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      1 //===--- Sema.cpp - AST Builder and Semantic Analysis 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 actions class which performs semantic analysis and
     11 // builds an AST out of a parse stream.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "clang/Sema/SemaInternal.h"
     16 #include "clang/AST/ASTContext.h"
     17 #include "clang/AST/ASTDiagnostic.h"
     18 #include "clang/AST/DeclCXX.h"
     19 #include "clang/AST/DeclFriend.h"
     20 #include "clang/AST/DeclObjC.h"
     21 #include "clang/AST/Expr.h"
     22 #include "clang/AST/ExprCXX.h"
     23 #include "clang/AST/StmtCXX.h"
     24 #include "clang/Basic/DiagnosticOptions.h"
     25 #include "clang/Basic/FileManager.h"
     26 #include "clang/Basic/PartialDiagnostic.h"
     27 #include "clang/Basic/TargetInfo.h"
     28 #include "clang/Lex/HeaderSearch.h"
     29 #include "clang/Lex/Preprocessor.h"
     30 #include "clang/Sema/CXXFieldCollector.h"
     31 #include "clang/Sema/DelayedDiagnostic.h"
     32 #include "clang/Sema/ExternalSemaSource.h"
     33 #include "clang/Sema/MultiplexExternalSemaSource.h"
     34 #include "clang/Sema/ObjCMethodList.h"
     35 #include "clang/Sema/PrettyDeclStackTrace.h"
     36 #include "clang/Sema/Scope.h"
     37 #include "clang/Sema/ScopeInfo.h"
     38 #include "clang/Sema/SemaConsumer.h"
     39 #include "clang/Sema/TemplateDeduction.h"
     40 #include "llvm/ADT/APFloat.h"
     41 #include "llvm/ADT/DenseMap.h"
     42 #include "llvm/ADT/SmallSet.h"
     43 using namespace clang;
     44 using namespace sema;
     45 
     46 SourceLocation Sema::getLocForEndOfToken(SourceLocation Loc, unsigned Offset) {
     47   return Lexer::getLocForEndOfToken(Loc, Offset, SourceMgr, LangOpts);
     48 }
     49 
     50 ModuleLoader &Sema::getModuleLoader() const { return PP.getModuleLoader(); }
     51 
     52 PrintingPolicy Sema::getPrintingPolicy(const ASTContext &Context,
     53                                        const Preprocessor &PP) {
     54   PrintingPolicy Policy = Context.getPrintingPolicy();
     55   Policy.Bool = Context.getLangOpts().Bool;
     56   if (!Policy.Bool) {
     57     if (const MacroInfo *
     58           BoolMacro = PP.getMacroInfo(&Context.Idents.get("bool"))) {
     59       Policy.Bool = BoolMacro->isObjectLike() &&
     60         BoolMacro->getNumTokens() == 1 &&
     61         BoolMacro->getReplacementToken(0).is(tok::kw__Bool);
     62     }
     63   }
     64 
     65   return Policy;
     66 }
     67 
     68 void Sema::ActOnTranslationUnitScope(Scope *S) {
     69   TUScope = S;
     70   PushDeclContext(S, Context.getTranslationUnitDecl());
     71 }
     72 
     73 Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
     74            TranslationUnitKind TUKind,
     75            CodeCompleteConsumer *CodeCompleter)
     76   : ExternalSource(nullptr),
     77     isMultiplexExternalSource(false), FPFeatures(pp.getLangOpts()),
     78     LangOpts(pp.getLangOpts()), PP(pp), Context(ctxt), Consumer(consumer),
     79     Diags(PP.getDiagnostics()), SourceMgr(PP.getSourceManager()),
     80     CollectStats(false), CodeCompleter(CodeCompleter),
     81     CurContext(nullptr), OriginalLexicalContext(nullptr),
     82     PackContext(nullptr), MSStructPragmaOn(false),
     83     MSPointerToMemberRepresentationMethod(
     84         LangOpts.getMSPointerToMemberRepresentationMethod()),
     85     VtorDispModeStack(1, MSVtorDispAttr::Mode(LangOpts.VtorDispMode)),
     86     DataSegStack(nullptr), BSSSegStack(nullptr), ConstSegStack(nullptr),
     87     CodeSegStack(nullptr), CurInitSeg(nullptr), VisContext(nullptr),
     88     IsBuildingRecoveryCallExpr(false),
     89     ExprNeedsCleanups(false), LateTemplateParser(nullptr),
     90     LateTemplateParserCleanup(nullptr),
     91     OpaqueParser(nullptr), IdResolver(pp), StdInitializerList(nullptr),
     92     CXXTypeInfoDecl(nullptr), MSVCGuidDecl(nullptr),
     93     NSNumberDecl(nullptr), NSValueDecl(nullptr),
     94     NSStringDecl(nullptr), StringWithUTF8StringMethod(nullptr),
     95     ValueWithBytesObjCTypeMethod(nullptr),
     96     NSArrayDecl(nullptr), ArrayWithObjectsMethod(nullptr),
     97     NSDictionaryDecl(nullptr), DictionaryWithObjectsMethod(nullptr),
     98     MSAsmLabelNameCounter(0),
     99     GlobalNewDeleteDeclared(false),
    100     TUKind(TUKind),
    101     NumSFINAEErrors(0),
    102     CachedFakeTopLevelModule(nullptr),
    103     AccessCheckingSFINAE(false), InNonInstantiationSFINAEContext(false),
    104     NonInstantiationEntries(0), ArgumentPackSubstitutionIndex(-1),
    105     CurrentInstantiationScope(nullptr), DisableTypoCorrection(false),
    106     TyposCorrected(0), AnalysisWarnings(*this), ThreadSafetyDeclCache(nullptr),
    107     VarDataSharingAttributesStack(nullptr), CurScope(nullptr),
    108     Ident_super(nullptr), Ident___float128(nullptr)
    109 {
    110   TUScope = nullptr;
    111 
    112   LoadedExternalKnownNamespaces = false;
    113   for (unsigned I = 0; I != NSAPI::NumNSNumberLiteralMethods; ++I)
    114     NSNumberLiteralMethods[I] = nullptr;
    115 
    116   if (getLangOpts().ObjC1)
    117     NSAPIObj.reset(new NSAPI(Context));
    118 
    119   if (getLangOpts().CPlusPlus)
    120     FieldCollector.reset(new CXXFieldCollector());
    121 
    122   // Tell diagnostics how to render things from the AST library.
    123   Diags.SetArgToStringFn(&FormatASTNodeDiagnosticArgument, &Context);
    124 
    125   ExprEvalContexts.emplace_back(PotentiallyEvaluated, 0, false, nullptr, false);
    126 
    127   FunctionScopes.push_back(new FunctionScopeInfo(Diags));
    128 
    129   // Initilization of data sharing attributes stack for OpenMP
    130   InitDataSharingAttributesStack();
    131 }
    132 
    133 void Sema::addImplicitTypedef(StringRef Name, QualType T) {
    134   DeclarationName DN = &Context.Idents.get(Name);
    135   if (IdResolver.begin(DN) == IdResolver.end())
    136     PushOnScopeChains(Context.buildImplicitTypedef(T, Name), TUScope);
    137 }
    138 
    139 void Sema::Initialize() {
    140   if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
    141     SC->InitializeSema(*this);
    142 
    143   // Tell the external Sema source about this Sema object.
    144   if (ExternalSemaSource *ExternalSema
    145       = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
    146     ExternalSema->InitializeSema(*this);
    147 
    148   // This needs to happen after ExternalSemaSource::InitializeSema(this) or we
    149   // will not be able to merge any duplicate __va_list_tag decls correctly.
    150   VAListTagName = PP.getIdentifierInfo("__va_list_tag");
    151 
    152   if (!TUScope)
    153     return;
    154 
    155   // Initialize predefined 128-bit integer types, if needed.
    156   if (Context.getTargetInfo().hasInt128Type()) {
    157     // If either of the 128-bit integer types are unavailable to name lookup,
    158     // define them now.
    159     DeclarationName Int128 = &Context.Idents.get("__int128_t");
    160     if (IdResolver.begin(Int128) == IdResolver.end())
    161       PushOnScopeChains(Context.getInt128Decl(), TUScope);
    162 
    163     DeclarationName UInt128 = &Context.Idents.get("__uint128_t");
    164     if (IdResolver.begin(UInt128) == IdResolver.end())
    165       PushOnScopeChains(Context.getUInt128Decl(), TUScope);
    166   }
    167 
    168 
    169   // Initialize predefined Objective-C types:
    170   if (getLangOpts().ObjC1) {
    171     // If 'SEL' does not yet refer to any declarations, make it refer to the
    172     // predefined 'SEL'.
    173     DeclarationName SEL = &Context.Idents.get("SEL");
    174     if (IdResolver.begin(SEL) == IdResolver.end())
    175       PushOnScopeChains(Context.getObjCSelDecl(), TUScope);
    176 
    177     // If 'id' does not yet refer to any declarations, make it refer to the
    178     // predefined 'id'.
