SemaCast.cpp revision 314564
1//===--- SemaCast.cpp - Semantic Analysis for Casts -----------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements semantic analysis for cast expressions, including 11// 1) C-style casts like '(int) x' 12// 2) C++ functional casts like 'int(x)' 13// 3) C++ named casts like 'static_cast<int>(x)' 14// 15//===----------------------------------------------------------------------===// 16 17#include "clang/Sema/SemaInternal.h" 18#include "clang/AST/ASTContext.h" 19#include "clang/AST/CXXInheritance.h" 20#include "clang/AST/ExprCXX.h" 21#include "clang/AST/ExprObjC.h" 22#include "clang/AST/RecordLayout.h" 23#include "clang/Basic/PartialDiagnostic.h" 24#include "clang/Basic/TargetInfo.h" 25#include "clang/Lex/Preprocessor.h" 26#include "clang/Sema/Initialization.h" 27#include "llvm/ADT/SmallVector.h" 28#include <set> 29using namespace clang; 30 31 32 33enum TryCastResult { 34 TC_NotApplicable, ///< The cast method is not applicable. 35 TC_Success, ///< The cast method is appropriate and successful. 36 TC_Failed ///< The cast method is appropriate, but failed. A 37 ///< diagnostic has been emitted. 38}; 39 40enum CastType { 41 CT_Const, ///< const_cast 42 CT_Static, ///< static_cast 43 CT_Reinterpret, ///< reinterpret_cast 44 CT_Dynamic, ///< dynamic_cast 45 CT_CStyle, ///< (Type)expr 46 CT_Functional ///< Type(expr) 47}; 48 49namespace { 50 struct CastOperation { 51 CastOperation(Sema &S, QualType destType, ExprResult src) 52 : Self(S), SrcExpr(src), DestType(destType), 53 ResultType(destType.getNonLValueExprType(S.Context)), 54 ValueKind(Expr::getValueKindForType(destType)), 55 Kind(CK_Dependent), IsARCUnbridgedCast(false) { 56 57 if (const BuiltinType *placeholder = 58 src.get()->getType()->getAsPlaceholderType()) { 59 PlaceholderKind = placeholder->getKind(); 60 } else { 61 PlaceholderKind = (BuiltinType::Kind) 0; 62 } 63 } 64 65 Sema &Self; 66 ExprResult SrcExpr; 67 QualType DestType; 68 QualType ResultType; 69 ExprValueKind ValueKind; 70 CastKind Kind; 71 BuiltinType::Kind PlaceholderKind; 72 CXXCastPath BasePath; 73 bool IsARCUnbridgedCast; 74 75 SourceRange OpRange; 76 SourceRange DestRange; 77 78 // Top-level semantics-checking routines. 79 void CheckConstCast(); 80 void CheckReinterpretCast(); 81 void CheckStaticCast(); 82 void CheckDynamicCast(); 83 void CheckCXXCStyleCast(bool FunctionalCast, bool ListInitialization); 84 void CheckCStyleCast(); 85 86 /// Complete an apparently-successful cast operation that yields 87 /// the given expression. 88 ExprResult complete(CastExpr *castExpr) { 89 // If this is an unbridged cast, wrap the result in an implicit 90 // cast that yields the unbridged-cast placeholder type. 91 if (IsARCUnbridgedCast) { 92 castExpr = ImplicitCastExpr::Create(Self.Context, 93 Self.Context.ARCUnbridgedCastTy, 94 CK_Dependent, castExpr, nullptr, 95 castExpr->getValueKind()); 96 } 97 return castExpr; 98 } 99 100 // Internal convenience methods. 101 102 /// Try to handle the given placeholder expression kind. Return 103 /// true if the source expression has the appropriate placeholder 104 /// kind. A placeholder can only be claimed once. 105 bool claimPlaceholder(BuiltinType::Kind K) { 106 if (PlaceholderKind != K) return false; 107 108 PlaceholderKind = (BuiltinType::Kind) 0; 109 return true; 110 } 111 112 bool isPlaceholder() const { 113 return PlaceholderKind != 0; 114 } 115 bool isPlaceholder(BuiltinType::Kind K) const { 116 return PlaceholderKind == K; 117 } 118 119 void checkCastAlign() { 120 Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange); 121 } 122 123 void checkObjCARCConversion(Sema::CheckedConversionKind CCK) { 124 assert(Self.getLangOpts().ObjCAutoRefCount); 125 126 Expr *src = SrcExpr.get(); 127 if (Self.CheckObjCARCConversion(OpRange, DestType, src, CCK) == 128 Sema::ACR_unbridged) 129 IsARCUnbridgedCast = true; 130 SrcExpr = src; 131 } 132 133 /// Check for and handle non-overload placeholder expressions. 134 void checkNonOverloadPlaceholders() { 135 if (!isPlaceholder() || isPlaceholder(BuiltinType::Overload)) 136 return; 137 138 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get()); 139 if (SrcExpr.isInvalid()) 140 return; 141 PlaceholderKind = (BuiltinType::Kind) 0; 142 } 143 }; 144} 145 146// The Try functions attempt a specific way of casting. If they succeed, they 147// return TC_Success. If their way of casting is not appropriate for the given 148// arguments, they return TC_NotApplicable and *may* set diag to a diagnostic 149// to emit if no other way succeeds. If their way of casting is appropriate but 150// fails, they return TC_Failed and *must* set diag; they can set it to 0 if 151// they emit a specialized diagnostic. 152// All diagnostics returned by these functions must expect the same three 153// arguments: 154// %0: Cast Type (a value from the CastType enumeration) 155// %1: Source Type 156// %2: Destination Type 157static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, 158 QualType DestType, bool CStyle, 159 CastKind &Kind, 160 CXXCastPath &BasePath, 161 unsigned &msg); 162static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, 163 QualType DestType, bool CStyle, 164 SourceRange OpRange, 165 unsigned &msg, 166 CastKind &Kind, 167 CXXCastPath &BasePath); 168static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType, 169 QualType DestType, bool CStyle, 170 SourceRange OpRange, 171 unsigned &msg, 172 CastKind &Kind, 173 CXXCastPath &BasePath); 174static TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType, 175 CanQualType DestType, bool CStyle, 176 SourceRange OpRange, 177 QualType OrigSrcType, 178 QualType OrigDestType, unsigned &msg, 179 CastKind &Kind, 180 CXXCastPath &BasePath); 181static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, 182 QualType SrcType, 183 QualType DestType,bool CStyle, 184 SourceRange OpRange, 185 unsigned &msg, 186 CastKind &Kind, 187 CXXCastPath &BasePath); 188 189static TryCastResult TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, 190 QualType DestType, 191 Sema::CheckedConversionKind CCK, 192 SourceRange OpRange, 193 unsigned &msg, CastKind &Kind, 194 bool ListInitialization); 195static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, 196 QualType DestType, 197 Sema::CheckedConversionKind CCK, 198 SourceRange OpRange, 199 unsigned &msg, CastKind &Kind, 200 CXXCastPath &BasePath, 201 bool ListInitialization); 202static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr, 203 QualType DestType, bool CStyle, 204 unsigned &msg); 205static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr, 206 QualType DestType, bool CStyle, 207 SourceRange OpRange, 208 unsigned &msg, 209 CastKind &Kind); 210 211 212/// ActOnCXXNamedCast - Parse {dynamic,static,reinterpret,const}_cast's. 213ExprResult 214Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind, 215 SourceLocation LAngleBracketLoc, Declarator &D, 216 SourceLocation RAngleBracketLoc, 217 SourceLocation LParenLoc, Expr *E, 218 SourceLocation RParenLoc) { 219 220 assert(!D.isInvalidType()); 221 222 TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, E->getType()); 223 if (D.isInvalidType()) 224 return ExprError(); 225 226 if (getLangOpts().CPlusPlus) { 227 // Check that there are no default arguments (C++ only). 228 CheckExtraCXXDefaultArguments(D); 229 } 230 231 return BuildCXXNamedCast(OpLoc, Kind, TInfo, E, 232 SourceRange(LAngleBracketLoc, RAngleBracketLoc), 233 SourceRange(LParenLoc, RParenLoc)); 234} 235 236ExprResult 237Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind, 238 TypeSourceInfo *DestTInfo, Expr *E, 239 SourceRange AngleBrackets, SourceRange Parens) { 240 ExprResult Ex = E; 241 QualType DestType = DestTInfo->getType(); 242 243 // If the type is dependent, we won't do the semantic analysis now. 244 bool TypeDependent = 245 DestType->isDependentType() || Ex.get()->isTypeDependent(); 246 247 CastOperation Op(*this, DestType, E); 248 Op.OpRange = SourceRange(OpLoc, Parens.getEnd()); 249 Op.DestRange = AngleBrackets; 250 251 switch (Kind) { 252 default: llvm_unreachable("Unknown C++ cast!"); 253 254 case tok::kw_const_cast: 255 if (!TypeDependent) { 256 Op.CheckConstCast(); 257 if (Op.SrcExpr.isInvalid()) 258 return ExprError(); 259 DiscardMisalignedMemberAddress(DestType.getTypePtr(), E); 260 } 261 return Op.complete(CXXConstCastExpr::Create(Context, Op.ResultType, 262 Op.ValueKind, Op.SrcExpr.get(), DestTInfo, 263 OpLoc, Parens.getEnd(), 264 AngleBrackets)); 265 266 case tok::kw_dynamic_cast: { 267 if (!TypeDependent) { 268 Op.CheckDynamicCast(); 269 if (Op.SrcExpr.isInvalid()) 270 return ExprError(); 271 } 272 return Op.complete(CXXDynamicCastExpr::Create(Context, Op.ResultType, 273 Op.ValueKind, Op.Kind, Op.SrcExpr.get(), 274 &Op.BasePath, DestTInfo, 275 OpLoc, Parens.getEnd(), 276 AngleBrackets)); 277 } 278 case tok::kw_reinterpret_cast: { 279 if (!TypeDependent) { 280 Op.CheckReinterpretCast(); 281 if (Op.SrcExpr.isInvalid()) 282 return ExprError(); 283 DiscardMisalignedMemberAddress(DestType.getTypePtr(), E); 284 } 285 return Op.complete(CXXReinterpretCastExpr::Create(Context, Op.ResultType, 286 Op.ValueKind, Op.Kind, Op.SrcExpr.get(), 287 nullptr, DestTInfo, OpLoc, 288 Parens.getEnd(), 289 AngleBrackets)); 290 } 291 case tok::kw_static_cast: { 292 if (!TypeDependent) { 293 Op.CheckStaticCast(); 294 if (Op.SrcExpr.isInvalid()) 295 return ExprError(); 296 DiscardMisalignedMemberAddress(DestType.getTypePtr(), E); 297 } 298 299 return Op.complete(CXXStaticCastExpr::Create(Context, Op.ResultType, 300 Op.ValueKind, Op.Kind, Op.SrcExpr.get(), 301 &Op.BasePath, DestTInfo, 302 OpLoc, Parens.getEnd(), 303 AngleBrackets)); 304 } 305 } 306} 307 308/// Try to diagnose a failed overloaded cast. Returns true if 309/// diagnostics were emitted. 310static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT, 311 SourceRange range, Expr *src, 312 QualType destType, 313 bool listInitialization) { 314 switch (CT) { 315 // These cast kinds don't consider user-defined conversions. 316 case CT_Const: 317 case CT_Reinterpret: 318 case CT_Dynamic: 319 return false; 320 321 // These do. 322 case CT_Static: 323 case CT_CStyle: 324 case CT_Functional: 325 break; 326 } 327 328 QualType srcType = src->getType(); 329 if (!destType->isRecordType() && !srcType->isRecordType()) 330 return false; 331 332 InitializedEntity entity = InitializedEntity::InitializeTemporary(destType); 333 InitializationKind initKind 334 = (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(), 335 range, listInitialization) 336 : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range, 337 listInitialization) 338 : InitializationKind::CreateCast(/*type range?*/ range); 339 InitializationSequence sequence(S, entity, initKind, src); 340 341 assert(sequence.Failed() && "initialization succeeded on second try?"); 342 switch (sequence.getFailureKind()) { 343 default: return false; 344 345 case InitializationSequence::FK_ConstructorOverloadFailed: 346 case InitializationSequence::FK_UserConversionOverloadFailed: 347 break; 348 } 349 350 OverloadCandidateSet &candidates = sequence.getFailedCandidateSet(); 351 352 unsigned msg = 0; 353 OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates; 354 355 switch (sequence.getFailedOverloadResult()) { 356 case OR_Success: llvm_unreachable("successful failed overload"); 357 case OR_No_Viable_Function: 358 if (candidates.empty()) 359 msg = diag::err_ovl_no_conversion_in_cast; 360 else 361 msg = diag::err_ovl_no_viable_conversion_in_cast; 362 howManyCandidates = OCD_AllCandidates; 363 break; 364 365 case OR_Ambiguous: 366 msg = diag::err_ovl_ambiguous_conversion_in_cast; 367 howManyCandidates = OCD_ViableCandidates; 368 break; 369 370 case OR_Deleted: 371 msg = diag::err_ovl_deleted_conversion_in_cast; 372 howManyCandidates = OCD_ViableCandidates; 373 break; 374 } 375 376 S.Diag(range.getBegin(), msg) 377 << CT << srcType << destType 378 << range << src->getSourceRange(); 379 380 candidates.NoteCandidates(S, howManyCandidates, src); 381 382 return true; 383} 384 385/// Diagnose a failed cast. 386static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType, 387 SourceRange opRange, Expr *src, QualType destType, 388 bool listInitialization) { 389 if (msg == diag::err_bad_cxx_cast_generic && 390 tryDiagnoseOverloadedCast(S, castType, opRange, src, destType, 391 listInitialization)) 392 return; 393 394 S.Diag(opRange.getBegin(), msg) << castType 395 << src->getType() << destType << opRange << src->getSourceRange(); 396 397 // Detect if both types are (ptr to) class, and note any incompleteness. 