1 //===--- SemaNamedCast.cpp - Semantic Analysis for Named Casts ------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements semantic analysis for C++ named casts.
12 //===----------------------------------------------------------------------===//
16 #include "clang/AST/ExprCXX.h"
17 #include "clang/AST/ASTContext.h"
18 #include "clang/AST/CXXInheritance.h"
19 #include "clang/Basic/PartialDiagnostic.h"
20 #include "llvm/ADT/SmallVector.h"
22 using namespace clang;
25 TC_NotApplicable, ///< The cast method is not applicable.
26 TC_Success, ///< The cast method is appropriate and successful.
27 TC_Failed ///< The cast method is appropriate, but failed. A
28 ///< diagnostic has been emitted.
32 CT_Const, ///< const_cast
33 CT_Static, ///< static_cast
34 CT_Reinterpret, ///< reinterpret_cast
35 CT_Dynamic, ///< dynamic_cast
36 CT_CStyle, ///< (Type)expr
37 CT_Functional ///< Type(expr)
40 static void CheckConstCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
41 const SourceRange &OpRange,
42 const SourceRange &DestRange);
43 static void CheckReinterpretCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
44 const SourceRange &OpRange,
45 const SourceRange &DestRange,
46 CastExpr::CastKind &Kind);
47 static void CheckStaticCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
48 const SourceRange &OpRange,
49 CastExpr::CastKind &Kind,
50 CXXMethodDecl *&ConversionDecl);
51 static void CheckDynamicCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
52 const SourceRange &OpRange,
53 const SourceRange &DestRange,
54 CastExpr::CastKind &Kind);
56 static bool CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType);
58 // The Try functions attempt a specific way of casting. If they succeed, they
59 // return TC_Success. If their way of casting is not appropriate for the given
60 // arguments, they return TC_NotApplicable and *may* set diag to a diagnostic
61 // to emit if no other way succeeds. If their way of casting is appropriate but
62 // fails, they return TC_Failed and *must* set diag; they can set it to 0 if
63 // they emit a specialized diagnostic.
64 // All diagnostics returned by these functions must expect the same three
66 // %0: Cast Type (a value from the CastType enumeration)
68 // %2: Destination Type
69 static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr,
70 QualType DestType, unsigned &msg);
71 static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr,
72 QualType DestType, bool CStyle,
73 const SourceRange &OpRange,
75 CastExpr::CastKind &Kind);
76 static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType,
77 QualType DestType, bool CStyle,
78 const SourceRange &OpRange,
80 CastExpr::CastKind &Kind);
81 static TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType,
82 CanQualType DestType, bool CStyle,
83 const SourceRange &OpRange,
85 QualType OrigDestType, unsigned &msg,
86 CastExpr::CastKind &Kind);
87 static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, QualType SrcType,
88 QualType DestType,bool CStyle,
89 const SourceRange &OpRange,
91 CastExpr::CastKind &Kind);
92 static TryCastResult TryStaticImplicitCast(Sema &Self, Expr *&SrcExpr,
93 QualType DestType, bool CStyle,
94 const SourceRange &OpRange,
96 CastExpr::CastKind &Kind,
97 CXXMethodDecl *&ConversionDecl);
98 static TryCastResult TryStaticCast(Sema &Self, Expr *&SrcExpr,
99 QualType DestType, bool CStyle,
100 const SourceRange &OpRange,
102 CastExpr::CastKind &Kind,
103 CXXMethodDecl *&ConversionDecl);
104 static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType,
105 bool CStyle, unsigned &msg);
106 static TryCastResult TryReinterpretCast(Sema &Self, Expr *SrcExpr,
107 QualType DestType, bool CStyle,
108 const SourceRange &OpRange,
110 CastExpr::CastKind &Kind);
112 /// ActOnCXXNamedCast - Parse {dynamic,static,reinterpret,const}_cast's.
113 Action::OwningExprResult
114 Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
115 SourceLocation LAngleBracketLoc, TypeTy *Ty,
116 SourceLocation RAngleBracketLoc,
117 SourceLocation LParenLoc, ExprArg E,
118 SourceLocation RParenLoc) {
120 TypeSourceInfo *DestTInfo;
121 QualType DestType = GetTypeFromParser(Ty, &DestTInfo);
123 DestTInfo = Context.getTrivialTypeSourceInfo(DestType, SourceLocation());
125 return BuildCXXNamedCast(OpLoc, Kind, DestTInfo, move(E),
126 SourceRange(LAngleBracketLoc, RAngleBracketLoc),
127 SourceRange(LParenLoc, RParenLoc));
130 Action::OwningExprResult
131 Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
132 TypeSourceInfo *DestTInfo, ExprArg E,
133 SourceRange AngleBrackets, SourceRange Parens) {
134 Expr *Ex = E.takeAs<Expr>();
135 QualType DestType = DestTInfo->getType();
137 SourceRange OpRange(OpLoc, Parens.getEnd());
138 SourceRange DestRange = AngleBrackets;
140 // If the type is dependent, we won't do the semantic analysis now.
141 // FIXME: should we check this in a more fine-grained manner?
