SemaCast.cpp revision 56f5d36fd13c5e271ebd05192c25c88d28e77f8d
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(bool &CastNodesCreated); 79 void CheckDynamicCast(); 80 void CheckCXXCStyleCast(bool FunctionalCast, bool &CastNodesCreated); 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, 194 CastKind &Kind); 195static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, 196 QualType DestType, 197 Sema::CheckedConversionKind CCK, 198 const SourceRange &OpRange, 199 unsigned &msg, 200 CastKind &Kind, 201 CXXCastPath &BasePath); 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 bool CastNodesCreated = false; 287 if (!TypeDependent) { 288 Op.CheckStaticCast(CastNodesCreated); 289 if (Op.SrcExpr.isInvalid()) 290 return ExprError(); 291 } 292 293 // CheckStaticCast _may_ have already created the cast node. Let's check 294 if (CastNodesCreated) { 295 if (CXXStaticCastExpr *Cast = 296 dyn_cast<CXXStaticCastExpr>(Op.SrcExpr.get())) { 297 assert(!Cast->getTypeInfoAsWritten() && 298 "The explicit cast node created by CheckStaticCast " 299 "has source type infos!"); 300 301 Cast->setTypeInfoAsWritten(DestTInfo); 302 Cast->setOperatorLoc(OpLoc); 303 Cast->setRParenLoc(Parens.getEnd()); 304 305 return Op.complete(Cast); 306 } 307 } 308 return Op.complete(CXXStaticCastExpr::Create(Context, Op.ResultType, 309 Op.ValueKind, Op.Kind, Op.SrcExpr.take(), 310 &Op.BasePath, DestTInfo, 311 OpLoc, Parens.getEnd())); 312 } 313 } 314 315 return ExprError(); 316} 317 318/// Try to diagnose a failed overloaded cast. Returns true if 319/// diagnostics were emitted. 320static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT, 321 SourceRange range, Expr *src, 322 QualType destType) { 323 switch (CT) { 324 // These cast kinds don't consider user-defined conversions. 325 case CT_Const: 326 case CT_Reinterpret: 327 case CT_Dynamic: 328 return false; 329 330 // These do. 331 case CT_Static: 332 case CT_CStyle: 333 case CT_Functional: 334 break; 335 } 336 337 QualType srcType = src->getType(); 338 if (!destType->isRecordType() && !srcType->isRecordType()) 339 return false; 340 341 InitializedEntity entity = InitializedEntity::InitializeTemporary(destType); 342 InitializationKind initKind 343 = (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(), 344 range) 345 : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range) 346 : InitializationKind::CreateStaticCast(/*type range?*/ range); 347 InitializationSequence sequence(S, entity, initKind, &src, 1); 348 349 assert(sequence.Failed() && "initialization succeeded on second try?"); 350 switch (sequence.getFailureKind()) { 351 default: return false; 352 353 case InitializationSequence::FK_ConstructorOverloadFailed: 354 case InitializationSequence::FK_UserConversionOverloadFailed: 355 break; 356 } 357 358 OverloadCandidateSet &candidates = sequence.getFailedCandidateSet(); 359 360 unsigned msg = 0; 361 OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates; 362 363 switch (sequence.getFailedOverloadResult()) { 364 case OR_Success: llvm_unreachable("successful failed overload"); 365 return false; 366 case OR_No_Viable_Function: 367 if (candidates.empty()) 368 msg = diag::err_ovl_no_conversion_in_cast; 369 else 370 msg = diag::err_ovl_no_viable_conversion_in_cast; 371 howManyCandidates = OCD_AllCandidates; 372 break; 373 374 case OR_Ambiguous: 375 msg = diag::err_ovl_ambiguous_conversion_in_cast; 376 howManyCandidates = OCD_ViableCandidates; 377 break; 378 379 case OR_Deleted: 380 msg = diag::err_ovl_deleted_conversion_in_cast; 381 howManyCandidates = OCD_ViableCandidates; 382 break; 383 } 384 385 S.Diag(range.getBegin(), msg) 386 << CT << srcType << destType 387 << range << src->getSourceRange(); 388 389 candidates.NoteCandidates(S, howManyCandidates, &src, 1); 390 391 return true; 392} 393 394/// Diagnose a failed cast. 395static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType, 396 SourceRange opRange, Expr *src, QualType destType) { 397 if (src->getType() == S.Context.BoundMemberTy) { 398 (void) S.CheckPlaceholderExpr(src); // will always fail 399 return; 400 } 401 402 if (msg == diag::err_bad_cxx_cast_generic && 403 tryDiagnoseOverloadedCast(S, castType, opRange, src, destType)) 404 return; 405 406 S.Diag(opRange.getBegin(), msg) << castType 407 << src->getType() << destType << opRange << src->getSourceRange(); 408} 409 410/// UnwrapDissimilarPointerTypes - Like Sema::UnwrapSimilarPointerTypes, 411/// this removes one level of indirection from both types, provided that they're 412/// the same kind of pointer (plain or to-member). Unlike the Sema function, 413/// this one doesn't care if the two pointers-to-member don't point into the 414/// same class. This is because CastsAwayConstness doesn't care. 415static bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) { 416 const PointerType *T1PtrType = T1->getAs<PointerType>(), 417 *T2PtrType = T2->getAs<PointerType>(); 418 if (T1PtrType && T2PtrType) { 419 T1 = T1PtrType->getPointeeType(); 420 T2 = T2PtrType->getPointeeType(); 421 return true; 422 } 423 const ObjCObjectPointerType *T1ObjCPtrType = 424 T1->getAs<ObjCObjectPointerType>(), 425 *T2ObjCPtrType = 426 T2->getAs<ObjCObjectPointerType>(); 427 if (T1ObjCPtrType) { 428 if (T2ObjCPtrType) { 429 T1 = T1ObjCPtrType->getPointeeType(); 430 T2 = T2ObjCPtrType->getPointeeType(); 431 return true; 432 } 433 else if (T2PtrType) { 434 T1 = T1ObjCPtrType->getPointeeType(); 435 T2 = T2PtrType->getPointeeType(); 436 return true; 437 } 438 } 439 else if (T2ObjCPtrType) { 440 if (T1PtrType) { 441 T2 = T2ObjCPtrType->getPointeeType(); 442 T1 = T1PtrType->getPointeeType(); 443 return true; 444 } 445 } 446 447 const MemberPointerType *T1MPType = T1->getAs<MemberPointerType>(), 448 *T2MPType = T2->getAs<MemberPointerType>(); 449 if (T1MPType && T2MPType) { 450 T1 = T1MPType->getPointeeType(); 451 T2 = T2MPType->getPointeeType(); 452 return true; 453 } 454 455 const BlockPointerType *T1BPType = T1->getAs<BlockPointerType>(), 456 *T2BPType = T2->getAs<BlockPointerType>(); 457 if (T1BPType && T2BPType) { 458 T1 = T1BPType->getPointeeType(); 459 T2 = T2BPType->getPointeeType(); 460 return true; 461 } 462 463 return false; 464} 465 466/// CastsAwayConstness - Check if the pointer conversion from SrcType to 467/// DestType casts away constness as defined in C++ 5.2.11p8ff. This is used by 468/// the cast checkers. Both arguments must denote pointer (possibly to member) 469/// types. 470/// 471/// \param CheckCVR Whether to check for const/volatile/restrict qualifiers. 472/// 473/// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers. 474static bool 475CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, 476 bool CheckCVR, bool CheckObjCLifetime) { 477 // If the only checking we care about is for Objective-C lifetime qualifiers, 478 // and we're not in ARC mode, there's nothing to check. 479 if (!CheckCVR && CheckObjCLifetime && 480 !Self.Context.getLangOptions().ObjCAutoRefCount) 481 return false; 482 483 // Casting away constness is defined in C++ 5.2.11p8 with reference to 484 // C++ 4.4. We piggyback on Sema::IsQualificationConversion for this, since 485 // the rules are non-trivial. So first we construct Tcv *...cv* as described 486 // in C++ 5.2.11p8. 487 assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() || 488 SrcType->isBlockPointerType()) && 489 "Source type is not pointer or pointer to member."); 490 assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() || 491 DestType->isBlockPointerType()) && 492 "Destination type is not pointer or pointer to member."); 493 494 QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType), 495 UnwrappedDestType = Self.Context.getCanonicalType(DestType); 496 SmallVector<Qualifiers, 8> cv1, cv2; 497 498 // Find the qualifiers. We only care about cvr-qualifiers for the 499 // purpose of this check, because other qualifiers (address spaces, 500 // Objective-C GC, etc.) are part of the type's identity. 501 while (UnwrapDissimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) { 502 // Determine the relevant qualifiers at this level. 