398 int DifferentPtrness = 0; 399 QualType From = destType; 400 if (auto Ptr = From->getAs<PointerType>()) { 401 From = Ptr->getPointeeType(); 402 DifferentPtrness++; 403 } 404 QualType To = src->getType(); 405 if (auto Ptr = To->getAs<PointerType>()) { 406 To = Ptr->getPointeeType(); 407 DifferentPtrness--; 408 } 409 if (!DifferentPtrness) { 410 auto RecFrom = From->getAs<RecordType>(); 411 auto RecTo = To->getAs<RecordType>(); 412 if (RecFrom && RecTo) { 413 auto DeclFrom = RecFrom->getAsCXXRecordDecl(); 414 if (!DeclFrom->isCompleteDefinition()) 415 S.Diag(DeclFrom->getLocation(), diag::note_type_incomplete) 416 << DeclFrom->getDeclName(); 417 auto DeclTo = RecTo->getAsCXXRecordDecl(); 418 if (!DeclTo->isCompleteDefinition()) 419 S.Diag(DeclTo->getLocation(), diag::note_type_incomplete) 420 << DeclTo->getDeclName(); 421 } 422 } 423} 424 425/// UnwrapDissimilarPointerTypes - Like Sema::UnwrapSimilarPointerTypes, 426/// this removes one level of indirection from both types, provided that they're 427/// the same kind of pointer (plain or to-member). Unlike the Sema function, 428/// this one doesn't care if the two pointers-to-member don't point into the 429/// same class. This is because CastsAwayConstness doesn't care. 430static bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) { 431 const PointerType *T1PtrType = T1->getAs<PointerType>(), 432 *T2PtrType = T2->getAs<PointerType>(); 433 if (T1PtrType && T2PtrType) { 434 T1 = T1PtrType->getPointeeType(); 435 T2 = T2PtrType->getPointeeType(); 436 return true; 437 } 438 const ObjCObjectPointerType *T1ObjCPtrType = 439 T1->getAs<ObjCObjectPointerType>(), 440 *T2ObjCPtrType = 441 T2->getAs<ObjCObjectPointerType>(); 442 if (T1ObjCPtrType) { 443 if (T2ObjCPtrType) { 444 T1 = T1ObjCPtrType->getPointeeType(); 445 T2 = T2ObjCPtrType->getPointeeType(); 446 return true; 447 } 448 else if (T2PtrType) { 449 T1 = T1ObjCPtrType->getPointeeType(); 450 T2 = T2PtrType->getPointeeType(); 451 return true; 452 } 453 } 454 else if (T2ObjCPtrType) { 455 if (T1PtrType) { 456 T2 = T2ObjCPtrType->getPointeeType(); 457 T1 = T1PtrType->getPointeeType(); 458 return true; 459 } 460 } 461 462 const MemberPointerType *T1MPType = T1->getAs<MemberPointerType>(), 463 *T2MPType = T2->getAs<MemberPointerType>(); 464 if (T1MPType && T2MPType) { 465 T1 = T1MPType->getPointeeType(); 466 T2 = T2MPType->getPointeeType(); 467 return true; 468 } 469 470 const BlockPointerType *T1BPType = T1->getAs<BlockPointerType>(), 471 *T2BPType = T2->getAs<BlockPointerType>(); 472 if (T1BPType && T2BPType) { 473 T1 = T1BPType->getPointeeType(); 474 T2 = T2BPType->getPointeeType(); 475 return true; 476 } 477 478 return false; 479} 480 481/// CastsAwayConstness - Check if the pointer conversion from SrcType to 482/// DestType casts away constness as defined in C++ 5.2.11p8ff. This is used by 483/// the cast checkers. Both arguments must denote pointer (possibly to member) 484/// types. 485/// 486/// \param CheckCVR Whether to check for const/volatile/restrict qualifiers. 487/// 488/// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers. 489static bool 490CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, 491 bool CheckCVR, bool CheckObjCLifetime, 492 QualType *TheOffendingSrcType = nullptr, 493 QualType *TheOffendingDestType = nullptr, 494 Qualifiers *CastAwayQualifiers = nullptr) { 495 // If the only checking we care about is for Objective-C lifetime qualifiers, 496 // and we're not in ObjC mode, there's nothing to check. 497 if (!CheckCVR && CheckObjCLifetime && 498 !Self.Context.getLangOpts().ObjC1) 499 return false; 500 501 // Casting away constness is defined in C++ 5.2.11p8 with reference to 502 // C++ 4.4. We piggyback on Sema::IsQualificationConversion for this, since 503 // the rules are non-trivial. So first we construct Tcv *...cv* as described 504 // in C++ 5.2.11p8. 505 assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() || 506 SrcType->isBlockPointerType()) && 507 "Source type is not pointer or pointer to member."); 508 assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() || 509 DestType->isBlockPointerType()) && 510 "Destination type is not pointer or pointer to member."); 511 512 QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType), 513 UnwrappedDestType = Self.Context.getCanonicalType(DestType); 514 SmallVector<Qualifiers, 8> cv1, cv2; 515 516 // Find the qualifiers. We only care about cvr-qualifiers for the 517 // purpose of this check, because other qualifiers (address spaces, 518 // Objective-C GC, etc.) are part of the type's identity. 519 QualType PrevUnwrappedSrcType = UnwrappedSrcType; 520 QualType PrevUnwrappedDestType = UnwrappedDestType; 521 while (UnwrapDissimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) { 522 // Determine the relevant qualifiers at this level. 523 Qualifiers SrcQuals, DestQuals; 524 Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals); 525 Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals); 526 527 Qualifiers RetainedSrcQuals, RetainedDestQuals; 528 if (CheckCVR) { 529 RetainedSrcQuals.setCVRQualifiers(SrcQuals.getCVRQualifiers()); 530 RetainedDestQuals.setCVRQualifiers(DestQuals.getCVRQualifiers()); 531 532 if (RetainedSrcQuals != RetainedDestQuals && TheOffendingSrcType && 533 TheOffendingDestType && CastAwayQualifiers) { 534 *TheOffendingSrcType = PrevUnwrappedSrcType; 535 *TheOffendingDestType = PrevUnwrappedDestType; 536 *CastAwayQualifiers = RetainedSrcQuals - RetainedDestQuals; 537 } 538 } 539 540 if (CheckObjCLifetime && 541 !DestQuals.compatiblyIncludesObjCLifetime(SrcQuals)) 542 return true; 543 544 cv1.push_back(RetainedSrcQuals); 545 cv2.push_back(RetainedDestQuals); 546 547 PrevUnwrappedSrcType = UnwrappedSrcType; 548 PrevUnwrappedDestType = UnwrappedDestType; 549 } 550 if (cv1.empty()) 551 return false; 552 553 // Construct void pointers with those qualifiers (in reverse order of 554 // unwrapping, of course). 555 QualType SrcConstruct = Self.Context.VoidTy; 556 QualType DestConstruct = Self.Context.VoidTy; 557 ASTContext &Context = Self.Context; 558 for (SmallVectorImpl<Qualifiers>::reverse_iterator i1 = cv1.rbegin(), 559 i2 = cv2.rbegin(); 560 i1 != cv1.rend(); ++i1, ++i2) { 561 SrcConstruct 562 = Context.getPointerType(Context.getQualifiedType(SrcConstruct, *i1)); 563 DestConstruct 564 = Context.getPointerType(Context.getQualifiedType(DestConstruct, *i2)); 565 } 566 567 // Test if they're compatible. 568 bool ObjCLifetimeConversion; 569 return SrcConstruct != DestConstruct && 570 !Self.IsQualificationConversion(SrcConstruct, DestConstruct, false, 571 ObjCLifetimeConversion); 572} 573 574/// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid. 575/// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime- 576/// checked downcasts in class hierarchies. 577void CastOperation::CheckDynamicCast() { 578 if (ValueKind == VK_RValue) 579 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 580 else if (isPlaceholder()) 581 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get()); 582 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 583 return; 584 585 QualType OrigSrcType = SrcExpr.get()->getType(); 586 QualType DestType = Self.Context.getCanonicalType(this->DestType); 587 588 // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type, 589 // or "pointer to cv void". 590 591 QualType DestPointee; 592 const PointerType *DestPointer = DestType->getAs<PointerType>(); 593 const ReferenceType *DestReference = nullptr; 594 if (DestPointer) { 595 DestPointee = DestPointer->getPointeeType(); 596 } else if ((DestReference = DestType->getAs<ReferenceType>())) { 597 DestPointee = DestReference->getPointeeType(); 598 } else { 599 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr) 600 << this->DestType << DestRange; 601 SrcExpr = ExprError(); 602 return; 603 } 604 605 const RecordType *DestRecord = DestPointee->getAs<RecordType>(); 606 if (DestPointee->isVoidType()) { 607 assert(DestPointer && "Reference to void is not possible"); 608 } else if (DestRecord) { 609 if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee, 610 diag::err_bad_dynamic_cast_incomplete, 611 DestRange)) { 612 SrcExpr = ExprError(); 613 return; 614 } 615 } else { 616 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 617 << DestPointee.getUnqualifiedType() << DestRange; 618 SrcExpr = ExprError(); 619 return; 620 } 621 622 // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to 623 // complete class type, [...]. If T is an lvalue reference type, v shall be 624 // an lvalue of a complete class type, [...]. If T is an rvalue reference 625 // type, v shall be an expression having a complete class type, [...] 626 QualType SrcType = Self.Context.getCanonicalType(OrigSrcType); 627 QualType SrcPointee; 628 if (DestPointer) { 629 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 630 SrcPointee = SrcPointer->getPointeeType(); 631 } else { 632 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr) 633 << OrigSrcType << SrcExpr.get()->getSourceRange(); 634 SrcExpr = ExprError(); 635 return; 636 } 637 } else if (DestReference->isLValueReferenceType()) { 638 if (!SrcExpr.get()->isLValue()) { 639 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue) 640 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 641 } 642 SrcPointee = SrcType; 643 } else { 644 // If we're dynamic_casting from a prvalue to an rvalue reference, we need 645 // to materialize the prvalue before we bind the reference to it. 646 if (SrcExpr.get()->isRValue()) 647 SrcExpr = Self.CreateMaterializeTemporaryExpr( 648 SrcType, SrcExpr.get(), /*IsLValueReference*/ false); 649 SrcPointee = SrcType; 650 } 651 652 const RecordType *SrcRecord = SrcPointee->getAs<RecordType>(); 653 if (SrcRecord) { 654 if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee, 655 diag::err_bad_dynamic_cast_incomplete, 656 SrcExpr.get())) { 657 SrcExpr = ExprError(); 658 return; 659 } 660 } else { 661 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 662 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 663 SrcExpr = ExprError(); 664 return; 665 } 666 667 assert((DestPointer || DestReference) && 668 "Bad destination non-ptr/ref slipped through."); 669 assert((DestRecord || DestPointee->isVoidType()) && 670 "Bad destination pointee slipped through."); 671 assert(SrcRecord && "Bad source pointee slipped through."); 672 673 // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness. 674 if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) { 675 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away) 676 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 677 SrcExpr = ExprError(); 678 return; 679 } 680 681 // C++ 5.2.7p3: If the type of v is the same as the required result type, 682 // [except for cv]. 683 if (DestRecord == SrcRecord) { 684 Kind = CK_NoOp; 685 return; 686 } 687 688 // C++ 5.2.7p5 689 // Upcasts are resolved statically. 690 if (DestRecord && 691 Self.IsDerivedFrom(OpRange.getBegin(), SrcPointee, DestPointee)) { 692 if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee, 693 OpRange.getBegin(), OpRange, 694 &BasePath)) { 695 SrcExpr = ExprError(); 696 return; 697 } 698 699 Kind = CK_DerivedToBase; 700 return; 701 } 702 703 // C++ 5.2.7p6: Otherwise, v shall be [polymorphic]. 704 const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition(); 705 assert(SrcDecl && "Definition missing"); 706 if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) { 707 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic) 708 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 709 SrcExpr = ExprError(); 710 } 711 712 // dynamic_cast is not available with -fno-rtti. 713 // As an exception, dynamic_cast to void* is available because it doesn't 714 // use RTTI. 715 if (!Self.getLangOpts().RTTI && !DestPointee->isVoidType()) { 716 Self.Diag(OpRange.getBegin(), diag::err_no_dynamic_cast_with_fno_rtti); 717 SrcExpr = ExprError(); 718 return; 719 } 720 721 // Done. Everything else is run-time checks. 