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/ExprCXX.h" 20#include "clang/AST/StmtCXX.h" 21#include "clang/Basic/Builtins.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" 27#include "llvm/ADT/SmallSet.h" 28 29using namespace clang; 30using namespace sema; 31 32static LookupResult lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD, 33 SourceLocation Loc, bool &Res) { 34 DeclarationName DN = S.PP.getIdentifierInfo(Name); 35 LookupResult LR(S, DN, Loc, Sema::LookupMemberName); 36 // Suppress diagnostics when a private member is selected. The same warnings 37 // will be produced again when building the call. 38 LR.suppressDiagnostics(); 39 Res = S.LookupQualifiedName(LR, RD); 40 return LR; 41} 42 43static bool lookupMember(Sema &S, const char *Name, CXXRecordDecl *RD, 44 SourceLocation Loc) { 45 bool Res; 46 lookupMember(S, Name, RD, Loc, Res); 47 return Res; 48} 49 50/// Look up the std::coroutine_traits<...>::promise_type for the given 51/// function type. 52static QualType lookupPromiseType(Sema &S, const FunctionDecl *FD, 53 SourceLocation KwLoc) { 54 const FunctionProtoType *FnType = FD->getType()->castAs<FunctionProtoType>(); 55 const SourceLocation FuncLoc = FD->getLocation(); 56 // FIXME: Cache std::coroutine_traits once we've found it. 57 NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace(); 58 if (!StdExp) { 59 S.Diag(KwLoc, diag::err_implied_coroutine_type_not_found) 60 << "std::experimental::coroutine_traits"; 61 return QualType(); 62 } 63 64 ClassTemplateDecl *CoroTraits = S.lookupCoroutineTraits(KwLoc, FuncLoc); 65 if (!CoroTraits) { 66 return QualType(); 67 } 68 69 // Form template argument list for coroutine_traits<R, P1, P2, ...> according 70 // to [dcl.fct.def.coroutine]3 71 TemplateArgumentListInfo Args(KwLoc, KwLoc); 72 auto AddArg = [&](QualType T) { 73 Args.addArgument(TemplateArgumentLoc( 74 TemplateArgument(T), S.Context.getTrivialTypeSourceInfo(T, KwLoc))); 75 }; 76 AddArg(FnType->getReturnType()); 77 // If the function is a non-static member function, add the type 78 // of the implicit object parameter before the formal parameters. 79 if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) { 80 if (MD->isInstance()) { 81 // [over.match.funcs]4 82 // For non-static member functions, the type of the implicit object 83 // parameter is 84 // -- "lvalue reference to cv X" for functions declared without a 85 // ref-qualifier or with the & ref-qualifier 86 // -- "rvalue reference to cv X" for functions declared with the && 87 // ref-qualifier 88 QualType T = MD->getThisType()->castAs<PointerType>()->getPointeeType(); 89 T = FnType->getRefQualifier() == RQ_RValue 90 ? S.Context.getRValueReferenceType(T) 91 : S.Context.getLValueReferenceType(T, /*SpelledAsLValue*/ true); 92 AddArg(T); 93 } 94 } 95 for (QualType T : FnType->getParamTypes()) 96 AddArg(T); 97 98 // Build the template-id. 99 QualType CoroTrait = 100 S.CheckTemplateIdType(TemplateName(CoroTraits), KwLoc, Args); 101 if (CoroTrait.isNull()) 102 return QualType(); 103 if (S.RequireCompleteType(KwLoc, CoroTrait, 104 diag::err_coroutine_type_missing_specialization)) 105 return QualType(); 106 107 auto *RD = CoroTrait->getAsCXXRecordDecl(); 108 assert(RD && "specialization of class template is not a class?"); 109 110 // 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>(); 115 if (!Promise) { 116 S.Diag(FuncLoc, 117 diag::err_implied_std_coroutine_traits_promise_type_not_found) 118 << RD; 119 return QualType(); 120 } 121 // The promise type is required to be a class type. 122 QualType PromiseType = S.Context.getTypeDeclType(Promise); 123 124 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); 129 }; 130 131 if (!PromiseType->getAsCXXRecordDecl()) { 132 S.Diag(FuncLoc, 133 diag::err_implied_std_coroutine_traits_promise_type_not_class) 134 << buildElaboratedType(); 135 return QualType(); 136 } 137 if (S.RequireCompleteType(FuncLoc, buildElaboratedType(), 138 diag::err_coroutine_promise_type_incomplete)) 139 return QualType(); 140 141 return PromiseType; 142} 143 144/// Look up the std::experimental::coroutine_handle<PromiseType>. 145static QualType lookupCoroutineHandleType(Sema &S, QualType PromiseType, 146 SourceLocation Loc) { 147 if (PromiseType.isNull()) 148 return QualType(); 149 150 NamespaceDecl *StdExp = S.lookupStdExperimentalNamespace(); 151 assert(StdExp && "Should already be diagnosed"); 152 153 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"; 158 return QualType(); 159 } 160 161 ClassTemplateDecl *CoroHandle = Result.getAsSingle<ClassTemplateDecl>(); 162 if (!CoroHandle) { 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); 167 return QualType(); 168 } 169 170 // 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))); 175 176 // Build the template-id. 177 QualType CoroHandleType = 178 S.CheckTemplateIdType(TemplateName(CoroHandle), Loc, Args); 179 if (CoroHandleType.isNull()) 180 return QualType(); 181 if (S.RequireCompleteType(Loc, CoroHandleType, 182 diag::err_coroutine_type_missing_specialization)) 183 return QualType(); 184 185 return CoroHandleType; 186} 187 188static bool isValidCoroutineContext(Sema &S, SourceLocation Loc, 189 StringRef Keyword) { 190 // [expr.await]p2 dictates that 'co_await' and 'co_yield' must be used within 191 // a function body. 192 // FIXME: This also covers [expr.await]p2: "An await-expression shall not 193 // appear in a default argument." But the diagnostic QoI here could be 194 // improved to inform the user that default arguments specifically are not 195 // allowed. 196 auto *FD = dyn_cast<FunctionDecl>(S.CurContext); 197 if (!FD) { 198 S.Diag(Loc, isa<ObjCMethodDecl>(S.CurContext) 199 ? diag::err_coroutine_objc_method 200 : diag::err_coroutine_outside_function) << Keyword; 201 return false; 202 } 203 204 // An enumeration for mapping the diagnostic type to the correct diagnostic 205 // selection index. 206 enum InvalidFuncDiag { 207 DiagCtor = 0, 208 DiagDtor, 209 DiagMain, 210 DiagConstexpr, 211 DiagAutoRet, 212 DiagVarargs, 213 DiagConsteval, 214 }; 215 bool Diagnosed = false; 216 auto DiagInvalid = [&](InvalidFuncDiag ID) { 217 S.Diag(Loc, diag::err_coroutine_invalid_func_context) << ID << Keyword; 218 Diagnosed = true; 219 return false; 220 }; 221 222 // Diagnose when a constructor, destructor 223 // or the function 'main' are declared as a coroutine. 224 auto *MD = dyn_cast<CXXMethodDecl>(FD); 225 // [class.ctor]p11: "A constructor shall not be a coroutine." 226 if (MD && isa<CXXConstructorDecl>(MD)) 227 return DiagInvalid(DiagCtor); 228 // [class.dtor]p17: "A destructor shall not be a coroutine." 229 else if (MD && isa<CXXDestructorDecl>(MD)) 230 return DiagInvalid(DiagDtor); 231 // [basic.start.main]p3: "The function main shall not be a coroutine." 232 else if (FD->isMain()) 233 return DiagInvalid(DiagMain); 234 235 // Emit a diagnostics for each of the following conditions which is not met. 236 // [expr.const]p2: "An expression e is a core constant expression unless the 237 // evaluation of e [...] would evaluate one of the following expressions: 238 // [...] an await-expression [...] a yield-expression." 239 if (FD->isConstexpr()) 240 DiagInvalid(FD->isConsteval() ? DiagConsteval : DiagConstexpr); 241 // [dcl.spec.auto]p15: "A function declared with a return type that uses a 242 // placeholder type shall not be a coroutine." 243 if (FD->getReturnType()->isUndeducedType()) 244 DiagInvalid(DiagAutoRet); 245 // [dcl.fct.def.coroutine]p1: "The parameter-declaration-clause of the 246 // coroutine shall not terminate with an ellipsis that is not part of a 247 // parameter-declaration." 