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SemaCast.cpp
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//===--- SemaCast.cpp - Semantic Analysis for Casts -----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for cast expressions, including
// 1) C-style casts like '(int) x'
// 2) C++ functional casts like 'int(x)'
// 3) C++ named casts like 'static_cast<int>(x)'
//
//===----------------------------------------------------------------------===//
#include "clang/Sema/SemaInternal.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/RecordLayout.h"
#include "clang/Basic/PartialDiagnostic.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/Initialization.h"
#include "llvm/ADT/SmallVector.h"
#include <set>
using namespace clang;
enum TryCastResult {
TC_NotApplicable, ///< The cast method is not applicable.
TC_Success, ///< The cast method is appropriate and successful.
TC_Failed ///< The cast method is appropriate, but failed. A
///< diagnostic has been emitted.
};
enum CastType {
CT_Const, ///< const_cast
CT_Static, ///< static_cast
CT_Reinterpret, ///< reinterpret_cast
CT_Dynamic, ///< dynamic_cast
CT_CStyle, ///< (Type)expr
CT_Functional ///< Type(expr)
};
namespace {
struct CastOperation {
CastOperation(Sema &S, QualType destType, ExprResult src)
: Self(S), SrcExpr(src), DestType(destType),
ResultType(destType.getNonLValueExprType(S.Context)),
ValueKind(Expr::getValueKindForType(destType)),
Kind(CK_Dependent), IsARCUnbridgedCast(false) {
if (const BuiltinType *placeholder =
src.get()->getType()->getAsPlaceholderType()) {
PlaceholderKind = placeholder->getKind();
} else {
PlaceholderKind = (BuiltinType::Kind) 0;
}
}
Sema &Self;
ExprResult SrcExpr;
QualType DestType;
QualType ResultType;
ExprValueKind ValueKind;
CastKind Kind;
BuiltinType::Kind PlaceholderKind;
CXXCastPath BasePath;
bool IsARCUnbridgedCast;
SourceRange OpRange;
SourceRange DestRange;
// Top-level semantics-checking routines.
void CheckConstCast();
void CheckReinterpretCast();
void CheckStaticCast();
void CheckDynamicCast();
void CheckCXXCStyleCast(bool FunctionalCast, bool ListInitialization);
void CheckCStyleCast();
/// Complete an apparently-successful cast operation that yields
/// the given expression.
ExprResult complete(CastExpr *castExpr) {
// If this is an unbridged cast, wrap the result in an implicit
// cast that yields the unbridged-cast placeholder type.
if (IsARCUnbridgedCast) {
castExpr = ImplicitCastExpr::Create(Self.Context,
Self.Context.ARCUnbridgedCastTy,
CK_Dependent, castExpr, nullptr,
castExpr->getValueKind());
}
return castExpr;
}
// Internal convenience methods.
/// Try to handle the given placeholder expression kind. Return
/// true if the source expression has the appropriate placeholder
/// kind. A placeholder can only be claimed once.
bool claimPlaceholder(BuiltinType::Kind K) {
if (PlaceholderKind != K) return false;
PlaceholderKind = (BuiltinType::Kind) 0;
return true;
}
bool isPlaceholder() const {
return PlaceholderKind != 0;
}
bool isPlaceholder(BuiltinType::Kind K) const {
return PlaceholderKind == K;
}
void checkCastAlign() {
Self.CheckCastAlign(SrcExpr.get(), DestType, OpRange);
}
void checkObjCConversion(Sema::CheckedConversionKind CCK) {
assert(Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers());
Expr *src = SrcExpr.get();
if (Self.CheckObjCConversion(OpRange, DestType, src, CCK) ==
Sema::ACR_unbridged)
IsARCUnbridgedCast = true;
SrcExpr = src;
}
/// Check for and handle non-overload placeholder expressions.
void checkNonOverloadPlaceholders() {
if (!isPlaceholder() || isPlaceholder(BuiltinType::Overload))
return;
SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
if (SrcExpr.isInvalid())
return;
PlaceholderKind = (BuiltinType::Kind) 0;
}
};
}
static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr,
QualType DestType);
// The Try functions attempt a specific way of casting. If they succeed, they
// return TC_Success. If their way of casting is not appropriate for the given
// arguments, they return TC_NotApplicable and *may* set diag to a diagnostic
// to emit if no other way succeeds. If their way of casting is appropriate but
// fails, they return TC_Failed and *must* set diag; they can set it to 0 if
// they emit a specialized diagnostic.
