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/Sema/Initialization.h" 19 #include "clang/AST/ExprCXX.h" 20 #include "clang/AST/ExprObjC.h" 21 #include "clang/AST/ASTContext.h" 22 #include "clang/AST/CXXInheritance.h" 23 #include "clang/Basic/PartialDiagnostic.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, move(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())); 262 263 case tok::kw_dynamic_cast: { 264 if (!TypeDependent) { 265 Op.CheckDynamicCast(); 266 if (Op.SrcExpr.isInvalid()) 267 return ExprError(); 268 } 269 return Op.complete(CXXDynamicCastExpr::Create(Context, Op.ResultType, 270 Op.ValueKind, Op.Kind, Op.SrcExpr.take(), 271 &Op.BasePath, DestTInfo, 272 OpLoc, Parens.getEnd())); 273 } 274 case tok::kw_reinterpret_cast: { 275 if (!TypeDependent) { 276 Op.CheckReinterpretCast(); 277 if (Op.SrcExpr.isInvalid()) 278 return ExprError(); 279 } 280 return Op.complete(CXXReinterpretCastExpr::Create(Context, Op.ResultType, 281 Op.ValueKind, Op.Kind, Op.SrcExpr.take(), 282 0, DestTInfo, OpLoc, 283 Parens.getEnd())); 284 } 285 case tok::kw_static_cast: { 286 if (!TypeDependent) { 287 Op.CheckStaticCast(); 288 if (Op.SrcExpr.isInvalid()) 289 return ExprError(); 290 } 291 292 return Op.complete(CXXStaticCastExpr::Create(Context, Op.ResultType, 293 Op.ValueKind, Op.Kind, Op.SrcExpr.take(), 294 &Op.BasePath, DestTInfo, 295 OpLoc, Parens.getEnd())); 296 } 297 } 298 } 299 300 /// Try to diagnose a failed overloaded cast. Returns true if 301 /// diagnostics were emitted. 302 static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT, 303 SourceRange range, Expr *src, 304 QualType destType, 305 bool listInitialization) { 306 switch (CT) { 307 // These cast kinds don't consider user-defined conversions. 308 case CT_Const: 309 case CT_Reinterpret: 310 case CT_Dynamic: 311 return false; 312 313 // These do. 314 case CT_Static: 315 case CT_CStyle: 316 case CT_Functional: 317 break; 318 } 319 320 QualType srcType = src->getType(); 321 if (!destType->isRecordType() && !srcType->isRecordType()) 322 return false; 323 324 InitializedEntity entity = InitializedEntity::InitializeTemporary(destType); 325 InitializationKind initKind 326 = (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(), 327 range, listInitialization) 328 : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range, 329 listInitialization) 330 : InitializationKind::CreateCast(/*type range?*/ range); 331 InitializationSequence sequence(S, entity, initKind, &src, 1); 332 333 assert(sequence.Failed() && "initialization succeeded on second try?"); 334 switch (sequence.getFailureKind()) { 335 default: return false; 336 337 case InitializationSequence::FK_ConstructorOverloadFailed: 338 case InitializationSequence::FK_UserConversionOverloadFailed: 339 break; 340 } 341 342 OverloadCandidateSet &candidates = sequence.getFailedCandidateSet(); 343 344 unsigned msg = 0; 345 OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates; 346 347 switch (sequence.getFailedOverloadResult()) { 348 case OR_Success: llvm_unreachable("successful failed overload"); 349 case OR_No_Viable_Function: 350 if (candidates.empty()) 351 msg = diag::err_ovl_no_conversion_in_cast; 352 else 353 msg = diag::err_ovl_no_viable_conversion_in_cast; 354 howManyCandidates = OCD_AllCandidates; 355 break; 356 357 case OR_Ambiguous: 358 msg = diag::err_ovl_ambiguous_conversion_in_cast; 359 howManyCandidates = OCD_ViableCandidates; 360 break; 361 362 case OR_Deleted: 363 msg = diag::err_ovl_deleted_conversion_in_cast; 364 howManyCandidates = OCD_ViableCandidates; 365 break; 366 } 367 368 S.Diag(range.getBegin(), msg) 369 << CT << srcType << destType 370 << range << src->getSourceRange(); 371 372 candidates.NoteCandidates(S, howManyCandidates, src); 373 374 return true; 375 } 376 377 /// Diagnose a failed cast. 378 static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType, 379 SourceRange opRange, Expr *src, QualType destType, 380 bool listInitialization) { 381 if (src->getType() == S.Context.BoundMemberTy) { 382 (void) S.CheckPlaceholderExpr(src); // will always fail 383 return; 384 } 385 386 if (msg == diag::err_bad_cxx_cast_generic && 387 tryDiagnoseOverloadedCast(S, castType, opRange, src, destType, 388 listInitialization)) 389 return; 390 391 S.Diag(opRange.getBegin(), msg) << castType 392 << src->getType() << destType << opRange << src->getSourceRange(); 393 } 394 395 /// UnwrapDissimilarPointerTypes - Like Sema::UnwrapSimilarPointerTypes, 396 /// this removes one level of indirection from both types, provided that they're 397 /// the same kind of pointer (plain or to-member). Unlike the Sema function, 398 /// this one doesn't care if the two pointers-to-member don't point into the 399 /// same class. This is because CastsAwayConstness doesn't care. 400 static bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) { 401 const PointerType *T1PtrType = T1->getAs<PointerType>(), 402 *T2PtrType = T2->getAs<PointerType>(); 403 if (T1PtrType && T2PtrType) { 404 T1 = T1PtrType->getPointeeType(); 405 T2 = T2PtrType->getPointeeType(); 406 return true; 407 } 408 const ObjCObjectPointerType *T1ObjCPtrType = 409 T1->getAs<ObjCObjectPointerType>(), 410 *T2ObjCPtrType = 411 T2->getAs<ObjCObjectPointerType>(); 412 if (T1ObjCPtrType) { 413 if (T2ObjCPtrType) { 414 T1 = T1ObjCPtrType->getPointeeType(); 415 T2 = T2ObjCPtrType->getPointeeType(); 416 return true; 417 } 418 else if (T2PtrType) { 419 T1 = T1ObjCPtrType->getPointeeType(); 420 T2 = T2PtrType->getPointeeType(); 421 return true; 422 } 423 } 424 else if (T2ObjCPtrType) { 425 if (T1PtrType) { 426 T2 = T2ObjCPtrType->getPointeeType(); 427 T1 = T1PtrType->getPointeeType(); 428 return true; 429 } 430 } 431 432 const MemberPointerType *T1MPType = T1->getAs<MemberPointerType>(), 433 *T2MPType = T2->getAs<MemberPointerType>(); 434 if (T1MPType && T2MPType) { 435 T1 = T1MPType->getPointeeType(); 436 T2 = T2MPType->getPointeeType(); 437 return true; 438 } 439 440 const BlockPointerType *T1BPType = T1->getAs<BlockPointerType>(), 441 *T2BPType = T2->getAs<BlockPointerType>(); 442 if (T1BPType && T2BPType) { 443 T1 = T1BPType->getPointeeType(); 444 T2 = T2BPType->getPointeeType(); 445 return true; 446 } 447 448 return false; 449 } 450 451 /// CastsAwayConstness - Check if the pointer conversion from SrcType to 452 /// DestType casts away constness as defined in C++ 5.2.11p8ff. This is used by 453 /// the cast checkers. Both arguments must denote pointer (possibly to member) 454 /// types. 455 /// 456 /// \param CheckCVR Whether to check for const/volatile/restrict qualifiers. 457 /// 458 /// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers. 459 static bool 460 CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, 461 bool CheckCVR, bool CheckObjCLifetime) { 462 // If the only checking we care about is for Objective-C lifetime qualifiers, 463 // and we're not in ARC mode, there's nothing to check. 464 if (!CheckCVR && CheckObjCLifetime && 465 !Self.Context.getLangOpts().ObjCAutoRefCount) 466 return false; 467 468 // Casting away constness is defined in C++ 5.2.11p8 with reference to 469 // C++ 4.4. We piggyback on Sema::IsQualificationConversion for this, since 470 // the rules are non-trivial. So first we construct Tcv *...cv* as described 471 // in C++ 5.2.11p8. 472 assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() || 473 SrcType->isBlockPointerType()) && 474 "Source type is not pointer or pointer to member."); 475 assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() || 476 DestType->isBlockPointerType()) && 477 "Destination type is not pointer or pointer to member."); 478 479 QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType), 480 UnwrappedDestType = Self.Context.getCanonicalType(DestType); 481 SmallVector<Qualifiers, 8> cv1, cv2; 482 483 // Find the qualifiers. We only care about cvr-qualifiers for the 484 // purpose of this check, because other qualifiers (address spaces, 485 // Objective-C GC, etc.) are part of the type's identity. 486 while (UnwrapDissimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) { 487 // Determine the relevant qualifiers at this level. 488 Qualifiers SrcQuals, DestQuals; 489 Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals); 490 Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals); 491 492 Qualifiers RetainedSrcQuals, RetainedDestQuals; 493 if (CheckCVR) { 494 RetainedSrcQuals.setCVRQualifiers(SrcQuals.getCVRQualifiers()); 495 RetainedDestQuals.setCVRQualifiers(DestQuals.getCVRQualifiers()); 496 } 497 498 if (CheckObjCLifetime && 499 !DestQuals.compatiblyIncludesObjCLifetime(SrcQuals)) 500 return true; 501 502 cv1.push_back(RetainedSrcQuals); 503 cv2.push_back(RetainedDestQuals); 504 } 505 if (cv1.empty()) 506 return false; 507 508 // Construct void pointers with those qualifiers (in reverse order of 509 // unwrapping, of course). 