1 //===--- Overload.h - C++ Overloading ---------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the data structures and types used in C++
11 // overload resolution.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CLANG_SEMA_OVERLOAD_H
16 #define LLVM_CLANG_SEMA_OVERLOAD_H
18 #include "clang/AST/Decl.h"
19 #include "clang/AST/DeclTemplate.h"
20 #include "clang/AST/Expr.h"
21 #include "clang/AST/TemplateBase.h"
22 #include "clang/AST/Type.h"
23 #include "clang/AST/UnresolvedSet.h"
24 #include "clang/Sema/SemaFixItUtils.h"
25 #include "clang/Sema/TemplateDeduction.h"
26 #include "llvm/ADT/SmallPtrSet.h"
27 #include "llvm/ADT/SmallVector.h"
28 #include "llvm/Support/AlignOf.h"
29 #include "llvm/Support/Allocator.h"
33 class CXXConstructorDecl;
34 class CXXConversionDecl;
38 /// OverloadingResult - Capture the result of performing overload
40 enum OverloadingResult {
41 OR_Success, ///< Overload resolution succeeded.
42 OR_No_Viable_Function, ///< No viable function found.
43 OR_Ambiguous, ///< Ambiguous candidates found.
44 OR_Deleted ///< Succeeded, but refers to a deleted function.
47 enum OverloadCandidateDisplayKind {
48 /// Requests that all candidates be shown. Viable candidates will
52 /// Requests that only viable candidates be shown.
56 /// ImplicitConversionKind - The kind of implicit conversion used to
57 /// convert an argument to a parameter's type. The enumerator values
58 /// match with Table 9 of (C++ 13.3.3.1.1) and are listed such that
59 /// better conversion kinds have smaller values.
60 enum ImplicitConversionKind {
61 ICK_Identity = 0, ///< Identity conversion (no conversion)
62 ICK_Lvalue_To_Rvalue, ///< Lvalue-to-rvalue conversion (C++ 4.1)
63 ICK_Array_To_Pointer, ///< Array-to-pointer conversion (C++ 4.2)
64 ICK_Function_To_Pointer, ///< Function-to-pointer (C++ 4.3)
65 ICK_Function_Conversion, ///< Function pointer conversion (C++17 4.13)
66 ICK_Qualification, ///< Qualification conversions (C++ 4.4)
67 ICK_Integral_Promotion, ///< Integral promotions (C++ 4.5)
68 ICK_Floating_Promotion, ///< Floating point promotions (C++ 4.6)
69 ICK_Complex_Promotion, ///< Complex promotions (Clang extension)
70 ICK_Integral_Conversion, ///< Integral conversions (C++ 4.7)
71 ICK_Floating_Conversion, ///< Floating point conversions (C++ 4.8)
72 ICK_Complex_Conversion, ///< Complex conversions (C99 6.3.1.6)
73 ICK_Floating_Integral, ///< Floating-integral conversions (C++ 4.9)
74 ICK_Pointer_Conversion, ///< Pointer conversions (C++ 4.10)
75 ICK_Pointer_Member, ///< Pointer-to-member conversions (C++ 4.11)
76 ICK_Boolean_Conversion, ///< Boolean conversions (C++ 4.12)
77 ICK_Compatible_Conversion, ///< Conversions between compatible types in C99
78 ICK_Derived_To_Base, ///< Derived-to-base (C++ [over.best.ics])
79 ICK_Vector_Conversion, ///< Vector conversions
80 ICK_Vector_Splat, ///< A vector splat from an arithmetic type
81 ICK_Complex_Real, ///< Complex-real conversions (C99 6.3.1.7)
82 ICK_Block_Pointer_Conversion, ///< Block Pointer conversions
83 ICK_TransparentUnionConversion, ///< Transparent Union Conversions
84 ICK_Writeback_Conversion, ///< Objective-C ARC writeback conversion
85 ICK_Zero_Event_Conversion, ///< Zero constant to event (OpenCL1.2 6.12.10)
86 ICK_Zero_Queue_Conversion, ///< Zero constant to queue
87 ICK_C_Only_Conversion, ///< Conversions allowed in C, but not C++
88 ICK_Incompatible_Pointer_Conversion, ///< C-only conversion between pointers
89 /// with incompatible types
90 ICK_Num_Conversion_Kinds, ///< The number of conversion kinds
93 /// ImplicitConversionRank - The rank of an implicit conversion
94 /// kind. The enumerator values match with Table 9 of (C++
95 /// 13.3.3.1.1) and are listed such that better conversion ranks
96 /// have smaller values.
