SemaCast.cpp revision 6dc00f6e98a00bd1c332927c3e04918d7e8b0d4f
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> 26using namespace clang; 27 28 29 30enum 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 37enum 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 46namespace { 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.getLangOptions().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 143static 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 157static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, 158 QualType DestType, bool CStyle, 159 CastKind &Kind, 160 CXXCastPath &BasePath, 161 unsigned &msg); 162static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, 163 QualType DestType, bool CStyle, 164 const SourceRange &OpRange, 165 unsigned &msg, 166 CastKind &Kind, 167 CXXCastPath &BasePath); 168static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType, 169 QualType DestType, bool CStyle, 170 const SourceRange &OpRange, 171 unsigned &msg, 172 CastKind &Kind, 173 CXXCastPath &BasePath); 174static 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); 181static 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 189static 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); 195static 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); 202static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType, 203 bool CStyle, unsigned &msg); 204static 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. 212ExprResult 213Sema::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 (getLangOptions().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 235ExprResult 236Sema::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. 302static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT, 303 SourceRange range, Expr *src, 304 QualType destType) { 305 switch (CT) { 306 // These cast kinds don't consider user-defined conversions. 307 case CT_Const: 308 case CT_Reinterpret: 309 case CT_Dynamic: 310 return false; 311 312 // These do. 313 case CT_Static: 314 case CT_CStyle: 315 case CT_Functional: 316 break; 317 } 318 319 QualType srcType = src->getType(); 320 if (!destType->isRecordType() && !srcType->isRecordType()) 321 return false; 322 323 bool initList = isa<InitListExpr>(src); 324 InitializedEntity entity = InitializedEntity::InitializeTemporary(destType); 325 InitializationKind initKind 326 = (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(), 327 range, initList) 328 : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range, 329 initList) 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, 1); 373 374 return true; 375} 376 377/// Diagnose a failed cast. 378static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType, 379 SourceRange opRange, Expr *src, QualType destType) { 380 if (src->getType() == S.Context.BoundMemberTy) { 381 (void) S.CheckPlaceholderExpr(src); // will always fail 382 return; 383 } 384 385 if (msg == diag::err_bad_cxx_cast_generic && 386 tryDiagnoseOverloadedCast(S, castType, opRange, src, destType)) 387 return; 388 389 S.Diag(opRange.getBegin(), msg) << castType 390 << src->getType() << destType << opRange << src->getSourceRange(); 391} 392 393/// UnwrapDissimilarPointerTypes - Like Sema::UnwrapSimilarPointerTypes, 394/// this removes one level of indirection from both types, provided that they're 395/// the same kind of pointer (plain or to-member). Unlike the Sema function, 396/// this one doesn't care if the two pointers-to-member don't point into the 397/// same class. This is because CastsAwayConstness doesn't care. 398static bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) { 399 const PointerType *T1PtrType = T1->getAs<PointerType>(), 400 *T2PtrType = T2->getAs<PointerType>(); 401 if (T1PtrType && T2PtrType) { 402 T1 = T1PtrType->getPointeeType(); 403 T2 = T2PtrType->getPointeeType(); 404 return true; 405 } 406 const ObjCObjectPointerType *T1ObjCPtrType = 407 T1->getAs<ObjCObjectPointerType>(), 408 *T2ObjCPtrType = 409 T2->getAs<ObjCObjectPointerType>(); 410 if (T1ObjCPtrType) { 411 if (T2ObjCPtrType) { 412 T1 = T1ObjCPtrType->getPointeeType(); 413 T2 = T2ObjCPtrType->getPointeeType(); 414 return true; 415 } 416 else if (T2PtrType) { 417 T1 = T1ObjCPtrType->getPointeeType(); 418 T2 = T2PtrType->getPointeeType(); 419 return true; 420 } 421 } 422 else if (T2ObjCPtrType) { 423 if (T1PtrType) { 424 T2 = T2ObjCPtrType->getPointeeType(); 425 T1 = T1PtrType->getPointeeType(); 426 return true; 427 } 428 } 429 430 const MemberPointerType *T1MPType = T1->getAs<MemberPointerType>(), 431 *T2MPType = T2->getAs<MemberPointerType>(); 432 if (T1MPType && T2MPType) { 433 T1 = T1MPType->getPointeeType(); 434 T2 = T2MPType->getPointeeType(); 435 return true; 436 } 437 438 const BlockPointerType *T1BPType = T1->getAs<BlockPointerType>(), 439 *T2BPType = T2->getAs<BlockPointerType>(); 440 if (T1BPType && T2BPType) { 441 T1 = T1BPType->getPointeeType(); 442 T2 = T2BPType->getPointeeType(); 443 return true; 444 } 445 446 return false; 447} 448 449/// CastsAwayConstness - Check if the pointer conversion from SrcType to 450/// DestType casts away constness as defined in C++ 5.2.11p8ff. This is used by 451/// the cast checkers. Both arguments must denote pointer (possibly to member) 452/// types. 453/// 454/// \param CheckCVR Whether to check for const/volatile/restrict qualifiers. 455/// 456/// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers. 457static bool 458CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, 459 bool CheckCVR, bool CheckObjCLifetime) { 460 // If the only checking we care about is for Objective-C lifetime qualifiers, 461 // and we're not in ARC mode, there's nothing to check. 462 if (!CheckCVR && CheckObjCLifetime && 463 !Self.Context.getLangOptions().ObjCAutoRefCount) 464 return false; 465 466 // Casting away constness is defined in C++ 5.2.11p8 with reference to 467 // C++ 4.4. We piggyback on Sema::IsQualificationConversion for this, since 468 // the rules are non-trivial. So first we construct Tcv *...cv* as described 469 // in C++ 5.2.11p8. 470 assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() || 471 SrcType->isBlockPointerType()) && 472 "Source type is not pointer or pointer to member."); 473 assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() || 474 DestType->isBlockPointerType()) && 475 "Destination type is not pointer or pointer to member."); 476 477 QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType), 478 UnwrappedDestType = Self.Context.getCanonicalType(DestType); 479 SmallVector<Qualifiers, 8> cv1, cv2; 480 481 // Find the qualifiers. We only care about cvr-qualifiers for the 482 // purpose of this check, because other qualifiers (address spaces, 483 // Objective-C GC, etc.) are part of the type's identity. 484 while (UnwrapDissimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) { 485 // Determine the relevant qualifiers at this level. 486 Qualifiers SrcQuals, DestQuals; 487 Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals); 488 Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals); 489 490 Qualifiers RetainedSrcQuals, RetainedDestQuals; 491 if (CheckCVR) { 492 RetainedSrcQuals.setCVRQualifiers(SrcQuals.getCVRQualifiers()); 493 RetainedDestQuals.setCVRQualifiers(DestQuals.getCVRQualifiers()); 494 } 495 496 if (CheckObjCLifetime && 497 !DestQuals.compatiblyIncludesObjCLifetime(SrcQuals)) 498 return true; 499 500 cv1.push_back(RetainedSrcQuals); 501 cv2.push_back(RetainedDestQuals); 502 } 503 if (cv1.empty()) 504 return false; 505 506 // Construct void pointers with those qualifiers (in reverse order of 507 // unwrapping, of course). 508 QualType SrcConstruct = Self.Context.VoidTy; 509 QualType DestConstruct = Self.Context.VoidTy; 510 ASTContext &Context = Self.Context; 511 for (SmallVector<Qualifiers, 8>::reverse_iterator i1 = cv1.rbegin(), 512 i2 = cv2.rbegin(); 513 i1 != cv1.rend(); ++i1, ++i2) { 514 SrcConstruct 515 = Context.getPointerType(Context.getQualifiedType(SrcConstruct, *i1)); 516 DestConstruct 517 = Context.getPointerType(Context.getQualifiedType(DestConstruct, *i2)); 518 } 519 520 // Test if they're compatible. 521 bool ObjCLifetimeConversion; 522 return SrcConstruct != DestConstruct && 523 !Self.IsQualificationConversion(SrcConstruct, DestConstruct, false, 524 ObjCLifetimeConversion); 525} 526 527/// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid. 528/// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime- 529/// checked downcasts in class hierarchies. 