510 QualType SrcConstruct = Self.Context.VoidTy; 511 QualType DestConstruct = Self.Context.VoidTy; 512 ASTContext &Context = Self.Context; 513 for (SmallVector<Qualifiers, 8>::reverse_iterator i1 = cv1.rbegin(), 514 i2 = cv2.rbegin(); 515 i1 != cv1.rend(); ++i1, ++i2) { 516 SrcConstruct 517 = Context.getPointerType(Context.getQualifiedType(SrcConstruct, *i1)); 518 DestConstruct 519 = Context.getPointerType(Context.getQualifiedType(DestConstruct, *i2)); 520 } 521 522 // Test if they're compatible. 523 bool ObjCLifetimeConversion; 524 return SrcConstruct != DestConstruct && 525 !Self.IsQualificationConversion(SrcConstruct, DestConstruct, false, 526 ObjCLifetimeConversion); 527 } 528 529 /// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid. 530 /// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime- 531 /// checked downcasts in class hierarchies. 532 void CastOperation::CheckDynamicCast() { 533 if (ValueKind == VK_RValue) 534 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 535 else if (isPlaceholder()) 536 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.take()); 537 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 538 return; 539 540 QualType OrigSrcType = SrcExpr.get()->getType(); 541 QualType DestType = Self.Context.getCanonicalType(this->DestType); 542 543 // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type, 544 // or "pointer to cv void". 545 546 QualType DestPointee; 547 const PointerType *DestPointer = DestType->getAs<PointerType>(); 548 const ReferenceType *DestReference = 0; 549 if (DestPointer) { 550 DestPointee = DestPointer->getPointeeType(); 551 } else if ((DestReference = DestType->getAs<ReferenceType>())) { 552 DestPointee = DestReference->getPointeeType(); 553 } else { 554 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr) 555 << this->DestType << DestRange; 556 return; 557 } 558 559 const RecordType *DestRecord = DestPointee->getAs<RecordType>(); 560 if (DestPointee->isVoidType()) { 561 assert(DestPointer && "Reference to void is not possible"); 562 } else if (DestRecord) { 563 if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee, 564 Self.PDiag(diag::err_bad_dynamic_cast_incomplete) 565 << DestRange)) 566 return; 567 } else { 568 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 569 << DestPointee.getUnqualifiedType() << DestRange; 570 return; 571 } 572 573 // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to 574 // complete class type, [...]. If T is an lvalue reference type, v shall be 575 // an lvalue of a complete class type, [...]. If T is an rvalue reference 576 // type, v shall be an expression having a complete class type, [...] 577 QualType SrcType = Self.Context.getCanonicalType(OrigSrcType); 578 QualType SrcPointee; 579 if (DestPointer) { 580 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 581 SrcPointee = SrcPointer->getPointeeType(); 582 } else { 583 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr) 584 << OrigSrcType << SrcExpr.get()->getSourceRange(); 585 return; 586 } 587 } else if (DestReference->isLValueReferenceType()) { 588 if (!SrcExpr.get()->isLValue()) { 589 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue) 590 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 591 } 592 SrcPointee = SrcType; 593 } else { 594 SrcPointee = SrcType; 595 } 596 597 const RecordType *SrcRecord = SrcPointee->getAs<RecordType>(); 598 if (SrcRecord) { 599 if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee, 600 Self.PDiag(diag::err_bad_dynamic_cast_incomplete) 601 << SrcExpr.get()->getSourceRange())) 602 return; 603 } else { 604 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 605 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 606 return; 607 } 608 609 assert((DestPointer || DestReference) && 610 "Bad destination non-ptr/ref slipped through."); 611 assert((DestRecord || DestPointee->isVoidType()) && 612 "Bad destination pointee slipped through."); 613 assert(SrcRecord && "Bad source pointee slipped through."); 614 615 // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness. 616 if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) { 617 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away) 618 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 619 return; 620 } 621 622 // C++ 5.2.7p3: If the type of v is the same as the required result type, 623 // [except for cv]. 624 if (DestRecord == SrcRecord) { 625 Kind = CK_NoOp; 626 return; 627 } 628 629 // C++ 5.2.7p5 630 // Upcasts are resolved statically. 631 if (DestRecord && Self.IsDerivedFrom(SrcPointee, DestPointee)) { 632 if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee, 633 OpRange.getBegin(), OpRange, 634 &BasePath)) 635 return; 636 637 Kind = CK_DerivedToBase; 638 639 // If we are casting to or through a virtual base class, we need a 640 // vtable. 641 if (Self.BasePathInvolvesVirtualBase(BasePath)) 642 Self.MarkVTableUsed(OpRange.getBegin(), 643 cast<CXXRecordDecl>(SrcRecord->getDecl())); 644 return; 645 } 646 647 // C++ 5.2.7p6: Otherwise, v shall be [polymorphic]. 648 const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition(); 649 assert(SrcDecl && "Definition missing"); 650 if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) { 651 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic) 652 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 653 } 654 Self.MarkVTableUsed(OpRange.getBegin(), 655 cast<CXXRecordDecl>(SrcRecord->getDecl())); 656 657 // Done. Everything else is run-time checks. 658 Kind = CK_Dynamic; 659 } 660 661 /// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid. 662 /// Refer to C++ 5.2.11 for details. const_cast is typically used in code 663 /// like this: 664 /// const char *str = "literal"; 665 /// legacy_function(const_cast\<char*\>(str)); 666 void CastOperation::CheckConstCast() { 667 if (ValueKind == VK_RValue) 668 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 669 else if (isPlaceholder()) 670 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.take()); 671 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 672 return; 673 674 unsigned msg = diag::err_bad_cxx_cast_generic; 675 if (TryConstCast(Self, SrcExpr.get(), DestType, /*CStyle*/false, msg) != TC_Success 676 && msg != 0) 677 Self.Diag(OpRange.getBegin(), msg) << CT_Const 678 << SrcExpr.get()->getType() << DestType << OpRange; 679 } 680 681 /// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is 682 /// valid. 683 /// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code 684 /// like this: 685 /// char *bytes = reinterpret_cast\<char*\>(int_ptr); 686 void CastOperation::CheckReinterpretCast() { 687 if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload)) 688 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 689 else 690 checkNonOverloadPlaceholders(); 691 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 692 return; 693 694 unsigned msg = diag::err_bad_cxx_cast_generic; 695 TryCastResult tcr = 696 TryReinterpretCast(Self, SrcExpr, DestType, 697 /*CStyle*/false, OpRange, msg, Kind); 698 if (tcr != TC_Success && msg != 0) 699 { 700 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 701 return; 702 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 703 //FIXME: &f<int>; is overloaded and resolvable 704 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload) 705 << OverloadExpr::find(SrcExpr.get()).Expression->getName() 706 << DestType << OpRange; 707 Self.NoteAllOverloadCandidates(SrcExpr.get()); 708 709 } else { 710 diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(), 711 DestType, /*listInitialization=*/false); 712 } 713 } else if (tcr == TC_Success && Self.getLangOpts().ObjCAutoRefCount) { 714 checkObjCARCConversion(Sema::CCK_OtherCast); 715 } 716 } 717 718 719 /// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid. 720 /// Refer to C++ 5.2.9 for details. Static casts are mostly used for making 721 /// implicit conversions explicit and getting rid of data loss warnings. 722 void CastOperation::CheckStaticCast() { 723 if (isPlaceholder()) { 724 checkNonOverloadPlaceholders(); 725 if (SrcExpr.isInvalid()) 726 return; 727 } 728 729 // This test is outside everything else because it's the only case where 730 // a non-lvalue-reference target type does not lead to decay. 