97 enum ImplicitConversionRank {
98 ICR_Exact_Match = 0, ///< Exact Match
99 ICR_Promotion, ///< Promotion
100 ICR_Conversion, ///< Conversion
101 ICR_Complex_Real_Conversion, ///< Complex <-> Real conversion
102 ICR_Writeback_Conversion, ///< ObjC ARC writeback conversion
103 ICR_C_Conversion, ///< Conversion only allowed in the C standard.
104 /// (e.g. void* to char*)
105 ICR_C_Conversion_Extension ///< Conversion not allowed by the C standard,
106 /// but that we accept as an extension anyway.
109 ImplicitConversionRank GetConversionRank(ImplicitConversionKind Kind);
111 /// NarrowingKind - The kind of narrowing conversion being performed by a
112 /// standard conversion sequence according to C++11 [dcl.init.list]p7.
114 /// Not a narrowing conversion.
117 /// A narrowing conversion by virtue of the source and destination types.
120 /// A narrowing conversion, because a constant expression got narrowed.
121 NK_Constant_Narrowing,
123 /// A narrowing conversion, because a non-constant-expression variable might
124 /// have got narrowed.
125 NK_Variable_Narrowing,
127 /// Cannot tell whether this is a narrowing conversion because the
128 /// expression is value-dependent.
129 NK_Dependent_Narrowing,
132 /// StandardConversionSequence - represents a standard conversion
133 /// sequence (C++ 13.3.3.1.1). A standard conversion sequence
134 /// contains between zero and three conversions. If a particular
135 /// conversion is not needed, it will be set to the identity conversion
136 /// (ICK_Identity). Note that the three conversions are
137 /// specified as separate members (rather than in an array) so that
138 /// we can keep the size of a standard conversion sequence to a
140 class StandardConversionSequence {
142 /// First -- The first conversion can be an lvalue-to-rvalue
143 /// conversion, array-to-pointer conversion, or
144 /// function-to-pointer conversion.
145 ImplicitConversionKind First : 8;
147 /// Second - The second conversion can be an integral promotion,
148 /// floating point promotion, integral conversion, floating point
149 /// conversion, floating-integral conversion, pointer conversion,
150 /// pointer-to-member conversion, or boolean conversion.
151 ImplicitConversionKind Second : 8;
153 /// Third - The third conversion can be a qualification conversion
154 /// or a function conversion.
155 ImplicitConversionKind Third : 8;
157 /// \brief Whether this is the deprecated conversion of a
158 /// string literal to a pointer to non-const character data
160 unsigned DeprecatedStringLiteralToCharPtr : 1;
162 /// \brief Whether the qualification conversion involves a change in the
163 /// Objective-C lifetime (for automatic reference counting).
164 unsigned QualificationIncludesObjCLifetime : 1;
166 /// IncompatibleObjC - Whether this is an Objective-C conversion
167 /// that we should warn about (if we actually use it).
168 unsigned IncompatibleObjC : 1;
170 /// ReferenceBinding - True when this is a reference binding
171 /// (C++ [over.ics.ref]).
172 unsigned ReferenceBinding : 1;
174 /// DirectBinding - True when this is a reference binding that is a
175 /// direct binding (C++ [dcl.init.ref]).
176 unsigned DirectBinding : 1;
178 /// \brief Whether this is an lvalue reference binding (otherwise, it's
179 /// an rvalue reference binding).
180 unsigned IsLvalueReference : 1;
182 /// \brief Whether we're binding to a function lvalue.
183 unsigned BindsToFunctionLvalue : 1;
185 /// \brief Whether we're binding to an rvalue.
186 unsigned BindsToRvalue : 1;
188 /// \brief Whether this binds an implicit object argument to a
189 /// non-static member function without a ref-qualifier.
190 unsigned BindsImplicitObjectArgumentWithoutRefQualifier : 1;
192 /// \brief Whether this binds a reference to an object with a different
193 /// Objective-C lifetime qualifier.