// All diagnostics returned by these functions must expect the same three
// arguments:
// %0: Cast Type (a value from the CastType enumeration)
// %1: Source Type
// %2: Destination Type
static TryCastResult TryLValueToRValueCast(Sema &Self, Expr *SrcExpr,
QualType DestType, bool CStyle,
CastKind &Kind,
CXXCastPath &BasePath,
unsigned &msg);
static TryCastResult TryStaticReferenceDowncast(Sema &Self, Expr *SrcExpr,
QualType DestType, bool CStyle,
SourceRange OpRange,
unsigned &msg,
CastKind &Kind,
CXXCastPath &BasePath);
static TryCastResult TryStaticPointerDowncast(Sema &Self, QualType SrcType,
QualType DestType, bool CStyle,
SourceRange OpRange,
unsigned &msg,
CastKind &Kind,
CXXCastPath &BasePath);
static TryCastResult TryStaticDowncast(Sema &Self, CanQualType SrcType,
CanQualType DestType, bool CStyle,
SourceRange OpRange,
QualType OrigSrcType,
QualType OrigDestType, unsigned &msg,
CastKind &Kind,
CXXCastPath &BasePath);
static TryCastResult TryStaticMemberPointerUpcast(Sema &Self, ExprResult &SrcExpr,
QualType SrcType,
QualType DestType,bool CStyle,
SourceRange OpRange,
unsigned &msg,
CastKind &Kind,
CXXCastPath &BasePath);
static TryCastResult TryStaticImplicitCast(Sema &Self, ExprResult &SrcExpr,
QualType DestType,
Sema::CheckedConversionKind CCK,
SourceRange OpRange,
unsigned &msg, CastKind &Kind,
bool ListInitialization);
static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
QualType DestType,
Sema::CheckedConversionKind CCK,
SourceRange OpRange,
unsigned &msg, CastKind &Kind,
CXXCastPath &BasePath,
bool ListInitialization);
static TryCastResult TryConstCast(Sema &Self, ExprResult &SrcExpr,
QualType DestType, bool CStyle,
unsigned &msg);
static TryCastResult TryReinterpretCast(Sema &Self, ExprResult &SrcExpr,
QualType DestType, bool CStyle,
SourceRange OpRange,
unsigned &msg,
CastKind &Kind);
/// ActOnCXXNamedCast - Parse {dynamic,static,reinterpret,const}_cast's.
ExprResult
Sema::ActOnCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
SourceLocation LAngleBracketLoc, Declarator &D,
SourceLocation RAngleBracketLoc,
SourceLocation LParenLoc, Expr *E,
SourceLocation RParenLoc) {
assert(!D.isInvalidType());
TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, E->getType());
if (D.isInvalidType())
return ExprError();
if (getLangOpts().CPlusPlus) {
// Check that there are no default arguments (C++ only).
CheckExtraCXXDefaultArguments(D);
}
return BuildCXXNamedCast(OpLoc, Kind, TInfo, E,
SourceRange(LAngleBracketLoc, RAngleBracketLoc),
SourceRange(LParenLoc, RParenLoc));
}
ExprResult
Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
TypeSourceInfo *DestTInfo, Expr *E,
SourceRange AngleBrackets, SourceRange Parens) {
ExprResult Ex = E;
QualType DestType = DestTInfo->getType();
// If the type is dependent, we won't do the semantic analysis now.
bool TypeDependent =
DestType->isDependentType() || Ex.get()->isTypeDependent();
CastOperation Op(*this, DestType, E);
Op.OpRange = SourceRange(OpLoc, Parens.getEnd());
Op.DestRange = AngleBrackets;
switch (Kind) {
default: llvm_unreachable("Unknown C++ cast!");
case tok::kw_const_cast:
if (!TypeDependent) {
Op.CheckConstCast();
if (Op.SrcExpr.isInvalid())
return ExprError();
DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
}
return Op.complete(CXXConstCastExpr::Create(Context, Op.ResultType,
Op.ValueKind, Op.SrcExpr.get(), DestTInfo,
OpLoc, Parens.getEnd(),
AngleBrackets));
case tok::kw_dynamic_cast: {
if (!TypeDependent) {
Op.CheckDynamicCast();
if (Op.SrcExpr.isInvalid())
return ExprError();
}
return Op.complete(CXXDynamicCastExpr::Create(Context, Op.ResultType,
Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
&Op.BasePath, DestTInfo,
OpLoc, Parens.getEnd(),
AngleBrackets));
}
case tok::kw_reinterpret_cast: {
if (!TypeDependent) {
Op.CheckReinterpretCast();
if (Op.SrcExpr.isInvalid())
return ExprError();
DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
}
return Op.complete(CXXReinterpretCastExpr::Create(Context, Op.ResultType,
Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
nullptr, DestTInfo, OpLoc,
Parens.getEnd(),
AngleBrackets));
}
case tok::kw_static_cast: {
if (!TypeDependent) {
Op.CheckStaticCast();
if (Op.SrcExpr.isInvalid())
return ExprError();
DiscardMisalignedMemberAddress(DestType.getTypePtr(), E);
}
return Op.complete(CXXStaticCastExpr::Create(Context, Op.ResultType,
Op.ValueKind, Op.Kind, Op.SrcExpr.get(),
&Op.BasePath, DestTInfo,
OpLoc, Parens.getEnd(),
AngleBrackets));
}
}
}
/// Try to diagnose a failed overloaded cast. Returns true if
/// diagnostics were emitted.