722 Kind = CK_Dynamic; 723} 724 725/// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid. 726/// Refer to C++ 5.2.11 for details. const_cast is typically used in code 727/// like this: 728/// const char *str = "literal"; 729/// legacy_function(const_cast\<char*\>(str)); 730void CastOperation::CheckConstCast() { 731 if (ValueKind == VK_RValue) 732 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 733 else if (isPlaceholder()) 734 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get()); 735 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 736 return; 737 738 unsigned msg = diag::err_bad_cxx_cast_generic; 739 if (TryConstCast(Self, SrcExpr, DestType, /*CStyle*/false, msg) != TC_Success 740 && msg != 0) { 741 Self.Diag(OpRange.getBegin(), msg) << CT_Const 742 << SrcExpr.get()->getType() << DestType << OpRange; 743 SrcExpr = ExprError(); 744 } 745} 746 747/// Check that a reinterpret_cast\<DestType\>(SrcExpr) is not used as upcast 748/// or downcast between respective pointers or references. 749static void DiagnoseReinterpretUpDownCast(Sema &Self, const Expr *SrcExpr, 750 QualType DestType, 751 SourceRange OpRange) { 752 QualType SrcType = SrcExpr->getType(); 753 // When casting from pointer or reference, get pointee type; use original 754 // type otherwise. 755 const CXXRecordDecl *SrcPointeeRD = SrcType->getPointeeCXXRecordDecl(); 756 const CXXRecordDecl *SrcRD = 757 SrcPointeeRD ? SrcPointeeRD : SrcType->getAsCXXRecordDecl(); 758 759 // Examining subobjects for records is only possible if the complete and 760 // valid definition is available. Also, template instantiation is not 761 // allowed here. 762 if (!SrcRD || !SrcRD->isCompleteDefinition() || SrcRD->isInvalidDecl()) 763 return; 764 765 const CXXRecordDecl *DestRD = DestType->getPointeeCXXRecordDecl(); 766 767 if (!DestRD || !DestRD->isCompleteDefinition() || DestRD->isInvalidDecl()) 768 return; 769 770 enum { 771 ReinterpretUpcast, 772 ReinterpretDowncast 773 } ReinterpretKind; 774 775 CXXBasePaths BasePaths; 776 777 if (SrcRD->isDerivedFrom(DestRD, BasePaths)) 778 ReinterpretKind = ReinterpretUpcast; 779 else if (DestRD->isDerivedFrom(SrcRD, BasePaths)) 780 ReinterpretKind = ReinterpretDowncast; 781 else 782 return; 783 784 bool VirtualBase = true; 785 bool NonZeroOffset = false; 786 for (CXXBasePaths::const_paths_iterator I = BasePaths.begin(), 787 E = BasePaths.end(); 788 I != E; ++I) { 789 const CXXBasePath &Path = *I; 790 CharUnits Offset = CharUnits::Zero(); 791 bool IsVirtual = false; 792 for (CXXBasePath::const_iterator IElem = Path.begin(), EElem = Path.end(); 793 IElem != EElem; ++IElem) { 794 IsVirtual = IElem->Base->isVirtual(); 795 if (IsVirtual) 796 break; 797 const CXXRecordDecl *BaseRD = IElem->Base->getType()->getAsCXXRecordDecl(); 798 assert(BaseRD && "Base type should be a valid unqualified class type"); 799 // Don't check if any base has invalid declaration or has no definition 800 // since it has no layout info. 801 const CXXRecordDecl *Class = IElem->Class, 802 *ClassDefinition = Class->getDefinition(); 803 if (Class->isInvalidDecl() || !ClassDefinition || 804 !ClassDefinition->isCompleteDefinition()) 805 return; 806 807 const ASTRecordLayout &DerivedLayout = 808 Self.Context.getASTRecordLayout(Class); 809 Offset += DerivedLayout.getBaseClassOffset(BaseRD); 810 } 811 if (!IsVirtual) { 812 // Don't warn if any path is a non-virtually derived base at offset zero. 813 if (Offset.isZero()) 814 return; 815 // Offset makes sense only for non-virtual bases. 816 else 817 NonZeroOffset = true; 818 } 819 VirtualBase = VirtualBase && IsVirtual; 820 } 821 822 (void) NonZeroOffset; // Silence set but not used warning. 823 assert((VirtualBase || NonZeroOffset) && 824 "Should have returned if has non-virtual base with zero offset"); 825 826 QualType BaseType = 827 ReinterpretKind == ReinterpretUpcast? DestType : SrcType; 828 QualType DerivedType = 829 ReinterpretKind == ReinterpretUpcast? SrcType : DestType; 830 831 SourceLocation BeginLoc = OpRange.getBegin(); 832 Self.Diag(BeginLoc, diag::warn_reinterpret_different_from_static) 833 << DerivedType << BaseType << !VirtualBase << int(ReinterpretKind) 834 << OpRange; 835 Self.Diag(BeginLoc, diag::note_reinterpret_updowncast_use_static) 836 << int(ReinterpretKind) 837 << FixItHint::CreateReplacement(BeginLoc, "static_cast"); 838} 839 840/// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is 841/// valid. 842/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code 843/// like this: 844/// char *bytes = reinterpret_cast\<char*\>(int_ptr); 845void CastOperation::CheckReinterpretCast() { 846 if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload)) 847 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 848 else 849 checkNonOverloadPlaceholders(); 850 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 851 return; 852 853 unsigned msg = diag::err_bad_cxx_cast_generic; 854 TryCastResult tcr = 855 TryReinterpretCast(Self, SrcExpr, DestType, 856 /*CStyle*/false, OpRange, msg, Kind); 857 if (tcr != TC_Success && msg != 0) 858 { 859 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 860 return; 861 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 862 //FIXME: &f<int>; is overloaded and resolvable 863 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload) 864 << OverloadExpr::find(SrcExpr.get()).Expression->getName() 865 << DestType << OpRange; 866 Self.NoteAllOverloadCandidates(SrcExpr.get()); 867 868 } else { 869 diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(), 870 DestType, /*listInitialization=*/false); 871 } 872 SrcExpr = ExprError(); 873 } else if (tcr == TC_Success) { 874 if (Self.getLangOpts().ObjCAutoRefCount) 875 checkObjCARCConversion(Sema::CCK_OtherCast); 876 DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange); 877 } 878} 879 880 881/// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid. 882/// Refer to C++ 5.2.9 for details. Static casts are mostly used for making 883/// implicit conversions explicit and getting rid of data loss warnings. 884void CastOperation::CheckStaticCast() { 885 if (isPlaceholder()) { 886 checkNonOverloadPlaceholders(); 887 if (SrcExpr.isInvalid()) 888 return; 889 } 890 891 // This test is outside everything else because it's the only case where 892 // a non-lvalue-reference target type does not lead to decay. 893 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 894 if (DestType->isVoidType()) { 895 Kind = CK_ToVoid; 896 897 if (claimPlaceholder(BuiltinType::Overload)) { 898 Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr, 899 false, // Decay Function to ptr 900 true, // Complain 901 OpRange, DestType, diag::err_bad_static_cast_overload); 902 if (SrcExpr.isInvalid()) 903 return; 904 } 905 906 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get()); 907 return; 908 } 909 910 if (ValueKind == VK_RValue && !DestType->isRecordType() && 911 !isPlaceholder(BuiltinType::Overload)) { 912 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 913 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 914 return; 915 } 916 917 unsigned msg = diag::err_bad_cxx_cast_generic; 918 TryCastResult tcr 919 = TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_OtherCast, OpRange, msg, 920 Kind, BasePath, /*ListInitialization=*/false); 921 if (tcr != TC_Success && msg != 0) { 922 if (SrcExpr.isInvalid()) 923 return; 924 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 925 OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression; 926 Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload) 927 << oe->getName() << DestType << OpRange 928 << oe->getQualifierLoc().getSourceRange(); 929 Self.NoteAllOverloadCandidates(SrcExpr.get()); 930 } else { 931 diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType, 932 /*listInitialization=*/false); 933 } 934 SrcExpr = ExprError(); 935 } else if (tcr == TC_Success) { 936 if (Kind == CK_BitCast) 937 checkCastAlign(); 938 if (Self.getLangOpts().ObjCAutoRefCount) 939 checkObjCARCConversion(Sema::CCK_OtherCast); 940 } else if (Kind == CK_BitCast) { 941 checkCastAlign(); 942 } 943} 944 945/// TryStaticCast - Check if a static cast can be performed, and do so if 946/// possible. If @p CStyle, ignore access restrictions on hierarchy casting 947/// and casting away constness. 948static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, 949 QualType DestType, 950 Sema::CheckedConversionKind CCK, 951 SourceRange OpRange, unsigned &msg, 952 CastKind &Kind, CXXCastPath &BasePath, 953 bool ListInitialization) { 954 // Determine whether we have the semantics of a C-style cast. 955 bool CStyle 956 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 957 958 // The order the tests is not entirely arbitrary. There is one conversion 959 // that can be handled in two different ways. Given: 960 // struct A {}; 961 // struct B : public A { 962 // B(); B(const A&); 963 // }; 964 // const A &a = B(); 965 // the cast static_cast<const B&>(a) could be seen as either a static 966 // reference downcast, or an explicit invocation of the user-defined 967 // conversion using B's conversion constructor. 968 // DR 427 specifies that the downcast is to be applied here. 969 970 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 971 // Done outside this function. 972 973 TryCastResult tcr; 974 975 // C++ 5.2.9p5, reference downcast. 976 // See the function for details. 977 // DR 427 specifies that this is to be applied before paragraph 2. 978 tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle, 979 OpRange, msg, Kind, BasePath); 980 if (tcr != TC_NotApplicable) 981 return tcr; 982 983 // C++11 [expr.static.cast]p3: 984 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2 985 // T2" if "cv2 T2" is reference-compatible with "cv1 T1". 986 tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind, 987 BasePath, msg); 988 if (tcr != TC_NotApplicable) 989 return tcr; 990 991 // C++ 5.2.9p2: An expression e can be explicitly converted to a type T 992 // [...] if the declaration "T t(e);" is well-formed, [...]. 993 tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg, 994 Kind, ListInitialization); 995 if (SrcExpr.isInvalid()) 996 return TC_Failed; 997 if (tcr != TC_NotApplicable) 998 return tcr; 999 1000 // C++ 5.2.9p6: May apply the reverse of any standard conversion, except 1001 // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean 1002 // conversions, subject to further restrictions. 1003 // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal 1004 // of qualification conversions impossible. 1005 // In the CStyle case, the earlier attempt to const_cast should have taken 1006 // care of reverse qualification conversions. 1007 1008 QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType()); 1009 1010 // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly 1011 // converted to an integral type. [...] A value of a scoped enumeration type 1012 // can also be explicitly converted to a floating-point type [...]. 1013 if (const EnumType *Enum = SrcType->getAs<EnumType>()) { 1014 if (Enum->getDecl()->isScoped()) { 1015 if (DestType->isBooleanType()) { 1016 Kind = CK_IntegralToBoolean; 1017 return TC_Success; 1018 } else if (DestType->isIntegralType(Self.Context)) { 1019 Kind = CK_IntegralCast; 1020 return TC_Success; 1021 } else if (DestType->isRealFloatingType()) { 1022 Kind = CK_IntegralToFloating; 1023 return TC_Success; 1024 } 1025 } 1026 } 1027 1028 // Reverse integral promotion/conversion. All such conversions are themselves 1029 // again integral promotions or conversions and are thus already handled by 1030 // p2 (TryDirectInitialization above). 1031 // (Note: any data loss warnings should be suppressed.) 1032 // The exception is the reverse of enum->integer, i.e. integer->enum (and 1033 // enum->enum). See also C++ 5.2.9p7. 1034 // The same goes for reverse floating point promotion/conversion and 1035 // floating-integral conversions. Again, only floating->enum is relevant. 1036 if (DestType->isEnumeralType()) { 1037 if (SrcType->isIntegralOrEnumerationType()) { 1038 Kind = CK_IntegralCast; 1039 return TC_Success; 1040 } else if (SrcType->isRealFloatingType()) { 1041 Kind = CK_FloatingToIntegral; 1042 return TC_Success; 1043 } 1044 } 1045 1046 // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast. 1047 // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance. 1048 tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg, 1049 Kind, BasePath); 1050 if (tcr != TC_NotApplicable) 1051 return tcr; 1052 1053 // Reverse member pointer conversion. C++ 4.11 specifies member pointer 1054 // conversion. C++ 5.2.9p9 has additional information. 