194 unsigned ObjCLifetimeConversionBinding : 1;
196 /// FromType - The type that this conversion is converting
197 /// from. This is an opaque pointer that can be translated into a
201 /// ToType - The types that this conversion is converting to in
202 /// each step. This is an opaque pointer that can be translated
206 /// CopyConstructor - The copy constructor that is used to perform
207 /// this conversion, when the conversion is actually just the
208 /// initialization of an object via copy constructor. Such
209 /// conversions are either identity conversions or derived-to-base
211 CXXConstructorDecl *CopyConstructor;
212 DeclAccessPair FoundCopyConstructor;
214 void setFromType(QualType T) { FromTypePtr = T.getAsOpaquePtr(); }
215 void setToType(unsigned Idx, QualType T) {
216 assert(Idx < 3 && "To type index is out of range");
217 ToTypePtrs[Idx] = T.getAsOpaquePtr();
219 void setAllToTypes(QualType T) {
220 ToTypePtrs[0] = T.getAsOpaquePtr();
221 ToTypePtrs[1] = ToTypePtrs[0];
222 ToTypePtrs[2] = ToTypePtrs[0];
225 QualType getFromType() const {
226 return QualType::getFromOpaquePtr(FromTypePtr);
228 QualType getToType(unsigned Idx) const {
229 assert(Idx < 3 && "To type index is out of range");
230 return QualType::getFromOpaquePtr(ToTypePtrs[Idx]);
233 void setAsIdentityConversion();
235 bool isIdentityConversion() const {
236 return Second == ICK_Identity && Third == ICK_Identity;
239 ImplicitConversionRank getRank() const;
240 NarrowingKind getNarrowingKind(ASTContext &Context, const Expr *Converted,
241 APValue &ConstantValue,
242 QualType &ConstantType) const;
243 bool isPointerConversionToBool() const;
244 bool isPointerConversionToVoidPointer(ASTContext& Context) const;
248 /// UserDefinedConversionSequence - Represents a user-defined
249 /// conversion sequence (C++ 13.3.3.1.2).
250 struct UserDefinedConversionSequence {
251 /// \brief Represents the standard conversion that occurs before
252 /// the actual user-defined conversion.
254 /// C++11 13.3.3.1.2p1:
255 /// If the user-defined conversion is specified by a constructor
256 /// (12.3.1), the initial standard conversion sequence converts
257 /// the source type to the type required by the argument of the
258 /// constructor. If the user-defined conversion is specified by
259 /// a conversion function (12.3.2), the initial standard
260 /// conversion sequence converts the source type to the implicit
261 /// object parameter of the conversion function.
262 StandardConversionSequence Before;
264 /// EllipsisConversion - When this is true, it means user-defined
265 /// conversion sequence starts with a ... (ellipsis) conversion, instead of
266 /// a standard conversion. In this case, 'Before' field must be ignored.
267 // FIXME. I much rather put this as the first field. But there seems to be
268 // a gcc code gen. bug which causes a crash in a test. Putting it here seems
269 // to work around the crash.
270 bool EllipsisConversion : 1;
272 /// HadMultipleCandidates - When this is true, it means that the
273 /// conversion function was resolved from an overloaded set having
274 /// size greater than 1.
275 bool HadMultipleCandidates : 1;
277 /// After - Represents the standard conversion that occurs after
278 /// the actual user-defined conversion.
279 StandardConversionSequence After;
281 /// ConversionFunction - The function that will perform the
282 /// user-defined conversion. Null if the conversion is an
283 /// aggregate initialization from an initializer list.
284 FunctionDecl* ConversionFunction;
286 /// \brief The declaration that we found via name lookup, which might be
287 /// the same as \c ConversionFunction or it might be a using declaration
288 /// that refers to \c ConversionFunction.
289 DeclAccessPair FoundConversionFunction;
294 /// Represents an ambiguous user-defined conversion sequence.
