1 //===--- SemaCast.cpp - Semantic Analysis for Casts -----------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements semantic analysis for cast expressions, including
11 // 1) C-style casts like '(int) x'
12 // 2) C++ functional casts like 'int(x)'
13 // 3) C++ named casts like 'static_cast<int>(x)'
14 //
15 //===----------------------------------------------------------------------===//
16
17 #include "clang/Sema/SemaInternal.h"
18 #include "clang/AST/ASTContext.h"
19 #include "clang/AST/CXXInheritance.h"
20 #include "clang/AST/ExprCXX.h"
21 #include "clang/AST/ExprObjC.h"
22 #include "clang/AST/RecordLayout.h"
23 #include "clang/Basic/PartialDiagnostic.h"
24 #include "clang/Basic/TargetInfo.h"
25 #include "clang/Sema/Initialization.h"
26 #include "llvm/ADT/SmallVector.h"
27 #include <set>
28 using namespace clang;
29
30
31
32 enum TryCastResult {
33 TC_NotApplicable, ///< The cast method is not applicable.
34 TC_Success, ///< The cast method is appropriate and successful.
35 TC_Failed ///< The cast method is appropriate, but failed. A
36 ///< diagnostic has been emitted.
37 };
38
39 enum CastType {
40 CT_Const, ///< const_cast
41 CT_Static, ///< static_cast
42 CT_Reinterpret, ///< reinterpret_cast
43 CT_Dynamic, ///< dynamic_cast
44 CT_CStyle, ///< (Type)expr
45 CT_Functional ///< Type(expr)
46 };
47
48 namespace {
49 struct CastOperation {
CastOperation__anonbb0500620111::CastOperation50 CastOperation(Sema &S, QualType destType, ExprResult src)
51 : Self(S), SrcExpr(src), DestType(destType),
52 ResultType(destType.getNonLValueExprType(S.Context)),
53 ValueKind(Expr::getValueKindForType(destType)),
54 Kind(CK_Dependent), IsARCUnbridgedCast(false) {
55
56 if (const BuiltinType *placeholder =
57 src.get()->getType()->getAsPlaceholderType()) {
58 PlaceholderKind = placeholder->getKind();
59 } else {
60 PlaceholderKind = (BuiltinType::Kind) 0;
61 }
62 }
63
64 Sema &Self;
65 ExprResult SrcExpr;
66 QualType DestType;
67 QualType ResultType;
68 ExprValueKind ValueKind;
69 CastKind Kind;
70 BuiltinType::Kind PlaceholderKind;
71 CXXCastPath BasePath;
72 bool IsARCUnbridgedCast;
73
74 SourceRange OpRange;
75 SourceRange DestRange;
76
77 // Top-level semantics-checking routines.
78 void CheckConstCast();
79 void CheckReinterpretCast();
80 void CheckStaticCast();
81 void CheckDynamicCast();
82 void CheckCXXCStyleCast(bool FunctionalCast, bool ListInitialization);
83 void CheckCStyleCast();
84
85 /// Complete an apparently-successful cast operation that yields
86 /// the given expression.
complete__anonbb0500620111::CastOperation87 ExprResult complete(CastExpr *castExpr) {
88 // If this is an unbridged cast, wrap the result in an implicit
89 // cast that yields the unbridged-cast placeholder type.
90 if (IsARCUnbridgedCast) {
91 castExpr = ImplicitCastExpr::Create(Self.Context,
92 Self.Context.ARCUnbridgedCastTy,
93 CK_Dependent, castExpr, nullptr,
94 castExpr->getValueKind());
95 }
96 return castExpr;
97 }
98
99 // Internal convenience methods.
100
101 /// Try to handle the given placeholder expression kind. Return
102 /// true if the source expression has the appropriate placeholder
103 /// kind. A placeholder can only be claimed once.
claimPlaceholder__anonbb0500620111::CastOperation104 bool claimPlaceholder(BuiltinType::Kind K) {
105 if (PlaceholderKind != K) return false;
106
107 PlaceholderKind = (BuiltinType::Kind) 0;
108 return true;
109 }
110
isPlaceholder__anonbb0500620111::CastOperation111 bool isPlaceholder() const {
112 return PlaceholderKind != 0;
113 }
isPlaceholder__anonbb0500620111::CastOperation114 bool isPlaceholder(BuiltinType::Kind K) const {
115 return PlaceholderKind == K;
116 }
117
checkCastAlign__anonbb0500620111::CastOperation118 void checkCastAlign() {
119 Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange);
120 }
121
checkObjCARCConversion__anonbb0500620111::CastOperation122 void checkObjCARCConversion(Sema::CheckedConversionKind CCK) {
123 assert(Self.getLangOpts().ObjCAutoRefCount);
124
125 Expr *src = SrcExpr.get();
126 if (Self.CheckObjCARCConversion(OpRange, DestType, src, CCK) ==
127 Sema::ACR_unbridged)
128 IsARCUnbridgedCast = true;
129 SrcExpr = src;
130 }
131
132 /// Check for and handle non-overload placeholder expressions.
checkNonOverloadPlaceholders__anonbb0500620111::CastOperation133 void checkNonOverloadPlaceholders() {
134 if (!isPlaceholder() || isPlaceholder(BuiltinType::Overload))
135 return;
136
137 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
138 if (SrcExpr.isInvalid())
139 return;
140 PlaceholderKind = (BuiltinType::Kind) 0;
141 }
142 };
143 }
144
145 // The Try functions attempt a specific way of casting. If they succeed, they
146 // return TC_Success. If their way of casting is not appropriate for the given
147 // arguments, they return TC_NotApplicable and *may* set diag to a diagnostic
148 // to emit if no other way succeeds. If their way of casting is appropriate but
149 // fails, they return TC_Failed and *must* set diag; they can set it to 0 if
150 // they emit a specialized diagnostic.
151 // All diagnostics returned by these functions must expect the same three
152 // arguments:
153 // %0: Cast Type (a value from the CastType enumeration)
154 // %1: Source Type
155 // %2: Destination Type
156 static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr,
157 QualType DestType, bool CStyle,
158 CastKind &Kind,
159 CXXCastPath &BasePath,
160 unsigned &msg);
161 static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr,
162 QualType DestType, bool CStyle,
163 SourceRange OpRange,
164 unsigned &msg,
165 CastKind &Kind,
166 CXXCastPath &BasePath);
167 static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType,
168 QualType DestType, bool CStyle,
169 SourceRange OpRange,
170 unsigned &msg,
171 CastKind &Kind,
172 CXXCastPath &BasePath);
173 static TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType,
174 CanQualType DestType, bool CStyle,
175 SourceRange OpRange,
176 QualType OrigSrcType,
177 QualType OrigDestType, unsigned &msg,
178 CastKind &Kind,
179 CXXCastPath &BasePath);
180 static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr,
181 QualType SrcType,
182 QualType DestType,bool CStyle,
183 SourceRange OpRange,
184 unsigned &msg,
185 CastKind &Kind,
186 CXXCastPath &BasePath);
187
188 static TryCastResult TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr,
189 QualType DestType,
190 Sema::CheckedConversionKind CCK,
191 SourceRange OpRange,
192 unsigned &msg, CastKind &Kind,
193 bool ListInitialization);
194 static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
195 QualType DestType,
196 Sema::CheckedConversionKind CCK,
197 SourceRange OpRange,
198 unsigned &msg, CastKind &Kind,
199 CXXCastPath &BasePath,
200 bool ListInitialization);
201 static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr,
202 QualType DestType, bool CStyle,
203 unsigned &msg);
204 static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
205 QualType DestType, bool CStyle,
206 SourceRange OpRange,
207 unsigned &msg,
208 CastKind &Kind);
209
210
211 /// ActOnCXXNamedCast - Parse {dynamic,static,reinterpret,const}_cast's.
212 ExprResult
ActOnCXXNamedCast(SourceLocation OpLoc,tok::TokenKind Kind,SourceLocation LAngleBracketLoc,Declarator & D,SourceLocation RAngleBracketLoc,SourceLocation LParenLoc,Expr * E,SourceLocation RParenLoc)213 Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
214 SourceLocation LAngleBracketLoc, Declarator &D,
215 SourceLocation RAngleBracketLoc,
216 SourceLocation LParenLoc, Expr *E,
217 SourceLocation RParenLoc) {
218
219 assert(!D.isInvalidType());
220
221 TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, E->getType());
222 if (D.isInvalidType())
223 return ExprError();
224
225 if (getLangOpts().CPlusPlus) {
226 // Check that there are no default arguments (C++ only).
227 CheckExtraCXXDefaultArguments(D);
228 }
229
230 return BuildCXXNamedCast(OpLoc, Kind, TInfo, E,
231 SourceRange(LAngleBracketLoc, RAngleBracketLoc),
232 SourceRange(LParenLoc, RParenLoc));
233 }
234
235 ExprResult
BuildCXXNamedCast(SourceLocation OpLoc,tok::TokenKind Kind,TypeSourceInfo * DestTInfo,Expr * E,SourceRange AngleBrackets,SourceRange Parens)236 Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
237 TypeSourceInfo *DestTInfo, Expr *E,
238 SourceRange AngleBrackets, SourceRange Parens) {
239 ExprResult Ex = E;
240 QualType DestType = DestTInfo->getType();
241
242 // If the type is dependent, we won't do the semantic analysis now.
243 bool TypeDependent =
244 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.get(), DestTInfo,
261 OpLoc, Parens.getEnd(),
262 AngleBrackets));
263
264 case tok::kw_dynamic_cast: {
265 if (!TypeDependent) {
266 Op.CheckDynamicCast();
267 if (Op.SrcExpr.isInvalid())
268 return ExprError();
269 }
270 return Op.complete(CXXDynamicCastExpr::Create(Context, Op.ResultType,
271 Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
272 &Op.BasePath, DestTInfo,
273 OpLoc, Parens.getEnd(),
274 AngleBrackets));
275 }
276 case tok::kw_reinterpret_cast: {
277 if (!TypeDependent) {
278 Op.CheckReinterpretCast();
279 if (Op.SrcExpr.isInvalid())
280 return ExprError();
281 }
282 return Op.complete(CXXReinterpretCastExpr::Create(Context, Op.ResultType,
283 Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
284 nullptr, DestTInfo, OpLoc,
285 Parens.getEnd(),
286 AngleBrackets));
287 }
288 case tok::kw_static_cast: {
289 if (!TypeDependent) {
290 Op.CheckStaticCast();
291 if (Op.SrcExpr.isInvalid())
292 return ExprError();
293 }
294
295 return Op.complete(CXXStaticCastExpr::Create(Context, Op.ResultType,
296 Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
297 &Op.BasePath, DestTInfo,
298 OpLoc, Parens.getEnd(),
299 AngleBrackets));
300 }
301 }
302 }
303
304 /// Try to diagnose a failed overloaded cast. Returns true if
305 /// diagnostics were emitted.
tryDiagnoseOverloadedCast(Sema & S,CastType CT,SourceRange range,Expr * src,QualType destType,bool listInitialization)306 static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT,
307 SourceRange range, Expr *src,
308 QualType destType,
309 bool listInitialization) {
310 switch (CT) {
311 // These cast kinds don't consider user-defined conversions.
312 case CT_Const:
313 case CT_Reinterpret:
314 case CT_Dynamic:
315 return false;
316
317 // These do.
318 case CT_Static:
319 case CT_CStyle:
320 case CT_Functional:
321 break;
322 }
323
324 QualType srcType = src->getType();
325 if (!destType->isRecordType() && !srcType->isRecordType())
326 return false;
327
328 InitializedEntity entity = InitializedEntity::InitializeTemporary(destType);
329 InitializationKind initKind
330 = (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(),
331 range, listInitialization)
332 : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range,
333 listInitialization)
334 : InitializationKind::CreateCast(/*type range?*/ range);
335 InitializationSequence sequence(S, entity, initKind, src);
336
337 assert(sequence.Failed() && "initialization succeeded on second try?");
338 switch (sequence.getFailureKind()) {
339 default: return false;
340
341 case InitializationSequence::FK_ConstructorOverloadFailed:
342 case InitializationSequence::FK_UserConversionOverloadFailed:
343 break;
344 }
345
346 OverloadCandidateSet &candidates = sequence.getFailedCandidateSet();
347
348 unsigned msg = 0;
349 OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates;
350
351 switch (sequence.getFailedOverloadResult()) {
352 case OR_Success: llvm_unreachable("successful failed overload");
353 case OR_No_Viable_Function:
354 if (candidates.empty())
355 msg = diag::err_ovl_no_conversion_in_cast;
356 else
357 msg = diag::err_ovl_no_viable_conversion_in_cast;
358 howManyCandidates = OCD_AllCandidates;
359 break;
360
361 case OR_Ambiguous:
362 msg = diag::err_ovl_ambiguous_conversion_in_cast;
363 howManyCandidates = OCD_ViableCandidates;
364 break;
365
366 case OR_Deleted:
367 msg = diag::err_ovl_deleted_conversion_in_cast;
368 howManyCandidates = OCD_ViableCandidates;
369 break;
370 }
371
372 S.Diag(range.getBegin(), msg)
373 << CT << srcType << destType
374 << range << src->getSourceRange();
375
376 candidates.NoteCandidates(S, howManyCandidates, src);
377
378 return true;
379 }
380
381 /// Diagnose a failed cast.
diagnoseBadCast(Sema & S,unsigned msg,CastType castType,SourceRange opRange,Expr * src,QualType destType,bool listInitialization)382 static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType,
383 SourceRange opRange, Expr *src, QualType destType,
384 bool listInitialization) {
385 if (msg == diag::err_bad_cxx_cast_generic &&
386 tryDiagnoseOverloadedCast(S, castType, opRange, src, destType,
387 listInitialization))
388 return;
389
390 S.Diag(opRange.getBegin(), msg) << castType
391 << src->getType() << destType << opRange << src->getSourceRange();
392
393 // Detect if both types are (ptr to) class, and note any incompleteness.
