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[mcs.git] / mcs / typemanager.cs

//
// typemanager.cs: C# type manager
//
// Author: Miguel de Icaza (miguel@gnu.org)
//         Ravi Pratap     (ravi@ximian.com)
//         Marek Safar     (marek.safar@seznam.cz)
//
// Dual licensed under the terms of the MIT X11 or GNU GPL
//
// Copyright 2001-2003 Ximian, Inc (http://www.ximian.com)
// Copyright 2003-2008 Novell, Inc.
//

//
// We will eventually remove the SIMPLE_SPEEDUP, and should never change 
// the behavior of the compilation.  This can be removed if we rework
// the code to get a list of namespaces available.
//
#define SIMPLE_SPEEDUP

using System;
using System.IO;
using System.Globalization;
using System.Collections;
using System.Reflection;
using System.Reflection.Emit;
using System.Text;
using System.Runtime.CompilerServices;
using System.Diagnostics;

namespace Mono.CSharp {

        partial class TypeManager {
        //
        // A list of core types that the compiler requires or uses
        //
        static public Type object_type;
        static public Type value_type;
        static public Type string_type;
        static public Type int32_type;
        static public Type uint32_type;
        static public Type int64_type;
        static public Type uint64_type;
        static public Type float_type;
        static public Type double_type;
        static public Type char_type;
        static public Type short_type;
        static public Type decimal_type;
        static public Type bool_type;
        static public Type sbyte_type;
        static public Type byte_type;
        static public Type ushort_type;
        static public Type enum_type;
        static public Type delegate_type;
        static public Type multicast_delegate_type;
        static public Type void_type;
        static public Type null_type;
        static public Type array_type;
        static public Type runtime_handle_type;
        static public Type type_type;
        static public Type ienumerator_type;
        static public Type ienumerable_type;
        static public Type idisposable_type;
        static public Type iasyncresult_type;
        static public Type asynccallback_type;
        static public Type intptr_type;
        static public Type uintptr_type;
        static public Type runtime_field_handle_type;
        static public Type runtime_argument_handle_type;
        static public Type attribute_type;
        static public Type void_ptr_type;
        static public Type exception_type;

        static public Type typed_reference_type;
        static public Type arg_iterator_type;
        static public Type mbr_type;
        public static Type runtime_helpers_type;

        // 
        // C# 2.0
        //
        static internal Type isvolatile_type;
        static public Type generic_ilist_type;
        static public Type generic_icollection_type;
        static public Type generic_ienumerator_type;
        static public Type generic_ienumerable_type;
        static public Type generic_nullable_type;

        //
        // C# 3.0
        //
        static internal Type expression_type;
        public static Type parameter_expression_type;
        public static Type fieldinfo_type;
        public static Type methodinfo_type;
        public static Type ctorinfo_type;

        //
        // C# 4.0
        //
        public static Type call_site_type;
        public static Type generic_call_site_type;
        public static TypeExpr binder_type;
        public static Type binder_flags;

        // 
        // Expressions representing the internal types.  Used during declaration
        // definition.
        //
        static public TypeExpr system_object_expr, system_string_expr; 
        static public TypeExpr system_boolean_expr, system_decimal_expr;
        static public TypeExpr system_single_expr, system_double_expr;
        static public TypeExpr system_sbyte_expr, system_byte_expr;
        static public TypeExpr system_int16_expr, system_uint16_expr;
        static public TypeExpr system_int32_expr, system_uint32_expr;
        static public TypeExpr system_int64_expr, system_uint64_expr;
        static public TypeExpr system_char_expr, system_void_expr;
        static public TypeExpr system_valuetype_expr;
        static public TypeExpr system_intptr_expr;
        public static TypeExpr expression_type_expr;


        //
        // These methods are called by code generated by the compiler
        //
        static public FieldInfo string_empty;
        static public MethodInfo system_type_get_type_from_handle;
        static public MethodInfo bool_movenext_void;
        static public MethodInfo void_dispose_void;
        static public MethodInfo void_monitor_enter_object;
        static public MethodInfo void_monitor_exit_object;
        static public MethodInfo void_initializearray_array_fieldhandle;
        static public MethodInfo delegate_combine_delegate_delegate;
        static public MethodInfo delegate_remove_delegate_delegate;
        static public PropertyInfo int_get_offset_to_string_data;
        static public MethodInfo int_interlocked_compare_exchange;
        static public PropertyInfo ienumerator_getcurrent;
        public static MethodInfo methodbase_get_type_from_handle;
        public static MethodInfo methodbase_get_type_from_handle_generic;
        public static MethodInfo fieldinfo_get_field_from_handle;
        public static MethodInfo fieldinfo_get_field_from_handle_generic;
        static public MethodInfo activator_create_instance;

        //
        // The constructors.
        //
        static public ConstructorInfo void_decimal_ctor_five_args;
        static public ConstructorInfo void_decimal_ctor_int_arg;
        public static ConstructorInfo void_decimal_ctor_long_arg;

        static PtrHashtable builder_to_declspace;

        static PtrHashtable builder_to_member_cache;

        // <remarks>
        //   Tracks the interfaces implemented by typebuilders.  We only
        //   enter those who do implement or or more interfaces
        // </remarks>
        static PtrHashtable builder_to_ifaces;

        // <remarks>
        //   Maps a MethodBase to its ParameterData (either InternalParameters or ReflectionParameters)
        // <remarks>
        static Hashtable method_params;

        // <remarks>
        //  A hash table from override methods to their base virtual method.
        // <remarks>
        static Hashtable method_overrides;

        // <remarks>
        //  Keeps track of methods
        // </remarks>

        static Hashtable builder_to_method;

        // <remarks>
        //  Contains all public types from referenced assemblies.
        //  This member is used only if CLS Compliance verification is required.
        // </remarks>
        public static Hashtable AllClsTopLevelTypes;

        static Hashtable fieldbuilders_to_fields;
        static Hashtable propertybuilder_to_property;
        static Hashtable fields;
        static Hashtable events;
        static PtrHashtable assembly_internals_vis_attrs;

        public static void CleanUp ()
        {
                // Lets get everything clean so that we can collect before generating code
                builder_to_declspace = null;
                builder_to_member_cache = null;
                builder_to_ifaces = null;
                builder_to_type_param = null;
                method_params = null;
                builder_to_method = null;
                
                fields = null;
                events = null;
                type_hash = null;
                propertybuilder_to_property = null;