static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT,
SourceRange range, Expr *src,
QualType destType,
bool listInitialization) {
switch (CT) {
// These cast kinds don't consider user-defined conversions.
case CT_Const:
case CT_Reinterpret:
case CT_Dynamic:
return false;
// These do.
case CT_Static:
case CT_CStyle:
case CT_Functional:
break;
}
QualType srcType = src->getType();
if (!destType->isRecordType() && !srcType->isRecordType())
return false;
InitializedEntity entity = InitializedEntity::InitializeTemporary(destType);
InitializationKind initKind
= (CT == CT_CStyle)? InitializationKind::CreateCStyleCast(range.getBegin(),
range, listInitialization)
: (CT == CT_Functional)? InitializationKind::CreateFunctionalCast(range,
listInitialization)
: InitializationKind::CreateCast(/*type range?*/ range);
InitializationSequence sequence(S, entity, initKind, src);
assert(sequence.Failed() && "initialization succeeded on second try?");
switch (sequence.getFailureKind()) {
default: return false;
case InitializationSequence::FK_ConstructorOverloadFailed:
case InitializationSequence::FK_UserConversionOverloadFailed:
break;
}
OverloadCandidateSet &candidates = sequence.getFailedCandidateSet();
unsigned msg = 0;
OverloadCandidateDisplayKind howManyCandidates = OCD_AllCandidates;
switch (sequence.getFailedOverloadResult()) {
case OR_Success: llvm_unreachable("successful failed overload");
case OR_No_Viable_Function:
if (candidates.empty())
msg = diag::err_ovl_no_conversion_in_cast;
else
msg = diag::err_ovl_no_viable_conversion_in_cast;
howManyCandidates = OCD_AllCandidates;
break;
case OR_Ambiguous:
msg = diag::err_ovl_ambiguous_conversion_in_cast;
howManyCandidates = OCD_ViableCandidates;
break;
case OR_Deleted:
msg = diag::err_ovl_deleted_conversion_in_cast;
howManyCandidates = OCD_ViableCandidates;
break;
}
S.Diag(range.getBegin(), msg)
<< CT << srcType << destType
<< range << src->getSourceRange();
candidates.NoteCandidates(S, howManyCandidates, src);
return true;
}
/// Diagnose a failed cast.
static void diagnoseBadCast(Sema &S, unsigned msg, CastType castType,
SourceRange opRange, Expr *src, QualType destType,
bool listInitialization) {
if (msg == diag::err_bad_cxx_cast_generic &&
tryDiagnoseOverloadedCast(S, castType, opRange, src, destType,
listInitialization))
return;
S.Diag(opRange.getBegin(), msg) << castType
<< src->getType() << destType << opRange << src->getSourceRange();
// Detect if both types are (ptr to) class, and note any incompleteness.
int DifferentPtrness = 0;
QualType From = destType;
if (auto Ptr = From->getAs<PointerType>()) {
From = Ptr->getPointeeType();
DifferentPtrness++;
}
QualType To = src->getType();
if (auto Ptr = To->getAs<PointerType>()) {
To = Ptr->getPointeeType();
DifferentPtrness--;
}
if (!DifferentPtrness) {
auto RecFrom = From->getAs<RecordType>();
auto RecTo = To->getAs<RecordType>();
if (RecFrom && RecTo) {
auto DeclFrom = RecFrom->getAsCXXRecordDecl();
if (!DeclFrom->isCompleteDefinition())
S.Diag(DeclFrom->getLocation(), diag::note_type_incomplete)
<< DeclFrom->getDeclName();
auto DeclTo = RecTo->getAsCXXRecordDecl();
if (!DeclTo->isCompleteDefinition())
S.Diag(DeclTo->getLocation(), diag::note_type_incomplete)
<< DeclTo->getDeclName();
}
}
}
/// UnwrapDissimilarPointerTypes - Like Sema::UnwrapSimilarPointerTypes,
/// this removes one level of indirection from both types, provided that they're
/// the same kind of pointer (plain or to-member). Unlike the Sema function,
/// this one doesn't care if the two pointers-to-member don't point into the
/// same class. This is because CastsAwayConstness doesn't care.
