1 //===- Overload.h - C++ Overloading -----------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file defines the data structures and types used in C++ 10 // overload resolution. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_CLANG_SEMA_OVERLOAD_H 15 #define LLVM_CLANG_SEMA_OVERLOAD_H 16 17 #include "clang/AST/Decl.h" 18 #include "clang/AST/DeclAccessPair.h" 19 #include "clang/AST/DeclBase.h" 20 #include "clang/AST/DeclCXX.h" 21 #include "clang/AST/DeclTemplate.h" 22 #include "clang/AST/Expr.h" 23 #include "clang/AST/Type.h" 24 #include "clang/Basic/LLVM.h" 25 #include "clang/Basic/SourceLocation.h" 26 #include "clang/Sema/SemaFixItUtils.h" 27 #include "clang/Sema/TemplateDeduction.h" 28 #include "llvm/ADT/ArrayRef.h" 29 #include "llvm/ADT/None.h" 30 #include "llvm/ADT/STLExtras.h" 31 #include "llvm/ADT/SmallPtrSet.h" 32 #include "llvm/ADT/SmallVector.h" 33 #include "llvm/ADT/StringRef.h" 34 #include "llvm/Support/AlignOf.h" 35 #include "llvm/Support/Allocator.h" 36 #include "llvm/Support/Casting.h" 37 #include "llvm/Support/ErrorHandling.h" 38 #include <cassert> 39 #include <cstddef> 40 #include <cstdint> 41 #include <utility> 42 43 namespace clang { 44 45 class APValue; 46 class ASTContext; 47 class Sema; 48 49 /// OverloadingResult - Capture the result of performing overload 50 /// resolution. 51 enum OverloadingResult { 52 /// Overload resolution succeeded. 53 OR_Success, 54 55 /// No viable function found. 56 OR_No_Viable_Function, 57 58 /// Ambiguous candidates found. 59 OR_Ambiguous, 60 61 /// Succeeded, but refers to a deleted function. 62 OR_Deleted 63 }; 64 65 enum OverloadCandidateDisplayKind { 66 /// Requests that all candidates be shown. Viable candidates will 67 /// be printed first. 68 OCD_AllCandidates, 69 70 /// Requests that only viable candidates be shown. 71 OCD_ViableCandidates, 72 73 /// Requests that only tied-for-best candidates be shown. 74 OCD_AmbiguousCandidates 75 }; 76 77 /// The parameter ordering that will be used for the candidate. This is 78 /// used to represent C++20 binary operator rewrites that reverse the order 79 /// of the arguments. If the parameter ordering is Reversed, the Args list is 80 /// reversed (but obviously the ParamDecls for the function are not). 81 /// 82 /// After forming an OverloadCandidate with reversed parameters, the list 83 /// of conversions will (as always) be indexed by argument, so will be 84 /// in reverse parameter order. 85 enum class OverloadCandidateParamOrder : char { Normal, Reversed }; 86 87 /// The kinds of rewrite we perform on overload candidates. Note that the 88 /// values here are chosen to serve as both bitflags and as a rank (lower 89 /// values are preferred by overload resolution). 90 enum OverloadCandidateRewriteKind : unsigned { 91 /// Candidate is not a rewritten candidate. 92 CRK_None = 0x0, 93 94 /// Candidate is a rewritten candidate with a different operator name. 95 CRK_DifferentOperator = 0x1, 96 97 /// Candidate is a rewritten candidate with a reversed order of parameters. 98 CRK_Reversed = 0x2, 99 }; 100 101 /// ImplicitConversionKind - The kind of implicit conversion used to 102 /// convert an argument to a parameter's type. The enumerator values 103 /// match with the table titled 'Conversions' in [over.ics.scs] and are listed 104 /// such that better conversion kinds have smaller values. 105 enum ImplicitConversionKind { 106 /// Identity conversion (no conversion) 107 ICK_Identity = 0, 108 109 /// Lvalue-to-rvalue conversion (C++ [conv.lval]) 110 ICK_Lvalue_To_Rvalue, 111 112 /// Array-to-pointer conversion (C++ [conv.array]) 113 ICK_Array_To_Pointer, 114 115 /// Function-to-pointer (C++ [conv.array]) 116 ICK_Function_To_Pointer, 117 118 /// Function pointer conversion (C++17 [conv.fctptr]) 119 ICK_Function_Conversion, 120 121 /// Qualification conversions (C++ [conv.qual]) 122 ICK_Qualification, 123 124 /// Integral promotions (C++ [conv.prom]) 125 ICK_Integral_Promotion, 126 127 /// Floating point promotions (C++ [conv.fpprom]) 128 ICK_Floating_Promotion, 129 130 /// Complex promotions (Clang extension) 131 ICK_Complex_Promotion, 132 133 /// Integral conversions (C++ [conv.integral]) 134 ICK_Integral_Conversion, 135 136 /// Floating point conversions (C++ [conv.double] 137 ICK_Floating_Conversion, 138 139 /// Complex conversions (C99 6.3.1.6) 140 ICK_Complex_Conversion, 141 142 /// Floating-integral conversions (C++ [conv.fpint]) 143 ICK_Floating_Integral, 144 145 /// Pointer conversions (C++ [conv.ptr]) 146 ICK_Pointer_Conversion, 147 148 /// Pointer-to-member conversions (C++ [conv.mem]) 149 ICK_Pointer_Member, 150 151 /// Boolean conversions (C++ [conv.bool]) 152 ICK_Boolean_Conversion, 153 154 /// Conversions between compatible types in C99 155 ICK_Compatible_Conversion, 156 157 /// Derived-to-base (C++ [over.best.ics]) 158 ICK_Derived_To_Base, 159 160 /// Vector conversions 161 ICK_Vector_Conversion, 162 163 /// A vector splat from an arithmetic type 164 ICK_Vector_Splat, 165 166 /// Complex-real conversions (C99 6.3.1.7) 167 ICK_Complex_Real, 168 169 /// Block Pointer conversions 170 ICK_Block_Pointer_Conversion, 171 172 /// Transparent Union Conversions 173 ICK_TransparentUnionConversion, 174 175 /// Objective-C ARC writeback conversion 176 ICK_Writeback_Conversion, 177 178 /// Zero constant to event (OpenCL1.2 6.12.10) 179 ICK_Zero_Event_Conversion, 180 181 /// Zero constant to queue 182 ICK_Zero_Queue_Conversion, 183 184 /// Conversions allowed in C, but not C++ 185 ICK_C_Only_Conversion, 186 187 /// C-only conversion between pointers with incompatible types 188 ICK_Incompatible_Pointer_Conversion, 189 190 /// The number of conversion kinds 191 ICK_Num_Conversion_Kinds, 192 }; 193 194 /// ImplicitConversionRank - The rank of an implicit conversion 195 /// kind. The enumerator values match with Table 9 of (C++ 196 /// 13.3.3.1.1) and are listed such that better conversion ranks 197 /// have smaller values. 