                TypeHandle.CleanUp ();
        }

        //
        // These are expressions that represent some of the internal data types, used
        // elsewhere
        //
        static void InitExpressionTypes ()
        {
                system_object_expr  = new TypeLookupExpression ("System", "Object");
                system_string_expr  = new TypeLookupExpression ("System", "String");
                system_boolean_expr = new TypeLookupExpression ("System", "Boolean");
                system_decimal_expr = new TypeLookupExpression ("System", "Decimal");
                system_single_expr  = new TypeLookupExpression ("System", "Single");
                system_double_expr  = new TypeLookupExpression ("System", "Double");
                system_sbyte_expr   = new TypeLookupExpression ("System", "SByte");
                system_byte_expr    = new TypeLookupExpression ("System", "Byte");
                system_int16_expr   = new TypeLookupExpression ("System", "Int16");
                system_uint16_expr  = new TypeLookupExpression ("System", "UInt16");
                system_int32_expr   = new TypeLookupExpression ("System", "Int32");
                system_uint32_expr  = new TypeLookupExpression ("System", "UInt32");
                system_int64_expr   = new TypeLookupExpression ("System", "Int64");
                system_uint64_expr  = new TypeLookupExpression ("System", "UInt64");
                system_char_expr    = new TypeLookupExpression ("System", "Char");
                system_void_expr    = new TypeLookupExpression ("System", "Void");
                system_valuetype_expr  = new TypeLookupExpression ("System", "ValueType");
                system_intptr_expr  = new TypeLookupExpression ("System", "IntPtr");
        }

        static TypeManager ()
        {
                Reset ();
        }

        static public void Reset ()
        {
                object_type = null;

                InitExpressionTypes ();
                
                builder_to_declspace = new PtrHashtable ();
                builder_to_member_cache = new PtrHashtable ();
                builder_to_method = new PtrHashtable ();
                builder_to_type_param = new PtrHashtable ();
                method_params = new PtrHashtable ();
                method_overrides = new PtrHashtable ();
                builder_to_ifaces = new PtrHashtable ();
                
                fieldbuilders_to_fields = new Hashtable ();
                propertybuilder_to_property = new Hashtable ();
                fields = new Hashtable ();
                type_hash = new DoubleHash ();
                assembly_internals_vis_attrs = new PtrHashtable ();
                iface_cache = new PtrHashtable ();
                
                closure = new Closure ();
                FilterWithClosure_delegate = new MemberFilter (closure.Filter);

                // TODO: I am really bored by all this static stuff
                system_type_get_type_from_handle =
                bool_movenext_void =
                void_dispose_void =
                void_monitor_enter_object =
                void_monitor_exit_object =
                void_initializearray_array_fieldhandle =
                delegate_combine_delegate_delegate =
                delegate_remove_delegate_delegate =
                int_interlocked_compare_exchange =
                methodbase_get_type_from_handle =
                methodbase_get_type_from_handle_generic =
                fieldinfo_get_field_from_handle =
                fieldinfo_get_field_from_handle_generic =
                activator_create_instance = null;

                int_get_offset_to_string_data =
                ienumerator_getcurrent = null;

                void_decimal_ctor_five_args =
                void_decimal_ctor_int_arg =
                void_decimal_ctor_long_arg = null;

                isvolatile_type = null;

                call_site_type =
                generic_call_site_type =
                binder_flags = null;

                binder_type = null;

                // to uncover regressions
                AllClsTopLevelTypes = null;
        }

        public static void AddUserType (DeclSpace ds)
        {
                builder_to_declspace.Add (ds.TypeBuilder, ds);
        }

        //
        // This entry point is used by types that we define under the covers
        // 
        public static void RegisterBuilder (Type tb, Type [] ifaces)
        {
                if (ifaces != null)
                        builder_to_ifaces [tb] = ifaces;
        }       

        public static void AddMethod (MethodBase builder, IMethodData method)
        {
                builder_to_method.Add (builder, method);
                method_params.Add (builder, method.ParameterInfo);
        }

        public static IMethodData GetMethod (MethodBase builder)
        {
                return (IMethodData) builder_to_method [builder];
        }

        /// <summary>
        ///   Returns the DeclSpace whose Type is `t' or null if there is no
        ///   DeclSpace for `t' (ie, the Type comes from a library)
        /// </summary>
        public static DeclSpace LookupDeclSpace (Type t)
        {
                return builder_to_declspace [t] as DeclSpace;
        }

        /// <summary>
        ///   Returns the TypeContainer whose Type is `t' or null if there is no
        ///   TypeContainer for `t' (ie, the Type comes from a library)
        /// </summary>
        public static TypeContainer LookupTypeContainer (Type t)
        {
                return builder_to_declspace [t] as TypeContainer;
        }

        public static MemberCache LookupMemberCache (Type t)
        {
                if (IsBeingCompiled (t)) {
                        DeclSpace container = (DeclSpace)builder_to_declspace [t];
                        if (container != null)
                                return container.MemberCache;
                }

                if (t is GenericTypeParameterBuilder) {
                        TypeParameter container = builder_to_type_param [t] as TypeParameter;

                        if (container != null)
                                return container.MemberCache;
                }

                return TypeHandle.GetMemberCache (t);
        }

        public static MemberCache LookupBaseInterfacesCache (Type t)
        {
                Type [] ifaces = GetInterfaces (t);

                if (ifaces != null && ifaces.Length == 1)
                        return LookupMemberCache (ifaces [0]);