248 if (FD->isVariadic()) 249 DiagInvalid(DiagVarargs); 250 251 return !Diagnosed; 252} 253 254static ExprResult buildOperatorCoawaitLookupExpr(Sema &SemaRef, Scope *S, 255 SourceLocation Loc) { 256 DeclarationName OpName = 257 SemaRef.Context.DeclarationNames.getCXXOperatorName(OO_Coawait); 258 LookupResult Operators(SemaRef, OpName, SourceLocation(), 259 Sema::LookupOperatorName); 260 SemaRef.LookupName(Operators, S); 261 262 assert(!Operators.isAmbiguous() && "Operator lookup cannot be ambiguous"); 263 const auto &Functions = Operators.asUnresolvedSet(); 264 bool IsOverloaded = 265 Functions.size() > 1 || 266 (Functions.size() == 1 && isa<FunctionTemplateDecl>(*Functions.begin())); 267 Expr *CoawaitOp = UnresolvedLookupExpr::Create( 268 SemaRef.Context, /*NamingClass*/ nullptr, NestedNameSpecifierLoc(), 269 DeclarationNameInfo(OpName, Loc), /*RequiresADL*/ true, IsOverloaded, 270 Functions.begin(), Functions.end()); 271 assert(CoawaitOp); 272 return CoawaitOp; 273} 274 275/// Build a call to 'operator co_await' if there is a suitable operator for 276/// the given expression. 277static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, SourceLocation Loc, 278 Expr *E, 279 UnresolvedLookupExpr *Lookup) { 280 UnresolvedSet<16> Functions; 281 Functions.append(Lookup->decls_begin(), Lookup->decls_end()); 282 return SemaRef.CreateOverloadedUnaryOp(Loc, UO_Coawait, Functions, E); 283} 284 285static ExprResult buildOperatorCoawaitCall(Sema &SemaRef, Scope *S, 286 SourceLocation Loc, Expr *E) { 287 ExprResult R = buildOperatorCoawaitLookupExpr(SemaRef, S, Loc); 288 if (R.isInvalid()) 289 return ExprError(); 290 return buildOperatorCoawaitCall(SemaRef, Loc, E, 291 cast<UnresolvedLookupExpr>(R.get())); 292} 293 294static Expr *buildBuiltinCall(Sema &S, SourceLocation Loc, Builtin::ID Id, 295 MultiExprArg CallArgs) { 296 StringRef Name = S.Context.BuiltinInfo.getName(Id); 297 LookupResult R(S, &S.Context.Idents.get(Name), Loc, Sema::LookupOrdinaryName); 298 S.LookupName(R, S.TUScope, /*AllowBuiltinCreation=*/true); 299 300 auto *BuiltInDecl = R.getAsSingle<FunctionDecl>(); 301 assert(BuiltInDecl && "failed to find builtin declaration"); 302 303 ExprResult DeclRef = 304 S.BuildDeclRefExpr(BuiltInDecl, BuiltInDecl->getType(), VK_LValue, Loc); 305 assert(DeclRef.isUsable() && "Builtin reference cannot fail"); 306 307 ExprResult Call = 308 S.BuildCallExpr(/*Scope=*/nullptr, DeclRef.get(), Loc, CallArgs, Loc); 309 310 assert(!Call.isInvalid() && "Call to builtin cannot fail!"); 311 return Call.get(); 312} 313 314static ExprResult buildCoroutineHandle(Sema &S, QualType PromiseType, 315 SourceLocation Loc) { 316 QualType CoroHandleType = lookupCoroutineHandleType(S, PromiseType, Loc); 317 if (CoroHandleType.isNull()) 318 return ExprError(); 319 320 DeclContext *LookupCtx = S.computeDeclContext(CoroHandleType); 321 LookupResult Found(S, &S.PP.getIdentifierTable().get("from_address"), Loc, 322 Sema::LookupOrdinaryName); 323 if (!S.LookupQualifiedName(Found, LookupCtx)) { 324 S.Diag(Loc, diag::err_coroutine_handle_missing_member) 325 << "from_address"; 326 return ExprError(); 327 } 328 329 Expr *FramePtr = 330 buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_frame, {}); 331 332 CXXScopeSpec SS; 333 ExprResult FromAddr = 334 S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false); 335 if (FromAddr.isInvalid()) 336 return ExprError(); 337 338 return S.BuildCallExpr(nullptr, FromAddr.get(), Loc, FramePtr, Loc); 339} 340 341struct ReadySuspendResumeResult { 342 enum AwaitCallType { ACT_Ready, ACT_Suspend, ACT_Resume }; 343 Expr *Results[3]; 344 OpaqueValueExpr *OpaqueValue; 345 bool IsInvalid; 346}; 347 348static ExprResult buildMemberCall(Sema &S, Expr *Base, SourceLocation Loc, 349 StringRef Name, MultiExprArg Args) { 350 DeclarationNameInfo NameInfo(&S.PP.getIdentifierTable().get(Name), Loc); 351 352 // FIXME: Fix BuildMemberReferenceExpr to take a const CXXScopeSpec&. 353 CXXScopeSpec SS; 354 ExprResult Result = S.BuildMemberReferenceExpr( 355 Base, Base->getType(), Loc, /*IsPtr=*/false, SS, 356 SourceLocation(), nullptr, NameInfo, /*TemplateArgs=*/nullptr, 357 /*Scope=*/nullptr); 358 if (Result.isInvalid()) 359 return ExprError(); 360 361 // We meant exactly what we asked for. No need for typo correction. 362 if (auto *TE = dyn_cast<TypoExpr>(Result.get())) { 363 S.clearDelayedTypo(TE); 364 S.Diag(Loc, diag::err_no_member) 365 << NameInfo.getName() << Base->getType()->getAsCXXRecordDecl() 366 << Base->getSourceRange(); 367 return ExprError(); 368 } 369 370 return S.BuildCallExpr(nullptr, Result.get(), Loc, Args, Loc, nullptr); 371} 372 373// See if return type is coroutine-handle and if so, invoke builtin coro-resume 374// on its address. This is to enable experimental support for coroutine-handle 375// returning await_suspend that results in a guaranteed tail call to the target 376// coroutine. 377static Expr *maybeTailCall(Sema &S, QualType RetType, Expr *E, 378 SourceLocation Loc) { 379 if (RetType->isReferenceType()) 380 return nullptr; 381 Type const *T = RetType.getTypePtr(); 382 if (!T->isClassType() && !T->isStructureType()) 383 return nullptr; 384 385 // FIXME: Add convertability check to coroutine_handle<>. Possibly via 386 // EvaluateBinaryTypeTrait(BTT_IsConvertible, ...) which is at the moment 387 // a private function in SemaExprCXX.cpp 388 389 ExprResult AddressExpr = buildMemberCall(S, E, Loc, "address", None); 390 if (AddressExpr.isInvalid()) 391 return nullptr; 392 393 Expr *JustAddress = AddressExpr.get(); 394 395 // Check that the type of AddressExpr is void* 396 if (!JustAddress->getType().getTypePtr()->isVoidPointerType()) 397 S.Diag(cast<CallExpr>(JustAddress)->getCalleeDecl()->getLocation(), 398 diag::warn_coroutine_handle_address_invalid_return_type) 399 << JustAddress->getType(); 400 401 // Clean up temporary objects so that they don't live across suspension points 402 // unnecessarily. We choose to clean up before the call to 403 // __builtin_coro_resume so that the cleanup code are not inserted in-between 404 // the resume call and return instruction, which would interfere with the 405 // musttail call contract. 406 JustAddress = S.MaybeCreateExprWithCleanups(JustAddress); 407 return buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_resume, 408 JustAddress); 409} 410 411/// Build calls to await_ready, await_suspend, and await_resume for a co_await 412/// expression. 413/// The generated AST tries to clean up temporary objects as early as 414/// possible so that they don't live across suspension points if possible. 415/// Having temporary objects living across suspension points unnecessarily can 416/// lead to large frame size, and also lead to memory corruptions if the 417/// coroutine frame is destroyed after coming back from suspension. This is done 418/// by wrapping both the await_ready call and the await_suspend call with 419/// ExprWithCleanups. In the end of this function, we also need to explicitly 420/// set cleanup state so that the CoawaitExpr is also wrapped with an 421/// ExprWithCleanups to clean up the awaiter associated with the co_await 422/// expression. 423static 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); 427 428 // Assume valid until we see otherwise. 429 // Further operations are responsible for setting IsInalid to true. 430 ReadySuspendResumeResult Calls = {{}, Operand, /*IsInvalid=*/false}; 431 432 using ACT = ReadySuspendResumeResult::AwaitCallType; 433 434 auto BuildSubExpr = [&](ACT CallType, StringRef Func, 435 MultiExprArg Arg) -> Expr * { 436 ExprResult Result = buildMemberCall(S, Operand, Loc, Func, Arg); 437 if (Result.isInvalid()) { 438 Calls.IsInvalid = true; 439 return nullptr; 440 } 441 Calls.Results[CallType] = Result.get(); 442 return Result.get(); 443 }; 444 445 CallExpr *AwaitReady = 446 cast_or_null<CallExpr>(BuildSubExpr(ACT::ACT_Ready, "await_ready", None)); 447 if (!AwaitReady) 448 return Calls; 449 if (!AwaitReady->getType()->isDependentType()) { 450 // [expr.await]p3 [...] 