    179     DeclarationName Id = &Context.Idents.get("id");
    180     if (IdResolver.begin(Id) == IdResolver.end())
    181       PushOnScopeChains(Context.getObjCIdDecl(), TUScope);
    182 
    183     // Create the built-in typedef for 'Class'.
    184     DeclarationName Class = &Context.Idents.get("Class");
    185     if (IdResolver.begin(Class) == IdResolver.end())
    186       PushOnScopeChains(Context.getObjCClassDecl(), TUScope);
    187 
    188     // Create the built-in forward declaratino for 'Protocol'.
    189     DeclarationName Protocol = &Context.Idents.get("Protocol");
    190     if (IdResolver.begin(Protocol) == IdResolver.end())
    191       PushOnScopeChains(Context.getObjCProtocolDecl(), TUScope);
    192   }
    193 
    194   // Initialize Microsoft "predefined C++ types".
    195   if (getLangOpts().MSVCCompat) {
    196     if (getLangOpts().CPlusPlus &&
    197         IdResolver.begin(&Context.Idents.get("type_info")) == IdResolver.end())
    198       PushOnScopeChains(Context.buildImplicitRecord("type_info", TTK_Class),
    199                         TUScope);
    200 
    201     addImplicitTypedef("size_t", Context.getSizeType());
    202   }
    203 
    204   // Initialize predefined OpenCL types.
    205   if (getLangOpts().OpenCL) {
    206     addImplicitTypedef("image1d_t", Context.OCLImage1dTy);
    207     addImplicitTypedef("image1d_array_t", Context.OCLImage1dArrayTy);
    208     addImplicitTypedef("image1d_buffer_t", Context.OCLImage1dBufferTy);
    209     addImplicitTypedef("image2d_t", Context.OCLImage2dTy);
    210     addImplicitTypedef("image2d_array_t", Context.OCLImage2dArrayTy);
    211     addImplicitTypedef("image3d_t", Context.OCLImage3dTy);
    212     addImplicitTypedef("sampler_t", Context.OCLSamplerTy);
    213     addImplicitTypedef("event_t", Context.OCLEventTy);
    214     if (getLangOpts().OpenCLVersion >= 200) {
    215       addImplicitTypedef("image2d_depth_t", Context.OCLImage2dDepthTy);
    216       addImplicitTypedef("image2d_array_depth_t",
    217                          Context.OCLImage2dArrayDepthTy);
    218       addImplicitTypedef("image2d_msaa_t", Context.OCLImage2dMSAATy);
    219       addImplicitTypedef("image2d_array_msaa_t", Context.OCLImage2dArrayMSAATy);
    220       addImplicitTypedef("image2d_msaa_depth_t", Context.OCLImage2dMSAADepthTy);
    221       addImplicitTypedef("image2d_array_msaa_depth_t",
    222                          Context.OCLImage2dArrayMSAADepthTy);
    223       addImplicitTypedef("clk_event_t", Context.OCLClkEventTy);
    224       addImplicitTypedef("queue_t", Context.OCLQueueTy);
    225       addImplicitTypedef("ndrange_t", Context.OCLNDRangeTy);
    226       addImplicitTypedef("reserve_id_t", Context.OCLReserveIDTy);
    227       addImplicitTypedef("atomic_int", Context.getAtomicType(Context.IntTy));
    228       addImplicitTypedef("atomic_uint",
    229                          Context.getAtomicType(Context.UnsignedIntTy));
    230       addImplicitTypedef("atomic_long", Context.getAtomicType(Context.LongTy));
    231       addImplicitTypedef("atomic_ulong",
    232                          Context.getAtomicType(Context.UnsignedLongTy));
    233       addImplicitTypedef("atomic_float",
    234                          Context.getAtomicType(Context.FloatTy));
    235       addImplicitTypedef("atomic_double",
    236                          Context.getAtomicType(Context.DoubleTy));
    237       // OpenCLC v2.0, s6.13.11.6 requires that atomic_flag is implemented as
    238       // 32-bit integer and OpenCLC v2.0, s6.1.1 int is always 32-bit wide.
    239       addImplicitTypedef("atomic_flag", Context.getAtomicType(Context.IntTy));
    240       addImplicitTypedef("atomic_intptr_t",
    241                          Context.getAtomicType(Context.getIntPtrType()));
    242       addImplicitTypedef("atomic_uintptr_t",
    243                          Context.getAtomicType(Context.getUIntPtrType()));
    244       addImplicitTypedef("atomic_size_t",
    245                          Context.getAtomicType(Context.getSizeType()));
    246       addImplicitTypedef("atomic_ptrdiff_t",
    247                          Context.getAtomicType(Context.getPointerDiffType()));
    248     }
    249   }
    250 
    251   if (Context.getTargetInfo().hasBuiltinMSVaList()) {
    252     DeclarationName MSVaList = &Context.Idents.get("__builtin_ms_va_list");
    253     if (IdResolver.begin(MSVaList) == IdResolver.end())
    254       PushOnScopeChains(Context.getBuiltinMSVaListDecl(), TUScope);
    255   }
    256 
    257   DeclarationName BuiltinVaList = &Context.Idents.get("__builtin_va_list");
    258   if (IdResolver.begin(BuiltinVaList) == IdResolver.end())
    259     PushOnScopeChains(Context.getBuiltinVaListDecl(), TUScope);
    260 }
    261 
    262 Sema::~Sema() {
    263   llvm::DeleteContainerSeconds(LateParsedTemplateMap);
    264   if (PackContext) FreePackedContext();
    265   if (VisContext) FreeVisContext();
    266   // Kill all the active scopes.
    267   for (unsigned I = 1, E = FunctionScopes.size(); I != E; ++I)
    268     delete FunctionScopes[I];
    269   if (FunctionScopes.size() == 1)
    270     delete FunctionScopes[0];
    271 
    272   // Tell the SemaConsumer to forget about us; we're going out of scope.
    273   if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
    274     SC->ForgetSema();
    275 
    276   // Detach from the external Sema source.
    277   if (ExternalSemaSource *ExternalSema
    278         = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
    279     ExternalSema->ForgetSema();
    280 
    281   // If Sema's ExternalSource is the multiplexer - we own it.
    282   if (isMultiplexExternalSource)
    283     delete ExternalSource;
    284 
    285   threadSafety::threadSafetyCleanup(ThreadSafetyDeclCache);
    286 
    287   // Destroys data sharing attributes stack for OpenMP
    288   DestroyDataSharingAttributesStack();
    289 
    290   assert(DelayedTypos.empty() && "Uncorrected typos!");
    291 }
    292 
    293 /// makeUnavailableInSystemHeader - There is an error in the current
    294 /// context.  If we're still in a system header, and we can plausibly
    295 /// make the relevant declaration unavailable instead of erroring, do
    296 /// so and return true.
    297 bool Sema::makeUnavailableInSystemHeader(SourceLocation loc,
    298                                       UnavailableAttr::ImplicitReason reason) {
    299   // If we're not in a function, it's an error.
    300   FunctionDecl *fn = dyn_cast<FunctionDecl>(CurContext);
    301   if (!fn) return false;
    302 
    303   // If we're in template instantiation, it's an error.
    304   if (!ActiveTemplateInstantiations.empty())
    305     return false;
    306 
    307   // If that function's not in a system header, it's an error.
    308   if (!Context.getSourceManager().isInSystemHeader(loc))
    309     return false;
    310 
    311   // If the function is already unavailable, it's not an error.
    312   if (fn->hasAttr<UnavailableAttr>()) return true;
    313 
    314   fn->addAttr(UnavailableAttr::CreateImplicit(Context, "", reason, loc));
    315   return true;
    316 }
    317 
    318 ASTMutationListener *Sema::getASTMutationListener() const {
    319   return getASTConsumer().GetASTMutationListener();
    320 }
    321 
    322 ///\brief Registers an external source. If an external source already exists,
    323 /// creates a multiplex external source and appends to it.
    324 ///
    325 ///\param[in] E - A non-null external sema source.
    326 ///
    327 void Sema::addExternalSource(ExternalSemaSource *E) {
    328   assert(E && "Cannot use with NULL ptr");
    329 
    330   if (!ExternalSource) {
    331     ExternalSource = E;
    332     return;
    333   }
    334 
    335   if (isMultiplexExternalSource)
    336     static_cast<MultiplexExternalSemaSource*>(ExternalSource)->addSource(*E);
    337   else {
    338     ExternalSource = new MultiplexExternalSemaSource(*ExternalSource, *E);
    339     isMultiplexExternalSource = true;
    340   }
    341 }
    342 
    343 /// \brief Print out statistics about the semantic analysis.
    344 void Sema::PrintStats() const {
    345   llvm::errs() << "\n*** Semantic Analysis Stats:\n";
    346   llvm::errs() << NumSFINAEErrors << " SFINAE diagnostics trapped.\n";
    347 
    348   BumpAlloc.PrintStats();
    349   AnalysisWarnings.PrintStats();
    350 }
    351 
    352 void Sema::diagnoseNullableToNonnullConversion(QualType DstType,
    353                                                QualType SrcType,
    354                                                SourceLocation Loc) {
    355   Optional<NullabilityKind> ExprNullability = SrcType->getNullability(Context);
    356   if (!ExprNullability || *ExprNullability != NullabilityKind::Nullable)
    357     return;
    358 
    359   Optional<NullabilityKind> TypeNullability = DstType->getNullability(Context);
    360   if (!TypeNullability || *TypeNullability != NullabilityKind::NonNull)
    361     return;
    362 
    363   Diag(Loc, diag::warn_nullability_lost) << SrcType << DstType;
    364 }
    365 
    366 /// ImpCastExprToType - If Expr is not of type 'Type', insert an implicit cast.