731 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 732 if (DestType->isVoidType()) { 733 Kind = CK_ToVoid; 734 735 if (claimPlaceholder(BuiltinType::Overload)) { 736 Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr, 737 false, // Decay Function to ptr 738 true, // Complain 739 OpRange, DestType, diag::err_bad_static_cast_overload); 740 if (SrcExpr.isInvalid()) 741 return; 742 } 743 744 SrcExpr = Self.IgnoredValueConversions(SrcExpr.take()); 745 return; 746 } 747 748 if (ValueKind == VK_RValue && !DestType->isRecordType() && 749 !isPlaceholder(BuiltinType::Overload)) { 750 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 751 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 752 return; 753 } 754 755 unsigned msg = diag::err_bad_cxx_cast_generic; 756 TryCastResult tcr 757 = TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_OtherCast, OpRange, msg, 758 Kind, BasePath, /*ListInitialization=*/false); 759 if (tcr != TC_Success && msg != 0) { 760 if (SrcExpr.isInvalid()) 761 return; 762 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 763 OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression; 764 Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload) 765 << oe->getName() << DestType << OpRange 766 << oe->getQualifierLoc().getSourceRange(); 767 Self.NoteAllOverloadCandidates(SrcExpr.get()); 768 } else { 769 diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType, 770 /*listInitialization=*/false); 771 } 772 } else if (tcr == TC_Success) { 773 if (Kind == CK_BitCast) 774 checkCastAlign(); 775 if (Self.getLangOpts().ObjCAutoRefCount) 776 checkObjCARCConversion(Sema::CCK_OtherCast); 777 } else if (Kind == CK_BitCast) { 778 checkCastAlign(); 779 } 780 } 781 782 /// TryStaticCast - Check if a static cast can be performed, and do so if 783 /// possible. If @p CStyle, ignore access restrictions on hierarchy casting 784 /// and casting away constness. 785 static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, 786 QualType DestType, 787 Sema::CheckedConversionKind CCK, 788 const SourceRange &OpRange, unsigned &msg, 789 CastKind &Kind, CXXCastPath &BasePath, 790 bool ListInitialization) { 791 // Determine whether we have the semantics of a C-style cast. 792 bool CStyle 793 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 794 795 // The order the tests is not entirely arbitrary. There is one conversion 796 // that can be handled in two different ways. Given: 797 // struct A {}; 798 // struct B : public A { 799 // B(); B(const A&); 800 // }; 801 // const A &a = B(); 802 // the cast static_cast<const B&>(a) could be seen as either a static 803 // reference downcast, or an explicit invocation of the user-defined 804 // conversion using B's conversion constructor. 805 // DR 427 specifies that the downcast is to be applied here. 806 807 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 808 // Done outside this function. 809 810 TryCastResult tcr; 811 812 // C++ 5.2.9p5, reference downcast. 813 // See the function for details. 814 // DR 427 specifies that this is to be applied before paragraph 2. 815 tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle, 816 OpRange, msg, Kind, BasePath); 817 if (tcr != TC_NotApplicable) 818 return tcr; 819 820 // C++0x [expr.static.cast]p3: 821 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2 822 // T2" if "cv2 T2" is reference-compatible with "cv1 T1". 823 tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind, 824 BasePath, msg); 825 if (tcr != TC_NotApplicable) 826 return tcr; 827 828 // C++ 5.2.9p2: An expression e can be explicitly converted to a type T 829 // [...] if the declaration "T t(e);" is well-formed, [...]. 830 tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg, 831 Kind, ListInitialization); 832 if (SrcExpr.isInvalid()) 833 return TC_Failed; 834 if (tcr != TC_NotApplicable) 835 return tcr; 836 837 // C++ 5.2.9p6: May apply the reverse of any standard conversion, except 838 // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean 839 // conversions, subject to further restrictions. 840 // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal 841 // of qualification conversions impossible. 842 // In the CStyle case, the earlier attempt to const_cast should have taken 843 // care of reverse qualification conversions. 844 845 QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType()); 846 847 // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly 848 // converted to an integral type. [...] A value of a scoped enumeration type 849 // can also be explicitly converted to a floating-point type [...]. 850 if (const EnumType *Enum = SrcType->getAs<EnumType>()) { 851 if (Enum->getDecl()->isScoped()) { 852 if (DestType->isBooleanType()) { 853 Kind = CK_IntegralToBoolean; 854 return TC_Success; 855 } else if (DestType->isIntegralType(Self.Context)) { 856 Kind = CK_IntegralCast; 857 return TC_Success; 858 } else if (DestType->isRealFloatingType()) { 859 Kind = CK_IntegralToFloating; 860 return TC_Success; 861 } 862 } 863 } 864 865 // Reverse integral promotion/conversion. All such conversions are themselves 866 // again integral promotions or conversions and are thus already handled by 867 // p2 (TryDirectInitialization above). 868 // (Note: any data loss warnings should be suppressed.) 869 // The exception is the reverse of enum->integer, i.e. integer->enum (and 870 // enum->enum). See also C++ 5.2.9p7. 871 // The same goes for reverse floating point promotion/conversion and 872 // floating-integral conversions. Again, only floating->enum is relevant. 873 if (DestType->isEnumeralType()) { 874 if (SrcType->isIntegralOrEnumerationType()) { 875 Kind = CK_IntegralCast; 876 return TC_Success; 877 } else if (SrcType->isRealFloatingType()) { 878 Kind = CK_FloatingToIntegral; 879 return TC_Success; 880 } 881 } 882 883 // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast. 884 // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance. 885 tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg, 886 Kind, BasePath); 887 if (tcr != TC_NotApplicable) 888 return tcr; 889 890 // Reverse member pointer conversion. C++ 4.11 specifies member pointer 891 // conversion. C++ 5.2.9p9 has additional information. 892 // DR54's access restrictions apply here also. 893 tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle, 894 OpRange, msg, Kind, BasePath); 895 if (tcr != TC_NotApplicable) 896 return tcr; 897 898 // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to 899 // void*. C++ 5.2.9p10 specifies additional restrictions, which really is 900 // just the usual constness stuff. 901 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 902 QualType SrcPointee = SrcPointer->getPointeeType(); 903 if (SrcPointee->isVoidType()) { 904 if (const PointerType *DestPointer = DestType->getAs<PointerType>()) { 905 QualType DestPointee = DestPointer->getPointeeType(); 906 if (DestPointee->isIncompleteOrObjectType()) { 907 // This is definitely the intended conversion, but it might fail due 908 // to a qualifier violation. Note that we permit Objective-C lifetime 909 // and GC qualifier mismatches here. 910 if (!CStyle) { 911 Qualifiers DestPointeeQuals = DestPointee.getQualifiers(); 912 Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers(); 913 DestPointeeQuals.removeObjCGCAttr(); 914 DestPointeeQuals.removeObjCLifetime(); 915 SrcPointeeQuals.removeObjCGCAttr(); 916 SrcPointeeQuals.removeObjCLifetime(); 917 if (DestPointeeQuals != SrcPointeeQuals && 918 !DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) { 919 msg = diag::err_bad_cxx_cast_qualifiers_away; 920 return TC_Failed; 921 } 922 } 923 Kind = CK_BitCast; 924 return TC_Success; 925 } 926 } 927 else if (DestType->isObjCObjectPointerType()) { 928 // allow both c-style cast and static_cast of objective-c pointers as 929 // they are pervasive. 930 Kind = CK_CPointerToObjCPointerCast; 931 return TC_Success; 932 } 933 else if (CStyle && DestType->isBlockPointerType()) { 934 // allow c-style cast of void * to block pointers. 935 Kind = CK_AnyPointerToBlockPointerCast; 936 return TC_Success; 937 } 938 } 939 } 940 // Allow arbitray objective-c pointer conversion with static casts. 941 if (SrcType->isObjCObjectPointerType() && 942 DestType->isObjCObjectPointerType()) { 943 Kind = CK_BitCast; 944 return TC_Success; 945 } 946 947 // We tried everything. Everything! Nothing works! :-( 948 return TC_NotApplicable; 949 } 950 951 /// Tests whether a conversion according to N2844 is valid. 