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Make both old and new versions of reference binding use the new classification functions, and updated them for N3092. 

llvm-svn: 107301
This commit is contained in:
Sebastian Redl 2010-06-30 18:13:39 +00:00
parent 5c768e4915
commit d92badfd9c
3 changed files with 195 additions and 156 deletions
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54
clang/lib/Sema/SemaInit.cpp
View File

@ -2239,8 +2239,6 @@ static void TryListInitialization(Sema &S,
/// \brief Try a reference initialization that involves calling a conversion
/// function.
///
/// FIXME: look intos DRs 656, 896
static OverloadingResult TryRefInitWithConversionFunction(Sema &S,
const InitializedEntity &Entity,
const InitializationKind &Kind,
@ -2331,7 +2329,7 @@ static OverloadingResult TryRefInitWithConversionFunction(Sema &S,
if (ConvTemplate)
Conv = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
else
Conv = cast<CXXConversionDecl>(*I);
Conv = cast<CXXConversionDecl>(D);
// If the conversion function doesn't return a reference type,
// it can't be considered for this conversion unless we're allowed to
@ -2401,14 +2399,14 @@ static OverloadingResult TryRefInitWithConversionFunction(Sema &S,
return OR_Success;
}
/// \brief Attempt reference initialization (C++0x [dcl.init.list])
/// \brief Attempt reference initialization (C++0x [dcl.init.ref])
static void TryReferenceInitialization(Sema &S,
const InitializedEntity &Entity,
const InitializationKind &Kind,
Expr *Initializer,
InitializationSequence &Sequence) {
Sequence.setSequenceKind(InitializationSequence::ReferenceBinding);
QualType DestType = Entity.getType();
QualType cv1T1 = DestType->getAs<ReferenceType>()->getPointeeType();
Qualifiers T1Quals;
@ -2417,7 +2415,7 @@ static void TryReferenceInitialization(Sema &S,
Qualifiers T2Quals;
QualType T2 = S.Context.getUnqualifiedArrayType(cv2T2, T2Quals);
SourceLocation DeclLoc = Initializer->getLocStart();
// If the initializer is the address of an overloaded function, try
// to resolve the overloaded function. If all goes well, T2 is the
// type of the resulting function.
@ -2431,29 +2429,33 @@ static void TryReferenceInitialization(Sema &S,
Sequence.SetFailed(InitializationSequence::FK_AddressOfOverloadFailed);
return;
}
Sequence.AddAddressOverloadResolutionStep(Fn, Found);
cv2T2 = Fn->getType();
T2 = cv2T2.getUnqualifiedType();
}
// Compute some basic properties of the types and the initializer.
bool isLValueRef = DestType->isLValueReferenceType();
bool isRValueRef = !isLValueRef;
bool DerivedToBase = false;
Expr::isLvalueResult InitLvalue = Initializer->isLvalue(S.Context);
Expr::Classification InitCategory = Initializer->Classify(S.Context);
Sema::ReferenceCompareResult RefRelationship
= S.CompareReferenceRelationship(DeclLoc, cv1T1, cv2T2, DerivedToBase);
// C++0x [dcl.init.ref]p5:
// A reference to type "cv1 T1" is initialized by an expression of type
// "cv2 T2" as follows:
//
// - If the reference is an lvalue reference and the initializer
// expression
// Note the analogous bullet points for rvlaue refs to functions. Because
// there are no function rvalues in C++, rvalue refs to functions are treated
// like lvalue refs.
OverloadingResult ConvOvlResult = OR_Success;
if (isLValueRef) {
if (InitLvalue == Expr::LV_Valid &&
bool T1Function = T1->isFunctionType();
if (isLValueRef || T1Function) {
if (InitCategory.isLValue() &&
RefRelationship >= Sema::Ref_Compatible_With_Added_Qualification) {
// - is an lvalue (but is not a bit-field), and "cv1 T1" is
// reference-compatible with "cv2 T2," or
@ -2481,10 +2483,13 @@ static void TryReferenceInitialization(Sema &S,
// with "cv3 T3" (this conversion is selected by enumerating the
// applicable conversion functions (13.3.1.6) and choosing the best
// one through overload resolution (13.3)),
if (RefRelationship == Sema::Ref_Incompatible && T2->isRecordType()) {
// If we have an rvalue ref to function type here, the rhs must be
// an rvalue.
if (RefRelationship == Sema::Ref_Incompatible && T2->isRecordType() &&
(isLValueRef || InitCategory.isRValue())) {
ConvOvlResult = TryRefInitWithConversionFunction(S, Entity, Kind,
Initializer,
/*AllowRValues=*/false,
/*AllowRValues=*/isRValueRef,
Sequence);
if (ConvOvlResult == OR_Success)
return;
@ -2495,19 +2500,20 @@ static void TryReferenceInitialization(Sema &S,
}
}
}
// - Otherwise, the reference shall be an lvalue reference to a
// non-volatile const type (i.e., cv1 shall be const), or the reference
// shall be an rvalue reference and the initializer expression shall
// be an rvalue.