394 int DifferentPtrness = 0;
395 QualType From = destType;
396 if (auto Ptr = From->getAs<PointerType>()) {
397 From = Ptr->getPointeeType();
398 DifferentPtrness++;
399 }
400 QualType To = src->getType();
401 if (auto Ptr = To->getAs<PointerType>()) {
402 To = Ptr->getPointeeType();
403 DifferentPtrness--;
404 }
405 if (!DifferentPtrness) {
406 auto RecFrom = From->getAs<RecordType>();
407 auto RecTo = To->getAs<RecordType>();
408 if (RecFrom && RecTo) {
409 auto DeclFrom = RecFrom->getAsCXXRecordDecl();
410 if (!DeclFrom->isCompleteDefinition())
411 S.Diag(DeclFrom->getLocation(), diag::note_type_incomplete)
412 << DeclFrom->getDeclName();
413 auto DeclTo = RecTo->getAsCXXRecordDecl();
414 if (!DeclTo->isCompleteDefinition())
415 S.Diag(DeclTo->getLocation(), diag::note_type_incomplete)
416 << DeclTo->getDeclName();
417 }
418 }
419 }
420
421 /// UnwrapDissimilarPointerTypes - Like Sema::UnwrapSimilarPointerTypes,
422 /// this removes one level of indirection from both types, provided that they're
423 /// the same kind of pointer (plain or to-member). Unlike the Sema function,
424 /// this one doesn't care if the two pointers-to-member don't point into the
425 /// same class. This is because CastsAwayConstness doesn't care.
UnwrapDissimilarPointerTypes(QualType & T1,QualType & T2)426 static bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) {
427 const PointerType *T1PtrType = T1->getAs<PointerType>(),
428 *T2PtrType = T2->getAs<PointerType>();
429 if (T1PtrType && T2PtrType) {
430 T1 = T1PtrType->getPointeeType();
431 T2 = T2PtrType->getPointeeType();
432 return true;
433 }
434 const ObjCObjectPointerType *T1ObjCPtrType =
435 T1->getAs<ObjCObjectPointerType>(),
436 *T2ObjCPtrType =
437 T2->getAs<ObjCObjectPointerType>();
438 if (T1ObjCPtrType) {
439 if (T2ObjCPtrType) {
440 T1 = T1ObjCPtrType->getPointeeType();
441 T2 = T2ObjCPtrType->getPointeeType();
442 return true;
443 }
444 else if (T2PtrType) {
445 T1 = T1ObjCPtrType->getPointeeType();
446 T2 = T2PtrType->getPointeeType();
447 return true;
448 }
449 }
450 else if (T2ObjCPtrType) {
451 if (T1PtrType) {
452 T2 = T2ObjCPtrType->getPointeeType();
453 T1 = T1PtrType->getPointeeType();
454 return true;
455 }
456 }
457
458 const MemberPointerType *T1MPType = T1->getAs<MemberPointerType>(),
459 *T2MPType = T2->getAs<MemberPointerType>();
460 if (T1MPType && T2MPType) {
461 T1 = T1MPType->getPointeeType();
462 T2 = T2MPType->getPointeeType();
463 return true;
464 }
465
466 const BlockPointerType *T1BPType = T1->getAs<BlockPointerType>(),
467 *T2BPType = T2->getAs<BlockPointerType>();
468 if (T1BPType && T2BPType) {
469 T1 = T1BPType->getPointeeType();
470 T2 = T2BPType->getPointeeType();
471 return true;
472 }
473
474 return false;
475 }
476
477 /// CastsAwayConstness - Check if the pointer conversion from SrcType to
478 /// DestType casts away constness as defined in C++ 5.2.11p8ff. This is used by
479 /// the cast checkers. Both arguments must denote pointer (possibly to member)
480 /// types.
481 ///
482 /// \param CheckCVR Whether to check for const/volatile/restrict qualifiers.
483 ///
484 /// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers.
485 static bool
CastsAwayConstness(Sema & Self,QualType SrcType,QualType DestType,bool CheckCVR,bool CheckObjCLifetime,QualType * TheOffendingSrcType=nullptr,QualType * TheOffendingDestType=nullptr,Qualifiers * CastAwayQualifiers=nullptr)486 CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType,
487 bool CheckCVR, bool CheckObjCLifetime,
488 QualType *TheOffendingSrcType = nullptr,
489 QualType *TheOffendingDestType = nullptr,
490 Qualifiers *CastAwayQualifiers = nullptr) {
491 // If the only checking we care about is for Objective-C lifetime qualifiers,
492 // and we're not in ObjC mode, there's nothing to check.
493 if (!CheckCVR && CheckObjCLifetime &&
494 !Self.Context.getLangOpts().ObjC1)
495 return false;
496
497 // Casting away constness is defined in C++ 5.2.11p8 with reference to
498 // C++ 4.4. We piggyback on Sema::IsQualificationConversion for this, since
499 // the rules are non-trivial. So first we construct Tcv *...cv* as described
500 // in C++ 5.2.11p8.
501 assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() ||
502 SrcType->isBlockPointerType()) &&
503 "Source type is not pointer or pointer to member.");
504 assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() ||
505 DestType->isBlockPointerType()) &&
506 "Destination type is not pointer or pointer to member.");
507
508 QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType),
509 UnwrappedDestType = Self.Context.getCanonicalType(DestType);
510 SmallVector<Qualifiers, 8> cv1, cv2;
511
512 // Find the qualifiers. We only care about cvr-qualifiers for the
513 // purpose of this check, because other qualifiers (address spaces,
514 // Objective-C GC, etc.) are part of the type's identity.
515 QualType PrevUnwrappedSrcType = UnwrappedSrcType;
516 QualType PrevUnwrappedDestType = UnwrappedDestType;
517 while (UnwrapDissimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) {
518 // Determine the relevant qualifiers at this level.
519 Qualifiers SrcQuals, DestQuals;
520 Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals);
521 Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals);
522
523 Qualifiers RetainedSrcQuals, RetainedDestQuals;
524 if (CheckCVR) {
525 RetainedSrcQuals.setCVRQualifiers(SrcQuals.getCVRQualifiers());
526 RetainedDestQuals.setCVRQualifiers(DestQuals.getCVRQualifiers());
527
528 if (RetainedSrcQuals != RetainedDestQuals && TheOffendingSrcType &&
529 TheOffendingDestType && CastAwayQualifiers) {
530 *TheOffendingSrcType = PrevUnwrappedSrcType;
531 *TheOffendingDestType = PrevUnwrappedDestType;
532 *CastAwayQualifiers = RetainedSrcQuals - RetainedDestQuals;
533 }
534 }
535
536 if (CheckObjCLifetime &&
537 !DestQuals.compatiblyIncludesObjCLifetime(SrcQuals))
538 return true;
539
540 cv1.push_back(RetainedSrcQuals);
541 cv2.push_back(RetainedDestQuals);
542
543 PrevUnwrappedSrcType = UnwrappedSrcType;
544 PrevUnwrappedDestType = UnwrappedDestType;
545 }
546 if (cv1.empty())
547 return false;
548
549 // Construct void pointers with those qualifiers (in reverse order of
550 // unwrapping, of course).
551 QualType SrcConstruct = Self.Context.VoidTy;
552 QualType DestConstruct = Self.Context.VoidTy;
553 ASTContext &Context = Self.Context;
554 for (SmallVectorImpl<Qualifiers>::reverse_iterator i1 = cv1.rbegin(),
555 i2 = cv2.rbegin();
556 i1 != cv1.rend(); ++i1, ++i2) {
557 SrcConstruct
558 = Context.getPointerType(Context.getQualifiedType(SrcConstruct, *i1));
559 DestConstruct
560 = Context.getPointerType(Context.getQualifiedType(DestConstruct, *i2));
561 }
562
563 // Test if they're compatible.
564 bool ObjCLifetimeConversion;
565 return SrcConstruct != DestConstruct &&
566 !Self.IsQualificationConversion(SrcConstruct, DestConstruct, false,
567 ObjCLifetimeConversion);
568 }
569
570 /// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid.
571 /// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime-
572 /// checked downcasts in class hierarchies.
CheckDynamicCast()573 void CastOperation::CheckDynamicCast() {
574 if (ValueKind == VK_RValue)
575 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
576 else if (isPlaceholder())
577 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
578 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
579 return;
580
581 QualType OrigSrcType = SrcExpr.get()->getType();
582 QualType DestType = Self.Context.getCanonicalType(this->DestType);
583
584 // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type,
585 // or "pointer to cv void".
586
587 QualType DestPointee;
588 const PointerType *DestPointer = DestType->getAs<PointerType>();
589 const ReferenceType *DestReference = nullptr;
590 if (DestPointer) {
591 DestPointee = DestPointer->getPointeeType();
592 } else if ((DestReference = DestType->getAs<ReferenceType>())) {
593 DestPointee = DestReference->getPointeeType();
594 } else {
595 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr)
596 << this->DestType << DestRange;
597 SrcExpr = ExprError();
598 return;
599 }
600
601 const RecordType *DestRecord = DestPointee->getAs<RecordType>();
602 if (DestPointee->isVoidType()) {
603 assert(DestPointer && "Reference to void is not possible");
604 } else if (DestRecord) {
605 if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee,
606 diag::err_bad_dynamic_cast_incomplete,
607 DestRange)) {
608 SrcExpr = ExprError();
609 return;
610 }
611 } else {
612 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
613 << DestPointee.getUnqualifiedType() << DestRange;
614 SrcExpr = ExprError();
615 return;
616 }
617
618 // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to
619 // complete class type, [...]. If T is an lvalue reference type, v shall be
620 // an lvalue of a complete class type, [...]. If T is an rvalue reference
621 // type, v shall be an expression having a complete class type, [...]
622 QualType SrcType = Self.Context.getCanonicalType(OrigSrcType);
623 QualType SrcPointee;
624 if (DestPointer) {
625 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
626 SrcPointee = SrcPointer->getPointeeType();
627 } else {
628 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr)
629 << OrigSrcType << SrcExpr.get()->getSourceRange();
630 SrcExpr = ExprError();
631 return;
632 }
633 } else if (DestReference->isLValueReferenceType()) {
634 if (!SrcExpr.get()->isLValue()) {
635 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue)
636 << CT_Dynamic << OrigSrcType << this->DestType << OpRange;
637 }
638 SrcPointee = SrcType;
639 } else {
640 // If we're dynamic_casting from a prvalue to an rvalue reference, we need
641 // to materialize the prvalue before we bind the reference to it.
642 if (SrcExpr.get()->isRValue())
643 SrcExpr = new (Self.Context) MaterializeTemporaryExpr(
644 SrcType, SrcExpr.get(), /*IsLValueReference*/false);
645 SrcPointee = SrcType;
646 }
647
648 const RecordType *SrcRecord = SrcPointee->getAs<RecordType>();
649 if (SrcRecord) {
650 if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee,
651 diag::err_bad_dynamic_cast_incomplete,
652 SrcExpr.get())) {
653 SrcExpr = ExprError();
654 return;
655 }
656 } else {
657 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
658 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
659 SrcExpr = ExprError();
660 return;
661 }
662
663 assert((DestPointer || DestReference) &&
664 "Bad destination non-ptr/ref slipped through.");
665 assert((DestRecord || DestPointee->isVoidType()) &&
666 "Bad destination pointee slipped through.");
667 assert(SrcRecord && "Bad source pointee slipped through.");
668
669 // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness.
670 if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) {
671 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away)
672 << CT_Dynamic << OrigSrcType << this->DestType << OpRange;
673 SrcExpr = ExprError();
674 return;
675 }
676
677 // C++ 5.2.7p3: If the type of v is the same as the required result type,
678 // [except for cv].
