1//===-- SemaCoroutine.cpp - Semantic Analysis for Coroutines --------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements semantic analysis for C++ Coroutines.
10//
11// This file contains references to sections of the Coroutines TS, which
12// can be found at http://wg21.link/coroutines.
13//
14//===----------------------------------------------------------------------===//
15
16#include "CoroutineStmtBuilder.h"
17#include "clang/AST/ASTLambda.h"
18#include "clang/AST/Decl.h"
19#include "clang/AST/Expr.h"
20#include "clang/AST/ExprCXX.h"
21#include "clang/AST/StmtCXX.h"
22#include "clang/Basic/Builtins.h"
23#include "clang/Lex/Preprocessor.h"
24#include "clang/Sema/EnterExpressionEvaluationContext.h"
25#include "clang/Sema/Initialization.h"
26#include "clang/Sema/Overload.h"
27#include "clang/Sema/ScopeInfo.h"
28#include "clang/Sema/SemaInternal.h"
29#include "llvm/ADT/SmallSet.h"
30
31using namespace clang;
32using namespace sema;
33
34static LookupResult lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
35 SourceLocation Loc, bool &Res) {
36 DeclarationName DN = S.PP.getIdentifierInfo(Name);
37 LookupResult LR(S, DN, Loc, Sema::LookupMemberName);
38 // Suppress diagnostics when a private member is selected. The same warnings
39 // will be produced again when building the call.
40 LR.suppressDiagnostics();
41 Res = S.LookupQualifiedName(LR, RD);
42 return LR;
43}
44
45static bool lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD,
46 SourceLocation Loc) {
47 bool Res;
48 lookupMember(S, Name, RD, Loc, Res);
49 return Res;
50}
51
52/// Look up the std::coroutine_traits<...>::promise_type for the given
53/// function type.
54static QualType lookupPromiseType(Sema &S, const FunctionDecl *FD,
55 SourceLocation KwLoc) {
56 const FunctionProtoType *FnType = FD->getType()->castAs<FunctionProtoType>();
57 const SourceLocation FuncLoc = FD->getLocation();
58
59 ClassTemplateDecl *CoroTraits =
60 S.lookupCoroutineTraits(KwLoc, FuncLoc);
61 if (!CoroTraits)
62 return QualType();
63
64 // Form template argument list for coroutine_traits<R, P1, P2, ...> according
65 // to [dcl.fct.def.coroutine]3
66 TemplateArgumentListInfo Args(KwLoc, KwLoc);
67 auto AddArg = [&](QualType T) {
68 Args.addArgument(Loc: TemplateArgumentLoc(
69 TemplateArgument(T), S.Context.getTrivialTypeSourceInfo(T, Loc: KwLoc)));
70 };
71 AddArg(FnType->getReturnType());
72 // If the function is a non-static member function, add the type
73 // of the implicit object parameter before the formal parameters.
74 if (auto *MD = dyn_cast<CXXMethodDecl>(Val: FD)) {
75 if (MD->isImplicitObjectMemberFunction()) {
76 // [over.match.funcs]4
77 // For non-static member functions, the type of the implicit object
78 // parameter is
79 // -- "lvalue reference to cv X" for functions declared without a
80 // ref-qualifier or with the & ref-qualifier
81 // -- "rvalue reference to cv X" for functions declared with the &&
82 // ref-qualifier
83 QualType T = MD->getFunctionObjectParameterType();
84 T = FnType->getRefQualifier() == RQ_RValue
85 ? S.Context.getRValueReferenceType(T)
86 : S.Context.getLValueReferenceType(T, /*SpelledAsLValue*/ true);
87 AddArg(T);
88 }
89 }
90 for (QualType T : FnType->getParamTypes())
91 AddArg(T);
92
93 // Build the template-id.
94 QualType CoroTrait =
95 S.CheckTemplateIdType(Template: TemplateName(CoroTraits), TemplateLoc: KwLoc, TemplateArgs&: Args);
96 if (CoroTrait.isNull())
97 return QualType();
98 if (S.RequireCompleteType(KwLoc, CoroTrait,
99 diag::err_coroutine_type_missing_specialization))
100 return QualType();
101
102 auto *RD = CoroTrait->getAsCXXRecordDecl();
103 assert(RD && "specialization of class template is not a class?");
104
105 // Look up the ::promise_type member.
106 LookupResult R(S, &S.PP.getIdentifierTable().get(Name: "promise_type"), KwLoc,
107 Sema::LookupOrdinaryName);
108 S.LookupQualifiedName(R, RD);
109 auto *Promise = R.getAsSingle<TypeDecl>();
110 if (!Promise) {
111 S.Diag(FuncLoc,
112 diag::err_implied_std_coroutine_traits_promise_type_not_found)
113 << RD;
114 return QualType();
115 }
116 // The promise type is required to be a class type.
117 QualType PromiseType = S.Context.getTypeDeclType(Decl: Promise);
118
119 auto buildElaboratedType = [&]() {
120 auto *NNS = NestedNameSpecifier::Create(Context: S.Context, Prefix: nullptr, NS: S.getStdNamespace());
121 NNS = NestedNameSpecifier::Create(Context: S.Context, Prefix: NNS, Template: false,
122 T: CoroTrait.getTypePtr());
123 return S.Context.getElaboratedType(Keyword: ElaboratedTypeKeyword::None, NNS,
124 NamedType: PromiseType);
125 };
126
127 if (!PromiseType->getAsCXXRecordDecl()) {
128 S.Diag(FuncLoc,
129 diag::err_implied_std_coroutine_traits_promise_type_not_class)
130 << buildElaboratedType();
131 return QualType();
132 }
133 if (S.RequireCompleteType(FuncLoc, buildElaboratedType(),
134 diag::err_coroutine_promise_type_incomplete))
135 return QualType();
136
137 return PromiseType;
138}
139
140/// Look up the std::coroutine_handle<PromiseType>.
141static QualType lookupCoroutineHandleType(Sema &S, QualType PromiseType,
142 SourceLocation Loc) {
143 if (PromiseType.isNull())
144 return QualType();
145
146 NamespaceDecl *CoroNamespace = S.getStdNamespace();
147 assert(CoroNamespace && "Should already be diagnosed");
148
149 LookupResult Result(S, &S.PP.getIdentifierTable().get(Name: "coroutine_handle"),
150 Loc, Sema::LookupOrdinaryName);
151 if (!S.LookupQualifiedName(Result, CoroNamespace)) {
152 S.Diag(Loc, diag::err_implied_coroutine_type_not_found)
153 << "std::coroutine_handle";
154 return QualType();
155 }
156
157 ClassTemplateDecl *CoroHandle = Result.getAsSingle<ClassTemplateDecl>();
158 if (!CoroHandle) {
159 Result.suppressDiagnostics();
160 // We found something weird. Complain about the first thing we found.
161 NamedDecl *Found = *Result.begin();
162 S.Diag(Found->getLocation(), diag::err_malformed_std_coroutine_handle);
163 return QualType();
164 }
165
166 // Form template argument list for coroutine_handle<Promise>.
167 TemplateArgumentListInfo Args(Loc, Loc);
168 Args.addArgument(Loc: TemplateArgumentLoc(
169 TemplateArgument(PromiseType),
170 S.Context.getTrivialTypeSourceInfo(T: PromiseType, Loc)));
171
172 // Build the template-id.
173 QualType CoroHandleType =
174 S.CheckTemplateIdType(Template: TemplateName(CoroHandle), TemplateLoc: Loc, TemplateArgs&: Args);
175 if (CoroHandleType.isNull())
176 return QualType();
177 if (S.RequireCompleteType(Loc, CoroHandleType,
178 diag::err_coroutine_type_missing_specialization))
179 return QualType();
180
181 return CoroHandleType;
182}
183
184static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
185 StringRef Keyword) {
186 // [expr.await]p2 dictates that 'co_await' and 'co_yield' must be used within
187 // a function body.
188 // FIXME: This also covers [expr.await]p2: "An await-expression shall not
189 // appear in a default argument." But the diagnostic QoI here could be
190 // improved to inform the user that default arguments specifically are not
191 // allowed.
192 auto *FD = dyn_cast<FunctionDecl>(Val: S.CurContext);
193 if (!FD) {
194 S.Diag(Loc, isa<ObjCMethodDecl>(S.CurContext)
195 ? diag::err_coroutine_objc_method
196 : diag::err_coroutine_outside_function) << Keyword;
197 return false;
198 }
199
200 // An enumeration for mapping the diagnostic type to the correct diagnostic
201 // selection index.
202 enum InvalidFuncDiag {
203 DiagCtor = 0,
204 DiagDtor,
205 DiagMain,
206 DiagConstexpr,
207 DiagAutoRet,
208 DiagVarargs,
209 DiagConsteval,
210 };
211 bool Diagnosed = false;
212 auto DiagInvalid = [&](InvalidFuncDiag ID) {
213 S.Diag(Loc, diag::err_coroutine_invalid_func_context) << ID << Keyword;
214 Diagnosed = true;
215 return false;
216 };
217
218 // Diagnose when a constructor, destructor
219 // or the function 'main' are declared as a coroutine.
220 auto *MD = dyn_cast<CXXMethodDecl>(Val: FD);
221 // [class.ctor]p11: "A constructor shall not be a coroutine."
222 if (MD && isa<CXXConstructorDecl>(Val: MD))
223 return DiagInvalid(DiagCtor);
224 // [class.dtor]p17: "A destructor shall not be a coroutine."
225 else if (MD && isa<CXXDestructorDecl>(Val: MD))
226 return DiagInvalid(DiagDtor);
227 // [basic.start.main]p3: "The function main shall not be a coroutine."
228 else if (FD->isMain())
229 return DiagInvalid(DiagMain);
230
231 // Emit a diagnostics for each of the following conditions which is not met.
232 // [expr.const]p2: "An expression e is a core constant expression unless the
233 // evaluation of e [...] would evaluate one of the following expressions:
234 // [...] an await-expression [...] a yield-expression."
235 if (FD->isConstexpr())
236 DiagInvalid(FD->isConsteval() ? DiagConsteval : DiagConstexpr);
237 // [dcl.spec.auto]p15: "A function declared with a return type that uses a
238 // placeholder type shall not be a coroutine."
239 if (FD->getReturnType()->isUndeducedType())
240 DiagInvalid(DiagAutoRet);
241 // [dcl.fct.def.coroutine]p1
242 // The parameter-declaration-clause of the coroutine shall not terminate with
243 // an ellipsis that is not part of a parameter-declaration.
244 if (FD->isVariadic())
245 DiagInvalid(DiagVarargs);
246
247 return !Diagnosed;
248}
249
250/// Build a call to 'operator co_await' if there is a suitable operator for
251/// the given expression.