1055 // DR54's access restrictions apply here also. 1056 tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle, 1057 OpRange, msg, Kind, BasePath); 1058 if (tcr != TC_NotApplicable) 1059 return tcr; 1060 1061 // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to 1062 // void*. C++ 5.2.9p10 specifies additional restrictions, which really is 1063 // just the usual constness stuff. 1064 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 1065 QualType SrcPointee = SrcPointer->getPointeeType(); 1066 if (SrcPointee->isVoidType()) { 1067 if (const PointerType *DestPointer = DestType->getAs<PointerType>()) { 1068 QualType DestPointee = DestPointer->getPointeeType(); 1069 if (DestPointee->isIncompleteOrObjectType()) { 1070 // This is definitely the intended conversion, but it might fail due 1071 // to a qualifier violation. Note that we permit Objective-C lifetime 1072 // and GC qualifier mismatches here. 1073 if (!CStyle) { 1074 Qualifiers DestPointeeQuals = DestPointee.getQualifiers(); 1075 Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers(); 1076 DestPointeeQuals.removeObjCGCAttr(); 1077 DestPointeeQuals.removeObjCLifetime(); 1078 SrcPointeeQuals.removeObjCGCAttr(); 1079 SrcPointeeQuals.removeObjCLifetime(); 1080 if (DestPointeeQuals != SrcPointeeQuals && 1081 !DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) { 1082 msg = diag::err_bad_cxx_cast_qualifiers_away; 1083 return TC_Failed; 1084 } 1085 } 1086 Kind = CK_BitCast; 1087 return TC_Success; 1088 } 1089 1090 // Microsoft permits static_cast from 'pointer-to-void' to 1091 // 'pointer-to-function'. 1092 if (!CStyle && Self.getLangOpts().MSVCCompat && 1093 DestPointee->isFunctionType()) { 1094 Self.Diag(OpRange.getBegin(), diag::ext_ms_cast_fn_obj) << OpRange; 1095 Kind = CK_BitCast; 1096 return TC_Success; 1097 } 1098 } 1099 else if (DestType->isObjCObjectPointerType()) { 1100 // allow both c-style cast and static_cast of objective-c pointers as 1101 // they are pervasive. 1102 Kind = CK_CPointerToObjCPointerCast; 1103 return TC_Success; 1104 } 1105 else if (CStyle && DestType->isBlockPointerType()) { 1106 // allow c-style cast of void * to block pointers. 1107 Kind = CK_AnyPointerToBlockPointerCast; 1108 return TC_Success; 1109 } 1110 } 1111 } 1112 // Allow arbitray objective-c pointer conversion with static casts. 1113 if (SrcType->isObjCObjectPointerType() && 1114 DestType->isObjCObjectPointerType()) { 1115 Kind = CK_BitCast; 1116 return TC_Success; 1117 } 1118 // Allow ns-pointer to cf-pointer conversion in either direction 1119 // with static casts. 1120 if (!CStyle && 1121 Self.CheckTollFreeBridgeStaticCast(DestType, SrcExpr.get(), Kind)) 1122 return TC_Success; 1123 1124 // See if it looks like the user is trying to convert between 1125 // related record types, and select a better diagnostic if so. 1126 if (auto SrcPointer = SrcType->getAs<PointerType>()) 1127 if (auto DestPointer = DestType->getAs<PointerType>()) 1128 if (SrcPointer->getPointeeType()->getAs<RecordType>() && 1129 DestPointer->getPointeeType()->getAs<RecordType>()) 1130 msg = diag::err_bad_cxx_cast_unrelated_class; 1131 1132 // We tried everything. Everything! Nothing works! :-( 1133 return TC_NotApplicable; 1134} 1135 1136/// Tests whether a conversion according to N2844 is valid. 1137TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, 1138 QualType DestType, bool CStyle, 1139 CastKind &Kind, CXXCastPath &BasePath, 1140 unsigned &msg) { 1141 // C++11 [expr.static.cast]p3: 1142 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to 1143 // cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1". 1144 const RValueReferenceType *R = DestType->getAs<RValueReferenceType>(); 1145 if (!R) 1146 return TC_NotApplicable; 1147 1148 if (!SrcExpr->isGLValue()) 1149 return TC_NotApplicable; 1150 1151 // Because we try the reference downcast before this function, from now on 1152 // this is the only cast possibility, so we issue an error if we fail now. 1153 // FIXME: Should allow casting away constness if CStyle. 1154 bool DerivedToBase; 1155 bool ObjCConversion; 1156 bool ObjCLifetimeConversion; 1157 QualType FromType = SrcExpr->getType(); 1158 QualType ToType = R->getPointeeType(); 1159 if (CStyle) { 1160 FromType = FromType.getUnqualifiedType(); 1161 ToType = ToType.getUnqualifiedType(); 1162 } 1163 1164 Sema::ReferenceCompareResult RefResult = Self.CompareReferenceRelationship( 1165 SrcExpr->getLocStart(), ToType, FromType, DerivedToBase, ObjCConversion, 1166 ObjCLifetimeConversion); 1167 if (RefResult != Sema::Ref_Compatible) { 1168 if (CStyle || RefResult == Sema::Ref_Incompatible) 1169 return TC_NotApplicable; 1170 // Diagnose types which are reference-related but not compatible here since 1171 // we can provide better diagnostics. In these cases forwarding to 1172 // [expr.static.cast]p4 should never result in a well-formed cast. 1173 msg = SrcExpr->isLValue() ? diag::err_bad_lvalue_to_rvalue_cast 1174 : diag::err_bad_rvalue_to_rvalue_cast; 1175 return TC_Failed; 1176 } 1177 1178 if (DerivedToBase) { 1179 Kind = CK_DerivedToBase; 1180 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1181 /*DetectVirtual=*/true); 1182 if (!Self.IsDerivedFrom(SrcExpr->getLocStart(), SrcExpr->getType(), 1183 R->getPointeeType(), Paths)) 1184 return TC_NotApplicable; 1185 1186 Self.BuildBasePathArray(Paths, BasePath); 1187 } else 1188 Kind = CK_NoOp; 1189 1190 return TC_Success; 1191} 1192 1193/// Tests whether a conversion according to C++ 5.2.9p5 is valid. 1194TryCastResult 1195TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType, 1196 bool CStyle, SourceRange OpRange, 1197 unsigned &msg, CastKind &Kind, 1198 CXXCastPath &BasePath) { 1199 // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be 1200 // cast to type "reference to cv2 D", where D is a class derived from B, 1201 // if a valid standard conversion from "pointer to D" to "pointer to B" 1202 // exists, cv2 >= cv1, and B is not a virtual base class of D. 1203 // In addition, DR54 clarifies that the base must be accessible in the 1204 // current context. Although the wording of DR54 only applies to the pointer 1205 // variant of this rule, the intent is clearly for it to apply to the this 1206 // conversion as well. 1207 1208 const ReferenceType *DestReference = DestType->getAs<ReferenceType>(); 1209 if (!DestReference) { 1210 return TC_NotApplicable; 1211 } 1212 bool RValueRef = DestReference->isRValueReferenceType(); 1213 if (!RValueRef && !SrcExpr->isLValue()) { 1214 // We know the left side is an lvalue reference, so we can suggest a reason. 1215 msg = diag::err_bad_cxx_cast_rvalue; 1216 return TC_NotApplicable; 1217 } 1218 1219 QualType DestPointee = DestReference->getPointeeType(); 1220 1221 // FIXME: If the source is a prvalue, we should issue a warning (because the 1222 // cast always has undefined behavior), and for AST consistency, we should 1223 // materialize a temporary. 1224 return TryStaticDowncast(Self, 1225 Self.Context.getCanonicalType(SrcExpr->getType()), 1226 Self.Context.getCanonicalType(DestPointee), CStyle, 1227 OpRange, SrcExpr->getType(), DestType, msg, Kind, 1228 BasePath); 1229} 1230 1231/// Tests whether a conversion according to C++ 5.2.9p8 is valid. 1232TryCastResult 1233TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType, 1234 bool CStyle, SourceRange OpRange, 1235 unsigned &msg, CastKind &Kind, 1236 CXXCastPath &BasePath) { 1237 // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class 1238 // type, can be converted to an rvalue of type "pointer to cv2 D", where D 1239 // is a class derived from B, if a valid standard conversion from "pointer 1240 // to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base 1241 // class of D. 1242 // In addition, DR54 clarifies that the base must be accessible in the 1243 // current context. 1244 1245 const PointerType *DestPointer = DestType->getAs<PointerType>(); 1246 if (!DestPointer) { 1247 return TC_NotApplicable; 1248 } 1249 1250 const PointerType *SrcPointer = SrcType->getAs<PointerType>(); 1251 if (!SrcPointer) { 1252 msg = diag::err_bad_static_cast_pointer_nonpointer; 1253 return TC_NotApplicable; 1254 } 1255 1256 return TryStaticDowncast(Self, 1257 Self.Context.getCanonicalType(SrcPointer->getPointeeType()), 1258 Self.Context.getCanonicalType(DestPointer->getPointeeType()), 1259 CStyle, OpRange, SrcType, DestType, msg, Kind, 1260 BasePath); 1261} 1262 1263/// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and 1264/// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to 1265/// DestType is possible and allowed. 1266TryCastResult 1267TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType, 1268 bool CStyle, SourceRange OpRange, QualType OrigSrcType, 1269 QualType OrigDestType, unsigned &msg, 1270 CastKind &Kind, CXXCastPath &BasePath) { 1271 // We can only work with complete types. But don't complain if it doesn't work 1272 if (!Self.isCompleteType(OpRange.getBegin(), SrcType) || 1273 !Self.isCompleteType(OpRange.getBegin(), DestType)) 1274 return TC_NotApplicable; 1275 1276 // Downcast can only happen in class hierarchies, so we need classes. 1277 if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) { 1278 return TC_NotApplicable; 1279 } 1280 1281 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1282 /*DetectVirtual=*/true); 1283 if (!Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths)) { 1284 return TC_NotApplicable; 1285 } 1286 1287 // Target type does derive from source type. Now we're serious. If an error 1288 // appears now, it's not ignored. 1289 // This may not be entirely in line with the standard. Take for example: 1290 // struct A {}; 1291 // struct B : virtual A { 1292 // B(A&); 1293 // }; 1294 // 1295 // void f() 1296 // { 1297 // (void)static_cast<const B&>(*((A*)0)); 1298 // } 1299 // As far as the standard is concerned, p5 does not apply (A is virtual), so 1300 // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid. 1301 // However, both GCC and Comeau reject this example, and accepting it would 1302 // mean more complex code if we're to preserve the nice error message. 1303 // FIXME: Being 100% compliant here would be nice to have. 1304 1305 // Must preserve cv, as always, unless we're in C-style mode. 1306 if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) { 1307 msg = diag::err_bad_cxx_cast_qualifiers_away; 1308 return TC_Failed; 1309 } 1310 1311 if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) { 1312 // This code is analoguous to that in CheckDerivedToBaseConversion, except 1313 // that it builds the paths in reverse order. 1314 // To sum up: record all paths to the base and build a nice string from 1315 // them. Use it to spice up the error message. 1316 if (!Paths.isRecordingPaths()) { 1317 Paths.clear(); 1318 Paths.setRecordingPaths(true); 1319 Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths); 1320 } 1321 std::string PathDisplayStr; 1322 std::set<unsigned> DisplayedPaths; 1323 for (clang::CXXBasePath &Path : Paths) { 1324 if (DisplayedPaths.insert(Path.back().SubobjectNumber).second) { 1325 // We haven't displayed a path to this particular base 1326 // class subobject yet. 1327 PathDisplayStr += "\n "; 1328 for (CXXBasePathElement &PE : llvm::reverse(Path)) 1329 PathDisplayStr += PE.Base->getType().getAsString() + " -> "; 1330 PathDisplayStr += QualType(DestType).getAsString(); 1331 } 1332 } 1333 1334 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast) 1335 << QualType(SrcType).getUnqualifiedType() 1336 << QualType(DestType).getUnqualifiedType() 1337 << PathDisplayStr << OpRange; 1338 msg = 0; 1339 return TC_Failed; 1340 } 1341 1342 if (Paths.getDetectedVirtual() != nullptr) { 1343 QualType VirtualBase(Paths.getDetectedVirtual(), 0); 1344 Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual) 1345 << OrigSrcType << OrigDestType << VirtualBase << OpRange; 1346 msg = 0; 1347 return TC_Failed; 1348 } 1349 1350 if (!CStyle) { 1351 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1352 SrcType, DestType, 1353 Paths.front(), 1354 diag::err_downcast_from_inaccessible_base)) { 1355 case Sema::AR_accessible: 1356 case Sema::AR_delayed: // be optimistic 1357 case Sema::AR_dependent: // be optimistic 1358 break; 1359 1360 case Sema::AR_inaccessible: 1361 msg = 0; 1362 return TC_Failed; 1363 } 1364 } 1365 1366 Self.BuildBasePathArray(Paths, BasePath); 1367 Kind = CK_BaseToDerived; 1368 return TC_Success; 1369} 1370 1371/// TryStaticMemberPointerUpcast - Tests whether a conversion according to 1372/// C++ 5.2.9p9 is valid: 1373/// 1374/// An rvalue of type "pointer to member of D of type cv1 T" can be 1375/// converted to an rvalue of type "pointer to member of B of type cv2 T", 1376/// where B is a base class of D [...]