530void CastOperation::CheckDynamicCast() { 531 if (ValueKind == VK_RValue) 532 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 533 else if (isPlaceholder()) 534 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.take()); 535 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 536 return; 537 538 QualType OrigSrcType = SrcExpr.get()->getType(); 539 QualType DestType = Self.Context.getCanonicalType(this->DestType); 540 541 // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type, 542 // or "pointer to cv void". 543 544 QualType DestPointee; 545 const PointerType *DestPointer = DestType->getAs<PointerType>(); 546 const ReferenceType *DestReference = 0; 547 if (DestPointer) { 548 DestPointee = DestPointer->getPointeeType(); 549 } else if ((DestReference = DestType->getAs<ReferenceType>())) { 550 DestPointee = DestReference->getPointeeType(); 551 } else { 552 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr) 553 << this->DestType << DestRange; 554 return; 555 } 556 557 const RecordType *DestRecord = DestPointee->getAs<RecordType>(); 558 if (DestPointee->isVoidType()) { 559 assert(DestPointer && "Reference to void is not possible"); 560 } else if (DestRecord) { 561 if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee, 562 Self.PDiag(diag::err_bad_dynamic_cast_incomplete) 563 << DestRange)) 564 return; 565 } else { 566 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 567 << DestPointee.getUnqualifiedType() << DestRange; 568 return; 569 } 570 571 // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to 572 // complete class type, [...]. If T is an lvalue reference type, v shall be 573 // an lvalue of a complete class type, [...]. If T is an rvalue reference 574 // type, v shall be an expression having a complete class type, [...] 575 QualType SrcType = Self.Context.getCanonicalType(OrigSrcType); 576 QualType SrcPointee; 577 if (DestPointer) { 578 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 579 SrcPointee = SrcPointer->getPointeeType(); 580 } else { 581 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr) 582 << OrigSrcType << SrcExpr.get()->getSourceRange(); 583 return; 584 } 585 } else if (DestReference->isLValueReferenceType()) { 586 if (!SrcExpr.get()->isLValue()) { 587 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue) 588 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 589 } 590 SrcPointee = SrcType; 591 } else { 592 SrcPointee = SrcType; 593 } 594 595 const RecordType *SrcRecord = SrcPointee->getAs<RecordType>(); 596 if (SrcRecord) { 597 if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee, 598 Self.PDiag(diag::err_bad_dynamic_cast_incomplete) 599 << SrcExpr.get()->getSourceRange())) 600 return; 601 } else { 602 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 603 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 604 return; 605 } 606 607 assert((DestPointer || DestReference) && 608 "Bad destination non-ptr/ref slipped through."); 609 assert((DestRecord || DestPointee->isVoidType()) && 610 "Bad destination pointee slipped through."); 611 assert(SrcRecord && "Bad source pointee slipped through."); 612 613 // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness. 614 if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) { 615 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away) 616 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 617 return; 618 } 619 620 // C++ 5.2.7p3: If the type of v is the same as the required result type, 621 // [except for cv]. 622 if (DestRecord == SrcRecord) { 623 Kind = CK_NoOp; 624 return; 625 } 626 627 // C++ 5.2.7p5 628 // Upcasts are resolved statically. 629 if (DestRecord && Self.IsDerivedFrom(SrcPointee, DestPointee)) { 630 if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee, 631 OpRange.getBegin(), OpRange, 632 &BasePath)) 633 return; 634 635 Kind = CK_DerivedToBase; 636 637 // If we are casting to or through a virtual base class, we need a 638 // vtable. 639 if (Self.BasePathInvolvesVirtualBase(BasePath)) 640 Self.MarkVTableUsed(OpRange.getBegin(), 641 cast<CXXRecordDecl>(SrcRecord->getDecl())); 642 return; 643 } 644 645 // C++ 5.2.7p6: Otherwise, v shall be [polymorphic]. 646 const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition(); 647 assert(SrcDecl && "Definition missing"); 648 if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) { 649 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic) 650 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 651 } 652 Self.MarkVTableUsed(OpRange.getBegin(), 653 cast<CXXRecordDecl>(SrcRecord->getDecl())); 654 655 // Done. Everything else is run-time checks. 656 Kind = CK_Dynamic; 657} 658 659/// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid. 660/// Refer to C++ 5.2.11 for details. const_cast is typically used in code 661/// like this: 662/// const char *str = "literal"; 663/// legacy_function(const_cast\<char*\>(str)); 664void CastOperation::CheckConstCast() { 665 if (ValueKind == VK_RValue) 666 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 667 else if (isPlaceholder()) 668 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.take()); 669 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 670 return; 671 672 unsigned msg = diag::err_bad_cxx_cast_generic; 673 if (TryConstCast(Self, SrcExpr.get(), DestType, /*CStyle*/false, msg) != TC_Success 674 && msg != 0) 675 Self.Diag(OpRange.getBegin(), msg) << CT_Const 676 << SrcExpr.get()->getType() << DestType << OpRange; 677} 678 679/// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is 680/// valid. 681/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code 682/// like this: 683/// char *bytes = reinterpret_cast\<char*\>(int_ptr); 684void CastOperation::CheckReinterpretCast() { 685 if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload)) 686 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 687 else 688 checkNonOverloadPlaceholders(); 689 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 690 return; 691 692 unsigned msg = diag::err_bad_cxx_cast_generic; 693 TryCastResult tcr = 694 TryReinterpretCast(Self, SrcExpr, DestType, 695 /*CStyle*/false, OpRange, msg, Kind); 696 if (tcr != TC_Success && msg != 0) 697 { 698 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 699 return; 700 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 701 //FIXME: &f<int>; is overloaded and resolvable 702 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload) 703 << OverloadExpr::find(SrcExpr.get()).Expression->getName() 704 << DestType << OpRange; 705 Self.NoteAllOverloadCandidates(SrcExpr.get()); 706 707 } else { 708 diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(), DestType); 709 } 710 } else if (tcr == TC_Success && Self.getLangOptions().ObjCAutoRefCount) { 711 checkObjCARCConversion(Sema::CCK_OtherCast); 712 } 713} 714 715 716/// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid. 717/// Refer to C++ 5.2.9 for details. Static casts are mostly used for making 718/// implicit conversions explicit and getting rid of data loss warnings. 719void CastOperation::CheckStaticCast() { 720 if (isPlaceholder()) { 721 checkNonOverloadPlaceholders(); 722 if (SrcExpr.isInvalid()) 723 return; 724 } 725 726 // This test is outside everything else because it's the only case where 727 // a non-lvalue-reference target type does not lead to decay. 