142 bool TypeDependent = DestType->isDependentType() || Ex->isTypeDependent();
145 default: assert(0 && "Unknown C++ cast!");
147 case tok::kw_const_cast:
149 CheckConstCast(*this, Ex, DestType, OpRange, DestRange);
150 return Owned(new (Context) CXXConstCastExpr(DestType.getNonReferenceType(),
151 Ex, DestTInfo, OpLoc));
153 case tok::kw_dynamic_cast: {
154 CastExpr::CastKind Kind = CastExpr::CK_Unknown;
156 CheckDynamicCast(*this, Ex, DestType, OpRange, DestRange, Kind);
157 return Owned(new (Context)CXXDynamicCastExpr(DestType.getNonReferenceType(),
158 Kind, Ex, DestTInfo, OpLoc));
160 case tok::kw_reinterpret_cast: {
161 CastExpr::CastKind Kind = CastExpr::CK_Unknown;
163 CheckReinterpretCast(*this, Ex, DestType, OpRange, DestRange, Kind);
164 return Owned(new (Context) CXXReinterpretCastExpr(
165 DestType.getNonReferenceType(),
166 Kind, Ex, DestTInfo, OpLoc));
168 case tok::kw_static_cast: {
169 CastExpr::CastKind Kind = CastExpr::CK_Unknown;
170 if (!TypeDependent) {
171 CXXMethodDecl *Method = 0;
173 CheckStaticCast(*this, Ex, DestType, OpRange, Kind, Method);
176 OwningExprResult CastArg
177 = BuildCXXCastArgument(OpLoc, DestType.getNonReferenceType(),
178 Kind, Method, Owned(Ex));
179 if (CastArg.isInvalid())
182 Ex = CastArg.takeAs<Expr>();
186 return Owned(new (Context) CXXStaticCastExpr(DestType.getNonReferenceType(),
187 Kind, Ex, DestTInfo, OpLoc));
194 /// UnwrapDissimilarPointerTypes - Like Sema::UnwrapSimilarPointerTypes,
195 /// this removes one level of indirection from both types, provided that they're
196 /// the same kind of pointer (plain or to-member). Unlike the Sema function,
197 /// this one doesn't care if the two pointers-to-member don't point into the
198 /// same class. This is because CastsAwayConstness doesn't care.
199 bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) {
200 const PointerType *T1PtrType = T1->getAs<PointerType>(),
201 *T2PtrType = T2->getAs<PointerType>();
202 if (T1PtrType && T2PtrType) {
203 T1 = T1PtrType->getPointeeType();
204 T2 = T2PtrType->getPointeeType();
208 const MemberPointerType *T1MPType = T1->getAs<MemberPointerType>(),
209 *T2MPType = T2->getAs<MemberPointerType>();
210 if (T1MPType && T2MPType) {
211 T1 = T1MPType->getPointeeType();
212 T2 = T2MPType->getPointeeType();
218 /// CastsAwayConstness - Check if the pointer conversion from SrcType to
219 /// DestType casts away constness as defined in C++ 5.2.11p8ff. This is used by
220 /// the cast checkers. Both arguments must denote pointer (possibly to member)
223 CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType) {
224 // Casting away constness is defined in C++ 5.2.11p8 with reference to
225 // C++ 4.4. We piggyback on Sema::IsQualificationConversion for this, since
226 // the rules are non-trivial. So first we construct Tcv *...cv* as described
228 assert((SrcType->isPointerType() || SrcType->isMemberPointerType()) &&
229 "Source type is not pointer or pointer to member.");
230 assert((DestType->isPointerType() || DestType->isMemberPointerType()) &&
231 "Destination type is not pointer or pointer to member.");
233 QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType),
234 UnwrappedDestType = Self.Context.getCanonicalType(DestType);
235 llvm::SmallVector<Qualifiers, 8> cv1, cv2;
237 // Find the qualifications.
238 while (UnwrapDissimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) {
239 cv1.push_back(UnwrappedSrcType.getQualifiers());
240 cv2.push_back(UnwrappedDestType.getQualifiers());
242 assert(cv1.size() > 0 && "Must have at least one pointer level.");
244 // Construct void pointers with those qualifiers (in reverse order of
245 // unwrapping, of course).
246 QualType SrcConstruct = Self.Context.VoidTy;
247 QualType DestConstruct = Self.Context.VoidTy;
248 ASTContext &Context = Self.Context;
249 for (llvm::SmallVector<Qualifiers, 8>::reverse_iterator i1 = cv1.rbegin(),
251 i1 != cv1.rend(); ++i1, ++i2) {
253 = Context.getPointerType(Context.getQualifiedType(SrcConstruct, *i1));
255 = Context.getPointerType(Context.getQualifiedType(DestConstruct, *i2));
258 // Test if they're compatible.
259 return SrcConstruct != DestConstruct &&
260 !Self.IsQualificationConversion(SrcConstruct, DestConstruct);
263 /// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid.
264 /// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime-
265 /// checked downcasts in class hierarchies.
267 CheckDynamicCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
268 const SourceRange &OpRange,
269 const SourceRange &DestRange, CastExpr::CastKind &Kind) {
270 QualType OrigDestType = DestType, OrigSrcType = SrcExpr->getType();
271 DestType = Self.Context.getCanonicalType(DestType);
273 // C++ 5.2.7p1: T shall be a pointer or reference to a complete class type,
274 // or "pointer to cv void".
276 QualType DestPointee;
277 const PointerType *DestPointer = DestType->getAs<PointerType>();
278 const ReferenceType *DestReference = DestType->getAs<ReferenceType>();
280 DestPointee = DestPointer->getPointeeType();
281 } else if (DestReference) {
282 DestPointee = DestReference->getPointeeType();
284 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr)
285 << OrigDestType << DestRange;
289 const RecordType *DestRecord = DestPointee->getAs<RecordType>();
290 if (DestPointee->isVoidType()) {
291 assert(DestPointer && "Reference to void is not possible");
292 } else if (DestRecord) {
293 if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee,
294 PDiag(diag::err_bad_dynamic_cast_incomplete)
298 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
299 << DestPointee.getUnqualifiedType() << DestRange;
303 // C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to
304 // complete class type, [...]. If T is an lvalue reference type, v shall be
305 // an lvalue of a complete class type, [...]. If T is an rvalue reference
306 // type, v shall be an expression having a complete effective class type,
309 QualType SrcType = Self.Context.getCanonicalType(OrigSrcType);
312 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
313 SrcPointee = SrcPointer->getPointeeType();
315 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr)
316 << OrigSrcType << SrcExpr->getSourceRange();
319 } else if (DestReference->isLValueReferenceType()) {
320 if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) {
321 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue)
322 << CT_Dynamic << OrigSrcType << OrigDestType << OpRange;
324 SrcPointee = SrcType;
326 SrcPointee = SrcType;
329 const RecordType *SrcRecord = SrcPointee->getAs<RecordType>();
331 if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee,
332 PDiag(diag::err_bad_dynamic_cast_incomplete)
333 << SrcExpr->getSourceRange()))
336 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
337 << SrcPointee.getUnqualifiedType() << SrcExpr->getSourceRange();
341 assert((DestPointer || DestReference) &&
342 "Bad destination non-ptr/ref slipped through.");
343 assert((DestRecord || DestPointee->isVoidType()) &&
344 "Bad destination pointee slipped through.");
345 assert(SrcRecord && "Bad source pointee slipped through.");
347 // C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness.