. 1377/// 1378TryCastResult 1379TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType, 1380 QualType DestType, bool CStyle, 1381 SourceRange OpRange, 1382 unsigned &msg, CastKind &Kind, 1383 CXXCastPath &BasePath) { 1384 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(); 1385 if (!DestMemPtr) 1386 return TC_NotApplicable; 1387 1388 bool WasOverloadedFunction = false; 1389 DeclAccessPair FoundOverload; 1390 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 1391 if (FunctionDecl *Fn 1392 = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false, 1393 FoundOverload)) { 1394 CXXMethodDecl *M = cast<CXXMethodDecl>(Fn); 1395 SrcType = Self.Context.getMemberPointerType(Fn->getType(), 1396 Self.Context.getTypeDeclType(M->getParent()).getTypePtr()); 1397 WasOverloadedFunction = true; 1398 } 1399 } 1400 1401 const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 1402 if (!SrcMemPtr) { 1403 msg = diag::err_bad_static_cast_member_pointer_nonmp; 1404 return TC_NotApplicable; 1405 } 1406 1407 // Lock down the inheritance model right now in MS ABI, whether or not the 1408 // pointee types are the same. 1409 if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) { 1410 (void)Self.isCompleteType(OpRange.getBegin(), SrcType); 1411 (void)Self.isCompleteType(OpRange.getBegin(), DestType); 1412 } 1413 1414 // T == T, modulo cv 1415 if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(), 1416 DestMemPtr->getPointeeType())) 1417 return TC_NotApplicable; 1418 1419 // B base of D 1420 QualType SrcClass(SrcMemPtr->getClass(), 0); 1421 QualType DestClass(DestMemPtr->getClass(), 0); 1422 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1423 /*DetectVirtual=*/true); 1424 if (!Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths)) 1425 return TC_NotApplicable; 1426 1427 // B is a base of D. But is it an allowed base? If not, it's a hard error. 1428 if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) { 1429 Paths.clear(); 1430 Paths.setRecordingPaths(true); 1431 bool StillOkay = 1432 Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths); 1433 assert(StillOkay); 1434 (void)StillOkay; 1435 std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths); 1436 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv) 1437 << 1 << SrcClass << DestClass << PathDisplayStr << OpRange; 1438 msg = 0; 1439 return TC_Failed; 1440 } 1441 1442 if (const RecordType *VBase = Paths.getDetectedVirtual()) { 1443 Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual) 1444 << SrcClass << DestClass << QualType(VBase, 0) << OpRange; 1445 msg = 0; 1446 return TC_Failed; 1447 } 1448 1449 if (!CStyle) { 1450 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1451 DestClass, SrcClass, 1452 Paths.front(), 1453 diag::err_upcast_to_inaccessible_base)) { 1454 case Sema::AR_accessible: 1455 case Sema::AR_delayed: 1456 case Sema::AR_dependent: 1457 // Optimistically assume that the delayed and dependent cases 1458 // will work out. 1459 break; 1460 1461 case Sema::AR_inaccessible: 1462 msg = 0; 1463 return TC_Failed; 1464 } 1465 } 1466 1467 if (WasOverloadedFunction) { 1468 // Resolve the address of the overloaded function again, this time 1469 // allowing complaints if something goes wrong. 1470 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 1471 DestType, 1472 true, 1473 FoundOverload); 1474 if (!Fn) { 1475 msg = 0; 1476 return TC_Failed; 1477 } 1478 1479 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn); 1480 if (!SrcExpr.isUsable()) { 1481 msg = 0; 1482 return TC_Failed; 1483 } 1484 } 1485 1486 Self.BuildBasePathArray(Paths, BasePath); 1487 Kind = CK_DerivedToBaseMemberPointer; 1488 return TC_Success; 1489} 1490 1491/// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2 1492/// is valid: 1493/// 1494/// An expression e can be explicitly converted to a type T using a 1495/// @c static_cast if the declaration "T t(e);" is well-formed [...]. 1496TryCastResult 1497TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, 1498 Sema::CheckedConversionKind CCK, 1499 SourceRange OpRange, unsigned &msg, 1500 CastKind &Kind, bool ListInitialization) { 1501 if (DestType->isRecordType()) { 1502 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 1503 diag::err_bad_dynamic_cast_incomplete) || 1504 Self.RequireNonAbstractType(OpRange.getBegin(), DestType, 1505 diag::err_allocation_of_abstract_type)) { 1506 msg = 0; 1507 return TC_Failed; 1508 } 1509 } 1510 1511 InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType); 1512 InitializationKind InitKind 1513 = (CCK == Sema::CCK_CStyleCast) 1514 ? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange, 1515 ListInitialization) 1516 : (CCK == Sema::CCK_FunctionalCast) 1517 ? InitializationKind::CreateFunctionalCast(OpRange, ListInitialization) 1518 : InitializationKind::CreateCast(OpRange); 1519 Expr *SrcExprRaw = SrcExpr.get(); 1520 // FIXME: Per DR242, we should check for an implicit conversion sequence 1521 // or for a constructor that could be invoked by direct-initialization 1522 // here, not for an initialization sequence. 1523 InitializationSequence InitSeq(Self, Entity, InitKind, SrcExprRaw); 1524 1525 // At this point of CheckStaticCast, if the destination is a reference, 1526 // or the expression is an overload expression this has to work. 1527 // There is no other way that works. 1528 // On the other hand, if we're checking a C-style cast, we've still got 1529 // the reinterpret_cast way. 1530 bool CStyle 1531 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 1532 if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType())) 1533 return TC_NotApplicable; 1534 1535 ExprResult Result = InitSeq.Perform(Self, Entity, InitKind, SrcExprRaw); 1536 if (Result.isInvalid()) { 1537 msg = 0; 1538 return TC_Failed; 1539 } 1540 1541 if (InitSeq.isConstructorInitialization()) 1542 Kind = CK_ConstructorConversion; 1543 else 1544 Kind = CK_NoOp; 1545 1546 SrcExpr = Result; 1547 return TC_Success; 1548} 1549 1550/// TryConstCast - See if a const_cast from source to destination is allowed, 1551/// and perform it if it is. 1552static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr, 1553 QualType DestType, bool CStyle, 1554 unsigned &msg) { 1555 DestType = Self.Context.getCanonicalType(DestType); 1556 QualType SrcType = SrcExpr.get()->getType(); 1557 bool NeedToMaterializeTemporary = false; 1558 1559 if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) { 1560 // C++11 5.2.11p4: 1561 // if a pointer to T1 can be explicitly converted to the type "pointer to 1562 // T2" using a const_cast, then the following conversions can also be 1563 // made: 1564 // -- an lvalue of type T1 can be explicitly converted to an lvalue of 1565 // type T2 using the cast const_cast<T2&>; 1566 // -- a glvalue of type T1 can be explicitly converted to an xvalue of 1567 // type T2 using the cast const_cast<T2&&>; and 1568 // -- if T1 is a class type, a prvalue of type T1 can be explicitly 1569 // converted to an xvalue of type T2 using the cast const_cast<T2&&>. 1570 1571 if (isa<LValueReferenceType>(DestTypeTmp) && !SrcExpr.get()->isLValue()) { 1572 // Cannot const_cast non-lvalue to lvalue reference type. But if this 1573 // is C-style, static_cast might find a way, so we simply suggest a 1574 // message and tell the parent to keep searching. 1575 msg = diag::err_bad_cxx_cast_rvalue; 1576 return TC_NotApplicable; 1577 } 1578 1579 if (isa<RValueReferenceType>(DestTypeTmp) && SrcExpr.get()->isRValue()) { 1580 if (!SrcType->isRecordType()) { 1581 // Cannot const_cast non-class prvalue to rvalue reference type. But if 1582 // this is C-style, static_cast can do this. 1583 msg = diag::err_bad_cxx_cast_rvalue; 1584 return TC_NotApplicable; 1585 } 1586 1587 // Materialize the class prvalue so that the const_cast can bind a 1588 // reference to it. 1589 NeedToMaterializeTemporary = true; 1590 } 1591 1592 // It's not completely clear under the standard whether we can 1593 // const_cast bit-field gl-values. Doing so would not be 1594 // intrinsically complicated, but for now, we say no for 1595 // consistency with other compilers and await the word of the 1596 // committee. 1597 if (SrcExpr.get()->refersToBitField()) { 1598 msg = diag::err_bad_cxx_cast_bitfield; 1599 return TC_NotApplicable; 1600 } 1601 1602 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 1603 SrcType = Self.Context.getPointerType(SrcType); 1604 } 1605 1606 // C++ 5.2.11p5: For a const_cast involving pointers to data members [...] 1607 // the rules for const_cast are the same as those used for pointers. 1608 1609 if (!DestType->isPointerType() && 1610 !DestType->isMemberPointerType() && 1611 !DestType->isObjCObjectPointerType()) { 1612 // Cannot cast to non-pointer, non-reference type. Note that, if DestType 1613 // was a reference type, we converted it to a pointer above. 1614 // The status of rvalue references isn't entirely clear, but it looks like 1615 // conversion to them is simply invalid. 1616 // C++ 5.2.11p3: For two pointer types [...] 1617 if (!CStyle) 1618 msg = diag::err_bad_const_cast_dest; 1619 return TC_NotApplicable; 1620 } 1621 if (DestType->isFunctionPointerType() || 1622 DestType->isMemberFunctionPointerType()) { 1623 // Cannot cast direct function pointers. 1624 // C++ 5.2.11p2: [...] where T is any object type or the void type [...] 1625 // T is the ultimate pointee of source and target type. 1626 if (!CStyle) 1627 msg = diag::err_bad_const_cast_dest; 1628 return TC_NotApplicable; 1629 } 1630 SrcType = Self.Context.getCanonicalType(SrcType); 1631 1632 // Unwrap the pointers. Ignore qualifiers. Terminate early if the types are 1633 // completely equal. 1634 // C++ 5.2.11p3 describes the core semantics of const_cast. All cv specifiers 1635 // in multi-level pointers may change, but the level count must be the same, 1636 // as must be the final pointee type. 1637 while (SrcType != DestType && 1638 Self.Context.UnwrapSimilarPointerTypes(SrcType, DestType)) { 1639 Qualifiers SrcQuals, DestQuals; 1640 SrcType = Self.Context.getUnqualifiedArrayType(SrcType, SrcQuals); 1641 DestType = Self.Context.getUnqualifiedArrayType(DestType, DestQuals); 1642 1643 // const_cast is permitted to strip cvr-qualifiers, only. Make sure that 1644 // the other qualifiers (e.g., address spaces) are identical. 1645 SrcQuals.removeCVRQualifiers(); 1646 DestQuals.removeCVRQualifiers(); 1647 if (SrcQuals != DestQuals) 1648 return TC_NotApplicable; 1649 } 1650 1651 // Since we're dealing in canonical types, the remainder must be the same. 1652 if (SrcType != DestType) 1653 return TC_NotApplicable; 1654 1655 if (NeedToMaterializeTemporary) 1656 // This is a const_cast from a class prvalue to an rvalue reference type. 1657 // Materialize a temporary to store the result of the conversion. 1658 SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcExpr.get()->getType(), 1659 SrcExpr.get(), 1660 /*IsLValueReference*/ false); 1661 1662 return TC_Success; 1663} 1664 1665// Checks for undefined behavior in reinterpret_cast. 1666// The cases that is checked for is: 1667// *reinterpret_cast<T*>(&a) 1668// reinterpret_cast<T&>(a) 1669// where accessing 'a' as type 'T' will result in undefined behavior. 1670void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType, 1671 bool IsDereference, 1672 SourceRange Range) { 1673 unsigned DiagID = IsDereference ? 