503 Qualifiers SrcQuals, DestQuals; 504 Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals); 505 Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals); 506 507 Qualifiers RetainedSrcQuals, RetainedDestQuals; 508 if (CheckCVR) { 509 RetainedSrcQuals.setCVRQualifiers(SrcQuals.getCVRQualifiers()); 510 RetainedDestQuals.setCVRQualifiers(DestQuals.getCVRQualifiers()); 511 } 512 513 if (CheckObjCLifetime && 514 !DestQuals.compatiblyIncludesObjCLifetime(SrcQuals)) 515 return true; 516 517 cv1.push_back(RetainedSrcQuals); 518 cv2.push_back(RetainedDestQuals); 519 } 520 if (cv1.empty()) 521 return false; 522 523 // Construct void pointers with those qualifiers (in reverse order of 524 // unwrapping, of course). 525 QualType SrcConstruct = Self.Context.VoidTy; 526 QualType DestConstruct = Self.Context.VoidTy; 527 ASTContext &Context = Self.Context; 528 for (SmallVector<Qualifiers, 8>::reverse_iterator i1 = cv1.rbegin(), 529 i2 = cv2.rbegin(); 530 i1 != cv1.rend(); ++i1, ++i2) { 531 SrcConstruct 532 = Context.getPointerType(Context.getQualifiedType(SrcConstruct, *i1)); 533 DestConstruct 534 = Context.getPointerType(Context.getQualifiedType(DestConstruct, *i2)); 535 } 536 537 // Test if they're compatible. 538 bool ObjCLifetimeConversion; 539 return SrcConstruct != DestConstruct && 540 !Self.IsQualificationConversion(SrcConstruct, DestConstruct, false, 541 ObjCLifetimeConversion); 542} 543 544/// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid. 545/// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime- 546/// checked downcasts in class hierarchies. 547void CastOperation::CheckDynamicCast() { 548 if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload)) { 549 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 550 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 551 return; 552 } 553 554 QualType OrigSrcType = SrcExpr.get()->getType(); 555 QualType DestType = Self.Context.getCanonicalType(this->DestType); 556 557 // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type, 558 // or "pointer to cv void". 559 560 QualType DestPointee; 561 const PointerType *DestPointer = DestType->getAs<PointerType>(); 562 const ReferenceType *DestReference = 0; 563 if (DestPointer) { 564 DestPointee = DestPointer->getPointeeType(); 565 } else if ((DestReference = DestType->getAs<ReferenceType>())) { 566 DestPointee = DestReference->getPointeeType(); 567 } else { 568 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr) 569 << this->DestType << DestRange; 570 return; 571 } 572 573 const RecordType *DestRecord = DestPointee->getAs<RecordType>(); 574 if (DestPointee->isVoidType()) { 575 assert(DestPointer && "Reference to void is not possible"); 576 } else if (DestRecord) { 577 if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee, 578 Self.PDiag(diag::err_bad_dynamic_cast_incomplete) 579 << DestRange)) 580 return; 581 } else { 582 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 583 << DestPointee.getUnqualifiedType() << DestRange; 584 return; 585 } 586 587 // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to 588 // complete class type, [...]. If T is an lvalue reference type, v shall be 589 // an lvalue of a complete class type, [...]. If T is an rvalue reference 590 // type, v shall be an expression having a complete class type, [...] 591 QualType SrcType = Self.Context.getCanonicalType(OrigSrcType); 592 QualType SrcPointee; 593 if (DestPointer) { 594 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 595 SrcPointee = SrcPointer->getPointeeType(); 596 } else { 597 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr) 598 << OrigSrcType << SrcExpr.get()->getSourceRange(); 599 return; 600 } 601 } else if (DestReference->isLValueReferenceType()) { 602 if (!SrcExpr.get()->isLValue()) { 603 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue) 604 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 605 } 606 SrcPointee = SrcType; 607 } else { 608 SrcPointee = SrcType; 609 } 610 611 const RecordType *SrcRecord = SrcPointee->getAs<RecordType>(); 612 if (SrcRecord) { 613 if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee, 614 Self.PDiag(diag::err_bad_dynamic_cast_incomplete) 615 << SrcExpr.get()->getSourceRange())) 616 return; 617 } else { 618 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 619 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 620 return; 621 } 622 623 assert((DestPointer || DestReference) && 624 "Bad destination non-ptr/ref slipped through."); 625 assert((DestRecord || DestPointee->isVoidType()) && 626 "Bad destination pointee slipped through."); 627 assert(SrcRecord && "Bad source pointee slipped through."); 628 629 // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness. 630 if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) { 631 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away) 632 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 633 return; 634 } 635 636 // C++ 5.2.7p3: If the type of v is the same as the required result type, 637 // [except for cv]. 638 if (DestRecord == SrcRecord) { 639 Kind = CK_NoOp; 640 return; 641 } 642 643 // C++ 5.2.7p5 644 // Upcasts are resolved statically. 645 if (DestRecord && Self.IsDerivedFrom(SrcPointee, DestPointee)) { 646 if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee, 647 OpRange.getBegin(), OpRange, 648 &BasePath)) 649 return; 650 651 Kind = CK_DerivedToBase; 652 653 // If we are casting to or through a virtual base class, we need a 654 // vtable. 655 if (Self.BasePathInvolvesVirtualBase(BasePath)) 656 Self.MarkVTableUsed(OpRange.getBegin(), 657 cast<CXXRecordDecl>(SrcRecord->getDecl())); 658 return; 659 } 660 661 // C++ 5.2.7p6: Otherwise, v shall be [polymorphic]. 662 const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition(); 663 assert(SrcDecl && "Definition missing"); 664 if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) { 665 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic) 666 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 667 } 668 Self.MarkVTableUsed(OpRange.getBegin(), 669 cast<CXXRecordDecl>(SrcRecord->getDecl())); 670 671 // Done. Everything else is run-time checks. 672 Kind = CK_Dynamic; 673} 674 675/// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid. 676/// Refer to C++ 5.2.11 for details. const_cast is typically used in code 677/// like this: 678/// const char *str = "literal"; 679/// legacy_function(const_cast\<char*\>(str)); 680void CastOperation::CheckConstCast() { 681 if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload)) { 682 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 683 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 684 return; 685 } 686 687 unsigned msg = diag::err_bad_cxx_cast_generic; 688 if (TryConstCast(Self, SrcExpr.get(), DestType, /*CStyle*/false, msg) != TC_Success 689 && msg != 0) 690 Self.Diag(OpRange.getBegin(), msg) << CT_Const 691 << SrcExpr.get()->getType() << DestType << OpRange; 692} 693 694/// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is 695/// valid. 696/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code 697/// like this: 698/// char *bytes = reinterpret_cast\<char*\>(int_ptr); 699void CastOperation::CheckReinterpretCast() { 700 if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload)) { 701 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 702 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 703 return; 704 } 705 706 unsigned msg = diag::err_bad_cxx_cast_generic; 707 TryCastResult tcr = 708 TryReinterpretCast(Self, SrcExpr, DestType, 709 /*CStyle*/false, OpRange, msg, Kind); 710 if (tcr != TC_Success && msg != 0) 711 { 712 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 713 return; 714 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 715 //FIXME: &f<int>; is overloaded and resolvable 716 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload) 717 << OverloadExpr::find(SrcExpr.get()).Expression->getName() 718 << DestType << OpRange; 719 Self.NoteAllOverloadCandidates(SrcExpr.get()); 720 721 } else { 722 diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(), DestType); 723 } 724 } else if (tcr == TC_Success && Self.getLangOptions().ObjCAutoRefCount) { 725 checkObjCARCConversion(Sema::CCK_OtherCast); 726 } 727} 728 729 730/// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid. 731/// Refer to C++ 5.2.9 for details. Static casts are mostly used for making 732/// implicit conversions explicit and getting rid of data loss warnings. 