252ExprResult Sema::BuildOperatorCoawaitCall(SourceLocation Loc, Expr *E,
253 UnresolvedLookupExpr *Lookup) {
254 UnresolvedSet<16> Functions;
255 Functions.append(I: Lookup->decls_begin(), E: Lookup->decls_end());
256 return CreateOverloadedUnaryOp(OpLoc: Loc, Opc: UO_Coawait, Fns: Functions, input: E);
257}
258
259static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, Scope *S,
260 SourceLocation Loc, Expr *E) {
261 ExprResult R = SemaRef.BuildOperatorCoawaitLookupExpr(S, Loc);
262 if (R.isInvalid())
263 return ExprError();
264 return SemaRef.BuildOperatorCoawaitCall(Loc, E,
265 Lookup: cast<UnresolvedLookupExpr>(Val: R.get()));
266}
267
268static ExprResult buildCoroutineHandle(Sema &S, QualType PromiseType,
269 SourceLocation Loc) {
270 QualType CoroHandleType = lookupCoroutineHandleType(S, PromiseType, Loc);
271 if (CoroHandleType.isNull())
272 return ExprError();
273
274 DeclContext *LookupCtx = S.computeDeclContext(T: CoroHandleType);
275 LookupResult Found(S, &S.PP.getIdentifierTable().get(Name: "from_address"), Loc,
276 Sema::LookupOrdinaryName);
277 if (!S.LookupQualifiedName(R&: Found, LookupCtx)) {
278 S.Diag(Loc, diag::err_coroutine_handle_missing_member)
279 << "from_address";
280 return ExprError();
281 }
282
283 Expr *FramePtr =
284 S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_frame, {});
285
286 CXXScopeSpec SS;
287 ExprResult FromAddr =
288 S.BuildDeclarationNameExpr(SS, R&: Found, /*NeedsADL=*/false);
289 if (FromAddr.isInvalid())
290 return ExprError();
291
292 return S.BuildCallExpr(S: nullptr, Fn: FromAddr.get(), LParenLoc: Loc, ArgExprs: FramePtr, RParenLoc: Loc);
293}
294
295struct ReadySuspendResumeResult {
296 enum AwaitCallType { ACT_Ready, ACT_Suspend, ACT_Resume };
297 Expr *Results[3];
298 OpaqueValueExpr *OpaqueValue;
299 bool IsInvalid;
300};
301
302static ExprResult buildMemberCall(Sema &S, Expr *Base, SourceLocation Loc,
303 StringRef Name, MultiExprArg Args) {
304 DeclarationNameInfo NameInfo(&S.PP.getIdentifierTable().get(Name), Loc);
305
306 // FIXME: Fix BuildMemberReferenceExpr to take a const CXXScopeSpec&.
307 CXXScopeSpec SS;
308 ExprResult Result = S.BuildMemberReferenceExpr(
309 Base, BaseType: Base->getType(), OpLoc: Loc, /*IsPtr=*/IsArrow: false, SS,
310 TemplateKWLoc: SourceLocation(), FirstQualifierInScope: nullptr, NameInfo, /*TemplateArgs=*/nullptr,
311 /*Scope=*/S: nullptr);
312 if (Result.isInvalid())
313 return ExprError();
314
315 // We meant exactly what we asked for. No need for typo correction.
316 if (auto *TE = dyn_cast<TypoExpr>(Val: Result.get())) {
317 S.clearDelayedTypo(TE);
318 S.Diag(Loc, diag::err_no_member)
319 << NameInfo.getName() << Base->getType()->getAsCXXRecordDecl()
320 << Base->getSourceRange();
321 return ExprError();
322 }
323
324 auto EndLoc = Args.empty() ? Loc : Args.back()->getEndLoc();
325 return S.BuildCallExpr(S: nullptr, Fn: Result.get(), LParenLoc: Loc, ArgExprs: Args, RParenLoc: EndLoc, ExecConfig: nullptr);
326}
327
328// See if return type is coroutine-handle and if so, invoke builtin coro-resume
329// on its address. This is to enable the support for coroutine-handle
330// returning await_suspend that results in a guaranteed tail call to the target
331// coroutine.
332static Expr *maybeTailCall(Sema &S, QualType RetType, Expr *E,
333 SourceLocation Loc) {
334 if (RetType->isReferenceType())
335 return nullptr;
336 Type const *T = RetType.getTypePtr();
337 if (!T->isClassType() && !T->isStructureType())
338 return nullptr;
339
340 // FIXME: Add convertability check to coroutine_handle<>. Possibly via
341 // EvaluateBinaryTypeTrait(BTT_IsConvertible, ...) which is at the moment
342 // a private function in SemaExprCXX.cpp
343
344 ExprResult AddressExpr = buildMemberCall(S, Base: E, Loc, Name: "address", Args: std::nullopt);
345 if (AddressExpr.isInvalid())
346 return nullptr;
347
348 Expr *JustAddress = AddressExpr.get();
349
350 // Check that the type of AddressExpr is void*
351 if (!JustAddress->getType().getTypePtr()->isVoidPointerType())
352 S.Diag(cast<CallExpr>(JustAddress)->getCalleeDecl()->getLocation(),
353 diag::warn_coroutine_handle_address_invalid_return_type)
354 << JustAddress->getType();
355
356 // Clean up temporary objects, because the resulting expression
357 // will become the body of await_suspend wrapper.
358 return S.MaybeCreateExprWithCleanups(SubExpr: JustAddress);
359}
360
361/// Build calls to await_ready, await_suspend, and await_resume for a co_await
362/// expression.
363/// The generated AST tries to clean up temporary objects as early as
364/// possible so that they don't live across suspension points if possible.
365/// Having temporary objects living across suspension points unnecessarily can
366/// lead to large frame size, and also lead to memory corruptions if the
367/// coroutine frame is destroyed after coming back from suspension. This is done
368/// by wrapping both the await_ready call and the await_suspend call with
369/// ExprWithCleanups. In the end of this function, we also need to explicitly
370/// set cleanup state so that the CoawaitExpr is also wrapped with an
371/// ExprWithCleanups to clean up the awaiter associated with the co_await
372/// expression.
373static ReadySuspendResumeResult buildCoawaitCalls(Sema &S, VarDecl *CoroPromise,
374 SourceLocation Loc, Expr *E) {
375 OpaqueValueExpr *Operand = new (S.Context)
376 OpaqueValueExpr(Loc, E->getType(), VK_LValue, E->getObjectKind(), E);
377
378 // Assume valid until we see otherwise.
379 // Further operations are responsible for setting IsInalid to true.
380 ReadySuspendResumeResult Calls = {.Results: {}, .OpaqueValue: Operand, /*IsInvalid=*/false};
381
382 using ACT = ReadySuspendResumeResult::AwaitCallType;
383
384 auto BuildSubExpr = [&](ACT CallType, StringRef Func,
385 MultiExprArg Arg) -> Expr * {
386 ExprResult Result = buildMemberCall(S, Operand, Loc, Func, Arg);
387 if (Result.isInvalid()) {
388 Calls.IsInvalid = true;
389 return nullptr;
390 }
391 Calls.Results[CallType] = Result.get();
392 return Result.get();
393 };
394
395 CallExpr *AwaitReady = cast_or_null<CallExpr>(
396 Val: BuildSubExpr(ACT::ACT_Ready, "await_ready", std::nullopt));
397 if (!AwaitReady)
398 return Calls;
399 if (!AwaitReady->getType()->isDependentType()) {
400 // [expr.await]p3 [...]
401 // — await-ready is the expression e.await_ready(), contextually converted
402 // to bool.
403 ExprResult Conv = S.PerformContextuallyConvertToBool(AwaitReady);
404 if (Conv.isInvalid()) {
405 S.Diag(AwaitReady->getDirectCallee()->getBeginLoc(),
406 diag::note_await_ready_no_bool_conversion);
407 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
408 << AwaitReady->getDirectCallee() << E->getSourceRange();
409 Calls.IsInvalid = true;
410 } else
411 Calls.Results[ACT::ACT_Ready] = S.MaybeCreateExprWithCleanups(SubExpr: Conv.get());
412 }
413
414 ExprResult CoroHandleRes =
415 buildCoroutineHandle(S, CoroPromise->getType(), Loc);
416 if (CoroHandleRes.isInvalid()) {
417 Calls.IsInvalid = true;
418 return Calls;
419 }
420 Expr *CoroHandle = CoroHandleRes.get();
421 CallExpr *AwaitSuspend = cast_or_null<CallExpr>(
422 Val: BuildSubExpr(ACT::ACT_Suspend, "await_suspend", CoroHandle));
423 if (!AwaitSuspend)
424 return Calls;
425 if (!AwaitSuspend->getType()->isDependentType()) {
426 // [expr.await]p3 [...]
427 // - await-suspend is the expression e.await_suspend(h), which shall be
428 // a prvalue of type void, bool, or std::coroutine_handle<Z> for some
429 // type Z.
430 QualType RetType = AwaitSuspend->getCallReturnType(Ctx: S.Context);
431
432 // Support for coroutine_handle returning await_suspend.
433 if (Expr *TailCallSuspend =
434 maybeTailCall(S, RetType, AwaitSuspend, Loc))
435 // Note that we don't wrap the expression with ExprWithCleanups here
436 // because that might interfere with tailcall contract (e.g. inserting
437 // clean up instructions in-between tailcall and return). Instead
438 // ExprWithCleanups is wrapped within maybeTailCall() prior to the resume
439 // call.
440 Calls.Results[ACT::ACT_Suspend] = TailCallSuspend;
441 else {
442 // non-class prvalues always have cv-unqualified types
443 if (RetType->isReferenceType() ||
444 (!RetType->isBooleanType() && !RetType->isVoidType())) {
445 S.Diag(AwaitSuspend->getCalleeDecl()->getLocation(),
446 diag::err_await_suspend_invalid_return_type)
447 << RetType;
448 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
449 << AwaitSuspend->getDirectCallee();
450 Calls.IsInvalid = true;
451 } else
452 Calls.Results[ACT::ACT_Suspend] =
453 S.MaybeCreateExprWithCleanups(AwaitSuspend);
454 }
455 }
456
457 BuildSubExpr(ACT::ACT_Resume, "await_resume", std::nullopt);
458
459 // Make sure the awaiter object gets a chance to be cleaned up.
460 S.Cleanup.setExprNeedsCleanups(true);
461
462 return Calls;
463}
464
465static ExprResult buildPromiseCall(Sema &S, VarDecl *Promise,
466 SourceLocation Loc, StringRef Name,
467 MultiExprArg Args) {
468
469 // Form a reference to the promise.
470 ExprResult PromiseRef = S.BuildDeclRefExpr(
471 Promise, Promise->getType().getNonReferenceType(), VK_LValue, Loc);
472 if (PromiseRef.isInvalid())
473 return ExprError();
474
475 return buildMemberCall(S, Base: PromiseRef.get(), Loc, Name, Args);
476}
477
478VarDecl *Sema::buildCoroutinePromise(SourceLocation Loc) {
479 assert(isa<FunctionDecl>(CurContext) && "not in a function scope");
480 auto *FD = cast<FunctionDecl>(Val: CurContext);
481 bool IsThisDependentType = [&] {
482 if (const auto *MD = dyn_cast_if_present<CXXMethodDecl>(Val: FD))
483 return MD->isImplicitObjectMemberFunction() &&
484 MD->getThisType()->isDependentType();
485 return false;
486 }();
487
488 QualType T = FD->getType()->isDependentType() || IsThisDependentType
489 ? Context.DependentTy
490 : lookupPromiseType(S&: *this, FD, KwLoc: Loc);
491 if (T.isNull())
492 return nullptr;
493
494 auto *VD = VarDecl::Create(C&: Context, DC: FD, StartLoc: FD->getLocation(), IdLoc: FD->getLocation(),
495 Id: &PP.getIdentifierTable().get(Name: "__promise"), T,
496 TInfo: Context.getTrivialTypeSourceInfo(T, Loc), S: SC_None);
497 VD->setImplicit();
498 CheckVariableDeclarationType(NewVD: VD);
499 if (VD->isInvalidDecl())
500 return nullptr;
501
502 auto *ScopeInfo = getCurFunction();
503
504 // Build a list of arguments, based on the coroutine function's arguments,
505 // that if present will be passed to the promise type's constructor.