198 enum ImplicitConversionRank { 199 /// Exact Match 200 ICR_Exact_Match = 0, 201 202 /// Promotion 203 ICR_Promotion, 204 205 /// Conversion 206 ICR_Conversion, 207 208 /// OpenCL Scalar Widening 209 ICR_OCL_Scalar_Widening, 210 211 /// Complex <-> Real conversion 212 ICR_Complex_Real_Conversion, 213 214 /// ObjC ARC writeback conversion 215 ICR_Writeback_Conversion, 216 217 /// Conversion only allowed in the C standard (e.g. void* to char*). 218 ICR_C_Conversion, 219 220 /// Conversion not allowed by the C standard, but that we accept as an 221 /// extension anyway. 222 ICR_C_Conversion_Extension 223 }; 224 225 ImplicitConversionRank GetConversionRank(ImplicitConversionKind Kind); 226 227 /// NarrowingKind - The kind of narrowing conversion being performed by a 228 /// standard conversion sequence according to C++11 [dcl.init.list]p7. 229 enum NarrowingKind { 230 /// Not a narrowing conversion. 231 NK_Not_Narrowing, 232 233 /// A narrowing conversion by virtue of the source and destination types. 234 NK_Type_Narrowing, 235 236 /// A narrowing conversion, because a constant expression got narrowed. 237 NK_Constant_Narrowing, 238 239 /// A narrowing conversion, because a non-constant-expression variable might 240 /// have got narrowed. 241 NK_Variable_Narrowing, 242 243 /// Cannot tell whether this is a narrowing conversion because the 244 /// expression is value-dependent. 245 NK_Dependent_Narrowing, 246 }; 247 248 /// StandardConversionSequence - represents a standard conversion 249 /// sequence (C++ 13.3.3.1.1). A standard conversion sequence 250 /// contains between zero and three conversions. If a particular 251 /// conversion is not needed, it will be set to the identity conversion 252 /// (ICK_Identity). Note that the three conversions are 253 /// specified as separate members (rather than in an array) so that 254 /// we can keep the size of a standard conversion sequence to a 255 /// single word. 256 class StandardConversionSequence { 257 public: 258 /// First -- The first conversion can be an lvalue-to-rvalue 259 /// conversion, array-to-pointer conversion, or 260 /// function-to-pointer conversion. 261 ImplicitConversionKind First : 8; 262 263 /// Second - The second conversion can be an integral promotion, 264 /// floating point promotion, integral conversion, floating point 265 /// conversion, floating-integral conversion, pointer conversion, 266 /// pointer-to-member conversion, or boolean conversion. 267 ImplicitConversionKind Second : 8; 268 269 /// Third - The third conversion can be a qualification conversion 270 /// or a function conversion. 271 ImplicitConversionKind Third : 8; 272 273 /// Whether this is the deprecated conversion of a 274 /// string literal to a pointer to non-const character data 275 /// (C++ 4.2p2). 276 unsigned DeprecatedStringLiteralToCharPtr : 1; 277 278 /// Whether the qualification conversion involves a change in the 279 /// Objective-C lifetime (for automatic reference counting). 280 unsigned QualificationIncludesObjCLifetime : 1; 281 282 /// IncompatibleObjC - Whether this is an Objective-C conversion 283 /// that we should warn about (if we actually use it). 284 unsigned IncompatibleObjC : 1; 285 286 /// ReferenceBinding - True when this is a reference binding 287 /// (C++ [over.ics.ref]). 288 unsigned ReferenceBinding : 1; 289 290 /// DirectBinding - True when this is a reference binding that is a 291 /// direct binding (C++ [dcl.init.ref]). 292 unsigned DirectBinding : 1; 293 294 /// Whether this is an lvalue reference binding (otherwise, it's 295 /// an rvalue reference binding). 296 unsigned IsLvalueReference : 1; 297 298 /// Whether we're binding to a function lvalue. 299 unsigned BindsToFunctionLvalue : 1; 300 301 /// Whether we're binding to an rvalue. 302 unsigned BindsToRvalue : 1; 303 304 /// Whether this binds an implicit object argument to a 305 /// non-static member function without a ref-qualifier. 306 unsigned BindsImplicitObjectArgumentWithoutRefQualifier : 1; 307 308 /// Whether this binds a reference to an object with a different 309 /// Objective-C lifetime qualifier. 310 unsigned ObjCLifetimeConversionBinding : 1; 311 312 /// FromType - The type that this conversion is converting 313 /// from. This is an opaque pointer that can be translated into a 314 /// QualType. 315 void *FromTypePtr; 316 317 /// ToType - The types that this conversion is converting to in 318 /// each step. This is an opaque pointer that can be translated 319 /// into a QualType. 320 void *ToTypePtrs[3]; 321 322 /// CopyConstructor - The copy constructor that is used to perform 323 /// this conversion, when the conversion is actually just the 324 /// initialization of an object via copy constructor. Such 325 /// conversions are either identity conversions or derived-to-base 326 /// conversions. 