[mono.git] / mcs / mcs / class.cs

//
// class.cs: Class and Struct handlers
//
// Authors: Miguel de Icaza (miguel@gnu.org)
//          Martin Baulig (martin@ximian.com)
//          Marek Safar (marek.safar@seznam.cz)
//
// Dual licensed under the terms of the MIT X11 or GNU GPL
//
// Copyright 2001, 2002, 2003 Ximian, Inc (http://www.ximian.com)
// Copyright 2004-2008 Novell, Inc
//

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Security;
using System.Security.Permissions;
using System.Text;
using System.Linq;

#if NET_2_1
using XmlElement = System.Object;
#else
using System.Xml;
#endif

using Mono.CompilerServices.SymbolWriter;

namespace Mono.CSharp {

        /// <summary>
        ///   This is the base class for structs and classes.  
        /// </summary>
        public abstract class TypeContainer : DeclSpace, ITypeDefinition
        {
                //
                // Different context is needed when resolving type container base
                // types. Type names come from the parent scope but type parameter
                // names from the container scope.
                //
                public struct BaseContext : IMemberContext
                {
                        TypeContainer tc;

                        public BaseContext (TypeContainer tc)
                        {
                                this.tc = tc;
                        }

                        #region IMemberContext Members

                        public CompilerContext Compiler {
                                get { return tc.Compiler; }
                        }

                        public TypeSpec CurrentType {
                                get { return tc.Parent.CurrentType; }
                        }

                        public TypeParameter[] CurrentTypeParameters {
                                get { return tc.PartialContainer.CurrentTypeParameters; }
                        }

                        public MemberCore CurrentMemberDefinition {
                                get { return tc; }
                        }

                        public bool HasUnresolvedConstraints {
                                get { return true; }
                        }

                        public bool IsObsolete {
                                get { return tc.IsObsolete; }
                        }

                        public bool IsUnsafe {
                                get { return tc.IsUnsafe; }
                        }

                        public bool IsStatic {
                                get { return tc.IsStatic; }
                        }

                        public string GetSignatureForError ()
                        {
                                return tc.GetSignatureForError ();
                        }

                        public ExtensionMethodGroupExpr LookupExtensionMethod (TypeSpec extensionType, string name, int arity, Location loc)
                        {
                                return null;
                        }

                        public FullNamedExpression LookupNamespaceAlias (string name)
                        {
                                return tc.Parent.LookupNamespaceAlias (name);
                        }

                        public FullNamedExpression LookupNamespaceOrType (string name, int arity, Location loc, bool ignore_cs0104)
                        {
                                if (arity == 0) {
                                        TypeParameter[] tp = CurrentTypeParameters;
                                        if (tp != null) {
                                                TypeParameter t = TypeParameter.FindTypeParameter (tp, name);
                                                if (t != null)
                                                        return new TypeParameterExpr (t, loc);
                                        }
                                }

                                return tc.Parent.LookupNamespaceOrType (name, arity, loc, ignore_cs0104);
                        }

                        #endregion
                }

                [Flags]
                enum CachedMethods
                {
                        Equals                          = 1,
                        GetHashCode                     = 1 << 1,
                        HasStaticFieldInitializer       = 1 << 2
                }


                // Whether this is a struct, class or interface
                public readonly MemberKind Kind;

                // Holds a list of classes and structures
                protected List<TypeContainer> types;

                List<MemberCore> ordered_explicit_member_list;
                List<MemberCore> ordered_member_list;

                // Holds the list of properties
                List<MemberCore> properties;

                // Holds the list of constructors
                protected List<Constructor> instance_constructors;

                // Holds the list of fields
                protected List<FieldBase> fields;

                // Holds a list of fields that have initializers
                protected List<FieldInitializer> initialized_fields;

                // Holds a list of static fields that have initializers
                protected List<FieldInitializer> initialized_static_fields;

                // Holds the list of constants
                protected List<MemberCore> constants;

                // Holds the methods.
                List<MemberCore> methods;

                // Holds the events
                protected List<MemberCore> events;

                // Holds the indexers
                List<MemberCore> indexers;

                // Holds the operators
                List<MemberCore> operators;

                // Holds the compiler generated classes
                List<CompilerGeneratedClass> compiler_generated;

                //
                // Pointers to the default constructor and the default static constructor
                //
                protected Constructor default_constructor;
                protected Constructor default_static_constructor;

                //
                // Points to the first non-static field added to the container.
                //
                // This is an arbitrary choice.  We are interested in looking at _some_ non-static field,
                // and the first one's as good as any.
                //
                FieldBase first_nonstatic_field = null;

                //
                // This one is computed after we can distinguish interfaces
                // from classes from the arraylist `type_bases' 
                //
                protected TypeSpec base_type;
                protected TypeExpr base_type_expr;
                protected TypeExpr[] iface_exprs;

                protected List<FullNamedExpression> type_bases;

                bool members_defined;
                bool members_defined_ok;
                bool type_defined;

                TypeContainer InTransit;

                GenericTypeParameterBuilder[] all_tp_builders;

                public const string DefaultIndexerName = "Item";

                private bool seen_normal_indexers = false;
                private string indexer_name = DefaultIndexerName;
                protected bool requires_delayed_unmanagedtype_check;
                bool error;

                private CachedMethods cached_method;

                protected TypeSpec spec;
                TypeSpec current_type;

                List<TypeContainer> partial_parts;

                /// <remarks>
                ///  The pending methods that need to be implemented
                //   (interfaces or abstract methods)
                /// </remarks>
                PendingImplementation pending;

                public TypeContainer (NamespaceEntry ns, DeclSpace parent, MemberName name,
                                      Attributes attrs, MemberKind kind)
                        : base (ns, parent, name, attrs)
                {
                        if (parent != null && parent.NamespaceEntry != ns)
                                throw new InternalErrorException ("A nested type should be in the same NamespaceEntry as its enclosing class");

                        this.Kind = kind;
                        this.PartialContainer = this;
                }

                #region Properties

                public override TypeSpec CurrentType {
                        get {
                                if (current_type == null) {
                                        if (IsGeneric) {
                                                //
                                                // Switch to inflated version as it's used by all expressions
                                                //
                                                var targs = CurrentTypeParameters == null ? TypeSpec.EmptyTypes : CurrentTypeParameters.Select (l => l.Type).ToArray ();
                                                current_type = spec.MakeGenericType (targs);
                                        } else {
                                                current_type = spec;
                                        }
                                }

                                return current_type;
                        }
                }

                public override TypeParameter[] CurrentTypeParameters {
                        get {
                                return PartialContainer.type_params;
                        }
                }

                int CurrentTypeParametersStartIndex {
                        get {
                                int total = all_tp_builders.Length;
                                if (CurrentTypeParameters != null) {
                                        return total - CurrentTypeParameters.Length;
                                }
                                return total;
                        }
                }

                public TypeSpec Definition {
                        get {
                                return spec;
                        }
                }

                public bool HasMembersDefined {
                        get {
                                return members_defined;
                        }
                }

                #endregion

                public bool AddMember (MemberCore symbol)
                {
                        return AddToContainer (symbol, symbol.MemberName.Basename);
                }

                protected virtual bool AddMemberType (TypeContainer ds)
                {
                        return AddToContainer (ds, ds.Basename);
                }

                protected virtual void RemoveMemberType (DeclSpace ds)
                {
                        RemoveFromContainer (ds.Basename);
                }

                public void AddConstant (Const constant)
                {
                        if (!AddMember (constant))
                                return;

                        if (constants == null)
                                constants = new List<MemberCore> ();
                        
                        constants.Add (constant);
                }

                public TypeContainer AddTypeContainer (TypeContainer tc)
                {
                        if (!AddMemberType (tc))
                                return tc;

                        if (types == null)
                                types = new List<TypeContainer> ();

                        types.Add (tc);
                        return tc;
                }

                public virtual TypeContainer AddPartial (TypeContainer next_part)
                {
                        return AddPartial (next_part, next_part.Basename);
                }

                protected TypeContainer AddPartial (TypeContainer next_part, string name)
                {
                        next_part.ModFlags |= Modifiers.PARTIAL;
                        TypeContainer tc = GetDefinition (name) as TypeContainer;
                        if (tc == null)
                                return AddTypeContainer (next_part);

                        if ((tc.ModFlags & Modifiers.PARTIAL) == 0) {
                                Report.SymbolRelatedToPreviousError (next_part);
                                Error_MissingPartialModifier (tc);
                        }

                        if (tc.Kind != next_part.Kind) {
                                Report.SymbolRelatedToPreviousError (tc);
                                Report.Error (261, next_part.Location,
                                        "Partial declarations of `{0}' must be all classes, all structs or all interfaces",
                                        next_part.GetSignatureForError ());
                        }

                        if ((tc.ModFlags & Modifiers.AccessibilityMask) != (next_part.ModFlags & Modifiers.AccessibilityMask) &&
                                ((tc.ModFlags & Modifiers.DEFAULT_ACCESS_MODIFER) == 0 &&
                                 (next_part.ModFlags & Modifiers.DEFAULT_ACCESS_MODIFER) == 0)) {
                                Report.SymbolRelatedToPreviousError (tc);
                                Report.Error (262, next_part.Location,
                                        "Partial declarations of `{0}' have conflicting accessibility modifiers",
                                        next_part.GetSignatureForError ());
                        }

                        if (tc.partial_parts == null)
                                tc.partial_parts = new List<TypeContainer> (1);

                        if ((next_part.ModFlags & Modifiers.DEFAULT_ACCESS_MODIFER) != 0) {
                                tc.ModFlags |= next_part.ModFlags & ~(Modifiers.DEFAULT_ACCESS_MODIFER | Modifiers.AccessibilityMask);
                        } else if ((tc.ModFlags & Modifiers.DEFAULT_ACCESS_MODIFER) != 0) {
                                tc.ModFlags &= ~(Modifiers.DEFAULT_ACCESS_MODIFER | Modifiers.AccessibilityMask);
                                tc.ModFlags |= next_part.ModFlags;
                        } else {
                                tc.ModFlags |= next_part.ModFlags;
                        }

                        tc.spec.Modifiers = tc.ModFlags;

                        if (next_part.attributes != null) {
                                if (tc.attributes == null)
                                        tc.attributes = next_part.attributes;
                                else
                                        tc.attributes.AddAttributes (next_part.attributes.Attrs);
                        }

                        next_part.PartialContainer = tc;
                        tc.partial_parts.Add (next_part);
                        return tc;
                }

                public virtual void RemoveTypeContainer (TypeContainer next_part)
                {
                        if (types != null)
                                types.Remove (next_part);
                        RemoveMemberType (next_part);
                }
                
                public void AddDelegate (Delegate d)
                {
                        AddTypeContainer (d);
                }

                private void AddMemberToList (MemberCore mc, List<MemberCore> alist, bool isexplicit)
                {
                        if (ordered_explicit_member_list == null)  {
                                ordered_explicit_member_list = new List<MemberCore> ();
                                ordered_member_list = new List<MemberCore> ();
                        }

                        if (isexplicit) {
                                if (Kind == MemberKind.Interface) {
                                        Report.Error (541, mc.Location,
                                                "`{0}': explicit interface declaration can only be declared in a class or struct",
                                                mc.GetSignatureForError ());
                                }

                                ordered_explicit_member_list.Add (mc);
                                alist.Insert (0, mc);
                        } else {
                                ordered_member_list.Add (mc);
                                alist.Add (mc);
                        }

                }
                
                public void AddMethod (MethodOrOperator method)
                {
                        if (!AddToContainer (method, method.MemberName.Basename))
                                return;
                        
                        if (methods == null)
                                methods = new List<MemberCore> ();

                        if (method.MemberName.Left != null) 
                                AddMemberToList (method, methods, true);
                        else 
                                AddMemberToList (method, methods, false);
                }

                public void AddConstructor (Constructor c)
                {
                        bool is_static = (c.ModFlags & Modifiers.STATIC) != 0;
                        if (!AddToContainer (c, is_static ?
                                ConstructorBuilder.ConstructorName : ConstructorBuilder.TypeConstructorName))
                                return;
                        
                        if (is_static && c.ParameterInfo.IsEmpty){
                                if (default_static_constructor != null) {
                                    Report.SymbolRelatedToPreviousError (default_static_constructor);
                                        Report.Error (111, c.Location,
                                                "A member `{0}' is already defined. Rename this member or use different parameter types",
                                                c.GetSignatureForError ());
                                    return;
                                }

                                default_static_constructor = c;
                        } else {
                                if (c.ParameterInfo.IsEmpty)
                                        default_constructor = c;
                                
                                if (instance_constructors == null)
                                        instance_constructors = new List<Constructor> ();
                                
