SemaCast.cpp revision 353358
1//===--- SemaCast.cpp - Semantic Analysis for Casts -----------------------===// 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 7//===----------------------------------------------------------------------===// 8// 9// This file implements semantic analysis for cast expressions, including 10// 1) C-style casts like '(int) x' 11// 2) C++ functional casts like 'int(x)' 12// 3) C++ named casts like 'static_cast<int>(x)' 13// 14//===----------------------------------------------------------------------===// 15 16#include "clang/Sema/SemaInternal.h" 17#include "clang/AST/ASTContext.h" 18#include "clang/AST/CXXInheritance.h" 19#include "clang/AST/ExprCXX.h" 20#include "clang/AST/ExprObjC.h" 21#include "clang/AST/RecordLayout.h" 22#include "clang/Basic/PartialDiagnostic.h" 23#include "clang/Basic/TargetInfo.h" 24#include "clang/Lex/Preprocessor.h" 25#include "clang/Sema/Initialization.h" 26#include "llvm/ADT/SmallVector.h" 27#include <set> 28using namespace clang; 29 30 31 32enum TryCastResult { 33 TC_NotApplicable, ///< The cast method is not applicable. 34 TC_Success, ///< The cast method is appropriate and successful. 35 TC_Extension, ///< The cast method is appropriate and accepted as a 36 ///< language extension. 37 TC_Failed ///< The cast method is appropriate, but failed. A 38 ///< diagnostic has been emitted. 39}; 40 41static bool isValidCast(TryCastResult TCR) { 42 return TCR == TC_Success || TCR == TC_Extension; 43} 44 45enum CastType { 46 CT_Const, ///< const_cast 47 CT_Static, ///< static_cast 48 CT_Reinterpret, ///< reinterpret_cast 49 CT_Dynamic, ///< dynamic_cast 50 CT_CStyle, ///< (Type)expr 51 CT_Functional ///< Type(expr) 52}; 53 54namespace { 55 struct CastOperation { 56 CastOperation(Sema &S, QualType destType, ExprResult src) 57 : Self(S), SrcExpr(src), DestType(destType), 58 ResultType(destType.getNonLValueExprType(S.Context)), 59 ValueKind(Expr::getValueKindForType(destType)), 60 Kind(CK_Dependent), IsARCUnbridgedCast(false) { 61 62 if (const BuiltinType *placeholder = 63 src.get()->getType()->getAsPlaceholderType()) { 64 PlaceholderKind = placeholder->getKind(); 65 } else { 66 PlaceholderKind = (BuiltinType::Kind) 0; 67 } 68 } 69 70 Sema &Self; 71 ExprResult SrcExpr; 72 QualType DestType; 73 QualType ResultType; 74 ExprValueKind ValueKind; 75 CastKind Kind; 76 BuiltinType::Kind PlaceholderKind; 77 CXXCastPath BasePath; 78 bool IsARCUnbridgedCast; 79 80 SourceRange OpRange; 81 SourceRange DestRange; 82 83 // Top-level semantics-checking routines. 84 void CheckConstCast(); 85 void CheckReinterpretCast(); 86 void CheckStaticCast(); 87 void CheckDynamicCast(); 88 void CheckCXXCStyleCast(bool FunctionalCast, bool ListInitialization); 89 void CheckCStyleCast(); 90 void CheckBuiltinBitCast(); 91 92 void updatePartOfExplicitCastFlags(CastExpr *CE) { 93 // Walk down from the CE to the OrigSrcExpr, and mark all immediate 94 // ImplicitCastExpr's as being part of ExplicitCastExpr. The original CE 95 // (which is a ExplicitCastExpr), and the OrigSrcExpr are not touched. 96 for (; auto *ICE = dyn_cast<ImplicitCastExpr>(CE->getSubExpr()); CE = ICE) 97 ICE->setIsPartOfExplicitCast(true); 98 } 99 100 /// Complete an apparently-successful cast operation that yields 101 /// the given expression. 102 ExprResult complete(CastExpr *castExpr) { 103 // If this is an unbridged cast, wrap the result in an implicit 104 // cast that yields the unbridged-cast placeholder type. 105 if (IsARCUnbridgedCast) { 106 castExpr = ImplicitCastExpr::Create(Self.Context, 107 Self.Context.ARCUnbridgedCastTy, 108 CK_Dependent, castExpr, nullptr, 109 castExpr->getValueKind()); 110 } 111 updatePartOfExplicitCastFlags(castExpr); 112 return castExpr; 113 } 114 115 // Internal convenience methods. 116 117 /// Try to handle the given placeholder expression kind. Return 118 /// true if the source expression has the appropriate placeholder 119 /// kind. A placeholder can only be claimed once. 120 bool claimPlaceholder(BuiltinType::Kind K) { 121 if (PlaceholderKind != K) return false; 122 123 PlaceholderKind = (BuiltinType::Kind) 0; 124 return true; 125 } 126 127 bool isPlaceholder() const { 128 return PlaceholderKind != 0; 129 } 130 bool isPlaceholder(BuiltinType::Kind K) const { 131 return PlaceholderKind == K; 132 } 133 134 // Language specific cast restrictions for address spaces. 135 void checkAddressSpaceCast(QualType SrcType, QualType DestType); 136 137 void checkCastAlign() { 138 Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange); 139 } 140 141 void checkObjCConversion(Sema::CheckedConversionKind CCK) { 142 assert(Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()); 143 144 Expr *src = SrcExpr.get(); 145 if (Self.CheckObjCConversion(OpRange, DestType, src, CCK) == 146 Sema::ACR_unbridged) 147 IsARCUnbridgedCast = true; 148 SrcExpr = src; 149 } 150 151 /// Check for and handle non-overload placeholder expressions. 152 void checkNonOverloadPlaceholders() { 153 if (!isPlaceholder() || isPlaceholder(BuiltinType::Overload)) 154 return; 155 156 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get()); 157 if (SrcExpr.isInvalid()) 158 return; 159 PlaceholderKind = (BuiltinType::Kind) 0; 160 } 161 }; 162} 163 164static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr, 165 QualType DestType); 166 167// The Try functions attempt a specific way of casting. If they succeed, they 168// return TC_Success. If their way of casting is not appropriate for the given 169// arguments, they return TC_NotApplicable and *may* set diag to a diagnostic 170// to emit if no other way succeeds. If their way of casting is appropriate but 171// fails, they return TC_Failed and *must* set diag; they can set it to 0 if 172// they emit a specialized diagnostic. 173// All diagnostics returned by these functions must expect the same three 174// arguments: 175// %0: Cast Type (a value from the CastType enumeration) 176// %1: Source Type 177// %2: Destination Type 178static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, 179 QualType DestType, bool CStyle, 180 CastKind &Kind, 181 CXXCastPath &BasePath, 182 unsigned &msg); 183static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, 184 QualType DestType, bool CStyle, 185 SourceRange OpRange, 186 unsigned &msg, 187 CastKind &Kind, 188 CXXCastPath &BasePath); 189static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType, 190 QualType DestType, bool CStyle, 191 SourceRange OpRange, 192 unsigned &msg, 193 CastKind &Kind, 194 CXXCastPath &BasePath); 195static TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType, 196 CanQualType DestType, bool CStyle, 197 SourceRange OpRange, 198 QualType OrigSrcType, 199 QualType OrigDestType, unsigned &msg, 200 CastKind &Kind, 201 CXXCastPath &BasePath); 202static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, 203 QualType SrcType, 204 QualType DestType,bool CStyle, 205 SourceRange OpRange, 206 unsigned &msg, 207 CastKind &Kind, 208 CXXCastPath &BasePath); 209 210static TryCastResult TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, 211 QualType DestType, 212 Sema::CheckedConversionKind CCK, 213 SourceRange OpRange, 214 unsigned &msg, CastKind &Kind, 215 bool ListInitialization); 216static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, 217 QualType DestType, 218 Sema::CheckedConversionKind CCK, 219 SourceRange OpRange, 220 unsigned &msg, CastKind &Kind, 221 CXXCastPath &BasePath, 222 bool ListInitialization); 223static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr, 224 QualType DestType, bool CStyle, 225 unsigned &msg); 226static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr, 227 QualType DestType, bool CStyle, 228 SourceRange OpRange, 229 unsigned &msg, 230 CastKind &Kind); 231 232 233/// ActOnCXXNamedCast - Parse {dynamic,static,reinterpret,const}_cast's. 234ExprResult 235Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind, 236 SourceLocation LAngleBracketLoc, Declarator &D, 237 SourceLocation RAngleBracketLoc, 238 SourceLocation LParenLoc, Expr *E, 239 SourceLocation RParenLoc) { 240 241 assert(!D.isInvalidType()); 242 243 TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, E->getType()); 244 if (D.isInvalidType()) 245 return ExprError(); 246 247 if (getLangOpts().CPlusPlus) { 248 // Check that there are no default arguments (C++ only). 249 CheckExtraCXXDefaultArguments(D); 250 } 251 252 return BuildCXXNamedCast(OpLoc, Kind, TInfo, E, 253 SourceRange(LAngleBracketLoc, RAngleBracketLoc), 254 SourceRange(LParenLoc, RParenLoc)); 255} 256 257ExprResult 258Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind, 259 TypeSourceInfo *DestTInfo, Expr *E, 260 SourceRange AngleBrackets, SourceRange Parens) { 261 ExprResult Ex = E; 262 QualType DestType = DestTInfo->getType(); 263 264 // If the type is dependent, we won't do the semantic analysis now. 265 bool TypeDependent = 266 DestType->isDependentType() || Ex.get()->isTypeDependent(); 267 268 CastOperation Op(*this, DestType, E); 269 Op.OpRange = SourceRange(OpLoc, Parens.getEnd()); 270 Op.DestRange = AngleBrackets; 271 272 switch (Kind) { 273 default: llvm_unreachable("Unknown C++ cast!"); 274 275 case tok::kw_const_cast: 276 if (!TypeDependent) { 277 Op.CheckConstCast(); 278 if (Op.SrcExpr.isInvalid()) 279 return ExprError(); 280 DiscardMisalignedMemberAddress(DestType.getTypePtr(), E); 281 } 282 return Op.complete(CXXConstCastExpr::Create(Context, Op.ResultType, 283 Op.ValueKind, Op.SrcExpr.get(), DestTInfo, 284 OpLoc, Parens.getEnd(), 285 AngleBrackets)); 286 287 case tok::kw_dynamic_cast: { 288 // dynamic_cast is not supported in C++ for OpenCL. 289 if (getLangOpts().OpenCLCPlusPlus) { 290 return ExprError(Diag(OpLoc, diag::err_openclcxx_not_supported) 291 << "dynamic_cast"); 292 } 293 294 if (!TypeDependent) { 295 Op.CheckDynamicCast(); 296 if (Op.SrcExpr.isInvalid()) 297 return ExprError(); 298 } 299 return Op.complete(CXXDynamicCastExpr::Create(Context, Op.ResultType, 300 Op.ValueKind, Op.Kind, Op.SrcExpr.get(), 301 &Op.BasePath, DestTInfo, 302 OpLoc, Parens.getEnd(), 303 AngleBrackets)); 304 } 305 case tok::kw_reinterpret_cast: { 306 if (!TypeDependent) { 307 Op.CheckReinterpretCast(); 308 if (Op.SrcExpr.isInvalid()) 309 return ExprError(); 310 DiscardMisalignedMemberAddress(DestType.getTypePtr(), E); 311 } 312 return Op.complete(CXXReinterpretCastExpr::Create(Context, Op.ResultType, 313 Op.ValueKind, Op.Kind, Op.SrcExpr.get(), 314 nullptr, DestTInfo, OpLoc, 315 Parens.getEnd(), 316 AngleBrackets)); 317 } 318 case tok::kw_static_cast: { 319 if (!TypeDependent) { 320 Op.CheckStaticCast(); 321 if (Op.SrcExpr.isInvalid()) 322 return ExprError(); 323 DiscardMisalignedMemberAddress(DestType.getTypePtr(), E); 324 } 325 326 return Op.complete(CXXStaticCastExpr::Create(Context, Op.ResultType, 327 Op.ValueKind, Op.Kind, Op.SrcExpr.get(), 328 &Op.BasePath, DestTInfo, 329 OpLoc, Parens.getEnd(), 330 AngleBrackets)); 331 } 332 } 333} 334 335ExprResult Sema::ActOnBuiltinBitCastExpr(SourceLocation KWLoc, Declarator &D, 336 ExprResult Operand, 337 SourceLocation RParenLoc) { 338 assert(!D.isInvalidType()); 339 340 TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, Operand.get()->getType()); 341 if (D.isInvalidType()) 342 return ExprError(); 343 344 return BuildBuiltinBitCastExpr(KWLoc, TInfo, Operand.get(), RParenLoc); 345} 346 347ExprResult Sema::BuildBuiltinBitCastExpr(SourceLocation KWLoc, 348 TypeSourceInfo *TSI, Expr *Operand, 349 SourceLocation RParenLoc) { 350 CastOperation Op(*this, TSI->getType(), Operand); 351 Op.OpRange = SourceRange(KWLoc, RParenLoc); 352 TypeLoc TL = TSI->getTypeLoc(); 353 Op.DestRange = SourceRange(TL.getBeginLoc(), TL.getEndLoc()); 354 355 if (!Operand->isTypeDependent() && !TSI->getType()->isDependentType()) { 356 Op.CheckBuiltinBitCast(); 357 if (Op.SrcExpr.isInvalid()) 358 return ExprError(); 359 } 360 361 BuiltinBitCastExpr *BCE = 362 new (Context) BuiltinBitCastExpr(Op.ResultType, Op.ValueKind, Op.Kind, 363 Op.SrcExpr.get(), TSI, KWLoc, RParenLoc); 364 return Op.complete(BCE); 365} 366 367/// Try to diagnose a failed overloaded cast. Returns true if 368/// diagnostics were emitted. 369static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT, 370 SourceRange range, Expr *src, 371 QualType destType, 372 bool listInitialization) { 373 switch (CT) { 374 // These cast kinds don't consider user-defined conversions. 375 case CT_Const: 376 case CT_Reinterpret: 377 case CT_Dynamic: 378 return false; 379 380 // These do. 381 case CT_Static: 382 case CT_CStyle: 383 case CT_Functional: 384 break; 385 } 386 387 QualType srcType = src->getType(); 388 if (!destType->isRecordType() && !srcType->isRecordType()) 389 return false; 390 391 InitializedEntity entity = InitializedEntity::InitializeTemporary(destType); 392 InitializationKind initKind 393 = (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(), 394 range, listInitialization) 395 : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range, 396 listInitialization) 397 : InitializationKind::CreateCast(/*type range?