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-rw-r--r--lib/Sema/SemaInit.cpp164
1 files changed, 141 insertions, 23 deletions
diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index 32024cb335dc..e4789cdf53bf 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -826,6 +826,34 @@ int InitListChecker::numStructUnionElements(QualType DeclType) {
return InitializableMembers - structDecl->hasFlexibleArrayMember();
}
+/// Determine whether Entity is an entity for which it is idiomatic to elide
+/// the braces in aggregate initialization.
+static bool isIdiomaticBraceElisionEntity(const InitializedEntity &Entity) {
+ // Recursive initialization of the one and only field within an aggregate
+ // class is considered idiomatic. This case arises in particular for
+ // initialization of std::array, where the C++ standard suggests the idiom of
+ //
+ // std::array<T, N> arr = {1, 2, 3};
+ //
+ // (where std::array is an aggregate struct containing a single array field.
+
+ // FIXME: Should aggregate initialization of a struct with a single
+ // base class and no members also suppress the warning?
+ if (Entity.getKind() != InitializedEntity::EK_Member || !Entity.getParent())
+ return false;
+
+ auto *ParentRD =
+ Entity.getParent()->getType()->castAs<RecordType>()->getDecl();
+ if (CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(ParentRD))
+ if (CXXRD->getNumBases())
+ return false;
+
+ auto FieldIt = ParentRD->field_begin();
+ assert(FieldIt != ParentRD->field_end() &&
+ "no fields but have initializer for member?");
+ return ++FieldIt == ParentRD->field_end();
+}
+
/// Check whether the range of the initializer \p ParentIList from element
/// \p Index onwards can be used to initialize an object of type \p T. Update
/// \p Index to indicate how many elements of the list were consumed.
@@ -886,7 +914,9 @@ void InitListChecker::CheckImplicitInitList(const InitializedEntity &Entity,
}
// Complain about missing braces.
- if (T->isArrayType() || T->isRecordType()) {
+ if ((T->isArrayType() || T->isRecordType()) &&
+ !ParentIList->isIdiomaticZeroInitializer(SemaRef.getLangOpts()) &&
+ !isIdiomaticBraceElisionEntity(Entity)) {
SemaRef.Diag(StructuredSubobjectInitList->getLocStart(),
diag::warn_missing_braces)
<< StructuredSubobjectInitList->getSourceRange()
@@ -1833,7 +1863,9 @@ void InitListChecker::CheckStructUnionTypes(
// worthwhile to skip over the rest of the initializer, though.
RecordDecl *RD = DeclType->getAs<RecordType>()->getDecl();
RecordDecl::field_iterator FieldEnd = RD->field_end();
- bool CheckForMissingFields = true;
+ bool CheckForMissingFields =
+ !IList->isIdiomaticZeroInitializer(SemaRef.getLangOpts());
+
while (Index < IList->getNumInits()) {
Expr *Init = IList->getInit(Index);
@@ -3531,12 +3563,13 @@ static OverloadingResult
ResolveConstructorOverload(Sema &S, SourceLocation DeclLoc,
MultiExprArg Args,
OverloadCandidateSet &CandidateSet,
+ QualType DestType,
DeclContext::lookup_result Ctors,
OverloadCandidateSet::iterator &Best,
bool CopyInitializing, bool AllowExplicit,
bool OnlyListConstructors, bool IsListInit,
bool SecondStepOfCopyInit = false) {
- CandidateSet.clear();
+ CandidateSet.clear(OverloadCandidateSet::CSK_InitByConstructor);
for (NamedDecl *D : Ctors) {
auto Info = getConstructorInfo(D);
@@ -3587,6 +3620,50 @@ ResolveConstructorOverload(Sema &S, SourceLocation DeclLoc,
}
}
+ // FIXME: Work around a bug in C++17 guaranteed copy elision.
+ //
+ // When initializing an object of class type T by constructor
+ // ([over.match.ctor]) or by list-initialization ([over.match.list])
+ // from a single expression of class type U, conversion functions of
+ // U that convert to the non-reference type cv T are candidates.
+ // Explicit conversion functions are only candidates during
+ // direct-initialization.
+ //
+ // Note: SecondStepOfCopyInit is only ever true in this case when
+ // evaluating whether to produce a C++98 compatibility warning.