/// And additionally, it handles C++ references. If both the types are
/// references, then their pointee types are returned,
/// else if only one of them is reference, it's pointee type is returned,
/// and the other type is returned as-is.
static bool UnwrapDissimilarPointerTypes(QualType& T1, QualType& T2) {
const PointerType *T1PtrType = T1->getAs<PointerType>(),
*T2PtrType = T2->getAs<PointerType>();
if (T1PtrType && T2PtrType) {
T1 = T1PtrType->getPointeeType();
T2 = T2PtrType->getPointeeType();
return true;
}
const ObjCObjectPointerType *T1ObjCPtrType =
T1->getAs<ObjCObjectPointerType>(),
*T2ObjCPtrType =
T2->getAs<ObjCObjectPointerType>();
if (T1ObjCPtrType) {
if (T2ObjCPtrType) {
T1 = T1ObjCPtrType->getPointeeType();
T2 = T2ObjCPtrType->getPointeeType();
return true;
}
else if (T2PtrType) {
T1 = T1ObjCPtrType->getPointeeType();
T2 = T2PtrType->getPointeeType();
return true;
}
}
else if (T2ObjCPtrType) {
if (T1PtrType) {
T2 = T2ObjCPtrType->getPointeeType();
T1 = T1PtrType->getPointeeType();
return true;
}
}
const MemberPointerType *T1MPType = T1->getAs<MemberPointerType>(),
*T2MPType = T2->getAs<MemberPointerType>();
if (T1MPType && T2MPType) {
T1 = T1MPType->getPointeeType();
T2 = T2MPType->getPointeeType();
return true;
}
const BlockPointerType *T1BPType = T1->getAs<BlockPointerType>(),
*T2BPType = T2->getAs<BlockPointerType>();
if (T1BPType && T2BPType) {
T1 = T1BPType->getPointeeType();
T2 = T2BPType->getPointeeType();
return true;
}
const LValueReferenceType *T1RefType = T1->getAs<LValueReferenceType>(),
*T2RefType = T2->getAs<LValueReferenceType>();
if (T1RefType && T2RefType) {
T1 = T1RefType->getPointeeType();
T2 = T2RefType->getPointeeType();
return true;
}
if (T1RefType) {
T1 = T1RefType->getPointeeType();
// T2 = T2;
return true;
}
if (T2RefType) {
// T1 = T1;
T2 = T2RefType->getPointeeType();
return true;
}
return false;
}
/// CastsAwayConstness - Check if the pointer conversion from SrcType to
/// DestType casts away constness as defined in C++ 5.2.11p8ff. This is used by
/// the cast checkers. Both arguments must denote pointer (possibly to member)
/// types.
///
/// \param CheckCVR Whether to check for const/volatile/restrict qualifiers.
///
/// \param CheckObjCLifetime Whether to check Objective-C lifetime qualifiers.
static bool
CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType,
bool CheckCVR, bool CheckObjCLifetime,
QualType *TheOffendingSrcType = nullptr,
QualType *TheOffendingDestType = nullptr,
Qualifiers *CastAwayQualifiers = nullptr) {
// If the only checking we care about is for Objective-C lifetime qualifiers,
// and we're not in ObjC mode, there's nothing to check.
if (!CheckCVR && CheckObjCLifetime &&
!Self.Context.getLangOpts().ObjC1)
return false;
// Casting away constness is defined in C++ 5.2.11p8 with reference to
// C++ 4.4. We piggyback on Sema::IsQualificationConversion for this, since
// the rules are non-trivial. So first we construct Tcv *...cv* as described
// in C++ 5.2.11p8.
assert((SrcType->isAnyPointerType() || SrcType->isMemberPointerType() ||
SrcType->isBlockPointerType() ||
DestType->isLValueReferenceType()) &&
"Source type is not pointer or pointer to member.");
assert((DestType->isAnyPointerType() || DestType->isMemberPointerType() ||
DestType->isBlockPointerType() ||
DestType->isLValueReferenceType()) &&
"Destination type is not pointer or pointer to member, or reference.");
QualType UnwrappedSrcType = Self.Context.getCanonicalType(SrcType),
UnwrappedDestType = Self.Context.getCanonicalType(DestType);
SmallVector<Qualifiers, 8> cv1, cv2;
// Find the qualifiers. We only care about cvr-qualifiers for the
// purpose of this check, because other qualifiers (address spaces,
// Objective-C GC, etc.) are part of the type's identity.