*/ range); 398 InitializationSequence sequence(S, entity, initKind, src); 399 400 assert(sequence.Failed() && "initialization succeeded on second try?"); 401 switch (sequence.getFailureKind()) { 402 default: return false; 403 404 case InitializationSequence::FK_ConstructorOverloadFailed: 405 case InitializationSequence::FK_UserConversionOverloadFailed: 406 break; 407 } 408 409 OverloadCandidateSet &candidates = sequence.getFailedCandidateSet(); 410 411 unsigned msg = 0; 412 OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates; 413 414 switch (sequence.getFailedOverloadResult()) { 415 case OR_Success: llvm_unreachable("successful failed overload"); 416 case OR_No_Viable_Function: 417 if (candidates.empty()) 418 msg = diag::err_ovl_no_conversion_in_cast; 419 else 420 msg = diag::err_ovl_no_viable_conversion_in_cast; 421 howManyCandidates = OCD_AllCandidates; 422 break; 423 424 case OR_Ambiguous: 425 msg = diag::err_ovl_ambiguous_conversion_in_cast; 426 howManyCandidates = OCD_ViableCandidates; 427 break; 428 429 case OR_Deleted: 430 msg = diag::err_ovl_deleted_conversion_in_cast; 431 howManyCandidates = OCD_ViableCandidates; 432 break; 433 } 434 435 candidates.NoteCandidates( 436 PartialDiagnosticAt(range.getBegin(), 437 S.PDiag(msg) << CT << srcType << destType << range 438 << src->getSourceRange()), 439 S, howManyCandidates, src); 440 441 return true; 442} 443 444/// Diagnose a failed cast. 445static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType, 446 SourceRange opRange, Expr *src, QualType destType, 447 bool listInitialization) { 448 if (msg == diag::err_bad_cxx_cast_generic && 449 tryDiagnoseOverloadedCast(S, castType, opRange, src, destType, 450 listInitialization)) 451 return; 452 453 S.Diag(opRange.getBegin(), msg) << castType 454 << src->getType() << destType << opRange << src->getSourceRange(); 455 456 // Detect if both types are (ptr to) class, and note any incompleteness. 457 int DifferentPtrness = 0; 458 QualType From = destType; 459 if (auto Ptr = From->getAs<PointerType>()) { 460 From = Ptr->getPointeeType(); 461 DifferentPtrness++; 462 } 463 QualType To = src->getType(); 464 if (auto Ptr = To->getAs<PointerType>()) { 465 To = Ptr->getPointeeType(); 466 DifferentPtrness--; 467 } 468 if (!DifferentPtrness) { 469 auto RecFrom = From->getAs<RecordType>(); 470 auto RecTo = To->getAs<RecordType>(); 471 if (RecFrom && RecTo) { 472 auto DeclFrom = RecFrom->getAsCXXRecordDecl(); 473 if (!DeclFrom->isCompleteDefinition()) 474 S.Diag(DeclFrom->getLocation(), diag::note_type_incomplete) 475 << DeclFrom->getDeclName(); 476 auto DeclTo = RecTo->getAsCXXRecordDecl(); 477 if (!DeclTo->isCompleteDefinition()) 478 S.Diag(DeclTo->getLocation(), diag::note_type_incomplete) 479 << DeclTo->getDeclName(); 480 } 481 } 482} 483 484namespace { 485/// The kind of unwrapping we did when determining whether a conversion casts 486/// away constness. 487enum CastAwayConstnessKind { 488 /// The conversion does not cast away constness. 489 CACK_None = 0, 490 /// We unwrapped similar types. 491 CACK_Similar = 1, 492 /// We unwrapped dissimilar types with similar representations (eg, a pointer 493 /// versus an Objective-C object pointer). 494 CACK_SimilarKind = 2, 495 /// We unwrapped representationally-unrelated types, such as a pointer versus 496 /// a pointer-to-member. 497 CACK_Incoherent = 3, 498}; 499} 500 501/// Unwrap one level of types for CastsAwayConstness. 502/// 503/// Like Sema::UnwrapSimilarTypes, this removes one level of indirection from 504/// both types, provided that they're both pointer-like or array-like. Unlike 505/// the Sema function, doesn't care if the unwrapped pieces are related. 506/// 507/// This function may remove additional levels as necessary for correctness: 508/// the resulting T1 is unwrapped sufficiently that it is never an array type, 509/// so that its qualifiers can be directly compared to those of T2 (which will 510/// have the combined set of qualifiers from all indermediate levels of T2), 511/// as (effectively) required by [expr.const.cast]p7 replacing T1's qualifiers 512/// with those from T2. 513static CastAwayConstnessKind 514unwrapCastAwayConstnessLevel(ASTContext &Context, QualType &T1, QualType &T2) { 515 enum { None, Ptr, MemPtr, BlockPtr, Array }; 516 auto Classify = [](QualType T) { 517 if (T->isAnyPointerType()) return Ptr; 518 if (T->isMemberPointerType()) return MemPtr; 519 if (T->isBlockPointerType()) return BlockPtr; 520 // We somewhat-arbitrarily don't look through VLA types here. This is at 521 // least consistent with the behavior of UnwrapSimilarTypes. 522 if (T->isConstantArrayType() || T->isIncompleteArrayType()) return Array; 523 return None; 524 }; 525 526 auto Unwrap = [&](QualType T) { 527 if (auto *AT = Context.getAsArrayType(T)) 528 return AT->getElementType(); 529 return T->getPointeeType(); 530 }; 531 532 CastAwayConstnessKind Kind; 533 534 if (T2->isReferenceType()) { 535 // Special case: if the destination type is a reference type, unwrap it as 536 // the first level. (The source will have been an lvalue expression in this 537 // case, so there is no corresponding "reference to" in T1 to remove.) This 538 // simulates removing a "pointer to" from both sides. 539 T2 = T2->getPointeeType(); 540 Kind = CastAwayConstnessKind::CACK_Similar; 541 } else if (Context.UnwrapSimilarTypes(T1, T2)) { 542 Kind = CastAwayConstnessKind::CACK_Similar; 543 } else { 544 // Try unwrapping mismatching levels. 545 int T1Class = Classify(T1); 546 if (T1Class == None) 547 return CastAwayConstnessKind::CACK_None; 548 549 int T2Class = Classify(T2); 550 if (T2Class == None) 551 return CastAwayConstnessKind::CACK_None; 552 553 T1 = Unwrap(T1); 554 T2 = Unwrap(T2); 555 Kind = T1Class == T2Class ? CastAwayConstnessKind::CACK_SimilarKind 556 : CastAwayConstnessKind::CACK_Incoherent; 557 } 558 559 // We've unwrapped at least one level. If the resulting T1 is a (possibly 560 // multidimensional) array type, any qualifier on any matching layer of 561 // T2 is considered to correspond to T1. Decompose down to the element 562 // type of T1 so that we can compare properly. 563 while (true) { 564 Context.UnwrapSimilarArrayTypes(T1, T2); 565 566 if (Classify(T1) != Array) 567 break; 568 569 auto T2Class = Classify(T2); 570 if (T2Class == None) 571 break; 572 573 if (T2Class != Array) 574 Kind = CastAwayConstnessKind::CACK_Incoherent; 575 else if (Kind != CastAwayConstnessKind::CACK_Incoherent) 576 Kind = CastAwayConstnessKind::CACK_SimilarKind; 577 578 T1 = Unwrap(T1); 579 T2 = Unwrap(T2).withCVRQualifiers(T2.getCVRQualifiers()); 580 } 581 582 return Kind; 583} 584 585/// Check if the pointer conversion from SrcType to DestType casts away 586/// constness as defined in C++ [expr.const.cast]. This is used by the cast 587/// checkers. Both arguments must denote pointer (possibly to member) types. 588/// 589/// \param CheckCVR Whether to check for const/volatile/restrict qualifiers. 590/// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers. 591static CastAwayConstnessKind 592CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, 593 bool CheckCVR, bool CheckObjCLifetime, 594 QualType *TheOffendingSrcType = nullptr, 595 QualType *TheOffendingDestType = nullptr, 596 Qualifiers *CastAwayQualifiers = nullptr) { 597 // If the only checking we care about is for Objective-C lifetime qualifiers, 598 // and we're not in ObjC mode, there's nothing to check. 599 if (!CheckCVR && CheckObjCLifetime && !Self.Context.getLangOpts().ObjC) 600 return CastAwayConstnessKind::CACK_None; 601 602 if (!DestType->isReferenceType()) { 603 assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() || 604 SrcType->isBlockPointerType()) && 605 "Source type is not pointer or pointer to member."); 606 assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() || 607 DestType->isBlockPointerType()) && 608 "Destination type is not pointer or pointer to member."); 609 } 610 611 QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType), 612 UnwrappedDestType = Self.Context.getCanonicalType(DestType); 613 614 // Find the qualifiers. We only care about cvr-qualifiers for the 615 // purpose of this check, because other qualifiers (address spaces, 616 // Objective-C GC, etc.) are part of the type's identity. 617 QualType PrevUnwrappedSrcType = UnwrappedSrcType; 618 QualType PrevUnwrappedDestType = UnwrappedDestType; 619 auto WorstKind = CastAwayConstnessKind::CACK_Similar; 620 bool AllConstSoFar = true; 621 while (auto Kind = unwrapCastAwayConstnessLevel( 622 Self.Context, UnwrappedSrcType, UnwrappedDestType)) { 623 // Track the worst kind of unwrap we needed to do before we found a 624 // problem. 625 if (Kind > WorstKind) 626 WorstKind = Kind; 627 628 // Determine the relevant qualifiers at this level. 629 Qualifiers SrcQuals, DestQuals; 630 Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals); 631 Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals); 632 633 // We do not meaningfully track object const-ness of Objective-C object 634 // types. Remove const from the source type if either the source or 635 // the destination is an Objective-C object type. 636 if (UnwrappedSrcType->isObjCObjectType() || 637 UnwrappedDestType->isObjCObjectType()) 638 SrcQuals.removeConst(); 639 640 if (CheckCVR) { 641 Qualifiers SrcCvrQuals = 642 Qualifiers::fromCVRMask(SrcQuals.getCVRQualifiers()); 643 Qualifiers DestCvrQuals = 644 Qualifiers::fromCVRMask(DestQuals.getCVRQualifiers()); 645 646 if (SrcCvrQuals != DestCvrQuals) { 647 if (CastAwayQualifiers) 648 *CastAwayQualifiers = SrcCvrQuals - DestCvrQuals; 649 650 // If we removed a cvr-qualifier, this is casting away 'constness'. 651 if (!DestCvrQuals.compatiblyIncludes(SrcCvrQuals)) { 652 if (TheOffendingSrcType) 653 *TheOffendingSrcType = PrevUnwrappedSrcType; 654 if (TheOffendingDestType) 655 *TheOffendingDestType = PrevUnwrappedDestType; 656 return WorstKind; 657 } 658 659 // If any prior level was not 'const', this is also casting away 660 // 'constness'. We noted the outermost type missing a 'const' already. 661 if (!AllConstSoFar) 662 return WorstKind; 663 } 664 } 665 666 if (CheckObjCLifetime && 667 !DestQuals.compatiblyIncludesObjCLifetime(SrcQuals)) 668 return WorstKind; 669 670 // If we found our first non-const-qualified type, this may be the place 671 // where things start to go wrong. 672 if (AllConstSoFar && !DestQuals.hasConst()) { 673 AllConstSoFar = false; 674 if (TheOffendingSrcType) 675 *TheOffendingSrcType = PrevUnwrappedSrcType; 676 if (TheOffendingDestType) 677 *TheOffendingDestType = PrevUnwrappedDestType; 678 } 679 680 PrevUnwrappedSrcType = UnwrappedSrcType; 681 PrevUnwrappedDestType = UnwrappedDestType; 682 } 683 684 return CastAwayConstnessKind::CACK_None; 685} 686 687static TryCastResult getCastAwayConstnessCastKind(CastAwayConstnessKind CACK, 688 unsigned &DiagID) { 689 switch (CACK) { 690 case CastAwayConstnessKind::CACK_None: 691 llvm_unreachable("did not cast away constness"); 692 693 case CastAwayConstnessKind::CACK_Similar: 694 // FIXME: Accept these as an extension too? 695 case CastAwayConstnessKind::CACK_SimilarKind: 696 DiagID = diag::err_bad_cxx_cast_qualifiers_away; 697 return TC_Failed; 698 699 case CastAwayConstnessKind::CACK_Incoherent: 700 DiagID = diag::ext_bad_cxx_cast_qualifiers_away_incoherent; 701 return TC_Extension; 702 } 703 704 llvm_unreachable("unexpected cast away constness kind"); 705} 706 707/// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid. 708/// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime- 709/// checked downcasts in class hierarchies. 710void CastOperation::CheckDynamicCast() { 711 if (ValueKind == VK_RValue) 712 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 713 else if (isPlaceholder()) 714 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get()); 715 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 716 return; 717 718 QualType OrigSrcType = SrcExpr.get()->getType(); 719 QualType DestType = Self.Context.getCanonicalType(this->DestType); 720 721 // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type, 722 // or "pointer to cv void". 723 724 QualType DestPointee; 725 const PointerType *DestPointer = DestType->getAs<PointerType>(); 726 const ReferenceType *DestReference = nullptr; 727 if (DestPointer) { 728 DestPointee = DestPointer->getPointeeType(); 729 } else if ((DestReference = DestType->getAs<ReferenceType>())) { 730 DestPointee = DestReference->getPointeeType(); 731 } else { 732 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr) 733 << this->DestType << DestRange; 734 SrcExpr = ExprError(); 735 return; 736 } 737 738 const RecordType *DestRecord = DestPointee->getAs<RecordType>(); 739 if (DestPointee->isVoidType()) { 740 assert(DestPointer && "Reference to void is not possible"); 741 } else if (DestRecord) { 742 if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee, 743 diag::err_bad_dynamic_cast_incomplete, 744 DestRange)) { 745 SrcExpr = ExprError(); 746 return; 747 } 748 } else { 749 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 750 << DestPointee.getUnqualifiedType() << DestRange; 751 SrcExpr = ExprError(); 752 return; 753 } 754 755 // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to 756 // complete class type, [...]. If T is an lvalue reference type, v shall be 757 // an lvalue of a complete class type, [...]. If T is an rvalue reference 758 // type, v shall be an expression having a complete class type, [...] 