733void CastOperation::CheckStaticCast(bool &CastNodesCreated) { 734 if (isPlaceholder()) { 735 checkNonOverloadPlaceholders(); 736 if (SrcExpr.isInvalid()) 737 return; 738 } 739 740 // This test is outside everything else because it's the only case where 741 // a non-lvalue-reference target type does not lead to decay. 742 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 743 if (DestType->isVoidType()) { 744 Kind = CK_ToVoid; 745 746 if (claimPlaceholder(BuiltinType::Overload)) { 747 Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr, 748 false, // Decay Function to ptr 749 true, // Complain 750 OpRange, DestType, diag::err_bad_static_cast_overload); 751 if (SrcExpr.isInvalid()) 752 return; 753 } 754 755 SrcExpr = Self.IgnoredValueConversions(SrcExpr.take()); 756 return; 757 } 758 759 if (ValueKind == VK_RValue && !DestType->isRecordType() && 760 !isPlaceholder(BuiltinType::Overload)) { 761 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 762 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 763 return; 764 } 765 766 Expr *SrcExprOrig = SrcExpr.get(); 767 unsigned msg = diag::err_bad_cxx_cast_generic; 768 TryCastResult tcr 769 = TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_StaticCast, OpRange, msg, 770 Kind, BasePath); 771 if (tcr != TC_Success && msg != 0) { 772 if (SrcExpr.isInvalid()) 773 return; 774 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 775 OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression; 776 Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload) 777 << oe->getName() << DestType << OpRange 778 << oe->getQualifierLoc().getSourceRange(); 779 Self.NoteAllOverloadCandidates(SrcExpr.get()); 780 } else { 781 diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType); 782 } 783 } else if (tcr == TC_Success) { 784 if (Kind == CK_BitCast) 785 checkCastAlign(); 786 if (Self.getLangOptions().ObjCAutoRefCount) 787 checkObjCARCConversion(Sema::CCK_StaticCast); 788 } else if (Kind == CK_BitCast) { 789 checkCastAlign(); 790 } 791 792 CastNodesCreated = (SrcExpr.get() != SrcExprOrig); 793} 794 795/// TryStaticCast - Check if a static cast can be performed, and do so if 796/// possible. If @p CStyle, ignore access restrictions on hierarchy casting 797/// and casting away constness. 798static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, 799 QualType DestType, 800 Sema::CheckedConversionKind CCK, 801 const SourceRange &OpRange, unsigned &msg, 802 CastKind &Kind, 803 CXXCastPath &BasePath) { 804 // Determine whether we have the semantics of a C-style cast. 805 bool CStyle 806 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 807 808 // The order the tests is not entirely arbitrary. There is one conversion 809 // that can be handled in two different ways. Given: 810 // struct A {}; 811 // struct B : public A { 812 // B(); B(const A&); 813 // }; 814 // const A &a = B(); 815 // the cast static_cast<const B&>(a) could be seen as either a static 816 // reference downcast, or an explicit invocation of the user-defined 817 // conversion using B's conversion constructor. 818 // DR 427 specifies that the downcast is to be applied here. 819 820 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 821 // Done outside this function. 822 823 TryCastResult tcr; 824 825 // C++ 5.2.9p5, reference downcast. 826 // See the function for details. 827 // DR 427 specifies that this is to be applied before paragraph 2. 828 tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle, OpRange, 829 msg, Kind, BasePath); 830 if (tcr != TC_NotApplicable) 831 return tcr; 832 833 // C++0x [expr.static.cast]p3: 834 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2 835 // T2" if "cv2 T2" is reference-compatible with "cv1 T1". 836 tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind, BasePath, 837 msg); 838 if (tcr != TC_NotApplicable) 839 return tcr; 840 841 // C++ 5.2.9p2: An expression e can be explicitly converted to a type T 842 // [...] if the declaration "T t(e);" is well-formed, [...]. 843 tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg, 844 Kind); 845 if (SrcExpr.isInvalid()) 846 return TC_Failed; 847 if (tcr != TC_NotApplicable) 848 return tcr; 849 850 // C++ 5.2.9p6: May apply the reverse of any standard conversion, except 851 // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean 852 // conversions, subject to further restrictions. 853 // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal 854 // of qualification conversions impossible. 855 // In the CStyle case, the earlier attempt to const_cast should have taken 856 // care of reverse qualification conversions. 857 858 QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType()); 859 860 // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly 861 // converted to an integral type. [...] A value of a scoped enumeration type 862 // can also be explicitly converted to a floating-point type [...]. 863 if (const EnumType *Enum = SrcType->getAs<EnumType>()) { 864 if (Enum->getDecl()->isScoped()) { 865 if (DestType->isBooleanType()) { 866 Kind = CK_IntegralToBoolean; 867 return TC_Success; 868 } else if (DestType->isIntegralType(Self.Context)) { 869 Kind = CK_IntegralCast; 870 return TC_Success; 871 } else if (DestType->isRealFloatingType()) { 872 Kind = CK_IntegralToFloating; 873 return TC_Success; 874 } 875 } 876 } 877 878 // Reverse integral promotion/conversion. All such conversions are themselves 879 // again integral promotions or conversions and are thus already handled by 880 // p2 (TryDirectInitialization above). 881 // (Note: any data loss warnings should be suppressed.) 882 // The exception is the reverse of enum->integer, i.e. integer->enum (and 883 // enum->enum). See also C++ 5.2.9p7. 884 // The same goes for reverse floating point promotion/conversion and 885 // floating-integral conversions. Again, only floating->enum is relevant. 886 if (DestType->isEnumeralType()) { 887 if (SrcType->isIntegralOrEnumerationType()) { 888 Kind = CK_IntegralCast; 889 return TC_Success; 890 } else if (SrcType->isRealFloatingType()) { 891 Kind = CK_FloatingToIntegral; 892 return TC_Success; 893 } 894 } 895 896 // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast. 897 // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance. 898 tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg, 899 Kind, BasePath); 900 if (tcr != TC_NotApplicable) 901 return tcr; 902 903 // Reverse member pointer conversion. C++ 4.11 specifies member pointer 904 // conversion. C++ 5.2.9p9 has additional information. 905 // DR54's access restrictions apply here also. 906 tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle, 907 OpRange, msg, Kind, BasePath); 908 if (tcr != TC_NotApplicable) 909 return tcr; 910 911 // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to 912 // void*. C++ 5.2.9p10 specifies additional restrictions, which really is 913 // just the usual constness stuff. 914 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 915 QualType SrcPointee = SrcPointer->getPointeeType(); 916 if (SrcPointee->isVoidType()) { 917 if (const PointerType *DestPointer = DestType->getAs<PointerType>()) { 918 QualType DestPointee = DestPointer->getPointeeType(); 919 if (DestPointee->isIncompleteOrObjectType()) { 920 // This is definitely the intended conversion, but it might fail due 921 // to a qualifier violation. Note that we permit Objective-C lifetime 922 // and GC qualifier mismatches here. 923 if (!CStyle) { 924 Qualifiers DestPointeeQuals = DestPointee.getQualifiers(); 925 Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers(); 926 DestPointeeQuals.removeObjCGCAttr(); 927 DestPointeeQuals.removeObjCLifetime(); 928 SrcPointeeQuals.removeObjCGCAttr(); 929 SrcPointeeQuals.removeObjCLifetime(); 930 if (DestPointeeQuals != SrcPointeeQuals && 931 !DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) { 932 msg = diag::err_bad_cxx_cast_qualifiers_away; 933 return TC_Failed; 934 } 935 } 936 Kind = CK_BitCast; 937 return TC_Success; 938 } 939 } 940 else if (DestType->isObjCObjectPointerType()) { 941 // allow both c-style cast and static_cast of objective-c pointers as 942 // they are pervasive. 