                                instance_constructors.Add (c);
                        }
                }

                public bool AddField (FieldBase field)
                {
                        if (!AddMember (field))
                                return false;

                        if (fields == null)
                                fields = new List<FieldBase> ();

                        fields.Add (field);

                        if ((field.ModFlags & Modifiers.STATIC) != 0)
                                return true;

                        if (first_nonstatic_field == null) {
                                first_nonstatic_field = field;
                                return true;
                        }

                        if (Kind == MemberKind.Struct && first_nonstatic_field.Parent != field.Parent) {
                                Report.SymbolRelatedToPreviousError (first_nonstatic_field.Parent);
                                Report.Warning (282, 3, field.Location,
                                        "struct instance field `{0}' found in different declaration from instance field `{1}'",
                                        field.GetSignatureForError (), first_nonstatic_field.GetSignatureForError ());
                        }
                        return true;
                }

                public void AddProperty (Property prop)
                {
                        if (!AddMember (prop))
                                return;

                        if (properties == null)
                                properties = new List<MemberCore> ();

                        if (prop.MemberName.Left != null)
                                AddMemberToList (prop, properties, true);
                        else 
                                AddMemberToList (prop, properties, false);
                }

                public void AddEvent (Event e)
                {
                        if (!AddMember (e))
                                return;

                        if (events == null)
                                events = new List<MemberCore> ();

                        events.Add (e);
                }

                /// <summary>
                /// Indexer has special handling in constrast to other AddXXX because the name can be driven by IndexerNameAttribute
                /// </summary>
                public void AddIndexer (Indexer i)
                {
                        if (indexers == null)
                                indexers = new List<MemberCore> ();

                        if (i.IsExplicitImpl)
                                AddMemberToList (i, indexers, true);
                        else 
                                AddMemberToList (i, indexers, false);
                }

                public void AddOperator (Operator op)
                {
                        if (!AddMember (op))
                                return;

                        if (operators == null)
                                operators = new List<MemberCore> ();

                        operators.Add (op);
                }

                public void AddCompilerGeneratedClass (CompilerGeneratedClass c)
                {
                        Report.Debug (64, "ADD COMPILER GENERATED CLASS", this, c);

                        if (compiler_generated == null)
                                compiler_generated = new List<CompilerGeneratedClass> ();

                        compiler_generated.Add (c);
                }

                public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
                {
                        if (a.Type == pa.DefaultMember) {
                                if (Indexers != null) {
                                        Report.Error (646, a.Location, "Cannot specify the `DefaultMember' attribute on type containing an indexer");
                                        return;
                                }
                        }

                        if (a.Type == pa.Required) {
                                Report.Error (1608, a.Location, "The RequiredAttribute attribute is not permitted on C# types");
                                return;
                        }

                        TypeBuilder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), cdata);
                } 

                public override AttributeTargets AttributeTargets {
                        get {
                                throw new NotSupportedException ();
                        }
                }

                public IList<TypeContainer> Types {
                        get {
                                return types;
                        }
                }

                public IList<MemberCore> Methods {
                        get {
                                return methods;
                        }
                }

                public IList<MemberCore> Constants {
                        get {
                                return constants;
                        }
                }

                public TypeSpec BaseType {
                        get {
                                return spec.BaseType;
                        }
                }

                public IList<FieldBase> Fields {
                        get {
                                return fields;
                        }
                }

                public IList<Constructor> InstanceConstructors {
                        get {
                                return instance_constructors;
                        }
                }

                public IList<MemberCore> Properties {
                        get {
                                return properties;
                        }
                }

                public IList<MemberCore> Events {
                        get {
                                return events;
                        }
                }
                
                public IList<MemberCore> Indexers {
                        get {
                                return indexers;
                        }
                }

                public IList<MemberCore> Operators {
                        get {
                                return operators;
                        }
                }

                public IList<CompilerGeneratedClass> CompilerGeneratedClasses {
                        get {
                                return compiler_generated;
                        }
                }

                protected override TypeAttributes TypeAttr {
                        get {
                                return ModifiersExtensions.TypeAttr (ModFlags, IsTopLevel) | base.TypeAttr;
                        }
                }

                public int TypeParametersCount {
                        get {
                                return MemberName.Arity;
                        }
                }

                TypeParameterSpec[] ITypeDefinition.TypeParameters {
                        get {
                                // TODO MemberCache: this is going to hurt
                                return PartialContainer.type_params.Select (l => l.Type).ToArray ();
                        }
                }

                public string GetAttributeDefaultMember ()
                {
                        return indexers == null ? DefaultIndexerName : indexer_name;
                }

                public bool IsComImport {
                        get {
                                if (OptAttributes == null)
                                        return false;

                                return OptAttributes.Contains (PredefinedAttributes.Get.ComImport);
                        }
                }

                string ITypeDefinition.Namespace {
                        get {
                                return NamespaceEntry.NS.MemberName.GetSignatureForError ();
                        }
                }

                public virtual void RegisterFieldForInitialization (MemberCore field, FieldInitializer expression)
                {
                        if ((field.ModFlags & Modifiers.STATIC) != 0){
                                if (initialized_static_fields == null) {
                                        PartialContainer.HasStaticFieldInitializer = true;
                                        initialized_static_fields = new List<FieldInitializer> (4);
                                }

                                initialized_static_fields.Add (expression);
                        } else {
                                if (initialized_fields == null)
                                        initialized_fields = new List<FieldInitializer> (4);

                                initialized_fields.Add (expression);
                        }
                }

                public void ResolveFieldInitializers (BlockContext ec)
                {
                        if (partial_parts != null) {
                                foreach (TypeContainer part in partial_parts) {
                                        part.DoResolveFieldInitializers (ec);
                                }
                        }
                        DoResolveFieldInitializers (ec);
                }

                void DoResolveFieldInitializers (BlockContext ec)
                {
                        if (ec.IsStatic) {
                                if (initialized_static_fields == null)
                                        return;

                                bool has_complex_initializer = !RootContext.Optimize;
                                int i;
                                ExpressionStatement [] init = new ExpressionStatement [initialized_static_fields.Count];
                                for (i = 0; i < initialized_static_fields.Count; ++i) {
                                        FieldInitializer fi = initialized_static_fields [i];
                                        ExpressionStatement s = fi.ResolveStatement (ec);
                                        if (s == null) {
                                                s = EmptyExpressionStatement.Instance;
                                        } else if (fi.IsComplexInitializer) {
                                                has_complex_initializer |= true;
                                        }

                                        init [i] = s;
                                }

                                for (i = 0; i < initialized_static_fields.Count; ++i) {
                                        FieldInitializer fi = initialized_static_fields [i];
                                        //
                                        // Need special check to not optimize code like this
                                        // static int a = b = 5;
                                        // static int b = 0;
                                        //
                                        if (!has_complex_initializer && fi.IsDefaultInitializer)
                                                continue;

                                        ec.CurrentBlock.AddScopeStatement (new StatementExpression (init [i]));
                                }

                                return;
                        }

                        if (initialized_fields == null)
                                return;

                        for (int i = 0; i < initialized_fields.Count; ++i) {
                                FieldInitializer fi = initialized_fields [i];
                                ExpressionStatement s = fi.ResolveStatement (ec);
                                if (s == null)
                                        continue;

                                //
                                // Field is re-initialized to its default value => removed
                                //
                                if (fi.IsDefaultInitializer && RootContext.Optimize)
                                        continue;

                                ec.CurrentBlock.AddScopeStatement (new StatementExpression (s));
                        }
                }

                public override string DocComment {
                        get {
                                return comment;
                        }
                        set {
                                if (value == null)
                                        return;

                                comment += value;
                        }
                }

                public PendingImplementation PendingImplementations {
                        get { return pending; }
                }

                public TypeSpec GetAttributeCoClass ()
                {
                        if (OptAttributes == null)
                                return null;

                        Attribute a = OptAttributes.Search (PredefinedAttributes.Get.CoClass);
                        if (a == null)
                                return null;

                        return a.GetCoClassAttributeValue ();
                }

                public AttributeUsageAttribute GetAttributeUsage (PredefinedAttribute pa)
                {
                        Attribute a = null;
                        if (OptAttributes != null) {
                                a = OptAttributes.Search (pa);
                        }

                        if (a == null)
                                return null;

                        return a.GetAttributeUsageAttribute ();
                }

                public virtual void AddBasesForPart (DeclSpace part, List<FullNamedExpression> bases)
                {
                        // FIXME: get rid of partial_parts and store lists of bases of each part here
                        // assumed, not verified: 'part' is in 'partial_parts' 
                        ((TypeContainer) part).type_bases = bases;
                }

                /// <summary>
                ///   This function computes the Base class and also the
                ///   list of interfaces that the class or struct @c implements.
                ///   
                ///   The return value is an array (might be null) of
                ///   interfaces implemented (as Types).
                ///   
                ///   The @base_class argument is set to the base object or null
                ///   if this is `System.Object'. 
                /// </summary>
                protected virtual TypeExpr[] ResolveBaseTypes (out TypeExpr base_class)
                {
                        base_class = null;
                        if (type_bases == null)
                                return null;

                        int count = type_bases.Count;
                        TypeExpr [] ifaces = null;
                        var base_context = new BaseContext (this);
                        for (int i = 0, j = 0; i < count; i++){
                                FullNamedExpression fne = type_bases [i];

                                TypeExpr fne_resolved = fne.ResolveAsTypeTerminal (base_context, false);
                                if (fne_resolved == null)
                                        continue;

                                if (i == 0 && Kind == MemberKind.Class && !fne_resolved.Type.IsInterface) {
                                        if (fne_resolved.Type == InternalType.Dynamic)
                                                Report.Error (1965, Location, "Class `{0}' cannot derive from the dynamic type",
                                                        GetSignatureForError ());
                                        else
                                                base_type = fne_resolved.Type;

                                        base_class = fne_resolved;
                                        continue;
                                }

                                if (ifaces == null)
                                        ifaces = new TypeExpr [count - i];

                                if (fne_resolved.Type.IsInterface) {
                                        for (int ii = 0; ii < j; ++ii) {
                                                if (TypeManager.IsEqual (fne_resolved.Type, ifaces [ii].Type)) {
                                                        Report.Error (528, Location, "`{0}' is already listed in interface list",
                                                                fne_resolved.GetSignatureForError ());
                                                        break;
                                                }
                                        }

                                        if (Kind == MemberKind.Interface && !IsAccessibleAs (fne_resolved.Type)) {
                                                Report.Error (61, fne.Location,
                                                        "Inconsistent accessibility: base interface `{0}' is less accessible than interface `{1}'",
                                                        fne_resolved.GetSignatureForError (), GetSignatureForError ());
                                        }
                                } else {
                                        Report.SymbolRelatedToPreviousError (fne_resolved.Type);
                                        if (Kind != MemberKind.Class) {
                                                Report.Error (527, fne.Location, "Type `{0}' in interface list is not an interface", fne_resolved.GetSignatureForError ());
                                        } else if (base_class != null)
                                                Report.Error (1721, fne.Location, "`{0}': Classes cannot have multiple base classes (`{1}' and `{2}')",
                                                        GetSignatureForError (), base_class.GetSignatureForError (), fne_resolved.GetSignatureForError ());
                                        else {
                                                Report.Error (1722, fne.Location, "`{0}': Base class `{1}' must be specified as first",
                                                        GetSignatureForError (), fne_resolved.GetSignatureForError ());
                                        }
                                }

                                ifaces [j++] = fne_resolved;
                        }

                        return ifaces;
                }

                TypeExpr[] GetNormalPartialBases ()
                {
                        var ifaces = new List<TypeExpr> (0);
                        if (iface_exprs != null)
                                ifaces.AddRange (iface_exprs);

                        foreach (TypeContainer part in partial_parts) {
                                TypeExpr new_base_class;
                                TypeExpr[] new_ifaces = part.ResolveBaseTypes (out new_base_class);
                                if (new_base_class != null) {
                                        if (base_type_expr != null && new_base_class.Type != base_type) {
                                                Report.SymbolRelatedToPreviousError (new_base_class.Location, "");
                                                Report.Error (263, part.Location,
                                                        "Partial declarations of `{0}' must not specify different base classes",
                                                        part.GetSignatureForError ());
                                        } else {
                                                base_type_expr = new_base_class;
                                                base_type = base_type_expr.Type;
                                        }
                                }

                                if (new_ifaces == null)
                                        continue;

                                foreach (TypeExpr iface in new_ifaces) {
                                        if (ifaces.Contains (iface))
                                                continue;

                                        ifaces.Add (iface);
                                }
                        }

                        if (ifaces.Count == 0)
                                return null;

