Fix bugs in sizing TableLayoutPanel (Xamarin bug 18638)

[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@gmail.com)
//
// Dual licensed under the terms of the MIT X11 or GNU GPL
//
// Copyright 2001, 2002, 2003 Ximian, Inc (http://www.ximian.com)
// Copyright 2004-2011 Novell, Inc
// Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
//

using System;
using System.Linq;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Security;
using System.Security.Permissions;
using System.Text;
using System.Diagnostics;
using Mono.CompilerServices.SymbolWriter;

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

#if STATIC
using SecurityType = System.Collections.Generic.List<IKVM.Reflection.Emit.CustomAttributeBuilder>;
using IKVM.Reflection;
using IKVM.Reflection.Emit;
#else
using SecurityType = System.Collections.Generic.Dictionary<System.Security.Permissions.SecurityAction, System.Security.PermissionSet>;
using System.Reflection;
using System.Reflection.Emit;
#endif

namespace Mono.CSharp
{
        //
        // General types container, used as a base class for all constructs which can hold types
        //
        public abstract class TypeContainer : MemberCore
        {
                public readonly MemberKind Kind;

                protected List<TypeContainer> containers;

                TypeDefinition main_container;

                protected Dictionary<string, MemberCore> defined_names;

                protected bool is_defined;

                public int CounterAnonymousMethods { get; set; }
                public int CounterAnonymousContainers { get; set; }
                public int CounterSwitchTypes { get; set; }

                protected TypeContainer (TypeContainer parent, MemberName name, Attributes attrs, MemberKind kind)
                        : base (parent, name, attrs)
                {
                        this.Kind = kind;
                        defined_names = new Dictionary<string, MemberCore> ();
                }

                public override TypeSpec CurrentType {
                        get {
                                return null;
                        }
                }

                public Dictionary<string, MemberCore> DefinedNames {
                        get {
                                return defined_names;
                        }
                }

                public TypeDefinition PartialContainer {
                        get {
                                return main_container;
                        }
                        protected set {
                                main_container = value;
                        }
                }

                public IList<TypeContainer> Containers {
                        get {
                                return containers;
                        }
                }

                //
                // Any unattached attributes during parsing get added here. User
                // by FULL_AST mode
                //
                public Attributes UnattachedAttributes {
                        get; set;
                }

                public void AddCompilerGeneratedClass (CompilerGeneratedContainer c)
                {
                        AddTypeContainerMember (c);
                }

                public virtual void AddPartial (TypeDefinition next_part)
                {
                        MemberCore mc;
                        (PartialContainer ?? this).defined_names.TryGetValue (next_part.MemberName.Basename, out mc);

                        AddPartial (next_part, mc as TypeDefinition);
                }

                protected void AddPartial (TypeDefinition next_part, TypeDefinition existing)
                {
                        next_part.ModFlags |= Modifiers.PARTIAL;

                        if (existing == null) {
                                AddTypeContainer (next_part);
                                return;
                        }

                        if ((existing.ModFlags & Modifiers.PARTIAL) == 0) {
                                if (existing.Kind != next_part.Kind) {
                                        AddTypeContainer (next_part);
                                } else {
                                        Report.SymbolRelatedToPreviousError (next_part);
                                        Error_MissingPartialModifier (existing);
                                }

                                return;
                        }

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

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

                        var tc_names = existing.CurrentTypeParameters;
                        if (tc_names != null) {
                                for (int i = 0; i < tc_names.Count; ++i) {
                                        var tp = next_part.MemberName.TypeParameters[i];
                                        if (tc_names[i].MemberName.Name != tp.MemberName.Name) {
                                                Report.SymbolRelatedToPreviousError (existing.Location, "");
                                                Report.Error (264, next_part.Location, "Partial declarations of `{0}' must have the same type parameter names in the same order",
                                                        next_part.GetSignatureForError ());
                                                break;
                                        }

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

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

                        existing.Definition.Modifiers = existing.ModFlags;

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

                        next_part.PartialContainer = existing;

                        existing.AddPartialPart (next_part);

                        AddTypeContainerMember (next_part);
                }

                public virtual void AddTypeContainer (TypeContainer tc)
                {
                        AddTypeContainerMember (tc);

                        var tparams = tc.MemberName.TypeParameters;
                        if (tparams != null && tc.PartialContainer != null) {
                                var td = (TypeDefinition) tc;
                                for (int i = 0; i < tparams.Count; ++i) {
                                        var tp = tparams[i];
                                        if (tp.MemberName == null)
                                                continue;

                                        td.AddNameToContainer (tp, tp.Name);
                                }
                        }
                }

                protected virtual void AddTypeContainerMember (TypeContainer tc)
                {
                        containers.Add (tc);
                }

                public virtual void CloseContainer ()
                {
                        if (containers != null) {
                                foreach (TypeContainer tc in containers) {
                                        tc.CloseContainer ();
                                }
                        }
                }

                public virtual void CreateMetadataName (StringBuilder sb)
                {
                        if (Parent != null && Parent.MemberName != null)
                                Parent.CreateMetadataName (sb);

                        MemberName.CreateMetadataName (sb);
                }

                public virtual bool CreateContainer ()
                {
                        if (containers != null) {
                                foreach (TypeContainer tc in containers) {
                                        tc.CreateContainer ();
                                }
                        }

                        return true;
                }

                public override bool Define ()
                {
                        if (containers != null) {
                                foreach (TypeContainer tc in containers) {
                                        tc.Define ();
                                }
                        }

                        // Release cache used by parser only
                        if (Module.Evaluator == null) {
                                defined_names = null;
                        } else {
                                defined_names.Clear ();
                        }

                        return true;
                }

                public virtual void PrepareEmit ()
                {
                        if (containers != null) {
                                foreach (var t in containers) {
                                        try {
                                                t.PrepareEmit ();
                                        } catch (Exception e) {
                                                if (MemberName == MemberName.Null)
                                                        throw;

                                                throw new InternalErrorException (t, e);
                                        }
                                }
                        }
                }

                public virtual bool DefineContainer ()
                {
                        if (is_defined)
                                return true;

                        is_defined = true;

                        DoDefineContainer ();

                        if (containers != null) {
                                foreach (TypeContainer tc in containers) {
                                        try {
                                                tc.DefineContainer ();
                                        } catch (Exception e) {
                                                if (MemberName == MemberName.Null)
                                                        throw;

                                                throw new InternalErrorException (tc, e);
                                        }
                                }
                        }

                        return true;
                }

                public virtual void ExpandBaseInterfaces ()
                {
                        if (containers != null) {
                                foreach (TypeContainer tc in containers) {
                                        tc.ExpandBaseInterfaces ();
                                }
                        }
                }

                protected virtual void DefineNamespace ()
                {
                        if (containers != null) {
                                foreach (var tc in containers) {
                                        try {
                                                tc.DefineNamespace ();
                                        } catch (Exception e) {
                                                throw new InternalErrorException (tc, e);
                                        }
                                }
                        }
                }

                protected virtual void DoDefineContainer ()
                {
                }

                public virtual void EmitContainer ()
                {
                        if (containers != null) {
                                for (int i = 0; i < containers.Count; ++i)
                                        containers[i].EmitContainer ();
                        }
                }

                protected void Error_MissingPartialModifier (MemberCore type)
                {
                        Report.Error (260, type.Location,
                                "Missing partial modifier on declaration of type `{0}'. Another partial declaration of this type exists",
                                type.GetSignatureForError ());
                }

                public override string GetSignatureForDocumentation ()
                {
                        if (Parent != null && Parent.MemberName != null)
                                return Parent.GetSignatureForDocumentation () + "." + MemberName.GetSignatureForDocumentation ();

                        return MemberName.GetSignatureForDocumentation ();
                }

                public override string GetSignatureForError ()
                {
                        if (Parent != null && Parent.MemberName != null) 
                                return Parent.GetSignatureForError () + "." + MemberName.GetSignatureForError ();

                        return MemberName.GetSignatureForError ();
                }

                public string GetSignatureForMetadata ()
                {
                        if (Parent is TypeDefinition) {
                                return Parent.GetSignatureForMetadata () + "+" + TypeNameParser.Escape (MemberName.Basename);
                        }

                        var sb = new StringBuilder ();
                        CreateMetadataName (sb);
                        return sb.ToString ();
                }

                public virtual void RemoveContainer (TypeContainer cont)
                {
                        if (containers != null)
                                containers.Remove (cont);

                        var tc = Parent == Module ? Module : this;
                        tc.defined_names.Remove (cont.MemberName.Basename);
                }

                public virtual void VerifyMembers ()
                {
                        if (containers != null) {
                                foreach (TypeContainer tc in containers)
                                        tc.VerifyMembers ();
                        }
                }

                public override void WriteDebugSymbol (MonoSymbolFile file)
                {
                        if (containers != null) {
                                foreach (TypeContainer tc in containers) {
                                        tc.WriteDebugSymbol (file);
                                }
                        }
                }
        }

        public abstract class TypeDefinition : TypeContainer, 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.PartialContainer.CurrentType; }
                        }

                        public TypeParameters CurrentTypeParameters {
                                get { return tc.PartialContainer.CurrentTypeParameters; }
                        }

                        public MemberCore CurrentMemberDefinition {
                                get { return tc; }
                        }

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

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

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

                        public ModuleContainer Module {
                                get { return tc.Module; }
                        }

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

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

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

                        public FullNamedExpression LookupNamespaceOrType (string name, int arity, LookupMode mode, Location loc)
                        {
                                if (arity == 0) {
                                        var tp = CurrentTypeParameters;
                                        if (tp != null) {
                                                TypeParameter t = tp.Find (name);
                                                if (t != null)
                                                        return new TypeParameterExpr (t, loc);
                                        }
                                }

