1 //===--- SemaCast.cpp - Semantic Analysis for Casts -----------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements semantic analysis for cast expressions, including
10 // 1) C-style casts like '(int) x'
11 // 2) C++ functional casts like 'int(x)'
12 // 3) C++ named casts like 'static_cast<int>(x)'
13 //
14 //===----------------------------------------------------------------------===//
15
16 #include "clang/Sema/SemaInternal.h"
17 #include "clang/AST/ASTContext.h"
18 #include "clang/AST/CXXInheritance.h"
19 #include "clang/AST/ExprCXX.h"
20 #include "clang/AST/ExprObjC.h"
21 #include "clang/AST/RecordLayout.h"
22 #include "clang/Basic/PartialDiagnostic.h"
23 #include "clang/Basic/TargetInfo.h"
24 #include "clang/Lex/Preprocessor.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_Extension, ///< The cast method is appropriate and accepted as a
36 ///< language extension.
37 TC_Failed ///< The cast method is appropriate, but failed. A
38 ///< diagnostic has been emitted.
39 };
40
isValidCast(TryCastResult TCR)41 static bool isValidCast(TryCastResult TCR) {
42 return TCR == TC_Success || TCR == TC_Extension;
43 }
44
45 enum CastType {
46 CT_Const, ///< const_cast
47 CT_Static, ///< static_cast
48 CT_Reinterpret, ///< reinterpret_cast
49 CT_Dynamic, ///< dynamic_cast
50 CT_CStyle, ///< (Type)expr
51 CT_Functional, ///< Type(expr)
52 CT_Addrspace ///< addrspace_cast
53 };
54
55 namespace {
56 struct CastOperation {
CastOperation__anon3d33b4f20111::CastOperation57 CastOperation(Sema &S, QualType destType, ExprResult src)
58 : Self(S), SrcExpr(src), DestType(destType),
59 ResultType(destType.getNonLValueExprType(S.Context)),
60 ValueKind(Expr::getValueKindForType(destType)),
61 Kind(CK_Dependent), IsARCUnbridgedCast(false) {
62
63 if (const BuiltinType *placeholder =
64 src.get()->getType()->getAsPlaceholderType()) {
65 PlaceholderKind = placeholder->getKind();
66 } else {
67 PlaceholderKind = (BuiltinType::Kind) 0;
68 }
69 }
70
71 Sema &Self;
72 ExprResult SrcExpr;
73 QualType DestType;
74 QualType ResultType;
75 ExprValueKind ValueKind;
76 CastKind Kind;
77 BuiltinType::Kind PlaceholderKind;
78 CXXCastPath BasePath;
79 bool IsARCUnbridgedCast;
80
81 SourceRange OpRange;
82 SourceRange DestRange;
83
84 // Top-level semantics-checking routines.
85 void CheckConstCast();
86 void CheckReinterpretCast();
87 void CheckStaticCast();
88 void CheckDynamicCast();
89 void CheckCXXCStyleCast(bool FunctionalCast, bool ListInitialization);
90 void CheckCStyleCast();
91 void CheckBuiltinBitCast();
92 void CheckAddrspaceCast();
93
updatePartOfExplicitCastFlags__anon3d33b4f20111::CastOperation94 void updatePartOfExplicitCastFlags(CastExpr *CE) {
95 // Walk down from the CE to the OrigSrcExpr, and mark all immediate
96 // ImplicitCastExpr's as being part of ExplicitCastExpr. The original CE
97 // (which is a ExplicitCastExpr), and the OrigSrcExpr are not touched.
98 for (; auto *ICE = dyn_cast<ImplicitCastExpr>(CE->getSubExpr()); CE = ICE)
99 ICE->setIsPartOfExplicitCast(true);
100 }
101
102 /// Complete an apparently-successful cast operation that yields
103 /// the given expression.
complete__anon3d33b4f20111::CastOperation104 ExprResult complete(CastExpr *castExpr) {
105 // If this is an unbridged cast, wrap the result in an implicit
106 // cast that yields the unbridged-cast placeholder type.
107 if (IsARCUnbridgedCast) {
108 castExpr = ImplicitCastExpr::Create(Self.Context,
109 Self.Context.ARCUnbridgedCastTy,
110 CK_Dependent, castExpr, nullptr,
111 castExpr->getValueKind());
112 }
113 updatePartOfExplicitCastFlags(castExpr);
114 return castExpr;
115 }
116
117 // Internal convenience methods.
118
119 /// Try to handle the given placeholder expression kind. Return
120 /// true if the source expression has the appropriate placeholder
121 /// kind. A placeholder can only be claimed once.
claimPlaceholder__anon3d33b4f20111::CastOperation122 bool claimPlaceholder(BuiltinType::Kind K) {
123 if (PlaceholderKind != K) return false;
124
125 PlaceholderKind = (BuiltinType::Kind) 0;
126 return true;
127 }
128
isPlaceholder__anon3d33b4f20111::CastOperation129 bool isPlaceholder() const {
130 return PlaceholderKind != 0;
131 }
isPlaceholder__anon3d33b4f20111::CastOperation132 bool isPlaceholder(BuiltinType::Kind K) const {
133 return PlaceholderKind == K;
134 }
135
136 // Language specific cast restrictions for address spaces.
137 void checkAddressSpaceCast(QualType SrcType, QualType DestType);
138
checkCastAlign__anon3d33b4f20111::CastOperation139 void checkCastAlign() {
140 Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange);
141 }
142
checkObjCConversion__anon3d33b4f20111::CastOperation143 void checkObjCConversion(Sema::CheckedConversionKind CCK) {
144 assert(Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers());
145
146 Expr *src = SrcExpr.get();
147 if (Self.CheckObjCConversion(OpRange, DestType, src, CCK) ==
148 Sema::ACR_unbridged)
149 IsARCUnbridgedCast = true;
150 SrcExpr = src;
151 }
152
153 /// Check for and handle non-overload placeholder expressions.
checkNonOverloadPlaceholders__anon3d33b4f20111::CastOperation154 void checkNonOverloadPlaceholders() {
155 if (!isPlaceholder() || isPlaceholder(BuiltinType::Overload))
156 return;
157
158 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
159 if (SrcExpr.isInvalid())
160 return;
161 PlaceholderKind = (BuiltinType::Kind) 0;
162 }
163 };
164
CheckNoDeref(Sema & S,const QualType FromType,const QualType ToType,SourceLocation OpLoc)165 void CheckNoDeref(Sema &S, const QualType FromType, const QualType ToType,
166 SourceLocation OpLoc) {
167 if (const auto *PtrType = dyn_cast<PointerType>(FromType)) {
168 if (PtrType->getPointeeType()->hasAttr(attr::NoDeref)) {
169 if (const auto *DestType = dyn_cast<PointerType>(ToType)) {
170 if (!DestType->getPointeeType()->hasAttr(attr::NoDeref)) {
171 S.Diag(OpLoc, diag::warn_noderef_to_dereferenceable_pointer);
172 }
173 }
174 }
175 }
176 }
177
178 struct CheckNoDerefRAII {
CheckNoDerefRAII__anon3d33b4f20111::CheckNoDerefRAII179 CheckNoDerefRAII(CastOperation &Op) : Op(Op) {}
~CheckNoDerefRAII__anon3d33b4f20111::CheckNoDerefRAII180 ~CheckNoDerefRAII() {
181 if (!Op.SrcExpr.isInvalid())
182 CheckNoDeref(Op.Self, Op.SrcExpr.get()->getType(), Op.ResultType,
183 Op.OpRange.getBegin());
184 }
185
186 CastOperation &Op;
187 };
188 }
189
190 static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr,
191 QualType DestType);
192
193 // The Try functions attempt a specific way of casting. If they succeed, they
194 // return TC_Success. If their way of casting is not appropriate for the given
195 // arguments, they return TC_NotApplicable and *may* set diag to a diagnostic
196 // to emit if no other way succeeds. If their way of casting is appropriate but
197 // fails, they return TC_Failed and *must* set diag; they can set it to 0 if
198 // they emit a specialized diagnostic.
199 // All diagnostics returned by these functions must expect the same three
200 // arguments:
201 // %0: Cast Type (a value from the CastType enumeration)
202 // %1: Source Type
203 // %2: Destination Type
204 static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr,
205 QualType DestType, bool CStyle,
206 CastKind &Kind,
207 CXXCastPath &BasePath,
208 unsigned &msg);
209 static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr,
210 QualType DestType, bool CStyle,
211 SourceRange OpRange,
212 unsigned &msg,
213 CastKind &Kind,
214 CXXCastPath &BasePath);
215 static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType,
216 QualType DestType, bool CStyle,
217 SourceRange OpRange,
218 unsigned &msg,
219 CastKind &Kind,
220 CXXCastPath &BasePath);
221 static TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType,
222 CanQualType DestType, bool CStyle,
223 SourceRange OpRange,
224 QualType OrigSrcType,
225 QualType OrigDestType, unsigned &msg,
226 CastKind &Kind,
227 CXXCastPath &BasePath);
228 static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr,
229 QualType SrcType,
230 QualType DestType,bool CStyle,
231 SourceRange OpRange,
232 unsigned &msg,
233 CastKind &Kind,
234 CXXCastPath &BasePath);
235
236 static TryCastResult TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr,
237 QualType DestType,
238 Sema::CheckedConversionKind CCK,
239 SourceRange OpRange,
240 unsigned &msg, CastKind &Kind,
241 bool ListInitialization);
242 static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
243 QualType DestType,
244 Sema::CheckedConversionKind CCK,
245 SourceRange OpRange,
246 unsigned &msg, CastKind &Kind,
247 CXXCastPath &BasePath,
248 bool ListInitialization);
249 static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr,
250 QualType DestType, bool CStyle,
251 unsigned &msg);
252 static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
253 QualType DestType, bool CStyle,
254 SourceRange OpRange, unsigned &msg,
255 CastKind &Kind);
256 static TryCastResult TryAddressSpaceCast(Sema &Self, ExprResult &SrcExpr,
257 QualType DestType, bool CStyle,
258 unsigned &msg, CastKind &Kind);
259
260 /// ActOnCXXNamedCast - Parse
261 /// {dynamic,static,reinterpret,const,addrspace}_cast's.
262 ExprResult
ActOnCXXNamedCast(SourceLocation OpLoc,tok::TokenKind Kind,SourceLocation LAngleBracketLoc,Declarator & D,SourceLocation RAngleBracketLoc,SourceLocation LParenLoc,Expr * E,SourceLocation RParenLoc)263 Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
264 SourceLocation LAngleBracketLoc, Declarator &D,
265 SourceLocation RAngleBracketLoc,
266 SourceLocation LParenLoc, Expr *E,
267 SourceLocation RParenLoc) {
268
269 assert(!D.isInvalidType());
270
271 TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, E->getType());
272 if (D.isInvalidType())
273 return ExprError();
274
275 if (getLangOpts().CPlusPlus) {
276 // Check that there are no default arguments (C++ only).
277 CheckExtraCXXDefaultArguments(D);
278 }
279
280 return BuildCXXNamedCast(OpLoc, Kind, TInfo, E,
281 SourceRange(LAngleBracketLoc, RAngleBracketLoc),
282 SourceRange(LParenLoc, RParenLoc));
283 }
284
285 ExprResult
BuildCXXNamedCast(SourceLocation OpLoc,tok::TokenKind Kind,TypeSourceInfo * DestTInfo,Expr * E,SourceRange AngleBrackets,SourceRange Parens)286 Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
287 TypeSourceInfo *DestTInfo, Expr *E,
288 SourceRange AngleBrackets, SourceRange Parens) {
289 ExprResult Ex = E;
290 QualType DestType = DestTInfo->getType();
291
292 // If the type is dependent, we won't do the semantic analysis now.
293 bool TypeDependent =
294 DestType->isDependentType() || Ex.get()->isTypeDependent();
295
296 CastOperation Op(*this, DestType, E);
297 Op.OpRange = SourceRange(OpLoc, Parens.getEnd());
298 Op.DestRange = AngleBrackets;
299
300 switch (Kind) {
301 default: llvm_unreachable("Unknown C++ cast!");
302
303 case tok::kw_addrspace_cast:
304 if (!TypeDependent) {
305 Op.CheckAddrspaceCast();
306 if (Op.SrcExpr.isInvalid())
307 return ExprError();
308 }
309 return Op.complete(CXXAddrspaceCastExpr::Create(
310 Context, Op.ResultType, Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
311 DestTInfo, OpLoc, Parens.getEnd(), AngleBrackets));
312
313 case tok::kw_const_cast:
314 if (!TypeDependent) {
315 Op.CheckConstCast();
316 if (Op.SrcExpr.isInvalid())
317 return ExprError();
318 DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
319 }
320 return Op.complete(CXXConstCastExpr::Create(Context, Op.ResultType,
321 Op.ValueKind, Op.SrcExpr.get(), DestTInfo,
322 OpLoc, Parens.getEnd(),
323 AngleBrackets));
324
325 case tok::kw_dynamic_cast: {
326 // dynamic_cast is not supported in C++ for OpenCL.
327 if (getLangOpts().OpenCLCPlusPlus) {
328 return ExprError(Diag(OpLoc, diag::err_openclcxx_not_supported)
329 << "dynamic_cast");
330 }
331
332 if (!TypeDependent) {
333 Op.CheckDynamicCast();
334 if (Op.SrcExpr.isInvalid())
335 return ExprError();
336 }
337 return Op.complete(CXXDynamicCastExpr::Create(Context, Op.ResultType,
338 Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
339 &Op.BasePath, DestTInfo,
340 OpLoc, Parens.getEnd(),
341 AngleBrackets));
342 }
343 case tok::kw_reinterpret_cast: {
344 if (!TypeDependent) {
345 Op.CheckReinterpretCast();
346 if (Op.SrcExpr.isInvalid())
347 return ExprError();
348 DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
349 }
350 return Op.complete(CXXReinterpretCastExpr::Create(Context, Op.ResultType,
351 Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
352 nullptr, DestTInfo, OpLoc,
353 Parens.getEnd(),
354 AngleBrackets));
355 }
356 case tok::kw_static_cast: {
357 if (!TypeDependent) {
358 Op.CheckStaticCast();
359 if (Op.SrcExpr.isInvalid())
360 return ExprError();
361 DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
362 }
363
364 return Op.complete(CXXStaticCastExpr::Create(Context, Op.ResultType,
365 Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
366 &Op.BasePath, DestTInfo,
367 OpLoc, Parens.getEnd(),
368 AngleBrackets));
369 }
370 }
371 }
372
ActOnBuiltinBitCastExpr(SourceLocation KWLoc,Declarator & D,ExprResult Operand,SourceLocation RParenLoc)373 ExprResult Sema::ActOnBuiltinBitCastExpr(SourceLocation KWLoc, Declarator &D,
374 ExprResult Operand,
375 SourceLocation RParenLoc) {
376 assert(!D.isInvalidType());
377
378 TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, Operand.get()->getType());
379 if (D.isInvalidType())
380 return ExprError();
381
382 return BuildBuiltinBitCastExpr(KWLoc, TInfo, Operand.get(), RParenLoc);
383 }
384
BuildBuiltinBitCastExpr(SourceLocation KWLoc,TypeSourceInfo * TSI,Expr * Operand,SourceLocation RParenLoc)385 ExprResult Sema::BuildBuiltinBitCastExpr(SourceLocation KWLoc,
386 TypeSourceInfo *TSI, Expr *Operand,
387 SourceLocation RParenLoc) {
388 CastOperation Op(*this, TSI->getType(), Operand);
389 Op.OpRange = SourceRange(KWLoc, RParenLoc);
390 TypeLoc TL = TSI->getTypeLoc();
391 Op.DestRange = SourceRange(TL.getBeginLoc(), TL.getEndLoc());
392
393 if (!Operand->isTypeDependent() && !TSI->getType()->isDependentType()) {
394 Op.CheckBuiltinBitCast();
395 if (Op.SrcExpr.isInvalid())
396 return ExprError();
397 }
398
399 BuiltinBitCastExpr *BCE =
400 new (Context) BuiltinBitCastExpr(Op.ResultType, Op.ValueKind, Op.Kind,
401 Op.SrcExpr.get(), TSI, KWLoc, RParenLoc);
402 return Op.complete(BCE);
403 }
404
405 /// Try to diagnose a failed overloaded cast. Returns true if
406 /// diagnostics were emitted.
tryDiagnoseOverloadedCast(Sema & S,CastType CT,SourceRange range,Expr * src,QualType destType,bool listInitialization)407 static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT,
408 SourceRange range, Expr *src,
409 QualType destType,
410 bool listInitialization) {
411 switch (CT) {
412 // These cast kinds don't consider user-defined conversions.