728 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 729 if (DestType->isVoidType()) { 730 Kind = CK_ToVoid; 731 732 if (claimPlaceholder(BuiltinType::Overload)) { 733 Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr, 734 false, // Decay Function to ptr 735 true, // Complain 736 OpRange, DestType, diag::err_bad_static_cast_overload); 737 if (SrcExpr.isInvalid()) 738 return; 739 } 740 741 SrcExpr = Self.IgnoredValueConversions(SrcExpr.take()); 742 return; 743 } 744 745 if (ValueKind == VK_RValue && !DestType->isRecordType() && 746 !isPlaceholder(BuiltinType::Overload)) { 747 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 748 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 749 return; 750 } 751 752 unsigned msg = diag::err_bad_cxx_cast_generic; 753 TryCastResult tcr 754 = TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_OtherCast, OpRange, msg, 755 Kind, BasePath, /*ListInitialization=*/false); 756 if (tcr != TC_Success && msg != 0) { 757 if (SrcExpr.isInvalid()) 758 return; 759 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 760 OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression; 761 Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload) 762 << oe->getName() << DestType << OpRange 763 << oe->getQualifierLoc().getSourceRange(); 764 Self.NoteAllOverloadCandidates(SrcExpr.get()); 765 } else { 766 diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType); 767 } 768 } else if (tcr == TC_Success) { 769 if (Kind == CK_BitCast) 770 checkCastAlign(); 771 if (Self.getLangOptions().ObjCAutoRefCount) 772 checkObjCARCConversion(Sema::CCK_OtherCast); 773 } else if (Kind == CK_BitCast) { 774 checkCastAlign(); 775 } 776} 777 778/// TryStaticCast - Check if a static cast can be performed, and do so if 779/// possible. If @p CStyle, ignore access restrictions on hierarchy casting 780/// and casting away constness. 781static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, 782 QualType DestType, 783 Sema::CheckedConversionKind CCK, 784 const SourceRange &OpRange, unsigned &msg, 785 CastKind &Kind, CXXCastPath &BasePath, 786 bool ListInitialization) { 787 // Determine whether we have the semantics of a C-style cast. 788 bool CStyle 789 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 790 791 // The order the tests is not entirely arbitrary. There is one conversion 792 // that can be handled in two different ways. Given: 793 // struct A {}; 794 // struct B : public A { 795 // B(); B(const A&); 796 // }; 797 // const A &a = B(); 798 // the cast static_cast<const B&>(a) could be seen as either a static 799 // reference downcast, or an explicit invocation of the user-defined 800 // conversion using B's conversion constructor. 801 // DR 427 specifies that the downcast is to be applied here. 802 803 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 804 // Done outside this function. 805 806 TryCastResult tcr; 807 808 // C++ 5.2.9p5, reference downcast. 809 // See the function for details. 810 // DR 427 specifies that this is to be applied before paragraph 2. 811 tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle, 812 OpRange, msg, Kind, BasePath); 813 if (tcr != TC_NotApplicable) 814 return tcr; 815 816 // C++0x [expr.static.cast]p3: 817 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2 818 // T2" if "cv2 T2" is reference-compatible with "cv1 T1". 819 tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind, 820 BasePath, msg); 821 if (tcr != TC_NotApplicable) 822 return tcr; 823 824 // C++ 5.2.9p2: An expression e can be explicitly converted to a type T 825 // [...] if the declaration "T t(e);" is well-formed, [...]. 826 tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg, 827 Kind, ListInitialization); 828 if (SrcExpr.isInvalid()) 829 return TC_Failed; 830 if (tcr != TC_NotApplicable) 831 return tcr; 832 833 // C++ 5.2.9p6: May apply the reverse of any standard conversion, except 834 // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean 835 // conversions, subject to further restrictions. 836 // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal 837 // of qualification conversions impossible. 838 // In the CStyle case, the earlier attempt to const_cast should have taken 839 // care of reverse qualification conversions. 840 841 QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType()); 842 843 // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly 844 // converted to an integral type. [...] A value of a scoped enumeration type 845 // can also be explicitly converted to a floating-point type [...]. 846 if (const EnumType *Enum = SrcType->getAs<EnumType>()) { 847 if (Enum->getDecl()->isScoped()) { 848 if (DestType->isBooleanType()) { 849 Kind = CK_IntegralToBoolean; 850 return TC_Success; 851 } else if (DestType->isIntegralType(Self.Context)) { 852 Kind = CK_IntegralCast; 853 return TC_Success; 854 } else if (DestType->isRealFloatingType()) { 855 Kind = CK_IntegralToFloating; 856 return TC_Success; 857 } 858 } 859 } 860 861 // Reverse integral promotion/conversion. All such conversions are themselves 862 // again integral promotions or conversions and are thus already handled by 863 // p2 (TryDirectInitialization above). 864 // (Note: any data loss warnings should be suppressed.) 865 // The exception is the reverse of enum->integer, i.e. integer->enum (and 866 // enum->enum). See also C++ 5.2.9p7. 867 // The same goes for reverse floating point promotion/conversion and 868 // floating-integral conversions. Again, only floating->enum is relevant. 869 if (DestType->isEnumeralType()) { 870 if (SrcType->isIntegralOrEnumerationType()) { 871 Kind = CK_IntegralCast; 872 return TC_Success; 873 } else if (SrcType->isRealFloatingType()) { 874 Kind = CK_FloatingToIntegral; 875 return TC_Success; 876 } 877 } 878 879 // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast. 880 // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance. 881 tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg, 882 Kind, BasePath); 883 if (tcr != TC_NotApplicable) 884 return tcr; 885 886 // Reverse member pointer conversion. C++ 4.11 specifies member pointer 887 // conversion. C++ 5.2.9p9 has additional information. 888 // DR54's access restrictions apply here also. 889 tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle, 890 OpRange, msg, Kind, BasePath); 891 if (tcr != TC_NotApplicable) 892 return tcr; 893 894 // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to 895 // void*. C++ 5.2.9p10 specifies additional restrictions, which really is 896 // just the usual constness stuff. 897 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 898 QualType SrcPointee = SrcPointer->getPointeeType(); 899 if (SrcPointee->isVoidType()) { 900 if (const PointerType *DestPointer = DestType->getAs<PointerType>()) { 901 QualType DestPointee = DestPointer->getPointeeType(); 902 if (DestPointee->isIncompleteOrObjectType()) { 903 // This is definitely the intended conversion, but it might fail due 904 // to a qualifier violation. Note that we permit Objective-C lifetime 905 // and GC qualifier mismatches here. 906 if (!CStyle) { 907 Qualifiers DestPointeeQuals = DestPointee.getQualifiers(); 908 Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers(); 909 DestPointeeQuals.removeObjCGCAttr(); 910 DestPointeeQuals.removeObjCLifetime(); 911 SrcPointeeQuals.removeObjCGCAttr(); 912 SrcPointeeQuals.removeObjCLifetime(); 913 if (DestPointeeQuals != SrcPointeeQuals && 914 !DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) { 915 msg = diag::err_bad_cxx_cast_qualifiers_away; 916 return TC_Failed; 917 } 918 } 919 Kind = CK_BitCast; 920 return TC_Success; 921 } 922 } 923 else if (DestType->isObjCObjectPointerType()) { 924 // allow both c-style cast and static_cast of objective-c pointers as 925 // they are pervasive. 926 Kind = CK_CPointerToObjCPointerCast; 927 return TC_Success; 928 } 929 else if (CStyle && DestType->isBlockPointerType()) { 930 // allow c-style cast of void * to block pointers. 931 Kind = CK_AnyPointerToBlockPointerCast; 932 return TC_Success; 933 } 934 } 935 } 936 // Allow arbitray objective-c pointer conversion with static casts. 937 if (SrcType->isObjCObjectPointerType() && 938 DestType->isObjCObjectPointerType()) { 939 Kind = CK_BitCast; 940 return TC_Success; 941 } 942 943 // We tried everything. Everything! Nothing works! :-( 944 return TC_NotApplicable; 945} 946 947/// Tests whether a conversion according to N2844 is valid. 948TryCastResult 949TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType, 950 bool CStyle, CastKind &Kind, CXXCastPath &BasePath, 951 unsigned &msg) { 952 // C++0x [expr.static.cast]p3: 953 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to 954 // cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1". 955 const RValueReferenceType *R = DestType->getAs<RValueReferenceType>(); 956 if (!R) 957 return TC_NotApplicable; 958 959 if (!SrcExpr->isGLValue()) 960 return TC_NotApplicable; 961 962 // Because we try the reference downcast before this function, from now on 963 // this is the only cast possibility, so we issue an error if we fail now. 964 // FIXME: Should allow casting away constness if CStyle. 