lib/Sema/Sema.cpp - platform/external/clang - Gitiles

 //===--- Sema.cpp - AST Builder and Semantic Analysis Implementation ------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the actions class which performs semantic analysis and
 // builds an AST out of a parse stream.
 //
 //===----------------------------------------------------------------------===//

 #include "clang/Sema/Sema.h"
 #include "TargetAttributesSema.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/APFloat.h"
 #include "clang/Sema/CXXFieldCollector.h"
 #include "clang/Sema/ExternalSemaSource.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/ScopeInfo.h"
 #include "clang/Sema/SemaConsumer.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/ASTDiagnostic.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/Expr.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Basic/PartialDiagnostic.h"
 #include "clang/Basic/TargetInfo.h"
 using namespace clang;
 using namespace sema;

 FunctionScopeInfo::~FunctionScopeInfo() { }

 void FunctionScopeInfo::Clear(unsigned NumErrors) {
   HasBranchProtectedScope = false;
   HasBranchIntoScope = false;
   HasIndirectGoto = false;

   LabelMap.clear();
   SwitchStack.clear();
   Returns.clear();
   NumErrorsAtStartOfFunction = NumErrors;
 }

 BlockScopeInfo::~BlockScopeInfo() { }

 void Sema::ActOnTranslationUnitScope(SourceLocation Loc, Scope *S) {
   TUScope = S;
   PushDeclContext(S, Context.getTranslationUnitDecl());

   VAListTagName = PP.getIdentifierInfo("__va_list_tag");

   if (!Context.isInt128Installed() && // May be set by ASTReader.
       PP.getTargetInfo().getPointerWidth(0) >= 64) {
     TypeSourceInfo *TInfo;

     // Install [u]int128_t for 64-bit targets.
     TInfo = Context.getTrivialTypeSourceInfo(Context.Int128Ty);
     PushOnScopeChains(TypedefDecl::Create(Context, CurContext,
                                           SourceLocation(),
                                           &Context.Idents.get("__int128_t"),
                                           TInfo), TUScope);

     TInfo = Context.getTrivialTypeSourceInfo(Context.UnsignedInt128Ty);
     PushOnScopeChains(TypedefDecl::Create(Context, CurContext,
                                           SourceLocation(),
                                           &Context.Idents.get("__uint128_t"),
                                           TInfo), TUScope);
     Context.setInt128Installed();
   }


   if (!PP.getLangOptions().ObjC1) return;

   // Built-in ObjC types may already be set by ASTReader (hence isNull checks).
   if (Context.getObjCSelType().isNull()) {
     // Create the built-in typedef for 'SEL'.
     QualType SelT = Context.getPointerType(Context.ObjCBuiltinSelTy);
     TypeSourceInfo *SelInfo = Context.getTrivialTypeSourceInfo(SelT);
     TypedefDecl *SelTypedef
       = TypedefDecl::Create(Context, CurContext, SourceLocation(),
                             &Context.Idents.get("SEL"), SelInfo);
     PushOnScopeChains(SelTypedef, TUScope);
     Context.setObjCSelType(Context.getTypeDeclType(SelTypedef));
     Context.ObjCSelRedefinitionType = Context.getObjCSelType();
   }

   // Synthesize "@class Protocol;
   if (Context.getObjCProtoType().isNull()) {
     ObjCInterfaceDecl *ProtocolDecl =
       ObjCInterfaceDecl::Create(Context, CurContext, SourceLocation(),
                                 &Context.Idents.get("Protocol"),
                                 SourceLocation(), true);
     Context.setObjCProtoType(Context.getObjCInterfaceType(ProtocolDecl));
     PushOnScopeChains(ProtocolDecl, TUScope, false);
   }
   // Create the built-in typedef for 'id'.
   if (Context.getObjCIdType().isNull()) {
     QualType T = Context.getObjCObjectType(Context.ObjCBuiltinIdTy, 0, 0);
     T = Context.getObjCObjectPointerType(T);
     TypeSourceInfo *IdInfo = Context.getTrivialTypeSourceInfo(T);
     TypedefDecl *IdTypedef
       = TypedefDecl::Create(Context, CurContext, SourceLocation(),
                             &Context.Idents.get("id"), IdInfo);
     PushOnScopeChains(IdTypedef, TUScope);
     Context.setObjCIdType(Context.getTypeDeclType(IdTypedef));
     Context.ObjCIdRedefinitionType = Context.getObjCIdType();
   }
   // Create the built-in typedef for 'Class'.
   if (Context.getObjCClassType().isNull()) {
     QualType T = Context.getObjCObjectType(Context.ObjCBuiltinClassTy, 0, 0);
     T = Context.getObjCObjectPointerType(T);
     TypeSourceInfo *ClassInfo = Context.getTrivialTypeSourceInfo(T);
     TypedefDecl *ClassTypedef
       = TypedefDecl::Create(Context, CurContext, SourceLocation(),
                             &Context.Idents.get("Class"), ClassInfo);
     PushOnScopeChains(ClassTypedef, TUScope);
     Context.setObjCClassType(Context.getTypeDeclType(ClassTypedef));
     Context.ObjCClassRedefinitionType = Context.getObjCClassType();
   }
 }

 Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
            bool CompleteTranslationUnit,
            CodeCompleteConsumer *CodeCompleter)
   : TheTargetAttributesSema(0),
     LangOpts(pp.getLangOptions()), PP(pp), Context(ctxt), Consumer(consumer),
     Diags(PP.getDiagnostics()), SourceMgr(PP.getSourceManager()),
     ExternalSource(0), CodeCompleter(CodeCompleter), CurContext(0),
     PackContext(0), VisContext(0), ParsingDeclDepth(0),
     IdResolver(pp.getLangOptions()), GlobalNewDeleteDeclared(false),
     CompleteTranslationUnit(CompleteTranslationUnit),
     NumSFINAEErrors(0), SuppressAccessChecking(false),
     NonInstantiationEntries(0), CurrentInstantiationScope(0), TyposCorrected(0),
     AnalysisWarnings(*this)
 {
   TUScope = 0;
   if (getLangOptions().CPlusPlus)
     FieldCollector.reset(new CXXFieldCollector());

   // Tell diagnostics how to render things from the AST library.
   PP.getDiagnostics().SetArgToStringFn(&FormatASTNodeDiagnosticArgument,
                                        &Context);

   ExprEvalContexts.push_back(
                   ExpressionEvaluationContextRecord(PotentiallyEvaluated, 0));

   FunctionScopes.push_back(new FunctionScopeInfo(Diags.getNumErrors()));
 }

 void Sema::Initialize() {
   // Tell the AST consumer about this Sema object.
   Consumer.Initialize(Context);

   // FIXME: Isn't this redundant with the initialization above?
   if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
     SC->InitializeSema(*this);

   // Tell the external Sema source about this Sema object.
   if (ExternalSemaSource *ExternalSema
       = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
     ExternalSema->InitializeSema(*this);
 }

 Sema::~Sema() {
   if (PackContext) FreePackedContext();
   if (VisContext) FreeVisContext();
   delete TheTargetAttributesSema;

   // Kill all the active scopes.
   for (unsigned I = 1, E = FunctionScopes.size(); I != E; ++I)
     delete FunctionScopes[I];
   if (FunctionScopes.size() == 1)
     delete FunctionScopes[0];

   // Tell the SemaConsumer to forget about us; we're going out of scope.
   if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
     SC->ForgetSema();

   // Detach from the external Sema source.
   if (ExternalSemaSource *ExternalSema
         = dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
     ExternalSema->ForgetSema();
 }

 /// ImpCastExprToType - If Expr is not of type 'Type', insert an implicit cast.
 /// If there is already an implicit cast, merge into the existing one.
 /// The result is of the given category.
 void Sema::ImpCastExprToType(Expr *&Expr, QualType Ty,
                              CastKind Kind, ExprValueKind VK,
                              const CXXCastPath *BasePath) {
   QualType ExprTy = Context.getCanonicalType(Expr->getType());
   QualType TypeTy = Context.getCanonicalType(Ty);

   if (ExprTy == TypeTy)
     return;

   if (Expr->getType()->isPointerType() && Ty->isPointerType()) {
     QualType ExprBaseType = cast<PointerType>(ExprTy)->getPointeeType();
     QualType BaseType = cast<PointerType>(TypeTy)->getPointeeType();
     if (ExprBaseType.getAddressSpace() != BaseType.getAddressSpace()) {
       Diag(Expr->getExprLoc(), diag::err_implicit_pointer_address_space_cast)
         << Expr->getSourceRange();
     }
   }

   // If this is a derived-to-base cast to a through a virtual base, we
   // need a vtable.
   if (Kind == CK_DerivedToBase &&
       BasePathInvolvesVirtualBase(*BasePath)) {
     QualType T = Expr->getType();
     if (const PointerType *Pointer = T->getAs<PointerType>())
       T = Pointer->getPointeeType();
     if (const RecordType *RecordTy = T->getAs<RecordType>())
       MarkVTableUsed(Expr->getLocStart(),
                      cast<CXXRecordDecl>(RecordTy->getDecl()));
   }

   if (ImplicitCastExpr *ImpCast = dyn_cast<ImplicitCastExpr>(Expr)) {
     if (ImpCast->getCastKind() == Kind && (!BasePath || BasePath->empty())) {
       ImpCast->setType(Ty);
       ImpCast->setValueKind(VK);
       return;
     }
   }

   Expr = ImplicitCastExpr::Create(Context, Ty, Kind, Expr, BasePath, VK);
 }

 ExprValueKind Sema::CastCategory(Expr *E) {
   Expr::Classification Classification = E->Classify(Context);
   return Classification.isRValue() ? VK_RValue :
       (Classification.isLValue() ? VK_LValue : VK_XValue);
 }

 void Sema::DeleteExpr(ExprTy *E) {
 }
 void Sema::DeleteStmt(StmtTy *S) {
 }

 /// \brief Used to prune the decls of Sema's UnusedFileScopedDecls vector.
 static bool ShouldRemoveFromUnused(Sema *SemaRef, const DeclaratorDecl *D) {
   if (D->isUsed())
     return true;

   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
     // UnusedFileScopedDecls stores the first declaration.
     // The declaration may have become definition so check again.
     const FunctionDecl *DeclToCheck;
     if (FD->hasBody(DeclToCheck))
       return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);

     // Later redecls may add new information resulting in not having to warn,
     // so check again.
     DeclToCheck = FD->getMostRecentDeclaration();
     if (DeclToCheck != FD)
       return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
   }

   if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
     // UnusedFileScopedDecls stores the first declaration.
     // The declaration may have become definition so check again.
     const VarDecl *DeclToCheck = VD->getDefinition();
     if (DeclToCheck)
       return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);

