SemaDeclCXX.cpp

//===------ SemaDeclCXX.cpp - Semantic Analysis for C++ Declarations ------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  This file implements semantic analysis for C++ declarations.
//
//===----------------------------------------------------------------------===//

#include "Sema.h"
#include "SemaInherit.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/TypeOrdering.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Parse/DeclSpec.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/Compiler.h"
#include <algorithm> // for std::equal
#include <map>

using namespace clang;

//===----------------------------------------------------------------------===//
// CheckDefaultArgumentVisitor
//===----------------------------------------------------------------------===//

namespace {
  /// CheckDefaultArgumentVisitor - C++ [dcl.fct.default] Traverses
  /// the default argument of a parameter to determine whether it
  /// contains any ill-formed subexpressions. For example, this will
  /// diagnose the use of local variables or parameters within the
  /// default argument expression.
  class VISIBILITY_HIDDEN CheckDefaultArgumentVisitor 
    : public StmtVisitor<CheckDefaultArgumentVisitor, bool> {
    Expr *DefaultArg;
    Sema *S;

  public:
    CheckDefaultArgumentVisitor(Expr *defarg, Sema *s) 
      : DefaultArg(defarg), S(s) {}

    bool VisitExpr(Expr *Node);
    bool VisitDeclRefExpr(DeclRefExpr *DRE);
    bool VisitCXXThisExpr(CXXThisExpr *ThisE);
  };

  /// VisitExpr - Visit all of the children of this expression.
  bool CheckDefaultArgumentVisitor::VisitExpr(Expr *Node) {
    bool IsInvalid = false;
    for (Stmt::child_iterator I = Node->child_begin(), 
         E = Node->child_end(); I != E; ++I)
      IsInvalid |= Visit(*I);
    return IsInvalid;
  }

  /// VisitDeclRefExpr - Visit a reference to a declaration, to
  /// determine whether this declaration can be used in the default
  /// argument expression.
  bool CheckDefaultArgumentVisitor::VisitDeclRefExpr(DeclRefExpr *DRE) {
    NamedDecl *Decl = DRE->getDecl();
    if (ParmVarDecl *Param = dyn_cast<ParmVarDecl>(Decl)) {
      // C++ [dcl.fct.default]p9
      //   Default arguments are evaluated each time the function is
      //   called. The order of evaluation of function arguments is
      //   unspecified. Consequently, parameters of a function shall not
      //   be used in default argument expressions, even if they are not
      //   evaluated. Parameters of a function declared before a default
      //   argument expression are in scope and can hide namespace and
      //   class member names.
      return S->Diag(DRE->getSourceRange().getBegin(), 
                     diag::err_param_default_argument_references_param)
         << Param->getDeclName() << DefaultArg->getSourceRange();
    } else if (VarDecl *VDecl = dyn_cast<VarDecl>(Decl)) {
      // C++ [dcl.fct.default]p7
      //   Local variables shall not be used in default argument
      //   expressions.
      if (VDecl->isBlockVarDecl())
        return S->Diag(DRE->getSourceRange().getBegin(), 
                       diag::err_param_default_argument_references_local)
          << VDecl->getDeclName() << DefaultArg->getSourceRange();
    }

    return false;
  }

  /// VisitCXXThisExpr - Visit a C++ "this" expression.
  bool CheckDefaultArgumentVisitor::VisitCXXThisExpr(CXXThisExpr *ThisE) {
    // C++ [dcl.fct.default]p8:
    //   The keyword this shall not be used in a default argument of a
    //   member function.
    return S->Diag(ThisE->getSourceRange().getBegin(),
                   diag::err_param_default_argument_references_this)
               << ThisE->getSourceRange();
  }
}

/// ActOnParamDefaultArgument - Check whether the default argument
/// provided for a function parameter is well-formed. If so, attach it
/// to the parameter declaration.
void
Sema::ActOnParamDefaultArgument(DeclTy *param, SourceLocation EqualLoc, 
                                ExprTy *defarg) {
  ParmVarDecl *Param = (ParmVarDecl *)param;
  ExprOwningPtr<Expr> DefaultArg(this, (Expr *)defarg);
  QualType ParamType = Param->getType();

  // Default arguments are only permitted in C++
  if (!getLangOptions().CPlusPlus) {
    Diag(EqualLoc, diag::err_param_default_argument)
      << DefaultArg->getSourceRange();
    Param->setInvalidDecl();
    return;
  }

  // C++ [dcl.fct.default]p5
  //   A default argument expression is implicitly converted (clause
  //   4) to the parameter type. The default argument expression has
  //   the same semantic constraints as the initializer expression in
  //   a declaration of a variable of the parameter type, using the
  //   copy-initialization semantics (8.5).
  Expr *DefaultArgPtr = DefaultArg.get();
  bool DefaultInitFailed = CheckInitializerTypes(DefaultArgPtr, ParamType,
                                                 EqualLoc,
                                                 Param->getDeclName(),
                                                 /*DirectInit=*/false);
  if (DefaultArgPtr != DefaultArg.get()) {
    DefaultArg.take();
    DefaultArg.reset(DefaultArgPtr);
  }
  if (DefaultInitFailed) {
    return;
  }