965 bool DerivedToBase; 966 bool ObjCConversion; 967 bool ObjCLifetimeConversion; 968 QualType FromType = SrcExpr->getType(); 969 QualType ToType = R->getPointeeType(); 970 if (CStyle) { 971 FromType = FromType.getUnqualifiedType(); 972 ToType = ToType.getUnqualifiedType(); 973 } 974 975 if (Self.CompareReferenceRelationship(SrcExpr->getLocStart(), 976 ToType, FromType, 977 DerivedToBase, ObjCConversion, 978 ObjCLifetimeConversion) 979 < Sema::Ref_Compatible_With_Added_Qualification) { 980 msg = diag::err_bad_lvalue_to_rvalue_cast; 981 return TC_Failed; 982 } 983 984 if (DerivedToBase) { 985 Kind = CK_DerivedToBase; 986 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 987 /*DetectVirtual=*/true); 988 if (!Self.IsDerivedFrom(SrcExpr->getType(), R->getPointeeType(), Paths)) 989 return TC_NotApplicable; 990 991 Self.BuildBasePathArray(Paths, BasePath); 992 } else 993 Kind = CK_NoOp; 994 995 return TC_Success; 996} 997 998/// Tests whether a conversion according to C++ 5.2.9p5 is valid. 999TryCastResult 1000TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType, 1001 bool CStyle, const SourceRange &OpRange, 1002 unsigned &msg, CastKind &Kind, 1003 CXXCastPath &BasePath) { 1004 // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be 1005 // cast to type "reference to cv2 D", where D is a class derived from B, 1006 // if a valid standard conversion from "pointer to D" to "pointer to B" 1007 // exists, cv2 >= cv1, and B is not a virtual base class of D. 1008 // In addition, DR54 clarifies that the base must be accessible in the 1009 // current context. Although the wording of DR54 only applies to the pointer 1010 // variant of this rule, the intent is clearly for it to apply to the this 1011 // conversion as well. 1012 1013 const ReferenceType *DestReference = DestType->getAs<ReferenceType>(); 1014 if (!DestReference) { 1015 return TC_NotApplicable; 1016 } 1017 bool RValueRef = DestReference->isRValueReferenceType(); 1018 if (!RValueRef && !SrcExpr->isLValue()) { 1019 // We know the left side is an lvalue reference, so we can suggest a reason. 1020 msg = diag::err_bad_cxx_cast_rvalue; 1021 return TC_NotApplicable; 1022 } 1023 1024 QualType DestPointee = DestReference->getPointeeType(); 1025 1026 return TryStaticDowncast(Self, 1027 Self.Context.getCanonicalType(SrcExpr->getType()), 1028 Self.Context.getCanonicalType(DestPointee), CStyle, 1029 OpRange, SrcExpr->getType(), DestType, msg, Kind, 1030 BasePath); 1031} 1032 1033/// Tests whether a conversion according to C++ 5.2.9p8 is valid. 1034TryCastResult 1035TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType, 1036 bool CStyle, const SourceRange &OpRange, 1037 unsigned &msg, CastKind &Kind, 1038 CXXCastPath &BasePath) { 1039 // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class 1040 // type, can be converted to an rvalue of type "pointer to cv2 D", where D 1041 // is a class derived from B, if a valid standard conversion from "pointer 1042 // to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base 1043 // class of D. 1044 // In addition, DR54 clarifies that the base must be accessible in the 1045 // current context. 1046 1047 const PointerType *DestPointer = DestType->getAs<PointerType>(); 1048 if (!DestPointer) { 1049 return TC_NotApplicable; 1050 } 1051 1052 const PointerType *SrcPointer = SrcType->getAs<PointerType>(); 1053 if (!SrcPointer) { 1054 msg = diag::err_bad_static_cast_pointer_nonpointer; 1055 return TC_NotApplicable; 1056 } 1057 1058 return TryStaticDowncast(Self, 1059 Self.Context.getCanonicalType(SrcPointer->getPointeeType()), 1060 Self.Context.getCanonicalType(DestPointer->getPointeeType()), 1061 CStyle, OpRange, SrcType, DestType, msg, Kind, 1062 BasePath); 1063} 1064 1065/// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and 1066/// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to 1067/// DestType is possible and allowed. 1068TryCastResult 1069TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType, 1070 bool CStyle, const SourceRange &OpRange, QualType OrigSrcType, 1071 QualType OrigDestType, unsigned &msg, 1072 CastKind &Kind, CXXCastPath &BasePath) { 1073 // We can only work with complete types. But don't complain if it doesn't work 1074 if (Self.RequireCompleteType(OpRange.getBegin(), SrcType, Self.PDiag(0)) || 1075 Self.RequireCompleteType(OpRange.getBegin(), DestType, Self.PDiag(0))) 1076 return TC_NotApplicable; 1077 1078 // Downcast can only happen in class hierarchies, so we need classes. 1079 if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) { 1080 return TC_NotApplicable; 1081 } 1082 1083 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1084 /*DetectVirtual=*/true); 1085 if (!Self.IsDerivedFrom(DestType, SrcType, Paths)) { 1086 return TC_NotApplicable; 1087 } 1088 1089 // Target type does derive from source type. Now we're serious. If an error 1090 // appears now, it's not ignored. 1091 // This may not be entirely in line with the standard. Take for example: 1092 // struct A {}; 1093 // struct B : virtual A { 1094 // B(A&); 1095 // }; 1096 // 1097 // void f() 1098 // { 1099 // (void)static_cast<const B&>(*((A*)0)); 1100 // } 1101 // As far as the standard is concerned, p5 does not apply (A is virtual), so 1102 // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid. 1103 // However, both GCC and Comeau reject this example, and accepting it would 1104 // mean more complex code if we're to preserve the nice error message. 1105 // FIXME: Being 100% compliant here would be nice to have. 1106 1107 // Must preserve cv, as always, unless we're in C-style mode. 1108 if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) { 1109 msg = diag::err_bad_cxx_cast_qualifiers_away; 1110 return TC_Failed; 1111 } 1112 1113 if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) { 1114 // This code is analoguous to that in CheckDerivedToBaseConversion, except 1115 // that it builds the paths in reverse order. 1116 // To sum up: record all paths to the base and build a nice string from 1117 // them. Use it to spice up the error message. 1118 if (!Paths.isRecordingPaths()) { 1119 Paths.clear(); 1120 Paths.setRecordingPaths(true); 1121 Self.IsDerivedFrom(DestType, SrcType, Paths); 1122 } 1123 std::string PathDisplayStr; 1124 std::set<unsigned> DisplayedPaths; 1125 for (CXXBasePaths::paths_iterator PI = Paths.begin(), PE = Paths.end(); 1126 PI != PE; ++PI) { 1127 if (DisplayedPaths.insert(PI->back().SubobjectNumber).second) { 1128 // We haven't displayed a path to this particular base 1129 // class subobject yet. 1130 PathDisplayStr += "\n "; 1131 for (CXXBasePath::const_reverse_iterator EI = PI->rbegin(), 1132 EE = PI->rend(); 1133 EI != EE; ++EI) 1134 PathDisplayStr += EI->Base->getType().getAsString() + " -> "; 1135 PathDisplayStr += QualType(DestType).getAsString(); 1136 } 1137 } 1138 1139 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast) 1140 << QualType(SrcType).getUnqualifiedType() 1141 << QualType(DestType).getUnqualifiedType() 1142 << PathDisplayStr << OpRange; 1143 msg = 0; 1144 return TC_Failed; 1145 } 1146 1147 if (Paths.getDetectedVirtual() != 0) { 1148 QualType VirtualBase(Paths.getDetectedVirtual(), 0); 1149 Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual) 1150 << OrigSrcType << OrigDestType << VirtualBase << OpRange; 1151 msg = 0; 1152 return TC_Failed; 1153 } 1154 1155 if (!CStyle) { 1156 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1157 SrcType, DestType, 1158 Paths.front(), 1159 diag::err_downcast_from_inaccessible_base)) { 1160 case Sema::AR_accessible: 1161 case Sema::AR_delayed: // be optimistic 1162 case Sema::AR_dependent: // be optimistic 1163 break; 1164 1165 case Sema::AR_inaccessible: 1166 msg = 0; 1167 return TC_Failed; 1168 } 1169 } 1170 1171 Self.BuildBasePathArray(Paths, BasePath); 1172 Kind = CK_BaseToDerived; 1173 return TC_Success; 1174} 1175 1176/// TryStaticMemberPointerUpcast - Tests whether a conversion according to 1177/// C++ 5.2.9p9 is valid: 1178/// 1179/// An rvalue of type "pointer to member of D of type cv1 T" can be 1180/// converted to an rvalue of type "pointer to member of B of type cv2 T", 1181/// where B is a base class of D [...]. 