952 TryCastResult 953 TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType, 954 bool CStyle, CastKind &Kind, CXXCastPath &BasePath, 955 unsigned &msg) { 956 // C++0x [expr.static.cast]p3: 957 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to 958 // cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1". 959 const RValueReferenceType *R = DestType->getAs<RValueReferenceType>(); 960 if (!R) 961 return TC_NotApplicable; 962 963 if (!SrcExpr->isGLValue()) 964 return TC_NotApplicable; 965 966 // Because we try the reference downcast before this function, from now on 967 // this is the only cast possibility, so we issue an error if we fail now. 968 // FIXME: Should allow casting away constness if CStyle. 969 bool DerivedToBase; 970 bool ObjCConversion; 971 bool ObjCLifetimeConversion; 972 QualType FromType = SrcExpr->getType(); 973 QualType ToType = R->getPointeeType(); 974 if (CStyle) { 975 FromType = FromType.getUnqualifiedType(); 976 ToType = ToType.getUnqualifiedType(); 977 } 978 979 if (Self.CompareReferenceRelationship(SrcExpr->getLocStart(), 980 ToType, FromType, 981 DerivedToBase, ObjCConversion, 982 ObjCLifetimeConversion) 983 < Sema::Ref_Compatible_With_Added_Qualification) { 984 msg = diag::err_bad_lvalue_to_rvalue_cast; 985 return TC_Failed; 986 } 987 988 if (DerivedToBase) { 989 Kind = CK_DerivedToBase; 990 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 991 /*DetectVirtual=*/true); 992 if (!Self.IsDerivedFrom(SrcExpr->getType(), R->getPointeeType(), Paths)) 993 return TC_NotApplicable; 994 995 Self.BuildBasePathArray(Paths, BasePath); 996 } else 997 Kind = CK_NoOp; 998 999 return TC_Success; 1000 } 1001 1002 /// Tests whether a conversion according to C++ 5.2.9p5 is valid. 1003 TryCastResult 1004 TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType, 1005 bool CStyle, const SourceRange &OpRange, 1006 unsigned &msg, CastKind &Kind, 1007 CXXCastPath &BasePath) { 1008 // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be 1009 // cast to type "reference to cv2 D", where D is a class derived from B, 1010 // if a valid standard conversion from "pointer to D" to "pointer to B" 1011 // exists, cv2 >= cv1, and B is not a virtual base class of D. 1012 // In addition, DR54 clarifies that the base must be accessible in the 1013 // current context. Although the wording of DR54 only applies to the pointer 1014 // variant of this rule, the intent is clearly for it to apply to the this 1015 // conversion as well. 1016 1017 const ReferenceType *DestReference = DestType->getAs<ReferenceType>(); 1018 if (!DestReference) { 1019 return TC_NotApplicable; 1020 } 1021 bool RValueRef = DestReference->isRValueReferenceType(); 1022 if (!RValueRef && !SrcExpr->isLValue()) { 1023 // We know the left side is an lvalue reference, so we can suggest a reason. 1024 msg = diag::err_bad_cxx_cast_rvalue; 1025 return TC_NotApplicable; 1026 } 1027 1028 QualType DestPointee = DestReference->getPointeeType(); 1029 1030 return TryStaticDowncast(Self, 1031 Self.Context.getCanonicalType(SrcExpr->getType()), 1032 Self.Context.getCanonicalType(DestPointee), CStyle, 1033 OpRange, SrcExpr->getType(), DestType, msg, Kind, 1034 BasePath); 1035 } 1036 1037 /// Tests whether a conversion according to C++ 5.2.9p8 is valid. 1038 TryCastResult 1039 TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType, 1040 bool CStyle, const SourceRange &OpRange, 1041 unsigned &msg, CastKind &Kind, 1042 CXXCastPath &BasePath) { 1043 // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class 1044 // type, can be converted to an rvalue of type "pointer to cv2 D", where D 1045 // is a class derived from B, if a valid standard conversion from "pointer 1046 // to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base 1047 // class of D. 1048 // In addition, DR54 clarifies that the base must be accessible in the 1049 // current context. 1050 1051 const PointerType *DestPointer = DestType->getAs<PointerType>(); 1052 if (!DestPointer) { 1053 return TC_NotApplicable; 1054 } 1055 1056 const PointerType *SrcPointer = SrcType->getAs<PointerType>(); 1057 if (!SrcPointer) { 1058 msg = diag::err_bad_static_cast_pointer_nonpointer; 1059 return TC_NotApplicable; 1060 } 1061 1062 return TryStaticDowncast(Self, 1063 Self.Context.getCanonicalType(SrcPointer->getPointeeType()), 1064 Self.Context.getCanonicalType(DestPointer->getPointeeType()), 1065 CStyle, OpRange, SrcType, DestType, msg, Kind, 1066 BasePath); 1067 } 1068 1069 /// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and 1070 /// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to 1071 /// DestType is possible and allowed. 1072 TryCastResult 1073 TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType, 1074 bool CStyle, const SourceRange &OpRange, QualType OrigSrcType, 1075 QualType OrigDestType, unsigned &msg, 1076 CastKind &Kind, CXXCastPath &BasePath) { 1077 // We can only work with complete types. But don't complain if it doesn't work 1078 if (Self.RequireCompleteType(OpRange.getBegin(), SrcType, Self.PDiag(0)) || 1079 Self.RequireCompleteType(OpRange.getBegin(), DestType, Self.PDiag(0))) 1080 return TC_NotApplicable; 1081 1082 // Downcast can only happen in class hierarchies, so we need classes. 1083 if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) { 1084 return TC_NotApplicable; 1085 } 1086 1087 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1088 /*DetectVirtual=*/true); 1089 if (!Self.IsDerivedFrom(DestType, SrcType, Paths)) { 1090 return TC_NotApplicable; 1091 } 1092 1093 // Target type does derive from source type. Now we're serious. If an error 1094 // appears now, it's not ignored. 1095 // This may not be entirely in line with the standard. Take for example: 1096 // struct A {}; 1097 // struct B : virtual A { 1098 // B(A&); 1099 // }; 1100 // 1101 // void f() 1102 // { 1103 // (void)static_cast<const B&>(*((A*)0)); 1104 // } 1105 // As far as the standard is concerned, p5 does not apply (A is virtual), so 1106 // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid. 1107 // However, both GCC and Comeau reject this example, and accepting it would 1108 // mean more complex code if we're to preserve the nice error message. 1109 // FIXME: Being 100% compliant here would be nice to have. 1110 1111 // Must preserve cv, as always, unless we're in C-style mode. 1112 if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) { 1113 msg = diag::err_bad_cxx_cast_qualifiers_away; 1114 return TC_Failed; 1115 } 1116 1117 if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) { 1118 // This code is analoguous to that in CheckDerivedToBaseConversion, except 1119 // that it builds the paths in reverse order. 1120 // To sum up: record all paths to the base and build a nice string from 1121 // them. Use it to spice up the error message. 1122 if (!Paths.isRecordingPaths()) { 1123 Paths.clear(); 1124 Paths.setRecordingPaths(true); 1125 Self.IsDerivedFrom(DestType, SrcType, Paths); 1126 } 1127 std::string PathDisplayStr; 1128 std::set<unsigned> DisplayedPaths; 1129 for (CXXBasePaths::paths_iterator PI = Paths.begin(), PE = Paths.end(); 1130 PI != PE; ++PI) { 1131 if (DisplayedPaths.insert(PI->back().SubobjectNumber).second) { 1132 // We haven't displayed a path to this particular base 1133 // class subobject yet. 1134 PathDisplayStr += "\n "; 1135 for (CXXBasePath::const_reverse_iterator EI = PI->rbegin(), 1136 EE = PI->rend(); 1137 EI != EE; ++EI) 1138 PathDisplayStr += EI->Base->getType().getAsString() + " -> "; 1139 PathDisplayStr += QualType(DestType).getAsString(); 1140 } 1141 } 1142 1143 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast) 1144 << QualType(SrcType).getUnqualifiedType() 1145 << QualType(DestType).getUnqualifiedType() 1146 << PathDisplayStr << OpRange; 1147 msg = 0; 1148 return TC_Failed; 1149 } 1150 1151 if (Paths.getDetectedVirtual() != 0) { 1152 QualType VirtualBase(Paths.getDetectedVirtual(), 0); 1153 Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual) 1154 << OrigSrcType << OrigDestType << VirtualBase << OpRange; 1155 msg = 0; 1156 return TC_Failed; 1157 } 1158 1159 if (!CStyle) { 1160 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1161 SrcType, DestType, 1162 Paths.front(), 1163 diag::err_downcast_from_inaccessible_base)) { 1164 case Sema::AR_accessible: 1165 case Sema::AR_delayed: // be optimistic 1166 case Sema::AR_dependent: // be optimistic 1167 break; 1168 1169 case Sema::AR_inaccessible: 1170 msg = 0; 1171 return TC_Failed; 1172 } 1173 } 1174 1175 Self.BuildBasePathArray(Paths, BasePath); 1176 Kind = CK_BaseToDerived; 1177 return TC_Success; 1178 } 1179 1180 /// TryStaticMemberPointerUpcast - Tests whether a conversion according to 1181 /// C++ 5.2.9p9 is valid: 1182 /// 1183 /// An rvalue of type "pointer to member of D of type cv1 T" can be 1184 /// converted to an rvalue of type "pointer to member of B of type cv2 T", 1185 /// where B is a base class of D [...]