451 // ��� await-ready is the expression e.await_ready(), contextually converted 452 // to bool. 453 ExprResult Conv = S.PerformContextuallyConvertToBool(AwaitReady); 454 if (Conv.isInvalid()) { 455 S.Diag(AwaitReady->getDirectCallee()->getBeginLoc(), 456 diag::note_await_ready_no_bool_conversion); 457 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required) 458 << AwaitReady->getDirectCallee() << E->getSourceRange(); 459 Calls.IsInvalid = true; 460 } else 461 Calls.Results[ACT::ACT_Ready] = S.MaybeCreateExprWithCleanups(Conv.get()); 462 } 463 464 ExprResult CoroHandleRes = 465 buildCoroutineHandle(S, CoroPromise->getType(), Loc); 466 if (CoroHandleRes.isInvalid()) { 467 Calls.IsInvalid = true; 468 return Calls; 469 } 470 Expr *CoroHandle = CoroHandleRes.get(); 471 CallExpr *AwaitSuspend = cast_or_null<CallExpr>( 472 BuildSubExpr(ACT::ACT_Suspend, "await_suspend", CoroHandle)); 473 if (!AwaitSuspend) 474 return Calls; 475 if (!AwaitSuspend->getType()->isDependentType()) { 476 // [expr.await]p3 [...] 477 // - await-suspend is the expression e.await_suspend(h), which shall be 478 // a prvalue of type void, bool, or std::coroutine_handle<Z> for some 479 // type Z. 480 QualType RetType = AwaitSuspend->getCallReturnType(S.Context); 481 482 // Experimental support for coroutine_handle returning await_suspend. 483 if (Expr *TailCallSuspend = 484 maybeTailCall(S, RetType, AwaitSuspend, Loc)) 485 // Note that we don't wrap the expression with ExprWithCleanups here 486 // because that might interfere with tailcall contract (e.g. inserting 487 // clean up instructions in-between tailcall and return). Instead 488 // ExprWithCleanups is wrapped within maybeTailCall() prior to the resume 489 // call. 490 Calls.Results[ACT::ACT_Suspend] = TailCallSuspend; 491 else { 492 // non-class prvalues always have cv-unqualified types 493 if (RetType->isReferenceType() || 494 (!RetType->isBooleanType() && !RetType->isVoidType())) { 495 S.Diag(AwaitSuspend->getCalleeDecl()->getLocation(), 496 diag::err_await_suspend_invalid_return_type) 497 << RetType; 498 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required) 499 << AwaitSuspend->getDirectCallee(); 500 Calls.IsInvalid = true; 501 } else 502 Calls.Results[ACT::ACT_Suspend] = 503 S.MaybeCreateExprWithCleanups(AwaitSuspend); 504 } 505 } 506 507 BuildSubExpr(ACT::ACT_Resume, "await_resume", None); 508 509 // Make sure the awaiter object gets a chance to be cleaned up. 510 S.Cleanup.setExprNeedsCleanups(true); 511 512 return Calls; 513} 514 515static ExprResult buildPromiseCall(Sema &S, VarDecl *Promise, 516 SourceLocation Loc, StringRef Name, 517 MultiExprArg Args) { 518 519 // Form a reference to the promise. 520 ExprResult PromiseRef = S.BuildDeclRefExpr( 521 Promise, Promise->getType().getNonReferenceType(), VK_LValue, Loc); 522 if (PromiseRef.isInvalid()) 523 return ExprError(); 524 525 return buildMemberCall(S, PromiseRef.get(), Loc, Name, Args); 526} 527 528VarDecl *Sema::buildCoroutinePromise(SourceLocation Loc) { 529 assert(isa<FunctionDecl>(CurContext) && "not in a function scope"); 530 auto *FD = cast<FunctionDecl>(CurContext); 531 bool IsThisDependentType = [&] { 532 if (auto *MD = dyn_cast_or_null<CXXMethodDecl>(FD)) 533 return MD->isInstance() && MD->getThisType()->isDependentType(); 534 else 535 return false; 536 }(); 537 538 QualType T = FD->getType()->isDependentType() || IsThisDependentType 539 ? Context.DependentTy 540 : lookupPromiseType(*this, FD, Loc); 541 if (T.isNull()) 542 return nullptr; 543 544 auto *VD = VarDecl::Create(Context, FD, FD->getLocation(), FD->getLocation(), 545 &PP.getIdentifierTable().get("__promise"), T, 546 Context.getTrivialTypeSourceInfo(T, Loc), SC_None); 547 VD->setImplicit(); 548 CheckVariableDeclarationType(VD); 549 if (VD->isInvalidDecl()) 550 return nullptr; 551 552 auto *ScopeInfo = getCurFunction(); 553 554 // Build a list of arguments, based on the coroutine function's arguments, 555 // that if present will be passed to the promise type's constructor. 556 llvm::SmallVector<Expr *, 4> CtorArgExprs; 557 558 // Add implicit object parameter. 559 if (auto *MD = dyn_cast<CXXMethodDecl>(FD)) { 560 if (MD->isInstance() && !isLambdaCallOperator(MD)) { 561 ExprResult ThisExpr = ActOnCXXThis(Loc); 562 if (ThisExpr.isInvalid()) 563 return nullptr; 564 ThisExpr = CreateBuiltinUnaryOp(Loc, UO_Deref, ThisExpr.get()); 565 if (ThisExpr.isInvalid()) 566 return nullptr; 567 CtorArgExprs.push_back(ThisExpr.get()); 568 } 569 } 570 571 // Add the coroutine function's parameters. 572 auto &Moves = ScopeInfo->CoroutineParameterMoves; 573 for (auto *PD : FD->parameters()) { 574 if (PD->getType()->isDependentType()) 575 continue; 576 577 auto RefExpr = ExprEmpty(); 578 auto Move = Moves.find(PD); 579 assert(Move != Moves.end() && 580 "Coroutine function parameter not inserted into move map"); 581 // If a reference to the function parameter exists in the coroutine 582 // frame, use that reference. 583 auto *MoveDecl = 584 cast<VarDecl>(cast<DeclStmt>(Move->second)->getSingleDecl()); 585 RefExpr = 586 BuildDeclRefExpr(MoveDecl, MoveDecl->getType().getNonReferenceType(), 587 ExprValueKind::VK_LValue, FD->getLocation()); 588 if (RefExpr.isInvalid()) 589 return nullptr; 590 CtorArgExprs.push_back(RefExpr.get()); 591 } 592 593 // If we have a non-zero number of constructor arguments, try to use them. 594 // Otherwise, fall back to the promise type's default constructor. 595 if (!CtorArgExprs.empty()) { 596 // Create an initialization sequence for the promise type using the 597 // constructor arguments, wrapped in a parenthesized list expression. 598 Expr *PLE = ParenListExpr::Create(Context, FD->getLocation(), 599 CtorArgExprs, FD->getLocation()); 600 InitializedEntity Entity = InitializedEntity::InitializeVariable(VD); 601 InitializationKind Kind = InitializationKind::CreateForInit( 602 VD->getLocation(), /*DirectInit=*/true, PLE); 603 InitializationSequence InitSeq(*this, Entity, Kind, CtorArgExprs, 604 /*TopLevelOfInitList=*/false, 605 /*TreatUnavailableAsInvalid=*/false); 606 607 // Attempt to initialize the promise type with the arguments. 608 // If that fails, fall back to the promise type's default constructor. 609 if (InitSeq) { 610 ExprResult Result = InitSeq.Perform(*this, Entity, Kind, CtorArgExprs); 611 if (Result.isInvalid()) { 612 VD->setInvalidDecl(); 613 } else if (Result.get()) { 614 VD->setInit(MaybeCreateExprWithCleanups(Result.get())); 615 VD->setInitStyle(VarDecl::CallInit); 616 CheckCompleteVariableDeclaration(VD); 617 } 618 } else 619 ActOnUninitializedDecl(VD); 620 } else 621 ActOnUninitializedDecl(VD); 622 623 FD->addDecl(VD); 624 return VD; 625} 626 627/// Check that this is a context in which a coroutine suspension can appear. 628static FunctionScopeInfo *checkCoroutineContext(Sema &S, SourceLocation Loc, 629 StringRef Keyword, 630 bool IsImplicit = false) { 631 if (!isValidCoroutineContext(S, Loc, Keyword)) 632 return nullptr; 633 634 assert(isa<FunctionDecl>(S.CurContext) && "not in a function scope"); 635 636 auto *ScopeInfo = S.getCurFunction(); 637 assert(ScopeInfo && "missing function scope for function"); 638 639 if (ScopeInfo->FirstCoroutineStmtLoc.isInvalid() && !IsImplicit) 640 ScopeInfo->setFirstCoroutineStmt(Loc, Keyword); 641 642 if (ScopeInfo->CoroutinePromise) 643 return ScopeInfo; 644 645 if (!S.buildCoroutineParameterMoves(Loc)) 646 return nullptr; 647 648 ScopeInfo->CoroutinePromise = S.buildCoroutinePromise(Loc); 649 if (!ScopeInfo->CoroutinePromise) 650 return nullptr; 651 652 return ScopeInfo; 653} 654 655/// Recursively check \p E and all its children to see if any call target 656/// (including constructor call) is declared noexcept. Also any value returned 657/// from the call has a noexcept destructor. 658static void checkNoThrow(Sema &S, const Stmt *E, 659 llvm::SmallPtrSetImpl<const Decl *> &ThrowingDecls) { 660 auto checkDeclNoexcept = [&](const Decl *D, bool IsDtor = false) { 661 // In the case of dtor, the call to dtor is implicit and hence we should 662 // pass nullptr to canCalleeThrow. 