943 Kind = CK_CPointerToObjCPointerCast; 944 return TC_Success; 945 } 946 else if (CStyle && DestType->isBlockPointerType()) { 947 // allow c-style cast of void * to block pointers. 948 Kind = CK_AnyPointerToBlockPointerCast; 949 return TC_Success; 950 } 951 } 952 } 953 // Allow arbitray objective-c pointer conversion with static casts. 954 if (SrcType->isObjCObjectPointerType() && 955 DestType->isObjCObjectPointerType()) { 956 Kind = CK_BitCast; 957 return TC_Success; 958 } 959 960 // We tried everything. Everything! Nothing works! :-( 961 return TC_NotApplicable; 962} 963 964/// Tests whether a conversion according to N2844 is valid. 965TryCastResult 966TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType, 967 bool CStyle, CastKind &Kind, CXXCastPath &BasePath, 968 unsigned &msg) { 969 // C++0x [expr.static.cast]p3: 970 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to 971 // cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1". 972 const RValueReferenceType *R = DestType->getAs<RValueReferenceType>(); 973 if (!R) 974 return TC_NotApplicable; 975 976 if (!SrcExpr->isGLValue()) 977 return TC_NotApplicable; 978 979 // Because we try the reference downcast before this function, from now on 980 // this is the only cast possibility, so we issue an error if we fail now. 981 // FIXME: Should allow casting away constness if CStyle. 982 bool DerivedToBase; 983 bool ObjCConversion; 984 bool ObjCLifetimeConversion; 985 QualType FromType = SrcExpr->getType(); 986 QualType ToType = R->getPointeeType(); 987 if (CStyle) { 988 FromType = FromType.getUnqualifiedType(); 989 ToType = ToType.getUnqualifiedType(); 990 } 991 992 if (Self.CompareReferenceRelationship(SrcExpr->getLocStart(), 993 ToType, FromType, 994 DerivedToBase, ObjCConversion, 995 ObjCLifetimeConversion) 996 < Sema::Ref_Compatible_With_Added_Qualification) { 997 msg = diag::err_bad_lvalue_to_rvalue_cast; 998 return TC_Failed; 999 } 1000 1001 if (DerivedToBase) { 1002 Kind = CK_DerivedToBase; 1003 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1004 /*DetectVirtual=*/true); 1005 if (!Self.IsDerivedFrom(SrcExpr->getType(), R->getPointeeType(), Paths)) 1006 return TC_NotApplicable; 1007 1008 Self.BuildBasePathArray(Paths, BasePath); 1009 } else 1010 Kind = CK_NoOp; 1011 1012 return TC_Success; 1013} 1014 1015/// Tests whether a conversion according to C++ 5.2.9p5 is valid. 1016TryCastResult 1017TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType, 1018 bool CStyle, const SourceRange &OpRange, 1019 unsigned &msg, CastKind &Kind, 1020 CXXCastPath &BasePath) { 1021 // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be 1022 // cast to type "reference to cv2 D", where D is a class derived from B, 1023 // if a valid standard conversion from "pointer to D" to "pointer to B" 1024 // exists, cv2 >= cv1, and B is not a virtual base class of D. 1025 // In addition, DR54 clarifies that the base must be accessible in the 1026 // current context. Although the wording of DR54 only applies to the pointer 1027 // variant of this rule, the intent is clearly for it to apply to the this 1028 // conversion as well. 1029 1030 const ReferenceType *DestReference = DestType->getAs<ReferenceType>(); 1031 if (!DestReference) { 1032 return TC_NotApplicable; 1033 } 1034 bool RValueRef = DestReference->isRValueReferenceType(); 1035 if (!RValueRef && !SrcExpr->isLValue()) { 1036 // We know the left side is an lvalue reference, so we can suggest a reason. 1037 msg = diag::err_bad_cxx_cast_rvalue; 1038 return TC_NotApplicable; 1039 } 1040 1041 QualType DestPointee = DestReference->getPointeeType(); 1042 1043 return TryStaticDowncast(Self, 1044 Self.Context.getCanonicalType(SrcExpr->getType()), 1045 Self.Context.getCanonicalType(DestPointee), CStyle, 1046 OpRange, SrcExpr->getType(), DestType, msg, Kind, 1047 BasePath); 1048} 1049 1050/// Tests whether a conversion according to C++ 5.2.9p8 is valid. 1051TryCastResult 1052TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType, 1053 bool CStyle, const SourceRange &OpRange, 1054 unsigned &msg, CastKind &Kind, 1055 CXXCastPath &BasePath) { 1056 // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class 1057 // type, can be converted to an rvalue of type "pointer to cv2 D", where D 1058 // is a class derived from B, if a valid standard conversion from "pointer 1059 // to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base 1060 // class of D. 1061 // In addition, DR54 clarifies that the base must be accessible in the 1062 // current context. 1063 1064 const PointerType *DestPointer = DestType->getAs<PointerType>(); 1065 if (!DestPointer) { 1066 return TC_NotApplicable; 1067 } 1068 1069 const PointerType *SrcPointer = SrcType->getAs<PointerType>(); 1070 if (!SrcPointer) { 1071 msg = diag::err_bad_static_cast_pointer_nonpointer; 1072 return TC_NotApplicable; 1073 } 1074 1075 return TryStaticDowncast(Self, 1076 Self.Context.getCanonicalType(SrcPointer->getPointeeType()), 1077 Self.Context.getCanonicalType(DestPointer->getPointeeType()), 1078 CStyle, OpRange, SrcType, DestType, msg, Kind, 1079 BasePath); 1080} 1081 1082/// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and 1083/// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to 1084/// DestType is possible and allowed. 1085TryCastResult 1086TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType, 1087 bool CStyle, const SourceRange &OpRange, QualType OrigSrcType, 1088 QualType OrigDestType, unsigned &msg, 1089 CastKind &Kind, CXXCastPath &BasePath) { 1090 // We can only work with complete types. But don't complain if it doesn't work 1091 if (Self.RequireCompleteType(OpRange.getBegin(), SrcType, Self.PDiag(0)) || 1092 Self.RequireCompleteType(OpRange.getBegin(), DestType, Self.PDiag(0))) 1093 return TC_NotApplicable; 1094 1095 // Downcast can only happen in class hierarchies, so we need classes. 1096 if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) { 1097 return TC_NotApplicable; 1098 } 1099 1100 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1101 /*DetectVirtual=*/true); 1102 if (!Self.IsDerivedFrom(DestType, SrcType, Paths)) { 1103 return TC_NotApplicable; 1104 } 1105 1106 // Target type does derive from source type. Now we're serious. If an error 1107 // appears now, it's not ignored. 1108 // This may not be entirely in line with the standard. Take for example: 1109 // struct A {}; 1110 // struct B : virtual A { 1111 // B(A&); 1112 // }; 1113 // 1114 // void f() 1115 // { 1116 // (void)static_cast<const B&>(*((A*)0)); 1117 // } 1118 // As far as the standard is concerned, p5 does not apply (A is virtual), so 1119 // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid. 1120 // However, both GCC and Comeau reject this example, and accepting it would 1121 // mean more complex code if we're to preserve the nice error message. 1122 // FIXME: Being 100% compliant here would be nice to have. 1123 1124 // Must preserve cv, as always, unless we're in C-style mode. 1125 if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) { 1126 msg = diag::err_bad_cxx_cast_qualifiers_away; 1127 return TC_Failed; 1128 } 1129 1130 if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) { 1131 // This code is analoguous to that in CheckDerivedToBaseConversion, except 1132 // that it builds the paths in reverse order. 1133 // To sum up: record all paths to the base and build a nice string from 1134 // them. Use it to spice up the error message. 