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      1 //===--- DeclBase.cpp - Declaration AST Node Implementation ---------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This file implements the Decl and DeclContext classes.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "clang/AST/DeclBase.h"
     15 #include "clang/AST/ASTContext.h"
     16 #include "clang/AST/ASTMutationListener.h"
     17 #include "clang/AST/Attr.h"
     18 #include "clang/AST/Decl.h"
     19 #include "clang/AST/DeclCXX.h"
     20 #include "clang/AST/DeclContextInternals.h"
     21 #include "clang/AST/DeclFriend.h"
     22 #include "clang/AST/DeclObjC.h"
     23 #include "clang/AST/DeclOpenMP.h"
     24 #include "clang/AST/DeclTemplate.h"
     25 #include "clang/AST/DependentDiagnostic.h"
     26 #include "clang/AST/ExternalASTSource.h"
     27 #include "clang/AST/Stmt.h"
     28 #include "clang/AST/StmtCXX.h"
     29 #include "clang/AST/Type.h"
     30 #include "clang/Basic/TargetInfo.h"
     31 #include "llvm/ADT/DenseMap.h"
     32 #include "llvm/Support/raw_ostream.h"
     33 #include <algorithm>
     34 using namespace clang;
     35 
     36 //===----------------------------------------------------------------------===//
     37 //  Statistics
     38 //===----------------------------------------------------------------------===//
     39 
     40 #define DECL(DERIVED, BASE) static int n##DERIVED##s = 0;
     41 #define ABSTRACT_DECL(DECL)
     42 #include "clang/AST/DeclNodes.inc"
     43 
     44 void Decl::updateOutOfDate(IdentifierInfo &II) const {
     45   getASTContext().getExternalSource()->updateOutOfDateIdentifier(II);
     46 }
     47 
     48 #define DECL(DERIVED, BASE)                                                    \
     49   static_assert(Decl::DeclObjAlignment >=                                      \
     50                     llvm::AlignOf<DERIVED##Decl>::Alignment,                   \
     51                 "Alignment sufficient after objects prepended to " #DERIVED);
     52 #define ABSTRACT_DECL(DECL)
     53 #include "clang/AST/DeclNodes.inc"
     54 
     55 void *Decl::operator new(std::size_t Size, const ASTContext &Context,
     56                          unsigned ID, std::size_t Extra) {
     57   // Allocate an extra 8 bytes worth of storage, which ensures that the
     58   // resulting pointer will still be 8-byte aligned.
     59   static_assert(sizeof(unsigned) * 2 >= DeclObjAlignment,
     60                 "Decl won't be misaligned");
     61   void *Start = Context.Allocate(Size + Extra + 8);
     62   void *Result = (char*)Start + 8;
     63 
     64   unsigned *PrefixPtr = (unsigned *)Result - 2;
     65 
     66   // Zero out the first 4 bytes; this is used to store the owning module ID.
     67   PrefixPtr[0] = 0;
     68 
     69   // Store the global declaration ID in the second 4 bytes.
     70   PrefixPtr[1] = ID;
     71 
     72   return Result;
     73 }
     74 
     75 void *Decl::operator new(std::size_t Size, const ASTContext &Ctx,
     76                          DeclContext *Parent, std::size_t Extra) {
     77   assert(!Parent || &Parent->getParentASTContext() == &Ctx);
     78   // With local visibility enabled, we track the owning module even for local
     79   // declarations.
     80   if (Ctx.getLangOpts().ModulesLocalVisibility) {
     81     // Ensure required alignment of the resulting object by adding extra
     82     // padding at the start if required.
     83     size_t ExtraAlign =
     84         llvm::OffsetToAlignment(sizeof(Module *), DeclObjAlignment);
     85     char *Buffer = reinterpret_cast<char *>(
     86         ::operator new(ExtraAlign + sizeof(Module *) + Size + Extra, Ctx));
     87     Buffer += ExtraAlign;
     88     return new (Buffer) Module*(nullptr) + 1;
     89   }
     90   return ::operator new(Size + Extra, Ctx);
     91 }
     92 
     93 Module *Decl::getOwningModuleSlow() const {
     94   assert(isFromASTFile() && "Not from AST file?");
     95   return getASTContext().getExternalSource()->getModule(getOwningModuleID());
     96 }
     97 
     98 bool Decl::hasLocalOwningModuleStorage() const {
     99   return getASTContext().getLangOpts().ModulesLocalVisibility;
    100 }
    101 
    102 const char *Decl::getDeclKindName() const {
    103   switch (DeclKind) {
    104   default: llvm_unreachable("Declaration not in DeclNodes.inc!");
    105 #define DECL(DERIVED, BASE) case DERIVED: return #DERIVED;
    106 #define ABSTRACT_DECL(DECL)
    107 #include "clang/AST/DeclNodes.inc"
    108   }
    109 }
    110 
    111 void Decl::setInvalidDecl(bool Invalid) {
    112   InvalidDecl = Invalid;
    113   assert(!isa<TagDecl>(this) || !cast<TagDecl>(this)->isCompleteDefinition());
    114   if (Invalid && !isa<ParmVarDecl>(this)) {
    115     // Defensive maneuver for ill-formed code: we're likely not to make it to
    116     // a point where we set the access specifier, so default it to "public"
    117     // to avoid triggering asserts elsewhere in the front end.
    118     setAccess(AS_public);
    119   }
    120 }
    121 
    122 const char *DeclContext::getDeclKindName() const {
    123   switch (DeclKind) {
    124   default: llvm_unreachable("Declaration context not in DeclNodes.inc!");
    125 #define DECL(DERIVED, BASE) case Decl::DERIVED: return #DERIVED;
    126 #define ABSTRACT_DECL(DECL)
    127 #include "clang/AST/DeclNodes.inc"
    128   }
    129 }
    130 
    131 bool Decl::StatisticsEnabled = false;
    132 void Decl::EnableStatistics() {
    133   StatisticsEnabled = true;
    134 }
    135 
    136 void Decl::PrintStats() {
    137   llvm::errs() << "\n*** Decl Stats:\n";
    138 
    139   int totalDecls = 0;
    140 #define DECL(DERIVED, BASE) totalDecls += n##DERIVED##s;
    141 #define ABSTRACT_DECL(DECL)
    142 #include "clang/AST/DeclNodes.inc"
    143   llvm::errs() << "  " << totalDecls << " decls total.\n";
    144 
    145   int totalBytes = 0;
    146 #define DECL(DERIVED, BASE)                                             \
    147   if (n##DERIVED##s > 0) {                                              \
    148     totalBytes += (int)(n##DERIVED##s * sizeof(DERIVED##Decl));         \
    149     llvm::errs() << "    " << n##DERIVED##s << " " #DERIVED " decls, "  \
    150                  << sizeof(DERIVED##Decl) << " each ("                  \
    151                  << n##DERIVED##s * sizeof(DERIVED##Decl)               \
    152                  << " bytes)\n";                                        \
    153   }
    154 #define ABSTRACT_DECL(DECL)
    155 #include "clang/AST/DeclNodes.inc"
    156 
    157   llvm::errs() << "Total bytes = " << totalBytes << "\n";
    158 }
    159 
    160 void Decl::add(Kind k) {
    161   switch (k) {
    162 #define DECL(DERIVED, BASE) case DERIVED: ++n##DERIVED##s; break;
    163 #define ABSTRACT_DECL(DECL)
    164 #include "clang/AST/DeclNodes.inc"
    165   }
    166 }
    167 
    168 bool Decl::isTemplateParameterPack() const {
    169   if (const TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(this))
    170     return TTP->isParameterPack();
    171   if (const NonTypeTemplateParmDecl *NTTP
    172                                 = dyn_cast<NonTypeTemplateParmDecl>(this))
    173     return NTTP->isParameterPack();
    174   if (const TemplateTemplateParmDecl *TTP
    175                                     = dyn_cast<TemplateTemplateParmDecl>(this))
    176     return TTP->isParameterPack();
    177   return false;
    178 }
    179 
    180 bool Decl::isParameterPack() const {
    181   if (const ParmVarDecl *Parm = dyn_cast<ParmVarDecl>(this))
    182     return Parm->isParameterPack();
    183 
    184   return isTemplateParameterPack();
    185 }
    186 
    187 FunctionDecl *Decl::getAsFunction() {
    188   if (FunctionDecl *FD = dyn_cast<FunctionDecl>(this))
    189     return FD;
    190   if (const FunctionTemplateDecl *FTD = dyn_cast<FunctionTemplateDecl>(this))
    191     return FTD->getTemplatedDecl();
    192   return nullptr;
    193 }
    194 
    195 bool Decl::isTemplateDecl() const {
    196   return isa<TemplateDecl>(this);
    197 }
    198 
    199 const DeclContext *Decl::getParentFunctionOrMethod() const {
    200   for (const DeclContext *DC = getDeclContext();
    201        DC && !DC->isTranslationUnit() && !DC->isNamespace();
    202        DC = DC->getParent())
    203     if (DC->isFunctionOrMethod())
    204       return DC;
    205 
    206   return nullptr;
    207 }
    208 
    209 
    210 //===----------------------------------------------------------------------===//
    211 // PrettyStackTraceDecl Implementation
    212 //===----------------------------------------------------------------------===//
    213 
    214 void PrettyStackTraceDecl::print(raw_ostream &OS) const {
    215   SourceLocation TheLoc = Loc;
    216   if (TheLoc.isInvalid() && TheDecl)
    217     TheLoc = TheDecl->getLocation();
    218 
    219   if (TheLoc.isValid()) {
    220     TheLoc.print(OS, SM);
    221     OS << ": ";
    222   }
    223 
    224   OS << Message;
    225 
    226   if (const NamedDecl *DN = dyn_cast_or_null<NamedDecl>(TheDecl)) {
    227     OS << " '";
    228     DN->printQualifiedName(OS);
    229     OS << '\'';
    230   }
    231   OS << '\n';
    232 }
    233 
    234 //===----------------------------------------------------------------------===//
    235 // Decl Implementation
    236 //===----------------------------------------------------------------------===//
    237 
    238 // Out-of-line virtual method providing a home for Decl.