    367 /// If there is already an implicit cast, merge into the existing one.
    368 /// The result is of the given category.
    369 ExprResult Sema::ImpCastExprToType(Expr *E, QualType Ty,
    370                                    CastKind Kind, ExprValueKind VK,
    371                                    const CXXCastPath *BasePath,
    372                                    CheckedConversionKind CCK) {
    373 #ifndef NDEBUG
    374   if (VK == VK_RValue && !E->isRValue()) {
    375     switch (Kind) {
    376     default:
    377       llvm_unreachable("can't implicitly cast lvalue to rvalue with this cast "
    378                        "kind");
    379     case CK_LValueToRValue:
    380     case CK_ArrayToPointerDecay:
    381     case CK_FunctionToPointerDecay:
    382     case CK_ToVoid:
    383       break;
    384     }
    385   }
    386   assert((VK == VK_RValue || !E->isRValue()) && "can't cast rvalue to lvalue");
    387 #endif
    388 
    389   diagnoseNullableToNonnullConversion(Ty, E->getType(), E->getLocStart());
    390 
    391   QualType ExprTy = Context.getCanonicalType(E->getType());
    392   QualType TypeTy = Context.getCanonicalType(Ty);
    393 
    394   if (ExprTy == TypeTy)
    395     return E;
    396 
    397   if (ImplicitCastExpr *ImpCast = dyn_cast<ImplicitCastExpr>(E)) {
    398     if (ImpCast->getCastKind() == Kind && (!BasePath || BasePath->empty())) {
    399       ImpCast->setType(Ty);
    400       ImpCast->setValueKind(VK);
    401       return E;
    402     }
    403   }
    404 
    405   return ImplicitCastExpr::Create(Context, Ty, Kind, E, BasePath, VK);
    406 }
    407 
    408 /// ScalarTypeToBooleanCastKind - Returns the cast kind corresponding
    409 /// to the conversion from scalar type ScalarTy to the Boolean type.
    410 CastKind Sema::ScalarTypeToBooleanCastKind(QualType ScalarTy) {
    411   switch (ScalarTy->getScalarTypeKind()) {
    412   case Type::STK_Bool: return CK_NoOp;
    413   case Type::STK_CPointer: return CK_PointerToBoolean;
    414   case Type::STK_BlockPointer: return CK_PointerToBoolean;
    415   case Type::STK_ObjCObjectPointer: return CK_PointerToBoolean;
    416   case Type::STK_MemberPointer: return CK_MemberPointerToBoolean;
    417   case Type::STK_Integral: return CK_IntegralToBoolean;
    418   case Type::STK_Floating: return CK_FloatingToBoolean;
    419   case Type::STK_IntegralComplex: return CK_IntegralComplexToBoolean;
    420   case Type::STK_FloatingComplex: return CK_FloatingComplexToBoolean;
    421   }
    422   return CK_Invalid;
    423 }
    424 
    425 /// \brief Used to prune the decls of Sema's UnusedFileScopedDecls vector.
    426 static bool ShouldRemoveFromUnused(Sema *SemaRef, const DeclaratorDecl *D) {
    427   if (D->getMostRecentDecl()->isUsed())
    428     return true;
    429 
    430   if (D->isExternallyVisible())
    431     return true;
    432 
    433   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
    434     // UnusedFileScopedDecls stores the first declaration.
    435     // The declaration may have become definition so check again.
    436     const FunctionDecl *DeclToCheck;
    437     if (FD->hasBody(DeclToCheck))
    438       return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
    439 
    440     // Later redecls may add new information resulting in not having to warn,
    441     // so check again.
    442     DeclToCheck = FD->getMostRecentDecl();
    443     if (DeclToCheck != FD)
    444       return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
    445   }
    446 
    447   if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
    448     // If a variable usable in constant expressions is referenced,
    449     // don't warn if it isn't used: if the value of a variable is required
    450     // for the computation of a constant expression, it doesn't make sense to
    451     // warn even if the variable isn't odr-used.  (isReferenced doesn't
    452     // precisely reflect that, but it's a decent approximation.)
    453     if (VD->isReferenced() &&
    454         VD->isUsableInConstantExpressions(SemaRef->Context))
    455       return true;
    456 
    457     // UnusedFileScopedDecls stores the first declaration.
    458     // The declaration may have become definition so check again.
    459     const VarDecl *DeclToCheck = VD->getDefinition();
    460     if (DeclToCheck)
    461       return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
    462 
    463     // Later redecls may add new information resulting in not having to warn,
    464     // so check again.
    465     DeclToCheck = VD->getMostRecentDecl();
    466     if (DeclToCheck != VD)
    467       return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
    468   }
    469 
    470   return false;
    471 }
    472 
    473 /// Obtains a sorted list of functions that are undefined but ODR-used.
    474 void Sema::getUndefinedButUsed(
    475     SmallVectorImpl<std::pair<NamedDecl *, SourceLocation> > &Undefined) {
    476   for (llvm::DenseMap<NamedDecl *, SourceLocation>::iterator
    477          I = UndefinedButUsed.begin(), E = UndefinedButUsed.end();
    478        I != E; ++I) {
    479     NamedDecl *ND = I->first;
    480 
    481     // Ignore attributes that have become invalid.
    482     if (ND->isInvalidDecl()) continue;
    483 
    484     // __attribute__((weakref)) is basically a definition.
    485     if (ND->hasAttr<WeakRefAttr>()) continue;
    486 
    487     if (FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
    488       if (FD->isDefined())
    489         continue;
    490       if (FD->isExternallyVisible() &&
    491           !FD->getMostRecentDecl()->isInlined())
    492         continue;
    493     } else {
    494       if (cast<VarDecl>(ND)->hasDefinition() != VarDecl::DeclarationOnly)
    495         continue;
    496       if (ND->isExternallyVisible())
    497         continue;
    498     }
    499 
    500     Undefined.push_back(std::make_pair(ND, I->second));
    501   }
    502 
    503   // Sort (in order of use site) so that we're not dependent on the iteration
    504   // order through an llvm::DenseMap.
    505   SourceManager &SM = Context.getSourceManager();
    506   std::sort(Undefined.begin(), Undefined.end(),
    507             [&SM](const std::pair<NamedDecl *, SourceLocation> &l,
    508                   const std::pair<NamedDecl *, SourceLocation> &r) {
    509     if (l.second.isValid() && !r.second.isValid())
    510       return true;
    511     if (!l.second.isValid() && r.second.isValid())
    512       return false;
    513     if (l.second != r.second)
    514       return SM.isBeforeInTranslationUnit(l.second, r.second);
    515     return SM.isBeforeInTranslationUnit(l.first->getLocation(),
    516                                         r.first->getLocation());
    517   });
    518 }
    519 
    520 /// checkUndefinedButUsed - Check for undefined objects with internal linkage
    521 /// or that are inline.
    522 static void checkUndefinedButUsed(Sema &S) {
    523   if (S.UndefinedButUsed.empty()) return;
    524 
    525   // Collect all the still-undefined entities with internal linkage.
    526   SmallVector<std::pair<NamedDecl *, SourceLocation>, 16> Undefined;
    527   S.getUndefinedButUsed(Undefined);
    528   if (Undefined.empty()) return;
    529 
    530   for (SmallVectorImpl<std::pair<NamedDecl *, SourceLocation> >::iterator
    531          I = Undefined.begin(), E = Undefined.end(); I != E; ++I) {
    532     NamedDecl *ND = I->first;
    533 
    534     if (ND->hasAttr<DLLImportAttr>() || ND->hasAttr<DLLExportAttr>()) {
    535       // An exported function will always be emitted when defined, so even if
    536       // the function is inline, it doesn't have to be emitted in this TU. An
    537       // imported function implies that it has been exported somewhere else.
    538       continue;
    539     }
    540 
    541     if (!ND->isExternallyVisible()) {
    542       S.Diag(ND->getLocation(), diag::warn_undefined_internal)
    543         << isa<VarDecl>(ND) << ND;
    544     } else {
    545       assert(cast<FunctionDecl>(ND)->getMostRecentDecl()->isInlined() &&
    546              "used object requires definition but isn't inline or internal?");
    547       S.Diag(ND->getLocation(), diag::warn_undefined_inline) << ND;
    548     }
    549     if (I->second.isValid())
    550       S.Diag(I->second, diag::note_used_here);
    551   }
    552 }
    553 
    554 void Sema::LoadExternalWeakUndeclaredIdentifiers() {
    555   if (!ExternalSource)
    556     return;
    557 
    558   SmallVector<std::pair<IdentifierInfo *, WeakInfo>, 4> WeakIDs;
    559   ExternalSource->ReadWeakUndeclaredIdentifiers(WeakIDs);
    560   for (auto &WeakID : WeakIDs)
    561     WeakUndeclaredIdentifiers.insert(WeakID);
    562 }
    563 
    564 
    565 typedef llvm::DenseMap<const CXXRecordDecl*, bool> RecordCompleteMap;
    566 
    567 /// \brief Returns true, if all methods and nested classes of the given
    568 /// CXXRecordDecl are defined in this translation unit.