                        return ifaces.ToArray ();
                }

                //
                // Checks that some operators come in pairs:
                //  == and !=
                // > and <
                // >= and <=
                // true and false
                //
                // They are matched based on the return type and the argument types
                //
                void CheckPairedOperators ()
                {
                        bool has_equality_or_inequality = false;
                        var operators = this.operators.ToArray ();
                        bool[] has_pair = new bool[operators.Length];

                        for (int i = 0; i < operators.Length; ++i) {
                                if (operators[i] == null)
                                        continue;

                                Operator o_a = (Operator) operators[i];
                                Operator.OpType o_type = o_a.OperatorType;
                                if (o_type == Operator.OpType.Equality || o_type == Operator.OpType.Inequality)
                                        has_equality_or_inequality = true;

                                Operator.OpType matching_type = o_a.GetMatchingOperator ();
                                if (matching_type == Operator.OpType.TOP) {
                                        operators[i] = null;
                                        continue;
                                }

                                for (int ii = 0; ii < operators.Length; ++ii) {
                                        Operator o_b = (Operator) operators[ii];
                                        if (o_b == null || o_b.OperatorType != matching_type)
                                                continue;

                                        if (!TypeManager.IsEqual (o_a.ReturnType, o_b.ReturnType))
                                                continue;

                                        if (!TypeSpecComparer.Default.Equals (o_a.ParameterTypes, o_b.ParameterTypes))
                                                continue;

                                        operators[i] = null;

                                        //
                                        // Used to ignore duplicate user conversions
                                        //
                                        has_pair[ii] = true;
                                }
                        }

                        for (int i = 0; i < operators.Length; ++i) {
                                if (operators[i] == null || has_pair[i])
                                        continue;

                                Operator o = (Operator) operators [i];
                                Report.Error (216, o.Location,
                                        "The operator `{0}' requires a matching operator `{1}' to also be defined",
                                        o.GetSignatureForError (), Operator.GetName (o.GetMatchingOperator ()));
                        }

                        if (has_equality_or_inequality) {
                                if (Methods == null || !HasEquals)
                                        Report.Warning (660, 2, Location, "`{0}' defines operator == or operator != but does not override Object.Equals(object o)",
                                                GetSignatureForError ());

                                if (Methods == null || !HasGetHashCode)
                                        Report.Warning (661, 2, Location, "`{0}' defines operator == or operator != but does not override Object.GetHashCode()",
                                                GetSignatureForError ());
                        }
                }
        
                bool CreateTypeBuilder ()
                {
                        //
                        // Sets .size to 1 for structs with no instance fields
                        //
                        int type_size = Kind == MemberKind.Struct && first_nonstatic_field == null ? 1 : 0;

                        if (IsTopLevel) {
                                if (GlobalRootNamespace.Instance.IsNamespace (Name)) {
                                        Report.Error (519, Location, "`{0}' clashes with a predefined namespace", Name);
                                        return false;
                                }

                                ModuleBuilder builder = Module.Compiled.Builder;
                                TypeBuilder = builder.DefineType (Name, TypeAttr, null, type_size);
                        } else {
                                TypeBuilder builder = Parent.TypeBuilder;

                                TypeBuilder = builder.DefineNestedType (Basename, TypeAttr, null, type_size);
                        }

                        spec.SetMetaInfo (TypeBuilder);
                        spec.MemberCache = new MemberCache (this);
                        spec.DeclaringType = Parent.CurrentType;

                        if (!IsTopLevel)
                                Parent.MemberCache.AddMember (spec);

                        if (IsGeneric) {
                                string[] param_names = new string[TypeParameters.Length];
                                for (int i = 0; i < TypeParameters.Length; i++)
                                        param_names [i] = TypeParameters[i].Name;

                                all_tp_builders = TypeBuilder.DefineGenericParameters (param_names);

                                int offset = CurrentTypeParametersStartIndex;
                                for (int i = offset; i < all_tp_builders.Length; i++) {
                                        CurrentTypeParameters [i - offset].Define (all_tp_builders [i], spec);
                                }
                        }

                        return true;
                }

                bool DefineBaseTypes ()
                {
                        iface_exprs = ResolveBaseTypes (out base_type_expr);
                        if (partial_parts != null) {
                                iface_exprs = GetNormalPartialBases ();
                        }

                        var cycle = CheckRecursiveDefinition (this);
                        if (cycle != null) {
                                Report.SymbolRelatedToPreviousError (cycle);
                                if (this is Interface) {
                                        Report.Error (529, Location,
                                                "Inherited interface `{0}' causes a cycle in the interface hierarchy of `{1}'",
                                            GetSignatureForError (), cycle.GetSignatureForError ());
                                } else {
                                        Report.Error (146, Location,
                                                "Circular base class dependency involving `{0}' and `{1}'",
                                                GetSignatureForError (), cycle.GetSignatureForError ());
                                }

                                base_type = null;
                        }

                        if (iface_exprs != null) {
                                foreach (TypeExpr iface in iface_exprs) {
                                        // Prevents a crash, the interface might not have been resolved: 442144
                                        if (iface == null)
                                                continue;
                                        
                                        var iface_type = iface.Type;

                                        if (!spec.AddInterface (iface_type))
                                                continue;

                                        if (iface_type.IsGeneric && spec.Interfaces != null) {
                                                foreach (var prev_iface in iface_exprs) {
                                                        if (prev_iface == iface)
                                                                break;

                                                        if (!TypeSpecComparer.Unify.IsEqual (iface_type, prev_iface.Type))
                                                                continue;

                                                        Report.Error (695, Location,
                                                                "`{0}' cannot implement both `{1}' and `{2}' because they may unify for some type parameter substitutions",
                                                                GetSignatureForError (), prev_iface.GetSignatureForError (), iface_type.GetSignatureForError ());
                                                }
                                        }

                                        TypeBuilder.AddInterfaceImplementation (iface_type.GetMetaInfo ());

                                        // Ensure the base is always setup
                                        var compiled_iface = iface_type.MemberDefinition as Interface;
                                        if (compiled_iface != null) {
                                                // TODO: Need DefineBaseType only
                                                compiled_iface.DefineType ();
                                        }

                                        if (iface_type.Interfaces != null) {
                                                var base_ifaces = new List<TypeSpec> (iface_type.Interfaces);
                                                for (int i = 0; i < base_ifaces.Count; ++i) {
                                                        var ii_iface_type = base_ifaces[i];
                                                        if (spec.AddInterface (ii_iface_type)) {
                                                                TypeBuilder.AddInterfaceImplementation (ii_iface_type.GetMetaInfo ());

                                                                if (ii_iface_type.Interfaces != null)
                                                                        base_ifaces.AddRange (ii_iface_type.Interfaces);
                                                        }
                                                }
                                        }
                                }
                        }

                        if (Kind == MemberKind.Interface) {
                                spec.BaseType = TypeManager.object_type;
                                return true;
                        }

                        if (base_type != null) {
                                spec.BaseType = base_type;

                                // Set base type after type creation
                                TypeBuilder.SetParent (base_type.GetMetaInfo ());
                        }

                        return true;
                }

                public virtual void DefineConstants ()
                {
                        if (constants != null) {
                                foreach (Const c in constants) {
                                        c.DefineValue ();
                                }
                        }

                        if (instance_constructors != null) {
                                foreach (MethodCore m in instance_constructors) {
                                        var p = m.ParameterInfo;
                                        if (!p.IsEmpty && p[p.Count - 1].HasDefaultValue) {
                                                var rc = new ResolveContext (m);
                                                p.ResolveDefaultValues (rc);
                                        }
                                }
                        }

                        if (methods != null) {
                                foreach (MethodCore m in methods) {
                                        var p = m.ParameterInfo;
                                        if (!p.IsEmpty && p[p.Count - 1].HasDefaultValue) {
                                                var rc = new ResolveContext (m);
                                                p.ResolveDefaultValues (rc);
                                        }
                                }
                        }

                        if (indexers != null) {
                                foreach (Indexer i in indexers) {
                                        var p = i.ParameterInfo;
                                        if (p[p.Count - 1].HasDefaultValue) {
                                            var rc = new ResolveContext (i);
                                                p.ResolveDefaultValues (rc);
                                        }
                                }
                        }

                        if (types != null) {
                                foreach (var t in types)
                                        t.DefineConstants ();
                        }
                }

                //
                // Defines the type in the appropriate ModuleBuilder or TypeBuilder.
                //
                public TypeBuilder CreateType ()
                {
                        if (TypeBuilder != null)
                                return TypeBuilder;

                        if (error)
                                return null;

                        if (!CreateTypeBuilder ()) {
                                error = true;
                                return null;
                        }

                        if (partial_parts != null) {
                                foreach (TypeContainer part in partial_parts) {
                                        part.spec = spec;
                                        part.current_type = current_type;
                                        part.TypeBuilder = TypeBuilder;
                                }
                        }

                        if (Types != null) {
                                foreach (TypeContainer tc in Types) {
                                        if (tc.CreateType () == null) {
                                                error = true;
                                                return null;
                                        }
                                }
                        }

                        return TypeBuilder;
                }

                public override TypeBuilder DefineType ()
                {
                        if (error)
                                return null;
                        if (type_defined)
                                return TypeBuilder;

                        type_defined = true;

                        if (!DefineBaseTypes ()) {
                                error = true;
                                return null;
                        }

                        if (!DefineNestedTypes ()) {
                                error = true;
                                return null;
                        }

                        return TypeBuilder;
                }

                public override void SetParameterInfo (List<Constraints> constraints_list)
                {
                        base.SetParameterInfo (constraints_list);

                        if (PartialContainer.CurrentTypeParameters == null || PartialContainer == this)
                                return;

                        TypeParameter[] tc_names = PartialContainer.CurrentTypeParameters;
                        for (int i = 0; i < tc_names.Length; ++i) {
                                if (tc_names [i].Name != type_params [i].Name) {
                                        Report.SymbolRelatedToPreviousError (PartialContainer.Location, "");
                                        Report.Error (264, Location, "Partial declarations of `{0}' must have the same type parameter names in the same order",
                                                GetSignatureForError ());
                                        break;
                                }

                                if (tc_names [i].Variance != type_params [i].Variance) {
                                        Report.SymbolRelatedToPreviousError (PartialContainer.Location, "");
                                        Report.Error (1067, Location, "Partial declarations of `{0}' must have the same type parameter variance modifiers",
                                                GetSignatureForError ());
                                        break;
                                }
                        }
                }

                //
                // Replaces normal spec with predefined one when compiling corlib
                // and this type container defines predefined type
                //
                public void SetPredefinedSpec (PredefinedTypeSpec spec)
                {
                        this.spec = spec;
                }

                void UpdateTypeParameterConstraints (TypeContainer part)
                {
                        TypeParameter[] current_params = type_params;
                        for (int i = 0; i < current_params.Length; i++) {
                                if (current_params [i].AddPartialConstraints (part, part.type_params [i]))
                                        continue;

                                Report.SymbolRelatedToPreviousError (Location, "");
                                Report.Error (265, part.Location,
                                        "Partial declarations of `{0}' have inconsistent constraints for type parameter `{1}'",
                                        GetSignatureForError (), current_params [i].GetSignatureForError ());
                        }
                }

                public bool ResolveTypeParameters ()
                {
                        if (!DoResolveTypeParameters ())
                                return false;

                        if (types != null) {
                                foreach (var type in types)
                                        if (!type.ResolveTypeParameters ())
                                                return false;
                        }

                        if (compiler_generated != null) {
                                foreach (CompilerGeneratedClass c in compiler_generated)
                                        if (!c.ResolveTypeParameters ())
                                                return false;
                        }

                        return true;
                }

                protected virtual bool DoResolveTypeParameters ()
                {
                        if (CurrentTypeParameters == null)
                                return true;

                        if (PartialContainer != this)
                                throw new InternalErrorException ();

                        var base_context = new BaseContext (this);
                        foreach (TypeParameter type_param in CurrentTypeParameters) {
                                if (!type_param.ResolveConstraints (base_context)) {
                                        error = true;
                                        return false;
                                }
                        }

                        if (partial_parts != null) {
                                foreach (TypeContainer part in partial_parts)
                                        UpdateTypeParameterConstraints (part);
                        }

                        return true;
                }

                protected virtual bool DefineNestedTypes ()
                {
                        if (Types != null) {
                                foreach (TypeContainer tc in Types)
                                        if (tc.DefineType () == null)
                                                return false;
                        }

                        return true;
                }

                TypeSpec CheckRecursiveDefinition (TypeContainer tc)
                {
                        if (InTransit != null)
                                return spec;

                        InTransit = tc;

                        if (base_type_expr != null) {
                                var ptc = base_type.MemberDefinition as TypeContainer;
                                if (ptc != null && ptc.CheckRecursiveDefinition (this) != null)
                                        return base_type;
                        }