327 CXXConstructorDecl *CopyConstructor; 328 DeclAccessPair FoundCopyConstructor; 329 setFromType(QualType T)330 void setFromType(QualType T) { FromTypePtr = T.getAsOpaquePtr(); } 331 setToType(unsigned Idx,QualType T)332 void setToType(unsigned Idx, QualType T) { 333 assert(Idx < 3 && "To type index is out of range"); 334 ToTypePtrs[Idx] = T.getAsOpaquePtr(); 335 } 336 setAllToTypes(QualType T)337 void setAllToTypes(QualType T) { 338 ToTypePtrs[0] = T.getAsOpaquePtr(); 339 ToTypePtrs[1] = ToTypePtrs[0]; 340 ToTypePtrs[2] = ToTypePtrs[0]; 341 } 342 getFromType()343 QualType getFromType() const { 344 return QualType::getFromOpaquePtr(FromTypePtr); 345 } 346 getToType(unsigned Idx)347 QualType getToType(unsigned Idx) const { 348 assert(Idx < 3 && "To type index is out of range"); 349 return QualType::getFromOpaquePtr(ToTypePtrs[Idx]); 350 } 351 352 void setAsIdentityConversion(); 353 isIdentityConversion()354 bool isIdentityConversion() const { 355 return Second == ICK_Identity && Third == ICK_Identity; 356 } 357 358 ImplicitConversionRank getRank() const; 359 NarrowingKind 360 getNarrowingKind(ASTContext &Context, const Expr *Converted, 361 APValue &ConstantValue, QualType &ConstantType, 362 bool IgnoreFloatToIntegralConversion = false) const; 363 bool isPointerConversionToBool() const; 364 bool isPointerConversionToVoidPointer(ASTContext& Context) const; 365 void dump() const; 366 }; 367 368 /// UserDefinedConversionSequence - Represents a user-defined 369 /// conversion sequence (C++ 13.3.3.1.2). 370 struct UserDefinedConversionSequence { 371 /// Represents the standard conversion that occurs before 372 /// the actual user-defined conversion. 373 /// 374 /// C++11 13.3.3.1.2p1: 375 /// If the user-defined conversion is specified by a constructor 376 /// (12.3.1), the initial standard conversion sequence converts 377 /// the source type to the type required by the argument of the 378 /// constructor. If the user-defined conversion is specified by 379 /// a conversion function (12.3.2), the initial standard 380 /// conversion sequence converts the source type to the implicit 381 /// object parameter of the conversion function. 382 StandardConversionSequence Before; 383 384 /// EllipsisConversion - When this is true, it means user-defined 385 /// conversion sequence starts with a ... (ellipsis) conversion, instead of 386 /// a standard conversion. In this case, 'Before' field must be ignored. 387 // FIXME. I much rather put this as the first field. But there seems to be 388 // a gcc code gen. bug which causes a crash in a test. Putting it here seems 389 // to work around the crash. 390 bool EllipsisConversion : 1; 391 392 /// HadMultipleCandidates - When this is true, it means that the 393 /// conversion function was resolved from an overloaded set having 394 /// size greater than 1. 395 bool HadMultipleCandidates : 1; 396 397 /// After - Represents the standard conversion that occurs after 398 /// the actual user-defined conversion. 399 StandardConversionSequence After; 400 401 /// ConversionFunction - The function that will perform the 402 /// user-defined conversion. Null if the conversion is an 403 /// aggregate initialization from an initializer list. 404 FunctionDecl* ConversionFunction; 405 406 /// The declaration that we found via name lookup, which might be 407 /// the same as \c ConversionFunction or it might be a using declaration 408 /// that refers to \c ConversionFunction. 409 DeclAccessPair FoundConversionFunction; 410 411 void dump() const; 412 }; 413 414 /// Represents an ambiguous user-defined conversion sequence. 415 struct AmbiguousConversionSequence { 416 using ConversionSet = 417 SmallVector<std::pair<NamedDecl *, FunctionDecl *>, 4>; 418 419 void *FromTypePtr; 420 void *ToTypePtr; 421 char Buffer[sizeof(ConversionSet)]; 422 getFromTypeAmbiguousConversionSequence423 QualType getFromType() const { 424 return QualType::getFromOpaquePtr(FromTypePtr); 425 } 426 getToTypeAmbiguousConversionSequence427 QualType getToType() const { 428 return QualType::getFromOpaquePtr(ToTypePtr); 429 } 430 setFromTypeAmbiguousConversionSequence431 void setFromType(QualType T) { FromTypePtr = T.getAsOpaquePtr(); } setToTypeAmbiguousConversionSequence432 void setToType(QualType T) { ToTypePtr = T.getAsOpaquePtr(); } 433 conversionsAmbiguousConversionSequence434 ConversionSet &conversions() { 435 return *reinterpret_cast<ConversionSet*>(Buffer); 436 } 437 conversionsAmbiguousConversionSequence438 const ConversionSet &conversions() const { 439 return *reinterpret_cast<const ConversionSet*>(Buffer); 440 } 441 addConversionAmbiguousConversionSequence442 void addConversion(NamedDecl *Found, FunctionDecl *D) { 443 conversions().push_back(std::make_pair(Found, D)); 444 } 445 446 using iterator = ConversionSet::iterator; 447 beginAmbiguousConversionSequence448 iterator begin() { return conversions().begin(); } endAmbiguousConversionSequence449 iterator end() { return conversions().end(); } 450 451 using const_iterator = ConversionSet::const_iterator; 452 beginAmbiguousConversionSequence453 const_iterator begin() const { return conversions().begin(); } endAmbiguousConversionSequence454 const_iterator end() const { return conversions().end(); } 455 456 void construct(); 457 void destruct(); 458 void copyFrom(const AmbiguousConversionSequence &); 459 }; 460 461 /// BadConversionSequence - Records information about an invalid 462 /// conversion sequence. 463 struct BadConversionSequence { 464 enum FailureKind { 465 no_conversion, 466 unrelated_class, 467 bad_qualifiers, 468 lvalue_ref_to_rvalue, 469 rvalue_ref_to_lvalue 470 }; 471 472 // This can be null, e.g. for implicit object arguments. 