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

                        #endregion
                }

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

                readonly List<MemberCore> members;

                // 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;

                Dictionary<MethodSpec, Method> hoisted_base_call_proxies;

                Dictionary<string, FullNamedExpression> Cache = new Dictionary<string, FullNamedExpression> ();

                //
                // 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.
                //
                protected FieldBase first_nonstatic_field;

                //
                // This one is computed after we can distinguish interfaces
                // from classes from the arraylist `type_bases' 
                //
                protected TypeSpec base_type;
                FullNamedExpression base_type_expr;     // TODO: It's temporary variable
                protected TypeSpec[] iface_exprs;

                protected List<FullNamedExpression> type_bases;

                // Partial parts for classes only
                List<TypeDefinition> class_partial_parts;

                TypeDefinition InTransit;

                public TypeBuilder TypeBuilder;
                GenericTypeParameterBuilder[] all_tp_builders;
                //
                // All recursive type parameters put together sharing same
                // TypeParameter instances
                //
                TypeParameters all_type_parameters;

                public const string DefaultIndexerName = "Item";

                bool has_normal_indexers;
                string indexer_name;
                protected bool requires_delayed_unmanagedtype_check;
                bool error;
                bool members_defined;
                bool members_defined_ok;
                protected bool has_static_constructor;

                private CachedMethods cached_method;

                protected TypeSpec spec;
                TypeSpec current_type;

                public int DynamicSitesCounter;
                public int AnonymousMethodsCounter;
                public int MethodGroupsCounter;

                static readonly string[] attribute_targets = new [] { "type" };
                static readonly string[] attribute_targets_primary = new [] { "type", "method" };

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

                protected TypeDefinition (TypeContainer parent, MemberName name, Attributes attrs, MemberKind kind)
                        : base (parent, name, attrs, kind)
                {
                        PartialContainer = this;
                        members = new List<MemberCore> ();
                }

                #region Properties

                public List<FullNamedExpression> BaseTypeExpressions {
                        get {
                                return type_bases;
                        }
                }

                public override TypeSpec CurrentType {
                        get {
                                if (current_type == null) {
                                        if (IsGenericOrParentIsGeneric) {
                                                //
                                                // Switch to inflated version as it's used by all expressions
                                                //
                                                var targs = CurrentTypeParameters == null ? TypeSpec.EmptyTypes : CurrentTypeParameters.Types;
                                                current_type = spec.MakeGenericType (this, targs);
                                        } else {
                                                current_type = spec;
                                        }
                                }

                                return current_type;
                        }
                }

                public override TypeParameters CurrentTypeParameters {
                        get {
                                return PartialContainer.MemberName.TypeParameters;
                        }
                }

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

                public virtual AssemblyDefinition DeclaringAssembly {
                        get {
                                return Module.DeclaringAssembly;
                        }
                }

                IAssemblyDefinition ITypeDefinition.DeclaringAssembly {
                        get {
                                return Module.DeclaringAssembly;
                        }
                }

                public TypeSpec Definition {
                        get {
                                return spec;
                        }
                }

                public bool HasMembersDefined {
                        get {
                                return members_defined;
                        }
                }

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

                // 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 HasOperators {
                        get {
                                return (caching_flags & Flags.HasUserOperators) != 0;
                        }
                        set {
                                caching_flags |= Flags.HasUserOperators;
                        }
                }

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

                public TypeSpec[] Interfaces {
                        get {
                                return iface_exprs;
                        }
                }

                public bool IsGenericOrParentIsGeneric {
                        get {
                                return all_type_parameters != null;
                        }
                }

                public bool IsTopLevel {
                        get {
                                return !(Parent is TypeDefinition);
                        }
                }

                public bool IsPartial {
                        get {
                                return (ModFlags & Modifiers.PARTIAL) != 0;
                        }
                }

                bool ITypeDefinition.IsTypeForwarder {
                        get {
                                return false;
                        }
                }

                bool ITypeDefinition.IsCyclicTypeForwarder {
                        get {
                                return false;
                        }
                }

                //
                // Returns true for secondary partial containers
                //
                bool IsPartialPart {
                        get {
                                return PartialContainer != this;
                        }
                }

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

                public List<MemberCore> Members {
                        get {
                                return members;
                        }
                }

                string ITypeDefinition.Namespace {
                        get {
                                var p = Parent;
                                while (p.Kind != MemberKind.Namespace)
                                        p = p.Parent;

                                return p.MemberName == null ? null : p.GetSignatureForError ();
                        }
                }

                public ParametersCompiled PrimaryConstructorParameters { get; set; }

                public Arguments PrimaryConstructorBaseArguments { get; set; }

                public Location PrimaryConstructorBaseArgumentsStart { get; set; }

                public TypeParameters TypeParametersAll {
                        get {
                                return all_type_parameters;
                        }
                }

                public override string[] ValidAttributeTargets {
                        get {
                                return PrimaryConstructorParameters != null ? attribute_targets_primary : attribute_targets;
                        }
                }

                #endregion

                public override void Accept (StructuralVisitor visitor)
                {
                        visitor.Visit (this);
                }

                public void AddMember (MemberCore symbol)
                {
                        if (symbol.MemberName.ExplicitInterface != null) {
                                if (!(Kind == MemberKind.Class || Kind == MemberKind.Struct)) {
                                        Report.Error (541, symbol.Location,
                                                "`{0}': explicit interface declaration can only be declared in a class or struct",
                                                symbol.GetSignatureForError ());
                                }
                        }

                        AddNameToContainer (symbol, symbol.MemberName.Name);
                        members.Add (symbol);
                }

                public override void AddTypeContainer (TypeContainer tc)
                {
                        AddNameToContainer (tc, tc.MemberName.Basename);

                        base.AddTypeContainer (tc);
                }

                protected override void AddTypeContainerMember (TypeContainer tc)
                {
                        members.Add (tc);

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

                        base.AddTypeContainerMember (tc);
                }

                //
                // Adds the member to defined_names table. It tests for duplications and enclosing name conflicts
                //
                public virtual void AddNameToContainer (MemberCore symbol, string name)
                {
                        if (((ModFlags | symbol.ModFlags) & Modifiers.COMPILER_GENERATED) != 0)
                                return;

                        MemberCore mc;
                        if (!PartialContainer.defined_names.TryGetValue (name, out mc)) {
                                PartialContainer.defined_names.Add (name, symbol);
                                return;
                        }

                        if (symbol.EnableOverloadChecks (mc))
                                return;

                        InterfaceMemberBase im = mc as InterfaceMemberBase;
                        if (im != null && im.IsExplicitImpl)
                                return;

                        Report.SymbolRelatedToPreviousError (mc);
                        if ((mc.ModFlags & Modifiers.PARTIAL) != 0 && (symbol is ClassOrStruct || symbol is Interface)) {
                                Error_MissingPartialModifier (symbol);
                                return;
                        }

                        if (symbol is TypeParameter) {
                                Report.Error (692, symbol.Location,
                                        "Duplicate type parameter `{0}'", symbol.GetSignatureForError ());
                        } else {
                                Report.Error (102, symbol.Location,
                                        "The type `{0}' already contains a definition for `{1}'",
                                        GetSignatureForError (), name);
                        }

                        return;
                }
        
                public void AddConstructor (Constructor c)
                {
                        AddConstructor (c, false);
                }

                public void AddConstructor (Constructor c, bool isDefault)
                {
                        bool is_static = (c.ModFlags & Modifiers.STATIC) != 0;
                        if (!isDefault)
                                AddNameToContainer (c, is_static ? Constructor.TypeConstructorName : Constructor.ConstructorName);

                        if (is_static && c.ParameterInfo.IsEmpty) {
                                PartialContainer.has_static_constructor = true;
                        } else {
                                PartialContainer.HasInstanceConstructor = true;
                        }

                        members.Add (c);
                }

                public bool AddField (FieldBase field)
                {
                        AddMember (field);

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

                        var first_field = PartialContainer.first_nonstatic_field;
                        if (first_field == null) {
                                PartialContainer.first_nonstatic_field = field;
                                return true;
                        }

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

                /// <summary>
                /// Indexer has special handling in constrast to other AddXXX because the name can be driven by IndexerNameAttribute
                /// </summary>
                public void AddIndexer (Indexer i)
                {
                        members.Add (i);
                }

                public void AddOperator (Operator op)
                {
                        PartialContainer.HasOperators = true;
                        AddMember (op);
                }

                public void AddPartialPart (TypeDefinition part)
                {
                        if (Kind != MemberKind.Class)
                                return;

                        if (class_partial_parts == null)
                                class_partial_parts = new List<TypeDefinition> ();

                        class_partial_parts.Add (part);
                }

                public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
                {
                        if (a.Target == AttributeTargets.Method) {
                                foreach (var m in members) {
                                        var c = m as Constructor;
                                        if (c == null)
                                                continue;

                                        if (c.IsPrimaryConstructor) {
                                                c.ApplyAttributeBuilder (a, ctor, cdata, pa);
                                                return;
                                        }
                                }

                                throw new InternalErrorException ();
                        }

                        if (has_normal_indexers && a.Type == pa.DefaultMember) {
                                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 TypeSpec BaseType {
                        get {
                                return spec.BaseType;
                        }
                }

                protected virtual TypeAttributes TypeAttr {
                        get {
                                return ModifiersExtensions.TypeAttr (ModFlags, IsTopLevel);
                        }
                }

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

                TypeParameterSpec[] ITypeDefinition.TypeParameters {
                        get {
                                return PartialContainer.CurrentTypeParameters.Types;
                        }
                }

                public string GetAttributeDefaultMember ()
                {
                        return indexer_name ?? DefaultIndexerName;
                }