                        if (iface_exprs != null) {
                                foreach (TypeExpr iface in iface_exprs) {
                                        // the interface might not have been resolved, prevents a crash, see #442144
                                        if (iface == null)
                                                continue;
                                        var ptc = iface.Type.MemberDefinition as Interface;
                                        if (ptc != null && ptc.CheckRecursiveDefinition (this) != null)
                                                return iface.Type;
                                }
                        }

                        if (!IsTopLevel && Parent.PartialContainer.CheckRecursiveDefinition (this) != null)
                                return spec;

                        InTransit = null;
                        return null;
                }

                /// <summary>
                ///   Populates our TypeBuilder with fields and methods
                /// </summary>
                public sealed override bool Define ()
                {
                        if (members_defined)
                                return members_defined_ok;

                        members_defined_ok = DoDefineMembers ();
                        members_defined = true;

                        if (types != null) {
                                foreach (var nested in types)
                                        nested.Define ();
                        }

                        return members_defined_ok;
                }

                protected virtual bool DoDefineMembers ()
                {
                        if (iface_exprs != null) {
                                foreach (TypeExpr iface in iface_exprs) {
                                        var iface_type = iface.Type;

                                        // Ensure the base is always setup
                                        var compiled_iface = iface_type.MemberDefinition as Interface;
                                        if (compiled_iface != null)
                                                compiled_iface.Define ();

                                        if (Kind == MemberKind.Interface)
                                                MemberCache.AddInterface (iface_type);

                                        ObsoleteAttribute oa = iface_type.GetAttributeObsolete ();
                                        if (oa != null && !IsObsolete)
                                                AttributeTester.Report_ObsoleteMessage (oa, iface.GetSignatureForError (), Location, Report);

                                        GenericTypeExpr ct = iface as GenericTypeExpr;
                                        if (ct != null) {
                                                // TODO: passing `this' is wrong, should be base type iface instead
                                                TypeManager.CheckTypeVariance (ct.Type, Variance.Covariant, this);

                                                ct.CheckConstraints (this);

                                                if (ct.HasDynamicArguments ()) {
                                                        Report.Error (1966, iface.Location,
                                                                "`{0}': cannot implement a dynamic interface `{1}'",
                                                                GetSignatureForError (), iface.GetSignatureForError ());
                                                        return false;
                                                }
                                        }
                                }
                        }

                        if (base_type_expr != null) {
                                ObsoleteAttribute obsolete_attr = base_type.GetAttributeObsolete ();
                                if (obsolete_attr != null && !IsObsolete)
                                        AttributeTester.Report_ObsoleteMessage (obsolete_attr, base_type.GetSignatureForError (), Location, Report);

                                var ct = base_type_expr as GenericTypeExpr;
                                if (ct != null)
                                        ct.CheckConstraints (this);
                        }

                        if (base_type != null) {
                                var baseContainer = base_type.MemberDefinition as ClassOrStruct;
                                if (baseContainer != null) {
                                        baseContainer.Define ();

                                        //
                                        // It can trigger define of this type (for generic types only)
                                        //
                                        if (HasMembersDefined)
                                                return true;
                                }
                        }

                        if (type_params != null) {
                                foreach (var tp in type_params) {
                                        tp.CheckGenericConstraints ();
                                }
                        }

                        if (!IsTopLevel) {
                                MemberSpec candidate;
                                var conflict_symbol = MemberCache.FindBaseMember (this, out candidate);
                                if (conflict_symbol == null && candidate == null) {
                                        if ((ModFlags & Modifiers.NEW) != 0)
                                                Report.Warning (109, 4, Location, "The member `{0}' does not hide an inherited member. The new keyword is not required",
                                                        GetSignatureForError ());
                                } else {
                                        if ((ModFlags & Modifiers.NEW) == 0) {
                                                if (candidate == null)
                                                        candidate = conflict_symbol;

                                                Report.SymbolRelatedToPreviousError (candidate);
                                                Report.Warning (108, 2, Location, "`{0}' hides inherited member `{1}'. Use the new keyword if hiding was intended",
                                                        GetSignatureForError (), candidate.GetSignatureForError ());
                                        }
                                }
                        }

                        DefineContainerMembers (constants);
                        DefineContainerMembers (fields);

                        if (Kind == MemberKind.Struct || Kind == MemberKind.Class) {
                                pending = PendingImplementation.GetPendingImplementations (this);

                                if (requires_delayed_unmanagedtype_check) {
                                        requires_delayed_unmanagedtype_check = false;
                                        foreach (FieldBase f in fields) {
                                                if (f.MemberType != null && f.MemberType.IsPointer)
                                                        TypeManager.VerifyUnmanaged (Compiler, f.MemberType, f.Location);
                                        }
                                }
                        }
                
                        //
                        // Constructors are not in the defined_names array
                        //
                        DefineContainerMembers (instance_constructors);
                
                        DefineContainerMembers (events);
                        DefineContainerMembers (ordered_explicit_member_list);
                        DefineContainerMembers (ordered_member_list);

                        if (operators != null) {
                                DefineContainerMembers (operators);
                                CheckPairedOperators ();
                        }

                        ComputeIndexerName();
                        CheckEqualsAndGetHashCode();

                        return true;
                }

                protected virtual void DefineContainerMembers (System.Collections.IList mcal) // IList<MemberCore>
                {
                        if (mcal != null) {
                                foreach (MemberCore mc in mcal) {
                                        try {
                                                mc.Define ();
                                        } catch (Exception e) {
                                                throw new InternalErrorException (mc, e);
                                        }
                                }
                        }
                }
                
                protected virtual void ComputeIndexerName ()
                {
                        if (indexers == null)
                                return;

                        string class_indexer_name = null;

                        //
                        // If there's both an explicit and an implicit interface implementation, the
                        // explicit one actually implements the interface while the other one is just
                        // a normal indexer.  See bug #37714.
                        //

                        // Invariant maintained by AddIndexer(): All explicit interface indexers precede normal indexers
                        foreach (Indexer i in indexers) {
                                if (i.InterfaceType != null) {
                                        if (seen_normal_indexers)
                                                throw new Exception ("Internal Error: 'Indexers' array not sorted properly.");
                                        continue;
                                }

                                seen_normal_indexers = true;

                                if (class_indexer_name == null) {
                                        class_indexer_name = i.ShortName;
                                        continue;
                                }

                                if (i.ShortName != class_indexer_name)
                                        Report.Error (668, i.Location, "Two indexers have different names; the IndexerName attribute must be used with the same name on every indexer within a type");
                        }

                        if (class_indexer_name != null)
                                indexer_name = class_indexer_name;
                }

                void EmitIndexerName ()
                {
                        if (!seen_normal_indexers)
                                return;

                        PredefinedAttribute pa = PredefinedAttributes.Get.DefaultMember;
                        if (pa.Constructor == null &&
                                !pa.ResolveConstructor (Location, TypeManager.string_type))
                                return;

                        CustomAttributeBuilder cb = new CustomAttributeBuilder (pa.Constructor, new string [] { GetAttributeDefaultMember () });
                        TypeBuilder.SetCustomAttribute (cb);
                }

                protected virtual void CheckEqualsAndGetHashCode ()
                {
                        if (methods == null)
                                return;

                        if (HasEquals && !HasGetHashCode) {
                                Report.Warning (659, 3, this.Location, "`{0}' overrides Object.Equals(object) but does not override Object.GetHashCode()", this.GetSignatureForError ());
                        }
                }

                // Indicated whether container has StructLayout attribute set Explicit
                public bool HasExplicitLayout {
                        get { return (caching_flags & Flags.HasExplicitLayout) != 0; }
                        set { caching_flags |= Flags.HasExplicitLayout; }
                }

                public bool HasStructLayout {
                        get { return (caching_flags & Flags.HasStructLayout) != 0; }
                        set { caching_flags |= Flags.HasStructLayout; }
                }

                public MemberCache MemberCache {
                        get {
                                return spec.MemberCache;
                        }
                }

                void CheckMemberUsage (List<MemberCore> al, string member_type)
                {
                        if (al == null)
                                return;

                        foreach (MemberCore mc in al) {
                                if ((mc.ModFlags & Modifiers.AccessibilityMask) != Modifiers.PRIVATE)
                                        continue;

                                if (!mc.IsUsed && (mc.caching_flags & Flags.Excluded) == 0) {
                                        Report.Warning (169, 3, mc.Location, "The private {0} `{1}' is never used", member_type, mc.GetSignatureForError ());
                                }
                        }
                }

                public virtual void VerifyMembers ()
                {
                        //
                        // Check for internal or private fields that were never assigned
                        //
                        if (Report.WarningLevel >= 3) {
                                if (RootContext.EnhancedWarnings) {
                                        CheckMemberUsage (properties, "property");
                                        CheckMemberUsage (methods, "method");
                                        CheckMemberUsage (constants, "constant");
                                }

                                if (fields != null){
                                        bool is_type_exposed = Kind == MemberKind.Struct || IsExposedFromAssembly ();
                                        foreach (FieldBase f in fields) {
                                                if ((f.ModFlags & Modifiers.AccessibilityMask) != Modifiers.PRIVATE) {
                                                        if (is_type_exposed)
                                                                continue;

                                                        f.SetIsUsed ();
                                                }                               
                                                
                                                if (!f.IsUsed){
                                                        if ((f.caching_flags & Flags.IsAssigned) == 0)
                                                                Report.Warning (169, 3, f.Location, "The private field `{0}' is never used", f.GetSignatureForError ());
                                                        else {
                                                                Report.Warning (414, 3, f.Location, "The private field `{0}' is assigned but its value is never used",
                                                                        f.GetSignatureForError ());
                                                        }
                                                        continue;
                                                }
                                                
                                                //
                                                // Only report 649 on level 4
                                                //
                                                if (Report.WarningLevel < 4)
                                                        continue;
                                                
                                                if ((f.caching_flags & Flags.IsAssigned) != 0)
                                                        continue;

                                                //
                                                // Don't be pendatic over serializable attributes
                                                //
                                                if (f.OptAttributes != null || PartialContainer.HasStructLayout)
                                                        continue;
                                                
                                                Constant c = New.Constantify (f.MemberType);
                                                Report.Warning (649, 4, f.Location, "Field `{0}' is never assigned to, and will always have its default value `{1}'",
                                                        f.GetSignatureForError (), c == null ? "null" : c.AsString ());
                                        }
                                }
                        }
                }

                public override void Emit ()
                {
                        if (all_tp_builders != null) {
                                int current_starts_index = CurrentTypeParametersStartIndex;
                                for (int i = 0; i < all_tp_builders.Length; i++) {
                                        if (i < current_starts_index) {
                                                TypeParameters[i].EmitConstraints (all_tp_builders [i]);
                                        } else {
                                                CurrentTypeParameters [i - current_starts_index].Emit ();
                                        }
                                }
                        }

                        if ((ModFlags & Modifiers.COMPILER_GENERATED) != 0 && !Parent.IsCompilerGenerated)
                                PredefinedAttributes.Get.CompilerGenerated.EmitAttribute (TypeBuilder);

                        base.Emit ();
                }

                // TODO: move to ClassOrStruct
                void EmitConstructors ()
                {
                        if (instance_constructors == null)
                                return;

                        if (spec.IsAttribute && IsExposedFromAssembly () && RootContext.VerifyClsCompliance && IsClsComplianceRequired ()) {
                                bool has_compliant_args = false;

                                foreach (Constructor c in instance_constructors) {
                                        try {
                                                c.Emit ();
                                        }
                                        catch (Exception e) {
                                                throw new InternalErrorException (c, e);
                                        }

                                        if (has_compliant_args)
                                                continue;

                                        has_compliant_args = c.HasCompliantArgs;
                                }
                                if (!has_compliant_args)
                                        Report.Warning (3015, 1, Location, "`{0}' has no accessible constructors which use only CLS-compliant types", GetSignatureForError ());
                        } else {
                                foreach (Constructor c in instance_constructors) {
                                        try {
                                                c.Emit ();
                                        }
                                        catch (Exception e) {
                                                throw new InternalErrorException (c, e);
                                        }
                                }
                        }
                }

                /// <summary>
                ///   Emits the code, this step is performed after all
                ///   the types, enumerations, constructors
                /// </summary>
                public virtual void EmitType ()
                {
                        if (OptAttributes != null)
                                OptAttributes.Emit ();

                        Emit ();

                        EmitConstructors ();

                        if (constants != null)
                                foreach (Const con in constants)
                                        con.Emit ();

                        if (default_static_constructor != null)
                                default_static_constructor.Emit ();
                        
                        if (operators != null)
                                foreach (Operator o in operators)
                                        o.Emit ();

