SemaCast.cpp revision d8d3ced6f5d7fa55272194b7165a2321a3be31dc
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 bool IsARCUnbridgedCast; 69 BuiltinType::Kind PlaceholderKind; 70 CXXCastPath BasePath; 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); 81 void CheckCStyleCast(); 82 83 // Internal convenience methods. 84 85 /// Try to handle the given placeholder expression kind. Return 86 /// true if the source expression has the appropriate placeholder 87 /// kind. A placeholder can only be claimed once. 88 bool claimPlaceholder(BuiltinType::Kind K) { 89 if (PlaceholderKind != K) return false; 90 91 PlaceholderKind = (BuiltinType::Kind) 0; 92 return true; 93 } 94 95 bool isPlaceholder() const { 96 return PlaceholderKind != 0; 97 } 98 bool isPlaceholder(BuiltinType::Kind K) const { 99 return PlaceholderKind == K; 100 } 101 102 void checkCastAlign() { 103 Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange); 104 } 105 106 void checkObjCARCConversion(Sema::CheckedConversionKind CCK) { 107 Expr *src = SrcExpr.get(); 108 Self.CheckObjCARCConversion(OpRange, DestType, src, CCK); 109 SrcExpr = src; 110 } 111 112 /// Check for and handle non-overload placeholder expressions. 113 void checkNonOverloadPlaceholders() { 114 if (!isPlaceholder() || isPlaceholder(BuiltinType::Overload)) 115 return; 116 117 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.take()); 118 if (SrcExpr.isInvalid()) 119 return; 120 PlaceholderKind = (BuiltinType::Kind) 0; 121 } 122 }; 123} 124 125static bool CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, 126 bool CheckCVR, bool CheckObjCLifetime); 127 128// The Try functions attempt a specific way of casting. If they succeed, they 129// return TC_Success. If their way of casting is not appropriate for the given 130// arguments, they return TC_NotApplicable and *may* set diag to a diagnostic 131// to emit if no other way succeeds. If their way of casting is appropriate but 132// fails, they return TC_Failed and *must* set diag; they can set it to 0 if 133// they emit a specialized diagnostic. 134// All diagnostics returned by these functions must expect the same three 135// arguments: 136// %0: Cast Type (a value from the CastType enumeration) 137// %1: Source Type 138// %2: Destination Type 139static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, 140 QualType DestType, bool CStyle, 141 CastKind &Kind, 142 CXXCastPath &BasePath, 143 unsigned &msg); 144static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, 145 QualType DestType, bool CStyle, 146 const SourceRange &OpRange, 147 unsigned &msg, 148 CastKind &Kind, 149 CXXCastPath &BasePath); 150static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType, 151 QualType DestType, bool CStyle, 152 const SourceRange &OpRange, 153 unsigned &msg, 154 CastKind &Kind, 155 CXXCastPath &BasePath); 156static TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType, 157 CanQualType DestType, bool CStyle, 158 const SourceRange &OpRange, 159 QualType OrigSrcType, 160 QualType OrigDestType, unsigned &msg, 161 CastKind &Kind, 162 CXXCastPath &BasePath); 163static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, 164 QualType SrcType, 165 QualType DestType,bool CStyle, 166 const SourceRange &OpRange, 167 unsigned &msg, 168 CastKind &Kind, 169 CXXCastPath &BasePath); 170 171static TryCastResult TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, 172 QualType DestType, 173 Sema::CheckedConversionKind CCK, 174 const SourceRange &OpRange, 175 unsigned &msg, 176 CastKind &Kind); 177static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, 178 QualType DestType, 179 Sema::CheckedConversionKind CCK, 180 const SourceRange &OpRange, 181 unsigned &msg, 182 CastKind &Kind, 183 CXXCastPath &BasePath); 184static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType, 185 bool CStyle, unsigned &msg); 186static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr, 187 QualType DestType, bool CStyle, 188 const SourceRange &OpRange, 189 unsigned &msg, 190 CastKind &Kind); 191 192 193/// ActOnCXXNamedCast - Parse {dynamic,static,reinterpret,const}_cast's. 194ExprResult 195Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind, 196 SourceLocation LAngleBracketLoc, Declarator &D, 197 SourceLocation RAngleBracketLoc, 198 SourceLocation LParenLoc, Expr *E, 199 SourceLocation RParenLoc) { 200 201 assert(!D.isInvalidType()); 202 203 TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, E->getType()); 204 if (D.isInvalidType()) 205 return ExprError(); 206 207 if (getLangOptions().CPlusPlus) { 208 // Check that there are no default arguments (C++ only). 209 CheckExtraCXXDefaultArguments(D); 210 } 211 212 return BuildCXXNamedCast(OpLoc, Kind, TInfo, move(E), 213 SourceRange(LAngleBracketLoc, RAngleBracketLoc), 214 SourceRange(LParenLoc, RParenLoc)); 215} 216 217ExprResult 218Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind, 219 TypeSourceInfo *DestTInfo, Expr *E, 220 SourceRange AngleBrackets, SourceRange Parens) { 221 ExprResult Ex = Owned(E); 222 QualType DestType = DestTInfo->getType(); 223 224 // If the type is dependent, we won't do the semantic analysis now. 225 // FIXME: should we check this in a more fine-grained manner? 226 bool TypeDependent = DestType->isDependentType() || Ex.get()->isTypeDependent(); 227 228 CastOperation Op(*this, DestType, E); 229 Op.OpRange = SourceRange(OpLoc, Parens.getEnd()); 230 Op.DestRange = AngleBrackets; 231 232 switch (Kind) { 233 default: llvm_unreachable("Unknown C++ cast!"); 234 235 case tok::kw_const_cast: 236 if (!TypeDependent) { 237 Op.CheckConstCast(); 238 if (Op.SrcExpr.isInvalid()) 239 return ExprError(); 240 } 241 return Owned(CXXConstCastExpr::Create(Context, Op.ResultType, Op.ValueKind, 242 Op.SrcExpr.take(), DestTInfo, OpLoc, 243 Parens.getEnd())); 244 245 case tok::kw_dynamic_cast: { 246 if (!TypeDependent) { 247 Op.CheckDynamicCast(); 248 if (Op.SrcExpr.isInvalid()) 249 return ExprError(); 250 } 251 return Owned(CXXDynamicCastExpr::Create(Context, Op.ResultType, 252 Op.ValueKind, Op.Kind, 253 Op.SrcExpr.take(), &Op.BasePath, 254 DestTInfo, OpLoc, Parens.getEnd())); 255 } 256 case tok::kw_reinterpret_cast: { 257 if (!TypeDependent) { 258 Op.CheckReinterpretCast(); 259 if (Op.SrcExpr.isInvalid()) 260 return ExprError(); 261 } 262 return Owned(CXXReinterpretCastExpr::Create(Context, Op.ResultType, 263 Op.ValueKind, Op.Kind, 264 Op.SrcExpr.take(), 0, 265 DestTInfo, OpLoc, 266 Parens.getEnd())); 267 } 268 case tok::kw_static_cast: { 269 if (!TypeDependent) { 270 Op.CheckStaticCast(); 271 if (Op.SrcExpr.isInvalid()) 272 return ExprError(); 273 } 274 275 return Owned(CXXStaticCastExpr::Create(Context, Op.ResultType, Op.ValueKind, 276 Op.Kind, Op.SrcExpr.take(), 277 &Op.BasePath, DestTInfo, OpLoc, 278 Parens.getEnd())); 279 } 280 } 281 282 return ExprError(); 283} 284 285/// Try to diagnose a failed overloaded cast. Returns true if 286/// diagnostics were emitted. 287static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT, 288 SourceRange range, Expr *src, 289 QualType destType) { 290 switch (CT) { 291 // These cast kinds don't consider user-defined conversions. 292 case CT_Const: 293 case CT_Reinterpret: 294 case CT_Dynamic: 295 return false; 296 297 // These do. 298 case CT_Static: 299 case CT_CStyle: 300 case CT_Functional: 301 break; 302 } 303 304 QualType srcType = src->getType(); 305 if (!destType->isRecordType() && !srcType->isRecordType()) 306 return false; 307 308 InitializedEntity entity = InitializedEntity::InitializeTemporary(destType); 309 InitializationKind initKind 310 = (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(), 311 range) 312 : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range) 313 : InitializationKind::CreateCast(/*type range?