+ if (S.getLangOpts().CPlusPlus17 && Args.size() == 1 &&
+ !SecondStepOfCopyInit) {
+ Expr *Initializer = Args[0];
+ auto *SourceRD = Initializer->getType()->getAsCXXRecordDecl();
+ if (SourceRD && S.isCompleteType(DeclLoc, Initializer->getType())) {
+ const auto &Conversions = SourceRD->getVisibleConversionFunctions();
+ for (auto I = Conversions.begin(), E = Conversions.end(); I != E; ++I) {
+ NamedDecl *D = *I;
+ CXXRecordDecl *ActingDC = cast<CXXRecordDecl>(D->getDeclContext());
+ D = D->getUnderlyingDecl();
+
+ FunctionTemplateDecl *ConvTemplate = dyn_cast<FunctionTemplateDecl>(D);
+ CXXConversionDecl *Conv;
+ if (ConvTemplate)
+ Conv = cast<CXXConversionDecl>(ConvTemplate->getTemplatedDecl());
+ else
+ Conv = cast<CXXConversionDecl>(D);
+
+ if ((AllowExplicit && !CopyInitializing) || !Conv->isExplicit()) {
+ if (ConvTemplate)
+ S.AddTemplateConversionCandidate(ConvTemplate, I.getPair(),
+ ActingDC, Initializer, DestType,
+ CandidateSet, AllowExplicit,
+ /*AllowResultConversion*/false);
+ else
+ S.AddConversionCandidate(Conv, I.getPair(), ActingDC, Initializer,
+ DestType, CandidateSet, AllowExplicit,
+ /*AllowResultConversion*/false);
+ }
+ }
+ }
+ }
+
// Perform overload resolution and return the result.
return CandidateSet.BestViableFunction(S, DeclLoc, Best);
}
@@ -3624,7 +3701,7 @@ static void TryConstructorInitialization(Sema &S,
return;
}
- // C++1z [dcl.init]p17:
+ // C++17 [dcl.init]p17:
// - If the initializer expression is a prvalue and the cv-unqualified
// version of the source type is the same class as the class of the
// destination, the initializer expression is used to initialize the
@@ -3633,7 +3710,7 @@ static void TryConstructorInitialization(Sema &S,
// class or delegating to another constructor from a mem-initializer.
// ObjC++: Lambda captured by the block in the lambda to block conversion
// should avoid copy elision.
- if (S.getLangOpts().CPlusPlus1z &&
+ if (S.getLangOpts().CPlusPlus17 &&
Entity.getKind() != InitializedEntity::EK_Base &&
Entity.getKind() != InitializedEntity::EK_Delegating &&
Entity.getKind() !=
@@ -3686,7 +3763,7 @@ static void TryConstructorInitialization(Sema &S,
// the first phase is omitted.
if (!(UnwrappedArgs.empty() && DestRecordDecl->hasDefaultConstructor()))
Result = ResolveConstructorOverload(S, Kind.getLocation(), Args,
- CandidateSet, Ctors, Best,
+ CandidateSet, DestType, Ctors, Best,
CopyInitialization, AllowExplicit,
/*OnlyListConstructor=*/true,
IsListInit);
@@ -3700,7 +3777,7 @@ static void TryConstructorInitialization(Sema &S,
if (Result == OR_No_Viable_Function) {
AsInitializerList = false;
Result = ResolveConstructorOverload(S, Kind.getLocation(), UnwrappedArgs,
- CandidateSet, Ctors, Best,
+ CandidateSet, DestType, Ctors, Best,
CopyInitialization, AllowExplicit,
/*OnlyListConstructors=*/false,
IsListInit);
@@ -3713,6 +3790,24 @@ static void TryConstructorInitialization(Sema &S,
return;
}
+ bool HadMultipleCandidates = (CandidateSet.size() > 1);
+
+ // In C++17, ResolveConstructorOverload can select a conversion function
+ // instead of a constructor.
+ if (auto *CD = dyn_cast<CXXConversionDecl>(Best->Function)) {
+ // Add the user-defined conversion step that calls the conversion function.
+ QualType ConvType = CD->getConversionType();
+ assert(S.Context.hasSameUnqualifiedType(ConvType, DestType) &&
+ "should not have selected this conversion function");
+ Sequence.AddUserConversionStep(CD, Best->FoundDecl, ConvType,
+ HadMultipleCandidates);
+ if (!S.Context.hasSameType(ConvType, DestType))
+ Sequence.AddQualificationConversionStep(DestType, VK_RValue);
+ if (IsListInit)
+ Sequence.RewrapReferenceInitList(Entity.getType(), ILE);
+ return;
+ }
+
// C++11 [dcl.init]p6:
// If a program calls for the default initialization of an object
// of a const-qualified type T, T shall be a class type with a
@@ -3741,7 +3836,6 @@ static void TryConstructorInitialization(Sema &S,
// Add the constructor initialization step. Any cv-qualification conversion is
// subsumed by the initialization.