    569 ///
    570 /// Should only be called from ActOnEndOfTranslationUnit so that all
    571 /// definitions are actually read.
    572 static bool MethodsAndNestedClassesComplete(const CXXRecordDecl *RD,
    573                                             RecordCompleteMap &MNCComplete) {
    574   RecordCompleteMap::iterator Cache = MNCComplete.find(RD);
    575   if (Cache != MNCComplete.end())
    576     return Cache->second;
    577   if (!RD->isCompleteDefinition())
    578     return false;
    579   bool Complete = true;
    580   for (DeclContext::decl_iterator I = RD->decls_begin(),
    581                                   E = RD->decls_end();
    582        I != E && Complete; ++I) {
    583     if (const CXXMethodDecl *M = dyn_cast<CXXMethodDecl>(*I))
    584       Complete = M->isDefined() || (M->isPure() && !isa<CXXDestructorDecl>(M));
    585     else if (const FunctionTemplateDecl *F = dyn_cast<FunctionTemplateDecl>(*I))
    586       // If the template function is marked as late template parsed at this
    587       // point, it has not been instantiated and therefore we have not
    588       // performed semantic analysis on it yet, so we cannot know if the type
    589       // can be considered complete.
    590       Complete = !F->getTemplatedDecl()->isLateTemplateParsed() &&
    591                   F->getTemplatedDecl()->isDefined();
    592     else if (const CXXRecordDecl *R = dyn_cast<CXXRecordDecl>(*I)) {
    593       if (R->isInjectedClassName())
    594         continue;
    595       if (R->hasDefinition())
    596         Complete = MethodsAndNestedClassesComplete(R->getDefinition(),
    597                                                    MNCComplete);
    598       else
    599         Complete = false;
    600     }
    601   }
    602   MNCComplete[RD] = Complete;
    603   return Complete;
    604 }
    605 
    606 /// \brief Returns true, if the given CXXRecordDecl is fully defined in this
    607 /// translation unit, i.e. all methods are defined or pure virtual and all
    608 /// friends, friend functions and nested classes are fully defined in this
    609 /// translation unit.
    610 ///
    611 /// Should only be called from ActOnEndOfTranslationUnit so that all
    612 /// definitions are actually read.
    613 static bool IsRecordFullyDefined(const CXXRecordDecl *RD,
    614                                  RecordCompleteMap &RecordsComplete,
    615                                  RecordCompleteMap &MNCComplete) {
    616   RecordCompleteMap::iterator Cache = RecordsComplete.find(RD);
    617   if (Cache != RecordsComplete.end())
    618     return Cache->second;
    619   bool Complete = MethodsAndNestedClassesComplete(RD, MNCComplete);
    620   for (CXXRecordDecl::friend_iterator I = RD->friend_begin(),
    621                                       E = RD->friend_end();
    622        I != E && Complete; ++I) {
    623     // Check if friend classes and methods are complete.
    624     if (TypeSourceInfo *TSI = (*I)->getFriendType()) {
    625       // Friend classes are available as the TypeSourceInfo of the FriendDecl.
    626       if (CXXRecordDecl *FriendD = TSI->getType()->getAsCXXRecordDecl())
    627         Complete = MethodsAndNestedClassesComplete(FriendD, MNCComplete);
    628       else
    629         Complete = false;
    630     } else {
    631       // Friend functions are available through the NamedDecl of FriendDecl.
    632       if (const FunctionDecl *FD =
    633           dyn_cast<FunctionDecl>((*I)->getFriendDecl()))
    634         Complete = FD->isDefined();
    635       else
    636         // This is a template friend, give up.
    637         Complete = false;
    638     }
    639   }
    640   RecordsComplete[RD] = Complete;
    641   return Complete;
    642 }
    643 
    644 void Sema::emitAndClearUnusedLocalTypedefWarnings() {
    645   if (ExternalSource)
    646     ExternalSource->ReadUnusedLocalTypedefNameCandidates(
    647         UnusedLocalTypedefNameCandidates);
    648   for (const TypedefNameDecl *TD : UnusedLocalTypedefNameCandidates) {
    649     if (TD->isReferenced())
    650       continue;
    651     Diag(TD->getLocation(), diag::warn_unused_local_typedef)
    652         << isa<TypeAliasDecl>(TD) << TD->getDeclName();
    653   }
    654   UnusedLocalTypedefNameCandidates.clear();
    655 }
    656 
    657 /// ActOnEndOfTranslationUnit - This is called at the very end of the
    658 /// translation unit when EOF is reached and all but the top-level scope is
    659 /// popped.
    660 void Sema::ActOnEndOfTranslationUnit() {
    661   assert(DelayedDiagnostics.getCurrentPool() == nullptr
    662          && "reached end of translation unit with a pool attached?");
    663 
    664   // If code completion is enabled, don't perform any end-of-translation-unit
    665   // work.
    666   if (PP.isCodeCompletionEnabled())
    667     return;
    668 
    669   // Complete translation units and modules define vtables and perform implicit
    670   // instantiations. PCH files do not.
    671   if (TUKind != TU_Prefix) {
    672     DiagnoseUseOfUnimplementedSelectors();
    673 
    674     // If DefinedUsedVTables ends up marking any virtual member functions it
    675     // might lead to more pending template instantiations, which we then need
    676     // to instantiate.
    677     DefineUsedVTables();
    678 
    679     // C++: Perform implicit template instantiations.
    680     //
    681     // FIXME: When we perform these implicit instantiations, we do not
    682     // carefully keep track of the point of instantiation (C++ [temp.point]).
    683     // This means that name lookup that occurs within the template
    684     // instantiation will always happen at the end of the translation unit,
    685     // so it will find some names that are not required to be found. This is
    686     // valid, but we could do better by diagnosing if an instantiation uses a
    687     // name that was not visible at its first point of instantiation.
    688     if (ExternalSource) {
    689       // Load pending instantiations from the external source.
    690       SmallVector<PendingImplicitInstantiation, 4> Pending;
    691       ExternalSource->ReadPendingInstantiations(Pending);
    692       PendingInstantiations.insert(PendingInstantiations.begin(),
    693                                    Pending.begin(), Pending.end());
    694     }
    695     PerformPendingInstantiations();
    696 
    697     if (LateTemplateParserCleanup)
    698       LateTemplateParserCleanup(OpaqueParser);
    699 
    700     CheckDelayedMemberExceptionSpecs();
    701   }
    702 
    703   // All delayed member exception specs should be checked or we end up accepting
    704   // incompatible declarations.
    705   // FIXME: This is wrong for TUKind == TU_Prefix. In that case, we need to
    706   // write out the lists to the AST file (if any).
    707   assert(DelayedDefaultedMemberExceptionSpecs.empty());
    708   assert(DelayedExceptionSpecChecks.empty());
    709 
    710   // All dllexport classes should have been processed already.
    711   assert(DelayedDllExportClasses.empty());
    712 
    713   // Remove file scoped decls that turned out to be used.
    714   UnusedFileScopedDecls.erase(
    715       std::remove_if(UnusedFileScopedDecls.begin(nullptr, true),
    716                      UnusedFileScopedDecls.end(),
    717                      std::bind1st(std::ptr_fun(ShouldRemoveFromUnused), this)),
    718       UnusedFileScopedDecls.end());
    719 
    720   if (TUKind == TU_Prefix) {
    721     // Translation unit prefixes don't need any of the checking below.
    722     TUScope = nullptr;
    723     return;
    724   }
    725 
    726   // Check for #pragma weak identifiers that were never declared
    727   LoadExternalWeakUndeclaredIdentifiers();
    728   for (auto WeakID : WeakUndeclaredIdentifiers) {
    729     if (WeakID.second.getUsed())
    730       continue;
    731 
    732     Decl *PrevDecl = LookupSingleName(TUScope, WeakID.first, SourceLocation(),
    733                                       LookupOrdinaryName);
    734     if (PrevDecl != nullptr &&
    735         !(isa<FunctionDecl>(PrevDecl) || isa<VarDecl>(PrevDecl)))
    736       Diag(WeakID.second.getLocation(), diag::warn_attribute_wrong_decl_type)
    737           << "'weak'" << ExpectedVariableOrFunction;
    738     else
    739       Diag(WeakID.second.getLocation(), diag::warn_weak_identifier_undeclared)
    740           << WeakID.first;
    741   }
    742 
    743   if (LangOpts.CPlusPlus11 &&
    744       !Diags.isIgnored(diag::warn_delegating_ctor_cycle, SourceLocation()))
    745     CheckDelegatingCtorCycles();
    746 
    747   if (TUKind == TU_Module) {
    748     // If we are building a module, resolve all of the exported declarations
    749     // now.