                // TODO: the builder_to_member_cache should be indexed by 'ifaces', not 't'
                MemberCache cache = builder_to_member_cache [t] as MemberCache;
                if (cache != null)
                        return cache;

                cache = new MemberCache (ifaces);
                builder_to_member_cache.Add (t, cache);
                return cache;
        }

        public static TypeContainer LookupInterface (Type t)
        {
                TypeContainer tc = (TypeContainer) builder_to_declspace [t];
                if ((tc == null) || (tc.Kind != Kind.Interface))
                        return null;

                return tc;
        }

        public static Delegate LookupDelegate (Type t)
        {
                return builder_to_declspace [t] as Delegate;
        }

        public static Class LookupClass (Type t)
        {
                return (Class) builder_to_declspace [t];
        }

        //
        // We use this hash for multiple kinds of constructed types:
        //
        //    (T, "&")  Given T, get T &
        //    (T, "*")  Given T, get T *
        //    (T, "[]") Given T and a array dimension, get T []
        //    (T, X)    Given a type T and a simple name X, get the type T+X
        //
        // Accessibility tests, if necessary, should be done by the user
        //
        static DoubleHash type_hash = new DoubleHash ();

        //
        // Gets the reference to T version of the Type (T&)
        //
        public static Type GetReferenceType (Type t)
        {
                return t.MakeByRefType ();
        }

        //
        // Gets the pointer to T version of the Type  (T*)
        //
        public static Type GetPointerType (Type t)
        {
                return GetConstructedType (t, "*");
        }

        public static Type GetConstructedType (Type t, string dim)
        {
                object ret = null;
                if (type_hash.Lookup (t, dim, out ret))
                        return (Type) ret;

                if (IsDynamicType (t)) {
                        ret = new DynamicArrayType (dim.Length - 1);
                        type_hash.Insert (t, dim, ret);
                        return (Type) ret;
                }

                ret = t.Module.GetType (t.ToString () + dim);
                if (ret != null) {
                        type_hash.Insert (t, dim, ret);
                        return (Type) ret;
                }

                if (dim == "&") {
                        ret = GetReferenceType (t);
                        type_hash.Insert (t, dim, ret);
                        return (Type) ret;
                }

                if (t.IsGenericParameter || t.IsGenericType) {
                        int pos = 0;
                        Type result = t;
                        while ((pos < dim.Length) && (dim [pos] == '[')) {
                                pos++;

                                if (dim [pos] == ']') {
                                        result = result.MakeArrayType ();
                                        pos++;

                                        if (pos < dim.Length)
                                                continue;

                                        type_hash.Insert (t, dim, result);
                                        return result;
                                }

                                int rank = 0;
                                while (dim [pos] == ',') {
                                        pos++; rank++;
                                }

                                if ((dim [pos] != ']') || (pos != dim.Length-1))
                                        break;

                                result = result.MakeArrayType (rank + 1);
                                type_hash.Insert (t, dim, result);
                                return result;
                        }
                }

                type_hash.Insert (t, dim, null);
                return null;
        }

        public static Type GetNestedType (Type t, string name)
        {
                object ret = null;
                if (!type_hash.Lookup (t, name, out ret)) {
                        ret = t.GetNestedType (name,
                               BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.DeclaredOnly);
                        type_hash.Insert (t, name, ret);
                }
                return (Type) ret;
        }

        /// <summary>
        /// Fills static table with exported types from all referenced assemblies.
        /// This information is required for CLS Compliance tests.
        /// </summary>
        public static void LoadAllImportedTypes ()
        {
                AllClsTopLevelTypes = new Hashtable (1500);
                foreach (Assembly a in GlobalRootNamespace.Instance.Assemblies) {
                        foreach (Type t in a.GetExportedTypes ()) {
                                AllClsTopLevelTypes [t.FullName.ToLower (System.Globalization.CultureInfo.InvariantCulture)] = null;
                        }
                }
        }

        /// <summary>
        ///   Returns the C# name of a type if possible, or the full type name otherwise
        /// </summary>
        static public string CSharpName (Type t)
        {
                if (t == null_type)
                        return "null";

                if (t == typeof (ArglistAccess))
                        return "__arglist";
                        
                if (t == typeof (AnonymousMethodBody))
                        return "anonymous method";

                if (t == typeof (MethodGroupExpr))
                        return "method group";

                if (IsDynamicType (t))
                        return "dynamic";

                if (t == null)
                        return "internal error";

                return CSharpName (GetFullName (t), t);
        }

        static readonly char [] elements = new char [] { '*', '[' };

        public static string CSharpName (string name, Type type)
        {
                if (name.Length > 10) {
                        string s;
                        switch (name) {
                        case "System.Int32": s = "int"; break;
                        case "System.Int64": s = "long"; break;
                        case "System.String": s = "string"; break;
                        case "System.Boolean": s = "bool"; break;
                        case "System.Void": s = "void"; break;
                        case "System.Object": s = "object"; break;
                        case "System.UInt32": s = "uint"; break;
                        case "System.Int16": s = "short"; break;
                        case "System.UInt16": s = "ushort"; break;
                        case "System.UInt64": s = "ulong"; break;
                        case "System.Single": s = "float"; break;
                        case "System.Double": s = "double"; break;
                        case "System.Decimal": s = "decimal"; break;
                        case "System.Char": s = "char"; break;
                        case "System.Byte": s = "byte"; break;
                        case "System.SByte": s = "sbyte"; break;
                        default: s = null; break;
                        }

                        if (s != null) {
                                //
                                // Predefined names can come from mscorlib only
                                //
                                if (type == null || type.Module.Name == "mscorlib.dll" || !RootContext.StdLib)
                                        return s;
                                        
                                return name;
                        }

                        if (name [0] == AnonymousTypeClass.ClassNamePrefix [0] && name.StartsWith (AnonymousTypeClass.ClassNamePrefix))
                                return AnonymousTypeClass.SignatureForError;

                        int idx = name.IndexOfAny (elements, 10);
                        if (idx > 0)
                                return CSharpName (name.Substring (0, idx), type) + name.Substring (idx);
                }

                return name.Replace ('+', '.');
        }

        static public string CSharpName (Type[] types)
        {
                if (types.Length == 0)
                        return string.Empty;