// be an rvalue or have a function type.
// We handled the function type stuff above.
if (!((isLValueRef && T1Quals.hasConst() && !T1Quals.hasVolatile()) ||
(isRValueRef && InitLvalue != Expr::LV_Valid))) {
(isRValueRef && InitCategory.isRValue()))) {
if (ConvOvlResult && !Sequence.getFailedCandidateSet().empty())
Sequence.SetOverloadFailure(
InitializationSequence::FK_ReferenceInitOverloadFailed,
ConvOvlResult);
else if (isLValueRef)
Sequence.SetFailed(InitLvalue == Expr::LV_Valid
Sequence.SetFailed(InitCategory.isLValue()
? (RefRelationship == Sema::Ref_Related
? InitializationSequence::FK_ReferenceInitDropsQualifiers
: InitializationSequence::FK_NonConstLValueReferenceBindingToUnrelated)
@ -2515,15 +2521,15 @@ static void TryReferenceInitialization(Sema &S,
else
Sequence.SetFailed(
InitializationSequence::FK_RValueReferenceBindingToLValue);
return;
}
// - If T1 and T2 are class types and
if (T1->isRecordType() && T2->isRecordType()) {
// - [If T1 is not a function type], if T2 is a class type and
if (!T1Function && T2->isRecordType()) {
// - the initializer expression is an rvalue and "cv1 T1" is
// reference-compatible with "cv2 T2", or
if (InitLvalue != Expr::LV_Valid &&
if (InitCategory.isRValue() &&
RefRelationship >= Sema::Ref_Compatible_With_Added_Qualification) {
// The corresponding bullet in C++03 [dcl.init.ref]p5 gives the
// compiler the freedom to perform a copy here or bind to the
@ -2546,7 +2552,7 @@ static void TryReferenceInitialization(Sema &S,
Sequence.AddReferenceBindingStep(cv1T1, /*bindingTemporary=*/true);
return;
}
// - T1 is not reference-related to T2 and the initializer expression
// can be implicitly converted to an rvalue of type "cv3 T3" (this
// conversion is selected by enumerating the applicable conversion

290
clang/lib/Sema/SemaOverload.cpp
View File

@ -2622,6 +2622,93 @@ Sema::CompareReferenceRelationship(SourceLocation Loc,
return Ref_Related;
}
/// \brief Look for a user-defined conversion to an lvalue reference-compatible
/// with DeclType. Return true if something definite is found.
static bool
FindConversionToLValue(Sema &S, ImplicitConversionSequence &ICS,
QualType DeclType, SourceLocation DeclLoc,
Expr *Init, QualType T2, bool AllowExplicit) {
assert(T2->isRecordType() && "Can only find conversions of record types.");
CXXRecordDecl *T2RecordDecl
= dyn_cast<CXXRecordDecl>(T2->getAs<RecordType>()->getDecl());
OverloadCandidateSet CandidateSet(DeclLoc);
const UnresolvedSetImpl *Conversions
= T2RecordDecl->getVisibleConversionFunctions();
for (UnresolvedSetImpl::iterator I = Conversions->begin(),
E = Conversions->end(); I != E; ++I) {
NamedDecl *D = *I;
CXXRecordDecl *ActingDC = cast<CXXRecordDecl>(D->getDeclContext());
if (isa<UsingShadowDecl>(D))
D = cast<UsingShadowDecl>(D)->getTargetDecl();
FunctionTemplateDecl *ConvTemplate
= dyn_cast<FunctionTemplateDecl>(D);
CXXConversionDecl *Conv;
if (ConvTemplate)
Conv = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
else
Conv = cast<CXXConversionDecl>(D);
// If the conversion function doesn't return a reference type,
// it can't be considered for this conversion. An rvalue reference
// is only acceptable if its referencee is a function type.