. 1186 /// 1187 TryCastResult 1188 TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType, 1189 QualType DestType, bool CStyle, 1190 const SourceRange &OpRange, 1191 unsigned &msg, CastKind &Kind, 1192 CXXCastPath &BasePath) { 1193 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(); 1194 if (!DestMemPtr) 1195 return TC_NotApplicable; 1196 1197 bool WasOverloadedFunction = false; 1198 DeclAccessPair FoundOverload; 1199 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 1200 if (FunctionDecl *Fn 1201 = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false, 1202 FoundOverload)) { 1203 CXXMethodDecl *M = cast<CXXMethodDecl>(Fn); 1204 SrcType = Self.Context.getMemberPointerType(Fn->getType(), 1205 Self.Context.getTypeDeclType(M->getParent()).getTypePtr()); 1206 WasOverloadedFunction = true; 1207 } 1208 } 1209 1210 const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 1211 if (!SrcMemPtr) { 1212 msg = diag::err_bad_static_cast_member_pointer_nonmp; 1213 return TC_NotApplicable; 1214 } 1215 1216 // T == T, modulo cv 1217 if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(), 1218 DestMemPtr->getPointeeType())) 1219 return TC_NotApplicable; 1220 1221 // B base of D 1222 QualType SrcClass(SrcMemPtr->getClass(), 0); 1223 QualType DestClass(DestMemPtr->getClass(), 0); 1224 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1225 /*DetectVirtual=*/true); 1226 if (!Self.IsDerivedFrom(SrcClass, DestClass, Paths)) { 1227 return TC_NotApplicable; 1228 } 1229 1230 // B is a base of D. But is it an allowed base? If not, it's a hard error. 1231 if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) { 1232 Paths.clear(); 1233 Paths.setRecordingPaths(true); 1234 bool StillOkay = Self.IsDerivedFrom(SrcClass, DestClass, Paths); 1235 assert(StillOkay); 1236 (void)StillOkay; 1237 std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths); 1238 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv) 1239 << 1 << SrcClass << DestClass << PathDisplayStr << OpRange; 1240 msg = 0; 1241 return TC_Failed; 1242 } 1243 1244 if (const RecordType *VBase = Paths.getDetectedVirtual()) { 1245 Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual) 1246 << SrcClass << DestClass << QualType(VBase, 0) << OpRange; 1247 msg = 0; 1248 return TC_Failed; 1249 } 1250 1251 if (!CStyle) { 1252 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1253 DestClass, SrcClass, 1254 Paths.front(), 1255 diag::err_upcast_to_inaccessible_base)) { 1256 case Sema::AR_accessible: 1257 case Sema::AR_delayed: 1258 case Sema::AR_dependent: 1259 // Optimistically assume that the delayed and dependent cases 1260 // will work out. 1261 break; 1262 1263 case Sema::AR_inaccessible: 1264 msg = 0; 1265 return TC_Failed; 1266 } 1267 } 1268 1269 if (WasOverloadedFunction) { 1270 // Resolve the address of the overloaded function again, this time 1271 // allowing complaints if something goes wrong. 1272 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 1273 DestType, 1274 true, 1275 FoundOverload); 1276 if (!Fn) { 1277 msg = 0; 1278 return TC_Failed; 1279 } 1280 1281 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn); 1282 if (!SrcExpr.isUsable()) { 1283 msg = 0; 1284 return TC_Failed; 1285 } 1286 } 1287 1288 Self.BuildBasePathArray(Paths, BasePath); 1289 Kind = CK_DerivedToBaseMemberPointer; 1290 return TC_Success; 1291 } 1292 1293 /// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2 1294 /// is valid: 1295 /// 1296 /// An expression e can be explicitly converted to a type T using a 1297 /// @c static_cast if the declaration "T t(e);" is well-formed [...]. 1298 TryCastResult 1299 TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, 1300 Sema::CheckedConversionKind CCK, 1301 const SourceRange &OpRange, unsigned &msg, 1302 CastKind &Kind, bool ListInitialization) { 1303 if (DestType->isRecordType()) { 1304 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 1305 diag::err_bad_dynamic_cast_incomplete)) { 1306 msg = 0; 1307 return TC_Failed; 1308 } 1309 } 1310 1311 InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType); 1312 InitializationKind InitKind 1313 = (CCK == Sema::CCK_CStyleCast) 1314 ? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange, 1315 ListInitialization) 1316 : (CCK == Sema::CCK_FunctionalCast) 1317 ? InitializationKind::CreateFunctionalCast(OpRange, ListInitialization) 1318 : InitializationKind::CreateCast(OpRange); 1319 Expr *SrcExprRaw = SrcExpr.get(); 1320 InitializationSequence InitSeq(Self, Entity, InitKind, &SrcExprRaw, 1); 1321 1322 // At this point of CheckStaticCast, if the destination is a reference, 1323 // or the expression is an overload expression this has to work. 1324 // There is no other way that works. 1325 // On the other hand, if we're checking a C-style cast, we've still got 1326 // the reinterpret_cast way. 1327 bool CStyle 1328 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 1329 if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType())) 1330 return TC_NotApplicable; 1331 1332 ExprResult Result 1333 = InitSeq.Perform(Self, Entity, InitKind, MultiExprArg(Self, &SrcExprRaw, 1)); 1334 if (Result.isInvalid()) { 1335 msg = 0; 1336 return TC_Failed; 1337 } 1338 1339 if (InitSeq.isConstructorInitialization()) 1340 Kind = CK_ConstructorConversion; 1341 else 1342 Kind = CK_NoOp; 1343 1344 SrcExpr = move(Result); 1345 return TC_Success; 1346 } 1347 1348 /// TryConstCast - See if a const_cast from source to destination is allowed, 1349 /// and perform it if it is. 1350 static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType, 1351 bool CStyle, unsigned &msg) { 1352 DestType = Self.Context.getCanonicalType(DestType); 1353 QualType SrcType = SrcExpr->getType(); 1354 if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) { 1355 if (DestTypeTmp->isLValueReferenceType() && !SrcExpr->isLValue()) { 1356 // Cannot const_cast non-lvalue to lvalue reference type. But if this 1357 // is C-style, static_cast might find a way, so we simply suggest a 1358 // message and tell the parent to keep searching. 1359 msg = diag::err_bad_cxx_cast_rvalue; 1360 return TC_NotApplicable; 1361 } 1362 1363 // C++ 5.2.11p4: An lvalue of type T1 can be [cast] to an lvalue of type T2 1364 // [...] if a pointer to T1 can be [cast] to the type pointer to T2. 1365 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 1366 SrcType = Self.Context.getPointerType(SrcType); 1367 } 1368 1369 // C++ 5.2.11p5: For a const_cast involving pointers to data members [...] 1370 // the rules for const_cast are the same as those used for pointers. 1371 1372 if (!DestType->isPointerType() && 1373 !DestType->isMemberPointerType() && 1374 !DestType->isObjCObjectPointerType()) { 1375 // Cannot cast to non-pointer, non-reference type. Note that, if DestType 1376 // was a reference type, we converted it to a pointer above. 1377 // The status of rvalue references isn't entirely clear, but it looks like 1378 // conversion to them is simply invalid. 1379 // C++ 5.2.11p3: For two pointer types [...] 1380 if (!CStyle) 1381 msg = diag::err_bad_const_cast_dest; 1382 return TC_NotApplicable; 1383 } 1384 if (DestType->isFunctionPointerType() || 1385 DestType->isMemberFunctionPointerType()) { 1386 // Cannot cast direct function pointers. 1387 // C++ 5.2.11p2: [...] where T is any object type or the void type [...] 1388 // T is the ultimate pointee of source and target type. 1389 if (!CStyle) 1390 msg = diag::err_bad_const_cast_dest; 1391 return TC_NotApplicable; 1392 } 1393 SrcType = Self.Context.getCanonicalType(SrcType); 1394 1395 // Unwrap the pointers. Ignore qualifiers. Terminate early if the types are 1396 // completely equal. 1397 // C++ 5.2.11p3 describes the core semantics of const_cast. All cv specifiers 1398 // in multi-level pointers may change, but the level count must be the same, 1399 // as must be the final pointee type. 1400 while (SrcType != DestType && 1401 Self.Context.UnwrapSimilarPointerTypes(SrcType, DestType)) { 1402 Qualifiers SrcQuals, DestQuals; 1403 SrcType = Self.Context.getUnqualifiedArrayType(SrcType, SrcQuals); 1404 DestType = Self.Context.getUnqualifiedArrayType(DestType, DestQuals); 1405 1406 // const_cast is permitted to strip cvr-qualifiers, only. Make sure that 1407 // the other qualifiers (e.g., address spaces) are identical. 