348 if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) {
349 Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_const_away)
350 << CT_Dynamic << OrigSrcType << OrigDestType << OpRange;
354 // C++ 5.2.7p3: If the type of v is the same as the required result type,
356 if (DestRecord == SrcRecord) {
361 // Upcasts are resolved statically.
362 if (DestRecord && Self.IsDerivedFrom(SrcPointee, DestPointee)) {
363 Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee,
364 OpRange.getBegin(), OpRange);
365 Kind = CastExpr::CK_DerivedToBase;
366 // Diagnostic already emitted on error.
370 // C++ 5.2.7p6: Otherwise, v shall be [polymorphic].
371 const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition(Self.Context);
372 assert(SrcDecl && "Definition missing");
373 if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) {
374 Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic)
375 << SrcPointee.getUnqualifiedType() << SrcExpr->getSourceRange();
378 // Done. Everything else is run-time checks.
379 Kind = CastExpr::CK_Dynamic;
382 /// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid.
383 /// Refer to C++ 5.2.11 for details. const_cast is typically used in code
385 /// const char *str = "literal";
386 /// legacy_function(const_cast\<char*\>(str));
388 CheckConstCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
389 const SourceRange &OpRange, const SourceRange &DestRange) {
390 if (!DestType->isLValueReferenceType())
391 Self.DefaultFunctionArrayConversion(SrcExpr);
393 unsigned msg = diag::err_bad_cxx_cast_generic;
394 if (TryConstCast(Self, SrcExpr, DestType, /*CStyle*/false, msg) != TC_Success
396 Self.Diag(OpRange.getBegin(), msg) << CT_Const
397 << SrcExpr->getType() << DestType << OpRange;
400 /// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is
402 /// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code
404 /// char *bytes = reinterpret_cast\<char*\>(int_ptr);
406 CheckReinterpretCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
407 const SourceRange &OpRange, const SourceRange &DestRange,
408 CastExpr::CastKind &Kind) {
409 if (!DestType->isLValueReferenceType())
410 Self.DefaultFunctionArrayConversion(SrcExpr);
412 unsigned msg = diag::err_bad_cxx_cast_generic;
413 if (TryReinterpretCast(Self, SrcExpr, DestType, /*CStyle*/false, OpRange,
415 != TC_Success && msg != 0)
416 Self.Diag(OpRange.getBegin(), msg) << CT_Reinterpret
417 << SrcExpr->getType() << DestType << OpRange;
421 /// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid.
422 /// Refer to C++ 5.2.9 for details. Static casts are mostly used for making
423 /// implicit conversions explicit and getting rid of data loss warnings.
425 CheckStaticCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
426 const SourceRange &OpRange, CastExpr::CastKind &Kind,
427 CXXMethodDecl *&ConversionDecl) {
428 // This test is outside everything else because it's the only case where
429 // a non-lvalue-reference target type does not lead to decay.
430 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
431 if (DestType->isVoidType()) {
432 Kind = CastExpr::CK_ToVoid;
436 if (!DestType->isLValueReferenceType() && !DestType->isRecordType())
437 Self.DefaultFunctionArrayConversion(SrcExpr);
439 unsigned msg = diag::err_bad_cxx_cast_generic;
440 if (TryStaticCast(Self, SrcExpr, DestType, /*CStyle*/false, OpRange, msg,
441 Kind, ConversionDecl)
442 != TC_Success && msg != 0)
443 Self.Diag(OpRange.getBegin(), msg) << CT_Static
444 << SrcExpr->getType() << DestType << OpRange;
447 /// TryStaticCast - Check if a static cast can be performed, and do so if
448 /// possible. If @p CStyle, ignore access restrictions on hierarchy casting
449 /// and casting away constness.
450 static TryCastResult TryStaticCast(Sema &Self, Expr *&SrcExpr,
451 QualType DestType, bool CStyle,
452 const SourceRange &OpRange, unsigned &msg,
453 CastExpr::CastKind &Kind,
454 CXXMethodDecl *&ConversionDecl) {
455 // The order the tests is not entirely arbitrary. There is one conversion
456 // that can be handled in two different ways. Given:
458 // struct B : public A {
462 // the cast static_cast<const B&>(a) could be seen as either a static
463 // reference downcast, or an explicit invocation of the user-defined
464 // conversion using B's conversion constructor.
465 // DR 427 specifies that the downcast is to be applied here.
467 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
468 // Done outside this function.
472 // C++ 5.2.9p5, reference downcast.
473 // See the function for details.
474 // DR 427 specifies that this is to be applied before paragraph 2.
475 tcr = TryStaticReferenceDowncast(Self, SrcExpr, DestType, CStyle, OpRange,
477 if (tcr != TC_NotApplicable)
480 // N2844 5.2.9p3: An lvalue of type "cv1 T1" can be cast to type "rvalue
481 // reference to cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1".
482 tcr = TryLValueToRValueCast(Self, SrcExpr, DestType, msg);
483 if (tcr != TC_NotApplicable) {
484 Kind = CastExpr::CK_NoOp;
488 // C++ 5.2.9p2: An expression e can be explicitly converted to a type T
489 // [...] if the declaration "T t(e);" is well-formed, [...].