679 if (DestRecord == SrcRecord) {
680 Kind = CK_NoOp;
681 return;
682 }
683
684 // C++ 5.2.7p5
685 // Upcasts are resolved statically.
686 if (DestRecord &&
687 Self.IsDerivedFrom(OpRange.getBegin(), SrcPointee, DestPointee)) {
688 if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee,
689 OpRange.getBegin(), OpRange,
690 &BasePath)) {
691 SrcExpr = ExprError();
692 return;
693 }
694
695 Kind = CK_DerivedToBase;
696 return;
697 }
698
699 // C++ 5.2.7p6: Otherwise, v shall be [polymorphic].
700 const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition();
701 assert(SrcDecl && "Definition missing");
702 if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) {
703 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic)
704 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
705 SrcExpr = ExprError();
706 }
707
708 // dynamic_cast is not available with -fno-rtti.
709 // As an exception, dynamic_cast to void* is available because it doesn't
710 // use RTTI.
711 if (!Self.getLangOpts().RTTI && !DestPointee->isVoidType()) {
712 Self.Diag(OpRange.getBegin(), diag::err_no_dynamic_cast_with_fno_rtti);
713 SrcExpr = ExprError();
714 return;
715 }
716
717 // Done. Everything else is run-time checks.
718 Kind = CK_Dynamic;
719 }
720
721 /// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid.
722 /// Refer to C++ 5.2.11 for details. const_cast is typically used in code
723 /// like this:
724 /// const char *str = "literal";
725 /// legacy_function(const_cast\<char*\>(str));
CheckConstCast()726 void CastOperation::CheckConstCast() {
727 if (ValueKind == VK_RValue)
728 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
729 else if (isPlaceholder())
730 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
731 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
732 return;
733
734 unsigned msg = diag::err_bad_cxx_cast_generic;
735 if (TryConstCast(Self, SrcExpr, DestType, /*CStyle*/false, msg) != TC_Success
736 && msg != 0) {
737 Self.Diag(OpRange.getBegin(), msg) << CT_Const
738 << SrcExpr.get()->getType() << DestType << OpRange;
739 SrcExpr = ExprError();
740 }
741 }
742
743 /// Check that a reinterpret_cast\<DestType\>(SrcExpr) is not used as upcast
744 /// or downcast between respective pointers or references.
DiagnoseReinterpretUpDownCast(Sema & Self,const Expr * SrcExpr,QualType DestType,SourceRange OpRange)745 static void DiagnoseReinterpretUpDownCast(Sema &Self, const Expr *SrcExpr,
746 QualType DestType,
747 SourceRange OpRange) {
748 QualType SrcType = SrcExpr->getType();
749 // When casting from pointer or reference, get pointee type; use original
750 // type otherwise.
751 const CXXRecordDecl *SrcPointeeRD = SrcType->getPointeeCXXRecordDecl();
752 const CXXRecordDecl *SrcRD =
753 SrcPointeeRD ? SrcPointeeRD : SrcType->getAsCXXRecordDecl();
754
755 // Examining subobjects for records is only possible if the complete and
756 // valid definition is available. Also, template instantiation is not
757 // allowed here.
758 if (!SrcRD || !SrcRD->isCompleteDefinition() || SrcRD->isInvalidDecl())
759 return;
760
761 const CXXRecordDecl *DestRD = DestType->getPointeeCXXRecordDecl();
762
763 if (!DestRD || !DestRD->isCompleteDefinition() || DestRD->isInvalidDecl())
764 return;
765
766 enum {
767 ReinterpretUpcast,
768 ReinterpretDowncast
769 } ReinterpretKind;
770
771 CXXBasePaths BasePaths;
772
773 if (SrcRD->isDerivedFrom(DestRD, BasePaths))
774 ReinterpretKind = ReinterpretUpcast;
775 else if (DestRD->isDerivedFrom(SrcRD, BasePaths))
776 ReinterpretKind = ReinterpretDowncast;
777 else
778 return;
779
780 bool VirtualBase = true;
781 bool NonZeroOffset = false;
782 for (CXXBasePaths::const_paths_iterator I = BasePaths.begin(),
783 E = BasePaths.end();
784 I != E; ++I) {
785 const CXXBasePath &Path = *I;
786 CharUnits Offset = CharUnits::Zero();
787 bool IsVirtual = false;
788 for (CXXBasePath::const_iterator IElem = Path.begin(), EElem = Path.end();
789 IElem != EElem; ++IElem) {
790 IsVirtual = IElem->Base->isVirtual();
791 if (IsVirtual)
792 break;
793 const CXXRecordDecl *BaseRD = IElem->Base->getType()->getAsCXXRecordDecl();
794 assert(BaseRD && "Base type should be a valid unqualified class type");
795 // Don't check if any base has invalid declaration or has no definition
796 // since it has no layout info.
797 const CXXRecordDecl *Class = IElem->Class,
798 *ClassDefinition = Class->getDefinition();
799 if (Class->isInvalidDecl() || !ClassDefinition ||
800 !ClassDefinition->isCompleteDefinition())
801 return;
802
803 const ASTRecordLayout &DerivedLayout =
804 Self.Context.getASTRecordLayout(Class);
805 Offset += DerivedLayout.getBaseClassOffset(BaseRD);
806 }
807 if (!IsVirtual) {
808 // Don't warn if any path is a non-virtually derived base at offset zero.
809 if (Offset.isZero())
810 return;
811 // Offset makes sense only for non-virtual bases.
812 else
813 NonZeroOffset = true;
814 }
815 VirtualBase = VirtualBase && IsVirtual;
816 }
817
818 (void) NonZeroOffset; // Silence set but not used warning.
819 assert((VirtualBase || NonZeroOffset) &&
820 "Should have returned if has non-virtual base with zero offset");
821
822 QualType BaseType =
823 ReinterpretKind == ReinterpretUpcast? DestType : SrcType;
824 QualType DerivedType =
825 ReinterpretKind == ReinterpretUpcast? SrcType : DestType;
826
827 SourceLocation BeginLoc = OpRange.getBegin();
828 Self.Diag(BeginLoc, diag::warn_reinterpret_different_from_static)
829 << DerivedType << BaseType << !VirtualBase << int(ReinterpretKind)
830 << OpRange;
831 Self.Diag(BeginLoc, diag::note_reinterpret_updowncast_use_static)
832 << int(ReinterpretKind)
833 << FixItHint::CreateReplacement(BeginLoc, "static_cast");
834 }
835
836 /// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is
837 /// valid.
838 /// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code
839 /// like this:
840 /// char *bytes = reinterpret_cast\<char*\>(int_ptr);
CheckReinterpretCast()841 void CastOperation::CheckReinterpretCast() {
842 if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload))
843 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
844 else
845 checkNonOverloadPlaceholders();
846 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
847 return;
848
849 unsigned msg = diag::err_bad_cxx_cast_generic;
850 TryCastResult tcr =
851 TryReinterpretCast(Self, SrcExpr, DestType,
852 /*CStyle*/false, OpRange, msg, Kind);
853 if (tcr != TC_Success && msg != 0)
854 {
855 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
856 return;
857 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
858 //FIXME: &f<int>; is overloaded and resolvable
859 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload)
860 << OverloadExpr::find(SrcExpr.get()).Expression->getName()
861 << DestType << OpRange;
862 Self.NoteAllOverloadCandidates(SrcExpr.get());
863
864 } else {
865 diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(),
866 DestType, /*listInitialization=*/false);
867 }
868 SrcExpr = ExprError();
869 } else if (tcr == TC_Success) {
870 if (Self.getLangOpts().ObjCAutoRefCount)
871 checkObjCARCConversion(Sema::CCK_OtherCast);
872 DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange);
873 }
874 }
875
876
877 /// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid.
878 /// Refer to C++ 5.2.9 for details. Static casts are mostly used for making
879 /// implicit conversions explicit and getting rid of data loss warnings.
CheckStaticCast()880 void CastOperation::CheckStaticCast() {
881 if (isPlaceholder()) {
882 checkNonOverloadPlaceholders();
883 if (SrcExpr.isInvalid())
884 return;
885 }
886
887 // This test is outside everything else because it's the only case where
888 // a non-lvalue-reference target type does not lead to decay.
889 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
890 if (DestType->isVoidType()) {
891 Kind = CK_ToVoid;
892
893 if (claimPlaceholder(BuiltinType::Overload)) {
894 Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr,
895 false, // Decay Function to ptr
896 true, // Complain
897 OpRange, DestType, diag::err_bad_static_cast_overload);
898 if (SrcExpr.isInvalid())
899 return;
900 }
901
902 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
903 return;
904 }
905
906 if (ValueKind == VK_RValue && !DestType->isRecordType() &&
907 !isPlaceholder(BuiltinType::Overload)) {
908 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
909 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
910 return;
911 }
912
913 unsigned msg = diag::err_bad_cxx_cast_generic;
914 TryCastResult tcr
915 = TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_OtherCast, OpRange, msg,
916 Kind, BasePath, /*ListInitialization=*/false);
917 if (tcr != TC_Success && msg != 0) {
918 if (SrcExpr.isInvalid())
919 return;
920 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
921 OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression;
922 Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload)
923 << oe->getName() << DestType << OpRange
924 << oe->getQualifierLoc().getSourceRange();
925 Self.NoteAllOverloadCandidates(SrcExpr.get());
926 } else {
927 diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType,
928 /*listInitialization=*/false);
929 }
930 SrcExpr = ExprError();
931 } else if (tcr == TC_Success) {
932 if (Kind == CK_BitCast)
933 checkCastAlign();
934 if (Self.getLangOpts().ObjCAutoRefCount)
935 checkObjCARCConversion(Sema::CCK_OtherCast);
936 } else if (Kind == CK_BitCast) {
937 checkCastAlign();
938 }
939 }
940
941 /// TryStaticCast - Check if a static cast can be performed, and do so if
942 /// possible. If @p CStyle, ignore access restrictions on hierarchy casting
943 /// and casting away constness.
TryStaticCast(Sema & Self,ExprResult & SrcExpr,QualType DestType,Sema::CheckedConversionKind CCK,SourceRange OpRange,unsigned & msg,CastKind & Kind,CXXCastPath & BasePath,bool ListInitialization)944 static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
945 QualType DestType,
946 Sema::CheckedConversionKind CCK,
947 SourceRange OpRange, unsigned &msg,
948 CastKind &Kind, CXXCastPath &BasePath,
949 bool ListInitialization) {
950 // Determine whether we have the semantics of a C-style cast.
951 bool CStyle
952 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast);
953
954 // The order the tests is not entirely arbitrary. There is one conversion
955 // that can be handled in two different ways. Given:
956 // struct A {};
957 // struct B : public A {
958 // B(); B(const A&);
959 // };
960 // const A &a = B();
961 // the cast static_cast<const B&>(a) could be seen as either a static
962 // reference downcast, or an explicit invocation of the user-defined
963 // conversion using B's conversion constructor.
964 // DR 427 specifies that the downcast is to be applied here.
965
966 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
967 // Done outside this function.
968
969 TryCastResult tcr;
970
971 // C++ 5.2.9p5, reference downcast.
972 // See the function for details.
973 // DR 427 specifies that this is to be applied before paragraph 2.
974 tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle,
975 OpRange, msg, Kind, BasePath);
976 if (tcr != TC_NotApplicable)
977 return tcr;
978
979 // C++11 [expr.static.cast]p3:
980 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2
981 // T2" if "cv2 T2" is reference-compatible with "cv1 T1".
982 tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind,
983 BasePath, msg);
984 if (tcr != TC_NotApplicable)
985 return tcr;
986
987 // C++ 5.2.9p2: An expression e can be explicitly converted to a type T
988 // [...] if the declaration "T t(e);" is well-formed, [...].
989 tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg,
990 Kind, ListInitialization);
991 if (SrcExpr.isInvalid())
992 return TC_Failed;
993 if (tcr != TC_NotApplicable)
994 return tcr;
995
996 // C++ 5.2.9p6: May apply the reverse of any standard conversion, except
997 // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean
998 // conversions, subject to further restrictions.
999 // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal
1000 // of qualification conversions impossible.
1001 // In the CStyle case, the earlier attempt to const_cast should have taken
1002 // care of reverse qualification conversions.
1003
1004 QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType());
1005
1006 // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly
1007 // converted to an integral type. [...] A value of a scoped enumeration type
1008 // can also be explicitly converted to a floating-point type [...].