1182/// 1183TryCastResult 1184TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType, 1185 QualType DestType, bool CStyle, 1186 const SourceRange &OpRange, 1187 unsigned &msg, CastKind &Kind, 1188 CXXCastPath &BasePath) { 1189 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(); 1190 if (!DestMemPtr) 1191 return TC_NotApplicable; 1192 1193 bool WasOverloadedFunction = false; 1194 DeclAccessPair FoundOverload; 1195 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 1196 if (FunctionDecl *Fn 1197 = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false, 1198 FoundOverload)) { 1199 CXXMethodDecl *M = cast<CXXMethodDecl>(Fn); 1200 SrcType = Self.Context.getMemberPointerType(Fn->getType(), 1201 Self.Context.getTypeDeclType(M->getParent()).getTypePtr()); 1202 WasOverloadedFunction = true; 1203 } 1204 } 1205 1206 const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 1207 if (!SrcMemPtr) { 1208 msg = diag::err_bad_static_cast_member_pointer_nonmp; 1209 return TC_NotApplicable; 1210 } 1211 1212 // T == T, modulo cv 1213 if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(), 1214 DestMemPtr->getPointeeType())) 1215 return TC_NotApplicable; 1216 1217 // B base of D 1218 QualType SrcClass(SrcMemPtr->getClass(), 0); 1219 QualType DestClass(DestMemPtr->getClass(), 0); 1220 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1221 /*DetectVirtual=*/true); 1222 if (!Self.IsDerivedFrom(SrcClass, DestClass, Paths)) { 1223 return TC_NotApplicable; 1224 } 1225 1226 // B is a base of D. But is it an allowed base? If not, it's a hard error. 1227 if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) { 1228 Paths.clear(); 1229 Paths.setRecordingPaths(true); 1230 bool StillOkay = Self.IsDerivedFrom(SrcClass, DestClass, Paths); 1231 assert(StillOkay); 1232 (void)StillOkay; 1233 std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths); 1234 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv) 1235 << 1 << SrcClass << DestClass << PathDisplayStr << OpRange; 1236 msg = 0; 1237 return TC_Failed; 1238 } 1239 1240 if (const RecordType *VBase = Paths.getDetectedVirtual()) { 1241 Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual) 1242 << SrcClass << DestClass << QualType(VBase, 0) << OpRange; 1243 msg = 0; 1244 return TC_Failed; 1245 } 1246 1247 if (!CStyle) { 1248 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1249 DestClass, SrcClass, 1250 Paths.front(), 1251 diag::err_upcast_to_inaccessible_base)) { 1252 case Sema::AR_accessible: 1253 case Sema::AR_delayed: 1254 case Sema::AR_dependent: 1255 // Optimistically assume that the delayed and dependent cases 1256 // will work out. 1257 break; 1258 1259 case Sema::AR_inaccessible: 1260 msg = 0; 1261 return TC_Failed; 1262 } 1263 } 1264 1265 if (WasOverloadedFunction) { 1266 // Resolve the address of the overloaded function again, this time 1267 // allowing complaints if something goes wrong. 1268 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 1269 DestType, 1270 true, 1271 FoundOverload); 1272 if (!Fn) { 1273 msg = 0; 1274 return TC_Failed; 1275 } 1276 1277 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn); 1278 if (!SrcExpr.isUsable()) { 1279 msg = 0; 1280 return TC_Failed; 1281 } 1282 } 1283 1284 Self.BuildBasePathArray(Paths, BasePath); 1285 Kind = CK_DerivedToBaseMemberPointer; 1286 return TC_Success; 1287} 1288 1289/// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2 1290/// is valid: 1291/// 1292/// An expression e can be explicitly converted to a type T using a 1293/// @c static_cast if the declaration "T t(e);" is well-formed [...]. 1294TryCastResult 1295TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, 1296 Sema::CheckedConversionKind CCK, 1297 const SourceRange &OpRange, unsigned &msg, 1298 CastKind &Kind, bool ListInitialization) { 1299 if (DestType->isRecordType()) { 1300 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 1301 diag::err_bad_dynamic_cast_incomplete)) { 1302 msg = 0; 1303 return TC_Failed; 1304 } 1305 } 1306 1307 InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType); 1308 InitializationKind InitKind 1309 = (CCK == Sema::CCK_CStyleCast) 1310 ? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange, 1311 ListInitialization) 1312 : (CCK == Sema::CCK_FunctionalCast) 1313 ? InitializationKind::CreateFunctionalCast(OpRange, ListInitialization) 1314 : InitializationKind::CreateCast(OpRange); 1315 Expr *SrcExprRaw = SrcExpr.get(); 1316 InitializationSequence InitSeq(Self, Entity, InitKind, &SrcExprRaw, 1); 1317 1318 // At this point of CheckStaticCast, if the destination is a reference, 1319 // or the expression is an overload expression this has to work. 1320 // There is no other way that works. 1321 // On the other hand, if we're checking a C-style cast, we've still got 1322 // the reinterpret_cast way. 1323 bool CStyle 1324 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 1325 if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType())) 1326 return TC_NotApplicable; 1327 1328 ExprResult Result 1329 = InitSeq.Perform(Self, Entity, InitKind, MultiExprArg(Self, &SrcExprRaw, 1)); 1330 if (Result.isInvalid()) { 1331 msg = 0; 1332 return TC_Failed; 1333 } 1334 1335 if (InitSeq.isConstructorInitialization()) 1336 Kind = CK_ConstructorConversion; 1337 else 1338 Kind = CK_NoOp; 1339 1340 SrcExpr = move(Result); 1341 return TC_Success; 1342} 1343 1344/// TryConstCast - See if a const_cast from source to destination is allowed, 1345/// and perform it if it is. 1346static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType, 1347 bool CStyle, unsigned &msg) { 1348 DestType = Self.Context.getCanonicalType(DestType); 1349 QualType SrcType = SrcExpr->getType(); 1350 if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) { 1351 if (DestTypeTmp->isLValueReferenceType() && !SrcExpr->isLValue()) { 1352 // Cannot const_cast non-lvalue to lvalue reference type. But if this 1353 // is C-style, static_cast might find a way, so we simply suggest a 1354 // message and tell the parent to keep searching. 1355 msg = diag::err_bad_cxx_cast_rvalue; 1356 return TC_NotApplicable; 1357 } 1358 1359 // C++ 5.2.11p4: An lvalue of type T1 can be [cast] to an lvalue of type T2 1360 // [...] if a pointer to T1 can be [cast] to the type pointer to T2. 1361 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 1362 SrcType = Self.Context.getPointerType(SrcType); 1363 } 1364 1365 // C++ 5.2.11p5: For a const_cast involving pointers to data members [...] 1366 // the rules for const_cast are the same as those used for pointers. 1367 1368 if (!DestType->isPointerType() && 1369 !DestType->isMemberPointerType() && 1370 !DestType->isObjCObjectPointerType()) { 1371 // Cannot cast to non-pointer, non-reference type. Note that, if DestType 1372 // was a reference type, we converted it to a pointer above. 1373 // The status of rvalue references isn't entirely clear, but it looks like 1374 // conversion to them is simply invalid. 1375 // C++ 5.2.11p3: For two pointer types [...] 1376 if (!CStyle) 1377 msg = diag::err_bad_const_cast_dest; 1378 return TC_NotApplicable; 1379 } 1380 if (DestType->isFunctionPointerType() || 1381 DestType->isMemberFunctionPointerType()) { 1382 // Cannot cast direct function pointers. 1383 // C++ 5.2.11p2: [...] where T is any object type or the void type [...] 1384 // T is the ultimate pointee of source and target type. 1385 if (!CStyle) 1386 msg = diag::err_bad_const_cast_dest; 1387 return TC_NotApplicable; 1388 } 1389 SrcType = Self.Context.getCanonicalType(SrcType); 1390 1391 // Unwrap the pointers. Ignore qualifiers. Terminate early if the types are 1392 // completely equal. 1393 // C++ 5.2.11p3 describes the core semantics of const_cast. All cv specifiers 1394 // in multi-level pointers may change, but the level count must be the same, 1395 // as must be the final pointee type. 1396 while (SrcType != DestType && 1397 Self.Context.UnwrapSimilarPointerTypes(SrcType, DestType)) { 1398 Qualifiers SrcQuals, DestQuals; 1399 SrcType = Self.Context.getUnqualifiedArrayType(SrcType, SrcQuals); 1400 DestType = Self.Context.getUnqualifiedArrayType(DestType, DestQuals); 1401 1402 // const_cast is permitted to strip cvr-qualifiers, only. Make sure that 1403 // the other qualifiers (e.g., address spaces) are identical. 