413 case CT_Const:
414 case CT_Reinterpret:
415 case CT_Dynamic:
416 case CT_Addrspace:
417 return false;
418
419 // These do.
420 case CT_Static:
421 case CT_CStyle:
422 case CT_Functional:
423 break;
424 }
425
426 QualType srcType = src->getType();
427 if (!destType->isRecordType() && !srcType->isRecordType())
428 return false;
429
430 InitializedEntity entity = InitializedEntity::InitializeTemporary(destType);
431 InitializationKind initKind
432 = (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(),
433 range, listInitialization)
434 : (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range,
435 listInitialization)
436 : InitializationKind::CreateCast(/*type range?*/ range);
437 InitializationSequence sequence(S, entity, initKind, src);
438
439 assert(sequence.Failed() && "initialization succeeded on second try?");
440 switch (sequence.getFailureKind()) {
441 default: return false;
442
443 case InitializationSequence::FK_ConstructorOverloadFailed:
444 case InitializationSequence::FK_UserConversionOverloadFailed:
445 break;
446 }
447
448 OverloadCandidateSet &candidates = sequence.getFailedCandidateSet();
449
450 unsigned msg = 0;
451 OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates;
452
453 switch (sequence.getFailedOverloadResult()) {
454 case OR_Success: llvm_unreachable("successful failed overload");
455 case OR_No_Viable_Function:
456 if (candidates.empty())
457 msg = diag::err_ovl_no_conversion_in_cast;
458 else
459 msg = diag::err_ovl_no_viable_conversion_in_cast;
460 howManyCandidates = OCD_AllCandidates;
461 break;
462
463 case OR_Ambiguous:
464 msg = diag::err_ovl_ambiguous_conversion_in_cast;
465 howManyCandidates = OCD_AmbiguousCandidates;
466 break;
467
468 case OR_Deleted:
469 msg = diag::err_ovl_deleted_conversion_in_cast;
470 howManyCandidates = OCD_ViableCandidates;
471 break;
472 }
473
474 candidates.NoteCandidates(
475 PartialDiagnosticAt(range.getBegin(),
476 S.PDiag(msg) << CT << srcType << destType << range
477 << src->getSourceRange()),
478 S, howManyCandidates, src);
479
480 return true;
481 }
482
483 /// Diagnose a failed cast.
diagnoseBadCast(Sema & S,unsigned msg,CastType castType,SourceRange opRange,Expr * src,QualType destType,bool listInitialization)484 static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType,
485 SourceRange opRange, Expr *src, QualType destType,
486 bool listInitialization) {
487 if (msg == diag::err_bad_cxx_cast_generic &&
488 tryDiagnoseOverloadedCast(S, castType, opRange, src, destType,
489 listInitialization))
490 return;
491
492 S.Diag(opRange.getBegin(), msg) << castType
493 << src->getType() << destType << opRange << src->getSourceRange();
494
495 // Detect if both types are (ptr to) class, and note any incompleteness.
496 int DifferentPtrness = 0;
497 QualType From = destType;
498 if (auto Ptr = From->getAs<PointerType>()) {
499 From = Ptr->getPointeeType();
500 DifferentPtrness++;
501 }
502 QualType To = src->getType();
503 if (auto Ptr = To->getAs<PointerType>()) {
504 To = Ptr->getPointeeType();
505 DifferentPtrness--;
506 }
507 if (!DifferentPtrness) {
508 auto RecFrom = From->getAs<RecordType>();
509 auto RecTo = To->getAs<RecordType>();
510 if (RecFrom && RecTo) {
511 auto DeclFrom = RecFrom->getAsCXXRecordDecl();
512 if (!DeclFrom->isCompleteDefinition())
513 S.Diag(DeclFrom->getLocation(), diag::note_type_incomplete)
514 << DeclFrom->getDeclName();
515 auto DeclTo = RecTo->getAsCXXRecordDecl();
516 if (!DeclTo->isCompleteDefinition())
517 S.Diag(DeclTo->getLocation(), diag::note_type_incomplete)
518 << DeclTo->getDeclName();
519 }
520 }
521 }
522
523 namespace {
524 /// The kind of unwrapping we did when determining whether a conversion casts
525 /// away constness.
526 enum CastAwayConstnessKind {
527 /// The conversion does not cast away constness.
528 CACK_None = 0,
529 /// We unwrapped similar types.
530 CACK_Similar = 1,
531 /// We unwrapped dissimilar types with similar representations (eg, a pointer
532 /// versus an Objective-C object pointer).
533 CACK_SimilarKind = 2,
534 /// We unwrapped representationally-unrelated types, such as a pointer versus
535 /// a pointer-to-member.
536 CACK_Incoherent = 3,
537 };
538 }
539
540 /// Unwrap one level of types for CastsAwayConstness.
541 ///
542 /// Like Sema::UnwrapSimilarTypes, this removes one level of indirection from
543 /// both types, provided that they're both pointer-like or array-like. Unlike
544 /// the Sema function, doesn't care if the unwrapped pieces are related.
545 ///
546 /// This function may remove additional levels as necessary for correctness:
547 /// the resulting T1 is unwrapped sufficiently that it is never an array type,
548 /// so that its qualifiers can be directly compared to those of T2 (which will
549 /// have the combined set of qualifiers from all indermediate levels of T2),
550 /// as (effectively) required by [expr.const.cast]p7 replacing T1's qualifiers
551 /// with those from T2.
552 static CastAwayConstnessKind
unwrapCastAwayConstnessLevel(ASTContext & Context,QualType & T1,QualType & T2)553 unwrapCastAwayConstnessLevel(ASTContext &Context, QualType &T1, QualType &T2) {
554 enum { None, Ptr, MemPtr, BlockPtr, Array };
555 auto Classify = [](QualType T) {
556 if (T->isAnyPointerType()) return Ptr;
557 if (T->isMemberPointerType()) return MemPtr;
558 if (T->isBlockPointerType()) return BlockPtr;
559 // We somewhat-arbitrarily don't look through VLA types here. This is at
560 // least consistent with the behavior of UnwrapSimilarTypes.
561 if (T->isConstantArrayType() || T->isIncompleteArrayType()) return Array;
562 return None;
563 };
564
565 auto Unwrap = [&](QualType T) {
566 if (auto *AT = Context.getAsArrayType(T))
567 return AT->getElementType();
568 return T->getPointeeType();
569 };
570
571 CastAwayConstnessKind Kind;
572
573 if (T2->isReferenceType()) {
574 // Special case: if the destination type is a reference type, unwrap it as
575 // the first level. (The source will have been an lvalue expression in this
576 // case, so there is no corresponding "reference to" in T1 to remove.) This
577 // simulates removing a "pointer to" from both sides.
578 T2 = T2->getPointeeType();
579 Kind = CastAwayConstnessKind::CACK_Similar;
580 } else if (Context.UnwrapSimilarTypes(T1, T2)) {
581 Kind = CastAwayConstnessKind::CACK_Similar;
582 } else {
583 // Try unwrapping mismatching levels.
584 int T1Class = Classify(T1);
585 if (T1Class == None)
586 return CastAwayConstnessKind::CACK_None;
587
588 int T2Class = Classify(T2);
589 if (T2Class == None)
590 return CastAwayConstnessKind::CACK_None;
591
592 T1 = Unwrap(T1);
593 T2 = Unwrap(T2);
594 Kind = T1Class == T2Class ? CastAwayConstnessKind::CACK_SimilarKind
595 : CastAwayConstnessKind::CACK_Incoherent;
596 }
597
598 // We've unwrapped at least one level. If the resulting T1 is a (possibly
599 // multidimensional) array type, any qualifier on any matching layer of
600 // T2 is considered to correspond to T1. Decompose down to the element
601 // type of T1 so that we can compare properly.
602 while (true) {
603 Context.UnwrapSimilarArrayTypes(T1, T2);
604
605 if (Classify(T1) != Array)
606 break;
607
608 auto T2Class = Classify(T2);
609 if (T2Class == None)
610 break;
611
612 if (T2Class != Array)
613 Kind = CastAwayConstnessKind::CACK_Incoherent;
614 else if (Kind != CastAwayConstnessKind::CACK_Incoherent)
615 Kind = CastAwayConstnessKind::CACK_SimilarKind;
616
617 T1 = Unwrap(T1);
618 T2 = Unwrap(T2).withCVRQualifiers(T2.getCVRQualifiers());
619 }
620
621 return Kind;
622 }
623
624 /// Check if the pointer conversion from SrcType to DestType casts away
625 /// constness as defined in C++ [expr.const.cast]. This is used by the cast
626 /// checkers. Both arguments must denote pointer (possibly to member) types.
627 ///
628 /// \param CheckCVR Whether to check for const/volatile/restrict qualifiers.
629 /// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers.
630 static CastAwayConstnessKind
CastsAwayConstness(Sema & Self,QualType SrcType,QualType DestType,bool CheckCVR,bool CheckObjCLifetime,QualType * TheOffendingSrcType=nullptr,QualType * TheOffendingDestType=nullptr,Qualifiers * CastAwayQualifiers=nullptr)631 CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType,
632 bool CheckCVR, bool CheckObjCLifetime,
633 QualType *TheOffendingSrcType = nullptr,
634 QualType *TheOffendingDestType = nullptr,
635 Qualifiers *CastAwayQualifiers = nullptr) {
636 // If the only checking we care about is for Objective-C lifetime qualifiers,
637 // and we're not in ObjC mode, there's nothing to check.
638 if (!CheckCVR && CheckObjCLifetime && !Self.Context.getLangOpts().ObjC)
639 return CastAwayConstnessKind::CACK_None;
640
641 if (!DestType->isReferenceType()) {
642 assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() ||
643 SrcType->isBlockPointerType()) &&
644 "Source type is not pointer or pointer to member.");
645 assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() ||
646 DestType->isBlockPointerType()) &&
647 "Destination type is not pointer or pointer to member.");
648 }
649
650 QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType),
651 UnwrappedDestType = Self.Context.getCanonicalType(DestType);
652
653 // Find the qualifiers. We only care about cvr-qualifiers for the
654 // purpose of this check, because other qualifiers (address spaces,
655 // Objective-C GC, etc.) are part of the type's identity.
656 QualType PrevUnwrappedSrcType = UnwrappedSrcType;
657 QualType PrevUnwrappedDestType = UnwrappedDestType;
658 auto WorstKind = CastAwayConstnessKind::CACK_Similar;
659 bool AllConstSoFar = true;
660 while (auto Kind = unwrapCastAwayConstnessLevel(
661 Self.Context, UnwrappedSrcType, UnwrappedDestType)) {
662 // Track the worst kind of unwrap we needed to do before we found a
663 // problem.
664 if (Kind > WorstKind)
665 WorstKind = Kind;
666
667 // Determine the relevant qualifiers at this level.
668 Qualifiers SrcQuals, DestQuals;
669 Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals);
670 Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals);
671
672 // We do not meaningfully track object const-ness of Objective-C object
673 // types. Remove const from the source type if either the source or
674 // the destination is an Objective-C object type.
675 if (UnwrappedSrcType->isObjCObjectType() ||
676 UnwrappedDestType->isObjCObjectType())
677 SrcQuals.removeConst();
678
679 if (CheckCVR) {
680 Qualifiers SrcCvrQuals =
681 Qualifiers::fromCVRMask(SrcQuals.getCVRQualifiers());
682 Qualifiers DestCvrQuals =
683 Qualifiers::fromCVRMask(DestQuals.getCVRQualifiers());
684
685 if (SrcCvrQuals != DestCvrQuals) {
686 if (CastAwayQualifiers)
687 *CastAwayQualifiers = SrcCvrQuals - DestCvrQuals;
688
689 // If we removed a cvr-qualifier, this is casting away 'constness'.
690 if (!DestCvrQuals.compatiblyIncludes(SrcCvrQuals)) {
691 if (TheOffendingSrcType)
692 *TheOffendingSrcType = PrevUnwrappedSrcType;
693 if (TheOffendingDestType)
694 *TheOffendingDestType = PrevUnwrappedDestType;
695 return WorstKind;
696 }
697
698 // If any prior level was not 'const', this is also casting away
699 // 'constness'. We noted the outermost type missing a 'const' already.
700 if (!AllConstSoFar)
701 return WorstKind;
702 }
703 }
704
705 if (CheckObjCLifetime &&
706 !DestQuals.compatiblyIncludesObjCLifetime(SrcQuals))
707 return WorstKind;
708
709 // If we found our first non-const-qualified type, this may be the place
710 // where things start to go wrong.
711 if (AllConstSoFar && !DestQuals.hasConst()) {
712 AllConstSoFar = false;
713 if (TheOffendingSrcType)
714 *TheOffendingSrcType = PrevUnwrappedSrcType;
715 if (TheOffendingDestType)
716 *TheOffendingDestType = PrevUnwrappedDestType;
717 }
718
719 PrevUnwrappedSrcType = UnwrappedSrcType;
720 PrevUnwrappedDestType = UnwrappedDestType;
721 }
722
723 return CastAwayConstnessKind::CACK_None;
724 }
725
getCastAwayConstnessCastKind(CastAwayConstnessKind CACK,unsigned & DiagID)726 static TryCastResult getCastAwayConstnessCastKind(CastAwayConstnessKind CACK,
727 unsigned &DiagID) {
728 switch (CACK) {
729 case CastAwayConstnessKind::CACK_None:
730 llvm_unreachable("did not cast away constness");
731
732 case CastAwayConstnessKind::CACK_Similar:
733 // FIXME: Accept these as an extension too?
734 case CastAwayConstnessKind::CACK_SimilarKind:
735 DiagID = diag::err_bad_cxx_cast_qualifiers_away;
736 return TC_Failed;
737
738 case CastAwayConstnessKind::CACK_Incoherent:
739 DiagID = diag::ext_bad_cxx_cast_qualifiers_away_incoherent;
740 return TC_Extension;
741 }
742
743 llvm_unreachable("unexpected cast away constness kind");
744 }
745
746 /// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid.
747 /// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime-
748 /// checked downcasts in class hierarchies.
CheckDynamicCast()749 void CastOperation::CheckDynamicCast() {
750 CheckNoDerefRAII NoderefCheck(*this);
751
752 if (ValueKind == VK_RValue)
753 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
754 else if (isPlaceholder())
755 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
756 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
757 return;
758
759 QualType OrigSrcType = SrcExpr.get()->getType();
760 QualType DestType = Self.Context.getCanonicalType(this->DestType);
761
762 // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type,
763 // or "pointer to cv void".
764
765 QualType DestPointee;
766 const PointerType *DestPointer = DestType->getAs<PointerType>();
767 const ReferenceType *DestReference = nullptr;
768 if (DestPointer) {
769 DestPointee = DestPointer->getPointeeType();
770 } else if ((DestReference = DestType->getAs<ReferenceType>())) {
771 DestPointee = DestReference->getPointeeType();
772 } else {
773 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr)
774 << this->DestType << DestRange;
775 SrcExpr = ExprError();
776 return;
777 }
778
779 const RecordType *DestRecord = DestPointee->getAs<RecordType>();
780 if (DestPointee->isVoidType()) {
781 assert(DestPointer && "Reference to void is not possible");
782 } else if (DestRecord) {
783 if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee,
784 diag::err_bad_cast_incomplete,
785 DestRange)) {
786 SrcExpr = ExprError();
787 return;
788 }
789 } else {
790 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
791 << DestPointee.getUnqualifiedType() << DestRange;
792 SrcExpr = ExprError();
793 return;
794 }
795
796 // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to
797 // complete class type, [...]. If T is an lvalue reference type, v shall be
798 // an lvalue of a complete class type, [...]. If T is an rvalue reference
799 // type, v shall be an expression having a complete class type, [...]
800 QualType SrcType = Self.Context.getCanonicalType(OrigSrcType);
801 QualType SrcPointee;
802 if (DestPointer) {
803 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
804 SrcPointee = SrcPointer->getPointeeType();
805 } else {
806 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr)
807 << OrigSrcType << this->DestType << SrcExpr.get()->getSourceRange();
808 SrcExpr = ExprError();
809 return;
810 }
811 } else if (DestReference->isLValueReferenceType()) {
812 if (!SrcExpr.get()->isLValue()) {
813 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue)
814 << CT_Dynamic << OrigSrcType << this->DestType << OpRange;
815 }
816 SrcPointee = SrcType;
817 } else {
818 // If we're dynamic_casting from a prvalue to an rvalue reference, we need
819 // to materialize the prvalue before we bind the reference to it.