     // Later redecls may add new information resulting in not having to warn,
     // so check again.
     DeclToCheck = VD->getMostRecentDeclaration();
     if (DeclToCheck != VD)
       return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
   }

   return false;
 }

 /// ActOnEndOfTranslationUnit - This is called at the very end of the
 /// translation unit when EOF is reached and all but the top-level scope is
 /// popped.
 void Sema::ActOnEndOfTranslationUnit() {
   // At PCH writing, implicit instantiations and VTable handling info are
   // stored and performed when the PCH is included.
   if (CompleteTranslationUnit)
     while (1) {
       // C++: Perform implicit template instantiations.
       //
       // FIXME: When we perform these implicit instantiations, we do not
       // carefully keep track of the point of instantiation (C++ [temp.point]).
       // This means that name lookup that occurs within the template
       // instantiation will always happen at the end of the translation unit,
       // so it will find some names that should not be found. Although this is
       // common behavior for C++ compilers, it is technically wrong. In the
       // future, we either need to be able to filter the results of name lookup
       // or we need to perform template instantiations earlier.
       PerformPendingInstantiations();

       /// If DefinedUsedVTables ends up marking any virtual member
       /// functions it might lead to more pending template
       /// instantiations, which is why we need to loop here.
       if (!DefineUsedVTables())
         break;
     }

   // Remove file scoped decls that turned out to be used.
   UnusedFileScopedDecls.erase(std::remove_if(UnusedFileScopedDecls.begin(),
                                              UnusedFileScopedDecls.end(),
                               std::bind1st(std::ptr_fun(ShouldRemoveFromUnused),
                                            this)),
                               UnusedFileScopedDecls.end());

   if (!CompleteTranslationUnit) {
     TUScope = 0;
     return;
   }

   // Check for #pragma weak identifiers that were never declared
   // FIXME: This will cause diagnostics to be emitted in a non-determinstic
   // order!  Iterating over a densemap like this is bad.
   for (llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator
        I = WeakUndeclaredIdentifiers.begin(),
        E = WeakUndeclaredIdentifiers.end(); I != E; ++I) {
     if (I->second.getUsed()) continue;

     Diag(I->second.getLocation(), diag::warn_weak_identifier_undeclared)
       << I->first;
   }

   // C99 6.9.2p2:
   //   A declaration of an identifier for an object that has file
   //   scope without an initializer, and without a storage-class
   //   specifier or with the storage-class specifier static,
   //   constitutes a tentative definition. If a translation unit
   //   contains one or more tentative definitions for an identifier,
   //   and the translation unit contains no external definition for
   //   that identifier, then the behavior is exactly as if the
   //   translation unit contains a file scope declaration of that
   //   identifier, with the composite type as of the end of the
   //   translation unit, with an initializer equal to 0.
   llvm::SmallSet<VarDecl *, 32> Seen;
   for (unsigned i = 0, e = TentativeDefinitions.size(); i != e; ++i) {
     VarDecl *VD = TentativeDefinitions[i]->getActingDefinition();

     // If the tentative definition was completed, getActingDefinition() returns
     // null. If we've already seen this variable before, insert()'s second
     // return value is false.
     if (VD == 0 || VD->isInvalidDecl() || !Seen.insert(VD))
       continue;

     if (const IncompleteArrayType *ArrayT
         = Context.getAsIncompleteArrayType(VD->getType())) {
       if (RequireCompleteType(VD->getLocation(),
                               ArrayT->getElementType(),
                               diag::err_tentative_def_incomplete_type_arr)) {
         VD->setInvalidDecl();
         continue;
       }

       // Set the length of the array to 1 (C99 6.9.2p5).
       Diag(VD->getLocation(), diag::warn_tentative_incomplete_array);
       llvm::APInt One(Context.getTypeSize(Context.getSizeType()), true);
       QualType T = Context.getConstantArrayType(ArrayT->getElementType(),
                                                 One, ArrayType::Normal, 0);
       VD->setType(T);
     } else if (RequireCompleteType(VD->getLocation(), VD->getType(),
                                    diag::err_tentative_def_incomplete_type))
       VD->setInvalidDecl();

     // Notify the consumer that we've completed a tentative definition.
     if (!VD->isInvalidDecl())
       Consumer.CompleteTentativeDefinition(VD);

   }

   // Output warning for unused file scoped decls.
   for (llvm::SmallVectorImpl<const DeclaratorDecl*>::iterator
          I = UnusedFileScopedDecls.begin(),
          E = UnusedFileScopedDecls.end(); I != E; ++I) {
     if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(*I)) {
       const FunctionDecl *DiagD;
       if (!FD->hasBody(DiagD))
         DiagD = FD;
       Diag(DiagD->getLocation(),
            isa<CXXMethodDecl>(DiagD) ? diag::warn_unused_member_function
                                      : diag::warn_unused_function)
             << DiagD->getDeclName();
     } else {
       const VarDecl *DiagD = cast<VarDecl>(*I)->getDefinition();
       if (!DiagD)
         DiagD = cast<VarDecl>(*I);
       Diag(DiagD->getLocation(), diag::warn_unused_variable)
             << DiagD->getDeclName();
     }
   }

   TUScope = 0;
 }


 //===----------------------------------------------------------------------===//
 // Helper functions.
 //===----------------------------------------------------------------------===//

 DeclContext *Sema::getFunctionLevelDeclContext() {
   DeclContext *DC = CurContext;

   while (isa<BlockDecl>(DC) || isa<EnumDecl>(DC))
     DC = DC->getParent();

   return DC;
 }

 /// getCurFunctionDecl - If inside of a function body, this returns a pointer
 /// to the function decl for the function being parsed.  If we're currently
 /// in a 'block', this returns the containing context.
 FunctionDecl *Sema::getCurFunctionDecl() {
   DeclContext *DC = getFunctionLevelDeclContext();
   return dyn_cast<FunctionDecl>(DC);
 }

