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//===--- Overload.h - C++ Overloading ---------------------------*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file defines the data structures and types used in C++
// overload resolution.
#include "clang/AST/Decl.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/Expr.h"
#include "clang/AST/TemplateBase.h"
#include "clang/AST/Type.h"
#include "clang/AST/UnresolvedSet.h"
#include "clang/Sema/SemaFixItUtils.h"
#include "clang/Sema/TemplateDeduction.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/AlignOf.h"
#include "llvm/Support/Allocator.h"
namespace clang {
class ASTContext;
class CXXConstructorDecl;
class CXXConversionDecl;
class FunctionDecl;
class Sema;
/// OverloadingResult - Capture the result of performing overload
/// resolution.
enum OverloadingResult {
OR_Success, ///< Overload resolution succeeded.
OR_No_Viable_Function, ///< No viable function found.
OR_Ambiguous, ///< Ambiguous candidates found.
OR_Deleted ///< Succeeded, but refers to a deleted function.
enum OverloadCandidateDisplayKind {
/// Requests that all candidates be shown. Viable candidates will
/// be printed first.
/// Requests that only viable candidates be shown.
/// ImplicitConversionKind - The kind of implicit conversion used to
/// convert an argument to a parameter's type. The enumerator values
/// match with Table 9 of (C++ and are listed such that
/// better conversion kinds have smaller values.
enum ImplicitConversionKind {
ICK_Identity = 0, ///< Identity conversion (no conversion)
ICK_Lvalue_To_Rvalue, ///< Lvalue-to-rvalue conversion (C++ 4.1)
ICK_Array_To_Pointer, ///< Array-to-pointer conversion (C++ 4.2)
ICK_Function_To_Pointer, ///< Function-to-pointer (C++ 4.3)
ICK_Function_Conversion, ///< Function pointer conversion (C++17 4.13)
ICK_Qualification, ///< Qualification conversions (C++ 4.4)
ICK_Integral_Promotion, ///< Integral promotions (C++ 4.5)
ICK_Floating_Promotion, ///< Floating point promotions (C++ 4.6)
ICK_Complex_Promotion, ///< Complex promotions (Clang extension)
ICK_Integral_Conversion, ///< Integral conversions (C++ 4.7)
ICK_Floating_Conversion, ///< Floating point conversions (C++ 4.8)
ICK_Complex_Conversion, ///< Complex conversions (C99
ICK_Floating_Integral, ///< Floating-integral conversions (C++ 4.9)
ICK_Pointer_Conversion, ///< Pointer conversions (C++ 4.10)
ICK_Pointer_Member, ///< Pointer-to-member conversions (C++ 4.11)
ICK_Boolean_Conversion, ///< Boolean conversions (C++ 4.12)
ICK_Compatible_Conversion, ///< Conversions between compatible types in C99
ICK_Derived_To_Base, ///< Derived-to-base (C++ [])
ICK_Vector_Conversion, ///< Vector conversions
ICK_Vector_Splat, ///< A vector splat from an arithmetic type
ICK_Complex_Real, ///< Complex-real conversions (C99
ICK_Block_Pointer_Conversion, ///< Block Pointer conversions
ICK_TransparentUnionConversion, ///< Transparent Union Conversions
ICK_Writeback_Conversion, ///< Objective-C ARC writeback conversion
ICK_Zero_Event_Conversion, ///< Zero constant to event (OpenCL1.2 6.12.10)
ICK_Zero_Queue_Conversion, ///< Zero constant to queue
ICK_C_Only_Conversion, ///< Conversions allowed in C, but not C++
ICK_Incompatible_Pointer_Conversion, ///< C-only conversion between pointers
/// with incompatible types
ICK_Num_Conversion_Kinds, ///< The number of conversion kinds
/// ImplicitConversionRank - The rank of an implicit conversion
/// kind. The enumerator values match with Table 9 of (C++
/// and are listed such that better conversion ranks
/// have smaller values.
enum ImplicitConversionRank {
ICR_Exact_Match = 0, ///< Exact Match
ICR_Promotion, ///< Promotion
ICR_Conversion, ///< Conversion
ICR_OCL_Scalar_Widening, ///< OpenCL Scalar Widening
ICR_Complex_Real_Conversion, ///< Complex <-> Real conversion
ICR_Writeback_Conversion, ///< ObjC ARC writeback conversion
ICR_C_Conversion, ///< Conversion only allowed in the C standard.