1009 if (const EnumType *Enum = SrcType->getAs<EnumType>()) {
1010 if (Enum->getDecl()->isScoped()) {
1011 if (DestType->isBooleanType()) {
1012 Kind = CK_IntegralToBoolean;
1013 return TC_Success;
1014 } else if (DestType->isIntegralType(Self.Context)) {
1015 Kind = CK_IntegralCast;
1016 return TC_Success;
1017 } else if (DestType->isRealFloatingType()) {
1018 Kind = CK_IntegralToFloating;
1019 return TC_Success;
1020 }
1021 }
1022 }
1023
1024 // Reverse integral promotion/conversion. All such conversions are themselves
1025 // again integral promotions or conversions and are thus already handled by
1026 // p2 (TryDirectInitialization above).
1027 // (Note: any data loss warnings should be suppressed.)
1028 // The exception is the reverse of enum->integer, i.e. integer->enum (and
1029 // enum->enum). See also C++ 5.2.9p7.
1030 // The same goes for reverse floating point promotion/conversion and
1031 // floating-integral conversions. Again, only floating->enum is relevant.
1032 if (DestType->isEnumeralType()) {
1033 if (SrcType->isIntegralOrEnumerationType()) {
1034 Kind = CK_IntegralCast;
1035 return TC_Success;
1036 } else if (SrcType->isRealFloatingType()) {
1037 Kind = CK_FloatingToIntegral;
1038 return TC_Success;
1039 }
1040 }
1041
1042 // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast.
1043 // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance.
1044 tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg,
1045 Kind, BasePath);
1046 if (tcr != TC_NotApplicable)
1047 return tcr;
1048
1049 // Reverse member pointer conversion. C++ 4.11 specifies member pointer
1050 // conversion. C++ 5.2.9p9 has additional information.
1051 // DR54's access restrictions apply here also.
1052 tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle,
1053 OpRange, msg, Kind, BasePath);
1054 if (tcr != TC_NotApplicable)
1055 return tcr;
1056
1057 // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to
1058 // void*. C++ 5.2.9p10 specifies additional restrictions, which really is
1059 // just the usual constness stuff.
1060 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
1061 QualType SrcPointee = SrcPointer->getPointeeType();
1062 if (SrcPointee->isVoidType()) {
1063 if (const PointerType *DestPointer = DestType->getAs<PointerType>()) {
1064 QualType DestPointee = DestPointer->getPointeeType();
1065 if (DestPointee->isIncompleteOrObjectType()) {
1066 // This is definitely the intended conversion, but it might fail due
1067 // to a qualifier violation. Note that we permit Objective-C lifetime
1068 // and GC qualifier mismatches here.
1069 if (!CStyle) {
1070 Qualifiers DestPointeeQuals = DestPointee.getQualifiers();
1071 Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers();
1072 DestPointeeQuals.removeObjCGCAttr();
1073 DestPointeeQuals.removeObjCLifetime();
1074 SrcPointeeQuals.removeObjCGCAttr();
1075 SrcPointeeQuals.removeObjCLifetime();
1076 if (DestPointeeQuals != SrcPointeeQuals &&
1077 !DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) {
1078 msg = diag::err_bad_cxx_cast_qualifiers_away;
1079 return TC_Failed;
1080 }
1081 }
1082 Kind = CK_BitCast;
1083 return TC_Success;
1084 }
1085
1086 // Microsoft permits static_cast from 'pointer-to-void' to
1087 // 'pointer-to-function'.
1088 if (!CStyle && Self.getLangOpts().MSVCCompat &&
1089 DestPointee->isFunctionType()) {
1090 Self.Diag(OpRange.getBegin(), diag::ext_ms_cast_fn_obj) << OpRange;
1091 Kind = CK_BitCast;
1092 return TC_Success;
1093 }
1094 }
1095 else if (DestType->isObjCObjectPointerType()) {
1096 // allow both c-style cast and static_cast of objective-c pointers as
1097 // they are pervasive.
1098 Kind = CK_CPointerToObjCPointerCast;
1099 return TC_Success;
1100 }
1101 else if (CStyle && DestType->isBlockPointerType()) {
1102 // allow c-style cast of void * to block pointers.
1103 Kind = CK_AnyPointerToBlockPointerCast;
1104 return TC_Success;
1105 }
1106 }
1107 }
1108 // Allow arbitray objective-c pointer conversion with static casts.
1109 if (SrcType->isObjCObjectPointerType() &&
1110 DestType->isObjCObjectPointerType()) {
1111 Kind = CK_BitCast;
1112 return TC_Success;
1113 }
1114 // Allow ns-pointer to cf-pointer conversion in either direction
1115 // with static casts.
1116 if (!CStyle &&
1117 Self.CheckTollFreeBridgeStaticCast(DestType, SrcExpr.get(), Kind))
1118 return TC_Success;
1119
1120 // See if it looks like the user is trying to convert between
1121 // related record types, and select a better diagnostic if so.
1122 if (auto SrcPointer = SrcType->getAs<PointerType>())
1123 if (auto DestPointer = DestType->getAs<PointerType>())
1124 if (SrcPointer->getPointeeType()->getAs<RecordType>() &&
1125 DestPointer->getPointeeType()->getAs<RecordType>())
1126 msg = diag::err_bad_cxx_cast_unrelated_class;
1127
1128 // We tried everything. Everything! Nothing works! :-(
1129 return TC_NotApplicable;
1130 }
1131
1132 /// Tests whether a conversion according to N2844 is valid.
1133 TryCastResult
TryLValueToRValueCast(Sema & Self,Expr * SrcExpr,QualType DestType,bool CStyle,CastKind & Kind,CXXCastPath & BasePath,unsigned & msg)1134 TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType,
1135 bool CStyle, CastKind &Kind, CXXCastPath &BasePath,
1136 unsigned &msg) {
1137 // C++11 [expr.static.cast]p3:
1138 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to
1139 // cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1".
1140 const RValueReferenceType *R = DestType->getAs<RValueReferenceType>();
1141 if (!R)
1142 return TC_NotApplicable;
1143
1144 if (!SrcExpr->isGLValue())
1145 return TC_NotApplicable;
1146
1147 // Because we try the reference downcast before this function, from now on
1148 // this is the only cast possibility, so we issue an error if we fail now.
1149 // FIXME: Should allow casting away constness if CStyle.
1150 bool DerivedToBase;
1151 bool ObjCConversion;
1152 bool ObjCLifetimeConversion;
1153 QualType FromType = SrcExpr->getType();
1154 QualType ToType = R->getPointeeType();
1155 if (CStyle) {
1156 FromType = FromType.getUnqualifiedType();
1157 ToType = ToType.getUnqualifiedType();
1158 }
1159
1160 if (Self.CompareReferenceRelationship(SrcExpr->getLocStart(),
1161 ToType, FromType,
1162 DerivedToBase, ObjCConversion,
1163 ObjCLifetimeConversion)
1164 < Sema::Ref_Compatible_With_Added_Qualification) {
1165 if (CStyle)
1166 return TC_NotApplicable;
1167 msg = diag::err_bad_lvalue_to_rvalue_cast;
1168 return TC_Failed;
1169 }
1170
1171 if (DerivedToBase) {
1172 Kind = CK_DerivedToBase;
1173 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1174 /*DetectVirtual=*/true);
1175 if (!Self.IsDerivedFrom(SrcExpr->getLocStart(), SrcExpr->getType(),
1176 R->getPointeeType(), Paths))
1177 return TC_NotApplicable;
1178
1179 Self.BuildBasePathArray(Paths, BasePath);
1180 } else
1181 Kind = CK_NoOp;
1182
1183 return TC_Success;
1184 }
1185
1186 /// Tests whether a conversion according to C++ 5.2.9p5 is valid.
1187 TryCastResult
TryStaticReferenceDowncast(Sema & Self,Expr * SrcExpr,QualType DestType,bool CStyle,SourceRange OpRange,unsigned & msg,CastKind & Kind,CXXCastPath & BasePath)1188 TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType,
1189 bool CStyle, SourceRange OpRange,
1190 unsigned &msg, CastKind &Kind,
1191 CXXCastPath &BasePath) {
1192 // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be
1193 // cast to type "reference to cv2 D", where D is a class derived from B,
1194 // if a valid standard conversion from "pointer to D" to "pointer to B"
1195 // exists, cv2 >= cv1, and B is not a virtual base class of D.
1196 // In addition, DR54 clarifies that the base must be accessible in the
1197 // current context. Although the wording of DR54 only applies to the pointer
1198 // variant of this rule, the intent is clearly for it to apply to the this
1199 // conversion as well.
1200
1201 const ReferenceType *DestReference = DestType->getAs<ReferenceType>();
1202 if (!DestReference) {
1203 return TC_NotApplicable;
1204 }
1205 bool RValueRef = DestReference->isRValueReferenceType();
1206 if (!RValueRef && !SrcExpr->isLValue()) {
1207 // We know the left side is an lvalue reference, so we can suggest a reason.
1208 msg = diag::err_bad_cxx_cast_rvalue;
1209 return TC_NotApplicable;
1210 }
1211
1212 QualType DestPointee = DestReference->getPointeeType();
1213
1214 // FIXME: If the source is a prvalue, we should issue a warning (because the
1215 // cast always has undefined behavior), and for AST consistency, we should
1216 // materialize a temporary.
1217 return TryStaticDowncast(Self,
1218 Self.Context.getCanonicalType(SrcExpr->getType()),
1219 Self.Context.getCanonicalType(DestPointee), CStyle,
1220 OpRange, SrcExpr->getType(), DestType, msg, Kind,
1221 BasePath);
1222 }
1223
1224 /// Tests whether a conversion according to C++ 5.2.9p8 is valid.
1225 TryCastResult
TryStaticPointerDowncast(Sema & Self,QualType SrcType,QualType DestType,bool CStyle,SourceRange OpRange,unsigned & msg,CastKind & Kind,CXXCastPath & BasePath)1226 TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType,
1227 bool CStyle, SourceRange OpRange,
1228 unsigned &msg, CastKind &Kind,
1229 CXXCastPath &BasePath) {
1230 // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class
1231 // type, can be converted to an rvalue of type "pointer to cv2 D", where D
1232 // is a class derived from B, if a valid standard conversion from "pointer
1233 // to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base
1234 // class of D.
1235 // In addition, DR54 clarifies that the base must be accessible in the
1236 // current context.
1237
1238 const PointerType *DestPointer = DestType->getAs<PointerType>();
1239 if (!DestPointer) {
1240 return TC_NotApplicable;
1241 }
1242
1243 const PointerType *SrcPointer = SrcType->getAs<PointerType>();
1244 if (!SrcPointer) {
1245 msg = diag::err_bad_static_cast_pointer_nonpointer;
1246 return TC_NotApplicable;
1247 }
1248
1249 return TryStaticDowncast(Self,
1250 Self.Context.getCanonicalType(SrcPointer->getPointeeType()),
1251 Self.Context.getCanonicalType(DestPointer->getPointeeType()),
1252 CStyle, OpRange, SrcType, DestType, msg, Kind,
1253 BasePath);
1254 }
1255
1256 /// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and
1257 /// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to
1258 /// DestType is possible and allowed.
1259 TryCastResult
TryStaticDowncast(Sema & Self,CanQualType SrcType,CanQualType DestType,bool CStyle,SourceRange OpRange,QualType OrigSrcType,QualType OrigDestType,unsigned & msg,CastKind & Kind,CXXCastPath & BasePath)1260 TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType,
1261 bool CStyle, SourceRange OpRange, QualType OrigSrcType,
1262 QualType OrigDestType, unsigned &msg,
1263 CastKind &Kind, CXXCastPath &BasePath) {
1264 // We can only work with complete types. But don't complain if it doesn't work
1265 if (!Self.isCompleteType(OpRange.getBegin(), SrcType) ||
1266 !Self.isCompleteType(OpRange.getBegin(), DestType))
1267 return TC_NotApplicable;
1268
1269 // Downcast can only happen in class hierarchies, so we need classes.
1270 if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) {
1271 return TC_NotApplicable;
1272 }
1273
1274 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1275 /*DetectVirtual=*/true);
1276 if (!Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths)) {
1277 return TC_NotApplicable;
1278 }
1279
1280 // Target type does derive from source type. Now we're serious. If an error
1281 // appears now, it's not ignored.
1282 // This may not be entirely in line with the standard. Take for example:
1283 // struct A {};
1284 // struct B : virtual A {
1285 // B(A&);
1286 // };
1287 //
1288 // void f()
1289 // {
1290 // (void)static_cast<const B&>(*((A*)0));
1291 // }
1292 // As far as the standard is concerned, p5 does not apply (A is virtual), so
1293 // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid.
1294 // However, both GCC and Comeau reject this example, and accepting it would
1295 // mean more complex code if we're to preserve the nice error message.
1296 // FIXME: Being 100% compliant here would be nice to have.
1297
1298 // Must preserve cv, as always, unless we're in C-style mode.