1404 SrcQuals.removeCVRQualifiers(); 1405 DestQuals.removeCVRQualifiers(); 1406 if (SrcQuals != DestQuals) 1407 return TC_NotApplicable; 1408 } 1409 1410 // Since we're dealing in canonical types, the remainder must be the same. 1411 if (SrcType != DestType) 1412 return TC_NotApplicable; 1413 1414 return TC_Success; 1415} 1416 1417// Checks for undefined behavior in reinterpret_cast. 1418// The cases that is checked for is: 1419// *reinterpret_cast<T*>(&a) 1420// reinterpret_cast<T&>(a) 1421// where accessing 'a' as type 'T' will result in undefined behavior. 1422void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType, 1423 bool IsDereference, 1424 SourceRange Range) { 1425 unsigned DiagID = IsDereference ? 1426 diag::warn_pointer_indirection_from_incompatible_type : 1427 diag::warn_undefined_reinterpret_cast; 1428 1429 if (Diags.getDiagnosticLevel(DiagID, Range.getBegin()) == 1430 DiagnosticsEngine::Ignored) { 1431 return; 1432 } 1433 1434 QualType SrcTy, DestTy; 1435 if (IsDereference) { 1436 if (!SrcType->getAs<PointerType>() || !DestType->getAs<PointerType>()) { 1437 return; 1438 } 1439 SrcTy = SrcType->getPointeeType(); 1440 DestTy = DestType->getPointeeType(); 1441 } else { 1442 if (!DestType->getAs<ReferenceType>()) { 1443 return; 1444 } 1445 SrcTy = SrcType; 1446 DestTy = DestType->getPointeeType(); 1447 } 1448 1449 // Cast is compatible if the types are the same. 1450 if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) { 1451 return; 1452 } 1453 // or one of the types is a char or void type 1454 if (DestTy->isAnyCharacterType() || DestTy->isVoidType() || 1455 SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) { 1456 return; 1457 } 1458 // or one of the types is a tag type. 1459 if (SrcTy->getAs<TagType>() || DestTy->getAs<TagType>()) { 1460 return; 1461 } 1462 1463 // FIXME: Scoped enums? 1464 if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) || 1465 (SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) { 1466 if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) { 1467 return; 1468 } 1469 } 1470 1471 Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range; 1472} 1473 1474static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr, 1475 QualType DestType, bool CStyle, 1476 const SourceRange &OpRange, 1477 unsigned &msg, 1478 CastKind &Kind) { 1479 bool IsLValueCast = false; 1480 1481 DestType = Self.Context.getCanonicalType(DestType); 1482 QualType SrcType = SrcExpr.get()->getType(); 1483 1484 // Is the source an overloaded name? (i.e. &foo) 1485 // If so, reinterpret_cast can not help us here (13.4, p1, bullet 5) ... 1486 if (SrcType == Self.Context.OverloadTy) { 1487 // ... unless foo<int> resolves to an lvalue unambiguously. 1488 // TODO: what if this fails because of DiagnoseUseOfDecl or something 1489 // like it? 1490 ExprResult SingleFunctionExpr = SrcExpr; 1491 if (Self.ResolveAndFixSingleFunctionTemplateSpecialization( 1492 SingleFunctionExpr, 1493 Expr::getValueKindForType(DestType) == VK_RValue // Convert Fun to Ptr 1494 ) && SingleFunctionExpr.isUsable()) { 1495 SrcExpr = move(SingleFunctionExpr); 1496 SrcType = SrcExpr.get()->getType(); 1497 } else { 1498 return TC_NotApplicable; 1499 } 1500 } 1501 1502 if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) { 1503 bool LValue = DestTypeTmp->isLValueReferenceType(); 1504 if (LValue && !SrcExpr.get()->isLValue()) { 1505 // Cannot cast non-lvalue to lvalue reference type. See the similar 1506 // comment in const_cast. 1507 msg = diag::err_bad_cxx_cast_rvalue; 1508 return TC_NotApplicable; 1509 } 1510 1511 if (!CStyle) { 1512 Self.CheckCompatibleReinterpretCast(SrcType, DestType, 1513 /*isDereference=*/false, OpRange); 1514 } 1515 1516 // C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the 1517 // same effect as the conversion *reinterpret_cast<T*>(&x) with the 1518 // built-in & and * operators. 1519 1520 const char *inappropriate = 0; 1521 switch (SrcExpr.get()->getObjectKind()) { 1522 case OK_Ordinary: 1523 break; 1524 case OK_BitField: inappropriate = "bit-field"; break; 1525 case OK_VectorComponent: inappropriate = "vector element"; break; 1526 case OK_ObjCProperty: inappropriate = "property expression"; break; 1527 } 1528 if (inappropriate) { 1529 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference) 1530 << inappropriate << DestType 1531 << OpRange << SrcExpr.get()->getSourceRange(); 1532 msg = 0; SrcExpr = ExprError(); 1533 return TC_NotApplicable; 1534 } 1535 1536 // This code does this transformation for the checked types. 1537 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 1538 SrcType = Self.Context.getPointerType(SrcType); 1539 1540 IsLValueCast = true; 1541 } 1542 1543 // Canonicalize source for comparison. 1544 SrcType = Self.Context.getCanonicalType(SrcType); 1545 1546 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(), 1547 *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 1548 if (DestMemPtr && SrcMemPtr) { 1549 // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1" 1550 // can be explicitly converted to an rvalue of type "pointer to member 1551 // of Y of type T2" if T1 and T2 are both function types or both object 1552 // types. 1553 if (DestMemPtr->getPointeeType()->isFunctionType() != 1554 SrcMemPtr->getPointeeType()->isFunctionType()) 1555 return TC_NotApplicable; 1556 1557 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away 1558 // constness. 1559 // A reinterpret_cast followed by a const_cast can, though, so in C-style, 1560 // we accept it. 1561 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, 1562 /*CheckObjCLifetime=*/CStyle)) { 1563 msg = diag::err_bad_cxx_cast_qualifiers_away; 1564 return TC_Failed; 1565 } 1566 1567 // Don't allow casting between member pointers of different sizes. 1568 if (Self.Context.getTypeSize(DestMemPtr) != 1569 Self.Context.getTypeSize(SrcMemPtr)) { 1570 msg = diag::err_bad_cxx_cast_member_pointer_size; 1571 return TC_Failed; 1572 } 1573 1574 // A valid member pointer cast. 1575 Kind = IsLValueCast? CK_LValueBitCast : CK_BitCast; 1576 return TC_Success; 1577 } 1578 1579 // See below for the enumeral issue. 1580 if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) { 1581 // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral 1582 // type large enough to hold it. A value of std::nullptr_t can be 1583 // converted to an integral type; the conversion has the same meaning 1584 // and validity as a conversion of (void*)0 to the integral type. 1585 if (Self.Context.getTypeSize(SrcType) > 1586 Self.Context.getTypeSize(DestType)) { 1587 msg = diag::err_bad_reinterpret_cast_small_int; 1588 return TC_Failed; 1589 } 1590 Kind = CK_PointerToIntegral; 1591 return TC_Success; 1592 } 1593 1594 bool destIsVector = DestType->isVectorType(); 1595 bool srcIsVector = SrcType->isVectorType(); 1596 if (srcIsVector || destIsVector) { 1597 // FIXME: Should this also apply to floating point types? 1598 bool srcIsScalar = SrcType->isIntegralType(Self.Context); 1599 bool destIsScalar = DestType->isIntegralType(Self.Context); 1600 1601 // Check if this is a cast between a vector and something else. 1602 if (!(srcIsScalar && destIsVector) && !(srcIsVector && destIsScalar) && 1603 !(srcIsVector && destIsVector)) 1604 return TC_NotApplicable; 1605 1606 // If both types have the same size, we can successfully cast. 1607 if (Self.Context.getTypeSize(SrcType) 1608 == Self.Context.getTypeSize(DestType)) { 1609 Kind = CK_BitCast; 1610 return TC_Success; 1611 } 1612 1613 if (destIsScalar) 1614 msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size; 1615 else if (srcIsScalar) 1616 msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size; 1617 else 1618 msg = diag::err_bad_cxx_cast_vector_to_vector_different_size; 1619 1620 return TC_Failed; 1621 } 1622 1623 if (SrcType == DestType) { 1624 // C++ 5.2.10p2 has a note that mentions that, subject to all other 1625 // restrictions, a cast to the same type is allowed so long as it does not 1626 // cast away constness. In C++98, the intent was not entirely clear here, 1627 // since all other paragraphs explicitly forbid casts to the same type. 1628 // C++11 clarifies this case with p2. 1629 // 1630 // The only allowed types are: integral, enumeration, pointer, or 1631 // pointer-to-member types. We also won't restrict Obj-C pointers either. 