  // Check that the default argument is well-formed
  CheckDefaultArgumentVisitor DefaultArgChecker(DefaultArg.get(), this);
  if (DefaultArgChecker.Visit(DefaultArg.get())) {
    Param->setInvalidDecl();
    return;
  }

  // Okay: add the default argument to the parameter
  Param->setDefaultArg(DefaultArg.take());
}

/// ActOnParamUnparsedDefaultArgument - We've seen a default
/// argument for a function parameter, but we can't parse it yet
/// because we're inside a class definition. Note that this default
/// argument will be parsed later.
void Sema::ActOnParamUnparsedDefaultArgument(DeclTy *param, 
                                             SourceLocation EqualLoc) {
  ParmVarDecl *Param = (ParmVarDecl*)param;
  if (Param)
    Param->setUnparsedDefaultArg();
}

/// ActOnParamDefaultArgumentError - Parsing or semantic analysis of
/// the default argument for the parameter param failed.
void Sema::ActOnParamDefaultArgumentError(DeclTy *param) {
  ((ParmVarDecl*)param)->setInvalidDecl();
}

/// CheckExtraCXXDefaultArguments - Check for any extra default
/// arguments in the declarator, which is not a function declaration
/// or definition and therefore is not permitted to have default
/// arguments. This routine should be invoked for every declarator
/// that is not a function declaration or definition.
void Sema::CheckExtraCXXDefaultArguments(Declarator &D) {
  // C++ [dcl.fct.default]p3
  //   A default argument expression shall be specified only in the
  //   parameter-declaration-clause of a function declaration or in a
  //   template-parameter (14.1). It shall not be specified for a
  //   parameter pack. If it is specified in a
  //   parameter-declaration-clause, it shall not occur within a
  //   declarator or abstract-declarator of a parameter-declaration.
  for (unsigned i = 0; i < D.getNumTypeObjects(); ++i) {
    DeclaratorChunk &chunk = D.getTypeObject(i);
    if (chunk.Kind == DeclaratorChunk::Function) {
      for (unsigned argIdx = 0; argIdx < chunk.Fun.NumArgs; ++argIdx) {
        ParmVarDecl *Param = (ParmVarDecl *)chunk.Fun.ArgInfo[argIdx].Param;
        if (Param->hasUnparsedDefaultArg()) {
          CachedTokens *Toks = chunk.Fun.ArgInfo[argIdx].DefaultArgTokens;
          Diag(Param->getLocation(), diag::err_param_default_argument_nonfunc)
            << SourceRange((*Toks)[1].getLocation(), Toks->back().getLocation());
          delete Toks;
          chunk.Fun.ArgInfo[argIdx].DefaultArgTokens = 0;
        } else if (Param->getDefaultArg()) {
          Diag(Param->getLocation(), diag::err_param_default_argument_nonfunc)
            << Param->getDefaultArg()->getSourceRange();
          Param->setDefaultArg(0);
        }
      }
    }
  }
}

// MergeCXXFunctionDecl - Merge two declarations of the same C++
// function, once we already know that they have the same
// type. Subroutine of MergeFunctionDecl.
FunctionDecl * 
Sema::MergeCXXFunctionDecl(FunctionDecl *New, FunctionDecl *Old) {
  // C++ [dcl.fct.default]p4:
  //
  //   For non-template functions, default arguments can be added in
  //   later declarations of a function in the same
  //   scope. Declarations in different scopes have completely
  //   distinct sets of default arguments. That is, declarations in
  //   inner scopes do not acquire default arguments from
  //   declarations in outer scopes, and vice versa. In a given
  //   function declaration, all parameters subsequent to a
  //   parameter with a default argument shall have default
  //   arguments supplied in this or previous declarations. A
  //   default argument shall not be redefined by a later
  //   declaration (not even to the same value).
  for (unsigned p = 0, NumParams = Old->getNumParams(); p < NumParams; ++p) {
    ParmVarDecl *OldParam = Old->getParamDecl(p);
    ParmVarDecl *NewParam = New->getParamDecl(p);

    if(OldParam->getDefaultArg() && NewParam->getDefaultArg()) {
      Diag(NewParam->getLocation(), 
           diag::err_param_default_argument_redefinition)
        << NewParam->getDefaultArg()->getSourceRange();
      Diag(OldParam->getLocation(), diag::note_previous_definition);
    } else if (OldParam->getDefaultArg()) {
      // Merge the old default argument into the new parameter
      NewParam->setDefaultArg(OldParam->getDefaultArg());
    }
  }

  return New;  
}

/// CheckCXXDefaultArguments - Verify that the default arguments for a
/// function declaration are well-formed according to C++
/// [dcl.fct.default].
void Sema::CheckCXXDefaultArguments(FunctionDecl *FD) {
  unsigned NumParams = FD->getNumParams();
  unsigned p;

  // Find first parameter with a default argument
  for (p = 0; p < NumParams; ++p) {
    ParmVarDecl *Param = FD->getParamDecl(p);
    if (Param->getDefaultArg())
      break;
  }

