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 &&
88 MD->getThisType(S.Context)->getAs<PointerType>()->getPointeeType();
89 T = FnType->getRefQualifier() == RQ_RValue
90 ? S.Context.getRValueReferenceType(T)
91 : S.Context.getLValueReferenceType(T, /*SpelledAsLValue*/ true);
95 for (QualType T : FnType->getParamTypes())
98 // Build the template-id.
100 S.CheckTemplateIdType(TemplateName(CoroTraits), KwLoc, Args);
101 if (CoroTrait.isNull())
103 if (S.RequireCompleteType(KwLoc, CoroTrait,
104 diag::err_coroutine_type_missing_specialization))
107 auto *RD = CoroTrait->getAsCXXRecordDecl();
108 assert(RD && "specialization of class template is not a class?");
110 // Look up the ::promise_type member.
111 LookupResult R(S, &S.PP.getIdentifierTable().get("promise_type"), KwLoc,
112 Sema::LookupOrdinaryName);
113 S.LookupQualifiedName(R, RD);
114 auto *Promise = R.getAsSingle<TypeDecl>();
117 diag::err_implied_std_coroutine_traits_promise_type_not_found)
121 // The promise type is required to be a class type.
122 QualType PromiseType = S.Context.getTypeDeclType(Promise);
124 auto buildElaboratedType = [&]() {
125 auto *NNS = NestedNameSpecifier::Create(S.Context, nullptr, StdExp);
126 NNS = NestedNameSpecifier::Create(S.Context, NNS, false,
127 CoroTrait.getTypePtr());
128 return S.Context.getElaboratedType(ETK_None, NNS, PromiseType);
131 if (!PromiseType->getAsCXXRecordDecl()) {
133 diag::err_implied_std_coroutine_traits_promise_type_not_class)
134 << buildElaboratedType();
137 if (S.RequireCompleteType(FuncLoc, buildElaboratedType(),
138 diag::err_coroutine_promise_type_incomplete))
144 /// Look up the std::experimental::coroutine_handle<PromiseType>.
145 static QualType lookupCoroutineHandleType(Sema &S, QualType PromiseType,
146 SourceLocation Loc) {
147 if (PromiseType.isNull())
150 NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace();
151 assert(StdExp && "Should already be diagnosed");
153 LookupResult Result(S, &S.PP.getIdentifierTable().get("coroutine_handle"),
154 Loc, Sema::LookupOrdinaryName);
155 if (!S.LookupQualifiedName(Result, StdExp)) {
156 S.Diag(Loc, diag::err_implied_coroutine_type_not_found)
157 << "std::experimental::coroutine_handle";
161 ClassTemplateDecl *CoroHandle = Result.getAsSingle<ClassTemplateDecl>();
163 Result.suppressDiagnostics();
164 // We found something weird. Complain about the first thing we found.
165 NamedDecl *Found = *Result.begin();
166 S.Diag(Found->getLocation(), diag::err_malformed_std_coroutine_handle);
170 // Form template argument list for coroutine_handle<Promise>.
171 TemplateArgumentListInfo Args(Loc, Loc);
172 Args.addArgument(TemplateArgumentLoc(
173 TemplateArgument(PromiseType),
174 S.Context.getTrivialTypeSourceInfo(PromiseType, Loc)));
176 // Build the template-id.
177 QualType CoroHandleType =
178 S.CheckTemplateIdType(TemplateName(CoroHandle), Loc, Args);
179 if (CoroHandleType.isNull())
181 if (S.RequireCompleteType(Loc, CoroHandleType,
182 diag::err_coroutine_type_missing_specialization))
185 return CoroHandleType;
188 static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
190 // 'co_await' and 'co_yield' are not permitted in unevaluated operands,
191 // such as subexpressions of \c sizeof.
193 // [expr.await]p2, emphasis added: "An await-expression shall appear only in
194 // a *potentially evaluated* expression within the compound-statement of a
195 // function-body outside of a handler [...] A context within a function where
196 // an await-expression can appear is called a suspension context of the
197 // function." And per [expr.yield]p1: "A yield-expression shall appear only
198 // within a suspension context of a function."
199 if (S.isUnevaluatedContext()) {
200 S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword;
204 // Per [expr.await]p2, any other usage must be within a function.
205 // FIXME: This also covers [expr.await]p2: "An await-expression shall not
206 // appear in a default argument." But the diagnostic QoI here could be
207 // improved to inform the user that default arguments specifically are not
209 auto *FD = dyn_cast<FunctionDecl>(S.CurContext);
211 S.Diag(Loc, isa<ObjCMethodDecl>(S.CurContext)
212 ? diag::err_coroutine_objc_method
213 : diag::err_coroutine_outside_function) << Keyword;
217 // An enumeration for mapping the diagnostic type to the correct diagnostic
219 enum InvalidFuncDiag {
229 bool Diagnosed = false;
230 auto DiagInvalid = [&](InvalidFuncDiag ID) {
231 S.Diag(Loc, diag::err_coroutine_invalid_func_context) << ID << Keyword;
236 // Diagnose when a constructor, destructor, copy/move assignment operator,
237 // or the function 'main' are declared as a coroutine.
238 auto *MD = dyn_cast<CXXMethodDecl>(FD);
239 // [class.ctor]p6: "A constructor shall not be a coroutine."
240 if (MD && isa<CXXConstructorDecl>(MD))
241 return DiagInvalid(DiagCtor);
242 // [class.dtor]p17: "A destructor shall not be a coroutine."
243 else if (MD && isa<CXXDestructorDecl>(MD))
244 return DiagInvalid(DiagDtor);
245 // N4499 [special]p6: "A special member function shall not be a coroutine."
246 // Per C++ [special]p1, special member functions are the "default constructor,
247 // copy constructor and copy assignment operator, move constructor and move
248 // assignment operator, and destructor."
249 else if (MD && MD->isCopyAssignmentOperator())
250 return DiagInvalid(DiagCopyAssign);
251 else if (MD && MD->isMoveAssignmentOperator())
252 return DiagInvalid(DiagMoveAssign);
253 // [basic.start.main]p3: "The function main shall not be a coroutine."
254 else if (FD->isMain())
255 return DiagInvalid(DiagMain);
257 // Emit a diagnostics for each of the following conditions which is not met.
258 // [expr.const]p2: "An expression e is a core constant expression unless the
259 // evaluation of e [...] would evaluate one of the following expressions:
260 // [...] an await-expression [...] a yield-expression."
261 if (FD->isConstexpr())
262 DiagInvalid(DiagConstexpr);
263 // [dcl.spec.auto]p15: "A function declared with a return type that uses a
264 // placeholder type shall not be a coroutine."
265 if (FD->getReturnType()->isUndeducedType())
266 DiagInvalid(DiagAutoRet);
267 // [dcl.fct.def.coroutine]p1: "The parameter-declaration-clause of the
268 // coroutine shall not terminate with an ellipsis that is not part of a
269 // parameter-declaration."