820 if (SrcExpr.get()->isRValue())
821 SrcExpr = Self.CreateMaterializeTemporaryExpr(
822 SrcType, SrcExpr.get(), /*IsLValueReference*/ false);
823 SrcPointee = SrcType;
824 }
825
826 const RecordType *SrcRecord = SrcPointee->getAs<RecordType>();
827 if (SrcRecord) {
828 if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee,
829 diag::err_bad_cast_incomplete,
830 SrcExpr.get())) {
831 SrcExpr = ExprError();
832 return;
833 }
834 } else {
835 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
836 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
837 SrcExpr = ExprError();
838 return;
839 }
840
841 assert((DestPointer || DestReference) &&
842 "Bad destination non-ptr/ref slipped through.");
843 assert((DestRecord || DestPointee->isVoidType()) &&
844 "Bad destination pointee slipped through.");
845 assert(SrcRecord && "Bad source pointee slipped through.");
846
847 // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness.
848 if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) {
849 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away)
850 << CT_Dynamic << OrigSrcType << this->DestType << OpRange;
851 SrcExpr = ExprError();
852 return;
853 }
854
855 // C++ 5.2.7p3: If the type of v is the same as the required result type,
856 // [except for cv].
857 if (DestRecord == SrcRecord) {
858 Kind = CK_NoOp;
859 return;
860 }
861
862 // C++ 5.2.7p5
863 // Upcasts are resolved statically.
864 if (DestRecord &&
865 Self.IsDerivedFrom(OpRange.getBegin(), SrcPointee, DestPointee)) {
866 if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee,
867 OpRange.getBegin(), OpRange,
868 &BasePath)) {
869 SrcExpr = ExprError();
870 return;
871 }
872
873 Kind = CK_DerivedToBase;
874 return;
875 }
876
877 // C++ 5.2.7p6: Otherwise, v shall be [polymorphic].
878 const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition();
879 assert(SrcDecl && "Definition missing");
880 if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) {
881 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic)
882 << SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
883 SrcExpr = ExprError();
884 }
885
886 // dynamic_cast is not available with -fno-rtti.
887 // As an exception, dynamic_cast to void* is available because it doesn't
888 // use RTTI.
889 if (!Self.getLangOpts().RTTI && !DestPointee->isVoidType()) {
890 Self.Diag(OpRange.getBegin(), diag::err_no_dynamic_cast_with_fno_rtti);
891 SrcExpr = ExprError();
892 return;
893 }
894
895 // Done. Everything else is run-time checks.
896 Kind = CK_Dynamic;
897 }
898
899 /// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid.
900 /// Refer to C++ 5.2.11 for details. const_cast is typically used in code
901 /// like this:
902 /// const char *str = "literal";
903 /// legacy_function(const_cast\<char*\>(str));
CheckConstCast()904 void CastOperation::CheckConstCast() {
905 CheckNoDerefRAII NoderefCheck(*this);
906
907 if (ValueKind == VK_RValue)
908 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
909 else if (isPlaceholder())
910 SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
911 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
912 return;
913
914 unsigned msg = diag::err_bad_cxx_cast_generic;
915 auto TCR = TryConstCast(Self, SrcExpr, DestType, /*CStyle*/ false, msg);
916 if (TCR != TC_Success && msg != 0) {
917 Self.Diag(OpRange.getBegin(), msg) << CT_Const
918 << SrcExpr.get()->getType() << DestType << OpRange;
919 }
920 if (!isValidCast(TCR))
921 SrcExpr = ExprError();
922 }
923
CheckAddrspaceCast()924 void CastOperation::CheckAddrspaceCast() {
925 unsigned msg = diag::err_bad_cxx_cast_generic;
926 auto TCR =
927 TryAddressSpaceCast(Self, SrcExpr, DestType, /*CStyle*/ false, msg, Kind);
928 if (TCR != TC_Success && msg != 0) {
929 Self.Diag(OpRange.getBegin(), msg)
930 << CT_Addrspace << SrcExpr.get()->getType() << DestType << OpRange;
931 }
932 if (!isValidCast(TCR))
933 SrcExpr = ExprError();
934 }
935
936 /// Check that a reinterpret_cast\<DestType\>(SrcExpr) is not used as upcast
937 /// or downcast between respective pointers or references.
DiagnoseReinterpretUpDownCast(Sema & Self,const Expr * SrcExpr,QualType DestType,SourceRange OpRange)938 static void DiagnoseReinterpretUpDownCast(Sema &Self, const Expr *SrcExpr,
939 QualType DestType,
940 SourceRange OpRange) {
941 QualType SrcType = SrcExpr->getType();
942 // When casting from pointer or reference, get pointee type; use original
943 // type otherwise.
944 const CXXRecordDecl *SrcPointeeRD = SrcType->getPointeeCXXRecordDecl();
945 const CXXRecordDecl *SrcRD =
946 SrcPointeeRD ? SrcPointeeRD : SrcType->getAsCXXRecordDecl();
947
948 // Examining subobjects for records is only possible if the complete and
949 // valid definition is available. Also, template instantiation is not
950 // allowed here.
951 if (!SrcRD || !SrcRD->isCompleteDefinition() || SrcRD->isInvalidDecl())
952 return;
953
954 const CXXRecordDecl *DestRD = DestType->getPointeeCXXRecordDecl();
955
956 if (!DestRD || !DestRD->isCompleteDefinition() || DestRD->isInvalidDecl())
957 return;
958
959 enum {
960 ReinterpretUpcast,
961 ReinterpretDowncast
962 } ReinterpretKind;
963
964 CXXBasePaths BasePaths;
965
966 if (SrcRD->isDerivedFrom(DestRD, BasePaths))
967 ReinterpretKind = ReinterpretUpcast;
968 else if (DestRD->isDerivedFrom(SrcRD, BasePaths))
969 ReinterpretKind = ReinterpretDowncast;
970 else
971 return;
972
973 bool VirtualBase = true;
974 bool NonZeroOffset = false;
975 for (CXXBasePaths::const_paths_iterator I = BasePaths.begin(),
976 E = BasePaths.end();
977 I != E; ++I) {
978 const CXXBasePath &Path = *I;
979 CharUnits Offset = CharUnits::Zero();
980 bool IsVirtual = false;
981 for (CXXBasePath::const_iterator IElem = Path.begin(), EElem = Path.end();
982 IElem != EElem; ++IElem) {
983 IsVirtual = IElem->Base->isVirtual();
984 if (IsVirtual)
985 break;
986 const CXXRecordDecl *BaseRD = IElem->Base->getType()->getAsCXXRecordDecl();
987 assert(BaseRD && "Base type should be a valid unqualified class type");
988 // Don't check if any base has invalid declaration or has no definition
989 // since it has no layout info.
990 const CXXRecordDecl *Class = IElem->Class,
991 *ClassDefinition = Class->getDefinition();
992 if (Class->isInvalidDecl() || !ClassDefinition ||
993 !ClassDefinition->isCompleteDefinition())
994 return;
995
996 const ASTRecordLayout &DerivedLayout =
997 Self.Context.getASTRecordLayout(Class);
998 Offset += DerivedLayout.getBaseClassOffset(BaseRD);
999 }
1000 if (!IsVirtual) {
1001 // Don't warn if any path is a non-virtually derived base at offset zero.
1002 if (Offset.isZero())
1003 return;
1004 // Offset makes sense only for non-virtual bases.
1005 else
1006 NonZeroOffset = true;
1007 }
1008 VirtualBase = VirtualBase && IsVirtual;
1009 }
1010
1011 (void) NonZeroOffset; // Silence set but not used warning.
1012 assert((VirtualBase || NonZeroOffset) &&
1013 "Should have returned if has non-virtual base with zero offset");
1014
1015 QualType BaseType =
1016 ReinterpretKind == ReinterpretUpcast? DestType : SrcType;
1017 QualType DerivedType =
1018 ReinterpretKind == ReinterpretUpcast? SrcType : DestType;
1019
1020 SourceLocation BeginLoc = OpRange.getBegin();
1021 Self.Diag(BeginLoc, diag::warn_reinterpret_different_from_static)
1022 << DerivedType << BaseType << !VirtualBase << int(ReinterpretKind)
1023 << OpRange;
1024 Self.Diag(BeginLoc, diag::note_reinterpret_updowncast_use_static)
1025 << int(ReinterpretKind)
1026 << FixItHint::CreateReplacement(BeginLoc, "static_cast");
1027 }
1028
1029 /// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is
1030 /// valid.
1031 /// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code
1032 /// like this:
1033 /// char *bytes = reinterpret_cast\<char*\>(int_ptr);
CheckReinterpretCast()1034 void CastOperation::CheckReinterpretCast() {
1035 if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload))
1036 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
1037 else
1038 checkNonOverloadPlaceholders();
1039 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
1040 return;
1041
1042 unsigned msg = diag::err_bad_cxx_cast_generic;
1043 TryCastResult tcr =
1044 TryReinterpretCast(Self, SrcExpr, DestType,
1045 /*CStyle*/false, OpRange, msg, Kind);
1046 if (tcr != TC_Success && msg != 0) {
1047 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
1048 return;
1049 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
1050 //FIXME: &f<int>; is overloaded and resolvable
1051 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload)
1052 << OverloadExpr::find(SrcExpr.get()).Expression->getName()
1053 << DestType << OpRange;
1054 Self.NoteAllOverloadCandidates(SrcExpr.get());
1055
1056 } else {
1057 diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(),
1058 DestType, /*listInitialization=*/false);
1059 }
1060 }
1061
1062 if (isValidCast(tcr)) {
1063 if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers())
1064 checkObjCConversion(Sema::CCK_OtherCast);
1065 DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange);
1066 } else {
1067 SrcExpr = ExprError();
1068 }
1069 }
1070
1071
1072 /// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid.
1073 /// Refer to C++ 5.2.9 for details. Static casts are mostly used for making
1074 /// implicit conversions explicit and getting rid of data loss warnings.
CheckStaticCast()1075 void CastOperation::CheckStaticCast() {
1076 CheckNoDerefRAII NoderefCheck(*this);
1077
1078 if (isPlaceholder()) {
1079 checkNonOverloadPlaceholders();
1080 if (SrcExpr.isInvalid())
1081 return;
1082 }
1083
1084 // This test is outside everything else because it's the only case where
1085 // a non-lvalue-reference target type does not lead to decay.
1086 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
1087 if (DestType->isVoidType()) {
1088 Kind = CK_ToVoid;
1089
1090 if (claimPlaceholder(BuiltinType::Overload)) {
1091 Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr,
1092 false, // Decay Function to ptr
1093 true, // Complain
1094 OpRange, DestType, diag::err_bad_static_cast_overload);
1095 if (SrcExpr.isInvalid())
1096 return;
1097 }
1098
1099 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
1100 return;
1101 }
1102
1103 if (ValueKind == VK_RValue && !DestType->isRecordType() &&
1104 !isPlaceholder(BuiltinType::Overload)) {
1105 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
1106 if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
1107 return;
1108 }
1109
1110 unsigned msg = diag::err_bad_cxx_cast_generic;
1111 TryCastResult tcr
1112 = TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_OtherCast, OpRange, msg,
1113 Kind, BasePath, /*ListInitialization=*/false);
1114 if (tcr != TC_Success && msg != 0) {
1115 if (SrcExpr.isInvalid())
1116 return;
1117 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
1118 OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression;
1119 Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload)
1120 << oe->getName() << DestType << OpRange
1121 << oe->getQualifierLoc().getSourceRange();
1122 Self.NoteAllOverloadCandidates(SrcExpr.get());
1123 } else {
1124 diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType,
1125 /*listInitialization=*/false);
1126 }
1127 }
1128
1129 if (isValidCast(tcr)) {
1130 if (Kind == CK_BitCast)
1131 checkCastAlign();
1132 if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers())
1133 checkObjCConversion(Sema::CCK_OtherCast);
1134 } else {
1135 SrcExpr = ExprError();
1136 }
1137 }
1138
IsAddressSpaceConversion(QualType SrcType,QualType DestType)1139 static bool IsAddressSpaceConversion(QualType SrcType, QualType DestType) {
1140 auto *SrcPtrType = SrcType->getAs<PointerType>();
1141 if (!SrcPtrType)
1142 return false;
1143 auto *DestPtrType = DestType->getAs<PointerType>();
1144 if (!DestPtrType)
1145 return false;
1146 return SrcPtrType->getPointeeType().getAddressSpace() !=
1147 DestPtrType->getPointeeType().getAddressSpace();
1148 }
1149
1150 /// TryStaticCast - Check if a static cast can be performed, and do so if
1151 /// possible. If @p CStyle, ignore access restrictions on hierarchy casting
1152 /// and casting away constness.
TryStaticCast(Sema & Self,ExprResult & SrcExpr,QualType DestType,Sema::CheckedConversionKind CCK,SourceRange OpRange,unsigned & msg,CastKind & Kind,CXXCastPath & BasePath,bool ListInitialization)1153 static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
1154 QualType DestType,
1155 Sema::CheckedConversionKind CCK,
1156 SourceRange OpRange, unsigned &msg,
1157 CastKind &Kind, CXXCastPath &BasePath,
1158 bool ListInitialization) {
1159 // Determine whether we have the semantics of a C-style cast.
1160 bool CStyle
1161 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast);
1162
1163 // The order the tests is not entirely arbitrary. There is one conversion
1164 // that can be handled in two different ways. Given:
1165 // struct A {};
1166 // struct B : public A {
1167 // B(); B(const A&);
1168 // };
1169 // const A &a = B();
1170 // the cast static_cast<const B&>(a) could be seen as either a static
1171 // reference downcast, or an explicit invocation of the user-defined
1172 // conversion using B's conversion constructor.
1173 // DR 427 specifies that the downcast is to be applied here.
1174
1175 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
1176 // Done outside this function.
1177
1178 TryCastResult tcr;
1179
1180 // C++ 5.2.9p5, reference downcast.
1181 // See the function for details.
1182 // DR 427 specifies that this is to be applied before paragraph 2.
1183 tcr = TryStaticReferenceDowncast(Self, SrcExpr.get(), DestType, CStyle,
1184 OpRange, msg, Kind, BasePath);
1185 if (tcr != TC_NotApplicable)
1186 return tcr;
1187
1188 // C++11 [expr.static.cast]p3:
1189 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to cv2
1190 // T2" if "cv2 T2" is reference-compatible with "cv1 T1".
1191 tcr = TryLValueToRValueCast(Self, SrcExpr.get(), DestType, CStyle, Kind,
1192 BasePath, msg);
1193 if (tcr != TC_NotApplicable)
1194 return tcr;
1195
1196 // C++ 5.2.9p2: An expression e can be explicitly converted to a type T
1197 // [...] if the declaration "T t(e);" is well-formed, [...].
1198 tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CCK, OpRange, msg,
1199 Kind, ListInitialization);
1200 if (SrcExpr.isInvalid())
1201 return TC_Failed;
1202 if (tcr != TC_NotApplicable)
1203 return tcr;
1204
1205 // C++ 5.2.9p6: May apply the reverse of any standard conversion, except
1206 // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean
1207 // conversions, subject to further restrictions.
1208 // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal
1209 // of qualification conversions impossible.
1210 // In the CStyle case, the earlier attempt to const_cast should have taken
1211 // care of reverse qualification conversions.
1212
1213 QualType SrcType = Self.Context.getCanonicalType(SrcExpr.get()->getType());
1214
1215 // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly
1216 // converted to an integral type. [...] A value of a scoped enumeration type
1217 // can also be explicitly converted to a floating-point type [...].
1218 if (const EnumType *Enum = SrcType->getAs<EnumType>()) {
1219 if (Enum->getDecl()->isScoped()) {
1220 if (DestType->isBooleanType()) {
1221 Kind = CK_IntegralToBoolean;
1222 return TC_Success;
1223 } else if (DestType->isIntegralType(Self.Context)) {
1224 Kind = CK_IntegralCast;
1225 return TC_Success;
1226 } else if (DestType->isRealFloatingType()) {
1227 Kind = CK_IntegralToFloating;
1228 return TC_Success;
1229 }
1230 }
1231 }
1232
1233 // Reverse integral promotion/conversion. All such conversions are themselves
1234 // again integral promotions or conversions and are thus already handled by
1235 // p2 (TryDirectInitialization above).
1236 // (Note: any data loss warnings should be suppressed.)
1237 // The exception is the reverse of enum->integer, i.e. integer->enum (and
1238 // enum->enum). See also C++ 5.2.9p7.
1239 // The same goes for reverse floating point promotion/conversion and
1240 // floating-integral conversions. Again, only floating->enum is relevant.