  // C++ [dcl.fct.default]p4:
  //   In a given function declaration, all parameters
  //   subsequent to a parameter with a default argument shall
  //   have default arguments supplied in this or previous
  //   declarations. A default argument shall not be redefined
  //   by a later declaration (not even to the same value).
  unsigned LastMissingDefaultArg = 0;
  for(; p < NumParams; ++p) {
    ParmVarDecl *Param = FD->getParamDecl(p);
    if (!Param->getDefaultArg()) {
      if (Param->isInvalidDecl())
        /* We already complained about this parameter. */;
      else if (Param->getIdentifier())
        Diag(Param->getLocation(), 
             diag::err_param_default_argument_missing_name)
          << Param->getIdentifier();
      else
        Diag(Param->getLocation(), 
             diag::err_param_default_argument_missing);
    
      LastMissingDefaultArg = p;
    }
  }

  if (LastMissingDefaultArg > 0) {
    // Some default arguments were missing. Clear out all of the
    // default arguments up to (and including) the last missing
    // default argument, so that we leave the function parameters
    // in a semantically valid state.
    for (p = 0; p <= LastMissingDefaultArg; ++p) {
      ParmVarDecl *Param = FD->getParamDecl(p);
      if (Param->getDefaultArg()) {
        if (!Param->hasUnparsedDefaultArg())
          Param->getDefaultArg()->Destroy(Context);
        Param->setDefaultArg(0);
      }
    }
  }
}

/// isCurrentClassName - Determine whether the identifier II is the
/// name of the class type currently being defined. In the case of
/// nested classes, this will only return true if II is the name of
/// the innermost class.
bool Sema::isCurrentClassName(const IdentifierInfo &II, Scope *,
                              const CXXScopeSpec *SS) {
  CXXRecordDecl *CurDecl;
  if (SS) {
    DeclContext *DC = static_cast<DeclContext*>(SS->getScopeRep());
    CurDecl = dyn_cast_or_null<CXXRecordDecl>(DC);
  } else
    CurDecl = dyn_cast_or_null<CXXRecordDecl>(CurContext);

  if (CurDecl)
    return &II == CurDecl->getIdentifier();
  else
    return false;
}

/// ActOnBaseSpecifier - Parsed a base specifier. A base specifier is
/// one entry in the base class list of a class specifier, for
/// example: 
///    class foo : public bar, virtual private baz { 
/// 'public bar' and 'virtual private baz' are each base-specifiers.
Sema::BaseResult 
Sema::ActOnBaseSpecifier(DeclTy *classdecl, SourceRange SpecifierRange,
                         bool Virtual, AccessSpecifier Access,
                         TypeTy *basetype, SourceLocation BaseLoc) {
  CXXRecordDecl *Decl = (CXXRecordDecl*)classdecl;
  QualType BaseType = Context.getTypeDeclType((TypeDecl*)basetype);

  // Base specifiers must be record types.
  if (!BaseType->isRecordType())
    return Diag(BaseLoc, diag::err_base_must_be_class) << SpecifierRange;

  // C++ [class.union]p1:
  //   A union shall not be used as a base class.
  if (BaseType->isUnionType())
    return Diag(BaseLoc, diag::err_union_as_base_class) << SpecifierRange;

  // C++ [class.union]p1:
  //   A union shall not have base classes.
  if (Decl->isUnion())
    return Diag(Decl->getLocation(), diag::err_base_clause_on_union)
              << SpecifierRange;

  // C++ [class.derived]p2:
  //   The class-name in a base-specifier shall not be an incompletely
  //   defined class.
  if (DiagnoseIncompleteType(BaseLoc, BaseType, diag::err_incomplete_base_class,
                             SpecifierRange))
    return true;

  // If the base class is polymorphic, the new one is, too.
  RecordDecl *BaseDecl = BaseType->getAsRecordType()->getDecl();
  assert(BaseDecl && "Record type has no declaration");
  BaseDecl = BaseDecl->getDefinition(Context);
  assert(BaseDecl && "Base type is not incomplete, but has no definition");
  if (cast<CXXRecordDecl>(BaseDecl)->isPolymorphic())
    Decl->setPolymorphic(true);

  // C++ [dcl.init.aggr]p1:
  //   An aggregate is [...] a class with [...] no base classes [...].
  Decl->setAggregate(false);
  Decl->setPOD(false);

  // Create the base specifier.
  return new CXXBaseSpecifier(SpecifierRange, Virtual, 
                              BaseType->isClassType(), Access, BaseType);
}

/// ActOnBaseSpecifiers - Attach the given base specifiers to the
/// class, after checking whether there are any duplicate base
/// classes.
void Sema::ActOnBaseSpecifiers(DeclTy *ClassDecl, BaseTy **Bases, 
                               unsigned NumBases) {
  if (NumBases == 0)
    return;

  // Used to keep track of which base types we have already seen, so
  // that we can properly diagnose redundant direct base types. Note
  // that the key is always the unqualified canonical type of the base
  // class.
  std::map<QualType, CXXBaseSpecifier*, QualTypeOrdering> KnownBaseTypes;

  // Copy non-redundant base specifiers into permanent storage.
  CXXBaseSpecifier **BaseSpecs = (CXXBaseSpecifier **)Bases;
  unsigned NumGoodBases = 0;
  for (unsigned idx = 0; idx < NumBases; ++idx) {
    QualType NewBaseType 
      = Context.getCanonicalType(BaseSpecs[idx]->getType());
    NewBaseType = NewBaseType.getUnqualifiedType();

    if (KnownBaseTypes[NewBaseType]) {
      // C++ [class.mi]p3:
      //   A class shall not be specified as a direct base class of a
      //   derived class more than once.
      Diag(BaseSpecs[idx]->getSourceRange().getBegin(),
           diag::err_duplicate_base_class)
        << KnownBaseTypes[NewBaseType]->getType()
        << BaseSpecs[idx]->getSourceRange();