                StringBuilder sb = new StringBuilder ();
                for (int i = 0; i < types.Length; ++i) {
                        if (i > 0)
                                sb.Append (", ");

                        sb.Append (CSharpName (types [i]));
                }
                return sb.ToString ();
        }

        /// <summary>
        ///  Returns the signature of the method with full namespace classification
        /// </summary>
        static public string GetFullNameSignature (MemberInfo mi)
        {
                PropertyInfo pi = mi as PropertyInfo;
                if (pi != null) {
                        MethodBase pmi = pi.GetGetMethod (true);
                        if (pmi == null)
                                pmi = pi.GetSetMethod (true);
                        if (GetParameterData (pmi).Count > 0)
                                mi = pmi;
                }
                return (mi is MethodBase)
                        ? CSharpSignature (mi as MethodBase) 
                        : CSharpName (mi.DeclaringType) + '.' + mi.Name;
        }

        private static int GetFullName (Type t, StringBuilder sb)
        {
                int pos = 0;

                if (!t.IsGenericType) {
                        sb.Append (t.FullName);
                        return 0;
                }

                if (t.DeclaringType != null) {
                        pos = GetFullName (t.DeclaringType, sb);
                        sb.Append ('.');
                } else if (t.Namespace != null && t.Namespace.Length != 0) {
                        sb.Append (t.Namespace);
                        sb.Append ('.');
                }
                sb.Append (RemoveGenericArity (t.Name));

                Type[] this_args = GetTypeArguments (t);

                if (this_args.Length < pos)
                        throw new InternalErrorException (
                                "Enclosing class " + t.DeclaringType + " has more type arguments than " + t);
                if (this_args.Length == pos)
                        return pos;

                sb.Append ('<');
                for (;;) {
                        sb.Append (CSharpName (this_args [pos++]));
                        if (pos == this_args.Length)
                                break;
                        sb.Append (',');
                }
                sb.Append ('>');
                return pos;
        }

        static string GetFullName (Type t)
        {
                if (t.IsArray) {
                        string dimension = t.Name.Substring (t.Name.LastIndexOf ('['));
                        return GetFullName (GetElementType (t)) + dimension;
                }

                if (IsNullableType (t) && !t.IsGenericTypeDefinition) {
                        t = TypeToCoreType (GetTypeArguments (t)[0]);
                        return CSharpName (t) + "?";
                }

                if (t.IsGenericParameter)
                        return t.Name;
                if (!t.IsGenericType)
                        return t.FullName;

                StringBuilder sb = new StringBuilder ();
                int pos = GetFullName (t, sb);
                if (pos <= 0)
                        throw new InternalErrorException ("Generic Type " + t + " doesn't have type arguments");
                return sb.ToString ();
        }

        public static string RemoveGenericArity (string from)
        {
                int i = from.IndexOf ('`');
                if (i > 0)
                        return from.Substring (0, i);
                return from;
        }

        /// <summary>
        /// When we need to report accessors as well
        /// </summary>
        static public string CSharpSignature (MethodBase mb)
        {
                return CSharpSignature (mb, false);
        }

        /// <summary>
        ///   Returns the signature of the method
        /// </summary>
        static public string CSharpSignature (MethodBase mb, bool show_accessor)
        {
                StringBuilder sig = new StringBuilder (CSharpName (mb.DeclaringType));
                sig.Append ('.');

                AParametersCollection iparams = GetParameterData (mb);
                string parameters = iparams.GetSignatureForError ();
                int accessor_end = 0;

                if (!mb.IsConstructor && TypeManager.IsSpecialMethod (mb)) {
                        string op_name = Operator.GetName (mb.Name);
                        if (op_name != null) {
                                if (op_name == "explicit" || op_name == "implicit") {
                                        sig.Append (op_name);
                                        sig.Append (" operator ");
                                        sig.Append (CSharpName (((MethodInfo)mb).ReturnType));
                                } else {
                                        sig.Append ("operator ");
                                        sig.Append (op_name);
                                }
                                sig.Append (parameters);
                                return sig.ToString ();
                        }

                        bool is_getter = mb.Name.StartsWith ("get_");
                        bool is_setter = mb.Name.StartsWith ("set_");
                        if (is_getter || is_setter || mb.Name.StartsWith ("add_")) {
                                accessor_end = 3;
                        } else if (mb.Name.StartsWith ("remove_")) {
                                accessor_end = 6;
                        }

                        // Is indexer
                        if (iparams.Count > (is_getter ? 0 : 1)) {
                                sig.Append ("this[");
                                if (is_getter)
                                        sig.Append (parameters.Substring (1, parameters.Length - 2));
                                else
                                        sig.Append (parameters.Substring (1, parameters.LastIndexOf (',') - 1));
                                sig.Append (']');
                        } else {
                                sig.Append (mb.Name.Substring (accessor_end + 1));
                        }
                } else {
                        if (mb.Name == ".ctor")
                                sig.Append (RemoveGenericArity (mb.DeclaringType.Name));
                        else {
                                sig.Append (mb.Name);

                                if (IsGenericMethod (mb)) {
                                        Type[] args = GetGenericArguments (mb);
                                        sig.Append ('<');
                                        for (int i = 0; i < args.Length; i++) {
                                                if (i > 0)
                                                        sig.Append (',');
                                                sig.Append (CSharpName (args [i]));
                                        }
                                        sig.Append ('>');
                                }
                        }

                        sig.Append (parameters);
                }

                if (show_accessor && accessor_end > 0) {
                        sig.Append ('.');
                        sig.Append (mb.Name.Substring (0, accessor_end));
                }

                return sig.ToString ();
        }

        public static string GetMethodName (MethodInfo m)
        {
                if (!IsGenericMethodDefinition (m) && !IsGenericMethod (m))
                        return m.Name;

                return MemberName.MakeName (m.Name, TypeManager.GetGenericArguments (m).Length);
        }

        static public string CSharpSignature (EventInfo ei)
        {
                return CSharpName (ei.DeclaringType) + "." + ei.Name;
        }