490 tcr = TryStaticImplicitCast(Self, SrcExpr, DestType, CStyle, OpRange, msg,
491 Kind, ConversionDecl);
492 if (tcr != TC_NotApplicable)
495 // C++ 5.2.9p6: May apply the reverse of any standard conversion, except
496 // lvalue-to-rvalue, array-to-pointer, function-to-pointer, and boolean
497 // conversions, subject to further restrictions.
498 // Also, C++ 5.2.9p1 forbids casting away constness, which makes reversal
499 // of qualification conversions impossible.
500 // In the CStyle case, the earlier attempt to const_cast should have taken
501 // care of reverse qualification conversions.
503 QualType OrigSrcType = SrcExpr->getType();
505 QualType SrcType = Self.Context.getCanonicalType(SrcExpr->getType());
507 // Reverse integral promotion/conversion. All such conversions are themselves
508 // again integral promotions or conversions and are thus already handled by
509 // p2 (TryDirectInitialization above).
510 // (Note: any data loss warnings should be suppressed.)
511 // The exception is the reverse of enum->integer, i.e. integer->enum (and
512 // enum->enum). See also C++ 5.2.9p7.
513 // The same goes for reverse floating point promotion/conversion and
514 // floating-integral conversions. Again, only floating->enum is relevant.
515 if (DestType->isEnumeralType()) {
516 if (SrcType->isComplexType() || SrcType->isVectorType()) {
517 // Fall through - these cannot be converted.
518 } else if (SrcType->isArithmeticType() || SrcType->isEnumeralType()) {
519 Kind = CastExpr::CK_IntegralCast;
524 // Reverse pointer upcast. C++ 4.10p3 specifies pointer upcast.
525 // C++ 5.2.9p8 additionally disallows a cast path through virtual inheritance.
526 tcr = TryStaticPointerDowncast(Self, SrcType, DestType, CStyle, OpRange, msg,
528 if (tcr != TC_NotApplicable)
531 // Reverse member pointer conversion. C++ 4.11 specifies member pointer
532 // conversion. C++ 5.2.9p9 has additional information.
533 // DR54's access restrictions apply here also.
534 tcr = TryStaticMemberPointerUpcast(Self, SrcType, DestType, CStyle,
536 if (tcr != TC_NotApplicable)
539 // Reverse pointer conversion to void*. C++ 4.10.p2 specifies conversion to
540 // void*. C++ 5.2.9p10 specifies additional restrictions, which really is
541 // just the usual constness stuff.
542 if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
543 QualType SrcPointee = SrcPointer->getPointeeType();
544 if (SrcPointee->isVoidType()) {
545 if (const PointerType *DestPointer = DestType->getAs<PointerType>()) {
546 QualType DestPointee = DestPointer->getPointeeType();
547 if (DestPointee->isIncompleteOrObjectType()) {
548 // This is definitely the intended conversion, but it might fail due
549 // to a const violation.
550 if (!CStyle && !DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) {
551 msg = diag::err_bad_cxx_cast_const_away;
554 Kind = CastExpr::CK_BitCast;
558 else if (CStyle && DestType->isObjCObjectPointerType()) {
559 // allow c-style cast of objective-c pointers as they are pervasive.
560 Kind = CastExpr::CK_AnyPointerToObjCPointerCast;
563 else if (CStyle && DestType->isBlockPointerType()) {
564 // allow c-style cast of void * to block pointers.
565 Kind = CastExpr::CK_AnyPointerToBlockPointerCast;
571 // We tried everything. Everything! Nothing works! :-(
572 return TC_NotApplicable;
575 /// Tests whether a conversion according to N2844 is valid.
577 TryLValueToRValueCast(Sema &Self, Expr *SrcExpr, QualType DestType,
579 // N2844 5.2.9p3: An lvalue of type "cv1 T1" can be cast to type "rvalue
580 // reference to cv2 T2" if "cv2 T2" is reference-compatible with "cv1 T1".
581 const RValueReferenceType *R = DestType->getAs<RValueReferenceType>();
583 return TC_NotApplicable;
585 if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid)
586 return TC_NotApplicable;
588 // Because we try the reference downcast before this function, from now on
589 // this is the only cast possibility, so we issue an error if we fail now.
590 // FIXME: Should allow casting away constness if CStyle.
592 if (Self.CompareReferenceRelationship(SrcExpr->getLocStart(),
593 SrcExpr->getType(), R->getPointeeType(),
595 Sema::Ref_Compatible_With_Added_Qualification) {
596 msg = diag::err_bad_lvalue_to_rvalue_cast;
600 // FIXME: Similar to CheckReferenceInit, we actually need more AST annotation
605 /// Tests whether a conversion according to C++ 5.2.9p5 is valid.
607 TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr, QualType DestType,
608 bool CStyle, const SourceRange &OpRange,
609 unsigned &msg, CastExpr::CastKind &Kind) {
610 // C++ 5.2.9p5: An lvalue of type "cv1 B", where B is a class type, can be
611 // cast to type "reference to cv2 D", where D is a class derived from B,
612 // if a valid standard conversion from "pointer to D" to "pointer to B"
613 // exists, cv2 >= cv1, and B is not a virtual base class of D.
614 // In addition, DR54 clarifies that the base must be accessible in the
615 // current context. Although the wording of DR54 only applies to the pointer
616 // variant of this rule, the intent is clearly for it to apply to the this
617 // conversion as well.
619 const ReferenceType *DestReference = DestType->getAs<ReferenceType>();
620 if (!DestReference) {
621 return TC_NotApplicable;
623 bool RValueRef = DestReference->isRValueReferenceType();
624 if (!RValueRef && SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) {
625 // We know the left side is an lvalue reference, so we can suggest a reason.
626 msg = diag::err_bad_cxx_cast_rvalue;
627 return TC_NotApplicable;
630 QualType DestPointee = DestReference->getPointeeType();
632 return TryStaticDowncast(Self,
633 Self.Context.getCanonicalType(SrcExpr->getType()),
634 Self.Context.getCanonicalType(DestPointee), CStyle,
635 OpRange, SrcExpr->getType(), DestType, msg, Kind);
638 /// Tests whether a conversion according to C++ 5.2.9p8 is valid.