1299 if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) {
1300 msg = diag::err_bad_cxx_cast_qualifiers_away;
1301 return TC_Failed;
1302 }
1303
1304 if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) {
1305 // This code is analoguous to that in CheckDerivedToBaseConversion, except
1306 // that it builds the paths in reverse order.
1307 // To sum up: record all paths to the base and build a nice string from
1308 // them. Use it to spice up the error message.
1309 if (!Paths.isRecordingPaths()) {
1310 Paths.clear();
1311 Paths.setRecordingPaths(true);
1312 Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths);
1313 }
1314 std::string PathDisplayStr;
1315 std::set<unsigned> DisplayedPaths;
1316 for (CXXBasePaths::paths_iterator PI = Paths.begin(), PE = Paths.end();
1317 PI != PE; ++PI) {
1318 if (DisplayedPaths.insert(PI->back().SubobjectNumber).second) {
1319 // We haven't displayed a path to this particular base
1320 // class subobject yet.
1321 PathDisplayStr += "\n ";
1322 for (CXXBasePath::const_reverse_iterator EI = PI->rbegin(),
1323 EE = PI->rend();
1324 EI != EE; ++EI)
1325 PathDisplayStr += EI->Base->getType().getAsString() + " -> ";
1326 PathDisplayStr += QualType(DestType).getAsString();
1327 }
1328 }
1329
1330 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast)
1331 << QualType(SrcType).getUnqualifiedType()
1332 << QualType(DestType).getUnqualifiedType()
1333 << PathDisplayStr << OpRange;
1334 msg = 0;
1335 return TC_Failed;
1336 }
1337
1338 if (Paths.getDetectedVirtual() != nullptr) {
1339 QualType VirtualBase(Paths.getDetectedVirtual(), 0);
1340 Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual)
1341 << OrigSrcType << OrigDestType << VirtualBase << OpRange;
1342 msg = 0;
1343 return TC_Failed;
1344 }
1345
1346 if (!CStyle) {
1347 switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
1348 SrcType, DestType,
1349 Paths.front(),
1350 diag::err_downcast_from_inaccessible_base)) {
1351 case Sema::AR_accessible:
1352 case Sema::AR_delayed: // be optimistic
1353 case Sema::AR_dependent: // be optimistic
1354 break;
1355
1356 case Sema::AR_inaccessible:
1357 msg = 0;
1358 return TC_Failed;
1359 }
1360 }
1361
1362 Self.BuildBasePathArray(Paths, BasePath);
1363 Kind = CK_BaseToDerived;
1364 return TC_Success;
1365 }
1366
1367 /// TryStaticMemberPointerUpcast - Tests whether a conversion according to
1368 /// C++ 5.2.9p9 is valid:
1369 ///
1370 /// An rvalue of type "pointer to member of D of type cv1 T" can be
1371 /// converted to an rvalue of type "pointer to member of B of type cv2 T",
1372 /// where B is a base class of D [...].
1373 ///
1374 TryCastResult
TryStaticMemberPointerUpcast(Sema & Self,ExprResult & SrcExpr,QualType SrcType,QualType DestType,bool CStyle,SourceRange OpRange,unsigned & msg,CastKind & Kind,CXXCastPath & BasePath)1375 TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType,
1376 QualType DestType, bool CStyle,
1377 SourceRange OpRange,
1378 unsigned &msg, CastKind &Kind,
1379 CXXCastPath &BasePath) {
1380 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>();
1381 if (!DestMemPtr)
1382 return TC_NotApplicable;
1383
1384 bool WasOverloadedFunction = false;
1385 DeclAccessPair FoundOverload;
1386 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
1387 if (FunctionDecl *Fn
1388 = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false,
1389 FoundOverload)) {
1390 CXXMethodDecl *M = cast<CXXMethodDecl>(Fn);
1391 SrcType = Self.Context.getMemberPointerType(Fn->getType(),
1392 Self.Context.getTypeDeclType(M->getParent()).getTypePtr());
1393 WasOverloadedFunction = true;
1394 }
1395 }
1396
1397 const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>();
1398 if (!SrcMemPtr) {
1399 msg = diag::err_bad_static_cast_member_pointer_nonmp;
1400 return TC_NotApplicable;
1401 }
1402
1403 // Lock down the inheritance model right now in MS ABI, whether or not the
1404 // pointee types are the same.
1405 if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft())
1406 (void)Self.isCompleteType(OpRange.getBegin(), SrcType);
1407
1408 // T == T, modulo cv
1409 if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(),
1410 DestMemPtr->getPointeeType()))
1411 return TC_NotApplicable;
1412
1413 // B base of D
1414 QualType SrcClass(SrcMemPtr->getClass(), 0);
1415 QualType DestClass(DestMemPtr->getClass(), 0);
1416 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1417 /*DetectVirtual=*/true);
1418 if (!Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths))
1419 return TC_NotApplicable;
1420
1421 // B is a base of D. But is it an allowed base? If not, it's a hard error.
1422 if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) {
1423 Paths.clear();
1424 Paths.setRecordingPaths(true);
1425 bool StillOkay =
1426 Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths);
1427 assert(StillOkay);
1428 (void)StillOkay;
1429 std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths);
1430 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv)
1431 << 1 << SrcClass << DestClass << PathDisplayStr << OpRange;
1432 msg = 0;
1433 return TC_Failed;
1434 }
1435
1436 if (const RecordType *VBase = Paths.getDetectedVirtual()) {
1437 Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual)
1438 << SrcClass << DestClass << QualType(VBase, 0) << OpRange;
1439 msg = 0;
1440 return TC_Failed;
1441 }
1442
1443 if (!CStyle) {
1444 switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
1445 DestClass, SrcClass,
1446 Paths.front(),
1447 diag::err_upcast_to_inaccessible_base)) {
1448 case Sema::AR_accessible:
1449 case Sema::AR_delayed:
1450 case Sema::AR_dependent:
1451 // Optimistically assume that the delayed and dependent cases
1452 // will work out.
1453 break;
1454
1455 case Sema::AR_inaccessible:
1456 msg = 0;
1457 return TC_Failed;
1458 }
1459 }
1460
1461 if (WasOverloadedFunction) {
1462 // Resolve the address of the overloaded function again, this time
1463 // allowing complaints if something goes wrong.
1464 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(),
1465 DestType,
1466 true,
1467 FoundOverload);
1468 if (!Fn) {
1469 msg = 0;
1470 return TC_Failed;
1471 }
1472
1473 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn);
1474 if (!SrcExpr.isUsable()) {
1475 msg = 0;
1476 return TC_Failed;
1477 }
1478 }
1479
1480 Self.BuildBasePathArray(Paths, BasePath);
1481 Kind = CK_DerivedToBaseMemberPointer;
1482 return TC_Success;
1483 }
1484
1485 /// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2
1486 /// is valid:
1487 ///
1488 /// An expression e can be explicitly converted to a type T using a
1489 /// @c static_cast if the declaration "T t(e);" is well-formed [...].
1490 TryCastResult
TryStaticImplicitCast(Sema & Self,ExprResult & SrcExpr,QualType DestType,Sema::CheckedConversionKind CCK,SourceRange OpRange,unsigned & msg,CastKind & Kind,bool ListInitialization)1491 TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
1492 Sema::CheckedConversionKind CCK,
1493 SourceRange OpRange, unsigned &msg,
1494 CastKind &Kind, bool ListInitialization) {
1495 if (DestType->isRecordType()) {
1496 if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
1497 diag::err_bad_dynamic_cast_incomplete) ||
1498 Self.RequireNonAbstractType(OpRange.getBegin(), DestType,
1499 diag::err_allocation_of_abstract_type)) {
1500 msg = 0;
1501 return TC_Failed;
1502 }
1503 }
1504
1505 InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType);
1506 InitializationKind InitKind
1507 = (CCK == Sema::CCK_CStyleCast)
1508 ? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange,
1509 ListInitialization)
1510 : (CCK == Sema::CCK_FunctionalCast)
1511 ? InitializationKind::CreateFunctionalCast(OpRange, ListInitialization)
1512 : InitializationKind::CreateCast(OpRange);
1513 Expr *SrcExprRaw = SrcExpr.get();
1514 InitializationSequence InitSeq(Self, Entity, InitKind, SrcExprRaw);
1515
1516 // At this point of CheckStaticCast, if the destination is a reference,
1517 // or the expression is an overload expression this has to work.
1518 // There is no other way that works.
1519 // On the other hand, if we're checking a C-style cast, we've still got
1520 // the reinterpret_cast way.
1521 bool CStyle
1522 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast);
1523 if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType()))
1524 return TC_NotApplicable;
1525
1526 ExprResult Result = InitSeq.Perform(Self, Entity, InitKind, SrcExprRaw);
1527 if (Result.isInvalid()) {
1528 msg = 0;
1529 return TC_Failed;
1530 }
1531
1532 if (InitSeq.isConstructorInitialization())
1533 Kind = CK_ConstructorConversion;
1534 else
1535 Kind = CK_NoOp;
1536
1537 SrcExpr = Result;
1538 return TC_Success;
1539 }
1540
1541 /// TryConstCast - See if a const_cast from source to destination is allowed,
1542 /// and perform it if it is.
TryConstCast(Sema & Self,ExprResult & SrcExpr,QualType DestType,bool CStyle,unsigned & msg)1543 static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr,
1544 QualType DestType, bool CStyle,
1545 unsigned &msg) {
1546 DestType = Self.Context.getCanonicalType(DestType);
1547 QualType SrcType = SrcExpr.get()->getType();
1548 bool NeedToMaterializeTemporary = false;
1549
1550 if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) {
1551 // C++11 5.2.11p4:
1552 // if a pointer to T1 can be explicitly converted to the type "pointer to
1553 // T2" using a const_cast, then the following conversions can also be
1554 // made:
1555 // -- an lvalue of type T1 can be explicitly converted to an lvalue of
1556 // type T2 using the cast const_cast<T2&>;
1557 // -- a glvalue of type T1 can be explicitly converted to an xvalue of
1558 // type T2 using the cast const_cast<T2&&>; and
1559 // -- if T1 is a class type, a prvalue of type T1 can be explicitly
1560 // converted to an xvalue of type T2 using the cast const_cast<T2&&>.
1561
1562 if (isa<LValueReferenceType>(DestTypeTmp) && !SrcExpr.get()->isLValue()) {
1563 // Cannot const_cast non-lvalue to lvalue reference type. But if this
1564 // is C-style, static_cast might find a way, so we simply suggest a
1565 // message and tell the parent to keep searching.
1566 msg = diag::err_bad_cxx_cast_rvalue;
1567 return TC_NotApplicable;
1568 }
1569
1570 if (isa<RValueReferenceType>(DestTypeTmp) && SrcExpr.get()->isRValue()) {
1571 if (!SrcType->isRecordType()) {
1572 // Cannot const_cast non-class prvalue to rvalue reference type. But if
1573 // this is C-style, static_cast can do this.
1574 msg = diag::err_bad_cxx_cast_rvalue;
1575 return TC_NotApplicable;
1576 }
1577
1578 // Materialize the class prvalue so that the const_cast can bind a
1579 // reference to it.
1580 NeedToMaterializeTemporary = true;
1581 }
1582
1583 // It's not completely clear under the standard whether we can
1584 // const_cast bit-field gl-values. Doing so would not be
1585 // intrinsically complicated, but for now, we say no for
1586 // consistency with other compilers and await the word of the
1587 // committee.
1588 if (SrcExpr.get()->refersToBitField()) {
1589 msg = diag::err_bad_cxx_cast_bitfield;
1590 return TC_NotApplicable;
1591 }
1592
1593 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
1594 SrcType = Self.Context.getPointerType(SrcType);
1595 }
1596
1597 // C++ 5.2.11p5: For a const_cast involving pointers to data members [...]
1598 // the rules for const_cast are the same as those used for pointers.
1599
1600 if (!DestType->isPointerType() &&
1601 !DestType->isMemberPointerType() &&
1602 !DestType->isObjCObjectPointerType()) {
1603 // Cannot cast to non-pointer, non-reference type. Note that, if DestType
1604 // was a reference type, we converted it to a pointer above.
1605 // The status of rvalue references isn't entirely clear, but it looks like
1606 // conversion to them is simply invalid.
1607 // C++ 5.2.11p3: For two pointer types [...]
1608 if (!CStyle)
1609 msg = diag::err_bad_const_cast_dest;
1610 return TC_NotApplicable;
1611 }
1612 if (DestType->isFunctionPointerType() ||
1613 DestType->isMemberFunctionPointerType()) {
1614 // Cannot cast direct function pointers.
1615 // C++ 5.2.11p2: [...] where T is any object type or the void type [...]
1616 // T is the ultimate pointee of source and target type.
1617 if (!CStyle)
1618 msg = diag::err_bad_const_cast_dest;
1619 return TC_NotApplicable;
1620 }
1621 SrcType = Self.Context.getCanonicalType(SrcType);
1622
1623 // Unwrap the pointers. Ignore qualifiers. Terminate early if the types are
1624 // completely equal.