    750     if (Module *CurrentModule = PP.getCurrentModule()) {
    751       ModuleMap &ModMap = PP.getHeaderSearchInfo().getModuleMap();
    752 
    753       SmallVector<Module *, 2> Stack;
    754       Stack.push_back(CurrentModule);
    755       while (!Stack.empty()) {
    756         Module *Mod = Stack.pop_back_val();
    757 
    758         // Resolve the exported declarations and conflicts.
    759         // FIXME: Actually complain, once we figure out how to teach the
    760         // diagnostic client to deal with complaints in the module map at this
    761         // point.
    762         ModMap.resolveExports(Mod, /*Complain=*/false);
    763         ModMap.resolveUses(Mod, /*Complain=*/false);
    764         ModMap.resolveConflicts(Mod, /*Complain=*/false);
    765 
    766         // Queue the submodules, so their exports will also be resolved.
    767         Stack.append(Mod->submodule_begin(), Mod->submodule_end());
    768       }
    769     }
    770 
    771     // Warnings emitted in ActOnEndOfTranslationUnit() should be emitted for
    772     // modules when they are built, not every time they are used.
    773     emitAndClearUnusedLocalTypedefWarnings();
    774 
    775     // Modules don't need any of the checking below.
    776     TUScope = nullptr;
    777     return;
    778   }
    779 
    780   // C99 6.9.2p2:
    781   //   A declaration of an identifier for an object that has file
    782   //   scope without an initializer, and without a storage-class
    783   //   specifier or with the storage-class specifier static,
    784   //   constitutes a tentative definition. If a translation unit
    785   //   contains one or more tentative definitions for an identifier,
    786   //   and the translation unit contains no external definition for
    787   //   that identifier, then the behavior is exactly as if the
    788   //   translation unit contains a file scope declaration of that
    789   //   identifier, with the composite type as of the end of the
    790   //   translation unit, with an initializer equal to 0.
    791   llvm::SmallSet<VarDecl *, 32> Seen;
    792   for (TentativeDefinitionsType::iterator
    793             T = TentativeDefinitions.begin(ExternalSource),
    794          TEnd = TentativeDefinitions.end();
    795        T != TEnd; ++T)
    796   {
    797     VarDecl *VD = (*T)->getActingDefinition();
    798 
    799     // If the tentative definition was completed, getActingDefinition() returns
    800     // null. If we've already seen this variable before, insert()'s second
    801     // return value is false.
    802     if (!VD || VD->isInvalidDecl() || !Seen.insert(VD).second)
    803       continue;
    804 
    805     if (const IncompleteArrayType *ArrayT
    806         = Context.getAsIncompleteArrayType(VD->getType())) {
    807       // Set the length of the array to 1 (C99 6.9.2p5).
    808       Diag(VD->getLocation(), diag::warn_tentative_incomplete_array);
    809       llvm::APInt One(Context.getTypeSize(Context.getSizeType()), true);
    810       QualType T = Context.getConstantArrayType(ArrayT->getElementType(),
    811                                                 One, ArrayType::Normal, 0);
    812       VD->setType(T);
    813     } else if (RequireCompleteType(VD->getLocation(), VD->getType(),
    814                                    diag::err_tentative_def_incomplete_type))
    815       VD->setInvalidDecl();
    816 
    817     CheckCompleteVariableDeclaration(VD);
    818 
    819     // Notify the consumer that we've completed a tentative definition.
    820     if (!VD->isInvalidDecl())
    821       Consumer.CompleteTentativeDefinition(VD);
    822 
    823   }
    824 
    825   // If there were errors, disable 'unused' warnings since they will mostly be
    826   // noise.
    827   if (!Diags.hasErrorOccurred()) {
    828     // Output warning for unused file scoped decls.
    829     for (UnusedFileScopedDeclsType::iterator
    830            I = UnusedFileScopedDecls.begin(ExternalSource),
    831            E = UnusedFileScopedDecls.end(); I != E; ++I) {
    832       if (ShouldRemoveFromUnused(this, *I))
    833         continue;
    834 
    835       if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(*I)) {
    836         const FunctionDecl *DiagD;
    837         if (!FD->hasBody(DiagD))
    838           DiagD = FD;
    839         if (DiagD->isDeleted())
    840           continue; // Deleted functions are supposed to be unused.
    841         if (DiagD->isReferenced()) {
    842           if (isa<CXXMethodDecl>(DiagD))
    843             Diag(DiagD->getLocation(), diag::warn_unneeded_member_function)
    844                   << DiagD->getDeclName();
    845           else {
    846             if (FD->getStorageClass() == SC_Static &&
    847                 !FD->isInlineSpecified() &&
    848                 !SourceMgr.isInMainFile(
    849                    SourceMgr.getExpansionLoc(FD->getLocation())))
    850               Diag(DiagD->getLocation(),
    851                    diag::warn_unneeded_static_internal_decl)
    852                   << DiagD->getDeclName();
    853             else
    854               Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
    855                    << /*function*/0 << DiagD->getDeclName();
    856           }
    857         } else {
    858           Diag(DiagD->getLocation(),
    859                isa<CXXMethodDecl>(DiagD) ? diag::warn_unused_member_function
    860                                          : diag::warn_unused_function)
    861                 << DiagD->getDeclName();
    862         }
    863       } else {
    864         const VarDecl *DiagD = cast<VarDecl>(*I)->getDefinition();
    865         if (!DiagD)
    866           DiagD = cast<VarDecl>(*I);
    867         if (DiagD->isReferenced()) {
    868           Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
    869                 << /*variable*/1 << DiagD->getDeclName();
    870         } else if (DiagD->getType().isConstQualified()) {
    871           Diag(DiagD->getLocation(), diag::warn_unused_const_variable)
    872               << DiagD->getDeclName();
    873         } else {
    874           Diag(DiagD->getLocation(), diag::warn_unused_variable)
    875               << DiagD->getDeclName();
    876         }
    877       }
    878     }
    879 
    880     if (ExternalSource)
    881       ExternalSource->ReadUndefinedButUsed(UndefinedButUsed);
    882     checkUndefinedButUsed(*this);
    883 
    884     emitAndClearUnusedLocalTypedefWarnings();
    885   }
    886 
    887   if (!Diags.isIgnored(diag::warn_unused_private_field, SourceLocation())) {
    888     RecordCompleteMap RecordsComplete;
    889     RecordCompleteMap MNCComplete;
    890     for (NamedDeclSetType::iterator I = UnusedPrivateFields.begin(),
    891          E = UnusedPrivateFields.end(); I != E; ++I) {
    892       const NamedDecl *D = *I;
    893       const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D->getDeclContext());
    894       if (RD && !RD->isUnion() &&
    895           IsRecordFullyDefined(RD, RecordsComplete, MNCComplete)) {
    896         Diag(D->getLocation(), diag::warn_unused_private_field)
    897               << D->getDeclName();
    898       }
    899     }
    900   }
    901 
    902   if (!Diags.isIgnored(diag::warn_mismatched_delete_new, SourceLocation())) {
    903     if (ExternalSource)
    904       ExternalSource->ReadMismatchingDeleteExpressions(DeleteExprs);
    905     for (const auto &DeletedFieldInfo : DeleteExprs) {
    906       for (const auto &DeleteExprLoc : DeletedFieldInfo.second) {
    907         AnalyzeDeleteExprMismatch(DeletedFieldInfo.first, DeleteExprLoc.first,
    908                                   DeleteExprLoc.second);
    909       }
    910     }
    911   }
    912 
    913   // Check we've noticed that we're no longer parsing the initializer for every
    914   // variable. If we miss cases, then at best we have a performance issue and
    915   // at worst a rejects-valid bug.
    916   assert(ParsingInitForAutoVars.empty() &&
    917          "Didn't unmark var as having its initializer parsed");
    918 
    919   TUScope = nullptr;
    920 }
    921 
    922 
    923 //===----------------------------------------------------------------------===//
    924 // Helper functions.
    925 //===----------------------------------------------------------------------===//
    926 
    927 DeclContext *Sema::getFunctionLevelDeclContext() {
    928   DeclContext *DC = CurContext;
    929 
    930   while (true) {
    931     if (isa<BlockDecl>(DC) || isa<EnumDecl>(DC) || isa<CapturedDecl>(DC)) {
    932       DC = DC->getParent();
    933     } else if (isa<CXXMethodDecl>(DC) &&
    934                cast<CXXMethodDecl>(DC)->getOverloadedOperator() == OO_Call &&
    935                cast<CXXRecordDecl>(DC->getParent())->isLambda()) {
    936       DC = DC->getParent()->getParent();
    937     }
    938     else break;
    939   }
    940 
    941   return DC;
    942 }
    943 
    944 /// getCurFunctionDecl - If inside of a function body, this returns a pointer
    945 /// to the function decl for the function being parsed.  If we're currently
    946 /// in a 'block', this returns the containing context.