                        if (properties != null)
                                foreach (Property p in properties)
                                        p.Emit ();

                        if (indexers != null) {
                                foreach (Indexer indx in indexers)
                                        indx.Emit ();
                                EmitIndexerName ();
                        }

                        if (events != null){
                                foreach (Event e in Events)
                                        e.Emit ();
                        }

                        if (methods != null) {
                                for (int i = 0; i < methods.Count; ++i)
                                        ((MethodOrOperator) methods [i]).Emit ();
                        }
                        
                        if (fields != null)
                                foreach (FieldBase f in fields)
                                        f.Emit ();

                        if (types != null) {
                                foreach (TypeContainer t in types)
                                        t.EmitType ();
                        }

                        if (pending != null)
                                pending.VerifyPendingMethods (Report);

                        if (Report.Errors > 0)
                                return;

                        if (compiler_generated != null) {
                                for (int i = 0; i < compiler_generated.Count; ++i)
                                        compiler_generated [i].EmitType ();
                        }
                }

                public void CloseType ()
                {
                        if ((caching_flags & Flags.CloseTypeCreated) != 0)
                                return;

                        // Close base type container first to avoid TypeLoadException
                        if (spec.BaseType != null) {
                                var btype = spec.BaseType.MemberDefinition as TypeContainer;
                                if (btype != null)
                                        btype.CloseType ();
                        }

                        try {
                                caching_flags |= Flags.CloseTypeCreated;
                                TypeBuilder.CreateType ();
                        } catch (TypeLoadException){
                                //
                                // This is fine, the code still created the type
                                //
//                              Report.Warning (-20, "Exception while creating class: " + TypeBuilder.Name);
//                              Console.WriteLine (e.Message);
                        } catch (Exception e) {
                                throw new InternalErrorException (this, e);
                        }
                        
                        if (Types != null){
                                foreach (TypeContainer tc in Types)
                                        tc.CloseType ();
                        }

                        if (compiler_generated != null)
                                foreach (CompilerGeneratedClass c in compiler_generated)
                                        c.CloseType ();
                        
                        types = null;
                        fields = null;
                        initialized_fields = null;
                        initialized_static_fields = null;
                        constants = null;
                        ordered_explicit_member_list = null;
                        ordered_member_list = null;
                        methods = null;
                        events = null;
                        indexers = null;
                        operators = null;
                        compiler_generated = null;
                        default_constructor = null;
                        default_static_constructor = null;
                        type_bases = null;
                        OptAttributes = null;
                }

                //
                // Performs the validation on a Method's modifiers (properties have
                // the same properties).
                //
                public bool MethodModifiersValid (MemberCore mc)
                {
                        const Modifiers vao = (Modifiers.VIRTUAL | Modifiers.ABSTRACT | Modifiers.OVERRIDE);
                        const Modifiers va = (Modifiers.VIRTUAL | Modifiers.ABSTRACT);
                        const Modifiers nv = (Modifiers.NEW | Modifiers.VIRTUAL);
                        bool ok = true;
                        var flags = mc.ModFlags;
                        
                        //
                        // At most one of static, virtual or override
                        //
                        if ((flags & Modifiers.STATIC) != 0){
                                if ((flags & vao) != 0){
                                        Report.Error (112, mc.Location, "A static member `{0}' cannot be marked as override, virtual or abstract",
                                                mc.GetSignatureForError ());
                                        ok = false;
                                }
                        }

                        if (Kind == MemberKind.Struct){
                                if ((flags & va) != 0){
                                        ModifiersExtensions.Error_InvalidModifier (mc.Location, "virtual or abstract", Report);
                                        ok = false;
                                }
                        }

                        if ((flags & Modifiers.OVERRIDE) != 0 && (flags & nv) != 0){
                                Report.Error (113, mc.Location, "A member `{0}' marked as override cannot be marked as new or virtual",
                                        mc.GetSignatureForError ());
                                ok = false;
                        }

                        //
                        // If the declaration includes the abstract modifier, then the
                        // declaration does not include static, virtual or extern
                        //
                        if ((flags & Modifiers.ABSTRACT) != 0){
                                if ((flags & Modifiers.EXTERN) != 0){
                                        Report.Error (
                                                180, mc.Location, "`{0}' cannot be both extern and abstract", mc.GetSignatureForError ());
                                        ok = false;
                                }

                                if ((flags & Modifiers.SEALED) != 0) {
                                        Report.Error (502, mc.Location, "`{0}' cannot be both abstract and sealed", mc.GetSignatureForError ());
                                        ok = false;
                                }

                                if ((flags & Modifiers.VIRTUAL) != 0){
                                        Report.Error (503, mc.Location, "The abstract method `{0}' cannot be marked virtual", mc.GetSignatureForError ());
                                        ok = false;
                                }

                                if ((ModFlags & Modifiers.ABSTRACT) == 0){
                                        Report.SymbolRelatedToPreviousError (this);
                                        Report.Error (513, mc.Location, "`{0}' is abstract but it is declared in the non-abstract class `{1}'",
                                                mc.GetSignatureForError (), GetSignatureForError ());
                                        ok = false;
                                }
                        }

                        if ((flags & Modifiers.PRIVATE) != 0){
                                if ((flags & vao) != 0){
                                        Report.Error (621, mc.Location, "`{0}': virtual or abstract members cannot be private", mc.GetSignatureForError ());
                                        ok = false;
                                }
                        }

                        if ((flags & Modifiers.SEALED) != 0){
                                if ((flags & Modifiers.OVERRIDE) == 0){
                                        Report.Error (238, mc.Location, "`{0}' cannot be sealed because it is not an override", mc.GetSignatureForError ());
                                        ok = false;
                                }
                        }

                        return ok;
                }

                public Constructor DefaultStaticConstructor {
                        get { return default_static_constructor; }
                }

                protected override bool VerifyClsCompliance ()
                {
                        if (!base.VerifyClsCompliance ())
                                return false;

                        // Check this name against other containers
                        NamespaceEntry.NS.VerifyClsCompliance ();

                        // Check all container names for user classes
                        if (Kind != MemberKind.Delegate)
                                MemberCache.VerifyClsCompliance (Definition, Report);

                        if (BaseType != null && !BaseType.IsCLSCompliant ()) {
                                Report.Warning (3009, 1, Location, "`{0}': base type `{1}' is not CLS-compliant",
                                        GetSignatureForError (), BaseType.GetSignatureForError ());
                        }
                        return true;
                }

                /// <summary>
                ///   Performs checks for an explicit interface implementation.  First it
                ///   checks whether the `interface_type' is a base inteface implementation.
                ///   Then it checks whether `name' exists in the interface type.
                /// </summary>
                public bool VerifyImplements (InterfaceMemberBase mb)
                {
                        var ifaces = spec.Interfaces;
                        if (ifaces != null) {
                                foreach (TypeSpec t in ifaces){
                                        if (TypeManager.IsEqual (t, mb.InterfaceType))
                                                return true;
                                }
                        }
                        
                        Report.SymbolRelatedToPreviousError (mb.InterfaceType);
                        Report.Error (540, mb.Location, "`{0}': containing type does not implement interface `{1}'",
                                mb.GetSignatureForError (), TypeManager.CSharpName (mb.InterfaceType));
                        return false;
                }

                //
                // Used for visiblity checks to tests whether this definition shares
                // base type baseType, it does member-definition search
                //
                public bool IsBaseTypeDefinition (TypeSpec baseType)
                {
                        // RootContext check
                        if (TypeBuilder == null)
                                return false;

                        var type = spec;
                        do {
                                if (type.MemberDefinition == baseType.MemberDefinition)
                                        return true;

                                type = type.BaseType;
                        } while (type != null);

                        return false;
                }

                public MemberCache LoadMembers (TypeSpec declaringType)
                {
                        throw new NotSupportedException ("Not supported for compiled definition " + GetSignatureForError ());
                }

                public void Mark_HasEquals ()
                {
                        cached_method |= CachedMethods.Equals;
                }

                public void Mark_HasGetHashCode ()
                {
                        cached_method |= CachedMethods.GetHashCode;
                }

                /// <summary>
                /// Method container contains Equals method
                /// </summary>
                public bool HasEquals {
                        get {
                                return (cached_method & CachedMethods.Equals) != 0;
                        }
                }
 
                /// <summary>
                /// Method container contains GetHashCode method
                /// </summary>
                public bool HasGetHashCode {
                        get {
                                return (cached_method & CachedMethods.GetHashCode) != 0;
                        }
                }

                public bool HasStaticFieldInitializer {
                        get {
                                return (cached_method & CachedMethods.HasStaticFieldInitializer) != 0;
                        }
                        set {
                                if (value)
                                        cached_method |= CachedMethods.HasStaticFieldInitializer;
                                else
                                        cached_method &= ~CachedMethods.HasStaticFieldInitializer;
                        }
                }

                //
                // Generates xml doc comments (if any), and if required,
                // handle warning report.
                //
                internal override void GenerateDocComment (DeclSpace ds)
                {
                        DocUtil.GenerateTypeDocComment (this, ds, Report);
                }

                public override string DocCommentHeader {
                        get { return "T:"; }
                }
        }

        public abstract class ClassOrStruct : TypeContainer
        {
                Dictionary<SecurityAction, PermissionSet> declarative_security;

                public ClassOrStruct (NamespaceEntry ns, DeclSpace parent,
                                      MemberName name, Attributes attrs, MemberKind kind)
                        : base (ns, parent, name, attrs, kind)
                {
                }

                protected override bool AddToContainer (MemberCore symbol, string name)
                {
                        if (name == MemberName.Name) {
                                if (symbol is TypeParameter) {
                                        Report.Error (694, symbol.Location,
                                                "Type parameter `{0}' has same name as containing type, or method",
                                                symbol.GetSignatureForError ());
                                        return false;
                                }

                                InterfaceMemberBase imb = symbol as InterfaceMemberBase;
                                if (imb == null || !imb.IsExplicitImpl) {
                                        Report.SymbolRelatedToPreviousError (this);
                                        Report.Error (542, symbol.Location, "`{0}': member names cannot be the same as their enclosing type",
                                                symbol.GetSignatureForError ());
                                        return false;
                                }
                        }

                        return base.AddToContainer (symbol, name);
                }

                public override void VerifyMembers ()
                {
                        base.VerifyMembers ();

                        if ((events != null) && Report.WarningLevel >= 3) {
                                foreach (Event e in events){
                                        // Note: The event can be assigned from same class only, so we can report
                                        // this warning for all accessibility modes
                                        if ((e.caching_flags & Flags.IsUsed) == 0)
                                                Report.Warning (67, 3, e.Location, "The event `{0}' is never used", e.GetSignatureForError ());
                                }
                        }
                }

                public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
                {
                        if (a.IsValidSecurityAttribute ()) {
                                if (declarative_security == null)
                                        declarative_security = new Dictionary<SecurityAction, PermissionSet> ();

                                a.ExtractSecurityPermissionSet (declarative_security);
                                return;
                        }

                        if (a.Type == pa.StructLayout) {
                                PartialContainer.HasStructLayout = true;

                                if (a.GetLayoutKindValue () == LayoutKind.Explicit)
                                        PartialContainer.HasExplicitLayout = true;
                        }

                        if (a.Type == pa.Dynamic) {
                                a.Error_MisusedDynamicAttribute ();
                                return;
                        }

                        base.ApplyAttributeBuilder (a, ctor, cdata, pa);
                }

                /// <summary>
                /// Defines the default constructors 
                /// </summary>
                protected void DefineDefaultConstructor (bool is_static)
                {
                        // The default instance constructor is public
                        // If the class is abstract, the default constructor is protected
                        // The default static constructor is private

                        Modifiers mods;
                        if (is_static) {
                                mods = Modifiers.STATIC | Modifiers.PRIVATE;
                        } else {
                                mods = ((ModFlags & Modifiers.ABSTRACT) != 0) ? Modifiers.PROTECTED : Modifiers.PUBLIC;
                        }

                        Constructor c = new Constructor (this, MemberName.Name, mods,
                                null, ParametersCompiled.EmptyReadOnlyParameters,
                                new GeneratedBaseInitializer (Location),
                                Location);
                        
                        AddConstructor (c);
                        c.Block = new ToplevelBlock (Compiler, ParametersCompiled.EmptyReadOnlyParameters, Location);
                }

                protected override bool DoDefineMembers ()
                {
                        CheckProtectedModifier ();

                        base.DoDefineMembers ();

                        if (default_static_constructor != null)
                                default_static_constructor.Define ();

                        return true;
                }

                public override void Emit ()
                {
                        if (default_static_constructor == null && PartialContainer.HasStaticFieldInitializer) {
                                DefineDefaultConstructor (true);
                                default_static_constructor.Define ();
                        }

                        base.Emit ();