    239 Decl::~Decl() { }
    240 
    241 void Decl::setDeclContext(DeclContext *DC) {
    242   DeclCtx = DC;
    243 }
    244 
    245 void Decl::setLexicalDeclContext(DeclContext *DC) {
    246   if (DC == getLexicalDeclContext())
    247     return;
    248 
    249   if (isInSemaDC()) {
    250     setDeclContextsImpl(getDeclContext(), DC, getASTContext());
    251   } else {
    252     getMultipleDC()->LexicalDC = DC;
    253   }
    254   Hidden = cast<Decl>(DC)->Hidden;
    255 }
    256 
    257 void Decl::setDeclContextsImpl(DeclContext *SemaDC, DeclContext *LexicalDC,
    258                                ASTContext &Ctx) {
    259   if (SemaDC == LexicalDC) {
    260     DeclCtx = SemaDC;
    261   } else {
    262     Decl::MultipleDC *MDC = new (Ctx) Decl::MultipleDC();
    263     MDC->SemanticDC = SemaDC;
    264     MDC->LexicalDC = LexicalDC;
    265     DeclCtx = MDC;
    266   }
    267 }
    268 
    269 bool Decl::isLexicallyWithinFunctionOrMethod() const {
    270   const DeclContext *LDC = getLexicalDeclContext();
    271   while (true) {
    272     if (LDC->isFunctionOrMethod())
    273       return true;
    274     if (!isa<TagDecl>(LDC))
    275       return false;
    276     LDC = LDC->getLexicalParent();
    277   }
    278   return false;
    279 }
    280 
    281 bool Decl::isInAnonymousNamespace() const {
    282   const DeclContext *DC = getDeclContext();
    283   do {
    284     if (const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(DC))
    285       if (ND->isAnonymousNamespace())
    286         return true;
    287   } while ((DC = DC->getParent()));
    288 
    289   return false;
    290 }
    291 
    292 bool Decl::isInStdNamespace() const {
    293   return getDeclContext()->isStdNamespace();
    294 }
    295 
    296 TranslationUnitDecl *Decl::getTranslationUnitDecl() {
    297   if (TranslationUnitDecl *TUD = dyn_cast<TranslationUnitDecl>(this))
    298     return TUD;
    299 
    300   DeclContext *DC = getDeclContext();
    301   assert(DC && "This decl is not contained in a translation unit!");
    302 
    303   while (!DC->isTranslationUnit()) {
    304     DC = DC->getParent();
    305     assert(DC && "This decl is not contained in a translation unit!");
    306   }
    307 
    308   return cast<TranslationUnitDecl>(DC);
    309 }
    310 
    311 ASTContext &Decl::getASTContext() const {
    312   return getTranslationUnitDecl()->getASTContext();
    313 }
    314 
    315 ASTMutationListener *Decl::getASTMutationListener() const {
    316   return getASTContext().getASTMutationListener();
    317 }
    318 
    319 unsigned Decl::getMaxAlignment() const {
    320   if (!hasAttrs())
    321     return 0;
    322 
    323   unsigned Align = 0;
    324   const AttrVec &V = getAttrs();
    325   ASTContext &Ctx = getASTContext();
    326   specific_attr_iterator<AlignedAttr> I(V.begin()), E(V.end());
    327   for (; I != E; ++I)
    328     Align = std::max(Align, I->getAlignment(Ctx));
    329   return Align;
    330 }
    331 
    332 bool Decl::isUsed(bool CheckUsedAttr) const {
    333   if (Used)
    334     return true;
    335 
    336   // Check for used attribute.
    337   if (CheckUsedAttr && hasAttr<UsedAttr>())
    338     return true;
    339 
    340   return false;
    341 }
    342 
    343 void Decl::markUsed(ASTContext &C) {
    344   if (Used)
    345     return;
    346 
    347   if (C.getASTMutationListener())
    348     C.getASTMutationListener()->DeclarationMarkedUsed(this);
    349 
    350   Used = true;
    351 }
    352 
    353 bool Decl::isReferenced() const {
    354   if (Referenced)
    355     return true;
    356 
    357   // Check redeclarations.
    358   for (auto I : redecls())
    359     if (I->Referenced)
    360       return true;
    361 
    362   return false;
    363 }
    364 
    365 /// \brief Determine the availability of the given declaration based on
    366 /// the target platform.
    367 ///
    368 /// When it returns an availability result other than \c AR_Available,
    369 /// if the \p Message parameter is non-NULL, it will be set to a
    370 /// string describing why the entity is unavailable.
    371 ///
    372 /// FIXME: Make these strings localizable, since they end up in
    373 /// diagnostics.
    374 static AvailabilityResult CheckAvailability(ASTContext &Context,
    375                                             const AvailabilityAttr *A,
    376                                             std::string *Message) {
    377   VersionTuple TargetMinVersion =
    378     Context.getTargetInfo().getPlatformMinVersion();
    379 
    380   if (TargetMinVersion.empty())
    381     return AR_Available;
    382 
    383   // Check if this is an App Extension "platform", and if so chop off
    384   // the suffix for matching with the actual platform.
    385   StringRef ActualPlatform = A->getPlatform()->getName();
    386   StringRef RealizedPlatform = ActualPlatform;
    387   if (Context.getLangOpts().AppExt) {
    388     size_t suffix = RealizedPlatform.rfind("_app_extension");
    389     if (suffix != StringRef::npos)
    390       RealizedPlatform = RealizedPlatform.slice(0, suffix);
    391   }
    392 
    393   StringRef TargetPlatform = Context.getTargetInfo().getPlatformName();
    394 
    395   // Match the platform name.
    396   if (RealizedPlatform != TargetPlatform)
    397     return AR_Available;
    398 
    399   StringRef PrettyPlatformName
    400     = AvailabilityAttr::getPrettyPlatformName(ActualPlatform);
    401 
    402   if (PrettyPlatformName.empty())
    403     PrettyPlatformName = ActualPlatform;
    404 
    405   std::string HintMessage;
    406   if (!A->getMessage().empty()) {
    407     HintMessage = " - ";
    408     HintMessage += A->getMessage();
    409   }
    410 
    411   // Make sure that this declaration has not been marked 'unavailable'.
    412   if (A->getUnavailable()) {
    413     if (Message) {
    414       Message->clear();
    415       llvm::raw_string_ostream Out(*Message);
    416       Out << "not available on " << PrettyPlatformName
    417           << HintMessage;
    418     }
    419 
    420     return AR_Unavailable;
    421   }
    422 
    423   // Make sure that this declaration has already been introduced.
    424   if (!A->getIntroduced().empty() &&
    425       TargetMinVersion < A->getIntroduced()) {
    426     if (Message) {
    427       Message->clear();
    428       llvm::raw_string_ostream Out(*Message);
    429       VersionTuple VTI(A->getIntroduced());
    430       VTI.UseDotAsSeparator();
    431       Out << "introduced in " << PrettyPlatformName << ' '
    432           << VTI << HintMessage;
    433     }
    434 
    435     return AR_NotYetIntroduced;
    436   }
    437 
    438   // Make sure that this declaration hasn't been obsoleted.
    439   if (!A->getObsoleted().empty() && TargetMinVersion >= A->getObsoleted()) {
    440     if (Message) {
    441       Message->clear();
    442       llvm::raw_string_ostream Out(*Message);
    443       VersionTuple VTO(A->getObsoleted());
    444       VTO.UseDotAsSeparator();
    445       Out << "obsoleted in " << PrettyPlatformName << ' '
    446           << VTO << HintMessage;
    447     }
    448 
    449     return AR_Unavailable;
    450   }
    451 
    452   // Make sure that this declaration hasn't been deprecated.