1241 if (DestType->isEnumeralType()) {
1242 if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
1243 diag::err_bad_cast_incomplete)) {
1244 SrcExpr = ExprError();
1245 return TC_Failed;
1246 }
1247 if (SrcType->isIntegralOrEnumerationType()) {
1248 Kind = CK_IntegralCast;
1249 return TC_Success;
1250 } else if (SrcType->isRealFloatingType()) {
1251 Kind = CK_FloatingToIntegral;
1252 return TC_Success;
1253 }
1254 }
1255
1256 // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast.
1257 // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance.
1258 tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg,
1259 Kind, BasePath);
1260 if (tcr != TC_NotApplicable)
1261 return tcr;
1262
1263 // Reverse member pointer conversion. C++ 4.11 specifies member pointer
1264 // conversion. C++ 5.2.9p9 has additional information.
1265 // DR54's access restrictions apply here also.
1266 tcr = TryStaticMemberPointerUpcast(Self, SrcExpr, SrcType, DestType, CStyle,
1267 OpRange, msg, Kind, BasePath);
1268 if (tcr != TC_NotApplicable)
1269 return tcr;
1270
1271 // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to
1272 // void*. C++ 5.2.9p10 specifies additional restrictions, which really is
1273 // just the usual constness stuff.
1274 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
1275 QualType SrcPointee = SrcPointer->getPointeeType();
1276 if (SrcPointee->isVoidType()) {
1277 if (const PointerType *DestPointer = DestType->getAs<PointerType>()) {
1278 QualType DestPointee = DestPointer->getPointeeType();
1279 if (DestPointee->isIncompleteOrObjectType()) {
1280 // This is definitely the intended conversion, but it might fail due
1281 // to a qualifier violation. Note that we permit Objective-C lifetime
1282 // and GC qualifier mismatches here.
1283 if (!CStyle) {
1284 Qualifiers DestPointeeQuals = DestPointee.getQualifiers();
1285 Qualifiers SrcPointeeQuals = SrcPointee.getQualifiers();
1286 DestPointeeQuals.removeObjCGCAttr();
1287 DestPointeeQuals.removeObjCLifetime();
1288 SrcPointeeQuals.removeObjCGCAttr();
1289 SrcPointeeQuals.removeObjCLifetime();
1290 if (DestPointeeQuals != SrcPointeeQuals &&
1291 !DestPointeeQuals.compatiblyIncludes(SrcPointeeQuals)) {
1292 msg = diag::err_bad_cxx_cast_qualifiers_away;
1293 return TC_Failed;
1294 }
1295 }
1296 Kind = IsAddressSpaceConversion(SrcType, DestType)
1297 ? CK_AddressSpaceConversion
1298 : CK_BitCast;
1299 return TC_Success;
1300 }
1301
1302 // Microsoft permits static_cast from 'pointer-to-void' to
1303 // 'pointer-to-function'.
1304 if (!CStyle && Self.getLangOpts().MSVCCompat &&
1305 DestPointee->isFunctionType()) {
1306 Self.Diag(OpRange.getBegin(), diag::ext_ms_cast_fn_obj) << OpRange;
1307 Kind = CK_BitCast;
1308 return TC_Success;
1309 }
1310 }
1311 else if (DestType->isObjCObjectPointerType()) {
1312 // allow both c-style cast and static_cast of objective-c pointers as
1313 // they are pervasive.
1314 Kind = CK_CPointerToObjCPointerCast;
1315 return TC_Success;
1316 }
1317 else if (CStyle && DestType->isBlockPointerType()) {
1318 // allow c-style cast of void * to block pointers.
1319 Kind = CK_AnyPointerToBlockPointerCast;
1320 return TC_Success;
1321 }
1322 }
1323 }
1324 // Allow arbitrary objective-c pointer conversion with static casts.
1325 if (SrcType->isObjCObjectPointerType() &&
1326 DestType->isObjCObjectPointerType()) {
1327 Kind = CK_BitCast;
1328 return TC_Success;
1329 }
1330 // Allow ns-pointer to cf-pointer conversion in either direction
1331 // with static casts.
1332 if (!CStyle &&
1333 Self.CheckTollFreeBridgeStaticCast(DestType, SrcExpr.get(), Kind))
1334 return TC_Success;
1335
1336 // See if it looks like the user is trying to convert between
1337 // related record types, and select a better diagnostic if so.
1338 if (auto SrcPointer = SrcType->getAs<PointerType>())
1339 if (auto DestPointer = DestType->getAs<PointerType>())
1340 if (SrcPointer->getPointeeType()->getAs<RecordType>() &&
1341 DestPointer->getPointeeType()->getAs<RecordType>())
1342 msg = diag::err_bad_cxx_cast_unrelated_class;
1343
1344 // We tried everything. Everything! Nothing works! :-(
1345 return TC_NotApplicable;
1346 }
1347
1348 /// Tests whether a conversion according to N2844 is valid.
TryLValueToRValueCast(Sema & Self,Expr * SrcExpr,QualType DestType,bool CStyle,CastKind & Kind,CXXCastPath & BasePath,unsigned & msg)1349 TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr,
1350 QualType DestType, bool CStyle,
1351 CastKind &Kind, CXXCastPath &BasePath,
1352 unsigned &msg) {
1353 // C++11 [expr.static.cast]p3:
1354 // A glvalue of type "cv1 T1" can be cast to type "rvalue reference to
1355 // cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1".
1356 const RValueReferenceType *R = DestType->getAs<RValueReferenceType>();
1357 if (!R)
1358 return TC_NotApplicable;
1359
1360 if (!SrcExpr->isGLValue())
1361 return TC_NotApplicable;
1362
1363 // Because we try the reference downcast before this function, from now on
1364 // this is the only cast possibility, so we issue an error if we fail now.
1365 // FIXME: Should allow casting away constness if CStyle.
1366 QualType FromType = SrcExpr->getType();
1367 QualType ToType = R->getPointeeType();
1368 if (CStyle) {
1369 FromType = FromType.getUnqualifiedType();
1370 ToType = ToType.getUnqualifiedType();
1371 }
1372
1373 Sema::ReferenceConversions RefConv;
1374 Sema::ReferenceCompareResult RefResult = Self.CompareReferenceRelationship(
1375 SrcExpr->getBeginLoc(), ToType, FromType, &RefConv);
1376 if (RefResult != Sema::Ref_Compatible) {
1377 if (CStyle || RefResult == Sema::Ref_Incompatible)
1378 return TC_NotApplicable;
1379 // Diagnose types which are reference-related but not compatible here since
1380 // we can provide better diagnostics. In these cases forwarding to
1381 // [expr.static.cast]p4 should never result in a well-formed cast.
1382 msg = SrcExpr->isLValue() ? diag::err_bad_lvalue_to_rvalue_cast
1383 : diag::err_bad_rvalue_to_rvalue_cast;
1384 return TC_Failed;
1385 }
1386
1387 if (RefConv & Sema::ReferenceConversions::DerivedToBase) {
1388 Kind = CK_DerivedToBase;
1389 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1390 /*DetectVirtual=*/true);
1391 if (!Self.IsDerivedFrom(SrcExpr->getBeginLoc(), SrcExpr->getType(),
1392 R->getPointeeType(), Paths))
1393 return TC_NotApplicable;
1394
1395 Self.BuildBasePathArray(Paths, BasePath);
1396 } else
1397 Kind = CK_NoOp;
1398
1399 return TC_Success;
1400 }
1401
1402 /// Tests whether a conversion according to C++ 5.2.9p5 is valid.
1403 TryCastResult
TryStaticReferenceDowncast(Sema & Self,Expr * SrcExpr,QualType DestType,bool CStyle,SourceRange OpRange,unsigned & msg,CastKind & Kind,CXXCastPath & BasePath)1404 TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType,
1405 bool CStyle, SourceRange OpRange,
1406 unsigned &msg, CastKind &Kind,
1407 CXXCastPath &BasePath) {
1408 // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be
1409 // cast to type "reference to cv2 D", where D is a class derived from B,
1410 // if a valid standard conversion from "pointer to D" to "pointer to B"
1411 // exists, cv2 >= cv1, and B is not a virtual base class of D.
1412 // In addition, DR54 clarifies that the base must be accessible in the
1413 // current context. Although the wording of DR54 only applies to the pointer
1414 // variant of this rule, the intent is clearly for it to apply to the this
1415 // conversion as well.
1416
1417 const ReferenceType *DestReference = DestType->getAs<ReferenceType>();
1418 if (!DestReference) {
1419 return TC_NotApplicable;
1420 }
1421 bool RValueRef = DestReference->isRValueReferenceType();
1422 if (!RValueRef && !SrcExpr->isLValue()) {
1423 // We know the left side is an lvalue reference, so we can suggest a reason.
1424 msg = diag::err_bad_cxx_cast_rvalue;
1425 return TC_NotApplicable;
1426 }
1427
1428 QualType DestPointee = DestReference->getPointeeType();
1429
1430 // FIXME: If the source is a prvalue, we should issue a warning (because the
1431 // cast always has undefined behavior), and for AST consistency, we should
1432 // materialize a temporary.
1433 return TryStaticDowncast(Self,
1434 Self.Context.getCanonicalType(SrcExpr->getType()),
1435 Self.Context.getCanonicalType(DestPointee), CStyle,
1436 OpRange, SrcExpr->getType(), DestType, msg, Kind,
1437 BasePath);
1438 }
1439
1440 /// Tests whether a conversion according to C++ 5.2.9p8 is valid.
1441 TryCastResult
TryStaticPointerDowncast(Sema & Self,QualType SrcType,QualType DestType,bool CStyle,SourceRange OpRange,unsigned & msg,CastKind & Kind,CXXCastPath & BasePath)1442 TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType,
1443 bool CStyle, SourceRange OpRange,
1444 unsigned &msg, CastKind &Kind,
1445 CXXCastPath &BasePath) {
1446 // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class
1447 // type, can be converted to an rvalue of type "pointer to cv2 D", where D
1448 // is a class derived from B, if a valid standard conversion from "pointer
1449 // to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base
1450 // class of D.
1451 // In addition, DR54 clarifies that the base must be accessible in the
1452 // current context.
1453
1454 const PointerType *DestPointer = DestType->getAs<PointerType>();
1455 if (!DestPointer) {
1456 return TC_NotApplicable;
1457 }
1458
1459 const PointerType *SrcPointer = SrcType->getAs<PointerType>();
1460 if (!SrcPointer) {
1461 msg = diag::err_bad_static_cast_pointer_nonpointer;
1462 return TC_NotApplicable;
1463 }
1464
1465 return TryStaticDowncast(Self,
1466 Self.Context.getCanonicalType(SrcPointer->getPointeeType()),
1467 Self.Context.getCanonicalType(DestPointer->getPointeeType()),
1468 CStyle, OpRange, SrcType, DestType, msg, Kind,
1469 BasePath);
1470 }
1471
1472 /// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and
1473 /// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to
1474 /// DestType is possible and allowed.
1475 TryCastResult
TryStaticDowncast(Sema & Self,CanQualType SrcType,CanQualType DestType,bool CStyle,SourceRange OpRange,QualType OrigSrcType,QualType OrigDestType,unsigned & msg,CastKind & Kind,CXXCastPath & BasePath)1476 TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType,
1477 bool CStyle, SourceRange OpRange, QualType OrigSrcType,
1478 QualType OrigDestType, unsigned &msg,
1479 CastKind &Kind, CXXCastPath &BasePath) {
1480 // We can only work with complete types. But don't complain if it doesn't work
1481 if (!Self.isCompleteType(OpRange.getBegin(), SrcType) ||
1482 !Self.isCompleteType(OpRange.getBegin(), DestType))
1483 return TC_NotApplicable;
1484
1485 // Downcast can only happen in class hierarchies, so we need classes.
1486 if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) {
1487 return TC_NotApplicable;
1488 }
1489
1490 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1491 /*DetectVirtual=*/true);
1492 if (!Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths)) {
1493 return TC_NotApplicable;
1494 }
1495
1496 // Target type does derive from source type. Now we're serious. If an error
1497 // appears now, it's not ignored.
1498 // This may not be entirely in line with the standard. Take for example:
1499 // struct A {};
1500 // struct B : virtual A {
1501 // B(A&);
1502 // };
1503 //
1504 // void f()
1505 // {
1506 // (void)static_cast<const B&>(*((A*)0));
1507 // }
1508 // As far as the standard is concerned, p5 does not apply (A is virtual), so
1509 // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid.
1510 // However, both GCC and Comeau reject this example, and accepting it would
1511 // mean more complex code if we're to preserve the nice error message.
1512 // FIXME: Being 100% compliant here would be nice to have.
1513
1514 // Must preserve cv, as always, unless we're in C-style mode.
1515 if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) {
1516 msg = diag::err_bad_cxx_cast_qualifiers_away;
1517 return TC_Failed;
1518 }
1519
1520 if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) {
1521 // This code is analoguous to that in CheckDerivedToBaseConversion, except
1522 // that it builds the paths in reverse order.
1523 // To sum up: record all paths to the base and build a nice string from
1524 // them. Use it to spice up the error message.
1525 if (!Paths.isRecordingPaths()) {
1526 Paths.clear();
1527 Paths.setRecordingPaths(true);
1528 Self.IsDerivedFrom(OpRange.getBegin(), DestType, SrcType, Paths);
1529 }
1530 std::string PathDisplayStr;
1531 std::set<unsigned> DisplayedPaths;
1532 for (clang::CXXBasePath &Path : Paths) {
1533 if (DisplayedPaths.insert(Path.back().SubobjectNumber).second) {
1534 // We haven't displayed a path to this particular base
1535 // class subobject yet.
1536 PathDisplayStr += "\n ";
1537 for (CXXBasePathElement &PE : llvm::reverse(Path))
1538 PathDisplayStr += PE.Base->getType().getAsString() + " -> ";
1539 PathDisplayStr += QualType(DestType).getAsString();
1540 }
1541 }
1542
1543 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast)
1544 << QualType(SrcType).getUnqualifiedType()
1545 << QualType(DestType).getUnqualifiedType()
1546 << PathDisplayStr << OpRange;
1547 msg = 0;
1548 return TC_Failed;
1549 }
1550
1551 if (Paths.getDetectedVirtual() != nullptr) {
1552 QualType VirtualBase(Paths.getDetectedVirtual(), 0);
1553 Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual)
1554 << OrigSrcType << OrigDestType << VirtualBase << OpRange;
1555 msg = 0;
1556 return TC_Failed;
1557 }
1558
1559 if (!CStyle) {
1560 switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
1561 SrcType, DestType,
1562 Paths.front(),
1563 diag::err_downcast_from_inaccessible_base)) {
1564 case Sema::AR_accessible:
1565 case Sema::AR_delayed: // be optimistic
1566 case Sema::AR_dependent: // be optimistic
1567 break;
1568
1569 case Sema::AR_inaccessible:
1570 msg = 0;
1571 return TC_Failed;
1572 }
1573 }
1574
1575 Self.BuildBasePathArray(Paths, BasePath);
1576 Kind = CK_BaseToDerived;
1577 return TC_Success;
1578 }
1579
1580 /// TryStaticMemberPointerUpcast - Tests whether a conversion according to
1581 /// C++ 5.2.9p9 is valid:
1582 ///
1583 /// An rvalue of type "pointer to member of D of type cv1 T" can be
1584 /// converted to an rvalue of type "pointer to member of B of type cv2 T",
1585 /// where B is a base class of D [...].
1586 ///
1587 TryCastResult
TryStaticMemberPointerUpcast(Sema & Self,ExprResult & SrcExpr,QualType SrcType,QualType DestType,bool CStyle,SourceRange OpRange,unsigned & msg,CastKind & Kind,CXXCastPath & BasePath)1588 TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr, QualType SrcType,
1589 QualType DestType, bool CStyle,
1590 SourceRange OpRange,
1591 unsigned &msg, CastKind &Kind,
1592 CXXCastPath &BasePath) {
1593 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>();
1594 if (!DestMemPtr)
1595 return TC_NotApplicable;
1596
1597 bool WasOverloadedFunction = false;
1598 DeclAccessPair FoundOverload;
1599 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
1600 if (FunctionDecl *Fn
1601 = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(), DestType, false,
1602 FoundOverload)) {
1603 CXXMethodDecl *M = cast<CXXMethodDecl>(Fn);
1604 SrcType = Self.Context.getMemberPointerType(Fn->getType(),
1605 Self.Context.getTypeDeclType(M->getParent()).getTypePtr());
1606 WasOverloadedFunction = true;
1607 }
1608 }
1609
1610 const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>();
1611 if (!SrcMemPtr) {
1612 msg = diag::err_bad_static_cast_member_pointer_nonmp;
1613 return TC_NotApplicable;
1614 }
1615
1616 // Lock down the inheritance model right now in MS ABI, whether or not the
1617 // pointee types are the same.