759 QualType SrcType = Self.Context.getCanonicalType(OrigSrcType); 760 QualType SrcPointee; 761 if (DestPointer) { 762 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 763 SrcPointee = SrcPointer->getPointeeType(); 764 } else { 765 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr) 766 << OrigSrcType << SrcExpr.get()->getSourceRange(); 767 SrcExpr = ExprError(); 768 return; 769 } 770 } else if (DestReference->isLValueReferenceType()) { 771 if (!SrcExpr.get()->isLValue()) { 772 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue) 773 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 774 } 775 SrcPointee = SrcType; 776 } else { 777 // If we're dynamic_casting from a prvalue to an rvalue reference, we need 778 // to materialize the prvalue before we bind the reference to it. 779 if (SrcExpr.get()->isRValue()) 780 SrcExpr = Self.CreateMaterializeTemporaryExpr( 781 SrcType, SrcExpr.get(), /*IsLValueReference*/ false); 782 SrcPointee = SrcType; 783 } 784 785 const RecordType *SrcRecord = SrcPointee->getAs<RecordType>(); 786 if (SrcRecord) { 787 if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee, 788 diag::err_bad_dynamic_cast_incomplete, 789 SrcExpr.get())) { 790 SrcExpr = ExprError(); 791 return; 792 } 793 } else { 794 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 795 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 796 SrcExpr = ExprError(); 797 return; 798 } 799 800 assert((DestPointer || DestReference) && 801 "Bad destination non-ptr/ref slipped through."); 802 assert((DestRecord || DestPointee->isVoidType()) && 803 "Bad destination pointee slipped through."); 804 assert(SrcRecord && "Bad source pointee slipped through."); 805 806 // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness. 807 if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) { 808 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away) 809 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 810 SrcExpr = ExprError(); 811 return; 812 } 813 814 // C++ 5.2.7p3: If the type of v is the same as the required result type, 815 // [except for cv]. 816 if (DestRecord == SrcRecord) { 817 Kind = CK_NoOp; 818 return; 819 } 820 821 // C++ 5.2.7p5 822 // Upcasts are resolved statically. 823 if (DestRecord && 824 Self.IsDerivedFrom(OpRange.getBegin(), SrcPointee, DestPointee)) { 825 if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee, 826 OpRange.getBegin(), OpRange, 827 &BasePath)) { 828 SrcExpr = ExprError(); 829 return; 830 } 831 832 Kind = CK_DerivedToBase; 833 return; 834 } 835 836 // C++ 5.2.7p6: Otherwise, v shall be [polymorphic]. 837 const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition(); 838 assert(SrcDecl && "Definition missing"); 839 if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) { 840 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic) 841 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 842 SrcExpr = ExprError(); 843 } 844 845 // dynamic_cast is not available with -fno-rtti. 846 // As an exception, dynamic_cast to void* is available because it doesn't 847 // use RTTI. 848 if (!Self.getLangOpts().RTTI && !DestPointee->isVoidType()) { 849 Self.Diag(OpRange.getBegin(), diag::err_no_dynamic_cast_with_fno_rtti); 850 SrcExpr = ExprError(); 851 return; 852 } 853 854 // Done. Everything else is run-time checks. 855 Kind = CK_Dynamic; 856} 857 858/// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid. 859/// Refer to C++ 5.2.11 for details. const_cast is typically used in code 860/// like this: 861/// const char *str = "literal"; 862/// legacy_function(const_cast\<char*\>(str)); 863void CastOperation::CheckConstCast() { 864 if (ValueKind == VK_RValue) 865 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 866 else if (isPlaceholder()) 867 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get()); 868 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 869 return; 870 871 unsigned msg = diag::err_bad_cxx_cast_generic; 872 auto TCR = TryConstCast(Self, SrcExpr, DestType, /*CStyle*/ false, msg); 873 if (TCR != TC_Success && msg != 0) { 874 Self.Diag(OpRange.getBegin(), msg) << CT_Const 875 << SrcExpr.get()->getType() << DestType << OpRange; 876 } 877 if (!isValidCast(TCR)) 878 SrcExpr = ExprError(); 879} 880 881/// Check that a reinterpret_cast\<DestType\>(SrcExpr) is not used as upcast 882/// or downcast between respective pointers or references. 883static void DiagnoseReinterpretUpDownCast(Sema &Self, const Expr *SrcExpr, 884 QualType DestType, 885 SourceRange OpRange) { 886 QualType SrcType = SrcExpr->getType(); 887 // When casting from pointer or reference, get pointee type; use original 888 // type otherwise. 889 const CXXRecordDecl *SrcPointeeRD = SrcType->getPointeeCXXRecordDecl(); 890 const CXXRecordDecl *SrcRD = 891 SrcPointeeRD ? SrcPointeeRD : SrcType->getAsCXXRecordDecl(); 892 893 // Examining subobjects for records is only possible if the complete and 894 // valid definition is available. Also, template instantiation is not 895 // allowed here. 896 if (!SrcRD || !SrcRD->isCompleteDefinition() || SrcRD->isInvalidDecl()) 897 return; 898 899 const CXXRecordDecl *DestRD = DestType->getPointeeCXXRecordDecl(); 900 901 if (!DestRD || !DestRD->isCompleteDefinition() || DestRD->isInvalidDecl()) 902 return; 903 904 enum { 905 ReinterpretUpcast, 906 ReinterpretDowncast 907 } ReinterpretKind; 908 909 CXXBasePaths BasePaths; 910 911 if (SrcRD->isDerivedFrom(DestRD, BasePaths)) 912 ReinterpretKind = ReinterpretUpcast; 913 else if (DestRD->isDerivedFrom(SrcRD, BasePaths)) 914 ReinterpretKind = ReinterpretDowncast; 915 else 916 return; 917 918 bool VirtualBase = true; 919 bool NonZeroOffset = false; 920 for (CXXBasePaths::const_paths_iterator I = BasePaths.begin(), 921 E = BasePaths.end(); 922 I != E; ++I) { 923 const CXXBasePath &Path = *I; 924 CharUnits Offset = CharUnits::Zero(); 925 bool IsVirtual = false; 926 for (CXXBasePath::const_iterator IElem = Path.begin(), EElem = Path.end(); 927 IElem != EElem; ++IElem) { 928 IsVirtual = IElem->Base->isVirtual(); 929 if (IsVirtual) 930 break; 931 const CXXRecordDecl *BaseRD = IElem->Base->getType()->getAsCXXRecordDecl(); 932 assert(BaseRD && "Base type should be a valid unqualified class type"); 933 // Don't check if any base has invalid declaration or has no definition 934 // since it has no layout info. 935 const CXXRecordDecl *Class = IElem->Class, 936 *ClassDefinition = Class->getDefinition(); 937 if (Class->isInvalidDecl() || !ClassDefinition || 938 !ClassDefinition->isCompleteDefinition()) 939 return; 940 941 const ASTRecordLayout &DerivedLayout = 942 Self.Context.getASTRecordLayout(Class); 943 Offset += DerivedLayout.getBaseClassOffset(BaseRD); 944 } 945 if (!IsVirtual) { 946 // Don't warn if any path is a non-virtually derived base at offset zero. 947 if (Offset.isZero()) 948 return; 949 // Offset makes sense only for non-virtual bases. 950 else 951 NonZeroOffset = true; 952 } 953 VirtualBase = VirtualBase && IsVirtual; 954 } 955 956 (void) NonZeroOffset; // Silence set but not used warning. 957 assert((VirtualBase || NonZeroOffset) && 958 "Should have returned if has non-virtual base with zero offset"); 959 960 QualType BaseType = 961 ReinterpretKind == ReinterpretUpcast? DestType : SrcType; 962 QualType DerivedType = 963 ReinterpretKind == ReinterpretUpcast? SrcType : DestType; 964 965 SourceLocation BeginLoc = OpRange.getBegin(); 966 Self.Diag(BeginLoc, diag::warn_reinterpret_different_from_static) 967 << DerivedType << BaseType << !VirtualBase << int(ReinterpretKind) 968 << OpRange; 969 Self.Diag(BeginLoc, diag::note_reinterpret_updowncast_use_static) 970 << int(ReinterpretKind) 971 << FixItHint::CreateReplacement(BeginLoc, "static_cast"); 972} 973 974/// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is 975/// valid. 976/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code 977/// like this: 978/// char *bytes = reinterpret_cast\<char*\>(int_ptr); 979void CastOperation::CheckReinterpretCast() { 980 if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload)) 981 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 982 else 983 checkNonOverloadPlaceholders(); 984 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 985 return; 986 987 unsigned msg = diag::err_bad_cxx_cast_generic; 988 TryCastResult tcr = 989 TryReinterpretCast(Self, SrcExpr, DestType, 990 /*CStyle*/false, OpRange, msg, Kind); 991 if (tcr != TC_Success && msg != 0) { 992 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 993 return; 994 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 995 //FIXME: &f<int>; is overloaded and resolvable 996 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload) 997 << OverloadExpr::find(SrcExpr.get()).Expression->getName() 998 << DestType << OpRange; 999 Self.NoteAllOverloadCandidates(SrcExpr.get()); 1000 1001 } else { 1002 diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(), 1003 DestType, /*listInitialization=*/false); 1004 } 1005 } 1006 1007 if (isValidCast(tcr)) { 1008 if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()) 1009 checkObjCConversion(Sema::CCK_OtherCast); 1010 DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange); 1011 } else { 1012 SrcExpr = ExprError(); 1013 } 1014} 1015 1016 1017/// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid. 1018/// Refer to C++ 5.2.9 for details. Static casts are mostly used for making 1019/// implicit conversions explicit and getting rid of data loss warnings. 1020void CastOperation::CheckStaticCast() { 1021 if (isPlaceholder()) { 1022 checkNonOverloadPlaceholders(); 1023 if (SrcExpr.isInvalid()) 1024 return; 1025 } 1026 1027 // This test is outside everything else because it's the only case where 1028 // a non-lvalue-reference target type does not lead to decay. 1029 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 1030 if (DestType->isVoidType()) { 1031 Kind = CK_ToVoid; 1032 1033 if (claimPlaceholder(BuiltinType::Overload)) { 1034 Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr, 1035 false, // Decay Function to ptr 1036 true, // Complain 1037 OpRange, DestType, diag::err_bad_static_cast_overload); 1038 if (SrcExpr.isInvalid()) 1039 return; 1040 } 1041 1042 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get()); 1043 return; 1044 } 1045 1046 if (ValueKind == VK_RValue && !DestType->isRecordType() && 1047 !isPlaceholder(BuiltinType::Overload)) { 1048 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 1049 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 1050 return; 1051 } 1052 1053 unsigned msg = diag::err_bad_cxx_cast_generic; 1054 TryCastResult tcr 1055 = TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_OtherCast, OpRange, msg, 1056 Kind, BasePath, /*ListInitialization=*/false); 1057 if (tcr != TC_Success && msg != 0) { 1058 if (SrcExpr.isInvalid()) 1059 return; 1060 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 1061 OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression; 1062 Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload) 1063 << oe->getName() << DestType << OpRange 1064 << oe->getQualifierLoc().getSourceRange(); 1065 Self.NoteAllOverloadCandidates(SrcExpr.get()); 1066 } else { 1067 diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType, 1068 /*listInitialization=*/false); 1069 } 1070 } 1071 1072 if (isValidCast(tcr)) { 1073 if (Kind == CK_BitCast) 1074 checkCastAlign(); 1075 if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()) 1076 checkObjCConversion(Sema::CCK_OtherCast); 1077 } else { 1078 SrcExpr = ExprError(); 1079 } 1080} 1081 1082static bool IsAddressSpaceConversion(QualType SrcType, QualType DestType) { 1083 auto *SrcPtrType = SrcType->getAs<PointerType>(); 1084 if (!SrcPtrType) 1085 return false; 1086 auto *DestPtrType = DestType->getAs<PointerType>(); 1087 if (!DestPtrType) 1088 return false; 1089 return SrcPtrType->getPointeeType().getAddressSpace() != 1090 DestPtrType->getPointeeType().getAddressSpace(); 1091} 1092 1093/// TryStaticCast - Check if a static cast can be performed, and do so if 1094/// possible. If @p CStyle, ignore access restrictions on hierarchy casting 1095/// and casting away constness. 1096static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, 1097 QualType DestType, 1098 Sema::CheckedConversionKind CCK, 1099 SourceRange OpRange, unsigned &msg, 1100 CastKind &Kind, CXXCastPath &BasePath, 1101 bool ListInitialization) { 1102 // Determine whether we have the semantics of a C-style cast. 1103 bool CStyle 1104 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 1105 1106 // The order the tests is not entirely arbitrary. There is one conversion 1107 // that can be handled in two different ways. Given: 1108 // struct A {}; 1109 // struct B : public A { 1110 // B(); B(const A&); 1111 // }; 1112 // const A &a = B(); 1113 // the cast static_cast<const B&>(a) could be seen as either a static 1114 // reference downcast, or an explicit invocation of the user-defined 1115 // conversion using B's conversion constructor. 1116 // DR 427 specifies that the downcast is to be applied here. 1117 1118 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 1119 // Done outside this function. 1120 1121 TryCastResult tcr; 1122 1123 // C++ 5.2.9p5, reference downcast. 1124 // See the function for details. 1125 // DR 427 specifies that this is to be applied before paragraph 2. 1126 tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle, 1127 OpRange, msg, Kind, BasePath); 1128 if (tcr != TC_NotApplicable) 1129 return tcr; 1130 1131 // C++11 [expr.static.cast]p3: 1132 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2 1133 // T2" if "cv2 T2" is reference-compatible with "cv1 T1". 1134 tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind, 1135 BasePath, msg); 1136 if (tcr != TC_NotApplicable) 1137 return tcr; 1138 1139 // C++ 5.2.9p2: An expression e can be explicitly converted to a type T 1140 // [...] if the declaration "T t(e);" is well-formed, [...]. 1141 tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg, 1142 Kind, ListInitialization); 1143 if (SrcExpr.isInvalid()) 1144 return TC_Failed; 1145 if (tcr != TC_NotApplicable) 1146 return tcr; 1147 1148 // C++ 5.2.9p6: May apply the reverse of any standard conversion, except 1149 // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean 1150 // conversions, subject to further restrictions. 1151 // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal 1152 // of qualification conversions impossible. 