    453   if (!A->getDeprecated().empty() && TargetMinVersion >= A->getDeprecated()) {
    454     if (Message) {
    455       Message->clear();
    456       llvm::raw_string_ostream Out(*Message);
    457       VersionTuple VTD(A->getDeprecated());
    458       VTD.UseDotAsSeparator();
    459       Out << "first deprecated in " << PrettyPlatformName << ' '
    460           << VTD << HintMessage;
    461     }
    462 
    463     return AR_Deprecated;
    464   }
    465 
    466   return AR_Available;
    467 }
    468 
    469 AvailabilityResult Decl::getAvailability(std::string *Message) const {
    470   AvailabilityResult Result = AR_Available;
    471   std::string ResultMessage;
    472 
    473   for (const auto *A : attrs()) {
    474     if (const auto *Deprecated = dyn_cast<DeprecatedAttr>(A)) {
    475       if (Result >= AR_Deprecated)
    476         continue;
    477 
    478       if (Message)
    479         ResultMessage = Deprecated->getMessage();
    480 
    481       Result = AR_Deprecated;
    482       continue;
    483     }
    484 
    485     if (const auto *Unavailable = dyn_cast<UnavailableAttr>(A)) {
    486       if (Message)
    487         *Message = Unavailable->getMessage();
    488       return AR_Unavailable;
    489     }
    490 
    491     if (const auto *Availability = dyn_cast<AvailabilityAttr>(A)) {
    492       AvailabilityResult AR = CheckAvailability(getASTContext(), Availability,
    493                                                 Message);
    494 
    495       if (AR == AR_Unavailable)
    496         return AR_Unavailable;
    497 
    498       if (AR > Result) {
    499         Result = AR;
    500         if (Message)
    501           ResultMessage.swap(*Message);
    502       }
    503       continue;
    504     }
    505   }
    506 
    507   if (Message)
    508     Message->swap(ResultMessage);
    509   return Result;
    510 }
    511 
    512 bool Decl::canBeWeakImported(bool &IsDefinition) const {
    513   IsDefinition = false;
    514 
    515   // Variables, if they aren't definitions.
    516   if (const VarDecl *Var = dyn_cast<VarDecl>(this)) {
    517     if (Var->isThisDeclarationADefinition()) {
    518       IsDefinition = true;
    519       return false;
    520     }
    521     return true;
    522 
    523   // Functions, if they aren't definitions.
    524   } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(this)) {
    525     if (FD->hasBody()) {
    526       IsDefinition = true;
    527       return false;
    528     }
    529     return true;
    530 
    531   // Objective-C classes, if this is the non-fragile runtime.
    532   } else if (isa<ObjCInterfaceDecl>(this) &&
    533              getASTContext().getLangOpts().ObjCRuntime.hasWeakClassImport()) {
    534     return true;
    535 
    536   // Nothing else.
    537   } else {
    538     return false;
    539   }
    540 }
    541 
    542 bool Decl::isWeakImported() const {
    543   bool IsDefinition;
    544   if (!canBeWeakImported(IsDefinition))
    545     return false;
    546 
    547   for (const auto *A : attrs()) {
    548     if (isa<WeakImportAttr>(A))
    549       return true;
    550 
    551     if (const auto *Availability = dyn_cast<AvailabilityAttr>(A)) {
    552       if (CheckAvailability(getASTContext(), Availability,
    553                             nullptr) == AR_NotYetIntroduced)
    554         return true;
    555     }
    556   }
    557 
    558   return false;
    559 }
    560 
    561 unsigned Decl::getIdentifierNamespaceForKind(Kind DeclKind) {
    562   switch (DeclKind) {
    563     case Function:
    564     case CXXMethod:
    565     case CXXConstructor:
    566     case CXXDestructor:
    567     case CXXConversion:
    568     case EnumConstant:
    569     case Var:
    570     case ImplicitParam:
    571     case ParmVar:
    572     case NonTypeTemplateParm:
    573     case ObjCMethod:
    574     case ObjCProperty:
    575     case MSProperty:
    576       return IDNS_Ordinary;
    577     case Label:
    578       return IDNS_Label;
    579     case IndirectField:
    580       return IDNS_Ordinary | IDNS_Member;
    581 
    582     case ObjCCompatibleAlias:
    583     case ObjCInterface:
    584       return IDNS_Ordinary | IDNS_Type;
    585 
    586     case Typedef:
    587     case TypeAlias:
    588     case TypeAliasTemplate:
    589     case UnresolvedUsingTypename:
    590     case TemplateTypeParm:
    591     case ObjCTypeParam:
    592       return IDNS_Ordinary | IDNS_Type;
    593 
    594     case UsingShadow:
    595       return 0; // we'll actually overwrite this later
    596 
    597     case UnresolvedUsingValue:
    598       return IDNS_Ordinary | IDNS_Using;
    599 
    600     case Using:
    601       return IDNS_Using;
    602 
    603     case ObjCProtocol:
    604       return IDNS_ObjCProtocol;
    605 
    606     case Field:
    607     case ObjCAtDefsField:
    608     case ObjCIvar:
    609       return IDNS_Member;
    610 
    611     case Record:
    612     case CXXRecord:
    613     case Enum:
    614       return IDNS_Tag | IDNS_Type;
    615 
    616     case Namespace:
    617     case NamespaceAlias:
    618       return IDNS_Namespace;
    619 
    620     case FunctionTemplate:
    621     case VarTemplate:
    622       return IDNS_Ordinary;
    623 
    624     case ClassTemplate:
    625     case TemplateTemplateParm:
    626       return IDNS_Ordinary | IDNS_Tag | IDNS_Type;
    627 
    628     // Never have names.
    629     case Friend:
    630     case FriendTemplate:
    631     case AccessSpec:
    632     case LinkageSpec:
    633     case FileScopeAsm:
    634     case StaticAssert:
    635     case ObjCPropertyImpl:
    636     case Block:
    637     case Captured:
    638     case TranslationUnit:
    639     case ExternCContext:
    640 
    641     case UsingDirective:
    642     case BuiltinTemplate:
    643     case ClassTemplateSpecialization:
    644     case ClassTemplatePartialSpecialization:
    645     case ClassScopeFunctionSpecialization:
    646     case VarTemplateSpecialization:
    647     case VarTemplatePartialSpecialization:
    648     case ObjCImplementation:
    649     case ObjCCategory:
    650     case ObjCCategoryImpl:
    651     case Import:
    652     case OMPThreadPrivate:
    653     case Empty:
    654       // Never looked up by name.
    655       return 0;
    656   }
    657 
    658   llvm_unreachable("Invalid DeclKind!");
    659 }
    660 
    661 void Decl::setAttrsImpl(const AttrVec &attrs, ASTContext &Ctx) {
    662   assert(!HasAttrs && "Decl already contains attrs.");
    663 
    664   AttrVec &AttrBlank = Ctx.getDeclAttrs(this);
    665   assert(AttrBlank.empty() && "HasAttrs was wrong?");
    666 
    667   AttrBlank = attrs;
    668   HasAttrs = true;
    669 }
    670 
    671 void Decl::dropAttrs() {
    672   if (!HasAttrs) return;
    673 
    674   HasAttrs = false;
    675   getASTContext().eraseDeclAttrs(this);
    676 }
    677 
    678 const AttrVec &Decl::getAttrs() const {
    679   assert(HasAttrs && "No attrs to get!");
    680   return getASTContext().getDeclAttrs(this);
    681 }
    682 
    683 Decl *Decl::castFromDeclContext (const DeclContext *D) {
    684   Decl::Kind DK = D->getDeclKind();
    685   switch(DK) {
    686 #define DECL(NAME, BASE)
    687 #define DECL_CONTEXT(NAME) \
    688     case Decl::NAME:       \
    689       return static_cast<NAME##Decl*>(const_cast<DeclContext*>(D));
    690 #define DECL_CONTEXT_BASE(NAME)
    691 #include "clang/AST/DeclNodes.inc"
    692     default:
    693 #define DECL(NAME, BASE)
    694 #define DECL_CONTEXT_BASE(NAME)                  \
    695       if (DK >= first##NAME && DK <= last##NAME) \
    696         return static_cast<NAME##Decl*>(const_cast<DeclContext*>(D));
    697 #include "clang/AST/DeclNodes.inc"
    698       llvm_unreachable("a decl that inherits DeclContext isn't handled");
    699   }
    700 }
    701 
    702 DeclContext *Decl::castToDeclContext(const Decl *D) {
    703   Decl::Kind DK = D->getKind();
    704   switch(DK) {
    705 #define DECL(NAME, BASE)
    706 #define DECL_CONTEXT(NAME) \
    707     case Decl::NAME:       \
    708       return static_cast<NAME##Decl*>(const_cast<Decl*>(D));
    709 #define DECL_CONTEXT_BASE(NAME)
    710 #include "clang/AST/DeclNodes.inc"
    711     default:
    712 #define DECL(NAME, BASE)
    713 #define DECL_CONTEXT_BASE(NAME)                                   \
    714       if (DK >= first##NAME && DK <= last##NAME)                  \
    715         return static_cast<NAME##Decl*>(const_cast<Decl*>(D));
    716 #include "clang/AST/DeclNodes.inc"
    717       llvm_unreachable("a decl that inherits DeclContext isn't handled");
    718   }
    719 }
    720 
    721 SourceLocation Decl::getBodyRBrace() const {
    722   // Special handling of FunctionDecl to avoid de-serializing the body from PCH.