/// (e.g. void* to char*)
ICR_C_Conversion_Extension ///< Conversion not allowed by the C standard,
/// but that we accept as an extension anyway.
ImplicitConversionRank GetConversionRank(ImplicitConversionKind Kind);
/// NarrowingKind - The kind of narrowing conversion being performed by a
/// standard conversion sequence according to C++11 [dcl.init.list]p7.
enum NarrowingKind {
/// Not a narrowing conversion.
/// A narrowing conversion by virtue of the source and destination types.
/// A narrowing conversion, because a constant expression got narrowed.
/// A narrowing conversion, because a non-constant-expression variable might
/// have got narrowed.
/// Cannot tell whether this is a narrowing conversion because the
/// expression is value-dependent.
/// StandardConversionSequence - represents a standard conversion
/// sequence (C++ A standard conversion sequence
/// contains between zero and three conversions. If a particular
/// conversion is not needed, it will be set to the identity conversion
/// (ICK_Identity). Note that the three conversions are
/// specified as separate members (rather than in an array) so that
/// we can keep the size of a standard conversion sequence to a
/// single word.
class StandardConversionSequence {
/// First -- The first conversion can be an lvalue-to-rvalue
/// conversion, array-to-pointer conversion, or
/// function-to-pointer conversion.
ImplicitConversionKind First : 8;
/// Second - The second conversion can be an integral promotion,
/// floating point promotion, integral conversion, floating point
/// conversion, floating-integral conversion, pointer conversion,
/// pointer-to-member conversion, or boolean conversion.
ImplicitConversionKind Second : 8;
/// Third - The third conversion can be a qualification conversion
/// or a function conversion.
ImplicitConversionKind Third : 8;
/// \brief Whether this is the deprecated conversion of a
/// string literal to a pointer to non-const character data
/// (C++ 4.2p2).
unsigned DeprecatedStringLiteralToCharPtr : 1;
/// \brief Whether the qualification conversion involves a change in the
/// Objective-C lifetime (for automatic reference counting).
unsigned QualificationIncludesObjCLifetime : 1;
/// IncompatibleObjC - Whether this is an Objective-C conversion
/// that we should warn about (if we actually use it).
unsigned IncompatibleObjC : 1;
/// ReferenceBinding - True when this is a reference binding
/// (C++ [over.ics.ref]).
unsigned ReferenceBinding : 1;
/// DirectBinding - True when this is a reference binding that is a
/// direct binding (C++ [dcl.init.ref]).
unsigned DirectBinding : 1;
/// \brief Whether this is an lvalue reference binding (otherwise, it's
/// an rvalue reference binding).
unsigned IsLvalueReference : 1;
/// \brief Whether we're binding to a function lvalue.
unsigned BindsToFunctionLvalue : 1;
/// \brief Whether we're binding to an rvalue.
unsigned BindsToRvalue : 1;
/// \brief Whether this binds an implicit object argument to a
/// non-static member function without a ref-qualifier.
unsigned BindsImplicitObjectArgumentWithoutRefQualifier : 1;
/// \brief Whether this binds a reference to an object with a different
/// Objective-C lifetime qualifier.
unsigned ObjCLifetimeConversionBinding : 1;
/// FromType - The type that this conversion is converting
/// from. This is an opaque pointer that can be translated into a
/// QualType.
void *FromTypePtr;
/// ToType - The types that this conversion is converting to in
/// each step. This is an opaque pointer that can be translated
/// into a QualType.
void *ToTypePtrs[3];
/// CopyConstructor - The copy constructor that is used to perform
/// this conversion, when the conversion is actually just the
/// initialization of an object via copy constructor. Such
/// conversions are either identity conversions or derived-to-base
/// conversions.