295 struct AmbiguousConversionSequence {
296 typedef SmallVector<std::pair<NamedDecl*, FunctionDecl*>, 4> ConversionSet;
300 char Buffer[sizeof(ConversionSet)];
302 QualType getFromType() const {
303 return QualType::getFromOpaquePtr(FromTypePtr);
305 QualType getToType() const {
306 return QualType::getFromOpaquePtr(ToTypePtr);
308 void setFromType(QualType T) { FromTypePtr = T.getAsOpaquePtr(); }
309 void setToType(QualType T) { ToTypePtr = T.getAsOpaquePtr(); }
311 ConversionSet &conversions() {
312 return *reinterpret_cast<ConversionSet*>(Buffer);
315 const ConversionSet &conversions() const {
316 return *reinterpret_cast<const ConversionSet*>(Buffer);
319 void addConversion(NamedDecl *Found, FunctionDecl *D) {
320 conversions().push_back(std::make_pair(Found, D));
323 typedef ConversionSet::iterator iterator;
324 iterator begin() { return conversions().begin(); }
325 iterator end() { return conversions().end(); }
327 typedef ConversionSet::const_iterator const_iterator;
328 const_iterator begin() const { return conversions().begin(); }
329 const_iterator end() const { return conversions().end(); }
333 void copyFrom(const AmbiguousConversionSequence &);
336 /// BadConversionSequence - Records information about an invalid
337 /// conversion sequence.
338 struct BadConversionSequence {
343 lvalue_ref_to_rvalue,
347 // This can be null, e.g. for implicit object arguments.
353 // The type we're converting from (an opaque QualType).
356 // The type we're converting to (an opaque QualType).
360 void init(FailureKind K, Expr *From, QualType To) {
361 init(K, From->getType(), To);
364 void init(FailureKind K, QualType From, QualType To) {
371 QualType getFromType() const { return QualType::getFromOpaquePtr(FromTy); }
372 QualType getToType() const { return QualType::getFromOpaquePtr(ToTy); }
374 void setFromExpr(Expr *E) {
376 setFromType(E->getType());
378 void setFromType(QualType T) { FromTy = T.getAsOpaquePtr(); }
379 void setToType(QualType T) { ToTy = T.getAsOpaquePtr(); }
382 /// ImplicitConversionSequence - Represents an implicit conversion
383 /// sequence, which may be a standard conversion sequence
384 /// (C++ 13.3.3.1.1), user-defined conversion sequence (C++ 13.3.3.1.2),
385 /// or an ellipsis conversion sequence (C++ 13.3.3.1.3).
386 class ImplicitConversionSequence {
388 /// Kind - The kind of implicit conversion sequence. BadConversion
389 /// specifies that there is no conversion from the source type to
390 /// the target type. AmbiguousConversion represents the unique
391 /// ambiguous conversion (C++0x [over.best.ics]p10).
393 StandardConversion = 0,
394 UserDefinedConversion,
402 Uninitialized = BadConversion + 1
405 /// ConversionKind - The kind of implicit conversion sequence.
406 unsigned ConversionKind : 30;
408 /// \brief Whether the target is really a std::initializer_list, and the
409 /// sequence only represents the worst element conversion.
410 unsigned StdInitializerListElement : 1;
412 void setKind(Kind K) {
418 if (ConversionKind == AmbiguousConversion) Ambiguous.destruct();
423 /// When ConversionKind == StandardConversion, provides the
424 /// details of the standard conversion sequence.
425 StandardConversionSequence Standard;
427 /// When ConversionKind == UserDefinedConversion, provides the
428 /// details of the user-defined conversion sequence.
429 UserDefinedConversionSequence UserDefined;
431 /// When ConversionKind == AmbiguousConversion, provides the
432 /// details of the ambiguous conversion.
433 AmbiguousConversionSequence Ambiguous;
435 /// When ConversionKind == BadConversion, provides the details
436 /// of the bad conversion.
437 BadConversionSequence Bad;
440 ImplicitConversionSequence()
441 : ConversionKind(Uninitialized), StdInitializerListElement(false) {
442 Standard.setAsIdentityConversion();
444 ~ImplicitConversionSequence() {
447 ImplicitConversionSequence(const ImplicitConversionSequence &Other)
448 : ConversionKind(Other.ConversionKind),
449 StdInitializerListElement(Other.StdInitializerListElement)
451 switch (ConversionKind) {
452 case Uninitialized: break;
453 case StandardConversion: Standard = Other.Standard; break;
454 case UserDefinedConversion: UserDefined = Other.UserDefined; break;
455 case AmbiguousConversion: Ambiguous.copyFrom(Other.Ambiguous); break;
456 case EllipsisConversion: break;
457 case BadConversion: Bad = Other.Bad; break;
461 ImplicitConversionSequence &
462 operator=(const ImplicitConversionSequence &Other) {
464 new (this) ImplicitConversionSequence(Other);
468 Kind getKind() const {
469 assert(isInitialized() && "querying uninitialized conversion");
470 return Kind(ConversionKind);
473 /// \brief Return a ranking of the implicit conversion sequence
474 /// kind, where smaller ranks represent better conversion
477 /// In particular, this routine gives user-defined conversion
478 /// sequences and ambiguous conversion sequences the same rank,
479 /// per C++ [over.best.ics]p10.