*/ range); 314 InitializationSequence sequence(S, entity, initKind, &src, 1); 315 316 assert(sequence.Failed() && "initialization succeeded on second try?"); 317 switch (sequence.getFailureKind()) { 318 default: return false; 319 320 case InitializationSequence::FK_ConstructorOverloadFailed: 321 case InitializationSequence::FK_UserConversionOverloadFailed: 322 break; 323 } 324 325 OverloadCandidateSet &candidates = sequence.getFailedCandidateSet(); 326 327 unsigned msg = 0; 328 OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates; 329 330 switch (sequence.getFailedOverloadResult()) { 331 case OR_Success: llvm_unreachable("successful failed overload"); 332 return false; 333 case OR_No_Viable_Function: 334 if (candidates.empty()) 335 msg = diag::err_ovl_no_conversion_in_cast; 336 else 337 msg = diag::err_ovl_no_viable_conversion_in_cast; 338 howManyCandidates = OCD_AllCandidates; 339 break; 340 341 case OR_Ambiguous: 342 msg = diag::err_ovl_ambiguous_conversion_in_cast; 343 howManyCandidates = OCD_ViableCandidates; 344 break; 345 346 case OR_Deleted: 347 msg = diag::err_ovl_deleted_conversion_in_cast; 348 howManyCandidates = OCD_ViableCandidates; 349 break; 350 } 351 352 S.Diag(range.getBegin(), msg) 353 << CT << srcType << destType 354 << range << src->getSourceRange(); 355 356 candidates.NoteCandidates(S, howManyCandidates, &src, 1); 357 358 return true; 359} 360 361/// Diagnose a failed cast. 362static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType, 363 SourceRange opRange, Expr *src, QualType destType) { 364 if (src->getType() == S.Context.BoundMemberTy) { 365 (void) S.CheckPlaceholderExpr(src); // will always fail 366 return; 367 } 368 369 if (msg == diag::err_bad_cxx_cast_generic && 370 tryDiagnoseOverloadedCast(S, castType, opRange, src, destType)) 371 return; 372 373 S.Diag(opRange.getBegin(), msg) << castType 374 << src->getType() << destType << opRange << src->getSourceRange(); 375} 376 377/// UnwrapDissimilarPointerTypes - Like Sema::UnwrapSimilarPointerTypes, 378/// this removes one level of indirection from both types, provided that they're 379/// the same kind of pointer (plain or to-member). Unlike the Sema function, 380/// this one doesn't care if the two pointers-to-member don't point into the 381/// same class. This is because CastsAwayConstness doesn't care. 382static bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) { 383 const PointerType *T1PtrType = T1->getAs<PointerType>(), 384 *T2PtrType = T2->getAs<PointerType>(); 385 if (T1PtrType && T2PtrType) { 386 T1 = T1PtrType->getPointeeType(); 387 T2 = T2PtrType->getPointeeType(); 388 return true; 389 } 390 const ObjCObjectPointerType *T1ObjCPtrType = 391 T1->getAs<ObjCObjectPointerType>(), 392 *T2ObjCPtrType = 393 T2->getAs<ObjCObjectPointerType>(); 394 if (T1ObjCPtrType) { 395 if (T2ObjCPtrType) { 396 T1 = T1ObjCPtrType->getPointeeType(); 397 T2 = T2ObjCPtrType->getPointeeType(); 398 return true; 399 } 400 else if (T2PtrType) { 401 T1 = T1ObjCPtrType->getPointeeType(); 402 T2 = T2PtrType->getPointeeType(); 403 return true; 404 } 405 } 406 else if (T2ObjCPtrType) { 407 if (T1PtrType) { 408 T2 = T2ObjCPtrType->getPointeeType(); 409 T1 = T1PtrType->getPointeeType(); 410 return true; 411 } 412 } 413 414 const MemberPointerType *T1MPType = T1->getAs<MemberPointerType>(), 415 *T2MPType = T2->getAs<MemberPointerType>(); 416 if (T1MPType && T2MPType) { 417 T1 = T1MPType->getPointeeType(); 418 T2 = T2MPType->getPointeeType(); 419 return true; 420 } 421 422 const BlockPointerType *T1BPType = T1->getAs<BlockPointerType>(), 423 *T2BPType = T2->getAs<BlockPointerType>(); 424 if (T1BPType && T2BPType) { 425 T1 = T1BPType->getPointeeType(); 426 T2 = T2BPType->getPointeeType(); 427 return true; 428 } 429 430 return false; 431} 432 433/// CastsAwayConstness - Check if the pointer conversion from SrcType to 434/// DestType casts away constness as defined in C++ 5.2.11p8ff. This is used by 435/// the cast checkers. Both arguments must denote pointer (possibly to member) 436/// types. 437/// 438/// \param CheckCVR Whether to check for const/volatile/restrict qualifiers. 439/// 440/// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers. 441static bool 442CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType, 443 bool CheckCVR, bool CheckObjCLifetime) { 444 // If the only checking we care about is for Objective-C lifetime qualifiers, 445 // and we're not in ARC mode, there's nothing to check. 446 if (!CheckCVR && CheckObjCLifetime && 447 !Self.Context.getLangOptions().ObjCAutoRefCount) 448 return false; 449 450 // Casting away constness is defined in C++ 5.2.11p8 with reference to 451 // C++ 4.4. We piggyback on Sema::IsQualificationConversion for this, since 452 // the rules are non-trivial. So first we construct Tcv *...cv* as described 453 // in C++ 5.2.11p8. 454 assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() || 455 SrcType->isBlockPointerType()) && 456 "Source type is not pointer or pointer to member."); 457 assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() || 458 DestType->isBlockPointerType()) && 459 "Destination type is not pointer or pointer to member."); 460 461 QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType), 462 UnwrappedDestType = Self.Context.getCanonicalType(DestType); 463 SmallVector<Qualifiers, 8> cv1, cv2; 464 465 // Find the qualifiers. We only care about cvr-qualifiers for the 466 // purpose of this check, because other qualifiers (address spaces, 467 // Objective-C GC, etc.) are part of the type's identity. 468 while (UnwrapDissimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) { 469 // Determine the relevant qualifiers at this level. 470 Qualifiers SrcQuals, DestQuals; 471 Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals); 472 Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals); 473 474 Qualifiers RetainedSrcQuals, RetainedDestQuals; 475 if (CheckCVR) { 476 RetainedSrcQuals.setCVRQualifiers(SrcQuals.getCVRQualifiers()); 477 RetainedDestQuals.setCVRQualifiers(DestQuals.getCVRQualifiers()); 478 } 479 480 if (CheckObjCLifetime && 481 !DestQuals.compatiblyIncludesObjCLifetime(SrcQuals)) 482 return true; 483 484 cv1.push_back(RetainedSrcQuals); 485 cv2.push_back(RetainedDestQuals); 486 } 487 if (cv1.empty()) 488 return false; 489 490 // Construct void pointers with those qualifiers (in reverse order of 491 // unwrapping, of course). 492 QualType SrcConstruct = Self.Context.VoidTy; 493 QualType DestConstruct = Self.Context.VoidTy; 494 ASTContext &Context = Self.Context; 495 for (SmallVector<Qualifiers, 8>::reverse_iterator i1 = cv1.rbegin(), 496 i2 = cv2.rbegin(); 497 i1 != cv1.rend(); ++i1, ++i2) { 498 SrcConstruct 499 = Context.getPointerType(Context.getQualifiedType(SrcConstruct, *i1)); 500 DestConstruct 501 = Context.getPointerType(Context.getQualifiedType(DestConstruct, *i2)); 502 } 503 504 // Test if they're compatible. 505 bool ObjCLifetimeConversion; 506 return SrcConstruct != DestConstruct && 507 !Self.IsQualificationConversion(SrcConstruct, DestConstruct, false, 508 ObjCLifetimeConversion); 509} 510 511/// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid. 512/// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime- 513/// checked downcasts in class hierarchies. 514void CastOperation::CheckDynamicCast() { 515 QualType OrigSrcType = SrcExpr.get()->getType(); 516 QualType DestType = Self.Context.getCanonicalType(this->DestType); 517 518 // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type, 519 // or "pointer to cv void". 520 521 QualType DestPointee; 522 const PointerType *DestPointer = DestType->getAs<PointerType>(); 523 const ReferenceType *DestReference = 0; 524 if (DestPointer) { 525 DestPointee = DestPointer->getPointeeType(); 526 } else if ((DestReference = DestType->getAs<ReferenceType>())) { 527 DestPointee = DestReference->getPointeeType(); 528 } else { 529 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr) 530 << this->DestType << DestRange; 531 return; 532 } 533 534 const RecordType *DestRecord = DestPointee->getAs<RecordType>(); 535 if (DestPointee->isVoidType()) { 536 assert(DestPointer && "Reference to void is not possible"); 537 } else if (DestRecord) { 538 if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee, 539 Self.PDiag(diag::err_bad_dynamic_cast_incomplete) 540 << DestRange)) 541 return; 542 } else { 543 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 544 << DestPointee.getUnqualifiedType() << DestRange; 545 return; 546 } 547 548 // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to 549 // complete class type, [...]. If T is an lvalue reference type, v shall be 550 // an lvalue of a complete class type, [...]. If T is an rvalue reference 551 // type, v shall be an expression having a complete class type, [...] 552 QualType SrcType = Self.Context.getCanonicalType(OrigSrcType); 553 QualType SrcPointee; 554 if (DestPointer) { 555 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 556 SrcPointee = SrcPointer->getPointeeType(); 557 } else { 558 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr) 559 << OrigSrcType << SrcExpr.get()->getSourceRange(); 560 return; 561 } 562 } else if (DestReference->isLValueReferenceType()) { 563 if (!SrcExpr.get()->isLValue()) { 564 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue) 565 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 566 } 567 SrcPointee = SrcType; 568 } else { 569 SrcPointee = SrcType; 570 } 571 572 const RecordType *SrcRecord = SrcPointee->getAs<RecordType>(); 573 if (SrcRecord) { 574 if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee, 575 Self.PDiag(diag::err_bad_dynamic_cast_incomplete) 576 << SrcExpr.get()->getSourceRange())) 577 return; 578 } else { 579 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class) 580 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 581 return; 582 } 583 584 assert((DestPointer || DestReference) && 585 "Bad destination non-ptr/ref slipped through."); 586 assert((DestRecord || DestPointee->isVoidType()) && 587 "Bad destination pointee slipped through."); 588 assert(SrcRecord && "Bad source pointee slipped through."); 589 590 // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness. 591 if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) { 592 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away) 593 << CT_Dynamic << OrigSrcType << this->DestType << OpRange; 594 return; 595 } 596 597 // C++ 5.2.7p3: If the type of v is the same as the required result type, 598 // [except for cv]. 