1674 diag::warn_pointer_indirection_from_incompatible_type : 1675 diag::warn_undefined_reinterpret_cast; 1676 1677 if (Diags.isIgnored(DiagID, Range.getBegin())) 1678 return; 1679 1680 QualType SrcTy, DestTy; 1681 if (IsDereference) { 1682 if (!SrcType->getAs<PointerType>() || !DestType->getAs<PointerType>()) { 1683 return; 1684 } 1685 SrcTy = SrcType->getPointeeType(); 1686 DestTy = DestType->getPointeeType(); 1687 } else { 1688 if (!DestType->getAs<ReferenceType>()) { 1689 return; 1690 } 1691 SrcTy = SrcType; 1692 DestTy = DestType->getPointeeType(); 1693 } 1694 1695 // Cast is compatible if the types are the same. 1696 if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) { 1697 return; 1698 } 1699 // or one of the types is a char or void type 1700 if (DestTy->isAnyCharacterType() || DestTy->isVoidType() || 1701 SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) { 1702 return; 1703 } 1704 // or one of the types is a tag type. 1705 if (SrcTy->getAs<TagType>() || DestTy->getAs<TagType>()) { 1706 return; 1707 } 1708 1709 // FIXME: Scoped enums? 1710 if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) || 1711 (SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) { 1712 if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) { 1713 return; 1714 } 1715 } 1716 1717 Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range; 1718} 1719 1720static void DiagnoseCastOfObjCSEL(Sema &Self, const ExprResult &SrcExpr, 1721 QualType DestType) { 1722 QualType SrcType = SrcExpr.get()->getType(); 1723 if (Self.Context.hasSameType(SrcType, DestType)) 1724 return; 1725 if (const PointerType *SrcPtrTy = SrcType->getAs<PointerType>()) 1726 if (SrcPtrTy->isObjCSelType()) { 1727 QualType DT = DestType; 1728 if (isa<PointerType>(DestType)) 1729 DT = DestType->getPointeeType(); 1730 if (!DT.getUnqualifiedType()->isVoidType()) 1731 Self.Diag(SrcExpr.get()->getExprLoc(), 1732 diag::warn_cast_pointer_from_sel) 1733 << SrcType << DestType << SrcExpr.get()->getSourceRange(); 1734 } 1735} 1736 1737/// Diagnose casts that change the calling convention of a pointer to a function 1738/// defined in the current TU. 1739static void DiagnoseCallingConvCast(Sema &Self, const ExprResult &SrcExpr, 1740 QualType DstType, SourceRange OpRange) { 1741 // Check if this cast would change the calling convention of a function 1742 // pointer type. 1743 QualType SrcType = SrcExpr.get()->getType(); 1744 if (Self.Context.hasSameType(SrcType, DstType) || 1745 !SrcType->isFunctionPointerType() || !DstType->isFunctionPointerType()) 1746 return; 1747 const auto *SrcFTy = 1748 SrcType->castAs<PointerType>()->getPointeeType()->castAs<FunctionType>(); 1749 const auto *DstFTy = 1750 DstType->castAs<PointerType>()->getPointeeType()->castAs<FunctionType>(); 1751 CallingConv SrcCC = SrcFTy->getCallConv(); 1752 CallingConv DstCC = DstFTy->getCallConv(); 1753 if (SrcCC == DstCC) 1754 return; 1755 1756 // We have a calling convention cast. Check if the source is a pointer to a 1757 // known, specific function that has already been defined. 1758 Expr *Src = SrcExpr.get()->IgnoreParenImpCasts(); 1759 if (auto *UO = dyn_cast<UnaryOperator>(Src)) 1760 if (UO->getOpcode() == UO_AddrOf) 1761 Src = UO->getSubExpr()->IgnoreParenImpCasts(); 1762 auto *DRE = dyn_cast<DeclRefExpr>(Src); 1763 if (!DRE) 1764 return; 1765 auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl()); 1766 const FunctionDecl *Definition; 1767 if (!FD || !FD->hasBody(Definition)) 1768 return; 1769 1770 // Only warn if we are casting from the default convention to a non-default 1771 // convention. This can happen when the programmer forgot to apply the calling 1772 // convention to the function definition and then inserted this cast to 1773 // satisfy the type system. 1774 CallingConv DefaultCC = Self.getASTContext().getDefaultCallingConvention( 1775 FD->isVariadic(), FD->isCXXInstanceMember()); 1776 if (DstCC == DefaultCC || SrcCC != DefaultCC) 1777 return; 1778 1779 // Diagnose this cast, as it is probably bad. 1780 StringRef SrcCCName = FunctionType::getNameForCallConv(SrcCC); 1781 StringRef DstCCName = FunctionType::getNameForCallConv(DstCC); 1782 Self.Diag(OpRange.getBegin(), diag::warn_cast_calling_conv) 1783 << SrcCCName << DstCCName << OpRange; 1784 1785 // The checks above are cheaper than checking if the diagnostic is enabled. 1786 // However, it's worth checking if the warning is enabled before we construct 1787 // a fixit. 1788 if (Self.Diags.isIgnored(diag::warn_cast_calling_conv, OpRange.getBegin())) 1789 return; 1790 1791 // Try to suggest a fixit to change the calling convention of the function 1792 // whose address was taken. Try to use the latest macro for the convention. 1793 // For example, users probably want to write "WINAPI" instead of "__stdcall" 1794 // to match the Windows header declarations. 1795 SourceLocation NameLoc = Definition->getNameInfo().getLoc(); 1796 Preprocessor &PP = Self.getPreprocessor(); 1797 SmallVector<TokenValue, 6> AttrTokens; 1798 SmallString<64> CCAttrText; 1799 llvm::raw_svector_ostream OS(CCAttrText); 1800 if (Self.getLangOpts().MicrosoftExt) { 1801 // __stdcall or __vectorcall 1802 OS << "__" << DstCCName; 1803 IdentifierInfo *II = PP.getIdentifierInfo(OS.str()); 1804 AttrTokens.push_back(II->isKeyword(Self.getLangOpts()) 1805 ? TokenValue(II->getTokenID()) 1806 : TokenValue(II)); 1807 } else { 1808 // __attribute__((stdcall)) or __attribute__((vectorcall)) 1809 OS << "__attribute__((" << DstCCName << "))"; 1810 AttrTokens.push_back(tok::kw___attribute); 1811 AttrTokens.push_back(tok::l_paren); 1812 AttrTokens.push_back(tok::l_paren); 1813 IdentifierInfo *II = PP.getIdentifierInfo(DstCCName); 1814 AttrTokens.push_back(II->isKeyword(Self.getLangOpts()) 1815 ? TokenValue(II->getTokenID()) 1816 : TokenValue(II)); 1817 AttrTokens.push_back(tok::r_paren); 1818 AttrTokens.push_back(tok::r_paren); 1819 } 1820 StringRef AttrSpelling = PP.getLastMacroWithSpelling(NameLoc, AttrTokens); 1821 if (!AttrSpelling.empty()) 1822 CCAttrText = AttrSpelling; 1823 OS << ' '; 1824 Self.Diag(NameLoc, diag::note_change_calling_conv_fixit) 1825 << FD << DstCCName << FixItHint::CreateInsertion(NameLoc, CCAttrText); 1826} 1827 1828static void checkIntToPointerCast(bool CStyle, SourceLocation Loc, 1829 const Expr *SrcExpr, QualType DestType, 1830 Sema &Self) { 1831 QualType SrcType = SrcExpr->getType(); 1832 1833 // Not warning on reinterpret_cast, boolean, constant expressions, etc 1834 // are not explicit design choices, but consistent with GCC's behavior. 1835 // Feel free to modify them if you've reason/evidence for an alternative. 1836 if (CStyle && SrcType->isIntegralType(Self.Context) 1837 && !SrcType->isBooleanType() 1838 && !SrcType->isEnumeralType() 1839 && !SrcExpr->isIntegerConstantExpr(Self.Context) 1840 && Self.Context.getTypeSize(DestType) > 1841 Self.Context.getTypeSize(SrcType)) { 1842 // Separate between casts to void* and non-void* pointers. 1843 // Some APIs use (abuse) void* for something like a user context, 1844 // and often that value is an integer even if it isn't a pointer itself. 1845 // Having a separate warning flag allows users to control the warning 1846 // for their workflow. 1847 unsigned Diag = DestType->isVoidPointerType() ? 1848 diag::warn_int_to_void_pointer_cast 1849 : diag::warn_int_to_pointer_cast; 1850 Self.Diag(Loc, Diag) << SrcType << DestType; 1851 } 1852} 1853 1854static bool fixOverloadedReinterpretCastExpr(Sema &Self, QualType DestType, 1855 ExprResult &Result) { 1856 // We can only fix an overloaded reinterpret_cast if 1857 // - it is a template with explicit arguments that resolves to an lvalue 1858 // unambiguously, or 1859 // - it is the only function in an overload set that may have its address 1860 // taken. 1861 1862 Expr *E = Result.get(); 1863 // TODO: what if this fails because of DiagnoseUseOfDecl or something 1864 // like it? 1865 if (Self.ResolveAndFixSingleFunctionTemplateSpecialization( 1866 Result, 1867 Expr::getValueKindForType(DestType) == VK_RValue // Convert Fun to Ptr 1868 ) && 1869 Result.isUsable()) 1870 return true; 1871 1872 // No guarantees that ResolveAndFixSingleFunctionTemplateSpecialization 1873 // preserves Result. 1874 Result = E; 1875 if (!Self.resolveAndFixAddressOfOnlyViableOverloadCandidate(Result)) 1876 return false; 1877 return Result.isUsable(); 1878} 1879 1880static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr, 1881 QualType DestType, bool CStyle, 1882 SourceRange OpRange, 1883 unsigned &msg, 1884 CastKind &Kind) { 1885 bool IsLValueCast = false; 1886 1887 DestType = Self.Context.getCanonicalType(DestType); 1888 QualType SrcType = SrcExpr.get()->getType(); 1889 1890 // Is the source an overloaded name? (i.e. &foo) 1891 // If so, reinterpret_cast generally can not help us here (13.4, p1, bullet 5) 1892 if (SrcType == Self.Context.OverloadTy) { 1893 ExprResult FixedExpr = SrcExpr; 1894 if (!fixOverloadedReinterpretCastExpr(Self, DestType, FixedExpr)) 1895 return TC_NotApplicable; 1896 1897 assert(FixedExpr.isUsable() && "Invalid result fixing overloaded expr"); 1898 SrcExpr = FixedExpr; 1899 SrcType = SrcExpr.get()->getType(); 1900 } 1901 1902 if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) { 1903 if (!SrcExpr.get()->isGLValue()) { 1904 // Cannot cast non-glvalue to (lvalue or rvalue) reference type. See the 1905 // similar comment in const_cast. 1906 msg = diag::err_bad_cxx_cast_rvalue; 1907 return TC_NotApplicable; 1908 } 1909 1910 if (!CStyle) { 1911 Self.CheckCompatibleReinterpretCast(SrcType, DestType, 1912 /*isDereference=*/false, OpRange); 1913 } 1914 1915 // C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the 1916 // same effect as the conversion *reinterpret_cast<T*>(&x) with the 1917 // built-in & and * operators. 1918 1919 const char *inappropriate = nullptr; 1920 switch (SrcExpr.get()->getObjectKind()) { 1921 case OK_Ordinary: 1922 break; 1923 case OK_BitField: 1924 msg = diag::err_bad_cxx_cast_bitfield; 1925 return TC_NotApplicable; 1926 // FIXME: Use a specific diagnostic for the rest of these cases. 1927 case OK_VectorComponent: inappropriate = "vector element"; break; 1928 case OK_ObjCProperty: inappropriate = "property expression"; break; 1929 case OK_ObjCSubscript: inappropriate = "container subscripting expression"; 1930 break; 1931 } 1932 if (inappropriate) { 1933 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference) 1934 << inappropriate << DestType 1935 << OpRange << SrcExpr.get()->getSourceRange(); 1936 msg = 0; SrcExpr = ExprError(); 1937 return TC_NotApplicable; 1938 } 1939 1940 // This code does this transformation for the checked types. 1941 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 1942 SrcType = Self.Context.getPointerType(SrcType); 1943 1944 IsLValueCast = true; 1945 } 1946 1947 // Canonicalize source for comparison. 1948 SrcType = Self.Context.getCanonicalType(SrcType); 1949 1950 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(), 1951 *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 1952 if (DestMemPtr && SrcMemPtr) { 1953 // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1" 1954 // can be explicitly converted to an rvalue of type "pointer to member 1955 // of Y of type T2" if T1 and T2 are both function types or both object 1956 // types. 1957 if (DestMemPtr->isMemberFunctionPointer() != 1958 SrcMemPtr->isMemberFunctionPointer()) 1959 return TC_NotApplicable; 1960 1961 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away 1962 // constness. 1963 // A reinterpret_cast followed by a const_cast can, though, so in C-style, 1964 // we accept it. 1965 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, 1966 /*CheckObjCLifetime=*/CStyle)) { 1967 msg = diag::err_bad_cxx_cast_qualifiers_away; 1968 return TC_Failed; 1969 } 1970 1971 if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) { 1972 // We need to determine the inheritance model that the class will use if 1973 // haven't yet. 1974 (void)Self.isCompleteType(OpRange.getBegin(), SrcType); 1975 (void)Self.isCompleteType(OpRange.getBegin(), DestType); 1976 } 1977 1978 // Don't allow casting between member pointers of different sizes. 1979 if (Self.Context.getTypeSize(DestMemPtr) != 1980 Self.Context.getTypeSize(SrcMemPtr)) { 1981 msg = diag::err_bad_cxx_cast_member_pointer_size; 1982 return TC_Failed; 1983 } 1984 1985 // A valid member pointer cast. 1986 assert(!IsLValueCast); 1987 Kind = CK_ReinterpretMemberPointer; 1988 return TC_Success; 1989 } 1990 1991 // See below for the enumeral issue. 