      // Delete the duplicate base class specifier; we're going to
      // overwrite its pointer later.
      delete BaseSpecs[idx];
    } else {
      // Okay, add this new base class.
      KnownBaseTypes[NewBaseType] = BaseSpecs[idx];
      BaseSpecs[NumGoodBases++] = BaseSpecs[idx];
    }
  }

  // Attach the remaining base class specifiers to the derived class.
  CXXRecordDecl *Decl = (CXXRecordDecl*)ClassDecl;
  Decl->setBases(BaseSpecs, NumGoodBases);

  // Delete the remaining (good) base class specifiers, since their
  // data has been copied into the CXXRecordDecl.
  for (unsigned idx = 0; idx < NumGoodBases; ++idx)
    delete BaseSpecs[idx];
}

//===----------------------------------------------------------------------===//
// C++ class member Handling
//===----------------------------------------------------------------------===//

/// ActOnCXXMemberDeclarator - This is invoked when a C++ class member
/// declarator is parsed. 'AS' is the access specifier, 'BW' specifies the
/// bitfield width if there is one and 'InitExpr' specifies the initializer if
/// any. 'LastInGroup' is non-null for cases where one declspec has multiple
/// declarators on it.
Sema::DeclTy *
Sema::ActOnCXXMemberDeclarator(Scope *S, AccessSpecifier AS, Declarator &D,
                               ExprTy *BW, ExprTy *InitExpr,
                               DeclTy *LastInGroup) {
  const DeclSpec &DS = D.getDeclSpec();
  DeclarationName Name = GetNameForDeclarator(D);
  Expr *BitWidth = static_cast<Expr*>(BW);
  Expr *Init = static_cast<Expr*>(InitExpr);
  SourceLocation Loc = D.getIdentifierLoc();

  bool isFunc = D.isFunctionDeclarator();

  // C++ 9.2p6: A member shall not be declared to have automatic storage
  // duration (auto, register) or with the extern storage-class-specifier.
  // C++ 7.1.1p8: The mutable specifier can be applied only to names of class
  // data members and cannot be applied to names declared const or static,
  // and cannot be applied to reference members.
  switch (DS.getStorageClassSpec()) {
    case DeclSpec::SCS_unspecified:
    case DeclSpec::SCS_typedef:
    case DeclSpec::SCS_static:
      // FALL THROUGH.
      break;
    case DeclSpec::SCS_mutable:
      if (isFunc) {
        if (DS.getStorageClassSpecLoc().isValid())
          Diag(DS.getStorageClassSpecLoc(), diag::err_mutable_function);
        else
          Diag(DS.getThreadSpecLoc(), diag::err_mutable_function);
        
        // FIXME: It would be nicer if the keyword was ignored only for this
        // declarator. Otherwise we could get follow-up errors.
        D.getMutableDeclSpec().ClearStorageClassSpecs();
      } else {
        QualType T = GetTypeForDeclarator(D, S);
        diag::kind err = static_cast<diag::kind>(0);
        if (T->isReferenceType())
          err = diag::err_mutable_reference;
        else if (T.isConstQualified())
          err = diag::err_mutable_const;
        if (err != 0) {
          if (DS.getStorageClassSpecLoc().isValid())
            Diag(DS.getStorageClassSpecLoc(), err);
          else
            Diag(DS.getThreadSpecLoc(), err);
          // FIXME: It would be nicer if the keyword was ignored only for this
          // declarator. Otherwise we could get follow-up errors.
          D.getMutableDeclSpec().ClearStorageClassSpecs();
        }
      }
      break;
    default:
      if (DS.getStorageClassSpecLoc().isValid())
        Diag(DS.getStorageClassSpecLoc(),
             diag::err_storageclass_invalid_for_member);
      else
        Diag(DS.getThreadSpecLoc(), diag::err_storageclass_invalid_for_member);
      D.getMutableDeclSpec().ClearStorageClassSpecs();
  }

  if (!isFunc &&
      D.getDeclSpec().getTypeSpecType() == DeclSpec::TST_typedef &&
      D.getNumTypeObjects() == 0) {
    // Check also for this case:
    //
    // typedef int f();
    // f a;
    //
    Decl *TD = static_cast<Decl *>(DS.getTypeRep());
    isFunc = Context.getTypeDeclType(cast<TypeDecl>(TD))->isFunctionType();
  }

  bool isInstField = ((DS.getStorageClassSpec() == DeclSpec::SCS_unspecified ||
                       DS.getStorageClassSpec() == DeclSpec::SCS_mutable) &&
                      !isFunc);

  Decl *Member;
  bool InvalidDecl = false;

  if (isInstField)
    Member = static_cast<Decl*>(ActOnField(S, cast<CXXRecordDecl>(CurContext), 
                                           Loc, D, BitWidth));
  else
    Member = static_cast<Decl*>(ActOnDeclarator(S, D, LastInGroup));

  if (!Member) return LastInGroup;

  assert((Name || isInstField) && "No identifier for non-field ?");