663 if (Sema::canCalleeThrow(S, IsDtor ? nullptr : cast<Expr>(E), D)) { 664 if (const auto *FD = dyn_cast<FunctionDecl>(D)) { 665 // co_await promise.final_suspend() could end up calling 666 // __builtin_coro_resume for symmetric transfer if await_suspend() 667 // returns a handle. In that case, even __builtin_coro_resume is not 668 // declared as noexcept and may throw, it does not throw _into_ the 669 // coroutine that just suspended, but rather throws back out from 670 // whoever called coroutine_handle::resume(), hence we claim that 671 // logically it does not throw. 672 if (FD->getBuiltinID() == Builtin::BI__builtin_coro_resume) 673 return; 674 } 675 if (ThrowingDecls.empty()) { 676 // First time seeing an error, emit the error message. 677 S.Diag(cast<FunctionDecl>(S.CurContext)->getLocation(), 678 diag::err_coroutine_promise_final_suspend_requires_nothrow); 679 } 680 ThrowingDecls.insert(D); 681 } 682 }; 683 auto SC = E->getStmtClass(); 684 if (SC == Expr::CXXConstructExprClass) { 685 auto const *Ctor = cast<CXXConstructExpr>(E)->getConstructor(); 686 checkDeclNoexcept(Ctor); 687 // Check the corresponding destructor of the constructor. 688 checkDeclNoexcept(Ctor->getParent()->getDestructor(), true); 689 } else if (SC == Expr::CallExprClass || SC == Expr::CXXMemberCallExprClass || 690 SC == Expr::CXXOperatorCallExprClass) { 691 if (!cast<CallExpr>(E)->isTypeDependent()) { 692 checkDeclNoexcept(cast<CallExpr>(E)->getCalleeDecl()); 693 auto ReturnType = cast<CallExpr>(E)->getCallReturnType(S.getASTContext()); 694 // Check the destructor of the call return type, if any. 695 if (ReturnType.isDestructedType() == 696 QualType::DestructionKind::DK_cxx_destructor) { 697 const auto *T = 698 cast<RecordType>(ReturnType.getCanonicalType().getTypePtr()); 699 checkDeclNoexcept( 700 dyn_cast<CXXRecordDecl>(T->getDecl())->getDestructor(), true); 701 } 702 } 703 } 704 for (const auto *Child : E->children()) { 705 if (!Child) 706 continue; 707 checkNoThrow(S, Child, ThrowingDecls); 708 } 709} 710 711bool Sema::checkFinalSuspendNoThrow(const Stmt *FinalSuspend) { 712 llvm::SmallPtrSet<const Decl *, 4> ThrowingDecls; 713 // We first collect all declarations that should not throw but not declared 714 // with noexcept. We then sort them based on the location before printing. 715 // This is to avoid emitting the same note multiple times on the same 716 // declaration, and also provide a deterministic order for the messages. 717 checkNoThrow(*this, FinalSuspend, ThrowingDecls); 718 auto SortedDecls = llvm::SmallVector<const Decl *, 4>{ThrowingDecls.begin(), 719 ThrowingDecls.end()}; 720 sort(SortedDecls, [](const Decl *A, const Decl *B) { 721 return A->getEndLoc() < B->getEndLoc(); 722 }); 723 for (const auto *D : SortedDecls) { 724 Diag(D->getEndLoc(), diag::note_coroutine_function_declare_noexcept); 725 } 726 return ThrowingDecls.empty(); 727} 728 729bool Sema::ActOnCoroutineBodyStart(Scope *SC, SourceLocation KWLoc, 730 StringRef Keyword) { 731 if (!checkCoroutineContext(*this, KWLoc, Keyword)) 732 return false; 733 auto *ScopeInfo = getCurFunction(); 734 assert(ScopeInfo->CoroutinePromise); 735 736 // If we have existing coroutine statements then we have already built 737 // the initial and final suspend points. 738 if (!ScopeInfo->NeedsCoroutineSuspends) 739 return true; 740 741 ScopeInfo->setNeedsCoroutineSuspends(false); 742 743 auto *Fn = cast<FunctionDecl>(CurContext); 744 SourceLocation Loc = Fn->getLocation(); 745 // Build the initial suspend point 746 auto buildSuspends = [&](StringRef Name) mutable -> StmtResult { 747 ExprResult Suspend = 748 buildPromiseCall(*this, ScopeInfo->CoroutinePromise, Loc, Name, None); 749 if (Suspend.isInvalid()) 750 return StmtError(); 751 Suspend = buildOperatorCoawaitCall(*this, SC, Loc, Suspend.get()); 752 if (Suspend.isInvalid()) 753 return StmtError(); 754 Suspend = BuildResolvedCoawaitExpr(Loc, Suspend.get(), 755 /*IsImplicit*/ true); 756 Suspend = ActOnFinishFullExpr(Suspend.get(), /*DiscardedValue*/ false); 757 if (Suspend.isInvalid()) { 758 Diag(Loc, diag::note_coroutine_promise_suspend_implicitly_required) 759 << ((Name == "initial_suspend") ? 0 : 1); 760 Diag(KWLoc, diag::note_declared_coroutine_here) << Keyword; 761 return StmtError(); 762 } 763 return cast<Stmt>(Suspend.get()); 764 }; 765 766 StmtResult InitSuspend = buildSuspends("initial_suspend"); 767 if (InitSuspend.isInvalid()) 768 return true; 769 770 StmtResult FinalSuspend = buildSuspends("final_suspend"); 771 if (FinalSuspend.isInvalid() || !checkFinalSuspendNoThrow(FinalSuspend.get())) 772 return true; 773 774 ScopeInfo->setCoroutineSuspends(InitSuspend.get(), FinalSuspend.get()); 775 776 return true; 777} 778 779// Recursively walks up the scope hierarchy until either a 'catch' or a function 780// scope is found, whichever comes first. 781static bool isWithinCatchScope(Scope *S) { 782 // 'co_await' and 'co_yield' keywords are disallowed within catch blocks, but 783 // lambdas that use 'co_await' are allowed. The loop below ends when a 784 // function scope is found in order to ensure the following behavior: 785 // 786 // void foo() { // <- function scope 787 // try { // 788 // co_await x; // <- 'co_await' is OK within a function scope 789 // } catch { // <- catch scope 790 // co_await x; // <- 'co_await' is not OK within a catch scope 791 // []() { // <- function scope 792 // co_await x; // <- 'co_await' is OK within a function scope 793 // }(); 794 // } 795 // } 796 while (S && !(S->getFlags() & Scope::FnScope)) { 797 if (S->getFlags() & Scope::CatchScope) 798 return true; 799 S = S->getParent(); 800 } 801 return false; 802} 803 804// [expr.await]p2, emphasis added: "An await-expression shall appear only in 805// a *potentially evaluated* expression within the compound-statement of a 806// function-body *outside of a handler* [...] A context within a function 807// where an await-expression can appear is called a suspension context of the 808// function." 809static void checkSuspensionContext(Sema &S, SourceLocation Loc, 810 StringRef Keyword) { 811 // First emphasis of [expr.await]p2: must be a potentially evaluated context. 812 // That is, 'co_await' and 'co_yield' cannot appear in subexpressions of 813 // \c sizeof. 814 if (S.isUnevaluatedContext()) 815 S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword; 816 817 // Second emphasis of [expr.await]p2: must be outside of an exception handler. 818 if (isWithinCatchScope(S.getCurScope())) 819 S.Diag(Loc, diag::err_coroutine_within_handler) << Keyword; 820} 821 822ExprResult Sema::ActOnCoawaitExpr(Scope *S, SourceLocation Loc, Expr *E) { 823 if (!ActOnCoroutineBodyStart(S, Loc, "co_await")) { 824 CorrectDelayedTyposInExpr(E); 825 return ExprError(); 826 } 827 828 checkSuspensionContext(*this, Loc, "co_await"); 829 830 if (E->getType()->isPlaceholderType()) { 831 ExprResult R = CheckPlaceholderExpr(E); 832 if (R.isInvalid()) return ExprError(); 833 E = R.get(); 834 } 835 ExprResult Lookup = buildOperatorCoawaitLookupExpr(*this, S, Loc); 836 if (Lookup.isInvalid()) 837 return ExprError(); 838 return BuildUnresolvedCoawaitExpr(Loc, E, 839 cast<UnresolvedLookupExpr>(Lookup.get())); 840} 841 842ExprResult Sema::BuildUnresolvedCoawaitExpr(SourceLocation Loc, Expr *E, 843 UnresolvedLookupExpr *Lookup) { 844 auto *FSI = checkCoroutineContext(*this, Loc, "co_await"); 845 if (!FSI) 846 return ExprError(); 847 848 if (E->getType()->isPlaceholderType()) { 849 ExprResult R = CheckPlaceholderExpr(E); 850 if (R.isInvalid()) 851 return ExprError(); 852 E = R.get(); 853 } 854 855 auto *Promise = FSI->CoroutinePromise; 856 if (Promise->getType()->isDependentType()) { 857 Expr *Res = 858 new (Context) DependentCoawaitExpr(Loc, Context.DependentTy, E, Lookup); 859 return Res; 860 } 861 862 auto *RD = Promise->getType()->getAsCXXRecordDecl(); 