                        if (declarative_security != null) {
                                foreach (var de in declarative_security) {
                                        TypeBuilder.AddDeclarativeSecurity (de.Key, de.Value);
                                }
                        }
                }

                public override ExtensionMethodGroupExpr LookupExtensionMethod (TypeSpec extensionType, string name, int arity, Location loc)
                {
                        DeclSpace top_level = Parent;
                        if (top_level != null) {
                                while (top_level.Parent != null)
                                        top_level = top_level.Parent;

                                var candidates = NamespaceEntry.NS.LookupExtensionMethod (extensionType, this, name, arity);
                                if (candidates != null)
                                        return new ExtensionMethodGroupExpr (candidates, NamespaceEntry, extensionType, loc);
                        }

                        return NamespaceEntry.LookupExtensionMethod (extensionType, name, arity, loc);
                }

                protected override TypeAttributes TypeAttr {
                        get {
                                if (default_static_constructor == null)
                                        return base.TypeAttr | TypeAttributes.BeforeFieldInit;

                                return base.TypeAttr;
                        }
                }
        }


        // TODO: should be sealed
        public class Class : ClassOrStruct {
                const Modifiers AllowedModifiers =
                        Modifiers.NEW |
                        Modifiers.PUBLIC |
                        Modifiers.PROTECTED |
                        Modifiers.INTERNAL |
                        Modifiers.PRIVATE |
                        Modifiers.ABSTRACT |
                        Modifiers.SEALED |
                        Modifiers.STATIC |
                        Modifiers.UNSAFE;

                public const TypeAttributes StaticClassAttribute = TypeAttributes.Abstract | TypeAttributes.Sealed;

                public Class (NamespaceEntry ns, DeclSpace parent, MemberName name, Modifiers mod,
                              Attributes attrs)
                        : base (ns, parent, name, attrs, MemberKind.Class)
                {
                        var accmods = (Parent == null || Parent.Parent == null) ? Modifiers.INTERNAL : Modifiers.PRIVATE;
                        this.ModFlags = ModifiersExtensions.Check (AllowedModifiers, mod, accmods, Location, Report);
                        spec = new TypeSpec (Kind, null, this, null, ModFlags);

                        if (IsStatic && RootContext.Version == LanguageVersion.ISO_1) {
                                Report.FeatureIsNotAvailable (Location, "static classes");
                        }
                }

                public override void AddBasesForPart (DeclSpace part, List<FullNamedExpression> bases)
                {
                        if (part.Name == "System.Object")
                                Report.Error (537, part.Location,
                                        "The class System.Object cannot have a base class or implement an interface.");
                        base.AddBasesForPart (part, bases);
                }

                public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
                {
                        if (a.Type == pa.AttributeUsage) {
                                if (!BaseType.IsAttribute && spec != TypeManager.attribute_type) {
                                        Report.Error (641, a.Location, "Attribute `{0}' is only valid on classes derived from System.Attribute", a.GetSignatureForError ());
                                }
                        }

                        if (a.Type == pa.Conditional && !BaseType.IsAttribute) {
                                Report.Error (1689, a.Location, "Attribute `System.Diagnostics.ConditionalAttribute' is only valid on methods or attribute classes");
                                return;
                        }

                        if (a.Type == pa.ComImport && !attributes.Contains (pa.Guid)) {
                                a.Error_MissingGuidAttribute ();
                                return;
                        }

                        if (a.Type == pa.Extension) {
                                a.Error_MisusedExtensionAttribute ();
                                return;
                        }

                        if (a.Type.IsConditionallyExcluded (Location))
                                return;

                        base.ApplyAttributeBuilder (a, ctor, cdata, pa);
                }

                public override AttributeTargets AttributeTargets {
                        get {
                                return AttributeTargets.Class;
                        }
                }

                protected override void DefineContainerMembers (System.Collections.IList list)
                {
                        if (list == null)
                                return;

                        if (!IsStatic) {
                                base.DefineContainerMembers (list);
                                return;
                        }

                        foreach (MemberCore m in list) {
                                if (m is Operator) {
                                        Report.Error (715, m.Location, "`{0}': Static classes cannot contain user-defined operators", m.GetSignatureForError ());
                                        continue;
                                }

                                if (m is Destructor) {
                                        Report.Error (711, m.Location, "`{0}': Static classes cannot contain destructor", GetSignatureForError ());
                                        continue;
                                }

                                if (m is Indexer) {
                                        Report.Error (720, m.Location, "`{0}': cannot declare indexers in a static class", m.GetSignatureForError ());
                                        continue;
                                }

                                if ((m.ModFlags & Modifiers.STATIC) != 0 || m is Enum || m is Delegate)
                                        continue;

                                if (m is Constructor) {
                                        Report.Error (710, m.Location, "`{0}': Static classes cannot have instance constructors", GetSignatureForError ());
                                        continue;
                                }

                                Method method = m as Method;
                                if (method != null && method.ParameterInfo.HasExtensionMethodType) {
                                        Report.Error (1105, m.Location, "`{0}': Extension methods must be declared static", m.GetSignatureForError ());
                                        continue;
                                }

                                Report.Error (708, m.Location, "`{0}': cannot declare instance members in a static class", m.GetSignatureForError ());
                        }

                        base.DefineContainerMembers (list);
                }

                protected override bool DoDefineMembers ()
                {
                        if ((ModFlags & Modifiers.ABSTRACT) == Modifiers.ABSTRACT && (ModFlags & (Modifiers.SEALED | Modifiers.STATIC)) != 0) {
                                Report.Error (418, Location, "`{0}': an abstract class cannot be sealed or static", GetSignatureForError ());
                        }

                        if ((ModFlags & (Modifiers.SEALED | Modifiers.STATIC)) == (Modifiers.SEALED | Modifiers.STATIC)) {
                                Report.Error (441, Location, "`{0}': a class cannot be both static and sealed", GetSignatureForError ());
                        }

                        if (InstanceConstructors == null && !IsStatic)
                                DefineDefaultConstructor (false);

                        return base.DoDefineMembers ();
                }

                public override void Emit ()
                {
                        base.Emit ();

                        if ((ModFlags & Modifiers.METHOD_EXTENSION) != 0)
                                PredefinedAttributes.Get.Extension.EmitAttribute (TypeBuilder);

                        var trans_flags = TypeManager.HasDynamicTypeUsed (base_type);
                        if (trans_flags != null) {
                                var pa = PredefinedAttributes.Get.DynamicTransform;
                                if (pa.Constructor != null || pa.ResolveConstructor (Location, ArrayContainer.MakeType (TypeManager.bool_type))) {
                                        TypeBuilder.SetCustomAttribute (new CustomAttributeBuilder (pa.Constructor, new object[] { trans_flags }));
                                }
                        }
                }

                protected override TypeExpr[] ResolveBaseTypes (out TypeExpr base_class)
                {
                        TypeExpr[] ifaces = base.ResolveBaseTypes (out base_class);

                        if (base_class == null) {
                                if (spec != TypeManager.object_type)
                                        base_type = TypeManager.object_type;
                        } else {
                                if (base_type.IsGenericParameter){
                                        Report.Error (689, base_class.Location, "`{0}': Cannot derive from type parameter `{1}'",
                                                GetSignatureForError (), base_type.GetSignatureForError ());
                                } else if (IsGeneric && base_type.IsAttribute) {
                                        Report.Error (698, base_class.Location,
                                                "A generic type cannot derive from `{0}' because it is an attribute class",
                                                base_class.GetSignatureForError ());
                                } else if (base_type.IsStatic) {
                                        Report.SymbolRelatedToPreviousError (base_class.Type);
                                        Report.Error (709, Location, "`{0}': Cannot derive from static class `{1}'",
                                                GetSignatureForError (), base_type.GetSignatureForError ());
                                } else if (base_type.IsSealed) {
                                        Report.SymbolRelatedToPreviousError (base_class.Type);
                                        Report.Error (509, Location, "`{0}': cannot derive from sealed type `{1}'",
                                                GetSignatureForError (), base_type.GetSignatureForError ());
                                } else if (PartialContainer.IsStatic && base_class.Type != TypeManager.object_type) {
                                        Report.Error (713, Location, "Static class `{0}' cannot derive from type `{1}'. Static classes must derive from object",
                                                GetSignatureForError (), base_class.GetSignatureForError ());
                                }

                                if (base_type is PredefinedTypeSpec && !(spec is PredefinedTypeSpec) &&
                                        (base_type == TypeManager.enum_type || base_type == TypeManager.value_type || base_type == TypeManager.multicast_delegate_type ||
                                        base_type == TypeManager.delegate_type || base_type == TypeManager.array_type)) {
                                        Report.Error (644, Location, "`{0}' cannot derive from special class `{1}'",
                                                GetSignatureForError (), base_type.GetSignatureForError ());

                                        base_type = TypeManager.object_type;
                                }

                                if (!IsAccessibleAs (base_type)) {
                                        Report.SymbolRelatedToPreviousError (base_type);
                                        Report.Error (60, Location, "Inconsistent accessibility: base class `{0}' is less accessible than class `{1}'",
                                                base_type.GetSignatureForError (), GetSignatureForError ());
                                }
                        }

                        if (PartialContainer.IsStatic && ifaces != null) {
                                foreach (TypeExpr t in ifaces)
                                        Report.SymbolRelatedToPreviousError (t.Type);
                                Report.Error (714, Location, "Static class `{0}' cannot implement interfaces", GetSignatureForError ());
                        }

                        return ifaces;
                }

                /// Search for at least one defined condition in ConditionalAttribute of attribute class
                /// Valid only for attribute classes.
                public override string[] ConditionalConditions ()
                {
                        if ((caching_flags & (Flags.Excluded_Undetected | Flags.Excluded)) == 0)
                                return null;

                        caching_flags &= ~Flags.Excluded_Undetected;

                        if (OptAttributes == null)
                                return null;

                        Attribute[] attrs = OptAttributes.SearchMulti (PredefinedAttributes.Get.Conditional);
                        if (attrs == null)
                                return null;

                        string[] conditions = new string[attrs.Length];
                        for (int i = 0; i < conditions.Length; ++i)
                                conditions[i] = attrs[i].GetConditionalAttributeValue ();

                        caching_flags |= Flags.Excluded;
                        return conditions;
                }

                //
                // FIXME: How do we deal with the user specifying a different
                // layout?
                //
                protected override TypeAttributes TypeAttr {
                        get {
                                TypeAttributes ta = base.TypeAttr | TypeAttributes.AutoLayout | TypeAttributes.Class;
                                if (IsStatic)
                                        ta |= StaticClassAttribute;
                                return ta;
                        }
                }
        }

        public sealed class Struct : ClassOrStruct {

                bool is_unmanaged, has_unmanaged_check_done;
                bool InTransit;

                // <summary>
                //   Modifiers allowed in a struct declaration
                // </summary>
                const Modifiers AllowedModifiers =
                        Modifiers.NEW       |
                        Modifiers.PUBLIC    |
                        Modifiers.PROTECTED |
                        Modifiers.INTERNAL  |
                        Modifiers.UNSAFE    |
                        Modifiers.PRIVATE;

                public Struct (NamespaceEntry ns, DeclSpace parent, MemberName name,
                               Modifiers mod, Attributes attrs)
                        : base (ns, parent, name, attrs, MemberKind.Struct)
                {
                        var accmods = parent.Parent == null ? Modifiers.INTERNAL : Modifiers.PRIVATE;                   
                        this.ModFlags = ModifiersExtensions.Check (AllowedModifiers, mod, accmods, Location, Report) | Modifiers.SEALED ;
                        spec = new TypeSpec (Kind, null, this, null, ModFlags);
                }

                public override AttributeTargets AttributeTargets {
                        get {
                                return AttributeTargets.Struct;
                        }
                }

                public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
                {
                        base.ApplyAttributeBuilder (a, ctor, cdata, pa);

                        //
                        // When struct constains fixed fixed and struct layout has explicitly
                        // set CharSet, its value has to be propagated to compiler generated
                        // fixed field types
                        //
                        if (a.Type == pa.StructLayout && Fields != null && a.HasField ("CharSet")) {
                                for (int i = 0; i < Fields.Count; ++i) {
                                        FixedField ff = Fields [i] as FixedField;
                                        if (ff != null)
                                                ff.SetCharSet (TypeBuilder.Attributes);
                                }
                        }
                }

                bool CheckStructCycles (Struct s)
                {
                        if (s.Fields == null)
                                return true;

                        if (s.InTransit)
                                return false;

                        s.InTransit = true;
                        foreach (FieldBase field in s.Fields) {
                                TypeSpec ftype = field.Spec.MemberType;
                                if (!ftype.IsStruct)
                                        continue;