 ObjCMethodDecl *Sema::getCurMethodDecl() {
   DeclContext *DC = getFunctionLevelDeclContext();
   return dyn_cast<ObjCMethodDecl>(DC);
 }

 NamedDecl *Sema::getCurFunctionOrMethodDecl() {
   DeclContext *DC = getFunctionLevelDeclContext();
   if (isa<ObjCMethodDecl>(DC) || isa<FunctionDecl>(DC))
     return cast<NamedDecl>(DC);
   return 0;
 }

 Sema::SemaDiagnosticBuilder::~SemaDiagnosticBuilder() {
   if (!this->Emit())
     return;

   // If this is not a note, and we're in a template instantiation
   // that is different from the last template instantiation where
   // we emitted an error, print a template instantiation
   // backtrace.
   if (!SemaRef.Diags.isBuiltinNote(DiagID) &&
       !SemaRef.ActiveTemplateInstantiations.empty() &&
       SemaRef.ActiveTemplateInstantiations.back()
         != SemaRef.LastTemplateInstantiationErrorContext) {
     SemaRef.PrintInstantiationStack();
     SemaRef.LastTemplateInstantiationErrorContext
       = SemaRef.ActiveTemplateInstantiations.back();
   }
 }

 Sema::SemaDiagnosticBuilder Sema::Diag(SourceLocation Loc, unsigned DiagID) {
   if (isSFINAEContext()) {
     switch (Diagnostic::getDiagnosticSFINAEResponse(DiagID)) {
     case Diagnostic::SFINAE_Report:
       // Fall through; we'll report the diagnostic below.
       break;

     case Diagnostic::SFINAE_SubstitutionFailure:
       // Count this failure so that we know that template argument deduction
       // has failed.
       ++NumSFINAEErrors;
       // Fall through

     case Diagnostic::SFINAE_Suppress:
       // Suppress this diagnostic.
       Diags.setLastDiagnosticIgnored();
       return SemaDiagnosticBuilder(*this);
     }
   }

   DiagnosticBuilder DB = Diags.Report(FullSourceLoc(Loc, SourceMgr), DiagID);
   return SemaDiagnosticBuilder(DB, *this, DiagID);
 }

 Sema::SemaDiagnosticBuilder
 Sema::Diag(SourceLocation Loc, const PartialDiagnostic& PD) {
   SemaDiagnosticBuilder Builder(Diag(Loc, PD.getDiagID()));
   PD.Emit(Builder);

   return Builder;
 }

 /// \brief Determines the active Scope associated with the given declaration
 /// context.
 ///
 /// This routine maps a declaration context to the active Scope object that
 /// represents that declaration context in the parser. It is typically used
 /// from "scope-less" code (e.g., template instantiation, lazy creation of
 /// declarations) that injects a name for name-lookup purposes and, therefore,
 /// must update the Scope.
 ///
 /// \returns The scope corresponding to the given declaraion context, or NULL
 /// if no such scope is open.
 Scope *Sema::getScopeForContext(DeclContext *Ctx) {

   if (!Ctx)
     return 0;

   Ctx = Ctx->getPrimaryContext();
   for (Scope *S = getCurScope(); S; S = S->getParent()) {
     // Ignore scopes that cannot have declarations. This is important for
     // out-of-line definitions of static class members.
     if (S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope))
       if (DeclContext *Entity = static_cast<DeclContext *> (S->getEntity()))
         if (Ctx == Entity->getPrimaryContext())
           return S;
   }

   return 0;
 }

 /// \brief Enter a new function scope
 void Sema::PushFunctionScope() {
   if (FunctionScopes.size() == 1) {
     // Use the "top" function scope rather than having to allocate
     // memory for a new scope.
     FunctionScopes.back()->Clear(getDiagnostics().getNumErrors());
     FunctionScopes.push_back(FunctionScopes.back());
     return;
   }

   FunctionScopes.push_back(
                       new FunctionScopeInfo(getDiagnostics().getNumErrors()));
 }

 void Sema::PushBlockScope(Scope *BlockScope, BlockDecl *Block) {
   FunctionScopes.push_back(new BlockScopeInfo(getDiagnostics().getNumErrors(),
                                               BlockScope, Block));
 }

 void Sema::PopFunctionOrBlockScope() {
   FunctionScopeInfo *Scope = FunctionScopes.pop_back_val();
   assert(!FunctionScopes.empty() && "mismatched push/pop!");
   if (FunctionScopes.back() != Scope)
     delete Scope;
 }

 /// \brief Determine whether any errors occurred within this function/method/
 /// block.
 bool Sema::hasAnyErrorsInThisFunction() const {
   return getCurFunction()->NumErrorsAtStartOfFunction
              != getDiagnostics().getNumErrors();
 }

 BlockScopeInfo *Sema::getCurBlock() {
   if (FunctionScopes.empty())
     return 0;

   return dyn_cast<BlockScopeInfo>(FunctionScopes.back());
 }

 // Pin this vtable to this file.
 ExternalSemaSource::~ExternalSemaSource() {}
	//===--- Sema.cpp - AST Builder and Semantic Analysis Implementation ------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file implements the actions class which performs semantic analysis and
	// builds an AST out of a parse stream.
	//
	//===----------------------------------------------------------------------===//