506 llvm::SmallVector<Expr *, 4> CtorArgExprs;
507
508 // Add implicit object parameter.
509 if (auto *MD = dyn_cast<CXXMethodDecl>(Val: FD)) {
510 if (MD->isImplicitObjectMemberFunction() && !isLambdaCallOperator(MD)) {
511 ExprResult ThisExpr = ActOnCXXThis(Loc);
512 if (ThisExpr.isInvalid())
513 return nullptr;
514 ThisExpr = CreateBuiltinUnaryOp(OpLoc: Loc, Opc: UO_Deref, InputExpr: ThisExpr.get());
515 if (ThisExpr.isInvalid())
516 return nullptr;
517 CtorArgExprs.push_back(Elt: ThisExpr.get());
518 }
519 }
520
521 // Add the coroutine function's parameters.
522 auto &Moves = ScopeInfo->CoroutineParameterMoves;
523 for (auto *PD : FD->parameters()) {
524 if (PD->getType()->isDependentType())
525 continue;
526
527 auto RefExpr = ExprEmpty();
528 auto Move = Moves.find(Key: PD);
529 assert(Move != Moves.end() &&
530 "Coroutine function parameter not inserted into move map");
531 // If a reference to the function parameter exists in the coroutine
532 // frame, use that reference.
533 auto *MoveDecl =
534 cast<VarDecl>(Val: cast<DeclStmt>(Val: Move->second)->getSingleDecl());
535 RefExpr =
536 BuildDeclRefExpr(MoveDecl, MoveDecl->getType().getNonReferenceType(),
537 ExprValueKind::VK_LValue, FD->getLocation());
538 if (RefExpr.isInvalid())
539 return nullptr;
540 CtorArgExprs.push_back(Elt: RefExpr.get());
541 }
542
543 // If we have a non-zero number of constructor arguments, try to use them.
544 // Otherwise, fall back to the promise type's default constructor.
545 if (!CtorArgExprs.empty()) {
546 // Create an initialization sequence for the promise type using the
547 // constructor arguments, wrapped in a parenthesized list expression.
548 Expr *PLE = ParenListExpr::Create(Ctx: Context, LParenLoc: FD->getLocation(),
549 Exprs: CtorArgExprs, RParenLoc: FD->getLocation());
550 InitializedEntity Entity = InitializedEntity::InitializeVariable(Var: VD);
551 InitializationKind Kind = InitializationKind::CreateForInit(
552 Loc: VD->getLocation(), /*DirectInit=*/true, Init: PLE);
553 InitializationSequence InitSeq(*this, Entity, Kind, CtorArgExprs,
554 /*TopLevelOfInitList=*/false,
555 /*TreatUnavailableAsInvalid=*/false);
556
557 // [dcl.fct.def.coroutine]5.7
558 // promise-constructor-arguments is determined as follows: overload
559 // resolution is performed on a promise constructor call created by
560 // assembling an argument list q_1 ... q_n . If a viable constructor is
561 // found ([over.match.viable]), then promise-constructor-arguments is ( q_1
562 // , ..., q_n ), otherwise promise-constructor-arguments is empty.
563 if (InitSeq) {
564 ExprResult Result = InitSeq.Perform(S&: *this, Entity, Kind, Args: CtorArgExprs);
565 if (Result.isInvalid()) {
566 VD->setInvalidDecl();
567 } else if (Result.get()) {
568 VD->setInit(MaybeCreateExprWithCleanups(SubExpr: Result.get()));
569 VD->setInitStyle(VarDecl::CallInit);
570 CheckCompleteVariableDeclaration(VD: VD);
571 }
572 } else
573 ActOnUninitializedDecl(dcl: VD);
574 } else
575 ActOnUninitializedDecl(dcl: VD);
576
577 FD->addDecl(D: VD);
578 return VD;
579}
580
581/// Check that this is a context in which a coroutine suspension can appear.
582static FunctionScopeInfo *checkCoroutineContext(Sema &S, SourceLocation Loc,
583 StringRef Keyword,
584 bool IsImplicit = false) {
585 if (!isValidCoroutineContext(S, Loc, Keyword))
586 return nullptr;
587
588 assert(isa<FunctionDecl>(S.CurContext) && "not in a function scope");
589
590 auto *ScopeInfo = S.getCurFunction();
591 assert(ScopeInfo && "missing function scope for function");
592
593 if (ScopeInfo->FirstCoroutineStmtLoc.isInvalid() && !IsImplicit)
594 ScopeInfo->setFirstCoroutineStmt(Loc, Keyword);
595
596 if (ScopeInfo->CoroutinePromise)
597 return ScopeInfo;
598
599 if (!S.buildCoroutineParameterMoves(Loc))
600 return nullptr;
601
602 ScopeInfo->CoroutinePromise = S.buildCoroutinePromise(Loc);
603 if (!ScopeInfo->CoroutinePromise)
604 return nullptr;
605
606 return ScopeInfo;
607}
608
609/// Recursively check \p E and all its children to see if any call target
610/// (including constructor call) is declared noexcept. Also any value returned
611/// from the call has a noexcept destructor.
612static void checkNoThrow(Sema &S, const Stmt *E,
613 llvm::SmallPtrSetImpl<const Decl *> &ThrowingDecls) {
614 auto checkDeclNoexcept = [&](const Decl *D, bool IsDtor = false) {
615 // In the case of dtor, the call to dtor is implicit and hence we should
616 // pass nullptr to canCalleeThrow.
617 if (Sema::canCalleeThrow(S, E: IsDtor ? nullptr : cast<Expr>(Val: E), D)) {
618 if (const auto *FD = dyn_cast<FunctionDecl>(Val: D)) {
619 // co_await promise.final_suspend() could end up calling
620 // __builtin_coro_resume for symmetric transfer if await_suspend()
621 // returns a handle. In that case, even __builtin_coro_resume is not
622 // declared as noexcept and may throw, it does not throw _into_ the
623 // coroutine that just suspended, but rather throws back out from
624 // whoever called coroutine_handle::resume(), hence we claim that
625 // logically it does not throw.
626 if (FD->getBuiltinID() == Builtin::BI__builtin_coro_resume)
627 return;
628 }
629 if (ThrowingDecls.empty()) {
630 // [dcl.fct.def.coroutine]p15
631 // The expression co_await promise.final_suspend() shall not be
632 // potentially-throwing ([except.spec]).
633 //
634 // First time seeing an error, emit the error message.
635 S.Diag(cast<FunctionDecl>(S.CurContext)->getLocation(),
636 diag::err_coroutine_promise_final_suspend_requires_nothrow);
637 }
638 ThrowingDecls.insert(Ptr: D);
639 }
640 };
641
642 if (auto *CE = dyn_cast<CXXConstructExpr>(Val: E)) {
643 CXXConstructorDecl *Ctor = CE->getConstructor();
644 checkDeclNoexcept(Ctor);
645 // Check the corresponding destructor of the constructor.
646 checkDeclNoexcept(Ctor->getParent()->getDestructor(), /*IsDtor=*/true);
647 } else if (auto *CE = dyn_cast<CallExpr>(Val: E)) {
648 if (CE->isTypeDependent())
649 return;
650
651 checkDeclNoexcept(CE->getCalleeDecl());
652 QualType ReturnType = CE->getCallReturnType(Ctx: S.getASTContext());
653 // Check the destructor of the call return type, if any.
654 if (ReturnType.isDestructedType() ==
655 QualType::DestructionKind::DK_cxx_destructor) {
656 const auto *T =
657 cast<RecordType>(Val: ReturnType.getCanonicalType().getTypePtr());
658 checkDeclNoexcept(cast<CXXRecordDecl>(Val: T->getDecl())->getDestructor(),
659 /*IsDtor=*/true);
660 }
661 } else
662 for (const auto *Child : E->children()) {
663 if (!Child)
664 continue;
665 checkNoThrow(S, E: Child, ThrowingDecls);
666 }
667}
668
669bool Sema::checkFinalSuspendNoThrow(const Stmt *FinalSuspend) {
670 llvm::SmallPtrSet<const Decl *, 4> ThrowingDecls;
671 // We first collect all declarations that should not throw but not declared
672 // with noexcept. We then sort them based on the location before printing.
673 // This is to avoid emitting the same note multiple times on the same
674 // declaration, and also provide a deterministic order for the messages.
675 checkNoThrow(S&: *this, E: FinalSuspend, ThrowingDecls);
676 auto SortedDecls = llvm::SmallVector<const Decl *, 4>{ThrowingDecls.begin(),
677 ThrowingDecls.end()};
678 sort(C&: SortedDecls, Comp: [](const Decl *A, const Decl *B) {
679 return A->getEndLoc() < B->getEndLoc();
680 });
681 for (const auto *D : SortedDecls) {
682 Diag(D->getEndLoc(), diag::note_coroutine_function_declare_noexcept);
683 }
684 return ThrowingDecls.empty();
685}
686
687bool Sema::ActOnCoroutineBodyStart(Scope *SC, SourceLocation KWLoc,
688 StringRef Keyword) {
689 // Ignore previous expr evaluation contexts.
690 EnterExpressionEvaluationContext PotentiallyEvaluated(
691 *this, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
692 if (!checkCoroutineContext(S&: *this, Loc: KWLoc, Keyword))
693 return false;
694 auto *ScopeInfo = getCurFunction();
695 assert(ScopeInfo->CoroutinePromise);
696
697 // If we have existing coroutine statements then we have already built
698 // the initial and final suspend points.
699 if (!ScopeInfo->NeedsCoroutineSuspends)
700 return true;
701
702 ScopeInfo->setNeedsCoroutineSuspends(false);
703
704 auto *Fn = cast<FunctionDecl>(Val: CurContext);
705 SourceLocation Loc = Fn->getLocation();
706 // Build the initial suspend point
707 auto buildSuspends = [&](StringRef Name) mutable -> StmtResult {
708 ExprResult Operand = buildPromiseCall(S&: *this, Promise: ScopeInfo->CoroutinePromise,
709 Loc, Name, Args: std::nullopt);
710 if (Operand.isInvalid())
711 return StmtError();
712 ExprResult Suspend =
713 buildOperatorCoawaitCall(SemaRef&: *this, S: SC, Loc, E: Operand.get());
714 if (Suspend.isInvalid())
715 return StmtError();
716 Suspend = BuildResolvedCoawaitExpr(KwLoc: Loc, Operand: Operand.get(), Awaiter: Suspend.get(),
717 /*IsImplicit*/ true);
718 Suspend = ActOnFinishFullExpr(Expr: Suspend.get(), /*DiscardedValue*/ false);
719 if (Suspend.isInvalid()) {
720 Diag(Loc, diag::note_coroutine_promise_suspend_implicitly_required)
721 << ((Name == "initial_suspend") ? 0 : 1);
722 Diag(KWLoc, diag::note_declared_coroutine_here) << Keyword;
723 return StmtError();
724 }
725 return cast<Stmt>(Val: Suspend.get());
726 };
727
728 StmtResult InitSuspend = buildSuspends("initial_suspend");
729 if (InitSuspend.isInvalid())
730 return true;
731
732 StmtResult FinalSuspend = buildSuspends("final_suspend");
733 if (FinalSuspend.isInvalid() || !checkFinalSuspendNoThrow(FinalSuspend: FinalSuspend.get()))
734 return true;
735
736 ScopeInfo->setCoroutineSuspends(Initial: InitSuspend.get(), Final: FinalSuspend.get());
737
738 return true;
739}
740
741// Recursively walks up the scope hierarchy until either a 'catch' or a function
742// scope is found, whichever comes first.