1992 if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) { 1993 // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral 1994 // type large enough to hold it. A value of std::nullptr_t can be 1995 // converted to an integral type; the conversion has the same meaning 1996 // and validity as a conversion of (void*)0 to the integral type. 1997 if (Self.Context.getTypeSize(SrcType) > 1998 Self.Context.getTypeSize(DestType)) { 1999 msg = diag::err_bad_reinterpret_cast_small_int; 2000 return TC_Failed; 2001 } 2002 Kind = CK_PointerToIntegral; 2003 return TC_Success; 2004 } 2005 2006 // Allow reinterpret_casts between vectors of the same size and 2007 // between vectors and integers of the same size. 2008 bool destIsVector = DestType->isVectorType(); 2009 bool srcIsVector = SrcType->isVectorType(); 2010 if (srcIsVector || destIsVector) { 2011 // The non-vector type, if any, must have integral type. This is 2012 // the same rule that C vector casts use; note, however, that enum 2013 // types are not integral in C++. 2014 if ((!destIsVector && !DestType->isIntegralType(Self.Context)) || 2015 (!srcIsVector && !SrcType->isIntegralType(Self.Context))) 2016 return TC_NotApplicable; 2017 2018 // The size we want to consider is eltCount * eltSize. 2019 // That's exactly what the lax-conversion rules will check. 2020 if (Self.areLaxCompatibleVectorTypes(SrcType, DestType)) { 2021 Kind = CK_BitCast; 2022 return TC_Success; 2023 } 2024 2025 // Otherwise, pick a reasonable diagnostic. 2026 if (!destIsVector) 2027 msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size; 2028 else if (!srcIsVector) 2029 msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size; 2030 else 2031 msg = diag::err_bad_cxx_cast_vector_to_vector_different_size; 2032 2033 return TC_Failed; 2034 } 2035 2036 if (SrcType == DestType) { 2037 // C++ 5.2.10p2 has a note that mentions that, subject to all other 2038 // restrictions, a cast to the same type is allowed so long as it does not 2039 // cast away constness. In C++98, the intent was not entirely clear here, 2040 // since all other paragraphs explicitly forbid casts to the same type. 2041 // C++11 clarifies this case with p2. 2042 // 2043 // The only allowed types are: integral, enumeration, pointer, or 2044 // pointer-to-member types. We also won't restrict Obj-C pointers either. 2045 Kind = CK_NoOp; 2046 TryCastResult Result = TC_NotApplicable; 2047 if (SrcType->isIntegralOrEnumerationType() || 2048 SrcType->isAnyPointerType() || 2049 SrcType->isMemberPointerType() || 2050 SrcType->isBlockPointerType()) { 2051 Result = TC_Success; 2052 } 2053 return Result; 2054 } 2055 2056 bool destIsPtr = DestType->isAnyPointerType() || 2057 DestType->isBlockPointerType(); 2058 bool srcIsPtr = SrcType->isAnyPointerType() || 2059 SrcType->isBlockPointerType(); 2060 if (!destIsPtr && !srcIsPtr) { 2061 // Except for std::nullptr_t->integer and lvalue->reference, which are 2062 // handled above, at least one of the two arguments must be a pointer. 2063 return TC_NotApplicable; 2064 } 2065 2066 if (DestType->isIntegralType(Self.Context)) { 2067 assert(srcIsPtr && "One type must be a pointer"); 2068 // C++ 5.2.10p4: A pointer can be explicitly converted to any integral 2069 // type large enough to hold it; except in Microsoft mode, where the 2070 // integral type size doesn't matter (except we don't allow bool). 2071 bool MicrosoftException = Self.getLangOpts().MicrosoftExt && 2072 !DestType->isBooleanType(); 2073 if ((Self.Context.getTypeSize(SrcType) > 2074 Self.Context.getTypeSize(DestType)) && 2075 !MicrosoftException) { 2076 msg = diag::err_bad_reinterpret_cast_small_int; 2077 return TC_Failed; 2078 } 2079 Kind = CK_PointerToIntegral; 2080 return TC_Success; 2081 } 2082 2083 if (SrcType->isIntegralOrEnumerationType()) { 2084 assert(destIsPtr && "One type must be a pointer"); 2085 checkIntToPointerCast(CStyle, OpRange.getBegin(), SrcExpr.get(), DestType, 2086 Self); 2087 // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly 2088 // converted to a pointer. 2089 // C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not 2090 // necessarily converted to a null pointer value.] 2091 Kind = CK_IntegralToPointer; 2092 return TC_Success; 2093 } 2094 2095 if (!destIsPtr || !srcIsPtr) { 2096 // With the valid non-pointer conversions out of the way, we can be even 2097 // more stringent. 2098 return TC_NotApplicable; 2099 } 2100 2101 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness. 2102 // The C-style cast operator can. 2103 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, 2104 /*CheckObjCLifetime=*/CStyle)) { 2105 msg = diag::err_bad_cxx_cast_qualifiers_away; 2106 return TC_Failed; 2107 } 2108 2109 // Cannot convert between block pointers and Objective-C object pointers. 2110 if ((SrcType->isBlockPointerType() && DestType->isObjCObjectPointerType()) || 2111 (DestType->isBlockPointerType() && SrcType->isObjCObjectPointerType())) 2112 return TC_NotApplicable; 2113 2114 if (IsLValueCast) { 2115 Kind = CK_LValueBitCast; 2116 } else if (DestType->isObjCObjectPointerType()) { 2117 Kind = Self.PrepareCastToObjCObjectPointer(SrcExpr); 2118 } else if (DestType->isBlockPointerType()) { 2119 if (!SrcType->isBlockPointerType()) { 2120 Kind = CK_AnyPointerToBlockPointerCast; 2121 } else { 2122 Kind = CK_BitCast; 2123 } 2124 } else { 2125 Kind = CK_BitCast; 2126 } 2127 2128 // Any pointer can be cast to an Objective-C pointer type with a C-style 2129 // cast. 2130 if (CStyle && DestType->isObjCObjectPointerType()) { 2131 return TC_Success; 2132 } 2133 if (CStyle) 2134 DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType); 2135 2136 DiagnoseCallingConvCast(Self, SrcExpr, DestType, OpRange); 2137 2138 // Not casting away constness, so the only remaining check is for compatible 2139 // pointer categories. 2140 2141 if (SrcType->isFunctionPointerType()) { 2142 if (DestType->isFunctionPointerType()) { 2143 // C++ 5.2.10p6: A pointer to a function can be explicitly converted to 2144 // a pointer to a function of a different type. 2145 return TC_Success; 2146 } 2147 2148 // C++0x 5.2.10p8: Converting a pointer to a function into a pointer to 2149 // an object type or vice versa is conditionally-supported. 2150 // Compilers support it in C++03 too, though, because it's necessary for 2151 // casting the return value of dlsym() and GetProcAddress(). 2152 // FIXME: Conditionally-supported behavior should be configurable in the 2153 // TargetInfo or similar. 2154 Self.Diag(OpRange.getBegin(), 2155 Self.getLangOpts().CPlusPlus11 ? 2156 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj) 2157 << OpRange; 2158 return TC_Success; 2159 } 2160 2161 if (DestType->isFunctionPointerType()) { 2162 // See above. 2163 Self.Diag(OpRange.getBegin(), 2164 Self.getLangOpts().CPlusPlus11 ? 2165 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj) 2166 << OpRange; 2167 return TC_Success; 2168 } 2169 2170 // C++ 5.2.10p7: A pointer to an object can be explicitly converted to 2171 // a pointer to an object of different type. 2172 // Void pointers are not specified, but supported by every compiler out there. 2173 // So we finish by allowing everything that remains - it's got to be two 2174 // object pointers. 2175 return TC_Success; 2176} 2177 2178void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle, 2179 bool ListInitialization) { 2180 // Handle placeholders. 2181 if (isPlaceholder()) { 2182 // C-style casts can resolve __unknown_any types. 2183 if (claimPlaceholder(BuiltinType::UnknownAny)) { 2184 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 2185 SrcExpr.get(), Kind, 2186 ValueKind, BasePath); 2187 return; 2188 } 2189 2190 checkNonOverloadPlaceholders(); 2191 if (SrcExpr.isInvalid()) 2192 return; 2193 } 2194 2195 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 2196 // This test is outside everything else because it's the only case where 2197 // a non-lvalue-reference target type does not lead to decay. 2198 if (DestType->isVoidType()) { 2199 Kind = CK_ToVoid; 2200 2201 if (claimPlaceholder(BuiltinType::Overload)) { 2202 Self.ResolveAndFixSingleFunctionTemplateSpecialization( 2203 SrcExpr, /* Decay Function to ptr */ false, 2204 /* Complain */ true, DestRange, DestType, 2205 diag::err_bad_cstyle_cast_overload); 2206 if (SrcExpr.isInvalid()) 2207 return; 2208 } 2209 2210 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get()); 2211 return; 2212 } 2213 2214 // If the type is dependent, we won't do any other semantic analysis now. 2215 if (DestType->isDependentType() || SrcExpr.get()->isTypeDependent() || 2216 SrcExpr.get()->isValueDependent()) { 2217 assert(Kind == CK_Dependent); 2218 return; 2219 } 2220 2221 if (ValueKind == VK_RValue && !DestType->isRecordType() && 2222 !isPlaceholder(BuiltinType::Overload)) { 2223 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 2224 if (SrcExpr.isInvalid()) 2225 return; 2226 } 2227 2228 // AltiVec vector initialization with a single literal. 2229 if (const VectorType *vecTy = DestType->getAs<VectorType>()) 2230 if (vecTy->getVectorKind() == VectorType::AltiVecVector 2231 && (SrcExpr.get()->getType()->isIntegerType() 2232 || SrcExpr.get()->getType()->isFloatingType())) { 2233 Kind = CK_VectorSplat; 2234 SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get()); 2235 return; 2236 } 2237 2238 // C++ [expr.cast]p5: The conversions performed by 2239 // - a const_cast, 2240 // - a static_cast, 2241 // - a static_cast followed by a const_cast, 2242 // - a reinterpret_cast, or 2243 // - a reinterpret_cast followed by a const_cast, 2244 // can be performed using the cast notation of explicit type conversion. 2245 // [...] If a conversion can be interpreted in more than one of the ways 2246 // listed above, the interpretation that appears first in the list is used, 2247 // even if a cast resulting from that interpretation is ill-formed. 2248 // In plain language, this means trying a const_cast ... 2249 unsigned msg = diag::err_bad_cxx_cast_generic; 2250 TryCastResult tcr = TryConstCast(Self, SrcExpr, DestType, 2251 /*CStyle*/true, msg); 2252 if (SrcExpr.isInvalid()) 2253 return; 2254 if (tcr == TC_Success) 2255 Kind = CK_NoOp; 2256 2257 Sema::CheckedConversionKind CCK 2258 = FunctionalStyle? Sema::CCK_FunctionalCast 2259 : Sema::CCK_CStyleCast; 2260 if (tcr == TC_NotApplicable) { 2261 // ... or if that is not possible, a static_cast, ignoring const, ... 2262 tcr = TryStaticCast(Self, SrcExpr, DestType, CCK, OpRange, 2263 msg, Kind, BasePath, ListInitialization); 2264 if (SrcExpr.isInvalid()) 2265 return; 2266 2267 if (tcr == TC_NotApplicable) { 2268 // ... and finally a reinterpret_cast, ignoring const. 2269 tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/true, 2270 OpRange, msg, Kind); 2271 if (SrcExpr.isInvalid()) 2272 return; 2273 } 2274 } 2275 2276 if (Self.getLangOpts().ObjCAutoRefCount && tcr == TC_Success) 2277 checkObjCARCConversion(CCK); 2278 2279 if (tcr != TC_Success && msg != 0) { 2280 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 2281 DeclAccessPair Found; 2282 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 2283 DestType, 2284 /*Complain*/ true, 2285 Found); 2286 if (Fn) { 2287 // If DestType is a function type (not to be confused with the function 2288 // pointer type), it will be possible to resolve the function address, 2289 // but the type cast should be considered as failure. 2290 OverloadExpr *OE = OverloadExpr::find(SrcExpr.get()).Expression; 2291 Self.Diag(OpRange.getBegin(), diag::err_bad_cstyle_cast_overload) 2292 << OE->getName() << DestType << OpRange 2293 << OE->getQualifierLoc().getSourceRange(); 2294 Self.NoteAllOverloadCandidates(SrcExpr.get()); 2295 } 2296 } else { 2297 diagnoseBadCast(Self, msg, (FunctionalStyle ? CT_Functional : CT_CStyle), 2298 OpRange, SrcExpr.get(), DestType, ListInitialization); 2299 } 2300 } else if (Kind == CK_BitCast) { 2301 checkCastAlign(); 2302 } 2303 2304 // Clear out SrcExpr if there was a fatal error. 2305 if (tcr != TC_Success) 2306 SrcExpr = ExprError(); 2307} 2308 2309/// DiagnoseBadFunctionCast - Warn whenever a function call is cast to a 2310/// non-matching type. Such as enum function call to int, int call to 2311/// pointer; etc. Cast to 'void' is an exception. 