    723   // FunctionDecl stores EndRangeLoc for this purpose.
    724   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(this)) {
    725     const FunctionDecl *Definition;
    726     if (FD->hasBody(Definition))
    727       return Definition->getSourceRange().getEnd();
    728     return SourceLocation();
    729   }
    730 
    731   if (Stmt *Body = getBody())
    732     return Body->getSourceRange().getEnd();
    733 
    734   return SourceLocation();
    735 }
    736 
    737 bool Decl::AccessDeclContextSanity() const {
    738 #ifndef NDEBUG
    739   // Suppress this check if any of the following hold:
    740   // 1. this is the translation unit (and thus has no parent)
    741   // 2. this is a template parameter (and thus doesn't belong to its context)
    742   // 3. this is a non-type template parameter
    743   // 4. the context is not a record
    744   // 5. it's invalid
    745   // 6. it's a C++0x static_assert.
    746   if (isa<TranslationUnitDecl>(this) ||
    747       isa<TemplateTypeParmDecl>(this) ||
    748       isa<NonTypeTemplateParmDecl>(this) ||
    749       !isa<CXXRecordDecl>(getDeclContext()) ||
    750       isInvalidDecl() ||
    751       isa<StaticAssertDecl>(this) ||
    752       // FIXME: a ParmVarDecl can have ClassTemplateSpecialization
    753       // as DeclContext (?).
    754       isa<ParmVarDecl>(this) ||
    755       // FIXME: a ClassTemplateSpecialization or CXXRecordDecl can have
    756       // AS_none as access specifier.
    757       isa<CXXRecordDecl>(this) ||
    758       isa<ClassScopeFunctionSpecializationDecl>(this))
    759     return true;
    760 
    761   assert(Access != AS_none &&
    762          "Access specifier is AS_none inside a record decl");
    763 #endif
    764   return true;
    765 }
    766 
    767 static Decl::Kind getKind(const Decl *D) { return D->getKind(); }
    768 static Decl::Kind getKind(const DeclContext *DC) { return DC->getDeclKind(); }
    769 
    770 const FunctionType *Decl::getFunctionType(bool BlocksToo) const {
    771   QualType Ty;
    772   if (const ValueDecl *D = dyn_cast<ValueDecl>(this))
    773     Ty = D->getType();
    774   else if (const TypedefNameDecl *D = dyn_cast<TypedefNameDecl>(this))
    775     Ty = D->getUnderlyingType();
    776   else
    777     return nullptr;
    778 
    779   if (Ty->isFunctionPointerType())
    780     Ty = Ty->getAs<PointerType>()->getPointeeType();
    781   else if (BlocksToo && Ty->isBlockPointerType())
    782     Ty = Ty->getAs<BlockPointerType>()->getPointeeType();
    783 
    784   return Ty->getAs<FunctionType>();
    785 }
    786 
    787 
    788 /// Starting at a given context (a Decl or DeclContext), look for a
    789 /// code context that is not a closure (a lambda, block, etc.).
    790 template <class T> static Decl *getNonClosureContext(T *D) {
    791   if (getKind(D) == Decl::CXXMethod) {
    792     CXXMethodDecl *MD = cast<CXXMethodDecl>(D);
    793     if (MD->getOverloadedOperator() == OO_Call &&
    794         MD->getParent()->isLambda())
    795       return getNonClosureContext(MD->getParent()->getParent());
    796     return MD;
    797   } else if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
    798     return FD;
    799   } else if (ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
    800     return MD;
    801   } else if (BlockDecl *BD = dyn_cast<BlockDecl>(D)) {
    802     return getNonClosureContext(BD->getParent());
    803   } else if (CapturedDecl *CD = dyn_cast<CapturedDecl>(D)) {
    804     return getNonClosureContext(CD->getParent());
    805   } else {
    806     return nullptr;
    807   }
    808 }
    809 
    810 Decl *Decl::getNonClosureContext() {
    811   return ::getNonClosureContext(this);
    812 }
    813 
    814 Decl *DeclContext::getNonClosureAncestor() {
    815   return ::getNonClosureContext(this);
    816 }
    817 
    818 //===----------------------------------------------------------------------===//
    819 // DeclContext Implementation
    820 //===----------------------------------------------------------------------===//
    821 
    822 bool DeclContext::classof(const Decl *D) {
    823   switch (D->getKind()) {
    824 #define DECL(NAME, BASE)
    825 #define DECL_CONTEXT(NAME) case Decl::NAME:
    826 #define DECL_CONTEXT_BASE(NAME)
    827 #include "clang/AST/DeclNodes.inc"
    828       return true;
    829     default:
    830 #define DECL(NAME, BASE)
    831 #define DECL_CONTEXT_BASE(NAME)                 \
    832       if (D->getKind() >= Decl::first##NAME &&  \
    833           D->getKind() <= Decl::last##NAME)     \
    834         return true;
    835 #include "clang/AST/DeclNodes.inc"
    836       return false;
    837   }
    838 }
    839 
    840 DeclContext::~DeclContext() { }
    841 
    842 /// \brief Find the parent context of this context that will be
    843 /// used for unqualified name lookup.
    844 ///
    845 /// Generally, the parent lookup context is the semantic context. However, for
    846 /// a friend function the parent lookup context is the lexical context, which
    847 /// is the class in which the friend is declared.
    848 DeclContext *DeclContext::getLookupParent() {
    849   // FIXME: Find a better way to identify friends
    850   if (isa<FunctionDecl>(this))
    851     if (getParent()->getRedeclContext()->isFileContext() &&
    852         getLexicalParent()->getRedeclContext()->isRecord())
    853       return getLexicalParent();
    854 
    855   return getParent();
    856 }
    857 
    858 bool DeclContext::isInlineNamespace() const {
    859   return isNamespace() &&
    860          cast<NamespaceDecl>(this)->isInline();
    861 }
    862 
    863 bool DeclContext::isStdNamespace() const {
    864   if (!isNamespace())
    865     return false;
    866 
    867   const NamespaceDecl *ND = cast<NamespaceDecl>(this);
    868   if (ND->isInline()) {
    869     return ND->getParent()->isStdNamespace();
    870   }
    871 
    872   if (!getParent()->getRedeclContext()->isTranslationUnit())
    873     return false;
    874 
    875   const IdentifierInfo *II = ND->getIdentifier();
    876   return II && II->isStr("std");
    877 }
    878 
    879 bool DeclContext::isDependentContext() const {
    880   if (isFileContext())
    881     return false;
    882 
    883   if (isa<ClassTemplatePartialSpecializationDecl>(this))
    884     return true;
    885 
    886   if (const CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(this)) {
    887     if (Record->getDescribedClassTemplate())
    888       return true;
    889 
    890     if (Record->isDependentLambda())
    891       return true;
    892   }
    893 
    894   if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(this)) {
    895     if (Function->getDescribedFunctionTemplate())
    896       return true;
    897 
    898     // Friend function declarations are dependent if their *lexical*
    899     // context is dependent.
    900     if (cast<Decl>(this)->getFriendObjectKind())
    901       return getLexicalParent()->isDependentContext();
    902   }
    903 
    904   // FIXME: A variable template is a dependent context, but is not a
    905   // DeclContext. A context within it (such as a lambda-expression)
    906   // should be considered dependent.