743static bool isWithinCatchScope(Scope *S) {
744 // 'co_await' and 'co_yield' keywords are disallowed within catch blocks, but
745 // lambdas that use 'co_await' are allowed. The loop below ends when a
746 // function scope is found in order to ensure the following behavior:
747 //
748 // void foo() { // <- function scope
749 // try { //
750 // co_await x; // <- 'co_await' is OK within a function scope
751 // } catch { // <- catch scope
752 // co_await x; // <- 'co_await' is not OK within a catch scope
753 // []() { // <- function scope
754 // co_await x; // <- 'co_await' is OK within a function scope
755 // }();
756 // }
757 // }
758 while (S && !S->isFunctionScope()) {
759 if (S->isCatchScope())
760 return true;
761 S = S->getParent();
762 }
763 return false;
764}
765
766// [expr.await]p2, emphasis added: "An await-expression shall appear only in
767// a *potentially evaluated* expression within the compound-statement of a
768// function-body *outside of a handler* [...] A context within a function
769// where an await-expression can appear is called a suspension context of the
770// function."
771static bool checkSuspensionContext(Sema &S, SourceLocation Loc,
772 StringRef Keyword) {
773 // First emphasis of [expr.await]p2: must be a potentially evaluated context.
774 // That is, 'co_await' and 'co_yield' cannot appear in subexpressions of
775 // \c sizeof.
776 if (S.isUnevaluatedContext()) {
777 S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword;
778 return false;
779 }
780
781 // Second emphasis of [expr.await]p2: must be outside of an exception handler.
782 if (isWithinCatchScope(S: S.getCurScope())) {
783 S.Diag(Loc, diag::err_coroutine_within_handler) << Keyword;
784 return false;
785 }
786
787 return true;
788}
789
790ExprResult Sema::ActOnCoawaitExpr(Scope *S, SourceLocation Loc, Expr *E) {
791 if (!checkSuspensionContext(S&: *this, Loc, Keyword: "co_await"))
792 return ExprError();
793
794 if (!ActOnCoroutineBodyStart(SC: S, KWLoc: Loc, Keyword: "co_await")) {
795 CorrectDelayedTyposInExpr(E);
796 return ExprError();
797 }
798
799 if (E->hasPlaceholderType()) {
800 ExprResult R = CheckPlaceholderExpr(E);
801 if (R.isInvalid()) return ExprError();
802 E = R.get();
803 }
804 ExprResult Lookup = BuildOperatorCoawaitLookupExpr(S, Loc);
805 if (Lookup.isInvalid())
806 return ExprError();
807 return BuildUnresolvedCoawaitExpr(KwLoc: Loc, Operand: E,
808 Lookup: cast<UnresolvedLookupExpr>(Val: Lookup.get()));
809}
810
811ExprResult Sema::BuildOperatorCoawaitLookupExpr(Scope *S, SourceLocation Loc) {
812 DeclarationName OpName =
813 Context.DeclarationNames.getCXXOperatorName(Op: OO_Coawait);
814 LookupResult Operators(*this, OpName, SourceLocation(),
815 Sema::LookupOperatorName);
816 LookupName(R&: Operators, S);
817
818 assert(!Operators.isAmbiguous() && "Operator lookup cannot be ambiguous");
819 const auto &Functions = Operators.asUnresolvedSet();
820 Expr *CoawaitOp = UnresolvedLookupExpr::Create(
821 Context, /*NamingClass*/ nullptr, QualifierLoc: NestedNameSpecifierLoc(),
822 NameInfo: DeclarationNameInfo(OpName, Loc), /*RequiresADL*/ true, Begin: Functions.begin(),
823 End: Functions.end(), /*KnownDependent=*/false);
824 assert(CoawaitOp);
825 return CoawaitOp;
826}
827
828// Attempts to resolve and build a CoawaitExpr from "raw" inputs, bailing out to
829// DependentCoawaitExpr if needed.
830ExprResult Sema::BuildUnresolvedCoawaitExpr(SourceLocation Loc, Expr *Operand,
831 UnresolvedLookupExpr *Lookup) {
832 auto *FSI = checkCoroutineContext(S&: *this, Loc, Keyword: "co_await");
833 if (!FSI)
834 return ExprError();
835
836 if (Operand->hasPlaceholderType()) {
837 ExprResult R = CheckPlaceholderExpr(E: Operand);
838 if (R.isInvalid())
839 return ExprError();
840 Operand = R.get();
841 }
842
843 auto *Promise = FSI->CoroutinePromise;
844 if (Promise->getType()->isDependentType()) {
845 Expr *Res = new (Context)
846 DependentCoawaitExpr(Loc, Context.DependentTy, Operand, Lookup);
847 return Res;
848 }
849
850 auto *RD = Promise->getType()->getAsCXXRecordDecl();
851 auto *Transformed = Operand;
852 if (lookupMember(*this, "await_transform", RD, Loc)) {
853 ExprResult R =
854 buildPromiseCall(S&: *this, Promise, Loc, Name: "await_transform", Args: Operand);
855 if (R.isInvalid()) {
856 Diag(Loc,
857 diag::note_coroutine_promise_implicit_await_transform_required_here)
858 << Operand->getSourceRange();
859 return ExprError();
860 }
861 Transformed = R.get();
862 }
863 ExprResult Awaiter = BuildOperatorCoawaitCall(Loc, E: Transformed, Lookup);
864 if (Awaiter.isInvalid())
865 return ExprError();
866
867 return BuildResolvedCoawaitExpr(KwLoc: Loc, Operand, Awaiter: Awaiter.get());
868}
869
870ExprResult Sema::BuildResolvedCoawaitExpr(SourceLocation Loc, Expr *Operand,
871 Expr *Awaiter, bool IsImplicit) {
872 auto *Coroutine = checkCoroutineContext(S&: *this, Loc, Keyword: "co_await", IsImplicit);
873 if (!Coroutine)
874 return ExprError();
875
876 if (Awaiter->hasPlaceholderType()) {
877 ExprResult R = CheckPlaceholderExpr(E: Awaiter);
878 if (R.isInvalid()) return ExprError();
879 Awaiter = R.get();
880 }
881
882 if (Awaiter->getType()->isDependentType()) {
883 Expr *Res = new (Context)
884 CoawaitExpr(Loc, Context.DependentTy, Operand, Awaiter, IsImplicit);
885 return Res;
886 }
887
888 // If the expression is a temporary, materialize it as an lvalue so that we
889 // can use it multiple times.
890 if (Awaiter->isPRValue())
891 Awaiter = CreateMaterializeTemporaryExpr(T: Awaiter->getType(), Temporary: Awaiter, BoundToLvalueReference: true);
892
893 // The location of the `co_await` token cannot be used when constructing
894 // the member call expressions since it's before the location of `Expr`, which
895 // is used as the start of the member call expression.
896 SourceLocation CallLoc = Awaiter->getExprLoc();
897
898 // Build the await_ready, await_suspend, await_resume calls.
899 ReadySuspendResumeResult RSS =
900 buildCoawaitCalls(S&: *this, CoroPromise: Coroutine->CoroutinePromise, Loc: CallLoc, E: Awaiter);
901 if (RSS.IsInvalid)
902 return ExprError();
903
904 Expr *Res = new (Context)
905 CoawaitExpr(Loc, Operand, Awaiter, RSS.Results[0], RSS.Results[1],
906 RSS.Results[2], RSS.OpaqueValue, IsImplicit);
907
908 return Res;
909}
910
911ExprResult Sema::ActOnCoyieldExpr(Scope *S, SourceLocation Loc, Expr *E) {
912 if (!checkSuspensionContext(S&: *this, Loc, Keyword: "co_yield"))
913 return ExprError();
914
915 if (!ActOnCoroutineBodyStart(SC: S, KWLoc: Loc, Keyword: "co_yield")) {
916 CorrectDelayedTyposInExpr(E);
917 return ExprError();
918 }
919
920 // Build yield_value call.
921 ExprResult Awaitable = buildPromiseCall(
922 S&: *this, Promise: getCurFunction()->CoroutinePromise, Loc, Name: "yield_value", Args: E);
923 if (Awaitable.isInvalid())
924 return ExprError();
925
926 // Build 'operator co_await' call.
927 Awaitable = buildOperatorCoawaitCall(SemaRef&: *this, S, Loc, E: Awaitable.get());
928 if (Awaitable.isInvalid())
929 return ExprError();
930
931 return BuildCoyieldExpr(KwLoc: Loc, E: Awaitable.get());
932}
933ExprResult Sema::BuildCoyieldExpr(SourceLocation Loc, Expr *E) {
934 auto *Coroutine = checkCoroutineContext(S&: *this, Loc, Keyword: "co_yield");
935 if (!Coroutine)
936 return ExprError();
937
938 if (E->hasPlaceholderType()) {
939 ExprResult R = CheckPlaceholderExpr(E);
940 if (R.isInvalid()) return ExprError();
941 E = R.get();
942 }
943
944 Expr *Operand = E;
945
946 if (E->getType()->isDependentType()) {
947 Expr *Res = new (Context) CoyieldExpr(Loc, Context.DependentTy, Operand, E);
948 return Res;
949 }
950
951 // If the expression is a temporary, materialize it as an lvalue so that we
952 // can use it multiple times.
953 if (E->isPRValue())
954 E = CreateMaterializeTemporaryExpr(T: E->getType(), Temporary: E, BoundToLvalueReference: true);
955
956 // Build the await_ready, await_suspend, await_resume calls.
957 ReadySuspendResumeResult RSS = buildCoawaitCalls(
958 S&: *this, CoroPromise: Coroutine->CoroutinePromise, Loc, E);
959 if (RSS.IsInvalid)
960 return ExprError();
961
962 Expr *Res =
963 new (Context) CoyieldExpr(Loc, Operand, E, RSS.Results[0], RSS.Results[1],
964 RSS.Results[2], RSS.OpaqueValue);
965
966 return Res;
967}
968
969StmtResult Sema::ActOnCoreturnStmt(Scope *S, SourceLocation Loc, Expr *E) {
970 if (!ActOnCoroutineBodyStart(SC: S, KWLoc: Loc, Keyword: "co_return")) {
971 CorrectDelayedTyposInExpr(E);
972 return StmtError();
973 }
974 return BuildCoreturnStmt(KwLoc: Loc, E);
975}
976
977StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E,
978 bool IsImplicit) {
979 auto *FSI = checkCoroutineContext(S&: *this, Loc, Keyword: "co_return", IsImplicit);
980 if (!FSI)
981 return StmtError();
982
983 if (E && E->hasPlaceholderType() &&
984 !E->hasPlaceholderType(K: BuiltinType::Overload)) {
985 ExprResult R = CheckPlaceholderExpr(E);
986 if (R.isInvalid()) return StmtError();
987 E = R.get();
988 }
989
990 VarDecl *Promise = FSI->CoroutinePromise;
991 ExprResult PC;
992 if (E && (isa<InitListExpr>(Val: E) || !E->getType()->isVoidType())) {
993 getNamedReturnInfo(E, Mode: SimplerImplicitMoveMode::ForceOn);
994 PC = buildPromiseCall(S&: *this, Promise, Loc, Name: "return_value", Args: E);
995 } else {
996 E = MakeFullDiscardedValueExpr(Arg: E).get();
997 PC = buildPromiseCall(S&: *this, Promise, Loc, Name: "return_void", Args: std::nullopt);
998 }
999 if (PC.isInvalid())
1000 return StmtError();
1001
1002 Expr *PCE = ActOnFinishFullExpr(Expr: PC.get(), /*DiscardedValue*/ false).get();
1003
1004 Stmt *Res = new (Context) CoreturnStmt(Loc, E, PCE, IsImplicit);
1005 return Res;
1006}
1007
1008/// Look up the std::nothrow object.