1135 if (!Paths.isRecordingPaths()) { 1136 Paths.clear(); 1137 Paths.setRecordingPaths(true); 1138 Self.IsDerivedFrom(DestType, SrcType, Paths); 1139 } 1140 std::string PathDisplayStr; 1141 std::set<unsigned> DisplayedPaths; 1142 for (CXXBasePaths::paths_iterator PI = Paths.begin(), PE = Paths.end(); 1143 PI != PE; ++PI) { 1144 if (DisplayedPaths.insert(PI->back().SubobjectNumber).second) { 1145 // We haven't displayed a path to this particular base 1146 // class subobject yet. 1147 PathDisplayStr += "\n "; 1148 for (CXXBasePath::const_reverse_iterator EI = PI->rbegin(), 1149 EE = PI->rend(); 1150 EI != EE; ++EI) 1151 PathDisplayStr += EI->Base->getType().getAsString() + " -> "; 1152 PathDisplayStr += QualType(DestType).getAsString(); 1153 } 1154 } 1155 1156 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast) 1157 << QualType(SrcType).getUnqualifiedType() 1158 << QualType(DestType).getUnqualifiedType() 1159 << PathDisplayStr << OpRange; 1160 msg = 0; 1161 return TC_Failed; 1162 } 1163 1164 if (Paths.getDetectedVirtual() != 0) { 1165 QualType VirtualBase(Paths.getDetectedVirtual(), 0); 1166 Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual) 1167 << OrigSrcType << OrigDestType << VirtualBase << OpRange; 1168 msg = 0; 1169 return TC_Failed; 1170 } 1171 1172 if (!CStyle) { 1173 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1174 SrcType, DestType, 1175 Paths.front(), 1176 diag::err_downcast_from_inaccessible_base)) { 1177 case Sema::AR_accessible: 1178 case Sema::AR_delayed: // be optimistic 1179 case Sema::AR_dependent: // be optimistic 1180 break; 1181 1182 case Sema::AR_inaccessible: 1183 msg = 0; 1184 return TC_Failed; 1185 } 1186 } 1187 1188 Self.BuildBasePathArray(Paths, BasePath); 1189 Kind = CK_BaseToDerived; 1190 return TC_Success; 1191} 1192 1193/// TryStaticMemberPointerUpcast - Tests whether a conversion according to 1194/// C++ 5.2.9p9 is valid: 1195/// 1196/// An rvalue of type "pointer to member of D of type cv1 T" can be 1197/// converted to an rvalue of type "pointer to member of B of type cv2 T", 1198/// where B is a base class of D [...]. 1199/// 1200TryCastResult 1201TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType, 1202 QualType DestType, bool CStyle, 1203 const SourceRange &OpRange, 1204 unsigned &msg, CastKind &Kind, 1205 CXXCastPath &BasePath) { 1206 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(); 1207 if (!DestMemPtr) 1208 return TC_NotApplicable; 1209 1210 bool WasOverloadedFunction = false; 1211 DeclAccessPair FoundOverload; 1212 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 1213 if (FunctionDecl *Fn 1214 = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false, 1215 FoundOverload)) { 1216 CXXMethodDecl *M = cast<CXXMethodDecl>(Fn); 1217 SrcType = Self.Context.getMemberPointerType(Fn->getType(), 1218 Self.Context.getTypeDeclType(M->getParent()).getTypePtr()); 1219 WasOverloadedFunction = true; 1220 } 1221 } 1222 1223 const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 1224 if (!SrcMemPtr) { 1225 msg = diag::err_bad_static_cast_member_pointer_nonmp; 1226 return TC_NotApplicable; 1227 } 1228 1229 // T == T, modulo cv 1230 if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(), 1231 DestMemPtr->getPointeeType())) 1232 return TC_NotApplicable; 1233 1234 // B base of D 1235 QualType SrcClass(SrcMemPtr->getClass(), 0); 1236 QualType DestClass(DestMemPtr->getClass(), 0); 1237 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1238 /*DetectVirtual=*/true); 1239 if (!Self.IsDerivedFrom(SrcClass, DestClass, Paths)) { 1240 return TC_NotApplicable; 1241 } 1242 1243 // B is a base of D. But is it an allowed base? If not, it's a hard error. 1244 if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) { 1245 Paths.clear(); 1246 Paths.setRecordingPaths(true); 1247 bool StillOkay = Self.IsDerivedFrom(SrcClass, DestClass, Paths); 1248 assert(StillOkay); 1249 (void)StillOkay; 1250 std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths); 1251 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv) 1252 << 1 << SrcClass << DestClass << PathDisplayStr << OpRange; 1253 msg = 0; 1254 return TC_Failed; 1255 } 1256 1257 if (const RecordType *VBase = Paths.getDetectedVirtual()) { 1258 Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual) 1259 << SrcClass << DestClass << QualType(VBase, 0) << OpRange; 1260 msg = 0; 1261 return TC_Failed; 1262 } 1263 1264 if (!CStyle) { 1265 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1266 DestClass, SrcClass, 1267 Paths.front(), 1268 diag::err_upcast_to_inaccessible_base)) { 1269 case Sema::AR_accessible: 1270 case Sema::AR_delayed: 1271 case Sema::AR_dependent: 1272 // Optimistically assume that the delayed and dependent cases 1273 // will work out. 1274 break; 1275 1276 case Sema::AR_inaccessible: 1277 msg = 0; 1278 return TC_Failed; 1279 } 1280 } 1281 1282 if (WasOverloadedFunction) { 1283 // Resolve the address of the overloaded function again, this time 1284 // allowing complaints if something goes wrong. 1285 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 1286 DestType, 1287 true, 1288 FoundOverload); 1289 if (!Fn) { 1290 msg = 0; 1291 return TC_Failed; 1292 } 1293 1294 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn); 1295 if (!SrcExpr.isUsable()) { 1296 msg = 0; 1297 return TC_Failed; 1298 } 1299 } 1300 1301 Self.BuildBasePathArray(Paths, BasePath); 1302 Kind = CK_DerivedToBaseMemberPointer; 1303 return TC_Success; 1304} 1305 1306/// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2 1307/// is valid: 1308/// 1309/// An expression e can be explicitly converted to a type T using a 1310/// @c static_cast if the declaration "T t(e);" is well-formed [...]. 1311TryCastResult 1312TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, 1313 Sema::CheckedConversionKind CCK, 1314 const SourceRange &OpRange, unsigned &msg, 1315 CastKind &Kind) { 1316 if (DestType->isRecordType()) { 1317 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 1318 diag::err_bad_dynamic_cast_incomplete)) { 1319 msg = 0; 1320 return TC_Failed; 1321 } 1322 } 1323 1324 InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType); 1325 InitializationKind InitKind 1326 = (CCK == Sema::CCK_CStyleCast) 1327 ? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange) 1328 : (CCK == Sema::CCK_FunctionalCast) 1329 ? InitializationKind::CreateFunctionalCast(OpRange) 1330 : InitializationKind::CreateStaticCast(OpRange); 1331 Expr *SrcExprRaw = SrcExpr.get(); 1332 InitializationSequence InitSeq(Self, Entity, InitKind, &SrcExprRaw, 1); 1333 1334 // At this point of CheckStaticCast, if the destination is a reference, 1335 // or the expression is an overload expression this has to work. 1336 // There is no other way that works. 1337 // On the other hand, if we're checking a C-style cast, we've still got 1338 // the reinterpret_cast way. 1339 bool CStyle 1340 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 1341 if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType())) 1342 return TC_NotApplicable; 1343 1344 ExprResult Result 1345 = InitSeq.Perform(Self, Entity, InitKind, MultiExprArg(Self, &SrcExprRaw, 1)); 1346 if (Result.isInvalid()) { 1347 msg = 0; 1348 return TC_Failed; 1349 } 1350 1351 if (InitSeq.isConstructorInitialization()) 1352 Kind = CK_ConstructorConversion; 1353 else 1354 Kind = CK_NoOp; 1355 1356 SrcExpr = move(Result); 1357 return TC_Success; 1358} 1359 1360/// TryConstCast - See if a const_cast from source to destination is allowed, 1361/// and perform it if it is. 1362static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType, 1363 bool CStyle, unsigned &msg) { 1364 DestType = Self.Context.getCanonicalType(DestType); 1365 QualType SrcType = SrcExpr->getType(); 1366 if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) { 1367 if (DestTypeTmp->isLValueReferenceType() && !SrcExpr->isLValue()) { 1368 // Cannot const_cast non-lvalue to lvalue reference type. But if this 1369 // is C-style, static_cast might find a way, so we simply suggest a 1370 // message and tell the parent to keep searching. 1371 msg = diag::err_bad_cxx_cast_rvalue; 1372 return TC_NotApplicable; 1373 } 1374 1375 // C++ 5.2.11p4: An lvalue of type T1 can be [cast] to an lvalue of type T2 1376 // [...] if a pointer to T1 can be [cast] to the type pointer to T2. 