640 TryStaticPointerDowncast(Sema &Self, QualType SrcType, QualType DestType,
641 bool CStyle, const SourceRange &OpRange,
642 unsigned &msg, CastExpr::CastKind &Kind) {
643 // C++ 5.2.9p8: An rvalue of type "pointer to cv1 B", where B is a class
644 // type, can be converted to an rvalue of type "pointer to cv2 D", where D
645 // is a class derived from B, if a valid standard conversion from "pointer
646 // to D" to "pointer to B" exists, cv2 >= cv1, and B is not a virtual base
648 // In addition, DR54 clarifies that the base must be accessible in the
651 const PointerType *DestPointer = DestType->getAs<PointerType>();
653 return TC_NotApplicable;
656 const PointerType *SrcPointer = SrcType->getAs<PointerType>();
658 msg = diag::err_bad_static_cast_pointer_nonpointer;
659 return TC_NotApplicable;
662 return TryStaticDowncast(Self,
663 Self.Context.getCanonicalType(SrcPointer->getPointeeType()),
664 Self.Context.getCanonicalType(DestPointer->getPointeeType()),
665 CStyle, OpRange, SrcType, DestType, msg, Kind);
668 /// TryStaticDowncast - Common functionality of TryStaticReferenceDowncast and
669 /// TryStaticPointerDowncast. Tests whether a static downcast from SrcType to
670 /// DestType is possible and allowed.
672 TryStaticDowncast(Sema &Self, CanQualType SrcType, CanQualType DestType,
673 bool CStyle, const SourceRange &OpRange, QualType OrigSrcType,
674 QualType OrigDestType, unsigned &msg,
675 CastExpr::CastKind &Kind) {
676 // We can only work with complete types. But don't complain if it doesn't work
677 if (Self.RequireCompleteType(OpRange.getBegin(), SrcType, PDiag(0)) ||
678 Self.RequireCompleteType(OpRange.getBegin(), DestType, PDiag(0)))
679 return TC_NotApplicable;
681 // Downcast can only happen in class hierarchies, so we need classes.
682 if (!DestType->getAs<RecordType>() || !SrcType->getAs<RecordType>()) {
683 return TC_NotApplicable;
686 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/!CStyle,
687 /*DetectVirtual=*/true);
688 if (!Self.IsDerivedFrom(DestType, SrcType, Paths)) {
689 return TC_NotApplicable;
692 // Target type does derive from source type. Now we're serious. If an error
693 // appears now, it's not ignored.
694 // This may not be entirely in line with the standard. Take for example:
696 // struct B : virtual A {
702 // (void)static_cast<const B&>(*((A*)0));
704 // As far as the standard is concerned, p5 does not apply (A is virtual), so
705 // p2 should be used instead - "const B& t(*((A*)0));" is perfectly valid.
706 // However, both GCC and Comeau reject this example, and accepting it would
707 // mean more complex code if we're to preserve the nice error message.
708 // FIXME: Being 100% compliant here would be nice to have.
710 // Must preserve cv, as always, unless we're in C-style mode.
711 if (!CStyle && !DestType.isAtLeastAsQualifiedAs(SrcType)) {
712 msg = diag::err_bad_cxx_cast_const_away;
716 if (Paths.isAmbiguous(SrcType.getUnqualifiedType())) {
717 // This code is analoguous to that in CheckDerivedToBaseConversion, except
718 // that it builds the paths in reverse order.
719 // To sum up: record all paths to the base and build a nice string from
720 // them. Use it to spice up the error message.
721 if (!Paths.isRecordingPaths()) {
723 Paths.setRecordingPaths(true);
724 Self.IsDerivedFrom(DestType, SrcType, Paths);
726 std::string PathDisplayStr;
727 std::set<unsigned> DisplayedPaths;
728 for (CXXBasePaths::paths_iterator PI = Paths.begin(), PE = Paths.end();
730 if (DisplayedPaths.insert(PI->back().SubobjectNumber).second) {
731 // We haven't displayed a path to this particular base
732 // class subobject yet.
733 PathDisplayStr += "\n ";
734 for (CXXBasePath::const_reverse_iterator EI = PI->rbegin(),
737 PathDisplayStr += EI->Base->getType().getAsString() + " -> ";
738 PathDisplayStr += QualType(DestType).getAsString();
742 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_base_to_derived_cast)
743 << QualType(SrcType).getUnqualifiedType()
744 << QualType(DestType).getUnqualifiedType()
745 << PathDisplayStr << OpRange;
750 if (Paths.getDetectedVirtual() != 0) {
751 QualType VirtualBase(Paths.getDetectedVirtual(), 0);
752 Self.Diag(OpRange.getBegin(), diag::err_static_downcast_via_virtual)
753 << OrigSrcType << OrigDestType << VirtualBase << OpRange;
758 if (!CStyle && Self.CheckBaseClassAccess(DestType, SrcType,
759 diag::err_downcast_from_inaccessible_base, Paths,
760 OpRange.getBegin(), DeclarationName())) {
765 Kind = CastExpr::CK_BaseToDerived;
769 /// TryStaticMemberPointerUpcast - Tests whether a conversion according to
770 /// C++ 5.2.9p9 is valid:
772 /// An rvalue of type "pointer to member of D of type cv1 T" can be
773 /// converted to an rvalue of type "pointer to member of B of type cv2 T",
774 /// where B is a base class of D [...].