                                if (ftype is PredefinedTypeSpec)
                                        continue;

                                foreach (var targ in ftype.TypeArguments) {
                                        if (!CheckFieldTypeCycle (targ)) {
                                                Report.Error (523, field.Location,
                                                        "Struct member `{0}' of type `{1}' causes a cycle in the struct layout",
                                                        field.GetSignatureForError (), ftype.GetSignatureForError ());
                                                break;
                                        }
                                }

                                if ((field.IsStatic && (!ftype.IsGeneric || ftype == CurrentType)))
                                        continue;

                                if (!CheckFieldTypeCycle (ftype)) {
                                        Report.Error (523, field.Location,
                                                "Struct member `{0}' of type `{1}' causes a cycle in the struct layout",
                                                field.GetSignatureForError (), ftype.GetSignatureForError ());
                                        break;
                                }
                        }

                        s.InTransit = false;
                        return true;
                }

                bool CheckFieldTypeCycle (TypeSpec ts)
                {
                        var fts = ts.MemberDefinition as Struct;
                        if (fts == null)
                                return true;

                        return CheckStructCycles (fts);
                }

                public override void Emit ()
                {
                        CheckStructCycles (this);

                        base.Emit ();
                }

                public override bool IsUnmanagedType ()
                {
                        if (fields == null)
                                return true;

                        if (has_unmanaged_check_done)
                                return is_unmanaged;

                        if (requires_delayed_unmanagedtype_check)
                                return true;

                        requires_delayed_unmanagedtype_check = true;

                        foreach (FieldBase f in fields) {
                                if (f.IsStatic)
                                        continue;

                                // It can happen when recursive unmanaged types are defined
                                // struct S { S* s; }
                                TypeSpec mt = f.MemberType;
                                if (mt == null) {
                                        return true;
                                }

                                while (mt.IsPointer)
                                        mt = TypeManager.GetElementType (mt);

                                if (mt.MemberDefinition == this) {
                                        for (var p = Parent; p != null; p = p.Parent) {
                                                if (p.Kind == MemberKind.Class) {
                                                        has_unmanaged_check_done = true;
                                                        return false;
                                                }
                                        }
                                        continue;
                                }

                                if (TypeManager.IsUnmanagedType (mt))
                                        continue;

                                has_unmanaged_check_done = true;
                                return false;
                        }

                        has_unmanaged_check_done = true;
                        is_unmanaged = true;
                        return true;
                }

                protected override TypeExpr[] ResolveBaseTypes (out TypeExpr base_class)
                {
                        TypeExpr[] ifaces = base.ResolveBaseTypes (out base_class);
                        base_type = TypeManager.value_type;
                        return ifaces;
                }

                protected override TypeAttributes TypeAttr {
                        get {
                                const TypeAttributes DefaultTypeAttributes =
                                        TypeAttributes.SequentialLayout |
                                        TypeAttributes.Sealed;

                                return base.TypeAttr | DefaultTypeAttributes;
                        }
                }

                public override void RegisterFieldForInitialization (MemberCore field, FieldInitializer expression)
                {
                        if ((field.ModFlags & Modifiers.STATIC) == 0) {
                                Report.Error (573, field.Location, "`{0}': Structs cannot have instance field initializers",
                                        field.GetSignatureForError ());
                                return;
                        }
                        base.RegisterFieldForInitialization (field, expression);
                }

        }

        /// <summary>
        ///   Interfaces
        /// </summary>
        public sealed class Interface : TypeContainer {

                /// <summary>
                ///   Modifiers allowed in a class declaration
                /// </summary>
                public const Modifiers AllowedModifiers =
                        Modifiers.NEW       |
                        Modifiers.PUBLIC    |
                        Modifiers.PROTECTED |
                        Modifiers.INTERNAL  |
                        Modifiers.UNSAFE    |
                        Modifiers.PRIVATE;

                public Interface (NamespaceEntry ns, DeclSpace parent, MemberName name, Modifiers mod,
                                  Attributes attrs)
                        : base (ns, parent, name, attrs, MemberKind.Interface)
                {
                        var accmods = parent.Parent == null ? Modifiers.INTERNAL : Modifiers.PRIVATE;

                        this.ModFlags = ModifiersExtensions.Check (AllowedModifiers, mod, accmods, name.Location, Report);
                        spec = new TypeSpec (Kind, null, this, null, ModFlags);
                }

                public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
                {
                        if (a.Type == pa.ComImport && !attributes.Contains (pa.Guid)) {
                                a.Error_MissingGuidAttribute ();
                                return;
                        }

                        base.ApplyAttributeBuilder (a, ctor, cdata, pa);
                }


                public override AttributeTargets AttributeTargets {
                        get {
                                return AttributeTargets.Interface;
                        }
                }

                protected override TypeAttributes TypeAttr {
                        get {
                                const TypeAttributes DefaultTypeAttributes =
                                        TypeAttributes.AutoLayout |
                                        TypeAttributes.Abstract |
                                        TypeAttributes.Interface;

                                return base.TypeAttr | DefaultTypeAttributes;
                        }
                }

                protected override bool VerifyClsCompliance ()
                {
                        if (!base.VerifyClsCompliance ())
                                return false;

                        if (iface_exprs != null) {
                                foreach (var iface in iface_exprs) {
                                        if (iface.Type.IsCLSCompliant ())
                                                continue;

                                        Report.SymbolRelatedToPreviousError (iface.Type);
                                        Report.Warning (3027, 1, Location, "`{0}' is not CLS-compliant because base interface `{1}' is not CLS-compliant",
                                                GetSignatureForError (), TypeManager.CSharpName (iface.Type));
                                }
                        }

                        return true;
                }
        }

        public abstract class InterfaceMemberBase : MemberBase {
                //
                // Whether this is an interface member.
                //
                public bool IsInterface;

                //
                // If true, this is an explicit interface implementation
                //
                public bool IsExplicitImpl;

                protected bool is_external_implementation;

                //
                // The interface type we are explicitly implementing
                //
                public TypeSpec InterfaceType;

                //
                // The method we're overriding if this is an override method.
                //
                protected MethodSpec base_method;

                readonly Modifiers explicit_mod_flags;
                public MethodAttributes flags;

                public InterfaceMemberBase (DeclSpace parent, GenericMethod generic,
                                   FullNamedExpression type, Modifiers mod, Modifiers allowed_mod,
                                   MemberName name, Attributes attrs)
                        : base (parent, generic, type, mod, allowed_mod, Modifiers.PRIVATE,
                                name, attrs)
                {
                        IsInterface = parent.PartialContainer.Kind == MemberKind.Interface;
                        IsExplicitImpl = (MemberName.Left != null);
                        explicit_mod_flags = mod;
                }
                
                protected override bool CheckBase ()
                {
                        if (!base.CheckBase ())
                                return false;

                        if ((caching_flags & Flags.MethodOverloadsExist) != 0)
                                CheckForDuplications ();
                        
                        if (IsExplicitImpl)
                                return true;

                        // For System.Object only
                        if (Parent.BaseType == null)
                                return true;

                        MemberSpec candidate;
                        var base_member = FindBaseMember (out candidate);

                        if ((ModFlags & Modifiers.OVERRIDE) != 0) {
                                if (base_member == null) {
                                        if (candidate == null) {
                                                if (this is Method && ((Method)this).ParameterInfo.IsEmpty && MemberName.Name == Destructor.MetadataName && MemberName.Arity == 0) {
                                                        Report.Error (249, Location, "Do not override `{0}'. Use destructor syntax instead",
                                                                "object.Finalize()");
                                                } else {
                                                        Report.Error (115, Location, "`{0}' is marked as an override but no suitable {1} found to override",
                                                                GetSignatureForError (), SimpleName.GetMemberType (this));
                                                }
                                        } else {
                                                Report.SymbolRelatedToPreviousError (candidate);
                                                if (this is Event)
                                                        Report.Error (72, Location, "`{0}': cannot override because `{1}' is not an event",
                                                                GetSignatureForError (), TypeManager.GetFullNameSignature (candidate));
                                                else if (this is PropertyBase)
                                                        Report.Error (544, Location, "`{0}': cannot override because `{1}' is not a property",
                                                                GetSignatureForError (), TypeManager.GetFullNameSignature (candidate));
                                                else
                                                        Report.Error (505, Location, "`{0}': cannot override because `{1}' is not a method",
                                                                GetSignatureForError (), TypeManager.GetFullNameSignature (candidate));
                                        }

                                        return false;
                                }

                                if (!CheckOverrideAgainstBase (base_member))
                                        return false;

                                ObsoleteAttribute oa = base_member.GetAttributeObsolete ();
                                if (oa != null) {
                                        if (OptAttributes == null || !OptAttributes.Contains (PredefinedAttributes.Get.Obsolete)) {
                                                Report.SymbolRelatedToPreviousError (base_member);
                                                Report.Warning (672, 1, Location, "Member `{0}' overrides obsolete member `{1}'. Add the Obsolete attribute to `{0}'",
                                                        GetSignatureForError (), TypeManager.GetFullNameSignature (base_member));
                                        }
                                } else {
                                        if (OptAttributes != null && OptAttributes.Contains (PredefinedAttributes.Get.Obsolete)) {
                                                Report.SymbolRelatedToPreviousError (base_member);
                                                Report.Warning (809, 1, Location, "Obsolete member `{0}' overrides non-obsolete member `{1}'",
                                                        GetSignatureForError (), TypeManager.GetFullNameSignature (base_member));
                                        }
                                }

                                base_method = base_member as MethodSpec;
                                return true;
                        }

                        if (base_member == null && candidate != null && (!(candidate is IParametersMember) || !(this is IParametersMember)))
                                base_member = candidate;

                        if (base_member == null) {
                                if ((ModFlags & Modifiers.NEW) != 0) {
                                        if (base_member == null) {
                                                Report.Warning (109, 4, Location, "The member `{0}' does not hide an inherited member. The new keyword is not required",
                                                        GetSignatureForError ());
                                        }
                                }
                        } else {
                                if ((ModFlags & Modifiers.NEW) == 0) {
                                        ModFlags |= Modifiers.NEW;
                                        Report.SymbolRelatedToPreviousError (base_member);
                                        if (!IsInterface && (base_member.Modifiers & (Modifiers.ABSTRACT | Modifiers.VIRTUAL | Modifiers.OVERRIDE)) != 0) {
                                                Report.Warning (114, 2, Location, "`{0}' hides inherited member `{1}'. To make the current member override that implementation, add the override keyword. Otherwise add the new keyword",
                                                        GetSignatureForError (), base_member.GetSignatureForError ());
                                        } else {
                                                Report.Warning (108, 2, Location, "`{0}' hides inherited member `{1}'. Use the new keyword if hiding was intended",
                                                        GetSignatureForError (), base_member.GetSignatureForError ());
                                        }
                                }

                                if (!IsInterface && base_member.IsAbstract) {
                                        Report.SymbolRelatedToPreviousError (base_member);
                                        Report.Error (533, Location, "`{0}' hides inherited abstract member `{1}'",
                                                GetSignatureForError (), base_member.GetSignatureForError ());
                                }
                        }

                        return true;
                }

                protected virtual bool CheckForDuplications ()
                {
                        return Parent.MemberCache.CheckExistingMembersOverloads (this, ParametersCompiled.EmptyReadOnlyParameters);
                }

                //
                // Performs various checks on the MethodInfo `mb' regarding the modifier flags
                // that have been defined.
                //
                protected virtual bool CheckOverrideAgainstBase (MemberSpec base_member)
                {
                        bool ok = true;

                        if ((base_member.Modifiers & (Modifiers.ABSTRACT | Modifiers.VIRTUAL | Modifiers.OVERRIDE | Modifiers.OVERRIDE_UNCHECKED)) == 0) {
                                Report.SymbolRelatedToPreviousError (base_member);
                                Report.Error (506, Location,
                                        "`{0}': cannot override inherited member `{1}' because it is not marked virtual, abstract or override",
                                         GetSignatureForError (), TypeManager.CSharpSignature (base_member));
                                ok = false;
                        }

                        // Now we check that the overriden method is not final  
                        if ((base_member.Modifiers & Modifiers.SEALED) != 0) {
                                Report.SymbolRelatedToPreviousError (base_member);
                                Report.Error (239, Location, "`{0}': cannot override inherited member `{1}' because it is sealed",
                                                          GetSignatureForError (), TypeManager.CSharpSignature (base_member));
                                ok = false;
                        }