1625 // C++ 5.2.11p3 describes the core semantics of const_cast. All cv specifiers
1626 // in multi-level pointers may change, but the level count must be the same,
1627 // as must be the final pointee type.
1628 while (SrcType != DestType &&
1629 Self.Context.UnwrapSimilarPointerTypes(SrcType, DestType)) {
1630 Qualifiers SrcQuals, DestQuals;
1631 SrcType = Self.Context.getUnqualifiedArrayType(SrcType, SrcQuals);
1632 DestType = Self.Context.getUnqualifiedArrayType(DestType, DestQuals);
1633
1634 // const_cast is permitted to strip cvr-qualifiers, only. Make sure that
1635 // the other qualifiers (e.g., address spaces) are identical.
1636 SrcQuals.removeCVRQualifiers();
1637 DestQuals.removeCVRQualifiers();
1638 if (SrcQuals != DestQuals)
1639 return TC_NotApplicable;
1640 }
1641
1642 // Since we're dealing in canonical types, the remainder must be the same.
1643 if (SrcType != DestType)
1644 return TC_NotApplicable;
1645
1646 if (NeedToMaterializeTemporary)
1647 // This is a const_cast from a class prvalue to an rvalue reference type.
1648 // Materialize a temporary to store the result of the conversion.
1649 SrcExpr = new (Self.Context) MaterializeTemporaryExpr(
1650 SrcType, SrcExpr.get(), /*IsLValueReference*/ false);
1651
1652 return TC_Success;
1653 }
1654
1655 // Checks for undefined behavior in reinterpret_cast.
1656 // The cases that is checked for is:
1657 // *reinterpret_cast<T*>(&a)
1658 // reinterpret_cast<T&>(a)
1659 // where accessing 'a' as type 'T' will result in undefined behavior.
CheckCompatibleReinterpretCast(QualType SrcType,QualType DestType,bool IsDereference,SourceRange Range)1660 void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType,
1661 bool IsDereference,
1662 SourceRange Range) {
1663 unsigned DiagID = IsDereference ?
1664 diag::warn_pointer_indirection_from_incompatible_type :
1665 diag::warn_undefined_reinterpret_cast;
1666
1667 if (Diags.isIgnored(DiagID, Range.getBegin()))
1668 return;
1669
1670 QualType SrcTy, DestTy;
1671 if (IsDereference) {
1672 if (!SrcType->getAs<PointerType>() || !DestType->getAs<PointerType>()) {
1673 return;
1674 }
1675 SrcTy = SrcType->getPointeeType();
1676 DestTy = DestType->getPointeeType();
1677 } else {
1678 if (!DestType->getAs<ReferenceType>()) {
1679 return;
1680 }
1681 SrcTy = SrcType;
1682 DestTy = DestType->getPointeeType();
1683 }
1684
1685 // Cast is compatible if the types are the same.
1686 if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) {
1687 return;
1688 }
1689 // or one of the types is a char or void type
1690 if (DestTy->isAnyCharacterType() || DestTy->isVoidType() ||
1691 SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) {
1692 return;
1693 }
1694 // or one of the types is a tag type.
1695 if (SrcTy->getAs<TagType>() || DestTy->getAs<TagType>()) {
1696 return;
1697 }
1698
1699 // FIXME: Scoped enums?
1700 if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) ||
1701 (SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) {
1702 if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) {
1703 return;
1704 }
1705 }
1706
1707 Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range;
1708 }
1709
DiagnoseCastOfObjCSEL(Sema & Self,const ExprResult & SrcExpr,QualType DestType)1710 static void DiagnoseCastOfObjCSEL(Sema &Self, const ExprResult &SrcExpr,
1711 QualType DestType) {
1712 QualType SrcType = SrcExpr.get()->getType();
1713 if (Self.Context.hasSameType(SrcType, DestType))
1714 return;
1715 if (const PointerType *SrcPtrTy = SrcType->getAs<PointerType>())
1716 if (SrcPtrTy->isObjCSelType()) {
1717 QualType DT = DestType;
1718 if (isa<PointerType>(DestType))
1719 DT = DestType->getPointeeType();
1720 if (!DT.getUnqualifiedType()->isVoidType())
1721 Self.Diag(SrcExpr.get()->getExprLoc(),
1722 diag::warn_cast_pointer_from_sel)
1723 << SrcType << DestType << SrcExpr.get()->getSourceRange();
1724 }
1725 }
1726
checkIntToPointerCast(bool CStyle,SourceLocation Loc,const Expr * SrcExpr,QualType DestType,Sema & Self)1727 static void checkIntToPointerCast(bool CStyle, SourceLocation Loc,
1728 const Expr *SrcExpr, QualType DestType,
1729 Sema &Self) {
1730 QualType SrcType = SrcExpr->getType();
1731
1732 // Not warning on reinterpret_cast, boolean, constant expressions, etc
1733 // are not explicit design choices, but consistent with GCC's behavior.
1734 // Feel free to modify them if you've reason/evidence for an alternative.
1735 if (CStyle && SrcType->isIntegralType(Self.Context)
1736 && !SrcType->isBooleanType()
1737 && !SrcType->isEnumeralType()
1738 && !SrcExpr->isIntegerConstantExpr(Self.Context)
1739 && Self.Context.getTypeSize(DestType) >
1740 Self.Context.getTypeSize(SrcType)) {
1741 // Separate between casts to void* and non-void* pointers.
1742 // Some APIs use (abuse) void* for something like a user context,
1743 // and often that value is an integer even if it isn't a pointer itself.
1744 // Having a separate warning flag allows users to control the warning
1745 // for their workflow.
1746 unsigned Diag = DestType->isVoidPointerType() ?
1747 diag::warn_int_to_void_pointer_cast
1748 : diag::warn_int_to_pointer_cast;
1749 Self.Diag(Loc, Diag) << SrcType << DestType;
1750 }
1751 }
1752
TryReinterpretCast(Sema & Self,ExprResult & SrcExpr,QualType DestType,bool CStyle,SourceRange OpRange,unsigned & msg,CastKind & Kind)1753 static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
1754 QualType DestType, bool CStyle,
1755 SourceRange OpRange,
1756 unsigned &msg,
1757 CastKind &Kind) {
1758 bool IsLValueCast = false;
1759
1760 DestType = Self.Context.getCanonicalType(DestType);
1761 QualType SrcType = SrcExpr.get()->getType();
1762
1763 // Is the source an overloaded name? (i.e. &foo)
1764 // If so, reinterpret_cast can not help us here (13.4, p1, bullet 5) ...
1765 if (SrcType == Self.Context.OverloadTy) {
1766 // ... unless foo<int> resolves to an lvalue unambiguously.
1767 // TODO: what if this fails because of DiagnoseUseOfDecl or something
1768 // like it?
1769 ExprResult SingleFunctionExpr = SrcExpr;
1770 if (Self.ResolveAndFixSingleFunctionTemplateSpecialization(
1771 SingleFunctionExpr,
1772 Expr::getValueKindForType(DestType) == VK_RValue // Convert Fun to Ptr
1773 ) && SingleFunctionExpr.isUsable()) {
1774 SrcExpr = SingleFunctionExpr;
1775 SrcType = SrcExpr.get()->getType();
1776 } else {
1777 return TC_NotApplicable;
1778 }
1779 }
1780
1781 if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) {
1782 if (!SrcExpr.get()->isGLValue()) {
1783 // Cannot cast non-glvalue to (lvalue or rvalue) reference type. See the
1784 // similar comment in const_cast.
1785 msg = diag::err_bad_cxx_cast_rvalue;
1786 return TC_NotApplicable;
1787 }
1788
1789 if (!CStyle) {
1790 Self.CheckCompatibleReinterpretCast(SrcType, DestType,
1791 /*isDereference=*/false, OpRange);
1792 }
1793
1794 // C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the
1795 // same effect as the conversion *reinterpret_cast<T*>(&x) with the
1796 // built-in & and * operators.
1797
1798 const char *inappropriate = nullptr;
1799 switch (SrcExpr.get()->getObjectKind()) {
1800 case OK_Ordinary:
1801 break;
1802 case OK_BitField: inappropriate = "bit-field"; break;
1803 case OK_VectorComponent: inappropriate = "vector element"; break;
1804 case OK_ObjCProperty: inappropriate = "property expression"; break;
1805 case OK_ObjCSubscript: inappropriate = "container subscripting expression";
1806 break;
1807 }
1808 if (inappropriate) {
1809 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference)
1810 << inappropriate << DestType
1811 << OpRange << SrcExpr.get()->getSourceRange();
1812 msg = 0; SrcExpr = ExprError();
1813 return TC_NotApplicable;
1814 }
1815
1816 // This code does this transformation for the checked types.
1817 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
1818 SrcType = Self.Context.getPointerType(SrcType);
1819
1820 IsLValueCast = true;
1821 }
1822
1823 // Canonicalize source for comparison.
1824 SrcType = Self.Context.getCanonicalType(SrcType);
1825
1826 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(),
1827 *SrcMemPtr = SrcType->getAs<MemberPointerType>();
1828 if (DestMemPtr && SrcMemPtr) {
1829 // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1"
1830 // can be explicitly converted to an rvalue of type "pointer to member
1831 // of Y of type T2" if T1 and T2 are both function types or both object
1832 // types.
1833 if (DestMemPtr->isMemberFunctionPointer() !=
1834 SrcMemPtr->isMemberFunctionPointer())
1835 return TC_NotApplicable;
1836
1837 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away
1838 // constness.
1839 // A reinterpret_cast followed by a const_cast can, though, so in C-style,
1840 // we accept it.
1841 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle,
1842 /*CheckObjCLifetime=*/CStyle)) {
1843 msg = diag::err_bad_cxx_cast_qualifiers_away;
1844 return TC_Failed;
1845 }
1846
1847 if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
1848 // We need to determine the inheritance model that the class will use if
1849 // haven't yet.
1850 (void)Self.isCompleteType(OpRange.getBegin(), SrcType);
1851 (void)Self.isCompleteType(OpRange.getBegin(), DestType);
1852 }
1853
1854 // Don't allow casting between member pointers of different sizes.
1855 if (Self.Context.getTypeSize(DestMemPtr) !=
1856 Self.Context.getTypeSize(SrcMemPtr)) {
1857 msg = diag::err_bad_cxx_cast_member_pointer_size;
1858 return TC_Failed;
1859 }
1860
1861 // A valid member pointer cast.
1862 assert(!IsLValueCast);
1863 Kind = CK_ReinterpretMemberPointer;
1864 return TC_Success;
1865 }
1866
1867 // See below for the enumeral issue.
1868 if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) {
1869 // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral
1870 // type large enough to hold it. A value of std::nullptr_t can be
1871 // converted to an integral type; the conversion has the same meaning
1872 // and validity as a conversion of (void*)0 to the integral type.
1873 if (Self.Context.getTypeSize(SrcType) >
1874 Self.Context.getTypeSize(DestType)) {
1875 msg = diag::err_bad_reinterpret_cast_small_int;
1876 return TC_Failed;
1877 }
1878 Kind = CK_PointerToIntegral;
1879 return TC_Success;
1880 }
1881
1882 // Allow reinterpret_casts between vectors of the same size and
1883 // between vectors and integers of the same size.
1884 bool destIsVector = DestType->isVectorType();
1885 bool srcIsVector = SrcType->isVectorType();
1886 if (srcIsVector || destIsVector) {
1887 // The non-vector type, if any, must have integral type. This is
1888 // the same rule that C vector casts use; note, however, that enum
1889 // types are not integral in C++.
1890 if ((!destIsVector && !DestType->isIntegralType(Self.Context)) ||
1891 (!srcIsVector && !SrcType->isIntegralType(Self.Context)))
1892 return TC_NotApplicable;
1893
1894 // The size we want to consider is eltCount * eltSize.
1895 // That's exactly what the lax-conversion rules will check.
1896 if (Self.areLaxCompatibleVectorTypes(SrcType, DestType)) {
1897 Kind = CK_BitCast;
1898 return TC_Success;
1899 }
1900
1901 // Otherwise, pick a reasonable diagnostic.
1902 if (!destIsVector)
1903 msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size;
1904 else if (!srcIsVector)
1905 msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size;
1906 else
1907 msg = diag::err_bad_cxx_cast_vector_to_vector_different_size;
1908
1909 return TC_Failed;
1910 }
1911
1912 if (SrcType == DestType) {
1913 // C++ 5.2.10p2 has a note that mentions that, subject to all other
1914 // restrictions, a cast to the same type is allowed so long as it does not
1915 // cast away constness. In C++98, the intent was not entirely clear here,
1916 // since all other paragraphs explicitly forbid casts to the same type.
