SemaCast.cpp revision 322740
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 checkObjCConversion(Sema::CheckedConversionKind CCK) { 124 assert(Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()); 125 126 Expr *src = SrcExpr.get(); 127 if (Self.CheckObjCConversion(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 146static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr, 147 QualType DestType); 148 149// The Try functions attempt a specific way of casting. If they succeed, they 150// return TC_Success. If their way of casting is not appropriate for the given 151// arguments, they return TC_NotApplicable and *may* set diag to a diagnostic 152// to emit if no other way succeeds. If their way of casting is appropriate but 153// fails, they return TC_Failed and *must* set diag; they can set it to 0 if 154// they emit a specialized diagnostic. 155// All diagnostics returned by these functions must expect the same three 156// arguments: 157// %0: Cast Type (a value from the CastType enumeration) 158// %1: Source Type 159// %2: Destination Type 160static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, 161 QualType DestType, bool CStyle, 162 CastKind &Kind, 163 CXXCastPath &BasePath, 164 unsigned &msg); 165static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, 166 QualType DestType, bool CStyle, 167 SourceRange OpRange, 168 unsigned &msg, 169 CastKind &Kind, 170 CXXCastPath &BasePath); 171static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType, 172 QualType DestType, bool CStyle, 173 SourceRange OpRange, 174 unsigned &msg, 175 CastKind &Kind, 176 CXXCastPath &BasePath); 177static TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType, 178 CanQualType DestType, bool CStyle, 179 SourceRange OpRange, 180 QualType OrigSrcType, 181 QualType OrigDestType, unsigned &msg, 182 CastKind &Kind, 183 CXXCastPath &BasePath); 184static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, 185 QualType SrcType, 186 QualType DestType,bool CStyle, 187 SourceRange OpRange, 188 unsigned &msg, 189 CastKind &Kind, 190 CXXCastPath &BasePath); 191 192static TryCastResult TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, 193 QualType DestType, 194 Sema::CheckedConversionKind CCK, 195 SourceRange OpRange, 196 unsigned &msg, CastKind &Kind, 197 bool ListInitialization); 198static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, 199 QualType DestType, 200 Sema::CheckedConversionKind CCK, 201 SourceRange OpRange, 202 unsigned &msg, CastKind &Kind, 203 CXXCastPath &BasePath, 204 bool ListInitialization); 205static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr, 206 QualType DestType, bool CStyle, 207 unsigned &msg); 208static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr, 209 QualType DestType, bool CStyle, 210 SourceRange OpRange, 211 unsigned &msg, 212 CastKind &Kind); 213 214 215/// ActOnCXXNamedCast - Parse {dynamic,static,reinterpret,const}_cast's. 216ExprResult 217Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind, 218 SourceLocation LAngleBracketLoc, Declarator &D, 219 SourceLocation RAngleBracketLoc, 220 SourceLocation LParenLoc, Expr *E, 221 SourceLocation RParenLoc) { 222 223 assert(!D.isInvalidType()); 224 225 TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, E->getType()); 226 if (D.isInvalidType()) 227 return ExprError(); 228 229 if (getLangOpts().CPlusPlus) { 230 // Check that there are no default arguments (C++ only). 231 CheckExtraCXXDefaultArguments(D); 232 } 233 234 return BuildCXXNamedCast(OpLoc, Kind, TInfo, E, 235 SourceRange(LAngleBracketLoc, RAngleBracketLoc), 236 SourceRange(LParenLoc, RParenLoc)); 237} 238 239ExprResult 240Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind, 241 TypeSourceInfo *DestTInfo, Expr *E, 242 SourceRange AngleBrackets, SourceRange Parens) { 243 ExprResult Ex = E; 244 QualType DestType = DestTInfo->getType(); 245 246 // If the type is dependent, we won't do the semantic analysis now. 247 bool TypeDependent = 248 DestType->isDependentType() || Ex.get()->isTypeDependent(); 249 250 CastOperation Op(*this, DestType, E); 251 Op.OpRange = SourceRange(OpLoc, Parens.getEnd()); 252 Op.DestRange = AngleBrackets; 253 254 switch (Kind) { 255 default: llvm_unreachable("Unknown C++ cast!"); 256 257 case tok::kw_const_cast: 258 if (!TypeDependent) { 259 Op.CheckConstCast(); 260 if (Op.SrcExpr.isInvalid()) 261 return ExprError(); 262 DiscardMisalignedMemberAddress(DestType.getTypePtr(), E); 263 } 264 return Op.complete(CXXConstCastExpr::Create(Context, Op.ResultType, 265 Op.ValueKind, Op.SrcExpr.get(), DestTInfo, 266 OpLoc, Parens.getEnd(), 267 AngleBrackets)); 268 269 case tok::kw_dynamic_cast: { 270 if (!TypeDependent) { 271 Op.CheckDynamicCast(); 272 if (Op.SrcExpr.isInvalid()) 273 return ExprError(); 274 } 275 return Op.complete(CXXDynamicCastExpr::Create(Context, Op.ResultType, 276 Op.ValueKind, Op.Kind, Op.SrcExpr.get(), 277 &Op.BasePath, DestTInfo, 278 OpLoc, Parens.getEnd(), 279 AngleBrackets)); 280 } 281 case tok::kw_reinterpret_cast: { 282 if (!TypeDependent) { 283 Op.CheckReinterpretCast(); 284 if (Op.SrcExpr.isInvalid()) 285 return ExprError(); 286 DiscardMisalignedMemberAddress(DestType.getTypePtr(), E); 287 } 288 return Op.complete(CXXReinterpretCastExpr::Create(Context, Op.ResultType, 289 Op.ValueKind, Op.Kind, Op.SrcExpr.get(), 290 nullptr, DestTInfo, OpLoc, 291 Parens.getEnd(), 292 AngleBrackets)); 293 } 294 case tok::kw_static_cast: { 295 if (!TypeDependent) { 296 Op.CheckStaticCast(); 297 if (Op.SrcExpr.isInvalid()) 298 return ExprError(); 299 DiscardMisalignedMemberAddress(DestType.getTypePtr(), E); 300 } 301 302 return Op.complete(CXXStaticCastExpr::Create(Context, Op.ResultType, 303 Op.ValueKind, Op.Kind, Op.SrcExpr.get(), 304 &Op.BasePath, DestTInfo, 305 OpLoc, Parens.getEnd(), 306 AngleBrackets)); 307 } 308 } 309} 310 311/// Try to diagnose a failed overloaded cast. Returns true if 312/// diagnostics were emitted. 313static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT, 314 SourceRange range, Expr *src, 315 QualType destType, 316 bool listInitialization) { 317 switch (CT) { 318 // These cast kinds don't consider user-defined conversions. 319 case CT_Const: 320 case CT_Reinterpret: 321 case CT_Dynamic: 322 return false; 323 324 // These do. 325 case CT_Static: 326 case CT_CStyle: 327 case CT_Functional: 328 break; 329 } 330 331 QualType srcType = src->getType(); 332 if (!destType->isRecordType() && !srcType->isRecordType()) 333 return false; 334 335 InitializedEntity entity = InitializedEntity::InitializeTemporary(destType); 336 InitializationKind initKind 337 = (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(), 338 range, listInitialization) 339 : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range, 340 listInitialization) 341 : InitializationKind::CreateCast(/*type range?*/ range); 342 InitializationSequence sequence(S, entity, initKind, src); 343 344 assert(sequence.Failed() && "initialization succeeded on second try?"); 345 switch (sequence.getFailureKind()) { 346 default: return false; 347 348 case InitializationSequence::FK_ConstructorOverloadFailed: 349 case InitializationSequence::FK_UserConversionOverloadFailed: 350 break; 351 } 352 353 OverloadCandidateSet &candidates = sequence.getFailedCandidateSet(); 354 355 unsigned msg = 0; 356 OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates; 357 358 switch (sequence.getFailedOverloadResult()) { 359 case OR_Success: llvm_unreachable("successful failed overload"); 360 case OR_No_Viable_Function: 361 if (candidates.empty()) 362 msg = diag::err_ovl_no_conversion_in_cast; 363 else 364 msg = diag::err_ovl_no_viable_conversion_in_cast; 365 howManyCandidates = OCD_AllCandidates; 366 break; 367 368 case OR_Ambiguous: 369 msg = diag::err_ovl_ambiguous_conversion_in_cast; 370 howManyCandidates = OCD_ViableCandidates; 371 break; 372 373 case OR_Deleted: 374 msg = diag::err_ovl_deleted_conversion_in_cast; 375 howManyCandidates = OCD_ViableCandidates; 376 break; 377 } 378 379 S.Diag(range.getBegin(), msg) 380 << CT << srcType << destType 381 << range << src->getSourceRange(); 382 383 candidates.NoteCandidates(S, howManyCandidates, src); 384 385 return true; 386} 387 388/// Diagnose a failed cast. 389static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType, 390 SourceRange opRange, Expr *src, QualType destType, 391 bool listInitialization) { 392 if (msg == diag::err_bad_cxx_cast_generic && 393 tryDiagnoseOverloadedCast(S, castType, opRange, src, destType, 394 listInitialization)) 395 return; 396 397 S.Diag(opRange.getBegin(), msg) << castType 398 << src->getType() << destType << opRange << src->getSourceRange(); 399 400 // Detect if both types are (ptr to) class, and note any incompleteness. 401 int DifferentPtrness = 0; 402 QualType From = destType; 403 if (auto Ptr = From->getAs<PointerType>()) { 404 From = Ptr->getPointeeType(); 405 DifferentPtrness++; 406 } 407 QualType To = src->getType(); 408 if (auto Ptr = To->getAs<PointerType>()) { 409 To = Ptr->getPointeeType(); 410 DifferentPtrness--; 411 } 412 if (!DifferentPtrness) { 413 auto RecFrom = From->getAs<RecordType>(); 414 auto RecTo = To->getAs<RecordType>(); 415 if (RecFrom && RecTo) { 416 auto DeclFrom = RecFrom->getAsCXXRecordDecl(); 417 if (!DeclFrom->isCompleteDefinition()) 418 S.Diag(DeclFrom->getLocation(), diag::note_type_incomplete) 419 << DeclFrom->getDeclName(); 420 auto DeclTo = RecTo->getAsCXXRecordDecl(); 421 if (!DeclTo->isCompleteDefinition()) 422 S.Diag(DeclTo->getLocation(), diag::note_type_incomplete) 423 << DeclTo->getDeclName(); 424 } 425 } 426} 427 428/// UnwrapDissimilarPointerTypes - Like Sema::UnwrapSimilarPointerTypes, 429/// this removes one level of indirection from both types, provided that they're 430/// the same kind of pointer (plain or to-member). Unlike the Sema function, 431/// this one doesn't care if the two pointers-to-member don't point into the 432/// same class. This is because CastsAwayConstness doesn't care. 433/// And additionally, it handles C++ references. If both the types are 434/// references, then their pointee types are returned, 435/// else if only one of them is reference, it's pointee type is returned, 436/// and the other type is returned as-is. 437static bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) { 438 const PointerType *T1PtrType = T1->getAs<PointerType>(), 439 *T2PtrType = T2->getAs<PointerType>(); 440 if (T1PtrType && T2PtrType) { 441 T1 = T1PtrType->getPointeeType(); 442 T2 = T2PtrType->getPointeeType(); 443 return true; 444 } 445 const ObjCObjectPointerType *T1ObjCPtrType = 446 T1->getAs<ObjCObjectPointerType>(), 447 *T2ObjCPtrType = 448 T2->getAs<ObjCObjectPointerType>(); 449 if (T1ObjCPtrType) { 450 if (T2ObjCPtrType) { 451 T1 = T1ObjCPtrType->getPointeeType(); 452 T2 = T2ObjCPtrType->getPointeeType(); 453 return true; 454 } 455 else if (T2PtrType) { 456 T1 = T1ObjCPtrType->getPointeeType(); 457 T2 = T2PtrType->getPointeeType(); 458 return true; 459 } 460 } 461 else if (T2ObjCPtrType) { 462 if (T1PtrType) { 463 T2 = T2ObjCPtrType->getPointeeType(); 464 T1 = T1PtrType->getPointeeType(); 465 return true; 466 } 467 } 468 469 const MemberPointerType *T1MPType = T1->getAs<MemberPointerType>(), 470 *T2MPType = T2->getAs<MemberPointerType>(); 471 if (T1MPType && T2MPType) { 472 T1 = T1MPType->getPointeeType(); 473 T2 = T2MPType->getPointeeType(); 474 return true; 475 } 476 477 const BlockPointerType *T1BPType = T1->getAs<BlockPointerType>(), 478 *T2BPType = T2->getAs<BlockPointerType>(); 479 if (T1BPType && T2BPType) { 480 T1 = T1BPType->getPointeeType(); 481 T2 = T2BPType->getPointeeType(); 482 return true; 483 } 484 485 const LValueReferenceType *T1RefType = T1->getAs<LValueReferenceType>(), 486 *T2RefType = T2->getAs<LValueReferenceType>(); 487 if (T1RefType && T2RefType) { 488 T1 = T1RefType->getPointeeType(); 489 T2 = T2RefType->getPointeeType(); 490 return true; 491 } 492 493 if (T1RefType) { 494 T1 = T1RefType->getPointeeType(); 495 // T2 = T2; 496 return true; 497 } 498 499 if (T2RefType) { 500 // T1 = T1; 501 T2 = T2RefType->getPointeeType(); 502 return true; 503 } 504 505 return false; 506} 507 508/// CastsAwayConstness - Check if the pointer conversion from SrcType to 509/// DestType casts away constness as defined in C++ 5.2.11p8ff. This is used by 510/// the cast checkers. Both arguments must denote pointer (possibly to member) 511/// types. 