777 TryStaticMemberPointerUpcast(Sema &Self, QualType SrcType, QualType DestType,
778 bool CStyle, const SourceRange &OpRange,
779 unsigned &msg, CastExpr::CastKind &Kind) {
780 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>();
782 return TC_NotApplicable;
783 const MemberPointerType *SrcMemPtr = SrcType->getAs<MemberPointerType>();
785 msg = diag::err_bad_static_cast_member_pointer_nonmp;
786 return TC_NotApplicable;
790 if (!Self.Context.hasSameUnqualifiedType(SrcMemPtr->getPointeeType(),
791 DestMemPtr->getPointeeType()))
792 return TC_NotApplicable;
795 QualType SrcClass(SrcMemPtr->getClass(), 0);
796 QualType DestClass(DestMemPtr->getClass(), 0);
797 CXXBasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/!CStyle,
798 /*DetectVirtual=*/true);
799 if (!Self.IsDerivedFrom(SrcClass, DestClass, Paths)) {
800 return TC_NotApplicable;
803 // B is a base of D. But is it an allowed base? If not, it's a hard error.
804 if (Paths.isAmbiguous(DestClass)) {
806 Paths.setRecordingPaths(true);
807 bool StillOkay = Self.IsDerivedFrom(SrcClass, DestClass, Paths);
809 StillOkay = StillOkay;
810 std::string PathDisplayStr = Self.getAmbiguousPathsDisplayString(Paths);
811 Self.Diag(OpRange.getBegin(), diag::err_ambiguous_memptr_conv)
812 << 1 << SrcClass << DestClass << PathDisplayStr << OpRange;
817 if (const RecordType *VBase = Paths.getDetectedVirtual()) {
818 Self.Diag(OpRange.getBegin(), diag::err_memptr_conv_via_virtual)
819 << SrcClass << DestClass << QualType(VBase, 0) << OpRange;
824 if (!CStyle && Self.CheckBaseClassAccess(DestType, SrcType,
825 diag::err_downcast_from_inaccessible_base, Paths,
826 OpRange.getBegin(), DeclarationName())) {
831 Kind = CastExpr::CK_DerivedToBaseMemberPointer;
835 /// TryStaticImplicitCast - Tests whether a conversion according to C++ 5.2.9p2
838 /// An expression e can be explicitly converted to a type T using a
839 /// @c static_cast if the declaration "T t(e);" is well-formed [...].
841 TryStaticImplicitCast(Sema &Self, Expr *&SrcExpr, QualType DestType,
842 bool CStyle, const SourceRange &OpRange, unsigned &msg,
843 CastExpr::CastKind &Kind,
844 CXXMethodDecl *&ConversionDecl) {
845 if (DestType->isRecordType()) {
846 if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
847 diag::err_bad_dynamic_cast_incomplete)) {
853 if (DestType->isReferenceType()) {
854 // All reference bindings insert implicit casts above that do the actual
856 Kind = CastExpr::CK_NoOp;
858 // At this point of CheckStaticCast, if the destination is a reference,
859 // this has to work. There is no other way that works.
860 // On the other hand, if we're checking a C-style cast, we've still got
861 // the reinterpret_cast way. So in C-style mode, we first try the call
862 // with an ICS to suppress errors.
864 ImplicitConversionSequence ICS;
865 if(Self.CheckReferenceInit(SrcExpr, DestType, OpRange.getBegin(),
866 /*SuppressUserConversions=*/false,
867 /*AllowExplicit=*/false, /*ForceRValue=*/false,
869 return TC_NotApplicable;
871 // Now we're committed either way.
872 if(!Self.CheckReferenceInit(SrcExpr, DestType, OpRange.getBegin(),
873 /*SuppressUserConversions=*/false,
874 /*AllowExplicit=*/false,
875 /*ForceRValue=*/false, 0,
876 /*IgnoreBaseAccess=*/CStyle))
879 // We already got an error message.
884 if (DestType->isRecordType()) {
885 if (CXXConstructorDecl *Constructor
886 = Self.TryInitializationByConstructor(DestType, &SrcExpr, 1,
888 InitializationKind::CreateDirect(OpRange.getBegin(),
890 OpRange.getEnd()))) {
891 ConversionDecl = Constructor;
892 Kind = CastExpr::CK_ConstructorConversion;
896 return TC_NotApplicable;
899 // FIXME: To get a proper error from invalid conversions here, we need to
900 // reimplement more of this.
901 // FIXME: This does not actually perform the conversion, and thus does not
902 // check for ambiguity or access.
903 ImplicitConversionSequence ICS =
904 Self.TryImplicitConversion(SrcExpr, DestType,
905 /*SuppressUserConversions=*/false,
906 /*AllowExplicit=*/true,
907 /*ForceRValue=*/false,
908 /*InOverloadResolution=*/false,
909 /*one of user provided casts*/true);
912 return TC_NotApplicable;
914 // The conversion is possible, so commit to it.
915 Kind = CastExpr::CK_NoOp;
917 return Self.PerformImplicitConversion(SrcExpr, DestType, ICS, Sema::AA_Casting,
918 /*IgnoreBaseAccess*/CStyle) ?
919 TC_Failed : TC_Success;
922 /// TryConstCast - See if a const_cast from source to destination is allowed,
923 /// and perform it if it is.
924 static TryCastResult TryConstCast(Sema &Self, Expr *SrcExpr, QualType DestType,
925 bool CStyle, unsigned &msg) {
926 DestType = Self.Context.getCanonicalType(DestType);
927 QualType SrcType = SrcExpr->getType();
928 if (const LValueReferenceType *DestTypeTmp =
929 DestType->getAs<LValueReferenceType>()) {
930 if (SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) {
931 // Cannot const_cast non-lvalue to lvalue reference type. But if this
932 // is C-style, static_cast might find a way, so we simply suggest a
933 // message and tell the parent to keep searching.
934 msg = diag::err_bad_cxx_cast_rvalue;
935 return TC_NotApplicable;
938 // C++ 5.2.11p4: An lvalue of type T1 can be [cast] to an lvalue of type T2
939 // [...] if a pointer to T1 can be [cast] to the type pointer to T2.
940 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
941 SrcType = Self.Context.getPointerType(SrcType);
944 // C++ 5.2.11p5: For a const_cast involving pointers to data members [...]
945 // the rules for const_cast are the same as those used for pointers.
947 if (!DestType->isPointerType() && !DestType->isMemberPointerType()) {
948 // Cannot cast to non-pointer, non-reference type. Note that, if DestType
949 // was a reference type, we converted it to a pointer above.