QualType PrevUnwrappedSrcType = UnwrappedSrcType;
QualType PrevUnwrappedDestType = UnwrappedDestType;
while (UnwrapDissimilarPointerTypes(UnwrappedSrcType, UnwrappedDestType)) {
// Determine the relevant qualifiers at this level.
Qualifiers SrcQuals, DestQuals;
Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals);
Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals);
// We do not meaningfully track object const-ness of Objective-C object
// types. Remove const from the source type if either the source or
// the destination is an Objective-C object type.
if (UnwrappedSrcType->isObjCObjectType() ||
UnwrappedDestType->isObjCObjectType())
SrcQuals.removeConst();
Qualifiers RetainedSrcQuals, RetainedDestQuals;
if (CheckCVR) {
RetainedSrcQuals.setCVRQualifiers(SrcQuals.getCVRQualifiers());
RetainedDestQuals.setCVRQualifiers(DestQuals.getCVRQualifiers());
if (RetainedSrcQuals != RetainedDestQuals && TheOffendingSrcType &&
TheOffendingDestType && CastAwayQualifiers) {
*TheOffendingSrcType = PrevUnwrappedSrcType;
*TheOffendingDestType = PrevUnwrappedDestType;
*CastAwayQualifiers = RetainedSrcQuals - RetainedDestQuals;
}
}
if (CheckObjCLifetime &&
!DestQuals.compatiblyIncludesObjCLifetime(SrcQuals))
return true;
cv1.push_back(RetainedSrcQuals);
cv2.push_back(RetainedDestQuals);
PrevUnwrappedSrcType = UnwrappedSrcType;
PrevUnwrappedDestType = UnwrappedDestType;
}
if (cv1.empty())
return false;
// Construct void pointers with those qualifiers (in reverse order of
// unwrapping, of course).
QualType SrcConstruct = Self.Context.VoidTy;
QualType DestConstruct = Self.Context.VoidTy;
ASTContext &Context = Self.Context;
for (SmallVectorImpl<Qualifiers>::reverse_iterator i1 = cv1.rbegin(),
i2 = cv2.rbegin();
i1 != cv1.rend(); ++i1, ++i2) {
SrcConstruct
= Context.getPointerType(Context.getQualifiedType(SrcConstruct, *i1));
DestConstruct
= Context.getPointerType(Context.getQualifiedType(DestConstruct, *i2));
}
// Test if they're compatible.
bool ObjCLifetimeConversion;
return SrcConstruct != DestConstruct &&
!Self.IsQualificationConversion(SrcConstruct, DestConstruct, false,
ObjCLifetimeConversion);
}
/// CheckDynamicCast - Check that a dynamic_cast\<DestType\>(SrcExpr) is valid.
/// Refer to C++ 5.2.7 for details. Dynamic casts are used mostly for runtime-
/// checked downcasts in class hierarchies.
void CastOperation::CheckDynamicCast() {
if (ValueKind == VK_RValue)
SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
else if (isPlaceholder())
SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
return;
QualType OrigSrcType = SrcExpr.get()->getType();
QualType DestType = Self.Context.getCanonicalType(this->DestType);
// C++ 5.2.7p1: T shall be a pointer or reference to a complete class type,
// or "pointer to cv void".
QualType DestPointee;
const PointerType *DestPointer = DestType->getAs<PointerType>();
const ReferenceType *DestReference = nullptr;
if (DestPointer) {
DestPointee = DestPointer->getPointeeType();
} else if ((DestReference = DestType->getAs<ReferenceType>())) {
DestPointee = DestReference->getPointeeType();
} else {
Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ref_or_ptr)
<< this->DestType << DestRange;
SrcExpr = ExprError();
return;
}
const RecordType *DestRecord = DestPointee->getAs<RecordType>();
if (DestPointee->isVoidType()) {
assert(DestPointer && "Reference to void is not possible");
} else if (DestRecord) {
if (Self.RequireCompleteType(OpRange.getBegin(), DestPointee,
diag::err_bad_dynamic_cast_incomplete,
DestRange)) {
SrcExpr = ExprError();
return;
}
} else {
Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
<< DestPointee.getUnqualifiedType() << DestRange;
SrcExpr = ExprError();
return;
}
// C++0x 5.2.7p2: If T is a pointer type, v shall be an rvalue of a pointer to
// complete class type, [...]. If T is an lvalue reference type, v shall be
// an lvalue of a complete class type, [...]. If T is an rvalue reference
// type, v shall be an expression having a complete class type, [...]