1618 if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
1619 (void)Self.isCompleteType(OpRange.getBegin(), SrcType);
1620 (void)Self.isCompleteType(OpRange.getBegin(), DestType);
1621 }
1622
1623 // T == T, modulo cv
1624 if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(),
1625 DestMemPtr->getPointeeType()))
1626 return TC_NotApplicable;
1627
1628 // B base of D
1629 QualType SrcClass(SrcMemPtr->getClass(), 0);
1630 QualType DestClass(DestMemPtr->getClass(), 0);
1631 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
1632 /*DetectVirtual=*/true);
1633 if (!Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths))
1634 return TC_NotApplicable;
1635
1636 // B is a base of D. But is it an allowed base? If not, it's a hard error.
1637 if (Paths.isAmbiguous(Self.Context.getCanonicalType(DestClass))) {
1638 Paths.clear();
1639 Paths.setRecordingPaths(true);
1640 bool StillOkay =
1641 Self.IsDerivedFrom(OpRange.getBegin(), SrcClass, DestClass, Paths);
1642 assert(StillOkay);
1643 (void)StillOkay;
1644 std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths);
1645 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv)
1646 << 1 << SrcClass << DestClass << PathDisplayStr << OpRange;
1647 msg = 0;
1648 return TC_Failed;
1649 }
1650
1651 if (const RecordType *VBase = Paths.getDetectedVirtual()) {
1652 Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual)
1653 << SrcClass << DestClass << QualType(VBase, 0) << OpRange;
1654 msg = 0;
1655 return TC_Failed;
1656 }
1657
1658 if (!CStyle) {
1659 switch (Self.CheckBaseClassAccess(OpRange.getBegin(),
1660 DestClass, SrcClass,
1661 Paths.front(),
1662 diag::err_upcast_to_inaccessible_base)) {
1663 case Sema::AR_accessible:
1664 case Sema::AR_delayed:
1665 case Sema::AR_dependent:
1666 // Optimistically assume that the delayed and dependent cases
1667 // will work out.
1668 break;
1669
1670 case Sema::AR_inaccessible:
1671 msg = 0;
1672 return TC_Failed;
1673 }
1674 }
1675
1676 if (WasOverloadedFunction) {
1677 // Resolve the address of the overloaded function again, this time
1678 // allowing complaints if something goes wrong.
1679 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(),
1680 DestType,
1681 true,
1682 FoundOverload);
1683 if (!Fn) {
1684 msg = 0;
1685 return TC_Failed;
1686 }
1687
1688 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr, FoundOverload, Fn);
1689 if (!SrcExpr.isUsable()) {
1690 msg = 0;
1691 return TC_Failed;
1692 }
1693 }
1694
1695 Self.BuildBasePathArray(Paths, BasePath);
1696 Kind = CK_DerivedToBaseMemberPointer;
1697 return TC_Success;
1698 }
1699
1700 /// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2
1701 /// is valid:
1702 ///
1703 /// An expression e can be explicitly converted to a type T using a
1704 /// @c static_cast if the declaration "T t(e);" is well-formed [...].
1705 TryCastResult
TryStaticImplicitCast(Sema & Self,ExprResult & SrcExpr,QualType DestType,Sema::CheckedConversionKind CCK,SourceRange OpRange,unsigned & msg,CastKind & Kind,bool ListInitialization)1706 TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr, QualType DestType,
1707 Sema::CheckedConversionKind CCK,
1708 SourceRange OpRange, unsigned &msg,
1709 CastKind &Kind, bool ListInitialization) {
1710 if (DestType->isRecordType()) {
1711 if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
1712 diag::err_bad_cast_incomplete) ||
1713 Self.RequireNonAbstractType(OpRange.getBegin(), DestType,
1714 diag::err_allocation_of_abstract_type)) {
1715 msg = 0;
1716 return TC_Failed;
1717 }
1718 }
1719
1720 InitializedEntity Entity = InitializedEntity::InitializeTemporary(DestType);
1721 InitializationKind InitKind
1722 = (CCK == Sema::CCK_CStyleCast)
1723 ? InitializationKind::CreateCStyleCast(OpRange.getBegin(), OpRange,
1724 ListInitialization)
1725 : (CCK == Sema::CCK_FunctionalCast)
1726 ? InitializationKind::CreateFunctionalCast(OpRange, ListInitialization)
1727 : InitializationKind::CreateCast(OpRange);
1728 Expr *SrcExprRaw = SrcExpr.get();
1729 // FIXME: Per DR242, we should check for an implicit conversion sequence
1730 // or for a constructor that could be invoked by direct-initialization
1731 // here, not for an initialization sequence.
1732 InitializationSequence InitSeq(Self, Entity, InitKind, SrcExprRaw);
1733
1734 // At this point of CheckStaticCast, if the destination is a reference,
1735 // or the expression is an overload expression this has to work.
1736 // There is no other way that works.
1737 // On the other hand, if we're checking a C-style cast, we've still got
1738 // the reinterpret_cast way.
1739 bool CStyle
1740 = (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast);
1741 if (InitSeq.Failed() && (CStyle || !DestType->isReferenceType()))
1742 return TC_NotApplicable;
1743
1744 ExprResult Result = InitSeq.Perform(Self, Entity, InitKind, SrcExprRaw);
1745 if (Result.isInvalid()) {
1746 msg = 0;
1747 return TC_Failed;
1748 }
1749
1750 if (InitSeq.isConstructorInitialization())
1751 Kind = CK_ConstructorConversion;
1752 else
1753 Kind = CK_NoOp;
1754
1755 SrcExpr = Result;
1756 return TC_Success;
1757 }
1758
1759 /// TryConstCast - See if a const_cast from source to destination is allowed,
1760 /// and perform it if it is.
TryConstCast(Sema & Self,ExprResult & SrcExpr,QualType DestType,bool CStyle,unsigned & msg)1761 static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr,
1762 QualType DestType, bool CStyle,
1763 unsigned &msg) {
1764 DestType = Self.Context.getCanonicalType(DestType);
1765 QualType SrcType = SrcExpr.get()->getType();
1766 bool NeedToMaterializeTemporary = false;
1767
1768 if (const ReferenceType *DestTypeTmp =DestType->getAs<ReferenceType>()) {
1769 // C++11 5.2.11p4:
1770 // if a pointer to T1 can be explicitly converted to the type "pointer to
1771 // T2" using a const_cast, then the following conversions can also be
1772 // made:
1773 // -- an lvalue of type T1 can be explicitly converted to an lvalue of
1774 // type T2 using the cast const_cast<T2&>;
1775 // -- a glvalue of type T1 can be explicitly converted to an xvalue of
1776 // type T2 using the cast const_cast<T2&&>; and
1777 // -- if T1 is a class type, a prvalue of type T1 can be explicitly
1778 // converted to an xvalue of type T2 using the cast const_cast<T2&&>.
1779
1780 if (isa<LValueReferenceType>(DestTypeTmp) && !SrcExpr.get()->isLValue()) {
1781 // Cannot const_cast non-lvalue to lvalue reference type. But if this
1782 // is C-style, static_cast might find a way, so we simply suggest a
1783 // message and tell the parent to keep searching.
1784 msg = diag::err_bad_cxx_cast_rvalue;
1785 return TC_NotApplicable;
1786 }
1787
1788 if (isa<RValueReferenceType>(DestTypeTmp) && SrcExpr.get()->isRValue()) {
1789 if (!SrcType->isRecordType()) {
1790 // Cannot const_cast non-class prvalue to rvalue reference type. But if
1791 // this is C-style, static_cast can do this.
1792 msg = diag::err_bad_cxx_cast_rvalue;
1793 return TC_NotApplicable;
1794 }
1795
1796 // Materialize the class prvalue so that the const_cast can bind a
1797 // reference to it.
1798 NeedToMaterializeTemporary = true;
1799 }
1800
1801 // It's not completely clear under the standard whether we can
1802 // const_cast bit-field gl-values. Doing so would not be
1803 // intrinsically complicated, but for now, we say no for
1804 // consistency with other compilers and await the word of the
1805 // committee.
1806 if (SrcExpr.get()->refersToBitField()) {
1807 msg = diag::err_bad_cxx_cast_bitfield;
1808 return TC_NotApplicable;
1809 }
1810
1811 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
1812 SrcType = Self.Context.getPointerType(SrcType);
1813 }
1814
1815 // C++ 5.2.11p5: For a const_cast involving pointers to data members [...]
1816 // the rules for const_cast are the same as those used for pointers.
1817
1818 if (!DestType->isPointerType() &&
1819 !DestType->isMemberPointerType() &&
1820 !DestType->isObjCObjectPointerType()) {
1821 // Cannot cast to non-pointer, non-reference type. Note that, if DestType
1822 // was a reference type, we converted it to a pointer above.
1823 // The status of rvalue references isn't entirely clear, but it looks like
1824 // conversion to them is simply invalid.
1825 // C++ 5.2.11p3: For two pointer types [...]
1826 if (!CStyle)
1827 msg = diag::err_bad_const_cast_dest;
1828 return TC_NotApplicable;
1829 }
1830 if (DestType->isFunctionPointerType() ||
1831 DestType->isMemberFunctionPointerType()) {
1832 // Cannot cast direct function pointers.
1833 // C++ 5.2.11p2: [...] where T is any object type or the void type [...]
1834 // T is the ultimate pointee of source and target type.
1835 if (!CStyle)
1836 msg = diag::err_bad_const_cast_dest;
1837 return TC_NotApplicable;
1838 }
1839
1840 // C++ [expr.const.cast]p3:
1841 // "For two similar types T1 and T2, [...]"
1842 //
1843 // We only allow a const_cast to change cvr-qualifiers, not other kinds of
1844 // type qualifiers. (Likewise, we ignore other changes when determining
1845 // whether a cast casts away constness.)
1846 if (!Self.Context.hasCvrSimilarType(SrcType, DestType))
1847 return TC_NotApplicable;
1848
1849 if (NeedToMaterializeTemporary)
1850 // This is a const_cast from a class prvalue to an rvalue reference type.
1851 // Materialize a temporary to store the result of the conversion.
1852 SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcExpr.get()->getType(),
1853 SrcExpr.get(),
1854 /*IsLValueReference*/ false);
1855
1856 return TC_Success;
1857 }
1858
1859 // Checks for undefined behavior in reinterpret_cast.
1860 // The cases that is checked for is:
1861 // *reinterpret_cast<T*>(&a)
1862 // reinterpret_cast<T&>(a)
1863 // where accessing 'a' as type 'T' will result in undefined behavior.
CheckCompatibleReinterpretCast(QualType SrcType,QualType DestType,bool IsDereference,SourceRange Range)1864 void Sema::CheckCompatibleReinterpretCast(QualType SrcType, QualType DestType,
1865 bool IsDereference,
1866 SourceRange Range) {
1867 unsigned DiagID = IsDereference ?
1868 diag::warn_pointer_indirection_from_incompatible_type :
1869 diag::warn_undefined_reinterpret_cast;
1870
1871 if (Diags.isIgnored(DiagID, Range.getBegin()))
1872 return;
1873
1874 QualType SrcTy, DestTy;
1875 if (IsDereference) {
1876 if (!SrcType->getAs<PointerType>() || !DestType->getAs<PointerType>()) {
1877 return;
1878 }
1879 SrcTy = SrcType->getPointeeType();
1880 DestTy = DestType->getPointeeType();
1881 } else {
1882 if (!DestType->getAs<ReferenceType>()) {
1883 return;
1884 }
1885 SrcTy = SrcType;
1886 DestTy = DestType->getPointeeType();
1887 }
1888
1889 // Cast is compatible if the types are the same.
1890 if (Context.hasSameUnqualifiedType(DestTy, SrcTy)) {
1891 return;
1892 }
1893 // or one of the types is a char or void type
1894 if (DestTy->isAnyCharacterType() || DestTy->isVoidType() ||
1895 SrcTy->isAnyCharacterType() || SrcTy->isVoidType()) {
1896 return;
1897 }
1898 // or one of the types is a tag type.
1899 if (SrcTy->getAs<TagType>() || DestTy->getAs<TagType>()) {
1900 return;
1901 }
1902
1903 // FIXME: Scoped enums?
1904 if ((SrcTy->isUnsignedIntegerType() && DestTy->isSignedIntegerType()) ||
1905 (SrcTy->isSignedIntegerType() && DestTy->isUnsignedIntegerType())) {
1906 if (Context.getTypeSize(DestTy) == Context.getTypeSize(SrcTy)) {
1907 return;
1908 }
1909 }
1910
1911 Diag(Range.getBegin(), DiagID) << SrcType << DestType << Range;
1912 }
1913
DiagnoseCastOfObjCSEL(Sema & Self,const ExprResult & SrcExpr,QualType DestType)1914 static void DiagnoseCastOfObjCSEL(Sema &Self, const ExprResult &SrcExpr,
1915 QualType DestType) {
1916 QualType SrcType = SrcExpr.get()->getType();
1917 if (Self.Context.hasSameType(SrcType, DestType))
1918 return;
1919 if (const PointerType *SrcPtrTy = SrcType->getAs<PointerType>())
1920 if (SrcPtrTy->isObjCSelType()) {
1921 QualType DT = DestType;
1922 if (isa<PointerType>(DestType))
1923 DT = DestType->getPointeeType();
1924 if (!DT.getUnqualifiedType()->isVoidType())
1925 Self.Diag(SrcExpr.get()->getExprLoc(),
1926 diag::warn_cast_pointer_from_sel)
1927 << SrcType << DestType << SrcExpr.get()->getSourceRange();
1928 }
1929 }
1930
1931 /// Diagnose casts that change the calling convention of a pointer to a function
1932 /// defined in the current TU.
DiagnoseCallingConvCast(Sema & Self,const ExprResult & SrcExpr,QualType DstType,SourceRange OpRange)1933 static void DiagnoseCallingConvCast(Sema &Self, const ExprResult &SrcExpr,
1934 QualType DstType, SourceRange OpRange) {
1935 // Check if this cast would change the calling convention of a function
1936 // pointer type.
1937 QualType SrcType = SrcExpr.get()->getType();
1938 if (Self.Context.hasSameType(SrcType, DstType) ||
1939 !SrcType->isFunctionPointerType() || !DstType->isFunctionPointerType())
1940 return;
1941 const auto *SrcFTy =
1942 SrcType->castAs<PointerType>()->getPointeeType()->castAs<FunctionType>();
1943 const auto *DstFTy =
1944 DstType->castAs<PointerType>()->getPointeeType()->castAs<FunctionType>();
1945 CallingConv SrcCC = SrcFTy->getCallConv();
1946 CallingConv DstCC = DstFTy->getCallConv();
1947 if (SrcCC == DstCC)
1948 return;
1949
1950 // We have a calling convention cast. Check if the source is a pointer to a
1951 // known, specific function that has already been defined.
1952 Expr *Src = SrcExpr.get()->IgnoreParenImpCasts();
1953 if (auto *UO = dyn_cast<UnaryOperator>(Src))
1954 if (UO->getOpcode() == UO_AddrOf)
1955 Src = UO->getSubExpr()->IgnoreParenImpCasts();
1956 auto *DRE = dyn_cast<DeclRefExpr>(Src);
1957 if (!DRE)
1958 return;
1959 auto *FD = dyn_cast<FunctionDecl>(DRE->getDecl());
1960 if (!FD)
1961 return;
1962
1963 // Only warn if we are casting from the default convention to a non-default
1964 // convention. This can happen when the programmer forgot to apply the calling
1965 // convention to the function declaration and then inserted this cast to
1966 // satisfy the type system.
1967 CallingConv DefaultCC = Self.getASTContext().getDefaultCallingConvention(
1968 FD->isVariadic(), FD->isCXXInstanceMember());
1969 if (DstCC == DefaultCC || SrcCC != DefaultCC)
1970 return;
1971
1972 // Diagnose this cast, as it is probably bad.
1973 StringRef SrcCCName = FunctionType::getNameForCallConv(SrcCC);
1974 StringRef DstCCName = FunctionType::getNameForCallConv(DstCC);
1975 Self.Diag(OpRange.getBegin(), diag::warn_cast_calling_conv)
1976 << SrcCCName << DstCCName << OpRange;
1977
1978 // The checks above are cheaper than checking if the diagnostic is enabled.