1917 // C++11 clarifies this case with p2.
1918 //
1919 // The only allowed types are: integral, enumeration, pointer, or
1920 // pointer-to-member types. We also won't restrict Obj-C pointers either.
1921 Kind = CK_NoOp;
1922 TryCastResult Result = TC_NotApplicable;
1923 if (SrcType->isIntegralOrEnumerationType() ||
1924 SrcType->isAnyPointerType() ||
1925 SrcType->isMemberPointerType() ||
1926 SrcType->isBlockPointerType()) {
1927 Result = TC_Success;
1928 }
1929 return Result;
1930 }
1931
1932 bool destIsPtr = DestType->isAnyPointerType() ||
1933 DestType->isBlockPointerType();
1934 bool srcIsPtr = SrcType->isAnyPointerType() ||
1935 SrcType->isBlockPointerType();
1936 if (!destIsPtr && !srcIsPtr) {
1937 // Except for std::nullptr_t->integer and lvalue->reference, which are
1938 // handled above, at least one of the two arguments must be a pointer.
1939 return TC_NotApplicable;
1940 }
1941
1942 if (DestType->isIntegralType(Self.Context)) {
1943 assert(srcIsPtr && "One type must be a pointer");
1944 // C++ 5.2.10p4: A pointer can be explicitly converted to any integral
1945 // type large enough to hold it; except in Microsoft mode, where the
1946 // integral type size doesn't matter (except we don't allow bool).
1947 bool MicrosoftException = Self.getLangOpts().MicrosoftExt &&
1948 !DestType->isBooleanType();
1949 if ((Self.Context.getTypeSize(SrcType) >
1950 Self.Context.getTypeSize(DestType)) &&
1951 !MicrosoftException) {
1952 msg = diag::err_bad_reinterpret_cast_small_int;
1953 return TC_Failed;
1954 }
1955 Kind = CK_PointerToIntegral;
1956 return TC_Success;
1957 }
1958
1959 if (SrcType->isIntegralOrEnumerationType()) {
1960 assert(destIsPtr && "One type must be a pointer");
1961 checkIntToPointerCast(CStyle, OpRange.getBegin(), SrcExpr.get(), DestType,
1962 Self);
1963 // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly
1964 // converted to a pointer.
1965 // C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not
1966 // necessarily converted to a null pointer value.]
1967 Kind = CK_IntegralToPointer;
1968 return TC_Success;
1969 }
1970
1971 if (!destIsPtr || !srcIsPtr) {
1972 // With the valid non-pointer conversions out of the way, we can be even
1973 // more stringent.
1974 return TC_NotApplicable;
1975 }
1976
1977 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness.
1978 // The C-style cast operator can.
1979 if (CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle,
1980 /*CheckObjCLifetime=*/CStyle)) {
1981 msg = diag::err_bad_cxx_cast_qualifiers_away;
1982 return TC_Failed;
1983 }
1984
1985 // Cannot convert between block pointers and Objective-C object pointers.
1986 if ((SrcType->isBlockPointerType() && DestType->isObjCObjectPointerType()) ||
1987 (DestType->isBlockPointerType() && SrcType->isObjCObjectPointerType()))
1988 return TC_NotApplicable;
1989
1990 if (IsLValueCast) {
1991 Kind = CK_LValueBitCast;
1992 } else if (DestType->isObjCObjectPointerType()) {
1993 Kind = Self.PrepareCastToObjCObjectPointer(SrcExpr);
1994 } else if (DestType->isBlockPointerType()) {
1995 if (!SrcType->isBlockPointerType()) {
1996 Kind = CK_AnyPointerToBlockPointerCast;
1997 } else {
1998 Kind = CK_BitCast;
1999 }
2000 } else {
2001 Kind = CK_BitCast;
2002 }
2003
2004 // Any pointer can be cast to an Objective-C pointer type with a C-style
2005 // cast.
2006 if (CStyle && DestType->isObjCObjectPointerType()) {
2007 return TC_Success;
2008 }
2009 if (CStyle)
2010 DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType);
2011
2012 // Not casting away constness, so the only remaining check is for compatible
2013 // pointer categories.
2014
2015 if (SrcType->isFunctionPointerType()) {
2016 if (DestType->isFunctionPointerType()) {
2017 // C++ 5.2.10p6: A pointer to a function can be explicitly converted to
2018 // a pointer to a function of a different type.
2019 return TC_Success;
2020 }
2021
2022 // C++0x 5.2.10p8: Converting a pointer to a function into a pointer to
2023 // an object type or vice versa is conditionally-supported.
2024 // Compilers support it in C++03 too, though, because it's necessary for
2025 // casting the return value of dlsym() and GetProcAddress().
2026 // FIXME: Conditionally-supported behavior should be configurable in the
2027 // TargetInfo or similar.
2028 Self.Diag(OpRange.getBegin(),
2029 Self.getLangOpts().CPlusPlus11 ?
2030 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj)
2031 << OpRange;
2032 return TC_Success;
2033 }
2034
2035 if (DestType->isFunctionPointerType()) {
2036 // See above.
2037 Self.Diag(OpRange.getBegin(),
2038 Self.getLangOpts().CPlusPlus11 ?
2039 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj)
2040 << OpRange;
2041 return TC_Success;
2042 }
2043
2044 // C++ 5.2.10p7: A pointer to an object can be explicitly converted to
2045 // a pointer to an object of different type.
2046 // Void pointers are not specified, but supported by every compiler out there.
2047 // So we finish by allowing everything that remains - it's got to be two
2048 // object pointers.
2049 return TC_Success;
2050 }
2051
CheckCXXCStyleCast(bool FunctionalStyle,bool ListInitialization)2052 void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle,
2053 bool ListInitialization) {
2054 // Handle placeholders.
2055 if (isPlaceholder()) {
2056 // C-style casts can resolve __unknown_any types.
2057 if (claimPlaceholder(BuiltinType::UnknownAny)) {
2058 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType,
2059 SrcExpr.get(), Kind,
2060 ValueKind, BasePath);
2061 return;
2062 }
2063
2064 checkNonOverloadPlaceholders();
2065 if (SrcExpr.isInvalid())
2066 return;
2067 }
2068
2069 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
2070 // This test is outside everything else because it's the only case where
2071 // a non-lvalue-reference target type does not lead to decay.
2072 if (DestType->isVoidType()) {
2073 Kind = CK_ToVoid;
2074
2075 if (claimPlaceholder(BuiltinType::Overload)) {
2076 Self.ResolveAndFixSingleFunctionTemplateSpecialization(
2077 SrcExpr, /* Decay Function to ptr */ false,
2078 /* Complain */ true, DestRange, DestType,
2079 diag::err_bad_cstyle_cast_overload);
2080 if (SrcExpr.isInvalid())
2081 return;
2082 }
2083
2084 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
2085 return;
2086 }
2087
2088 // If the type is dependent, we won't do any other semantic analysis now.
2089 if (DestType->isDependentType() || SrcExpr.get()->isTypeDependent() ||
2090 SrcExpr.get()->isValueDependent()) {
2091 assert(Kind == CK_Dependent);
2092 return;
2093 }
2094
2095 if (ValueKind == VK_RValue && !DestType->isRecordType() &&
2096 !isPlaceholder(BuiltinType::Overload)) {
2097 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
2098 if (SrcExpr.isInvalid())
2099 return;
2100 }
2101
2102 // AltiVec vector initialization with a single literal.
2103 if (const VectorType *vecTy = DestType->getAs<VectorType>())
2104 if (vecTy->getVectorKind() == VectorType::AltiVecVector
2105 && (SrcExpr.get()->getType()->isIntegerType()
2106 || SrcExpr.get()->getType()->isFloatingType())) {
2107 Kind = CK_VectorSplat;
2108 return;
2109 }
2110
2111 // C++ [expr.cast]p5: The conversions performed by
2112 // - a const_cast,
2113 // - a static_cast,
2114 // - a static_cast followed by a const_cast,
2115 // - a reinterpret_cast, or
2116 // - a reinterpret_cast followed by a const_cast,
2117 // can be performed using the cast notation of explicit type conversion.
2118 // [...] If a conversion can be interpreted in more than one of the ways
2119 // listed above, the interpretation that appears first in the list is used,
2120 // even if a cast resulting from that interpretation is ill-formed.
2121 // In plain language, this means trying a const_cast ...
2122 unsigned msg = diag::err_bad_cxx_cast_generic;
2123 TryCastResult tcr = TryConstCast(Self, SrcExpr, DestType,
2124 /*CStyle*/true, msg);
2125 if (SrcExpr.isInvalid())
2126 return;
2127 if (tcr == TC_Success)
2128 Kind = CK_NoOp;
2129
2130 Sema::CheckedConversionKind CCK
2131 = FunctionalStyle? Sema::CCK_FunctionalCast
2132 : Sema::CCK_CStyleCast;
2133 if (tcr == TC_NotApplicable) {
2134 // ... or if that is not possible, a static_cast, ignoring const, ...
2135 tcr = TryStaticCast(Self, SrcExpr, DestType, CCK, OpRange,
2136 msg, Kind, BasePath, ListInitialization);
2137 if (SrcExpr.isInvalid())
2138 return;
2139
2140 if (tcr == TC_NotApplicable) {
2141 // ... and finally a reinterpret_cast, ignoring const.
2142 tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/true,
2143 OpRange, msg, Kind);
2144 if (SrcExpr.isInvalid())
2145 return;
2146 }
2147 }
2148
2149 if (Self.getLangOpts().ObjCAutoRefCount && tcr == TC_Success)
2150 checkObjCARCConversion(CCK);
2151
2152 if (tcr != TC_Success && msg != 0) {
2153 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
2154 DeclAccessPair Found;
2155 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(),
2156 DestType,
2157 /*Complain*/ true,
2158 Found);
2159 if (Fn) {
2160 // If DestType is a function type (not to be confused with the function
2161 // pointer type), it will be possible to resolve the function address,
2162 // but the type cast should be considered as failure.
2163 OverloadExpr *OE = OverloadExpr::find(SrcExpr.get()).Expression;
2164 Self.Diag(OpRange.getBegin(), diag::err_bad_cstyle_cast_overload)
2165 << OE->getName() << DestType << OpRange
2166 << OE->getQualifierLoc().getSourceRange();
2167 Self.NoteAllOverloadCandidates(SrcExpr.get());
2168 }
2169 } else {
2170 diagnoseBadCast(Self, msg, (FunctionalStyle ? CT_Functional : CT_CStyle),
2171 OpRange, SrcExpr.get(), DestType, ListInitialization);
2172 }
2173 } else if (Kind == CK_BitCast) {
2174 checkCastAlign();
2175 }
2176
2177 // Clear out SrcExpr if there was a fatal error.
2178 if (tcr != TC_Success)
2179 SrcExpr = ExprError();
2180 }
2181
2182 /// DiagnoseBadFunctionCast - Warn whenever a function call is cast to a
2183 /// non-matching type. Such as enum function call to int, int call to
2184 /// pointer; etc. Cast to 'void' is an exception.
DiagnoseBadFunctionCast(Sema & Self,const ExprResult & SrcExpr,QualType DestType)2185 static void DiagnoseBadFunctionCast(Sema &Self, const ExprResult &SrcExpr,
2186 QualType DestType) {
2187 if (Self.Diags.isIgnored(diag::warn_bad_function_cast,
2188 SrcExpr.get()->getExprLoc()))
2189 return;
2190
2191 if (!isa<CallExpr>(SrcExpr.get()))
2192 return;
2193
2194 QualType SrcType = SrcExpr.get()->getType();
2195 if (DestType.getUnqualifiedType()->isVoidType())
2196 return;
2197 if ((SrcType->isAnyPointerType() || SrcType->isBlockPointerType())
2198 && (DestType->isAnyPointerType() || DestType->isBlockPointerType()))
2199 return;
2200 if (SrcType->isIntegerType() && DestType->isIntegerType() &&
2201 (SrcType->isBooleanType() == DestType->isBooleanType()) &&
2202 (SrcType->isEnumeralType() == DestType->isEnumeralType()))
2203 return;
2204 if (SrcType->isRealFloatingType() && DestType->isRealFloatingType())
2205 return;
2206 if (SrcType->isEnumeralType() && DestType->isEnumeralType())
2207 return;
2208 if (SrcType->isComplexType() && DestType->isComplexType())
2209 return;
2210 if (SrcType->isComplexIntegerType() && DestType->isComplexIntegerType())
2211 return;
2212
2213 Self.Diag(SrcExpr.get()->getExprLoc(),
2214 diag::warn_bad_function_cast)
2215 << SrcType << DestType << SrcExpr.get()->getSourceRange();
2216 }
2217
2218 /// Check the semantics of a C-style cast operation, in C.