1153 // In the CStyle case, the earlier attempt to const_cast should have taken 1154 // care of reverse qualification conversions. 1155 1156 QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType()); 1157 1158 // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly 1159 // converted to an integral type. [...] A value of a scoped enumeration type 1160 // can also be explicitly converted to a floating-point type [...]. 1161 if (const EnumType *Enum = SrcType->getAs<EnumType>()) { 1162 if (Enum->getDecl()->isScoped()) { 1163 if (DestType->isBooleanType()) { 1164 Kind = CK_IntegralToBoolean; 1165 return TC_Success; 1166 } else if (DestType->isIntegralType(Self.Context)) { 1167 Kind = CK_IntegralCast; 1168 return TC_Success; 1169 } else if (DestType->isRealFloatingType()) { 1170 Kind = CK_IntegralToFloating; 1171 return TC_Success; 1172 } 1173 } 1174 } 1175 1176 // Reverse integral promotion/conversion. All such conversions are themselves 1177 // again integral promotions or conversions and are thus already handled by 1178 // p2 (TryDirectInitialization above). 1179 // (Note: any data loss warnings should be suppressed.) 1180 // The exception is the reverse of enum->integer, i.e. integer->enum (and 1181 // enum->enum). See also C++ 5.2.9p7. 1182 // The same goes for reverse floating point promotion/conversion and 1183 // floating-integral conversions. Again, only floating->enum is relevant. 1184 if (DestType->isEnumeralType()) { 1185 if (SrcType->isIntegralOrEnumerationType()) { 1186 Kind = CK_IntegralCast; 1187 return TC_Success; 1188 } else if (SrcType->isRealFloatingType()) { 1189 Kind = CK_FloatingToIntegral; 1190 return TC_Success; 1191 } 1192 } 1193 1194 // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast. 1195 // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance. 1196 tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg, 1197 Kind, BasePath); 1198 if (tcr != TC_NotApplicable) 1199 return tcr; 1200 1201 // Reverse member pointer conversion. C++ 4.11 specifies member pointer 1202 // conversion. C++ 5.2.9p9 has additional information. 1203 // DR54's access restrictions apply here also. 1204 tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle, 1205 OpRange, msg, Kind, BasePath); 1206 if (tcr != TC_NotApplicable) 1207 return tcr; 1208 1209 // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to 1210 // void*. C++ 5.2.9p10 specifies additional restrictions, which really is 1211 // just the usual constness stuff. 1212 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 1213 QualType SrcPointee = SrcPointer->getPointeeType(); 1214 if (SrcPointee->isVoidType()) { 1215 if (const PointerType *DestPointer = DestType->getAs<PointerType>()) { 1216 QualType DestPointee = DestPointer->getPointeeType(); 1217 if (DestPointee->isIncompleteOrObjectType()) { 1218 // This is definitely the intended conversion, but it might fail due 1219 // to a qualifier violation. Note that we permit Objective-C lifetime 1220 // and GC qualifier mismatches here. 1221 if (!CStyle) { 1222 Qualifiers DestPointeeQuals = DestPointee.getQualifiers(); 1223 Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers(); 1224 DestPointeeQuals.removeObjCGCAttr(); 1225 DestPointeeQuals.removeObjCLifetime(); 1226 SrcPointeeQuals.removeObjCGCAttr(); 1227 SrcPointeeQuals.removeObjCLifetime(); 1228 if (DestPointeeQuals != SrcPointeeQuals && 1229 !DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) { 1230 msg = diag::err_bad_cxx_cast_qualifiers_away; 1231 return TC_Failed; 1232 } 1233 } 1234 Kind = IsAddressSpaceConversion(SrcType, DestType) 1235 ? CK_AddressSpaceConversion 1236 : CK_BitCast; 1237 return TC_Success; 1238 } 1239 1240 // Microsoft permits static_cast from 'pointer-to-void' to 1241 // 'pointer-to-function'. 1242 if (!CStyle && Self.getLangOpts().MSVCCompat && 1243 DestPointee->isFunctionType()) { 1244 Self.Diag(OpRange.getBegin(), diag::ext_ms_cast_fn_obj) << OpRange; 1245 Kind = CK_BitCast; 1246 return TC_Success; 1247 } 1248 } 1249 else if (DestType->isObjCObjectPointerType()) { 1250 // allow both c-style cast and static_cast of objective-c pointers as 1251 // they are pervasive. 1252 Kind = CK_CPointerToObjCPointerCast; 1253 return TC_Success; 1254 } 1255 else if (CStyle && DestType->isBlockPointerType()) { 1256 // allow c-style cast of void * to block pointers. 1257 Kind = CK_AnyPointerToBlockPointerCast; 1258 return TC_Success; 1259 } 1260 } 1261 } 1262 // Allow arbitrary objective-c pointer conversion with static casts. 1263 if (SrcType->isObjCObjectPointerType() && 1264 DestType->isObjCObjectPointerType()) { 1265 Kind = CK_BitCast; 1266 return TC_Success; 1267 } 1268 // Allow ns-pointer to cf-pointer conversion in either direction 1269 // with static casts. 1270 if (!CStyle && 1271 Self.CheckTollFreeBridgeStaticCast(DestType, SrcExpr.get(), Kind)) 1272 return TC_Success; 1273 1274 // See if it looks like the user is trying to convert between 1275 // related record types, and select a better diagnostic if so. 1276 if (auto SrcPointer = SrcType->getAs<PointerType>()) 1277 if (auto DestPointer = DestType->getAs<PointerType>()) 1278 if (SrcPointer->getPointeeType()->getAs<RecordType>() && 1279 DestPointer->getPointeeType()->getAs<RecordType>()) 1280 msg = diag::err_bad_cxx_cast_unrelated_class; 1281 1282 // We tried everything. Everything! Nothing works! :-( 1283 return TC_NotApplicable; 1284} 1285 1286/// Tests whether a conversion according to N2844 is valid. 1287TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, 1288 QualType DestType, bool CStyle, 1289 CastKind &Kind, CXXCastPath &BasePath, 1290 unsigned &msg) { 1291 // C++11 [expr.static.cast]p3: 1292 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to 1293 // cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1". 1294 const RValueReferenceType *R = DestType->getAs<RValueReferenceType>(); 1295 if (!R) 1296 return TC_NotApplicable; 1297 1298 if (!SrcExpr->isGLValue()) 1299 return TC_NotApplicable; 1300 1301 // Because we try the reference downcast before this function, from now on 1302 // this is the only cast possibility, so we issue an error if we fail now. 1303 // FIXME: Should allow casting away constness if CStyle. 1304 bool DerivedToBase; 1305 bool ObjCConversion; 1306 bool ObjCLifetimeConversion; 1307 QualType FromType = SrcExpr->getType(); 1308 QualType ToType = R->getPointeeType(); 1309 if (CStyle) { 1310 FromType = FromType.getUnqualifiedType(); 1311 ToType = ToType.getUnqualifiedType(); 1312 } 1313 1314 Sema::ReferenceCompareResult RefResult = Self.CompareReferenceRelationship( 1315 SrcExpr->getBeginLoc(), ToType, FromType, DerivedToBase, ObjCConversion, 1316 ObjCLifetimeConversion); 1317 if (RefResult != Sema::Ref_Compatible) { 1318 if (CStyle || RefResult == Sema::Ref_Incompatible) 1319 return TC_NotApplicable; 1320 // Diagnose types which are reference-related but not compatible here since 1321 // we can provide better diagnostics. In these cases forwarding to 1322 // [expr.static.cast]p4 should never result in a well-formed cast. 1323 msg = SrcExpr->isLValue() ? diag::err_bad_lvalue_to_rvalue_cast 1324 : diag::err_bad_rvalue_to_rvalue_cast; 1325 return TC_Failed; 1326 } 1327 1328 if (DerivedToBase) { 1329 Kind = CK_DerivedToBase; 1330 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1331 /*DetectVirtual=*/true); 1332 if (!Self.IsDerivedFrom(SrcExpr->getBeginLoc(), SrcExpr->getType(), 1333 R->getPointeeType(), Paths)) 1334 return TC_NotApplicable; 1335 1336 Self.BuildBasePathArray(Paths, BasePath); 1337 } else 1338 Kind = CK_NoOp; 1339 1340 return TC_Success; 1341} 1342 1343/// Tests whether a conversion according to C++ 5.2.9p5 is valid. 1344TryCastResult 1345TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType, 1346 bool CStyle, SourceRange OpRange, 1347 unsigned &msg, CastKind &Kind, 1348 CXXCastPath &BasePath) { 1349 // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be 1350 // cast to type "reference to cv2 D", where D is a class derived from B, 1351 // if a valid standard conversion from "pointer to D" to "pointer to B" 1352 // exists, cv2 >= cv1, and B is not a virtual base class of D. 1353 // In addition, DR54 clarifies that the base must be accessible in the 1354 // current context. Although the wording of DR54 only applies to the pointer 1355 // variant of this rule, the intent is clearly for it to apply to the this 1356 // conversion as well. 1357 1358 const ReferenceType *DestReference = DestType->getAs<ReferenceType>(); 1359 if (!DestReference) { 1360 return TC_NotApplicable; 1361 } 1362 bool RValueRef = DestReference->isRValueReferenceType(); 1363 if (!RValueRef && !SrcExpr->isLValue()) { 1364 // We know the left side is an lvalue reference, so we can suggest a reason. 1365 msg = diag::err_bad_cxx_cast_rvalue; 1366 return TC_NotApplicable; 1367 } 1368 1369 QualType DestPointee = DestReference->getPointeeType(); 1370 1371 // FIXME: If the source is a prvalue, we should issue a warning (because the 1372 // cast always has undefined behavior), and for AST consistency, we should 1373 // materialize a temporary. 1374 return TryStaticDowncast(Self, 1375 Self.Context.getCanonicalType(SrcExpr->getType()), 1376 Self.Context.getCanonicalType(DestPointee), CStyle, 1377 OpRange, SrcExpr->getType(), DestType, msg, Kind, 1378 BasePath); 1379} 1380 1381/// Tests whether a conversion according to C++ 5.2.9p8 is valid. 1382TryCastResult 1383TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType, 1384 bool CStyle, SourceRange OpRange, 1385 unsigned &msg, CastKind &Kind, 1386 CXXCastPath &BasePath) { 1387 // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class 1388 // type, can be converted to an rvalue of type "pointer to cv2 D", where D 1389 // is a class derived from B, if a valid standard conversion from "pointer 1390 // to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base 1391 // class of D. 1392 // In addition, DR54 clarifies that the base must be accessible in the 1393 // current context. 1394 1395 const PointerType *DestPointer = DestType->getAs<PointerType>(); 1396 if (!DestPointer) { 1397 return TC_NotApplicable; 1398 } 1399 1400 const PointerType *SrcPointer = SrcType->getAs<PointerType>(); 1401 if (!SrcPointer) { 1402 msg = diag::err_bad_static_cast_pointer_nonpointer; 1403 return TC_NotApplicable; 1404 } 1405 1406 return TryStaticDowncast(Self, 1407 Self.Context.getCanonicalType(SrcPointer->getPointeeType()), 1408 Self.Context.getCanonicalType(DestPointer->getPointeeType()), 1409 CStyle, OpRange, SrcType, DestType, msg, Kind, 1410 BasePath); 1411} 1412 1413/// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and 1414/// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to 1415/// DestType is possible and allowed. 1416TryCastResult 1417TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType, 1418 bool CStyle, SourceRange OpRange, QualType OrigSrcType, 1419 QualType OrigDestType, unsigned &msg, 1420 CastKind &Kind, CXXCastPath &BasePath) { 1421 // We can only work with complete types. But don't complain if it doesn't work 1422 if (!Self.isCompleteType(OpRange.getBegin(), SrcType) || 1423 !Self.isCompleteType(OpRange.getBegin(), DestType)) 1424 return TC_NotApplicable; 1425 1426 // Downcast can only happen in class hierarchies, so we need classes. 1427 if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) { 1428 return TC_NotApplicable; 1429 } 1430 1431 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1432 /*DetectVirtual=*/true); 1433 if (!Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths)) { 1434 return TC_NotApplicable; 1435 } 1436 1437 // Target type does derive from source type. Now we're serious. If an error 1438 // appears now, it's not ignored. 1439 // This may not be entirely in line with the standard. Take for example: 1440 // struct A {}; 1441 // struct B : virtual A { 1442 // B(A&); 1443 // }; 1444 // 1445 // void f() 1446 // { 1447 // (void)static_cast<const B&>(*((A*)0)); 1448 // } 1449 // As far as the standard is concerned, p5 does not apply (A is virtual), so 1450 // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid. 1451 // However, both GCC and Comeau reject this example, and accepting it would 1452 // mean more complex code if we're to preserve the nice error message. 1453 // FIXME: Being 100% compliant here would be nice to have. 1454 1455 // Must preserve cv, as always, unless we're in C-style mode. 1456 if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) { 1457 msg = diag::err_bad_cxx_cast_qualifiers_away; 1458 return TC_Failed; 1459 } 1460 1461 if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) { 1462 // This code is analoguous to that in CheckDerivedToBaseConversion, except 1463 // that it builds the paths in reverse order. 1464 // To sum up: record all paths to the base and build a nice string from 1465 // them. Use it to spice up the error message. 