1979 // However, it's worth checking if the warning is enabled before we construct
1980 // a fixit.
1981 if (Self.Diags.isIgnored(diag::warn_cast_calling_conv, OpRange.getBegin()))
1982 return;
1983
1984 // Try to suggest a fixit to change the calling convention of the function
1985 // whose address was taken. Try to use the latest macro for the convention.
1986 // For example, users probably want to write "WINAPI" instead of "__stdcall"
1987 // to match the Windows header declarations.
1988 SourceLocation NameLoc = FD->getFirstDecl()->getNameInfo().getLoc();
1989 Preprocessor &PP = Self.getPreprocessor();
1990 SmallVector<TokenValue, 6> AttrTokens;
1991 SmallString<64> CCAttrText;
1992 llvm::raw_svector_ostream OS(CCAttrText);
1993 if (Self.getLangOpts().MicrosoftExt) {
1994 // __stdcall or __vectorcall
1995 OS << "__" << DstCCName;
1996 IdentifierInfo *II = PP.getIdentifierInfo(OS.str());
1997 AttrTokens.push_back(II->isKeyword(Self.getLangOpts())
1998 ? TokenValue(II->getTokenID())
1999 : TokenValue(II));
2000 } else {
2001 // __attribute__((stdcall)) or __attribute__((vectorcall))
2002 OS << "__attribute__((" << DstCCName << "))";
2003 AttrTokens.push_back(tok::kw___attribute);
2004 AttrTokens.push_back(tok::l_paren);
2005 AttrTokens.push_back(tok::l_paren);
2006 IdentifierInfo *II = PP.getIdentifierInfo(DstCCName);
2007 AttrTokens.push_back(II->isKeyword(Self.getLangOpts())
2008 ? TokenValue(II->getTokenID())
2009 : TokenValue(II));
2010 AttrTokens.push_back(tok::r_paren);
2011 AttrTokens.push_back(tok::r_paren);
2012 }
2013 StringRef AttrSpelling = PP.getLastMacroWithSpelling(NameLoc, AttrTokens);
2014 if (!AttrSpelling.empty())
2015 CCAttrText = AttrSpelling;
2016 OS << ' ';
2017 Self.Diag(NameLoc, diag::note_change_calling_conv_fixit)
2018 << FD << DstCCName << FixItHint::CreateInsertion(NameLoc, CCAttrText);
2019 }
2020
checkIntToPointerCast(bool CStyle,const SourceRange & OpRange,const Expr * SrcExpr,QualType DestType,Sema & Self)2021 static void checkIntToPointerCast(bool CStyle, const SourceRange &OpRange,
2022 const Expr *SrcExpr, QualType DestType,
2023 Sema &Self) {
2024 QualType SrcType = SrcExpr->getType();
2025
2026 // Not warning on reinterpret_cast, boolean, constant expressions, etc
2027 // are not explicit design choices, but consistent with GCC's behavior.
2028 // Feel free to modify them if you've reason/evidence for an alternative.
2029 if (CStyle && SrcType->isIntegralType(Self.Context)
2030 && !SrcType->isBooleanType()
2031 && !SrcType->isEnumeralType()
2032 && !SrcExpr->isIntegerConstantExpr(Self.Context)
2033 && Self.Context.getTypeSize(DestType) >
2034 Self.Context.getTypeSize(SrcType)) {
2035 // Separate between casts to void* and non-void* pointers.
2036 // Some APIs use (abuse) void* for something like a user context,
2037 // and often that value is an integer even if it isn't a pointer itself.
2038 // Having a separate warning flag allows users to control the warning
2039 // for their workflow.
2040 unsigned Diag = DestType->isVoidPointerType() ?
2041 diag::warn_int_to_void_pointer_cast
2042 : diag::warn_int_to_pointer_cast;
2043 Self.Diag(OpRange.getBegin(), Diag) << SrcType << DestType << OpRange;
2044 }
2045 }
2046
fixOverloadedReinterpretCastExpr(Sema & Self,QualType DestType,ExprResult & Result)2047 static bool fixOverloadedReinterpretCastExpr(Sema &Self, QualType DestType,
2048 ExprResult &Result) {
2049 // We can only fix an overloaded reinterpret_cast if
2050 // - it is a template with explicit arguments that resolves to an lvalue
2051 // unambiguously, or
2052 // - it is the only function in an overload set that may have its address
2053 // taken.
2054
2055 Expr *E = Result.get();
2056 // TODO: what if this fails because of DiagnoseUseOfDecl or something
2057 // like it?
2058 if (Self.ResolveAndFixSingleFunctionTemplateSpecialization(
2059 Result,
2060 Expr::getValueKindForType(DestType) == VK_RValue // Convert Fun to Ptr
2061 ) &&
2062 Result.isUsable())
2063 return true;
2064
2065 // No guarantees that ResolveAndFixSingleFunctionTemplateSpecialization
2066 // preserves Result.
2067 Result = E;
2068 if (!Self.resolveAndFixAddressOfSingleOverloadCandidate(
2069 Result, /*DoFunctionPointerConversion=*/true))
2070 return false;
2071 return Result.isUsable();
2072 }
2073
TryReinterpretCast(Sema & Self,ExprResult & SrcExpr,QualType DestType,bool CStyle,SourceRange OpRange,unsigned & msg,CastKind & Kind)2074 static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
2075 QualType DestType, bool CStyle,
2076 SourceRange OpRange,
2077 unsigned &msg,
2078 CastKind &Kind) {
2079 bool IsLValueCast = false;
2080
2081 DestType = Self.Context.getCanonicalType(DestType);
2082 QualType SrcType = SrcExpr.get()->getType();
2083
2084 // Is the source an overloaded name? (i.e. &foo)
2085 // If so, reinterpret_cast generally can not help us here (13.4, p1, bullet 5)
2086 if (SrcType == Self.Context.OverloadTy) {
2087 ExprResult FixedExpr = SrcExpr;
2088 if (!fixOverloadedReinterpretCastExpr(Self, DestType, FixedExpr))
2089 return TC_NotApplicable;
2090
2091 assert(FixedExpr.isUsable() && "Invalid result fixing overloaded expr");
2092 SrcExpr = FixedExpr;
2093 SrcType = SrcExpr.get()->getType();
2094 }
2095
2096 if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) {
2097 if (!SrcExpr.get()->isGLValue()) {
2098 // Cannot cast non-glvalue to (lvalue or rvalue) reference type. See the
2099 // similar comment in const_cast.
2100 msg = diag::err_bad_cxx_cast_rvalue;
2101 return TC_NotApplicable;
2102 }
2103
2104 if (!CStyle) {
2105 Self.CheckCompatibleReinterpretCast(SrcType, DestType,
2106 /*IsDereference=*/false, OpRange);
2107 }
2108
2109 // C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the
2110 // same effect as the conversion *reinterpret_cast<T*>(&x) with the
2111 // built-in & and * operators.
2112
2113 const char *inappropriate = nullptr;
2114 switch (SrcExpr.get()->getObjectKind()) {
2115 case OK_Ordinary:
2116 break;
2117 case OK_BitField:
2118 msg = diag::err_bad_cxx_cast_bitfield;
2119 return TC_NotApplicable;
2120 // FIXME: Use a specific diagnostic for the rest of these cases.
2121 case OK_VectorComponent: inappropriate = "vector element"; break;
2122 case OK_MatrixComponent:
2123 inappropriate = "matrix element";
2124 break;
2125 case OK_ObjCProperty: inappropriate = "property expression"; break;
2126 case OK_ObjCSubscript: inappropriate = "container subscripting expression";
2127 break;
2128 }
2129 if (inappropriate) {
2130 Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_reference)
2131 << inappropriate << DestType
2132 << OpRange << SrcExpr.get()->getSourceRange();
2133 msg = 0; SrcExpr = ExprError();
2134 return TC_NotApplicable;
2135 }
2136
2137 // This code does this transformation for the checked types.
2138 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
2139 SrcType = Self.Context.getPointerType(SrcType);
2140
2141 IsLValueCast = true;
2142 }
2143
2144 // Canonicalize source for comparison.
2145 SrcType = Self.Context.getCanonicalType(SrcType);
2146
2147 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(),
2148 *SrcMemPtr = SrcType->getAs<MemberPointerType>();
2149 if (DestMemPtr && SrcMemPtr) {
2150 // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1"
2151 // can be explicitly converted to an rvalue of type "pointer to member
2152 // of Y of type T2" if T1 and T2 are both function types or both object
2153 // types.
2154 if (DestMemPtr->isMemberFunctionPointer() !=
2155 SrcMemPtr->isMemberFunctionPointer())
2156 return TC_NotApplicable;
2157
2158 if (Self.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
2159 // We need to determine the inheritance model that the class will use if
2160 // haven't yet.
2161 (void)Self.isCompleteType(OpRange.getBegin(), SrcType);
2162 (void)Self.isCompleteType(OpRange.getBegin(), DestType);
2163 }
2164
2165 // Don't allow casting between member pointers of different sizes.
2166 if (Self.Context.getTypeSize(DestMemPtr) !=
2167 Self.Context.getTypeSize(SrcMemPtr)) {
2168 msg = diag::err_bad_cxx_cast_member_pointer_size;
2169 return TC_Failed;
2170 }
2171
2172 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away
2173 // constness.
2174 // A reinterpret_cast followed by a const_cast can, though, so in C-style,
2175 // we accept it.
2176 if (auto CACK =
2177 CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle,
2178 /*CheckObjCLifetime=*/CStyle))
2179 return getCastAwayConstnessCastKind(CACK, msg);
2180
2181 // A valid member pointer cast.
2182 assert(!IsLValueCast);
2183 Kind = CK_ReinterpretMemberPointer;
2184 return TC_Success;
2185 }
2186
2187 // See below for the enumeral issue.
2188 if (SrcType->isNullPtrType() && DestType->isIntegralType(Self.Context)) {
2189 // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral
2190 // type large enough to hold it. A value of std::nullptr_t can be
2191 // converted to an integral type; the conversion has the same meaning
2192 // and validity as a conversion of (void*)0 to the integral type.
2193 if (Self.Context.getTypeSize(SrcType) >
2194 Self.Context.getTypeSize(DestType)) {
2195 msg = diag::err_bad_reinterpret_cast_small_int;
2196 return TC_Failed;
2197 }
2198 Kind = CK_PointerToIntegral;
2199 return TC_Success;
2200 }
2201
2202 // Allow reinterpret_casts between vectors of the same size and
2203 // between vectors and integers of the same size.
2204 bool destIsVector = DestType->isVectorType();
2205 bool srcIsVector = SrcType->isVectorType();
2206 if (srcIsVector || destIsVector) {
2207 // The non-vector type, if any, must have integral type. This is
2208 // the same rule that C vector casts use; note, however, that enum
2209 // types are not integral in C++.
2210 if ((!destIsVector && !DestType->isIntegralType(Self.Context)) ||
2211 (!srcIsVector && !SrcType->isIntegralType(Self.Context)))
2212 return TC_NotApplicable;
2213
2214 // The size we want to consider is eltCount * eltSize.
2215 // That's exactly what the lax-conversion rules will check.
2216 if (Self.areLaxCompatibleVectorTypes(SrcType, DestType)) {
2217 Kind = CK_BitCast;
2218 return TC_Success;
2219 }
2220
2221 // Otherwise, pick a reasonable diagnostic.
2222 if (!destIsVector)
2223 msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size;
2224 else if (!srcIsVector)
2225 msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size;
2226 else
2227 msg = diag::err_bad_cxx_cast_vector_to_vector_different_size;
2228
2229 return TC_Failed;
2230 }
2231
2232 if (SrcType == DestType) {
2233 // C++ 5.2.10p2 has a note that mentions that, subject to all other
2234 // restrictions, a cast to the same type is allowed so long as it does not
2235 // cast away constness. In C++98, the intent was not entirely clear here,
2236 // since all other paragraphs explicitly forbid casts to the same type.
2237 // C++11 clarifies this case with p2.
2238 //
2239 // The only allowed types are: integral, enumeration, pointer, or
2240 // pointer-to-member types. We also won't restrict Obj-C pointers either.
2241 Kind = CK_NoOp;
2242 TryCastResult Result = TC_NotApplicable;
2243 if (SrcType->isIntegralOrEnumerationType() ||
2244 SrcType->isAnyPointerType() ||
2245 SrcType->isMemberPointerType() ||
2246 SrcType->isBlockPointerType()) {
2247 Result = TC_Success;
2248 }
2249 return Result;
2250 }
2251
2252 bool destIsPtr = DestType->isAnyPointerType() ||
2253 DestType->isBlockPointerType();
2254 bool srcIsPtr = SrcType->isAnyPointerType() ||
2255 SrcType->isBlockPointerType();
2256 if (!destIsPtr && !srcIsPtr) {
2257 // Except for std::nullptr_t->integer and lvalue->reference, which are
2258 // handled above, at least one of the two arguments must be a pointer.
2259 return TC_NotApplicable;
2260 }
2261
2262 if (DestType->isIntegralType(Self.Context)) {
2263 assert(srcIsPtr && "One type must be a pointer");
2264 // C++ 5.2.10p4: A pointer can be explicitly converted to any integral
2265 // type large enough to hold it; except in Microsoft mode, where the
2266 // integral type size doesn't matter (except we don't allow bool).
2267 if ((Self.Context.getTypeSize(SrcType) >
2268 Self.Context.getTypeSize(DestType))) {
2269 bool MicrosoftException =
2270 Self.getLangOpts().MicrosoftExt && !DestType->isBooleanType();
2271 if (MicrosoftException) {
2272 unsigned Diag = SrcType->isVoidPointerType()
2273 ? diag::warn_void_pointer_to_int_cast
2274 : diag::warn_pointer_to_int_cast;
2275 Self.Diag(OpRange.getBegin(), Diag) << SrcType << DestType << OpRange;
2276 } else {
2277 msg = diag::err_bad_reinterpret_cast_small_int;
2278 return TC_Failed;
2279 }
2280 }
2281 Kind = CK_PointerToIntegral;
2282 return TC_Success;
2283 }
2284
2285 if (SrcType->isIntegralOrEnumerationType()) {
2286 assert(destIsPtr && "One type must be a pointer");
2287 checkIntToPointerCast(CStyle, OpRange, SrcExpr.get(), DestType, Self);
2288 // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly
2289 // converted to a pointer.
2290 // C++ 5.2.10p9: [Note: ...a null pointer constant of integral type is not
2291 // necessarily converted to a null pointer value.]
2292 Kind = CK_IntegralToPointer;
2293 return TC_Success;
2294 }
2295
2296 if (!destIsPtr || !srcIsPtr) {
2297 // With the valid non-pointer conversions out of the way, we can be even
2298 // more stringent.
2299 return TC_NotApplicable;
2300 }
2301
2302 // Cannot convert between block pointers and Objective-C object pointers.
2303 if ((SrcType->isBlockPointerType() && DestType->isObjCObjectPointerType()) ||
2304 (DestType->isBlockPointerType() && SrcType->isObjCObjectPointerType()))
2305 return TC_NotApplicable;
2306
2307 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness.
2308 // The C-style cast operator can.
2309 TryCastResult SuccessResult = TC_Success;
2310 if (auto CACK =
2311 CastsAwayConstness(Self, SrcType, DestType, /*CheckCVR=*/!CStyle,
2312 /*CheckObjCLifetime=*/CStyle))
2313 SuccessResult = getCastAwayConstnessCastKind(CACK, msg);
2314
2315 if (IsAddressSpaceConversion(SrcType, DestType)) {
2316 Kind = CK_AddressSpaceConversion;
2317 assert(SrcType->isPointerType() && DestType->isPointerType());
2318 if (!CStyle &&
2319 !DestType->getPointeeType().getQualifiers().isAddressSpaceSupersetOf(
2320 SrcType->getPointeeType().getQualifiers())) {
2321 SuccessResult = TC_Failed;
2322 }
2323 } else if (IsLValueCast) {
2324 Kind = CK_LValueBitCast;
2325 } else if (DestType->isObjCObjectPointerType()) {
2326 Kind = Self.PrepareCastToObjCObjectPointer(SrcExpr);
2327 } else if (DestType->isBlockPointerType()) {
2328 if (!SrcType->isBlockPointerType()) {
2329 Kind = CK_AnyPointerToBlockPointerCast;
2330 } else {
2331 Kind = CK_BitCast;
2332 }
2333 } else {
2334 Kind = CK_BitCast;
2335 }
2336
2337 // Any pointer can be cast to an Objective-C pointer type with a C-style
2338 // cast.