1408 SrcQuals.removeCVRQualifiers(); 1409 DestQuals.removeCVRQualifiers(); 1410 if (SrcQuals != DestQuals) 1411 return TC_NotApplicable; 1412 } 1413 1414 // Since we're dealing in canonical types, the remainder must be the same. 1415 if (SrcType != DestType) 1416 return TC_NotApplicable; 1417 1418 return TC_Success; 1419 } 1420 1421 // Checks for undefined behavior in reinterpret_cast. 1422 // The cases that is checked for is: 1423 // *reinterpret_cast<T*>(&a) 1424 // reinterpret_cast<T&>(a) 1425 // where accessing 'a' as type 'T' will result in undefined behavior. 1426 void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType, 1427 bool IsDereference, 1428 SourceRange Range) { 1429 unsigned DiagID = IsDereference ? 1430 diag::warn_pointer_indirection_from_incompatible_type : 1431 diag::warn_undefined_reinterpret_cast; 1432 1433 if (Diags.getDiagnosticLevel(DiagID, Range.getBegin()) == 1434 DiagnosticsEngine::Ignored) { 1435 return; 1436 } 1437 1438 QualType SrcTy, DestTy; 1439 if (IsDereference) { 1440 if (!SrcType->getAs<PointerType>() || !DestType->getAs<PointerType>()) { 1441 return; 1442 } 1443 SrcTy = SrcType->getPointeeType(); 1444 DestTy = DestType->getPointeeType(); 1445 } else { 1446 if (!DestType->getAs<ReferenceType>()) { 1447 return; 1448 } 1449 SrcTy = SrcType; 1450 DestTy = DestType->getPointeeType(); 1451 } 1452 1453 // Cast is compatible if the types are the same. 1454 if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) { 1455 return; 1456 } 1457 // or one of the types is a char or void type 1458 if (DestTy->isAnyCharacterType() || DestTy->isVoidType() || 1459 SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) { 1460 return; 1461 } 1462 // or one of the types is a tag type. 1463 if (SrcTy->getAs<TagType>() || DestTy->getAs<TagType>()) { 1464 return; 1465 } 1466 1467 // FIXME: Scoped enums? 1468 if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) || 1469 (SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) { 1470 if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) { 1471 return; 1472 } 1473 } 1474 1475 Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range; 1476 } 1477 1478 static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr, 1479 QualType DestType, bool CStyle, 1480 const SourceRange &OpRange, 1481 unsigned &msg, 1482 CastKind &Kind) { 1483 bool IsLValueCast = false; 1484 1485 DestType = Self.Context.getCanonicalType(DestType); 1486 QualType SrcType = SrcExpr.get()->getType(); 1487 1488 // Is the source an overloaded name? (i.e. &foo) 1489 // If so, reinterpret_cast can not help us here (13.4, p1, bullet 5) ... 1490 if (SrcType == Self.Context.OverloadTy) { 1491 // ... unless foo<int> resolves to an lvalue unambiguously. 1492 // TODO: what if this fails because of DiagnoseUseOfDecl or something 1493 // like it? 1494 ExprResult SingleFunctionExpr = SrcExpr; 1495 if (Self.ResolveAndFixSingleFunctionTemplateSpecialization( 1496 SingleFunctionExpr, 1497 Expr::getValueKindForType(DestType) == VK_RValue // Convert Fun to Ptr 1498 ) && SingleFunctionExpr.isUsable()) { 1499 SrcExpr = move(SingleFunctionExpr); 1500 SrcType = SrcExpr.get()->getType(); 1501 } else { 1502 return TC_NotApplicable; 1503 } 1504 } 1505 1506 if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) { 1507 bool LValue = DestTypeTmp->isLValueReferenceType(); 1508 if (LValue && !SrcExpr.get()->isLValue()) { 1509 // Cannot cast non-lvalue to lvalue reference type. See the similar 1510 // comment in const_cast. 1511 msg = diag::err_bad_cxx_cast_rvalue; 1512 return TC_NotApplicable; 1513 } 1514 1515 if (!CStyle) { 1516 Self.CheckCompatibleReinterpretCast(SrcType, DestType, 1517 /*isDereference=*/false, OpRange); 1518 } 1519 1520 // C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the 1521 // same effect as the conversion *reinterpret_cast<T*>(&x) with the 1522 // built-in & and * operators. 1523 1524 const char *inappropriate = 0; 1525 switch (SrcExpr.get()->getObjectKind()) { 1526 case OK_Ordinary: 1527 break; 1528 case OK_BitField: inappropriate = "bit-field"; break; 1529 case OK_VectorComponent: inappropriate = "vector element"; break; 1530 case OK_ObjCProperty: inappropriate = "property expression"; break; 1531 case OK_ObjCSubscript: inappropriate = "container subscripting expression"; 1532 break; 1533 } 1534 if (inappropriate) { 1535 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference) 1536 << inappropriate << DestType 1537 << OpRange << SrcExpr.get()->getSourceRange(); 1538 msg = 0; SrcExpr = ExprError(); 1539 return TC_NotApplicable; 1540 } 1541 1542 // This code does this transformation for the checked types. 1543 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 1544 SrcType = Self.Context.getPointerType(SrcType); 1545 1546 IsLValueCast = true; 1547 } 1548 1549 // Canonicalize source for comparison. 1550 SrcType = Self.Context.getCanonicalType(SrcType); 1551 1552 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(), 1553 *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 1554 if (DestMemPtr && SrcMemPtr) { 1555 // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1" 1556 // can be explicitly converted to an rvalue of type "pointer to member 1557 // of Y of type T2" if T1 and T2 are both function types or both object 1558 // types. 1559 if (DestMemPtr->getPointeeType()->isFunctionType() != 1560 SrcMemPtr->getPointeeType()->isFunctionType()) 1561 return TC_NotApplicable; 1562 1563 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away 1564 // constness. 1565 // A reinterpret_cast followed by a const_cast can, though, so in C-style, 1566 // we accept it. 1567 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, 1568 /*CheckObjCLifetime=*/CStyle)) { 1569 msg = diag::err_bad_cxx_cast_qualifiers_away; 1570 return TC_Failed; 1571 } 1572 1573 // Don't allow casting between member pointers of different sizes. 1574 if (Self.Context.getTypeSize(DestMemPtr) != 1575 Self.Context.getTypeSize(SrcMemPtr)) { 1576 msg = diag::err_bad_cxx_cast_member_pointer_size; 1577 return TC_Failed; 1578 } 1579 1580 // A valid member pointer cast. 1581 assert(!IsLValueCast); 1582 Kind = CK_ReinterpretMemberPointer; 1583 return TC_Success; 1584 } 1585 1586 // See below for the enumeral issue. 1587 if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) { 1588 // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral 1589 // type large enough to hold it. A value of std::nullptr_t can be 1590 // converted to an integral type; the conversion has the same meaning 1591 // and validity as a conversion of (void*)0 to the integral type. 1592 if (Self.Context.getTypeSize(SrcType) > 1593 Self.Context.getTypeSize(DestType)) { 1594 msg = diag::err_bad_reinterpret_cast_small_int; 1595 return TC_Failed; 1596 } 1597 Kind = CK_PointerToIntegral; 1598 return TC_Success; 1599 } 1600 1601 bool destIsVector = DestType->isVectorType(); 1602 bool srcIsVector = SrcType->isVectorType(); 1603 if (srcIsVector || destIsVector) { 1604 // FIXME: Should this also apply to floating point types? 1605 bool srcIsScalar = SrcType->isIntegralType(Self.Context); 1606 bool destIsScalar = DestType->isIntegralType(Self.Context); 1607 1608 // Check if this is a cast between a vector and something else. 1609 if (!(srcIsScalar && destIsVector) && !(srcIsVector && destIsScalar) && 1610 !(srcIsVector && destIsVector)) 1611 return TC_NotApplicable; 1612 1613 // If both types have the same size, we can successfully cast. 1614 if (Self.Context.getTypeSize(SrcType) 1615 == Self.Context.getTypeSize(DestType)) { 1616 Kind = CK_BitCast; 1617 return TC_Success; 1618 } 1619 1620 if (destIsScalar) 1621 msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size; 1622 else if (srcIsScalar) 1623 msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size; 1624 else 1625 msg = diag::err_bad_cxx_cast_vector_to_vector_different_size; 1626 1627 return TC_Failed; 1628 } 1629 1630 if (SrcType == DestType) { 1631 // C++ 5.2.10p2 has a note that mentions that, subject to all other 1632 // restrictions, a cast to the same type is allowed so long as it does not 1633 // cast away constness. In C++98, the intent was not entirely clear here, 1634 // since all other paragraphs explicitly forbid casts to the same type. 1635 // C++11 clarifies this case with p2. 