950 // The status of rvalue references isn't entirely clear, but it looks like
951 // conversion to them is simply invalid.
952 // C++ 5.2.11p3: For two pointer types [...]
954 msg = diag::err_bad_const_cast_dest;
955 return TC_NotApplicable;
957 if (DestType->isFunctionPointerType() ||
958 DestType->isMemberFunctionPointerType()) {
959 // Cannot cast direct function pointers.
960 // C++ 5.2.11p2: [...] where T is any object type or the void type [...]
961 // T is the ultimate pointee of source and target type.
963 msg = diag::err_bad_const_cast_dest;
964 return TC_NotApplicable;
966 SrcType = Self.Context.getCanonicalType(SrcType);
968 // Unwrap the pointers. Ignore qualifiers. Terminate early if the types are
970 // FIXME: const_cast should probably not be able to convert between pointers
971 // to different address spaces.
972 // C++ 5.2.11p3 describes the core semantics of const_cast. All cv specifiers
973 // in multi-level pointers may change, but the level count must be the same,
974 // as must be the final pointee type.
975 while (SrcType != DestType &&
976 Self.UnwrapSimilarPointerTypes(SrcType, DestType)) {
978 SrcType = Self.Context.getUnqualifiedArrayType(SrcType, Quals);
979 DestType = Self.Context.getUnqualifiedArrayType(DestType, Quals);
982 // Since we're dealing in canonical types, the remainder must be the same.
983 if (SrcType != DestType)
984 return TC_NotApplicable;
989 static TryCastResult TryReinterpretCast(Sema &Self, Expr *SrcExpr,
990 QualType DestType, bool CStyle,
991 const SourceRange &OpRange,
993 CastExpr::CastKind &Kind) {
994 DestType = Self.Context.getCanonicalType(DestType);
995 QualType SrcType = SrcExpr->getType();
996 if (const ReferenceType *DestTypeTmp = DestType->getAs<ReferenceType>()) {
997 bool LValue = DestTypeTmp->isLValueReferenceType();
998 if (LValue && SrcExpr->isLvalue(Self.Context) != Expr::LV_Valid) {
999 // Cannot cast non-lvalue to reference type. See the similar comment in
1001 msg = diag::err_bad_cxx_cast_rvalue;
1002 return TC_NotApplicable;
1005 // C++ 5.2.10p10: [...] a reference cast reinterpret_cast<T&>(x) has the
1006 // same effect as the conversion *reinterpret_cast<T*>(&x) with the
1007 // built-in & and * operators.
1008 // This code does this transformation for the checked types.
1009 DestType = Self.Context.getPointerType(DestTypeTmp->getPointeeType());
1010 SrcType = Self.Context.getPointerType(SrcType);
1013 // Canonicalize source for comparison.
1014 SrcType = Self.Context.getCanonicalType(SrcType);
1016 const MemberPointerType *DestMemPtr = DestType->getAs<MemberPointerType>(),
1017 *SrcMemPtr = SrcType->getAs<MemberPointerType>();
1018 if (DestMemPtr && SrcMemPtr) {
1019 // C++ 5.2.10p9: An rvalue of type "pointer to member of X of type T1"
1020 // can be explicitly converted to an rvalue of type "pointer to member
1021 // of Y of type T2" if T1 and T2 are both function types or both object
1023 if (DestMemPtr->getPointeeType()->isFunctionType() !=
1024 SrcMemPtr->getPointeeType()->isFunctionType())
1025 return TC_NotApplicable;
1027 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away
1029 // A reinterpret_cast followed by a const_cast can, though, so in C-style,
1031 if (!CStyle && CastsAwayConstness(Self, SrcType, DestType)) {
1032 msg = diag::err_bad_cxx_cast_const_away;
1036 // A valid member pointer cast.
1037 Kind = CastExpr::CK_BitCast;
1041 // See below for the enumeral issue.
1042 if (SrcType->isNullPtrType() && DestType->isIntegralType() &&
1043 !DestType->isEnumeralType()) {
1044 // C++0x 5.2.10p4: A pointer can be explicitly converted to any integral
1045 // type large enough to hold it. A value of std::nullptr_t can be
1046 // converted to an integral type; the conversion has the same meaning
1047 // and validity as a conversion of (void*)0 to the integral type.
1048 if (Self.Context.getTypeSize(SrcType) >
1049 Self.Context.getTypeSize(DestType)) {
1050 msg = diag::err_bad_reinterpret_cast_small_int;
1053 Kind = CastExpr::CK_PointerToIntegral;
1057 bool destIsVector = DestType->isVectorType();
1058 bool srcIsVector = SrcType->isVectorType();
1059 if (srcIsVector || destIsVector) {
1060 bool srcIsScalar = SrcType->isIntegralType() && !SrcType->isEnumeralType();
1062 DestType->isIntegralType() && !DestType->isEnumeralType();
1064 // Check if this is a cast between a vector and something else.
1065 if (!(srcIsScalar && destIsVector) && !(srcIsVector && destIsScalar) &&
1066 !(srcIsVector && destIsVector))
1067 return TC_NotApplicable;
1069 // If both types have the same size, we can successfully cast.
1070 if (Self.Context.getTypeSize(SrcType)
1071 == Self.Context.getTypeSize(DestType)) {
1072 Kind = CastExpr::CK_BitCast;
1077 msg = diag::err_bad_cxx_cast_vector_to_scalar_different_size;
1078 else if (srcIsScalar)
1079 msg = diag::err_bad_cxx_cast_scalar_to_vector_different_size;
1081 msg = diag::err_bad_cxx_cast_vector_to_vector_different_size;
1087 CStyle? DestType->isAnyPointerType() : DestType->isPointerType();
1089 CStyle ? SrcType->isAnyPointerType() : SrcType->isPointerType();
1090 if (!destIsPtr && !srcIsPtr) {
1091 // Except for std::nullptr_t->integer and lvalue->reference, which are
1092 // handled above, at least one of the two arguments must be a pointer.