  // set/getAccess is not part of Decl's interface to avoid bloating it with C++
  // specific methods. Use a wrapper class that can be used with all C++ class
  // member decls.
  CXXClassMemberWrapper(Member).setAccess(AS);

  // C++ [dcl.init.aggr]p1:
  //   An aggregate is an array or a class (clause 9) with [...] no
  //   private or protected non-static data members (clause 11).
  // A POD must be an aggregate.
  if (isInstField && (AS == AS_private || AS == AS_protected)) {
    CXXRecordDecl *Record = cast<CXXRecordDecl>(CurContext);
    Record->setAggregate(false);
    Record->setPOD(false);
  }

  if (DS.isVirtualSpecified()) {
    if (!isFunc || DS.getStorageClassSpec() == DeclSpec::SCS_static) {
      Diag(DS.getVirtualSpecLoc(), diag::err_virtual_non_function);
      InvalidDecl = true;
    } else {
      cast<CXXMethodDecl>(Member)->setVirtual();
      CXXRecordDecl *CurClass = cast<CXXRecordDecl>(CurContext);
      CurClass->setAggregate(false);
      CurClass->setPOD(false);
      CurClass->setPolymorphic(true);
    }
  }

  // FIXME: The above definition of virtual is not sufficient. A function is
  // also virtual if it overrides an already virtual function. This is important
  // to do here because it decides the validity of a pure specifier.

  if (BitWidth) {
    // C++ 9.6p2: Only when declaring an unnamed bit-field may the
    // constant-expression be a value equal to zero.
    // FIXME: Check this.

    if (D.isFunctionDeclarator()) {
      // FIXME: Emit diagnostic about only constructors taking base initializers
      // or something similar, when constructor support is in place.
      Diag(Loc, diag::err_not_bitfield_type)
        << Name << BitWidth->getSourceRange();
      InvalidDecl = true;

    } else if (isInstField) {
      // C++ 9.6p3: A bit-field shall have integral or enumeration type.
      if (!cast<FieldDecl>(Member)->getType()->isIntegralType()) {
        Diag(Loc, diag::err_not_integral_type_bitfield)
          << Name << BitWidth->getSourceRange();
        InvalidDecl = true;
      }

    } else if (isa<FunctionDecl>(Member)) {
      // A function typedef ("typedef int f(); f a;").
      // C++ 9.6p3: A bit-field shall have integral or enumeration type.
      Diag(Loc, diag::err_not_integral_type_bitfield)
        << Name << BitWidth->getSourceRange();
      InvalidDecl = true;

    } else if (isa<TypedefDecl>(Member)) {
      // "cannot declare 'A' to be a bit-field type"
      Diag(Loc, diag::err_not_bitfield_type)
        << Name << BitWidth->getSourceRange();
      InvalidDecl = true;

    } else {
      assert(isa<CXXClassVarDecl>(Member) &&
             "Didn't we cover all member kinds?");
      // C++ 9.6p3: A bit-field shall not be a static member.
      // "static member 'A' cannot be a bit-field"
      Diag(Loc, diag::err_static_not_bitfield)
        << Name << BitWidth->getSourceRange();
      InvalidDecl = true;
    }
  }

  if (Init) {
    // C++ 9.2p4: A member-declarator can contain a constant-initializer only
    // if it declares a static member of const integral or const enumeration
    // type.
    if (CXXClassVarDecl *CVD = dyn_cast<CXXClassVarDecl>(Member)) {
      // ...static member of...
      CVD->setInit(Init);
      // ...const integral or const enumeration type.
      if (Context.getCanonicalType(CVD->getType()).isConstQualified() &&
          CVD->getType()->isIntegralType()) {
        // constant-initializer
        if (CheckForConstantInitializer(Init, CVD->getType()))
          InvalidDecl = true;

      } else {
        // not const integral.
        Diag(Loc, diag::err_member_initialization)
          << Name << Init->getSourceRange();
        InvalidDecl = true;
      }

    } else {
      // not static member. perhaps virtual function?
      if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Member)) {
        // With declarators parsed the way they are, the parser cannot
        // distinguish between a normal initializer and a pure-specifier.
        // Thus this grotesque test.
        IntegerLiteral *IL;
        if ((IL = dyn_cast<IntegerLiteral>(Init)) && IL->getValue() == 0 &&
            Context.getCanonicalType(IL->getType()) == Context.IntTy) {
          if (MD->isVirtual())
            MD->setPure();
          else {
            Diag(Loc, diag::err_non_virtual_pure)
              << Name << Init->getSourceRange();
            InvalidDecl = true;
          }
        } else {
          Diag(Loc, diag::err_member_function_initialization)
            << Name << Init->getSourceRange();
          InvalidDecl = true;
        }
      } else {
        Diag(Loc, diag::err_member_initialization)
          << Name << Init->getSourceRange();
        InvalidDecl = true;
      }
    }
  }

  if (InvalidDecl)
    Member->setInvalidDecl();

  if (isInstField) {
    FieldCollector->Add(cast<FieldDecl>(Member));
    return LastInGroup;
  }
  return Member;
}