480 unsigned getKindRank() const {
482 case StandardConversion:
485 case UserDefinedConversion:
486 case AmbiguousConversion:
489 case EllipsisConversion:
496 llvm_unreachable("Invalid ImplicitConversionSequence::Kind!");
499 bool isBad() const { return getKind() == BadConversion; }
500 bool isStandard() const { return getKind() == StandardConversion; }
501 bool isEllipsis() const { return getKind() == EllipsisConversion; }
502 bool isAmbiguous() const { return getKind() == AmbiguousConversion; }
503 bool isUserDefined() const { return getKind() == UserDefinedConversion; }
504 bool isFailure() const { return isBad() || isAmbiguous(); }
506 /// Determines whether this conversion sequence has been
507 /// initialized. Most operations should never need to query
508 /// uninitialized conversions and should assert as above.
509 bool isInitialized() const { return ConversionKind != Uninitialized; }
511 /// Sets this sequence as a bad conversion for an explicit argument.
512 void setBad(BadConversionSequence::FailureKind Failure,
513 Expr *FromExpr, QualType ToType) {
514 setKind(BadConversion);
515 Bad.init(Failure, FromExpr, ToType);
518 /// Sets this sequence as a bad conversion for an implicit argument.
519 void setBad(BadConversionSequence::FailureKind Failure,
520 QualType FromType, QualType ToType) {
521 setKind(BadConversion);
522 Bad.init(Failure, FromType, ToType);
525 void setStandard() { setKind(StandardConversion); }
526 void setEllipsis() { setKind(EllipsisConversion); }
527 void setUserDefined() { setKind(UserDefinedConversion); }
528 void setAmbiguous() {
529 if (ConversionKind == AmbiguousConversion) return;
530 ConversionKind = AmbiguousConversion;
531 Ambiguous.construct();
534 /// \brief Whether the target is really a std::initializer_list, and the
535 /// sequence only represents the worst element conversion.
536 bool isStdInitializerListElement() const {
537 return StdInitializerListElement;
540 void setStdInitializerListElement(bool V = true) {
541 StdInitializerListElement = V;
544 // The result of a comparison between implicit conversion
545 // sequences. Use Sema::CompareImplicitConversionSequences to
546 // actually perform the comparison.
549 Indistinguishable = 0,
553 void DiagnoseAmbiguousConversion(Sema &S,
554 SourceLocation CaretLoc,
555 const PartialDiagnostic &PDiag) const;
560 enum OverloadFailureKind {
561 ovl_fail_too_many_arguments,
562 ovl_fail_too_few_arguments,
563 ovl_fail_bad_conversion,
564 ovl_fail_bad_deduction,
566 /// This conversion candidate was not considered because it
567 /// duplicates the work of a trivial or derived-to-base
569 ovl_fail_trivial_conversion,
571 /// This conversion candidate was not considered because it is
572 /// an illegal instantiation of a constructor temploid: it is
573 /// callable with one argument, we only have one argument, and
574 /// its first parameter type is exactly the type of the class.
576 /// Defining such a constructor directly is illegal, and
577 /// template-argument deduction is supposed to ignore such
578 /// instantiations, but we can still get one with the right
579 /// kind of implicit instantiation.
580 ovl_fail_illegal_constructor,
582 /// This conversion candidate is not viable because its result
583 /// type is not implicitly convertible to the desired type.
584 ovl_fail_bad_final_conversion,
586 /// This conversion function template specialization candidate is not
587 /// viable because the final conversion was not an exact match.
588 ovl_fail_final_conversion_not_exact,
590 /// (CUDA) This candidate was not viable because the callee
591 /// was not accessible from the caller's target (i.e. host->device,
592 /// global->host, device->host).
595 /// This candidate function was not viable because an enable_if
596 /// attribute disabled it.
599 /// This candidate was not viable because its address could not be taken.
600 ovl_fail_addr_not_available,
602 /// This candidate was not viable because its OpenCL extension is disabled.