1466 if (!Paths.isRecordingPaths()) { 1467 Paths.clear(); 1468 Paths.setRecordingPaths(true); 1469 Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths); 1470 } 1471 std::string PathDisplayStr; 1472 std::set<unsigned> DisplayedPaths; 1473 for (clang::CXXBasePath &Path : Paths) { 1474 if (DisplayedPaths.insert(Path.back().SubobjectNumber).second) { 1475 // We haven't displayed a path to this particular base 1476 // class subobject yet. 1477 PathDisplayStr += "\n "; 1478 for (CXXBasePathElement &PE : llvm::reverse(Path)) 1479 PathDisplayStr += PE.Base->getType().getAsString() + " -> "; 1480 PathDisplayStr += QualType(DestType).getAsString(); 1481 } 1482 } 1483 1484 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast) 1485 << QualType(SrcType).getUnqualifiedType() 1486 << QualType(DestType).getUnqualifiedType() 1487 << PathDisplayStr << OpRange; 1488 msg = 0; 1489 return TC_Failed; 1490 } 1491 1492 if (Paths.getDetectedVirtual() != nullptr) { 1493 QualType VirtualBase(Paths.getDetectedVirtual(), 0); 1494 Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual) 1495 << OrigSrcType << OrigDestType << VirtualBase << OpRange; 1496 msg = 0; 1497 return TC_Failed; 1498 } 1499 1500 if (!CStyle) { 1501 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1502 SrcType, DestType, 1503 Paths.front(), 1504 diag::err_downcast_from_inaccessible_base)) { 1505 case Sema::AR_accessible: 1506 case Sema::AR_delayed: // be optimistic 1507 case Sema::AR_dependent: // be optimistic 1508 break; 1509 1510 case Sema::AR_inaccessible: 1511 msg = 0; 1512 return TC_Failed; 1513 } 1514 } 1515 1516 Self.BuildBasePathArray(Paths, BasePath); 1517 Kind = CK_BaseToDerived; 1518 return TC_Success; 1519} 1520 1521/// TryStaticMemberPointerUpcast - Tests whether a conversion according to 1522/// C++ 5.2.9p9 is valid: 1523/// 1524/// An rvalue of type "pointer to member of D of type cv1 T" can be 1525/// converted to an rvalue of type "pointer to member of B of type cv2 T", 1526/// where B is a base class of D [...]. 1527/// 1528TryCastResult 1529TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType, 1530 QualType DestType, bool CStyle, 1531 SourceRange OpRange, 1532 unsigned &msg, CastKind &Kind, 1533 CXXCastPath &BasePath) { 1534 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(); 1535 if (!DestMemPtr) 1536 return TC_NotApplicable; 1537 1538 bool WasOverloadedFunction = false; 1539 DeclAccessPair FoundOverload; 1540 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 1541 if (FunctionDecl *Fn 1542 = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false, 1543 FoundOverload)) { 1544 CXXMethodDecl *M = cast<CXXMethodDecl>(Fn); 1545 SrcType = Self.Context.getMemberPointerType(Fn->getType(), 1546 Self.Context.getTypeDeclType(M->getParent()).getTypePtr()); 1547 WasOverloadedFunction = true; 1548 } 1549 } 1550 1551 const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 1552 if (!SrcMemPtr) { 1553 msg = diag::err_bad_static_cast_member_pointer_nonmp; 1554 return TC_NotApplicable; 1555 } 1556 1557 // Lock down the inheritance model right now in MS ABI, whether or not the 1558 // pointee types are the same. 1559 if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) { 1560 (void)Self.isCompleteType(OpRange.getBegin(), SrcType); 1561 (void)Self.isCompleteType(OpRange.getBegin(), DestType); 1562 } 1563 1564 // T == T, modulo cv 1565 if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(), 1566 DestMemPtr->getPointeeType())) 1567 return TC_NotApplicable; 1568 1569 // B base of D 1570 QualType SrcClass(SrcMemPtr->getClass(), 0); 1571 QualType DestClass(DestMemPtr->getClass(), 0); 1572 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1573 /*DetectVirtual=*/true); 1574 if (!Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths)) 1575 return TC_NotApplicable; 1576 1577 // B is a base of D. But is it an allowed base? If not, it's a hard error. 1578 if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) { 1579 Paths.clear(); 1580 Paths.setRecordingPaths(true); 1581 bool StillOkay = 1582 Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths); 1583 assert(StillOkay); 1584 (void)StillOkay; 1585 std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths); 1586 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv) 1587 << 1 << SrcClass << DestClass << PathDisplayStr << OpRange; 1588 msg = 0; 1589 return TC_Failed; 1590 } 1591 1592 if (const RecordType *VBase = Paths.getDetectedVirtual()) { 1593 Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual) 1594 << SrcClass << DestClass << QualType(VBase, 0) << OpRange; 1595 msg = 0; 1596 return TC_Failed; 1597 } 1598 1599 if (!CStyle) { 1600 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1601 DestClass, SrcClass, 1602 Paths.front(), 1603 diag::err_upcast_to_inaccessible_base)) { 1604 case Sema::AR_accessible: 1605 case Sema::AR_delayed: 1606 case Sema::AR_dependent: 1607 // Optimistically assume that the delayed and dependent cases 1608 // will work out. 1609 break; 1610 1611 case Sema::AR_inaccessible: 1612 msg = 0; 1613 return TC_Failed; 1614 } 1615 } 1616 1617 if (WasOverloadedFunction) { 1618 // Resolve the address of the overloaded function again, this time 1619 // allowing complaints if something goes wrong. 1620 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 1621 DestType, 1622 true, 1623 FoundOverload); 1624 if (!Fn) { 1625 msg = 0; 1626 return TC_Failed; 1627 } 1628 1629 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn); 1630 if (!SrcExpr.isUsable()) { 1631 msg = 0; 1632 return TC_Failed; 1633 } 1634 } 1635 1636 Self.BuildBasePathArray(Paths, BasePath); 1637 Kind = CK_DerivedToBaseMemberPointer; 1638 return TC_Success; 1639} 1640 1641/// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2 1642/// is valid: 1643/// 1644/// An expression e can be explicitly converted to a type T using a 1645/// @c static_cast if the declaration "T t(e);" is well-formed [...]. 1646TryCastResult 1647TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, 1648 Sema::CheckedConversionKind CCK, 1649 SourceRange OpRange, unsigned &msg, 1650 CastKind &Kind, bool ListInitialization) { 1651 if (DestType->isRecordType()) { 1652 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 1653 diag::err_bad_dynamic_cast_incomplete) || 1654 Self.RequireNonAbstractType(OpRange.getBegin(), DestType, 1655 diag::err_allocation_of_abstract_type)) { 1656 msg = 0; 1657 return TC_Failed; 1658 } 1659 } 1660 1661 InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType); 1662 InitializationKind InitKind 1663 = (CCK == Sema::CCK_CStyleCast) 1664 ? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange, 1665 ListInitialization) 1666 : (CCK == Sema::CCK_FunctionalCast) 1667 ? InitializationKind::CreateFunctionalCast(OpRange, ListInitialization) 1668 : InitializationKind::CreateCast(OpRange); 1669 Expr *SrcExprRaw = SrcExpr.get(); 1670 // FIXME: Per DR242, we should check for an implicit conversion sequence 1671 // or for a constructor that could be invoked by direct-initialization 1672 // here, not for an initialization sequence. 1673 InitializationSequence InitSeq(Self, Entity, InitKind, SrcExprRaw); 1674 1675 // At this point of CheckStaticCast, if the destination is a reference, 1676 // or the expression is an overload expression this has to work. 1677 // There is no other way that works. 1678 // On the other hand, if we're checking a C-style cast, we've still got 1679 // the reinterpret_cast way. 1680 bool CStyle 1681 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 1682 if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType())) 1683 return TC_NotApplicable; 1684 1685 ExprResult Result = InitSeq.Perform(Self, Entity, InitKind, SrcExprRaw); 1686 if (Result.isInvalid()) { 1687 msg = 0; 1688 return TC_Failed; 1689 } 1690 1691 if (InitSeq.isConstructorInitialization()) 1692 Kind = CK_ConstructorConversion; 1693 else 1694 Kind = CK_NoOp; 1695 1696 SrcExpr = Result; 1697 return TC_Success; 1698} 1699 1700/// TryConstCast - See if a const_cast from source to destination is allowed, 1701/// and perform it if it is. 1702static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr, 1703 QualType DestType, bool CStyle, 1704 unsigned &msg) { 1705 DestType = Self.Context.getCanonicalType(DestType); 1706 QualType SrcType = SrcExpr.get()->getType(); 1707 bool NeedToMaterializeTemporary = false; 1708 1709 if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) { 1710 // C++11 5.2.11p4: 1711 // if a pointer to T1 can be explicitly converted to the type "pointer to 1712 // T2" using a const_cast, then the following conversions can also be 1713 // made: 1714 // -- an lvalue of type T1 can be explicitly converted to an lvalue of 1715 // type T2 using the cast const_cast<T2&>; 1716 // -- a glvalue of type T1 can be explicitly converted to an xvalue of 1717 // type T2 using the cast const_cast<T2&&>; and 1718 // -- if T1 is a class type, a prvalue of type T1 can be explicitly 1719 // converted to an xvalue of type T2 using the cast const_cast<T2&&>. 1720 1721 if (isa<LValueReferenceType>(DestTypeTmp) && !SrcExpr.get()->isLValue()) { 1722 // Cannot const_cast non-lvalue to lvalue reference type. But if this 1723 // is C-style, static_cast might find a way, so we simply suggest a 1724 // message and tell the parent to keep searching. 1725 msg = diag::err_bad_cxx_cast_rvalue; 1726 return TC_NotApplicable; 1727 } 1728 1729 if (isa<RValueReferenceType>(DestTypeTmp) && SrcExpr.get()->isRValue()) { 1730 if (!SrcType->isRecordType()) { 1731 // Cannot const_cast non-class prvalue to rvalue reference type. But if 1732 // this is C-style, static_cast can do this. 1733 msg = diag::err_bad_cxx_cast_rvalue; 1734 return TC_NotApplicable; 1735 } 1736 1737 // Materialize the class prvalue so that the const_cast can bind a 1738 // reference to it. 1739 NeedToMaterializeTemporary = true; 1740 } 1741 1742 // It's not completely clear under the standard whether we can 1743 // const_cast bit-field gl-values. Doing so would not be 1744 // intrinsically complicated, but for now, we say no for 1745 // consistency with other compilers and await the word of the 1746 // committee. 1747 if (SrcExpr.get()->refersToBitField()) { 1748 msg = diag::err_bad_cxx_cast_bitfield; 1749 return TC_NotApplicable; 1750 } 1751 1752 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 1753 SrcType = Self.Context.getPointerType(SrcType); 1754 } 1755 1756 // C++ 5.2.11p5: For a const_cast involving pointers to data members [...] 1757 // the rules for const_cast are the same as those used for pointers. 1758 1759 if (!DestType->isPointerType() && 1760 !DestType->isMemberPointerType() && 1761 !DestType->isObjCObjectPointerType()) { 1762 // Cannot cast to non-pointer, non-reference type. Note that, if DestType 1763 // was a reference type, we converted it to a pointer above. 1764 // The status of rvalue references isn't entirely clear, but it looks like 1765 // conversion to them is simply invalid. 1766 // C++ 5.2.11p3: For two pointer types [...] 1767 if (!CStyle) 1768 msg = diag::err_bad_const_cast_dest; 1769 return TC_NotApplicable; 1770 } 1771 if (DestType->isFunctionPointerType() || 1772 DestType->isMemberFunctionPointerType()) { 1773 // Cannot cast direct function pointers. 1774 // C++ 5.2.11p2: [...] where T is any object type or the void type [...] 1775 // T is the ultimate pointee of source and target type. 1776 if (!CStyle) 1777 msg = diag::err_bad_const_cast_dest; 1778 return TC_NotApplicable; 1779 } 1780 1781 // C++ [expr.const.cast]p3: 1782 // "For two similar types T1 and T2, [...]" 1783 // 1784 // We only allow a const_cast to change cvr-qualifiers, not other kinds of 1785 // type qualifiers. (Likewise, we ignore other changes when determining 1786 // whether a cast casts away constness.) 1787 if (!Self.Context.hasCvrSimilarType(SrcType, DestType)) 1788 return TC_NotApplicable; 1789 1790 if (NeedToMaterializeTemporary) 1791 // This is a const_cast from a class prvalue to an rvalue reference type. 1792 // Materialize a temporary to store the result of the conversion. 1793 SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcExpr.get()->getType(), 1794 SrcExpr.get(), 1795 /*IsLValueReference*/ false); 1796 1797 return TC_Success; 1798} 1799 1800// Checks for undefined behavior in reinterpret_cast. 1801// The cases that is checked for is: 1802// *reinterpret_cast<T*>(&a) 1803// reinterpret_cast<T&>(a) 1804// where accessing 'a' as type 'T' will result in undefined behavior. 1805void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType, 1806 bool IsDereference, 1807 SourceRange Range) { 1808 unsigned DiagID = IsDereference ? 1809 diag::warn_pointer_indirection_from_incompatible_type : 1810 diag::warn_undefined_reinterpret_cast; 1811 1812 if (Diags.isIgnored(DiagID, Range.getBegin())) 1813 return; 1814 1815 QualType SrcTy, DestTy; 1816 if (IsDereference) { 1817 if (!SrcType->getAs<PointerType>() || !DestType->getAs<PointerType>()) { 1818 return; 1819 } 1820 SrcTy = SrcType->getPointeeType(); 1821 DestTy = DestType->getPointeeType(); 1822 } else { 1823 if (!DestType->getAs<ReferenceType>()) { 1824 return; 1825 } 1826 SrcTy = SrcType; 1827 DestTy = DestType->getPointeeType(); 1828 } 1829 1830 // Cast is compatible if the types are the same. 1831 if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) { 1832 return; 1833 } 1834 // or one of the types is a char or void type 1835 if (DestTy->isAnyCharacterType() || DestTy->isVoidType() || 1836 SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) { 1837 return; 1838 } 1839 // or one of the types is a tag type. 1840 if (SrcTy->getAs<TagType>() || DestTy->getAs<TagType>()) { 1841 return; 1842 } 1843 1844 // FIXME: Scoped enums? 