863 if (lookupMember(*this, "await_transform", RD, Loc)) { 864 ExprResult R = buildPromiseCall(*this, Promise, Loc, "await_transform", E); 865 if (R.isInvalid()) { 866 Diag(Loc, 867 diag::note_coroutine_promise_implicit_await_transform_required_here) 868 << E->getSourceRange(); 869 return ExprError(); 870 } 871 E = R.get(); 872 } 873 ExprResult Awaitable = buildOperatorCoawaitCall(*this, Loc, E, Lookup); 874 if (Awaitable.isInvalid()) 875 return ExprError(); 876 877 return BuildResolvedCoawaitExpr(Loc, Awaitable.get()); 878} 879 880ExprResult Sema::BuildResolvedCoawaitExpr(SourceLocation Loc, Expr *E, 881 bool IsImplicit) { 882 auto *Coroutine = checkCoroutineContext(*this, Loc, "co_await", IsImplicit); 883 if (!Coroutine) 884 return ExprError(); 885 886 if (E->getType()->isPlaceholderType()) { 887 ExprResult R = CheckPlaceholderExpr(E); 888 if (R.isInvalid()) return ExprError(); 889 E = R.get(); 890 } 891 892 if (E->getType()->isDependentType()) { 893 Expr *Res = new (Context) 894 CoawaitExpr(Loc, Context.DependentTy, E, IsImplicit); 895 return Res; 896 } 897 898 // If the expression is a temporary, materialize it as an lvalue so that we 899 // can use it multiple times. 900 if (E->getValueKind() == VK_RValue) 901 E = CreateMaterializeTemporaryExpr(E->getType(), E, true); 902 903 // The location of the `co_await` token cannot be used when constructing 904 // the member call expressions since it's before the location of `Expr`, which 905 // is used as the start of the member call expression. 906 SourceLocation CallLoc = E->getExprLoc(); 907 908 // Build the await_ready, await_suspend, await_resume calls. 909 ReadySuspendResumeResult RSS = buildCoawaitCalls( 910 *this, Coroutine->CoroutinePromise, CallLoc, E); 911 if (RSS.IsInvalid) 912 return ExprError(); 913 914 Expr *Res = 915 new (Context) CoawaitExpr(Loc, E, RSS.Results[0], RSS.Results[1], 916 RSS.Results[2], RSS.OpaqueValue, IsImplicit); 917 918 return Res; 919} 920 921ExprResult Sema::ActOnCoyieldExpr(Scope *S, SourceLocation Loc, Expr *E) { 922 if (!ActOnCoroutineBodyStart(S, Loc, "co_yield")) { 923 CorrectDelayedTyposInExpr(E); 924 return ExprError(); 925 } 926 927 checkSuspensionContext(*this, Loc, "co_yield"); 928 929 // Build yield_value call. 930 ExprResult Awaitable = buildPromiseCall( 931 *this, getCurFunction()->CoroutinePromise, Loc, "yield_value", E); 932 if (Awaitable.isInvalid()) 933 return ExprError(); 934 935 // Build 'operator co_await' call. 936 Awaitable = buildOperatorCoawaitCall(*this, S, Loc, Awaitable.get()); 937 if (Awaitable.isInvalid()) 938 return ExprError(); 939 940 return BuildCoyieldExpr(Loc, Awaitable.get()); 941} 942ExprResult Sema::BuildCoyieldExpr(SourceLocation Loc, Expr *E) { 943 auto *Coroutine = checkCoroutineContext(*this, Loc, "co_yield"); 944 if (!Coroutine) 945 return ExprError(); 946 947 if (E->getType()->isPlaceholderType()) { 948 ExprResult R = CheckPlaceholderExpr(E); 949 if (R.isInvalid()) return ExprError(); 950 E = R.get(); 951 } 952 953 if (E->getType()->isDependentType()) { 954 Expr *Res = new (Context) CoyieldExpr(Loc, Context.DependentTy, E); 955 return Res; 956 } 957 958 // If the expression is a temporary, materialize it as an lvalue so that we 959 // can use it multiple times. 960 if (E->getValueKind() == VK_RValue) 961 E = CreateMaterializeTemporaryExpr(E->getType(), E, true); 962 963 // Build the await_ready, await_suspend, await_resume calls. 964 ReadySuspendResumeResult RSS = buildCoawaitCalls( 965 *this, Coroutine->CoroutinePromise, Loc, E); 966 if (RSS.IsInvalid) 967 return ExprError(); 968 969 Expr *Res = 970 new (Context) CoyieldExpr(Loc, E, RSS.Results[0], RSS.Results[1], 971 RSS.Results[2], RSS.OpaqueValue); 972 973 return Res; 974} 975 976StmtResult Sema::ActOnCoreturnStmt(Scope *S, SourceLocation Loc, Expr *E) { 977 if (!ActOnCoroutineBodyStart(S, Loc, "co_return")) { 978 CorrectDelayedTyposInExpr(E); 979 return StmtError(); 980 } 981 return BuildCoreturnStmt(Loc, E); 982} 983 984StmtResult Sema::BuildCoreturnStmt(SourceLocation Loc, Expr *E, 985 bool IsImplicit) { 986 auto *FSI = checkCoroutineContext(*this, Loc, "co_return", IsImplicit); 987 if (!FSI) 988 return StmtError(); 989 990 if (E && E->getType()->isPlaceholderType() && 991 !E->getType()->isSpecificPlaceholderType(BuiltinType::Overload)) { 992 ExprResult R = CheckPlaceholderExpr(E); 993 if (R.isInvalid()) return StmtError(); 994 E = R.get(); 995 } 996 997 // Move the return value if we can 998 if (E) { 999 const VarDecl *NRVOCandidate = this->getCopyElisionCandidate( 1000 E->getType(), E, CES_ImplicitlyMovableCXX20); 1001 if (NRVOCandidate) { 1002 InitializedEntity Entity = 1003 InitializedEntity::InitializeResult(Loc, E->getType(), NRVOCandidate); 1004 ExprResult MoveResult = this->PerformMoveOrCopyInitialization( 1005 Entity, NRVOCandidate, E->getType(), E); 1006 if (MoveResult.get()) 1007 E = MoveResult.get(); 1008 } 1009 } 1010 1011 // FIXME: If the operand is a reference to a variable that's about to go out 1012 // of scope, we should treat the operand as an xvalue for this overload 1013 // resolution. 1014 VarDecl *Promise = FSI->CoroutinePromise; 1015 ExprResult PC; 1016 if (E && (isa<InitListExpr>(E) || !E->getType()->isVoidType())) { 1017 PC = buildPromiseCall(*this, Promise, Loc, "return_value", E); 1018 } else { 1019 E = MakeFullDiscardedValueExpr(E).get(); 1020 PC = buildPromiseCall(*this, Promise, Loc, "return_void", None); 1021 } 1022 if (PC.isInvalid()) 1023 return StmtError(); 1024 1025 Expr *PCE = ActOnFinishFullExpr(PC.get(), /*DiscardedValue*/ false).get(); 1026 1027 Stmt *Res = new (Context) CoreturnStmt(Loc, E, PCE, IsImplicit); 1028 return Res; 1029} 1030 1031/// Look up the std::nothrow object. 1032static Expr *buildStdNoThrowDeclRef(Sema &S, SourceLocation Loc) { 1033 NamespaceDecl *Std = S.getStdNamespace(); 1034 assert(Std && "Should already be diagnosed"); 1035 1036 LookupResult Result(S, &S.PP.getIdentifierTable().get("nothrow"), Loc, 1037 Sema::LookupOrdinaryName); 1038 if (!S.LookupQualifiedName(Result, Std)) { 1039 // FIXME: <experimental/coroutine> should have been included already. 1040 // If we require it to include <new> then this diagnostic is no longer 1041 // needed. 1042 S.Diag(Loc, diag::err_implicit_coroutine_std_nothrow_type_not_found); 1043 return nullptr; 1044 } 1045 1046 auto *VD = Result.getAsSingle<VarDecl>(); 1047 if (!VD) { 1048 Result.suppressDiagnostics(); 1049 // We found something weird. Complain about the first thing we found. 1050 NamedDecl *Found = *Result.begin(); 1051 S.Diag(Found->getLocation(), diag::err_malformed_std_nothrow); 1052 return nullptr; 1053 } 1054 1055 ExprResult DR = S.BuildDeclRefExpr(VD, VD->getType(), VK_LValue, Loc); 1056 if (DR.isInvalid()) 1057 return nullptr; 1058 1059 return DR.get(); 1060} 1061 1062// Find an appropriate delete for the promise. 1063static FunctionDecl *findDeleteForPromise(Sema &S, SourceLocation Loc, 1064 QualType PromiseType) { 1065 FunctionDecl *OperatorDelete = nullptr; 1066 1067 DeclarationName DeleteName = 1068 S.Context.DeclarationNames.getCXXOperatorName(OO_Delete); 1069 1070 auto *PointeeRD = PromiseType->getAsCXXRecordDecl(); 1071 assert(PointeeRD && "PromiseType must be a CxxRecordDecl type"); 1072 1073 if (S.FindDeallocationFunction(Loc, PointeeRD, DeleteName, OperatorDelete)) 1074 return nullptr; 1075 1076 if (!OperatorDelete) { 1077 // Look for a global declaration. 