        //
        // Looks up a type, and aborts if it is not found.  This is used
        // by predefined types required by the compiler
        //
        public static Type CoreLookupType (CompilerContext ctx, string ns_name, string name, Kind type_kind, bool required)
        {
                Namespace ns = GlobalRootNamespace.Instance.GetNamespace (ns_name, true);
                Expression expr = ns.Lookup (ctx, name, Location.Null);

                if (expr == null) {
                        if (required) {
                                ctx.Report.Error (518, "The predefined type `{0}.{1}' is not defined or imported",
                                        ns_name, name);
                        }
                        return null;
                }

                Type t = expr.Type;
                if (RootContext.StdLib || t == null || !required)
                        return t;

                // TODO: All predefined imported types have to have correct signature
                if (!IsBeingCompiled (t))
                        return t;

                DeclSpace ds = (DeclSpace)RootContext.ToplevelTypes.GetDefinition (t.FullName);
                if (ds is Delegate) {
                        if (type_kind == Kind.Delegate)
                                return t;
                } else {
                        TypeContainer tc = (TypeContainer)ds;
                        if (tc.Kind == type_kind)
                                return t;
                }

                ctx.Report.Error (520, ds.Location, "The predefined type `{0}.{1}' is not declared correctly",
                        ns_name, name);
                return null;
        }

        static MemberInfo GetPredefinedMember (Type t, string name, MemberTypes mt, Location loc, params Type [] args)
        {
                const BindingFlags flags = instance_and_static | BindingFlags.Public | BindingFlags.DeclaredOnly;

                MemberInfo [] members = MemberLookup (null, null, t, mt, flags, name, null);
                if (members != null) {
                        for (int i = 0; i < members.Length; ++i) {
                                MemberInfo member = members [i];
                                if (mt == MemberTypes.Method || mt == MemberTypes.Constructor) {
                                        MethodBase mb = member as MethodBase;
                                        if (mb == null)
                                                continue;

                                        AParametersCollection pd = TypeManager.GetParameterData (mb);
                                        if (IsEqual (pd.Types, args))
                                                return member;
                                }
                                if (mt == MemberTypes.Field) {
                                        FieldInfo fi = member as FieldInfo;
                                        if (fi == null)
                                                continue;

                                        if (args.Length >= 1 && !IsEqual (TypeToCoreType (fi.FieldType), args [0]))
                                                continue;

                                        return member;
                                }

                                if (mt == MemberTypes.Property) {
                                        PropertyInfo pi = member as PropertyInfo;
                                        if (pi == null)
                                                continue;

                                        if (args.Length >= 1 && !IsEqual (TypeToCoreType (pi.PropertyType), args [0]))
                                                continue;

                                        return member;
                                }
                        }
                }

                string method_args = null;
                if (mt == MemberTypes.Method || mt == MemberTypes.Constructor)
                        method_args = "(" + TypeManager.CSharpName (args) + ")";

                RootContext.ToplevelTypes.Compiler.Report.Error (656, loc, "The compiler required member `{0}.{1}{2}' could not be found or is inaccessible",
                        TypeManager.CSharpName (t), name, method_args);

                return null;
        }

        //
        // Returns the ConstructorInfo for "args"
        //
        public static ConstructorInfo GetPredefinedConstructor (Type t, Location loc, params Type [] args)
        {
                return (ConstructorInfo) GetPredefinedMember (t, ConstructorInfo.ConstructorName, MemberTypes.Constructor, loc, args);
        }

        //
        // Returns the MethodInfo for a method named `name' defined
        // in type `t' which takes arguments of types `args'
        //
        public static MethodInfo GetPredefinedMethod (Type t, string name, Location loc, params Type [] args)
        {
                return (MethodInfo)GetPredefinedMember (t, name, MemberTypes.Method, loc, args);
        }

        public static FieldInfo GetPredefinedField (Type t, string name, Location loc, params Type [] args)
        {
                return (FieldInfo) GetPredefinedMember (t, name, MemberTypes.Field, loc, args);
        }

        public static PropertyInfo GetPredefinedProperty (Type t, string name, Location loc, params Type [] args)
        {
                return (PropertyInfo) GetPredefinedMember (t, name, MemberTypes.Property, loc, args);
        }

        /// <remarks>
        ///   The types have to be initialized after the initial
        ///   population of the type has happened (for example, to
        ///   bootstrap the corlib.dll
        /// </remarks>
        public static bool InitCoreTypes (CompilerContext ctx)
        {
                object_type   = CoreLookupType (ctx, "System", "Object", Kind.Class, true);
                system_object_expr.Type = object_type;
                value_type    = CoreLookupType (ctx, "System", "ValueType", Kind.Class, true);
                system_valuetype_expr.Type = value_type;
                attribute_type = CoreLookupType (ctx, "System", "Attribute", Kind.Class, true);

                int32_type    = CoreLookupType (ctx, "System", "Int32", Kind.Struct, true);
                system_int32_expr.Type = int32_type;
                int64_type    = CoreLookupType (ctx, "System", "Int64", Kind.Struct, true);
                system_int64_expr.Type = int64_type;
                uint32_type   = CoreLookupType (ctx, "System", "UInt32", Kind.Struct, true);
                system_uint32_expr.Type = uint32_type;
                uint64_type   = CoreLookupType (ctx, "System", "UInt64", Kind.Struct, true);
                system_uint64_expr.Type = uint64_type;
                byte_type     = CoreLookupType (ctx, "System", "Byte", Kind.Struct, true);
                system_byte_expr.Type = byte_type;
                sbyte_type    = CoreLookupType (ctx, "System", "SByte", Kind.Struct, true);
                system_sbyte_expr.Type = sbyte_type;
                short_type    = CoreLookupType (ctx, "System", "Int16", Kind.Struct, true);
                system_int16_expr.Type = short_type;
                ushort_type   = CoreLookupType (ctx, "System", "UInt16", Kind.Struct, true);
                system_uint16_expr.Type = ushort_type;

                ienumerator_type     = CoreLookupType (ctx, "System.Collections", "IEnumerator", Kind.Interface, true);
                ienumerable_type     = CoreLookupType (ctx, "System.Collections", "IEnumerable", Kind.Interface, true);
                idisposable_type     = CoreLookupType (ctx, "System", "IDisposable", Kind.Interface, true);