    907 
    908   return getParent() && getParent()->isDependentContext();
    909 }
    910 
    911 bool DeclContext::isTransparentContext() const {
    912   if (DeclKind == Decl::Enum)
    913     return !cast<EnumDecl>(this)->isScoped();
    914   else if (DeclKind == Decl::LinkageSpec)
    915     return true;
    916 
    917   return false;
    918 }
    919 
    920 static bool isLinkageSpecContext(const DeclContext *DC,
    921                                  LinkageSpecDecl::LanguageIDs ID) {
    922   while (DC->getDeclKind() != Decl::TranslationUnit) {
    923     if (DC->getDeclKind() == Decl::LinkageSpec)
    924       return cast<LinkageSpecDecl>(DC)->getLanguage() == ID;
    925     DC = DC->getLexicalParent();
    926   }
    927   return false;
    928 }
    929 
    930 bool DeclContext::isExternCContext() const {
    931   return isLinkageSpecContext(this, clang::LinkageSpecDecl::lang_c);
    932 }
    933 
    934 bool DeclContext::isExternCXXContext() const {
    935   return isLinkageSpecContext(this, clang::LinkageSpecDecl::lang_cxx);
    936 }
    937 
    938 bool DeclContext::Encloses(const DeclContext *DC) const {
    939   if (getPrimaryContext() != this)
    940     return getPrimaryContext()->Encloses(DC);
    941 
    942   for (; DC; DC = DC->getParent())
    943     if (DC->getPrimaryContext() == this)
    944       return true;
    945   return false;
    946 }
    947 
    948 DeclContext *DeclContext::getPrimaryContext() {
    949   switch (DeclKind) {
    950   case Decl::TranslationUnit:
    951   case Decl::ExternCContext:
    952   case Decl::LinkageSpec:
    953   case Decl::Block:
    954   case Decl::Captured:
    955     // There is only one DeclContext for these entities.
    956     return this;
    957 
    958   case Decl::Namespace:
    959     // The original namespace is our primary context.
    960     return static_cast<NamespaceDecl*>(this)->getOriginalNamespace();
    961 
    962   case Decl::ObjCMethod:
    963     return this;
    964 
    965   case Decl::ObjCInterface:
    966     if (ObjCInterfaceDecl *Def = cast<ObjCInterfaceDecl>(this)->getDefinition())
    967       return Def;
    968 
    969     return this;
    970 
    971   case Decl::ObjCProtocol:
    972     if (ObjCProtocolDecl *Def = cast<ObjCProtocolDecl>(this)->getDefinition())
    973       return Def;
    974 
    975     return this;
    976 
    977   case Decl::ObjCCategory:
    978     return this;
    979 
    980   case Decl::ObjCImplementation:
    981   case Decl::ObjCCategoryImpl:
    982     return this;
    983 
    984   default:
    985     if (DeclKind >= Decl::firstTag && DeclKind <= Decl::lastTag) {
    986       // If this is a tag type that has a definition or is currently
    987       // being defined, that definition is our primary context.
    988       TagDecl *Tag = cast<TagDecl>(this);
    989 
    990       if (TagDecl *Def = Tag->getDefinition())
    991         return Def;
    992 
    993       if (const TagType *TagTy = dyn_cast<TagType>(Tag->getTypeForDecl())) {
    994         // Note, TagType::getDecl returns the (partial) definition one exists.
    995         TagDecl *PossiblePartialDef = TagTy->getDecl();
    996         if (PossiblePartialDef->isBeingDefined())
    997           return PossiblePartialDef;
    998       } else {
    999         assert(isa<InjectedClassNameType>(Tag->getTypeForDecl()));
   1000       }
   1001 
   1002       return Tag;
   1003     }
   1004 
   1005     assert(DeclKind >= Decl::firstFunction && DeclKind <= Decl::lastFunction &&
   1006           "Unknown DeclContext kind");
   1007     return this;
   1008   }
   1009 }
   1010 
   1011 void
   1012 DeclContext::collectAllContexts(SmallVectorImpl<DeclContext *> &Contexts){
   1013   Contexts.clear();
   1014 
   1015   if (DeclKind != Decl::Namespace) {
   1016     Contexts.push_back(this);
   1017     return;
   1018   }
   1019 
   1020   NamespaceDecl *Self = static_cast<NamespaceDecl *>(this);
   1021   for (NamespaceDecl *N = Self->getMostRecentDecl(); N;
   1022        N = N->getPreviousDecl())
   1023     Contexts.push_back(N);
   1024 
   1025   std::reverse(Contexts.begin(), Contexts.end());
   1026 }
   1027 
   1028 std::pair<Decl *, Decl *>
   1029 DeclContext::BuildDeclChain(ArrayRef<Decl*> Decls,
   1030                             bool FieldsAlreadyLoaded) {
   1031   // Build up a chain of declarations via the Decl::NextInContextAndBits field.
   1032   Decl *FirstNewDecl = nullptr;
   1033   Decl *PrevDecl = nullptr;
   1034   for (unsigned I = 0, N = Decls.size(); I != N; ++I) {
   1035     if (FieldsAlreadyLoaded && isa<FieldDecl>(Decls[I]))
   1036       continue;
   1037 
   1038     Decl *D = Decls[I];
   1039     if (PrevDecl)
   1040       PrevDecl->NextInContextAndBits.setPointer(D);
   1041     else
   1042       FirstNewDecl = D;
   1043 
   1044     PrevDecl = D;
   1045   }
   1046 
   1047   return std::make_pair(FirstNewDecl, PrevDecl);
   1048 }
   1049 
   1050 /// \brief We have just acquired external visible storage, and we already have
   1051 /// built a lookup map. For every name in the map, pull in the new names from
   1052 /// the external storage.
   1053 void DeclContext::reconcileExternalVisibleStorage() const {
   1054   assert(NeedToReconcileExternalVisibleStorage && LookupPtr);
   1055   NeedToReconcileExternalVisibleStorage = false;
   1056 
   1057   for (auto &Lookup : *LookupPtr)
   1058     Lookup.second.setHasExternalDecls();
   1059 }
   1060 
   1061 /// \brief Load the declarations within this lexical storage from an
   1062 /// external source.
   1063 /// \return \c true if any declarations were added.
   1064 bool
   1065 DeclContext::LoadLexicalDeclsFromExternalStorage() const {
   1066   ExternalASTSource *Source = getParentASTContext().getExternalSource();
   1067   assert(hasExternalLexicalStorage() && Source && "No external storage?");
   1068 
   1069   // Notify that we have a DeclContext that is initializing.
   1070   ExternalASTSource::Deserializing ADeclContext(Source);
   1071 
   1072   // Load the external declarations, if any.
   1073   SmallVector<Decl*, 64> Decls;
   1074   ExternalLexicalStorage = false;
   1075   Source->FindExternalLexicalDecls(this, Decls);
   1076 
   1077   if (Decls.empty())
   1078     return false;
   1079 
   1080   // We may have already loaded just the fields of this record, in which case
   1081   // we need to ignore them.
   1082   bool FieldsAlreadyLoaded = false;
   1083   if (const RecordDecl *RD = dyn_cast<RecordDecl>(this))
   1084     FieldsAlreadyLoaded = RD->LoadedFieldsFromExternalStorage;
   1085 
   1086   // Splice the newly-read declarations into the beginning of the list
   1087   // of declarations.
   1088   Decl *ExternalFirst, *ExternalLast;
   1089   std::tie(ExternalFirst, ExternalLast) =
   1090       BuildDeclChain(Decls, FieldsAlreadyLoaded);
   1091   ExternalLast->NextInContextAndBits.setPointer(FirstDecl);
   1092   FirstDecl = ExternalFirst;
   1093   if (!LastDecl)
   1094     LastDecl = ExternalLast;
   1095   return true;
   1096 }
   1097 
   1098 DeclContext::lookup_result
   1099 ExternalASTSource::SetNoExternalVisibleDeclsForName(const DeclContext *DC,
   1100                                                     DeclarationName Name) {
   1101   ASTContext &Context = DC->getParentASTContext();
   1102   StoredDeclsMap *Map;
   1103   if (!(Map = DC->LookupPtr))
   1104     Map = DC->CreateStoredDeclsMap(Context);
   1105   if (DC->NeedToReconcileExternalVisibleStorage)
   1106     DC->reconcileExternalVisibleStorage();
   1107 
   1108   (*Map)[Name].removeExternalDecls();
   1109 
   1110   return DeclContext::lookup_result();
   1111 }
   1112 
   1113 DeclContext::lookup_result
   1114 ExternalASTSource::SetExternalVisibleDeclsForName(const DeclContext *DC,
   1115                                                   DeclarationName Name,
   1116                                                   ArrayRef<NamedDecl*> Decls) {
   1117   ASTContext &Context = DC->getParentASTContext();
   1118   StoredDeclsMap *Map;
   1119   if (!(Map = DC->LookupPtr))
   1120     Map = DC->CreateStoredDeclsMap(Context);
   1121   if (DC->NeedToReconcileExternalVisibleStorage)
   1122     DC->reconcileExternalVisibleStorage();
   1123 
   1124   StoredDeclsList &List = (*Map)[Name];
   1125 
   1126   // Clear out any old external visible declarations, to avoid quadratic
   1127   // performance in the redeclaration checks below.
   1128   List.removeExternalDecls();
   1129 
   1130   if (!List.isNull()) {
   1131     // We have both existing declarations and new declarations for this name.
   1132     // Some of the declarations may simply replace existing ones. Handle those
   1133     // first.