512/// 513/// \param CheckCVR Whether to check for const/volatile/restrict qualifiers. 514/// 515/// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers. 516static bool 517CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, 518 bool CheckCVR, bool CheckObjCLifetime, 519 QualType *TheOffendingSrcType = nullptr, 520 QualType *TheOffendingDestType = nullptr, 521 Qualifiers *CastAwayQualifiers = nullptr) { 522 // If the only checking we care about is for Objective-C lifetime qualifiers, 523 // and we're not in ObjC mode, there's nothing to check. 524 if (!CheckCVR && CheckObjCLifetime && 525 !Self.Context.getLangOpts().ObjC1) 526 return false; 527 528 // Casting away constness is defined in C++ 5.2.11p8 with reference to 529 // C++ 4.4. We piggyback on Sema::IsQualificationConversion for this, since 530 // the rules are non-trivial. So first we construct Tcv *...cv* as described 531 // in C++ 5.2.11p8. 532 assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() || 533 SrcType->isBlockPointerType() || 534 DestType->isLValueReferenceType()) && 535 "Source type is not pointer or pointer to member."); 536 assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() || 537 DestType->isBlockPointerType() || 538 DestType->isLValueReferenceType()) && 539 "Destination type is not pointer or pointer to member, or reference."); 540 541 QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType), 542 UnwrappedDestType = Self.Context.getCanonicalType(DestType); 543 SmallVector<Qualifiers, 8> cv1, cv2; 544 545 // Find the qualifiers. We only care about cvr-qualifiers for the 546 // purpose of this check, because other qualifiers (address spaces, 547 // Objective-C GC, etc.) are part of the type's identity. 548 QualType PrevUnwrappedSrcType = UnwrappedSrcType; 549 QualType PrevUnwrappedDestType = UnwrappedDestType; 550 while (UnwrapDissimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) { 551 // Determine the relevant qualifiers at this level. 552 Qualifiers SrcQuals, DestQuals; 553 Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals); 554 Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals); 555 556 // We do not meaningfully track object const-ness of Objective-C object 557 // types. Remove const from the source type if either the source or 558 // the destination is an Objective-C object type. 559 if (UnwrappedSrcType->isObjCObjectType() || 560 UnwrappedDestType->isObjCObjectType()) 561 SrcQuals.removeConst(); 562 563 Qualifiers RetainedSrcQuals, RetainedDestQuals; 564 if (CheckCVR) { 565 RetainedSrcQuals.setCVRQualifiers(SrcQuals.getCVRQualifiers()); 566 RetainedDestQuals.setCVRQualifiers(DestQuals.getCVRQualifiers()); 567 568 if (RetainedSrcQuals != RetainedDestQuals && TheOffendingSrcType && 569 TheOffendingDestType && CastAwayQualifiers) { 570 *TheOffendingSrcType = PrevUnwrappedSrcType; 571 *TheOffendingDestType = PrevUnwrappedDestType; 572 *CastAwayQualifiers = RetainedSrcQuals - RetainedDestQuals; 573 } 574 } 575 576 if (CheckObjCLifetime && 577 !DestQuals.compatiblyIncludesObjCLifetime(SrcQuals)) 578 return true; 579 580 cv1.push_back(RetainedSrcQuals); 581 cv2.push_back(RetainedDestQuals); 582 583 PrevUnwrappedSrcType = UnwrappedSrcType; 584 PrevUnwrappedDestType = UnwrappedDestType; 585 } 586 if (cv1.empty()) 587 return false; 588 589 // Construct void pointers with those qualifiers (in reverse order of 590 // unwrapping, of course). 591 QualType SrcConstruct = Self.Context.VoidTy; 592 QualType DestConstruct = Self.Context.VoidTy; 593 ASTContext &Context = Self.Context; 594 for (SmallVectorImpl<Qualifiers>::reverse_iterator i1 = cv1.rbegin(), 595 i2 = cv2.rbegin(); 596 i1 != cv1.rend(); ++i1, ++i2) { 597 SrcConstruct 598 = Context.getPointerType(Context.getQualifiedType(SrcConstruct, *i1)); 599 DestConstruct 600 = Context.getPointerType(Context.getQualifiedType(DestConstruct, *i2)); 601 } 602 603 // Test if they're compatible. 604 bool ObjCLifetimeConversion; 605 return SrcConstruct != DestConstruct && 606 !Self.IsQualificationConversion(SrcConstruct, DestConstruct, false, 607 ObjCLifetimeConversion); 608} 609 610/// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid. 611/// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime- 612/// checked downcasts in class hierarchies. 613void CastOperation::CheckDynamicCast() { 614 if (ValueKind == VK_RValue) 615 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 616 else if (isPlaceholder()) 617 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get()); 618 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 619 return; 620 621 QualType OrigSrcType = SrcExpr.get()->getType(); 622 QualType DestType = Self.Context.getCanonicalType(this->DestType); 623 624 // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type, 625 // or "pointer to cv void". 626 627 QualType DestPointee; 628 const PointerType *DestPointer = DestType->getAs<PointerType>(); 629 const ReferenceType *DestReference = nullptr; 630 if (DestPointer) { 631 DestPointee = DestPointer->getPointeeType(); 632 } else if ((DestReference = DestType->getAs<ReferenceType>())) { 633 DestPointee = DestReference->getPointeeType(); 634 } else { 635 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr) 636 << this->DestType << DestRange; 637 SrcExpr = ExprError(); 638 return; 639 } 640 641 const RecordType *DestRecord = DestPointee->getAs<RecordType>(); 642 if (DestPointee->isVoidType()) { 643 assert(DestPointer && "Reference to void is not possible"); 644 } else if (DestRecord) { 645 if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee, 646 diag::err_bad_dynamic_cast_incomplete, 647 DestRange)) { 648 SrcExpr = ExprError(); 649 return; 650 } 651 } else { 652 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 653 << DestPointee.getUnqualifiedType() << DestRange; 654 SrcExpr = ExprError(); 655 return; 656 } 657 658 // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to 659 // complete class type, [...]. If T is an lvalue reference type, v shall be 660 // an lvalue of a complete class type, [...]. If T is an rvalue reference 661 // type, v shall be an expression having a complete class type, [...] 662 QualType SrcType = Self.Context.getCanonicalType(OrigSrcType); 663 QualType SrcPointee; 664 if (DestPointer) { 665 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 666 SrcPointee = SrcPointer->getPointeeType(); 667 } else { 668 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr) 669 << OrigSrcType << SrcExpr.get()->getSourceRange(); 670 SrcExpr = ExprError(); 671 return; 672 } 673 } else if (DestReference->isLValueReferenceType()) { 674 if (!SrcExpr.get()->isLValue()) { 675 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue) 676 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 677 } 678 SrcPointee = SrcType; 679 } else { 680 // If we're dynamic_casting from a prvalue to an rvalue reference, we need 681 // to materialize the prvalue before we bind the reference to it. 682 if (SrcExpr.get()->isRValue()) 683 SrcExpr = Self.CreateMaterializeTemporaryExpr( 684 SrcType, SrcExpr.get(), /*IsLValueReference*/ false); 685 SrcPointee = SrcType; 686 } 687 688 const RecordType *SrcRecord = SrcPointee->getAs<RecordType>(); 689 if (SrcRecord) { 690 if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee, 691 diag::err_bad_dynamic_cast_incomplete, 692 SrcExpr.get())) { 693 SrcExpr = ExprError(); 694 return; 695 } 696 } else { 697 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 698 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 699 SrcExpr = ExprError(); 700 return; 701 } 702 703 assert((DestPointer || DestReference) && 704 "Bad destination non-ptr/ref slipped through."); 705 assert((DestRecord || DestPointee->isVoidType()) && 706 "Bad destination pointee slipped through."); 707 assert(SrcRecord && "Bad source pointee slipped through."); 708 709 // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness. 710 if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) { 711 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away) 712 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 713 SrcExpr = ExprError(); 714 return; 715 } 716 717 // C++ 5.2.7p3: If the type of v is the same as the required result type, 718 // [except for cv]. 719 if (DestRecord == SrcRecord) { 720 Kind = CK_NoOp; 721 return; 722 } 723 724 // C++ 5.2.7p5 725 // Upcasts are resolved statically. 726 if (DestRecord && 727 Self.IsDerivedFrom(OpRange.getBegin(), SrcPointee, DestPointee)) { 728 if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee, 729 OpRange.getBegin(), OpRange, 730 &BasePath)) { 731 SrcExpr = ExprError(); 732 return; 733 } 734 735 Kind = CK_DerivedToBase; 736 return; 737 } 738 739 // C++ 5.2.7p6: Otherwise, v shall be [polymorphic]. 740 const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition(); 741 assert(SrcDecl && "Definition missing"); 742 if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) { 743 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic) 744 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 745 SrcExpr = ExprError(); 746 } 747 748 // dynamic_cast is not available with -fno-rtti. 749 // As an exception, dynamic_cast to void* is available because it doesn't 750 // use RTTI. 751 if (!Self.getLangOpts().RTTI && !DestPointee->isVoidType()) { 752 Self.Diag(OpRange.getBegin(), diag::err_no_dynamic_cast_with_fno_rtti); 753 SrcExpr = ExprError(); 754 return; 755 } 756 757 // Done. Everything else is run-time checks. 758 Kind = CK_Dynamic; 759} 760 761/// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid. 762/// Refer to C++ 5.2.11 for details. const_cast is typically used in code 763/// like this: 764/// const char *str = "literal"; 765/// legacy_function(const_cast\<char*\>(str)); 766void CastOperation::CheckConstCast() { 767 if (ValueKind == VK_RValue) 768 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 769 else if (isPlaceholder()) 770 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get()); 771 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 772 return; 773 774 unsigned msg = diag::err_bad_cxx_cast_generic; 775 if (TryConstCast(Self, SrcExpr, DestType, /*CStyle*/false, msg) != TC_Success 776 && msg != 0) { 777 Self.Diag(OpRange.getBegin(), msg) << CT_Const 778 << SrcExpr.get()->getType() << DestType << OpRange; 779 SrcExpr = ExprError(); 780 } 781} 782 783/// Check that a reinterpret_cast\<DestType\>(SrcExpr) is not used as upcast 784/// or downcast between respective pointers or references. 785static void DiagnoseReinterpretUpDownCast(Sema &Self, const Expr *SrcExpr, 786 QualType DestType, 787 SourceRange OpRange) { 788 QualType SrcType = SrcExpr->getType(); 789 // When casting from pointer or reference, get pointee type; use original 790 // type otherwise. 