473 Expr *FromExpr; 474 475 FailureKind Kind; 476 477 private: 478 // The type we're converting from (an opaque QualType). 479 void *FromTy; 480 481 // The type we're converting to (an opaque QualType). 482 void *ToTy; 483 484 public: initBadConversionSequence485 void init(FailureKind K, Expr *From, QualType To) { 486 init(K, From->getType(), To); 487 FromExpr = From; 488 } 489 initBadConversionSequence490 void init(FailureKind K, QualType From, QualType To) { 491 Kind = K; 492 FromExpr = nullptr; 493 setFromType(From); 494 setToType(To); 495 } 496 getFromTypeBadConversionSequence497 QualType getFromType() const { return QualType::getFromOpaquePtr(FromTy); } getToTypeBadConversionSequence498 QualType getToType() const { return QualType::getFromOpaquePtr(ToTy); } 499 setFromExprBadConversionSequence500 void setFromExpr(Expr *E) { 501 FromExpr = E; 502 setFromType(E->getType()); 503 } 504 setFromTypeBadConversionSequence505 void setFromType(QualType T) { FromTy = T.getAsOpaquePtr(); } setToTypeBadConversionSequence506 void setToType(QualType T) { ToTy = T.getAsOpaquePtr(); } 507 }; 508 509 /// ImplicitConversionSequence - Represents an implicit conversion 510 /// sequence, which may be a standard conversion sequence 511 /// (C++ 13.3.3.1.1), user-defined conversion sequence (C++ 13.3.3.1.2), 512 /// or an ellipsis conversion sequence (C++ 13.3.3.1.3). 513 class ImplicitConversionSequence { 514 public: 515 /// Kind - The kind of implicit conversion sequence. BadConversion 516 /// specifies that there is no conversion from the source type to 517 /// the target type. AmbiguousConversion represents the unique 518 /// ambiguous conversion (C++0x [over.best.ics]p10). 519 enum Kind { 520 StandardConversion = 0, 521 UserDefinedConversion, 522 AmbiguousConversion, 523 EllipsisConversion, 524 BadConversion 525 }; 526 527 private: 528 enum { 529 Uninitialized = BadConversion + 1 530 }; 531 532 /// ConversionKind - The kind of implicit conversion sequence. 533 unsigned ConversionKind : 30; 534 535 /// Whether the target is really a std::initializer_list, and the 536 /// sequence only represents the worst element conversion. 537 unsigned StdInitializerListElement : 1; 538 setKind(Kind K)539 void setKind(Kind K) { 540 destruct(); 541 ConversionKind = K; 542 } 543 destruct()544 void destruct() { 545 if (ConversionKind == AmbiguousConversion) Ambiguous.destruct(); 546 } 547 548 public: 549 union { 550 /// When ConversionKind == StandardConversion, provides the 551 /// details of the standard conversion sequence. 552 StandardConversionSequence Standard; 553 554 /// When ConversionKind == UserDefinedConversion, provides the 555 /// details of the user-defined conversion sequence. 556 UserDefinedConversionSequence UserDefined; 557 558 /// When ConversionKind == AmbiguousConversion, provides the 559 /// details of the ambiguous conversion. 560 AmbiguousConversionSequence Ambiguous; 561 562 /// When ConversionKind == BadConversion, provides the details 563 /// of the bad conversion. 564 BadConversionSequence Bad; 565 }; 566 ImplicitConversionSequence()567 ImplicitConversionSequence() 568 : ConversionKind(Uninitialized), StdInitializerListElement(false) { 569 Standard.setAsIdentityConversion(); 570 } 571 ImplicitConversionSequence(const ImplicitConversionSequence & Other)572 ImplicitConversionSequence(const ImplicitConversionSequence &Other) 573 : ConversionKind(Other.ConversionKind), 574 StdInitializerListElement(Other.StdInitializerListElement) { 575 switch (ConversionKind) { 576 case Uninitialized: break; 577 case StandardConversion: Standard = Other.Standard; break; 578 case UserDefinedConversion: UserDefined = Other.UserDefined; break; 579 case AmbiguousConversion: Ambiguous.copyFrom(Other.Ambiguous); break; 580 case EllipsisConversion: break; 581 case BadConversion: Bad = Other.Bad; break; 582 } 583 } 584 585 ImplicitConversionSequence & 586 operator=(const ImplicitConversionSequence &Other) { 587 destruct(); 588 new (this) ImplicitConversionSequence(Other); 589 return *this; 590 } 591 ~ImplicitConversionSequence()592 ~ImplicitConversionSequence() { 593 destruct(); 594 } 595 getKind()596 Kind getKind() const { 597 assert(isInitialized() && "querying uninitialized conversion"); 598 return Kind(ConversionKind); 599 } 600 601 /// Return a ranking of the implicit conversion sequence 602 /// kind, where smaller ranks represent better conversion 603 /// sequences. 604 /// 605 /// In particular, this routine gives user-defined conversion 606 /// sequences and ambiguous conversion sequences the same rank, 607 /// per C++ [over.best.ics]p10. getKindRank()608 unsigned getKindRank() const { 609 switch (getKind()) { 610 case StandardConversion: 611 return 0; 612 613 case UserDefinedConversion: 614 case AmbiguousConversion: 615 return 1; 616 617 case EllipsisConversion: 618 return 2; 619 620 case BadConversion: 621 return 3; 622 } 623 624 llvm_unreachable("Invalid ImplicitConversionSequence::Kind!"); 625 } 626 isBad()627 bool isBad() const { return getKind() == BadConversion; } isStandard()628 bool isStandard() const { return getKind() == StandardConversion; } isEllipsis()629 bool isEllipsis() const { return getKind() == EllipsisConversion; } isAmbiguous()630 bool isAmbiguous() const { return getKind() == AmbiguousConversion; } isUserDefined()631 bool isUserDefined() const { return getKind() == UserDefinedConversion; } isFailure()632 bool isFailure() const { return isBad() || isAmbiguous(); } 633 634 /// Determines whether this conversion sequence has been 635 /// initialized. Most operations should never need to query 636 /// uninitialized conversions and should assert as above. isInitialized()637 bool isInitialized() const { return ConversionKind != Uninitialized; } 638 639 /// Sets this sequence as a bad conversion for an explicit argument. setBad(BadConversionSequence::FailureKind Failure,Expr * FromExpr,QualType ToType)640 void setBad(BadConversionSequence::FailureKind Failure, 641 Expr *FromExpr, QualType ToType) { 642 setKind(BadConversion); 643 Bad.init(Failure, FromExpr, ToType); 644 } 645 646 /// Sets this sequence as a bad conversion for an implicit argument. setBad(BadConversionSequence::FailureKind Failure,QualType FromType,QualType ToType)647 void setBad(BadConversionSequence::FailureKind Failure, 648 QualType FromType, QualType ToType) { 649 setKind(BadConversion); 650 Bad.init(Failure, FromType, ToType); 651 } 652 setStandard()653 void setStandard() { setKind(StandardConversion); } setEllipsis()654 void setEllipsis() { setKind(EllipsisConversion); } setUserDefined()655 void setUserDefined() { setKind(UserDefinedConversion); } 656 setAmbiguous()657 void setAmbiguous() { 658 if (ConversionKind == AmbiguousConversion) return; 659 ConversionKind = AmbiguousConversion; 660 Ambiguous.construct(); 661 } 662 setAsIdentityConversion(QualType T)663 void setAsIdentityConversion(QualType T) { 664 setStandard(); 665 Standard.setAsIdentityConversion(); 666 Standard.setFromType(T); 667 Standard.setAllToTypes(T); 668 } 669 670 /// Whether the target is really a std::initializer_list, and the 671 /// sequence only represents the worst element conversion. isStdInitializerListElement()672 bool isStdInitializerListElement() const { 673 return StdInitializerListElement; 674 } 675 676 void setStdInitializerListElement(bool V = true) { 677 StdInitializerListElement = V; 678 } 679 680 /// Form an "implicit" conversion sequence from nullptr_t to bool, for a 681 /// direct-initialization of a bool object from nullptr_t. getNullptrToBool(QualType SourceType,QualType DestType,bool NeedLValToRVal)682 static ImplicitConversionSequence getNullptrToBool(QualType SourceType, 683 QualType DestType, 684 bool NeedLValToRVal) { 685 ImplicitConversionSequence ICS; 686 ICS.setStandard(); 687 ICS.Standard.setAsIdentityConversion(); 688 ICS.Standard.setFromType(SourceType); 689 if (NeedLValToRVal) 690 ICS.Standard.First = ICK_Lvalue_To_Rvalue; 691 ICS.Standard.setToType(0, SourceType); 692 ICS.Standard.Second = ICK_Boolean_Conversion; 693 ICS.Standard.setToType(1, DestType); 694 ICS.Standard.setToType(2, DestType); 695 return ICS; 696 } 697 698 // The result of a comparison between implicit conversion 699 // sequences. Use Sema::CompareImplicitConversionSequences to 700 // actually perform the comparison. 701 enum CompareKind { 702 Better = -1, 703 Indistinguishable = 0, 704 Worse = 1 705 }; 706 707 void DiagnoseAmbiguousConversion(Sema &S, 708 SourceLocation CaretLoc, 709 const PartialDiagnostic &PDiag) const; 710 711 void dump() const; 712 }; 713 714 enum OverloadFailureKind { 715 ovl_fail_too_many_arguments, 716 ovl_fail_too_few_arguments, 717 ovl_fail_bad_conversion, 718 ovl_fail_bad_deduction, 719 720 /// This conversion candidate was not considered because it 721 /// duplicates the work of a trivial or derived-to-base 722 /// conversion. 723 ovl_fail_trivial_conversion, 724 725 /// This conversion candidate was not considered because it is 726 /// an illegal instantiation of a constructor temploid: it is 727 /// callable with one argument, we only have one argument, and 728 /// its first parameter type is exactly the type of the class. 729 /// 730 /// Defining such a constructor directly is illegal, and 731 /// template-argument deduction is supposed to ignore such 732 /// instantiations, but we can still get one with the right 733 /// kind of implicit instantiation. 734 ovl_fail_illegal_constructor, 735 736 /// This conversion candidate is not viable because its result 737 /// type is not implicitly convertible to the desired type. 738 ovl_fail_bad_final_conversion, 739 740 /// This conversion function template specialization candidate is not 741 /// viable because the final conversion was not an exact match. 742 ovl_fail_final_conversion_not_exact, 743 744 /// (CUDA) This candidate was not viable because the callee 745 /// was not accessible from the caller's target (i.e. host->device, 746 /// global->host, device->host). 747 ovl_fail_bad_target, 748 749 /// This candidate function was not viable because an enable_if 750 /// attribute disabled it. 751 ovl_fail_enable_if, 752 753 /// This candidate constructor or conversion function is explicit but 754 /// the context doesn't permit explicit functions. 755 ovl_fail_explicit, 756 757 /// This candidate was not viable because its address could not be taken. 758 ovl_fail_addr_not_available, 759 760 /// This candidate was not viable because its OpenCL extension is disabled. 761 ovl_fail_ext_disabled, 762 763 /// This inherited constructor is not viable because it would slice the 764 /// argument. 765 ovl_fail_inhctor_slice, 766 767 /// This candidate was not viable because it is a non-default multiversioned 768 /// function. 769 ovl_non_default_multiversion_function, 770 771 /// This constructor/conversion candidate fail due to an address space 772 /// mismatch between the object being constructed and the overload 773 /// candidate. 774 ovl_fail_object_addrspace_mismatch, 775 776 /// This candidate was not viable because its associated constraints were 777 /// not satisfied. 