1377 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 1378 SrcType = Self.Context.getPointerType(SrcType); 1379 } 1380 1381 // C++ 5.2.11p5: For a const_cast involving pointers to data members [...] 1382 // the rules for const_cast are the same as those used for pointers. 1383 1384 if (!DestType->isPointerType() && 1385 !DestType->isMemberPointerType() && 1386 !DestType->isObjCObjectPointerType()) { 1387 // Cannot cast to non-pointer, non-reference type. Note that, if DestType 1388 // was a reference type, we converted it to a pointer above. 1389 // The status of rvalue references isn't entirely clear, but it looks like 1390 // conversion to them is simply invalid. 1391 // C++ 5.2.11p3: For two pointer types [...] 1392 if (!CStyle) 1393 msg = diag::err_bad_const_cast_dest; 1394 return TC_NotApplicable; 1395 } 1396 if (DestType->isFunctionPointerType() || 1397 DestType->isMemberFunctionPointerType()) { 1398 // Cannot cast direct function pointers. 1399 // C++ 5.2.11p2: [...] where T is any object type or the void type [...] 1400 // T is the ultimate pointee of source and target type. 1401 if (!CStyle) 1402 msg = diag::err_bad_const_cast_dest; 1403 return TC_NotApplicable; 1404 } 1405 SrcType = Self.Context.getCanonicalType(SrcType); 1406 1407 // Unwrap the pointers. Ignore qualifiers. Terminate early if the types are 1408 // completely equal. 1409 // C++ 5.2.11p3 describes the core semantics of const_cast. All cv specifiers 1410 // in multi-level pointers may change, but the level count must be the same, 1411 // as must be the final pointee type. 1412 while (SrcType != DestType && 1413 Self.Context.UnwrapSimilarPointerTypes(SrcType, DestType)) { 1414 Qualifiers SrcQuals, DestQuals; 1415 SrcType = Self.Context.getUnqualifiedArrayType(SrcType, SrcQuals); 1416 DestType = Self.Context.getUnqualifiedArrayType(DestType, DestQuals); 1417 1418 // const_cast is permitted to strip cvr-qualifiers, only. Make sure that 1419 // the other qualifiers (e.g., address spaces) are identical. 1420 SrcQuals.removeCVRQualifiers(); 1421 DestQuals.removeCVRQualifiers(); 1422 if (SrcQuals != DestQuals) 1423 return TC_NotApplicable; 1424 } 1425 1426 // Since we're dealing in canonical types, the remainder must be the same. 1427 if (SrcType != DestType) 1428 return TC_NotApplicable; 1429 1430 return TC_Success; 1431} 1432 1433// Checks for undefined behavior in reinterpret_cast. 1434// The cases that is checked for is: 1435// *reinterpret_cast<T*>(&a) 1436// reinterpret_cast<T&>(a) 1437// where accessing 'a' as type 'T' will result in undefined behavior. 1438void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType, 1439 bool IsDereference, 1440 SourceRange Range) { 1441 unsigned DiagID = IsDereference ? 1442 diag::warn_pointer_indirection_from_incompatible_type : 1443 diag::warn_undefined_reinterpret_cast; 1444 1445 if (Diags.getDiagnosticLevel(DiagID, Range.getBegin()) == 1446 DiagnosticsEngine::Ignored) { 1447 return; 1448 } 1449 1450 QualType SrcTy, DestTy; 1451 if (IsDereference) { 1452 if (!SrcType->getAs<PointerType>() || !DestType->getAs<PointerType>()) { 1453 return; 1454 } 1455 SrcTy = SrcType->getPointeeType(); 1456 DestTy = DestType->getPointeeType(); 1457 } else { 1458 if (!DestType->getAs<ReferenceType>()) { 1459 return; 1460 } 1461 SrcTy = SrcType; 1462 DestTy = DestType->getPointeeType(); 1463 } 1464 1465 // Cast is compatible if the types are the same. 1466 if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) { 1467 return; 1468 } 1469 // or one of the types is a char or void type 1470 if (DestTy->isAnyCharacterType() || DestTy->isVoidType() || 1471 SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) { 1472 return; 1473 } 1474 // or one of the types is a tag type. 1475 if (SrcTy->getAs<TagType>() || DestTy->getAs<TagType>()) { 1476 return; 1477 } 1478 1479 // FIXME: Scoped enums? 1480 if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) || 1481 (SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) { 1482 if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) { 1483 return; 1484 } 1485 } 1486 1487 Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range; 1488} 1489 1490static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr, 1491 QualType DestType, bool CStyle, 1492 const SourceRange &OpRange, 1493 unsigned &msg, 1494 CastKind &Kind) { 1495 bool IsLValueCast = false; 1496 1497 DestType = Self.Context.getCanonicalType(DestType); 1498 QualType SrcType = SrcExpr.get()->getType(); 1499 1500 // Is the source an overloaded name? (i.e. &foo) 1501 // If so, reinterpret_cast can not help us here (13.4, p1, bullet 5) ... 1502 if (SrcType == Self.Context.OverloadTy) { 1503 // ... unless foo<int> resolves to an lvalue unambiguously. 1504 // TODO: what if this fails because of DiagnoseUseOfDecl or something 1505 // like it? 1506 ExprResult SingleFunctionExpr = SrcExpr; 1507 if (Self.ResolveAndFixSingleFunctionTemplateSpecialization( 1508 SingleFunctionExpr, 1509 Expr::getValueKindForType(DestType) == VK_RValue // Convert Fun to Ptr 1510 ) && SingleFunctionExpr.isUsable()) { 1511 SrcExpr = move(SingleFunctionExpr); 1512 SrcType = SrcExpr.get()->getType(); 1513 } else { 1514 return TC_NotApplicable; 1515 } 1516 } 1517 1518 if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) { 1519 bool LValue = DestTypeTmp->isLValueReferenceType(); 1520 if (LValue && !SrcExpr.get()->isLValue()) { 1521 // Cannot cast non-lvalue to lvalue reference type. See the similar 1522 // comment in const_cast. 1523 msg = diag::err_bad_cxx_cast_rvalue; 1524 return TC_NotApplicable; 1525 } 1526 1527 if (!CStyle) { 1528 Self.CheckCompatibleReinterpretCast(SrcType, DestType, 1529 /*isDereference=*/false, OpRange); 1530 } 1531 1532 // C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the 1533 // same effect as the conversion *reinterpret_cast<T*>(&x) with the 1534 // built-in & and * operators. 1535 1536 const char *inappropriate = 0; 1537 switch (SrcExpr.get()->getObjectKind()) { 1538 case OK_Ordinary: 1539 break; 1540 case OK_BitField: inappropriate = "bit-field"; break; 1541 case OK_VectorComponent: inappropriate = "vector element"; break; 1542 case OK_ObjCProperty: inappropriate = "property expression"; break; 1543 } 1544 if (inappropriate) { 1545 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference) 1546 << inappropriate << DestType 1547 << OpRange << SrcExpr.get()->getSourceRange(); 1548 msg = 0; SrcExpr = ExprError(); 1549 return TC_NotApplicable; 1550 } 1551 1552 // This code does this transformation for the checked types. 1553 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 1554 SrcType = Self.Context.getPointerType(SrcType); 1555 1556 IsLValueCast = true; 1557 } 1558 1559 // Canonicalize source for comparison. 1560 SrcType = Self.Context.getCanonicalType(SrcType); 1561 1562 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(), 1563 *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 1564 if (DestMemPtr && SrcMemPtr) { 1565 // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1" 1566 // can be explicitly converted to an rvalue of type "pointer to member 1567 // of Y of type T2" if T1 and T2 are both function types or both object 1568 // types. 1569 if (DestMemPtr->getPointeeType()->isFunctionType() != 1570 SrcMemPtr->getPointeeType()->isFunctionType()) 1571 return TC_NotApplicable; 1572 1573 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away 1574 // constness. 1575 // A reinterpret_cast followed by a const_cast can, though, so in C-style, 1576 // we accept it. 1577 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, 1578 /*CheckObjCLifetime=*/CStyle)) { 1579 msg = diag::err_bad_cxx_cast_qualifiers_away; 1580 return TC_Failed; 1581 } 1582 1583 // Don't allow casting between member pointers of different sizes. 1584 if (Self.Context.getTypeSize(DestMemPtr) != 1585 Self.Context.getTypeSize(SrcMemPtr)) { 1586 msg = diag::err_bad_cxx_cast_member_pointer_size; 1587 return TC_Failed; 1588 } 1589 1590 // A valid member pointer cast. 1591 Kind = IsLValueCast? CK_LValueBitCast : CK_BitCast; 1592 return TC_Success; 1593 } 1594 1595 // See below for the enumeral issue. 