791 const CXXRecordDecl *SrcPointeeRD = SrcType->getPointeeCXXRecordDecl(); 792 const CXXRecordDecl *SrcRD = 793 SrcPointeeRD ? SrcPointeeRD : SrcType->getAsCXXRecordDecl(); 794 795 // Examining subobjects for records is only possible if the complete and 796 // valid definition is available. Also, template instantiation is not 797 // allowed here. 798 if (!SrcRD || !SrcRD->isCompleteDefinition() || SrcRD->isInvalidDecl()) 799 return; 800 801 const CXXRecordDecl *DestRD = DestType->getPointeeCXXRecordDecl(); 802 803 if (!DestRD || !DestRD->isCompleteDefinition() || DestRD->isInvalidDecl()) 804 return; 805 806 enum { 807 ReinterpretUpcast, 808 ReinterpretDowncast 809 } ReinterpretKind; 810 811 CXXBasePaths BasePaths; 812 813 if (SrcRD->isDerivedFrom(DestRD, BasePaths)) 814 ReinterpretKind = ReinterpretUpcast; 815 else if (DestRD->isDerivedFrom(SrcRD, BasePaths)) 816 ReinterpretKind = ReinterpretDowncast; 817 else 818 return; 819 820 bool VirtualBase = true; 821 bool NonZeroOffset = false; 822 for (CXXBasePaths::const_paths_iterator I = BasePaths.begin(), 823 E = BasePaths.end(); 824 I != E; ++I) { 825 const CXXBasePath &Path = *I; 826 CharUnits Offset = CharUnits::Zero(); 827 bool IsVirtual = false; 828 for (CXXBasePath::const_iterator IElem = Path.begin(), EElem = Path.end(); 829 IElem != EElem; ++IElem) { 830 IsVirtual = IElem->Base->isVirtual(); 831 if (IsVirtual) 832 break; 833 const CXXRecordDecl *BaseRD = IElem->Base->getType()->getAsCXXRecordDecl(); 834 assert(BaseRD && "Base type should be a valid unqualified class type"); 835 // Don't check if any base has invalid declaration or has no definition 836 // since it has no layout info. 837 const CXXRecordDecl *Class = IElem->Class, 838 *ClassDefinition = Class->getDefinition(); 839 if (Class->isInvalidDecl() || !ClassDefinition || 840 !ClassDefinition->isCompleteDefinition()) 841 return; 842 843 const ASTRecordLayout &DerivedLayout = 844 Self.Context.getASTRecordLayout(Class); 845 Offset += DerivedLayout.getBaseClassOffset(BaseRD); 846 } 847 if (!IsVirtual) { 848 // Don't warn if any path is a non-virtually derived base at offset zero. 849 if (Offset.isZero()) 850 return; 851 // Offset makes sense only for non-virtual bases. 852 else 853 NonZeroOffset = true; 854 } 855 VirtualBase = VirtualBase && IsVirtual; 856 } 857 858 (void) NonZeroOffset; // Silence set but not used warning. 859 assert((VirtualBase || NonZeroOffset) && 860 "Should have returned if has non-virtual base with zero offset"); 861 862 QualType BaseType = 863 ReinterpretKind == ReinterpretUpcast? DestType : SrcType; 864 QualType DerivedType = 865 ReinterpretKind == ReinterpretUpcast? SrcType : DestType; 866 867 SourceLocation BeginLoc = OpRange.getBegin(); 868 Self.Diag(BeginLoc, diag::warn_reinterpret_different_from_static) 869 << DerivedType << BaseType << !VirtualBase << int(ReinterpretKind) 870 << OpRange; 871 Self.Diag(BeginLoc, diag::note_reinterpret_updowncast_use_static) 872 << int(ReinterpretKind) 873 << FixItHint::CreateReplacement(BeginLoc, "static_cast"); 874} 875 876/// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is 877/// valid. 878/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code 879/// like this: 880/// char *bytes = reinterpret_cast\<char*\>(int_ptr); 881void CastOperation::CheckReinterpretCast() { 882 if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload)) 883 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 884 else 885 checkNonOverloadPlaceholders(); 886 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 887 return; 888 889 unsigned msg = diag::err_bad_cxx_cast_generic; 890 TryCastResult tcr = 891 TryReinterpretCast(Self, SrcExpr, DestType, 892 /*CStyle*/false, OpRange, msg, Kind); 893 if (tcr != TC_Success && msg != 0) 894 { 895 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 896 return; 897 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 898 //FIXME: &f<int>; is overloaded and resolvable 899 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload) 900 << OverloadExpr::find(SrcExpr.get()).Expression->getName() 901 << DestType << OpRange; 902 Self.NoteAllOverloadCandidates(SrcExpr.get()); 903 904 } else { 905 diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(), 906 DestType, /*listInitialization=*/false); 907 } 908 SrcExpr = ExprError(); 909 } else if (tcr == TC_Success) { 910 if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()) 911 checkObjCConversion(Sema::CCK_OtherCast); 912 DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange); 913 } 914} 915 916 917/// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid. 918/// Refer to C++ 5.2.9 for details. Static casts are mostly used for making 919/// implicit conversions explicit and getting rid of data loss warnings. 920void CastOperation::CheckStaticCast() { 921 if (isPlaceholder()) { 922 checkNonOverloadPlaceholders(); 923 if (SrcExpr.isInvalid()) 924 return; 925 } 926 927 // This test is outside everything else because it's the only case where 928 // a non-lvalue-reference target type does not lead to decay. 929 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 930 if (DestType->isVoidType()) { 931 Kind = CK_ToVoid; 932 933 if (claimPlaceholder(BuiltinType::Overload)) { 934 Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr, 935 false, // Decay Function to ptr 936 true, // Complain 937 OpRange, DestType, diag::err_bad_static_cast_overload); 938 if (SrcExpr.isInvalid()) 939 return; 940 } 941 942 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get()); 943 return; 944 } 945 946 if (ValueKind == VK_RValue && !DestType->isRecordType() && 947 !isPlaceholder(BuiltinType::Overload)) { 948 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 949 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 950 return; 951 } 952 953 unsigned msg = diag::err_bad_cxx_cast_generic; 954 TryCastResult tcr 955 = TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_OtherCast, OpRange, msg, 956 Kind, BasePath, /*ListInitialization=*/false); 957 if (tcr != TC_Success && msg != 0) { 958 if (SrcExpr.isInvalid()) 959 return; 960 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 961 OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression; 962 Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload) 963 << oe->getName() << DestType << OpRange 964 << oe->getQualifierLoc().getSourceRange(); 965 Self.NoteAllOverloadCandidates(SrcExpr.get()); 966 } else { 967 diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType, 968 /*listInitialization=*/false); 969 } 970 SrcExpr = ExprError(); 971 } else if (tcr == TC_Success) { 972 if (Kind == CK_BitCast) 973 checkCastAlign(); 974 if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()) 975 checkObjCConversion(Sema::CCK_OtherCast); 976 } else if (Kind == CK_BitCast) { 977 checkCastAlign(); 978 } 979} 980 981/// TryStaticCast - Check if a static cast can be performed, and do so if 982/// possible. If @p CStyle, ignore access restrictions on hierarchy casting 983/// and casting away constness. 984static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, 985 QualType DestType, 986 Sema::CheckedConversionKind CCK, 987 SourceRange OpRange, unsigned &msg, 988 CastKind &Kind, CXXCastPath &BasePath, 989 bool ListInitialization) { 990 // Determine whether we have the semantics of a C-style cast. 991 bool CStyle 992 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 993 994 // The order the tests is not entirely arbitrary. There is one conversion 995 // that can be handled in two different ways. Given: 996 // struct A {}; 997 // struct B : public A { 998 // B(); B(const A&); 999 // }; 1000 // const A &a = B(); 1001 // the cast static_cast<const B&>(a) could be seen as either a static 1002 // reference downcast, or an explicit invocation of the user-defined 1003 // conversion using B's conversion constructor. 1004 // DR 427 specifies that the downcast is to be applied here. 1005 1006 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 1007 // Done outside this function. 1008 1009 TryCastResult tcr; 1010 1011 // C++ 5.2.9p5, reference downcast. 1012 // See the function for details. 1013 // DR 427 specifies that this is to be applied before paragraph 2. 1014 tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle, 1015 OpRange, msg, Kind, BasePath); 1016 if (tcr != TC_NotApplicable) 1017 return tcr; 1018 1019 // C++11 [expr.static.cast]p3: 1020 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2 1021 // T2" if "cv2 T2" is reference-compatible with "cv1 T1". 1022 tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind, 1023 BasePath, msg); 1024 if (tcr != TC_NotApplicable) 1025 return tcr; 1026 1027 // C++ 5.2.9p2: An expression e can be explicitly converted to a type T 1028 // [...] if the declaration "T t(e);" is well-formed, [...]. 1029 tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg, 1030 Kind, ListInitialization); 1031 if (SrcExpr.isInvalid()) 1032 return TC_Failed; 1033 if (tcr != TC_NotApplicable) 1034 return tcr; 1035 1036 // C++ 5.2.9p6: May apply the reverse of any standard conversion, except 1037 // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean 1038 // conversions, subject to further restrictions. 1039 // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal 1040 // of qualification conversions impossible. 1041 // In the CStyle case, the earlier attempt to const_cast should have taken 1042 // care of reverse qualification conversions. 1043 1044 QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType()); 1045 1046 // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly 1047 // converted to an integral type. [...] A value of a scoped enumeration type 1048 // can also be explicitly converted to a floating-point type [...]. 1049 if (const EnumType *Enum = SrcType->getAs<EnumType>()) { 1050 if (Enum->getDecl()->isScoped()) { 1051 if (DestType->isBooleanType()) { 1052 Kind = CK_IntegralToBoolean; 1053 return TC_Success; 1054 } else if (DestType->isIntegralType(Self.Context)) { 1055 Kind = CK_IntegralCast; 1056 return TC_Success; 1057 } else if (DestType->isRealFloatingType()) { 1058 Kind = CK_IntegralToFloating; 1059 return TC_Success; 1060 } 1061 } 1062 } 1063 1064 // Reverse integral promotion/conversion. All such conversions are themselves 1065 // again integral promotions or conversions and are thus already handled by 1066 // p2 (TryDirectInitialization above). 1067 // (Note: any data loss warnings should be suppressed.) 1068 // The exception is the reverse of enum->integer, i.e. integer->enum (and 1069 // enum->enum). See also C++ 5.2.9p7. 1070 // The same goes for reverse floating point promotion/conversion and 1071 // floating-integral conversions. Again, only floating->enum is relevant. 1072 if (DestType->isEnumeralType()) { 1073 if (SrcType->isIntegralOrEnumerationType()) { 1074 Kind = CK_IntegralCast; 1075 return TC_Success; 1076 } else if (SrcType->isRealFloatingType()) { 1077 Kind = CK_FloatingToIntegral; 1078 return TC_Success; 1079 } 1080 } 1081 1082 // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast. 1083 // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance. 1084 tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg, 1085 Kind, BasePath); 1086 if (tcr != TC_NotApplicable) 1087 return tcr; 1088 1089 // Reverse member pointer conversion. C++ 4.11 specifies member pointer 1090 // conversion. C++ 5.2.9p9 has additional information. 1091 // DR54's access restrictions apply here also. 1092 tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle, 1093 OpRange, msg, Kind, BasePath); 1094 if (tcr != TC_NotApplicable) 1095 return tcr; 1096 1097 // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to 1098 // void*. C++ 5.2.9p10 specifies additional restrictions, which really is 1099 // just the usual constness stuff. 1100 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 1101 QualType SrcPointee = SrcPointer->getPointeeType(); 1102 if (SrcPointee->isVoidType()) { 1103 if (const PointerType *DestPointer = DestType->getAs<PointerType>()) { 1104 QualType DestPointee = DestPointer->getPointeeType(); 1105 if (DestPointee->isIncompleteOrObjectType()) { 1106 // This is definitely the intended conversion, but it might fail due 1107 // to a qualifier violation. Note that we permit Objective-C lifetime 1108 // and GC qualifier mismatches here. 1109 if (!CStyle) { 1110 Qualifiers DestPointeeQuals = DestPointee.getQualifiers(); 1111 Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers(); 1112 DestPointeeQuals.removeObjCGCAttr(); 1113 DestPointeeQuals.removeObjCLifetime(); 1114 SrcPointeeQuals.removeObjCGCAttr(); 1115 SrcPointeeQuals.removeObjCLifetime(); 1116 if (DestPointeeQuals != SrcPointeeQuals && 1117 !DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) { 1118 msg = diag::err_bad_cxx_cast_qualifiers_away; 1119 return TC_Failed; 1120 } 1121 } 1122 Kind = CK_BitCast; 1123 return TC_Success; 1124 } 1125 1126 // Microsoft permits static_cast from 'pointer-to-void' to 1127 // 'pointer-to-function'. 