const ReferenceType *RefType =
Conv->getConversionType()->getAs<ReferenceType>();
if (RefType && (RefType->isLValueReferenceType() ||
RefType->getPointeeType()->isFunctionType()) &&
(AllowExplicit || !Conv->isExplicit())) {
if (ConvTemplate)
S.AddTemplateConversionCandidate(ConvTemplate, I.getPair(), ActingDC,
Init, DeclType, CandidateSet);
else
S.AddConversionCandidate(Conv, I.getPair(), ActingDC, Init,
DeclType, CandidateSet);
}
}
OverloadCandidateSet::iterator Best;
switch (S.BestViableFunction(CandidateSet, DeclLoc, Best)) {
case OR_Success:
// C++ [over.ics.ref]p1:
//
// [...] If the parameter binds directly to the result of
// applying a conversion function to the argument
// expression, the implicit conversion sequence is a
// user-defined conversion sequence (13.3.3.1.2), with the
// second standard conversion sequence either an identity
// conversion or, if the conversion function returns an
// entity of a type that is a derived class of the parameter
// type, a derived-to-base Conversion.
if (!Best->FinalConversion.DirectBinding)
return false;
ICS.setUserDefined();
ICS.UserDefined.Before = Best->Conversions[0].Standard;
ICS.UserDefined.After = Best->FinalConversion;
ICS.UserDefined.ConversionFunction = Best->Function;
ICS.UserDefined.EllipsisConversion = false;
assert(ICS.UserDefined.After.ReferenceBinding &&
ICS.UserDefined.After.DirectBinding &&
"Expected a direct reference binding!");
return true;
case OR_Ambiguous:
ICS.setAmbiguous();
for (OverloadCandidateSet::iterator Cand = CandidateSet.begin();
Cand != CandidateSet.end(); ++Cand)
if (Cand->Viable)
ICS.Ambiguous.addConversion(Cand->Function);
return true;
case OR_No_Viable_Function:
case OR_Deleted:
// There was no suitable conversion, or we found a deleted
// conversion; continue with other checks.
return false;
}
}
/// \brief Compute an implicit conversion sequence for reference
/// initialization.
static ImplicitConversionSequence
@ -2651,149 +2738,72 @@ TryReferenceInit(Sema &S, Expr *&Init, QualType DeclType,
// Compute some basic properties of the types and the initializer.
bool isRValRef = DeclType->isRValueReferenceType();
bool DerivedToBase = false;
Expr::isLvalueResult InitLvalue = Init->isLvalue(S.Context);
Expr::Classification InitCategory = Init->Classify(S.Context);
Sema::ReferenceCompareResult RefRelationship
= S.CompareReferenceRelationship(DeclLoc, T1, T2, DerivedToBase);
// C++ [over.ics.ref]p3:
// Except for an implicit object parameter, for which see 13.3.1,
// a standard conversion sequence cannot be formed if it requires
// binding an lvalue reference to non-const to an rvalue or
// binding an rvalue reference to an lvalue.
//
// FIXME: DPG doesn't trust this code. It seems far too early to
// abort because of a binding of an rvalue reference to an lvalue.
if (isRValRef && InitLvalue == Expr::LV_Valid)
return ICS;
// C++0x [dcl.init.ref]p16:
// C++0x [dcl.init.ref]p5:
// A reference to type "cv1 T1" is initialized by an expression
// of type "cv2 T2" as follows:
// -- If the initializer expression
// -- is an lvalue (but is not a bit-field), and "cv1 T1" is
// reference-compatible with "cv2 T2," or
//
// Per C++ [over.ics.ref]p4, we don't check the bit-field property here.
if (InitLvalue == Expr::LV_Valid &&
RefRelationship >= Sema::Ref_Compatible_With_Added_Qualification) {
// C++ [over.ics.ref]p1:
// When a parameter of reference type binds directly (8.5.3)
// to an argument expression, the implicit conversion sequence
// is the identity conversion, unless the argument expression
// has a type that is a derived class of the parameter type,
// in which case the implicit conversion sequence is a
// derived-to-base Conversion (13.3.3.1).
ICS.setStandard();
ICS.Standard.First = ICK_Identity;
ICS.Standard.Second = DerivedToBase? ICK_Derived_To_Base : ICK_Identity;
ICS.Standard.Third = ICK_Identity;
ICS.Standard.FromTypePtr = T2.getAsOpaquePtr();
ICS.Standard.setToType(0, T2);
ICS.Standard.setToType(1, T1);
ICS.Standard.setToType(2, T1);
ICS.Standard.ReferenceBinding = true;
ICS.Standard.DirectBinding = true;
ICS.Standard.RRefBinding = false;
ICS.Standard.CopyConstructor = 0;
// Nothing more to do: the inaccessibility/ambiguity check for
// derived-to-base conversions is suppressed when we're
// computing the implicit conversion sequence (C++
// [over.best.ics]p2).