	#include "clang/Sema/Sema.h"
	#include "TargetAttributesSema.h"
	#include "llvm/ADT/DenseMap.h"
	#include "llvm/ADT/SmallSet.h"
	#include "llvm/ADT/APFloat.h"
	#include "clang/Sema/CXXFieldCollector.h"
	#include "clang/Sema/ExternalSemaSource.h"
	#include "clang/Sema/Scope.h"
	#include "clang/Sema/ScopeInfo.h"
	#include "clang/Sema/SemaConsumer.h"
	#include "clang/AST/ASTContext.h"
	#include "clang/AST/ASTDiagnostic.h"
	#include "clang/AST/DeclCXX.h"
	#include "clang/AST/DeclObjC.h"
	#include "clang/AST/Expr.h"
	#include "clang/Lex/Preprocessor.h"
	#include "clang/Basic/PartialDiagnostic.h"
	#include "clang/Basic/TargetInfo.h"
	using namespace clang;
	using namespace sema;

	FunctionScopeInfo::~FunctionScopeInfo() { }

	void FunctionScopeInfo::Clear(unsigned NumErrors) {
	HasBranchProtectedScope = false;
	HasBranchIntoScope = false;
	HasIndirectGoto = false;

	LabelMap.clear();
	SwitchStack.clear();
	Returns.clear();
	NumErrorsAtStartOfFunction = NumErrors;
	}

	BlockScopeInfo::~BlockScopeInfo() { }

	void Sema::ActOnTranslationUnitScope(SourceLocation Loc, Scope *S) {
	TUScope = S;
	PushDeclContext(S, Context.getTranslationUnitDecl());

	VAListTagName = PP.getIdentifierInfo("__va_list_tag");

	if (!Context.isInt128Installed() && // May be set by ASTReader.
	PP.getTargetInfo().getPointerWidth(0) >= 64) {
	TypeSourceInfo *TInfo;

	// Install [u]int128_t for 64-bit targets.
	TInfo = Context.getTrivialTypeSourceInfo(Context.Int128Ty);
	PushOnScopeChains(TypedefDecl::Create(Context, CurContext,
	SourceLocation(),
	&Context.Idents.get("__int128_t"),
	TInfo), TUScope);

	TInfo = Context.getTrivialTypeSourceInfo(Context.UnsignedInt128Ty);
	PushOnScopeChains(TypedefDecl::Create(Context, CurContext,
	SourceLocation(),
	&Context.Idents.get("__uint128_t"),
	TInfo), TUScope);
	Context.setInt128Installed();
	}


	if (!PP.getLangOptions().ObjC1) return;

	// Built-in ObjC types may already be set by ASTReader (hence isNull checks).
	if (Context.getObjCSelType().isNull()) {
	// Create the built-in typedef for 'SEL'.
	QualType SelT = Context.getPointerType(Context.ObjCBuiltinSelTy);
	TypeSourceInfo *SelInfo = Context.getTrivialTypeSourceInfo(SelT);
	TypedefDecl *SelTypedef
	= TypedefDecl::Create(Context, CurContext, SourceLocation(),
	&Context.Idents.get("SEL"), SelInfo);
	PushOnScopeChains(SelTypedef, TUScope);
	Context.setObjCSelType(Context.getTypeDeclType(SelTypedef));
	Context.ObjCSelRedefinitionType = Context.getObjCSelType();
	}

	// Synthesize "@class Protocol;
	if (Context.getObjCProtoType().isNull()) {
	ObjCInterfaceDecl *ProtocolDecl =
	ObjCInterfaceDecl::Create(Context, CurContext, SourceLocation(),
	&Context.Idents.get("Protocol"),
	SourceLocation(), true);
	Context.setObjCProtoType(Context.getObjCInterfaceType(ProtocolDecl));
	PushOnScopeChains(ProtocolDecl, TUScope, false);
	}
	// Create the built-in typedef for 'id'.
	if (Context.getObjCIdType().isNull()) {
	QualType T = Context.getObjCObjectType(Context.ObjCBuiltinIdTy, 0, 0);
	T = Context.getObjCObjectPointerType(T);
	TypeSourceInfo *IdInfo = Context.getTrivialTypeSourceInfo(T);
	TypedefDecl *IdTypedef
	= TypedefDecl::Create(Context, CurContext, SourceLocation(),
	&Context.Idents.get("id"), IdInfo);
	PushOnScopeChains(IdTypedef, TUScope);
	Context.setObjCIdType(Context.getTypeDeclType(IdTypedef));
	Context.ObjCIdRedefinitionType = Context.getObjCIdType();
	}
	// Create the built-in typedef for 'Class'.
	if (Context.getObjCClassType().isNull()) {
	QualType T = Context.getObjCObjectType(Context.ObjCBuiltinClassTy, 0, 0);
	T = Context.getObjCObjectPointerType(T);
	TypeSourceInfo *ClassInfo = Context.getTrivialTypeSourceInfo(T);
	TypedefDecl *ClassTypedef
	= TypedefDecl::Create(Context, CurContext, SourceLocation(),
	&Context.Idents.get("Class"), ClassInfo);
	PushOnScopeChains(ClassTypedef, TUScope);
	Context.setObjCClassType(Context.getTypeDeclType(ClassTypedef));
	Context.ObjCClassRedefinitionType = Context.getObjCClassType();
	}
	}