270 if (FD->isVariadic())
271 DiagInvalid(DiagVarargs);
276 static ExprResult buildOperatorCoawaitLookupExpr(Sema &SemaRef, Scope *S,
277 SourceLocation Loc) {
278 DeclarationName OpName =
279 SemaRef.Context.DeclarationNames.getCXXOperatorName(OO_Coawait);
280 LookupResult Operators(SemaRef, OpName, SourceLocation(),
281 Sema::LookupOperatorName);
282 SemaRef.LookupName(Operators, S);
284 assert(!Operators.isAmbiguous() && "Operator lookup cannot be ambiguous");
285 const auto &Functions = Operators.asUnresolvedSet();
287 Functions.size() > 1 ||
288 (Functions.size() == 1 && isa<FunctionTemplateDecl>(*Functions.begin()));
289 Expr *CoawaitOp = UnresolvedLookupExpr::Create(
290 SemaRef.Context, /*NamingClass*/ nullptr, NestedNameSpecifierLoc(),
291 DeclarationNameInfo(OpName, Loc), /*RequiresADL*/ true, IsOverloaded,
292 Functions.begin(), Functions.end());
297 /// Build a call to 'operator co_await' if there is a suitable operator for
298 /// the given expression.
299 static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, SourceLocation Loc,
301 UnresolvedLookupExpr *Lookup) {
302 UnresolvedSet<16> Functions;
303 Functions.append(Lookup->decls_begin(), Lookup->decls_end());
304 return SemaRef.CreateOverloadedUnaryOp(Loc, UO_Coawait, Functions, E);
307 static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, Scope *S,
308 SourceLocation Loc, Expr *E) {
309 ExprResult R = buildOperatorCoawaitLookupExpr(SemaRef, S, Loc);
312 return buildOperatorCoawaitCall(SemaRef, Loc, E,
313 cast<UnresolvedLookupExpr>(R.get()));
316 static Expr *buildBuiltinCall(Sema &S, SourceLocation Loc, Builtin::ID Id,
317 MultiExprArg CallArgs) {
318 StringRef Name = S.Context.BuiltinInfo.getName(Id);
319 LookupResult R(S, &S.Context.Idents.get(Name), Loc, Sema::LookupOrdinaryName);
320 S.LookupName(R, S.TUScope, /*AllowBuiltinCreation=*/true);
322 auto *BuiltInDecl = R.getAsSingle<FunctionDecl>();
323 assert(BuiltInDecl && "failed to find builtin declaration");
326 S.BuildDeclRefExpr(BuiltInDecl, BuiltInDecl->getType(), VK_LValue, Loc);
327 assert(DeclRef.isUsable() && "Builtin reference cannot fail");
330 S.ActOnCallExpr(/*Scope=*/nullptr, DeclRef.get(), Loc, CallArgs, Loc);
332 assert(!Call.isInvalid() && "Call to builtin cannot fail!");
336 static ExprResult buildCoroutineHandle(Sema &S, QualType PromiseType,
337 SourceLocation Loc) {
338 QualType CoroHandleType = lookupCoroutineHandleType(S, PromiseType, Loc);
339 if (CoroHandleType.isNull())
342 DeclContext *LookupCtx = S.computeDeclContext(CoroHandleType);
343 LookupResult Found(S, &S.PP.getIdentifierTable().get("from_address"), Loc,
344 Sema::LookupOrdinaryName);
345 if (!S.LookupQualifiedName(Found, LookupCtx)) {
346 S.Diag(Loc, diag::err_coroutine_handle_missing_member)
352 buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_frame, {});
355 ExprResult FromAddr =
356 S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
357 if (FromAddr.isInvalid())
360 return S.ActOnCallExpr(nullptr, FromAddr.get(), Loc, FramePtr, Loc);
363 struct ReadySuspendResumeResult {
364 enum AwaitCallType { ACT_Ready, ACT_Suspend, ACT_Resume };
366 OpaqueValueExpr *OpaqueValue;
370 static ExprResult buildMemberCall(Sema &S, Expr *Base, SourceLocation Loc,
371 StringRef Name, MultiExprArg Args) {
372 DeclarationNameInfo NameInfo(&S.PP.getIdentifierTable().get(Name), Loc);
374 // FIXME: Fix BuildMemberReferenceExpr to take a const CXXScopeSpec&.
376 ExprResult Result = S.BuildMemberReferenceExpr(
377 Base, Base->getType(), Loc, /*IsPtr=*/false, SS,
378 SourceLocation(), nullptr, NameInfo, /*TemplateArgs=*/nullptr,
380 if (Result.isInvalid())
383 // We meant exactly what we asked for. No need for typo correction.
384 if (auto *TE = dyn_cast<TypoExpr>(Result.get())) {
385 S.clearDelayedTypo(TE);
386 S.Diag(Loc, diag::err_no_member)
387 << NameInfo.getName() << Base->getType()->getAsCXXRecordDecl()
388 << Base->getSourceRange();
392 return S.ActOnCallExpr(nullptr, Result.get(), Loc, Args, Loc, nullptr);
395 // See if return type is coroutine-handle and if so, invoke builtin coro-resume
396 // on its address. This is to enable experimental support for coroutine-handle
397 // returning await_suspend that results in a guaranteed tail call to the target
399 static Expr *maybeTailCall(Sema &S, QualType RetType, Expr *E,
400 SourceLocation Loc) {
401 if (RetType->isReferenceType())
403 Type const *T = RetType.getTypePtr();
404 if (!T->isClassType() && !T->isStructureType())
407 // FIXME: Add convertability check to coroutine_handle<>. Possibly via
408 // EvaluateBinaryTypeTrait(BTT_IsConvertible, ...) which is at the moment
409 // a private function in SemaExprCXX.cpp
411 ExprResult AddressExpr = buildMemberCall(S, E, Loc, "address", None);
412 if (AddressExpr.isInvalid())
415 Expr *JustAddress = AddressExpr.get();
416 // FIXME: Check that the type of AddressExpr is void*
417 return buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_resume,
421 /// Build calls to await_ready, await_suspend, and await_resume for a co_await
423 static ReadySuspendResumeResult buildCoawaitCalls(Sema &S, VarDecl *CoroPromise,
424 SourceLocation Loc, Expr *E) {
425 OpaqueValueExpr *Operand = new (S.Context)
426 OpaqueValueExpr(Loc, E->getType(), VK_LValue, E->getObjectKind(), E);
428 // Assume invalid until we see otherwise.
429 ReadySuspendResumeResult Calls = {{}, Operand, /*IsInvalid=*/true};
431 ExprResult CoroHandleRes = buildCoroutineHandle(S, CoroPromise->getType(), Loc);
432 if (CoroHandleRes.isInvalid())
434 Expr *CoroHandle = CoroHandleRes.get();
436 const StringRef Funcs[] = {"await_ready", "await_suspend", "await_resume"};
437 MultiExprArg Args[] = {None, CoroHandle, None};
438 for (size_t I = 0, N = llvm::array_lengthof(Funcs); I != N; ++I) {
439 ExprResult Result = buildMemberCall(S, Operand, Loc, Funcs[I], Args[I]);
440 if (Result.isInvalid())
442 Calls.Results[I] = Result.get();
445 // Assume the calls are valid; all further checking should make them invalid.