1009static Expr *buildStdNoThrowDeclRef(Sema &S, SourceLocation Loc) {
1010 NamespaceDecl *Std = S.getStdNamespace();
1011 assert(Std && "Should already be diagnosed");
1012
1013 LookupResult Result(S, &S.PP.getIdentifierTable().get(Name: "nothrow"), Loc,
1014 Sema::LookupOrdinaryName);
1015 if (!S.LookupQualifiedName(Result, Std)) {
1016 // <coroutine> is not requred to include <new>, so we couldn't omit
1017 // the check here.
1018 S.Diag(Loc, diag::err_implicit_coroutine_std_nothrow_type_not_found);
1019 return nullptr;
1020 }
1021
1022 auto *VD = Result.getAsSingle<VarDecl>();
1023 if (!VD) {
1024 Result.suppressDiagnostics();
1025 // We found something weird. Complain about the first thing we found.
1026 NamedDecl *Found = *Result.begin();
1027 S.Diag(Found->getLocation(), diag::err_malformed_std_nothrow);
1028 return nullptr;
1029 }
1030
1031 ExprResult DR = S.BuildDeclRefExpr(VD, VD->getType(), VK_LValue, Loc);
1032 if (DR.isInvalid())
1033 return nullptr;
1034
1035 return DR.get();
1036}
1037
1038static TypeSourceInfo *getTypeSourceInfoForStdAlignValT(Sema &S,
1039 SourceLocation Loc) {
1040 EnumDecl *StdAlignValT = S.getStdAlignValT();
1041 QualType StdAlignValDecl = S.Context.getTypeDeclType(StdAlignValT);
1042 return S.Context.getTrivialTypeSourceInfo(T: StdAlignValDecl);
1043}
1044
1045// Find an appropriate delete for the promise.
1046static bool findDeleteForPromise(Sema &S, SourceLocation Loc, QualType PromiseType,
1047 FunctionDecl *&OperatorDelete) {
1048 DeclarationName DeleteName =
1049 S.Context.DeclarationNames.getCXXOperatorName(Op: OO_Delete);
1050
1051 auto *PointeeRD = PromiseType->getAsCXXRecordDecl();
1052 assert(PointeeRD && "PromiseType must be a CxxRecordDecl type");
1053
1054 const bool Overaligned = S.getLangOpts().CoroAlignedAllocation;
1055
1056 // [dcl.fct.def.coroutine]p12
1057 // The deallocation function's name is looked up by searching for it in the
1058 // scope of the promise type. If nothing is found, a search is performed in
1059 // the global scope.
1060 if (S.FindDeallocationFunction(StartLoc: Loc, RD: PointeeRD, Name: DeleteName, Operator&: OperatorDelete,
1061 /*Diagnose*/ true, /*WantSize*/ true,
1062 /*WantAligned*/ Overaligned))
1063 return false;
1064
1065 // [dcl.fct.def.coroutine]p12
1066 // If both a usual deallocation function with only a pointer parameter and a
1067 // usual deallocation function with both a pointer parameter and a size
1068 // parameter are found, then the selected deallocation function shall be the
1069 // one with two parameters. Otherwise, the selected deallocation function
1070 // shall be the function with one parameter.
1071 if (!OperatorDelete) {
1072 // Look for a global declaration.
1073 // Coroutines can always provide their required size.
1074 const bool CanProvideSize = true;
1075 // Sema::FindUsualDeallocationFunction will try to find the one with two
1076 // parameters first. It will return the deallocation function with one
1077 // parameter if failed.
1078 OperatorDelete = S.FindUsualDeallocationFunction(StartLoc: Loc, CanProvideSize,
1079 Overaligned, Name: DeleteName);
1080
1081 if (!OperatorDelete)
1082 return false;
1083 }
1084
1085 S.MarkFunctionReferenced(Loc, Func: OperatorDelete);
1086 return true;
1087}
1088
1089
1090void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body) {
1091 FunctionScopeInfo *Fn = getCurFunction();
1092 assert(Fn && Fn->isCoroutine() && "not a coroutine");
1093 if (!Body) {
1094 assert(FD->isInvalidDecl() &&
1095 "a null body is only allowed for invalid declarations");
1096 return;
1097 }
1098 // We have a function that uses coroutine keywords, but we failed to build
1099 // the promise type.
1100 if (!Fn->CoroutinePromise)
1101 return FD->setInvalidDecl();
1102
1103 if (isa<CoroutineBodyStmt>(Val: Body)) {
1104 // Nothing todo. the body is already a transformed coroutine body statement.
1105 return;
1106 }
1107
1108 // The always_inline attribute doesn't reliably apply to a coroutine,
1109 // because the coroutine will be split into pieces and some pieces
1110 // might be called indirectly, as in a virtual call. Even the ramp
1111 // function cannot be inlined at -O0, due to pipeline ordering
1112 // problems (see https://llvm.org/PR53413). Tell the user about it.
1113 if (FD->hasAttr<AlwaysInlineAttr>())
1114 Diag(FD->getLocation(), diag::warn_always_inline_coroutine);
1115
1116 // The design of coroutines means we cannot allow use of VLAs within one, so
1117 // diagnose if we've seen a VLA in the body of this function.
1118 if (Fn->FirstVLALoc.isValid())
1119 Diag(Fn->FirstVLALoc, diag::err_vla_in_coroutine_unsupported);
1120
1121 // [stmt.return.coroutine]p1:
1122 // A coroutine shall not enclose a return statement ([stmt.return]).
1123 if (Fn->FirstReturnLoc.isValid()) {
1124 assert(Fn->FirstCoroutineStmtLoc.isValid() &&
1125 "first coroutine location not set");
1126 Diag(Fn->FirstReturnLoc, diag::err_return_in_coroutine);
1127 Diag(Fn->FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1128 << Fn->getFirstCoroutineStmtKeyword();
1129 }
1130
1131 // Coroutines will get splitted into pieces. The GNU address of label
1132 // extension wouldn't be meaningful in coroutines.
1133 for (AddrLabelExpr *ALE : Fn->AddrLabels)
1134 Diag(ALE->getBeginLoc(), diag::err_coro_invalid_addr_of_label);
1135
1136 CoroutineStmtBuilder Builder(*this, *FD, *Fn, Body);
1137 if (Builder.isInvalid() || !Builder.buildStatements())
1138 return FD->setInvalidDecl();
1139
1140 // Build body for the coroutine wrapper statement.
1141 Body = CoroutineBodyStmt::Create(C: Context, Args: Builder);
1142}
1143
1144static CompoundStmt *buildCoroutineBody(Stmt *Body, ASTContext &Context) {
1145 if (auto *CS = dyn_cast<CompoundStmt>(Val: Body))
1146 return CS;
1147
1148 // The body of the coroutine may be a try statement if it is in
1149 // 'function-try-block' syntax. Here we wrap it into a compound
1150 // statement for consistency.
1151 assert(isa<CXXTryStmt>(Body) && "Unimaged coroutine body type");
1152 return CompoundStmt::Create(C: Context, Stmts: {Body}, FPFeatures: FPOptionsOverride(),
1153 LB: SourceLocation(), RB: SourceLocation());
1154}
1155
1156CoroutineStmtBuilder::CoroutineStmtBuilder(Sema &S, FunctionDecl &FD,
1157 sema::FunctionScopeInfo &Fn,
1158 Stmt *Body)
1159 : S(S), FD(FD), Fn(Fn), Loc(FD.getLocation()),
1160 IsPromiseDependentType(
1161 !Fn.CoroutinePromise ||
1162 Fn.CoroutinePromise->getType()->isDependentType()) {
1163 this->Body = buildCoroutineBody(Body, Context&: S.getASTContext());
1164
1165 for (auto KV : Fn.CoroutineParameterMoves)
1166 this->ParamMovesVector.push_back(Elt: KV.second);
1167 this->ParamMoves = this->ParamMovesVector;
1168
1169 if (!IsPromiseDependentType) {
1170 PromiseRecordDecl = Fn.CoroutinePromise->getType()->getAsCXXRecordDecl();
1171 assert(PromiseRecordDecl && "Type should have already been checked");
1172 }
1173 this->IsValid = makePromiseStmt() && makeInitialAndFinalSuspend();
1174}
1175
1176bool CoroutineStmtBuilder::buildStatements() {
1177 assert(this->IsValid && "coroutine already invalid");
1178 this->IsValid = makeReturnObject();
1179 if (this->IsValid && !IsPromiseDependentType)
1180 buildDependentStatements();
1181 return this->IsValid;
1182}
1183
1184bool CoroutineStmtBuilder::buildDependentStatements() {
1185 assert(this->IsValid && "coroutine already invalid");
1186 assert(!this->IsPromiseDependentType &&
1187 "coroutine cannot have a dependent promise type");
1188 this->IsValid = makeOnException() && makeOnFallthrough() &&
1189 makeGroDeclAndReturnStmt() && makeReturnOnAllocFailure() &&
1190 makeNewAndDeleteExpr();
1191 return this->IsValid;
1192}
1193
1194bool CoroutineStmtBuilder::makePromiseStmt() {
1195 // Form a declaration statement for the promise declaration, so that AST
1196 // visitors can more easily find it.
1197 StmtResult PromiseStmt =
1198 S.ActOnDeclStmt(Decl: S.ConvertDeclToDeclGroup(Fn.CoroutinePromise), StartLoc: Loc, EndLoc: Loc);
1199 if (PromiseStmt.isInvalid())
1200 return false;
1201
1202 this->Promise = PromiseStmt.get();
1203 return true;
1204}
1205
1206bool CoroutineStmtBuilder::makeInitialAndFinalSuspend() {
1207 if (Fn.hasInvalidCoroutineSuspends())
1208 return false;
1209 this->InitialSuspend = cast<Expr>(Val: Fn.CoroutineSuspends.first);
1210 this->FinalSuspend = cast<Expr>(Val: Fn.CoroutineSuspends.second);
1211 return true;
1212}
1213
1214static bool diagReturnOnAllocFailure(Sema &S, Expr *E,
1215 CXXRecordDecl *PromiseRecordDecl,
1216 FunctionScopeInfo &Fn) {
1217 auto Loc = E->getExprLoc();
1218 if (auto *DeclRef = dyn_cast_or_null<DeclRefExpr>(Val: E)) {
1219 auto *Decl = DeclRef->getDecl();
1220 if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(Val: Decl)) {
1221 if (Method->isStatic())
1222 return true;
1223 else
1224 Loc = Decl->getLocation();
1225 }
1226 }
1227
1228 S.Diag(
1229 Loc,
1230 diag::err_coroutine_promise_get_return_object_on_allocation_failure)
1231 << PromiseRecordDecl;
1232 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1233 << Fn.getFirstCoroutineStmtKeyword();
1234 return false;
1235}
1236
1237bool CoroutineStmtBuilder::makeReturnOnAllocFailure() {
1238 assert(!IsPromiseDependentType &&
1239 "cannot make statement while the promise type is dependent");
1240
1241 // [dcl.fct.def.coroutine]p10
1242 // If a search for the name get_return_object_on_allocation_failure in
1243 // the scope of the promise type ([class.member.lookup]) finds any
1244 // declarations, then the result of a call to an allocation function used to
1245 // obtain storage for the coroutine state is assumed to return nullptr if it
1246 // fails to obtain storage, ... If the allocation function returns nullptr,
1247 // ... and the return value is obtained by a call to
1248 // T::get_return_object_on_allocation_failure(), where T is the
1249 // promise type.