    947 FunctionDecl *Sema::getCurFunctionDecl() {
    948   DeclContext *DC = getFunctionLevelDeclContext();
    949   return dyn_cast<FunctionDecl>(DC);
    950 }
    951 
    952 ObjCMethodDecl *Sema::getCurMethodDecl() {
    953   DeclContext *DC = getFunctionLevelDeclContext();
    954   while (isa<RecordDecl>(DC))
    955     DC = DC->getParent();
    956   return dyn_cast<ObjCMethodDecl>(DC);
    957 }
    958 
    959 NamedDecl *Sema::getCurFunctionOrMethodDecl() {
    960   DeclContext *DC = getFunctionLevelDeclContext();
    961   if (isa<ObjCMethodDecl>(DC) || isa<FunctionDecl>(DC))
    962     return cast<NamedDecl>(DC);
    963   return nullptr;
    964 }
    965 
    966 void Sema::EmitCurrentDiagnostic(unsigned DiagID) {
    967   // FIXME: It doesn't make sense to me that DiagID is an incoming argument here
    968   // and yet we also use the current diag ID on the DiagnosticsEngine. This has
    969   // been made more painfully obvious by the refactor that introduced this
    970   // function, but it is possible that the incoming argument can be
    971   // eliminnated. If it truly cannot be (for example, there is some reentrancy
    972   // issue I am not seeing yet), then there should at least be a clarifying
    973   // comment somewhere.
    974   if (Optional<TemplateDeductionInfo*> Info = isSFINAEContext()) {
    975     switch (DiagnosticIDs::getDiagnosticSFINAEResponse(
    976               Diags.getCurrentDiagID())) {
    977     case DiagnosticIDs::SFINAE_Report:
    978       // We'll report the diagnostic below.
    979       break;
    980 
    981     case DiagnosticIDs::SFINAE_SubstitutionFailure:
    982       // Count this failure so that we know that template argument deduction
    983       // has failed.
    984       ++NumSFINAEErrors;
    985 
    986       // Make a copy of this suppressed diagnostic and store it with the
    987       // template-deduction information.
    988       if (*Info && !(*Info)->hasSFINAEDiagnostic()) {
    989         Diagnostic DiagInfo(&Diags);
    990         (*Info)->addSFINAEDiagnostic(DiagInfo.getLocation(),
    991                        PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
    992       }
    993 
    994       Diags.setLastDiagnosticIgnored();
    995       Diags.Clear();
    996       return;
    997 
    998     case DiagnosticIDs::SFINAE_AccessControl: {
    999       // Per C++ Core Issue 1170, access control is part of SFINAE.
   1000       // Additionally, the AccessCheckingSFINAE flag can be used to temporarily
   1001       // make access control a part of SFINAE for the purposes of checking
   1002       // type traits.
   1003       if (!AccessCheckingSFINAE && !getLangOpts().CPlusPlus11)
   1004         break;
   1005 
   1006       SourceLocation Loc = Diags.getCurrentDiagLoc();
   1007 
   1008       // Suppress this diagnostic.
   1009       ++NumSFINAEErrors;
   1010 
   1011       // Make a copy of this suppressed diagnostic and store it with the
   1012       // template-deduction information.
   1013       if (*Info && !(*Info)->hasSFINAEDiagnostic()) {
   1014         Diagnostic DiagInfo(&Diags);
   1015         (*Info)->addSFINAEDiagnostic(DiagInfo.getLocation(),
   1016                        PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
   1017       }
   1018 
   1019       Diags.setLastDiagnosticIgnored();
   1020       Diags.Clear();
   1021 
   1022       // Now the diagnostic state is clear, produce a C++98 compatibility
   1023       // warning.
   1024       Diag(Loc, diag::warn_cxx98_compat_sfinae_access_control);
   1025 
   1026       // The last diagnostic which Sema produced was ignored. Suppress any
   1027       // notes attached to it.
   1028       Diags.setLastDiagnosticIgnored();
   1029       return;
   1030     }
   1031 
   1032     case DiagnosticIDs::SFINAE_Suppress:
   1033       // Make a copy of this suppressed diagnostic and store it with the
   1034       // template-deduction information;
   1035       if (*Info) {
   1036         Diagnostic DiagInfo(&Diags);
   1037         (*Info)->addSuppressedDiagnostic(DiagInfo.getLocation(),
   1038                        PartialDiagnostic(DiagInfo, Context.getDiagAllocator()));
   1039       }
   1040 
   1041       // Suppress this diagnostic.
   1042       Diags.setLastDiagnosticIgnored();
   1043       Diags.Clear();
   1044       return;
   1045     }
   1046   }
   1047 
   1048   // Set up the context's printing policy based on our current state.
   1049   Context.setPrintingPolicy(getPrintingPolicy());
   1050 
   1051   // Emit the diagnostic.
   1052   if (!Diags.EmitCurrentDiagnostic())
   1053     return;
   1054 
   1055   // If this is not a note, and we're in a template instantiation
   1056   // that is different from the last template instantiation where
   1057   // we emitted an error, print a template instantiation
   1058   // backtrace.
   1059   if (!DiagnosticIDs::isBuiltinNote(DiagID) &&
   1060       !ActiveTemplateInstantiations.empty() &&
   1061       ActiveTemplateInstantiations.back()
   1062         != LastTemplateInstantiationErrorContext) {
   1063     PrintInstantiationStack();
   1064     LastTemplateInstantiationErrorContext = ActiveTemplateInstantiations.back();
   1065   }
   1066 }
   1067 
   1068 Sema::SemaDiagnosticBuilder
   1069 Sema::Diag(SourceLocation Loc, const PartialDiagnostic& PD) {
   1070   SemaDiagnosticBuilder Builder(Diag(Loc, PD.getDiagID()));
   1071   PD.Emit(Builder);
   1072 
   1073   return Builder;
   1074 }
   1075 
   1076 /// \brief Looks through the macro-expansion chain for the given
   1077 /// location, looking for a macro expansion with the given name.
   1078 /// If one is found, returns true and sets the location to that
   1079 /// expansion loc.
   1080 bool Sema::findMacroSpelling(SourceLocation &locref, StringRef name) {
   1081   SourceLocation loc = locref;
   1082   if (!loc.isMacroID()) return false;
   1083 
   1084   // There's no good way right now to look at the intermediate
   1085   // expansions, so just jump to the expansion location.
   1086   loc = getSourceManager().getExpansionLoc(loc);
   1087 
   1088   // If that's written with the name, stop here.
   1089   SmallVector<char, 16> buffer;
   1090   if (getPreprocessor().getSpelling(loc, buffer) == name) {
   1091     locref = loc;
   1092     return true;
   1093   }
   1094   return false;
   1095 }
   1096 
   1097 /// \brief Determines the active Scope associated with the given declaration
   1098 /// context.
   1099 ///
   1100 /// This routine maps a declaration context to the active Scope object that
   1101 /// represents that declaration context in the parser. It is typically used
   1102 /// from "scope-less" code (e.g., template instantiation, lazy creation of
   1103 /// declarations) that injects a name for name-lookup purposes and, therefore,
   1104 /// must update the Scope.
   1105 ///
   1106 /// \returns The scope corresponding to the given declaraion context, or NULL
   1107 /// if no such scope is open.
   1108 Scope *Sema::getScopeForContext(DeclContext *Ctx) {
   1109 
   1110   if (!Ctx)
   1111     return nullptr;
   1112 
   1113   Ctx = Ctx->getPrimaryContext();
   1114   for (Scope *S = getCurScope(); S; S = S->getParent()) {
   1115     // Ignore scopes that cannot have declarations. This is important for
   1116     // out-of-line definitions of static class members.
   1117     if (S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope))
   1118       if (DeclContext *Entity = S->getEntity())
   1119         if (Ctx == Entity->getPrimaryContext())
   1120           return S;
   1121   }
   1122 
   1123   return nullptr;
   1124 }
   1125 
   1126 /// \brief Enter a new function scope
   1127 void Sema::PushFunctionScope() {
   1128   if (FunctionScopes.size() == 1) {
   1129     // Use the "top" function scope rather than having to allocate
   1130     // memory for a new scope.
   1131     FunctionScopes.back()->Clear();
   1132     FunctionScopes.push_back(FunctionScopes.back());
   1133     return;
   1134   }
   1135 
   1136   FunctionScopes.push_back(new FunctionScopeInfo(getDiagnostics()));
   1137 }
   1138 
   1139 void Sema::PushBlockScope(Scope *BlockScope, BlockDecl *Block) {
   1140   FunctionScopes.push_back(new BlockScopeInfo(getDiagnostics(),
   1141                                               BlockScope, Block));
   1142 }
   1143 
   1144 LambdaScopeInfo *Sema::PushLambdaScope() {
   1145   LambdaScopeInfo *const LSI = new LambdaScopeInfo(getDiagnostics());
   1146   FunctionScopes.push_back(LSI);
   1147   return LSI;
   1148 }
   1149 
   1150 void Sema::RecordParsingTemplateParameterDepth(unsigned Depth) {
   1151   if (LambdaScopeInfo *const LSI = getCurLambda()) {
   1152     LSI->AutoTemplateParameterDepth = Depth;
   1153     return;
   1154   }
   1155   llvm_unreachable(
   1156       "Remove assertion if intentionally called in a non-lambda context.");
   1157 }
   1158 
   1159 void Sema::PopFunctionScopeInfo(const AnalysisBasedWarnings::Policy *WP,
   1160                                 const Decl *D, const BlockExpr *blkExpr) {
   1161   FunctionScopeInfo *Scope = FunctionScopes.pop_back_val();
   1162   assert(!FunctionScopes.empty() && "mismatched push/pop!");
   1163 
   1164   // Issue any analysis-based warnings.