2312static void DiagnoseBadFunctionCast(Sema &Self, const ExprResult &SrcExpr, 2313 QualType DestType) { 2314 if (Self.Diags.isIgnored(diag::warn_bad_function_cast, 2315 SrcExpr.get()->getExprLoc())) 2316 return; 2317 2318 if (!isa<CallExpr>(SrcExpr.get())) 2319 return; 2320 2321 QualType SrcType = SrcExpr.get()->getType(); 2322 if (DestType.getUnqualifiedType()->isVoidType()) 2323 return; 2324 if ((SrcType->isAnyPointerType() || SrcType->isBlockPointerType()) 2325 && (DestType->isAnyPointerType() || DestType->isBlockPointerType())) 2326 return; 2327 if (SrcType->isIntegerType() && DestType->isIntegerType() && 2328 (SrcType->isBooleanType() == DestType->isBooleanType()) && 2329 (SrcType->isEnumeralType() == DestType->isEnumeralType())) 2330 return; 2331 if (SrcType->isRealFloatingType() && DestType->isRealFloatingType()) 2332 return; 2333 if (SrcType->isEnumeralType() && DestType->isEnumeralType()) 2334 return; 2335 if (SrcType->isComplexType() && DestType->isComplexType()) 2336 return; 2337 if (SrcType->isComplexIntegerType() && DestType->isComplexIntegerType()) 2338 return; 2339 2340 Self.Diag(SrcExpr.get()->getExprLoc(), 2341 diag::warn_bad_function_cast) 2342 << SrcType << DestType << SrcExpr.get()->getSourceRange(); 2343} 2344 2345/// Check the semantics of a C-style cast operation, in C. 2346void CastOperation::CheckCStyleCast() { 2347 assert(!Self.getLangOpts().CPlusPlus); 2348 2349 // C-style casts can resolve __unknown_any types. 2350 if (claimPlaceholder(BuiltinType::UnknownAny)) { 2351 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 2352 SrcExpr.get(), Kind, 2353 ValueKind, BasePath); 2354 return; 2355 } 2356 2357 // C99 6.5.4p2: the cast type needs to be void or scalar and the expression 2358 // type needs to be scalar. 2359 if (DestType->isVoidType()) { 2360 // We don't necessarily do lvalue-to-rvalue conversions on this. 2361 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get()); 2362 if (SrcExpr.isInvalid()) 2363 return; 2364 2365 // Cast to void allows any expr type. 2366 Kind = CK_ToVoid; 2367 return; 2368 } 2369 2370 // Overloads are allowed with C extensions, so we need to support them. 2371 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 2372 DeclAccessPair DAP; 2373 if (FunctionDecl *FD = Self.ResolveAddressOfOverloadedFunction( 2374 SrcExpr.get(), DestType, /*Complain=*/true, DAP)) 2375 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr.get(), DAP, FD); 2376 else 2377 return; 2378 assert(SrcExpr.isUsable()); 2379 } 2380 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 2381 if (SrcExpr.isInvalid()) 2382 return; 2383 QualType SrcType = SrcExpr.get()->getType(); 2384 2385 assert(!SrcType->isPlaceholderType()); 2386 2387 // OpenCL v1 s6.5: Casting a pointer to address space A to a pointer to 2388 // address space B is illegal. 2389 if (Self.getLangOpts().OpenCL && DestType->isPointerType() && 2390 SrcType->isPointerType()) { 2391 const PointerType *DestPtr = DestType->getAs<PointerType>(); 2392 if (!DestPtr->isAddressSpaceOverlapping(*SrcType->getAs<PointerType>())) { 2393 Self.Diag(OpRange.getBegin(), 2394 diag::err_typecheck_incompatible_address_space) 2395 << SrcType << DestType << Sema::AA_Casting 2396 << SrcExpr.get()->getSourceRange(); 2397 SrcExpr = ExprError(); 2398 return; 2399 } 2400 } 2401 2402 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 2403 diag::err_typecheck_cast_to_incomplete)) { 2404 SrcExpr = ExprError(); 2405 return; 2406 } 2407 2408 if (!DestType->isScalarType() && !DestType->isVectorType()) { 2409 const RecordType *DestRecordTy = DestType->getAs<RecordType>(); 2410 2411 if (DestRecordTy && Self.Context.hasSameUnqualifiedType(DestType, SrcType)){ 2412 // GCC struct/union extension: allow cast to self. 2413 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_nonscalar) 2414 << DestType << SrcExpr.get()->getSourceRange(); 2415 Kind = CK_NoOp; 2416 return; 2417 } 2418 2419 // GCC's cast to union extension. 2420 if (DestRecordTy && DestRecordTy->getDecl()->isUnion()) { 2421 RecordDecl *RD = DestRecordTy->getDecl(); 2422 RecordDecl::field_iterator Field, FieldEnd; 2423 for (Field = RD->field_begin(), FieldEnd = RD->field_end(); 2424 Field != FieldEnd; ++Field) { 2425 if (Self.Context.hasSameUnqualifiedType(Field->getType(), SrcType) && 2426 !Field->isUnnamedBitfield()) { 2427 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union) 2428 << SrcExpr.get()->getSourceRange(); 2429 break; 2430 } 2431 } 2432 if (Field == FieldEnd) { 2433 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cast_to_union_no_type) 2434 << SrcType << SrcExpr.get()->getSourceRange(); 2435 SrcExpr = ExprError(); 2436 return; 2437 } 2438 Kind = CK_ToUnion; 2439 return; 2440 } 2441 2442 // OpenCL v2.0 s6.13.10 - Allow casts from '0' to event_t type. 2443 if (Self.getLangOpts().OpenCL && DestType->isEventT()) { 2444 llvm::APSInt CastInt; 2445 if (SrcExpr.get()->EvaluateAsInt(CastInt, Self.Context)) { 2446 if (0 == CastInt) { 2447 Kind = CK_ZeroToOCLEvent; 2448 return; 2449 } 2450 Self.Diag(OpRange.getBegin(), 2451 diag::err_opencl_cast_non_zero_to_event_t) 2452 << CastInt.toString(10) << SrcExpr.get()->getSourceRange(); 2453 SrcExpr = ExprError(); 2454 return; 2455 } 2456 } 2457 2458 // Reject any other conversions to non-scalar types. 2459 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cond_expect_scalar) 2460 << DestType << SrcExpr.get()->getSourceRange(); 2461 SrcExpr = ExprError(); 2462 return; 2463 } 2464 2465 // The type we're casting to is known to be a scalar or vector. 2466 2467 // Require the operand to be a scalar or vector. 2468 if (!SrcType->isScalarType() && !SrcType->isVectorType()) { 2469 Self.Diag(SrcExpr.get()->getExprLoc(), 2470 diag::err_typecheck_expect_scalar_operand) 2471 << SrcType << SrcExpr.get()->getSourceRange(); 2472 SrcExpr = ExprError(); 2473 return; 2474 } 2475 2476 if (DestType->isExtVectorType()) { 2477 SrcExpr = Self.CheckExtVectorCast(OpRange, DestType, SrcExpr.get(), Kind); 2478 return; 2479 } 2480 2481 if (const VectorType *DestVecTy = DestType->getAs<VectorType>()) { 2482 if (DestVecTy->getVectorKind() == VectorType::AltiVecVector && 2483 (SrcType->isIntegerType() || SrcType->isFloatingType())) { 2484 Kind = CK_VectorSplat; 2485 SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get()); 2486 } else if (Self.CheckVectorCast(OpRange, DestType, SrcType, Kind)) { 2487 SrcExpr = ExprError(); 2488 } 2489 return; 2490 } 2491 2492 if (SrcType->isVectorType()) { 2493 if (Self.CheckVectorCast(OpRange, SrcType, DestType, Kind)) 2494 SrcExpr = ExprError(); 2495 return; 2496 } 2497 2498 // The source and target types are both scalars, i.e. 2499 // - arithmetic types (fundamental, enum, and complex) 2500 // - all kinds of pointers 2501 // Note that member pointers were filtered out with C++, above. 2502 2503 if (isa<ObjCSelectorExpr>(SrcExpr.get())) { 2504 Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_selector_expr); 2505 SrcExpr = ExprError(); 2506 return; 2507 } 2508 2509 // If either type is a pointer, the other type has to be either an 2510 // integer or a pointer. 2511 if (!DestType->isArithmeticType()) { 2512 if (!SrcType->isIntegralType(Self.Context) && SrcType->isArithmeticType()) { 2513 Self.Diag(SrcExpr.get()->getExprLoc(), 2514 diag::err_cast_pointer_from_non_pointer_int) 2515 << SrcType << SrcExpr.get()->getSourceRange(); 2516 SrcExpr = ExprError(); 2517 return; 2518 } 2519 checkIntToPointerCast(/* CStyle */ true, OpRange.getBegin(), SrcExpr.get(), 2520 DestType, Self); 2521 } else if (!SrcType->isArithmeticType()) { 2522 if (!DestType->isIntegralType(Self.Context) && 2523 DestType->isArithmeticType()) { 2524 Self.Diag(SrcExpr.get()->getLocStart(), 2525 diag::err_cast_pointer_to_non_pointer_int) 2526 << DestType << SrcExpr.get()->getSourceRange(); 2527 SrcExpr = ExprError(); 2528 return; 2529 } 2530 } 2531 2532 if (Self.getLangOpts().OpenCL && 2533 !Self.getOpenCLOptions().isEnabled("cl_khr_fp16")) { 2534 if (DestType->isHalfType()) { 2535 Self.Diag(SrcExpr.get()->getLocStart(), diag::err_opencl_cast_to_half) 2536 << DestType << SrcExpr.get()->getSourceRange(); 2537 SrcExpr = ExprError(); 2538 return; 2539 } 2540 } 2541 2542 // ARC imposes extra restrictions on casts. 2543 if (Self.getLangOpts().ObjCAutoRefCount) { 2544 checkObjCARCConversion(Sema::CCK_CStyleCast); 2545 if (SrcExpr.isInvalid()) 2546 return; 2547 2548 if (const PointerType *CastPtr = DestType->getAs<PointerType>()) { 2549 if (const PointerType *ExprPtr = SrcType->getAs<PointerType>()) { 2550 Qualifiers CastQuals = CastPtr->getPointeeType().getQualifiers(); 2551 Qualifiers ExprQuals = ExprPtr->getPointeeType().getQualifiers(); 2552 if (CastPtr->getPointeeType()->isObjCLifetimeType() && 2553 ExprPtr->getPointeeType()->isObjCLifetimeType() && 2554 !CastQuals.compatiblyIncludesObjCLifetime(ExprQuals)) { 2555 Self.Diag(SrcExpr.get()->getLocStart(), 2556 diag::err_typecheck_incompatible_ownership) 2557 << SrcType << DestType << Sema::AA_Casting 2558 << SrcExpr.get()->getSourceRange(); 2559 return; 2560 } 2561 } 2562 } 2563 else if (!Self.CheckObjCARCUnavailableWeakConversion(DestType, SrcType)) { 2564 Self.Diag(SrcExpr.get()->getLocStart(), 2565 diag::err_arc_convesion_of_weak_unavailable) 2566 << 1 << SrcType << DestType << SrcExpr.get()->getSourceRange(); 2567 SrcExpr = ExprError(); 2568 return; 2569 } 2570 } 2571 2572 DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType); 2573 DiagnoseCallingConvCast(Self, SrcExpr, DestType, OpRange); 2574 DiagnoseBadFunctionCast(Self, SrcExpr, DestType); 2575 Kind = Self.PrepareScalarCast(SrcExpr, DestType); 2576 if (SrcExpr.isInvalid()) 2577 return; 2578 2579 if (Kind == CK_BitCast) 2580 checkCastAlign(); 2581 2582 // -Wcast-qual 2583 QualType TheOffendingSrcType, TheOffendingDestType; 2584 Qualifiers CastAwayQualifiers; 2585 if (SrcType->isAnyPointerType() && DestType->isAnyPointerType() && 2586 CastsAwayConstness(Self, SrcType, DestType, true, false, 2587 &TheOffendingSrcType, &TheOffendingDestType, 2588 &CastAwayQualifiers)) { 2589 int qualifiers = -1; 2590 if (CastAwayQualifiers.hasConst() && CastAwayQualifiers.hasVolatile()) { 2591 qualifiers = 0; 2592 } else if (CastAwayQualifiers.hasConst()) { 2593 qualifiers = 1; 2594 } else if (CastAwayQualifiers.hasVolatile()) { 2595 qualifiers = 2; 2596 } 2597 // This is a variant of int **x; const int **y = (const int **)x; 2598 if (qualifiers == -1) 2599 Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual2) << 2600 SrcType << DestType; 2601 else 2602 Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual) << 2603 TheOffendingSrcType << TheOffendingDestType << qualifiers; 2604 } 2605} 2606 2607ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc, 2608 TypeSourceInfo *CastTypeInfo, 2609 SourceLocation RPLoc, 2610 Expr *CastExpr) { 2611 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr); 2612 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2613 Op.OpRange = SourceRange(LPLoc, CastExpr->getLocEnd()); 2614 2615 if (getLangOpts().CPlusPlus) { 2616 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/ false, 2617 isa<InitListExpr>(CastExpr)); 2618 } else { 2619 Op.CheckCStyleCast(); 2620 } 2621 2622 if (Op.SrcExpr.isInvalid()) 2623 return ExprError(); 2624 2625 return Op.complete(CStyleCastExpr::Create(Context, Op.ResultType, 2626 Op.ValueKind, Op.Kind, Op.SrcExpr.get(), 2627 &Op.BasePath, CastTypeInfo, LPLoc, RPLoc)); 2628} 2629 2630ExprResult Sema::BuildCXXFunctionalCastExpr(TypeSourceInfo *CastTypeInfo, 2631 SourceLocation LPLoc, 2632 Expr *CastExpr, 2633 SourceLocation RPLoc) { 2634 assert(LPLoc.isValid() && "List-initialization shouldn't get here."); 2635 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr); 2636 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2637 Op.OpRange = SourceRange(Op.DestRange.getBegin(), CastExpr->getLocEnd()); 2638 2639 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/true, /*ListInit=*/false); 2640 if (Op.SrcExpr.isInvalid()) 2641 return ExprError(); 2642 2643 auto *SubExpr = Op.SrcExpr.get(); 2644 if (auto *BindExpr = dyn_cast<CXXBindTemporaryExpr>(SubExpr)) 2645 SubExpr = BindExpr->getSubExpr(); 2646 if (auto *ConstructExpr = dyn_cast<CXXConstructExpr>(SubExpr)) 2647 ConstructExpr->setParenOrBraceRange(SourceRange(LPLoc, RPLoc)); 2648 2649 return Op.complete(CXXFunctionalCastExpr::Create(Context, Op.ResultType, 2650 Op.ValueKind, CastTypeInfo, Op.Kind, 2651 Op.SrcExpr.get(), &Op.BasePath, LPLoc, RPLoc)); 2652} 2653