599 if (DestRecord == SrcRecord) { 600 Kind = CK_NoOp; 601 return; 602 } 603 604 // C++ 5.2.7p5 605 // Upcasts are resolved statically. 606 if (DestRecord && Self.IsDerivedFrom(SrcPointee, DestPointee)) { 607 if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee, 608 OpRange.getBegin(), OpRange, 609 &BasePath)) 610 return; 611 612 Kind = CK_DerivedToBase; 613 614 // If we are casting to or through a virtual base class, we need a 615 // vtable. 616 if (Self.BasePathInvolvesVirtualBase(BasePath)) 617 Self.MarkVTableUsed(OpRange.getBegin(), 618 cast<CXXRecordDecl>(SrcRecord->getDecl())); 619 return; 620 } 621 622 // C++ 5.2.7p6: Otherwise, v shall be [polymorphic]. 623 const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition(); 624 assert(SrcDecl && "Definition missing"); 625 if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) { 626 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic) 627 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange(); 628 } 629 Self.MarkVTableUsed(OpRange.getBegin(), 630 cast<CXXRecordDecl>(SrcRecord->getDecl())); 631 632 // Done. Everything else is run-time checks. 633 Kind = CK_Dynamic; 634} 635 636/// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid. 637/// Refer to C++ 5.2.11 for details. const_cast is typically used in code 638/// like this: 639/// const char *str = "literal"; 640/// legacy_function(const_cast\<char*\>(str)); 641void CastOperation::CheckConstCast() { 642 if (ValueKind == VK_RValue) { 643 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 644 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 645 return; 646 } 647 648 unsigned msg = diag::err_bad_cxx_cast_generic; 649 if (TryConstCast(Self, SrcExpr.get(), DestType, /*CStyle*/false, msg) != TC_Success 650 && msg != 0) 651 Self.Diag(OpRange.getBegin(), msg) << CT_Const 652 << SrcExpr.get()->getType() << DestType << OpRange; 653} 654 655/// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is 656/// valid. 657/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code 658/// like this: 659/// char *bytes = reinterpret_cast\<char*\>(int_ptr); 660void CastOperation::CheckReinterpretCast() { 661 if (ValueKind == VK_RValue) { 662 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 663 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 664 return; 665 } 666 667 unsigned msg = diag::err_bad_cxx_cast_generic; 668 TryCastResult tcr = 669 TryReinterpretCast(Self, SrcExpr, DestType, 670 /*CStyle*/false, OpRange, msg, Kind); 671 if (tcr != TC_Success && msg != 0) 672 { 673 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 674 return; 675 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 676 //FIXME: &f<int>; is overloaded and resolvable 677 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload) 678 << OverloadExpr::find(SrcExpr.get()).Expression->getName() 679 << DestType << OpRange; 680 Self.NoteAllOverloadCandidates(SrcExpr.get()); 681 682 } else { 683 diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(), DestType); 684 } 685 } else if (tcr == TC_Success && Self.getLangOptions().ObjCAutoRefCount) { 686 checkObjCARCConversion(Sema::CCK_OtherCast); 687 } 688} 689 690 691/// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid. 692/// Refer to C++ 5.2.9 for details. Static casts are mostly used for making 693/// implicit conversions explicit and getting rid of data loss warnings. 694void CastOperation::CheckStaticCast() { 695 if (isPlaceholder()) { 696 checkNonOverloadPlaceholders(); 697 if (SrcExpr.isInvalid()) 698 return; 699 } 700 701 // This test is outside everything else because it's the only case where 702 // a non-lvalue-reference target type does not lead to decay. 703 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 704 if (DestType->isVoidType()) { 705 Kind = CK_ToVoid; 706 707 if (claimPlaceholder(BuiltinType::Overload)) { 708 ExprResult SingleFunctionExpression = 709 Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr.get(), 710 false, // Decay Function to ptr 711 true, // Complain 712 OpRange, DestType, diag::err_bad_static_cast_overload); 713 if (SingleFunctionExpression.isUsable()) 714 SrcExpr = SingleFunctionExpression; 715 } 716 717 SrcExpr = Self.IgnoredValueConversions(SrcExpr.take()); 718 return; 719 } 720 721 if (ValueKind == VK_RValue && !DestType->isRecordType()) { 722 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 723 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error 724 return; 725 } 726 727 unsigned msg = diag::err_bad_cxx_cast_generic; 728 TryCastResult tcr 729 = TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_OtherCast, OpRange, msg, 730 Kind, BasePath); 731 if (tcr != TC_Success && msg != 0) { 732 if (SrcExpr.isInvalid()) 733 return; 734 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 735 OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression; 736 Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload) 737 << oe->getName() << DestType << OpRange 738 << oe->getQualifierLoc().getSourceRange(); 739 Self.NoteAllOverloadCandidates(SrcExpr.get()); 740 } else { 741 diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType); 742 } 743 } else if (tcr == TC_Success) { 744 if (Kind == CK_BitCast) 745 checkCastAlign(); 746 if (Self.getLangOptions().ObjCAutoRefCount) 747 checkObjCARCConversion(Sema::CCK_OtherCast); 748 } else if (Kind == CK_BitCast) { 749 checkCastAlign(); 750 } 751} 752 753/// TryStaticCast - Check if a static cast can be performed, and do so if 754/// possible. If @p CStyle, ignore access restrictions on hierarchy casting 755/// and casting away constness. 756static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr, 757 QualType DestType, 758 Sema::CheckedConversionKind CCK, 759 const SourceRange &OpRange, unsigned &msg, 760 CastKind &Kind, 761 CXXCastPath &BasePath) { 762 // Determine whether we have the semantics of a C-style cast. 763 bool CStyle 764 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 765 766 // The order the tests is not entirely arbitrary. There is one conversion 767 // that can be handled in two different ways. Given: 768 // struct A {}; 769 // struct B : public A { 770 // B(); B(const A&); 771 // }; 772 // const A &a = B(); 773 // the cast static_cast<const B&>(a) could be seen as either a static 774 // reference downcast, or an explicit invocation of the user-defined 775 // conversion using B's conversion constructor. 776 // DR 427 specifies that the downcast is to be applied here. 777 778 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 779 // Done outside this function. 780 781 TryCastResult tcr; 782 783 // C++ 5.2.9p5, reference downcast. 784 // See the function for details. 785 // DR 427 specifies that this is to be applied before paragraph 2. 786 tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle, OpRange, 787 msg, Kind, BasePath); 788 if (tcr != TC_NotApplicable) 789 return tcr; 790 791 // C++0x [expr.static.cast]p3: 792 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2 793 // T2" if "cv2 T2" is reference-compatible with "cv1 T1". 794 tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind, BasePath, 795 msg); 796 if (tcr != TC_NotApplicable) 797 return tcr; 798 799 // C++ 5.2.9p2: An expression e can be explicitly converted to a type T 800 // [...] if the declaration "T t(e);" is well-formed, [...]. 801 tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg, 802 Kind); 803 if (SrcExpr.isInvalid()) 804 return TC_Failed; 805 if (tcr != TC_NotApplicable) 806 return tcr; 807 808 // C++ 5.2.9p6: May apply the reverse of any standard conversion, except 809 // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean 810 // conversions, subject to further restrictions. 811 // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal 812 // of qualification conversions impossible. 813 // In the CStyle case, the earlier attempt to const_cast should have taken 814 // care of reverse qualification conversions. 815 816 QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType()); 817 818 // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly 819 // converted to an integral type. [...] A value of a scoped enumeration type 820 // can also be explicitly converted to a floating-point type [...]. 821 if (const EnumType *Enum = SrcType->getAs<EnumType>()) { 822 if (Enum->getDecl()->isScoped()) { 823 if (DestType->isBooleanType()) { 824 Kind = CK_IntegralToBoolean; 825 return TC_Success; 826 } else if (DestType->isIntegralType(Self.Context)) { 827 Kind = CK_IntegralCast; 828 return TC_Success; 829 } else if (DestType->isRealFloatingType()) { 830 Kind = CK_IntegralToFloating; 831 return TC_Success; 832 } 833 } 834 } 835 836 // Reverse integral promotion/conversion. All such conversions are themselves 837 // again integral promotions or conversions and are thus already handled by 838 // p2 (TryDirectInitialization above). 