   1165   if (WP && D)
   1166     AnalysisWarnings.IssueWarnings(*WP, Scope, D, blkExpr);
   1167   else
   1168     for (const auto &PUD : Scope->PossiblyUnreachableDiags)
   1169       Diag(PUD.Loc, PUD.PD);
   1170 
   1171   if (FunctionScopes.back() != Scope)
   1172     delete Scope;
   1173 }
   1174 
   1175 void Sema::PushCompoundScope() {
   1176   getCurFunction()->CompoundScopes.push_back(CompoundScopeInfo());
   1177 }
   1178 
   1179 void Sema::PopCompoundScope() {
   1180   FunctionScopeInfo *CurFunction = getCurFunction();
   1181   assert(!CurFunction->CompoundScopes.empty() && "mismatched push/pop");
   1182 
   1183   CurFunction->CompoundScopes.pop_back();
   1184 }
   1185 
   1186 /// \brief Determine whether any errors occurred within this function/method/
   1187 /// block.
   1188 bool Sema::hasAnyUnrecoverableErrorsInThisFunction() const {
   1189   return getCurFunction()->ErrorTrap.hasUnrecoverableErrorOccurred();
   1190 }
   1191 
   1192 BlockScopeInfo *Sema::getCurBlock() {
   1193   if (FunctionScopes.empty())
   1194     return nullptr;
   1195 
   1196   auto CurBSI = dyn_cast<BlockScopeInfo>(FunctionScopes.back());
   1197   if (CurBSI && CurBSI->TheDecl &&
   1198       !CurBSI->TheDecl->Encloses(CurContext)) {
   1199     // We have switched contexts due to template instantiation.
   1200     assert(!ActiveTemplateInstantiations.empty());
   1201     return nullptr;
   1202   }
   1203 
   1204   return CurBSI;
   1205 }
   1206 
   1207 LambdaScopeInfo *Sema::getCurLambda() {
   1208   if (FunctionScopes.empty())
   1209     return nullptr;
   1210 
   1211   auto CurLSI = dyn_cast<LambdaScopeInfo>(FunctionScopes.back());
   1212   if (CurLSI && CurLSI->Lambda &&
   1213       !CurLSI->Lambda->Encloses(CurContext)) {
   1214     // We have switched contexts due to template instantiation.
   1215     assert(!ActiveTemplateInstantiations.empty());
   1216     return nullptr;
   1217   }
   1218 
   1219   return CurLSI;
   1220 }
   1221 // We have a generic lambda if we parsed auto parameters, or we have
   1222 // an associated template parameter list.
   1223 LambdaScopeInfo *Sema::getCurGenericLambda() {
   1224   if (LambdaScopeInfo *LSI =  getCurLambda()) {
   1225     return (LSI->AutoTemplateParams.size() ||
   1226                     LSI->GLTemplateParameterList) ? LSI : nullptr;
   1227   }
   1228   return nullptr;
   1229 }
   1230 
   1231 
   1232 void Sema::ActOnComment(SourceRange Comment) {
   1233   if (!LangOpts.RetainCommentsFromSystemHeaders &&
   1234       SourceMgr.isInSystemHeader(Comment.getBegin()))
   1235     return;
   1236   RawComment RC(SourceMgr, Comment, false,
   1237                 LangOpts.CommentOpts.ParseAllComments);
   1238   if (RC.isAlmostTrailingComment()) {
   1239     SourceRange MagicMarkerRange(Comment.getBegin(),
   1240                                  Comment.getBegin().getLocWithOffset(3));
   1241     StringRef MagicMarkerText;
   1242     switch (RC.getKind()) {
   1243     case RawComment::RCK_OrdinaryBCPL:
   1244       MagicMarkerText = "///<";
   1245       break;
   1246     case RawComment::RCK_OrdinaryC:
   1247       MagicMarkerText = "/**<";
   1248       break;
   1249     default:
   1250       llvm_unreachable("if this is an almost Doxygen comment, "
   1251                        "it should be ordinary");
   1252     }
   1253     Diag(Comment.getBegin(), diag::warn_not_a_doxygen_trailing_member_comment) <<
   1254       FixItHint::CreateReplacement(MagicMarkerRange, MagicMarkerText);
   1255   }
   1256   Context.addComment(RC);
   1257 }
   1258 
   1259 // Pin this vtable to this file.
   1260 ExternalSemaSource::~ExternalSemaSource() {}
   1261 
   1262 void ExternalSemaSource::ReadMethodPool(Selector Sel) { }
   1263 
   1264 void ExternalSemaSource::ReadKnownNamespaces(
   1265                            SmallVectorImpl<NamespaceDecl *> &Namespaces) {
   1266 }
   1267 
   1268 void ExternalSemaSource::ReadUndefinedButUsed(
   1269                        llvm::DenseMap<NamedDecl *, SourceLocation> &Undefined) {
   1270 }
   1271 
   1272 void ExternalSemaSource::ReadMismatchingDeleteExpressions(llvm::MapVector<
   1273     FieldDecl *, llvm::SmallVector<std::pair<SourceLocation, bool>, 4>> &) {}
   1274 
   1275 void PrettyDeclStackTraceEntry::print(raw_ostream &OS) const {
   1276   SourceLocation Loc = this->Loc;
   1277   if (!Loc.isValid() && TheDecl) Loc = TheDecl->getLocation();
   1278   if (Loc.isValid()) {
   1279     Loc.print(OS, S.getSourceManager());
   1280     OS << ": ";
   1281   }
   1282   OS << Message;
   1283 
   1284   if (TheDecl && isa<NamedDecl>(TheDecl)) {
   1285     std::string Name = cast<NamedDecl>(TheDecl)->getNameAsString();
   1286     if (!Name.empty())
   1287       OS << " '" << Name << '\'';
   1288   }
   1289 
   1290   OS << '\n';
   1291 }
   1292 
   1293 /// \brief Figure out if an expression could be turned into a call.
   1294 ///
   1295 /// Use this when trying to recover from an error where the programmer may have
   1296 /// written just the name of a function instead of actually calling it.
   1297 ///
   1298 /// \param E - The expression to examine.
   1299 /// \param ZeroArgCallReturnTy - If the expression can be turned into a call
   1300 ///  with no arguments, this parameter is set to the type returned by such a
   1301 ///  call; otherwise, it is set to an empty QualType.
   1302 /// \param OverloadSet - If the expression is an overloaded function
   1303 ///  name, this parameter is populated with the decls of the various overloads.
   1304 bool Sema::tryExprAsCall(Expr &E, QualType &ZeroArgCallReturnTy,
   1305                          UnresolvedSetImpl &OverloadSet) {
   1306   ZeroArgCallReturnTy = QualType();
   1307   OverloadSet.clear();
   1308 
   1309   const OverloadExpr *Overloads = nullptr;
   1310   bool IsMemExpr = false;
   1311   if (E.getType() == Context.OverloadTy) {
   1312     OverloadExpr::FindResult FR = OverloadExpr::find(const_cast<Expr*>(&E));
   1313 
   1314     // Ignore overloads that are pointer-to-member constants.
   1315     if (FR.HasFormOfMemberPointer)
   1316       return false;
   1317 
   1318     Overloads = FR.Expression;
   1319   } else if (E.getType() == Context.BoundMemberTy) {
   1320     Overloads = dyn_cast<UnresolvedMemberExpr>(E.IgnoreParens());
   1321     IsMemExpr = true;
   1322   }
   1323 
   1324   bool Ambiguous = false;
   1325 
   1326   if (Overloads) {
   1327     for (OverloadExpr::decls_iterator it = Overloads->decls_begin(),
   1328          DeclsEnd = Overloads->decls_end(); it != DeclsEnd; ++it) {
   1329       OverloadSet.addDecl(*it);
   1330 
   1331       // Check whether the function is a non-template, non-member which takes no
   1332       // arguments.
   1333       if (IsMemExpr)
   1334         continue;
   1335       if (const FunctionDecl *OverloadDecl
   1336             = dyn_cast<FunctionDecl>((*it)->getUnderlyingDecl())) {
   1337         if (OverloadDecl->getMinRequiredArguments() == 0) {
   1338           if (!ZeroArgCallReturnTy.isNull() && !Ambiguous) {
   1339             ZeroArgCallReturnTy = QualType();
   1340             Ambiguous = true;
   1341           } else
   1342             ZeroArgCallReturnTy = OverloadDecl->getReturnType();
   1343         }
   1344       }
   1345     }
   1346 
   1347     // If it's not a member, use better machinery to try to resolve the call
   1348     if (!IsMemExpr)
   1349       return !ZeroArgCallReturnTy.isNull();
   1350   }
   1351 
   1352   // Attempt to call the member with no arguments - this will correctly handle
   1353   // member templates with defaults/deduction of template arguments, overloads
   1354   // with default arguments, etc.