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

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

                public void RegisterFieldForInitialization (MemberCore field, FieldInitializer expression)
                {
                        if (IsPartialPart)
                                PartialContainer.RegisterFieldForInitialization (field, expression);

                        if ((field.ModFlags & Modifiers.STATIC) != 0){
                                if (initialized_static_fields == null) {
                                        HasStaticFieldInitializer = true;
                                        initialized_static_fields = new List<FieldInitializer> (4);
                                }

                                initialized_static_fields.Add (expression);
                        } else {
                                if (Kind == MemberKind.Struct) {
                                        if (Compiler.Settings.Version != LanguageVersion.Experimental) {
                                                Report.Error (573, expression.Location, "'{0}': Structs cannot have instance property or field initializers",
                                                        GetSignatureForError ());
                                        }
                                }

                                if (initialized_fields == null)
                                        initialized_fields = new List<FieldInitializer> (4);

                                initialized_fields.Add (expression);
                        }
                }

                public void ResolveFieldInitializers (BlockContext ec)
                {
                        Debug.Assert (!IsPartialPart);

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

                                bool has_complex_initializer = !ec.Module.Compiler.Settings.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.IsSideEffectFree) {
                                                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.AssignmentInfoOffset += fi.AssignmentOffset;
                                        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];

                                //
                                // Clone before resolving otherwise when field initializer is needed
                                // in more than 1 constructor any resolve after the initial one would
                                // only took the resolved expression which is problem for expressions
                                // that generate extra expressions or code during Resolve phase
                                //
                                var cloned = fi.Clone (new CloneContext ());

                                ExpressionStatement s = fi.ResolveStatement (ec);
                                if (s == null) {
                                        initialized_fields [i] = new FieldInitializer (fi.Field, ErrorExpression.Instance, Location.Null);
                                        continue;
                                }

                                //
                                // Field is re-initialized to its default value => removed
                                //
                                if (fi.IsDefaultInitializer && Kind != MemberKind.Struct && ec.Module.Compiler.Settings.Optimize)
                                        continue;

                                ec.AssignmentInfoOffset += fi.AssignmentOffset;
                                ec.CurrentBlock.AddScopeStatement (new StatementExpression (s));
                                initialized_fields [i] = (FieldInitializer) cloned;
                        }
                }

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

                                comment += value;
                        }
                }

                public PendingImplementation PendingImplementations {
                        get { return pending; }
                }

                internal override void GenerateDocComment (DocumentationBuilder builder)
                {
                        if (IsPartialPart)
                                return;

                        base.GenerateDocComment (builder);

                        foreach (var member in members)
                                member.GenerateDocComment (builder);
                }

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

                        Attribute a = OptAttributes.Search (Module.PredefinedAttributes.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 CompilationSourceFile GetCompilationSourceFile ()
                {
                        TypeContainer ns = Parent;
                        while (true) {
                                var sf = ns as CompilationSourceFile;
                                if (sf != null)
                                        return sf;

                                ns = ns.Parent;
                        }
                }

                public virtual void SetBaseTypes (List<FullNamedExpression> baseTypes)
                {
                        type_bases = baseTypes;
                }

                /// <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 TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
                {
                        base_class = null;
                        if (type_bases == null)
                                return null;

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

                                var fne_resolved = fne.ResolveAsType (base_context);
                                if (fne_resolved == null)
                                        continue;

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

                                                continue;
                                        }
                                        
                                        base_type = fne_resolved;
                                        base_class = fne;
                                        continue;
                                }

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

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

                                        if (Kind == MemberKind.Interface && !IsAccessibleAs (fne_resolved)) {
                                                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);
                                        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;
                }

                //
                // 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;
                        List<Operator.OpType> found_matched = new List<Operator.OpType> ();

                        for (int i = 0; i < members.Count; ++i) {
                                var o_a = members[i] as Operator;
                                if (o_a == null)
                                        continue;

                                var o_type = o_a.OperatorType;
                                if (o_type == Operator.OpType.Equality || o_type == Operator.OpType.Inequality)
                                        has_equality_or_inequality = true;

                                if (found_matched.Contains (o_type))
                                        continue;

                                var matching_type = o_a.GetMatchingOperator ();
                                if (matching_type == Operator.OpType.TOP) {
                                        continue;
                                }

                                bool pair_found = false;
                                for (int ii = 0; ii < members.Count; ++ii) {
                                        var o_b = members[ii] as Operator;
                                        if (o_b == null || o_b.OperatorType != matching_type)
                                                continue;

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

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

                                        found_matched.Add (matching_type);
                                        pair_found = true;
                                        break;
                                }

                                if (!pair_found) {
                                        Report.Error (216, o_a.Location,
                                                "The operator `{0}' requires a matching operator `{1}' to also be defined",
                                                o_a.GetSignatureForError (), Operator.GetName (matching_type));
                                }
                        }

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

                                if (!HasGetHashCode)
                                        Report.Warning (661, 2, Location, "`{0}' defines operator == or operator != but does not override Object.GetHashCode()",
                                                GetSignatureForError ());
                        }
                }

                public override void CreateMetadataName (StringBuilder sb)
                {
                        if (Parent.MemberName != null) {
                                Parent.CreateMetadataName (sb);

                                if (sb.Length != 0) {
                                        sb.Append (".");
                                }
                        }

                        sb.Append (MemberName.Basename);
                }
        
                bool CreateTypeBuilder ()
                {
                        //
                        // Sets .size to 1 for structs with no instance fields
                        //
                        int type_size = Kind == MemberKind.Struct && first_nonstatic_field == null && !(this is StateMachine) ? 1 : 0;

                        var parent_def = Parent as TypeDefinition;
                        if (parent_def == null) {
                                var sb = new StringBuilder ();
                                CreateMetadataName (sb);
                                TypeBuilder = Module.CreateBuilder (sb.ToString (), TypeAttr, type_size);
                        } else {
                                TypeBuilder = parent_def.TypeBuilder.DefineNestedType (MemberName.Basename, TypeAttr, null, type_size);
                        }

                        if (DeclaringAssembly.Importer != null)
                                DeclaringAssembly.Importer.AddCompiledType (TypeBuilder, spec);

                        spec.SetMetaInfo (TypeBuilder);
                        spec.MemberCache = new MemberCache (this);

                        TypeParameters parentAllTypeParameters = null;
                        if (parent_def != null) {
                                spec.DeclaringType = Parent.CurrentType;
                                parent_def.MemberCache.AddMember (spec);
                                parentAllTypeParameters = parent_def.all_type_parameters;
                        }

                        if (MemberName.TypeParameters != null || parentAllTypeParameters != null) {
                                var tparam_names = CreateTypeParameters (parentAllTypeParameters);

                                all_tp_builders = TypeBuilder.DefineGenericParameters (tparam_names);

                                if (CurrentTypeParameters != null) {
                                        CurrentTypeParameters.Create (spec, CurrentTypeParametersStartIndex, this);
                                        CurrentTypeParameters.Define (all_tp_builders);
                                }
                        }

                        return true;
                }

                string[] CreateTypeParameters (TypeParameters parentAllTypeParameters)
                {
                        string[] names;
                        int parent_offset = 0;
                        if (parentAllTypeParameters != null) {
                                if (CurrentTypeParameters == null) {
                                        all_type_parameters = parentAllTypeParameters;
                                        return parentAllTypeParameters.GetAllNames ();
                                }

                                names = new string[parentAllTypeParameters.Count + CurrentTypeParameters.Count];
                                all_type_parameters = new TypeParameters (names.Length);
                                all_type_parameters.Add (parentAllTypeParameters);

                                parent_offset = all_type_parameters.Count;
                                for (int i = 0; i < parent_offset; ++i)
                                        names[i] = all_type_parameters[i].MemberName.Name;

                        } else {
                                names = new string[CurrentTypeParameters.Count];
                        }

                        for (int i = 0; i < CurrentTypeParameters.Count; ++i) {
                                if (all_type_parameters != null)
                                        all_type_parameters.Add (MemberName.TypeParameters[i]);

                                var name = CurrentTypeParameters[i].MemberName.Name;
                                names[parent_offset + i] = name;
                                for (int ii = 0; ii < parent_offset + i; ++ii) {
                                        if (names[ii] != name)
                                                continue;

                                        var tp = CurrentTypeParameters[i];
                                        var conflict = all_type_parameters[ii];

                                        tp.WarningParentNameConflict (conflict);
                                }
                        }

                        if (all_type_parameters == null)
                                all_type_parameters = CurrentTypeParameters;

                        return names;
                }


                public SourceMethodBuilder CreateMethodSymbolEntry ()
                {
                        if (Module.DeclaringAssembly.SymbolWriter == null || (ModFlags & Modifiers.DEBUGGER_HIDDEN) != 0)
                                return null;

                        var source_file = GetCompilationSourceFile ();
                        if (source_file == null)
                                return null;

                        return new SourceMethodBuilder (source_file.SymbolUnitEntry);
                }

                //
                // Creates a proxy base method call inside this container for hoisted base member calls
                //
                public MethodSpec CreateHoistedBaseCallProxy (ResolveContext rc, MethodSpec method)
                {
                        Method proxy_method;

                        //
                        // One proxy per base method is enough
                        //
                        if (hoisted_base_call_proxies == null) {
                                hoisted_base_call_proxies = new Dictionary<MethodSpec, Method> ();
                                proxy_method = null;
                        } else {
                                hoisted_base_call_proxies.TryGetValue (method, out proxy_method);
                        }

                        if (proxy_method == null) {
                                string name = CompilerGeneratedContainer.MakeName (method.Name, null, "BaseCallProxy", hoisted_base_call_proxies.Count);