QualType SrcType = Self.Context.getCanonicalType(OrigSrcType);
QualType SrcPointee;
if (DestPointer) {
if (const PointerType *SrcPointer = SrcType->getAs<PointerType>()) {
SrcPointee = SrcPointer->getPointeeType();
} else {
Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_ptr)
<< OrigSrcType << SrcExpr.get()->getSourceRange();
SrcExpr = ExprError();
return;
}
} else if (DestReference->isLValueReferenceType()) {
if (!SrcExpr.get()->isLValue()) {
Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_rvalue)
<< CT_Dynamic << OrigSrcType << this->DestType << OpRange;
}
SrcPointee = SrcType;
} else {
// If we're dynamic_casting from a prvalue to an rvalue reference, we need
// to materialize the prvalue before we bind the reference to it.
if (SrcExpr.get()->isRValue())
SrcExpr = Self.CreateMaterializeTemporaryExpr(
SrcType, SrcExpr.get(), /*IsLValueReference*/ false);
SrcPointee = SrcType;
}
const RecordType *SrcRecord = SrcPointee->getAs<RecordType>();
if (SrcRecord) {
if (Self.RequireCompleteType(OpRange.getBegin(), SrcPointee,
diag::err_bad_dynamic_cast_incomplete,
SrcExpr.get())) {
SrcExpr = ExprError();
return;
}
} else {
Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_class)
<< SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
SrcExpr = ExprError();
return;
}
assert((DestPointer || DestReference) &&
"Bad destination non-ptr/ref slipped through.");
assert((DestRecord || DestPointee->isVoidType()) &&
"Bad destination pointee slipped through.");
assert(SrcRecord && "Bad source pointee slipped through.");
// C++ 5.2.7p1: The dynamic_cast operator shall not cast away constness.
if (!DestPointee.isAtLeastAsQualifiedAs(SrcPointee)) {
Self.Diag(OpRange.getBegin(), diag::err_bad_cxx_cast_qualifiers_away)
<< CT_Dynamic << OrigSrcType << this->DestType << OpRange;
SrcExpr = ExprError();
return;
}
// C++ 5.2.7p3: If the type of v is the same as the required result type,
// [except for cv].
if (DestRecord == SrcRecord) {
Kind = CK_NoOp;
return;
}
// C++ 5.2.7p5
// Upcasts are resolved statically.
if (DestRecord &&
Self.IsDerivedFrom(OpRange.getBegin(), SrcPointee, DestPointee)) {
if (Self.CheckDerivedToBaseConversion(SrcPointee, DestPointee,
OpRange.getBegin(), OpRange,
&BasePath)) {
SrcExpr = ExprError();
return;
}
Kind = CK_DerivedToBase;
return;
}
// C++ 5.2.7p6: Otherwise, v shall be [polymorphic].
const RecordDecl *SrcDecl = SrcRecord->getDecl()->getDefinition();
assert(SrcDecl && "Definition missing");
if (!cast<CXXRecordDecl>(SrcDecl)->isPolymorphic()) {
Self.Diag(OpRange.getBegin(), diag::err_bad_dynamic_cast_not_polymorphic)
<< SrcPointee.getUnqualifiedType() << SrcExpr.get()->getSourceRange();
SrcExpr = ExprError();
}
// dynamic_cast is not available with -fno-rtti.
// As an exception, dynamic_cast to void* is available because it doesn't
// use RTTI.
if (!Self.getLangOpts().RTTI && !DestPointee->isVoidType()) {
Self.Diag(OpRange.getBegin(), diag::err_no_dynamic_cast_with_fno_rtti);
SrcExpr = ExprError();
return;
}
// Done. Everything else is run-time checks.
Kind = CK_Dynamic;
}
/// CheckConstCast - Check that a const_cast\<DestType\>(SrcExpr) is valid.