1250 DeclarationName DN =
1251 S.PP.getIdentifierInfo(Name: "get_return_object_on_allocation_failure");
1252 LookupResult Found(S, DN, Loc, Sema::LookupMemberName);
1253 if (!S.LookupQualifiedName(Found, PromiseRecordDecl))
1254 return true;
1255
1256 CXXScopeSpec SS;
1257 ExprResult DeclNameExpr =
1258 S.BuildDeclarationNameExpr(SS, R&: Found, /*NeedsADL=*/false);
1259 if (DeclNameExpr.isInvalid())
1260 return false;
1261
1262 if (!diagReturnOnAllocFailure(S, E: DeclNameExpr.get(), PromiseRecordDecl, Fn))
1263 return false;
1264
1265 ExprResult ReturnObjectOnAllocationFailure =
1266 S.BuildCallExpr(S: nullptr, Fn: DeclNameExpr.get(), LParenLoc: Loc, ArgExprs: {}, RParenLoc: Loc);
1267 if (ReturnObjectOnAllocationFailure.isInvalid())
1268 return false;
1269
1270 StmtResult ReturnStmt =
1271 S.BuildReturnStmt(ReturnLoc: Loc, RetValExp: ReturnObjectOnAllocationFailure.get());
1272 if (ReturnStmt.isInvalid()) {
1273 S.Diag(Found.getFoundDecl()->getLocation(), diag::note_member_declared_here)
1274 << DN;
1275 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1276 << Fn.getFirstCoroutineStmtKeyword();
1277 return false;
1278 }
1279
1280 this->ReturnStmtOnAllocFailure = ReturnStmt.get();
1281 return true;
1282}
1283
1284// Collect placement arguments for allocation function of coroutine FD.
1285// Return true if we collect placement arguments succesfully. Return false,
1286// otherwise.
1287static bool collectPlacementArgs(Sema &S, FunctionDecl &FD, SourceLocation Loc,
1288 SmallVectorImpl<Expr *> &PlacementArgs) {
1289 if (auto *MD = dyn_cast<CXXMethodDecl>(Val: &FD)) {
1290 if (MD->isImplicitObjectMemberFunction() && !isLambdaCallOperator(MD)) {
1291 ExprResult ThisExpr = S.ActOnCXXThis(Loc);
1292 if (ThisExpr.isInvalid())
1293 return false;
1294 ThisExpr = S.CreateBuiltinUnaryOp(OpLoc: Loc, Opc: UO_Deref, InputExpr: ThisExpr.get());
1295 if (ThisExpr.isInvalid())
1296 return false;
1297 PlacementArgs.push_back(Elt: ThisExpr.get());
1298 }
1299 }
1300
1301 for (auto *PD : FD.parameters()) {
1302 if (PD->getType()->isDependentType())
1303 continue;
1304
1305 // Build a reference to the parameter.
1306 auto PDLoc = PD->getLocation();
1307 ExprResult PDRefExpr =
1308 S.BuildDeclRefExpr(PD, PD->getOriginalType().getNonReferenceType(),
1309 ExprValueKind::VK_LValue, PDLoc);
1310 if (PDRefExpr.isInvalid())
1311 return false;
1312
1313 PlacementArgs.push_back(Elt: PDRefExpr.get());
1314 }
1315
1316 return true;
1317}
1318
1319bool CoroutineStmtBuilder::makeNewAndDeleteExpr() {
1320 // Form and check allocation and deallocation calls.
1321 assert(!IsPromiseDependentType &&
1322 "cannot make statement while the promise type is dependent");
1323 QualType PromiseType = Fn.CoroutinePromise->getType();
1324
1325 if (S.RequireCompleteType(Loc, PromiseType, diag::err_incomplete_type))
1326 return false;
1327
1328 const bool RequiresNoThrowAlloc = ReturnStmtOnAllocFailure != nullptr;
1329
1330 // According to [dcl.fct.def.coroutine]p9, Lookup allocation functions using a
1331 // parameter list composed of the requested size of the coroutine state being
1332 // allocated, followed by the coroutine function's arguments. If a matching
1333 // allocation function exists, use it. Otherwise, use an allocation function
1334 // that just takes the requested size.
1335 //
1336 // [dcl.fct.def.coroutine]p9
1337 // An implementation may need to allocate additional storage for a
1338 // coroutine.
1339 // This storage is known as the coroutine state and is obtained by calling a
1340 // non-array allocation function ([basic.stc.dynamic.allocation]). The
1341 // allocation function's name is looked up by searching for it in the scope of
1342 // the promise type.
1343 // - If any declarations are found, overload resolution is performed on a
1344 // function call created by assembling an argument list. The first argument is
1345 // the amount of space requested, and has type std::size_t. The
1346 // lvalues p1 ... pn are the succeeding arguments.
1347 //
1348 // ...where "p1 ... pn" are defined earlier as:
1349 //
1350 // [dcl.fct.def.coroutine]p3
1351 // The promise type of a coroutine is `std::coroutine_traits<R, P1, ...,
1352 // Pn>`
1353 // , where R is the return type of the function, and `P1, ..., Pn` are the
1354 // sequence of types of the non-object function parameters, preceded by the
1355 // type of the object parameter ([dcl.fct]) if the coroutine is a non-static
1356 // member function. [dcl.fct.def.coroutine]p4 In the following, p_i is an
1357 // lvalue of type P_i, where p1 denotes the object parameter and p_i+1 denotes
1358 // the i-th non-object function parameter for a non-static member function,
1359 // and p_i denotes the i-th function parameter otherwise. For a non-static
1360 // member function, q_1 is an lvalue that denotes *this; any other q_i is an
1361 // lvalue that denotes the parameter copy corresponding to p_i.
1362
1363 FunctionDecl *OperatorNew = nullptr;
1364 SmallVector<Expr *, 1> PlacementArgs;
1365
1366 const bool PromiseContainsNew = [this, &PromiseType]() -> bool {
1367 DeclarationName NewName =
1368 S.getASTContext().DeclarationNames.getCXXOperatorName(Op: OO_New);
1369 LookupResult R(S, NewName, Loc, Sema::LookupOrdinaryName);
1370
1371 if (PromiseType->isRecordType())
1372 S.LookupQualifiedName(R, PromiseType->getAsCXXRecordDecl());
1373
1374 return !R.empty() && !R.isAmbiguous();
1375 }();
1376
1377 // Helper function to indicate whether the last lookup found the aligned
1378 // allocation function.
1379 bool PassAlignment = S.getLangOpts().CoroAlignedAllocation;
1380 auto LookupAllocationFunction = [&](Sema::AllocationFunctionScope NewScope =
1381 Sema::AFS_Both,
1382 bool WithoutPlacementArgs = false,
1383 bool ForceNonAligned = false) {
1384 // [dcl.fct.def.coroutine]p9
1385 // The allocation function's name is looked up by searching for it in the
1386 // scope of the promise type.
1387 // - If any declarations are found, ...
1388 // - If no declarations are found in the scope of the promise type, a search
1389 // is performed in the global scope.
1390 if (NewScope == Sema::AFS_Both)
1391 NewScope = PromiseContainsNew ? Sema::AFS_Class : Sema::AFS_Global;
1392
1393 PassAlignment = !ForceNonAligned && S.getLangOpts().CoroAlignedAllocation;
1394 FunctionDecl *UnusedResult = nullptr;
1395 S.FindAllocationFunctions(StartLoc: Loc, Range: SourceRange(), NewScope,
1396 /*DeleteScope*/ Sema::AFS_Both, AllocType: PromiseType,
1397 /*isArray*/ IsArray: false, PassAlignment,
1398 PlaceArgs: WithoutPlacementArgs ? MultiExprArg{}
1399 : PlacementArgs,
1400 OperatorNew, OperatorDelete&: UnusedResult, /*Diagnose*/ false);
1401 };
1402
1403 // We don't expect to call to global operator new with (size, p0, …, pn).
1404 // So if we choose to lookup the allocation function in global scope, we
1405 // shouldn't lookup placement arguments.
1406 if (PromiseContainsNew && !collectPlacementArgs(S, FD, Loc, PlacementArgs))
1407 return false;
1408
1409 LookupAllocationFunction();
1410
1411 if (PromiseContainsNew && !PlacementArgs.empty()) {
1412 // [dcl.fct.def.coroutine]p9
1413 // If no viable function is found ([over.match.viable]), overload
1414 // resolution
1415 // is performed again on a function call created by passing just the amount
1416 // of space required as an argument of type std::size_t.
1417 //
1418 // Proposed Change of [dcl.fct.def.coroutine]p9 in P2014R0:
1419 // Otherwise, overload resolution is performed again on a function call
1420 // created
1421 // by passing the amount of space requested as an argument of type
1422 // std::size_t as the first argument, and the requested alignment as
1423 // an argument of type std:align_val_t as the second argument.
1424 if (!OperatorNew ||
1425 (S.getLangOpts().CoroAlignedAllocation && !PassAlignment))
1426 LookupAllocationFunction(/*NewScope*/ Sema::AFS_Class,
1427 /*WithoutPlacementArgs*/ true);
1428 }
1429
1430 // Proposed Change of [dcl.fct.def.coroutine]p12 in P2014R0:
1431 // Otherwise, overload resolution is performed again on a function call
1432 // created
1433 // by passing the amount of space requested as an argument of type
1434 // std::size_t as the first argument, and the lvalues p1 ... pn as the
1435 // succeeding arguments. Otherwise, overload resolution is performed again
1436 // on a function call created by passing just the amount of space required as
1437 // an argument of type std::size_t.
1438 //
1439 // So within the proposed change in P2014RO, the priority order of aligned
1440 // allocation functions wiht promise_type is:
1441 //
1442 // void* operator new( std::size_t, std::align_val_t, placement_args... );
1443 // void* operator new( std::size_t, std::align_val_t);
1444 // void* operator new( std::size_t, placement_args... );
1445 // void* operator new( std::size_t);
1446
1447 // Helper variable to emit warnings.
1448 bool FoundNonAlignedInPromise = false;
1449 if (PromiseContainsNew && S.getLangOpts().CoroAlignedAllocation)
1450 if (!OperatorNew || !PassAlignment) {
1451 FoundNonAlignedInPromise = OperatorNew;
1452
1453 LookupAllocationFunction(/*NewScope*/ Sema::AFS_Class,
1454 /*WithoutPlacementArgs*/ false,
1455 /*ForceNonAligned*/ true);
1456
1457 if (!OperatorNew && !PlacementArgs.empty())
1458 LookupAllocationFunction(/*NewScope*/ Sema::AFS_Class,
1459 /*WithoutPlacementArgs*/ true,
1460 /*ForceNonAligned*/ true);
1461 }
1462
1463 bool IsGlobalOverload =
1464 OperatorNew && !isa<CXXRecordDecl>(OperatorNew->getDeclContext());
1465 // If we didn't find a class-local new declaration and non-throwing new
1466 // was is required then we need to lookup the non-throwing global operator
1467 // instead.