2339 if (CStyle && DestType->isObjCObjectPointerType()) {
2340 return SuccessResult;
2341 }
2342 if (CStyle)
2343 DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType);
2344
2345 DiagnoseCallingConvCast(Self, SrcExpr, DestType, OpRange);
2346
2347 // Not casting away constness, so the only remaining check is for compatible
2348 // pointer categories.
2349
2350 if (SrcType->isFunctionPointerType()) {
2351 if (DestType->isFunctionPointerType()) {
2352 // C++ 5.2.10p6: A pointer to a function can be explicitly converted to
2353 // a pointer to a function of a different type.
2354 return SuccessResult;
2355 }
2356
2357 // C++0x 5.2.10p8: Converting a pointer to a function into a pointer to
2358 // an object type or vice versa is conditionally-supported.
2359 // Compilers support it in C++03 too, though, because it's necessary for
2360 // casting the return value of dlsym() and GetProcAddress().
2361 // FIXME: Conditionally-supported behavior should be configurable in the
2362 // TargetInfo or similar.
2363 Self.Diag(OpRange.getBegin(),
2364 Self.getLangOpts().CPlusPlus11 ?
2365 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj)
2366 << OpRange;
2367 return SuccessResult;
2368 }
2369
2370 if (DestType->isFunctionPointerType()) {
2371 // See above.
2372 Self.Diag(OpRange.getBegin(),
2373 Self.getLangOpts().CPlusPlus11 ?
2374 diag::warn_cxx98_compat_cast_fn_obj : diag::ext_cast_fn_obj)
2375 << OpRange;
2376 return SuccessResult;
2377 }
2378
2379 // Diagnose address space conversion in nested pointers.
2380 QualType DestPtee = DestType->getPointeeType().isNull()
2381 ? DestType->getPointeeType()
2382 : DestType->getPointeeType()->getPointeeType();
2383 QualType SrcPtee = SrcType->getPointeeType().isNull()
2384 ? SrcType->getPointeeType()
2385 : SrcType->getPointeeType()->getPointeeType();
2386 while (!DestPtee.isNull() && !SrcPtee.isNull()) {
2387 if (DestPtee.getAddressSpace() != SrcPtee.getAddressSpace()) {
2388 Self.Diag(OpRange.getBegin(),
2389 diag::warn_bad_cxx_cast_nested_pointer_addr_space)
2390 << CStyle << SrcType << DestType << SrcExpr.get()->getSourceRange();
2391 break;
2392 }
2393 DestPtee = DestPtee->getPointeeType();
2394 SrcPtee = SrcPtee->getPointeeType();
2395 }
2396
2397 // C++ 5.2.10p7: A pointer to an object can be explicitly converted to
2398 // a pointer to an object of different type.
2399 // Void pointers are not specified, but supported by every compiler out there.
2400 // So we finish by allowing everything that remains - it's got to be two
2401 // object pointers.
2402 return SuccessResult;
2403 }
2404
TryAddressSpaceCast(Sema & Self,ExprResult & SrcExpr,QualType DestType,bool CStyle,unsigned & msg,CastKind & Kind)2405 static TryCastResult TryAddressSpaceCast(Sema &Self, ExprResult &SrcExpr,
2406 QualType DestType, bool CStyle,
2407 unsigned &msg, CastKind &Kind) {
2408 if (!Self.getLangOpts().OpenCL)
2409 // FIXME: As compiler doesn't have any information about overlapping addr
2410 // spaces at the moment we have to be permissive here.
2411 return TC_NotApplicable;
2412 // Even though the logic below is general enough and can be applied to
2413 // non-OpenCL mode too, we fast-path above because no other languages
2414 // define overlapping address spaces currently.
2415 auto SrcType = SrcExpr.get()->getType();
2416 // FIXME: Should this be generalized to references? The reference parameter
2417 // however becomes a reference pointee type here and therefore rejected.
2418 // Perhaps this is the right behavior though according to C++.
2419 auto SrcPtrType = SrcType->getAs<PointerType>();
2420 if (!SrcPtrType)
2421 return TC_NotApplicable;
2422 auto DestPtrType = DestType->getAs<PointerType>();
2423 if (!DestPtrType)
2424 return TC_NotApplicable;
2425 auto SrcPointeeType = SrcPtrType->getPointeeType();
2426 auto DestPointeeType = DestPtrType->getPointeeType();
2427 if (!DestPointeeType.isAddressSpaceOverlapping(SrcPointeeType)) {
2428 msg = diag::err_bad_cxx_cast_addr_space_mismatch;
2429 return TC_Failed;
2430 }
2431 auto SrcPointeeTypeWithoutAS =
2432 Self.Context.removeAddrSpaceQualType(SrcPointeeType.getCanonicalType());
2433 auto DestPointeeTypeWithoutAS =
2434 Self.Context.removeAddrSpaceQualType(DestPointeeType.getCanonicalType());
2435 if (Self.Context.hasSameType(SrcPointeeTypeWithoutAS,
2436 DestPointeeTypeWithoutAS)) {
2437 Kind = SrcPointeeType.getAddressSpace() == DestPointeeType.getAddressSpace()
2438 ? CK_NoOp
2439 : CK_AddressSpaceConversion;
2440 return TC_Success;
2441 } else {
2442 return TC_NotApplicable;
2443 }
2444 }
2445
checkAddressSpaceCast(QualType SrcType,QualType DestType)2446 void CastOperation::checkAddressSpaceCast(QualType SrcType, QualType DestType) {
2447 // In OpenCL only conversions between pointers to objects in overlapping
2448 // addr spaces are allowed. v2.0 s6.5.5 - Generic addr space overlaps
2449 // with any named one, except for constant.
2450
2451 // Converting the top level pointee addrspace is permitted for compatible
2452 // addrspaces (such as 'generic int *' to 'local int *' or vice versa), but
2453 // if any of the nested pointee addrspaces differ, we emit a warning
2454 // regardless of addrspace compatibility. This makes
2455 // local int ** p;
2456 // return (generic int **) p;
2457 // warn even though local -> generic is permitted.
2458 if (Self.getLangOpts().OpenCL) {
2459 const Type *DestPtr, *SrcPtr;
2460 bool Nested = false;
2461 unsigned DiagID = diag::err_typecheck_incompatible_address_space;
2462 DestPtr = Self.getASTContext().getCanonicalType(DestType.getTypePtr()),
2463 SrcPtr = Self.getASTContext().getCanonicalType(SrcType.getTypePtr());
2464
2465 while (isa<PointerType>(DestPtr) && isa<PointerType>(SrcPtr)) {
2466 const PointerType *DestPPtr = cast<PointerType>(DestPtr);
2467 const PointerType *SrcPPtr = cast<PointerType>(SrcPtr);
2468 QualType DestPPointee = DestPPtr->getPointeeType();
2469 QualType SrcPPointee = SrcPPtr->getPointeeType();
2470 if (Nested
2471 ? DestPPointee.getAddressSpace() != SrcPPointee.getAddressSpace()
2472 : !DestPPointee.isAddressSpaceOverlapping(SrcPPointee)) {
2473 Self.Diag(OpRange.getBegin(), DiagID)
2474 << SrcType << DestType << Sema::AA_Casting
2475 << SrcExpr.get()->getSourceRange();
2476 if (!Nested)
2477 SrcExpr = ExprError();
2478 return;
2479 }
2480
2481 DestPtr = DestPPtr->getPointeeType().getTypePtr();
2482 SrcPtr = SrcPPtr->getPointeeType().getTypePtr();
2483 Nested = true;
2484 DiagID = diag::ext_nested_pointer_qualifier_mismatch;
2485 }
2486 }
2487 }
2488
CheckCXXCStyleCast(bool FunctionalStyle,bool ListInitialization)2489 void CastOperation::CheckCXXCStyleCast(bool FunctionalStyle,
2490 bool ListInitialization) {
2491 assert(Self.getLangOpts().CPlusPlus);
2492
2493 // Handle placeholders.
2494 if (isPlaceholder()) {
2495 // C-style casts can resolve __unknown_any types.
2496 if (claimPlaceholder(BuiltinType::UnknownAny)) {
2497 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType,
2498 SrcExpr.get(), Kind,
2499 ValueKind, BasePath);
2500 return;
2501 }
2502
2503 checkNonOverloadPlaceholders();
2504 if (SrcExpr.isInvalid())
2505 return;
2506 }
2507
2508 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
2509 // This test is outside everything else because it's the only case where
2510 // a non-lvalue-reference target type does not lead to decay.
2511 if (DestType->isVoidType()) {
2512 Kind = CK_ToVoid;
2513
2514 if (claimPlaceholder(BuiltinType::Overload)) {
2515 Self.ResolveAndFixSingleFunctionTemplateSpecialization(
2516 SrcExpr, /* Decay Function to ptr */ false,
2517 /* Complain */ true, DestRange, DestType,
2518 diag::err_bad_cstyle_cast_overload);
2519 if (SrcExpr.isInvalid())
2520 return;
2521 }
2522
2523 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
2524 return;
2525 }
2526
2527 // If the type is dependent, we won't do any other semantic analysis now.
2528 if (DestType->isDependentType() || SrcExpr.get()->isTypeDependent() ||
2529 SrcExpr.get()->isValueDependent()) {
2530 assert(Kind == CK_Dependent);
2531 return;
2532 }
2533
2534 if (ValueKind == VK_RValue && !DestType->isRecordType() &&
2535 !isPlaceholder(BuiltinType::Overload)) {
2536 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
2537 if (SrcExpr.isInvalid())
2538 return;
2539 }
2540
2541 // AltiVec vector initialization with a single literal.
2542 if (const VectorType *vecTy = DestType->getAs<VectorType>())
2543 if (vecTy->getVectorKind() == VectorType::AltiVecVector
2544 && (SrcExpr.get()->getType()->isIntegerType()
2545 || SrcExpr.get()->getType()->isFloatingType())) {
2546 Kind = CK_VectorSplat;
2547 SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get());
2548 return;
2549 }
2550
2551 // C++ [expr.cast]p5: The conversions performed by
2552 // - a const_cast,
2553 // - a static_cast,
2554 // - a static_cast followed by a const_cast,
2555 // - a reinterpret_cast, or
2556 // - a reinterpret_cast followed by a const_cast,
2557 // can be performed using the cast notation of explicit type conversion.
2558 // [...] If a conversion can be interpreted in more than one of the ways
2559 // listed above, the interpretation that appears first in the list is used,
2560 // even if a cast resulting from that interpretation is ill-formed.
2561 // In plain language, this means trying a const_cast ...
2562 // Note that for address space we check compatibility after const_cast.
2563 unsigned msg = diag::err_bad_cxx_cast_generic;
2564 TryCastResult tcr = TryConstCast(Self, SrcExpr, DestType,
2565 /*CStyle*/ true, msg);
2566 if (SrcExpr.isInvalid())
2567 return;
2568 if (isValidCast(tcr))
2569 Kind = CK_NoOp;
2570
2571 Sema::CheckedConversionKind CCK =
2572 FunctionalStyle ? Sema::CCK_FunctionalCast : Sema::CCK_CStyleCast;
2573 if (tcr == TC_NotApplicable) {
2574 tcr = TryAddressSpaceCast(Self, SrcExpr, DestType, /*CStyle*/ true, msg,
2575 Kind);
2576 if (SrcExpr.isInvalid())
2577 return;
2578
2579 if (tcr == TC_NotApplicable) {
2580 // ... or if that is not possible, a static_cast, ignoring const and
2581 // addr space, ...
2582 tcr = TryStaticCast(Self, SrcExpr, DestType, CCK, OpRange, msg, Kind,
2583 BasePath, ListInitialization);
2584 if (SrcExpr.isInvalid())
2585 return;
2586
2587 if (tcr == TC_NotApplicable) {
2588 // ... and finally a reinterpret_cast, ignoring const and addr space.
2589 tcr = TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/ true,
2590 OpRange, msg, Kind);
2591 if (SrcExpr.isInvalid())
2592 return;
2593 }
2594 }
2595 }
2596
2597 if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers() &&
2598 isValidCast(tcr))
2599 checkObjCConversion(CCK);
2600
2601 if (tcr != TC_Success && msg != 0) {
2602 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
2603 DeclAccessPair Found;
2604 FunctionDecl *Fn = Self.ResolveAddressOfOverloadedFunction(SrcExpr.get(),
2605 DestType,
2606 /*Complain*/ true,
2607 Found);
2608 if (Fn) {
2609 // If DestType is a function type (not to be confused with the function
2610 // pointer type), it will be possible to resolve the function address,
2611 // but the type cast should be considered as failure.
2612 OverloadExpr *OE = OverloadExpr::find(SrcExpr.get()).Expression;
2613 Self.Diag(OpRange.getBegin(), diag::err_bad_cstyle_cast_overload)
2614 << OE->getName() << DestType << OpRange
2615 << OE->getQualifierLoc().getSourceRange();
2616 Self.NoteAllOverloadCandidates(SrcExpr.get());
2617 }
2618 } else {
2619 diagnoseBadCast(Self, msg, (FunctionalStyle ? CT_Functional : CT_CStyle),
2620 OpRange, SrcExpr.get(), DestType, ListInitialization);
2621 }
2622 }
2623
2624 if (isValidCast(tcr)) {
2625 if (Kind == CK_BitCast)
2626 checkCastAlign();
2627 } else {
2628 SrcExpr = ExprError();
2629 }
2630 }
2631
2632 /// DiagnoseBadFunctionCast - Warn whenever a function call is cast to a
2633 /// non-matching type. Such as enum function call to int, int call to
2634 /// pointer; etc. Cast to 'void' is an exception.
DiagnoseBadFunctionCast(Sema & Self,const ExprResult & SrcExpr,QualType DestType)2635 static void DiagnoseBadFunctionCast(Sema &Self, const ExprResult &SrcExpr,
2636 QualType DestType) {
2637 if (Self.Diags.isIgnored(diag::warn_bad_function_cast,
2638 SrcExpr.get()->getExprLoc()))
2639 return;
2640
2641 if (!isa<CallExpr>(SrcExpr.get()))
2642 return;
2643
2644 QualType SrcType = SrcExpr.get()->getType();
2645 if (DestType.getUnqualifiedType()->isVoidType())
2646 return;
2647 if ((SrcType->isAnyPointerType() || SrcType->isBlockPointerType())
2648 && (DestType->isAnyPointerType() || DestType->isBlockPointerType()))
2649 return;
2650 if (SrcType->isIntegerType() && DestType->isIntegerType() &&
2651 (SrcType->isBooleanType() == DestType->isBooleanType()) &&
2652 (SrcType->isEnumeralType() == DestType->isEnumeralType()))
2653 return;
2654 if (SrcType->isRealFloatingType() && DestType->isRealFloatingType())
2655 return;
2656 if (SrcType->isEnumeralType() && DestType->isEnumeralType())
2657 return;
2658 if (SrcType->isComplexType() && DestType->isComplexType())
2659 return;
2660 if (SrcType->isComplexIntegerType() && DestType->isComplexIntegerType())
2661 return;
2662
2663 Self.Diag(SrcExpr.get()->getExprLoc(),
2664 diag::warn_bad_function_cast)
2665 << SrcType << DestType << SrcExpr.get()->getSourceRange();
2666 }
2667
2668 /// Check the semantics of a C-style cast operation, in C.
CheckCStyleCast()2669 void CastOperation::CheckCStyleCast() {
2670 assert(!Self.getLangOpts().CPlusPlus);
2671
2672 // C-style casts can resolve __unknown_any types.
2673 if (claimPlaceholder(BuiltinType::UnknownAny)) {
2674 SrcExpr = Self.checkUnknownAnyCast(DestRange, DestType,
2675 SrcExpr.get(), Kind,
2676 ValueKind, BasePath);
2677 return;
2678 }
2679
2680 // C99 6.5.4p2: the cast type needs to be void or scalar and the expression
2681 // type needs to be scalar.
2682 if (DestType->isVoidType()) {
2683 // We don't necessarily do lvalue-to-rvalue conversions on this.
2684 SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
2685 if (SrcExpr.isInvalid())
2686 return;
2687
2688 // Cast to void allows any expr type.
2689 Kind = CK_ToVoid;
2690 return;
2691 }
2692
2693 // Overloads are allowed with C extensions, so we need to support them.