1845 if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) || 1846 (SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) { 1847 if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) { 1848 return; 1849 } 1850 } 1851 1852 Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range; 1853} 1854 1855static void DiagnoseCastOfObjCSEL(Sema &Self, const ExprResult &SrcExpr, 1856 QualType DestType) { 1857 QualType SrcType = SrcExpr.get()->getType(); 1858 if (Self.Context.hasSameType(SrcType, DestType)) 1859 return; 1860 if (const PointerType *SrcPtrTy = SrcType->getAs<PointerType>()) 1861 if (SrcPtrTy->isObjCSelType()) { 1862 QualType DT = DestType; 1863 if (isa<PointerType>(DestType)) 1864 DT = DestType->getPointeeType(); 1865 if (!DT.getUnqualifiedType()->isVoidType()) 1866 Self.Diag(SrcExpr.get()->getExprLoc(), 1867 diag::warn_cast_pointer_from_sel) 1868 << SrcType << DestType << SrcExpr.get()->getSourceRange(); 1869 } 1870} 1871 1872/// Diagnose casts that change the calling convention of a pointer to a function 1873/// defined in the current TU. 1874static void DiagnoseCallingConvCast(Sema &Self, const ExprResult &SrcExpr, 1875 QualType DstType, SourceRange OpRange) { 1876 // Check if this cast would change the calling convention of a function 1877 // pointer type. 1878 QualType SrcType = SrcExpr.get()->getType(); 1879 if (Self.Context.hasSameType(SrcType, DstType) || 1880 !SrcType->isFunctionPointerType() || !DstType->isFunctionPointerType()) 1881 return; 1882 const auto *SrcFTy = 1883 SrcType->castAs<PointerType>()->getPointeeType()->castAs<FunctionType>(); 1884 const auto *DstFTy = 1885 DstType->castAs<PointerType>()->getPointeeType()->castAs<FunctionType>(); 1886 CallingConv SrcCC = SrcFTy->getCallConv(); 1887 CallingConv DstCC = DstFTy->getCallConv(); 1888 if (SrcCC == DstCC) 1889 return; 1890 1891 // We have a calling convention cast. Check if the source is a pointer to a 1892 // known, specific function that has already been defined. 1893 Expr *Src = SrcExpr.get()->IgnoreParenImpCasts(); 1894 if (auto *UO = dyn_cast<UnaryOperator>(Src)) 1895 if (UO->getOpcode() == UO_AddrOf) 1896 Src = UO->getSubExpr()->IgnoreParenImpCasts(); 1897 auto *DRE = dyn_cast<DeclRefExpr>(Src); 1898 if (!DRE) 1899 return; 1900 auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl()); 1901 if (!FD) 1902 return; 1903 1904 // Only warn if we are casting from the default convention to a non-default 1905 // convention. This can happen when the programmer forgot to apply the calling 1906 // convention to the function declaration and then inserted this cast to 1907 // satisfy the type system. 1908 CallingConv DefaultCC = Self.getASTContext().getDefaultCallingConvention( 1909 FD->isVariadic(), FD->isCXXInstanceMember()); 1910 if (DstCC == DefaultCC || SrcCC != DefaultCC) 1911 return; 1912 1913 // Diagnose this cast, as it is probably bad. 1914 StringRef SrcCCName = FunctionType::getNameForCallConv(SrcCC); 1915 StringRef DstCCName = FunctionType::getNameForCallConv(DstCC); 1916 Self.Diag(OpRange.getBegin(), diag::warn_cast_calling_conv) 1917 << SrcCCName << DstCCName << OpRange; 1918 1919 // The checks above are cheaper than checking if the diagnostic is enabled. 1920 // However, it's worth checking if the warning is enabled before we construct 1921 // a fixit. 1922 if (Self.Diags.isIgnored(diag::warn_cast_calling_conv, OpRange.getBegin())) 1923 return; 1924 1925 // Try to suggest a fixit to change the calling convention of the function 1926 // whose address was taken. Try to use the latest macro for the convention. 1927 // For example, users probably want to write "WINAPI" instead of "__stdcall" 1928 // to match the Windows header declarations. 1929 SourceLocation NameLoc = FD->getFirstDecl()->getNameInfo().getLoc(); 1930 Preprocessor &PP = Self.getPreprocessor(); 1931 SmallVector<TokenValue, 6> AttrTokens; 1932 SmallString<64> CCAttrText; 1933 llvm::raw_svector_ostream OS(CCAttrText); 1934 if (Self.getLangOpts().MicrosoftExt) { 1935 // __stdcall or __vectorcall 1936 OS << "__" << DstCCName; 1937 IdentifierInfo *II = PP.getIdentifierInfo(OS.str()); 1938 AttrTokens.push_back(II->isKeyword(Self.getLangOpts()) 1939 ? TokenValue(II->getTokenID()) 1940 : TokenValue(II)); 1941 } else { 1942 // __attribute__((stdcall)) or __attribute__((vectorcall)) 1943 OS << "__attribute__((" << DstCCName << "))"; 1944 AttrTokens.push_back(tok::kw___attribute); 1945 AttrTokens.push_back(tok::l_paren); 1946 AttrTokens.push_back(tok::l_paren); 1947 IdentifierInfo *II = PP.getIdentifierInfo(DstCCName); 1948 AttrTokens.push_back(II->isKeyword(Self.getLangOpts()) 1949 ? TokenValue(II->getTokenID()) 1950 : TokenValue(II)); 1951 AttrTokens.push_back(tok::r_paren); 1952 AttrTokens.push_back(tok::r_paren); 1953 } 1954 StringRef AttrSpelling = PP.getLastMacroWithSpelling(NameLoc, AttrTokens); 1955 if (!AttrSpelling.empty()) 1956 CCAttrText = AttrSpelling; 1957 OS << ' '; 1958 Self.Diag(NameLoc, diag::note_change_calling_conv_fixit) 1959 << FD << DstCCName << FixItHint::CreateInsertion(NameLoc, CCAttrText); 1960} 1961 1962static void checkIntToPointerCast(bool CStyle, SourceLocation Loc, 1963 const Expr *SrcExpr, QualType DestType, 1964 Sema &Self) { 1965 QualType SrcType = SrcExpr->getType(); 1966 1967 // Not warning on reinterpret_cast, boolean, constant expressions, etc 1968 // are not explicit design choices, but consistent with GCC's behavior. 1969 // Feel free to modify them if you've reason/evidence for an alternative. 1970 if (CStyle && SrcType->isIntegralType(Self.Context) 1971 && !SrcType->isBooleanType() 1972 && !SrcType->isEnumeralType() 1973 && !SrcExpr->isIntegerConstantExpr(Self.Context) 1974 && Self.Context.getTypeSize(DestType) > 1975 Self.Context.getTypeSize(SrcType)) { 1976 // Separate between casts to void* and non-void* pointers. 1977 // Some APIs use (abuse) void* for something like a user context, 1978 // and often that value is an integer even if it isn't a pointer itself. 1979 // Having a separate warning flag allows users to control the warning 1980 // for their workflow. 1981 unsigned Diag = DestType->isVoidPointerType() ? 1982 diag::warn_int_to_void_pointer_cast 1983 : diag::warn_int_to_pointer_cast; 1984 Self.Diag(Loc, Diag) << SrcType << DestType; 1985 } 1986} 1987 1988static bool fixOverloadedReinterpretCastExpr(Sema &Self, QualType DestType, 1989 ExprResult &Result) { 1990 // We can only fix an overloaded reinterpret_cast if 1991 // - it is a template with explicit arguments that resolves to an lvalue 1992 // unambiguously, or 1993 // - it is the only function in an overload set that may have its address 1994 // taken. 1995 1996 Expr *E = Result.get(); 1997 // TODO: what if this fails because of DiagnoseUseOfDecl or something 1998 // like it? 1999 if (Self.ResolveAndFixSingleFunctionTemplateSpecialization( 2000 Result, 2001 Expr::getValueKindForType(DestType) == VK_RValue // Convert Fun to Ptr 2002 ) && 2003 Result.isUsable()) 2004 return true; 2005 2006 // No guarantees that ResolveAndFixSingleFunctionTemplateSpecialization 2007 // preserves Result. 2008 Result = E; 2009 if (!Self.resolveAndFixAddressOfOnlyViableOverloadCandidate( 2010 Result, /*DoFunctionPointerConversion=*/true)) 2011 return false; 2012 return Result.isUsable(); 2013} 2014 2015static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr, 2016 QualType DestType, bool CStyle, 2017 SourceRange OpRange, 2018 unsigned &msg, 2019 CastKind &Kind) { 2020 bool IsLValueCast = false; 2021 2022 DestType = Self.Context.getCanonicalType(DestType); 2023 QualType SrcType = SrcExpr.get()->getType(); 2024 2025 // Is the source an overloaded name? (i.e. &foo) 2026 // If so, reinterpret_cast generally can not help us here (13.4, p1, bullet 5) 2027 if (SrcType == Self.Context.OverloadTy) { 2028 ExprResult FixedExpr = SrcExpr; 2029 if (!fixOverloadedReinterpretCastExpr(Self, DestType, FixedExpr)) 2030 return TC_NotApplicable; 2031 2032 assert(FixedExpr.isUsable() && "Invalid result fixing overloaded expr"); 2033 SrcExpr = FixedExpr; 2034 SrcType = SrcExpr.get()->getType(); 2035 } 2036 2037 if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) { 2038 if (!SrcExpr.get()->isGLValue()) { 2039 // Cannot cast non-glvalue to (lvalue or rvalue) reference type. See the 2040 // similar comment in const_cast. 2041 msg = diag::err_bad_cxx_cast_rvalue; 2042 return TC_NotApplicable; 2043 } 2044 2045 if (!CStyle) { 2046 Self.CheckCompatibleReinterpretCast(SrcType, DestType, 2047 /*IsDereference=*/false, OpRange); 2048 } 2049 2050 // C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the 2051 // same effect as the conversion *reinterpret_cast<T*>(&x) with the 2052 // built-in & and * operators. 2053 2054 const char *inappropriate = nullptr; 2055 switch (SrcExpr.get()->getObjectKind()) { 2056 case OK_Ordinary: 2057 break; 2058 case OK_BitField: 2059 msg = diag::err_bad_cxx_cast_bitfield; 2060 return TC_NotApplicable; 2061 // FIXME: Use a specific diagnostic for the rest of these cases. 2062 case OK_VectorComponent: inappropriate = "vector element"; break; 2063 case OK_ObjCProperty: inappropriate = "property expression"; break; 2064 case OK_ObjCSubscript: inappropriate = "container subscripting expression"; 2065 break; 2066 } 2067 if (inappropriate) { 2068 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference) 2069 << inappropriate << DestType 2070 << OpRange << SrcExpr.get()->getSourceRange(); 2071 msg = 0; SrcExpr = ExprError(); 2072 return TC_NotApplicable; 2073 } 2074 2075 // This code does this transformation for the checked types. 2076 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 2077 SrcType = Self.Context.getPointerType(SrcType); 2078 2079 IsLValueCast = true; 2080 } 2081 2082 // Canonicalize source for comparison. 2083 SrcType = Self.Context.getCanonicalType(SrcType); 2084 2085 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(), 2086 *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 2087 if (DestMemPtr && SrcMemPtr) { 2088 // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1" 2089 // can be explicitly converted to an rvalue of type "pointer to member 2090 // of Y of type T2" if T1 and T2 are both function types or both object 2091 // types. 2092 if (DestMemPtr->isMemberFunctionPointer() != 2093 SrcMemPtr->isMemberFunctionPointer()) 2094 return TC_NotApplicable; 2095 2096 if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) { 2097 // We need to determine the inheritance model that the class will use if 2098 // haven't yet. 2099 (void)Self.isCompleteType(OpRange.getBegin(), SrcType); 2100 (void)Self.isCompleteType(OpRange.getBegin(), DestType); 2101 } 2102 2103 // Don't allow casting between member pointers of different sizes. 2104 if (Self.Context.getTypeSize(DestMemPtr) != 2105 Self.Context.getTypeSize(SrcMemPtr)) { 2106 msg = diag::err_bad_cxx_cast_member_pointer_size; 2107 return TC_Failed; 2108 } 2109 2110 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away 2111 // constness. 2112 // A reinterpret_cast followed by a const_cast can, though, so in C-style, 2113 // we accept it. 2114 if (auto CACK = 2115 CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, 2116 /*CheckObjCLifetime=*/CStyle)) 2117 return getCastAwayConstnessCastKind(CACK, msg); 2118 2119 // A valid member pointer cast. 2120 assert(!IsLValueCast); 2121 Kind = CK_ReinterpretMemberPointer; 2122 return TC_Success; 2123 } 2124 2125 // See below for the enumeral issue. 2126 if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) { 2127 // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral 2128 // type large enough to hold it. A value of std::nullptr_t can be 2129 // converted to an integral type; the conversion has the same meaning 2130 // and validity as a conversion of (void*)0 to the integral type. 2131 if (Self.Context.getTypeSize(SrcType) > 2132 Self.Context.getTypeSize(DestType)) { 2133 msg = diag::err_bad_reinterpret_cast_small_int; 2134 return TC_Failed; 2135 } 2136 Kind = CK_PointerToIntegral; 2137 return TC_Success; 2138 } 2139 2140 // Allow reinterpret_casts between vectors of the same size and 2141 // between vectors and integers of the same size. 2142 bool destIsVector = DestType->isVectorType(); 2143 bool srcIsVector = SrcType->isVectorType(); 2144 if (srcIsVector || destIsVector) { 2145 // The non-vector type, if any, must have integral type. This is 2146 // the same rule that C vector casts use; note, however, that enum 2147 // types are not integral in C++. 2148 if ((!destIsVector && !DestType->isIntegralType(Self.Context)) || 2149 (!srcIsVector && !SrcType->isIntegralType(Self.Context))) 2150 return TC_NotApplicable; 2151 2152 // The size we want to consider is eltCount * eltSize. 2153 // That's exactly what the lax-conversion rules will check. 2154 if (Self.areLaxCompatibleVectorTypes(SrcType, DestType)) { 2155 Kind = CK_BitCast; 2156 return TC_Success; 2157 } 2158 2159 // Otherwise, pick a reasonable diagnostic. 2160 if (!destIsVector) 2161 msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size; 2162 else if (!srcIsVector) 2163 msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size; 2164 else 2165 msg = diag::err_bad_cxx_cast_vector_to_vector_different_size; 2166 2167 return TC_Failed; 2168 } 2169 2170 if (SrcType == DestType) { 2171 // C++ 5.2.10p2 has a note that mentions that, subject to all other 2172 // restrictions, a cast to the same type is allowed so long as it does not 2173 // cast away constness. In C++98, the intent was not entirely clear here, 2174 // since all other paragraphs explicitly forbid casts to the same type. 2175 // C++11 clarifies this case with p2. 2176 // 2177 // The only allowed types are: integral, enumeration, pointer, or 2178 // pointer-to-member types. We also won't restrict Obj-C pointers either. 2179 Kind = CK_NoOp; 2180 TryCastResult Result = TC_NotApplicable; 2181 if (SrcType->isIntegralOrEnumerationType() || 2182 SrcType->isAnyPointerType() || 2183 SrcType->isMemberPointerType() || 2184 SrcType->isBlockPointerType()) { 2185 Result = TC_Success; 2186 } 2187 return Result; 2188 } 2189 2190 bool destIsPtr = DestType->isAnyPointerType() || 2191 DestType->isBlockPointerType(); 2192 bool srcIsPtr = SrcType->isAnyPointerType() || 2193 SrcType->isBlockPointerType(); 2194 if (!destIsPtr && !srcIsPtr) { 2195 // Except for std::nullptr_t->integer and lvalue->reference, which are 2196 // handled above, at least one of the two arguments must be a pointer. 