   1355   if (IsMemExpr && !E.isTypeDependent()) {
   1356     bool Suppress = getDiagnostics().getSuppressAllDiagnostics();
   1357     getDiagnostics().setSuppressAllDiagnostics(true);
   1358     ExprResult R = BuildCallToMemberFunction(nullptr, &E, SourceLocation(),
   1359                                              None, SourceLocation());
   1360     getDiagnostics().setSuppressAllDiagnostics(Suppress);
   1361     if (R.isUsable()) {
   1362       ZeroArgCallReturnTy = R.get()->getType();
   1363       return true;
   1364     }
   1365     return false;
   1366   }
   1367 
   1368   if (const DeclRefExpr *DeclRef = dyn_cast<DeclRefExpr>(E.IgnoreParens())) {
   1369     if (const FunctionDecl *Fun = dyn_cast<FunctionDecl>(DeclRef->getDecl())) {
   1370       if (Fun->getMinRequiredArguments() == 0)
   1371         ZeroArgCallReturnTy = Fun->getReturnType();
   1372       return true;
   1373     }
   1374   }
   1375 
   1376   // We don't have an expression that's convenient to get a FunctionDecl from,
   1377   // but we can at least check if the type is "function of 0 arguments".
   1378   QualType ExprTy = E.getType();
   1379   const FunctionType *FunTy = nullptr;
   1380   QualType PointeeTy = ExprTy->getPointeeType();
   1381   if (!PointeeTy.isNull())
   1382     FunTy = PointeeTy->getAs<FunctionType>();
   1383   if (!FunTy)
   1384     FunTy = ExprTy->getAs<FunctionType>();
   1385 
   1386   if (const FunctionProtoType *FPT =
   1387       dyn_cast_or_null<FunctionProtoType>(FunTy)) {
   1388     if (FPT->getNumParams() == 0)
   1389       ZeroArgCallReturnTy = FunTy->getReturnType();
   1390     return true;
   1391   }
   1392   return false;
   1393 }
   1394 
   1395 /// \brief Give notes for a set of overloads.
   1396 ///
   1397 /// A companion to tryExprAsCall. In cases when the name that the programmer
   1398 /// wrote was an overloaded function, we may be able to make some guesses about
   1399 /// plausible overloads based on their return types; such guesses can be handed
   1400 /// off to this method to be emitted as notes.
   1401 ///
   1402 /// \param Overloads - The overloads to note.
   1403 /// \param FinalNoteLoc - If we've suppressed printing some overloads due to
   1404 ///  -fshow-overloads=best, this is the location to attach to the note about too
   1405 ///  many candidates. Typically this will be the location of the original
   1406 ///  ill-formed expression.
   1407 static void noteOverloads(Sema &S, const UnresolvedSetImpl &Overloads,
   1408                           const SourceLocation FinalNoteLoc) {
   1409   int ShownOverloads = 0;
   1410   int SuppressedOverloads = 0;
   1411   for (UnresolvedSetImpl::iterator It = Overloads.begin(),
   1412        DeclsEnd = Overloads.end(); It != DeclsEnd; ++It) {
   1413     // FIXME: Magic number for max shown overloads stolen from
   1414     // OverloadCandidateSet::NoteCandidates.
   1415     if (ShownOverloads >= 4 && S.Diags.getShowOverloads() == Ovl_Best) {
   1416       ++SuppressedOverloads;
   1417       continue;
   1418     }
   1419 
   1420     NamedDecl *Fn = (*It)->getUnderlyingDecl();
   1421     S.Diag(Fn->getLocation(), diag::note_possible_target_of_call);
   1422     ++ShownOverloads;
   1423   }
   1424 
   1425   if (SuppressedOverloads)
   1426     S.Diag(FinalNoteLoc, diag::note_ovl_too_many_candidates)
   1427       << SuppressedOverloads;
   1428 }
   1429 
   1430 static void notePlausibleOverloads(Sema &S, SourceLocation Loc,
   1431                                    const UnresolvedSetImpl &Overloads,
   1432                                    bool (*IsPlausibleResult)(QualType)) {
   1433   if (!IsPlausibleResult)
   1434     return noteOverloads(S, Overloads, Loc);
   1435 
   1436   UnresolvedSet<2> PlausibleOverloads;
   1437   for (OverloadExpr::decls_iterator It = Overloads.begin(),
   1438          DeclsEnd = Overloads.end(); It != DeclsEnd; ++It) {
   1439     const FunctionDecl *OverloadDecl = cast<FunctionDecl>(*It);
   1440     QualType OverloadResultTy = OverloadDecl->getReturnType();
   1441     if (IsPlausibleResult(OverloadResultTy))
   1442       PlausibleOverloads.addDecl(It.getDecl());
   1443   }
   1444   noteOverloads(S, PlausibleOverloads, Loc);
   1445 }
   1446 
   1447 /// Determine whether the given expression can be called by just
   1448 /// putting parentheses after it.  Notably, expressions with unary
   1449 /// operators can't be because the unary operator will start parsing
   1450 /// outside the call.
   1451 static bool IsCallableWithAppend(Expr *E) {
   1452   E = E->IgnoreImplicit();
   1453   return (!isa<CStyleCastExpr>(E) &&
   1454           !isa<UnaryOperator>(E) &&
   1455           !isa<BinaryOperator>(E) &&
   1456           !isa<CXXOperatorCallExpr>(E));
   1457 }
   1458 
   1459 bool Sema::tryToRecoverWithCall(ExprResult &E, const PartialDiagnostic &PD,
   1460                                 bool ForceComplain,
   1461                                 bool (*IsPlausibleResult)(QualType)) {
   1462   SourceLocation Loc = E.get()->getExprLoc();
   1463   SourceRange Range = E.get()->getSourceRange();
   1464 
   1465   QualType ZeroArgCallTy;
   1466   UnresolvedSet<4> Overloads;
   1467   if (tryExprAsCall(*E.get(), ZeroArgCallTy, Overloads) &&
   1468       !ZeroArgCallTy.isNull() &&
   1469       (!IsPlausibleResult || IsPlausibleResult(ZeroArgCallTy))) {
   1470     // At this point, we know E is potentially callable with 0
   1471     // arguments and that it returns something of a reasonable type,
   1472     // so we can emit a fixit and carry on pretending that E was
   1473     // actually a CallExpr.
   1474     SourceLocation ParenInsertionLoc = getLocForEndOfToken(Range.getEnd());
   1475     Diag(Loc, PD)
   1476       << /*zero-arg*/ 1 << Range
   1477       << (IsCallableWithAppend(E.get())
   1478           ? FixItHint::CreateInsertion(ParenInsertionLoc, "()")
   1479           : FixItHint());
   1480     notePlausibleOverloads(*this, Loc, Overloads, IsPlausibleResult);
   1481 
   1482     // FIXME: Try this before emitting the fixit, and suppress diagnostics
   1483     // while doing so.
   1484     E = ActOnCallExpr(nullptr, E.get(), Range.getEnd(), None,
   1485                       Range.getEnd().getLocWithOffset(1));
   1486     return true;
   1487   }
   1488 
   1489   if (!ForceComplain) return false;
   1490 
   1491   Diag(Loc, PD) << /*not zero-arg*/ 0 << Range;
   1492   notePlausibleOverloads(*this, Loc, Overloads, IsPlausibleResult);
   1493   E = ExprError();
   1494   return true;
   1495 }
   1496 
   1497 IdentifierInfo *Sema::getSuperIdentifier() const {
   1498   if (!Ident_super)
   1499     Ident_super = &Context.Idents.get("super");
   1500   return Ident_super;
   1501 }
   1502 
   1503 IdentifierInfo *Sema::getFloat128Identifier() const {
   1504   if (!Ident___float128)
   1505     Ident___float128 = &Context.Idents.get("__float128");
   1506   return Ident___float128;
   1507 }
   1508 
   1509 void Sema::PushCapturedRegionScope(Scope *S, CapturedDecl *CD, RecordDecl *RD,
   1510                                    CapturedRegionKind K) {
   1511   CapturingScopeInfo *CSI = new CapturedRegionScopeInfo(
   1512       getDiagnostics(), S, CD, RD, CD->getContextParam(), K);
   1513   CSI->ReturnType = Context.VoidTy;
   1514   FunctionScopes.push_back(CSI);
   1515 }
   1516 
   1517 CapturedRegionScopeInfo *Sema::getCurCapturedRegion() {
   1518   if (FunctionScopes.empty())
   1519     return nullptr;
   1520 
   1521   return dyn_cast<CapturedRegionScopeInfo>(FunctionScopes.back());
   1522 }
   1523 
   1524 const llvm::MapVector<FieldDecl *, Sema::DeleteLocs> &
   1525 Sema::getMismatchingDeleteExpressions() const {
   1526   return DeleteExprs;
   1527 }
   1528