603 ovl_fail_ext_disabled,
606 /// OverloadCandidate - A single candidate in an overload set (C++ 13.3).
607 struct OverloadCandidate {
608 /// Function - The actual function that this candidate
609 /// represents. When NULL, this is a built-in candidate
610 /// (C++ [over.oper]) or a surrogate for a conversion to a
611 /// function pointer or reference (C++ [over.call.object]).
612 FunctionDecl *Function;
614 /// FoundDecl - The original declaration that was looked up /
615 /// invented / otherwise found, together with its access.
616 /// Might be a UsingShadowDecl or a FunctionTemplateDecl.
617 DeclAccessPair FoundDecl;
619 // BuiltinTypes - Provides the return and parameter types of a
620 // built-in overload candidate. Only valid when Function is NULL.
623 QualType ParamTypes[3];
626 /// Surrogate - The conversion function for which this candidate
627 /// is a surrogate, but only if IsSurrogate is true.
628 CXXConversionDecl *Surrogate;
630 /// Conversions - The conversion sequences used to convert the
631 /// function arguments to the function parameters, the pointer points to a
632 /// fixed size array with NumConversions elements. The memory is owned by
633 /// the OverloadCandidateSet.
634 ImplicitConversionSequence *Conversions;
636 /// The FixIt hints which can be used to fix the Bad candidate.
637 ConversionFixItGenerator Fix;
639 /// NumConversions - The number of elements in the Conversions array.
640 unsigned NumConversions;
642 /// Viable - True to indicate that this overload candidate is viable.
645 /// IsSurrogate - True to indicate that this candidate is a
646 /// surrogate for a conversion to a function pointer or reference
647 /// (C++ [over.call.object]).
650 /// IgnoreObjectArgument - True to indicate that the first
651 /// argument's conversion, which for this function represents the
652 /// implicit object argument, should be ignored. This will be true
653 /// when the candidate is a static member function (where the
654 /// implicit object argument is just a placeholder) or a
655 /// non-static member function when the call doesn't have an
657 bool IgnoreObjectArgument;
659 /// FailureKind - The reason why this candidate is not viable.
660 /// Actually an OverloadFailureKind.
661 unsigned char FailureKind;
663 /// \brief The number of call arguments that were explicitly provided,
664 /// to be used while performing partial ordering of function templates.
665 unsigned ExplicitCallArguments;
668 DeductionFailureInfo DeductionFailure;
670 /// FinalConversion - For a conversion function (where Function is
671 /// a CXXConversionDecl), the standard conversion that occurs
672 /// after the call to the overload candidate to convert the result
673 /// of calling the conversion function to the required type.
674 StandardConversionSequence FinalConversion;
677 /// hasAmbiguousConversion - Returns whether this overload
678 /// candidate requires an ambiguous conversion or not.
679 bool hasAmbiguousConversion() const {
680 for (unsigned i = 0, e = NumConversions; i != e; ++i) {
681 if (!Conversions[i].isInitialized()) return false;
682 if (Conversions[i].isAmbiguous()) return true;
687 bool TryToFixBadConversion(unsigned Idx, Sema &S) {
688 bool CanFix = Fix.tryToFixConversion(
689 Conversions[Idx].Bad.FromExpr,
690 Conversions[Idx].Bad.getFromType(),
691 Conversions[Idx].Bad.getToType(), S);
693 // If at least one conversion fails, the candidate cannot be fixed.
700 unsigned getNumParams() const {
702 auto STy = Surrogate->getConversionType();
703 while (STy->isPointerType() || STy->isReferenceType())
704 STy = STy->getPointeeType();
705 return STy->getAs<FunctionProtoType>()->getNumParams();
708 return Function->getNumParams();
709 return ExplicitCallArguments;
713 /// OverloadCandidateSet - A set of overload candidates, used in C++
714 /// overload resolution (C++ 13.3).
715 class OverloadCandidateSet {
717 enum CandidateSetKind {
720 /// Lookup for candidates for a call using operator syntax. Candidates
721 /// that have no parameters of class type will be skipped unless there
722 /// is a parameter of (reference to) enum type and the corresponding
723 /// argument is of the same enum type.
728 SmallVector<OverloadCandidate, 16> Candidates;
729 llvm::SmallPtrSet<Decl *, 16> Functions;
731 // Allocator for OverloadCandidate::Conversions. We store the first few
732 // elements inline to avoid allocation for small sets.