839 // (Note: any data loss warnings should be suppressed.) 840 // The exception is the reverse of enum->integer, i.e. integer->enum (and 841 // enum->enum). See also C++ 5.2.9p7. 842 // The same goes for reverse floating point promotion/conversion and 843 // floating-integral conversions. Again, only floating->enum is relevant. 844 if (DestType->isEnumeralType()) { 845 if (SrcType->isIntegralOrEnumerationType()) { 846 Kind = CK_IntegralCast; 847 return TC_Success; 848 } else if (SrcType->isRealFloatingType()) { 849 Kind = CK_FloatingToIntegral; 850 return TC_Success; 851 } 852 } 853 854 // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast. 855 // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance. 856 tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg, 857 Kind, BasePath); 858 if (tcr != TC_NotApplicable) 859 return tcr; 860 861 // Reverse member pointer conversion. C++ 4.11 specifies member pointer 862 // conversion. C++ 5.2.9p9 has additional information. 863 // DR54's access restrictions apply here also. 864 tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle, 865 OpRange, msg, Kind, BasePath); 866 if (tcr != TC_NotApplicable) 867 return tcr; 868 869 // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to 870 // void*. C++ 5.2.9p10 specifies additional restrictions, which really is 871 // just the usual constness stuff. 872 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) { 873 QualType SrcPointee = SrcPointer->getPointeeType(); 874 if (SrcPointee->isVoidType()) { 875 if (const PointerType *DestPointer = DestType->getAs<PointerType>()) { 876 QualType DestPointee = DestPointer->getPointeeType(); 877 if (DestPointee->isIncompleteOrObjectType()) { 878 // This is definitely the intended conversion, but it might fail due 879 // to a qualifier violation. Note that we permit Objective-C lifetime 880 // and GC qualifier mismatches here. 881 if (!CStyle) { 882 Qualifiers DestPointeeQuals = DestPointee.getQualifiers(); 883 Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers(); 884 DestPointeeQuals.removeObjCGCAttr(); 885 DestPointeeQuals.removeObjCLifetime(); 886 SrcPointeeQuals.removeObjCGCAttr(); 887 SrcPointeeQuals.removeObjCLifetime(); 888 if (DestPointeeQuals != SrcPointeeQuals && 889 !DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) { 890 msg = diag::err_bad_cxx_cast_qualifiers_away; 891 return TC_Failed; 892 } 893 } 894 Kind = CK_BitCast; 895 return TC_Success; 896 } 897 } 898 else if (DestType->isObjCObjectPointerType()) { 899 // allow both c-style cast and static_cast of objective-c pointers as 900 // they are pervasive. 901 Kind = CK_CPointerToObjCPointerCast; 902 return TC_Success; 903 } 904 else if (CStyle && DestType->isBlockPointerType()) { 905 // allow c-style cast of void * to block pointers. 906 Kind = CK_AnyPointerToBlockPointerCast; 907 return TC_Success; 908 } 909 } 910 } 911 // Allow arbitray objective-c pointer conversion with static casts. 912 if (SrcType->isObjCObjectPointerType() && 913 DestType->isObjCObjectPointerType()) { 914 Kind = CK_BitCast; 915 return TC_Success; 916 } 917 918 // We tried everything. Everything! Nothing works! :-( 919 return TC_NotApplicable; 920} 921 922/// Tests whether a conversion according to N2844 is valid. 923TryCastResult 924TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType, 925 bool CStyle, CastKind &Kind, CXXCastPath &BasePath, 926 unsigned &msg) { 927 // C++0x [expr.static.cast]p3: 928 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to 929 // cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1". 930 const RValueReferenceType *R = DestType->getAs<RValueReferenceType>(); 931 if (!R) 932 return TC_NotApplicable; 933 934 if (!SrcExpr->isGLValue()) 935 return TC_NotApplicable; 936 937 // Because we try the reference downcast before this function, from now on 938 // this is the only cast possibility, so we issue an error if we fail now. 939 // FIXME: Should allow casting away constness if CStyle. 940 bool DerivedToBase; 941 bool ObjCConversion; 942 bool ObjCLifetimeConversion; 943 QualType FromType = SrcExpr->getType(); 944 QualType ToType = R->getPointeeType(); 945 if (CStyle) { 946 FromType = FromType.getUnqualifiedType(); 947 ToType = ToType.getUnqualifiedType(); 948 } 949 950 if (Self.CompareReferenceRelationship(SrcExpr->getLocStart(), 951 ToType, FromType, 952 DerivedToBase, ObjCConversion, 953 ObjCLifetimeConversion) 954 < Sema::Ref_Compatible_With_Added_Qualification) { 955 msg = diag::err_bad_lvalue_to_rvalue_cast; 956 return TC_Failed; 957 } 958 959 if (DerivedToBase) { 960 Kind = CK_DerivedToBase; 961 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 962 /*DetectVirtual=*/true); 963 if (!Self.IsDerivedFrom(SrcExpr->getType(), R->getPointeeType(), Paths)) 964 return TC_NotApplicable; 965 966 Self.BuildBasePathArray(Paths, BasePath); 967 } else 968 Kind = CK_NoOp; 969 970 return TC_Success; 971} 972 973/// Tests whether a conversion according to C++ 5.2.9p5 is valid. 974TryCastResult 975TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType, 976 bool CStyle, const SourceRange &OpRange, 977 unsigned &msg, CastKind &Kind, 978 CXXCastPath &BasePath) { 979 // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be 980 // cast to type "reference to cv2 D", where D is a class derived from B, 981 // if a valid standard conversion from "pointer to D" to "pointer to B" 982 // exists, cv2 >= cv1, and B is not a virtual base class of D. 983 // In addition, DR54 clarifies that the base must be accessible in the 984 // current context. Although the wording of DR54 only applies to the pointer 985 // variant of this rule, the intent is clearly for it to apply to the this 986 // conversion as well. 987 988 const ReferenceType *DestReference = DestType->getAs<ReferenceType>(); 989 if (!DestReference) { 990 return TC_NotApplicable; 991 } 992 bool RValueRef = DestReference->isRValueReferenceType(); 993 if (!RValueRef && !SrcExpr->isLValue()) { 994 // We know the left side is an lvalue reference, so we can suggest a reason. 995 msg = diag::err_bad_cxx_cast_rvalue; 996 return TC_NotApplicable; 997 } 998 999 QualType DestPointee = DestReference->getPointeeType(); 1000 1001 return TryStaticDowncast(Self, 1002 Self.Context.getCanonicalType(SrcExpr->getType()), 1003 Self.Context.getCanonicalType(DestPointee), CStyle, 1004 OpRange, SrcExpr->getType(), DestType, msg, Kind, 1005 BasePath); 1006} 1007 1008/// Tests whether a conversion according to C++ 5.2.9p8 is valid. 1009TryCastResult 1010TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType, 1011 bool CStyle, const SourceRange &OpRange, 1012 unsigned &msg, CastKind &Kind, 1013 CXXCastPath &BasePath) { 1014 // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class 1015 // type, can be converted to an rvalue of type "pointer to cv2 D", where D 1016 // is a class derived from B, if a valid standard conversion from "pointer 1017 // to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base 1018 // class of D. 1019 // In addition, DR54 clarifies that the base must be accessible in the 1020 // current context. 1021 1022 const PointerType *DestPointer = DestType->getAs<PointerType>(); 1023 if (!DestPointer) { 1024 return TC_NotApplicable; 1025 } 1026 1027 const PointerType *SrcPointer = SrcType->getAs<PointerType>(); 1028 if (!SrcPointer) { 1029 msg = diag::err_bad_static_cast_pointer_nonpointer; 1030 return TC_NotApplicable; 1031 } 1032 1033 return TryStaticDowncast(Self, 1034 Self.Context.getCanonicalType(SrcPointer->getPointeeType()), 1035 Self.Context.getCanonicalType(DestPointer->getPointeeType()), 1036 CStyle, OpRange, SrcType, DestType, msg, Kind, 1037 BasePath); 1038} 1039 1040/// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and 1041/// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to 1042/// DestType is possible and allowed. 1043TryCastResult 1044TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType, 1045 bool CStyle, const SourceRange &OpRange, QualType OrigSrcType, 1046 QualType OrigDestType, unsigned &msg, 1047 CastKind &Kind, CXXCastPath &BasePath) { 1048 // We can only work with complete types. But don't complain if it doesn't work 1049 if (Self.RequireCompleteType(OpRange.getBegin(), SrcType, Self.PDiag(0)) || 1050 Self.RequireCompleteType(OpRange.getBegin(), DestType, Self.PDiag(0))) 1051 return TC_NotApplicable; 1052 1053 // Downcast can only happen in class hierarchies, so we need classes. 1054 if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) { 1055 return TC_NotApplicable; 1056 } 1057 1058 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1059 /*DetectVirtual=*/true); 1060 if (!Self.IsDerivedFrom(DestType, SrcType, Paths)) { 1061 return TC_NotApplicable; 1062 } 1063 1064 // Target type does derive from source type. Now we're serious. If an error 1065 // appears now, it's not ignored. 