2197 return TC_NotApplicable; 2198 } 2199 2200 if (DestType->isIntegralType(Self.Context)) { 2201 assert(srcIsPtr && "One type must be a pointer"); 2202 // C++ 5.2.10p4: A pointer can be explicitly converted to any integral 2203 // type large enough to hold it; except in Microsoft mode, where the 2204 // integral type size doesn't matter (except we don't allow bool). 2205 bool MicrosoftException = Self.getLangOpts().MicrosoftExt && 2206 !DestType->isBooleanType(); 2207 if ((Self.Context.getTypeSize(SrcType) > 2208 Self.Context.getTypeSize(DestType)) && 2209 !MicrosoftException) { 2210 msg = diag::err_bad_reinterpret_cast_small_int; 2211 return TC_Failed; 2212 } 2213 Kind = CK_PointerToIntegral; 2214 return TC_Success; 2215 } 2216 2217 if (SrcType->isIntegralOrEnumerationType()) { 2218 assert(destIsPtr && "One type must be a pointer"); 2219 checkIntToPointerCast(CStyle, OpRange.getBegin(), SrcExpr.get(), DestType, 2220 Self); 2221 // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly 2222 // converted to a pointer. 2223 // C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not 2224 // necessarily converted to a null pointer value.] 2225 Kind = CK_IntegralToPointer; 2226 return TC_Success; 2227 } 2228 2229 if (!destIsPtr || !srcIsPtr) { 2230 // With the valid non-pointer conversions out of the way, we can be even 2231 // more stringent. 2232 return TC_NotApplicable; 2233 } 2234 2235 // Cannot convert between block pointers and Objective-C object pointers. 2236 if ((SrcType->isBlockPointerType() && DestType->isObjCObjectPointerType()) || 2237 (DestType->isBlockPointerType() && SrcType->isObjCObjectPointerType())) 2238 return TC_NotApplicable; 2239 2240 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness. 2241 // The C-style cast operator can. 2242 TryCastResult SuccessResult = TC_Success; 2243 if (auto CACK = 2244 CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, 2245 /*CheckObjCLifetime=*/CStyle)) 2246 SuccessResult = getCastAwayConstnessCastKind(CACK, msg); 2247 2248 if (IsAddressSpaceConversion(SrcType, DestType)) { 2249 Kind = CK_AddressSpaceConversion; 2250 assert(SrcType->isPointerType() && DestType->isPointerType()); 2251 if (!CStyle && 2252 !DestType->getPointeeType().getQualifiers().isAddressSpaceSupersetOf( 2253 SrcType->getPointeeType().getQualifiers())) { 2254 SuccessResult = TC_Failed; 2255 } 2256 } else if (IsLValueCast) { 2257 Kind = CK_LValueBitCast; 2258 } else if (DestType->isObjCObjectPointerType()) { 2259 Kind = Self.PrepareCastToObjCObjectPointer(SrcExpr); 2260 } else if (DestType->isBlockPointerType()) { 2261 if (!SrcType->isBlockPointerType()) { 2262 Kind = CK_AnyPointerToBlockPointerCast; 2263 } else { 2264 Kind = CK_BitCast; 2265 } 2266 } else { 2267 Kind = CK_BitCast; 2268 } 2269 2270 // Any pointer can be cast to an Objective-C pointer type with a C-style 2271 // cast. 2272 if (CStyle && DestType->isObjCObjectPointerType()) { 2273 return SuccessResult; 2274 } 2275 if (CStyle) 2276 DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType); 2277 2278 DiagnoseCallingConvCast(Self, SrcExpr, DestType, OpRange); 2279 2280 // Not casting away constness, so the only remaining check is for compatible 2281 // pointer categories. 2282 2283 if (SrcType->isFunctionPointerType()) { 2284 if (DestType->isFunctionPointerType()) { 2285 // C++ 5.2.10p6: A pointer to a function can be explicitly converted to 2286 // a pointer to a function of a different type. 2287 return SuccessResult; 2288 } 2289 2290 // C++0x 5.2.10p8: Converting a pointer to a function into a pointer to 2291 // an object type or vice versa is conditionally-supported. 2292 // Compilers support it in C++03 too, though, because it's necessary for 2293 // casting the return value of dlsym() and GetProcAddress(). 2294 // FIXME: Conditionally-supported behavior should be configurable in the 2295 // TargetInfo or similar. 2296 Self.Diag(OpRange.getBegin(), 2297 Self.getLangOpts().CPlusPlus11 ? 2298 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj) 2299 << OpRange; 2300 return SuccessResult; 2301 } 2302 2303 if (DestType->isFunctionPointerType()) { 2304 // See above. 2305 Self.Diag(OpRange.getBegin(), 2306 Self.getLangOpts().CPlusPlus11 ? 2307 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj) 2308 << OpRange; 2309 return SuccessResult; 2310 } 2311 2312 // C++ 5.2.10p7: A pointer to an object can be explicitly converted to 2313 // a pointer to an object of different type. 2314 // Void pointers are not specified, but supported by every compiler out there. 2315 // So we finish by allowing everything that remains - it's got to be two 2316 // object pointers. 2317 return SuccessResult; 2318} 2319 2320static TryCastResult TryAddressSpaceCast(Sema &Self, ExprResult &SrcExpr, 2321 QualType DestType, bool CStyle, 2322 unsigned &msg) { 2323 if (!Self.getLangOpts().OpenCL) 2324 // FIXME: As compiler doesn't have any information about overlapping addr 2325 // spaces at the moment we have to be permissive here. 2326 return TC_NotApplicable; 2327 // Even though the logic below is general enough and can be applied to 2328 // non-OpenCL mode too, we fast-path above because no other languages 2329 // define overlapping address spaces currently. 2330 auto SrcType = SrcExpr.get()->getType(); 2331 auto SrcPtrType = SrcType->getAs<PointerType>(); 2332 if (!SrcPtrType) 2333 return TC_NotApplicable; 2334 auto DestPtrType = DestType->getAs<PointerType>(); 2335 if (!DestPtrType) 2336 return TC_NotApplicable; 2337 auto SrcPointeeType = SrcPtrType->getPointeeType(); 2338 auto DestPointeeType = DestPtrType->getPointeeType(); 2339 if (SrcPointeeType.getAddressSpace() == DestPointeeType.getAddressSpace()) 2340 return TC_NotApplicable; 2341 if (!DestPtrType->isAddressSpaceOverlapping(*SrcPtrType)) { 2342 msg = diag::err_bad_cxx_cast_addr_space_mismatch; 2343 return TC_Failed; 2344 } 2345 auto SrcPointeeTypeWithoutAS = 2346 Self.Context.removeAddrSpaceQualType(SrcPointeeType.getCanonicalType()); 2347 auto DestPointeeTypeWithoutAS = 2348 Self.Context.removeAddrSpaceQualType(DestPointeeType.getCanonicalType()); 2349 return Self.Context.hasSameType(SrcPointeeTypeWithoutAS, 2350 DestPointeeTypeWithoutAS) 2351 ? TC_Success 2352 : TC_NotApplicable; 2353} 2354 2355void CastOperation::checkAddressSpaceCast(QualType SrcType, QualType DestType) { 2356 // In OpenCL only conversions between pointers to objects in overlapping 2357 // addr spaces are allowed. v2.0 s6.5.5 - Generic addr space overlaps 2358 // with any named one, except for constant. 2359 2360 // Converting the top level pointee addrspace is permitted for compatible 2361 // addrspaces (such as 'generic int *' to 'local int *' or vice versa), but 2362 // if any of the nested pointee addrspaces differ, we emit a warning 2363 // regardless of addrspace compatibility. This makes 2364 // local int ** p; 2365 // return (generic int **) p; 2366 // warn even though local -> generic is permitted. 2367 if (Self.getLangOpts().OpenCL) { 2368 const Type *DestPtr, *SrcPtr; 2369 bool Nested = false; 2370 unsigned DiagID = diag::err_typecheck_incompatible_address_space; 2371 DestPtr = Self.getASTContext().getCanonicalType(DestType.getTypePtr()), 2372 SrcPtr = Self.getASTContext().getCanonicalType(SrcType.getTypePtr()); 2373 2374 while (isa<PointerType>(DestPtr) && isa<PointerType>(SrcPtr)) { 2375 const PointerType *DestPPtr = cast<PointerType>(DestPtr); 2376 const PointerType *SrcPPtr = cast<PointerType>(SrcPtr); 2377 QualType DestPPointee = DestPPtr->getPointeeType(); 2378 QualType SrcPPointee = SrcPPtr->getPointeeType(); 2379 if (Nested ? DestPPointee.getAddressSpace() != 2380 SrcPPointee.getAddressSpace() 2381 : !DestPPtr->isAddressSpaceOverlapping(*SrcPPtr)) { 2382 Self.Diag(OpRange.getBegin(), DiagID) 2383 << SrcType << DestType << Sema::AA_Casting 2384 << SrcExpr.get()->getSourceRange(); 2385 if (!Nested) 2386 SrcExpr = ExprError(); 2387 return; 2388 } 2389 2390 DestPtr = DestPPtr->getPointeeType().getTypePtr(); 2391 SrcPtr = SrcPPtr->getPointeeType().getTypePtr(); 2392 Nested = true; 2393 DiagID = diag::ext_nested_pointer_qualifier_mismatch; 2394 } 2395 } 2396} 2397 2398void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle, 2399 bool ListInitialization) { 2400 assert(Self.getLangOpts().CPlusPlus); 2401 2402 // Handle placeholders. 2403 if (isPlaceholder()) { 2404 // C-style casts can resolve __unknown_any types. 2405 if (claimPlaceholder(BuiltinType::UnknownAny)) { 2406 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 2407 SrcExpr.get(), Kind, 2408 ValueKind, BasePath); 2409 return; 2410 } 2411 2412 checkNonOverloadPlaceholders(); 2413 if (SrcExpr.isInvalid()) 2414 return; 2415 } 2416 2417 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 2418 // This test is outside everything else because it's the only case where 2419 // a non-lvalue-reference target type does not lead to decay. 2420 if (DestType->isVoidType()) { 2421 Kind = CK_ToVoid; 2422 2423 if (claimPlaceholder(BuiltinType::Overload)) { 2424 Self.ResolveAndFixSingleFunctionTemplateSpecialization( 2425 SrcExpr, /* Decay Function to ptr */ false, 2426 /* Complain */ true, DestRange, DestType, 2427 diag::err_bad_cstyle_cast_overload); 2428 if (SrcExpr.isInvalid()) 2429 return; 2430 } 2431 2432 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get()); 2433 return; 2434 } 2435 2436 // If the type is dependent, we won't do any other semantic analysis now. 2437 if (DestType->isDependentType() || SrcExpr.get()->isTypeDependent() || 2438 SrcExpr.get()->isValueDependent()) { 2439 assert(Kind == CK_Dependent); 2440 return; 2441 } 2442 2443 if (ValueKind == VK_RValue && !DestType->isRecordType() && 2444 !isPlaceholder(BuiltinType::Overload)) { 2445 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 2446 if (SrcExpr.isInvalid()) 2447 return; 2448 } 2449 2450 // AltiVec vector initialization with a single literal. 2451 if (const VectorType *vecTy = DestType->getAs<VectorType>()) 2452 if (vecTy->getVectorKind() == VectorType::AltiVecVector 2453 && (SrcExpr.get()->getType()->isIntegerType() 2454 || SrcExpr.get()->getType()->isFloatingType())) { 2455 Kind = CK_VectorSplat; 2456 SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get()); 2457 return; 2458 } 2459 2460 // C++ [expr.cast]p5: The conversions performed by 2461 // - a const_cast, 2462 // - a static_cast, 2463 // - a static_cast followed by a const_cast, 2464 // - a reinterpret_cast, or 2465 // - a reinterpret_cast followed by a const_cast, 2466 // can be performed using the cast notation of explicit type conversion. 2467 // [...] If a conversion can be interpreted in more than one of the ways 2468 // listed above, the interpretation that appears first in the list is used, 2469 // even if a cast resulting from that interpretation is ill-formed. 2470 // In plain language, this means trying a const_cast ... 2471 // Note that for address space we check compatibility after const_cast. 2472 unsigned msg = diag::err_bad_cxx_cast_generic; 2473 TryCastResult tcr = TryConstCast(Self, SrcExpr, DestType, 2474 /*CStyle*/ true, msg); 2475 if (SrcExpr.isInvalid()) 2476 return; 2477 if (isValidCast(tcr)) 2478 Kind = CK_NoOp; 2479 2480 Sema::CheckedConversionKind CCK = 2481 FunctionalStyle ? Sema::CCK_FunctionalCast : Sema::CCK_CStyleCast; 2482 if (tcr == TC_NotApplicable) { 2483 tcr = TryAddressSpaceCast(Self, SrcExpr, DestType, /*CStyle*/ true, msg); 2484 if (SrcExpr.isInvalid()) 2485 return; 2486 2487 if (isValidCast(tcr)) 2488 Kind = CK_AddressSpaceConversion; 2489 2490 if (tcr == TC_NotApplicable) { 2491 // ... or if that is not possible, a static_cast, ignoring const, ... 2492 tcr = TryStaticCast(Self, SrcExpr, DestType, CCK, OpRange, msg, Kind, 2493 BasePath, ListInitialization); 2494 if (SrcExpr.isInvalid()) 2495 return; 2496 2497 if (tcr == TC_NotApplicable) { 2498 // ... and finally a reinterpret_cast, ignoring const. 2499 tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/ true, 2500 OpRange, msg, Kind); 2501 if (SrcExpr.isInvalid()) 2502 return; 2503 } 2504 } 2505 } 2506 2507 if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() && 2508 isValidCast(tcr)) 2509 checkObjCConversion(CCK); 2510 2511 if (tcr != TC_Success && msg != 0) { 2512 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 2513 DeclAccessPair Found; 2514 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 2515 DestType, 2516 /*Complain*/ true, 2517 Found); 2518 if (Fn) { 2519 // If DestType is a function type (not to be confused with the function 2520 // pointer type), it will be possible to resolve the function address, 2521 // but the type cast should be considered as failure. 2522 OverloadExpr *OE = OverloadExpr::find(SrcExpr.get()).Expression; 2523 Self.Diag(OpRange.getBegin(), diag::err_bad_cstyle_cast_overload) 2524 << OE->getName() << DestType << OpRange 2525 << OE->getQualifierLoc().getSourceRange(); 2526 Self.NoteAllOverloadCandidates(SrcExpr.get()); 2527 } 2528 } else { 2529 diagnoseBadCast(Self, msg, (FunctionalStyle ? CT_Functional : CT_CStyle), 2530 OpRange, SrcExpr.get(), DestType, ListInitialization); 2531 } 2532 } 2533 2534 if (isValidCast(tcr)) { 2535 if (Kind == CK_BitCast) 2536 checkCastAlign(); 2537 } else { 2538 SrcExpr = ExprError(); 2539 } 2540} 2541 2542/// DiagnoseBadFunctionCast - Warn whenever a function call is cast to a 2543/// non-matching type. Such as enum function call to int, int call to 2544/// pointer; etc. Cast to 'void' is an exception. 