1636 // 1637 // The only allowed types are: integral, enumeration, pointer, or 1638 // pointer-to-member types. We also won't restrict Obj-C pointers either. 1639 Kind = CK_NoOp; 1640 TryCastResult Result = TC_NotApplicable; 1641 if (SrcType->isIntegralOrEnumerationType() || 1642 SrcType->isAnyPointerType() || 1643 SrcType->isMemberPointerType() || 1644 SrcType->isBlockPointerType()) { 1645 Result = TC_Success; 1646 } 1647 return Result; 1648 } 1649 1650 bool destIsPtr = DestType->isAnyPointerType() || 1651 DestType->isBlockPointerType(); 1652 bool srcIsPtr = SrcType->isAnyPointerType() || 1653 SrcType->isBlockPointerType(); 1654 if (!destIsPtr && !srcIsPtr) { 1655 // Except for std::nullptr_t->integer and lvalue->reference, which are 1656 // handled above, at least one of the two arguments must be a pointer. 1657 return TC_NotApplicable; 1658 } 1659 1660 if (DestType->isIntegralType(Self.Context)) { 1661 assert(srcIsPtr && "One type must be a pointer"); 1662 // C++ 5.2.10p4: A pointer can be explicitly converted to any integral 1663 // type large enough to hold it; except in Microsoft mode, where the 1664 // integral type size doesn't matter. 1665 if ((Self.Context.getTypeSize(SrcType) > 1666 Self.Context.getTypeSize(DestType)) && 1667 !Self.getLangOpts().MicrosoftExt) { 1668 msg = diag::err_bad_reinterpret_cast_small_int; 1669 return TC_Failed; 1670 } 1671 Kind = CK_PointerToIntegral; 1672 return TC_Success; 1673 } 1674 1675 if (SrcType->isIntegralOrEnumerationType()) { 1676 assert(destIsPtr && "One type must be a pointer"); 1677 // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly 1678 // converted to a pointer. 1679 // C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not 1680 // necessarily converted to a null pointer value.] 1681 Kind = CK_IntegralToPointer; 1682 return TC_Success; 1683 } 1684 1685 if (!destIsPtr || !srcIsPtr) { 1686 // With the valid non-pointer conversions out of the way, we can be even 1687 // more stringent. 1688 return TC_NotApplicable; 1689 } 1690 1691 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness. 1692 // The C-style cast operator can. 1693 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, 1694 /*CheckObjCLifetime=*/CStyle)) { 1695 msg = diag::err_bad_cxx_cast_qualifiers_away; 1696 return TC_Failed; 1697 } 1698 1699 // Cannot convert between block pointers and Objective-C object pointers. 1700 if ((SrcType->isBlockPointerType() && DestType->isObjCObjectPointerType()) || 1701 (DestType->isBlockPointerType() && SrcType->isObjCObjectPointerType())) 1702 return TC_NotApplicable; 1703 1704 if (IsLValueCast) { 1705 Kind = CK_LValueBitCast; 1706 } else if (DestType->isObjCObjectPointerType()) { 1707 Kind = Self.PrepareCastToObjCObjectPointer(SrcExpr); 1708 } else if (DestType->isBlockPointerType()) { 1709 if (!SrcType->isBlockPointerType()) { 1710 Kind = CK_AnyPointerToBlockPointerCast; 1711 } else { 1712 Kind = CK_BitCast; 1713 } 1714 } else { 1715 Kind = CK_BitCast; 1716 } 1717 1718 // Any pointer can be cast to an Objective-C pointer type with a C-style 1719 // cast. 1720 if (CStyle && DestType->isObjCObjectPointerType()) { 1721 return TC_Success; 1722 } 1723 1724 // Not casting away constness, so the only remaining check is for compatible 1725 // pointer categories. 1726 1727 if (SrcType->isFunctionPointerType()) { 1728 if (DestType->isFunctionPointerType()) { 1729 // C++ 5.2.10p6: A pointer to a function can be explicitly converted to 1730 // a pointer to a function of a different type. 1731 return TC_Success; 1732 } 1733 1734 // C++0x 5.2.10p8: Converting a pointer to a function into a pointer to 1735 // an object type or vice versa is conditionally-supported. 1736 // Compilers support it in C++03 too, though, because it's necessary for 1737 // casting the return value of dlsym() and GetProcAddress(). 1738 // FIXME: Conditionally-supported behavior should be configurable in the 1739 // TargetInfo or similar. 1740 Self.Diag(OpRange.getBegin(), 1741 Self.getLangOpts().CPlusPlus0x ? 1742 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj) 1743 << OpRange; 1744 return TC_Success; 1745 } 1746 1747 if (DestType->isFunctionPointerType()) { 1748 // See above. 1749 Self.Diag(OpRange.getBegin(), 1750 Self.getLangOpts().CPlusPlus0x ? 1751 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj) 1752 << OpRange; 1753 return TC_Success; 1754 } 1755 1756 // C++ 5.2.10p7: A pointer to an object can be explicitly converted to 1757 // a pointer to an object of different type. 1758 // Void pointers are not specified, but supported by every compiler out there. 1759 // So we finish by allowing everything that remains - it's got to be two 1760 // object pointers. 1761 return TC_Success; 1762 } 1763 1764 void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle, 1765 bool ListInitialization) { 1766 // Handle placeholders. 1767 if (isPlaceholder()) { 1768 // C-style casts can resolve __unknown_any types. 1769 if (claimPlaceholder(BuiltinType::UnknownAny)) { 1770 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 1771 SrcExpr.get(), Kind, 1772 ValueKind, BasePath); 1773 return; 1774 } 1775 1776 checkNonOverloadPlaceholders(); 1777 if (SrcExpr.isInvalid()) 1778 return; 1779 } 1780 1781 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 1782 // This test is outside everything else because it's the only case where 1783 // a non-lvalue-reference target type does not lead to decay. 1784 if (DestType->isVoidType()) { 1785 Kind = CK_ToVoid; 1786 1787 if (claimPlaceholder(BuiltinType::Overload)) { 1788 Self.ResolveAndFixSingleFunctionTemplateSpecialization( 1789 SrcExpr, /* Decay Function to ptr */ false, 1790 /* Complain */ true, DestRange, DestType, 1791 diag::err_bad_cstyle_cast_overload); 1792 if (SrcExpr.isInvalid()) 1793 return; 1794 } 1795 1796 SrcExpr = Self.IgnoredValueConversions(SrcExpr.take()); 1797 if (SrcExpr.isInvalid()) 1798 return; 1799 1800 return; 1801 } 1802 1803 // If the type is dependent, we won't do any other semantic analysis now. 1804 if (DestType->isDependentType() || SrcExpr.get()->isTypeDependent()) { 1805 assert(Kind == CK_Dependent); 1806 return; 1807 } 1808 1809 if (ValueKind == VK_RValue && !DestType->isRecordType() && 1810 !isPlaceholder(BuiltinType::Overload)) { 1811 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 1812 if (SrcExpr.isInvalid()) 1813 return; 1814 } 1815 1816 // AltiVec vector initialization with a single literal. 1817 if (const VectorType *vecTy = DestType->getAs<VectorType>()) 1818 if (vecTy->getVectorKind() == VectorType::AltiVecVector 1819 && (SrcExpr.get()->getType()->isIntegerType() 1820 || SrcExpr.get()->getType()->isFloatingType())) { 1821 Kind = CK_VectorSplat; 1822 return; 1823 } 1824 1825 // C++ [expr.cast]p5: The conversions performed by 1826 // - a const_cast, 1827 // - a static_cast, 1828 // - a static_cast followed by a const_cast, 1829 // - a reinterpret_cast, or 1830 // - a reinterpret_cast followed by a const_cast, 1831 // can be performed using the cast notation of explicit type conversion. 1832 // [...] If a conversion can be interpreted in more than one of the ways 1833 // listed above, the interpretation that appears first in the list is used, 1834 // even if a cast resulting from that interpretation is ill-formed. 1835 // In plain language, this means trying a const_cast ... 1836 unsigned msg = diag::err_bad_cxx_cast_generic; 1837 TryCastResult tcr = TryConstCast(Self, SrcExpr.get(), DestType, 1838 /*CStyle*/true, msg); 1839 if (tcr == TC_Success) 1840 Kind = CK_NoOp; 1841 1842 Sema::CheckedConversionKind CCK 1843 = FunctionalStyle? Sema::CCK_FunctionalCast 1844 : Sema::CCK_CStyleCast; 1845 if (tcr == TC_NotApplicable) { 1846 // ... or if that is not possible, a static_cast, ignoring const, ... 1847 tcr = TryStaticCast(Self, SrcExpr, DestType, CCK, OpRange, 1848 msg, Kind, BasePath, ListInitialization); 1849 if (SrcExpr.isInvalid()) 1850 return; 1851 1852 if (tcr == TC_NotApplicable) { 1853 // ... and finally a reinterpret_cast, ignoring const. 1854 tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/true, 1855 OpRange, msg, Kind); 1856 if (SrcExpr.isInvalid()) 1857 return; 1858 } 1859 } 1860 1861 if (Self.getLangOpts().ObjCAutoRefCount && tcr == TC_Success) 1862 checkObjCARCConversion(CCK); 1863 1864 if (tcr != TC_Success && msg != 0) { 1865 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 1866 DeclAccessPair Found; 1867 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 1868 DestType, 1869 /*Complain*/ true, 1870 Found); 1871 1872 assert(!Fn && "cast failed but able to resolve overload expression!!"); 1873 (void)Fn; 1874 1875 } else { 1876 diagnoseBadCast(Self, msg, (FunctionalStyle ? CT_Functional : CT_CStyle), 1877 OpRange, SrcExpr.get(), DestType, ListInitialization); 1878 } 1879 } else if (Kind == CK_BitCast) { 1880 checkCastAlign(); 1881 } 1882 1883 // Clear out SrcExpr if there was a fatal error. 