446 Calls.IsInvalid = false;
448 using ACT = ReadySuspendResumeResult::AwaitCallType;
449 CallExpr *AwaitReady = cast<CallExpr>(Calls.Results[ACT::ACT_Ready]);
450 if (!AwaitReady->getType()->isDependentType()) {
451 // [expr.await]p3 [...]
452 // — await-ready is the expression e.await_ready(), contextually converted
454 ExprResult Conv = S.PerformContextuallyConvertToBool(AwaitReady);
455 if (Conv.isInvalid()) {
456 S.Diag(AwaitReady->getDirectCallee()->getLocStart(),
457 diag::note_await_ready_no_bool_conversion);
458 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
459 << AwaitReady->getDirectCallee() << E->getSourceRange();
460 Calls.IsInvalid = true;
462 Calls.Results[ACT::ACT_Ready] = Conv.get();
464 CallExpr *AwaitSuspend = cast<CallExpr>(Calls.Results[ACT::ACT_Suspend]);
465 if (!AwaitSuspend->getType()->isDependentType()) {
466 // [expr.await]p3 [...]
467 // - await-suspend is the expression e.await_suspend(h), which shall be
468 // a prvalue of type void or bool.
469 QualType RetType = AwaitSuspend->getCallReturnType(S.Context);
471 // Experimental support for coroutine_handle returning await_suspend.
472 if (Expr *TailCallSuspend = maybeTailCall(S, RetType, AwaitSuspend, Loc))
473 Calls.Results[ACT::ACT_Suspend] = TailCallSuspend;
475 // non-class prvalues always have cv-unqualified types
476 if (RetType->isReferenceType() ||
477 (!RetType->isBooleanType() && !RetType->isVoidType())) {
478 S.Diag(AwaitSuspend->getCalleeDecl()->getLocation(),
479 diag::err_await_suspend_invalid_return_type)
481 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
482 << AwaitSuspend->getDirectCallee();
483 Calls.IsInvalid = true;
491 static ExprResult buildPromiseCall(Sema &S, VarDecl *Promise,
492 SourceLocation Loc, StringRef Name,
495 // Form a reference to the promise.
496 ExprResult PromiseRef = S.BuildDeclRefExpr(
497 Promise, Promise->getType().getNonReferenceType(), VK_LValue, Loc);
498 if (PromiseRef.isInvalid())
501 return buildMemberCall(S, PromiseRef.get(), Loc, Name, Args);
504 VarDecl *Sema::buildCoroutinePromise(SourceLocation Loc) {
505 assert(isa<FunctionDecl>(CurContext) && "not in a function scope");
506 auto *FD = cast<FunctionDecl>(CurContext);
507 bool IsThisDependentType = [&] {
508 if (auto *MD = dyn_cast_or_null<CXXMethodDecl>(FD))
509 return MD->isInstance() && MD->getThisType(Context)->isDependentType();
514 QualType T = FD->getType()->isDependentType() || IsThisDependentType
515 ? Context.DependentTy
516 : lookupPromiseType(*this, FD, Loc);
520 auto *VD = VarDecl::Create(Context, FD, FD->getLocation(), FD->getLocation(),
521 &PP.getIdentifierTable().get("__promise"), T,
522 Context.getTrivialTypeSourceInfo(T, Loc), SC_None);
523 CheckVariableDeclarationType(VD);
524 if (VD->isInvalidDecl())
527 auto *ScopeInfo = getCurFunction();
528 // Build a list of arguments, based on the coroutine functions arguments,
529 // that will be passed to the promise type's constructor.
530 llvm::SmallVector<Expr *, 4> CtorArgExprs;
532 // Add implicit object parameter.
533 if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) {
534 if (MD->isInstance() && !isLambdaCallOperator(MD)) {
535 ExprResult ThisExpr = ActOnCXXThis(Loc);
536 if (ThisExpr.isInvalid())
538 ThisExpr = CreateBuiltinUnaryOp(Loc, UO_Deref, ThisExpr.get());
539 if (ThisExpr.isInvalid())
541 CtorArgExprs.push_back(ThisExpr.get());
545 auto &Moves = ScopeInfo->CoroutineParameterMoves;
546 for (auto *PD : FD->parameters()) {
547 if (PD->getType()->isDependentType())
550 auto RefExpr = ExprEmpty();
551 auto Move = Moves.find(PD);
552 assert(Move != Moves.end() &&
553 "Coroutine function parameter not inserted into move map");
554 // If a reference to the function parameter exists in the coroutine
555 // frame, use that reference.
557 cast<VarDecl>(cast<DeclStmt>(Move->second)->getSingleDecl());
559 BuildDeclRefExpr(MoveDecl, MoveDecl->getType().getNonReferenceType(),
560 ExprValueKind::VK_LValue, FD->getLocation());
561 if (RefExpr.isInvalid())
563 CtorArgExprs.push_back(RefExpr.get());
566 // Create an initialization sequence for the promise type using the
567 // constructor arguments, wrapped in a parenthesized list expression.
568 Expr *PLE = new (Context) ParenListExpr(Context, FD->getLocation(),
569 CtorArgExprs, FD->getLocation());
570 InitializedEntity Entity = InitializedEntity::InitializeVariable(VD);
571 InitializationKind Kind = InitializationKind::CreateForInit(
572 VD->getLocation(), /*DirectInit=*/true, PLE);
573 InitializationSequence InitSeq(*this, Entity, Kind, CtorArgExprs,
574 /*TopLevelOfInitList=*/false,
575 /*TreatUnavailableAsInvalid=*/false);
577 // Attempt to initialize the promise type with the arguments.
578 // If that fails, fall back to the promise type's default constructor.
580 ExprResult Result = InitSeq.Perform(*this, Entity, Kind, CtorArgExprs);
581 if (Result.isInvalid()) {
582 VD->setInvalidDecl();
583 } else if (Result.get()) {
584 VD->setInit(MaybeCreateExprWithCleanups(Result.get()));
585 VD->setInitStyle(VarDecl::CallInit);
586 CheckCompleteVariableDeclaration(VD);
589 ActOnUninitializedDecl(VD);
595 /// Check that this is a context in which a coroutine suspension can appear.
596 static FunctionScopeInfo *checkCoroutineContext(Sema &S, SourceLocation Loc,
598 bool IsImplicit = false) {
599 if (!isValidCoroutineContext(S, Loc, Keyword))
602 assert(isa<FunctionDecl>(S.CurContext) && "not in a function scope");
604 auto *ScopeInfo = S.getCurFunction();
605 assert(ScopeInfo && "missing function scope for function");
607 if (ScopeInfo->FirstCoroutineStmtLoc.isInvalid() && !IsImplicit)
608 ScopeInfo->setFirstCoroutineStmt(Loc, Keyword);
610 if (ScopeInfo->CoroutinePromise)
613 if (!S.buildCoroutineParameterMoves(Loc))
616 ScopeInfo->CoroutinePromise = S.buildCoroutinePromise(Loc);
617 if (!ScopeInfo->CoroutinePromise)
623 bool Sema::ActOnCoroutineBodyStart(Scope *SC, SourceLocation KWLoc,
625 if (!checkCoroutineContext(*this, KWLoc, Keyword))
627 auto *ScopeInfo = getCurFunction();
628 assert(ScopeInfo->CoroutinePromise);
630 // If we have existing coroutine statements then we have already built
631 // the initial and final suspend points.