CXXConstructorDecl *CopyConstructor;
DeclAccessPair FoundCopyConstructor;
void setFromType(QualType T) { FromTypePtr = T.getAsOpaquePtr(); }
void setToType(unsigned Idx, QualType T) {
assert(Idx < 3 && "To type index is out of range");
ToTypePtrs[Idx] = T.getAsOpaquePtr();
void setAllToTypes(QualType T) {
ToTypePtrs[0] = T.getAsOpaquePtr();
ToTypePtrs[1] = ToTypePtrs[0];
ToTypePtrs[2] = ToTypePtrs[0];
QualType getFromType() const {
return QualType::getFromOpaquePtr(FromTypePtr);
QualType getToType(unsigned Idx) const {
assert(Idx < 3 && "To type index is out of range");
return QualType::getFromOpaquePtr(ToTypePtrs[Idx]);
void setAsIdentityConversion();
bool isIdentityConversion() const {
return Second == ICK_Identity && Third == ICK_Identity;
ImplicitConversionRank getRank() const;
NarrowingKind getNarrowingKind(ASTContext &Context, const Expr *Converted,
APValue &ConstantValue,
QualType &ConstantType) const;
bool isPointerConversionToBool() const;
bool isPointerConversionToVoidPointer(ASTContext& Context) const;
void dump() const;
/// UserDefinedConversionSequence - Represents a user-defined
/// conversion sequence (C++
struct UserDefinedConversionSequence {
/// \brief Represents the standard conversion that occurs before
/// the actual user-defined conversion.
/// C++11
/// If the user-defined conversion is specified by a constructor
/// (12.3.1), the initial standard conversion sequence converts
/// the source type to the type required by the argument of the
/// constructor. If the user-defined conversion is specified by
/// a conversion function (12.3.2), the initial standard
/// conversion sequence converts the source type to the implicit
/// object parameter of the conversion function.
StandardConversionSequence Before;
/// EllipsisConversion - When this is true, it means user-defined
/// conversion sequence starts with a ... (ellipsis) conversion, instead of
/// a standard conversion. In this case, 'Before' field must be ignored.
// FIXME. I much rather put this as the first field. But there seems to be
// a gcc code gen. bug which causes a crash in a test. Putting it here seems
// to work around the crash.
bool EllipsisConversion : 1;
/// HadMultipleCandidates - When this is true, it means that the
/// conversion function was resolved from an overloaded set having
/// size greater than 1.
bool HadMultipleCandidates : 1;
/// After - Represents the standard conversion that occurs after
/// the actual user-defined conversion.
StandardConversionSequence After;
/// ConversionFunction - The function that will perform the
/// user-defined conversion. Null if the conversion is an
/// aggregate initialization from an initializer list.
FunctionDecl* ConversionFunction;
/// \brief The declaration that we found via name lookup, which might be
/// the same as \c ConversionFunction or it might be a using declaration
/// that refers to \c ConversionFunction.
DeclAccessPair FoundConversionFunction;
void dump() const;
/// Represents an ambiguous user-defined conversion sequence.
struct AmbiguousConversionSequence {
typedef SmallVector<std::pair<NamedDecl*, FunctionDecl*>, 4> ConversionSet;
void *FromTypePtr;
void *ToTypePtr;
char Buffer[sizeof(ConversionSet)];
QualType getFromType() const {
return QualType::getFromOpaquePtr(FromTypePtr);
QualType getToType() const {
return QualType::getFromOpaquePtr(ToTypePtr);
void setFromType(QualType T) { FromTypePtr = T.getAsOpaquePtr(); }
void setToType(QualType T) { ToTypePtr = T.getAsOpaquePtr(); }
ConversionSet &conversions() {
return *reinterpret_cast<ConversionSet*>(Buffer);
const ConversionSet &conversions() const {
return *reinterpret_cast<const ConversionSet*>(Buffer);
void addConversion(NamedDecl *Found, FunctionDecl *D) {
conversions().push_back(std::make_pair(Found, D));
typedef ConversionSet::iterator iterator;
iterator begin() { return conversions().begin(); }
iterator end() { return conversions().end(); }
typedef ConversionSet::const_iterator const_iterator;
const_iterator begin() const { return conversions().begin(); }
const_iterator end() const { return conversions().end(); }
void construct();
void destruct();
void copyFrom(const AmbiguousConversionSequence &);
/// BadConversionSequence - Records information about an invalid
/// conversion sequence.
struct BadConversionSequence {
enum FailureKind {
// This can be null, e.g. for implicit object arguments.