1632 Kind = CK_NoOp; 1633 TryCastResult Result = TC_NotApplicable; 1634 if (SrcType->isIntegralOrEnumerationType() || 1635 SrcType->isAnyPointerType() || 1636 SrcType->isMemberPointerType() || 1637 SrcType->isBlockPointerType()) { 1638 Result = TC_Success; 1639 } 1640 return Result; 1641 } 1642 1643 bool destIsPtr = DestType->isAnyPointerType() || 1644 DestType->isBlockPointerType(); 1645 bool srcIsPtr = SrcType->isAnyPointerType() || 1646 SrcType->isBlockPointerType(); 1647 if (!destIsPtr && !srcIsPtr) { 1648 // Except for std::nullptr_t->integer and lvalue->reference, which are 1649 // handled above, at least one of the two arguments must be a pointer. 1650 return TC_NotApplicable; 1651 } 1652 1653 if (DestType->isIntegralType(Self.Context)) { 1654 assert(srcIsPtr && "One type must be a pointer"); 1655 // C++ 5.2.10p4: A pointer can be explicitly converted to any integral 1656 // type large enough to hold it; except in Microsoft mode, where the 1657 // integral type size doesn't matter. 1658 if ((Self.Context.getTypeSize(SrcType) > 1659 Self.Context.getTypeSize(DestType)) && 1660 !Self.getLangOptions().MicrosoftExt) { 1661 msg = diag::err_bad_reinterpret_cast_small_int; 1662 return TC_Failed; 1663 } 1664 Kind = CK_PointerToIntegral; 1665 return TC_Success; 1666 } 1667 1668 if (SrcType->isIntegralOrEnumerationType()) { 1669 assert(destIsPtr && "One type must be a pointer"); 1670 // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly 1671 // converted to a pointer. 1672 // C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not 1673 // necessarily converted to a null pointer value.] 1674 Kind = CK_IntegralToPointer; 1675 return TC_Success; 1676 } 1677 1678 if (!destIsPtr || !srcIsPtr) { 1679 // With the valid non-pointer conversions out of the way, we can be even 1680 // more stringent. 1681 return TC_NotApplicable; 1682 } 1683 1684 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness. 1685 // The C-style cast operator can. 1686 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, 1687 /*CheckObjCLifetime=*/CStyle)) { 1688 msg = diag::err_bad_cxx_cast_qualifiers_away; 1689 return TC_Failed; 1690 } 1691 1692 // Cannot convert between block pointers and Objective-C object pointers. 1693 if ((SrcType->isBlockPointerType() && DestType->isObjCObjectPointerType()) || 1694 (DestType->isBlockPointerType() && SrcType->isObjCObjectPointerType())) 1695 return TC_NotApplicable; 1696 1697 if (IsLValueCast) { 1698 Kind = CK_LValueBitCast; 1699 } else if (DestType->isObjCObjectPointerType()) { 1700 Kind = Self.PrepareCastToObjCObjectPointer(SrcExpr); 1701 } else if (DestType->isBlockPointerType()) { 1702 if (!SrcType->isBlockPointerType()) { 1703 Kind = CK_AnyPointerToBlockPointerCast; 1704 } else { 1705 Kind = CK_BitCast; 1706 } 1707 } else { 1708 Kind = CK_BitCast; 1709 } 1710 1711 // Any pointer can be cast to an Objective-C pointer type with a C-style 1712 // cast. 1713 if (CStyle && DestType->isObjCObjectPointerType()) { 1714 return TC_Success; 1715 } 1716 1717 // Not casting away constness, so the only remaining check is for compatible 1718 // pointer categories. 1719 1720 if (SrcType->isFunctionPointerType()) { 1721 if (DestType->isFunctionPointerType()) { 1722 // C++ 5.2.10p6: A pointer to a function can be explicitly converted to 1723 // a pointer to a function of a different type. 1724 return TC_Success; 1725 } 1726 1727 // C++0x 5.2.10p8: Converting a pointer to a function into a pointer to 1728 // an object type or vice versa is conditionally-supported. 1729 // Compilers support it in C++03 too, though, because it's necessary for 1730 // casting the return value of dlsym() and GetProcAddress(). 1731 // FIXME: Conditionally-supported behavior should be configurable in the 1732 // TargetInfo or similar. 1733 Self.Diag(OpRange.getBegin(), 1734 Self.getLangOptions().CPlusPlus0x ? 1735 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj) 1736 << OpRange; 1737 return TC_Success; 1738 } 1739 1740 if (DestType->isFunctionPointerType()) { 1741 // See above. 1742 Self.Diag(OpRange.getBegin(), 1743 Self.getLangOptions().CPlusPlus0x ? 1744 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj) 1745 << OpRange; 1746 return TC_Success; 1747 } 1748 1749 // C++ 5.2.10p7: A pointer to an object can be explicitly converted to 1750 // a pointer to an object of different type. 1751 // Void pointers are not specified, but supported by every compiler out there. 1752 // So we finish by allowing everything that remains - it's got to be two 1753 // object pointers. 1754 return TC_Success; 1755} 1756 1757void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle, 1758 bool ListInitialization) { 1759 // Handle placeholders. 1760 if (isPlaceholder()) { 1761 // C-style casts can resolve __unknown_any types. 1762 if (claimPlaceholder(BuiltinType::UnknownAny)) { 1763 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 1764 SrcExpr.get(), Kind, 1765 ValueKind, BasePath); 1766 return; 1767 } 1768 1769 checkNonOverloadPlaceholders(); 1770 if (SrcExpr.isInvalid()) 1771 return; 1772 } 1773 1774 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 1775 // This test is outside everything else because it's the only case where 1776 // a non-lvalue-reference target type does not lead to decay. 1777 if (DestType->isVoidType()) { 1778 Kind = CK_ToVoid; 1779 1780 if (claimPlaceholder(BuiltinType::Overload)) { 1781 Self.ResolveAndFixSingleFunctionTemplateSpecialization( 1782 SrcExpr, /* Decay Function to ptr */ false, 1783 /* Complain */ true, DestRange, DestType, 1784 diag::err_bad_cstyle_cast_overload); 1785 if (SrcExpr.isInvalid()) 1786 return; 1787 } 1788 1789 SrcExpr = Self.IgnoredValueConversions(SrcExpr.take()); 1790 if (SrcExpr.isInvalid()) 1791 return; 1792 1793 return; 1794 } 1795 1796 // If the type is dependent, we won't do any other semantic analysis now. 1797 if (DestType->isDependentType() || SrcExpr.get()->isTypeDependent()) { 1798 assert(Kind == CK_Dependent); 1799 return; 1800 } 1801 1802 if (ValueKind == VK_RValue && !DestType->isRecordType() && 1803 !isPlaceholder(BuiltinType::Overload)) { 1804 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 1805 if (SrcExpr.isInvalid()) 1806 return; 1807 } 1808 1809 // AltiVec vector initialization with a single literal. 1810 if (const VectorType *vecTy = DestType->getAs<VectorType>()) 1811 if (vecTy->getVectorKind() == VectorType::AltiVecVector 1812 && (SrcExpr.get()->getType()->isIntegerType() 1813 || SrcExpr.get()->getType()->isFloatingType())) { 1814 Kind = CK_VectorSplat; 1815 return; 1816 } 1817 1818 // C++ [expr.cast]p5: The conversions performed by 1819 // - a const_cast, 1820 // - a static_cast, 1821 // - a static_cast followed by a const_cast, 1822 // - a reinterpret_cast, or 1823 // - a reinterpret_cast followed by a const_cast, 1824 // can be performed using the cast notation of explicit type conversion. 1825 // [...] If a conversion can be interpreted in more than one of the ways 1826 // listed above, the interpretation that appears first in the list is used, 1827 // even if a cast resulting from that interpretation is ill-formed. 1828 // In plain language, this means trying a const_cast ... 1829 unsigned msg = diag::err_bad_cxx_cast_generic; 1830 TryCastResult tcr = TryConstCast(Self, SrcExpr.get(), DestType, 1831 /*CStyle*/true, msg); 1832 if (tcr == TC_Success) 1833 Kind = CK_NoOp; 1834 1835 Sema::CheckedConversionKind CCK 1836 = FunctionalStyle? Sema::CCK_FunctionalCast 1837 : Sema::CCK_CStyleCast; 1838 if (tcr == TC_NotApplicable) { 1839 // ... or if that is not possible, a static_cast, ignoring const, ... 1840 tcr = TryStaticCast(Self, SrcExpr, DestType, CCK, OpRange, 1841 msg, Kind, BasePath, ListInitialization); 1842 if (SrcExpr.isInvalid()) 1843 return; 1844 1845 if (tcr == TC_NotApplicable) { 1846 // ... and finally a reinterpret_cast, ignoring const. 1847 tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/true, 1848 OpRange, msg, Kind); 1849 if (SrcExpr.isInvalid()) 1850 return; 1851 } 1852 } 1853 1854 if (Self.getLangOptions().ObjCAutoRefCount && tcr == TC_Success) 1855 checkObjCARCConversion(CCK); 1856 1857 if (tcr != TC_Success && msg != 0) { 1858 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 1859 DeclAccessPair Found; 1860 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 1861 DestType, 1862 /*Complain*/ true, 1863 Found); 1864 1865 assert(!Fn && "cast failed but able to resolve overload expression!!"); 1866 (void)Fn; 1867 1868 } else { 1869 diagnoseBadCast(Self, msg, (FunctionalStyle ? CT_Functional : CT_CStyle), 1870 OpRange, SrcExpr.get(), DestType); 1871 } 1872 } else if (Kind == CK_BitCast) { 1873 checkCastAlign(); 1874 } 1875 1876 // Clear out SrcExpr if there was a fatal error. 