	Sema::Sema(Preprocessor &pp, ASTContext &ctxt, ASTConsumer &consumer,
	bool CompleteTranslationUnit,
	CodeCompleteConsumer *CodeCompleter)
	: TheTargetAttributesSema(0),
	LangOpts(pp.getLangOptions()), PP(pp), Context(ctxt), Consumer(consumer),
	Diags(PP.getDiagnostics()), SourceMgr(PP.getSourceManager()),
	ExternalSource(0), CodeCompleter(CodeCompleter), CurContext(0),
	PackContext(0), VisContext(0), ParsingDeclDepth(0),
	IdResolver(pp.getLangOptions()), GlobalNewDeleteDeclared(false),
	CompleteTranslationUnit(CompleteTranslationUnit),
	NumSFINAEErrors(0), SuppressAccessChecking(false),
	NonInstantiationEntries(0), CurrentInstantiationScope(0), TyposCorrected(0),
	AnalysisWarnings(*this)
	{
	TUScope = 0;
	if (getLangOptions().CPlusPlus)
	FieldCollector.reset(new CXXFieldCollector());

	// Tell diagnostics how to render things from the AST library.
	PP.getDiagnostics().SetArgToStringFn(&FormatASTNodeDiagnosticArgument,
	&Context);

	ExprEvalContexts.push_back(
	ExpressionEvaluationContextRecord(PotentiallyEvaluated, 0));

	FunctionScopes.push_back(new FunctionScopeInfo(Diags.getNumErrors()));
	}

	void Sema::Initialize() {
	// Tell the AST consumer about this Sema object.
	Consumer.Initialize(Context);

	// FIXME: Isn't this redundant with the initialization above?
	if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
	SC->InitializeSema(*this);

	// Tell the external Sema source about this Sema object.
	if (ExternalSemaSource *ExternalSema
	= dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
	ExternalSema->InitializeSema(*this);
	}

	Sema::~Sema() {
	if (PackContext) FreePackedContext();
	if (VisContext) FreeVisContext();
	delete TheTargetAttributesSema;

	// Kill all the active scopes.
	for (unsigned I = 1, E = FunctionScopes.size(); I != E; ++I)
	delete FunctionScopes[I];
	if (FunctionScopes.size() == 1)
	delete FunctionScopes[0];

	// Tell the SemaConsumer to forget about us; we're going out of scope.
	if (SemaConsumer *SC = dyn_cast<SemaConsumer>(&Consumer))
	SC->ForgetSema();

	// Detach from the external Sema source.
	if (ExternalSemaSource *ExternalSema
	= dyn_cast_or_null<ExternalSemaSource>(Context.getExternalSource()))
	ExternalSema->ForgetSema();
	}

	/// ImpCastExprToType - If Expr is not of type 'Type', insert an implicit cast.
	/// If there is already an implicit cast, merge into the existing one.
	/// The result is of the given category.
	void Sema::ImpCastExprToType(Expr *&Expr, QualType Ty,
	CastKind Kind, ExprValueKind VK,
	const CXXCastPath *BasePath) {
	QualType ExprTy = Context.getCanonicalType(Expr->getType());
	QualType TypeTy = Context.getCanonicalType(Ty);

	if (ExprTy == TypeTy)
	return;

	if (Expr->getType()->isPointerType() && Ty->isPointerType()) {
	QualType ExprBaseType = cast<PointerType>(ExprTy)->getPointeeType();
	QualType BaseType = cast<PointerType>(TypeTy)->getPointeeType();
	if (ExprBaseType.getAddressSpace() != BaseType.getAddressSpace()) {
	Diag(Expr->getExprLoc(), diag::err_implicit_pointer_address_space_cast)
	<< Expr->getSourceRange();
	}
	}

	// If this is a derived-to-base cast to a through a virtual base, we
	// need a vtable.
	if (Kind == CK_DerivedToBase &&
	BasePathInvolvesVirtualBase(*BasePath)) {
	QualType T = Expr->getType();
	if (const PointerType *Pointer = T->getAs<PointerType>())
	T = Pointer->getPointeeType();
	if (const RecordType *RecordTy = T->getAs<RecordType>())
	MarkVTableUsed(Expr->getLocStart(),
	cast<CXXRecordDecl>(RecordTy->getDecl()));
	}

	if (ImplicitCastExpr *ImpCast = dyn_cast<ImplicitCastExpr>(Expr)) {
	if (ImpCast->getCastKind() == Kind && (!BasePath \|\| BasePath->empty())) {
	ImpCast->setType(Ty);
	ImpCast->setValueKind(VK);
	return;
	}
	}

	Expr = ImplicitCastExpr::Create(Context, Ty, Kind, Expr, BasePath, VK);
	}

	ExprValueKind Sema::CastCategory(Expr *E) {
	Expr::Classification Classification = E->Classify(Context);
	return Classification.isRValue() ? VK_RValue :
	(Classification.isLValue() ? VK_LValue : VK_XValue);
	}

	void Sema::DeleteExpr(ExprTy *E) {
	}
	void Sema::DeleteStmt(StmtTy *S) {
	}

	/// \brief Used to prune the decls of Sema's UnusedFileScopedDecls vector.
	static bool ShouldRemoveFromUnused(Sema SemaRef, const DeclaratorDecl D) {
	if (D->isUsed())
	return true;

	if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
	// UnusedFileScopedDecls stores the first declaration.
	// The declaration may have become definition so check again.
	const FunctionDecl *DeclToCheck;
	if (FD->hasBody(DeclToCheck))
	return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);

	// Later redecls may add new information resulting in not having to warn,
	// so check again.
	DeclToCheck = FD->getMostRecentDeclaration();
	if (DeclToCheck != FD)
	return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
	}

	if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
	// UnusedFileScopedDecls stores the first declaration.
	// The declaration may have become definition so check again.
	const VarDecl *DeclToCheck = VD->getDefinition();
	if (DeclToCheck)
	return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);