Expr *FromExpr;
FailureKind Kind;
// The type we're converting from (an opaque QualType).
void *FromTy;
// The type we're converting to (an opaque QualType).
void *ToTy;
void init(FailureKind K, Expr *From, QualType To) {
init(K, From->getType(), To);
FromExpr = From;
void init(FailureKind K, QualType From, QualType To) {
Kind = K;
FromExpr = nullptr;
QualType getFromType() const { return QualType::getFromOpaquePtr(FromTy); }
QualType getToType() const { return QualType::getFromOpaquePtr(ToTy); }
void setFromExpr(Expr *E) {
FromExpr = E;
void setFromType(QualType T) { FromTy = T.getAsOpaquePtr(); }
void setToType(QualType T) { ToTy = T.getAsOpaquePtr(); }
/// ImplicitConversionSequence - Represents an implicit conversion
/// sequence, which may be a standard conversion sequence
/// (C++, user-defined conversion sequence (C++,
/// or an ellipsis conversion sequence (C++
class ImplicitConversionSequence {
/// Kind - The kind of implicit conversion sequence. BadConversion
/// specifies that there is no conversion from the source type to
/// the target type. AmbiguousConversion represents the unique
/// ambiguous conversion (C++0x []p10).
enum Kind {
StandardConversion = 0,
enum {
Uninitialized = BadConversion + 1
/// ConversionKind - The kind of implicit conversion sequence.
unsigned ConversionKind : 30;
/// \brief Whether the target is really a std::initializer_list, and the
/// sequence only represents the worst element conversion.
unsigned StdInitializerListElement : 1;
void setKind(Kind K) {
ConversionKind = K;
void destruct() {
if (ConversionKind == AmbiguousConversion) Ambiguous.destruct();
union {
/// When ConversionKind == StandardConversion, provides the
/// details of the standard conversion sequence.
StandardConversionSequence Standard;
/// When ConversionKind == UserDefinedConversion, provides the
/// details of the user-defined conversion sequence.
UserDefinedConversionSequence UserDefined;
/// When ConversionKind == AmbiguousConversion, provides the
/// details of the ambiguous conversion.
AmbiguousConversionSequence Ambiguous;
/// When ConversionKind == BadConversion, provides the details
/// of the bad conversion.
BadConversionSequence Bad;
: ConversionKind(Uninitialized), StdInitializerListElement(false) {
~ImplicitConversionSequence() {
ImplicitConversionSequence(const ImplicitConversionSequence &Other)
: ConversionKind(Other.ConversionKind),
switch (ConversionKind) {
case Uninitialized: break;
case StandardConversion: Standard = Other.Standard; break;
case UserDefinedConversion: UserDefined = Other.UserDefined; break;
case AmbiguousConversion: Ambiguous.copyFrom(Other.Ambiguous); break;
case EllipsisConversion: break;
case BadConversion: Bad = Other.Bad; break;
ImplicitConversionSequence &
operator=(const ImplicitConversionSequence &Other) {
new (this) ImplicitConversionSequence(Other);
return *this;
Kind getKind() const {
assert(isInitialized() && "querying uninitialized conversion");
return Kind(ConversionKind);
/// \brief Return a ranking of the implicit conversion sequence
/// kind, where smaller ranks represent better conversion
/// sequences.