                // HACK: DefineType immediately resolves iterators (very wrong)
                generic_ienumerator_type = CoreLookupType (ctx, "System.Collections.Generic", "IEnumerator`1", Kind.Interface, false);

                char_type     = CoreLookupType (ctx, "System", "Char", Kind.Struct, true);
                system_char_expr.Type = char_type;
                string_type   = CoreLookupType (ctx, "System", "String", Kind.Class, true);
                system_string_expr.Type = string_type;
                float_type    = CoreLookupType (ctx, "System", "Single", Kind.Struct, true);
                system_single_expr.Type = float_type;
                double_type   = CoreLookupType (ctx, "System", "Double", Kind.Struct, true);
                system_double_expr.Type = double_type;
                decimal_type  = CoreLookupType (ctx, "System", "Decimal", Kind.Struct, true);
                system_decimal_expr.Type = decimal_type;
                bool_type     = CoreLookupType (ctx, "System", "Boolean", Kind.Struct, true);
                system_boolean_expr.Type = bool_type;
                intptr_type = CoreLookupType (ctx, "System", "IntPtr", Kind.Struct, true);
                system_intptr_expr.Type = intptr_type;
                uintptr_type = CoreLookupType (ctx, "System", "UIntPtr", Kind.Struct, true);

                multicast_delegate_type = CoreLookupType (ctx, "System", "MulticastDelegate", Kind.Class, true);
                delegate_type           = CoreLookupType (ctx, "System", "Delegate", Kind.Class, true);

                enum_type       = CoreLookupType (ctx, "System", "Enum", Kind.Class, true);
                array_type      = CoreLookupType (ctx, "System", "Array", Kind.Class, true);
                void_type       = CoreLookupType (ctx, "System", "Void", Kind.Struct, true);
                system_void_expr.Type = void_type;
                type_type       = CoreLookupType (ctx, "System", "Type", Kind.Class, true);
                exception_type = CoreLookupType (ctx, "System", "Exception", Kind.Class, true);

                runtime_field_handle_type = CoreLookupType (ctx, "System", "RuntimeFieldHandle", Kind.Struct, true);
                runtime_handle_type = CoreLookupType (ctx, "System", "RuntimeTypeHandle", Kind.Struct, true);

                PredefinedAttributes.Get.ParamArray.Resolve (false);
                PredefinedAttributes.Get.Out.Resolve (false);

                return ctx.Report.Errors == 0;
        }

        //
        // Initializes optional core types
        //
        public static void InitOptionalCoreTypes (CompilerContext ctx)
        {
                //
                // These are only used for compare purposes
                //
                null_type = typeof (NullLiteral);
                
                void_ptr_type = GetPointerType (void_type);

                //
                // Initialize InternalsVisibleTo as the very first optional type. Otherwise we would populate
                // types cache with incorrect accessiblity when any of optional types is internal.
                //
                PredefinedAttributes.Get.Initialize ();

                runtime_argument_handle_type = CoreLookupType (ctx, "System", "RuntimeArgumentHandle", Kind.Struct, false);
                asynccallback_type = CoreLookupType (ctx, "System", "AsyncCallback", Kind.Delegate, false);
                iasyncresult_type = CoreLookupType (ctx, "System", "IAsyncResult", Kind.Interface, false);
                typed_reference_type = CoreLookupType (ctx, "System", "TypedReference", Kind.Struct, false);
                arg_iterator_type = CoreLookupType (ctx, "System", "ArgIterator", Kind.Struct, false);
                mbr_type = CoreLookupType (ctx, "System", "MarshalByRefObject", Kind.Class, false);

                //
                // Optional attributes, used for error reporting only
                //
                //if (PredefinedAttributes.Get.Obsolete.IsDefined) {
                //    Class c = TypeManager.LookupClass (PredefinedAttributes.Get.Obsolete.Type);
                //    if (c != null)
                //        c.Define ();
                //}

                generic_ilist_type = CoreLookupType (ctx, "System.Collections.Generic", "IList`1", Kind.Interface, false);
                generic_icollection_type = CoreLookupType (ctx, "System.Collections.Generic", "ICollection`1", Kind.Interface, false);
                generic_ienumerable_type = CoreLookupType (ctx, "System.Collections.Generic", "IEnumerable`1", Kind.Interface, false);
                generic_nullable_type = CoreLookupType (ctx, "System", "Nullable`1", Kind.Struct, false);

                //
                // Optional types which are used as types and for member lookup
                //
                runtime_helpers_type = CoreLookupType (ctx, "System.Runtime.CompilerServices", "RuntimeHelpers", Kind.Class, false);

                // New in .NET 3.5
                // Note: extension_attribute_type is already loaded
                expression_type = CoreLookupType (ctx, "System.Linq.Expressions", "Expression`1", Kind.Class, false);

                if (!RootContext.StdLib) {
                        //
                        // HACK: When building Mono corlib mcs uses loaded mscorlib which
                        // has different predefined types and this method sets mscorlib types
                        // to be same to avoid any type check errors.
                        //

                        Type type = typeof (Type);
                        Type [] system_4_type_arg = { type, type, type, type };
                                
                        MethodInfo set_corlib_type_builders = 
                                typeof (System.Reflection.Emit.AssemblyBuilder).GetMethod (
                                "SetCorlibTypeBuilders", BindingFlags.NonPublic | BindingFlags.Instance, null,
                                system_4_type_arg, null);

                        if (set_corlib_type_builders != null) {
                                object[] args = new object [4];
                                args [0] = object_type;
                                args [1] = value_type;
                                args [2] = enum_type;
                                args [3] = void_type;
                                