1468 if (RequiresNoThrowAlloc && (!OperatorNew || IsGlobalOverload)) {
1469 auto *StdNoThrow = buildStdNoThrowDeclRef(S, Loc);
1470 if (!StdNoThrow)
1471 return false;
1472 PlacementArgs = {StdNoThrow};
1473 OperatorNew = nullptr;
1474 LookupAllocationFunction(Sema::AFS_Global);
1475 }
1476
1477 // If we found a non-aligned allocation function in the promise_type,
1478 // it indicates the user forgot to update the allocation function. Let's emit
1479 // a warning here.
1480 if (FoundNonAlignedInPromise) {
1481 S.Diag(OperatorNew->getLocation(),
1482 diag::warn_non_aligned_allocation_function)
1483 << &FD;
1484 }
1485
1486 if (!OperatorNew) {
1487 if (PromiseContainsNew)
1488 S.Diag(Loc, diag::err_coroutine_unusable_new) << PromiseType << &FD;
1489 else if (RequiresNoThrowAlloc)
1490 S.Diag(Loc, diag::err_coroutine_unfound_nothrow_new)
1491 << &FD << S.getLangOpts().CoroAlignedAllocation;
1492
1493 return false;
1494 }
1495
1496 if (RequiresNoThrowAlloc) {
1497 const auto *FT = OperatorNew->getType()->castAs<FunctionProtoType>();
1498 if (!FT->isNothrow(/*ResultIfDependent*/ false)) {
1499 S.Diag(OperatorNew->getLocation(),
1500 diag::err_coroutine_promise_new_requires_nothrow)
1501 << OperatorNew;
1502 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
1503 << OperatorNew;
1504 return false;
1505 }
1506 }
1507
1508 FunctionDecl *OperatorDelete = nullptr;
1509 if (!findDeleteForPromise(S, Loc, PromiseType, OperatorDelete)) {
1510 // FIXME: We should add an error here. According to:
1511 // [dcl.fct.def.coroutine]p12
1512 // If no usual deallocation function is found, the program is ill-formed.
1513 return false;
1514 }
1515
1516 Expr *FramePtr =
1517 S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_frame, {});
1518
1519 Expr *FrameSize =
1520 S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_size, {});
1521
1522 Expr *FrameAlignment = nullptr;
1523
1524 if (S.getLangOpts().CoroAlignedAllocation) {
1525 FrameAlignment =
1526 S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_align, {});
1527
1528 TypeSourceInfo *AlignValTy = getTypeSourceInfoForStdAlignValT(S, Loc);
1529 if (!AlignValTy)
1530 return false;
1531
1532 FrameAlignment = S.BuildCXXNamedCast(OpLoc: Loc, Kind: tok::kw_static_cast, Ty: AlignValTy,
1533 E: FrameAlignment, AngleBrackets: SourceRange(Loc, Loc),
1534 Parens: SourceRange(Loc, Loc))
1535 .get();
1536 }
1537
1538 // Make new call.
1539 ExprResult NewRef =
1540 S.BuildDeclRefExpr(OperatorNew, OperatorNew->getType(), VK_LValue, Loc);
1541 if (NewRef.isInvalid())
1542 return false;
1543
1544 SmallVector<Expr *, 2> NewArgs(1, FrameSize);
1545 if (S.getLangOpts().CoroAlignedAllocation && PassAlignment)
1546 NewArgs.push_back(Elt: FrameAlignment);
1547
1548 if (OperatorNew->getNumParams() > NewArgs.size())
1549 llvm::append_range(C&: NewArgs, R&: PlacementArgs);
1550
1551 ExprResult NewExpr =
1552 S.BuildCallExpr(S: S.getCurScope(), Fn: NewRef.get(), LParenLoc: Loc, ArgExprs: NewArgs, RParenLoc: Loc);
1553 NewExpr = S.ActOnFinishFullExpr(Expr: NewExpr.get(), /*DiscardedValue*/ false);
1554 if (NewExpr.isInvalid())
1555 return false;
1556
1557 // Make delete call.
1558
1559 QualType OpDeleteQualType = OperatorDelete->getType();
1560
1561 ExprResult DeleteRef =
1562 S.BuildDeclRefExpr(OperatorDelete, OpDeleteQualType, VK_LValue, Loc);
1563 if (DeleteRef.isInvalid())
1564 return false;
1565
1566 Expr *CoroFree =
1567 S.BuildBuiltinCallExpr(Loc, Builtin::BI__builtin_coro_free, {FramePtr});
1568
1569 SmallVector<Expr *, 2> DeleteArgs{CoroFree};
1570
1571 // [dcl.fct.def.coroutine]p12
1572 // The selected deallocation function shall be called with the address of
1573 // the block of storage to be reclaimed as its first argument. If a
1574 // deallocation function with a parameter of type std::size_t is
1575 // used, the size of the block is passed as the corresponding argument.
1576 const auto *OpDeleteType =
1577 OpDeleteQualType.getTypePtr()->castAs<FunctionProtoType>();
1578 if (OpDeleteType->getNumParams() > DeleteArgs.size() &&
1579 S.getASTContext().hasSameUnqualifiedType(
1580 T1: OpDeleteType->getParamType(DeleteArgs.size()), T2: FrameSize->getType()))
1581 DeleteArgs.push_back(Elt: FrameSize);
1582
1583 // Proposed Change of [dcl.fct.def.coroutine]p12 in P2014R0:
1584 // If deallocation function lookup finds a usual deallocation function with
1585 // a pointer parameter, size parameter and alignment parameter then this
1586 // will be the selected deallocation function, otherwise if lookup finds a
1587 // usual deallocation function with both a pointer parameter and a size
1588 // parameter, then this will be the selected deallocation function.
1589 // Otherwise, if lookup finds a usual deallocation function with only a
1590 // pointer parameter, then this will be the selected deallocation
1591 // function.
1592 //
1593 // So we are not forced to pass alignment to the deallocation function.
1594 if (S.getLangOpts().CoroAlignedAllocation &&
1595 OpDeleteType->getNumParams() > DeleteArgs.size() &&
1596 S.getASTContext().hasSameUnqualifiedType(
1597 T1: OpDeleteType->getParamType(DeleteArgs.size()),
1598 T2: FrameAlignment->getType()))
1599 DeleteArgs.push_back(Elt: FrameAlignment);
1600
1601 ExprResult DeleteExpr =
1602 S.BuildCallExpr(S: S.getCurScope(), Fn: DeleteRef.get(), LParenLoc: Loc, ArgExprs: DeleteArgs, RParenLoc: Loc);
1603 DeleteExpr =
1604 S.ActOnFinishFullExpr(Expr: DeleteExpr.get(), /*DiscardedValue*/ false);
1605 if (DeleteExpr.isInvalid())
1606 return false;
1607
1608 this->Allocate = NewExpr.get();
1609 this->Deallocate = DeleteExpr.get();
1610
1611 return true;
1612}
1613
1614bool CoroutineStmtBuilder::makeOnFallthrough() {
1615 assert(!IsPromiseDependentType &&
1616 "cannot make statement while the promise type is dependent");
1617
1618 // [dcl.fct.def.coroutine]/p6
1619 // If searches for the names return_void and return_value in the scope of
1620 // the promise type each find any declarations, the program is ill-formed.
1621 // [Note 1: If return_void is found, flowing off the end of a coroutine is
1622 // equivalent to a co_return with no operand. Otherwise, flowing off the end
1623 // of a coroutine results in undefined behavior ([stmt.return.coroutine]). —
1624 // end note]
1625 bool HasRVoid, HasRValue;
1626 LookupResult LRVoid =
1627 lookupMember(S, Name: "return_void", RD: PromiseRecordDecl, Loc, Res&: HasRVoid);
1628 LookupResult LRValue =
1629 lookupMember(S, Name: "return_value", RD: PromiseRecordDecl, Loc, Res&: HasRValue);
1630
1631 StmtResult Fallthrough;
1632 if (HasRVoid && HasRValue) {
1633 // FIXME Improve this diagnostic
1634 S.Diag(FD.getLocation(),
1635 diag::err_coroutine_promise_incompatible_return_functions)
1636 << PromiseRecordDecl;
1637 S.Diag(LRVoid.getRepresentativeDecl()->getLocation(),
1638 diag::note_member_first_declared_here)
1639 << LRVoid.getLookupName();
1640 S.Diag(LRValue.getRepresentativeDecl()->getLocation(),
1641 diag::note_member_first_declared_here)
1642 << LRValue.getLookupName();
1643 return false;
1644 } else if (!HasRVoid && !HasRValue) {
1645 // We need to set 'Fallthrough'. Otherwise the other analysis part might
1646 // think the coroutine has defined a return_value method. So it might emit
1647 // **false** positive warning. e.g.,
1648 //
1649 // promise_without_return_func foo() {
1650 // co_await something();
1651 // }
1652 //
1653 // Then AnalysisBasedWarning would emit a warning about `foo()` lacking a
1654 // co_return statements, which isn't correct.
1655 Fallthrough = S.ActOnNullStmt(SemiLoc: PromiseRecordDecl->getLocation());
1656 if (Fallthrough.isInvalid())
1657 return false;
1658 } else if (HasRVoid) {
1659 Fallthrough = S.BuildCoreturnStmt(Loc: FD.getLocation(), E: nullptr,
1660 /*IsImplicit=*/true);
1661 Fallthrough = S.ActOnFinishFullStmt(Stmt: Fallthrough.get());
1662 if (Fallthrough.isInvalid())
1663 return false;
1664 }
1665
1666 this->OnFallthrough = Fallthrough.get();
1667 return true;
1668}
1669
1670bool CoroutineStmtBuilder::makeOnException() {
1671 // Try to form 'p.unhandled_exception();'
1672 assert(!IsPromiseDependentType &&
1673 "cannot make statement while the promise type is dependent");
1674
1675 const bool RequireUnhandledException = S.getLangOpts().CXXExceptions;
1676
1677 if (!lookupMember(S, Name: "unhandled_exception", RD: PromiseRecordDecl, Loc)) {
1678 auto DiagID =
1679 RequireUnhandledException
1680 ? diag::err_coroutine_promise_unhandled_exception_required
1681 : diag::
1682 warn_coroutine_promise_unhandled_exception_required_with_exceptions;
1683 S.Diag(Loc, DiagID) << PromiseRecordDecl;
1684 S.Diag(PromiseRecordDecl->getLocation(), diag::note_defined_here)
1685 << PromiseRecordDecl;
1686 return !RequireUnhandledException;
1687 }
1688
1689 // If exceptions are disabled, don't try to build OnException.
1690 if (!S.getLangOpts().CXXExceptions)
1691 return true;
1692
1693 ExprResult UnhandledException = buildPromiseCall(
1694 S, Promise: Fn.CoroutinePromise, Loc, Name: "unhandled_exception", Args: std::nullopt);
1695 UnhandledException = S.ActOnFinishFullExpr(Expr: UnhandledException.get(), CC: Loc,
1696 /*DiscardedValue*/ false);
1697 if (UnhandledException.isInvalid())
1698 return false;
1699
1700 // Since the body of the coroutine will be wrapped in try-catch, it will
1701 // be incompatible with SEH __try if present in a function.
1702 if (!S.getLangOpts().Borland && Fn.FirstSEHTryLoc.isValid()) {
1703 S.Diag(Fn.FirstSEHTryLoc, diag::err_seh_in_a_coroutine_with_cxx_exceptions);
1704 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1705 << Fn.getFirstCoroutineStmtKeyword();
1706 return false;
1707 }
1708
1709 this->OnException = UnhandledException.get();
1710 return true;
1711}
1712
1713bool CoroutineStmtBuilder::makeReturnObject() {
1714 // [dcl.fct.def.coroutine]p7
1715 // The expression promise.get_return_object() is used to initialize the
1716 // returned reference or prvalue result object of a call to a coroutine.