/// In particular, this routine gives user-defined conversion
/// sequences and ambiguous conversion sequences the same rank,
/// per C++ []p10.
unsigned getKindRank() const {
switch (getKind()) {
case StandardConversion:
return 0;
case UserDefinedConversion:
case AmbiguousConversion:
return 1;
case EllipsisConversion:
return 2;
case BadConversion:
return 3;
llvm_unreachable("Invalid ImplicitConversionSequence::Kind!");
bool isBad() const { return getKind() == BadConversion; }
bool isStandard() const { return getKind() == StandardConversion; }
bool isEllipsis() const { return getKind() == EllipsisConversion; }
bool isAmbiguous() const { return getKind() == AmbiguousConversion; }
bool isUserDefined() const { return getKind() == UserDefinedConversion; }
bool isFailure() const { return isBad() || isAmbiguous(); }
/// Determines whether this conversion sequence has been
/// initialized. Most operations should never need to query
/// uninitialized conversions and should assert as above.
bool isInitialized() const { return ConversionKind != Uninitialized; }
/// Sets this sequence as a bad conversion for an explicit argument.
void setBad(BadConversionSequence::FailureKind Failure,
Expr *FromExpr, QualType ToType) {
Bad.init(Failure, FromExpr, ToType);
/// Sets this sequence as a bad conversion for an implicit argument.
void setBad(BadConversionSequence::FailureKind Failure,
QualType FromType, QualType ToType) {
Bad.init(Failure, FromType, ToType);
void setStandard() { setKind(StandardConversion); }
void setEllipsis() { setKind(EllipsisConversion); }
void setUserDefined() { setKind(UserDefinedConversion); }
void setAmbiguous() {
if (ConversionKind == AmbiguousConversion) return;
ConversionKind = AmbiguousConversion;
void setAsIdentityConversion(QualType T) {
/// \brief Whether the target is really a std::initializer_list, and the
/// sequence only represents the worst element conversion.
bool isStdInitializerListElement() const {
return StdInitializerListElement;
void setStdInitializerListElement(bool V = true) {
StdInitializerListElement = V;
// The result of a comparison between implicit conversion
// sequences. Use Sema::CompareImplicitConversionSequences to
// actually perform the comparison.
enum CompareKind {
Better = -1,
Indistinguishable = 0,
Worse = 1
void DiagnoseAmbiguousConversion(Sema &S,
SourceLocation CaretLoc,
const PartialDiagnostic &PDiag) const;
void dump() const;
enum OverloadFailureKind {
/// This conversion candidate was not considered because it
/// duplicates the work of a trivial or derived-to-base
/// conversion.
/// This conversion candidate was not considered because it is
/// an illegal instantiation of a constructor temploid: it is
/// callable with one argument, we only have one argument, and
/// its first parameter type is exactly the type of the class.
/// Defining such a constructor directly is illegal, and
/// template-argument deduction is supposed to ignore such
/// instantiations, but we can still get one with the right
/// kind of implicit instantiation.
/// This conversion candidate is not viable because its result
/// type is not implicitly convertible to the desired type.
/// This conversion function template specialization candidate is not
/// viable because the final conversion was not an exact match.
/// (CUDA) This candidate was not viable because the callee
/// was not accessible from the caller's target (i.e. host->device,
/// global->host, device->host).
/// This candidate function was not viable because an enable_if
/// attribute disabled it.
/// This candidate was not viable because its address could not be taken.
/// This candidate was not viable because its OpenCL extension is disabled.
/// This inherited constructor is not viable because it would slice the
/// argument.
/// A list of implicit conversion sequences for the arguments of an
/// OverloadCandidate.
typedef llvm::MutableArrayRef<ImplicitConversionSequence>
/// OverloadCandidate - A single candidate in an overload set (C++ 13.3).
struct OverloadCandidate {
/// Function - The actual function that this candidate
/// represents. When NULL, this is a built-in candidate
/// (C++ [over.oper]) or a surrogate for a conversion to a
/// function pointer or reference (C++ []).
FunctionDecl *Function;
/// FoundDecl - The original declaration that was looked up /
/// invented / otherwise found, together with its access.
/// Might be a UsingShadowDecl or a FunctionTemplateDecl.
DeclAccessPair FoundDecl;
/// BuiltinParamTypes - Provides the parameter types of a built-in overload
/// candidate. Only valid when Function is NULL.
QualType BuiltinParamTypes[3];
/// Surrogate - The conversion function for which this candidate
/// is a surrogate, but only if IsSurrogate is true.
CXXConversionDecl *Surrogate;
/// The conversion sequences used to convert the function arguments
/// to the function parameters.