1128 if (!CStyle && Self.getLangOpts().MSVCCompat && 1129 DestPointee->isFunctionType()) { 1130 Self.Diag(OpRange.getBegin(), diag::ext_ms_cast_fn_obj) << OpRange; 1131 Kind = CK_BitCast; 1132 return TC_Success; 1133 } 1134 } 1135 else if (DestType->isObjCObjectPointerType()) { 1136 // allow both c-style cast and static_cast of objective-c pointers as 1137 // they are pervasive. 1138 Kind = CK_CPointerToObjCPointerCast; 1139 return TC_Success; 1140 } 1141 else if (CStyle && DestType->isBlockPointerType()) { 1142 // allow c-style cast of void * to block pointers. 1143 Kind = CK_AnyPointerToBlockPointerCast; 1144 return TC_Success; 1145 } 1146 } 1147 } 1148 // Allow arbitray objective-c pointer conversion with static casts. 1149 if (SrcType->isObjCObjectPointerType() && 1150 DestType->isObjCObjectPointerType()) { 1151 Kind = CK_BitCast; 1152 return TC_Success; 1153 } 1154 // Allow ns-pointer to cf-pointer conversion in either direction 1155 // with static casts. 1156 if (!CStyle && 1157 Self.CheckTollFreeBridgeStaticCast(DestType, SrcExpr.get(), Kind)) 1158 return TC_Success; 1159 1160 // See if it looks like the user is trying to convert between 1161 // related record types, and select a better diagnostic if so. 1162 if (auto SrcPointer = SrcType->getAs<PointerType>()) 1163 if (auto DestPointer = DestType->getAs<PointerType>()) 1164 if (SrcPointer->getPointeeType()->getAs<RecordType>() && 1165 DestPointer->getPointeeType()->getAs<RecordType>()) 1166 msg = diag::err_bad_cxx_cast_unrelated_class; 1167 1168 // We tried everything. Everything! Nothing works! :-( 1169 return TC_NotApplicable; 1170} 1171 1172/// Tests whether a conversion according to N2844 is valid. 1173TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, 1174 QualType DestType, bool CStyle, 1175 CastKind &Kind, CXXCastPath &BasePath, 1176 unsigned &msg) { 1177 // C++11 [expr.static.cast]p3: 1178 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to 1179 // cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1". 1180 const RValueReferenceType *R = DestType->getAs<RValueReferenceType>(); 1181 if (!R) 1182 return TC_NotApplicable; 1183 1184 if (!SrcExpr->isGLValue()) 1185 return TC_NotApplicable; 1186 1187 // Because we try the reference downcast before this function, from now on 1188 // this is the only cast possibility, so we issue an error if we fail now. 1189 // FIXME: Should allow casting away constness if CStyle. 1190 bool DerivedToBase; 1191 bool ObjCConversion; 1192 bool ObjCLifetimeConversion; 1193 QualType FromType = SrcExpr->getType(); 1194 QualType ToType = R->getPointeeType(); 1195 if (CStyle) { 1196 FromType = FromType.getUnqualifiedType(); 1197 ToType = ToType.getUnqualifiedType(); 1198 } 1199 1200 Sema::ReferenceCompareResult RefResult = Self.CompareReferenceRelationship( 1201 SrcExpr->getLocStart(), ToType, FromType, DerivedToBase, ObjCConversion, 1202 ObjCLifetimeConversion); 1203 if (RefResult != Sema::Ref_Compatible) { 1204 if (CStyle || RefResult == Sema::Ref_Incompatible) 1205 return TC_NotApplicable; 1206 // Diagnose types which are reference-related but not compatible here since 1207 // we can provide better diagnostics. In these cases forwarding to 1208 // [expr.static.cast]p4 should never result in a well-formed cast. 1209 msg = SrcExpr->isLValue() ? diag::err_bad_lvalue_to_rvalue_cast 1210 : diag::err_bad_rvalue_to_rvalue_cast; 1211 return TC_Failed; 1212 } 1213 1214 if (DerivedToBase) { 1215 Kind = CK_DerivedToBase; 1216 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1217 /*DetectVirtual=*/true); 1218 if (!Self.IsDerivedFrom(SrcExpr->getLocStart(), SrcExpr->getType(), 1219 R->getPointeeType(), Paths)) 1220 return TC_NotApplicable; 1221 1222 Self.BuildBasePathArray(Paths, BasePath); 1223 } else 1224 Kind = CK_NoOp; 1225 1226 return TC_Success; 1227} 1228 1229/// Tests whether a conversion according to C++ 5.2.9p5 is valid. 1230TryCastResult 1231TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType, 1232 bool CStyle, SourceRange OpRange, 1233 unsigned &msg, CastKind &Kind, 1234 CXXCastPath &BasePath) { 1235 // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be 1236 // cast to type "reference to cv2 D", where D is a class derived from B, 1237 // if a valid standard conversion from "pointer to D" to "pointer to B" 1238 // exists, cv2 >= cv1, and B is not a virtual base class of D. 1239 // In addition, DR54 clarifies that the base must be accessible in the 1240 // current context. Although the wording of DR54 only applies to the pointer 1241 // variant of this rule, the intent is clearly for it to apply to the this 1242 // conversion as well. 1243 1244 const ReferenceType *DestReference = DestType->getAs<ReferenceType>(); 1245 if (!DestReference) { 1246 return TC_NotApplicable; 1247 } 1248 bool RValueRef = DestReference->isRValueReferenceType(); 1249 if (!RValueRef && !SrcExpr->isLValue()) { 1250 // We know the left side is an lvalue reference, so we can suggest a reason. 1251 msg = diag::err_bad_cxx_cast_rvalue; 1252 return TC_NotApplicable; 1253 } 1254 1255 QualType DestPointee = DestReference->getPointeeType(); 1256 1257 // FIXME: If the source is a prvalue, we should issue a warning (because the 1258 // cast always has undefined behavior), and for AST consistency, we should 1259 // materialize a temporary. 1260 return TryStaticDowncast(Self, 1261 Self.Context.getCanonicalType(SrcExpr->getType()), 1262 Self.Context.getCanonicalType(DestPointee), CStyle, 1263 OpRange, SrcExpr->getType(), DestType, msg, Kind, 1264 BasePath); 1265} 1266 1267/// Tests whether a conversion according to C++ 5.2.9p8 is valid. 1268TryCastResult 1269TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType, 1270 bool CStyle, SourceRange OpRange, 1271 unsigned &msg, CastKind &Kind, 1272 CXXCastPath &BasePath) { 1273 // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class 1274 // type, can be converted to an rvalue of type "pointer to cv2 D", where D 1275 // is a class derived from B, if a valid standard conversion from "pointer 1276 // to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base 1277 // class of D. 1278 // In addition, DR54 clarifies that the base must be accessible in the 1279 // current context. 1280 1281 const PointerType *DestPointer = DestType->getAs<PointerType>(); 1282 if (!DestPointer) { 1283 return TC_NotApplicable; 1284 } 1285 1286 const PointerType *SrcPointer = SrcType->getAs<PointerType>(); 1287 if (!SrcPointer) { 1288 msg = diag::err_bad_static_cast_pointer_nonpointer; 1289 return TC_NotApplicable; 1290 } 1291 1292 return TryStaticDowncast(Self, 1293 Self.Context.getCanonicalType(SrcPointer->getPointeeType()), 1294 Self.Context.getCanonicalType(DestPointer->getPointeeType()), 1295 CStyle, OpRange, SrcType, DestType, msg, Kind, 1296 BasePath); 1297} 1298 1299/// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and 1300/// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to 1301/// DestType is possible and allowed. 1302TryCastResult 1303TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType, 1304 bool CStyle, SourceRange OpRange, QualType OrigSrcType, 1305 QualType OrigDestType, unsigned &msg, 1306 CastKind &Kind, CXXCastPath &BasePath) { 1307 // We can only work with complete types. But don't complain if it doesn't work 1308 if (!Self.isCompleteType(OpRange.getBegin(), SrcType) || 1309 !Self.isCompleteType(OpRange.getBegin(), DestType)) 1310 return TC_NotApplicable; 1311 1312 // Downcast can only happen in class hierarchies, so we need classes. 1313 if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) { 1314 return TC_NotApplicable; 1315 } 1316 1317 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1318 /*DetectVirtual=*/true); 1319 if (!Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths)) { 1320 return TC_NotApplicable; 1321 } 1322 1323 // Target type does derive from source type. Now we're serious. If an error 1324 // appears now, it's not ignored. 1325 // This may not be entirely in line with the standard. Take for example: 1326 // struct A {}; 1327 // struct B : virtual A { 1328 // B(A&); 1329 // }; 1330 // 1331 // void f() 1332 // { 1333 // (void)static_cast<const B&>(*((A*)0)); 1334 // } 1335 // As far as the standard is concerned, p5 does not apply (A is virtual), so 1336 // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid. 1337 // However, both GCC and Comeau reject this example, and accepting it would 1338 // mean more complex code if we're to preserve the nice error message. 1339 // FIXME: Being 100% compliant here would be nice to have. 1340 1341 // Must preserve cv, as always, unless we're in C-style mode. 1342 if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) { 1343 msg = diag::err_bad_cxx_cast_qualifiers_away; 1344 return TC_Failed; 1345 } 1346 1347 if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) { 1348 // This code is analoguous to that in CheckDerivedToBaseConversion, except 1349 // that it builds the paths in reverse order. 1350 // To sum up: record all paths to the base and build a nice string from 1351 // them. Use it to spice up the error message. 1352 if (!Paths.isRecordingPaths()) { 1353 Paths.clear(); 1354 Paths.setRecordingPaths(true); 1355 Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths); 1356 } 1357 std::string PathDisplayStr; 1358 std::set<unsigned> DisplayedPaths; 1359 for (clang::CXXBasePath &Path : Paths) { 1360 if (DisplayedPaths.insert(Path.back().SubobjectNumber).second) { 1361 // We haven't displayed a path to this particular base 1362 // class subobject yet. 1363 PathDisplayStr += "\n "; 1364 for (CXXBasePathElement &PE : llvm::reverse(Path)) 1365 PathDisplayStr += PE.Base->getType().getAsString() + " -> "; 1366 PathDisplayStr += QualType(DestType).getAsString(); 1367 } 1368 } 1369 1370 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast) 1371 << QualType(SrcType).getUnqualifiedType() 1372 << QualType(DestType).getUnqualifiedType() 1373 << PathDisplayStr << OpRange; 1374 msg = 0; 1375 return TC_Failed; 1376 } 1377 1378 if (Paths.getDetectedVirtual() != nullptr) { 1379 QualType VirtualBase(Paths.getDetectedVirtual(), 0); 1380 Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual) 1381 << OrigSrcType << OrigDestType << VirtualBase << OpRange; 1382 msg = 0; 1383 return TC_Failed; 1384 } 1385 1386 if (!CStyle) { 1387 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1388 SrcType, DestType, 1389 Paths.front(), 1390 diag::err_downcast_from_inaccessible_base)) { 1391 case Sema::AR_accessible: 1392 case Sema::AR_delayed: // be optimistic 1393 case Sema::AR_dependent: // be optimistic 1394 break; 1395 1396 case Sema::AR_inaccessible: 1397 msg = 0; 1398 return TC_Failed; 1399 } 1400 } 1401 1402 Self.BuildBasePathArray(Paths, BasePath); 1403 Kind = CK_BaseToDerived; 1404 return TC_Success; 1405} 1406 1407/// TryStaticMemberPointerUpcast - Tests whether a conversion according to 1408/// C++ 5.2.9p9 is valid: 1409/// 1410/// An rvalue of type "pointer to member of D of type cv1 T" can be 1411/// converted to an rvalue of type "pointer to member of B of type cv2 T", 1412/// where B is a base class of D [...]. 1413/// 1414TryCastResult 1415TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType, 1416 QualType DestType, bool CStyle, 1417 SourceRange OpRange, 1418 unsigned &msg, CastKind &Kind, 1419 CXXCastPath &BasePath) { 1420 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(); 1421 if (!DestMemPtr) 1422 return TC_NotApplicable; 1423 1424 bool WasOverloadedFunction = false; 1425 DeclAccessPair FoundOverload; 1426 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 1427 if (FunctionDecl *Fn 1428 = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false, 1429 FoundOverload)) { 1430 CXXMethodDecl *M = cast<CXXMethodDecl>(Fn); 1431 SrcType = Self.Context.getMemberPointerType(Fn->getType(), 1432 Self.Context.getTypeDeclType(M->getParent()).getTypePtr()); 1433 WasOverloadedFunction = true; 1434 } 1435 } 1436 1437 const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 1438 if (!SrcMemPtr) { 1439 msg = diag::err_bad_static_cast_member_pointer_nonmp; 1440 return TC_NotApplicable; 1441 } 1442 1443 // Lock down the inheritance model right now in MS ABI, whether or not the 1444 // pointee types are the same. 1445 if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) { 1446 (void)Self.isCompleteType(OpRange.getBegin(), SrcType); 1447 (void)Self.isCompleteType(OpRange.getBegin(), DestType); 1448 } 1449 1450 // T == T, modulo cv 1451 if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(), 1452 DestMemPtr->getPointeeType())) 1453 return TC_NotApplicable; 1454 1455 // B base of D 1456 QualType SrcClass(SrcMemPtr->getClass(), 0); 1457 QualType DestClass(DestMemPtr->getClass(), 0); 1458 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1459 /*DetectVirtual=*/true); 1460 if (!Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths)) 1461 return TC_NotApplicable; 1462 1463 // B is a base of D. But is it an allowed base? If not, it's a hard error. 1464 if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) { 1465 Paths.clear(); 1466 Paths.setRecordingPaths(true); 1467 bool StillOkay = 1468 Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths); 1469 assert(StillOkay); 1470 (void)StillOkay; 1471 std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths); 1472 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv) 1473 << 1 << SrcClass << DestClass << PathDisplayStr << OpRange; 1474 msg = 0; 1475 return TC_Failed; 1476 } 1477 1478 if (const RecordType *VBase = Paths.getDetectedVirtual()) { 1479 Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual) 1480 << SrcClass << DestClass << QualType(VBase, 0) << OpRange; 1481 msg = 0; 1482 return TC_Failed; 1483 } 1484 1485 if (!CStyle) { 1486 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1487 DestClass, SrcClass, 1488 Paths.front(), 1489 diag::err_upcast_to_inaccessible_base)) { 1490 case Sema::AR_accessible: 1491 case Sema::AR_delayed: 1492 case Sema::AR_dependent: 1493 // Optimistically assume that the delayed and dependent cases 1494 // will work out. 1495 break; 1496 1497 case Sema::AR_inaccessible: 1498 msg = 0; 1499 return TC_Failed; 1500 } 1501 } 1502 1503 if (WasOverloadedFunction) { 1504 // Resolve the address of the overloaded function again, this time 1505 // allowing complaints if something goes wrong. 1506 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 1507 DestType, 1508 true, 1509 FoundOverload); 1510 if (!Fn) { 1511 msg = 0; 1512 return TC_Failed; 1513 } 1514 1515 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn); 1516 if (!SrcExpr.isUsable()) { 1517 msg = 0; 1518 return TC_Failed; 1519 } 1520 } 1521 1522 Self.BuildBasePathArray(Paths, BasePath); 1523 Kind = CK_DerivedToBaseMemberPointer; 1524 return TC_Success; 1525} 1526 1527/// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2 1528/// is valid: 1529/// 1530/// An expression e can be explicitly converted to a type T using a 1531/// @c static_cast if the declaration "T t(e);" is well-formed [...]. 1532TryCastResult 1533TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, 1534 Sema::CheckedConversionKind CCK, 1535 SourceRange OpRange, unsigned &msg, 1536 CastKind &Kind, bool ListInitialization) { 1537 if (DestType->isRecordType()) { 1538 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 1539 diag::err_bad_dynamic_cast_incomplete) || 1540 Self.RequireNonAbstractType(OpRange.getBegin(), DestType, 1541 diag::err_allocation_of_abstract_type)) { 1542 msg = 0; 1543 return TC_Failed; 1544 } 1545 } 1546 1547 InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType); 1548 InitializationKind InitKind 1549 = (CCK == Sema::CCK_CStyleCast) 1550 ? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange, 1551 ListInitialization) 1552 : (CCK == Sema::CCK_FunctionalCast) 1553 ? InitializationKind::CreateFunctionalCast(OpRange, ListInitialization) 1554 : InitializationKind::CreateCast(OpRange); 1555 Expr *SrcExprRaw = SrcExpr.get(); 1556 // FIXME: Per DR242, we should check for an implicit conversion sequence 1557 // or for a constructor that could be invoked by direct-initialization 1558 // here, not for an initialization sequence. 1559 InitializationSequence InitSeq(Self, Entity, InitKind, SrcExprRaw); 1560 1561 // At this point of CheckStaticCast, if the destination is a reference, 1562 // or the expression is an overload expression this has to work. 1563 // There is no other way that works. 1564 // On the other hand, if we're checking a C-style cast, we've still got 1565 // the reinterpret_cast way. 1566 bool CStyle 1567 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 1568 if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType())) 1569 return TC_NotApplicable; 1570 1571 ExprResult Result = InitSeq.Perform(Self, Entity, InitKind, SrcExprRaw); 1572 if (Result.isInvalid()) { 1573 msg = 0; 1574 return TC_Failed; 1575 } 1576 1577 if (InitSeq.isConstructorInitialization()) 1578 Kind = CK_ConstructorConversion; 1579 else 1580 Kind = CK_NoOp; 1581 1582 SrcExpr = Result; 1583 return TC_Success; 1584} 1585 1586/// TryConstCast - See if a const_cast from source to destination is allowed, 1587/// and perform it if it is. 1588static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr, 1589 QualType DestType, bool CStyle, 1590 unsigned &msg) { 1591 DestType = Self.Context.getCanonicalType(DestType); 1592 QualType SrcType = SrcExpr.get()->getType(); 1593 bool NeedToMaterializeTemporary = false; 1594 1595 if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) { 1596 // C++11 5.2.11p4: 1597 // if a pointer to T1 can be explicitly converted to the type "pointer to 1598 // T2" using a const_cast, then the following conversions can also be 1599 // made: 1600 // -- an lvalue of type T1 can be explicitly converted to an lvalue of 1601 // type T2 using the cast const_cast<T2&>; 1602 // -- a glvalue of type T1 can be explicitly converted to an xvalue of 1603 // type T2 using the cast const_cast<T2&&>; and 1604 // -- if T1 is a class type, a prvalue of type T1 can be explicitly 1605 // converted to an xvalue of type T2 using the cast const_cast<T2&&>. 1606 1607 if (isa<LValueReferenceType>(DestTypeTmp) && !SrcExpr.get()->isLValue()) { 1608 // Cannot const_cast non-lvalue to lvalue reference type. But if this 1609 // is C-style, static_cast might find a way, so we simply suggest a 1610 // message and tell the parent to keep searching. 1611 msg = diag::err_bad_cxx_cast_rvalue; 1612 return TC_NotApplicable; 1613 } 1614 1615 if (isa<RValueReferenceType>(DestTypeTmp) && SrcExpr.get()->isRValue()) { 1616 if (!SrcType->isRecordType()) { 1617 // Cannot const_cast non-class prvalue to rvalue reference type. But if 1618 // this is C-style, static_cast can do this. 1619 msg = diag::err_bad_cxx_cast_rvalue; 1620 return TC_NotApplicable; 1621 } 1622 1623 // Materialize the class prvalue so that the const_cast can bind a 1624 // reference to it. 1625 NeedToMaterializeTemporary = true; 1626 } 1627 1628 // It's not completely clear under the standard whether we can 1629 // const_cast bit-field gl-values. Doing so would not be 1630 // intrinsically complicated, but for now, we say no for 1631 // consistency with other compilers and await the word of the 1632 // committee. 1633 if (SrcExpr.get()->refersToBitField()) { 1634 msg = diag::err_bad_cxx_cast_bitfield; 1635 return TC_NotApplicable; 1636 } 1637 1638 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 1639 SrcType = Self.Context.getPointerType(SrcType); 1640 } 1641 1642 // C++ 5.2.11p5: For a const_cast involving pointers to data members [...] 1643 // the rules for const_cast are the same as those used for pointers. 1644 1645 if (!DestType->isPointerType() && 1646 !DestType->isMemberPointerType() && 1647 !DestType->isObjCObjectPointerType()) { 1648 // Cannot cast to non-pointer, non-reference type. Note that, if DestType 1649 // was a reference type, we converted it to a pointer above. 1650 // The status of rvalue references isn't entirely clear, but it looks like 1651 // conversion to them is simply invalid. 1652 // C++ 5.2.11p3: For two pointer types [...] 1653 if (!CStyle) 1654 msg = diag::err_bad_const_cast_dest; 1655 return TC_NotApplicable; 1656 } 1657 if (DestType->isFunctionPointerType() || 1658 DestType->isMemberFunctionPointerType()) { 1659 // Cannot cast direct function pointers. 1660 // C++ 5.2.11p2: [...] where T is any object type or the void type [...] 1661 // T is the ultimate pointee of source and target type. 1662 if (!CStyle) 1663 msg = diag::err_bad_const_cast_dest; 1664 return TC_NotApplicable; 1665 } 1666 SrcType = Self.Context.getCanonicalType(SrcType); 1667 1668 // Unwrap the pointers. Ignore qualifiers. Terminate early if the types are 1669 // completely equal. 1670 // C++ 5.2.11p3 describes the core semantics of const_cast. All cv specifiers 1671 // in multi-level pointers may change, but the level count must be the same, 1672 // as must be the final pointee type. 1673 while (SrcType != DestType && 1674 Self.Context.UnwrapSimilarPointerTypes(SrcType, DestType)) { 1675 Qualifiers SrcQuals, DestQuals; 1676 SrcType = Self.Context.getUnqualifiedArrayType(SrcType, SrcQuals); 1677 DestType = Self.Context.getUnqualifiedArrayType(DestType, DestQuals); 1678 1679 // const_cast is permitted to strip cvr-qualifiers, only. Make sure that 1680 // the other qualifiers (e.g., address spaces) are identical. 1681 SrcQuals.removeCVRQualifiers(); 1682 DestQuals.removeCVRQualifiers(); 1683 if (SrcQuals != DestQuals) 1684 return TC_NotApplicable; 1685 } 1686 1687 // Since we're dealing in canonical types, the remainder must be the same. 1688 if (SrcType != DestType) 1689 return TC_NotApplicable; 1690 1691 if (NeedToMaterializeTemporary) 1692 // This is a const_cast from a class prvalue to an rvalue reference type. 1693 // Materialize a temporary to store the result of the conversion. 1694 SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcExpr.get()->getType(), 1695 SrcExpr.get(), 1696 /*IsLValueReference*/ false); 1697 1698 return TC_Success; 1699} 1700 1701// Checks for undefined behavior in reinterpret_cast. 1702// The cases that is checked for is: 1703// *reinterpret_cast<T*>(&a) 1704// reinterpret_cast<T&>(a) 1705// where accessing 'a' as type 'T' will result in undefined behavior. 1706void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType, 1707 bool IsDereference, 1708 SourceRange Range) { 1709 unsigned DiagID = IsDereference ? 1710 diag::warn_pointer_indirection_from_incompatible_type : 1711 diag::warn_undefined_reinterpret_cast; 1712 1713 if (Diags.isIgnored(DiagID, Range.getBegin())) 1714 return; 1715 1716 QualType SrcTy, DestTy; 1717 if (IsDereference) { 1718 if (!SrcType->getAs<PointerType>() || !DestType->getAs<PointerType>()) { 1719 return; 1720 } 1721 SrcTy = SrcType->getPointeeType(); 1722 DestTy = DestType->getPointeeType(); 1723 } else { 1724 if (!DestType->getAs<ReferenceType>()) { 1725 return; 1726 } 1727 SrcTy = SrcType; 1728 DestTy = DestType->getPointeeType(); 1729 } 1730 1731 // Cast is compatible if the types are the same. 1732 if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) { 1733 return; 1734 } 1735 // or one of the types is a char or void type 1736 if (DestTy->isAnyCharacterType() || DestTy->isVoidType() || 1737 SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) { 1738 return; 1739 } 1740 // or one of the types is a tag type. 1741 if (SrcTy->getAs<TagType>() || DestTy->getAs<TagType>()) { 1742 return; 1743 } 1744 1745 // FIXME: Scoped enums? 