   1134     llvm::SmallVector<unsigned, 8> Skip;
   1135     for (unsigned I = 0, N = Decls.size(); I != N; ++I)
   1136       if (List.HandleRedeclaration(Decls[I], /*IsKnownNewer*/false))
   1137         Skip.push_back(I);
   1138     Skip.push_back(Decls.size());
   1139 
   1140     // Add in any new declarations.
   1141     unsigned SkipPos = 0;
   1142     for (unsigned I = 0, N = Decls.size(); I != N; ++I) {
   1143       if (I == Skip[SkipPos])
   1144         ++SkipPos;
   1145       else
   1146         List.AddSubsequentDecl(Decls[I]);
   1147     }
   1148   } else {
   1149     // Convert the array to a StoredDeclsList.
   1150     for (ArrayRef<NamedDecl*>::iterator
   1151            I = Decls.begin(), E = Decls.end(); I != E; ++I) {
   1152       if (List.isNull())
   1153         List.setOnlyValue(*I);
   1154       else
   1155         List.AddSubsequentDecl(*I);
   1156     }
   1157   }
   1158 
   1159   return List.getLookupResult();
   1160 }
   1161 
   1162 DeclContext::decl_iterator DeclContext::decls_begin() const {
   1163   if (hasExternalLexicalStorage())
   1164     LoadLexicalDeclsFromExternalStorage();
   1165   return decl_iterator(FirstDecl);
   1166 }
   1167 
   1168 bool DeclContext::decls_empty() const {
   1169   if (hasExternalLexicalStorage())
   1170     LoadLexicalDeclsFromExternalStorage();
   1171 
   1172   return !FirstDecl;
   1173 }
   1174 
   1175 bool DeclContext::containsDecl(Decl *D) const {
   1176   return (D->getLexicalDeclContext() == this &&
   1177           (D->NextInContextAndBits.getPointer() || D == LastDecl));
   1178 }
   1179 
   1180 void DeclContext::removeDecl(Decl *D) {
   1181   assert(D->getLexicalDeclContext() == this &&
   1182          "decl being removed from non-lexical context");
   1183   assert((D->NextInContextAndBits.getPointer() || D == LastDecl) &&
   1184          "decl is not in decls list");
   1185 
   1186   // Remove D from the decl chain.  This is O(n) but hopefully rare.
   1187   if (D == FirstDecl) {
   1188     if (D == LastDecl)
   1189       FirstDecl = LastDecl = nullptr;
   1190     else
   1191       FirstDecl = D->NextInContextAndBits.getPointer();
   1192   } else {
   1193     for (Decl *I = FirstDecl; true; I = I->NextInContextAndBits.getPointer()) {
   1194       assert(I && "decl not found in linked list");
   1195       if (I->NextInContextAndBits.getPointer() == D) {
   1196         I->NextInContextAndBits.setPointer(D->NextInContextAndBits.getPointer());
   1197         if (D == LastDecl) LastDecl = I;
   1198         break;
   1199       }
   1200     }
   1201   }
   1202 
   1203   // Mark that D is no longer in the decl chain.
   1204   D->NextInContextAndBits.setPointer(nullptr);
   1205 
   1206   // Remove D from the lookup table if necessary.
   1207   if (isa<NamedDecl>(D)) {
   1208     NamedDecl *ND = cast<NamedDecl>(D);
   1209 
   1210     // Remove only decls that have a name
   1211     if (!ND->getDeclName()) return;
   1212 
   1213     auto *DC = this;
   1214     do {
   1215       StoredDeclsMap *Map = DC->getPrimaryContext()->LookupPtr;
   1216       if (Map) {
   1217         StoredDeclsMap::iterator Pos = Map->find(ND->getDeclName());
   1218         assert(Pos != Map->end() && "no lookup entry for decl");
   1219         if (Pos->second.getAsVector() || Pos->second.getAsDecl() == ND)
   1220           Pos->second.remove(ND);
   1221       }
   1222     } while (DC->isTransparentContext() && (DC = DC->getParent()));
   1223   }
   1224 }
   1225 
   1226 void DeclContext::addHiddenDecl(Decl *D) {
   1227   assert(D->getLexicalDeclContext() == this &&
   1228          "Decl inserted into wrong lexical context");
   1229   assert(!D->getNextDeclInContext() && D != LastDecl &&
   1230          "Decl already inserted into a DeclContext");
   1231 
   1232   if (FirstDecl) {
   1233     LastDecl->NextInContextAndBits.setPointer(D);
   1234     LastDecl = D;
   1235   } else {
   1236     FirstDecl = LastDecl = D;
   1237   }
   1238 
   1239   // Notify a C++ record declaration that we've added a member, so it can
   1240   // update its class-specific state.
   1241   if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(this))
   1242     Record->addedMember(D);
   1243 
   1244   // If this is a newly-created (not de-serialized) import declaration, wire
   1245   // it in to the list of local import declarations.
   1246   if (!D->isFromASTFile()) {
   1247     if (ImportDecl *Import = dyn_cast<ImportDecl>(D))
   1248       D->getASTContext().addedLocalImportDecl(Import);
   1249   }
   1250 }
   1251 
   1252 void DeclContext::addDecl(Decl *D) {
   1253   addHiddenDecl(D);
   1254 
   1255   if (NamedDecl *ND = dyn_cast<NamedDecl>(D))
   1256     ND->getDeclContext()->getPrimaryContext()->
   1257         makeDeclVisibleInContextWithFlags(ND, false, true);
   1258 }
   1259 
   1260 void DeclContext::addDeclInternal(Decl *D) {
   1261   addHiddenDecl(D);
   1262 
   1263   if (NamedDecl *ND = dyn_cast<NamedDecl>(D))
   1264     ND->getDeclContext()->getPrimaryContext()->
   1265         makeDeclVisibleInContextWithFlags(ND, true, true);
   1266 }
   1267 
   1268 /// shouldBeHidden - Determine whether a declaration which was declared
   1269 /// within its semantic context should be invisible to qualified name lookup.
   1270 static bool shouldBeHidden(NamedDecl *D) {
   1271   // Skip unnamed declarations.
   1272   if (!D->getDeclName())
   1273     return true;
   1274 
   1275   // Skip entities that can't be found by name lookup into a particular
   1276   // context.
   1277   if ((D->getIdentifierNamespace() == 0 && !isa<UsingDirectiveDecl>(D)) ||
   1278       D->isTemplateParameter())
   1279     return true;
   1280 
   1281   // Skip template specializations.
   1282   // FIXME: This feels like a hack. Should DeclarationName support
   1283   // template-ids, or is there a better way to keep specializations
   1284   // from being visible?
   1285   if (isa<ClassTemplateSpecializationDecl>(D))
   1286     return true;
   1287   if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
   1288     if (FD->isFunctionTemplateSpecialization())
   1289       return true;
   1290 
   1291   return false;
   1292 }
   1293 
   1294 /// buildLookup - Build the lookup data structure with all of the
   1295 /// declarations in this DeclContext (and any other contexts linked
   1296 /// to it or transparent contexts nested within it) and return it.
   1297 ///
   1298 /// Note that the produced map may miss out declarations from an
   1299 /// external source. If it does, those entries will be marked with
   1300 /// the 'hasExternalDecls' flag.
   1301 StoredDeclsMap *DeclContext::buildLookup() {
   1302   assert(this == getPrimaryContext() && "buildLookup called on non-primary DC");
   1303 
   1304   if (!HasLazyLocalLexicalLookups && !HasLazyExternalLexicalLookups)
   1305     return LookupPtr;
   1306 
   1307   SmallVector<DeclContext *, 2> Contexts;
   1308   collectAllContexts(Contexts);
   1309 
   1310   if (HasLazyExternalLexicalLookups) {
   1311     HasLazyExternalLexicalLookups = false;
   1312     for (auto *DC : Contexts) {
   1313       if (DC->hasExternalLexicalStorage())
   1314         HasLazyLocalLexicalLookups |=
   1315             DC->LoadLexicalDeclsFromExternalStorage();
   1316     }
   1317 
   1318     if (!HasLazyLocalLexicalLookups)
   1319       return LookupPtr;
   1320   }
   1321 
   1322   for (auto *DC : Contexts)
   1323     buildLookupImpl(DC, hasExternalVisibleStorage());
   1324 
   1325   // We no longer have any lazy decls.
   1326   HasLazyLocalLexicalLookups = false;
   1327   return LookupPtr;
   1328 }
   1329 
   1330 /// buildLookupImpl - Build part of the lookup data structure for the
   1331 /// declarations contained within DCtx, which will either be this
   1332 /// DeclContext, a DeclContext linked to it, or a transparent context
   1333 /// nested within it.
   1334 void DeclContext::buildLookupImpl(DeclContext *DCtx, bool Internal) {
   1335   for (Decl *D : DCtx->noload_decls()) {
   1336     // Insert this declaration into the lookup structure, but only if
   1337     // it's semantically within its decl context. Any other decls which
   1338     // should be found in this context are added eagerly.