ConversionSequenceList Conversions;
/// The FixIt hints which can be used to fix the Bad candidate.
ConversionFixItGenerator Fix;
/// Viable - True to indicate that this overload candidate is viable.
bool Viable;
/// IsSurrogate - True to indicate that this candidate is a
/// surrogate for a conversion to a function pointer or reference
/// (C++ []).
bool IsSurrogate;
/// IgnoreObjectArgument - True to indicate that the first
/// argument's conversion, which for this function represents the
/// implicit object argument, should be ignored. This will be true
/// when the candidate is a static member function (where the
/// implicit object argument is just a placeholder) or a
/// non-static member function when the call doesn't have an
/// object argument.
bool IgnoreObjectArgument;
/// FailureKind - The reason why this candidate is not viable.
/// Actually an OverloadFailureKind.
unsigned char FailureKind;
/// \brief The number of call arguments that were explicitly provided,
/// to be used while performing partial ordering of function templates.
unsigned ExplicitCallArguments;
union {
DeductionFailureInfo DeductionFailure;
/// FinalConversion - For a conversion function (where Function is
/// a CXXConversionDecl), the standard conversion that occurs
/// after the call to the overload candidate to convert the result
/// of calling the conversion function to the required type.
StandardConversionSequence FinalConversion;
/// hasAmbiguousConversion - Returns whether this overload
/// candidate requires an ambiguous conversion or not.
bool hasAmbiguousConversion() const {
for (auto &C : Conversions) {
if (!C.isInitialized()) return false;
if (C.isAmbiguous()) return true;
return false;
bool TryToFixBadConversion(unsigned Idx, Sema &S) {
bool CanFix = Fix.tryToFixConversion(
Conversions[Idx].Bad.getToType(), S);
// If at least one conversion fails, the candidate cannot be fixed.
if (!CanFix)
return CanFix;
unsigned getNumParams() const {
if (IsSurrogate) {
auto STy = Surrogate->getConversionType();
while (STy->isPointerType() || STy->isReferenceType())
STy = STy->getPointeeType();
return STy->getAs<FunctionProtoType>()->getNumParams();
if (Function)
return Function->getNumParams();
return ExplicitCallArguments;
/// OverloadCandidateSet - A set of overload candidates, used in C++
/// overload resolution (C++ 13.3).
class OverloadCandidateSet {
enum CandidateSetKind {
/// Normal lookup.
/// C++ [over.match.oper]:
/// Lookup of operator function candidates in a call using operator
/// syntax. Candidates that have no parameters of class type will be
/// skipped unless there is a parameter of (reference to) enum type and
/// the corresponding argument is of the same enum type.
/// C++ [over.match.copy]:
/// Copy-initialization of an object of class type by user-defined
/// conversion.
/// C++ [over.match.ctor], [over.match.list]
/// Initialization of an object of class type by constructor,
/// using either a parenthesized or braced list of arguments.
SmallVector<OverloadCandidate, 16> Candidates;
llvm::SmallPtrSet<Decl *, 16> Functions;
// Allocator for ConversionSequenceLists. We store the first few of these
// inline to avoid allocation for small sets.
llvm::BumpPtrAllocator SlabAllocator;
SourceLocation Loc;
CandidateSetKind Kind;
constexpr static unsigned NumInlineBytes =
24 * sizeof(ImplicitConversionSequence);
unsigned NumInlineBytesUsed;
llvm::AlignedCharArray<alignof(void *), NumInlineBytes> InlineSpace;
/// If we have space, allocates from inline storage. Otherwise, allocates
/// from the slab allocator.
/// FIXME: It would probably be nice to have a SmallBumpPtrAllocator
/// instead.