1596 if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) { 1597 // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral 1598 // type large enough to hold it. A value of std::nullptr_t can be 1599 // converted to an integral type; the conversion has the same meaning 1600 // and validity as a conversion of (void*)0 to the integral type. 1601 if (Self.Context.getTypeSize(SrcType) > 1602 Self.Context.getTypeSize(DestType)) { 1603 msg = diag::err_bad_reinterpret_cast_small_int; 1604 return TC_Failed; 1605 } 1606 Kind = CK_PointerToIntegral; 1607 return TC_Success; 1608 } 1609 1610 bool destIsVector = DestType->isVectorType(); 1611 bool srcIsVector = SrcType->isVectorType(); 1612 if (srcIsVector || destIsVector) { 1613 // FIXME: Should this also apply to floating point types? 1614 bool srcIsScalar = SrcType->isIntegralType(Self.Context); 1615 bool destIsScalar = DestType->isIntegralType(Self.Context); 1616 1617 // Check if this is a cast between a vector and something else. 1618 if (!(srcIsScalar && destIsVector) && !(srcIsVector && destIsScalar) && 1619 !(srcIsVector && destIsVector)) 1620 return TC_NotApplicable; 1621 1622 // If both types have the same size, we can successfully cast. 1623 if (Self.Context.getTypeSize(SrcType) 1624 == Self.Context.getTypeSize(DestType)) { 1625 Kind = CK_BitCast; 1626 return TC_Success; 1627 } 1628 1629 if (destIsScalar) 1630 msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size; 1631 else if (srcIsScalar) 1632 msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size; 1633 else 1634 msg = diag::err_bad_cxx_cast_vector_to_vector_different_size; 1635 1636 return TC_Failed; 1637 } 1638 1639 bool destIsPtr = DestType->isAnyPointerType() || 1640 DestType->isBlockPointerType(); 1641 bool srcIsPtr = SrcType->isAnyPointerType() || 1642 SrcType->isBlockPointerType(); 1643 if (!destIsPtr && !srcIsPtr) { 1644 // Except for std::nullptr_t->integer and lvalue->reference, which are 1645 // handled above, at least one of the two arguments must be a pointer. 1646 return TC_NotApplicable; 1647 } 1648 1649 if (SrcType == DestType) { 1650 // C++ 5.2.10p2 has a note that mentions that, subject to all other 1651 // restrictions, a cast to the same type is allowed. The intent is not 1652 // entirely clear here, since all other paragraphs explicitly forbid casts 1653 // to the same type. However, the behavior of compilers is pretty consistent 1654 // on this point: allow same-type conversion if the involved types are 1655 // pointers, disallow otherwise. 1656 Kind = CK_NoOp; 1657 return TC_Success; 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.getLangOptions().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.getLangOptions().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.getLangOptions().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 1764void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle, 1765 bool &CastNodesCreated) { 1766 CastNodesCreated = false; 1767 // Handle placeholders. 1768 if (isPlaceholder()) { 1769 // C-style casts can resolve __unknown_any types. 1770 if (claimPlaceholder(BuiltinType::UnknownAny)) { 1771 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 1772 SrcExpr.get(), Kind, 1773 ValueKind, BasePath); 1774 return; 1775 } 1776 1777 checkNonOverloadPlaceholders(); 1778 if (SrcExpr.isInvalid()) 1779 return; 1780 } 1781 1782 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 1783 // This test is outside everything else because it's the only case where 1784 // a non-lvalue-reference target type does not lead to decay. 1785 if (DestType->isVoidType()) { 1786 Kind = CK_ToVoid; 1787 1788 if (claimPlaceholder(BuiltinType::Overload)) { 1789 Self.ResolveAndFixSingleFunctionTemplateSpecialization( 1790 SrcExpr, /* Decay Function to ptr */ false, 1791 /* Complain */ true, DestRange, DestType, 1792 diag::err_bad_cstyle_cast_overload); 1793 if (SrcExpr.isInvalid()) 1794 return; 1795 } 1796 1797 SrcExpr = Self.IgnoredValueConversions(SrcExpr.take()); 1798 if (SrcExpr.isInvalid()) 1799 return; 1800 1801 return; 1802 } 1803 1804 // If the type is dependent, we won't do any other semantic analysis now. 1805 if (DestType->isDependentType() || SrcExpr.get()->isTypeDependent()) { 1806 assert(Kind == CK_Dependent); 1807 return; 1808 } 1809 1810 if (ValueKind == VK_RValue && !DestType->isRecordType() && 1811 !isPlaceholder(BuiltinType::Overload)) { 1812 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 1813 if (SrcExpr.isInvalid()) 1814 return; 1815 } 1816 1817 // AltiVec vector initialization with a single literal. 1818 if (const VectorType *vecTy = DestType->getAs<VectorType>()) 1819 if (vecTy->getVectorKind() == VectorType::AltiVecVector 1820 && (SrcExpr.get()->getType()->isIntegerType() 1821 || SrcExpr.get()->getType()->isFloatingType())) { 1822 Kind = CK_VectorSplat; 1823 return; 1824 } 1825 1826 // C++ [expr.cast]p5: The conversions performed by 1827 // - a const_cast, 1828 // - a static_cast, 1829 // - a static_cast followed by a const_cast, 1830 // - a reinterpret_cast, or 1831 // - a reinterpret_cast followed by a const_cast, 1832 // can be performed using the cast notation of explicit type conversion. 1833 // [...] If a conversion can be interpreted in more than one of the ways 1834 // listed above, the interpretation that appears first in the list is used, 1835 // even if a cast resulting from that interpretation is ill-formed. 1836 // In plain language, this means trying a const_cast ... 1837 unsigned msg = diag::err_bad_cxx_cast_generic; 1838 TryCastResult tcr = TryConstCast(Self, SrcExpr.get(), DestType, 1839 /*CStyle*/true, msg); 1840 if (tcr == TC_Success) 1841 Kind = CK_NoOp; 1842 1843 Sema::CheckedConversionKind CCK 1844 = FunctionalStyle? Sema::CCK_FunctionalCast 1845 : Sema::CCK_CStyleCast; 1846 if (tcr == TC_NotApplicable) { 1847 Expr *SrcExprOrig = SrcExpr.get(); 1848 // ... or if that is not possible, a static_cast, ignoring const, ... 1849 tcr = TryStaticCast(Self, SrcExpr, DestType, CCK, OpRange, 1850 msg, Kind, BasePath); 1851 if (SrcExpr.isInvalid()) 1852 return; 1853 1854 if (tcr == TC_NotApplicable) { 1855 // ... and finally a reinterpret_cast, ignoring const. 1856 tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/true, 1857 OpRange, msg, Kind); 1858 if (SrcExpr.isInvalid()) 1859 return; 1860 } 1861 1862 CastNodesCreated = (SrcExpr.get() != SrcExprOrig); 1863 } 1864 1865 if (Self.getLangOptions().ObjCAutoRefCount && tcr == TC_Success) 1866 checkObjCARCConversion(CCK); 1867 1868 if (tcr != TC_Success && msg != 0) { 1869 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 1870 DeclAccessPair Found; 1871 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 1872 DestType, 1873 /*Complain*/ true, 1874 Found); 1875 1876 assert(!Fn && "cast failed but able to resolve overload expression!!"); 1877 (void)Fn; 1878 1879 } else { 1880 diagnoseBadCast(Self, msg, (FunctionalStyle ? CT_Functional : CT_CStyle), 1881 OpRange, SrcExpr.get(), DestType); 1882 } 1883 } else if (Kind == CK_BitCast) { 1884 checkCastAlign(); 1885 } 1886 1887 // Clear out SrcExpr if there was a fatal error. 1888 if (tcr != TC_Success) 1889 SrcExpr = ExprError(); 1890} 1891 1892/// Check the semantics of a C-style cast operation, in C. 1893void CastOperation::CheckCStyleCast() { 1894 assert(!Self.getLangOptions().CPlusPlus); 1895 1896 // C-style casts can resolve __unknown_any types. 1897 if (claimPlaceholder(BuiltinType::UnknownAny)) { 1898 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 1899 SrcExpr.get(), Kind, 1900 ValueKind, BasePath); 1901 return; 1902 } 1903 1904 // C99 6.5.4p2: the cast type needs to be void or scalar and the expression 1905 // type needs to be scalar. 