/// ActOnMemInitializer - Handle a C++ member initializer.
Sema::MemInitResult 
Sema::ActOnMemInitializer(DeclTy *ConstructorD,
                          Scope *S,
                          IdentifierInfo *MemberOrBase,
                          SourceLocation IdLoc,
                          SourceLocation LParenLoc,
                          ExprTy **Args, unsigned NumArgs,
                          SourceLocation *CommaLocs,
                          SourceLocation RParenLoc) {
  CXXConstructorDecl *Constructor 
    = dyn_cast<CXXConstructorDecl>((Decl*)ConstructorD);
  if (!Constructor) {
    // The user wrote a constructor initializer on a function that is
    // not a C++ constructor. Ignore the error for now, because we may
    // have more member initializers coming; we'll diagnose it just
    // once in ActOnMemInitializers.
    return true;
  }

  CXXRecordDecl *ClassDecl = Constructor->getParent();

  // C++ [class.base.init]p2:
  //   Names in a mem-initializer-id are looked up in the scope of the
  //   constructor’s class and, if not found in that scope, are looked
  //   up in the scope containing the constructor’s
  //   definition. [Note: if the constructor’s class contains a member
  //   with the same name as a direct or virtual base class of the
  //   class, a mem-initializer-id naming the member or base class and
  //   composed of a single identifier refers to the class member. A
  //   mem-initializer-id for the hidden base class may be specified
  //   using a qualified name. ]
  // Look for a member, first.
  FieldDecl *Member = 0;
  DeclContext::lookup_result Result = ClassDecl->lookup(MemberOrBase);
  if (Result.first != Result.second)
    Member = dyn_cast<FieldDecl>(*Result.first);

  // FIXME: Handle members of an anonymous union.

  if (Member) {
    // FIXME: Perform direct initialization of the member.
    return new CXXBaseOrMemberInitializer(Member, (Expr **)Args, NumArgs);
  }

  // It didn't name a member, so see if it names a class.
  TypeTy *BaseTy = getTypeName(*MemberOrBase, IdLoc, S, 0/*SS*/);
  if (!BaseTy)
    return Diag(IdLoc, diag::err_mem_init_not_member_or_class)
      << MemberOrBase << SourceRange(IdLoc, RParenLoc);
  
  QualType BaseType = Context.getTypeDeclType((TypeDecl *)BaseTy);
  if (!BaseType->isRecordType())
    return Diag(IdLoc, diag::err_base_init_does_not_name_class)
      << BaseType << SourceRange(IdLoc, RParenLoc);

  // C++ [class.base.init]p2:
  //   [...] Unless the mem-initializer-id names a nonstatic data
  //   member of the constructor’s class or a direct or virtual base
  //   of that class, the mem-initializer is ill-formed. A
  //   mem-initializer-list can initialize a base class using any
  //   name that denotes that base class type.
  
  // First, check for a direct base class.
  const CXXBaseSpecifier *DirectBaseSpec = 0;
  for (CXXRecordDecl::base_class_const_iterator Base = ClassDecl->bases_begin();
       Base != ClassDecl->bases_end(); ++Base) {
    if (Context.getCanonicalType(BaseType).getUnqualifiedType() == 
        Context.getCanonicalType(Base->getType()).getUnqualifiedType()) {
      // We found a direct base of this type. That's what we're
      // initializing.
      DirectBaseSpec = &*Base;
      break;
    }
  }
  
  // Check for a virtual base class.
  // FIXME: We might be able to short-circuit this if we know in
  // advance that there are no virtual bases.
  const CXXBaseSpecifier *VirtualBaseSpec = 0;
  if (!DirectBaseSpec || !DirectBaseSpec->isVirtual()) {
    // We haven't found a base yet; search the class hierarchy for a
    // virtual base class.
    BasePaths Paths(/*FindAmbiguities=*/true, /*RecordPaths=*/true,
                    /*DetectVirtual=*/false);
    if (IsDerivedFrom(Context.getTypeDeclType(ClassDecl), BaseType, Paths)) {
      for (BasePaths::paths_iterator Path = Paths.begin(); 
           Path != Paths.end(); ++Path) {
        if (Path->back().Base->isVirtual()) {
          VirtualBaseSpec = Path->back().Base;
          break;
        }
      }
    }
  }

  // C++ [base.class.init]p2:
  //   If a mem-initializer-id is ambiguous because it designates both
  //   a direct non-virtual base class and an inherited virtual base
  //   class, the mem-initializer is ill-formed.
  if (DirectBaseSpec && VirtualBaseSpec)
    return Diag(IdLoc, diag::err_base_init_direct_and_virtual)
      << MemberOrBase << SourceRange(IdLoc, RParenLoc);

  return new CXXBaseOrMemberInitializer(BaseType, (Expr **)Args, NumArgs);
}


void Sema::ActOnFinishCXXMemberSpecification(Scope* S, SourceLocation RLoc,
                                             DeclTy *TagDecl,
                                             SourceLocation LBrac,
                                             SourceLocation RBrac) {
  AdjustDeclIfTemplate(TagDecl);
  ActOnFields(S, RLoc, TagDecl,
              (DeclTy**)FieldCollector->getCurFields(),
              FieldCollector->getCurNumFields(), LBrac, RBrac, 0);
  AddImplicitlyDeclaredMembersToClass(cast<CXXRecordDecl>((Decl*)TagDecl));
}