2694 if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
2695 DeclAccessPair DAP;
2696 if (FunctionDecl *FD = Self.ResolveAddressOfOverloadedFunction(
2697 SrcExpr.get(), DestType, /*Complain=*/true, DAP))
2698 SrcExpr = Self.FixOverloadedFunctionReference(SrcExpr.get(), DAP, FD);
2699 else
2700 return;
2701 assert(SrcExpr.isUsable());
2702 }
2703 SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
2704 if (SrcExpr.isInvalid())
2705 return;
2706 QualType SrcType = SrcExpr.get()->getType();
2707
2708 assert(!SrcType->isPlaceholderType());
2709
2710 checkAddressSpaceCast(SrcType, DestType);
2711 if (SrcExpr.isInvalid())
2712 return;
2713
2714 if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
2715 diag::err_typecheck_cast_to_incomplete)) {
2716 SrcExpr = ExprError();
2717 return;
2718 }
2719
2720 // Allow casting a sizeless built-in type to itself.
2721 if (DestType->isSizelessBuiltinType() &&
2722 Self.Context.hasSameUnqualifiedType(DestType, SrcType)) {
2723 Kind = CK_NoOp;
2724 return;
2725 }
2726
2727 if (!DestType->isScalarType() && !DestType->isVectorType()) {
2728 const RecordType *DestRecordTy = DestType->getAs<RecordType>();
2729
2730 if (DestRecordTy && Self.Context.hasSameUnqualifiedType(DestType, SrcType)){
2731 // GCC struct/union extension: allow cast to self.
2732 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_nonscalar)
2733 << DestType << SrcExpr.get()->getSourceRange();
2734 Kind = CK_NoOp;
2735 return;
2736 }
2737
2738 // GCC's cast to union extension.
2739 if (DestRecordTy && DestRecordTy->getDecl()->isUnion()) {
2740 RecordDecl *RD = DestRecordTy->getDecl();
2741 if (CastExpr::getTargetFieldForToUnionCast(RD, SrcType)) {
2742 Self.Diag(OpRange.getBegin(), diag::ext_typecheck_cast_to_union)
2743 << SrcExpr.get()->getSourceRange();
2744 Kind = CK_ToUnion;
2745 return;
2746 } else {
2747 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cast_to_union_no_type)
2748 << SrcType << SrcExpr.get()->getSourceRange();
2749 SrcExpr = ExprError();
2750 return;
2751 }
2752 }
2753
2754 // OpenCL v2.0 s6.13.10 - Allow casts from '0' to event_t type.
2755 if (Self.getLangOpts().OpenCL && DestType->isEventT()) {
2756 Expr::EvalResult Result;
2757 if (SrcExpr.get()->EvaluateAsInt(Result, Self.Context)) {
2758 llvm::APSInt CastInt = Result.Val.getInt();
2759 if (0 == CastInt) {
2760 Kind = CK_ZeroToOCLOpaqueType;
2761 return;
2762 }
2763 Self.Diag(OpRange.getBegin(),
2764 diag::err_opencl_cast_non_zero_to_event_t)
2765 << CastInt.toString(10) << SrcExpr.get()->getSourceRange();
2766 SrcExpr = ExprError();
2767 return;
2768 }
2769 }
2770
2771 // Reject any other conversions to non-scalar types.
2772 Self.Diag(OpRange.getBegin(), diag::err_typecheck_cond_expect_scalar)
2773 << DestType << SrcExpr.get()->getSourceRange();
2774 SrcExpr = ExprError();
2775 return;
2776 }
2777
2778 // The type we're casting to is known to be a scalar or vector.
2779
2780 // Require the operand to be a scalar or vector.
2781 if (!SrcType->isScalarType() && !SrcType->isVectorType()) {
2782 Self.Diag(SrcExpr.get()->getExprLoc(),
2783 diag::err_typecheck_expect_scalar_operand)
2784 << SrcType << SrcExpr.get()->getSourceRange();
2785 SrcExpr = ExprError();
2786 return;
2787 }
2788
2789 if (DestType->isExtVectorType()) {
2790 SrcExpr = Self.CheckExtVectorCast(OpRange, DestType, SrcExpr.get(), Kind);
2791 return;
2792 }
2793
2794 if (const VectorType *DestVecTy = DestType->getAs<VectorType>()) {
2795 if (DestVecTy->getVectorKind() == VectorType::AltiVecVector &&
2796 (SrcType->isIntegerType() || SrcType->isFloatingType())) {
2797 Kind = CK_VectorSplat;
2798 SrcExpr = Self.prepareVectorSplat(DestType, SrcExpr.get());
2799 } else if (Self.CheckVectorCast(OpRange, DestType, SrcType, Kind)) {
2800 SrcExpr = ExprError();
2801 }
2802 return;
2803 }
2804
2805 if (SrcType->isVectorType()) {
2806 if (Self.CheckVectorCast(OpRange, SrcType, DestType, Kind))
2807 SrcExpr = ExprError();
2808 return;
2809 }
2810
2811 // The source and target types are both scalars, i.e.
2812 // - arithmetic types (fundamental, enum, and complex)
2813 // - all kinds of pointers
2814 // Note that member pointers were filtered out with C++, above.
2815
2816 if (isa<ObjCSelectorExpr>(SrcExpr.get())) {
2817 Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_selector_expr);
2818 SrcExpr = ExprError();
2819 return;
2820 }
2821
2822 // Can't cast to or from bfloat
2823 if (DestType->isBFloat16Type() && !SrcType->isBFloat16Type()) {
2824 Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_to_bfloat16)
2825 << SrcExpr.get()->getSourceRange();
2826 SrcExpr = ExprError();
2827 return;
2828 }
2829 if (SrcType->isBFloat16Type() && !DestType->isBFloat16Type()) {
2830 Self.Diag(SrcExpr.get()->getExprLoc(), diag::err_cast_from_bfloat16)
2831 << SrcExpr.get()->getSourceRange();
2832 SrcExpr = ExprError();
2833 return;
2834 }
2835
2836 // If either type is a pointer, the other type has to be either an
2837 // integer or a pointer.
2838 if (!DestType->isArithmeticType()) {
2839 if (!SrcType->isIntegralType(Self.Context) && SrcType->isArithmeticType()) {
2840 Self.Diag(SrcExpr.get()->getExprLoc(),
2841 diag::err_cast_pointer_from_non_pointer_int)
2842 << SrcType << SrcExpr.get()->getSourceRange();
2843 SrcExpr = ExprError();
2844 return;
2845 }
2846 checkIntToPointerCast(/* CStyle */ true, OpRange, SrcExpr.get(), DestType,
2847 Self);
2848 } else if (!SrcType->isArithmeticType()) {
2849 if (!DestType->isIntegralType(Self.Context) &&
2850 DestType->isArithmeticType()) {
2851 Self.Diag(SrcExpr.get()->getBeginLoc(),
2852 diag::err_cast_pointer_to_non_pointer_int)
2853 << DestType << SrcExpr.get()->getSourceRange();
2854 SrcExpr = ExprError();
2855 return;
2856 }
2857
2858 if ((Self.Context.getTypeSize(SrcType) >
2859 Self.Context.getTypeSize(DestType)) &&
2860 !DestType->isBooleanType()) {
2861 // C 6.3.2.3p6: Any pointer type may be converted to an integer type.
2862 // Except as previously specified, the result is implementation-defined.
2863 // If the result cannot be represented in the integer type, the behavior
2864 // is undefined. The result need not be in the range of values of any
2865 // integer type.
2866 unsigned Diag;
2867 if (SrcType->isVoidPointerType())
2868 Diag = DestType->isEnumeralType() ? diag::warn_void_pointer_to_enum_cast
2869 : diag::warn_void_pointer_to_int_cast;
2870 else if (DestType->isEnumeralType())
2871 Diag = diag::warn_pointer_to_enum_cast;
2872 else
2873 Diag = diag::warn_pointer_to_int_cast;
2874 Self.Diag(OpRange.getBegin(), Diag) << SrcType << DestType << OpRange;
2875 }
2876 }
2877
2878 if (Self.getLangOpts().OpenCL &&
2879 !Self.getOpenCLOptions().isEnabled("cl_khr_fp16")) {
2880 if (DestType->isHalfType()) {
2881 Self.Diag(SrcExpr.get()->getBeginLoc(), diag::err_opencl_cast_to_half)
2882 << DestType << SrcExpr.get()->getSourceRange();
2883 SrcExpr = ExprError();
2884 return;
2885 }
2886 }
2887
2888 // ARC imposes extra restrictions on casts.
2889 if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers()) {
2890 checkObjCConversion(Sema::CCK_CStyleCast);
2891 if (SrcExpr.isInvalid())
2892 return;
2893
2894 const PointerType *CastPtr = DestType->getAs<PointerType>();
2895 if (Self.getLangOpts().ObjCAutoRefCount && CastPtr) {
2896 if (const PointerType *ExprPtr = SrcType->getAs<PointerType>()) {
2897 Qualifiers CastQuals = CastPtr->getPointeeType().getQualifiers();
2898 Qualifiers ExprQuals = ExprPtr->getPointeeType().getQualifiers();
2899 if (CastPtr->getPointeeType()->isObjCLifetimeType() &&
2900 ExprPtr->getPointeeType()->isObjCLifetimeType() &&
2901 !CastQuals.compatiblyIncludesObjCLifetime(ExprQuals)) {
2902 Self.Diag(SrcExpr.get()->getBeginLoc(),
2903 diag::err_typecheck_incompatible_ownership)
2904 << SrcType << DestType << Sema::AA_Casting
2905 << SrcExpr.get()->getSourceRange();
2906 return;
2907 }
2908 }
2909 }
2910 else if (!Self.CheckObjCARCUnavailableWeakConversion(DestType, SrcType)) {
2911 Self.Diag(SrcExpr.get()->getBeginLoc(),
2912 diag::err_arc_convesion_of_weak_unavailable)
2913 << 1 << SrcType << DestType << SrcExpr.get()->getSourceRange();
2914 SrcExpr = ExprError();
2915 return;
2916 }
2917 }
2918
2919 DiagnoseCastOfObjCSEL(Self, SrcExpr, DestType);
2920 DiagnoseCallingConvCast(Self, SrcExpr, DestType, OpRange);
2921 DiagnoseBadFunctionCast(Self, SrcExpr, DestType);
2922 Kind = Self.PrepareScalarCast(SrcExpr, DestType);
2923 if (SrcExpr.isInvalid())
2924 return;
2925
2926 if (Kind == CK_BitCast)
2927 checkCastAlign();
2928 }
2929
CheckBuiltinBitCast()2930 void CastOperation::CheckBuiltinBitCast() {
2931 QualType SrcType = SrcExpr.get()->getType();
2932
2933 if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
2934 diag::err_typecheck_cast_to_incomplete) ||
2935 Self.RequireCompleteType(OpRange.getBegin(), SrcType,
2936 diag::err_incomplete_type)) {
2937 SrcExpr = ExprError();
2938 return;
2939 }
2940
2941 if (SrcExpr.get()->isRValue())
2942 SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcType, SrcExpr.get(),
2943 /*IsLValueReference=*/false);
2944
2945 CharUnits DestSize = Self.Context.getTypeSizeInChars(DestType);
2946 CharUnits SourceSize = Self.Context.getTypeSizeInChars(SrcType);
2947 if (DestSize != SourceSize) {
2948 Self.Diag(OpRange.getBegin(), diag::err_bit_cast_type_size_mismatch)
2949 << (int)SourceSize.getQuantity() << (int)DestSize.getQuantity();
2950 SrcExpr = ExprError();
2951 return;
2952 }
2953
2954 if (!DestType.isTriviallyCopyableType(Self.Context)) {
2955 Self.Diag(OpRange.getBegin(), diag::err_bit_cast_non_trivially_copyable)
2956 << 1;
2957 SrcExpr = ExprError();
2958 return;
2959 }
2960
2961 if (!SrcType.isTriviallyCopyableType(Self.Context)) {
2962 Self.Diag(OpRange.getBegin(), diag::err_bit_cast_non_trivially_copyable)
2963 << 0;
2964 SrcExpr = ExprError();
2965 return;
2966 }
2967
2968 Kind = CK_LValueToRValueBitCast;
2969 }
2970
2971 /// DiagnoseCastQual - Warn whenever casts discards a qualifiers, be it either
2972 /// const, volatile or both.
DiagnoseCastQual(Sema & Self,const ExprResult & SrcExpr,QualType DestType)2973 static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr,
2974 QualType DestType) {
2975 if (SrcExpr.isInvalid())
2976 return;
2977
2978 QualType SrcType = SrcExpr.get()->getType();
2979 if (!((SrcType->isAnyPointerType() && DestType->isAnyPointerType()) ||
2980 DestType->isLValueReferenceType()))
2981 return;
2982
2983 QualType TheOffendingSrcType, TheOffendingDestType;
2984 Qualifiers CastAwayQualifiers;
2985 if (CastsAwayConstness(Self, SrcType, DestType, true, false,
2986 &TheOffendingSrcType, &TheOffendingDestType,
2987 &CastAwayQualifiers) !=
2988 CastAwayConstnessKind::CACK_Similar)
2989 return;
2990
2991 // FIXME: 'restrict' is not properly handled here.
2992 int qualifiers = -1;
2993 if (CastAwayQualifiers.hasConst() && CastAwayQualifiers.hasVolatile()) {
2994 qualifiers = 0;
2995 } else if (CastAwayQualifiers.hasConst()) {
2996 qualifiers = 1;
2997 } else if (CastAwayQualifiers.hasVolatile()) {
2998 qualifiers = 2;
2999 }
3000 // This is a variant of int **x; const int **y = (const int **)x;
3001 if (qualifiers == -1)
3002 Self.Diag(SrcExpr.get()->getBeginLoc(), diag::warn_cast_qual2)
3003 << SrcType << DestType;
3004 else
3005 Self.Diag(SrcExpr.get()->getBeginLoc(), diag::warn_cast_qual)
3006 << TheOffendingSrcType << TheOffendingDestType << qualifiers;
3007 }
3008
BuildCStyleCastExpr(SourceLocation LPLoc,TypeSourceInfo * CastTypeInfo,SourceLocation RPLoc,Expr * CastExpr)3009 ExprResult Sema::BuildCStyleCastExpr(SourceLocation LPLoc,
3010 TypeSourceInfo *CastTypeInfo,
3011 SourceLocation RPLoc,
3012 Expr *CastExpr) {
3013 CastOperation Op(*this, CastTypeInfo->getType(), CastExpr);
3014 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange();
3015 Op.OpRange = SourceRange(LPLoc, CastExpr->getEndLoc());
3016
3017 if (getLangOpts().CPlusPlus) {
3018 Op.CheckCXXCStyleCast(/*FunctionalCast=*/ false,
3019 isa<InitListExpr>(CastExpr));
3020 } else {
3021 Op.CheckCStyleCast();
3022 }
3023
3024 if (Op.SrcExpr.isInvalid())
3025 return ExprError();
3026
3027 // -Wcast-qual
3028 DiagnoseCastQual(Op.Self, Op.SrcExpr, Op.DestType);
3029
3030 return Op.complete(CStyleCastExpr::Create(Context, Op.ResultType,
3031 Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
3032 &Op.BasePath, CastTypeInfo, LPLoc, RPLoc));
3033 }
3034
BuildCXXFunctionalCastExpr(TypeSourceInfo * CastTypeInfo,QualType Type,SourceLocation LPLoc,Expr * CastExpr,SourceLocation RPLoc)3035 ExprResult Sema::BuildCXXFunctionalCastExpr(TypeSourceInfo *CastTypeInfo,
3036 QualType Type,
3037 SourceLocation LPLoc,
3038 Expr *CastExpr,
3039 SourceLocation RPLoc) {
3040 assert(LPLoc.isValid() && "List-initialization shouldn't get here.");
3041 CastOperation Op(*this, Type, CastExpr);
3042 Op.DestRange = CastTypeInfo->getTypeLoc().getSourceRange();
3043 Op.OpRange = SourceRange(Op.DestRange.getBegin(), CastExpr->getEndLoc());
3044
3045 Op.CheckCXXCStyleCast(/*FunctionalCast=*/true, /*ListInit=*/false);
3046 if (Op.SrcExpr.isInvalid())
3047 return ExprError();
3048
3049 auto *SubExpr = Op.SrcExpr.get();
3050 if (auto *BindExpr = dyn_cast<CXXBindTemporaryExpr>(SubExpr))
3051 SubExpr = BindExpr->getSubExpr();
3052 if (auto *ConstructExpr = dyn_cast<CXXConstructExpr>(SubExpr))
3053 ConstructExpr->setParenOrBraceRange(SourceRange(LPLoc, RPLoc));
3054
3055 return Op.complete(CXXFunctionalCastExpr::Create(Context, Op.ResultType,
3056 Op.ValueKind, CastTypeInfo, Op.Kind,
3057 Op.SrcExpr.get(), &Op.BasePath, LPLoc, RPLoc));
3058 }
3059