/// FIXME: Now that this only allocates ImplicitConversionSequences, do we
/// want to un-generalize this?
template <typename T>
T *slabAllocate(unsigned N) {
// It's simpler if this doesn't need to consider alignment.
static_assert(alignof(T) == alignof(void *),
"Only works for pointer-aligned types.");
static_assert(std::is_trivial<T>::value ||
std::is_same<ImplicitConversionSequence, T>::value,
"Add destruction logic to OverloadCandidateSet::clear().");
unsigned NBytes = sizeof(T) * N;
if (NBytes > NumInlineBytes - NumInlineBytesUsed)
return SlabAllocator.Allocate<T>(N);
char *FreeSpaceStart = InlineSpace.buffer + NumInlineBytesUsed;
assert(uintptr_t(FreeSpaceStart) % alignof(void *) == 0 &&
"Misaligned storage!");
NumInlineBytesUsed += NBytes;
return reinterpret_cast<T *>(FreeSpaceStart);
OverloadCandidateSet(const OverloadCandidateSet &) = delete;
void operator=(const OverloadCandidateSet &) = delete;
void destroyCandidates();
OverloadCandidateSet(SourceLocation Loc, CandidateSetKind CSK)
: Loc(Loc), Kind(CSK), NumInlineBytesUsed(0) {}
~OverloadCandidateSet() { destroyCandidates(); }
SourceLocation getLocation() const { return Loc; }
CandidateSetKind getKind() const { return Kind; }
/// \brief Determine when this overload candidate will be new to the
/// overload set.
bool isNewCandidate(Decl *F) {
return Functions.insert(F->getCanonicalDecl()).second;
/// \brief Clear out all of the candidates.
void clear(CandidateSetKind CSK);
typedef SmallVectorImpl<OverloadCandidate>::iterator iterator;
iterator begin() { return Candidates.begin(); }
iterator end() { return Candidates.end(); }
size_t size() const { return Candidates.size(); }
bool empty() const { return Candidates.empty(); }
/// \brief Allocate storage for conversion sequences for NumConversions
/// conversions.
allocateConversionSequences(unsigned NumConversions) {
ImplicitConversionSequence *Conversions =
// Construct the new objects.
for (unsigned I = 0; I != NumConversions; ++I)
new (&Conversions[I]) ImplicitConversionSequence();
return ConversionSequenceList(Conversions, NumConversions);
/// \brief Add a new candidate with NumConversions conversion sequence slots
/// to the overload set.
OverloadCandidate &addCandidate(unsigned NumConversions = 0,
ConversionSequenceList Conversions = None) {
assert((Conversions.empty() || Conversions.size() == NumConversions) &&
"preallocated conversion sequence has wrong length");
OverloadCandidate &C = Candidates.back();
C.Conversions = Conversions.empty()
? allocateConversionSequences(NumConversions)
: Conversions;
return C;
/// Find the best viable function on this overload set, if it exists.
OverloadingResult BestViableFunction(Sema &S, SourceLocation Loc,
OverloadCandidateSet::iterator& Best);
void NoteCandidates(Sema &S,
OverloadCandidateDisplayKind OCD,
ArrayRef<Expr *> Args,
StringRef Opc = "",
SourceLocation Loc = SourceLocation(),
llvm::function_ref<bool(OverloadCandidate&)> Filter =
[](OverloadCandidate&) { return true; });
bool isBetterOverloadCandidate(Sema &S,
const OverloadCandidate &Cand1,
const OverloadCandidate &Cand2,
SourceLocation Loc,
OverloadCandidateSet::CandidateSetKind Kind);
struct ConstructorInfo {
DeclAccessPair FoundDecl;
CXXConstructorDecl *Constructor;
FunctionTemplateDecl *ConstructorTmpl;
explicit operator bool() const { return Constructor; }
// FIXME: Add an AddOverloadCandidate / AddTemplateOverloadCandidate overload
// that takes one of these.
inline ConstructorInfo getConstructorInfo(NamedDecl *ND) {
if (isa<UsingDecl>(ND))
return ConstructorInfo{};
// For constructors, the access check is performed against the underlying
// declaration, not the found declaration.
auto *D = ND->getUnderlyingDecl();
ConstructorInfo Info = {DeclAccessPair::make(ND, D->getAccess()), nullptr,
Info.ConstructorTmpl = dyn_cast<FunctionTemplateDecl>(D);
if (Info.ConstructorTmpl)
D = Info.ConstructorTmpl->getTemplatedDecl();
Info.Constructor = dyn_cast<CXXConstructorDecl>(D);
return Info;
} // end namespace clang