632 if (!ScopeInfo->NeedsCoroutineSuspends)
635 ScopeInfo->setNeedsCoroutineSuspends(false);
637 auto *Fn = cast<FunctionDecl>(CurContext);
638 SourceLocation Loc = Fn->getLocation();
639 // Build the initial suspend point
640 auto buildSuspends = [&](StringRef Name) mutable -> StmtResult {
642 buildPromiseCall(*this, ScopeInfo->CoroutinePromise, Loc, Name, None);
643 if (Suspend.isInvalid())
645 Suspend = buildOperatorCoawaitCall(*this, SC, Loc, Suspend.get());
646 if (Suspend.isInvalid())
648 Suspend = BuildResolvedCoawaitExpr(Loc, Suspend.get(),
649 /*IsImplicit*/ true);
650 Suspend = ActOnFinishFullExpr(Suspend.get());
651 if (Suspend.isInvalid()) {
652 Diag(Loc, diag::note_coroutine_promise_suspend_implicitly_required)
653 << ((Name == "initial_suspend") ? 0 : 1);
654 Diag(KWLoc, diag::note_declared_coroutine_here) << Keyword;
657 return cast<Stmt>(Suspend.get());
660 StmtResult InitSuspend = buildSuspends("initial_suspend");
661 if (InitSuspend.isInvalid())
664 StmtResult FinalSuspend = buildSuspends("final_suspend");
665 if (FinalSuspend.isInvalid())
668 ScopeInfo->setCoroutineSuspends(InitSuspend.get(), FinalSuspend.get());
673 ExprResult Sema::ActOnCoawaitExpr(Scope *S, SourceLocation Loc, Expr *E) {
674 if (!ActOnCoroutineBodyStart(S, Loc, "co_await")) {
675 CorrectDelayedTyposInExpr(E);
679 if (E->getType()->isPlaceholderType()) {
680 ExprResult R = CheckPlaceholderExpr(E);
681 if (R.isInvalid()) return ExprError();
684 ExprResult Lookup = buildOperatorCoawaitLookupExpr(*this, S, Loc);
685 if (Lookup.isInvalid())
687 return BuildUnresolvedCoawaitExpr(Loc, E,
688 cast<UnresolvedLookupExpr>(Lookup.get()));
691 ExprResult Sema::BuildUnresolvedCoawaitExpr(SourceLocation Loc, Expr *E,
692 UnresolvedLookupExpr *Lookup) {
693 auto *FSI = checkCoroutineContext(*this, Loc, "co_await");
697 if (E->getType()->isPlaceholderType()) {
698 ExprResult R = CheckPlaceholderExpr(E);
704 auto *Promise = FSI->CoroutinePromise;
705 if (Promise->getType()->isDependentType()) {
707 new (Context) DependentCoawaitExpr(Loc, Context.DependentTy, E, Lookup);
711 auto *RD = Promise->getType()->getAsCXXRecordDecl();
712 if (lookupMember(*this, "await_transform", RD, Loc)) {
713 ExprResult R = buildPromiseCall(*this, Promise, Loc, "await_transform", E);
716 diag::note_coroutine_promise_implicit_await_transform_required_here)
717 << E->getSourceRange();
722 ExprResult Awaitable = buildOperatorCoawaitCall(*this, Loc, E, Lookup);
723 if (Awaitable.isInvalid())
726 return BuildResolvedCoawaitExpr(Loc, Awaitable.get());
729 ExprResult Sema::BuildResolvedCoawaitExpr(SourceLocation Loc, Expr *E,
731 auto *Coroutine = checkCoroutineContext(*this, Loc, "co_await", IsImplicit);
735 if (E->getType()->isPlaceholderType()) {
736 ExprResult R = CheckPlaceholderExpr(E);
737 if (R.isInvalid()) return ExprError();
741 if (E->getType()->isDependentType()) {
742 Expr *Res = new (Context)
743 CoawaitExpr(Loc, Context.DependentTy, E, IsImplicit);
747 // If the expression is a temporary, materialize it as an lvalue so that we
748 // can use it multiple times.
749 if (E->getValueKind() == VK_RValue)
750 E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
752 // The location of the `co_await` token cannot be used when constructing
753 // the member call expressions since it's before the location of `Expr`, which
754 // is used as the start of the member call expression.
755 SourceLocation CallLoc = E->getExprLoc();
757 // Build the await_ready, await_suspend, await_resume calls.
758 ReadySuspendResumeResult RSS =
759 buildCoawaitCalls(*this, Coroutine->CoroutinePromise, CallLoc, E);
764 new (Context) CoawaitExpr(Loc, E, RSS.Results[0], RSS.Results[1],
765 RSS.Results[2], RSS.OpaqueValue, IsImplicit);
770 ExprResult Sema::ActOnCoyieldExpr(Scope *S, SourceLocation Loc, Expr *E) {
771 if (!ActOnCoroutineBodyStart(S, Loc, "co_yield")) {
772 CorrectDelayedTyposInExpr(E);
776 // Build yield_value call.
777 ExprResult Awaitable = buildPromiseCall(
778 *this, getCurFunction()->CoroutinePromise, Loc, "yield_value", E);
779 if (Awaitable.isInvalid())
782 // Build 'operator co_await' call.
783 Awaitable = buildOperatorCoawaitCall(*this, S, Loc, Awaitable.get());
784 if (Awaitable.isInvalid())
787 return BuildCoyieldExpr(Loc, Awaitable.get());
789 ExprResult Sema::BuildCoyieldExpr(SourceLocation Loc, Expr *E) {
790 auto *Coroutine = checkCoroutineContext(*this, Loc, "co_yield");
794 if (E->getType()->isPlaceholderType()) {
795 ExprResult R = CheckPlaceholderExpr(E);
796 if (R.isInvalid()) return ExprError();
800 if (E->getType()->isDependentType()) {
801 Expr *Res = new (Context) CoyieldExpr(Loc, Context.DependentTy, E);
805 // If the expression is a temporary, materialize it as an lvalue so that we
806 // can use it multiple times.
807 if (E->getValueKind() == VK_RValue)
808 E = CreateMaterializeTemporaryExpr(E->getType(), E, true);
810 // Build the await_ready, await_suspend, await_resume calls.