778 ovl_fail_constraints_not_satisfied, 779 }; 780 781 /// A list of implicit conversion sequences for the arguments of an 782 /// OverloadCandidate. 783 using ConversionSequenceList = 784 llvm::MutableArrayRef<ImplicitConversionSequence>; 785 786 /// OverloadCandidate - A single candidate in an overload set (C++ 13.3). 787 struct OverloadCandidate { 788 /// Function - The actual function that this candidate 789 /// represents. When NULL, this is a built-in candidate 790 /// (C++ [over.oper]) or a surrogate for a conversion to a 791 /// function pointer or reference (C++ [over.call.object]). 792 FunctionDecl *Function; 793 794 /// FoundDecl - The original declaration that was looked up / 795 /// invented / otherwise found, together with its access. 796 /// Might be a UsingShadowDecl or a FunctionTemplateDecl. 797 DeclAccessPair FoundDecl; 798 799 /// BuiltinParamTypes - Provides the parameter types of a built-in overload 800 /// candidate. Only valid when Function is NULL. 801 QualType BuiltinParamTypes[3]; 802 803 /// Surrogate - The conversion function for which this candidate 804 /// is a surrogate, but only if IsSurrogate is true. 805 CXXConversionDecl *Surrogate; 806 807 /// The conversion sequences used to convert the function arguments 808 /// to the function parameters. Note that these are indexed by argument, 809 /// so may not match the parameter order of Function. 810 ConversionSequenceList Conversions; 811 812 /// The FixIt hints which can be used to fix the Bad candidate. 813 ConversionFixItGenerator Fix; 814 815 /// Viable - True to indicate that this overload candidate is viable. 816 bool Viable : 1; 817 818 /// Whether this candidate is the best viable function, or tied for being 819 /// the best viable function. 820 /// 821 /// For an ambiguous overload resolution, indicates whether this candidate 822 /// was part of the ambiguity kernel: the minimal non-empty set of viable 823 /// candidates such that all elements of the ambiguity kernel are better 824 /// than all viable candidates not in the ambiguity kernel. 825 bool Best : 1; 826 827 /// IsSurrogate - True to indicate that this candidate is a 828 /// surrogate for a conversion to a function pointer or reference 829 /// (C++ [over.call.object]). 830 bool IsSurrogate : 1; 831 832 /// IgnoreObjectArgument - True to indicate that the first 833 /// argument's conversion, which for this function represents the 834 /// implicit object argument, should be ignored. This will be true 835 /// when the candidate is a static member function (where the 836 /// implicit object argument is just a placeholder) or a 837 /// non-static member function when the call doesn't have an 838 /// object argument. 839 bool IgnoreObjectArgument : 1; 840 841 /// True if the candidate was found using ADL. 842 CallExpr::ADLCallKind IsADLCandidate : 1; 843 844 /// Whether this is a rewritten candidate, and if so, of what kind? 845 unsigned RewriteKind : 2; 846 847 /// FailureKind - The reason why this candidate is not viable. 848 /// Actually an OverloadFailureKind. 849 unsigned char FailureKind; 850 851 /// The number of call arguments that were explicitly provided, 852 /// to be used while performing partial ordering of function templates. 853 unsigned ExplicitCallArguments; 854 855 union { 856 DeductionFailureInfo DeductionFailure; 857 858 /// FinalConversion - For a conversion function (where Function is 859 /// a CXXConversionDecl), the standard conversion that occurs 860 /// after the call to the overload candidate to convert the result 861 /// of calling the conversion function to the required type. 862 StandardConversionSequence FinalConversion; 863 }; 864 865 /// Get RewriteKind value in OverloadCandidateRewriteKind type (This 866 /// function is to workaround the spurious GCC bitfield enum warning) getRewriteKindOverloadCandidate867 OverloadCandidateRewriteKind getRewriteKind() const { 868 return static_cast<OverloadCandidateRewriteKind>(RewriteKind); 869 } 870 isReversedOverloadCandidate871 bool isReversed() const { return getRewriteKind() & CRK_Reversed; } 872 873 /// hasAmbiguousConversion - Returns whether this overload 874 /// candidate requires an ambiguous conversion or not. hasAmbiguousConversionOverloadCandidate875 bool hasAmbiguousConversion() const { 876 for (auto &C : Conversions) { 877 if (!C.isInitialized()) return false; 878 if (C.isAmbiguous()) return true; 879 } 880 return false; 881 } 882 TryToFixBadConversionOverloadCandidate883 bool TryToFixBadConversion(unsigned Idx, Sema &S) { 884 bool CanFix = Fix.tryToFixConversion( 885 Conversions[Idx].Bad.FromExpr, 886 Conversions[Idx].Bad.getFromType(), 887 Conversions[Idx].Bad.getToType(), S); 888 889 // If at least one conversion fails, the candidate cannot be fixed. 890 if (!CanFix) 891 Fix.clear(); 892 893 return CanFix; 894 } 895 getNumParamsOverloadCandidate896 unsigned getNumParams() const { 897 if (IsSurrogate) { 898 QualType STy = Surrogate->getConversionType(); 899 while (STy->isPointerType() || STy->isReferenceType()) 900 STy = STy->getPointeeType(); 901 return STy->castAs<FunctionProtoType>()->getNumParams(); 902 } 903 if (Function) 904 return Function->getNumParams(); 905 return ExplicitCallArguments; 906 } 907 908 private: 909 friend class OverloadCandidateSet; OverloadCandidateOverloadCandidate910 OverloadCandidate() 911 : IsSurrogate(false), IsADLCandidate(CallExpr::NotADL), RewriteKind(CRK_None) {} 912 }; 913 914 /// OverloadCandidateSet - A set of overload candidates, used in C++ 915 /// overload resolution (C++ 13.3). 