::err_malformed_std_coroutine_traits);
1566 return StdCoroutineTraitsCache;