1746 if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) || 1747 (SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) { 1748 if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) { 1749 return; 1750 } 1751 } 1752 1753 Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range; 1754} 1755 1756static void DiagnoseCastOfObjCSEL(Sema &Self, const ExprResult &SrcExpr, 1757 QualType DestType) { 1758 QualType SrcType = SrcExpr.get()->getType(); 1759 if (Self.Context.hasSameType(SrcType, DestType)) 1760 return; 1761 if (const PointerType *SrcPtrTy = SrcType->getAs<PointerType>()) 1762 if (SrcPtrTy->isObjCSelType()) { 1763 QualType DT = DestType; 1764 if (isa<PointerType>(DestType)) 1765 DT = DestType->getPointeeType(); 1766 if (!DT.getUnqualifiedType()->isVoidType()) 1767 Self.Diag(SrcExpr.get()->getExprLoc(), 1768 diag::warn_cast_pointer_from_sel) 1769 << SrcType << DestType << SrcExpr.get()->getSourceRange(); 1770 } 1771} 1772 1773/// Diagnose casts that change the calling convention of a pointer to a function 1774/// defined in the current TU. 1775static void DiagnoseCallingConvCast(Sema &Self, const ExprResult &SrcExpr, 1776 QualType DstType, SourceRange OpRange) { 1777 // Check if this cast would change the calling convention of a function 1778 // pointer type. 1779 QualType SrcType = SrcExpr.get()->getType(); 1780 if (Self.Context.hasSameType(SrcType, DstType) || 1781 !SrcType->isFunctionPointerType() || !DstType->isFunctionPointerType()) 1782 return; 1783 const auto *SrcFTy = 1784 SrcType->castAs<PointerType>()->getPointeeType()->castAs<FunctionType>(); 1785 const auto *DstFTy = 1786 DstType->castAs<PointerType>()->getPointeeType()->castAs<FunctionType>(); 1787 CallingConv SrcCC = SrcFTy->getCallConv(); 1788 CallingConv DstCC = DstFTy->getCallConv(); 1789 if (SrcCC == DstCC) 1790 return; 1791 1792 // We have a calling convention cast. Check if the source is a pointer to a 1793 // known, specific function that has already been defined. 1794 Expr *Src = SrcExpr.get()->IgnoreParenImpCasts(); 1795 if (auto *UO = dyn_cast<UnaryOperator>(Src)) 1796 if (UO->getOpcode() == UO_AddrOf) 1797 Src = UO->getSubExpr()->IgnoreParenImpCasts(); 1798 auto *DRE = dyn_cast<DeclRefExpr>(Src); 1799 if (!DRE) 1800 return; 1801 auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl()); 1802 if (!FD) 1803 return; 1804 1805 // Only warn if we are casting from the default convention to a non-default 1806 // convention. This can happen when the programmer forgot to apply the calling 1807 // convention to the function declaration and then inserted this cast to 1808 // satisfy the type system. 1809 CallingConv DefaultCC = Self.getASTContext().getDefaultCallingConvention( 1810 FD->isVariadic(), FD->isCXXInstanceMember()); 1811 if (DstCC == DefaultCC || SrcCC != DefaultCC) 1812 return; 1813 1814 // Diagnose this cast, as it is probably bad. 1815 StringRef SrcCCName = FunctionType::getNameForCallConv(SrcCC); 1816 StringRef DstCCName = FunctionType::getNameForCallConv(DstCC); 1817 Self.Diag(OpRange.getBegin(), diag::warn_cast_calling_conv) 1818 << SrcCCName << DstCCName << OpRange; 1819 1820 // The checks above are cheaper than checking if the diagnostic is enabled. 1821 // However, it's worth checking if the warning is enabled before we construct 1822 // a fixit. 1823 if (Self.Diags.isIgnored(diag::warn_cast_calling_conv, OpRange.getBegin())) 1824 return; 1825 1826 // Try to suggest a fixit to change the calling convention of the function 1827 // whose address was taken. Try to use the latest macro for the convention. 1828 // For example, users probably want to write "WINAPI" instead of "__stdcall" 1829 // to match the Windows header declarations. 1830 SourceLocation NameLoc = FD->getFirstDecl()->getNameInfo().getLoc(); 1831 Preprocessor &PP = Self.getPreprocessor(); 1832 SmallVector<TokenValue, 6> AttrTokens; 1833 SmallString<64> CCAttrText; 1834 llvm::raw_svector_ostream OS(CCAttrText); 1835 if (Self.getLangOpts().MicrosoftExt) { 1836 // __stdcall or __vectorcall 1837 OS << "__" << DstCCName; 1838 IdentifierInfo *II = PP.getIdentifierInfo(OS.str()); 1839 AttrTokens.push_back(II->isKeyword(Self.getLangOpts()) 1840 ? TokenValue(II->getTokenID()) 1841 : TokenValue(II)); 1842 } else { 1843 // __attribute__((stdcall)) or __attribute__((vectorcall)) 1844 OS << "__attribute__((" << DstCCName << "))"; 1845 AttrTokens.push_back(tok::kw___attribute); 1846 AttrTokens.push_back(tok::l_paren); 1847 AttrTokens.push_back(tok::l_paren); 1848 IdentifierInfo *II = PP.getIdentifierInfo(DstCCName); 1849 AttrTokens.push_back(II->isKeyword(Self.getLangOpts()) 1850 ? TokenValue(II->getTokenID()) 1851 : TokenValue(II)); 1852 AttrTokens.push_back(tok::r_paren); 1853 AttrTokens.push_back(tok::r_paren); 1854 } 1855 StringRef AttrSpelling = PP.getLastMacroWithSpelling(NameLoc, AttrTokens); 1856 if (!AttrSpelling.empty()) 1857 CCAttrText = AttrSpelling; 1858 OS << ' '; 1859 Self.Diag(NameLoc, diag::note_change_calling_conv_fixit) 1860 << FD << DstCCName << FixItHint::CreateInsertion(NameLoc, CCAttrText); 1861} 1862 1863static void checkIntToPointerCast(bool CStyle, SourceLocation Loc, 1864 const Expr *SrcExpr, QualType DestType, 1865 Sema &Self) { 1866 QualType SrcType = SrcExpr->getType(); 1867 1868 // Not warning on reinterpret_cast, boolean, constant expressions, etc 1869 // are not explicit design choices, but consistent with GCC's behavior. 1870 // Feel free to modify them if you've reason/evidence for an alternative. 1871 if (CStyle && SrcType->isIntegralType(Self.Context) 1872 && !SrcType->isBooleanType() 1873 && !SrcType->isEnumeralType() 1874 && !SrcExpr->isIntegerConstantExpr(Self.Context) 1875 && Self.Context.getTypeSize(DestType) > 1876 Self.Context.getTypeSize(SrcType)) { 1877 // Separate between casts to void* and non-void* pointers. 1878 // Some APIs use (abuse) void* for something like a user context, 1879 // and often that value is an integer even if it isn't a pointer itself. 1880 // Having a separate warning flag allows users to control the warning 1881 // for their workflow. 1882 unsigned Diag = DestType->isVoidPointerType() ? 1883 diag::warn_int_to_void_pointer_cast 1884 : diag::warn_int_to_pointer_cast; 1885 Self.Diag(Loc, Diag) << SrcType << DestType; 1886 } 1887} 1888 1889static bool fixOverloadedReinterpretCastExpr(Sema &Self, QualType DestType, 1890 ExprResult &Result) { 1891 // We can only fix an overloaded reinterpret_cast if 1892 // - it is a template with explicit arguments that resolves to an lvalue 1893 // unambiguously, or 1894 // - it is the only function in an overload set that may have its address 1895 // taken. 1896 1897 Expr *E = Result.get(); 1898 // TODO: what if this fails because of DiagnoseUseOfDecl or something 1899 // like it? 1900 if (Self.ResolveAndFixSingleFunctionTemplateSpecialization( 1901 Result, 1902 Expr::getValueKindForType(DestType) == VK_RValue // Convert Fun to Ptr 1903 ) && 1904 Result.isUsable()) 1905 return true; 1906 1907 // No guarantees that ResolveAndFixSingleFunctionTemplateSpecialization 1908 // preserves Result. 1909 Result = E; 1910 if (!Self.resolveAndFixAddressOfOnlyViableOverloadCandidate( 1911 Result, /*DoFunctionPointerConversion=*/true)) 1912 return false; 1913 return Result.isUsable(); 1914} 1915 1916static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr, 1917 QualType DestType, bool CStyle, 1918 SourceRange OpRange, 1919 unsigned &msg, 1920 CastKind &Kind) { 1921 bool IsLValueCast = false; 1922 1923 DestType = Self.Context.getCanonicalType(DestType); 1924 QualType SrcType = SrcExpr.get()->getType(); 1925 1926 // Is the source an overloaded name? (i.e. &foo) 1927 // If so, reinterpret_cast generally can not help us here (13.4, p1, bullet 5) 1928 if (SrcType == Self.Context.OverloadTy) { 1929 ExprResult FixedExpr = SrcExpr; 1930 if (!fixOverloadedReinterpretCastExpr(Self, DestType, FixedExpr)) 1931 return TC_NotApplicable; 1932 1933 assert(FixedExpr.isUsable() && "Invalid result fixing overloaded expr"); 1934 SrcExpr = FixedExpr; 1935 SrcType = SrcExpr.get()->getType(); 1936 } 1937 1938 if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) { 1939 if (!SrcExpr.get()->isGLValue()) { 1940 // Cannot cast non-glvalue to (lvalue or rvalue) reference type. See the 1941 // similar comment in const_cast. 1942 msg = diag::err_bad_cxx_cast_rvalue; 1943 return TC_NotApplicable; 1944 } 1945 1946 if (!CStyle) { 1947 Self.CheckCompatibleReinterpretCast(SrcType, DestType, 1948 /*isDereference=*/false, OpRange); 1949 } 1950 1951 // C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the 1952 // same effect as the conversion *reinterpret_cast<T*>(&x) with the 1953 // built-in & and * operators. 1954 1955 const char *inappropriate = nullptr; 1956 switch (SrcExpr.get()->getObjectKind()) { 1957 case OK_Ordinary: 1958 break; 1959 case OK_BitField: 1960 msg = diag::err_bad_cxx_cast_bitfield; 1961 return TC_NotApplicable; 1962 // FIXME: Use a specific diagnostic for the rest of these cases. 1963 case OK_VectorComponent: inappropriate = "vector element"; break; 1964 case OK_ObjCProperty: inappropriate = "property expression"; break; 1965 case OK_ObjCSubscript: inappropriate = "container subscripting expression"; 1966 break; 1967 } 1968 if (inappropriate) { 1969 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference) 1970 << inappropriate << DestType 1971 << OpRange << SrcExpr.get()->getSourceRange(); 1972 msg = 0; SrcExpr = ExprError(); 1973 return TC_NotApplicable; 1974 } 1975 1976 // This code does this transformation for the checked types. 1977 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 1978 SrcType = Self.Context.getPointerType(SrcType); 1979 1980 IsLValueCast = true; 1981 } 1982 1983 // Canonicalize source for comparison. 1984 SrcType = Self.Context.getCanonicalType(SrcType); 1985 1986 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(), 1987 *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 1988 if (DestMemPtr && SrcMemPtr) { 1989 // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1" 1990 // can be explicitly converted to an rvalue of type "pointer to member 1991 // of Y of type T2" if T1 and T2 are both function types or both object 1992 // types. 1993 if (DestMemPtr->isMemberFunctionPointer() != 1994 SrcMemPtr->isMemberFunctionPointer()) 1995 return TC_NotApplicable; 1996 1997 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away 1998 // constness. 1999 // A reinterpret_cast followed by a const_cast can, though, so in C-style, 2000 // we accept it. 2001 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, 2002 /*CheckObjCLifetime=*/CStyle)) { 2003 msg = diag::err_bad_cxx_cast_qualifiers_away; 2004 return TC_Failed; 2005 } 2006 2007 if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) { 2008 // We need to determine the inheritance model that the class will use if 2009 // haven't yet. 2010 (void)Self.isCompleteType(OpRange.getBegin(), SrcType); 2011 (void)Self.isCompleteType(OpRange.getBegin(), DestType); 2012 } 2013 2014 // Don't allow casting between member pointers of different sizes. 2015 if (Self.Context.getTypeSize(DestMemPtr) != 2016 Self.Context.getTypeSize(SrcMemPtr)) { 2017 msg = diag::err_bad_cxx_cast_member_pointer_size; 2018 return TC_Failed; 2019 } 2020 2021 // A valid member pointer cast. 2022 assert(!IsLValueCast); 2023 Kind = CK_ReinterpretMemberPointer; 2024 return TC_Success; 2025 } 2026 2027 // See below for the enumeral issue. 2028 if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) { 2029 // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral 2030 // type large enough to hold it. A value of std::nullptr_t can be 2031 // converted to an integral type; the conversion has the same meaning 2032 // and validity as a conversion of (void*)0 to the integral type. 2033 if (Self.Context.getTypeSize(SrcType) > 2034 Self.Context.getTypeSize(DestType)) { 2035 msg = diag::err_bad_reinterpret_cast_small_int; 2036 return TC_Failed; 2037 } 2038 Kind = CK_PointerToIntegral; 2039 return TC_Success; 2040 } 2041 2042 // Allow reinterpret_casts between vectors of the same size and 2043 // between vectors and integers of the same size. 2044 bool destIsVector = DestType->isVectorType(); 2045 bool srcIsVector = SrcType->isVectorType(); 2046 if (srcIsVector || destIsVector) { 2047 // The non-vector type, if any, must have integral type. This is 2048 // the same rule that C vector casts use; note, however, that enum 2049 // types are not integral in C++. 2050 if ((!destIsVector && !DestType->isIntegralType(Self.Context)) || 2051 (!srcIsVector && !SrcType->isIntegralType(Self.Context))) 2052 return TC_NotApplicable; 2053 2054 // The size we want to consider is eltCount * eltSize. 