1066 // This may not be entirely in line with the standard. Take for example: 1067 // struct A {}; 1068 // struct B : virtual A { 1069 // B(A&); 1070 // }; 1071 // 1072 // void f() 1073 // { 1074 // (void)static_cast<const B&>(*((A*)0)); 1075 // } 1076 // As far as the standard is concerned, p5 does not apply (A is virtual), so 1077 // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid. 1078 // However, both GCC and Comeau reject this example, and accepting it would 1079 // mean more complex code if we're to preserve the nice error message. 1080 // FIXME: Being 100% compliant here would be nice to have. 1081 1082 // Must preserve cv, as always, unless we're in C-style mode. 1083 if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) { 1084 msg = diag::err_bad_cxx_cast_qualifiers_away; 1085 return TC_Failed; 1086 } 1087 1088 if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) { 1089 // This code is analoguous to that in CheckDerivedToBaseConversion, except 1090 // that it builds the paths in reverse order. 1091 // To sum up: record all paths to the base and build a nice string from 1092 // them. Use it to spice up the error message. 1093 if (!Paths.isRecordingPaths()) { 1094 Paths.clear(); 1095 Paths.setRecordingPaths(true); 1096 Self.IsDerivedFrom(DestType, SrcType, Paths); 1097 } 1098 std::string PathDisplayStr; 1099 std::set<unsigned> DisplayedPaths; 1100 for (CXXBasePaths::paths_iterator PI = Paths.begin(), PE = Paths.end(); 1101 PI != PE; ++PI) { 1102 if (DisplayedPaths.insert(PI->back().SubobjectNumber).second) { 1103 // We haven't displayed a path to this particular base 1104 // class subobject yet. 1105 PathDisplayStr += "\n "; 1106 for (CXXBasePath::const_reverse_iterator EI = PI->rbegin(), 1107 EE = PI->rend(); 1108 EI != EE; ++EI) 1109 PathDisplayStr += EI->Base->getType().getAsString() + " -> "; 1110 PathDisplayStr += QualType(DestType).getAsString(); 1111 } 1112 } 1113 1114 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast) 1115 << QualType(SrcType).getUnqualifiedType() 1116 << QualType(DestType).getUnqualifiedType() 1117 << PathDisplayStr << OpRange; 1118 msg = 0; 1119 return TC_Failed; 1120 } 1121 1122 if (Paths.getDetectedVirtual() != 0) { 1123 QualType VirtualBase(Paths.getDetectedVirtual(), 0); 1124 Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual) 1125 << OrigSrcType << OrigDestType << VirtualBase << OpRange; 1126 msg = 0; 1127 return TC_Failed; 1128 } 1129 1130 if (!CStyle) { 1131 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1132 SrcType, DestType, 1133 Paths.front(), 1134 diag::err_downcast_from_inaccessible_base)) { 1135 case Sema::AR_accessible: 1136 case Sema::AR_delayed: // be optimistic 1137 case Sema::AR_dependent: // be optimistic 1138 break; 1139 1140 case Sema::AR_inaccessible: 1141 msg = 0; 1142 return TC_Failed; 1143 } 1144 } 1145 1146 Self.BuildBasePathArray(Paths, BasePath); 1147 Kind = CK_BaseToDerived; 1148 return TC_Success; 1149} 1150 1151/// TryStaticMemberPointerUpcast - Tests whether a conversion according to 1152/// C++ 5.2.9p9 is valid: 1153/// 1154/// An rvalue of type "pointer to member of D of type cv1 T" can be 1155/// converted to an rvalue of type "pointer to member of B of type cv2 T", 1156/// where B is a base class of D [...]. 1157/// 1158TryCastResult 1159TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType, 1160 QualType DestType, bool CStyle, 1161 const SourceRange &OpRange, 1162 unsigned &msg, CastKind &Kind, 1163 CXXCastPath &BasePath) { 1164 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(); 1165 if (!DestMemPtr) 1166 return TC_NotApplicable; 1167 1168 bool WasOverloadedFunction = false; 1169 DeclAccessPair FoundOverload; 1170 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 1171 if (FunctionDecl *Fn 1172 = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false, 1173 FoundOverload)) { 1174 CXXMethodDecl *M = cast<CXXMethodDecl>(Fn); 1175 SrcType = Self.Context.getMemberPointerType(Fn->getType(), 1176 Self.Context.getTypeDeclType(M->getParent()).getTypePtr()); 1177 WasOverloadedFunction = true; 1178 } 1179 } 1180 1181 const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 1182 if (!SrcMemPtr) { 1183 msg = diag::err_bad_static_cast_member_pointer_nonmp; 1184 return TC_NotApplicable; 1185 } 1186 1187 // T == T, modulo cv 1188 if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(), 1189 DestMemPtr->getPointeeType())) 1190 return TC_NotApplicable; 1191 1192 // B base of D 1193 QualType SrcClass(SrcMemPtr->getClass(), 0); 1194 QualType DestClass(DestMemPtr->getClass(), 0); 1195 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true, 1196 /*DetectVirtual=*/true); 1197 if (!Self.IsDerivedFrom(SrcClass, DestClass, Paths)) { 1198 return TC_NotApplicable; 1199 } 1200 1201 // B is a base of D. But is it an allowed base? If not, it's a hard error. 1202 if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) { 1203 Paths.clear(); 1204 Paths.setRecordingPaths(true); 1205 bool StillOkay = Self.IsDerivedFrom(SrcClass, DestClass, Paths); 1206 assert(StillOkay); 1207 (void)StillOkay; 1208 std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths); 1209 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv) 1210 << 1 << SrcClass << DestClass << PathDisplayStr << OpRange; 1211 msg = 0; 1212 return TC_Failed; 1213 } 1214 1215 if (const RecordType *VBase = Paths.getDetectedVirtual()) { 1216 Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual) 1217 << SrcClass << DestClass << QualType(VBase, 0) << OpRange; 1218 msg = 0; 1219 return TC_Failed; 1220 } 1221 1222 if (!CStyle) { 1223 switch (Self.CheckBaseClassAccess(OpRange.getBegin(), 1224 DestClass, SrcClass, 1225 Paths.front(), 1226 diag::err_upcast_to_inaccessible_base)) { 1227 case Sema::AR_accessible: 1228 case Sema::AR_delayed: 1229 case Sema::AR_dependent: 1230 // Optimistically assume that the delayed and dependent cases 1231 // will work out. 1232 break; 1233 1234 case Sema::AR_inaccessible: 1235 msg = 0; 1236 return TC_Failed; 1237 } 1238 } 1239 1240 if (WasOverloadedFunction) { 1241 // Resolve the address of the overloaded function again, this time 1242 // allowing complaints if something goes wrong. 1243 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 1244 DestType, 1245 true, 1246 FoundOverload); 1247 if (!Fn) { 1248 msg = 0; 1249 return TC_Failed; 1250 } 1251 1252 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn); 1253 if (!SrcExpr.isUsable()) { 1254 msg = 0; 1255 return TC_Failed; 1256 } 1257 } 1258 1259 Self.BuildBasePathArray(Paths, BasePath); 1260 Kind = CK_DerivedToBaseMemberPointer; 1261 return TC_Success; 1262} 1263 1264/// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2 1265/// is valid: 1266/// 1267/// An expression e can be explicitly converted to a type T using a 1268/// @c static_cast if the declaration "T t(e);" is well-formed [...]. 1269TryCastResult 1270TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType, 1271 Sema::CheckedConversionKind CCK, 1272 const SourceRange &OpRange, unsigned &msg, 1273 CastKind &Kind) { 1274 if (DestType->isRecordType()) { 1275 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 1276 diag::err_bad_dynamic_cast_incomplete)) { 1277 msg = 0; 1278 return TC_Failed; 1279 } 1280 } 1281 1282 InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType); 1283 InitializationKind InitKind 1284 = (CCK == Sema::CCK_CStyleCast) 1285 ? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange) 1286 : (CCK == Sema::CCK_FunctionalCast) 1287 ? InitializationKind::CreateFunctionalCast(OpRange) 1288 : InitializationKind::CreateCast(OpRange); 1289 Expr *SrcExprRaw = SrcExpr.get(); 1290 InitializationSequence InitSeq(Self, Entity, InitKind, &SrcExprRaw, 1); 1291 1292 // At this point of CheckStaticCast, if the destination is a reference, 1293 // or the expression is an overload expression this has to work. 1294 // There is no other way that works. 1295 // On the other hand, if we're checking a C-style cast, we've still got 1296 // the reinterpret_cast way. 1297 bool CStyle 1298 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast); 1299 if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType())) 1300 return TC_NotApplicable; 1301 1302 ExprResult Result 1303 = InitSeq.Perform(Self, Entity, InitKind, MultiExprArg(Self, &SrcExprRaw, 1)); 1304 if (Result.isInvalid()) { 1305 msg = 0; 1306 return TC_Failed; 1307 } 1308 1309 if (InitSeq.isConstructorInitialization()) 1310 Kind = CK_ConstructorConversion; 1311 else 1312 Kind = CK_NoOp; 1313 1314 SrcExpr = move(Result); 1315 return TC_Success; 1316} 1317 1318/// TryConstCast - See if a const_cast from source to destination is allowed, 1319/// and perform it if it is. 1320static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType, 1321 bool CStyle, unsigned &msg) { 1322 DestType = Self.Context.getCanonicalType(DestType); 1323 QualType SrcType = SrcExpr->getType(); 1324 if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) { 1325 if (DestTypeTmp->isLValueReferenceType() && !SrcExpr->isLValue()) { 1326 // Cannot const_cast non-lvalue to lvalue reference type. But if this 1327 // is C-style, static_cast might find a way, so we simply suggest a 1328 // message and tell the parent to keep searching. 