811 ReadySuspendResumeResult RSS =
812 buildCoawaitCalls(*this, Coroutine->CoroutinePromise, Loc, E);
817 new (Context) CoyieldExpr(Loc, E, RSS.Results[0], RSS.Results[1],
818 RSS.Results[2], RSS.OpaqueValue);
823 StmtResult Sema::ActOnCoreturnStmt(Scope *S, SourceLocation Loc, Expr *E) {
824 if (!ActOnCoroutineBodyStart(S, Loc, "co_return")) {
825 CorrectDelayedTyposInExpr(E);
828 return BuildCoreturnStmt(Loc, E);
831 StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E,
833 auto *FSI = checkCoroutineContext(*this, Loc, "co_return", IsImplicit);
837 if (E && E->getType()->isPlaceholderType() &&
838 !E->getType()->isSpecificPlaceholderType(BuiltinType::Overload)) {
839 ExprResult R = CheckPlaceholderExpr(E);
840 if (R.isInvalid()) return StmtError();
844 // FIXME: If the operand is a reference to a variable that's about to go out
845 // of scope, we should treat the operand as an xvalue for this overload
847 VarDecl *Promise = FSI->CoroutinePromise;
849 if (E && (isa<InitListExpr>(E) || !E->getType()->isVoidType())) {
850 PC = buildPromiseCall(*this, Promise, Loc, "return_value", E);
852 E = MakeFullDiscardedValueExpr(E).get();
853 PC = buildPromiseCall(*this, Promise, Loc, "return_void", None);
858 Expr *PCE = ActOnFinishFullExpr(PC.get()).get();
860 Stmt *Res = new (Context) CoreturnStmt(Loc, E, PCE, IsImplicit);
864 /// Look up the std::nothrow object.
865 static Expr *buildStdNoThrowDeclRef(Sema &S, SourceLocation Loc) {
866 NamespaceDecl *Std = S.getStdNamespace();
867 assert(Std && "Should already be diagnosed");
869 LookupResult Result(S, &S.PP.getIdentifierTable().get("nothrow"), Loc,
870 Sema::LookupOrdinaryName);
871 if (!S.LookupQualifiedName(Result, Std)) {
872 // FIXME: <experimental/coroutine> should have been included already.
873 // If we require it to include <new> then this diagnostic is no longer
875 S.Diag(Loc, diag::err_implicit_coroutine_std_nothrow_type_not_found);
879 auto *VD = Result.getAsSingle<VarDecl>();
881 Result.suppressDiagnostics();
882 // We found something weird. Complain about the first thing we found.
883 NamedDecl *Found = *Result.begin();
884 S.Diag(Found->getLocation(), diag::err_malformed_std_nothrow);
888 ExprResult DR = S.BuildDeclRefExpr(VD, VD->getType(), VK_LValue, Loc);
895 // Find an appropriate delete for the promise.
896 static FunctionDecl *findDeleteForPromise(Sema &S, SourceLocation Loc,
897 QualType PromiseType) {
898 FunctionDecl *OperatorDelete = nullptr;
900 DeclarationName DeleteName =
901 S.Context.DeclarationNames.getCXXOperatorName(OO_Delete);
903 auto *PointeeRD = PromiseType->getAsCXXRecordDecl();
904 assert(PointeeRD && "PromiseType must be a CxxRecordDecl type");
906 if (S.FindDeallocationFunction(Loc, PointeeRD, DeleteName, OperatorDelete))
909 if (!OperatorDelete) {
910 // Look for a global declaration.
911 const bool CanProvideSize = S.isCompleteType(Loc, PromiseType);
912 const bool Overaligned = false;
913 OperatorDelete = S.FindUsualDeallocationFunction(Loc, CanProvideSize,
914 Overaligned, DeleteName);
916 S.MarkFunctionReferenced(Loc, OperatorDelete);
917 return OperatorDelete;
921 void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body) {
922 FunctionScopeInfo *Fn = getCurFunction();
923 assert(Fn && Fn->isCoroutine() && "not a coroutine");
925 assert(FD->isInvalidDecl() &&
926 "a null body is only allowed for invalid declarations");
929 // We have a function that uses coroutine keywords, but we failed to build
931 if (!Fn->CoroutinePromise)
932 return FD->setInvalidDecl();
934 if (isa<CoroutineBodyStmt>(Body)) {
935 // Nothing todo. the body is already a transformed coroutine body statement.
939 // Coroutines [stmt.return]p1:
940 // A return statement shall not appear in a coroutine.
941 if (Fn->FirstReturnLoc.isValid()) {
942 assert(Fn->FirstCoroutineStmtLoc.isValid() &&
943 "first coroutine location not set");
944 Diag(Fn->FirstReturnLoc, diag::err_return_in_coroutine);
945 Diag(Fn->FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
946 << Fn->getFirstCoroutineStmtKeyword();
948 CoroutineStmtBuilder Builder(*this, *FD, *Fn, Body);
949 if (Builder.isInvalid() || !Builder.buildStatements())
950 return FD->setInvalidDecl();
952 // Build body for the coroutine wrapper statement.
953 Body = CoroutineBodyStmt::Create(Context, Builder);
956 CoroutineStmtBuilder::CoroutineStmtBuilder(Sema &S, FunctionDecl &FD,
957 sema::FunctionScopeInfo &Fn,
959 : S(S), FD(FD), Fn(Fn), Loc(FD.getLocation()),
960 IsPromiseDependentType(
961 !Fn.CoroutinePromise ||
962 Fn.CoroutinePromise->getType()->isDependentType()) {
965 for (auto KV : Fn.CoroutineParameterMoves)
966 this->ParamMovesVector.push_back(KV.second);
967 this->ParamMoves = this->ParamMovesVector;
969 if (!IsPromiseDependentType) {
970 PromiseRecordDecl = Fn.CoroutinePromise->getType()->getAsCXXRecordDecl();
971 assert(PromiseRecordDecl && "Type should have already been checked");
973 this->IsValid = makePromiseStmt() && makeInitialAndFinalSuspend();
976 bool CoroutineStmtBuilder::buildStatements() {
977 assert(this->IsValid && "coroutine already invalid");
978 this->IsValid = makeReturnObject();
979 if (this->IsValid && !IsPromiseDependentType)
980 buildDependentStatements();
981 return this->IsValid;
984 bool CoroutineStmtBuilder::buildDependentStatements() {
985 assert(this->IsValid && "coroutine already invalid");
986 assert(!this->IsPromiseDependentType &&
987 "coroutine cannot have a dependent promise type");
988 this->IsValid = makeOnException() && makeOnFallthrough() &&
989 makeGroDeclAndReturnStmt() && makeReturnOnAllocFailure() &&
990 makeNewAndDeleteExpr();
991 return this->IsValid;
994 bool CoroutineStmtBuilder::makePromiseStmt() {
995 // Form a declaration statement for the promise declaration, so that AST
996 // visitors can more easily find it.
997 StmtResult PromiseStmt =
998 S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(Fn.CoroutinePromise), Loc, Loc);
999 if (PromiseStmt.isInvalid())
1002 this->Promise = PromiseStmt.get();
1006 bool CoroutineStmtBuilder::makeInitialAndFinalSuspend() {
1007 if (Fn.hasInvalidCoroutineSuspends())
1009 this->InitialSuspend = cast<Expr>(Fn.CoroutineSuspends.first);
1010 this->FinalSuspend = cast<Expr>(Fn.CoroutineSuspends.second);
1014 static bool diagReturnOnAllocFailure(Sema &S, Expr *E,
1015 CXXRecordDecl *PromiseRecordDecl,
1016 FunctionScopeInfo &Fn) {
1017 auto Loc = E->getExprLoc();
1018 if (auto *DeclRef = dyn_cast_or_null<DeclRefExpr>(E)) {
1019 auto *Decl = DeclRef->getDecl();
1020 if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(Decl)) {
1021 if (Method->isStatic())
1024 Loc = Decl->getLocation();
1030 diag::err_coroutine_promise_get_return_object_on_allocation_failure)
1031 << PromiseRecordDecl;
1032 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1033 << Fn.getFirstCoroutineStmtKeyword();
1037 bool CoroutineStmtBuilder::makeReturnOnAllocFailure() {
1038 assert(!IsPromiseDependentType &&
1039 "cannot make statement while the promise type is dependent");
1041 // [dcl.fct.def.coroutine]/8
1042 // The unqualified-id get_return_object_on_allocation_failure is looked up in
1043 // the scope of class P by class member access lookup (3.4.5). ...