2055 // That's exactly what the lax-conversion rules will check. 2056 if (Self.areLaxCompatibleVectorTypes(SrcType, DestType)) { 2057 Kind = CK_BitCast; 2058 return TC_Success; 2059 } 2060 2061 // Otherwise, pick a reasonable diagnostic. 2062 if (!destIsVector) 2063 msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size; 2064 else if (!srcIsVector) 2065 msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size; 2066 else 2067 msg = diag::err_bad_cxx_cast_vector_to_vector_different_size; 2068 2069 return TC_Failed; 2070 } 2071 2072 if (SrcType == DestType) { 2073 // C++ 5.2.10p2 has a note that mentions that, subject to all other 2074 // restrictions, a cast to the same type is allowed so long as it does not 2075 // cast away constness. In C++98, the intent was not entirely clear here, 2076 // since all other paragraphs explicitly forbid casts to the same type. 2077 // C++11 clarifies this case with p2. 2078 // 2079 // The only allowed types are: integral, enumeration, pointer, or 2080 // pointer-to-member types. We also won't restrict Obj-C pointers either. 2081 Kind = CK_NoOp; 2082 TryCastResult Result = TC_NotApplicable; 2083 if (SrcType->isIntegralOrEnumerationType() || 2084 SrcType->isAnyPointerType() || 2085 SrcType->isMemberPointerType() || 2086 SrcType->isBlockPointerType()) { 2087 Result = TC_Success; 2088 } 2089 return Result; 2090 } 2091 2092 bool destIsPtr = DestType->isAnyPointerType() || 2093 DestType->isBlockPointerType(); 2094 bool srcIsPtr = SrcType->isAnyPointerType() || 2095 SrcType->isBlockPointerType(); 2096 if (!destIsPtr && !srcIsPtr) { 2097 // Except for std::nullptr_t->integer and lvalue->reference, which are 2098 // handled above, at least one of the two arguments must be a pointer. 2099 return TC_NotApplicable; 2100 } 2101 2102 if (DestType->isIntegralType(Self.Context)) { 2103 assert(srcIsPtr && "One type must be a pointer"); 2104 // C++ 5.2.10p4: A pointer can be explicitly converted to any integral 2105 // type large enough to hold it; except in Microsoft mode, where the 2106 // integral type size doesn't matter (except we don't allow bool). 2107 bool MicrosoftException = Self.getLangOpts().MicrosoftExt && 2108 !DestType->isBooleanType(); 2109 if ((Self.Context.getTypeSize(SrcType) > 2110 Self.Context.getTypeSize(DestType)) && 2111 !MicrosoftException) { 2112 msg = diag::err_bad_reinterpret_cast_small_int; 2113 return TC_Failed; 2114 } 2115 Kind = CK_PointerToIntegral; 2116 return TC_Success; 2117 } 2118 2119 if (SrcType->isIntegralOrEnumerationType()) { 2120 assert(destIsPtr && "One type must be a pointer"); 2121 checkIntToPointerCast(CStyle, OpRange.getBegin(), SrcExpr.get(), DestType, 2122 Self); 2123 // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly 2124 // converted to a pointer. 2125 // C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not 2126 // necessarily converted to a null pointer value.] 2127 Kind = CK_IntegralToPointer; 2128 return TC_Success; 2129 } 2130 2131 if (!destIsPtr || !srcIsPtr) { 2132 // With the valid non-pointer conversions out of the way, we can be even 2133 // more stringent. 2134 return TC_NotApplicable; 2135 } 2136 2137 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness. 2138 // The C-style cast operator can. 2139 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, 2140 /*CheckObjCLifetime=*/CStyle)) { 2141 msg = diag::err_bad_cxx_cast_qualifiers_away; 2142 return TC_Failed; 2143 } 2144 2145 // Cannot convert between block pointers and Objective-C object pointers. 2146 if ((SrcType->isBlockPointerType() && DestType->isObjCObjectPointerType()) || 2147 (DestType->isBlockPointerType() && SrcType->isObjCObjectPointerType())) 2148 return TC_NotApplicable; 2149 2150 if (IsLValueCast) { 2151 Kind = CK_LValueBitCast; 2152 } else if (DestType->isObjCObjectPointerType()) { 2153 Kind = Self.PrepareCastToObjCObjectPointer(SrcExpr); 2154 } else if (DestType->isBlockPointerType()) { 2155 if (!SrcType->isBlockPointerType()) { 2156 Kind = CK_AnyPointerToBlockPointerCast; 2157 } else { 2158 Kind = CK_BitCast; 2159 } 2160 } else { 2161 Kind = CK_BitCast; 2162 } 2163 2164 // Any pointer can be cast to an Objective-C pointer type with a C-style 2165 // cast. 2166 if (CStyle && DestType->isObjCObjectPointerType()) { 2167 return TC_Success; 2168 } 2169 if (CStyle) 2170 DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType); 2171 2172 DiagnoseCallingConvCast(Self, SrcExpr, DestType, OpRange); 2173 2174 // Not casting away constness, so the only remaining check is for compatible 2175 // pointer categories. 2176 2177 if (SrcType->isFunctionPointerType()) { 2178 if (DestType->isFunctionPointerType()) { 2179 // C++ 5.2.10p6: A pointer to a function can be explicitly converted to 2180 // a pointer to a function of a different type. 2181 return TC_Success; 2182 } 2183 2184 // C++0x 5.2.10p8: Converting a pointer to a function into a pointer to 2185 // an object type or vice versa is conditionally-supported. 2186 // Compilers support it in C++03 too, though, because it's necessary for 2187 // casting the return value of dlsym() and GetProcAddress(). 2188 // FIXME: Conditionally-supported behavior should be configurable in the 2189 // TargetInfo or similar. 2190 Self.Diag(OpRange.getBegin(), 2191 Self.getLangOpts().CPlusPlus11 ? 2192 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj) 2193 << OpRange; 2194 return TC_Success; 2195 } 2196 2197 if (DestType->isFunctionPointerType()) { 2198 // See above. 2199 Self.Diag(OpRange.getBegin(), 2200 Self.getLangOpts().CPlusPlus11 ? 2201 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj) 2202 << OpRange; 2203 return TC_Success; 2204 } 2205 2206 // C++ 5.2.10p7: A pointer to an object can be explicitly converted to 2207 // a pointer to an object of different type. 2208 // Void pointers are not specified, but supported by every compiler out there. 2209 // So we finish by allowing everything that remains - it's got to be two 2210 // object pointers. 2211 return TC_Success; 2212} 2213 2214void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle, 2215 bool ListInitialization) { 2216 assert(Self.getLangOpts().CPlusPlus); 2217 2218 // Handle placeholders. 2219 if (isPlaceholder()) { 2220 // C-style casts can resolve __unknown_any types. 2221 if (claimPlaceholder(BuiltinType::UnknownAny)) { 2222 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 2223 SrcExpr.get(), Kind, 2224 ValueKind, BasePath); 2225 return; 2226 } 2227 2228 checkNonOverloadPlaceholders(); 2229 if (SrcExpr.isInvalid()) 2230 return; 2231 } 2232 2233 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 2234 // This test is outside everything else because it's the only case where 2235 // a non-lvalue-reference target type does not lead to decay. 2236 if (DestType->isVoidType()) { 2237 Kind = CK_ToVoid; 2238 2239 if (claimPlaceholder(BuiltinType::Overload)) { 2240 Self.ResolveAndFixSingleFunctionTemplateSpecialization( 2241 SrcExpr, /* Decay Function to ptr */ false, 2242 /* Complain */ true, DestRange, DestType, 2243 diag::err_bad_cstyle_cast_overload); 2244 if (SrcExpr.isInvalid()) 2245 return; 2246 } 2247 2248 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get()); 2249 return; 2250 } 2251 2252 // If the type is dependent, we won't do any other semantic analysis now. 2253 if (DestType->isDependentType() || SrcExpr.get()->isTypeDependent() || 2254 SrcExpr.get()->isValueDependent()) { 2255 assert(Kind == CK_Dependent); 2256 return; 2257 } 2258 2259 if (ValueKind == VK_RValue && !DestType->isRecordType() && 2260 !isPlaceholder(BuiltinType::Overload)) { 2261 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 2262 if (SrcExpr.isInvalid()) 2263 return; 2264 } 2265 2266 // AltiVec vector initialization with a single literal. 2267 if (const VectorType *vecTy = DestType->getAs<VectorType>()) 2268 if (vecTy->getVectorKind() == VectorType::AltiVecVector 2269 && (SrcExpr.get()->getType()->isIntegerType() 2270 || SrcExpr.get()->getType()->isFloatingType())) { 2271 Kind = CK_VectorSplat; 2272 SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get()); 2273 return; 2274 } 2275 2276 // C++ [expr.cast]p5: The conversions performed by 2277 // - a const_cast, 2278 // - a static_cast, 2279 // - a static_cast followed by a const_cast, 2280 // - a reinterpret_cast, or 2281 // - a reinterpret_cast followed by a const_cast, 2282 // can be performed using the cast notation of explicit type conversion. 2283 // [...] If a conversion can be interpreted in more than one of the ways 2284 // listed above, the interpretation that appears first in the list is used, 2285 // even if a cast resulting from that interpretation is ill-formed. 2286 // In plain language, this means trying a const_cast ... 2287 unsigned msg = diag::err_bad_cxx_cast_generic; 2288 TryCastResult tcr = TryConstCast(Self, SrcExpr, DestType, 2289 /*CStyle*/true, msg); 2290 if (SrcExpr.isInvalid()) 2291 return; 2292 if (tcr == TC_Success) 2293 Kind = CK_NoOp; 2294 2295 Sema::CheckedConversionKind CCK 2296 = FunctionalStyle? Sema::CCK_FunctionalCast 2297 : Sema::CCK_CStyleCast; 2298 if (tcr == TC_NotApplicable) { 2299 // ... or if that is not possible, a static_cast, ignoring const, ... 2300 tcr = TryStaticCast(Self, SrcExpr, DestType, CCK, OpRange, 2301 msg, Kind, BasePath, ListInitialization); 2302 if (SrcExpr.isInvalid()) 2303 return; 2304 2305 if (tcr == TC_NotApplicable) { 2306 // ... and finally a reinterpret_cast, ignoring const. 2307 tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/true, 2308 OpRange, msg, Kind); 2309 if (SrcExpr.isInvalid()) 2310 return; 2311 } 2312 } 2313 2314 if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() && 2315 tcr == TC_Success) 2316 checkObjCConversion(CCK); 2317 2318 if (tcr != TC_Success && msg != 0) { 2319 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 2320 DeclAccessPair Found; 2321 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 2322 DestType, 2323 /*Complain*/ true, 2324 Found); 2325 if (Fn) { 2326 // If DestType is a function type (not to be confused with the function 2327 // pointer type), it will be possible to resolve the function address, 2328 // but the type cast should be considered as failure. 2329 OverloadExpr *OE = OverloadExpr::find(SrcExpr.get()).Expression; 2330 Self.Diag(OpRange.getBegin(), diag::err_bad_cstyle_cast_overload) 2331 << OE->getName() << DestType << OpRange 2332 << OE->getQualifierLoc().getSourceRange(); 2333 Self.NoteAllOverloadCandidates(SrcExpr.get()); 2334 } 2335 } else { 2336 diagnoseBadCast(Self, msg, (FunctionalStyle ? CT_Functional : CT_CStyle), 2337 OpRange, SrcExpr.get(), DestType, ListInitialization); 2338 } 2339 } else if (Kind == CK_BitCast) { 2340 checkCastAlign(); 2341 } 2342 2343 // Clear out SrcExpr if there was a fatal error. 2344 if (tcr != TC_Success) 2345 SrcExpr = ExprError(); 2346} 2347 2348/// DiagnoseBadFunctionCast - Warn whenever a function call is cast to a 2349/// non-matching type. Such as enum function call to int, int call to 2350/// pointer; etc. Cast to 'void' is an exception. 2351static void DiagnoseBadFunctionCast(Sema &Self, const ExprResult &SrcExpr, 2352 QualType DestType) { 2353 if (Self.Diags.isIgnored(diag::warn_bad_function_cast, 2354 SrcExpr.get()->getExprLoc())) 2355 return; 2356 2357 if (!isa<CallExpr>(SrcExpr.get())) 2358 return; 2359 2360 QualType SrcType = SrcExpr.get()->getType(); 2361 if (DestType.getUnqualifiedType()->isVoidType()) 2362 return; 2363 if ((SrcType->isAnyPointerType() || SrcType->isBlockPointerType()) 2364 && (DestType->isAnyPointerType() || DestType->isBlockPointerType())) 2365 return; 2366 if (SrcType->isIntegerType() && DestType->isIntegerType() && 2367 (SrcType->isBooleanType() == DestType->isBooleanType()) && 2368 (SrcType->isEnumeralType() == DestType->isEnumeralType())) 2369 return; 2370 if (SrcType->isRealFloatingType() && DestType->isRealFloatingType()) 2371 return; 2372 if (SrcType->isEnumeralType() && DestType->isEnumeralType()) 2373 return; 2374 if (SrcType->isComplexType() && DestType->isComplexType()) 2375 return; 2376 if (SrcType->isComplexIntegerType() && DestType->isComplexIntegerType()) 2377 return; 2378 2379 Self.Diag(SrcExpr.get()->getExprLoc(), 2380 diag::warn_bad_function_cast) 2381 << SrcType << DestType << SrcExpr.get()->getSourceRange(); 2382} 2383 2384/// Check the semantics of a C-style cast operation, in C. 2385void CastOperation::CheckCStyleCast() { 2386 assert(!Self.getLangOpts().CPlusPlus); 2387 2388 // C-style casts can resolve __unknown_any types. 