                                MemberName member_name;
                                TypeArguments targs = null;
                                TypeSpec return_type = method.ReturnType;
                                var local_param_types = method.Parameters.Types;

                                if (method.IsGeneric) {
                                        //
                                        // Copy all base generic method type parameters info
                                        //
                                        var hoisted_tparams = method.GenericDefinition.TypeParameters;
                                        var tparams = new TypeParameters ();

                                        targs = new TypeArguments ();
                                        targs.Arguments = new TypeSpec[hoisted_tparams.Length];
                                        for (int i = 0; i < hoisted_tparams.Length; ++i) {
                                                var tp = hoisted_tparams[i];
                                                var local_tp = new TypeParameter (tp, null, new MemberName (tp.Name, Location), null);
                                                tparams.Add (local_tp);

                                                targs.Add (new SimpleName (tp.Name, Location));
                                                targs.Arguments[i] = local_tp.Type;
                                        }

                                        member_name = new MemberName (name, tparams, Location);

                                        //
                                        // Mutate any method type parameters from original
                                        // to newly created hoisted version
                                        //
                                        var mutator = new TypeParameterMutator (hoisted_tparams, tparams);
                                        return_type = mutator.Mutate (return_type);
                                        local_param_types = mutator.Mutate (local_param_types);
                                } else {
                                        member_name = new MemberName (name);
                                }

                                var base_parameters = new Parameter[method.Parameters.Count];
                                for (int i = 0; i < base_parameters.Length; ++i) {
                                        var base_param = method.Parameters.FixedParameters[i];
                                        base_parameters[i] = new Parameter (new TypeExpression (local_param_types [i], Location),
                                                base_param.Name, base_param.ModFlags, null, Location);
                                        base_parameters[i].Resolve (this, i);
                                }

                                var cloned_params = ParametersCompiled.CreateFullyResolved (base_parameters, method.Parameters.Types);
                                if (method.Parameters.HasArglist) {
                                        cloned_params.FixedParameters[0] = new Parameter (null, "__arglist", Parameter.Modifier.NONE, null, Location);
                                        cloned_params.Types[0] = Module.PredefinedTypes.RuntimeArgumentHandle.Resolve ();
                                }

                                // Compiler generated proxy
                                proxy_method = new Method (this, new TypeExpression (return_type, Location),
                                        Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED | Modifiers.DEBUGGER_HIDDEN,
                                        member_name, cloned_params, null);

                                var block = new ToplevelBlock (Compiler, proxy_method.ParameterInfo, Location) {
                                        IsCompilerGenerated = true
                                };

                                var mg = MethodGroupExpr.CreatePredefined (method, method.DeclaringType, Location);
                                mg.InstanceExpression = new BaseThis (method.DeclaringType, Location);
                                if (targs != null)
                                        mg.SetTypeArguments (rc, targs);

                                // Get all the method parameters and pass them as arguments
                                var real_base_call = new Invocation (mg, block.GetAllParametersArguments ());
                                Statement statement;
                                if (method.ReturnType.Kind == MemberKind.Void)
                                        statement = new StatementExpression (real_base_call);
                                else
                                        statement = new Return (real_base_call, Location);

                                block.AddStatement (statement);
                                proxy_method.Block = block;

                                members.Add (proxy_method);
                                proxy_method.Define ();
                                proxy_method.PrepareEmit ();

                                hoisted_base_call_proxies.Add (method, proxy_method);
                        }

                        return proxy_method.Spec;
                }

                protected bool DefineBaseTypes ()
                {
                        if (IsPartialPart && Kind == MemberKind.Class)
                                return true;

                        return DoDefineBaseType ();
                }

                bool DoDefineBaseType ()
                {
                        iface_exprs = ResolveBaseTypes (out base_type_expr);
                        bool set_base_type;

                        if (IsPartialPart) {
                                set_base_type = false;

                                if (base_type_expr != null) {
                                        if (PartialContainer.base_type_expr != null && PartialContainer.base_type != base_type) {
                                                Report.SymbolRelatedToPreviousError (base_type_expr.Location, "");
                                                Report.Error (263, Location,
                                                        "Partial declarations of `{0}' must not specify different base classes",
                                                        GetSignatureForError ());
                                        } else {
                                                PartialContainer.base_type_expr = base_type_expr;
                                                PartialContainer.base_type = base_type;
                                                set_base_type = true;
                                        }
                                }

                                if (iface_exprs != null) {
                                        if (PartialContainer.iface_exprs == null)
                                                PartialContainer.iface_exprs = iface_exprs;
                                        else {
                                                var ifaces = new List<TypeSpec> (PartialContainer.iface_exprs);
                                                foreach (var iface_partial in iface_exprs) {
                                                        if (ifaces.Contains (iface_partial))
                                                                continue;

                                                        ifaces.Add (iface_partial);
                                                }

                                                PartialContainer.iface_exprs = ifaces.ToArray ();
                                        }
                                }

                                PartialContainer.members.AddRange (members);
                                if (containers != null) {
                                        if (PartialContainer.containers == null)
                                                PartialContainer.containers = new List<TypeContainer> ();

                                        PartialContainer.containers.AddRange (containers);
                                }

                                if (PrimaryConstructorParameters != null) {
                                        if (PartialContainer.PrimaryConstructorParameters != null) {
                                                Report.Error (8036, Location, "Only one part of a partial type can declare primary constructor parameters");
                                        } else {
                                                PartialContainer.PrimaryConstructorParameters = PrimaryConstructorParameters;
                                        }
                                }

                                members_defined = members_defined_ok = true;
                                caching_flags |= Flags.CloseTypeCreated;
                        } else {
                                set_base_type = true;
                        }

                        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 ());

                                        iface_exprs = null;
                                        PartialContainer.iface_exprs = null;
                                } else {
                                        Report.Error (146, Location,
                                                "Circular base class dependency involving `{0}' and `{1}'",
                                                GetSignatureForError (), cycle.GetSignatureForError ());

                                        base_type = null;
                                        PartialContainer.base_type = null;
                                }
                        }

                        if (iface_exprs != null) {
                                if (!PrimaryConstructorBaseArgumentsStart.IsNull) {
                                        Report.Error (8049, PrimaryConstructorBaseArgumentsStart, "Implemented interfaces cannot have arguments");
                                }

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

                                        TypeBuilder.AddInterfaceImplementation (iface_type.GetMetaInfo ());
                                }
                        }

                        if (Kind == MemberKind.Interface) {
                                spec.BaseType = Compiler.BuiltinTypes.Object;
                                return true;
                        }

                        if (set_base_type) {
                                SetBaseType ();
                        }

                        //
                        // Base type of partial container has to be resolved before we
                        // resolve any nested types of the container. We need to know
                        // partial parts because the base type can be specified in file
                        // defined after current container
                        //
                        if (class_partial_parts != null) {
                                foreach (var pp in class_partial_parts) {
                                        if (pp.PrimaryConstructorBaseArguments != null)
                                                PrimaryConstructorBaseArguments = pp.PrimaryConstructorBaseArguments;

                                        pp.DoDefineBaseType ();
                                }

                        }

                        return true;
                }

                void SetBaseType ()
                {
                        if (base_type == null) {
                                TypeBuilder.SetParent (null);
                                return;
                        }

                        if (spec.BaseType == base_type)
                                return;

                        spec.BaseType = base_type;

                        if (IsPartialPart)
                                spec.UpdateInflatedInstancesBaseType ();

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

                public override void ExpandBaseInterfaces ()
                {
                        if (!IsPartialPart)
                                DoExpandBaseInterfaces ();

                        base.ExpandBaseInterfaces ();
                }

                public void DoExpandBaseInterfaces ()
                {
                        if ((caching_flags & Flags.InterfacesExpanded) != 0)
                                return;

                        caching_flags |= Flags.InterfacesExpanded;

                        //
                        // Expand base interfaces. It cannot be done earlier because all partial
                        // interface parts need to be defined before the type they are used from
                        //
                        if (iface_exprs != null) {
                                foreach (var iface in iface_exprs) {
                                        if (iface == null)
                                                continue;

                                        var td = iface.MemberDefinition as TypeDefinition;
                                        if (td != null)
                                                td.DoExpandBaseInterfaces ();

                                        if (iface.Interfaces == null)
                                                continue;

                                        foreach (var biface in iface.Interfaces) {
                                                if (spec.AddInterfaceDefined (biface)) {
                                                        TypeBuilder.AddInterfaceImplementation (biface.GetMetaInfo ());
                                                }
                                        }
                                }
                        }

                        //
                        // Include all base type interfaces too, see ImportTypeBase for details
                        //
                        if (base_type != null) {
                                var td = base_type.MemberDefinition as TypeDefinition;
                                if (td != null)
                                        td.DoExpandBaseInterfaces ();

                                //
                                // Simply use base interfaces only, they are all expanded which makes
                                // it easy to handle generic type argument propagation with single
                                // inflator only.
                                //
                                // interface IA<T> : IB<T>
                                // interface IB<U> : IC<U>
                                // interface IC<V>
                                //
                                if (base_type.Interfaces != null) {
                                        foreach (var iface in base_type.Interfaces) {
                                                spec.AddInterfaceDefined (iface);
                                        }
                                }
                        }
                }

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

                        foreach (var member in members) {
                                var pbm = member as PropertyBasedMember;
                                if (pbm != null)
                                        pbm.PrepareEmit ();

                                var pm = member as IParametersMember;
                                if (pm != null) {
                                        var mc = member as MethodOrOperator;
                                        if (mc != null) {
                                                mc.PrepareEmit ();
                                        }

                                        var p = pm.Parameters;
                                        if (p.IsEmpty)
                                                continue;