1078 const bool CanProvideSize = S.isCompleteType(Loc, PromiseType); 1079 const bool Overaligned = false; 1080 OperatorDelete = S.FindUsualDeallocationFunction(Loc, CanProvideSize, 1081 Overaligned, DeleteName); 1082 } 1083 S.MarkFunctionReferenced(Loc, OperatorDelete); 1084 return OperatorDelete; 1085} 1086 1087 1088void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body) { 1089 FunctionScopeInfo *Fn = getCurFunction(); 1090 assert(Fn && Fn->isCoroutine() && "not a coroutine"); 1091 if (!Body) { 1092 assert(FD->isInvalidDecl() && 1093 "a null body is only allowed for invalid declarations"); 1094 return; 1095 } 1096 // We have a function that uses coroutine keywords, but we failed to build 1097 // the promise type. 1098 if (!Fn->CoroutinePromise) 1099 return FD->setInvalidDecl(); 1100 1101 if (isa<CoroutineBodyStmt>(Body)) { 1102 // Nothing todo. the body is already a transformed coroutine body statement. 1103 return; 1104 } 1105 1106 // Coroutines [stmt.return]p1: 1107 // A return statement shall not appear in a coroutine. 1108 if (Fn->FirstReturnLoc.isValid()) { 1109 assert(Fn->FirstCoroutineStmtLoc.isValid() && 1110 "first coroutine location not set"); 1111 Diag(Fn->FirstReturnLoc, diag::err_return_in_coroutine); 1112 Diag(Fn->FirstCoroutineStmtLoc, diag::note_declared_coroutine_here) 1113 << Fn->getFirstCoroutineStmtKeyword(); 1114 } 1115 CoroutineStmtBuilder Builder(*this, *FD, *Fn, Body); 1116 if (Builder.isInvalid() || !Builder.buildStatements()) 1117 return FD->setInvalidDecl(); 1118 1119 // Build body for the coroutine wrapper statement. 1120 Body = CoroutineBodyStmt::Create(Context, Builder); 1121} 1122 1123CoroutineStmtBuilder::CoroutineStmtBuilder(Sema &S, FunctionDecl &FD, 1124 sema::FunctionScopeInfo &Fn, 1125 Stmt *Body) 1126 : S(S), FD(FD), Fn(Fn), Loc(FD.getLocation()), 1127 IsPromiseDependentType( 1128 !Fn.CoroutinePromise || 1129 Fn.CoroutinePromise->getType()->isDependentType()) { 1130 this->Body = Body; 1131 1132 for (auto KV : Fn.CoroutineParameterMoves) 1133 this->ParamMovesVector.push_back(KV.second); 1134 this->ParamMoves = this->ParamMovesVector; 1135 1136 if (!IsPromiseDependentType) { 1137 PromiseRecordDecl = Fn.CoroutinePromise->getType()->getAsCXXRecordDecl(); 1138 assert(PromiseRecordDecl && "Type should have already been checked"); 1139 } 1140 this->IsValid = makePromiseStmt() && makeInitialAndFinalSuspend(); 1141} 1142 1143bool CoroutineStmtBuilder::buildStatements() { 1144 assert(this->IsValid && "coroutine already invalid"); 1145 this->IsValid = makeReturnObject(); 1146 if (this->IsValid && !IsPromiseDependentType) 1147 buildDependentStatements(); 1148 return this->IsValid; 1149} 1150 1151bool CoroutineStmtBuilder::buildDependentStatements() { 1152 assert(this->IsValid && "coroutine already invalid"); 1153 assert(!this->IsPromiseDependentType && 1154 "coroutine cannot have a dependent promise type"); 1155 this->IsValid = makeOnException() && makeOnFallthrough() && 1156 makeGroDeclAndReturnStmt() && makeReturnOnAllocFailure() && 1157 makeNewAndDeleteExpr(); 1158 return this->IsValid; 1159} 1160 1161bool CoroutineStmtBuilder::makePromiseStmt() { 1162 // Form a declaration statement for the promise declaration, so that AST 1163 // visitors can more easily find it. 1164 StmtResult PromiseStmt = 1165 S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(Fn.CoroutinePromise), Loc, Loc); 1166 if (PromiseStmt.isInvalid()) 1167 return false; 1168 1169 this->Promise = PromiseStmt.get(); 1170 return true; 1171} 1172 1173bool CoroutineStmtBuilder::makeInitialAndFinalSuspend() { 1174 if (Fn.hasInvalidCoroutineSuspends()) 1175 return false; 1176 this->InitialSuspend = cast<Expr>(Fn.CoroutineSuspends.first); 1177 this->FinalSuspend = cast<Expr>(Fn.CoroutineSuspends.second); 1178 return true; 1179} 1180 1181static bool diagReturnOnAllocFailure(Sema &S, Expr *E, 1182 CXXRecordDecl *PromiseRecordDecl, 1183 FunctionScopeInfo &Fn) { 1184 auto Loc = E->getExprLoc(); 1185 if (auto *DeclRef = dyn_cast_or_null<DeclRefExpr>(E)) { 1186 auto *Decl = DeclRef->getDecl(); 1187 if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(Decl)) { 1188 if (Method->isStatic()) 1189 return true; 1190 else 1191 Loc = Decl->getLocation(); 1192 } 1193 } 1194 1195 S.Diag( 1196 Loc, 1197 diag::err_coroutine_promise_get_return_object_on_allocation_failure) 1198 << PromiseRecordDecl; 1199 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here) 1200 << Fn.getFirstCoroutineStmtKeyword(); 1201 return false; 1202} 1203 1204bool CoroutineStmtBuilder::makeReturnOnAllocFailure() { 1205 assert(!IsPromiseDependentType && 1206 "cannot make statement while the promise type is dependent"); 1207 1208 // [dcl.fct.def.coroutine]/8 1209 // The unqualified-id get_return_object_on_allocation_failure is looked up in 1210 // the scope of class P by class member access lookup (3.4.5). ... 1211 // If an allocation function returns nullptr, ... the coroutine return value 1212 // is obtained by a call to ... get_return_object_on_allocation_failure(). 1213 1214 DeclarationName DN = 1215 S.PP.getIdentifierInfo("get_return_object_on_allocation_failure"); 1216 LookupResult Found(S, DN, Loc, Sema::LookupMemberName); 1217 if (!S.LookupQualifiedName(Found, PromiseRecordDecl)) 1218 return true; 1219 1220 CXXScopeSpec SS; 1221 ExprResult DeclNameExpr = 1222 S.BuildDeclarationNameExpr(SS, Found, /*NeedsADL=*/false); 1223 if (DeclNameExpr.isInvalid()) 1224 return false; 1225 1226 if (!diagReturnOnAllocFailure(S, DeclNameExpr.get(), PromiseRecordDecl, Fn)) 1227 return false; 1228 1229 ExprResult ReturnObjectOnAllocationFailure = 1230 S.BuildCallExpr(nullptr, DeclNameExpr.get(), Loc, {}, Loc); 1231 if (ReturnObjectOnAllocationFailure.isInvalid()) 1232 return false; 1233 1234 StmtResult ReturnStmt = 1235 S.BuildReturnStmt(Loc, ReturnObjectOnAllocationFailure.get()); 1236 if (ReturnStmt.isInvalid()) { 1237 S.Diag(Found.getFoundDecl()->getLocation(), diag::note_member_declared_here) 1238 << DN; 1239 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here) 1240 << Fn.getFirstCoroutineStmtKeyword(); 1241 return false; 1242 } 1243 1244 this->ReturnStmtOnAllocFailure = ReturnStmt.get(); 1245 return true; 1246} 1247 1248bool CoroutineStmtBuilder::makeNewAndDeleteExpr() { 1249 // Form and check allocation and deallocation calls. 1250 assert(!IsPromiseDependentType && 1251 "cannot make statement while the promise type is dependent"); 1252 QualType PromiseType = Fn.CoroutinePromise->getType(); 1253 1254 if (S.RequireCompleteType(Loc, PromiseType, diag::err_incomplete_type)) 1255 return false; 1256 1257 const bool RequiresNoThrowAlloc = ReturnStmtOnAllocFailure != nullptr; 1258 1259 // [dcl.fct.def.coroutine]/7 1260 // Lookup allocation functions using a parameter list composed of the 1261 // requested size of the coroutine state being allocated, followed by 1262 // the coroutine function's arguments. If a matching allocation function 1263 // exists, use it. Otherwise, use an allocation function that just takes 1264 // the requested size. 1265 1266 FunctionDecl *OperatorNew = nullptr; 1267 FunctionDecl *OperatorDelete = nullptr; 1268 FunctionDecl *UnusedResult = nullptr; 1269 bool PassAlignment = false; 1270 SmallVector<Expr *, 1> PlacementArgs; 1271 1272 // [dcl.fct.def.coroutine]/7 1273 // "The allocation function���s name is looked up in the scope of P. 1274 // [...] If the lookup finds an allocation function in the scope of P, 1275 // overload resolution is performed on a function call created by assembling 1276 // an argument list. The first argument is the amount of space requested, 1277 // and has type std::size_t. The lvalues p1 ... pn are the succeeding 1278 // arguments." 1279 // 1280 // ...where "p1 ... pn" are defined earlier as: 1281 // 1282 // [dcl.fct.def.coroutine]/3 1283 // "For a coroutine f that is a non-static member function, let P1 denote the 1284 // type of the implicit object parameter (13.3.1) and P2 ... Pn be the types 1285 // of the function parameters; otherwise let P1 ... Pn be the types of the 1286 // function parameters. Let p1 ... pn be lvalues denoting those objects." 