2389 if (claimPlaceholder(BuiltinType::UnknownAny)) { 2390 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 2391 SrcExpr.get(), Kind, 2392 ValueKind, BasePath); 2393 return; 2394 } 2395 2396 // C99 6.5.4p2: the cast type needs to be void or scalar and the expression 2397 // type needs to be scalar. 2398 if (DestType->isVoidType()) { 2399 // We don't necessarily do lvalue-to-rvalue conversions on this. 2400 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get()); 2401 if (SrcExpr.isInvalid()) 2402 return; 2403 2404 // Cast to void allows any expr type. 2405 Kind = CK_ToVoid; 2406 return; 2407 } 2408 2409 // Overloads are allowed with C extensions, so we need to support them. 2410 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 2411 DeclAccessPair DAP; 2412 if (FunctionDecl *FD = Self.ResolveAddressOfOverloadedFunction( 2413 SrcExpr.get(), DestType, /*Complain=*/true, DAP)) 2414 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr.get(), DAP, FD); 2415 else 2416 return; 2417 assert(SrcExpr.isUsable()); 2418 } 2419 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 2420 if (SrcExpr.isInvalid()) 2421 return; 2422 QualType SrcType = SrcExpr.get()->getType(); 2423 2424 assert(!SrcType->isPlaceholderType()); 2425 2426 // OpenCL v1 s6.5: Casting a pointer to address space A to a pointer to 2427 // address space B is illegal. 2428 if (Self.getLangOpts().OpenCL && DestType->isPointerType() && 2429 SrcType->isPointerType()) { 2430 const PointerType *DestPtr = DestType->getAs<PointerType>(); 2431 if (!DestPtr->isAddressSpaceOverlapping(*SrcType->getAs<PointerType>())) { 2432 Self.Diag(OpRange.getBegin(), 2433 diag::err_typecheck_incompatible_address_space) 2434 << SrcType << DestType << Sema::AA_Casting 2435 << SrcExpr.get()->getSourceRange(); 2436 SrcExpr = ExprError(); 2437 return; 2438 } 2439 } 2440 2441 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 2442 diag::err_typecheck_cast_to_incomplete)) { 2443 SrcExpr = ExprError(); 2444 return; 2445 } 2446 2447 if (!DestType->isScalarType() && !DestType->isVectorType()) { 2448 const RecordType *DestRecordTy = DestType->getAs<RecordType>(); 2449 2450 if (DestRecordTy && Self.Context.hasSameUnqualifiedType(DestType, SrcType)){ 2451 // GCC struct/union extension: allow cast to self. 2452 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_nonscalar) 2453 << DestType << SrcExpr.get()->getSourceRange(); 2454 Kind = CK_NoOp; 2455 return; 2456 } 2457 2458 // GCC's cast to union extension. 2459 if (DestRecordTy && DestRecordTy->getDecl()->isUnion()) { 2460 RecordDecl *RD = DestRecordTy->getDecl(); 2461 RecordDecl::field_iterator Field, FieldEnd; 2462 for (Field = RD->field_begin(), FieldEnd = RD->field_end(); 2463 Field != FieldEnd; ++Field) { 2464 if (Self.Context.hasSameUnqualifiedType(Field->getType(), SrcType) && 2465 !Field->isUnnamedBitfield()) { 2466 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union) 2467 << SrcExpr.get()->getSourceRange(); 2468 break; 2469 } 2470 } 2471 if (Field == FieldEnd) { 2472 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cast_to_union_no_type) 2473 << SrcType << SrcExpr.get()->getSourceRange(); 2474 SrcExpr = ExprError(); 2475 return; 2476 } 2477 Kind = CK_ToUnion; 2478 return; 2479 } 2480 2481 // OpenCL v2.0 s6.13.10 - Allow casts from '0' to event_t type. 2482 if (Self.getLangOpts().OpenCL && DestType->isEventT()) { 2483 llvm::APSInt CastInt; 2484 if (SrcExpr.get()->EvaluateAsInt(CastInt, Self.Context)) { 2485 if (0 == CastInt) { 2486 Kind = CK_ZeroToOCLEvent; 2487 return; 2488 } 2489 Self.Diag(OpRange.getBegin(), 2490 diag::err_opencl_cast_non_zero_to_event_t) 2491 << CastInt.toString(10) << SrcExpr.get()->getSourceRange(); 2492 SrcExpr = ExprError(); 2493 return; 2494 } 2495 } 2496 2497 // Reject any other conversions to non-scalar types. 2498 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cond_expect_scalar) 2499 << DestType << SrcExpr.get()->getSourceRange(); 2500 SrcExpr = ExprError(); 2501 return; 2502 } 2503 2504 // The type we're casting to is known to be a scalar or vector. 2505 2506 // Require the operand to be a scalar or vector. 2507 if (!SrcType->isScalarType() && !SrcType->isVectorType()) { 2508 Self.Diag(SrcExpr.get()->getExprLoc(), 2509 diag::err_typecheck_expect_scalar_operand) 2510 << SrcType << SrcExpr.get()->getSourceRange(); 2511 SrcExpr = ExprError(); 2512 return; 2513 } 2514 2515 if (DestType->isExtVectorType()) { 2516 SrcExpr = Self.CheckExtVectorCast(OpRange, DestType, SrcExpr.get(), Kind); 2517 return; 2518 } 2519 2520 if (const VectorType *DestVecTy = DestType->getAs<VectorType>()) { 2521 if (DestVecTy->getVectorKind() == VectorType::AltiVecVector && 2522 (SrcType->isIntegerType() || SrcType->isFloatingType())) { 2523 Kind = CK_VectorSplat; 2524 SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get()); 2525 } else if (Self.CheckVectorCast(OpRange, DestType, SrcType, Kind)) { 2526 SrcExpr = ExprError(); 2527 } 2528 return; 2529 } 2530 2531 if (SrcType->isVectorType()) { 2532 if (Self.CheckVectorCast(OpRange, SrcType, DestType, Kind)) 2533 SrcExpr = ExprError(); 2534 return; 2535 } 2536 2537 // The source and target types are both scalars, i.e. 2538 // - arithmetic types (fundamental, enum, and complex) 2539 // - all kinds of pointers 2540 // Note that member pointers were filtered out with C++, above. 2541 2542 if (isa<ObjCSelectorExpr>(SrcExpr.get())) { 2543 Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_selector_expr); 2544 SrcExpr = ExprError(); 2545 return; 2546 } 2547 2548 // If either type is a pointer, the other type has to be either an 2549 // integer or a pointer. 2550 if (!DestType->isArithmeticType()) { 2551 if (!SrcType->isIntegralType(Self.Context) && SrcType->isArithmeticType()) { 2552 Self.Diag(SrcExpr.get()->getExprLoc(), 2553 diag::err_cast_pointer_from_non_pointer_int) 2554 << SrcType << SrcExpr.get()->getSourceRange(); 2555 SrcExpr = ExprError(); 2556 return; 2557 } 2558 checkIntToPointerCast(/* CStyle */ true, OpRange.getBegin(), SrcExpr.get(), 2559 DestType, Self); 2560 } else if (!SrcType->isArithmeticType()) { 2561 if (!DestType->isIntegralType(Self.Context) && 2562 DestType->isArithmeticType()) { 2563 Self.Diag(SrcExpr.get()->getLocStart(), 2564 diag::err_cast_pointer_to_non_pointer_int) 2565 << DestType << SrcExpr.get()->getSourceRange(); 2566 SrcExpr = ExprError(); 2567 return; 2568 } 2569 } 2570 2571 if (Self.getLangOpts().OpenCL && 2572 !Self.getOpenCLOptions().isEnabled("cl_khr_fp16")) { 2573 if (DestType->isHalfType()) { 2574 Self.Diag(SrcExpr.get()->getLocStart(), diag::err_opencl_cast_to_half) 2575 << DestType << SrcExpr.get()->getSourceRange(); 2576 SrcExpr = ExprError(); 2577 return; 2578 } 2579 } 2580 2581 // ARC imposes extra restrictions on casts. 2582 if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()) { 2583 checkObjCConversion(Sema::CCK_CStyleCast); 2584 if (SrcExpr.isInvalid()) 2585 return; 2586 2587 const PointerType *CastPtr = DestType->getAs<PointerType>(); 2588 if (Self.getLangOpts().ObjCAutoRefCount && CastPtr) { 2589 if (const PointerType *ExprPtr = SrcType->getAs<PointerType>()) { 2590 Qualifiers CastQuals = CastPtr->getPointeeType().getQualifiers(); 2591 Qualifiers ExprQuals = ExprPtr->getPointeeType().getQualifiers(); 2592 if (CastPtr->getPointeeType()->isObjCLifetimeType() && 2593 ExprPtr->getPointeeType()->isObjCLifetimeType() && 2594 !CastQuals.compatiblyIncludesObjCLifetime(ExprQuals)) { 2595 Self.Diag(SrcExpr.get()->getLocStart(), 2596 diag::err_typecheck_incompatible_ownership) 2597 << SrcType << DestType << Sema::AA_Casting 2598 << SrcExpr.get()->getSourceRange(); 2599 return; 2600 } 2601 } 2602 } 2603 else if (!Self.CheckObjCARCUnavailableWeakConversion(DestType, SrcType)) { 2604 Self.Diag(SrcExpr.get()->getLocStart(), 2605 diag::err_arc_convesion_of_weak_unavailable) 2606 << 1 << SrcType << DestType << SrcExpr.get()->getSourceRange(); 2607 SrcExpr = ExprError(); 2608 return; 2609 } 2610 } 2611 2612 DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType); 2613 DiagnoseCallingConvCast(Self, SrcExpr, DestType, OpRange); 2614 DiagnoseBadFunctionCast(Self, SrcExpr, DestType); 2615 Kind = Self.PrepareScalarCast(SrcExpr, DestType); 2616 if (SrcExpr.isInvalid()) 2617 return; 2618 2619 if (Kind == CK_BitCast) 2620 checkCastAlign(); 2621} 2622 2623/// DiagnoseCastQual - Warn whenever casts discards a qualifiers, be it either 2624/// const, volatile or both. 2625static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr, 2626 QualType DestType) { 2627 if (SrcExpr.isInvalid()) 2628 return; 2629 2630 QualType SrcType = SrcExpr.get()->getType(); 2631 if (!((SrcType->isAnyPointerType() && DestType->isAnyPointerType()) || 2632 DestType->isLValueReferenceType())) 2633 return; 2634 2635 QualType TheOffendingSrcType, TheOffendingDestType; 2636 Qualifiers CastAwayQualifiers; 2637 if (!CastsAwayConstness(Self, SrcType, DestType, true, false, 2638 &TheOffendingSrcType, &TheOffendingDestType, 2639 &CastAwayQualifiers)) 2640 return; 2641 2642 int qualifiers = -1; 2643 if (CastAwayQualifiers.hasConst() && CastAwayQualifiers.hasVolatile()) { 2644 qualifiers = 0; 2645 } else if (CastAwayQualifiers.hasConst()) { 2646 qualifiers = 1; 2647 } else if (CastAwayQualifiers.hasVolatile()) { 2648 qualifiers = 2; 2649 } 2650 // This is a variant of int **x; const int **y = (const int **)x; 2651 if (qualifiers == -1) 2652 Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual2) 2653 << SrcType << DestType; 2654 else 2655 Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual) 2656 << TheOffendingSrcType << TheOffendingDestType << qualifiers; 2657} 2658 2659ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc, 2660 TypeSourceInfo *CastTypeInfo, 2661 SourceLocation RPLoc, 2662 Expr *CastExpr) { 2663 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr); 2664 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2665 Op.OpRange = SourceRange(LPLoc, CastExpr->getLocEnd()); 2666 2667 if (getLangOpts().CPlusPlus) { 2668 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/ false, 2669 isa<InitListExpr>(CastExpr)); 2670 } else { 2671 Op.CheckCStyleCast(); 2672 } 2673 2674 if (Op.SrcExpr.isInvalid()) 2675 return ExprError(); 2676 2677 // -Wcast-qual 2678 DiagnoseCastQual(Op.Self, Op.SrcExpr, Op.DestType); 2679 2680 return Op.complete(CStyleCastExpr::Create(Context, Op.ResultType, 2681 Op.ValueKind, Op.Kind, Op.SrcExpr.get(), 2682 &Op.BasePath, CastTypeInfo, LPLoc, RPLoc)); 2683} 2684 2685ExprResult Sema::BuildCXXFunctionalCastExpr(TypeSourceInfo *CastTypeInfo, 2686 QualType Type, 2687 SourceLocation LPLoc, 2688 Expr *CastExpr, 2689 SourceLocation RPLoc) { 2690 assert(LPLoc.isValid() && "List-initialization shouldn't get here."); 2691 CastOperation Op(*this, Type, CastExpr); 2692 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2693 Op.OpRange = SourceRange(Op.DestRange.getBegin(), CastExpr->getLocEnd()); 2694 2695 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/true, /*ListInit=*/false); 2696 if (Op.SrcExpr.isInvalid()) 2697 return ExprError(); 2698 2699 auto *SubExpr = Op.SrcExpr.get(); 2700 if (auto *BindExpr = dyn_cast<CXXBindTemporaryExpr>(SubExpr)) 2701 SubExpr = BindExpr->getSubExpr(); 2702 if (auto *ConstructExpr = dyn_cast<CXXConstructExpr>(SubExpr)) 2703 ConstructExpr->setParenOrBraceRange(SourceRange(LPLoc, RPLoc)); 2704 2705 return Op.complete(CXXFunctionalCastExpr::Create(Context, Op.ResultType, 2706 Op.ValueKind, CastTypeInfo, Op.Kind, 2707 Op.SrcExpr.get(), &Op.BasePath, LPLoc, RPLoc)); 2708} 2709