                                        ((ParametersCompiled) p).ResolveDefaultValues (member);
                                        continue;
                                }

                                var c = member as Const;
                                if (c != null)
                                        c.DefineValue ();
                        }

                        base.PrepareEmit ();
                }

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

                        if (error)
                                return false;

                        if (IsPartialPart) {
                                spec = PartialContainer.spec;
                                TypeBuilder = PartialContainer.TypeBuilder;
                                all_tp_builders = PartialContainer.all_tp_builders;
                                all_type_parameters = PartialContainer.all_type_parameters;
                        } else {
                                if (!CreateTypeBuilder ()) {
                                        error = true;
                                        return false;
                                }
                        }

                        return base.CreateContainer ();
                }

                protected override void DoDefineContainer ()
                {
                        DefineBaseTypes ();

                        DoResolveTypeParameters ();
                }

                //
                // Replaces normal spec with predefined one when compiling corlib
                // and this type container defines predefined type
                //
                public void SetPredefinedSpec (BuiltinTypeSpec spec)
                {
                        // When compiling build-in types we start with two
                        // version of same type. One is of BuiltinTypeSpec and
                        // second one is ordinary TypeSpec. The unification
                        // happens at later stage when we know which type
                        // really matches the builtin type signature. However
                        // that means TypeSpec create during CreateType of this
                        // type has to be replaced with builtin one
                        // 
                        spec.SetMetaInfo (TypeBuilder);
                        spec.MemberCache = this.spec.MemberCache;
                        spec.DeclaringType = this.spec.DeclaringType;

                        this.spec = spec;
                        current_type = null;
                }

                public override void RemoveContainer (TypeContainer cont)
                {
                        base.RemoveContainer (cont);
                        Members.Remove (cont);
                        Cache.Remove (cont.MemberName.Basename);
                }

                protected virtual bool DoResolveTypeParameters ()
                {
                        var tparams = MemberName.TypeParameters;
                        if (tparams == null)
                                return true;

                        var base_context = new BaseContext (this);
                        for (int i = 0; i < tparams.Count; ++i) {
                                var tp = tparams[i];

                                if (!tp.ResolveConstraints (base_context)) {
                                        error = true;
                                        return false;
                                }

                                if (IsPartialPart) {
                                        var pc_tp = PartialContainer.CurrentTypeParameters [i];

                                        tp.Create (spec, this);
                                        tp.Define (pc_tp);

                                        if (tp.OptAttributes != null) {
                                                if (pc_tp.OptAttributes == null)
                                                        pc_tp.OptAttributes = tp.OptAttributes;
                                                else
                                                        pc_tp.OptAttributes.Attrs.AddRange (tp.OptAttributes.Attrs);
                                        }
                                }
                        }

                        if (IsPartialPart) {
                                PartialContainer.CurrentTypeParameters.UpdateConstraints (this);
                        }

                        return true;
                }

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

                        InTransit = tc;

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

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

                        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;

                        base.Define ();

                        return members_defined_ok;
                }

                protected virtual bool DoDefineMembers ()
                {
                        Debug.Assert (!IsPartialPart);

                        if (iface_exprs != null) {
                                foreach (var iface_type in iface_exprs) {
                                        if (iface_type == null)
                                                continue;

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

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

                                        if (iface_type.Arity > 0) {
                                                // TODO: passing `this' is wrong, should be base type iface instead
                                                VarianceDecl.CheckTypeVariance (iface_type, Variance.Covariant, this);

                                                if (((InflatedTypeSpec) iface_type).HasDynamicArgument () && !IsCompilerGenerated) {
                                                        Report.Error (1966, Location,
                                                                "`{0}': cannot implement a dynamic interface `{1}'",
                                                                GetSignatureForError (), iface_type.GetSignatureForError ());
                                                        return false;
                                                }
                                        }

                                        if (iface_type.IsGenericOrParentIsGeneric) {
                                                foreach (var prev_iface in iface_exprs) {
                                                        if (prev_iface == iface_type || prev_iface == null)
                                                                break;

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

                                if (Kind == MemberKind.Interface) {
                                        foreach (var iface in spec.Interfaces) {
                                                MemberCache.AddInterface (iface);
                                        }
                                }
                        }

                        if (base_type != null) {
                                //
                                // Run checks skipped during DefineType (e.g FullNamedExpression::ResolveAsType)
                                //
                                if (base_type_expr != null) {
                                        ObsoleteAttribute obsolete_attr = base_type.GetAttributeObsolete ();
                                        if (obsolete_attr != null && !IsObsolete)
                                                AttributeTester.Report_ObsoleteMessage (obsolete_attr, base_type.GetSignatureForError (), base_type_expr.Location, Report);

                                        if (IsGenericOrParentIsGeneric && base_type.IsAttribute) {
                                                Report.Error (698, base_type_expr.Location,
                                                        "A generic type cannot derive from `{0}' because it is an attribute class",
                                                        base_type.GetSignatureForError ());
                                        }
                                }

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

                        var count = members.Count;              
                        for (int i = 0; i < count; ++i) {
                                var mc = members[i] as InterfaceMemberBase;
                                if (mc == null || !mc.IsExplicitImpl)
                                        continue;

                                try {
                                        mc.Define ();
                                } catch (Exception e) {
                                        throw new InternalErrorException (mc, e);
                                }
                        }

                        for (int i = 0; i < count; ++i) {
                                var mc = members[i] as InterfaceMemberBase;
                                if (mc != null && mc.IsExplicitImpl)
                                        continue;

                                if (members[i] is TypeContainer)
                                        continue;

                                try {
                                        members[i].Define ();
                                } catch (Exception e) {
                                        throw new InternalErrorException (members[i], e);
                                }
                        }

                        if (HasOperators) {
                                CheckPairedOperators ();
                        }

                        if (requires_delayed_unmanagedtype_check) {
                                requires_delayed_unmanagedtype_check = false;
                                foreach (var member in members) {
                                        var f = member as Field;
                                        if (f != null && f.MemberType != null && f.MemberType.IsPointer)
                                                TypeManager.VerifyUnmanaged (Module, f.MemberType, f.Location);
                                }
                        }

                        ComputeIndexerName();

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

                        if (Kind == MemberKind.Interface && iface_exprs != null) {
                                MemberCache.RemoveHiddenMembers (spec);
                        }

                        return true;
                }

                void ComputeIndexerName ()
                {
                        var indexers = MemberCache.FindMembers (spec, MemberCache.IndexerNameAlias, true);
                        if (indexers == null)
                                return;

                        string class_indexer_name = null;

                        //
                        // Check normal indexers for consistent name, explicit interface implementation
                        // indexers are ignored
                        //
                        foreach (var indexer in indexers) {
                                //
                                // FindMembers can return unfiltered full hierarchy names
                                //
                                if (indexer.DeclaringType != spec)
                                        continue;

                                has_normal_indexers = true;

                                if (class_indexer_name == null) {
                                        indexer_name = class_indexer_name = indexer.Name;
                                        continue;
                                }

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

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

                        var ctor = Module.PredefinedMembers.DefaultMemberAttributeCtor.Get ();
                        if (ctor == null)
                                return;

                        var encoder = new AttributeEncoder ();
                        encoder.Encode (GetAttributeDefaultMember ());
                        encoder.EncodeEmptyNamedArguments ();

                        TypeBuilder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray ());
                }

                public override void VerifyMembers ()
                {
                        //
                        // Check for internal or private fields that were never assigned
                        //
                        if (!IsCompilerGenerated && Compiler.Settings.WarningLevel >= 3 && this == PartialContainer) {
                                bool is_type_exposed = Kind == MemberKind.Struct || IsExposedFromAssembly ();
                                foreach (var member in members) {
                                        if (member is Event) {
                                                //
                                                // An event can be assigned from same class only, report
                                                // this warning for all accessibility modes
                                                //
                                                if (!member.IsUsed && !PartialContainer.HasStructLayout)
                                                        Report.Warning (67, 3, member.Location, "The event `{0}' is never used", member.GetSignatureForError ());

                                                continue;
                                        }

                                        if ((member.ModFlags & Modifiers.AccessibilityMask) != Modifiers.PRIVATE) {
                                                if (is_type_exposed)
                                                        continue;

                                                member.SetIsUsed ();
                                        }

                                        var f = member as Field;
                                        if (f == null)
                                                continue;

                                        if (!member.IsUsed) {
                                                if (!PartialContainer.HasStructLayout) {
                                                        if ((member.caching_flags & Flags.IsAssigned) == 0) {
                                                                Report.Warning (169, 3, member.Location, "The private field `{0}' is never used", member.GetSignatureForError ());
                                                        } else {
                                                                Report.Warning (414, 3, member.Location, "The private field `{0}' is assigned but its value is never used",
                                                                        member.GetSignatureForError ());
                                                        }
                                                }

                                                continue;
                                        }

                                        if ((f.caching_flags & Flags.IsAssigned) != 0)
                                                continue;

                                        //
                                        // Only report 649 on level 4
                                        //
                                        if (Compiler.Settings.WarningLevel < 4)
                                                continue;

                                        //
                                        // Don't be pedantic when type requires specific layout
                                        //
                                        if (f.OptAttributes != null || PartialContainer.HasStructLayout)
                                                continue;

                                        Constant c = New.Constantify (f.MemberType, f.Location);
                                        string value;
                                        if (c != null) {
                                                value = c.GetValueAsLiteral ();
                                        } else if (TypeSpec.IsReferenceType (f.MemberType)) {
                                                value = "null";
                                        } else {
                                                value = null;
                                        }

                                        if (value != null)
                                                value = " `" + value + "'";

                                        Report.Warning (649, 4, f.Location, "Field `{0}' is never assigned to, and will always have its default value{1}",
                                                f.GetSignatureForError (), value);
                                }
                        }