1287 if (auto *MD = dyn_cast<CXXMethodDecl>(&FD)) { 1288 if (MD->isInstance() && !isLambdaCallOperator(MD)) { 1289 ExprResult ThisExpr = S.ActOnCXXThis(Loc); 1290 if (ThisExpr.isInvalid()) 1291 return false; 1292 ThisExpr = S.CreateBuiltinUnaryOp(Loc, UO_Deref, ThisExpr.get()); 1293 if (ThisExpr.isInvalid()) 1294 return false; 1295 PlacementArgs.push_back(ThisExpr.get()); 1296 } 1297 } 1298 for (auto *PD : FD.parameters()) { 1299 if (PD->getType()->isDependentType()) 1300 continue; 1301 1302 // Build a reference to the parameter. 1303 auto PDLoc = PD->getLocation(); 1304 ExprResult PDRefExpr = 1305 S.BuildDeclRefExpr(PD, PD->getOriginalType().getNonReferenceType(), 1306 ExprValueKind::VK_LValue, PDLoc); 1307 if (PDRefExpr.isInvalid()) 1308 return false; 1309 1310 PlacementArgs.push_back(PDRefExpr.get()); 1311 } 1312 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Class, 1313 /*DeleteScope*/ Sema::AFS_Both, PromiseType, 1314 /*isArray*/ false, PassAlignment, PlacementArgs, 1315 OperatorNew, UnusedResult, /*Diagnose*/ false); 1316 1317 // [dcl.fct.def.coroutine]/7 1318 // "If no matching function is found, overload resolution is performed again 1319 // on a function call created by passing just the amount of space required as 1320 // an argument of type std::size_t." 1321 if (!OperatorNew && !PlacementArgs.empty()) { 1322 PlacementArgs.clear(); 1323 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Class, 1324 /*DeleteScope*/ Sema::AFS_Both, PromiseType, 1325 /*isArray*/ false, PassAlignment, PlacementArgs, 1326 OperatorNew, UnusedResult, /*Diagnose*/ false); 1327 } 1328 1329 // [dcl.fct.def.coroutine]/7 1330 // "The allocation function���s name is looked up in the scope of P. If this 1331 // lookup fails, the allocation function���s name is looked up in the global 1332 // scope." 1333 if (!OperatorNew) { 1334 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Global, 1335 /*DeleteScope*/ Sema::AFS_Both, PromiseType, 1336 /*isArray*/ false, PassAlignment, PlacementArgs, 1337 OperatorNew, UnusedResult); 1338 } 1339 1340 bool IsGlobalOverload = 1341 OperatorNew && !isa<CXXRecordDecl>(OperatorNew->getDeclContext()); 1342 // If we didn't find a class-local new declaration and non-throwing new 1343 // was is required then we need to lookup the non-throwing global operator 1344 // instead. 1345 if (RequiresNoThrowAlloc && (!OperatorNew || IsGlobalOverload)) { 1346 auto *StdNoThrow = buildStdNoThrowDeclRef(S, Loc); 1347 if (!StdNoThrow) 1348 return false; 1349 PlacementArgs = {StdNoThrow}; 1350 OperatorNew = nullptr; 1351 S.FindAllocationFunctions(Loc, SourceRange(), /*NewScope*/ Sema::AFS_Both, 1352 /*DeleteScope*/ Sema::AFS_Both, PromiseType, 1353 /*isArray*/ false, PassAlignment, PlacementArgs, 1354 OperatorNew, UnusedResult); 1355 } 1356 1357 if (!OperatorNew) 1358 return false; 1359 1360 if (RequiresNoThrowAlloc) { 1361 const auto *FT = OperatorNew->getType()->castAs<FunctionProtoType>(); 1362 if (!FT->isNothrow(/*ResultIfDependent*/ false)) { 1363 S.Diag(OperatorNew->getLocation(), 1364 diag::err_coroutine_promise_new_requires_nothrow) 1365 << OperatorNew; 1366 S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required) 1367 << OperatorNew; 1368 return false; 1369 } 1370 } 1371 1372 if ((OperatorDelete = findDeleteForPromise(S, Loc, PromiseType)) == nullptr) 1373 return false; 1374 1375 Expr *FramePtr = 1376 buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_frame, {}); 1377 1378 Expr *FrameSize = 1379 buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_size, {}); 1380 1381 // Make new call. 1382 1383 ExprResult NewRef = 1384 S.BuildDeclRefExpr(OperatorNew, OperatorNew->getType(), VK_LValue, Loc); 1385 if (NewRef.isInvalid()) 1386 return false; 1387 1388 SmallVector<Expr *, 2> NewArgs(1, FrameSize); 1389 for (auto Arg : PlacementArgs) 1390 NewArgs.push_back(Arg); 1391 1392 ExprResult NewExpr = 1393 S.BuildCallExpr(S.getCurScope(), NewRef.get(), Loc, NewArgs, Loc); 1394 NewExpr = S.ActOnFinishFullExpr(NewExpr.get(), /*DiscardedValue*/ false); 1395 if (NewExpr.isInvalid()) 1396 return false; 1397 1398 // Make delete call. 1399 1400 QualType OpDeleteQualType = OperatorDelete->getType(); 1401 1402 ExprResult DeleteRef = 1403 S.BuildDeclRefExpr(OperatorDelete, OpDeleteQualType, VK_LValue, Loc); 1404 if (DeleteRef.isInvalid()) 1405 return false; 1406 1407 Expr *CoroFree = 1408 buildBuiltinCall(S, Loc, Builtin::BI__builtin_coro_free, {FramePtr}); 1409 1410 SmallVector<Expr *, 2> DeleteArgs{CoroFree}; 1411 1412 // Check if we need to pass the size. 1413 const auto *OpDeleteType = 1414 OpDeleteQualType.getTypePtr()->castAs<FunctionProtoType>(); 1415 if (OpDeleteType->getNumParams() > 1) 1416 DeleteArgs.push_back(FrameSize); 1417 1418 ExprResult DeleteExpr = 1419 S.BuildCallExpr(S.getCurScope(), DeleteRef.get(), Loc, DeleteArgs, Loc); 1420 DeleteExpr = 1421 S.ActOnFinishFullExpr(DeleteExpr.get(), /*DiscardedValue*/ false); 1422 if (DeleteExpr.isInvalid()) 1423 return false; 1424 1425 this->Allocate = NewExpr.get(); 1426 this->Deallocate = DeleteExpr.get(); 1427 1428 return true; 1429} 1430 1431bool CoroutineStmtBuilder::makeOnFallthrough() { 1432 assert(!IsPromiseDependentType && 1433 "cannot make statement while the promise type is dependent"); 1434 1435 // [dcl.fct.def.coroutine]/4 1436 // The unqualified-ids 'return_void' and 'return_value' are looked up in 1437 // the scope of class P. If both are found, the program is ill-formed. 1438 bool HasRVoid, HasRValue; 1439 LookupResult LRVoid = 1440 lookupMember(S, "return_void", PromiseRecordDecl, Loc, HasRVoid); 1441 LookupResult LRValue = 1442 lookupMember(S, "return_value", PromiseRecordDecl, Loc, HasRValue); 1443 1444 StmtResult Fallthrough; 1445 if (HasRVoid && HasRValue) { 1446 // FIXME Improve this diagnostic 1447 S.Diag(FD.getLocation(), 1448 diag::err_coroutine_promise_incompatible_return_functions) 1449 << PromiseRecordDecl; 1450 S.Diag(LRVoid.getRepresentativeDecl()->getLocation(), 1451 diag::note_member_first_declared_here) 1452 << LRVoid.getLookupName(); 1453 S.Diag(LRValue.getRepresentativeDecl()->getLocation(), 1454 diag::note_member_first_declared_here) 1455 << LRValue.getLookupName(); 1456 return false; 1457 } else if (!HasRVoid && !HasRValue) { 1458 // FIXME: The PDTS currently specifies this case as UB, not ill-formed. 1459 // However we still diagnose this as an error since until the PDTS is fixed. 1460 S.Diag(FD.getLocation(), 1461 diag::err_coroutine_promise_requires_return_function) 1462 << PromiseRecordDecl; 1463 S.Diag(PromiseRecordDecl->getLocation(), diag::note_defined_here) 1464 << PromiseRecordDecl; 1465 return false; 1466 } else if (HasRVoid) { 1467 // If the unqualified-id return_void is found, flowing off the end of a 1468 // coroutine is equivalent to a co_return with no operand. Otherwise, 1469 // flowing off the end of a coroutine results in undefined behavior. 1470 Fallthrough = S.BuildCoreturnStmt(FD.getLocation(), nullptr, 1471 /*IsImplicit*/false); 1472 Fallthrough = S.ActOnFinishFullStmt(Fallthrough.get()); 1473 if (Fallthrough.isInvalid()) 1474 return false; 1475 } 1476 1477 this->OnFallthrough = Fallthrough.get(); 1478 return true; 1479} 1480 1481bool CoroutineStmtBuilder::makeOnException() { 1482 // Try to form 'p.unhandled_exception();' 1483 assert(!IsPromiseDependentType && 1484 "cannot make statement while the promise type is dependent"); 1485 1486 const bool RequireUnhandledException = S.getLangOpts().CXXExceptions; 1487 1488 if (!lookupMember(S, "unhandled_exception", PromiseRecordDecl, Loc)) { 1489 auto DiagID = 1490 RequireUnhandledException 1491 ? diag::err_coroutine_promise_unhandled_exception_required 1492 : diag:: 1493 warn_coroutine_promise_unhandled_exception_required_with_exceptions; 1494 S.Diag(Loc, DiagID) << PromiseRecordDecl; 1495 S.Diag(PromiseRecordDecl->getLocation(), diag::note_defined_here) 1496 << PromiseRecordDecl; 1497 return !RequireUnhandledException; 1498 } 1499 1500 // If exceptions are disabled, don't try to build OnException. 