   1339     //
   1340     // If it's from an AST file, don't add it now. It'll get handled by
   1341     // FindExternalVisibleDeclsByName if needed. Exception: if we're not
   1342     // in C++, we do not track external visible decls for the TU, so in
   1343     // that case we need to collect them all here.
   1344     if (NamedDecl *ND = dyn_cast<NamedDecl>(D))
   1345       if (ND->getDeclContext() == DCtx && !shouldBeHidden(ND) &&
   1346           (!ND->isFromASTFile() ||
   1347            (isTranslationUnit() &&
   1348             !getParentASTContext().getLangOpts().CPlusPlus)))
   1349         makeDeclVisibleInContextImpl(ND, Internal);
   1350 
   1351     // If this declaration is itself a transparent declaration context
   1352     // or inline namespace, add the members of this declaration of that
   1353     // context (recursively).
   1354     if (DeclContext *InnerCtx = dyn_cast<DeclContext>(D))
   1355       if (InnerCtx->isTransparentContext() || InnerCtx->isInlineNamespace())
   1356         buildLookupImpl(InnerCtx, Internal);
   1357   }
   1358 }
   1359 
   1360 NamedDecl *const DeclContextLookupResult::SingleElementDummyList = nullptr;
   1361 
   1362 DeclContext::lookup_result
   1363 DeclContext::lookup(DeclarationName Name) const {
   1364   assert(DeclKind != Decl::LinkageSpec &&
   1365          "Should not perform lookups into linkage specs!");
   1366 
   1367   const DeclContext *PrimaryContext = getPrimaryContext();
   1368   if (PrimaryContext != this)
   1369     return PrimaryContext->lookup(Name);
   1370 
   1371   // If we have an external source, ensure that any later redeclarations of this
   1372   // context have been loaded, since they may add names to the result of this
   1373   // lookup (or add external visible storage).
   1374   ExternalASTSource *Source = getParentASTContext().getExternalSource();
   1375   if (Source)
   1376     (void)cast<Decl>(this)->getMostRecentDecl();
   1377 
   1378   if (hasExternalVisibleStorage()) {
   1379     assert(Source && "external visible storage but no external source?");
   1380 
   1381     if (NeedToReconcileExternalVisibleStorage)
   1382       reconcileExternalVisibleStorage();
   1383 
   1384     StoredDeclsMap *Map = LookupPtr;
   1385 
   1386     if (HasLazyLocalLexicalLookups || HasLazyExternalLexicalLookups)
   1387       // FIXME: Make buildLookup const?
   1388       Map = const_cast<DeclContext*>(this)->buildLookup();
   1389 
   1390     if (!Map)
   1391       Map = CreateStoredDeclsMap(getParentASTContext());
   1392 
   1393     // If we have a lookup result with no external decls, we are done.
   1394     std::pair<StoredDeclsMap::iterator, bool> R =
   1395         Map->insert(std::make_pair(Name, StoredDeclsList()));
   1396     if (!R.second && !R.first->second.hasExternalDecls())
   1397       return R.first->second.getLookupResult();
   1398 
   1399     if (Source->FindExternalVisibleDeclsByName(this, Name) || !R.second) {
   1400       if (StoredDeclsMap *Map = LookupPtr) {
   1401         StoredDeclsMap::iterator I = Map->find(Name);
   1402         if (I != Map->end())
   1403           return I->second.getLookupResult();
   1404       }
   1405     }
   1406 
   1407     return lookup_result();
   1408   }
   1409 
   1410   StoredDeclsMap *Map = LookupPtr;
   1411   if (HasLazyLocalLexicalLookups || HasLazyExternalLexicalLookups)
   1412     Map = const_cast<DeclContext*>(this)->buildLookup();
   1413 
   1414   if (!Map)
   1415     return lookup_result();
   1416 
   1417   StoredDeclsMap::iterator I = Map->find(Name);
   1418   if (I == Map->end())
   1419     return lookup_result();
   1420 
   1421   return I->second.getLookupResult();
   1422 }
   1423 
   1424 DeclContext::lookup_result
   1425 DeclContext::noload_lookup(DeclarationName Name) {
   1426   assert(DeclKind != Decl::LinkageSpec &&
   1427          "Should not perform lookups into linkage specs!");
   1428 
   1429   DeclContext *PrimaryContext = getPrimaryContext();
   1430   if (PrimaryContext != this)
   1431     return PrimaryContext->noload_lookup(Name);
   1432 
   1433   // If we have any lazy lexical declarations not in our lookup map, add them
   1434   // now. Don't import any external declarations, not even if we know we have
   1435   // some missing from the external visible lookups.
   1436   if (HasLazyLocalLexicalLookups) {
   1437     SmallVector<DeclContext *, 2> Contexts;
   1438     collectAllContexts(Contexts);
   1439     for (unsigned I = 0, N = Contexts.size(); I != N; ++I)
   1440       buildLookupImpl(Contexts[I], hasExternalVisibleStorage());
   1441     HasLazyLocalLexicalLookups = false;
   1442   }
   1443 
   1444   StoredDeclsMap *Map = LookupPtr;
   1445   if (!Map)
   1446     return lookup_result();
   1447 
   1448   StoredDeclsMap::iterator I = Map->find(Name);
   1449   return I != Map->end() ? I->second.getLookupResult()
   1450                          : lookup_result();
   1451 }
   1452 
   1453 void DeclContext::localUncachedLookup(DeclarationName Name,
   1454                                       SmallVectorImpl<NamedDecl *> &Results) {
   1455   Results.clear();
   1456 
   1457   // If there's no external storage, just perform a normal lookup and copy
   1458   // the results.
   1459   if (!hasExternalVisibleStorage() && !hasExternalLexicalStorage() && Name) {
   1460     lookup_result LookupResults = lookup(Name);
   1461     Results.insert(Results.end(), LookupResults.begin(), LookupResults.end());
   1462     return;
   1463   }
   1464 
   1465   // If we have a lookup table, check there first. Maybe we'll get lucky.
   1466   // FIXME: Should we be checking these flags on the primary context?
   1467   if (Name && !HasLazyLocalLexicalLookups && !HasLazyExternalLexicalLookups) {
   1468     if (StoredDeclsMap *Map = LookupPtr) {
   1469       StoredDeclsMap::iterator Pos = Map->find(Name);
   1470       if (Pos != Map->end()) {
   1471         Results.insert(Results.end(),
   1472                        Pos->second.getLookupResult().begin(),
   1473                        Pos->second.getLookupResult().end());
   1474         return;
   1475       }
   1476     }
   1477   }
   1478 
   1479   // Slow case: grovel through the declarations in our chain looking for
   1480   // matches.
   1481   // FIXME: If we have lazy external declarations, this will not find them!
   1482   // FIXME: Should we CollectAllContexts and walk them all here?
   1483   for (Decl *D = FirstDecl; D; D = D->getNextDeclInContext()) {
   1484     if (NamedDecl *ND = dyn_cast<NamedDecl>(D))
   1485       if (ND->getDeclName() == Name)
   1486         Results.push_back(ND);
   1487   }
   1488 }
   1489 
   1490 DeclContext *DeclContext::getRedeclContext() {
   1491   DeclContext *Ctx = this;
   1492   // Skip through transparent contexts.
   1493   while (Ctx->isTransparentContext())
   1494     Ctx = Ctx->getParent();
   1495   return Ctx;
   1496 }
   1497 
   1498 DeclContext *DeclContext::getEnclosingNamespaceContext() {
   1499   DeclContext *Ctx = this;
   1500   // Skip through non-namespace, non-translation-unit contexts.
   1501   while (!Ctx->isFileContext())
   1502     Ctx = Ctx->getParent();
   1503   return Ctx->getPrimaryContext();
   1504 }
   1505 
   1506 RecordDecl *DeclContext::getOuterLexicalRecordContext() {
   1507   // Loop until we find a non-record context.
   1508   RecordDecl *OutermostRD = nullptr;
   1509   DeclContext *DC = this;
   1510   while (DC->isRecord()) {
   1511     OutermostRD = cast<RecordDecl>(DC);
   1512     DC = DC->getLexicalParent();
   1513   }
   1514   return OutermostRD;
   1515 }
   1516 
   1517 bool DeclContext::InEnclosingNamespaceSetOf(const DeclContext *O) const {
   1518   // For non-file contexts, this is equivalent to Equals.
   1519   if (!isFileContext())
   1520     return O->Equals(this);
   1521 
   1522   do {
   1523     if (O->Equals(this))
   1524       return true;
   1525 
   1526     const NamespaceDecl *NS = dyn_cast<NamespaceDecl>(O);
   1527     if (!NS || !NS->isInline())
   1528       break;
   1529     O = NS->getParent();
   1530   } while (O);
   1531 
   1532   return false;
   1533 }
   1534 
   1535 void DeclContext::makeDeclVisibleInContext(NamedDecl *D) {
   1536   DeclContext *PrimaryDC = this->getPrimaryContext();
   1537   DeclContext *DeclDC = D->getDeclContext()->getPrimaryContext();
   1538   // If the decl is being added outside of its semantic decl context, we
   1539   // need to ensure that we eagerly build the lookup information for it.