- bool HadMultipleCandidates = (CandidateSet.size() > 1);
Sequence.AddConstructorInitializationStep(
Best->FoundDecl, CtorDecl, DestArrayType, HadMultipleCandidates,
IsListInit | IsInitListCopy, AsInitializerList);
@@ -3984,7 +4078,7 @@ static void TryListInitialization(Sema &S,
// value T(v); if a narrowing conversion is required to convert v to
// the underlying type of T, the program is ill-formed.
auto *ET = DestType->getAs<EnumType>();
- if (S.getLangOpts().CPlusPlus1z &&
+ if (S.getLangOpts().CPlusPlus17 &&
Kind.getKind() == InitializationKind::IK_DirectList &&
ET && ET->getDecl()->isFixed() &&
!S.Context.hasSameUnqualifiedType(E->getType(), DestType) &&
@@ -4087,7 +4181,7 @@ static OverloadingResult TryRefInitWithConversionFunction(
// Build the candidate set directly in the initialization sequence
// structure, so that it will persist if we fail.
OverloadCandidateSet &CandidateSet = Sequence.getFailedCandidateSet();
- CandidateSet.clear();
+ CandidateSet.clear(OverloadCandidateSet::CSK_InitByUserDefinedConversion);
// Determine whether we are allowed to call explicit constructors or
// explicit conversion operators.
@@ -4173,7 +4267,7 @@ static OverloadingResult TryRefInitWithConversionFunction(
// Perform overload resolution. If it fails, return the failed result.
OverloadCandidateSet::iterator Best;
if (OverloadingResult Result
- = CandidateSet.BestViableFunction(S, DeclLoc, Best, true))
+ = CandidateSet.BestViableFunction(S, DeclLoc, Best))
return Result;
FunctionDecl *Function = Best->Function;
@@ -4417,7 +4511,7 @@ static void TryReferenceInitializationCore(Sema &S,
RefRelationship == Sema::Ref_Related)) &&
((InitCategory.isXValue() && !isNonReferenceableGLValue(Initializer)) ||
(InitCategory.isPRValue() &&
- (S.getLangOpts().CPlusPlus1z || T2->isRecordType() ||
+ (S.getLangOpts().CPlusPlus17 || T2->isRecordType() ||
T2->isArrayType())))) {
ExprValueKind ValueKind = InitCategory.isXValue() ? VK_XValue : VK_RValue;
if (InitCategory.isPRValue() && T2->isRecordType()) {
@@ -4687,7 +4781,7 @@ static void TryUserDefinedConversion(Sema &S,
// Build the candidate set directly in the initialization sequence
// structure, so that it will persist if we fail.
OverloadCandidateSet &CandidateSet = Sequence.getFailedCandidateSet();
- CandidateSet.clear();
+ CandidateSet.clear(OverloadCandidateSet::CSK_InitByUserDefinedConversion);
// Determine whether we are allowed to call explicit constructors or
// explicit conversion operators.
@@ -4766,7 +4860,7 @@ static void TryUserDefinedConversion(Sema &S,
// Perform overload resolution. If it fails, return the failed result.
OverloadCandidateSet::iterator Best;
if (OverloadingResult Result
- = CandidateSet.BestViableFunction(S, DeclLoc, Best, true)) {
+ = CandidateSet.BestViableFunction(S, DeclLoc, Best)) {
Sequence.SetOverloadFailure(
InitializationSequence::FK_UserConversionOverloadFailed,
Result);
@@ -4793,7 +4887,7 @@ static void TryUserDefinedConversion(Sema &S,
// copy-initialization.
// Note that this just performs a simple object copy from the temporary.
//
- // C++1z:
+ // C++17:
// - if the function is a constructor, the call is a prvalue of the
// cv-unqualified version of the destination type whose return object
// is initialized by the constructor. The call is used to
@@ -4802,7 +4896,7 @@ static void TryUserDefinedConversion(Sema &S,
// Therefore we need to do nothing further.
//
// FIXME: Mark this copy as extraneous.
- if (!S.getLangOpts().CPlusPlus1z)
+ if (!S.getLangOpts().CPlusPlus17)
Sequence.AddFinalCopy(DestType);
else if (DestType.hasQualifiers())
Sequence.AddQualificationConversionStep(DestType, VK_RValue);
@@ -4818,13 +4912,13 @@ static void TryUserDefinedConversion(Sema &S,
// The call is used to direct-initialize [...] the object that is the
// destination of the copy-initialization.
//
- // In C++1z, this does not call a constructor if we enter /17.6.1:
+ // In C++17, this does not call a constructor if we enter /17.6.1:
// - If the initializer expression is a prvalue and the cv-unqualified
// version of the source type is the same as the class of the
// destination [... do not make an extra copy]
//
// FIXME: Mark this copy as extraneous.