return ICS;
}
// -- has a class type (i.e., T2 is a class type), where T1 is
// not reference-related to T2, and can be implicitly
// converted to an lvalue of type "cv3 T3," where "cv1 T1"
// is reference-compatible with "cv3 T3" 92) (this
// conversion is selected by enumerating the applicable
// conversion functions (13.3.1.6) and choosing the best
// one through overload resolution (13.3)),
if (!isRValRef && !SuppressUserConversions && T2->isRecordType() &&
!S.RequireCompleteType(DeclLoc, T2, 0) &&
RefRelationship == Sema::Ref_Incompatible) {
CXXRecordDecl *T2RecordDecl
= dyn_cast<CXXRecordDecl>(T2->getAs<RecordType>()->getDecl());
OverloadCandidateSet CandidateSet(DeclLoc);
const UnresolvedSetImpl *Conversions
= T2RecordDecl->getVisibleConversionFunctions();
for (UnresolvedSetImpl::iterator I = Conversions->begin(),
E = Conversions->end(); I != E; ++I) {
NamedDecl *D = *I;
CXXRecordDecl *ActingDC = cast<CXXRecordDecl>(D->getDeclContext());
if (isa<UsingShadowDecl>(D))
D = cast<UsingShadowDecl>(D)->getTargetDecl();
FunctionTemplateDecl *ConvTemplate
= dyn_cast<FunctionTemplateDecl>(D);
CXXConversionDecl *Conv;
if (ConvTemplate)
Conv = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
else
Conv = cast<CXXConversionDecl>(D);
// If the conversion function doesn't return a reference type,
// it can't be considered for this conversion.
if (Conv->getConversionType()->isLValueReferenceType() &&
(AllowExplicit || !Conv->isExplicit())) {
if (ConvTemplate)
S.AddTemplateConversionCandidate(ConvTemplate, I.getPair(), ActingDC,
Init, DeclType, CandidateSet);
else
S.AddConversionCandidate(Conv, I.getPair(), ActingDC, Init,
DeclType, CandidateSet);
}
}
OverloadCandidateSet::iterator Best;
switch (S.BestViableFunction(CandidateSet, DeclLoc, Best)) {
case OR_Success:
// -- If reference is an lvalue reference and the initializer expression
// The next bullet point (T1 is a function) is pretty much equivalent to this
// one, so it's handled here.
if (!isRValRef || T1->isFunctionType()) {
// -- is an lvalue (but is not a bit-field), and "cv1 T1" is
// reference-compatible with "cv2 T2," or
//
// Per C++ [over.ics.ref]p4, we don't check the bit-field property here.
if (InitCategory.isLValue() &&
RefRelationship >= Sema::Ref_Compatible_With_Added_Qualification) {
// C++ [over.ics.ref]p1:
//
// [...] If the parameter binds directly to the result of
// applying a conversion function to the argument
// expression, the implicit conversion sequence is a
// user-defined conversion sequence (13.3.3.1.2), with the
// second standard conversion sequence either an identity
// conversion or, if the conversion function returns an
// entity of a type that is a derived class of the parameter
// type, a derived-to-base Conversion.
if (!Best->FinalConversion.DirectBinding)
break;
// When a parameter of reference type binds directly (8.5.3)
// to an argument expression, the implicit conversion sequence
// is the identity conversion, unless the argument expression
// has a type that is a derived class of the parameter type,
// in which case the implicit conversion sequence is a
// derived-to-base Conversion (13.3.3.1).
ICS.setStandard();
ICS.Standard.First = ICK_Identity;
ICS.Standard.Second = DerivedToBase? ICK_Derived_To_Base : ICK_Identity;
ICS.Standard.Third = ICK_Identity;
ICS.Standard.FromTypePtr = T2.getAsOpaquePtr();
ICS.Standard.setToType(0, T2);
ICS.Standard.setToType(1, T1);
ICS.Standard.setToType(2, T1);
ICS.Standard.ReferenceBinding = true;
ICS.Standard.DirectBinding = true;
ICS.Standard.RRefBinding = isRValRef;
ICS.Standard.CopyConstructor = 0;
ICS.setUserDefined();
ICS.UserDefined.Before = Best->Conversions[0].Standard;
ICS.UserDefined.After = Best->FinalConversion;
ICS.UserDefined.ConversionFunction = Best->Function;
ICS.UserDefined.EllipsisConversion = false;
assert(ICS.UserDefined.After.ReferenceBinding &&
ICS.UserDefined.After.DirectBinding &&
"Expected a direct reference binding!");
// Nothing more to do: the inaccessibility/ambiguity check for
// derived-to-base conversions is suppressed when we're
// computing the implicit conversion sequence (C++
// [over.best.ics]p2).