1329 msg = diag::err_bad_cxx_cast_rvalue; 1330 return TC_NotApplicable; 1331 } 1332 1333 // C++ 5.2.11p4: An lvalue of type T1 can be [cast] to an lvalue of type T2 1334 // [...] if a pointer to T1 can be [cast] to the type pointer to T2. 1335 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 1336 SrcType = Self.Context.getPointerType(SrcType); 1337 } 1338 1339 // C++ 5.2.11p5: For a const_cast involving pointers to data members [...] 1340 // the rules for const_cast are the same as those used for pointers. 1341 1342 if (!DestType->isPointerType() && 1343 !DestType->isMemberPointerType() && 1344 !DestType->isObjCObjectPointerType()) { 1345 // Cannot cast to non-pointer, non-reference type. Note that, if DestType 1346 // was a reference type, we converted it to a pointer above. 1347 // The status of rvalue references isn't entirely clear, but it looks like 1348 // conversion to them is simply invalid. 1349 // C++ 5.2.11p3: For two pointer types [...] 1350 if (!CStyle) 1351 msg = diag::err_bad_const_cast_dest; 1352 return TC_NotApplicable; 1353 } 1354 if (DestType->isFunctionPointerType() || 1355 DestType->isMemberFunctionPointerType()) { 1356 // Cannot cast direct function pointers. 1357 // C++ 5.2.11p2: [...] where T is any object type or the void type [...] 1358 // T is the ultimate pointee of source and target type. 1359 if (!CStyle) 1360 msg = diag::err_bad_const_cast_dest; 1361 return TC_NotApplicable; 1362 } 1363 SrcType = Self.Context.getCanonicalType(SrcType); 1364 1365 // Unwrap the pointers. Ignore qualifiers. Terminate early if the types are 1366 // completely equal. 1367 // C++ 5.2.11p3 describes the core semantics of const_cast. All cv specifiers 1368 // in multi-level pointers may change, but the level count must be the same, 1369 // as must be the final pointee type. 1370 while (SrcType != DestType && 1371 Self.Context.UnwrapSimilarPointerTypes(SrcType, DestType)) { 1372 Qualifiers SrcQuals, DestQuals; 1373 SrcType = Self.Context.getUnqualifiedArrayType(SrcType, SrcQuals); 1374 DestType = Self.Context.getUnqualifiedArrayType(DestType, DestQuals); 1375 1376 // const_cast is permitted to strip cvr-qualifiers, only. Make sure that 1377 // the other qualifiers (e.g., address spaces) are identical. 1378 SrcQuals.removeCVRQualifiers(); 1379 DestQuals.removeCVRQualifiers(); 1380 if (SrcQuals != DestQuals) 1381 return TC_NotApplicable; 1382 } 1383 1384 // Since we're dealing in canonical types, the remainder must be the same. 1385 if (SrcType != DestType) 1386 return TC_NotApplicable; 1387 1388 return TC_Success; 1389} 1390 1391// Checks for undefined behavior in reinterpret_cast. 1392// The cases that is checked for is: 1393// *reinterpret_cast<T*>(&a) 1394// reinterpret_cast<T&>(a) 1395// where accessing 'a' as type 'T' will result in undefined behavior. 1396void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType, 1397 bool IsDereference, 1398 SourceRange Range) { 1399 unsigned DiagID = IsDereference ? 1400 diag::warn_pointer_indirection_from_incompatible_type : 1401 diag::warn_undefined_reinterpret_cast; 1402 1403 if (Diags.getDiagnosticLevel(DiagID, Range.getBegin()) == 1404 DiagnosticsEngine::Ignored) { 1405 return; 1406 } 1407 1408 QualType SrcTy, DestTy; 1409 if (IsDereference) { 1410 if (!SrcType->getAs<PointerType>() || !DestType->getAs<PointerType>()) { 1411 return; 1412 } 1413 SrcTy = SrcType->getPointeeType(); 1414 DestTy = DestType->getPointeeType(); 1415 } else { 1416 if (!DestType->getAs<ReferenceType>()) { 1417 return; 1418 } 1419 SrcTy = SrcType; 1420 DestTy = DestType->getPointeeType(); 1421 } 1422 1423 // Cast is compatible if the types are the same. 1424 if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) { 1425 return; 1426 } 1427 // or one of the types is a char or void type 1428 if (DestTy->isAnyCharacterType() || DestTy->isVoidType() || 1429 SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) { 1430 return; 1431 } 1432 // or one of the types is a tag type. 1433 if (SrcTy->getAs<TagType>() || DestTy->getAs<TagType>()) { 1434 return; 1435 } 1436 1437 // FIXME: Scoped enums? 1438 if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) || 1439 (SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) { 1440 if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) { 1441 return; 1442 } 1443 } 1444 1445 Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range; 1446} 1447 1448static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr, 1449 QualType DestType, bool CStyle, 1450 const SourceRange &OpRange, 1451 unsigned &msg, 1452 CastKind &Kind) { 1453 bool IsLValueCast = false; 1454 1455 DestType = Self.Context.getCanonicalType(DestType); 1456 QualType SrcType = SrcExpr.get()->getType(); 1457 1458 // Is the source an overloaded name? (i.e. &foo) 1459 // If so, reinterpret_cast can not help us here (13.4, p1, bullet 5) ... 1460 if (SrcType == Self.Context.OverloadTy) { 1461 // ... unless foo<int> resolves to an lvalue unambiguously 1462 ExprResult SingleFunctionExpr = 1463 Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr.get(), 1464 Expr::getValueKindForType(DestType) == VK_RValue // Convert Fun to Ptr 1465 ); 1466 if (SingleFunctionExpr.isUsable()) { 1467 SrcExpr = move(SingleFunctionExpr); 1468 SrcType = SrcExpr.get()->getType(); 1469 } 1470 else 1471 return TC_NotApplicable; 1472 } 1473 1474 if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) { 1475 bool LValue = DestTypeTmp->isLValueReferenceType(); 1476 if (LValue && !SrcExpr.get()->isLValue()) { 1477 // Cannot cast non-lvalue to lvalue reference type. See the similar 1478 // comment in const_cast. 1479 msg = diag::err_bad_cxx_cast_rvalue; 1480 return TC_NotApplicable; 1481 } 1482 1483 if (!CStyle) { 1484 Self.CheckCompatibleReinterpretCast(SrcType, DestType, 1485 /*isDereference=*/false, OpRange); 1486 } 1487 1488 // C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the 1489 // same effect as the conversion *reinterpret_cast<T*>(&x) with the 1490 // built-in & and * operators. 1491 1492 const char *inappropriate = 0; 1493 switch (SrcExpr.get()->getObjectKind()) { 1494 case OK_Ordinary: 1495 break; 1496 case OK_BitField: inappropriate = "bit-field"; break; 1497 case OK_VectorComponent: inappropriate = "vector element"; break; 1498 case OK_ObjCProperty: inappropriate = "property expression"; break; 1499 } 1500 if (inappropriate) { 1501 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference) 1502 << inappropriate << DestType 1503 << OpRange << SrcExpr.get()->getSourceRange(); 1504 msg = 0; SrcExpr = ExprError(); 1505 return TC_NotApplicable; 1506 } 1507 1508 // This code does this transformation for the checked types. 1509 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType()); 1510 SrcType = Self.Context.getPointerType(SrcType); 1511 1512 IsLValueCast = true; 1513 } 1514 1515 // Canonicalize source for comparison. 1516 SrcType = Self.Context.getCanonicalType(SrcType); 1517 1518 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(), 1519 *SrcMemPtr = SrcType->getAs<MemberPointerType>(); 1520 if (DestMemPtr && SrcMemPtr) { 1521 // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1" 1522 // can be explicitly converted to an rvalue of type "pointer to member 1523 // of Y of type T2" if T1 and T2 are both function types or both object 1524 // types. 1525 if (DestMemPtr->getPointeeType()->isFunctionType() != 1526 SrcMemPtr->getPointeeType()->isFunctionType()) 1527 return TC_NotApplicable; 1528 1529 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away 1530 // constness. 1531 // A reinterpret_cast followed by a const_cast can, though, so in C-style, 1532 // we accept it. 1533 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, 1534 /*CheckObjCLifetime=*/CStyle)) { 1535 msg = diag::err_bad_cxx_cast_qualifiers_away; 1536 return TC_Failed; 1537 } 1538 1539 // Don't allow casting between member pointers of different sizes. 1540 if (Self.Context.getTypeSize(DestMemPtr) != 1541 Self.Context.getTypeSize(SrcMemPtr)) { 1542 msg = diag::err_bad_cxx_cast_member_pointer_size; 1543 return TC_Failed; 1544 } 1545 1546 // A valid member pointer cast. 1547 Kind = IsLValueCast? CK_LValueBitCast : CK_BitCast; 1548 return TC_Success; 1549 } 1550 1551 // See below for the enumeral issue. 1552 if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) { 1553 // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral 1554 // type large enough to hold it. A value of std::nullptr_t can be 1555 // converted to an integral type; the conversion has the same meaning 1556 // and validity as a conversion of (void*)0 to the integral type. 1557 if (Self.Context.getTypeSize(SrcType) > 1558 Self.Context.getTypeSize(DestType)) { 1559 msg = diag::err_bad_reinterpret_cast_small_int; 1560 return TC_Failed; 1561 } 1562 Kind = CK_PointerToIntegral; 1563 return TC_Success; 1564 } 1565 1566 bool destIsVector = DestType->isVectorType(); 1567 bool srcIsVector = SrcType->isVectorType(); 1568 if (srcIsVector || destIsVector) { 1569 // FIXME: Should this also apply to floating point types? 