- if (!S.getLangOpts().CPlusPlus1z ||
+ if (!S.getLangOpts().CPlusPlus17 ||
Function->getReturnType()->isReferenceType() ||
!S.Context.hasSameUnqualifiedType(ConvType, DestType))
Sequence.AddFinalCopy(DestType);
@@ -5657,7 +5751,7 @@ static ExprResult CopyObject(Sema &S,
OverloadCandidateSet::iterator Best;
switch (ResolveConstructorOverload(
- S, Loc, CurInitExpr, CandidateSet, Ctors, Best,
+ S, Loc, CurInitExpr, CandidateSet, T, Ctors, Best,
/*CopyInitializing=*/false, /*AllowExplicit=*/true,
/*OnlyListConstructors=*/false, /*IsListInit=*/false,
/*SecondStepOfCopyInit=*/true)) {
@@ -5797,7 +5891,7 @@ static void CheckCXX98CompatAccessibleCopy(Sema &S,
// Perform overload resolution.
OverloadCandidateSet::iterator Best;
OverloadingResult OR = ResolveConstructorOverload(
- S, Loc, CurInitExpr, CandidateSet, Ctors, Best,
+ S, Loc, CurInitExpr, CandidateSet, CurInitExpr->getType(), Ctors, Best,
/*CopyInitializing=*/false, /*AllowExplicit=*/true,
/*OnlyListConstructors=*/false, /*IsListInit=*/false,
/*SecondStepOfCopyInit=*/true);
@@ -6328,6 +6422,10 @@ static void CheckMoveOnConstruction(Sema &S, const Expr *InitExpr,
if (!VD || !VD->hasLocalStorage())
return;
+ // __block variables are not moved implicitly.
+ if (VD->hasAttr<BlocksAttr>())
+ return;
+
QualType SourceType = VD->getType();
if (!SourceType->isRecordType())
return;
@@ -7535,8 +7633,7 @@ bool InitializationSequence::Diagnose(Sema &S,
<< Args[0]->getSourceRange();
OverloadCandidateSet::iterator Best;
OverloadingResult Ovl
- = FailedCandidateSet.BestViableFunction(S, Kind.getLocation(), Best,
- true);
+ = FailedCandidateSet.BestViableFunction(S, Kind.getLocation(), Best);
if (Ovl == OR_Deleted) {
S.NoteDeletedFunction(Best->Function);
} else {
@@ -8339,6 +8436,16 @@ Sema::PerformCopyInitialization(const InitializedEntity &Entity,
return Result;
}
+/// Determine whether RD is, or is derived from, a specialization of CTD.
+static bool isOrIsDerivedFromSpecializationOf(CXXRecordDecl *RD,
+ ClassTemplateDecl *CTD) {
+ auto NotSpecialization = [&] (const CXXRecordDecl *Candidate) {
+ auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(Candidate);
+ return !CTSD || !declaresSameEntity(CTSD->getSpecializedTemplate(), CTD);
+ };
+ return !(NotSpecialization(RD) && RD->forallBases(NotSpecialization));
+}
+
QualType Sema::DeduceTemplateSpecializationFromInitializer(
TypeSourceInfo *TSInfo, const InitializedEntity &Entity,
const InitializationKind &Kind, MultiExprArg Inits) {
@@ -8405,7 +8512,7 @@ QualType Sema::DeduceTemplateSpecializationFromInitializer(
OverloadCandidateSet::iterator Best;
auto tryToResolveOverload =
[&](bool OnlyListConstructors) -> OverloadingResult {
- Candidates.clear();
+ Candidates.clear(OverloadCandidateSet::CSK_Normal);
for (auto I = Guides.begin(), E = Guides.end(); I != E; ++I) {
NamedDecl *D = (*I)->getUnderlyingDecl();
if (D->isInvalidDecl())
@@ -8483,6 +8590,17 @@ QualType Sema::DeduceTemplateSpecializationFromInitializer(
break;
}
}
+ } else if (ListInit->getNumInits() == 1) {
+ // C++ [over.match.class.deduct]:
+ // As an exception, the first phase in [over.match.list] (considering
+ // initializer-list constructors) is omitted if the initializer list
+ // consists of a single expression of type cv U, where U is a
+ // specialization of C or a class derived from a specialization of C.
+ Expr *E = ListInit->getInit(0);
+ auto *RD = E->getType()->getAsCXXRecordDecl();
+ if (!isa<InitListExpr>(E) && RD &&
+ isOrIsDerivedFromSpecializationOf(RD, Template))
+ TryListConstructors = false;
}
if (TryListConstructors)
generated by cgit v1.2.3 (git 2.25.1) at 2025-11-04 15:27:13 +0000