return ICS;
}
case OR_Ambiguous:
ICS.setAmbiguous();
for (OverloadCandidateSet::iterator Cand = CandidateSet.begin();
Cand != CandidateSet.end(); ++Cand)
if (Cand->Viable)
ICS.Ambiguous.addConversion(Cand->Function);
return ICS;
case OR_No_Viable_Function:
case OR_Deleted:
// There was no suitable conversion, or we found a deleted
// conversion; continue with other checks.
break;
// -- has a class type (i.e., T2 is a class type), where T1 is
// not reference-related to T2, and can be implicitly
// converted to an lvalue of type "cv3 T3," where "cv1 T1"
// is reference-compatible with "cv3 T3" 92) (this
// conversion is selected by enumerating the applicable
// conversion functions (13.3.1.6) and choosing the best
// one through overload resolution (13.3)),
if (!SuppressUserConversions && T2->isRecordType() &&
!S.RequireCompleteType(DeclLoc, T2, 0) &&
RefRelationship == Sema::Ref_Incompatible) {
if (FindConversionToLValue(S, ICS, DeclType, DeclLoc,
Init, T2, AllowExplicit))
return ICS;
}
}
// -- Otherwise, the reference shall be to a non-volatile const
// type (i.e., cv1 shall be const), or the reference shall be an
// rvalue reference and the initializer expression shall be an rvalue.
// -- Otherwise, the reference shall be an lvalue reference to a
// non-volatile const type (i.e., cv1 shall be const), or the reference
// shall be an rvalue reference and the initializer expression shall be
// an rvalue or have a function type.
//
// We actually handle one oddity of C++ [over.ics.ref] at this
// point, which is that, due to p2 (which short-circuits reference
@ -2802,10 +2812,26 @@ TryReferenceInit(Sema &S, Expr *&Init, QualType DeclType,
// reference to bind to an rvalue. Hence the check for the presence
// of "const" rather than checking for "const" being the only
// qualifier.
if (!isRValRef && !T1.isConstQualified())
// This is also the point where rvalue references and lvalue inits no longer
// go together.
if ((!isRValRef && !T1.isConstQualified()) ||
(isRValRef && InitCategory.isLValue()))
return ICS;
// -- if T2 is a class type and
// -- If T1 is a function type, then
// -- if T2 is the same type as T1, the reference is bound to the
// initializer expression lvalue;
// -- if T2 is a class type and the initializer expression can be
// implicitly converted to an lvalue of type T1 [...], the
// reference is bound to the function lvalue that is the result
// of the conversion;
// This is the same as for the lvalue case above, so it was handled there.
// -- otherwise, the program is ill-formed.
// This is the one difference to the lvalue case.
if (T1->isFunctionType())
return ICS;
// -- Otherwise, if T2 is a class type and
// -- the initializer expression is an rvalue and "cv1 T1"
// is reference-compatible with "cv2 T2," or
//
@ -2824,7 +2850,7 @@ TryReferenceInit(Sema &S, Expr *&Init, QualType DeclType,
//
// We're only checking the first case here, which is a direct
// binding in C++0x but not in C++03.
if (InitLvalue != Expr::LV_Valid && T2->isRecordType() &&
if (InitCategory.isRValue() && T2->isRecordType() &&
RefRelationship >= Sema::Ref_Compatible_With_Added_Qualification) {
ICS.setStandard();
ICS.Standard.First = ICK_Identity;

7
clang/test/SemaCXX/rval-references.cpp
View File

@ -21,6 +21,10 @@ struct conv_to_not_int_rvalue {
operator not_int &&();
};
typedef void (fun_type)();
void fun();
fun_type &&make_fun();
void f() {
int &&virr1; // expected-error {{declaration of reference variable 'virr1' requires an initializer}}
int &&virr2 = 0;
@ -47,6 +51,9 @@ void f() {
not_int &ni5 = cnir; // expected-error{{non-const lvalue reference to type 'not_int' cannot bind to a value of unrelated type 'conv_to_not_int_rvalue'}}
not_int &&ni6 = conv_to_not_int_rvalue();
fun_type &&fun_ref = fun; // works because functions are special
fun_type &&fun_ref2 = make_fun(); // same
fun_type &fun_lref = make_fun(); // also special
try {
} catch(int&&) { // expected-error {{cannot catch exceptions by rvalue reference}}