                        base.VerifyMembers ();
                }

                public override void Emit ()
                {
                        if (OptAttributes != null)
                                OptAttributes.Emit ();

                        if (!IsCompilerGenerated) {
                                if (!IsTopLevel) {
                                        MemberSpec candidate;
                                        bool overrides = false;
                                        var conflict_symbol = MemberCache.FindBaseMember (this, out candidate, ref overrides);
                                        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 ());
                                                }
                                        }
                                }

                                // Run constraints check on all possible generic types
                                if (base_type != null && base_type_expr != null) {
                                        ConstraintChecker.Check (this, base_type, base_type_expr.Location);
                                }

                                if (iface_exprs != null) {
                                        foreach (var iface_type in iface_exprs) {
                                                if (iface_type == null)
                                                        continue;

                                                ConstraintChecker.Check (this, iface_type, Location);   // TODO: Location is wrong
                                        }
                                }
                        }

                        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) {
                                                all_type_parameters[i].EmitConstraints (all_tp_builders [i]);
                                        } else {
                                                var tp = CurrentTypeParameters [i - current_starts_index];
                                                tp.CheckGenericConstraints (!IsObsolete);
                                                tp.Emit ();
                                        }
                                }
                        }

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

#if STATIC
                        if ((TypeBuilder.Attributes & TypeAttributes.StringFormatMask) == 0 && Module.HasDefaultCharSet)
                                TypeBuilder.__SetAttributes (TypeBuilder.Attributes | Module.DefaultCharSetType);
#endif

                        base.Emit ();

                        for (int i = 0; i < members.Count; i++) {
                                var m = members[i];
                                if ((m.caching_flags & Flags.CloseTypeCreated) != 0)
                                        continue;

                                m.Emit ();
                        }

                        EmitIndexerName ();
                        CheckAttributeClsCompliance ();

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


                void CheckAttributeClsCompliance ()
                {
                        if (!spec.IsAttribute || !IsExposedFromAssembly () || !Compiler.Settings.VerifyClsCompliance || !IsClsComplianceRequired ())
                                return;

                        foreach (var m in members) {
                                var c = m as Constructor;
                                if (c == null)
                                        continue;

                                if (c.HasCompliantArgs)
                                        return;
                        }

                        Report.Warning (3015, 1, Location, "`{0}' has no accessible constructors which use only CLS-compliant types", GetSignatureForError ());
                }

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

                        Emit ();
                }

                public override void CloseContainer ()
                {
                        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.CloseContainer ();

                                        if ((caching_flags & Flags.CloseTypeCreated) != 0)
                                                return;
                                }
                        }

                        try {
                                caching_flags |= Flags.CloseTypeCreated;
                                TypeBuilder.CreateType ();
                        } catch (TypeLoadException) {
                                //
                                // This is fine, the code still created the type
                                //
                        } catch (Exception e) {
                                throw new InternalErrorException (this, e);
                        }

                        base.CloseContainer ();
                        
                        containers = null;
                        initialized_fields = null;
                        initialized_static_fields = null;
                        type_bases = null;
                        OptAttributes = null;
                }

                //
                // Performs the validation on a Method's modifiers (properties have
                // the same properties).
                //
                // TODO: Why is it not done at parse stage, move to Modifiers::Check
                //
                public bool MethodModifiersValid (MemberCore mc)
                {
                        const Modifiers vao = (Modifiers.VIRTUAL | Modifiers.ABSTRACT | Modifiers.OVERRIDE);
                        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 ((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;
                }

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

                        // 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 = PartialContainer.Interfaces;
                        if (ifaces != null) {
                                foreach (TypeSpec t in ifaces){
                                        if (t == mb.InterfaceType)
                                                return true;

                                        var expanded_base = t.Interfaces;
                                        if (expanded_base == null)
                                                continue;

                                        foreach (var bt in expanded_base) {
                                                if (bt == mb.InterfaceType)
                                                        return true;
                                        }
                                }
                        }
                        
                        Report.SymbolRelatedToPreviousError (mb.InterfaceType);
                        Report.Error (540, mb.Location, "`{0}': containing type does not implement interface `{1}'",
                                mb.GetSignatureForError (), mb.InterfaceType.GetSignatureForError ());
                        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 override bool IsClsComplianceRequired ()
                {
                        if (IsPartialPart)
                                return PartialContainer.IsClsComplianceRequired ();

                        return base.IsClsComplianceRequired ();
                }

                bool ITypeDefinition.IsInternalAsPublic (IAssemblyDefinition assembly)
                {
                        return Module.DeclaringAssembly == assembly;
                }

                public virtual bool IsUnmanagedType ()
                {
                        return false;
                }

                public void LoadMembers (TypeSpec declaringType, bool onlyTypes, ref MemberCache cache)
                {
                        throw new NotSupportedException ("Not supported for compiled definition " + GetSignatureForError ());
                }

                //
                // Public function used to locate types.
                //
                // Returns: Type or null if they type can not be found.
                //
                public override FullNamedExpression LookupNamespaceOrType (string name, int arity, LookupMode mode, Location loc)
                {
                        FullNamedExpression e;
                        if (arity == 0 && Cache.TryGetValue (name, out e) && mode != LookupMode.IgnoreAccessibility)
                                return e;

                        e = null;

                        if (arity == 0) {
                                var tp = CurrentTypeParameters;
                                if (tp != null) {
                                        TypeParameter tparam = tp.Find (name);
                                        if (tparam != null)
                                                e = new TypeParameterExpr (tparam, Location.Null);
                                }
                        }

                        if (e == null) {
                                TypeSpec t = LookupNestedTypeInHierarchy (name, arity);

                                if (t != null && (t.IsAccessible (this) || mode == LookupMode.IgnoreAccessibility))
                                        e = new TypeExpression (t, Location.Null);
                                else {
                                        var errors = Compiler.Report.Errors;
                                        e = Parent.LookupNamespaceOrType (name, arity, mode, loc);

                                        // TODO: LookupNamespaceOrType does more than just lookup. The result
                                        // cannot be cached or the error reporting won't happen
                                        if (errors != Compiler.Report.Errors)
                                                return e;
                                }
                        }

                        // TODO MemberCache: How to cache arity stuff ?
                        if (arity == 0 && mode == LookupMode.Normal)
                                Cache[name] = e;

                        return e;
                }

                TypeSpec LookupNestedTypeInHierarchy (string name, int arity)
                {
                        // Has any nested type
                        // Does not work, because base type can have
                        //if (PartialContainer.Types == null)
                        //      return null;

                        var container = PartialContainer.CurrentType;
                        return MemberCache.FindNestedType (container, name, arity);
                }

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

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

                public override void WriteDebugSymbol (MonoSymbolFile file)
                {
                        if (IsPartialPart)
                                return;

                        foreach (var m in members) {
                                m.WriteDebugSymbol (file);
                        }
                }

                /// <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;
                        }
                }

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

        public abstract class ClassOrStruct : TypeDefinition
        {
                public const TypeAttributes StaticClassAttribute = TypeAttributes.Abstract | TypeAttributes.Sealed;

                SecurityType declarative_security;
                protected Constructor generated_primary_constructor;

                protected ClassOrStruct (TypeContainer parent, MemberName name, Attributes attrs, MemberKind kind)
                        : base (parent, name, attrs, kind)
                {
                }

                public ToplevelBlock PrimaryConstructorBlock { get; set; }

                protected override TypeAttributes TypeAttr {
                        get {
                                TypeAttributes ta = base.TypeAttr;
                                if (!has_static_constructor)
                                        ta |= TypeAttributes.BeforeFieldInit;

                                if (Kind == MemberKind.Class) {
                                        ta |= TypeAttributes.AutoLayout | TypeAttributes.Class;
                                        if (IsStatic)
                                                ta |= StaticClassAttribute;
                                } else {
                                        ta |= TypeAttributes.SequentialLayout;
                                }

                                return ta;
                        }
                }

                public override void AddNameToContainer (MemberCore symbol, string name)
                {
                        if (!(symbol is Constructor) && symbol.MemberName.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;
                                }

                                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;
                                }
                        }

                        base.AddNameToContainer (symbol, name);
                }

                public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
                {
                        if (a.IsValidSecurityAttribute ()) {
                                a.ExtractSecurityPermissionSet (ctor, ref declarative_security);
                                return;
                        }

                        if (a.Type == pa.StructLayout) {
                                PartialContainer.HasStructLayout = true;
                                if (a.IsExplicitLayoutKind ())
                                        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 virtual Constructor 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;
                        ParametersCompiled parameters = null;
                        if (is_static) {
                                mods = Modifiers.STATIC | Modifiers.PRIVATE;
                                parameters = ParametersCompiled.EmptyReadOnlyParameters;
                        } else {
                                mods = ((ModFlags & Modifiers.ABSTRACT) != 0) ? Modifiers.PROTECTED : Modifiers.PUBLIC;
                                parameters = PrimaryConstructorParameters ?? ParametersCompiled.EmptyReadOnlyParameters;
                        }

                        var c = new Constructor (this, MemberName.Name, mods, null, parameters, Location);
                        if (Kind == MemberKind.Class)
                                c.Initializer = new GeneratedBaseInitializer (Location, PrimaryConstructorBaseArguments);

                        if (PrimaryConstructorParameters != null && !is_static) {
                                c.IsPrimaryConstructor = true;
                                c.caching_flags |= Flags.MethodOverloadsExist;
                        }
                        
                        AddConstructor (c, true);
                        if (PrimaryConstructorBlock == null) {
                                c.Block = new ToplevelBlock (Compiler, parameters, Location) {
                                        IsCompilerGenerated = true
                                };
                        } else {
                                c.Block = PrimaryConstructorBlock;
                        }