/// Refer to C++ 5.2.11 for details. const_cast is typically used in code
/// like this:
/// const char *str = "literal";
/// legacy_function(const_cast\<char*\>(str));
void CastOperation::CheckConstCast() {
if (ValueKind == VK_RValue)
SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
else if (isPlaceholder())
SrcExpr = Self.CheckPlaceholderExpr(SrcExpr.get());
if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
return;
unsigned msg = diag::err_bad_cxx_cast_generic;
if (TryConstCast(Self, SrcExpr, DestType, /*CStyle*/false, msg) != TC_Success
&& msg != 0) {
Self.Diag(OpRange.getBegin(), msg) << CT_Const
<< SrcExpr.get()->getType() << DestType << OpRange;
SrcExpr = ExprError();
}
}
/// Check that a reinterpret_cast\<DestType\>(SrcExpr) is not used as upcast
/// or downcast between respective pointers or references.
static void DiagnoseReinterpretUpDownCast(Sema &Self, const Expr *SrcExpr,
QualType DestType,
SourceRange OpRange) {
QualType SrcType = SrcExpr->getType();
// When casting from pointer or reference, get pointee type; use original
// type otherwise.
const CXXRecordDecl *SrcPointeeRD = SrcType->getPointeeCXXRecordDecl();
const CXXRecordDecl *SrcRD =
SrcPointeeRD ? SrcPointeeRD : SrcType->getAsCXXRecordDecl();
// Examining subobjects for records is only possible if the complete and
// valid definition is available. Also, template instantiation is not
// allowed here.
if (!SrcRD || !SrcRD->isCompleteDefinition() || SrcRD->isInvalidDecl())
return;
const CXXRecordDecl *DestRD = DestType->getPointeeCXXRecordDecl();
if (!DestRD || !DestRD->isCompleteDefinition() || DestRD->isInvalidDecl())
return;
enum {
ReinterpretUpcast,
ReinterpretDowncast
} ReinterpretKind;
CXXBasePaths BasePaths;
if (SrcRD->isDerivedFrom(DestRD, BasePaths))
ReinterpretKind = ReinterpretUpcast;
else if (DestRD->isDerivedFrom(SrcRD, BasePaths))
ReinterpretKind = ReinterpretDowncast;
else
return;
bool VirtualBase = true;
bool NonZeroOffset = false;
for (CXXBasePaths::const_paths_iterator I = BasePaths.begin(),
E = BasePaths.end();
I != E; ++I) {
const CXXBasePath &Path = *I;
CharUnits Offset = CharUnits::Zero();
bool IsVirtual = false;
for (CXXBasePath::const_iterator IElem = Path.begin(), EElem = Path.end();
IElem != EElem; ++IElem) {
IsVirtual = IElem->Base->isVirtual();
if (IsVirtual)
break;
const CXXRecordDecl *BaseRD = IElem->Base->getType()->getAsCXXRecordDecl();
assert(BaseRD && "Base type should be a valid unqualified class type");
// Don't check if any base has invalid declaration or has no definition
// since it has no layout info.
const CXXRecordDecl *Class = IElem->Class,
*ClassDefinition = Class->getDefinition();
if (Class->isInvalidDecl() || !ClassDefinition ||
!ClassDefinition->isCompleteDefinition())
return;
const ASTRecordLayout &DerivedLayout =
Self.Context.getASTRecordLayout(Class);
Offset += DerivedLayout.getBaseClassOffset(BaseRD);
}
if (!IsVirtual) {
// Don't warn if any path is a non-virtually derived base at offset zero.
if (Offset.isZero())
return;
// Offset makes sense only for non-virtual bases.
else
NonZeroOffset = true;
}
VirtualBase = VirtualBase && IsVirtual;
}
(void) NonZeroOffset; // Silence set but not used warning.
assert((VirtualBase || NonZeroOffset) &&
"Should have returned if has non-virtual base with zero offset");
QualType BaseType =
ReinterpretKind == ReinterpretUpcast? DestType : SrcType;
QualType DerivedType =
ReinterpretKind == ReinterpretUpcast? SrcType : DestType;
SourceLocation BeginLoc = OpRange.getBegin();
Self.Diag(BeginLoc, diag::warn_reinterpret_different_from_static)
<< DerivedType << BaseType << !VirtualBase << int(ReinterpretKind)
<< OpRange;
Self.Diag(BeginLoc, diag::note_reinterpret_updowncast_use_static)
<< int(ReinterpretKind)
<< FixItHint::CreateReplacement(BeginLoc, "static_cast");
}
/// CheckReinterpretCast - Check that a reinterpret_cast\<DestType\>(SrcExpr) is
/// valid.