733 llvm::BumpPtrAllocator ConversionSequenceAllocator;
736 CandidateSetKind Kind;
738 unsigned NumInlineSequences;
739 llvm::AlignedCharArray<alignof(ImplicitConversionSequence),
740 16 * sizeof(ImplicitConversionSequence)>
743 OverloadCandidateSet(const OverloadCandidateSet &) = delete;
744 void operator=(const OverloadCandidateSet &) = delete;
746 void destroyCandidates();
749 OverloadCandidateSet(SourceLocation Loc, CandidateSetKind CSK)
750 : Loc(Loc), Kind(CSK), NumInlineSequences(0) {}
751 ~OverloadCandidateSet() { destroyCandidates(); }
753 SourceLocation getLocation() const { return Loc; }
754 CandidateSetKind getKind() const { return Kind; }
756 /// \brief Determine when this overload candidate will be new to the
758 bool isNewCandidate(Decl *F) {
759 return Functions.insert(F->getCanonicalDecl()).second;
762 /// \brief Clear out all of the candidates.
765 typedef SmallVectorImpl<OverloadCandidate>::iterator iterator;
766 iterator begin() { return Candidates.begin(); }
767 iterator end() { return Candidates.end(); }
769 size_t size() const { return Candidates.size(); }
770 bool empty() const { return Candidates.empty(); }
772 /// \brief Add a new candidate with NumConversions conversion sequence slots
773 /// to the overload set.
774 OverloadCandidate &addCandidate(unsigned NumConversions = 0) {
775 Candidates.push_back(OverloadCandidate());
776 OverloadCandidate &C = Candidates.back();
778 // Assign space from the inline array if there are enough free slots
780 if (NumConversions + NumInlineSequences <= 16) {
781 ImplicitConversionSequence *I =
782 (ImplicitConversionSequence *)InlineSpace.buffer;
783 C.Conversions = &I[NumInlineSequences];
784 NumInlineSequences += NumConversions;
786 // Otherwise get memory from the allocator.
787 C.Conversions = ConversionSequenceAllocator
788 .Allocate<ImplicitConversionSequence>(NumConversions);
791 // Construct the new objects.
792 for (unsigned i = 0; i != NumConversions; ++i)
793 new (&C.Conversions[i]) ImplicitConversionSequence();
795 C.NumConversions = NumConversions;
799 /// Find the best viable function on this overload set, if it exists.
800 OverloadingResult BestViableFunction(Sema &S, SourceLocation Loc,
801 OverloadCandidateSet::iterator& Best,
802 bool UserDefinedConversion = false);
804 void NoteCandidates(Sema &S,
805 OverloadCandidateDisplayKind OCD,
806 ArrayRef<Expr *> Args,
808 SourceLocation Loc = SourceLocation(),
809 llvm::function_ref<bool(OverloadCandidate&)> Filter =
810 [](OverloadCandidate&) { return true; });
813 bool isBetterOverloadCandidate(Sema &S,
814 const OverloadCandidate& Cand1,
815 const OverloadCandidate& Cand2,
817 bool UserDefinedConversion = false);
819 struct ConstructorInfo {
820 DeclAccessPair FoundDecl;
821 CXXConstructorDecl *Constructor;
822 FunctionTemplateDecl *ConstructorTmpl;
823 explicit operator bool() const { return Constructor; }
825 // FIXME: Add an AddOverloadCandidate / AddTemplateOverloadCandidate overload
826 // that takes one of these.
827 inline ConstructorInfo getConstructorInfo(NamedDecl *ND) {
828 if (isa<UsingDecl>(ND))
829 return ConstructorInfo{};
831 // For constructors, the access check is performed against the underlying
832 // declaration, not the found declaration.
833 auto *D = ND->getUnderlyingDecl();
834 ConstructorInfo Info = {DeclAccessPair::make(ND, D->getAccess()), nullptr,
836 Info.ConstructorTmpl = dyn_cast<FunctionTemplateDecl>(D);
837 if (Info.ConstructorTmpl)
838 D = Info.ConstructorTmpl->getTemplatedDecl();
839 Info.Constructor = dyn_cast<CXXConstructorDecl>(D);
842 } // end namespace clang
844 #endif // LLVM_CLANG_SEMA_OVERLOAD_H