                        return c;
                }

                protected override bool DoDefineMembers ()
                {
                        CheckProtectedModifier ();

                        if (PrimaryConstructorParameters != null) {

                                foreach (Parameter p in PrimaryConstructorParameters.FixedParameters) {
                                        if (p.Name == MemberName.Name) {
                                                Report.Error (8039, p.Location, "Primary constructor of type `{0}' has parameter of same name as containing type",
                                                        GetSignatureForError ());
                                        }

                                        if (CurrentTypeParameters != null) {
                                                for (int i = 0; i < CurrentTypeParameters.Count; ++i) {
                                                        var tp = CurrentTypeParameters [i];
                                                        if (p.Name == tp.Name) {
                                                                Report.Error (8038, p.Location, "Primary constructor of type `{0}' has parameter of same name as type parameter `{1}'",
                                                                        GetSignatureForError (), p.GetSignatureForError ());
                                                        }
                                                }
                                        }
                                }
                        }

                        base.DoDefineMembers ();

                        return true;
                }

                public override void Emit ()
                {
                        if (!has_static_constructor && HasStaticFieldInitializer) {
                                var c = DefineDefaultConstructor (true);
                                c.Define ();
                        }

                        base.Emit ();

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


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

                public override void Accept (StructuralVisitor visitor)
                {
                        visitor.Visit (this);
                }

                public override void SetBaseTypes (List<FullNamedExpression> baseTypes)
                {
                        var pmn = MemberName;
                        if (pmn.Name == "Object" && !pmn.IsGeneric && Parent.MemberName.Name == "System" && Parent.MemberName.Left == null)
                                Report.Error (537, Location,
                                        "The class System.Object cannot have a base class or implement an interface.");

                        base.SetBaseTypes (baseTypes);
                }

                public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
                {
                        if (a.Type == pa.AttributeUsage) {
                                if (!BaseType.IsAttribute && spec.BuiltinType != BuiltinTypeSpec.Type.Attribute) {
                                        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 (this))
                                return;

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

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

                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 (IsStatic) {
                                if (PrimaryConstructorParameters != null) {
                                        Report.Error (-800, Location, "`{0}': Static classes cannot have primary constructor", GetSignatureForError ());
                                        PrimaryConstructorParameters = null;
                                }

                                foreach (var m in Members) {
                                        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 TypeContainer)
                                                continue;

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

                                        Report.Error (708, m.Location, "`{0}': cannot declare instance members in a static class", m.GetSignatureForError ());
                                }
                        } else {
                                if (!PartialContainer.HasInstanceConstructor || PrimaryConstructorParameters != null)
                                        generated_primary_constructor = DefineDefaultConstructor (false);
                        }

                        return base.DoDefineMembers ();
                }

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

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

                        if (base_type != null && base_type.HasDynamicElement) {
                                Module.PredefinedAttributes.Dynamic.EmitAttribute (TypeBuilder, base_type, Location);
                        }
                }

                public override void GetCompletionStartingWith (string prefix, List<string> results)
                {
                        base.GetCompletionStartingWith (prefix, results);

                        var bt = base_type;
                        while (bt != null) {
                                results.AddRange (MemberCache.GetCompletitionMembers (this, bt, prefix).Where (l => l.IsStatic).Select (l => l.Name));
                                bt = bt.BaseType;
                        }
                }

                protected override TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
                {
                        var ifaces = base.ResolveBaseTypes (out base_class);

                        if (base_class == null) {
                                if (spec.BuiltinType != BuiltinTypeSpec.Type.Object)
                                        base_type = Compiler.BuiltinTypes.Object;
                        } else {
                                if (base_type.IsGenericParameter){
                                        Report.Error (689, base_class.Location, "`{0}': Cannot derive from type parameter `{1}'",
                                                GetSignatureForError (), base_type.GetSignatureForError ());
                                } else if (base_type.IsStatic) {
                                        Report.SymbolRelatedToPreviousError (base_type);
                                        Report.Error (709, Location, "`{0}': Cannot derive from static class `{1}'",
                                                GetSignatureForError (), base_type.GetSignatureForError ());
                                } else if (base_type.IsSealed) {
                                        Report.SymbolRelatedToPreviousError (base_type);
                                        Report.Error (509, Location, "`{0}': cannot derive from sealed type `{1}'",
                                                GetSignatureForError (), base_type.GetSignatureForError ());
                                } else if (PartialContainer.IsStatic && base_type.BuiltinType != BuiltinTypeSpec.Type.Object) {
                                        Report.Error (713, Location, "Static class `{0}' cannot derive from type `{1}'. Static classes must derive from object",
                                                GetSignatureForError (), base_type.GetSignatureForError ());
                                }

                                switch (base_type.BuiltinType) {
                                case BuiltinTypeSpec.Type.Enum:
                                case BuiltinTypeSpec.Type.ValueType:
                                case BuiltinTypeSpec.Type.MulticastDelegate:
                                case BuiltinTypeSpec.Type.Delegate:
                                case BuiltinTypeSpec.Type.Array:
                                        if (!(spec is BuiltinTypeSpec)) {
                                                Report.Error (644, Location, "`{0}' cannot derive from special class `{1}'",
                                                        GetSignatureForError (), base_type.GetSignatureForError ());

                                                base_type = Compiler.BuiltinTypes.Object;
                                        }
                                        break;
                                }

                                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 (var t in ifaces)
                                        Report.SymbolRelatedToPreviousError (t);
                                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 (Module.PredefinedAttributes.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;
                }
        }

        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 (TypeContainer parent, MemberName name, Modifiers mod, Attributes attrs)
                        : base (parent, name, attrs, MemberKind.Struct)
                {
                        var accmods = IsTopLevel ? 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 Accept (StructuralVisitor visitor)
                {
                        visitor.Visit (this);
                }

                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 types
                        //
                        if (a.Type == pa.StructLayout) {
                                var value = a.GetNamedValue ("CharSet");
                                if (value == null)
                                        return;

                                for (int i = 0; i < Members.Count; ++i) {
                                        FixedField ff = Members [i] as FixedField;
                                        if (ff == null)
                                                continue;

                                        ff.CharSet = (CharSet) System.Enum.Parse (typeof (CharSet), value.GetValue ().ToString ());
                                }
                        }
                }

                bool CheckStructCycles ()
                {
                        if (InTransit)
                                return false;

                        InTransit = true;
                        foreach (var member in Members) {
                                var field = member as Field;
                                if (field == null)
                                        continue;

                                TypeSpec ftype = field.Spec.MemberType;
                                if (!ftype.IsStruct)
                                        continue;

                                if (ftype is BuiltinTypeSpec)
                                        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;
                                        }
                                }

                                //
                                // Static fields of exactly same type are allowed
                                //
                                if (field.IsStatic && 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;
                                }
                        }

                        InTransit = false;
                        return true;
                }

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

                        return fts.CheckStructCycles ();
                }

                protected override bool DoDefineMembers ()
                {
                        var res = base.DoDefineMembers ();

                        if (PrimaryConstructorParameters != null || (initialized_fields != null && !HasUserDefaultConstructor ())) {
                                generated_primary_constructor = DefineDefaultConstructor (false);
                                generated_primary_constructor.Define ();
                        }

                        return res;
                }

                public override void Emit ()
                {
                        CheckStructCycles ();

                        base.Emit ();
                }

                bool HasUserDefaultConstructor ()
                {
                        foreach (var m in PartialContainer.Members) {
                                var c = m as Constructor;
                                if (c == null)
                                        continue;

                                if (!c.IsStatic && c.ParameterInfo.IsEmpty)
                                        return true;
                        }

                        return false;
                }

                public override bool IsUnmanagedType ()
                {
                        if (has_unmanaged_check_done)
                                return is_unmanaged;

                        if (requires_delayed_unmanagedtype_check)
                                return true;

                        var parent_def = Parent.PartialContainer;
                        if (parent_def != null && parent_def.IsGenericOrParentIsGeneric) {
                                has_unmanaged_check_done = true;
                                return false;
                        }

                        if (first_nonstatic_field != null) {
                                requires_delayed_unmanagedtype_check = true;

                                foreach (var member in Members) {
                                        var f = member as Field;
                                        if (f == null)
                                                continue;

                                        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;
                                        }

                                        if (mt.IsUnmanaged)
                                                continue;

                                        has_unmanaged_check_done = true;
                                        return false;
                                }

                                has_unmanaged_check_done = true;
                        }

                        is_unmanaged = true;
                        return true;
                }

                protected override TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
                {
                        var ifaces = base.ResolveBaseTypes (out base_class);
                        base_type = Compiler.BuiltinTypes.ValueType;
                        return ifaces;
                }
        }

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

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

                public Interface (TypeContainer parent, MemberName name, Modifiers mod, Attributes attrs)
                        : base (parent, name, attrs, MemberKind.Interface)
                {
                        var accmods = IsTopLevel ? Modifiers.INTERNAL : Modifiers.PRIVATE;

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

                #region Properties

                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;
                        }
                }

                #endregion

                public override void Accept (StructuralVisitor visitor)
                {
                        visitor.Visit (this);
                }

                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);
                }

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

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

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

                        return true;
                }
        }

        public abstract class InterfaceMemberBase : MemberBase
        {
                //
                // Common modifiers allowed in a class declaration
                //
                protected const Modifiers AllowedModifiersClass =
                        Modifiers.NEW |
                        Modifiers.PUBLIC |
                        Modifiers.PROTECTED |
                        Modifiers.INTERNAL |
                        Modifiers.PRIVATE |
                        Modifiers.STATIC |
                        Modifiers.VIRTUAL |
                        Modifiers.SEALED |
                        Modifiers.OVERRIDE |
                        Modifiers.ABSTRACT |
                        Modifiers.UNSAFE |
                        Modifiers.EXTERN;