/// Refer to C++ 5.2.10 for details. reinterpret_cast is typically used in code
/// like this:
/// char *bytes = reinterpret_cast\<char*\>(int_ptr);
void CastOperation::CheckReinterpretCast() {
if (ValueKind == VK_RValue && !isPlaceholder(BuiltinType::Overload))
SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
else
checkNonOverloadPlaceholders();
if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
return;
unsigned msg = diag::err_bad_cxx_cast_generic;
TryCastResult tcr =
TryReinterpretCast(Self, SrcExpr, DestType,
/*CStyle*/false, OpRange, msg, Kind);
if (tcr != TC_Success && msg != 0)
{
if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
return;
if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
//FIXME: &f<int>; is overloaded and resolvable
Self.Diag(OpRange.getBegin(), diag::err_bad_reinterpret_cast_overload)
<< OverloadExpr::find(SrcExpr.get()).Expression->getName()
<< DestType << OpRange;
Self.NoteAllOverloadCandidates(SrcExpr.get());
} else {
diagnoseBadCast(Self, msg, CT_Reinterpret, OpRange, SrcExpr.get(),
DestType, /*listInitialization=*/false);
}
SrcExpr = ExprError();
} else if (tcr == TC_Success) {
if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers())
checkObjCConversion(Sema::CCK_OtherCast);
DiagnoseReinterpretUpDownCast(Self, SrcExpr.get(), DestType, OpRange);
}
}
/// CheckStaticCast - Check that a static_cast\<DestType\>(SrcExpr) is valid.
/// Refer to C++ 5.2.9 for details. Static casts are mostly used for making
/// implicit conversions explicit and getting rid of data loss warnings.
void CastOperation::CheckStaticCast() {
if (isPlaceholder()) {
checkNonOverloadPlaceholders();
if (SrcExpr.isInvalid())
return;
}
// This test is outside everything else because it's the only case where
// a non-lvalue-reference target type does not lead to decay.
// C++ 5.2.9p4: Any expression can be explicitly converted to type "cv void".
if (DestType->isVoidType()) {
Kind = CK_ToVoid;
if (claimPlaceholder(BuiltinType::Overload)) {
Self.ResolveAndFixSingleFunctionTemplateSpecialization(SrcExpr,
false, // Decay Function to ptr
true, // Complain
OpRange, DestType, diag::err_bad_static_cast_overload);
if (SrcExpr.isInvalid())
return;
}
SrcExpr = Self.IgnoredValueConversions(SrcExpr.get());
return;
}
if (ValueKind == VK_RValue && !DestType->isRecordType() &&
!isPlaceholder(BuiltinType::Overload)) {
SrcExpr = Self.DefaultFunctionArrayLvalueConversion(SrcExpr.get());
if (SrcExpr.isInvalid()) // if conversion failed, don't report another error
return;
}
unsigned msg = diag::err_bad_cxx_cast_generic;
TryCastResult tcr
= TryStaticCast(Self, SrcExpr, DestType, Sema::CCK_OtherCast, OpRange, msg,
Kind, BasePath, /*ListInitialization=*/false);
if (tcr != TC_Success && msg != 0) {
if (SrcExpr.isInvalid())
return;
if (SrcExpr.get()->getType() == Self.Context.OverloadTy) {
OverloadExpr* oe = OverloadExpr::find(SrcExpr.get()).Expression;
Self.Diag(OpRange.getBegin(), diag::err_bad_static_cast_overload)
<< oe->getName() << DestType << OpRange
<< oe->getQualifierLoc().getSourceRange();
Self.NoteAllOverloadCandidates(SrcExpr.get());
} else {
diagnoseBadCast(Self, msg, CT_Static, OpRange, SrcExpr.get(), DestType,
/*listInitialization=*/false);
}
SrcExpr = ExprError();
} else if (tcr == TC_Success) {
if (Kind == CK_BitCast)
checkCastAlign();
if (Self.getLangOpts().allowsNonTrivialObjCLifetimeQualifiers())
checkObjCConversion(Sema::CCK_OtherCast);
} else if (Kind == CK_BitCast) {
checkCastAlign();
}
}
/// TryStaticCast - Check if a static cast can be performed, and do so if
/// possible. If @p CStyle, ignore access restrictions on hierarchy casting
/// and casting away constness.
static TryCastResult TryStaticCast(Sema &Self, ExprResult &SrcExpr,
QualType DestType,
Sema::CheckedConversionKind CCK,
SourceRange OpRange, unsigned &msg,
CastKind &Kind, CXXCastPath &BasePath,
bool ListInitialization) {
// Determine whether we have the semantics of a C-style cast.
bool CStyle
= (CCK == Sema::CCK_CStyleCast || CCK == Sema::CCK_FunctionalCast);
// The order the tests is not entirely arbitrary. There is one conversion
// that can be handled in two different ways. Given:
// struct A {};
// struct B : public A {
// B(); B(const A&);
// };
// const A &a = B();