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