CheckCStyleCast()2219 void CastOperation::CheckCStyleCast() {
2220 assert(!Self.getLangOpts().CPlusPlus);
2221
2222 // C-style casts can resolve __unknown_any types.
2223 if (claimPlaceholder(BuiltinType::UnknownAny)) {
2224 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType,
2225 SrcExpr.get(), Kind,
2226 ValueKind, BasePath);
2227 return;
2228 }
2229
2230 // C99 6.5.4p2: the cast type needs to be void or scalar and the expression
2231 // type needs to be scalar.
2232 if (DestType->isVoidType()) {
2233 // We don't necessarily do lvalue-to-rvalue conversions on this.
2234 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
2235 if (SrcExpr.isInvalid())
2236 return;
2237
2238 // Cast to void allows any expr type.
2239 Kind = CK_ToVoid;
2240 return;
2241 }
2242
2243 // Overloads are allowed with C extensions, so we need to support them.
2244 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
2245 DeclAccessPair DAP;
2246 if (FunctionDecl *FD = Self.ResolveAddressOfOverloadedFunction(
2247 SrcExpr.get(), DestType, /*Complain=*/true, DAP))
2248 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr.get(), DAP, FD);
2249 else
2250 return;
2251 assert(SrcExpr.isUsable());
2252 }
2253 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
2254 if (SrcExpr.isInvalid())
2255 return;
2256 QualType SrcType = SrcExpr.get()->getType();
2257
2258 assert(!SrcType->isPlaceholderType());
2259
2260 // OpenCL v1 s6.5: Casting a pointer to address space A to a pointer to
2261 // address space B is illegal.
2262 if (Self.getLangOpts().OpenCL && DestType->isPointerType() &&
2263 SrcType->isPointerType()) {
2264 const PointerType *DestPtr = DestType->getAs<PointerType>();
2265 if (!DestPtr->isAddressSpaceOverlapping(*SrcType->getAs<PointerType>())) {
2266 Self.Diag(OpRange.getBegin(),
2267 diag::err_typecheck_incompatible_address_space)
2268 << SrcType << DestType << Sema::AA_Casting
2269 << SrcExpr.get()->getSourceRange();
2270 SrcExpr = ExprError();
2271 return;
2272 }
2273 }
2274
2275 if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
2276 diag::err_typecheck_cast_to_incomplete)) {
2277 SrcExpr = ExprError();
2278 return;
2279 }
2280
2281 if (!DestType->isScalarType() && !DestType->isVectorType()) {
2282 const RecordType *DestRecordTy = DestType->getAs<RecordType>();
2283
2284 if (DestRecordTy && Self.Context.hasSameUnqualifiedType(DestType, SrcType)){
2285 // GCC struct/union extension: allow cast to self.
2286 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_nonscalar)
2287 << DestType << SrcExpr.get()->getSourceRange();
2288 Kind = CK_NoOp;
2289 return;
2290 }
2291
2292 // GCC's cast to union extension.
2293 if (DestRecordTy && DestRecordTy->getDecl()->isUnion()) {
2294 RecordDecl *RD = DestRecordTy->getDecl();
2295 RecordDecl::field_iterator Field, FieldEnd;
2296 for (Field = RD->field_begin(), FieldEnd = RD->field_end();
2297 Field != FieldEnd; ++Field) {
2298 if (Self.Context.hasSameUnqualifiedType(Field->getType(), SrcType) &&
2299 !Field->isUnnamedBitfield()) {
2300 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union)
2301 << SrcExpr.get()->getSourceRange();
2302 break;
2303 }
2304 }
2305 if (Field == FieldEnd) {
2306 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cast_to_union_no_type)
2307 << SrcType << SrcExpr.get()->getSourceRange();
2308 SrcExpr = ExprError();
2309 return;
2310 }
2311 Kind = CK_ToUnion;
2312 return;
2313 }
2314
2315 // Reject any other conversions to non-scalar types.
2316 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cond_expect_scalar)
2317 << DestType << SrcExpr.get()->getSourceRange();
2318 SrcExpr = ExprError();
2319 return;
2320 }
2321
2322 // The type we're casting to is known to be a scalar or vector.
2323
2324 // Require the operand to be a scalar or vector.
2325 if (!SrcType->isScalarType() && !SrcType->isVectorType()) {
2326 Self.Diag(SrcExpr.get()->getExprLoc(),
2327 diag::err_typecheck_expect_scalar_operand)
2328 << SrcType << SrcExpr.get()->getSourceRange();
2329 SrcExpr = ExprError();
2330 return;
2331 }
2332
2333 if (DestType->isExtVectorType()) {
2334 SrcExpr = Self.CheckExtVectorCast(OpRange, DestType, SrcExpr.get(), Kind);
2335 return;
2336 }
2337
2338 if (const VectorType *DestVecTy = DestType->getAs<VectorType>()) {
2339 if (DestVecTy->getVectorKind() == VectorType::AltiVecVector &&
2340 (SrcType->isIntegerType() || SrcType->isFloatingType())) {
2341 Kind = CK_VectorSplat;
2342 } else if (Self.CheckVectorCast(OpRange, DestType, SrcType, Kind)) {
2343 SrcExpr = ExprError();
2344 }
2345 return;
2346 }
2347
2348 if (SrcType->isVectorType()) {
2349 if (Self.CheckVectorCast(OpRange, SrcType, DestType, Kind))
2350 SrcExpr = ExprError();
2351 return;
2352 }
2353
2354 // The source and target types are both scalars, i.e.
2355 // - arithmetic types (fundamental, enum, and complex)
2356 // - all kinds of pointers
2357 // Note that member pointers were filtered out with C++, above.
2358
2359 if (isa<ObjCSelectorExpr>(SrcExpr.get())) {
2360 Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_selector_expr);
2361 SrcExpr = ExprError();
2362 return;
2363 }
2364
2365 // If either type is a pointer, the other type has to be either an
2366 // integer or a pointer.
2367 if (!DestType->isArithmeticType()) {
2368 if (!SrcType->isIntegralType(Self.Context) && SrcType->isArithmeticType()) {
2369 Self.Diag(SrcExpr.get()->getExprLoc(),
2370 diag::err_cast_pointer_from_non_pointer_int)
2371 << SrcType << SrcExpr.get()->getSourceRange();
2372 SrcExpr = ExprError();
2373 return;
2374 }
2375 checkIntToPointerCast(/* CStyle */ true, OpRange.getBegin(), SrcExpr.get(),
2376 DestType, Self);
2377 } else if (!SrcType->isArithmeticType()) {
2378 if (!DestType->isIntegralType(Self.Context) &&
2379 DestType->isArithmeticType()) {
2380 Self.Diag(SrcExpr.get()->getLocStart(),
2381 diag::err_cast_pointer_to_non_pointer_int)
2382 << DestType << SrcExpr.get()->getSourceRange();
2383 SrcExpr = ExprError();
2384 return;
2385 }
2386 }
2387
2388 if (Self.getLangOpts().OpenCL && !Self.getOpenCLOptions().cl_khr_fp16) {
2389 if (DestType->isHalfType()) {
2390 Self.Diag(SrcExpr.get()->getLocStart(), diag::err_opencl_cast_to_half)
2391 << DestType << SrcExpr.get()->getSourceRange();
2392 SrcExpr = ExprError();
2393 return;
2394 }
2395 }
2396
2397 // ARC imposes extra restrictions on casts.
2398 if (Self.getLangOpts().ObjCAutoRefCount) {
2399 checkObjCARCConversion(Sema::CCK_CStyleCast);
2400 if (SrcExpr.isInvalid())
2401 return;
2402
2403 if (const PointerType *CastPtr = DestType->getAs<PointerType>()) {
2404 if (const PointerType *ExprPtr = SrcType->getAs<PointerType>()) {
2405 Qualifiers CastQuals = CastPtr->getPointeeType().getQualifiers();
2406 Qualifiers ExprQuals = ExprPtr->getPointeeType().getQualifiers();
2407 if (CastPtr->getPointeeType()->isObjCLifetimeType() &&
2408 ExprPtr->getPointeeType()->isObjCLifetimeType() &&
2409 !CastQuals.compatiblyIncludesObjCLifetime(ExprQuals)) {
2410 Self.Diag(SrcExpr.get()->getLocStart(),
2411 diag::err_typecheck_incompatible_ownership)
2412 << SrcType << DestType << Sema::AA_Casting
2413 << SrcExpr.get()->getSourceRange();
2414 return;
2415 }
2416 }
2417 }
2418 else if (!Self.CheckObjCARCUnavailableWeakConversion(DestType, SrcType)) {
2419 Self.Diag(SrcExpr.get()->getLocStart(),
2420 diag::err_arc_convesion_of_weak_unavailable)
2421 << 1 << SrcType << DestType << SrcExpr.get()->getSourceRange();
2422 SrcExpr = ExprError();
2423 return;
2424 }
2425 }
2426
2427 DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType);
2428 DiagnoseBadFunctionCast(Self, SrcExpr, DestType);
2429 Kind = Self.PrepareScalarCast(SrcExpr, DestType);
2430 if (SrcExpr.isInvalid())
2431 return;
2432
2433 if (Kind == CK_BitCast)
2434 checkCastAlign();
2435
2436 // -Wcast-qual
2437 QualType TheOffendingSrcType, TheOffendingDestType;
2438 Qualifiers CastAwayQualifiers;
2439 if (SrcType->isAnyPointerType() && DestType->isAnyPointerType() &&
2440 CastsAwayConstness(Self, SrcType, DestType, true, false,
2441 &TheOffendingSrcType, &TheOffendingDestType,
2442 &CastAwayQualifiers)) {
2443 int qualifiers = -1;
2444 if (CastAwayQualifiers.hasConst() && CastAwayQualifiers.hasVolatile()) {
2445 qualifiers = 0;
2446 } else if (CastAwayQualifiers.hasConst()) {
2447 qualifiers = 1;
2448 } else if (CastAwayQualifiers.hasVolatile()) {
2449 qualifiers = 2;
2450 }
2451 // This is a variant of int **x; const int **y = (const int **)x;
2452 if (qualifiers == -1)
2453 Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual2) <<
2454 SrcType << DestType;
2455 else
2456 Self.Diag(SrcExpr.get()->getLocStart(), diag::warn_cast_qual) <<
2457 TheOffendingSrcType << TheOffendingDestType << qualifiers;
2458 }
2459 }
2460
BuildCStyleCastExpr(SourceLocation LPLoc,TypeSourceInfo * CastTypeInfo,SourceLocation RPLoc,Expr * CastExpr)2461 ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc,
2462 TypeSourceInfo *CastTypeInfo,
2463 SourceLocation RPLoc,
2464 Expr *CastExpr) {
2465 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr);
2466 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange();
2467 Op.OpRange = SourceRange(LPLoc, CastExpr->getLocEnd());
2468
2469 if (getLangOpts().CPlusPlus) {
2470 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/ false,
2471 isa<InitListExpr>(CastExpr));
2472 } else {
2473 Op.CheckCStyleCast();
2474 }
2475
2476 if (Op.SrcExpr.isInvalid())
2477 return ExprError();
2478
2479 return Op.complete(CStyleCastExpr::Create(Context, Op.ResultType,
2480 Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
2481 &Op.BasePath, CastTypeInfo, LPLoc, RPLoc));
2482 }
2483
BuildCXXFunctionalCastExpr(TypeSourceInfo * CastTypeInfo,SourceLocation LPLoc,Expr * CastExpr,SourceLocation RPLoc)2484 ExprResult Sema::BuildCXXFunctionalCastExpr(TypeSourceInfo *CastTypeInfo,
2485 SourceLocation LPLoc,
2486 Expr *CastExpr,
2487 SourceLocation RPLoc) {
2488 assert(LPLoc.isValid() && "List-initialization shouldn't get here.");
2489 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr);
2490 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange();
2491 Op.OpRange = SourceRange(Op.DestRange.getBegin(), CastExpr->getLocEnd());
2492
2493 Op.CheckCXXCStyleCast(/*FunctionalStyle=*/true, /*ListInit=*/false);
2494 if (Op.SrcExpr.isInvalid())
2495 return ExprError();
2496
2497 auto *SubExpr = Op.SrcExpr.get();
2498 if (auto *BindExpr = dyn_cast<CXXBindTemporaryExpr>(SubExpr))
2499 SubExpr = BindExpr->getSubExpr();
2500 if (auto *ConstructExpr = dyn_cast<CXXConstructExpr>(SubExpr))
2501 ConstructExpr->setParenOrBraceRange(SourceRange(LPLoc, RPLoc));
2502
2503 return Op.complete(CXXFunctionalCastExpr::Create(Context, Op.ResultType,
2504 Op.ValueKind, CastTypeInfo, Op.Kind,
2505 Op.SrcExpr.get(), &Op.BasePath, LPLoc, RPLoc));
2506 }
2507