1877 if (tcr != TC_Success) 1878 SrcExpr = ExprError(); 1879} 1880 1881/// Check the semantics of a C-style cast operation, in C. 1882void CastOperation::CheckCStyleCast() { 1883 assert(!Self.getLangOptions().CPlusPlus); 1884 1885 // C-style casts can resolve __unknown_any types. 1886 if (claimPlaceholder(BuiltinType::UnknownAny)) { 1887 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 1888 SrcExpr.get(), Kind, 1889 ValueKind, BasePath); 1890 return; 1891 } 1892 1893 // C99 6.5.4p2: the cast type needs to be void or scalar and the expression 1894 // type needs to be scalar. 1895 if (DestType->isVoidType()) { 1896 // We don't necessarily do lvalue-to-rvalue conversions on this. 1897 SrcExpr = Self.IgnoredValueConversions(SrcExpr.take()); 1898 if (SrcExpr.isInvalid()) 1899 return; 1900 1901 // Cast to void allows any expr type. 1902 Kind = CK_ToVoid; 1903 return; 1904 } 1905 1906 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 1907 if (SrcExpr.isInvalid()) 1908 return; 1909 QualType SrcType = SrcExpr.get()->getType(); 1910 1911 // You can cast an _Atomic(T) to anything you can cast a T to. 1912 if (const AtomicType *AtomicSrcType = SrcType->getAs<AtomicType>()) 1913 SrcType = AtomicSrcType->getValueType(); 1914 1915 assert(!SrcType->isPlaceholderType()); 1916 1917 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 1918 diag::err_typecheck_cast_to_incomplete)) { 1919 SrcExpr = ExprError(); 1920 return; 1921 } 1922 1923 if (!DestType->isScalarType() && !DestType->isVectorType()) { 1924 const RecordType *DestRecordTy = DestType->getAs<RecordType>(); 1925 1926 if (DestRecordTy && Self.Context.hasSameUnqualifiedType(DestType, SrcType)){ 1927 // GCC struct/union extension: allow cast to self. 1928 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_nonscalar) 1929 << DestType << SrcExpr.get()->getSourceRange(); 1930 Kind = CK_NoOp; 1931 return; 1932 } 1933 1934 // GCC's cast to union extension. 1935 if (DestRecordTy && DestRecordTy->getDecl()->isUnion()) { 1936 RecordDecl *RD = DestRecordTy->getDecl(); 1937 RecordDecl::field_iterator Field, FieldEnd; 1938 for (Field = RD->field_begin(), FieldEnd = RD->field_end(); 1939 Field != FieldEnd; ++Field) { 1940 if (Self.Context.hasSameUnqualifiedType(Field->getType(), SrcType) && 1941 !Field->isUnnamedBitfield()) { 1942 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union) 1943 << SrcExpr.get()->getSourceRange(); 1944 break; 1945 } 1946 } 1947 if (Field == FieldEnd) { 1948 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cast_to_union_no_type) 1949 << SrcType << SrcExpr.get()->getSourceRange(); 1950 SrcExpr = ExprError(); 1951 return; 1952 } 1953 Kind = CK_ToUnion; 1954 return; 1955 } 1956 1957 // Reject any other conversions to non-scalar types. 1958 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cond_expect_scalar) 1959 << DestType << SrcExpr.get()->getSourceRange(); 1960 SrcExpr = ExprError(); 1961 return; 1962 } 1963 1964 // The type we're casting to is known to be a scalar or vector. 1965 1966 // Require the operand to be a scalar or vector. 1967 if (!SrcType->isScalarType() && !SrcType->isVectorType()) { 1968 Self.Diag(SrcExpr.get()->getExprLoc(), 1969 diag::err_typecheck_expect_scalar_operand) 1970 << SrcType << SrcExpr.get()->getSourceRange(); 1971 SrcExpr = ExprError(); 1972 return; 1973 } 1974 1975 if (DestType->isExtVectorType()) { 1976 SrcExpr = Self.CheckExtVectorCast(OpRange, DestType, SrcExpr.take(), Kind); 1977 return; 1978 } 1979 1980 if (const VectorType *DestVecTy = DestType->getAs<VectorType>()) { 1981 if (DestVecTy->getVectorKind() == VectorType::AltiVecVector && 1982 (SrcType->isIntegerType() || SrcType->isFloatingType())) { 1983 Kind = CK_VectorSplat; 1984 } else if (Self.CheckVectorCast(OpRange, DestType, SrcType, Kind)) { 1985 SrcExpr = ExprError(); 1986 } 1987 return; 1988 } 1989 1990 if (SrcType->isVectorType()) { 1991 if (Self.CheckVectorCast(OpRange, SrcType, DestType, Kind)) 1992 SrcExpr = ExprError(); 1993 return; 1994 } 1995 1996 // The source and target types are both scalars, i.e. 1997 // - arithmetic types (fundamental, enum, and complex) 1998 // - all kinds of pointers 1999 // Note that member pointers were filtered out with C++, above. 2000 2001 if (isa<ObjCSelectorExpr>(SrcExpr.get())) { 2002 Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_selector_expr); 2003 SrcExpr = ExprError(); 2004 return; 2005 } 2006 2007 // If either type is a pointer, the other type has to be either an 2008 // integer or a pointer. 2009 if (!DestType->isArithmeticType()) { 2010 if (!SrcType->isIntegralType(Self.Context) && SrcType->isArithmeticType()) { 2011 Self.Diag(SrcExpr.get()->getExprLoc(), 2012 diag::err_cast_pointer_from_non_pointer_int) 2013 << SrcType << SrcExpr.get()->getSourceRange(); 2014 SrcExpr = ExprError(); 2015 return; 2016 } 2017 } else if (!SrcType->isArithmeticType()) { 2018 if (!DestType->isIntegralType(Self.Context) && 2019 DestType->isArithmeticType()) { 2020 Self.Diag(SrcExpr.get()->getLocStart(), 2021 diag::err_cast_pointer_to_non_pointer_int) 2022 << DestType << SrcExpr.get()->getSourceRange(); 2023 SrcExpr = ExprError(); 2024 return; 2025 } 2026 } 2027 2028 // ARC imposes extra restrictions on casts. 2029 if (Self.getLangOptions().ObjCAutoRefCount) { 2030 checkObjCARCConversion(Sema::CCK_CStyleCast); 2031 if (SrcExpr.isInvalid()) 2032 return; 2033 2034 if (const PointerType *CastPtr = DestType->getAs<PointerType>()) { 2035 if (const PointerType *ExprPtr = SrcType->getAs<PointerType>()) { 2036 Qualifiers CastQuals = CastPtr->getPointeeType().getQualifiers(); 2037 Qualifiers ExprQuals = ExprPtr->getPointeeType().getQualifiers(); 2038 if (CastPtr->getPointeeType()->isObjCLifetimeType() && 2039 ExprPtr->getPointeeType()->isObjCLifetimeType() && 2040 !CastQuals.compatiblyIncludesObjCLifetime(ExprQuals)) { 2041 Self.Diag(SrcExpr.get()->getLocStart(), 2042 diag::err_typecheck_incompatible_ownership) 2043 << SrcType << DestType << Sema::AA_Casting 2044 << SrcExpr.get()->getSourceRange(); 2045 return; 2046 } 2047 } 2048 } 2049 else if (!Self.CheckObjCARCUnavailableWeakConversion(DestType, SrcType)) { 2050 Self.Diag(SrcExpr.get()->getLocStart(), 2051 diag::err_arc_convesion_of_weak_unavailable) 2052 << 1 << SrcType << DestType << SrcExpr.get()->getSourceRange(); 2053 SrcExpr = ExprError(); 2054 return; 2055 } 2056 } 2057 2058 Kind = Self.PrepareScalarCast(SrcExpr, DestType); 2059 if (SrcExpr.isInvalid()) 2060 return; 2061 2062 if (Kind == CK_BitCast) 2063 checkCastAlign(); 2064} 2065 2066ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc, 2067 TypeSourceInfo *CastTypeInfo, 2068 SourceLocation RPLoc, 2069 Expr *CastExpr) { 2070 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr); 2071 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2072 Op.OpRange = SourceRange(LPLoc, CastExpr->getLocEnd()); 2073 2074 if (getLangOptions().CPlusPlus) { 2075 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/ false, 2076 isa<InitListExpr>(CastExpr)); 2077 } else { 2078 Op.CheckCStyleCast(); 2079 } 2080 2081 if (Op.SrcExpr.isInvalid()) 2082 return ExprError(); 2083 2084 return Op.complete(CStyleCastExpr::Create(Context, Op.ResultType, 2085 Op.ValueKind, Op.Kind, Op.SrcExpr.take(), 2086 &Op.BasePath, CastTypeInfo, LPLoc, RPLoc)); 2087} 2088 2089ExprResult Sema::BuildCXXFunctionalCastExpr(TypeSourceInfo *CastTypeInfo, 2090 SourceLocation LPLoc, 2091 Expr *CastExpr, 2092 SourceLocation RPLoc) { 2093 bool ListInitialization = LPLoc.isInvalid(); 2094 assert((!ListInitialization || isa<InitListExpr>(CastExpr)) && 2095 "List initialization must have initializer list as expression."); 2096 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr); 2097 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2098 Op.OpRange = SourceRange(Op.DestRange.getBegin(), CastExpr->getLocEnd()); 2099 2100 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/ true, ListInitialization); 2101 if (Op.SrcExpr.isInvalid()) 2102 return ExprError(); 2103 2104 return Op.complete(CXXFunctionalCastExpr::Create(Context, Op.ResultType, 2105 Op.ValueKind, CastTypeInfo, Op.DestRange.getBegin(), 2106 Op.Kind, Op.SrcExpr.take(), &Op.BasePath, RPLoc)); 2107} 2108