                                set_corlib_type_builders.Invoke (CodeGen.Assembly.Builder, args);
                        } else {
                                ctx.Report.Warning (-26, 3, "The compilation may fail due to missing `{0}.SetCorlibTypeBuilders({1})' method",
                                        TypeManager.CSharpName (typeof (System.Reflection.Emit.AssemblyBuilder)),
                                        TypeManager.CSharpName (system_4_type_arg));
                        }
                }
        }

        const BindingFlags instance_and_static = BindingFlags.Static | BindingFlags.Instance;

        /// <remarks>
        ///   This is the "old", non-cache based FindMembers() function.  We cannot use
        ///   the cache here because there is no member name argument.
        /// </remarks>
        public static MemberList FindMembers (Type t, MemberTypes mt, BindingFlags bf,
                                              MemberFilter filter, object criteria)
        {
#if MS_COMPATIBLE
                if (t.IsGenericType)
                        t = t.GetGenericTypeDefinition ();
#endif

                DeclSpace decl = (DeclSpace) builder_to_declspace [t];

                //
                // `builder_to_declspace' contains all dynamic types.
                //
                if (decl != null) {
                        MemberList list;
                        Timer.StartTimer (TimerType.FindMembers);
                        list = decl.FindMembers (mt, bf, filter, criteria);
                        Timer.StopTimer (TimerType.FindMembers);
                        return list;
                }

                //
                // We have to take care of arrays specially, because GetType on
                // a TypeBuilder array will return a Type, not a TypeBuilder,
                // and we can not call FindMembers on this type.
                //
                if (
#if MS_COMPATIBLE
                        !t.IsGenericType &&
#endif
                        t.IsSubclassOf (TypeManager.array_type))
                        return new MemberList (TypeManager.array_type.FindMembers (mt, bf, filter, criteria));

                if (t is GenericTypeParameterBuilder) {
                        TypeParameter tparam = (TypeParameter) builder_to_type_param [t];

                        Timer.StartTimer (TimerType.FindMembers);
                        MemberList list = tparam.FindMembers (
                                mt, bf | BindingFlags.DeclaredOnly, filter, criteria);
                        Timer.StopTimer (TimerType.FindMembers);
                        return list;
                }

                //
                // Since FindMembers will not lookup both static and instance
                // members, we emulate this behaviour here.
                //
                if ((bf & instance_and_static) == instance_and_static){
                        MemberInfo [] i_members = t.FindMembers (
                                mt, bf & ~BindingFlags.Static, filter, criteria);

                        int i_len = i_members.Length;
                        if (i_len == 1){
                                MemberInfo one = i_members [0];

                                //
                                // If any of these are present, we are done!
                                //
                                if ((one is Type) || (one is EventInfo) || (one is FieldInfo))
                                        return new MemberList (i_members);
                        }
                                
                        MemberInfo [] s_members = t.FindMembers (
                                mt, bf & ~BindingFlags.Instance, filter, criteria);

                        int s_len = s_members.Length;
                        if (i_len > 0 || s_len > 0)
                                return new MemberList (i_members, s_members);
                        else {
                                if (i_len > 0)
                                        return new MemberList (i_members);
                                else
                                        return new MemberList (s_members);
                        }
                }

                return new MemberList (t.FindMembers (mt, bf, filter, criteria));
        }


        /// <summary>
        ///   This method is only called from within MemberLookup.  It tries to use the member
        ///   cache if possible and falls back to the normal FindMembers if not.  The `used_cache'
        ///   flag tells the caller whether we used the cache or not.  If we used the cache, then
        ///   our return value will already contain all inherited members and the caller don't need
        ///   to check base classes and interfaces anymore.
        /// </summary>
        private static MemberInfo [] MemberLookup_FindMembers (Type t, MemberTypes mt, BindingFlags bf,
                                                               string name, out bool used_cache)
        {
                MemberCache cache;

                //
                // If this is a dynamic type, it's always in the `builder_to_declspace' hash table
                // and we can ask the DeclSpace for the MemberCache.
                //
#if MS_COMPATIBLE
                if (t.Assembly == CodeGen.Assembly.Builder) {
                        if (t.IsGenericParameter) {
                                TypeParameter tparam = (TypeParameter) builder_to_type_param[t];

                                used_cache = true;
                                if (tparam.MemberCache == null)
                                        return new MemberInfo[0];

                                return tparam.MemberCache.FindMembers (
                                        mt, bf, name, FilterWithClosure_delegate, null);
                        }

                        //
                        // We have to take care of arrays specially, because GetType on
                        // a TypeBuilder array will return a Type, not a TypeBuilder,
                        // and we can not call FindMembers on this type.
                        //
                        if (t.IsArray) {
                                used_cache = true;
                                return TypeHandle.ArrayType.MemberCache.FindMembers (
                                        mt, bf, name, FilterWithClosure_delegate, null);
                        }

                        if (t.IsGenericType && !t.IsGenericTypeDefinition)
                                t = t.GetGenericTypeDefinition ();
#else
                if (t is TypeBuilder) {
#endif
                        DeclSpace decl = (DeclSpace) builder_to_declspace [t];
                        cache = decl.MemberCache;

                        //
                        // If this DeclSpace has a MemberCache, use it.
                        //

                        if (cache != null) {
                                used_cache = true;
                                return cache.FindMembers (
                                        mt, bf, name, FilterWithClosure_delegate, null);
                        }

                        // If there is no MemberCache, we need to use the "normal" FindMembers.
                        // Note, this is a VERY uncommon route!