   1540   PrimaryDC->makeDeclVisibleInContextWithFlags(D, false, PrimaryDC == DeclDC);
   1541 }
   1542 
   1543 void DeclContext::makeDeclVisibleInContextWithFlags(NamedDecl *D, bool Internal,
   1544                                                     bool Recoverable) {
   1545   assert(this == getPrimaryContext() && "expected a primary DC");
   1546 
   1547   // Skip declarations within functions.
   1548   if (isFunctionOrMethod())
   1549     return;
   1550 
   1551   // Skip declarations which should be invisible to name lookup.
   1552   if (shouldBeHidden(D))
   1553     return;
   1554 
   1555   // If we already have a lookup data structure, perform the insertion into
   1556   // it. If we might have externally-stored decls with this name, look them
   1557   // up and perform the insertion. If this decl was declared outside its
   1558   // semantic context, buildLookup won't add it, so add it now.
   1559   //
   1560   // FIXME: As a performance hack, don't add such decls into the translation
   1561   // unit unless we're in C++, since qualified lookup into the TU is never
   1562   // performed.
   1563   if (LookupPtr || hasExternalVisibleStorage() ||
   1564       ((!Recoverable || D->getDeclContext() != D->getLexicalDeclContext()) &&
   1565        (getParentASTContext().getLangOpts().CPlusPlus ||
   1566         !isTranslationUnit()))) {
   1567     // If we have lazily omitted any decls, they might have the same name as
   1568     // the decl which we are adding, so build a full lookup table before adding
   1569     // this decl.
   1570     buildLookup();
   1571     makeDeclVisibleInContextImpl(D, Internal);
   1572   } else {
   1573     HasLazyLocalLexicalLookups = true;
   1574   }
   1575 
   1576   // If we are a transparent context or inline namespace, insert into our
   1577   // parent context, too. This operation is recursive.
   1578   if (isTransparentContext() || isInlineNamespace())
   1579     getParent()->getPrimaryContext()->
   1580         makeDeclVisibleInContextWithFlags(D, Internal, Recoverable);
   1581 
   1582   Decl *DCAsDecl = cast<Decl>(this);
   1583   // Notify that a decl was made visible unless we are a Tag being defined.
   1584   if (!(isa<TagDecl>(DCAsDecl) && cast<TagDecl>(DCAsDecl)->isBeingDefined()))
   1585     if (ASTMutationListener *L = DCAsDecl->getASTMutationListener())
   1586       L->AddedVisibleDecl(this, D);
   1587 }
   1588 
   1589 void DeclContext::makeDeclVisibleInContextImpl(NamedDecl *D, bool Internal) {
   1590   // Find or create the stored declaration map.
   1591   StoredDeclsMap *Map = LookupPtr;
   1592   if (!Map) {
   1593     ASTContext *C = &getParentASTContext();
   1594     Map = CreateStoredDeclsMap(*C);
   1595   }
   1596 
   1597   // If there is an external AST source, load any declarations it knows about
   1598   // with this declaration's name.
   1599   // If the lookup table contains an entry about this name it means that we
   1600   // have already checked the external source.
   1601   if (!Internal)
   1602     if (ExternalASTSource *Source = getParentASTContext().getExternalSource())
   1603       if (hasExternalVisibleStorage() &&
   1604           Map->find(D->getDeclName()) == Map->end())
   1605         Source->FindExternalVisibleDeclsByName(this, D->getDeclName());
   1606 
   1607   // Insert this declaration into the map.
   1608   StoredDeclsList &DeclNameEntries = (*Map)[D->getDeclName()];
   1609 
   1610   if (Internal) {
   1611     // If this is being added as part of loading an external declaration,
   1612     // this may not be the only external declaration with this name.
   1613     // In this case, we never try to replace an existing declaration; we'll
   1614     // handle that when we finalize the list of declarations for this name.
   1615     DeclNameEntries.setHasExternalDecls();
   1616     DeclNameEntries.AddSubsequentDecl(D);
   1617     return;
   1618   }
   1619 
   1620   if (DeclNameEntries.isNull()) {
   1621     DeclNameEntries.setOnlyValue(D);
   1622     return;
   1623   }
   1624 
   1625   if (DeclNameEntries.HandleRedeclaration(D, /*IsKnownNewer*/!Internal)) {
   1626     // This declaration has replaced an existing one for which
   1627     // declarationReplaces returns true.
   1628     return;
   1629   }
   1630 
   1631   // Put this declaration into the appropriate slot.
   1632   DeclNameEntries.AddSubsequentDecl(D);
   1633 }
   1634 
   1635 UsingDirectiveDecl *DeclContext::udir_iterator::operator*() const {
   1636   return cast<UsingDirectiveDecl>(*I);
   1637 }
   1638 
   1639 /// Returns iterator range [First, Last) of UsingDirectiveDecls stored within
   1640 /// this context.
   1641 DeclContext::udir_range DeclContext::using_directives() const {
   1642   // FIXME: Use something more efficient than normal lookup for using
   1643   // directives. In C++, using directives are looked up more than anything else.
   1644   lookup_result Result = lookup(UsingDirectiveDecl::getName());
   1645   return udir_range(Result.begin(), Result.end());
   1646 }
   1647 
   1648 //===----------------------------------------------------------------------===//
   1649 // Creation and Destruction of StoredDeclsMaps.                               //
   1650 //===----------------------------------------------------------------------===//
   1651 
   1652 StoredDeclsMap *DeclContext::CreateStoredDeclsMap(ASTContext &C) const {
   1653   assert(!LookupPtr && "context already has a decls map");
   1654   assert(getPrimaryContext() == this &&
   1655          "creating decls map on non-primary context");
   1656 
   1657   StoredDeclsMap *M;
   1658   bool Dependent = isDependentContext();
   1659   if (Dependent)
   1660     M = new DependentStoredDeclsMap();
   1661   else
   1662     M = new StoredDeclsMap();
   1663   M->Previous = C.LastSDM;
   1664   C.LastSDM = llvm::PointerIntPair<StoredDeclsMap*,1>(M, Dependent);
   1665   LookupPtr = M;
   1666   return M;
   1667 }
   1668 
   1669 void ASTContext::ReleaseDeclContextMaps() {
   1670   // It's okay to delete DependentStoredDeclsMaps via a StoredDeclsMap
   1671   // pointer because the subclass doesn't add anything that needs to
   1672   // be deleted.
   1673   StoredDeclsMap::DestroyAll(LastSDM.getPointer(), LastSDM.getInt());
   1674 }
   1675 
   1676 void StoredDeclsMap::DestroyAll(StoredDeclsMap *Map, bool Dependent) {
   1677   while (Map) {
   1678     // Advance the iteration before we invalidate memory.
   1679     llvm::PointerIntPair<StoredDeclsMap*,1> Next = Map->Previous;
   1680 
   1681     if (Dependent)
   1682       delete static_cast<DependentStoredDeclsMap*>(Map);
   1683     else
   1684       delete Map;
   1685 
   1686     Map = Next.getPointer();
   1687     Dependent = Next.getInt();
   1688   }
   1689 }
   1690 
   1691 DependentDiagnostic *DependentDiagnostic::Create(ASTContext &C,
   1692                                                  DeclContext *Parent,
   1693                                            const PartialDiagnostic &PDiag) {
   1694   assert(Parent->isDependentContext()
   1695          && "cannot iterate dependent diagnostics of non-dependent context");
   1696   Parent = Parent->getPrimaryContext();
   1697   if (!Parent->LookupPtr)
   1698     Parent->CreateStoredDeclsMap(C);
   1699 
   1700   DependentStoredDeclsMap *Map =
   1701       static_cast<DependentStoredDeclsMap *>(Parent->LookupPtr);
   1702 
   1703   // Allocate the copy of the PartialDiagnostic via the ASTContext's
   1704   // BumpPtrAllocator, rather than the ASTContext itself.
   1705   PartialDiagnostic::Storage *DiagStorage = nullptr;
   1706   if (PDiag.hasStorage())
   1707     DiagStorage = new (C) PartialDiagnostic::Storage;
   1708 
   1709   DependentDiagnostic *DD = new (C) DependentDiagnostic(PDiag, DiagStorage);
   1710 
   1711   // TODO: Maybe we shouldn't reverse the order during insertion.
   1712   DD->NextDiagnostic = Map->FirstDiagnostic;
   1713   Map->FirstDiagnostic = DD;
   1714 
   1715   return DD;
   1716 }
   1717