/// AddImplicitlyDeclaredMembersToClass - Adds any implicitly-declared
/// special functions, such as the default constructor, copy
/// constructor, or destructor, to the given C++ class (C++
/// [special]p1).  This routine can only be executed just before the
/// definition of the class is complete.
void Sema::AddImplicitlyDeclaredMembersToClass(CXXRecordDecl *ClassDecl) {
  QualType ClassType = Context.getTypeDeclType(ClassDecl);
  ClassType = Context.getCanonicalType(ClassType);

  if (!ClassDecl->hasUserDeclaredConstructor()) {
    // C++ [class.ctor]p5:
    //   A default constructor for a class X is a constructor of class X
    //   that can be called without an argument. If there is no
    //   user-declared constructor for class X, a default constructor is
    //   implicitly declared. An implicitly-declared default constructor
    //   is an inline public member of its class.
    DeclarationName Name 
      = Context.DeclarationNames.getCXXConstructorName(ClassType);
    CXXConstructorDecl *DefaultCon = 
      CXXConstructorDecl::Create(Context, ClassDecl,
                                 ClassDecl->getLocation(), Name,
                                 Context.getFunctionType(Context.VoidTy,
                                                         0, 0, false, 0),
                                 /*isExplicit=*/false,
                                 /*isInline=*/true,
                                 /*isImplicitlyDeclared=*/true);
    DefaultCon->setAccess(AS_public);
    DefaultCon->setImplicit();
    ClassDecl->addDecl(DefaultCon);

    // Notify the class that we've added a constructor.
    ClassDecl->addedConstructor(Context, DefaultCon);
  }

  if (!ClassDecl->hasUserDeclaredCopyConstructor()) {
    // C++ [class.copy]p4:
    //   If the class definition does not explicitly declare a copy
    //   constructor, one is declared implicitly.

    // C++ [class.copy]p5:
    //   The implicitly-declared copy constructor for a class X will
    //   have the form
    //
    //       X::X(const X&)
    //
    //   if
    bool HasConstCopyConstructor = true;

    //     -- each direct or virtual base class B of X has a copy
    //        constructor whose first parameter is of type const B& or
    //        const volatile B&, and
    for (CXXRecordDecl::base_class_iterator Base = ClassDecl->bases_begin();
         HasConstCopyConstructor && Base != ClassDecl->bases_end(); ++Base) {
      const CXXRecordDecl *BaseClassDecl
        = cast<CXXRecordDecl>(Base->getType()->getAsRecordType()->getDecl());
      HasConstCopyConstructor 
        = BaseClassDecl->hasConstCopyConstructor(Context);
    }

    //     -- for all the nonstatic data members of X that are of a
    //        class type M (or array thereof), each such class type
    //        has a copy constructor whose first parameter is of type
    //        const M& or const volatile M&.
    for (CXXRecordDecl::field_iterator Field = ClassDecl->field_begin();
         HasConstCopyConstructor && Field != ClassDecl->field_end(); ++Field) {
      QualType FieldType = (*Field)->getType();
      if (const ArrayType *Array = Context.getAsArrayType(FieldType))
        FieldType = Array->getElementType();
      if (const RecordType *FieldClassType = FieldType->getAsRecordType()) {
        const CXXRecordDecl *FieldClassDecl 
          = cast<CXXRecordDecl>(FieldClassType->getDecl());
        HasConstCopyConstructor 
          = FieldClassDecl->hasConstCopyConstructor(Context);
      }
    }

    //   Otherwise, the implicitly declared copy constructor will have
    //   the form
    //
    //       X::X(X&)
    QualType ArgType = ClassType;
    if (HasConstCopyConstructor)
      ArgType = ArgType.withConst();
    ArgType = Context.getReferenceType(ArgType);

    //   An implicitly-declared copy constructor is an inline public
    //   member of its class.
    DeclarationName Name 
      = Context.DeclarationNames.getCXXConstructorName(ClassType);
    CXXConstructorDecl *CopyConstructor
      = CXXConstructorDecl::Create(Context, ClassDecl,
                                   ClassDecl->getLocation(), Name,
                                   Context.getFunctionType(Context.VoidTy,
                                                           &ArgType, 1,
                                                           false, 0),
                                   /*isExplicit=*/false,
                                   /*isInline=*/true,
                                   /*isImplicitlyDeclared=*/true);
    CopyConstructor->setAccess(AS_public);
    CopyConstructor->setImplicit();

    // Add the parameter to the constructor.
    ParmVarDecl *FromParam = ParmVarDecl::Create(Context, CopyConstructor,
                                                 ClassDecl->getLocation(),
                                                 /*IdentifierInfo=*/0,
                                                 ArgType, VarDecl::None, 0);
    CopyConstructor->setParams(Context, &FromParam, 1);

    ClassDecl->addedConstructor(Context, CopyConstructor);
    ClassDecl->addDecl(CopyConstructor);
  }

  if (!ClassDecl->hasUserDeclaredCopyAssignment()) {
    // Note: The following rules are largely analoguous to the copy
    // constructor rules. Note that virtual bases are not taken into account
    // for determining the argument type of the operator. Note also that
    // operators taking an object instead of a reference are allowed.
    //
    // C++ [class.copy]p10:
    //   If the class definition does not explicitly declare a copy
    //   assignment operator, one is declared implicitly.
    //   The implicitly-defined copy assignment operator for a class X
    //   will have the form
    //
    //       X& X::operator=(const X&)
    //
    //   if
    bool HasConstCopyAssignment = true;