1717 ExprResult ReturnObject = buildPromiseCall(S, Promise: Fn.CoroutinePromise, Loc,
1718 Name: "get_return_object", Args: std::nullopt);
1719 if (ReturnObject.isInvalid())
1720 return false;
1721
1722 this->ReturnValue = ReturnObject.get();
1723 return true;
1724}
1725
1726static void noteMemberDeclaredHere(Sema &S, Expr *E, FunctionScopeInfo &Fn) {
1727 if (auto *MbrRef = dyn_cast<CXXMemberCallExpr>(Val: E)) {
1728 auto *MethodDecl = MbrRef->getMethodDecl();
1729 S.Diag(MethodDecl->getLocation(), diag::note_member_declared_here)
1730 << MethodDecl;
1731 }
1732 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here)
1733 << Fn.getFirstCoroutineStmtKeyword();
1734}
1735
1736bool CoroutineStmtBuilder::makeGroDeclAndReturnStmt() {
1737 assert(!IsPromiseDependentType &&
1738 "cannot make statement while the promise type is dependent");
1739 assert(this->ReturnValue && "ReturnValue must be already formed");
1740
1741 QualType const GroType = this->ReturnValue->getType();
1742 assert(!GroType->isDependentType() &&
1743 "get_return_object type must no longer be dependent");
1744
1745 QualType const FnRetType = FD.getReturnType();
1746 assert(!FnRetType->isDependentType() &&
1747 "get_return_object type must no longer be dependent");
1748
1749 // The call to get_­return_­object is sequenced before the call to
1750 // initial_­suspend and is invoked at most once, but there are caveats
1751 // regarding on whether the prvalue result object may be initialized
1752 // directly/eager or delayed, depending on the types involved.
1753 //
1754 // More info at https://github.com/cplusplus/papers/issues/1414
1755 bool GroMatchesRetType = S.getASTContext().hasSameType(T1: GroType, T2: FnRetType);
1756
1757 if (FnRetType->isVoidType()) {
1758 ExprResult Res =
1759 S.ActOnFinishFullExpr(Expr: this->ReturnValue, CC: Loc, /*DiscardedValue*/ false);
1760 if (Res.isInvalid())
1761 return false;
1762
1763 if (!GroMatchesRetType)
1764 this->ResultDecl = Res.get();
1765 return true;
1766 }
1767
1768 if (GroType->isVoidType()) {
1769 // Trigger a nice error message.
1770 InitializedEntity Entity =
1771 InitializedEntity::InitializeResult(ReturnLoc: Loc, Type: FnRetType);
1772 S.PerformCopyInitialization(Entity, EqualLoc: SourceLocation(), Init: ReturnValue);
1773 noteMemberDeclaredHere(S, E: ReturnValue, Fn);
1774 return false;
1775 }
1776
1777 StmtResult ReturnStmt;
1778 clang::VarDecl *GroDecl = nullptr;
1779 if (GroMatchesRetType) {
1780 ReturnStmt = S.BuildReturnStmt(ReturnLoc: Loc, RetValExp: ReturnValue);
1781 } else {
1782 GroDecl = VarDecl::Create(
1783 C&: S.Context, DC: &FD, StartLoc: FD.getLocation(), IdLoc: FD.getLocation(),
1784 Id: &S.PP.getIdentifierTable().get(Name: "__coro_gro"), T: GroType,
1785 TInfo: S.Context.getTrivialTypeSourceInfo(T: GroType, Loc), S: SC_None);
1786 GroDecl->setImplicit();
1787
1788 S.CheckVariableDeclarationType(NewVD: GroDecl);
1789 if (GroDecl->isInvalidDecl())
1790 return false;
1791
1792 InitializedEntity Entity = InitializedEntity::InitializeVariable(Var: GroDecl);
1793 ExprResult Res =
1794 S.PerformCopyInitialization(Entity, EqualLoc: SourceLocation(), Init: ReturnValue);
1795 if (Res.isInvalid())
1796 return false;
1797
1798 Res = S.ActOnFinishFullExpr(Expr: Res.get(), /*DiscardedValue*/ false);
1799 if (Res.isInvalid())
1800 return false;
1801
1802 S.AddInitializerToDecl(GroDecl, Res.get(),
1803 /*DirectInit=*/false);
1804
1805 S.FinalizeDeclaration(GroDecl);
1806
1807 // Form a declaration statement for the return declaration, so that AST
1808 // visitors can more easily find it.
1809 StmtResult GroDeclStmt =
1810 S.ActOnDeclStmt(Decl: S.ConvertDeclToDeclGroup(GroDecl), StartLoc: Loc, EndLoc: Loc);
1811 if (GroDeclStmt.isInvalid())
1812 return false;
1813
1814 this->ResultDecl = GroDeclStmt.get();
1815
1816 ExprResult declRef = S.BuildDeclRefExpr(GroDecl, GroType, VK_LValue, Loc);
1817 if (declRef.isInvalid())
1818 return false;
1819
1820 ReturnStmt = S.BuildReturnStmt(ReturnLoc: Loc, RetValExp: declRef.get());
1821 }
1822
1823 if (ReturnStmt.isInvalid()) {
1824 noteMemberDeclaredHere(S, E: ReturnValue, Fn);
1825 return false;
1826 }
1827
1828 if (!GroMatchesRetType &&
1829 cast<clang::ReturnStmt>(Val: ReturnStmt.get())->getNRVOCandidate() == GroDecl)
1830 GroDecl->setNRVOVariable(true);
1831
1832 this->ReturnStmt = ReturnStmt.get();
1833 return true;
1834}
1835
1836// Create a static_cast\<T&&>(expr).
1837static Expr *castForMoving(Sema &S, Expr *E, QualType T = QualType()) {
1838 if (T.isNull())
1839 T = E->getType();
1840 QualType TargetType = S.BuildReferenceType(
1841 T, /*SpelledAsLValue*/ LValueRef: false, Loc: SourceLocation(), Entity: DeclarationName());
1842 SourceLocation ExprLoc = E->getBeginLoc();
1843 TypeSourceInfo *TargetLoc =
1844 S.Context.getTrivialTypeSourceInfo(T: TargetType, Loc: ExprLoc);
1845
1846 return S
1847 .BuildCXXNamedCast(OpLoc: ExprLoc, Kind: tok::kw_static_cast, Ty: TargetLoc, E,
1848 AngleBrackets: SourceRange(ExprLoc, ExprLoc), Parens: E->getSourceRange())
1849 .get();
1850}
1851
1852/// Build a variable declaration for move parameter.
1853static VarDecl *buildVarDecl(Sema &S, SourceLocation Loc, QualType Type,
1854 IdentifierInfo *II) {
1855 TypeSourceInfo *TInfo = S.Context.getTrivialTypeSourceInfo(T: Type, Loc);
1856 VarDecl *Decl = VarDecl::Create(C&: S.Context, DC: S.CurContext, StartLoc: Loc, IdLoc: Loc, Id: II, T: Type,
1857 TInfo, S: SC_None);
1858 Decl->setImplicit();
1859 return Decl;
1860}
1861
1862// Build statements that move coroutine function parameters to the coroutine
1863// frame, and store them on the function scope info.
1864bool Sema::buildCoroutineParameterMoves(SourceLocation Loc) {
1865 assert(isa<FunctionDecl>(CurContext) && "not in a function scope");
1866 auto *FD = cast<FunctionDecl>(Val: CurContext);
1867
1868 auto *ScopeInfo = getCurFunction();
1869 if (!ScopeInfo->CoroutineParameterMoves.empty())
1870 return false;
1871
1872 // [dcl.fct.def.coroutine]p13
1873 // When a coroutine is invoked, after initializing its parameters
1874 // ([expr.call]), a copy is created for each coroutine parameter. For a
1875 // parameter of type cv T, the copy is a variable of type cv T with
1876 // automatic storage duration that is direct-initialized from an xvalue of
1877 // type T referring to the parameter.
1878 for (auto *PD : FD->parameters()) {
1879 if (PD->getType()->isDependentType())
1880 continue;
1881
1882 // Preserve the referenced state for unused parameter diagnostics.
1883 bool DeclReferenced = PD->isReferenced();
1884
1885 ExprResult PDRefExpr =
1886 BuildDeclRefExpr(PD, PD->getType().getNonReferenceType(),
1887 ExprValueKind::VK_LValue, Loc); // FIXME: scope?
1888
1889 PD->setReferenced(DeclReferenced);
1890
1891 if (PDRefExpr.isInvalid())
1892 return false;
1893
1894 Expr *CExpr = nullptr;
1895 if (PD->getType()->getAsCXXRecordDecl() ||
1896 PD->getType()->isRValueReferenceType())
1897 CExpr = castForMoving(S&: *this, E: PDRefExpr.get());
1898 else
1899 CExpr = PDRefExpr.get();
1900 // [dcl.fct.def.coroutine]p13
1901 // The initialization and destruction of each parameter copy occurs in the
1902 // context of the called coroutine.
1903 auto *D = buildVarDecl(*this, Loc, PD->getType(), PD->getIdentifier());
1904 AddInitializerToDecl(dcl: D, init: CExpr, /*DirectInit=*/true);
1905
1906 // Convert decl to a statement.
1907 StmtResult Stmt = ActOnDeclStmt(Decl: ConvertDeclToDeclGroup(Ptr: D), StartLoc: Loc, EndLoc: Loc);
1908 if (Stmt.isInvalid())
1909 return false;
1910
1911 ScopeInfo->CoroutineParameterMoves.insert(KV: std::make_pair(x&: PD, y: Stmt.get()));
1912 }
1913 return true;
1914}
1915
1916StmtResult Sema::BuildCoroutineBodyStmt(CoroutineBodyStmt::CtorArgs Args) {
1917 CoroutineBodyStmt *Res = CoroutineBodyStmt::Create(C: Context, Args);
1918 if (!Res)
1919 return StmtError();
1920 return Res;
1921}
1922
1923ClassTemplateDecl *Sema::lookupCoroutineTraits(SourceLocation KwLoc,
1924 SourceLocation FuncLoc) {
1925 if (StdCoroutineTraitsCache)
1926 return StdCoroutineTraitsCache;
1927
1928 IdentifierInfo const &TraitIdent =
1929 PP.getIdentifierTable().get(Name: "coroutine_traits");
1930
1931 NamespaceDecl *StdSpace = getStdNamespace();
1932 LookupResult Result(*this, &TraitIdent, FuncLoc, LookupOrdinaryName);
1933 bool Found = StdSpace && LookupQualifiedName(Result, StdSpace);
1934
1935 if (!Found) {
1936 // The goggles, we found nothing!
1937 Diag(KwLoc, diag::err_implied_coroutine_type_not_found)
1938 << "std::coroutine_traits";
1939 return nullptr;
1940 }
1941
1942 // coroutine_traits is required to be a class template.
1943 StdCoroutineTraitsCache = Result.getAsSingle<ClassTemplateDecl>();
1944 if (!StdCoroutineTraitsCache) {
1945 Result.suppressDiagnostics();
1946 NamedDecl *Found = *Result.begin();
1947 Diag(Found->getLocation(), diag::err_malformed_std_coroutine_traits);
1948 return nullptr;
1949 }
1950
1951 return StdCoroutineTraitsCache;
1952}
1953

source code of clang/lib/Sema/SemaCoroutine.cpp