916 class OverloadCandidateSet { 917 public: 918 enum CandidateSetKind { 919 /// Normal lookup. 920 CSK_Normal, 921 922 /// C++ [over.match.oper]: 923 /// Lookup of operator function candidates in a call using operator 924 /// syntax. Candidates that have no parameters of class type will be 925 /// skipped unless there is a parameter of (reference to) enum type and 926 /// the corresponding argument is of the same enum type. 927 CSK_Operator, 928 929 /// C++ [over.match.copy]: 930 /// Copy-initialization of an object of class type by user-defined 931 /// conversion. 932 CSK_InitByUserDefinedConversion, 933 934 /// C++ [over.match.ctor], [over.match.list] 935 /// Initialization of an object of class type by constructor, 936 /// using either a parenthesized or braced list of arguments. 937 CSK_InitByConstructor, 938 }; 939 940 /// Information about operator rewrites to consider when adding operator 941 /// functions to a candidate set. 942 struct OperatorRewriteInfo { OperatorRewriteInfoOperatorRewriteInfo943 OperatorRewriteInfo() 944 : OriginalOperator(OO_None), AllowRewrittenCandidates(false) {} OperatorRewriteInfoOperatorRewriteInfo945 OperatorRewriteInfo(OverloadedOperatorKind Op, bool AllowRewritten) 946 : OriginalOperator(Op), AllowRewrittenCandidates(AllowRewritten) {} 947 948 /// The original operator as written in the source. 949 OverloadedOperatorKind OriginalOperator; 950 /// Whether we should include rewritten candidates in the overload set. 951 bool AllowRewrittenCandidates; 952 953 /// Would use of this function result in a rewrite using a different 954 /// operator? isRewrittenOperatorOperatorRewriteInfo955 bool isRewrittenOperator(const FunctionDecl *FD) { 956 return OriginalOperator && 957 FD->getDeclName().getCXXOverloadedOperator() != OriginalOperator; 958 } 959 isAcceptableCandidateOperatorRewriteInfo960 bool isAcceptableCandidate(const FunctionDecl *FD) { 961 if (!OriginalOperator) 962 return true; 963 964 // For an overloaded operator, we can have candidates with a different 965 // name in our unqualified lookup set. Make sure we only consider the 966 // ones we're supposed to. 967 OverloadedOperatorKind OO = 968 FD->getDeclName().getCXXOverloadedOperator(); 969 return OO && (OO == OriginalOperator || 970 (AllowRewrittenCandidates && 971 OO == getRewrittenOverloadedOperator(OriginalOperator))); 972 } 973 974 /// Determine the kind of rewrite that should be performed for this 975 /// candidate. 976 OverloadCandidateRewriteKind getRewriteKindOperatorRewriteInfo977 getRewriteKind(const FunctionDecl *FD, OverloadCandidateParamOrder PO) { 978 OverloadCandidateRewriteKind CRK = CRK_None; 979 if (isRewrittenOperator(FD)) 980 CRK = OverloadCandidateRewriteKind(CRK | CRK_DifferentOperator); 981 if (PO == OverloadCandidateParamOrder::Reversed) 982 CRK = OverloadCandidateRewriteKind(CRK | CRK_Reversed); 983 return CRK; 984 } 985 986 /// Determines whether this operator could be implemented by a function 987 /// with reversed parameter order. isReversibleOperatorRewriteInfo988 bool isReversible() { 989 return AllowRewrittenCandidates && OriginalOperator && 990 (getRewrittenOverloadedOperator(OriginalOperator) != OO_None || 991 shouldAddReversed(OriginalOperator)); 992 } 993 994 /// Determine whether we should consider looking for and adding reversed 995 /// candidates for operator Op. 996 bool shouldAddReversed(OverloadedOperatorKind Op); 997 998 /// Determine whether we should add a rewritten candidate for \p FD with 999 /// reversed parameter order. 1000 bool shouldAddReversed(ASTContext &Ctx, const FunctionDecl *FD); 1001 }; 1002 1003 private: 1004 SmallVector<OverloadCandidate, 16> Candidates; 1005 llvm::SmallPtrSet<uintptr_t, 16> Functions; 1006 1007 // Allocator for ConversionSequenceLists. We store the first few of these 1008 // inline to avoid allocation for small sets. 1009 llvm::BumpPtrAllocator SlabAllocator; 1010 1011 SourceLocation Loc; 1012 CandidateSetKind Kind; 1013 OperatorRewriteInfo RewriteInfo; 1014 1015 constexpr static unsigned NumInlineBytes = 1016 24 * sizeof(ImplicitConversionSequence); 1017 unsigned NumInlineBytesUsed = 0; 1018 alignas(void *) char InlineSpace[NumInlineBytes]; 1019 1020 // Address space of the object being constructed. 1021 LangAS DestAS = LangAS::Default; 1022 1023 /// If we have space, allocates from inline storage. Otherwise, allocates 1024 /// from the slab allocator. 1025 /// FIXME: It would probably be nice to have a SmallBumpPtrAllocator 1026 /// instead. 1027 /// FIXME: Now that this only allocates ImplicitConversionSequences, do we 1028 /// want to un-generalize this? 1029 template <typename T> slabAllocate(unsigned N)1030 T *slabAllocate(unsigned N) { 1031 // It's simpler if this doesn't need to consider alignment. 