1044 // If an allocation function returns nullptr, ... the coroutine return value
1045 // is obtained by a call to ... get_return_object_on_allocation_failure().
1047 DeclarationName DN =
1048 S.PP.getIdentifierInfo("get_return_object_on_allocation_failure");
1049 LookupResult Found(S, DN, Loc, Sema::LookupMemberName);
1050 if (!S.LookupQualifiedName(Found, PromiseRecordDecl))
1054 ExprResult DeclNameExpr =
1055 S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false);
1056 if (DeclNameExpr.isInvalid())
1059 if (!diagReturnOnAllocFailure(S, DeclNameExpr.get(), PromiseRecordDecl, Fn))
1062 ExprResult ReturnObjectOnAllocationFailure =
1063 S.ActOnCallExpr(nullptr, DeclNameExpr.get(), Loc, {}, Loc);
1064 if (ReturnObjectOnAllocationFailure.isInvalid())
1067 StmtResult ReturnStmt =
1068 S.BuildReturnStmt(Loc, ReturnObjectOnAllocationFailure.get());
1069 if (ReturnStmt.isInvalid()) {
1070 S.Diag(Found.getFoundDecl()->getLocation(), diag::note_member_declared_here)
1072 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1073 << Fn.getFirstCoroutineStmtKeyword();
1077 this->ReturnStmtOnAllocFailure = ReturnStmt.get();
1081 bool CoroutineStmtBuilder::makeNewAndDeleteExpr() {
1082 // Form and check allocation and deallocation calls.
1083 assert(!IsPromiseDependentType &&
1084 "cannot make statement while the promise type is dependent");
1085 QualType PromiseType = Fn.CoroutinePromise->getType();
1087 if (S.RequireCompleteType(Loc, PromiseType, diag::err_incomplete_type))
1090 const bool RequiresNoThrowAlloc = ReturnStmtOnAllocFailure != nullptr;
1092 // [dcl.fct.def.coroutine]/7
1093 // Lookup allocation functions using a parameter list composed of the
1094 // requested size of the coroutine state being allocated, followed by
1095 // the coroutine function's arguments. If a matching allocation function
1096 // exists, use it. Otherwise, use an allocation function that just takes
1097 // the requested size.
1099 FunctionDecl *OperatorNew = nullptr;
1100 FunctionDecl *OperatorDelete = nullptr;
1101 FunctionDecl *UnusedResult = nullptr;
1102 bool PassAlignment = false;
1103 SmallVector<Expr *, 1> PlacementArgs;
1105 // [dcl.fct.def.coroutine]/7
1106 // "The allocation function’s name is looked up in the scope of P.
1107 // [...] If the lookup finds an allocation function in the scope of P,
1108 // overload resolution is performed on a function call created by assembling
1109 // an argument list. The first argument is the amount of space requested,
1110 // and has type std::size_t. The lvalues p1 ... pn are the succeeding
1113 // ...where "p1 ... pn" are defined earlier as:
1115 // [dcl.fct.def.coroutine]/3
1116 // "For a coroutine f that is a non-static member function, let P1 denote the
1117 // type of the implicit object parameter (13.3.1) and P2 ... Pn be the types
1118 // of the function parameters; otherwise let P1 ... Pn be the types of the
1119 // function parameters. Let p1 ... pn be lvalues denoting those objects."
1120 if (auto *MD = dyn_cast<CXXMethodDecl>(&FD)) {
1121 if (MD->isInstance() && !isLambdaCallOperator(MD)) {
1122 ExprResult ThisExpr = S.ActOnCXXThis(Loc);
1123 if (ThisExpr.isInvalid())
1125 ThisExpr = S.CreateBuiltinUnaryOp(Loc, UO_Deref, ThisExpr.get());
1126 if (ThisExpr.isInvalid())
1128 PlacementArgs.push_back(ThisExpr.get());
1131 for (auto *PD : FD.parameters()) {
1132 if (PD->getType()->isDependentType())
1135 // Build a reference to the parameter.
1136 auto PDLoc = PD->getLocation();
1137 ExprResult PDRefExpr =
1138 S.BuildDeclRefExpr(PD, PD->getOriginalType().getNonReferenceType(),
1139 ExprValueKind::VK_LValue, PDLoc);
1140 if (PDRefExpr.isInvalid())
1143 PlacementArgs.push_back(PDRefExpr.get());
1145 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Class,
1146 /*DeleteScope*/ Sema::AFS_Both, PromiseType,
1147 /*isArray*/ false, PassAlignment, PlacementArgs,
1148 OperatorNew, UnusedResult, /*Diagnose*/ false);
1150 // [dcl.fct.def.coroutine]/7
1151 // "If no matching function is found, overload resolution is performed again
1152 // on a function call created by passing just the amount of space required as
1153 // an argument of type std::size_t."
1154 if (!OperatorNew && !PlacementArgs.empty()) {
1155 PlacementArgs.clear();
1156 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Class,
1157 /*DeleteScope*/ Sema::AFS_Both, PromiseType,
1158 /*isArray*/ false, PassAlignment, PlacementArgs,
1159 OperatorNew, UnusedResult, /*Diagnose*/ false);
1162 // [dcl.fct.def.coroutine]/7
1163 // "The allocation function’s name is looked up in the scope of P. If this
1164 // lookup fails, the allocation function’s name is looked up in the global
1167 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Global,
1168 /*DeleteScope*/ Sema::AFS_Both, PromiseType,
1169 /*isArray*/ false, PassAlignment, PlacementArgs,
1170 OperatorNew, UnusedResult);
1173 bool IsGlobalOverload =
1174 OperatorNew && !isa<CXXRecordDecl>(OperatorNew->getDeclContext());
1175 // If we didn't find a class-local new declaration and non-throwing new
1176 // was is required then we need to lookup the non-throwing global operator
1178 if (RequiresNoThrowAlloc && (!OperatorNew || IsGlobalOverload)) {
1179 auto *StdNoThrow = buildStdNoThrowDeclRef(S, Loc);
1182 PlacementArgs = {StdNoThrow};
1183 OperatorNew = nullptr;
1184 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Both,
1185 /*DeleteScope*/ Sema::AFS_Both, PromiseType,
1186 /*isArray*/ false, PassAlignment, PlacementArgs,
1187 OperatorNew, UnusedResult);
1193 if (RequiresNoThrowAlloc) {
1194 const auto *FT = OperatorNew->getType()->getAs<FunctionProtoType>();
1195 if (!FT->isNothrow(/*ResultIfDependent*/ false)) {
1196 S.Diag(OperatorNew->getLocation(),
1197 diag::err_coroutine_promise_new_requires_nothrow)
1199 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
1205 if ((OperatorDelete = findDeleteForPromise(S, Loc, PromiseType)) == nullptr)
1209 buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_frame, {});
1212 buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_size, {});
1217 S.BuildDeclRefExpr(OperatorNew, OperatorNew->getType(), VK_LValue, Loc);
1218 if (NewRef.isInvalid())
1221 SmallVector<Expr *, 2> NewArgs(1, FrameSize);
1222 for (auto Arg : PlacementArgs)
1223 NewArgs.push_back(Arg);
1225 ExprResult NewExpr =
1226 S.ActOnCallExpr(S.getCurScope(), NewRef.get(), Loc, NewArgs, Loc);
1227 NewExpr = S.ActOnFinishFullExpr(NewExpr.get());
1228 if (NewExpr.isInvalid())
1231 // Make delete call.