1501 if (!S.getLangOpts().CXXExceptions) 1502 return true; 1503 1504 ExprResult UnhandledException = buildPromiseCall(S, Fn.CoroutinePromise, Loc, 1505 "unhandled_exception", None); 1506 UnhandledException = S.ActOnFinishFullExpr(UnhandledException.get(), Loc, 1507 /*DiscardedValue*/ false); 1508 if (UnhandledException.isInvalid()) 1509 return false; 1510 1511 // Since the body of the coroutine will be wrapped in try-catch, it will 1512 // be incompatible with SEH __try if present in a function. 1513 if (!S.getLangOpts().Borland && Fn.FirstSEHTryLoc.isValid()) { 1514 S.Diag(Fn.FirstSEHTryLoc, diag::err_seh_in_a_coroutine_with_cxx_exceptions); 1515 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here) 1516 << Fn.getFirstCoroutineStmtKeyword(); 1517 return false; 1518 } 1519 1520 this->OnException = UnhandledException.get(); 1521 return true; 1522} 1523 1524bool CoroutineStmtBuilder::makeReturnObject() { 1525 // Build implicit 'p.get_return_object()' expression and form initialization 1526 // of return type from it. 1527 ExprResult ReturnObject = 1528 buildPromiseCall(S, Fn.CoroutinePromise, Loc, "get_return_object", None); 1529 if (ReturnObject.isInvalid()) 1530 return false; 1531 1532 this->ReturnValue = ReturnObject.get(); 1533 return true; 1534} 1535 1536static void noteMemberDeclaredHere(Sema &S, Expr *E, FunctionScopeInfo &Fn) { 1537 if (auto *MbrRef = dyn_cast<CXXMemberCallExpr>(E)) { 1538 auto *MethodDecl = MbrRef->getMethodDecl(); 1539 S.Diag(MethodDecl->getLocation(), diag::note_member_declared_here) 1540 << MethodDecl; 1541 } 1542 S.Diag(Fn.FirstCoroutineStmtLoc, diag::note_declared_coroutine_here) 1543 << Fn.getFirstCoroutineStmtKeyword(); 1544} 1545 1546bool CoroutineStmtBuilder::makeGroDeclAndReturnStmt() { 1547 assert(!IsPromiseDependentType && 1548 "cannot make statement while the promise type is dependent"); 1549 assert(this->ReturnValue && "ReturnValue must be already formed"); 1550 1551 QualType const GroType = this->ReturnValue->getType(); 1552 assert(!GroType->isDependentType() && 1553 "get_return_object type must no longer be dependent"); 1554 1555 QualType const FnRetType = FD.getReturnType(); 1556 assert(!FnRetType->isDependentType() && 1557 "get_return_object type must no longer be dependent"); 1558 1559 if (FnRetType->isVoidType()) { 1560 ExprResult Res = 1561 S.ActOnFinishFullExpr(this->ReturnValue, Loc, /*DiscardedValue*/ false); 1562 if (Res.isInvalid()) 1563 return false; 1564 1565 this->ResultDecl = Res.get(); 1566 return true; 1567 } 1568 1569 if (GroType->isVoidType()) { 1570 // Trigger a nice error message. 1571 InitializedEntity Entity = 1572 InitializedEntity::InitializeResult(Loc, FnRetType, false); 1573 S.PerformMoveOrCopyInitialization(Entity, nullptr, FnRetType, ReturnValue); 1574 noteMemberDeclaredHere(S, ReturnValue, Fn); 1575 return false; 1576 } 1577 1578 auto *GroDecl = VarDecl::Create( 1579 S.Context, &FD, FD.getLocation(), FD.getLocation(), 1580 &S.PP.getIdentifierTable().get("__coro_gro"), GroType, 1581 S.Context.getTrivialTypeSourceInfo(GroType, Loc), SC_None); 1582 GroDecl->setImplicit(); 1583 1584 S.CheckVariableDeclarationType(GroDecl); 1585 if (GroDecl->isInvalidDecl()) 1586 return false; 1587 1588 InitializedEntity Entity = InitializedEntity::InitializeVariable(GroDecl); 1589 ExprResult Res = S.PerformMoveOrCopyInitialization(Entity, nullptr, GroType, 1590 this->ReturnValue); 1591 if (Res.isInvalid()) 1592 return false; 1593 1594 Res = S.ActOnFinishFullExpr(Res.get(), /*DiscardedValue*/ false); 1595 if (Res.isInvalid()) 1596 return false; 1597 1598 S.AddInitializerToDecl(GroDecl, Res.get(), 1599 /*DirectInit=*/false); 1600 1601 S.FinalizeDeclaration(GroDecl); 1602 1603 // Form a declaration statement for the return declaration, so that AST 1604 // visitors can more easily find it. 1605 StmtResult GroDeclStmt = 1606 S.ActOnDeclStmt(S.ConvertDeclToDeclGroup(GroDecl), Loc, Loc); 1607 if (GroDeclStmt.isInvalid()) 1608 return false; 1609 1610 this->ResultDecl = GroDeclStmt.get(); 1611 1612 ExprResult declRef = S.BuildDeclRefExpr(GroDecl, GroType, VK_LValue, Loc); 1613 if (declRef.isInvalid()) 1614 return false; 1615 1616 StmtResult ReturnStmt = S.BuildReturnStmt(Loc, declRef.get()); 1617 if (ReturnStmt.isInvalid()) { 1618 noteMemberDeclaredHere(S, ReturnValue, Fn); 1619 return false; 1620 } 1621 if (cast<clang::ReturnStmt>(ReturnStmt.get())->getNRVOCandidate() == GroDecl) 1622 GroDecl->setNRVOVariable(true); 1623 1624 this->ReturnStmt = ReturnStmt.get(); 1625 return true; 1626} 1627 1628// Create a static_cast\<T&&>(expr). 1629static Expr *castForMoving(Sema &S, Expr *E, QualType T = QualType()) { 1630 if (T.isNull()) 1631 T = E->getType(); 1632 QualType TargetType = S.BuildReferenceType( 1633 T, /*SpelledAsLValue*/ false, SourceLocation(), DeclarationName()); 1634 SourceLocation ExprLoc = E->getBeginLoc(); 1635 TypeSourceInfo *TargetLoc = 1636 S.Context.getTrivialTypeSourceInfo(TargetType, ExprLoc); 1637 1638 return S 1639 .BuildCXXNamedCast(ExprLoc, tok::kw_static_cast, TargetLoc, E, 1640 SourceRange(ExprLoc, ExprLoc), E->getSourceRange()) 1641 .get(); 1642} 1643 1644/// Build a variable declaration for move parameter. 1645static VarDecl *buildVarDecl(Sema &S, SourceLocation Loc, QualType Type, 1646 IdentifierInfo *II) { 1647 TypeSourceInfo *TInfo = S.Context.getTrivialTypeSourceInfo(Type, Loc); 1648 VarDecl *Decl = VarDecl::Create(S.Context, S.CurContext, Loc, Loc, II, Type, 1649 TInfo, SC_None); 1650 Decl->setImplicit(); 1651 return Decl; 1652} 1653 1654// Build statements that move coroutine function parameters to the coroutine 1655// frame, and store them on the function scope info. 1656bool Sema::buildCoroutineParameterMoves(SourceLocation Loc) { 1657 assert(isa<FunctionDecl>(CurContext) && "not in a function scope"); 1658 auto *FD = cast<FunctionDecl>(CurContext); 1659 1660 auto *ScopeInfo = getCurFunction(); 1661 if (!ScopeInfo->CoroutineParameterMoves.empty()) 1662 return false; 1663 1664 for (auto *PD : FD->parameters()) { 1665 if (PD->getType()->isDependentType()) 1666 continue; 1667 1668 ExprResult PDRefExpr = 1669 BuildDeclRefExpr(PD, PD->getType().getNonReferenceType(), 1670 ExprValueKind::VK_LValue, Loc); // FIXME: scope? 1671 if (PDRefExpr.isInvalid()) 1672 return false; 1673 1674 Expr *CExpr = nullptr; 1675 if (PD->getType()->getAsCXXRecordDecl() || 1676 PD->getType()->isRValueReferenceType()) 1677 CExpr = castForMoving(*this, PDRefExpr.get()); 1678 else 1679 CExpr = PDRefExpr.get(); 1680 1681 auto D = buildVarDecl(*this, Loc, PD->getType(), PD->getIdentifier()); 1682 AddInitializerToDecl(D, CExpr, /*DirectInit=*/true); 1683 1684 // Convert decl to a statement. 1685 StmtResult Stmt = ActOnDeclStmt(ConvertDeclToDeclGroup(D), Loc, Loc); 1686 if (Stmt.isInvalid()) 1687 return false; 1688 1689 ScopeInfo->CoroutineParameterMoves.insert(std::make_pair(PD, Stmt.get())); 1690 } 1691 return true; 1692} 1693 1694StmtResult Sema::BuildCoroutineBodyStmt(CoroutineBodyStmt::CtorArgs Args) { 1695 CoroutineBodyStmt *Res = CoroutineBodyStmt::Create(Context, Args); 1696 if (!Res) 1697 return StmtError(); 1698 return Res; 1699} 1700 1701ClassTemplateDecl *Sema::lookupCoroutineTraits(SourceLocation KwLoc, 1702 SourceLocation FuncLoc) { 1703 if (!StdCoroutineTraitsCache) { 1704 if (auto StdExp = lookupStdExperimentalNamespace()) { 1705 LookupResult Result(*this, 1706 &PP.getIdentifierTable().get("coroutine_traits"), 1707 FuncLoc, LookupOrdinaryName); 1708 if (!LookupQualifiedName(Result, StdExp)) { 1709 Diag(KwLoc, diag::err_implied_coroutine_type_not_found) 1710 << "std::experimental::coroutine_traits"; 1711 return nullptr; 1712 } 1713 if (!(StdCoroutineTraitsCache = 1714 Result.getAsSingle<ClassTemplateDecl>())) { 1715 Result.suppressDiagnostics(); 1716 NamedDecl *Found = *Result.begin(); 1717 Diag(Found->getLocation(), diag::err_malformed_std_coroutine_traits); 1718 return nullptr; 1719 } 1720 } 1721 } 1722 return StdCoroutineTraitsCache; 1723} 1724