                        var base_member_type = ((IInterfaceMemberSpec) base_member).MemberType;
                        if (!TypeSpecComparer.Override.IsEqual (MemberType, base_member_type)) {
                                Report.SymbolRelatedToPreviousError (base_member);
                                if (this is PropertyBasedMember) {
                                        Report.Error (1715, Location, "`{0}': type must be `{1}' to match overridden member `{2}'",
                                                GetSignatureForError (), TypeManager.CSharpName (base_member_type), TypeManager.CSharpSignature (base_member));
                                } else {
                                        Report.Error (508, Location, "`{0}': return type must be `{1}' to match overridden member `{2}'",
                                                GetSignatureForError (), TypeManager.CSharpName (base_member_type), TypeManager.CSharpSignature (base_member));
                                }
                                ok = false;
                        }

                        return ok;
                }

                protected static bool CheckAccessModifiers (MemberCore this_member, MemberSpec base_member)
                {
                        var thisp = this_member.ModFlags & Modifiers.AccessibilityMask;
                        var base_classp = base_member.Modifiers & Modifiers.AccessibilityMask;

                        if ((base_classp & (Modifiers.PROTECTED | Modifiers.INTERNAL)) == (Modifiers.PROTECTED | Modifiers.INTERNAL)) {
                                //
                                // when overriding protected internal, the method can be declared
                                // protected internal only within the same assembly or assembly
                                // which has InternalsVisibleTo
                                //
                                if ((thisp & (Modifiers.PROTECTED | Modifiers.INTERNAL)) == (Modifiers.PROTECTED | Modifiers.INTERNAL)) {
                                        return TypeManager.IsThisOrFriendAssembly (this_member.Assembly, base_member.Assembly);
                                } 
                                if ((thisp & Modifiers.PROTECTED) != Modifiers.PROTECTED) {
                                        //
                                        // if it's not "protected internal", it must be "protected"
                                        //

                                        return false;
                                }
                                if (this_member.Parent.PartialContainer.Module.Assembly == base_member.Assembly) {
                                        //
                                        // protected within the same assembly - an error
                                        //
                                        return false;
                                }
                                if ((thisp & ~(Modifiers.PROTECTED | Modifiers.INTERNAL)) !=
                                           (base_classp & ~(Modifiers.PROTECTED | Modifiers.INTERNAL))) {
                                        //
                                        // protected ok, but other attributes differ - report an error
                                        //
                                        return false;
                                }
                                return true;
                        }

                        return thisp == base_classp;
                }

                public override bool Define ()
                {
                        if (IsInterface) {
                                ModFlags = Modifiers.PUBLIC | Modifiers.ABSTRACT |
                                        Modifiers.VIRTUAL | (ModFlags & (Modifiers.UNSAFE | Modifiers.NEW));

                                flags = MethodAttributes.Public |
                                        MethodAttributes.Abstract |
                                        MethodAttributes.HideBySig |
                                        MethodAttributes.NewSlot |
                                        MethodAttributes.Virtual;
                        } else {
                                Parent.PartialContainer.MethodModifiersValid (this);

                                flags = ModifiersExtensions.MethodAttr (ModFlags);
                        }

                        if (IsExplicitImpl) {
                                TypeExpr iface_texpr = MemberName.Left.GetTypeExpression ().ResolveAsTypeTerminal (Parent, false);
                                if (iface_texpr == null)
                                        return false;

                                if ((ModFlags & Modifiers.PARTIAL) != 0) {
                                        Report.Error (754, Location, "A partial method `{0}' cannot explicitly implement an interface",
                                                GetSignatureForError ());
                                }

                                InterfaceType = iface_texpr.Type;

                                if (!InterfaceType.IsInterface) {
                                        Report.SymbolRelatedToPreviousError (InterfaceType);
                                        Report.Error (538, Location, "The type `{0}' in explicit interface declaration is not an interface",
                                                TypeManager.CSharpName (InterfaceType));
                                } else {
                                        Parent.PartialContainer.VerifyImplements (this);
                                }

                                ModifiersExtensions.Check (Modifiers.AllowedExplicitImplFlags, explicit_mod_flags, 0, Location, Report);
                        }

                        return base.Define ();
                }

                protected bool DefineParameters (ParametersCompiled parameters)
                {
                        if (!parameters.Resolve (this))
                                return false;

                        bool error = false;
                        for (int i = 0; i < parameters.Count; ++i) {
                                Parameter p = parameters [i];

                                if (p.HasDefaultValue && (IsExplicitImpl || this is Operator || (this is Indexer && parameters.Count == 1)))
                                        p.Warning_UselessOptionalParameter (Report);

                                if (p.CheckAccessibility (this))
                                        continue;

                                TypeSpec t = parameters.Types [i];
                                Report.SymbolRelatedToPreviousError (t);
                                if (this is Indexer)
                                        Report.Error (55, Location,
                                                      "Inconsistent accessibility: parameter type `{0}' is less accessible than indexer `{1}'",
                                                      TypeManager.CSharpName (t), GetSignatureForError ());
                                else if (this is Operator)
                                        Report.Error (57, Location,
                                                      "Inconsistent accessibility: parameter type `{0}' is less accessible than operator `{1}'",
                                                      TypeManager.CSharpName (t), GetSignatureForError ());
                                else
                                        Report.Error (51, Location,
                                                "Inconsistent accessibility: parameter type `{0}' is less accessible than method `{1}'",
                                                TypeManager.CSharpName (t), GetSignatureForError ());
                                error = true;
                        }
                        return !error;
                }

                public override void Emit()
                {
                        // for extern static method must be specified either DllImport attribute or MethodImplAttribute.
                        // We are more strict than csc and report this as an error because SRE does not allow emit that
                        if ((ModFlags & Modifiers.EXTERN) != 0 && !is_external_implementation) {
                                if (this is Constructor) {
                                        Report.Error (824, Location,
                                                "Constructor `{0}' is marked `external' but has no external implementation specified", GetSignatureForError ());
                                } else {
                                        Report.Error (626, Location,
                                                "`{0}' is marked as an external but has no DllImport attribute. Consider adding a DllImport attribute to specify the external implementation",
                                                GetSignatureForError ());
                                }
                        }

                        base.Emit ();
                }

                public override bool EnableOverloadChecks (MemberCore overload)
                {
                        //
                        // Two members can differ in their explicit interface
                        // type parameter only
                        //
                        InterfaceMemberBase imb = overload as InterfaceMemberBase;
                        if (imb != null && imb.IsExplicitImpl) {
                                if (IsExplicitImpl) {
                                        caching_flags |= Flags.MethodOverloadsExist;
                                }
                                return true;
                        }

                        return IsExplicitImpl;
                }

                protected void Error_CannotChangeAccessModifiers (MemberCore member, MemberSpec base_member)
                {
                        Report.SymbolRelatedToPreviousError (base_member);
                        Report.Error (507, member.Location,
                                "`{0}': cannot change access modifiers when overriding `{1}' inherited member `{2}'",
                                member.GetSignatureForError (),
                                ModifiersExtensions.AccessibilityName (base_member.Modifiers),
                                base_member.GetSignatureForError ());
                }

                protected void Error_StaticReturnType ()
                {
                        Report.Error (722, Location,
                                "`{0}': static types cannot be used as return types",
                                MemberType.GetSignatureForError ());
                }

                /// <summary>
                /// Gets base method and its return type
                /// </summary>
                protected virtual MemberSpec FindBaseMember (out MemberSpec bestCandidate)
                {
                        return MemberCache.FindBaseMember (this, out bestCandidate);
                }

                //
                // The "short" name of this property / indexer / event.  This is the
                // name without the explicit interface.
                //
                public string ShortName {
                        get { return MemberName.Name; }
                        set { SetMemberName (new MemberName (MemberName.Left, value, Location)); }
                }
                
                //
                // Returns full metadata method name
                //
                public string GetFullName (MemberName name)
                {
                        return GetFullName (name.Name);
                }

                public string GetFullName (string name)
                {
                        if (!IsExplicitImpl)
                                return name;

                        //
                        // When dealing with explicit members a full interface type
                        // name is added to member name to avoid possible name conflicts
                        //
                        // We use CSharpName which gets us full name with benefit of
                        // replacing predefined names which saves some space and name
                        // is still unique
                        //
                        return TypeManager.CSharpName (InterfaceType) + "." + name;
                }

                protected override bool VerifyClsCompliance ()
                {
                        if (!base.VerifyClsCompliance ()) {
                                return false;
                        }

                        if (GenericMethod != null)
                                GenericMethod.VerifyClsCompliance ();

                        return true;
                }

                public override bool IsUsed 
                {
                        get { return IsExplicitImpl || base.IsUsed; }
                }

        }

        public abstract class MemberBase : MemberCore
        {
                protected FullNamedExpression type_expr;
                protected TypeSpec member_type;

                public readonly DeclSpace ds;
                public readonly GenericMethod GenericMethod;

                protected MemberBase (DeclSpace parent, GenericMethod generic,
                                      FullNamedExpression type, Modifiers mod, Modifiers allowed_mod, Modifiers def_mod,
                                      MemberName name, Attributes attrs)
                        : base (parent, name, attrs)
                {
                        this.ds = generic != null ? generic : (DeclSpace) parent;
                        this.type_expr = type;
                        ModFlags = ModifiersExtensions.Check (allowed_mod, mod, def_mod, Location, Report);
                        GenericMethod = generic;
                        if (GenericMethod != null)
                                GenericMethod.ModFlags = ModFlags;
                }

                #region Properties

                public TypeSpec MemberType {
                        get {
                                return member_type;
                        }
                }

                public FullNamedExpression TypeExpression {
                        get {
                                return type_expr;
                        }
                }

                #endregion

                //
                // Main member define entry
                //
                public override bool Define ()
                {
                        DoMemberTypeIndependentChecks ();

                        //
                        // Returns false only when type resolution failed
                        //
                        if (!ResolveMemberType ())
                                return false;

                        DoMemberTypeDependentChecks ();
                        return true;
                }

                //
                // Any type_name independent checks
                //
                protected virtual void DoMemberTypeIndependentChecks ()
                {
                        if ((Parent.ModFlags & Modifiers.SEALED) != 0 &&
                                (ModFlags & (Modifiers.VIRTUAL | Modifiers.ABSTRACT)) != 0) {
                                Report.Error (549, Location, "New virtual member `{0}' is declared in a sealed class `{1}'",
                                        GetSignatureForError (), Parent.GetSignatureForError ());
                        }
                }

                //
                // Any type_name dependent checks
                //
                protected virtual void DoMemberTypeDependentChecks ()
                {
                        // verify accessibility
                        if (!IsAccessibleAs (MemberType)) {
                                Report.SymbolRelatedToPreviousError (MemberType);
                                if (this is Property)
                                        Report.Error (53, Location,
                                                      "Inconsistent accessibility: property type `" +
                                                      TypeManager.CSharpName (MemberType) + "' is less " +
                                                      "accessible than property `" + GetSignatureForError () + "'");
                                else if (this is Indexer)
                                        Report.Error (54, Location,
                                                      "Inconsistent accessibility: indexer return type `" +
                                                      TypeManager.CSharpName (MemberType) + "' is less " +
                                                      "accessible than indexer `" + GetSignatureForError () + "'");
                                else if (this is MethodCore) {
                                        if (this is Operator)
                                                Report.Error (56, Location,
                                                              "Inconsistent accessibility: return type `" +
                                                              TypeManager.CSharpName (MemberType) + "' is less " +
                                                              "accessible than operator `" + GetSignatureForError () + "'");
                                        else
                                                Report.Error (50, Location,
                                                              "Inconsistent accessibility: return type `" +
                                                              TypeManager.CSharpName (MemberType) + "' is less " +
                                                              "accessible than method `" + GetSignatureForError () + "'");
                                } else {
                                        Report.Error (52, Location,
                                                      "Inconsistent accessibility: field type `" +
                                                      TypeManager.CSharpName (MemberType) + "' is less " +
                                                      "accessible than field `" + GetSignatureForError () + "'");
                                }
                        }

                        Variance variance = this is Event ? Variance.Contravariant : Variance.Covariant;
                        TypeManager.CheckTypeVariance (MemberType, variance, this);
                }

                protected bool IsTypePermitted ()
                {
                        if (TypeManager.IsSpecialType (MemberType)) {
                                Report.Error (610, Location, "Field or property cannot be of type `{0}'", TypeManager.CSharpName (MemberType));
                                return false;
                        }
                        return true;
                }

                protected virtual bool CheckBase ()
                {
                        CheckProtectedModifier ();

                        return true;
                }

                protected virtual bool ResolveMemberType ()
                {
                        if (member_type != null)
                                throw new InternalErrorException ("Multi-resolve");

                        TypeExpr te = type_expr.ResolveAsTypeTerminal (this, false);
                        if (te == null)
                                return false;
                        
                        //
                        // Replace original type name, error reporting can use fully resolved name
                        //
                        type_expr = te;

                        member_type = te.Type;
                        return true;
                }
        }
}