1233 QualType OpDeleteQualType = OperatorDelete->getType();
1235 ExprResult DeleteRef =
1236 S.BuildDeclRefExpr(OperatorDelete, OpDeleteQualType, VK_LValue, Loc);
1237 if (DeleteRef.isInvalid())
1241 buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_free, {FramePtr});
1243 SmallVector<Expr *, 2> DeleteArgs{CoroFree};
1245 // Check if we need to pass the size.
1246 const auto *OpDeleteType =
1247 OpDeleteQualType.getTypePtr()->getAs<FunctionProtoType>();
1248 if (OpDeleteType->getNumParams() > 1)
1249 DeleteArgs.push_back(FrameSize);
1251 ExprResult DeleteExpr =
1252 S.ActOnCallExpr(S.getCurScope(), DeleteRef.get(), Loc, DeleteArgs, Loc);
1253 DeleteExpr = S.ActOnFinishFullExpr(DeleteExpr.get());
1254 if (DeleteExpr.isInvalid())
1257 this->Allocate = NewExpr.get();
1258 this->Deallocate = DeleteExpr.get();
1263 bool CoroutineStmtBuilder::makeOnFallthrough() {
1264 assert(!IsPromiseDependentType &&
1265 "cannot make statement while the promise type is dependent");
1267 // [dcl.fct.def.coroutine]/4
1268 // The unqualified-ids 'return_void' and 'return_value' are looked up in
1269 // the scope of class P. If both are found, the program is ill-formed.
1270 bool HasRVoid, HasRValue;
1271 LookupResult LRVoid =
1272 lookupMember(S, "return_void", PromiseRecordDecl, Loc, HasRVoid);
1273 LookupResult LRValue =
1274 lookupMember(S, "return_value", PromiseRecordDecl, Loc, HasRValue);
1276 StmtResult Fallthrough;
1277 if (HasRVoid && HasRValue) {
1278 // FIXME Improve this diagnostic
1279 S.Diag(FD.getLocation(),
1280 diag::err_coroutine_promise_incompatible_return_functions)
1281 << PromiseRecordDecl;
1282 S.Diag(LRVoid.getRepresentativeDecl()->getLocation(),
1283 diag::note_member_first_declared_here)
1284 << LRVoid.getLookupName();
1285 S.Diag(LRValue.getRepresentativeDecl()->getLocation(),
1286 diag::note_member_first_declared_here)
1287 << LRValue.getLookupName();
1289 } else if (!HasRVoid && !HasRValue) {
1290 // FIXME: The PDTS currently specifies this case as UB, not ill-formed.
1291 // However we still diagnose this as an error since until the PDTS is fixed.
1292 S.Diag(FD.getLocation(),
1293 diag::err_coroutine_promise_requires_return_function)
1294 << PromiseRecordDecl;
1295 S.Diag(PromiseRecordDecl->getLocation(), diag::note_defined_here)
1296 << PromiseRecordDecl;
1298 } else if (HasRVoid) {
1299 // If the unqualified-id return_void is found, flowing off the end of a
1300 // coroutine is equivalent to a co_return with no operand. Otherwise,
1301 // flowing off the end of a coroutine results in undefined behavior.
1302 Fallthrough = S.BuildCoreturnStmt(FD.getLocation(), nullptr,
1303 /*IsImplicit*/false);
1304 Fallthrough = S.ActOnFinishFullStmt(Fallthrough.get());
1305 if (Fallthrough.isInvalid())
1309 this->OnFallthrough = Fallthrough.get();
1313 bool CoroutineStmtBuilder::makeOnException() {
1314 // Try to form 'p.unhandled_exception();'
1315 assert(!IsPromiseDependentType &&
1316 "cannot make statement while the promise type is dependent");
1318 const bool RequireUnhandledException = S.getLangOpts().CXXExceptions;
1320 if (!lookupMember(S, "unhandled_exception", PromiseRecordDecl, Loc)) {
1322 RequireUnhandledException
1323 ? diag::err_coroutine_promise_unhandled_exception_required
1325 warn_coroutine_promise_unhandled_exception_required_with_exceptions;
1326 S.Diag(Loc, DiagID) << PromiseRecordDecl;
1327 S.Diag(PromiseRecordDecl->getLocation(), diag::note_defined_here)
1328 << PromiseRecordDecl;
1329 return !RequireUnhandledException;
1332 // If exceptions are disabled, don't try to build OnException.
1333 if (!S.getLangOpts().CXXExceptions)
1336 ExprResult UnhandledException = buildPromiseCall(S, Fn.CoroutinePromise, Loc,
1337 "unhandled_exception", None);
1338 UnhandledException = S.ActOnFinishFullExpr(UnhandledException.get(), Loc);
1339 if (UnhandledException.isInvalid())
1342 // Since the body of the coroutine will be wrapped in try-catch, it will
1343 // be incompatible with SEH __try if present in a function.
1344 if (!S.getLangOpts().Borland && Fn.FirstSEHTryLoc.isValid()) {
1345 S.Diag(Fn.FirstSEHTryLoc, diag::err_seh_in_a_coroutine_with_cxx_exceptions);
1346 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1347 << Fn.getFirstCoroutineStmtKeyword();
1351 this->OnException = UnhandledException.get();
1355 bool CoroutineStmtBuilder::makeReturnObject() {
1356 // Build implicit 'p.get_return_object()' expression and form initialization
1357 // of return type from it.