1570 bool srcIsScalar = SrcType->isIntegralType(Self.Context); 1571 bool destIsScalar = DestType->isIntegralType(Self.Context); 1572 1573 // Check if this is a cast between a vector and something else. 1574 if (!(srcIsScalar && destIsVector) && !(srcIsVector && destIsScalar) && 1575 !(srcIsVector && destIsVector)) 1576 return TC_NotApplicable; 1577 1578 // If both types have the same size, we can successfully cast. 1579 if (Self.Context.getTypeSize(SrcType) 1580 == Self.Context.getTypeSize(DestType)) { 1581 Kind = CK_BitCast; 1582 return TC_Success; 1583 } 1584 1585 if (destIsScalar) 1586 msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size; 1587 else if (srcIsScalar) 1588 msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size; 1589 else 1590 msg = diag::err_bad_cxx_cast_vector_to_vector_different_size; 1591 1592 return TC_Failed; 1593 } 1594 1595 bool destIsPtr = DestType->isAnyPointerType() || 1596 DestType->isBlockPointerType(); 1597 bool srcIsPtr = SrcType->isAnyPointerType() || 1598 SrcType->isBlockPointerType(); 1599 if (!destIsPtr && !srcIsPtr) { 1600 // Except for std::nullptr_t->integer and lvalue->reference, which are 1601 // handled above, at least one of the two arguments must be a pointer. 1602 return TC_NotApplicable; 1603 } 1604 1605 if (SrcType == DestType) { 1606 // C++ 5.2.10p2 has a note that mentions that, subject to all other 1607 // restrictions, a cast to the same type is allowed. The intent is not 1608 // entirely clear here, since all other paragraphs explicitly forbid casts 1609 // to the same type. However, the behavior of compilers is pretty consistent 1610 // on this point: allow same-type conversion if the involved types are 1611 // pointers, disallow otherwise. 1612 Kind = CK_NoOp; 1613 return TC_Success; 1614 } 1615 1616 if (DestType->isIntegralType(Self.Context)) { 1617 assert(srcIsPtr && "One type must be a pointer"); 1618 // C++ 5.2.10p4: A pointer can be explicitly converted to any integral 1619 // type large enough to hold it; except in Microsoft mode, where the 1620 // integral type size doesn't matter. 1621 if ((Self.Context.getTypeSize(SrcType) > 1622 Self.Context.getTypeSize(DestType)) && 1623 !Self.getLangOptions().MicrosoftExt) { 1624 msg = diag::err_bad_reinterpret_cast_small_int; 1625 return TC_Failed; 1626 } 1627 Kind = CK_PointerToIntegral; 1628 return TC_Success; 1629 } 1630 1631 if (SrcType->isIntegralOrEnumerationType()) { 1632 assert(destIsPtr && "One type must be a pointer"); 1633 // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly 1634 // converted to a pointer. 1635 // C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not 1636 // necessarily converted to a null pointer value.] 1637 Kind = CK_IntegralToPointer; 1638 return TC_Success; 1639 } 1640 1641 if (!destIsPtr || !srcIsPtr) { 1642 // With the valid non-pointer conversions out of the way, we can be even 1643 // more stringent. 1644 return TC_NotApplicable; 1645 } 1646 1647 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness. 1648 // The C-style cast operator can. 1649 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle, 1650 /*CheckObjCLifetime=*/CStyle)) { 1651 msg = diag::err_bad_cxx_cast_qualifiers_away; 1652 return TC_Failed; 1653 } 1654 1655 // Cannot convert between block pointers and Objective-C object pointers. 1656 if ((SrcType->isBlockPointerType() && DestType->isObjCObjectPointerType()) || 1657 (DestType->isBlockPointerType() && SrcType->isObjCObjectPointerType())) 1658 return TC_NotApplicable; 1659 1660 if (IsLValueCast) { 1661 Kind = CK_LValueBitCast; 1662 } else if (DestType->isObjCObjectPointerType()) { 1663 Kind = Self.PrepareCastToObjCObjectPointer(SrcExpr); 1664 } else if (DestType->isBlockPointerType()) { 1665 if (!SrcType->isBlockPointerType()) { 1666 Kind = CK_AnyPointerToBlockPointerCast; 1667 } else { 1668 Kind = CK_BitCast; 1669 } 1670 } else { 1671 Kind = CK_BitCast; 1672 } 1673 1674 // Any pointer can be cast to an Objective-C pointer type with a C-style 1675 // cast. 1676 if (CStyle && DestType->isObjCObjectPointerType()) { 1677 return TC_Success; 1678 } 1679 1680 // Not casting away constness, so the only remaining check is for compatible 1681 // pointer categories. 1682 1683 if (SrcType->isFunctionPointerType()) { 1684 if (DestType->isFunctionPointerType()) { 1685 // C++ 5.2.10p6: A pointer to a function can be explicitly converted to 1686 // a pointer to a function of a different type. 1687 return TC_Success; 1688 } 1689 1690 // C++0x 5.2.10p8: Converting a pointer to a function into a pointer to 1691 // an object type or vice versa is conditionally-supported. 1692 // Compilers support it in C++03 too, though, because it's necessary for 1693 // casting the return value of dlsym() and GetProcAddress(). 1694 // FIXME: Conditionally-supported behavior should be configurable in the 1695 // TargetInfo or similar. 1696 if (!Self.getLangOptions().CPlusPlus0x) 1697 Self.Diag(OpRange.getBegin(), diag::ext_cast_fn_obj) << OpRange; 1698 return TC_Success; 1699 } 1700 1701 if (DestType->isFunctionPointerType()) { 1702 // See above. 1703 if (!Self.getLangOptions().CPlusPlus0x) 1704 Self.Diag(OpRange.getBegin(), diag::ext_cast_fn_obj) << OpRange; 1705 return TC_Success; 1706 } 1707 1708 // C++ 5.2.10p7: A pointer to an object can be explicitly converted to 1709 // a pointer to an object of different type. 1710 // Void pointers are not specified, but supported by every compiler out there. 1711 // So we finish by allowing everything that remains - it's got to be two 1712 // object pointers. 1713 return TC_Success; 1714} 1715 1716void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle) { 1717 // Handle placeholders. 1718 if (isPlaceholder()) { 1719 // C-style casts can resolve __unknown_any types. 1720 if (claimPlaceholder(BuiltinType::UnknownAny)) { 1721 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 1722 SrcExpr.get(), Kind, 1723 ValueKind, BasePath); 1724 return; 1725 } 1726 1727 checkNonOverloadPlaceholders(); 1728 if (SrcExpr.isInvalid()) 1729 return; 1730 } 1731 1732 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void". 1733 // This test is outside everything else because it's the only case where 1734 // a non-lvalue-reference target type does not lead to decay. 1735 if (DestType->isVoidType()) { 1736 Kind = CK_ToVoid; 1737 1738 if (claimPlaceholder(BuiltinType::Overload)) { 1739 SrcExpr = Self.ResolveAndFixSingleFunctionTemplateSpecialization( 1740 SrcExpr.take(), /* Decay Function to ptr */ false, 1741 /* Complain */ true, DestRange, DestType, 1742 diag::err_bad_cstyle_cast_overload); 1743 if (SrcExpr.isInvalid()) 1744 return; 1745 } 1746 1747 SrcExpr = Self.IgnoredValueConversions(SrcExpr.take()); 1748 if (SrcExpr.isInvalid()) 1749 return; 1750 1751 return; 1752 } 1753 1754 // If the type is dependent, we won't do any other semantic analysis now. 1755 if (DestType->isDependentType() || SrcExpr.get()->isTypeDependent()) { 1756 assert(Kind == CK_Dependent); 1757 return; 1758 } 1759 1760 if (ValueKind == VK_RValue && !DestType->isRecordType()) { 1761 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 1762 if (SrcExpr.isInvalid()) 1763 return; 1764 } 1765 1766 // AltiVec vector initialization with a single literal. 1767 if (const VectorType *vecTy = DestType->getAs<VectorType>()) 1768 if (vecTy->getVectorKind() == VectorType::AltiVecVector 1769 && (SrcExpr.get()->getType()->isIntegerType() 1770 || SrcExpr.get()->getType()->isFloatingType())) { 1771 Kind = CK_VectorSplat; 1772 return; 1773 } 1774 1775 // C++ [expr.cast]p5: The conversions performed by 1776 // - a const_cast, 1777 // - a static_cast, 1778 // - a static_cast followed by a const_cast, 1779 // - a reinterpret_cast, or 1780 // - a reinterpret_cast followed by a const_cast, 1781 // can be performed using the cast notation of explicit type conversion. 1782 // [...] If a conversion can be interpreted in more than one of the ways 1783 // listed above, the interpretation that appears first in the list is used, 1784 // even if a cast resulting from that interpretation is ill-formed. 1785 // In plain language, this means trying a const_cast ... 1786 unsigned msg = diag::err_bad_cxx_cast_generic; 1787 TryCastResult tcr = TryConstCast(Self, SrcExpr.get(), DestType, 1788 /*CStyle*/true, msg); 1789 if (tcr == TC_Success) 1790 Kind = CK_NoOp; 1791 1792 Sema::CheckedConversionKind CCK 1793 = FunctionalStyle? Sema::CCK_FunctionalCast 1794 : Sema::CCK_CStyleCast; 1795 if (tcr == TC_NotApplicable) { 1796 // ... or if that is not possible, a static_cast, ignoring const, ... 