1906 if (DestType->isVoidType()) { 1907 // We don't necessarily do lvalue-to-rvalue conversions on this. 1908 SrcExpr = Self.IgnoredValueConversions(SrcExpr.take()); 1909 if (SrcExpr.isInvalid()) 1910 return; 1911 1912 // Cast to void allows any expr type. 1913 Kind = CK_ToVoid; 1914 return; 1915 } 1916 1917 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 1918 if (SrcExpr.isInvalid()) 1919 return; 1920 QualType SrcType = SrcExpr.get()->getType(); 1921 assert(!SrcType->isPlaceholderType()); 1922 1923 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 1924 diag::err_typecheck_cast_to_incomplete)) { 1925 SrcExpr = ExprError(); 1926 return; 1927 } 1928 1929 if (!DestType->isScalarType() && !DestType->isVectorType()) { 1930 const RecordType *DestRecordTy = DestType->getAs<RecordType>(); 1931 1932 if (DestRecordTy && Self.Context.hasSameUnqualifiedType(DestType, SrcType)){ 1933 // GCC struct/union extension: allow cast to self. 1934 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_nonscalar) 1935 << DestType << SrcExpr.get()->getSourceRange(); 1936 Kind = CK_NoOp; 1937 return; 1938 } 1939 1940 // GCC's cast to union extension. 1941 if (DestRecordTy && DestRecordTy->getDecl()->isUnion()) { 1942 RecordDecl *RD = DestRecordTy->getDecl(); 1943 RecordDecl::field_iterator Field, FieldEnd; 1944 for (Field = RD->field_begin(), FieldEnd = RD->field_end(); 1945 Field != FieldEnd; ++Field) { 1946 if (Self.Context.hasSameUnqualifiedType(Field->getType(), SrcType) && 1947 !Field->isUnnamedBitfield()) { 1948 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union) 1949 << SrcExpr.get()->getSourceRange(); 1950 break; 1951 } 1952 } 1953 if (Field == FieldEnd) { 1954 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cast_to_union_no_type) 1955 << SrcType << SrcExpr.get()->getSourceRange(); 1956 SrcExpr = ExprError(); 1957 return; 1958 } 1959 Kind = CK_ToUnion; 1960 return; 1961 } 1962 1963 // Reject any other conversions to non-scalar types. 1964 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cond_expect_scalar) 1965 << DestType << SrcExpr.get()->getSourceRange(); 1966 SrcExpr = ExprError(); 1967 return; 1968 } 1969 1970 // The type we're casting to is known to be a scalar or vector. 1971 1972 // Require the operand to be a scalar or vector. 1973 if (!SrcType->isScalarType() && !SrcType->isVectorType()) { 1974 Self.Diag(SrcExpr.get()->getExprLoc(), 1975 diag::err_typecheck_expect_scalar_operand) 1976 << SrcType << SrcExpr.get()->getSourceRange(); 1977 SrcExpr = ExprError(); 1978 return; 1979 } 1980 1981 if (DestType->isExtVectorType()) { 1982 SrcExpr = Self.CheckExtVectorCast(OpRange, DestType, SrcExpr.take(), Kind); 1983 return; 1984 } 1985 1986 if (const VectorType *DestVecTy = DestType->getAs<VectorType>()) { 1987 if (DestVecTy->getVectorKind() == VectorType::AltiVecVector && 1988 (SrcType->isIntegerType() || SrcType->isFloatingType())) { 1989 Kind = CK_VectorSplat; 1990 } else if (Self.CheckVectorCast(OpRange, DestType, SrcType, Kind)) { 1991 SrcExpr = ExprError(); 1992 } 1993 return; 1994 } 1995 1996 if (SrcType->isVectorType()) { 1997 if (Self.CheckVectorCast(OpRange, SrcType, DestType, Kind)) 1998 SrcExpr = ExprError(); 1999 return; 2000 } 2001 2002 // The source and target types are both scalars, i.e. 2003 // - arithmetic types (fundamental, enum, and complex) 2004 // - all kinds of pointers 2005 // Note that member pointers were filtered out with C++, above. 2006 2007 if (isa<ObjCSelectorExpr>(SrcExpr.get())) { 2008 Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_selector_expr); 2009 SrcExpr = ExprError(); 2010 return; 2011 } 2012 2013 // If either type is a pointer, the other type has to be either an 2014 // integer or a pointer. 2015 if (!DestType->isArithmeticType()) { 2016 if (!SrcType->isIntegralType(Self.Context) && SrcType->isArithmeticType()) { 2017 Self.Diag(SrcExpr.get()->getExprLoc(), 2018 diag::err_cast_pointer_from_non_pointer_int) 2019 << SrcType << SrcExpr.get()->getSourceRange(); 2020 SrcExpr = ExprError(); 2021 return; 2022 } 2023 } else if (!SrcType->isArithmeticType()) { 2024 if (!DestType->isIntegralType(Self.Context) && 2025 DestType->isArithmeticType()) { 2026 Self.Diag(SrcExpr.get()->getLocStart(), 2027 diag::err_cast_pointer_to_non_pointer_int) 2028 << DestType << SrcExpr.get()->getSourceRange(); 2029 SrcExpr = ExprError(); 2030 return; 2031 } 2032 } 2033 2034 // ARC imposes extra restrictions on casts. 2035 if (Self.getLangOptions().ObjCAutoRefCount) { 2036 checkObjCARCConversion(Sema::CCK_CStyleCast); 2037 if (SrcExpr.isInvalid()) 2038 return; 2039 2040 if (const PointerType *CastPtr = DestType->getAs<PointerType>()) { 2041 if (const PointerType *ExprPtr = SrcType->getAs<PointerType>()) { 2042 Qualifiers CastQuals = CastPtr->getPointeeType().getQualifiers(); 2043 Qualifiers ExprQuals = ExprPtr->getPointeeType().getQualifiers(); 2044 if (CastPtr->getPointeeType()->isObjCLifetimeType() && 2045 ExprPtr->getPointeeType()->isObjCLifetimeType() && 2046 !CastQuals.compatiblyIncludesObjCLifetime(ExprQuals)) { 2047 Self.Diag(SrcExpr.get()->getLocStart(), 2048 diag::err_typecheck_incompatible_ownership) 2049 << SrcType << DestType << Sema::AA_Casting 2050 << SrcExpr.get()->getSourceRange(); 2051 return; 2052 } 2053 } 2054 } 2055 else if (!Self.CheckObjCARCUnavailableWeakConversion(DestType, SrcType)) { 2056 Self.Diag(SrcExpr.get()->getLocStart(), 2057 diag::err_arc_convesion_of_weak_unavailable) 2058 << 1 << SrcType << DestType << SrcExpr.get()->getSourceRange(); 2059 SrcExpr = ExprError(); 2060 return; 2061 } 2062 } 2063 2064 Kind = Self.PrepareScalarCast(SrcExpr, DestType); 2065 if (SrcExpr.isInvalid()) 2066 return; 2067 2068 if (Kind == CK_BitCast) 2069 checkCastAlign(); 2070} 2071 2072ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc, 2073 TypeSourceInfo *CastTypeInfo, 2074 SourceLocation RPLoc, 2075 Expr *CastExpr) { 2076 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr); 2077 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2078 Op.OpRange = SourceRange(LPLoc, CastExpr->getLocEnd()); 2079 2080 bool CastNodesCreated = false; 2081 if (getLangOptions().CPlusPlus) { 2082 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/ false, CastNodesCreated); 2083 } else { 2084 Op.CheckCStyleCast(); 2085 } 2086 2087 if (Op.SrcExpr.isInvalid()) 2088 return ExprError(); 2089 2090 // CheckCXXCStyleCast _may_ have already created the CStyleCastExpr 2091 // node. Let's check. 2092 if (CastNodesCreated) { 2093 if (CStyleCastExpr *Cast = dyn_cast<CStyleCastExpr>(Op.SrcExpr.get())){ 2094 assert(!Cast->getTypeInfoAsWritten() && 2095 "The explicit cast node created by CheckStaticCast " 2096 "has source type infos!"); 2097 Cast->setTypeInfoAsWritten(CastTypeInfo); 2098 Cast->setLParenLoc(LPLoc); 2099 Cast->setRParenLoc(RPLoc); 2100 return Op.complete(Cast); 2101 } 2102 } 2103 2104 return Op.complete(CStyleCastExpr::Create(Context, Op.ResultType, 2105 Op.ValueKind, Op.Kind, Op.SrcExpr.take(), 2106 &Op.BasePath, CastTypeInfo, LPLoc, RPLoc)); 2107} 2108 2109ExprResult Sema::BuildCXXFunctionalCastExpr(TypeSourceInfo *CastTypeInfo, 2110 SourceLocation LPLoc, 2111 Expr *CastExpr, 2112 SourceLocation RPLoc) { 2113 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr); 2114 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2115 Op.OpRange = SourceRange(Op.DestRange.getBegin(), CastExpr->getLocEnd()); 2116 2117 bool CastNodesCreated = false; 2118 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/ true, CastNodesCreated); 2119 if (Op.SrcExpr.isInvalid()) 2120 return ExprError(); 2121 2122 // CheckCXXCStyleCast _may_ have already created the CXXFunctionalCastExpr 2123 // node. Let's check. 2124 if (CastNodesCreated) { 2125 if (CXXFunctionalCastExpr *Cast = 2126 dyn_cast<CXXFunctionalCastExpr>(Op.SrcExpr.get())){ 2127 assert(!Cast->getTypeInfoAsWritten() && 2128 "The explicit cast node created by CheckStaticCast " 2129 "has source type infos!"); 2130 Cast->setTypeInfoAsWritten(CastTypeInfo); 2131 Cast->setTypeBeginLoc(Op.DestRange.getBegin()); 2132 Cast->setRParenLoc(RPLoc); 2133 return Op.complete(Cast); 2134 } 2135 } 2136 2137 return Op.complete(CXXFunctionalCastExpr::Create(Context, Op.ResultType, 2138 Op.ValueKind, CastTypeInfo, Op.DestRange.getBegin(), 2139 Op.Kind, Op.SrcExpr.take(), &Op.BasePath, RPLoc)); 2140} 2141 2142