	// Later redecls may add new information resulting in not having to warn,
	// so check again.
	DeclToCheck = VD->getMostRecentDeclaration();
	if (DeclToCheck != VD)
	return !SemaRef->ShouldWarnIfUnusedFileScopedDecl(DeclToCheck);
	}

	return false;
	}

	/// ActOnEndOfTranslationUnit - This is called at the very end of the
	/// translation unit when EOF is reached and all but the top-level scope is
	/// popped.
	void Sema::ActOnEndOfTranslationUnit() {
	// At PCH writing, implicit instantiations and VTable handling info are
	// stored and performed when the PCH is included.
	if (CompleteTranslationUnit)
	while (1) {
	// C++: Perform implicit template instantiations.
	//
	// FIXME: When we perform these implicit instantiations, we do not
	// carefully keep track of the point of instantiation (C++ [temp.point]).
	// This means that name lookup that occurs within the template
	// instantiation will always happen at the end of the translation unit,
	// so it will find some names that should not be found. Although this is
	// common behavior for C++ compilers, it is technically wrong. In the
	// future, we either need to be able to filter the results of name lookup
	// or we need to perform template instantiations earlier.
	PerformPendingInstantiations();

	/// If DefinedUsedVTables ends up marking any virtual member
	/// functions it might lead to more pending template
	/// instantiations, which is why we need to loop here.
	if (!DefineUsedVTables())
	break;
	}

	// Remove file scoped decls that turned out to be used.
	UnusedFileScopedDecls.erase(std::remove_if(UnusedFileScopedDecls.begin(),
	UnusedFileScopedDecls.end(),
	std::bind1st(std::ptr_fun(ShouldRemoveFromUnused),
	this)),
	UnusedFileScopedDecls.end());

	if (!CompleteTranslationUnit) {
	TUScope = 0;
	return;
	}

	// Check for #pragma weak identifiers that were never declared
	// FIXME: This will cause diagnostics to be emitted in a non-determinstic
	// order! Iterating over a densemap like this is bad.
	for (llvm::DenseMap<IdentifierInfo*,WeakInfo>::iterator
	I = WeakUndeclaredIdentifiers.begin(),
	E = WeakUndeclaredIdentifiers.end(); I != E; ++I) {
	if (I->second.getUsed()) continue;

	Diag(I->second.getLocation(), diag::warn_weak_identifier_undeclared)
	<< I->first;
	}

	// C99 6.9.2p2:
	// A declaration of an identifier for an object that has file
	// scope without an initializer, and without a storage-class
	// specifier or with the storage-class specifier static,
	// constitutes a tentative definition. If a translation unit
	// contains one or more tentative definitions for an identifier,
	// and the translation unit contains no external definition for
	// that identifier, then the behavior is exactly as if the
	// translation unit contains a file scope declaration of that
	// identifier, with the composite type as of the end of the
	// translation unit, with an initializer equal to 0.
	llvm::SmallSet<VarDecl *, 32> Seen;
	for (unsigned i = 0, e = TentativeDefinitions.size(); i != e; ++i) {
	VarDecl *VD = TentativeDefinitions[i]->getActingDefinition();

	// If the tentative definition was completed, getActingDefinition() returns
	// null. If we've already seen this variable before, insert()'s second
	// return value is false.
	if (VD == 0 \|\| VD->isInvalidDecl() \|\| !Seen.insert(VD))
	continue;

	if (const IncompleteArrayType *ArrayT
	= Context.getAsIncompleteArrayType(VD->getType())) {
	if (RequireCompleteType(VD->getLocation(),
	ArrayT->getElementType(),
	diag::err_tentative_def_incomplete_type_arr)) {
	VD->setInvalidDecl();
	continue;
	}

	// Set the length of the array to 1 (C99 6.9.2p5).
	Diag(VD->getLocation(), diag::warn_tentative_incomplete_array);
	llvm::APInt One(Context.getTypeSize(Context.getSizeType()), true);
	QualType T = Context.getConstantArrayType(ArrayT->getElementType(),
	One, ArrayType::Normal, 0);
	VD->setType(T);
	} else if (RequireCompleteType(VD->getLocation(), VD->getType(),
	diag::err_tentative_def_incomplete_type))
	VD->setInvalidDecl();

	// Notify the consumer that we've completed a tentative definition.
	if (!VD->isInvalidDecl())
	Consumer.CompleteTentativeDefinition(VD);

	}

	// Output warning for unused file scoped decls.
	for (llvm::SmallVectorImpl<const DeclaratorDecl*>::iterator
	I = UnusedFileScopedDecls.begin(),
	E = UnusedFileScopedDecls.end(); I != E; ++I) {
	if (const FunctionDecl FD = dyn_cast<FunctionDecl>(I)) {
	const FunctionDecl *DiagD;
	if (!FD->hasBody(DiagD))
	DiagD = FD;
	Diag(DiagD->getLocation(),
	isa<CXXMethodDecl>(DiagD) ? diag::warn_unused_member_function
	: diag::warn_unused_function)
	<< DiagD->getDeclName();
	} else {
	const VarDecl DiagD = cast<VarDecl>(I)->getDefinition();
	if (!DiagD)
	DiagD = cast<VarDecl>(*I);
	Diag(DiagD->getLocation(), diag::warn_unused_variable)
	<< DiagD->getDeclName();
	}
	}

	TUScope = 0;
	}


	//===----------------------------------------------------------------------===//
	// Helper functions.
	//===----------------------------------------------------------------------===//