1884 if (tcr != TC_Success) 1885 SrcExpr = ExprError(); 1886 } 1887 1888 /// Check the semantics of a C-style cast operation, in C. 1889 void CastOperation::CheckCStyleCast() { 1890 assert(!Self.getLangOpts().CPlusPlus); 1891 1892 // C-style casts can resolve __unknown_any types. 1893 if (claimPlaceholder(BuiltinType::UnknownAny)) { 1894 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 1895 SrcExpr.get(), Kind, 1896 ValueKind, BasePath); 1897 return; 1898 } 1899 1900 // C99 6.5.4p2: the cast type needs to be void or scalar and the expression 1901 // type needs to be scalar. 1902 if (DestType->isVoidType()) { 1903 // We don't necessarily do lvalue-to-rvalue conversions on this. 1904 SrcExpr = Self.IgnoredValueConversions(SrcExpr.take()); 1905 if (SrcExpr.isInvalid()) 1906 return; 1907 1908 // Cast to void allows any expr type. 1909 Kind = CK_ToVoid; 1910 return; 1911 } 1912 1913 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 1914 if (SrcExpr.isInvalid()) 1915 return; 1916 QualType SrcType = SrcExpr.get()->getType(); 1917 1918 // You can cast an _Atomic(T) to anything you can cast a T to. 1919 if (const AtomicType *AtomicSrcType = SrcType->getAs<AtomicType>()) 1920 SrcType = AtomicSrcType->getValueType(); 1921 1922 assert(!SrcType->isPlaceholderType()); 1923 1924 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 1925 diag::err_typecheck_cast_to_incomplete)) { 1926 SrcExpr = ExprError(); 1927 return; 1928 } 1929 1930 if (!DestType->isScalarType() && !DestType->isVectorType()) { 1931 const RecordType *DestRecordTy = DestType->getAs<RecordType>(); 1932 1933 if (DestRecordTy && Self.Context.hasSameUnqualifiedType(DestType, SrcType)){ 1934 // GCC struct/union extension: allow cast to self. 1935 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_nonscalar) 1936 << DestType << SrcExpr.get()->getSourceRange(); 1937 Kind = CK_NoOp; 1938 return; 1939 } 1940 1941 // GCC's cast to union extension. 1942 if (DestRecordTy && DestRecordTy->getDecl()->isUnion()) { 1943 RecordDecl *RD = DestRecordTy->getDecl(); 1944 RecordDecl::field_iterator Field, FieldEnd; 1945 for (Field = RD->field_begin(), FieldEnd = RD->field_end(); 1946 Field != FieldEnd; ++Field) { 1947 if (Self.Context.hasSameUnqualifiedType(Field->getType(), SrcType) && 1948 !Field->isUnnamedBitfield()) { 1949 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union) 1950 << SrcExpr.get()->getSourceRange(); 1951 break; 1952 } 1953 } 1954 if (Field == FieldEnd) { 1955 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cast_to_union_no_type) 1956 << SrcType << SrcExpr.get()->getSourceRange(); 1957 SrcExpr = ExprError(); 1958 return; 1959 } 1960 Kind = CK_ToUnion; 1961 return; 1962 } 1963 1964 // Reject any other conversions to non-scalar types. 1965 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cond_expect_scalar) 1966 << DestType << SrcExpr.get()->getSourceRange(); 1967 SrcExpr = ExprError(); 1968 return; 1969 } 1970 1971 // The type we're casting to is known to be a scalar or vector. 1972 1973 // Require the operand to be a scalar or vector. 1974 if (!SrcType->isScalarType() && !SrcType->isVectorType()) { 1975 Self.Diag(SrcExpr.get()->getExprLoc(), 1976 diag::err_typecheck_expect_scalar_operand) 1977 << SrcType << SrcExpr.get()->getSourceRange(); 1978 SrcExpr = ExprError(); 1979 return; 1980 } 1981 1982 if (DestType->isExtVectorType()) { 1983 SrcExpr = Self.CheckExtVectorCast(OpRange, DestType, SrcExpr.take(), Kind); 1984 return; 1985 } 1986 1987 if (const VectorType *DestVecTy = DestType->getAs<VectorType>()) { 1988 if (DestVecTy->getVectorKind() == VectorType::AltiVecVector && 1989 (SrcType->isIntegerType() || SrcType->isFloatingType())) { 1990 Kind = CK_VectorSplat; 1991 } else if (Self.CheckVectorCast(OpRange, DestType, SrcType, Kind)) { 1992 SrcExpr = ExprError(); 1993 } 1994 return; 1995 } 1996 1997 if (SrcType->isVectorType()) { 1998 if (Self.CheckVectorCast(OpRange, SrcType, DestType, Kind)) 1999 SrcExpr = ExprError(); 2000 return; 2001 } 2002 2003 // The source and target types are both scalars, i.e. 2004 // - arithmetic types (fundamental, enum, and complex) 2005 // - all kinds of pointers 2006 // Note that member pointers were filtered out with C++, above. 2007 2008 if (isa<ObjCSelectorExpr>(SrcExpr.get())) { 2009 Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_selector_expr); 2010 SrcExpr = ExprError(); 2011 return; 2012 } 2013 2014 // If either type is a pointer, the other type has to be either an 2015 // integer or a pointer. 2016 if (!DestType->isArithmeticType()) { 2017 if (!SrcType->isIntegralType(Self.Context) && SrcType->isArithmeticType()) { 2018 Self.Diag(SrcExpr.get()->getExprLoc(), 2019 diag::err_cast_pointer_from_non_pointer_int) 2020 << SrcType << SrcExpr.get()->getSourceRange(); 2021 SrcExpr = ExprError(); 2022 return; 2023 } 2024 } else if (!SrcType->isArithmeticType()) { 2025 if (!DestType->isIntegralType(Self.Context) && 2026 DestType->isArithmeticType()) { 2027 Self.Diag(SrcExpr.get()->getLocStart(), 2028 diag::err_cast_pointer_to_non_pointer_int) 2029 << DestType << SrcExpr.get()->getSourceRange(); 2030 SrcExpr = ExprError(); 2031 return; 2032 } 2033 } 2034 2035 // ARC imposes extra restrictions on casts. 2036 if (Self.getLangOpts().ObjCAutoRefCount) { 2037 checkObjCARCConversion(Sema::CCK_CStyleCast); 2038 if (SrcExpr.isInvalid()) 2039 return; 2040 2041 if (const PointerType *CastPtr = DestType->getAs<PointerType>()) { 2042 if (const PointerType *ExprPtr = SrcType->getAs<PointerType>()) { 2043 Qualifiers CastQuals = CastPtr->getPointeeType().getQualifiers(); 2044 Qualifiers ExprQuals = ExprPtr->getPointeeType().getQualifiers(); 2045 if (CastPtr->getPointeeType()->isObjCLifetimeType() && 2046 ExprPtr->getPointeeType()->isObjCLifetimeType() && 2047 !CastQuals.compatiblyIncludesObjCLifetime(ExprQuals)) { 2048 Self.Diag(SrcExpr.get()->getLocStart(), 2049 diag::err_typecheck_incompatible_ownership) 2050 << SrcType << DestType << Sema::AA_Casting 2051 << SrcExpr.get()->getSourceRange(); 2052 return; 2053 } 2054 } 2055 } 2056 else if (!Self.CheckObjCARCUnavailableWeakConversion(DestType, SrcType)) { 2057 Self.Diag(SrcExpr.get()->getLocStart(), 2058 diag::err_arc_convesion_of_weak_unavailable) 2059 << 1 << SrcType << DestType << SrcExpr.get()->getSourceRange(); 2060 SrcExpr = ExprError(); 2061 return; 2062 } 2063 } 2064 2065 Kind = Self.PrepareScalarCast(SrcExpr, DestType); 2066 if (SrcExpr.isInvalid()) 2067 return; 2068 2069 if (Kind == CK_BitCast) 2070 checkCastAlign(); 2071 } 2072 2073 ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc, 2074 TypeSourceInfo *CastTypeInfo, 2075 SourceLocation RPLoc, 2076 Expr *CastExpr) { 2077 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr); 2078 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2079 Op.OpRange = SourceRange(LPLoc, CastExpr->getLocEnd()); 2080 2081 if (getLangOpts().CPlusPlus) { 2082 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/ false, 2083 isa<InitListExpr>(CastExpr)); 2084 } else { 2085 Op.CheckCStyleCast(); 2086 } 2087 2088 if (Op.SrcExpr.isInvalid()) 2089 return ExprError(); 2090 2091 return Op.complete(CStyleCastExpr::Create(Context, Op.ResultType, 2092 Op.ValueKind, Op.Kind, Op.SrcExpr.take(), 2093 &Op.BasePath, CastTypeInfo, LPLoc, RPLoc)); 2094 } 2095 2096 ExprResult Sema::BuildCXXFunctionalCastExpr(TypeSourceInfo *CastTypeInfo, 2097 SourceLocation LPLoc, 2098 Expr *CastExpr, 2099 SourceLocation RPLoc) { 2100 assert(LPLoc.isValid() && "List-initialization shouldn't get here."); 2101 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr); 2102 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2103 Op.OpRange = SourceRange(Op.DestRange.getBegin(), CastExpr->getLocEnd()); 2104 2105 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/true, /*ListInit=*/false); 2106 if (Op.SrcExpr.isInvalid()) 2107 return ExprError(); 2108 2109 return Op.complete(CXXFunctionalCastExpr::Create(Context, Op.ResultType, 2110 Op.ValueKind, CastTypeInfo, Op.DestRange.getBegin(), 2111 Op.Kind, Op.SrcExpr.take(), &Op.BasePath, RPLoc)); 2112 } 2113