2545static void DiagnoseBadFunctionCast(Sema &Self, const ExprResult &SrcExpr, 2546 QualType DestType) { 2547 if (Self.Diags.isIgnored(diag::warn_bad_function_cast, 2548 SrcExpr.get()->getExprLoc())) 2549 return; 2550 2551 if (!isa<CallExpr>(SrcExpr.get())) 2552 return; 2553 2554 QualType SrcType = SrcExpr.get()->getType(); 2555 if (DestType.getUnqualifiedType()->isVoidType()) 2556 return; 2557 if ((SrcType->isAnyPointerType() || SrcType->isBlockPointerType()) 2558 && (DestType->isAnyPointerType() || DestType->isBlockPointerType())) 2559 return; 2560 if (SrcType->isIntegerType() && DestType->isIntegerType() && 2561 (SrcType->isBooleanType() == DestType->isBooleanType()) && 2562 (SrcType->isEnumeralType() == DestType->isEnumeralType())) 2563 return; 2564 if (SrcType->isRealFloatingType() && DestType->isRealFloatingType()) 2565 return; 2566 if (SrcType->isEnumeralType() && DestType->isEnumeralType()) 2567 return; 2568 if (SrcType->isComplexType() && DestType->isComplexType()) 2569 return; 2570 if (SrcType->isComplexIntegerType() && DestType->isComplexIntegerType()) 2571 return; 2572 2573 Self.Diag(SrcExpr.get()->getExprLoc(), 2574 diag::warn_bad_function_cast) 2575 << SrcType << DestType << SrcExpr.get()->getSourceRange(); 2576} 2577 2578/// Check the semantics of a C-style cast operation, in C. 2579void CastOperation::CheckCStyleCast() { 2580 assert(!Self.getLangOpts().CPlusPlus); 2581 2582 // C-style casts can resolve __unknown_any types. 2583 if (claimPlaceholder(BuiltinType::UnknownAny)) { 2584 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 2585 SrcExpr.get(), Kind, 2586 ValueKind, BasePath); 2587 return; 2588 } 2589 2590 // C99 6.5.4p2: the cast type needs to be void or scalar and the expression 2591 // type needs to be scalar. 2592 if (DestType->isVoidType()) { 2593 // We don't necessarily do lvalue-to-rvalue conversions on this. 2594 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get()); 2595 if (SrcExpr.isInvalid()) 2596 return; 2597 2598 // Cast to void allows any expr type. 2599 Kind = CK_ToVoid; 2600 return; 2601 } 2602 2603 // Overloads are allowed with C extensions, so we need to support them. 2604 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 2605 DeclAccessPair DAP; 2606 if (FunctionDecl *FD = Self.ResolveAddressOfOverloadedFunction( 2607 SrcExpr.get(), DestType, /*Complain=*/true, DAP)) 2608 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr.get(), DAP, FD); 2609 else 2610 return; 2611 assert(SrcExpr.isUsable()); 2612 } 2613 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get()); 2614 if (SrcExpr.isInvalid()) 2615 return; 2616 QualType SrcType = SrcExpr.get()->getType(); 2617 2618 assert(!SrcType->isPlaceholderType()); 2619 2620 checkAddressSpaceCast(SrcType, DestType); 2621 if (SrcExpr.isInvalid()) 2622 return; 2623 2624 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 2625 diag::err_typecheck_cast_to_incomplete)) { 2626 SrcExpr = ExprError(); 2627 return; 2628 } 2629 2630 if (!DestType->isScalarType() && !DestType->isVectorType()) { 2631 const RecordType *DestRecordTy = DestType->getAs<RecordType>(); 2632 2633 if (DestRecordTy && Self.Context.hasSameUnqualifiedType(DestType, SrcType)){ 2634 // GCC struct/union extension: allow cast to self. 2635 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_nonscalar) 2636 << DestType << SrcExpr.get()->getSourceRange(); 2637 Kind = CK_NoOp; 2638 return; 2639 } 2640 2641 // GCC's cast to union extension. 2642 if (DestRecordTy && DestRecordTy->getDecl()->isUnion()) { 2643 RecordDecl *RD = DestRecordTy->getDecl(); 2644 if (CastExpr::getTargetFieldForToUnionCast(RD, SrcType)) { 2645 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union) 2646 << SrcExpr.get()->getSourceRange(); 2647 Kind = CK_ToUnion; 2648 return; 2649 } else { 2650 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cast_to_union_no_type) 2651 << SrcType << SrcExpr.get()->getSourceRange(); 2652 SrcExpr = ExprError(); 2653 return; 2654 } 2655 } 2656 2657 // OpenCL v2.0 s6.13.10 - Allow casts from '0' to event_t type. 2658 if (Self.getLangOpts().OpenCL && DestType->isEventT()) { 2659 Expr::EvalResult Result; 2660 if (SrcExpr.get()->EvaluateAsInt(Result, Self.Context)) { 2661 llvm::APSInt CastInt = Result.Val.getInt(); 2662 if (0 == CastInt) { 2663 Kind = CK_ZeroToOCLOpaqueType; 2664 return; 2665 } 2666 Self.Diag(OpRange.getBegin(), 2667 diag::err_opencl_cast_non_zero_to_event_t) 2668 << CastInt.toString(10) << SrcExpr.get()->getSourceRange(); 2669 SrcExpr = ExprError(); 2670 return; 2671 } 2672 } 2673 2674 // Reject any other conversions to non-scalar types. 2675 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cond_expect_scalar) 2676 << DestType << SrcExpr.get()->getSourceRange(); 2677 SrcExpr = ExprError(); 2678 return; 2679 } 2680 2681 // The type we're casting to is known to be a scalar or vector. 2682 2683 // Require the operand to be a scalar or vector. 2684 if (!SrcType->isScalarType() && !SrcType->isVectorType()) { 2685 Self.Diag(SrcExpr.get()->getExprLoc(), 2686 diag::err_typecheck_expect_scalar_operand) 2687 << SrcType << SrcExpr.get()->getSourceRange(); 2688 SrcExpr = ExprError(); 2689 return; 2690 } 2691 2692 if (DestType->isExtVectorType()) { 2693 SrcExpr = Self.CheckExtVectorCast(OpRange, DestType, SrcExpr.get(), Kind); 2694 return; 2695 } 2696 2697 if (const VectorType *DestVecTy = DestType->getAs<VectorType>()) { 2698 if (DestVecTy->getVectorKind() == VectorType::AltiVecVector && 2699 (SrcType->isIntegerType() || SrcType->isFloatingType())) { 2700 Kind = CK_VectorSplat; 2701 SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get()); 2702 } else if (Self.CheckVectorCast(OpRange, DestType, SrcType, Kind)) { 2703 SrcExpr = ExprError(); 2704 } 2705 return; 2706 } 2707 2708 if (SrcType->isVectorType()) { 2709 if (Self.CheckVectorCast(OpRange, SrcType, DestType, Kind)) 2710 SrcExpr = ExprError(); 2711 return; 2712 } 2713 2714 // The source and target types are both scalars, i.e. 2715 // - arithmetic types (fundamental, enum, and complex) 2716 // - all kinds of pointers 2717 // Note that member pointers were filtered out with C++, above. 2718 2719 if (isa<ObjCSelectorExpr>(SrcExpr.get())) { 2720 Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_selector_expr); 2721 SrcExpr = ExprError(); 2722 return; 2723 } 2724 2725 // If either type is a pointer, the other type has to be either an 2726 // integer or a pointer. 2727 if (!DestType->isArithmeticType()) { 2728 if (!SrcType->isIntegralType(Self.Context) && SrcType->isArithmeticType()) { 2729 Self.Diag(SrcExpr.get()->getExprLoc(), 2730 diag::err_cast_pointer_from_non_pointer_int) 2731 << SrcType << SrcExpr.get()->getSourceRange(); 2732 SrcExpr = ExprError(); 2733 return; 2734 } 2735 checkIntToPointerCast(/* CStyle */ true, OpRange.getBegin(), SrcExpr.get(), 2736 DestType, Self); 2737 } else if (!SrcType->isArithmeticType()) { 2738 if (!DestType->isIntegralType(Self.Context) && 2739 DestType->isArithmeticType()) { 2740 Self.Diag(SrcExpr.get()->getBeginLoc(), 2741 diag::err_cast_pointer_to_non_pointer_int) 2742 << DestType << SrcExpr.get()->getSourceRange(); 2743 SrcExpr = ExprError(); 2744 return; 2745 } 2746 } 2747 2748 if (Self.getLangOpts().OpenCL && 2749 !Self.getOpenCLOptions().isEnabled("cl_khr_fp16")) { 2750 if (DestType->isHalfType()) { 2751 Self.Diag(SrcExpr.get()->getBeginLoc(), diag::err_opencl_cast_to_half) 2752 << DestType << SrcExpr.get()->getSourceRange(); 2753 SrcExpr = ExprError(); 2754 return; 2755 } 2756 } 2757 2758 // ARC imposes extra restrictions on casts. 2759 if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()) { 2760 checkObjCConversion(Sema::CCK_CStyleCast); 2761 if (SrcExpr.isInvalid()) 2762 return; 2763 2764 const PointerType *CastPtr = DestType->getAs<PointerType>(); 2765 if (Self.getLangOpts().ObjCAutoRefCount && CastPtr) { 2766 if (const PointerType *ExprPtr = SrcType->getAs<PointerType>()) { 2767 Qualifiers CastQuals = CastPtr->getPointeeType().getQualifiers(); 2768 Qualifiers ExprQuals = ExprPtr->getPointeeType().getQualifiers(); 2769 if (CastPtr->getPointeeType()->isObjCLifetimeType() && 2770 ExprPtr->getPointeeType()->isObjCLifetimeType() && 2771 !CastQuals.compatiblyIncludesObjCLifetime(ExprQuals)) { 2772 Self.Diag(SrcExpr.get()->getBeginLoc(), 2773 diag::err_typecheck_incompatible_ownership) 2774 << SrcType << DestType << Sema::AA_Casting 2775 << SrcExpr.get()->getSourceRange(); 2776 return; 2777 } 2778 } 2779 } 2780 else if (!Self.CheckObjCARCUnavailableWeakConversion(DestType, SrcType)) { 2781 Self.Diag(SrcExpr.get()->getBeginLoc(), 2782 diag::err_arc_convesion_of_weak_unavailable) 2783 << 1 << SrcType << DestType << SrcExpr.get()->getSourceRange(); 2784 SrcExpr = ExprError(); 2785 return; 2786 } 2787 } 2788 2789 DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType); 2790 DiagnoseCallingConvCast(Self, SrcExpr, DestType, OpRange); 2791 DiagnoseBadFunctionCast(Self, SrcExpr, DestType); 2792 Kind = Self.PrepareScalarCast(SrcExpr, DestType); 2793 if (SrcExpr.isInvalid()) 2794 return; 2795 2796 if (Kind == CK_BitCast) 2797 checkCastAlign(); 2798} 2799 2800void CastOperation::CheckBuiltinBitCast() { 2801 QualType SrcType = SrcExpr.get()->getType(); 2802 if (SrcExpr.get()->isRValue()) 2803 SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcType, SrcExpr.get(), 2804 /*IsLValueReference=*/false); 2805 2806 CharUnits DestSize = Self.Context.getTypeSizeInChars(DestType); 2807 CharUnits SourceSize = Self.Context.getTypeSizeInChars(SrcType); 2808 if (DestSize != SourceSize) { 2809 Self.Diag(OpRange.getBegin(), diag::err_bit_cast_type_size_mismatch) 2810 << (int)SourceSize.getQuantity() << (int)DestSize.getQuantity(); 2811 SrcExpr = ExprError(); 2812 return; 2813 } 2814 2815 if (!DestType.isTriviallyCopyableType(Self.Context)) { 2816 Self.Diag(OpRange.getBegin(), diag::err_bit_cast_non_trivially_copyable) 2817 << 1; 2818 SrcExpr = ExprError(); 2819 return; 2820 } 2821 2822 if (!SrcType.isTriviallyCopyableType(Self.Context)) { 2823 Self.Diag(OpRange.getBegin(), diag::err_bit_cast_non_trivially_copyable) 2824 << 0; 2825 SrcExpr = ExprError(); 2826 return; 2827 } 2828 2829 if (Self.Context.hasSameUnqualifiedType(DestType, SrcType)) { 2830 Kind = CK_NoOp; 2831 return; 2832 } 2833 2834 Kind = CK_LValueToRValueBitCast; 2835} 2836 2837/// DiagnoseCastQual - Warn whenever casts discards a qualifiers, be it either 2838/// const, volatile or both. 2839static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr, 2840 QualType DestType) { 2841 if (SrcExpr.isInvalid()) 2842 return; 2843 2844 QualType SrcType = SrcExpr.get()->getType(); 2845 if (!((SrcType->isAnyPointerType() && DestType->isAnyPointerType()) || 2846 DestType->isLValueReferenceType())) 2847 return; 2848 2849 QualType TheOffendingSrcType, TheOffendingDestType; 2850 Qualifiers CastAwayQualifiers; 2851 if (CastsAwayConstness(Self, SrcType, DestType, true, false, 2852 &TheOffendingSrcType, &TheOffendingDestType, 2853 &CastAwayQualifiers) != 2854 CastAwayConstnessKind::CACK_Similar) 2855 return; 2856 2857 // FIXME: 'restrict' is not properly handled here. 2858 int qualifiers = -1; 2859 if (CastAwayQualifiers.hasConst() && CastAwayQualifiers.hasVolatile()) { 2860 qualifiers = 0; 2861 } else if (CastAwayQualifiers.hasConst()) { 2862 qualifiers = 1; 2863 } else if (CastAwayQualifiers.hasVolatile()) { 2864 qualifiers = 2; 2865 } 2866 // This is a variant of int **x; const int **y = (const int **)x; 2867 if (qualifiers == -1) 2868 Self.Diag(SrcExpr.get()->getBeginLoc(), diag::warn_cast_qual2) 2869 << SrcType << DestType; 2870 else 2871 Self.Diag(SrcExpr.get()->getBeginLoc(), diag::warn_cast_qual) 2872 << TheOffendingSrcType << TheOffendingDestType << qualifiers; 2873} 2874 2875ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc, 2876 TypeSourceInfo *CastTypeInfo, 2877 SourceLocation RPLoc, 2878 Expr *CastExpr) { 2879 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr); 2880 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2881 Op.OpRange = SourceRange(LPLoc, CastExpr->getEndLoc()); 2882 2883 if (getLangOpts().CPlusPlus) { 2884 Op.CheckCXXCStyleCast(/*FunctionalCast=*/ false, 2885 isa<InitListExpr>(CastExpr)); 2886 } else { 2887 Op.CheckCStyleCast(); 2888 } 2889 2890 if (Op.SrcExpr.isInvalid()) 2891 return ExprError(); 2892 2893 // -Wcast-qual 2894 DiagnoseCastQual(Op.Self, Op.SrcExpr, Op.DestType); 2895 2896 return Op.complete(CStyleCastExpr::Create(Context, Op.ResultType, 2897 Op.ValueKind, Op.Kind, Op.SrcExpr.get(), 2898 &Op.BasePath, CastTypeInfo, LPLoc, RPLoc)); 2899} 2900 2901ExprResult Sema::BuildCXXFunctionalCastExpr(TypeSourceInfo *CastTypeInfo, 2902 QualType Type, 2903 SourceLocation LPLoc, 2904 Expr *CastExpr, 2905 SourceLocation RPLoc) { 2906 assert(LPLoc.isValid() && "List-initialization shouldn't get here."); 2907 CastOperation Op(*this, Type, CastExpr); 2908 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2909 Op.OpRange = SourceRange(Op.DestRange.getBegin(), CastExpr->getEndLoc()); 2910 2911 Op.CheckCXXCStyleCast(/*FunctionalCast=*/true, /*ListInit=*/false); 2912 if (Op.SrcExpr.isInvalid()) 2913 return ExprError(); 2914 2915 auto *SubExpr = Op.SrcExpr.get(); 2916 if (auto *BindExpr = dyn_cast<CXXBindTemporaryExpr>(SubExpr)) 2917 SubExpr = BindExpr->getSubExpr(); 2918 if (auto *ConstructExpr = dyn_cast<CXXConstructExpr>(SubExpr)) 2919 ConstructExpr->setParenOrBraceRange(SourceRange(LPLoc, RPLoc)); 2920 2921 return Op.complete(CXXFunctionalCastExpr::Create(Context, Op.ResultType, 2922 Op.ValueKind, CastTypeInfo, Op.Kind, 2923 Op.SrcExpr.get(), &Op.BasePath, LPLoc, RPLoc)); 2924} 2925