    //       -- each direct base class B of X has a copy assignment operator
    //          whose parameter is of type const B&, const volatile B& or B,
    //          and
    for (CXXRecordDecl::base_class_iterator Base = ClassDecl->bases_begin();
         HasConstCopyAssignment && Base != ClassDecl->bases_end(); ++Base) {
      const CXXRecordDecl *BaseClassDecl
        = cast<CXXRecordDecl>(Base->getType()->getAsRecordType()->getDecl());
      HasConstCopyAssignment = BaseClassDecl->hasConstCopyAssignment(Context);
    }

    //       -- for all the nonstatic data members of X that are of a class
    //          type M (or array thereof), each such class type has a copy
    //          assignment operator whose parameter is of type const M&,
    //          const volatile M& or M.
    for (CXXRecordDecl::field_iterator Field = ClassDecl->field_begin();
         HasConstCopyAssignment && Field != ClassDecl->field_end(); ++Field) {
      QualType FieldType = (*Field)->getType();
      if (const ArrayType *Array = Context.getAsArrayType(FieldType))
        FieldType = Array->getElementType();
      if (const RecordType *FieldClassType = FieldType->getAsRecordType()) {
        const CXXRecordDecl *FieldClassDecl
          = cast<CXXRecordDecl>(FieldClassType->getDecl());
        HasConstCopyAssignment
          = FieldClassDecl->hasConstCopyAssignment(Context);
      }
    }

    //   Otherwise, the implicitly declared copy assignment operator will
    //   have the form
    //
    //       X& X::operator=(X&)
    QualType ArgType = ClassType;
    QualType RetType = Context.getReferenceType(ArgType);
    if (HasConstCopyAssignment)
      ArgType = ArgType.withConst();
    ArgType = Context.getReferenceType(ArgType);

    //   An implicitly-declared copy assignment operator is an inline public
    //   member of its class.
    DeclarationName Name =
      Context.DeclarationNames.getCXXOperatorName(OO_Equal);
    CXXMethodDecl *CopyAssignment =
      CXXMethodDecl::Create(Context, ClassDecl, ClassDecl->getLocation(), Name,
                            Context.getFunctionType(RetType, &ArgType, 1,
                                                    false, 0),
                            /*isStatic=*/false, /*isInline=*/true);
    CopyAssignment->setAccess(AS_public);
    CopyAssignment->setImplicit();

    // Add the parameter to the operator.
    ParmVarDecl *FromParam = ParmVarDecl::Create(Context, CopyAssignment,
                                                 ClassDecl->getLocation(),
                                                 /*IdentifierInfo=*/0,
                                                 ArgType, VarDecl::None, 0);
    CopyAssignment->setParams(Context, &FromParam, 1);

    // Don't call addedAssignmentOperator. There is no way to distinguish an
    // implicit from an explicit assignment operator.
    ClassDecl->addDecl(CopyAssignment);
  }

  if (!ClassDecl->hasUserDeclaredDestructor()) {
    // C++ [class.dtor]p2:
    //   If a class has no user-declared destructor, a destructor is
    //   declared implicitly. An implicitly-declared destructor is an
    //   inline public member of its class.
    DeclarationName Name 
      = Context.DeclarationNames.getCXXDestructorName(ClassType);
    CXXDestructorDecl *Destructor 
      = CXXDestructorDecl::Create(Context, ClassDecl,
                                  ClassDecl->getLocation(), Name,
                                  Context.getFunctionType(Context.VoidTy,
                                                          0, 0, false, 0),
                                  /*isInline=*/true,
                                  /*isImplicitlyDeclared=*/true);
    Destructor->setAccess(AS_public);
    Destructor->setImplicit();
    ClassDecl->addDecl(Destructor);
  }
}

/// ActOnStartDelayedCXXMethodDeclaration - We have completed
/// parsing a top-level (non-nested) C++ class, and we are now
/// parsing those parts of the given Method declaration that could
/// not be parsed earlier (C++ [class.mem]p2), such as default
/// arguments. This action should enter the scope of the given
/// Method declaration as if we had just parsed the qualified method
/// name. However, it should not bring the parameters into scope;
/// that will be performed by ActOnDelayedCXXMethodParameter.
void Sema::ActOnStartDelayedCXXMethodDeclaration(Scope *S, DeclTy *Method) {
  CXXScopeSpec SS;
  SS.setScopeRep(((FunctionDecl*)Method)->getDeclContext());
  ActOnCXXEnterDeclaratorScope(S, SS);
}

/// ActOnDelayedCXXMethodParameter - We've already started a delayed
/// C++ method declaration. We're (re-)introducing the given
/// function parameter into scope for use in parsing later parts of
/// the method declaration. For example, we could see an
/// ActOnParamDefaultArgument event for this parameter.
void Sema::ActOnDelayedCXXMethodParameter(Scope *S, DeclTy *ParamD) {
  ParmVarDecl *Param = (ParmVarDecl*)ParamD;

  // If this parameter has an unparsed default argument, clear it out
  // to make way for the parsed default argument.