1093 return TC_NotApplicable;
1096 if (SrcType == DestType) {
1097 // C++ 5.2.10p2 has a note that mentions that, subject to all other
1098 // restrictions, a cast to the same type is allowed. The intent is not
1099 // entirely clear here, since all other paragraphs explicitly forbid casts
1100 // to the same type. However, the behavior of compilers is pretty consistent
1101 // on this point: allow same-type conversion if the involved types are
1102 // pointers, disallow otherwise.
1103 Kind = CastExpr::CK_NoOp;
1107 // Note: Clang treats enumeration types as integral types. If this is ever
1108 // changed for C++, the additional check here will be redundant.
1109 if (DestType->isIntegralType() && !DestType->isEnumeralType()) {
1110 assert(srcIsPtr && "One type must be a pointer");
1111 // C++ 5.2.10p4: A pointer can be explicitly converted to any integral
1112 // type large enough to hold it.
1113 if (Self.Context.getTypeSize(SrcType) >
1114 Self.Context.getTypeSize(DestType)) {
1115 msg = diag::err_bad_reinterpret_cast_small_int;
1118 Kind = CastExpr::CK_PointerToIntegral;
1122 if (SrcType->isIntegralType() || SrcType->isEnumeralType()) {
1123 assert(destIsPtr && "One type must be a pointer");
1124 // C++ 5.2.10p5: A value of integral or enumeration type can be explicitly
1125 // converted to a pointer.
1126 Kind = CastExpr::CK_IntegralToPointer;
1130 if (!destIsPtr || !srcIsPtr) {
1131 // With the valid non-pointer conversions out of the way, we can be even
1133 return TC_NotApplicable;
1136 // C++ 5.2.10p2: The reinterpret_cast operator shall not cast away constness.
1137 // The C-style cast operator can.
1138 if (!CStyle && CastsAwayConstness(Self, SrcType, DestType)) {
1139 msg = diag::err_bad_cxx_cast_const_away;
1142 if (CStyle && DestType->isObjCObjectPointerType()) {
1143 Kind = CastExpr::CK_AnyPointerToObjCPointerCast;
1147 // Not casting away constness, so the only remaining check is for compatible
1148 // pointer categories.
1149 Kind = CastExpr::CK_BitCast;
1151 if (SrcType->isFunctionPointerType()) {
1152 if (DestType->isFunctionPointerType()) {
1153 // C++ 5.2.10p6: A pointer to a function can be explicitly converted to
1154 // a pointer to a function of a different type.
1158 // C++0x 5.2.10p8: Converting a pointer to a function into a pointer to
1159 // an object type or vice versa is conditionally-supported.
1160 // Compilers support it in C++03 too, though, because it's necessary for
1161 // casting the return value of dlsym() and GetProcAddress().
1162 // FIXME: Conditionally-supported behavior should be configurable in the
1163 // TargetInfo or similar.
1164 if (!Self.getLangOptions().CPlusPlus0x)
1165 Self.Diag(OpRange.getBegin(), diag::ext_cast_fn_obj) << OpRange;
1169 if (DestType->isFunctionPointerType()) {
1171 if (!Self.getLangOptions().CPlusPlus0x)
1172 Self.Diag(OpRange.getBegin(), diag::ext_cast_fn_obj) << OpRange;
1176 // C++ 5.2.10p7: A pointer to an object can be explicitly converted to
1177 // a pointer to an object of different type.
1178 // Void pointers are not specified, but supported by every compiler out there.
1179 // So we finish by allowing everything that remains - it's got to be two
1184 bool Sema::CXXCheckCStyleCast(SourceRange R, QualType CastTy, Expr *&CastExpr,
1185 CastExpr::CastKind &Kind, bool FunctionalStyle,
1186 CXXMethodDecl *&ConversionDecl) {
1187 // This test is outside everything else because it's the only case where
1188 // a non-lvalue-reference target type does not lead to decay.
1189 // C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
1190 if (CastTy->isVoidType()) {
1191 Kind = CastExpr::CK_ToVoid;
1195 // If the type is dependent, we won't do any other semantic analysis now.
1196 if (CastTy->isDependentType() || CastExpr->isTypeDependent())
1199 if (!CastTy->isLValueReferenceType() && !CastTy->isRecordType())
1200 DefaultFunctionArrayConversion(CastExpr);
1202 // C++ [expr.cast]p5: The conversions performed by
1205 // - a static_cast followed by a const_cast,
1206 // - a reinterpret_cast, or
1207 // - a reinterpret_cast followed by a const_cast,
1208 // can be performed using the cast notation of explicit type conversion.
1209 // [...] If a conversion can be interpreted in more than one of the ways
1210 // listed above, the interpretation that appears first in the list is used,
1211 // even if a cast resulting from that interpretation is ill-formed.
1212 // In plain language, this means trying a const_cast ...
1213 unsigned msg = diag::err_bad_cxx_cast_generic;
1214 TryCastResult tcr = TryConstCast(*this, CastExpr, CastTy, /*CStyle*/true,
1216 if (tcr == TC_Success)
1217 Kind = CastExpr::CK_NoOp;
1219 if (tcr == TC_NotApplicable) {
1220 // ... or if that is not possible, a static_cast, ignoring const, ...
1221 tcr = TryStaticCast(*this, CastExpr, CastTy, /*CStyle*/true, R, msg,
1222 Kind, ConversionDecl);
1223 if (tcr == TC_NotApplicable) {
1224 // ... and finally a reinterpret_cast, ignoring const.
1225 tcr = TryReinterpretCast(*this, CastExpr, CastTy, /*CStyle*/true, R, msg,
1230 if (tcr != TC_Success && msg != 0)
1231 Diag(R.getBegin(), msg) << (FunctionalStyle ? CT_Functional : CT_CStyle)
1232 << CastExpr->getType() << CastTy << R;
1234 return tcr != TC_Success;