	DeclContext *Sema::getFunctionLevelDeclContext() {
	DeclContext *DC = CurContext;

	while (isa<BlockDecl>(DC) \|\| isa<EnumDecl>(DC))
	DC = DC->getParent();

	return DC;
	}

	/// getCurFunctionDecl - If inside of a function body, this returns a pointer
	/// to the function decl for the function being parsed. If we're currently
	/// in a 'block', this returns the containing context.
	FunctionDecl *Sema::getCurFunctionDecl() {
	DeclContext *DC = getFunctionLevelDeclContext();
	return dyn_cast<FunctionDecl>(DC);
	}

	ObjCMethodDecl *Sema::getCurMethodDecl() {
	DeclContext *DC = getFunctionLevelDeclContext();
	return dyn_cast<ObjCMethodDecl>(DC);
	}

	NamedDecl *Sema::getCurFunctionOrMethodDecl() {
	DeclContext *DC = getFunctionLevelDeclContext();
	if (isa<ObjCMethodDecl>(DC) \|\| isa<FunctionDecl>(DC))
	return cast<NamedDecl>(DC);
	return 0;
	}

	Sema::SemaDiagnosticBuilder::~SemaDiagnosticBuilder() {
	if (!this->Emit())
	return;

	// If this is not a note, and we're in a template instantiation
	// that is different from the last template instantiation where
	// we emitted an error, print a template instantiation
	// backtrace.
	if (!SemaRef.Diags.isBuiltinNote(DiagID) &&
	!SemaRef.ActiveTemplateInstantiations.empty() &&
	SemaRef.ActiveTemplateInstantiations.back()
	!= SemaRef.LastTemplateInstantiationErrorContext) {
	SemaRef.PrintInstantiationStack();
	SemaRef.LastTemplateInstantiationErrorContext
	= SemaRef.ActiveTemplateInstantiations.back();
	}
	}

	Sema::SemaDiagnosticBuilder Sema::Diag(SourceLocation Loc, unsigned DiagID) {
	if (isSFINAEContext()) {
	switch (Diagnostic::getDiagnosticSFINAEResponse(DiagID)) {
	case Diagnostic::SFINAE_Report:
	// Fall through; we'll report the diagnostic below.
	break;

	case Diagnostic::SFINAE_SubstitutionFailure:
	// Count this failure so that we know that template argument deduction
	// has failed.
	++NumSFINAEErrors;
	// Fall through

	case Diagnostic::SFINAE_Suppress:
	// Suppress this diagnostic.
	Diags.setLastDiagnosticIgnored();
	return SemaDiagnosticBuilder(*this);
	}
	}

	DiagnosticBuilder DB = Diags.Report(FullSourceLoc(Loc, SourceMgr), DiagID);
	return SemaDiagnosticBuilder(DB, *this, DiagID);
	}

	Sema::SemaDiagnosticBuilder
	Sema::Diag(SourceLocation Loc, const PartialDiagnostic& PD) {
	SemaDiagnosticBuilder Builder(Diag(Loc, PD.getDiagID()));
	PD.Emit(Builder);

	return Builder;
	}

	/// \brief Determines the active Scope associated with the given declaration
	/// context.
	///
	/// This routine maps a declaration context to the active Scope object that
	/// represents that declaration context in the parser. It is typically used
	/// from "scope-less" code (e.g., template instantiation, lazy creation of
	/// declarations) that injects a name for name-lookup purposes and, therefore,
	/// must update the Scope.
	///
	/// \returns The scope corresponding to the given declaraion context, or NULL
	/// if no such scope is open.
	Scope Sema::getScopeForContext(DeclContext Ctx) {

	if (!Ctx)
	return 0;

	Ctx = Ctx->getPrimaryContext();
	for (Scope *S = getCurScope(); S; S = S->getParent()) {
	// Ignore scopes that cannot have declarations. This is important for
	// out-of-line definitions of static class members.
	if (S->getFlags() & (Scope::DeclScope \| Scope::TemplateParamScope))
	if (DeclContext Entity = static_cast<DeclContext > (S->getEntity()))
	if (Ctx == Entity->getPrimaryContext())
	return S;
	}

	return 0;
	}

	/// \brief Enter a new function scope
	void Sema::PushFunctionScope() {
	if (FunctionScopes.size() == 1) {
	// Use the "top" function scope rather than having to allocate
	// memory for a new scope.
	FunctionScopes.back()->Clear(getDiagnostics().getNumErrors());
	FunctionScopes.push_back(FunctionScopes.back());
	return;
	}

	FunctionScopes.push_back(
	new FunctionScopeInfo(getDiagnostics().getNumErrors()));
	}

	void Sema::PushBlockScope(Scope BlockScope, BlockDecl Block) {
	FunctionScopes.push_back(new BlockScopeInfo(getDiagnostics().getNumErrors(),
	BlockScope, Block));
	}

	void Sema::PopFunctionOrBlockScope() {
	FunctionScopeInfo *Scope = FunctionScopes.pop_back_val();
	assert(!FunctionScopes.empty() && "mismatched push/pop!");
	if (FunctionScopes.back() != Scope)
	delete Scope;
	}

	/// \brief Determine whether any errors occurred within this function/method/
	/// block.
	bool Sema::hasAnyErrorsInThisFunction() const {
	return getCurFunction()->NumErrorsAtStartOfFunction
	!= getDiagnostics().getNumErrors();
	}

	BlockScopeInfo *Sema::getCurBlock() {
	if (FunctionScopes.empty())
	return 0;

	return dyn_cast<BlockScopeInfo>(FunctionScopes.back());
	}

	// Pin this vtable to this file.
	ExternalSemaSource::~ExternalSemaSource() {}