1358 ExprResult ReturnObject =
1359 buildPromiseCall(S, Fn.CoroutinePromise, Loc, "get_return_object", None);
1360 if (ReturnObject.isInvalid())
1363 this->ReturnValue = ReturnObject.get();
1367 static void noteMemberDeclaredHere(Sema &S, Expr *E, FunctionScopeInfo &Fn) {
1368 if (auto *MbrRef = dyn_cast<CXXMemberCallExpr>(E)) {
1369 auto *MethodDecl = MbrRef->getMethodDecl();
1370 S.Diag(MethodDecl->getLocation(), diag::note_member_declared_here)
1373 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1374 << Fn.getFirstCoroutineStmtKeyword();
1377 bool CoroutineStmtBuilder::makeGroDeclAndReturnStmt() {
1378 assert(!IsPromiseDependentType &&
1379 "cannot make statement while the promise type is dependent");
1380 assert(this->ReturnValue && "ReturnValue must be already formed");
1382 QualType const GroType = this->ReturnValue->getType();
1383 assert(!GroType->isDependentType() &&
1384 "get_return_object type must no longer be dependent");
1386 QualType const FnRetType = FD.getReturnType();
1387 assert(!FnRetType->isDependentType() &&
1388 "get_return_object type must no longer be dependent");
1390 if (FnRetType->isVoidType()) {
1391 ExprResult Res = S.ActOnFinishFullExpr(this->ReturnValue, Loc);
1392 if (Res.isInvalid())
1395 this->ResultDecl = Res.get();
1399 if (GroType->isVoidType()) {
1400 // Trigger a nice error message.
1401 InitializedEntity Entity =
1402 InitializedEntity::InitializeResult(Loc, FnRetType, false);
1403 S.PerformMoveOrCopyInitialization(Entity, nullptr, FnRetType, ReturnValue);
1404 noteMemberDeclaredHere(S, ReturnValue, Fn);
1408 auto *GroDecl = VarDecl::Create(
1409 S.Context, &FD, FD.getLocation(), FD.getLocation(),
1410 &S.PP.getIdentifierTable().get("__coro_gro"), GroType,
1411 S.Context.getTrivialTypeSourceInfo(GroType, Loc), SC_None);
1413 S.CheckVariableDeclarationType(GroDecl);
1414 if (GroDecl->isInvalidDecl())
1417 InitializedEntity Entity = InitializedEntity::InitializeVariable(GroDecl);
1418 ExprResult Res = S.PerformMoveOrCopyInitialization(Entity, nullptr, GroType,
1420 if (Res.isInvalid())
1423 Res = S.ActOnFinishFullExpr(Res.get());
1424 if (Res.isInvalid())
1427 S.AddInitializerToDecl(GroDecl, Res.get(),
1428 /*DirectInit=*/false);
1430 S.FinalizeDeclaration(GroDecl);
1432 // Form a declaration statement for the return declaration, so that AST
1433 // visitors can more easily find it.
1434 StmtResult GroDeclStmt =
1435 S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(GroDecl), Loc, Loc);
1436 if (GroDeclStmt.isInvalid())
1439 this->ResultDecl = GroDeclStmt.get();
1441 ExprResult declRef = S.BuildDeclRefExpr(GroDecl, GroType, VK_LValue, Loc);
1442 if (declRef.isInvalid())
1445 StmtResult ReturnStmt = S.BuildReturnStmt(Loc, declRef.get());
1446 if (ReturnStmt.isInvalid()) {
1447 noteMemberDeclaredHere(S, ReturnValue, Fn);
1450 if (cast<clang::ReturnStmt>(ReturnStmt.get())->getNRVOCandidate() == GroDecl)
1451 GroDecl->setNRVOVariable(true);
1453 this->ReturnStmt = ReturnStmt.get();
1457 // Create a static_cast\<T&&>(expr).
1458 static Expr *castForMoving(Sema &S, Expr *E, QualType T = QualType()) {
1461 QualType TargetType = S.BuildReferenceType(
1462 T, /*SpelledAsLValue*/ false, SourceLocation(), DeclarationName());
1463 SourceLocation ExprLoc = E->getLocStart();
1464 TypeSourceInfo *TargetLoc =
1465 S.Context.getTrivialTypeSourceInfo(TargetType, ExprLoc);
1468 .BuildCXXNamedCast(ExprLoc, tok::kw_static_cast, TargetLoc, E,
1469 SourceRange(ExprLoc, ExprLoc), E->getSourceRange())
1473 /// Build a variable declaration for move parameter.
1474 static VarDecl *buildVarDecl(Sema &S, SourceLocation Loc, QualType Type,
1475 IdentifierInfo *II) {
1476 TypeSourceInfo *TInfo = S.Context.getTrivialTypeSourceInfo(Type, Loc);
1477 VarDecl *Decl = VarDecl::Create(S.Context, S.CurContext, Loc, Loc, II, Type,
1479 Decl->setImplicit();
1483 // Build statements that move coroutine function parameters to the coroutine
1484 // frame, and store them on the function scope info.
1485 bool Sema::buildCoroutineParameterMoves(SourceLocation Loc) {
1486 assert(isa<FunctionDecl>(CurContext) && "not in a function scope");
1487 auto *FD = cast<FunctionDecl>(CurContext);
1489 auto *ScopeInfo = getCurFunction();
1490 assert(ScopeInfo->CoroutineParameterMoves.empty() &&
1491 "Should not build parameter moves twice");
1493 for (auto *PD : FD->parameters()) {
1494 if (PD->getType()->isDependentType())
1497 ExprResult PDRefExpr =
1498 BuildDeclRefExpr(PD, PD->getType().getNonReferenceType(),
1499 ExprValueKind::VK_LValue, Loc); // FIXME: scope?
1500 if (PDRefExpr.isInvalid())
1503 Expr *CExpr = nullptr;
1504 if (PD->getType()->getAsCXXRecordDecl() ||
1505 PD->getType()->isRValueReferenceType())
1506 CExpr = castForMoving(*this, PDRefExpr.get());
1508 CExpr = PDRefExpr.get();
1510 auto D = buildVarDecl(*this, Loc, PD->getType(), PD->getIdentifier());
1511 AddInitializerToDecl(D, CExpr, /*DirectInit=*/true);
1513 // Convert decl to a statement.
1514 StmtResult Stmt = ActOnDeclStmt(ConvertDeclToDeclGroup(D), Loc, Loc);
1515 if (Stmt.isInvalid())
1518 ScopeInfo->CoroutineParameterMoves.insert(std::make_pair(PD, Stmt.get()));
1523 StmtResult Sema::BuildCoroutineBodyStmt(CoroutineBodyStmt::CtorArgs Args) {
1524 CoroutineBodyStmt *Res = CoroutineBodyStmt::Create(Context, Args);
1530 ClassTemplateDecl *Sema::lookupCoroutineTraits(SourceLocation KwLoc,
1531 SourceLocation FuncLoc) {
1532 if (!StdCoroutineTraitsCache) {
1533 if (auto StdExp = lookupStdExperimentalNamespace()) {
1534 LookupResult Result(*this,
1535 &PP.getIdentifierTable().get("coroutine_traits"),
1536 FuncLoc, LookupOrdinaryName);
1537 if (!LookupQualifiedName(Result, StdExp)) {
1538 Diag(KwLoc, diag::err_implied_coroutine_type_not_found)
1539 << "std::experimental::coroutine_traits";
1542 if (!(StdCoroutineTraitsCache =
1543 Result.getAsSingle<ClassTemplateDecl>())) {
1544 Result.suppressDiagnostics();
1545 NamedDecl *Found = *Result.begin();
1546 Diag(Found->getLocation(), diag::err_malformed_std_coroutine_traits);
1551 return StdCoroutineTraitsCache;