1032 static_assert(alignof(T) == alignof(void *), 1033 "Only works for pointer-aligned types."); 1034 static_assert(std::is_trivial<T>::value || 1035 std::is_same<ImplicitConversionSequence, T>::value, 1036 "Add destruction logic to OverloadCandidateSet::clear()."); 1037 1038 unsigned NBytes = sizeof(T) * N; 1039 if (NBytes > NumInlineBytes - NumInlineBytesUsed) 1040 return SlabAllocator.Allocate<T>(N); 1041 char *FreeSpaceStart = InlineSpace + NumInlineBytesUsed; 1042 assert(uintptr_t(FreeSpaceStart) % alignof(void *) == 0 && 1043 "Misaligned storage!"); 1044 1045 NumInlineBytesUsed += NBytes; 1046 return reinterpret_cast<T *>(FreeSpaceStart); 1047 } 1048 1049 void destroyCandidates(); 1050 1051 public: 1052 OverloadCandidateSet(SourceLocation Loc, CandidateSetKind CSK, 1053 OperatorRewriteInfo RewriteInfo = {}) Loc(Loc)1054 : Loc(Loc), Kind(CSK), RewriteInfo(RewriteInfo) {} 1055 OverloadCandidateSet(const OverloadCandidateSet &) = delete; 1056 OverloadCandidateSet &operator=(const OverloadCandidateSet &) = delete; ~OverloadCandidateSet()1057 ~OverloadCandidateSet() { destroyCandidates(); } 1058 getLocation()1059 SourceLocation getLocation() const { return Loc; } getKind()1060 CandidateSetKind getKind() const { return Kind; } getRewriteInfo()1061 OperatorRewriteInfo getRewriteInfo() const { return RewriteInfo; } 1062 1063 /// Determine when this overload candidate will be new to the 1064 /// overload set. 1065 bool isNewCandidate(Decl *F, OverloadCandidateParamOrder PO = 1066 OverloadCandidateParamOrder::Normal) { 1067 uintptr_t Key = reinterpret_cast<uintptr_t>(F->getCanonicalDecl()); 1068 Key |= static_cast<uintptr_t>(PO); 1069 return Functions.insert(Key).second; 1070 } 1071 1072 /// Exclude a function from being considered by overload resolution. exclude(Decl * F)1073 void exclude(Decl *F) { 1074 isNewCandidate(F, OverloadCandidateParamOrder::Normal); 1075 isNewCandidate(F, OverloadCandidateParamOrder::Reversed); 1076 } 1077 1078 /// Clear out all of the candidates. 1079 void clear(CandidateSetKind CSK); 1080 1081 using iterator = SmallVectorImpl<OverloadCandidate>::iterator; 1082 begin()1083 iterator begin() { return Candidates.begin(); } end()1084 iterator end() { return Candidates.end(); } 1085 size()1086 size_t size() const { return Candidates.size(); } empty()1087 bool empty() const { return Candidates.empty(); } 1088 1089 /// Allocate storage for conversion sequences for NumConversions 1090 /// conversions. 1091 ConversionSequenceList allocateConversionSequences(unsigned NumConversions)1092 allocateConversionSequences(unsigned NumConversions) { 1093 ImplicitConversionSequence *Conversions = 1094 slabAllocate<ImplicitConversionSequence>(NumConversions); 1095 1096 // Construct the new objects. 1097 for (unsigned I = 0; I != NumConversions; ++I) 1098 new (&Conversions[I]) ImplicitConversionSequence(); 1099 1100 return ConversionSequenceList(Conversions, NumConversions); 1101 } 1102 1103 /// Add a new candidate with NumConversions conversion sequence slots 1104 /// to the overload set. 1105 OverloadCandidate &addCandidate(unsigned NumConversions = 0, 1106 ConversionSequenceList Conversions = None) { 1107 assert((Conversions.empty() || Conversions.size() == NumConversions) && 1108 "preallocated conversion sequence has wrong length"); 1109 1110 Candidates.push_back(OverloadCandidate()); 1111 OverloadCandidate &C = Candidates.back(); 1112 C.Conversions = Conversions.empty() 1113 ? allocateConversionSequences(NumConversions) 1114 : Conversions; 1115 return C; 1116 } 1117 1118 /// Find the best viable function on this overload set, if it exists. 1119 OverloadingResult BestViableFunction(Sema &S, SourceLocation Loc, 1120 OverloadCandidateSet::iterator& Best); 1121 1122 SmallVector<OverloadCandidate *, 32> CompleteCandidates( 1123 Sema &S, OverloadCandidateDisplayKind OCD, ArrayRef<Expr *> Args, 1124 SourceLocation OpLoc = SourceLocation(), 1125 llvm::function_ref<bool(OverloadCandidate &)> Filter = 1126 [](OverloadCandidate &) { return true; }); 1127 1128 void NoteCandidates( 1129 PartialDiagnosticAt PA, Sema &S, OverloadCandidateDisplayKind OCD, 1130 ArrayRef<Expr *> Args, StringRef Opc = "", 1131 SourceLocation Loc = SourceLocation(), 1132 llvm::function_ref<bool(OverloadCandidate &)> Filter = 1133 [](OverloadCandidate &) { return true; }); 1134 1135 void NoteCandidates(Sema &S, ArrayRef<Expr *> Args, 1136 ArrayRef<OverloadCandidate *> Cands, 1137 StringRef Opc = "", 1138 SourceLocation OpLoc = SourceLocation()); 1139 getDestAS()1140 LangAS getDestAS() { return DestAS; } 1141 setDestAS(LangAS AS)1142 void setDestAS(LangAS AS) { 1143 assert((Kind == CSK_InitByConstructor || 1144 Kind == CSK_InitByUserDefinedConversion) && 1145 "can't set the destination address space when not constructing an " 1146 "object"); 1147 DestAS = AS; 1148 } 1149 1150 }; 1151 1152 bool isBetterOverloadCandidate(Sema &S, 1153 const OverloadCandidate &Cand1, 1154 const OverloadCandidate &Cand2, 1155 SourceLocation Loc, 1156 OverloadCandidateSet::CandidateSetKind Kind); 1157 1158 struct ConstructorInfo { 1159 DeclAccessPair FoundDecl; 1160 CXXConstructorDecl *Constructor; 1161 FunctionTemplateDecl *ConstructorTmpl; 1162 1163 explicit operator bool() const { return Constructor; } 1164 }; 1165 1166 // FIXME: Add an AddOverloadCandidate / AddTemplateOverloadCandidate overload 1167 // that takes one of these. getConstructorInfo(NamedDecl * ND)1168 inline ConstructorInfo getConstructorInfo(NamedDecl *ND) { 1169 if (isa<UsingDecl>(ND)) 1170 return ConstructorInfo{}; 1171 1172 // For constructors, the access check is performed against the underlying 1173 // declaration, not the found declaration. 1174 auto *D = ND->getUnderlyingDecl(); 1175 ConstructorInfo Info = {DeclAccessPair::make(ND, D->getAccess()), nullptr, 1176 nullptr}; 1177 Info.ConstructorTmpl = dyn_cast<FunctionTemplateDecl>(D); 1178 if (Info.ConstructorTmpl) 1179 D = Info.ConstructorTmpl->getTemplatedDecl(); 1180 Info.Constructor = dyn_cast<CXXConstructorDecl>(D); 1181 return Info; 1182 } 1183 1184 } // namespace clang 1185 1186 #endif // LLVM_CLANG_SEMA_OVERLOAD_H 1187