                //
                // Common modifiers allowed in a struct declaration
                //
                protected const Modifiers AllowedModifiersStruct =
                        Modifiers.NEW |
                        Modifiers.PUBLIC |
                        Modifiers.PROTECTED |
                        Modifiers.INTERNAL |
                        Modifiers.PRIVATE |
                        Modifiers.STATIC |
                        Modifiers.OVERRIDE |
                        Modifiers.UNSAFE |
                        Modifiers.EXTERN;

                //
                // Common modifiers allowed in a interface declaration
                //
                protected const Modifiers AllowedModifiersInterface =
                        Modifiers.NEW |
                        Modifiers.UNSAFE;

                //
                // Whether this is an interface member.
                //
                public bool IsInterface;

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

                protected InterfaceMemberBase (TypeDefinition parent, FullNamedExpression type, Modifiers mod, Modifiers allowed_mod, MemberName name, Attributes attrs)
                        : base (parent, type, mod, allowed_mod, Modifiers.PRIVATE, name, attrs)
                {
                        IsInterface = parent.Kind == MemberKind.Interface;
                        IsExplicitImpl = (MemberName.ExplicitInterface != null);
                        explicit_mod_flags = mod;
                }

                public abstract Variance ExpectedMemberTypeVariance { get; }
                
                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;
                        bool overrides = false;
                        var base_member = FindBaseMember (out candidate, ref overrides);

                        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;
                                }

                                //
                                // Handles ambiguous overrides
                                //
                                if (candidate != null) {
                                        Report.SymbolRelatedToPreviousError (candidate);
                                        Report.SymbolRelatedToPreviousError (base_member);

                                        // Get member definition for error reporting
                                        var m1 = MemberCache.GetMember (base_member.DeclaringType.GetDefinition (), base_member);
                                        var m2 = MemberCache.GetMember (candidate.DeclaringType.GetDefinition (), candidate);

                                        Report.Error (462, Location,
                                                "`{0}' cannot override inherited members `{1}' and `{2}' because they have the same signature when used in type `{3}'",
                                                GetSignatureForError (), m1.GetSignatureForError (), m2.GetSignatureForError (), Parent.GetSignatureForError ());
                                }

                                if (!CheckOverrideAgainstBase (base_member))
                                        return false;

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

                                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;
                                        if (!IsCompilerGenerated) {
                                                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 && !overrides && !IsStatic) {
                                        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)) == 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 (), base_member_type.GetSignatureForError (), base_member.GetSignatureForError ());
                                } else {
                                        Report.Error (508, Location, "`{0}': return type must be `{1}' to match overridden member `{2}'",
                                                GetSignatureForError (), base_member_type.GetSignatureForError (), base_member.GetSignatureForError ());
                                }
                                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)) {
                                //
                                // It must be at least "protected"
                                //
                                if ((thisp & Modifiers.PROTECTED) == 0) {
                                        return false;
                                }

                                //
                                // when overriding protected internal, the method can be declared
                                // protected internal only within the same assembly or assembly
                                // which has InternalsVisibleTo
                                //
                                if ((thisp & Modifiers.INTERNAL) != 0) {
                                        return base_member.DeclaringType.MemberDefinition.IsInternalAsPublic (this_member.Module.DeclaringAssembly);
                                }

                                //
                                // protected overriding protected internal inside same assembly
                                // requires internal modifier as well
                                //
                                if (base_member.DeclaringType.MemberDefinition.IsInternalAsPublic (this_member.Module.DeclaringAssembly)) {
                                        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) {
                                InterfaceType = MemberName.ExplicitInterface.ResolveAsType (Parent);
                                if (InterfaceType == null)
                                        return false;

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

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

                                Modifiers allowed_explicit = Modifiers.AllowedExplicitImplFlags;
                                if (this is Method)
                                        allowed_explicit |= Modifiers.ASYNC;

                                ModifiersExtensions.Check (allowed_explicit, 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}'",
                                                      t.GetSignatureForError (), GetSignatureForError ());
                                else if (this is Operator)
                                        Report.Error (57, Location,
                                                      "Inconsistent accessibility: parameter type `{0}' is less accessible than operator `{1}'",
                                                      t.GetSignatureForError (), GetSignatureForError ());
                                else
                                        Report.Error (51, Location,
                                                "Inconsistent accessibility: parameter type `{0}' is less accessible than method `{1}'",
                                                t.GetSignatureForError (), GetSignatureForError ());
                                error = true;
                        }
                        return !error;
                }

                protected override void DoMemberTypeDependentChecks ()
                {
                        base.DoMemberTypeDependentChecks ();

                        VarianceDecl.CheckTypeVariance (MemberType, ExpectedMemberTypeVariance, this);
                }

                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 && (OptAttributes == null || !OptAttributes.HasResolveError ())) {
                                if (this is Constructor) {
                                        Report.Warning (824, 1, Location,
                                                "Constructor `{0}' is marked `external' but has no external implementation specified", GetSignatureForError ());
                                } else {
                                        Report.Warning (626, 1, 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)
                {
                        var base_modifiers = base_member.Modifiers;

                        // Remove internal modifier from types which are not internally accessible
                        if ((base_modifiers & Modifiers.AccessibilityMask) == (Modifiers.PROTECTED | Modifiers.INTERNAL) &&
                                !base_member.DeclaringType.MemberDefinition.IsInternalAsPublic (member.Module.DeclaringAssembly))
                                base_modifiers = Modifiers.PROTECTED;

                        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_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, ref bool overrides)
                {
                        return MemberCache.FindBaseMember (this, out bestCandidate, ref overrides);
                }

                //
                // The "short" name of this property / indexer / event.  This is the
                // name without the explicit interface.
                //
                public string ShortName {
                        get { return MemberName.Name; }
                }
                
                //
                // 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 InterfaceType.GetSignatureForError () + "." + name;
                }

                public override string GetSignatureForDocumentation ()
                {
                        if (IsExplicitImpl)
                                return Parent.GetSignatureForDocumentation () + "." + InterfaceType.GetExplicitNameSignatureForDocumentation () + "#" + ShortName;

                        return Parent.GetSignatureForDocumentation () + "." + ShortName;
                }

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

                public override void SetConstraints (List<Constraints> constraints_list)
                {
                        if (((ModFlags & Modifiers.OVERRIDE) != 0 || IsExplicitImpl)) {
                                Report.Error (460, Location,
                                        "`{0}': Cannot specify constraints for overrides and explicit interface implementation methods",
                                        GetSignatureForError ());
                        }

                        base.SetConstraints (constraints_list);
                }
        }

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

                protected MemberBase (TypeDefinition parent, FullNamedExpression type, Modifiers mod, Modifiers allowed_mod, Modifiers def_mod, MemberName name, Attributes attrs)
                        : base (parent, name, attrs)
                {
                        this.Parent = parent;
                        this.type_expr = type;

                        if (name != MemberName.Null)
                                ModFlags = ModifiersExtensions.Check (allowed_mod, mod, def_mod, Location, Report);
                }

                #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 `" +
                                                MemberType.GetSignatureForError () + "' is less " +
                                                "accessible than property `" + GetSignatureForError () + "'");
                                else if (this is Indexer)
                                        Report.Error (54, Location,
                                                "Inconsistent accessibility: indexer return type `" +
                                                MemberType.GetSignatureForError () + "' is less " +
                                                "accessible than indexer `" + GetSignatureForError () + "'");
                                else if (this is MethodCore) {
                                        if (this is Operator)
                                                Report.Error (56, Location,
                                                        "Inconsistent accessibility: return type `" +
                                                        MemberType.GetSignatureForError () + "' is less " +
                                                        "accessible than operator `" + GetSignatureForError () + "'");
                                        else
                                                Report.Error (50, Location,
                                                        "Inconsistent accessibility: return type `" +
                                                        MemberType.GetSignatureForError () + "' is less " +
                                                        "accessible than method `" + GetSignatureForError () + "'");
                                } else if (this is Event) {
                                        Report.Error (7025, Location,
                                                "Inconsistent accessibility: event type `{0}' is less accessible than event `{1}'",
                                                MemberType.GetSignatureForError (), GetSignatureForError ());
                                } else {
                                        Report.Error (52, Location,
                                                      "Inconsistent accessibility: field type `" +
                                                      MemberType.GetSignatureForError () + "' is less " +
                                                      "accessible than field `" + GetSignatureForError () + "'");
                                }
                        }
                }

                protected void IsTypePermitted ()
                {
                        if (MemberType.IsSpecialRuntimeType) {
                                if (Parent is StateMachine) {
                                        Report.Error (4012, Location,
                                                "Parameters or local variables of type `{0}' cannot be declared in async methods or iterators",
                                                MemberType.GetSignatureForError ());
                                } else if (Parent is HoistedStoreyClass) {
                                        Report.Error (4013, Location,
                                                "Local variables of type `{0}' cannot be used inside anonymous methods, lambda expressions or query expressions",
                                                MemberType.GetSignatureForError ());
                                } else {
                                        Report.Error (610, Location, 
                                                "Field or property cannot be of type `{0}'", MemberType.GetSignatureForError ());
                                }
                        }
                }

                protected virtual bool CheckBase ()
                {
                        CheckProtectedModifier ();

                        return true;
                }

                public override string GetSignatureForDocumentation ()
                {
                        return Parent.GetSignatureForDocumentation () + "." + MemberName.Basename;
                }

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

                        member_type = type_expr.ResolveAsType (this);
                        return member_type != null;
                }
        }
}