1797 tcr = TryStaticCast(Self, SrcExpr, DestType, CCK, OpRange, 1798 msg, Kind, BasePath); 1799 if (SrcExpr.isInvalid()) 1800 return; 1801 1802 if (tcr == TC_NotApplicable) { 1803 // ... and finally a reinterpret_cast, ignoring const. 1804 tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/true, 1805 OpRange, msg, Kind); 1806 if (SrcExpr.isInvalid()) 1807 return; 1808 } 1809 } 1810 1811 if (Self.getLangOptions().ObjCAutoRefCount && tcr == TC_Success) 1812 checkObjCARCConversion(CCK); 1813 1814 if (tcr != TC_Success && msg != 0) { 1815 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) { 1816 DeclAccessPair Found; 1817 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), 1818 DestType, 1819 /*Complain*/ true, 1820 Found); 1821 1822 assert(!Fn && "cast failed but able to resolve overload expression!!"); 1823 (void)Fn; 1824 1825 } else { 1826 diagnoseBadCast(Self, msg, (FunctionalStyle ? CT_Functional : CT_CStyle), 1827 OpRange, SrcExpr.get(), DestType); 1828 } 1829 } else if (Kind == CK_BitCast) { 1830 checkCastAlign(); 1831 } 1832 1833 // Clear out SrcExpr if there was a fatal error. 1834 if (tcr != TC_Success) 1835 SrcExpr = ExprError(); 1836} 1837 1838/// Check the semantics of a C-style cast operation, in C. 1839void CastOperation::CheckCStyleCast() { 1840 assert(!Self.getLangOptions().CPlusPlus); 1841 1842 // Handle placeholders. 1843 if (isPlaceholder()) { 1844 // C-style casts can resolve __unknown_any types. 1845 if (claimPlaceholder(BuiltinType::UnknownAny)) { 1846 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType, 1847 SrcExpr.get(), Kind, 1848 ValueKind, BasePath); 1849 return; 1850 } 1851 1852 checkNonOverloadPlaceholders(); 1853 if (SrcExpr.isInvalid()) 1854 return; 1855 } 1856 1857 assert(!isPlaceholder()); 1858 1859 // C99 6.5.4p2: the cast type needs to be void or scalar and the expression 1860 // type needs to be scalar. 1861 if (DestType->isVoidType()) { 1862 // We don't necessarily do lvalue-to-rvalue conversions on this. 1863 SrcExpr = Self.IgnoredValueConversions(SrcExpr.take()); 1864 if (SrcExpr.isInvalid()) 1865 return; 1866 1867 // Cast to void allows any expr type. 1868 Kind = CK_ToVoid; 1869 return; 1870 } 1871 1872 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.take()); 1873 if (SrcExpr.isInvalid()) 1874 return; 1875 QualType SrcType = SrcExpr.get()->getType(); 1876 1877 if (Self.RequireCompleteType(OpRange.getBegin(), DestType, 1878 diag::err_typecheck_cast_to_incomplete)) { 1879 SrcExpr = ExprError(); 1880 return; 1881 } 1882 1883 if (!DestType->isScalarType() && !DestType->isVectorType()) { 1884 const RecordType *DestRecordTy = DestType->getAs<RecordType>(); 1885 1886 if (DestRecordTy && Self.Context.hasSameUnqualifiedType(DestType, SrcType)){ 1887 // GCC struct/union extension: allow cast to self. 1888 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_nonscalar) 1889 << DestType << SrcExpr.get()->getSourceRange(); 1890 Kind = CK_NoOp; 1891 return; 1892 } 1893 1894 // GCC's cast to union extension. 1895 if (DestRecordTy && DestRecordTy->getDecl()->isUnion()) { 1896 RecordDecl *RD = DestRecordTy->getDecl(); 1897 RecordDecl::field_iterator Field, FieldEnd; 1898 for (Field = RD->field_begin(), FieldEnd = RD->field_end(); 1899 Field != FieldEnd; ++Field) { 1900 if (Self.Context.hasSameUnqualifiedType(Field->getType(), SrcType) && 1901 !Field->isUnnamedBitfield()) { 1902 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union) 1903 << SrcExpr.get()->getSourceRange(); 1904 break; 1905 } 1906 } 1907 if (Field == FieldEnd) { 1908 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cast_to_union_no_type) 1909 << SrcType << SrcExpr.get()->getSourceRange(); 1910 SrcExpr = ExprError(); 1911 return; 1912 } 1913 Kind = CK_ToUnion; 1914 return; 1915 } 1916 1917 // Reject any other conversions to non-scalar types. 1918 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cond_expect_scalar) 1919 << DestType << SrcExpr.get()->getSourceRange(); 1920 SrcExpr = ExprError(); 1921 return; 1922 } 1923 1924 // The type we're casting to is known to be a scalar or vector. 1925 1926 // Require the operand to be a scalar or vector. 1927 if (!SrcType->isScalarType() && !SrcType->isVectorType()) { 1928 Self.Diag(SrcExpr.get()->getExprLoc(), 1929 diag::err_typecheck_expect_scalar_operand) 1930 << SrcType << SrcExpr.get()->getSourceRange(); 1931 SrcExpr = ExprError(); 1932 return; 1933 } 1934 1935 if (DestType->isExtVectorType()) { 1936 SrcExpr = Self.CheckExtVectorCast(OpRange, DestType, SrcExpr.take(), Kind); 1937 return; 1938 } 1939 1940 if (const VectorType *DestVecTy = DestType->getAs<VectorType>()) { 1941 if (DestVecTy->getVectorKind() == VectorType::AltiVecVector && 1942 (SrcType->isIntegerType() || SrcType->isFloatingType())) { 1943 Kind = CK_VectorSplat; 1944 } else if (Self.CheckVectorCast(OpRange, DestType, SrcType, Kind)) { 1945 SrcExpr = ExprError(); 1946 } 1947 return; 1948 } 1949 1950 if (SrcType->isVectorType()) { 1951 if (Self.CheckVectorCast(OpRange, SrcType, DestType, Kind)) 1952 SrcExpr = ExprError(); 1953 return; 1954 } 1955 1956 // The source and target types are both scalars, i.e. 1957 // - arithmetic types (fundamental, enum, and complex) 1958 // - all kinds of pointers 1959 // Note that member pointers were filtered out with C++, above. 1960 1961 if (isa<ObjCSelectorExpr>(SrcExpr.get())) { 1962 Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_selector_expr); 1963 SrcExpr = ExprError(); 1964 return; 1965 } 1966 1967 // If either type is a pointer, the other type has to be either an 1968 // integer or a pointer. 1969 if (!DestType->isArithmeticType()) { 1970 if (!SrcType->isIntegralType(Self.Context) && SrcType->isArithmeticType()) { 1971 Self.Diag(SrcExpr.get()->getExprLoc(), 1972 diag::err_cast_pointer_from_non_pointer_int) 1973 << SrcType << SrcExpr.get()->getSourceRange(); 1974 SrcExpr = ExprError(); 1975 return; 1976 } 1977 } else if (!SrcType->isArithmeticType()) { 1978 if (!DestType->isIntegralType(Self.Context) && 1979 DestType->isArithmeticType()) { 1980 Self.Diag(SrcExpr.get()->getLocStart(), 1981 diag::err_cast_pointer_to_non_pointer_int) 1982 << SrcType << SrcExpr.get()->getSourceRange(); 1983 SrcExpr = ExprError(); 1984 return; 1985 } 1986 } 1987 1988 // ARC imposes extra restrictions on casts. 1989 if (Self.getLangOptions().ObjCAutoRefCount) { 1990 checkObjCARCConversion(Sema::CCK_CStyleCast); 1991 if (SrcExpr.isInvalid()) 1992 return; 1993 1994 if (const PointerType *CastPtr = DestType->getAs<PointerType>()) { 1995 if (const PointerType *ExprPtr = SrcType->getAs<PointerType>()) { 1996 Qualifiers CastQuals = CastPtr->getPointeeType().getQualifiers(); 1997 Qualifiers ExprQuals = ExprPtr->getPointeeType().getQualifiers(); 1998 if (CastPtr->getPointeeType()->isObjCLifetimeType() && 1999 ExprPtr->getPointeeType()->isObjCLifetimeType() && 2000 !CastQuals.compatiblyIncludesObjCLifetime(ExprQuals)) { 2001 Self.Diag(SrcExpr.get()->getLocStart(), 2002 diag::err_typecheck_incompatible_ownership) 2003 << SrcType << DestType << Sema::AA_Casting 2004 << SrcExpr.get()->getSourceRange(); 2005 return; 2006 } 2007 } 2008 } 2009 else if (!Self.CheckObjCARCUnavailableWeakConversion(DestType, SrcType)) { 2010 Self.Diag(SrcExpr.get()->getLocStart(), 2011 diag::err_arc_convesion_of_weak_unavailable) 2012 << 1 << SrcType << DestType << SrcExpr.get()->getSourceRange(); 2013 SrcExpr = ExprError(); 2014 return; 2015 } 2016 } 2017 2018 Kind = Self.PrepareScalarCast(SrcExpr, DestType); 2019 if (SrcExpr.isInvalid()) 2020 return; 2021 2022 if (Kind == CK_BitCast) 2023 checkCastAlign(); 2024} 2025 2026ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc, 2027 TypeSourceInfo *CastTypeInfo, 2028 SourceLocation RPLoc, 2029 Expr *CastExpr) { 2030 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr); 2031 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2032 Op.OpRange = SourceRange(LPLoc, CastExpr->getLocEnd()); 2033 2034 if (getLangOptions().CPlusPlus) { 2035 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/ false); 2036 } else { 2037 Op.CheckCStyleCast(); 2038 } 2039 2040 if (Op.SrcExpr.isInvalid()) 2041 return ExprError(); 2042 2043 return Owned(CStyleCastExpr::Create(Context, Op.ResultType, Op.ValueKind, 2044 Op.Kind, Op.SrcExpr.take(), &Op.BasePath, 2045 CastTypeInfo, LPLoc, RPLoc)); 2046} 2047 2048ExprResult Sema::BuildCXXFunctionalCastExpr(TypeSourceInfo *CastTypeInfo, 2049 SourceLocation LPLoc, 2050 Expr *CastExpr, 2051 SourceLocation RPLoc) { 2052 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr); 2053 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange(); 2054 Op.OpRange = SourceRange(Op.DestRange.getBegin(), CastExpr->getLocEnd()); 2055 2056 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/ true); 2057 if (Op.SrcExpr.isInvalid()) 2058 return ExprError(); 2059 2060 return Owned(CXXFunctionalCastExpr::Create(Context, Op.ResultType, 2061 Op.ValueKind, CastTypeInfo, 2062 Op.DestRange.getBegin(), 2063 Op.Kind, Op.SrcExpr.take(), 2064 &Op.BasePath, RPLoc)); 2065} 2066