                        MemberList list;
                        Timer.StartTimer (TimerType.FindMembers);
                        list = decl.FindMembers (mt, bf | BindingFlags.DeclaredOnly,
                                                 FilterWithClosure_delegate, name);
                        Timer.StopTimer (TimerType.FindMembers);
                        used_cache = false;
                        return (MemberInfo []) list;
                }

                //
                // We have to take care of arrays specially, because GetType on
                // a TypeBuilder array will return a Type, not a TypeBuilder,
                // and we can not call FindMembers on this type.
                //
                if (t.IsArray) {
                        used_cache = true;
                        return TypeHandle.ArrayType.MemberCache.FindMembers (
                                mt, bf, name, FilterWithClosure_delegate, null);
                }

                if (t is GenericTypeParameterBuilder) {
                        TypeParameter tparam = (TypeParameter) builder_to_type_param [t];

                        used_cache = true;
                        if (tparam.MemberCache == null)
                                return new MemberInfo [0];

                        return tparam.MemberCache.FindMembers (
                                mt, bf, name, FilterWithClosure_delegate, null);
                }

                if (IsGenericType (t) && (mt == MemberTypes.NestedType)) {
                        //
                        // This happens if we're resolving a class'es base class and interfaces
                        // in TypeContainer.DefineType().  At this time, the types aren't
                        // populated yet, so we can't use the cache.
                        //
                        MemberInfo[] info = t.FindMembers (mt, bf | BindingFlags.DeclaredOnly,
                                                           FilterWithClosure_delegate, name);
                        used_cache = false;
                        return info;
                }

                //
                // This call will always succeed.  There is exactly one TypeHandle instance per
                // type, TypeHandle.GetMemberCache() will, if necessary, create a new one, and return
                // the corresponding MemberCache.
                //
                cache = TypeHandle.GetMemberCache (t);

                used_cache = true;
                return cache.FindMembers (mt, bf, name, FilterWithClosure_delegate, null);
        }

        //
        // Return true for SRE dynamic/unclosed members
        //
        public static bool IsBeingCompiled (MemberInfo mi)
        {
                return mi.Module.Assembly == RootContext.ToplevelTypes.Module.Assembly;
        }

        public static bool IsBuiltinType (Type t)
        {
                t = TypeToCoreType (t);
                if (t == object_type || t == string_type || t == int32_type || t == uint32_type ||
                    t == int64_type || t == uint64_type || t == float_type || t == double_type ||
                    t == char_type || t == short_type || t == decimal_type || t == bool_type ||
                    t == sbyte_type || t == byte_type || t == ushort_type || t == void_type)
                        return true;
                else
                        return false;
        }

        //
        // This is like IsBuiltinType, but lacks decimal_type, we should also clean up
        // the pieces in the code where we use IsBuiltinType and special case decimal_type.
        // 
        public static bool IsPrimitiveType (Type t)
        {
                return (t == int32_type || t == uint32_type ||
                    t == int64_type || t == uint64_type || t == float_type || t == double_type ||
                    t == char_type || t == short_type || t == bool_type ||
                    t == sbyte_type || t == byte_type || t == ushort_type);
        }

        public static bool IsDelegateType (Type t)
        {
                if (TypeManager.IsGenericParameter (t))
                        return false;

                if (t == TypeManager.delegate_type || t == TypeManager.multicast_delegate_type)
                        return false;

                t = DropGenericTypeArguments (t);
                return IsSubclassOf (t, TypeManager.delegate_type);
        }

        //
        // Is a type of dynamic type
        //
        public static bool IsDynamicType (Type t)
        {
                if (object.ReferenceEquals (InternalType.Dynamic, t))
                        return true;

                if (t != object_type)
                        return false;

                if (IsBeingCompiled (t))
                        return false;

                PredefinedAttribute pa = PredefinedAttributes.Get.Dynamic;
                if (pa == null)
                        return false;

                object[] res = t.GetCustomAttributes (pa.Type, false);
                return res != null && res.Length != 0;
        }
        
        public static bool IsEnumType (Type t)
        {
                t = DropGenericTypeArguments (t);
                return t.BaseType == TypeManager.enum_type;
        }

        public static bool IsBuiltinOrEnum (Type t)
        {
                if (IsBuiltinType (t))
                        return true;
                
                if (IsEnumType (t))
                        return true;

                return false;
        }

        public static bool IsAttributeType (Type t)
        {
                return t == attribute_type && t.BaseType != null || IsSubclassOf (t, attribute_type);
        }
        
        //
        // Whether a type is unmanaged.  This is used by the unsafe code (25.2)
        //
        // mcs4: delete, DeclSpace.IsUnmanagedType is replacement
        public static bool IsUnmanagedType (Type t)
        {
                DeclSpace ds = TypeManager.LookupDeclSpace (t);
                if (ds != null)
                        return ds.IsUnmanagedType ();

                // builtins that are not unmanaged types
                if (t == TypeManager.object_type || t == TypeManager.string_type)
                        return false;

                if (IsGenericType (t) || IsGenericParameter (t))
                        return false;

                if (IsBuiltinOrEnum (t))
                        return true;

                // Someone did the work of checking if the ElementType of t is unmanaged.  Let's not repeat it.
                if (t.IsPointer)
                        return IsUnmanagedType (GetElementType (t));

                // Arrays are disallowed, even if we mark them with [MarshalAs(UnmanagedType.ByValArray, ...)]
                if (t.IsArray)
                        return false;

                if (!IsValueType (t))
                        return false;

                for (Type p = t.DeclaringType; p != null; p = p.DeclaringType) {
                        if (IsGenericTypeDefinition (p))
                                return false;
                }

                bool retval = true;
                {
                        FieldInfo [] fields = t.GetFields (BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
                        
                        foreach (FieldInfo f in fields){
                                if (!IsUnmanagedType (f.FieldType)){
                                        retval = false;
                                }
                        }
                }

                return retval;
        }

        //
        // Null is considered to be a reference type
        //                      
        public static bool IsReferenceType (Type t)
        {
                if (TypeManager.IsGenericParameter (t)) {
                        GenericConstraints constraints = TypeManager.GetTypeParameterConstraints (t);
                        if (constraints == null)
                                return false;

                        return constraints.IsReferenceType;
                }

                return !IsStruct (t) && !IsEnumType (t);
        }                       
                
        public static bool IsValueType (Type t)
        {
                if (TypeManager.IsGenericParameter (t)) {
                        GenericConstraints constraints = TypeManager.GetTypeParameterConstraints (t);
                        if (constraints == null)
                                return false;

                        return constraints.IsValueType;
                }

                return IsStruct (t) || IsEnumType (t);
        }

        public static bool IsStruct (Type t)
        {
                return t.BaseType == value_type && t != enum_type && t.IsSealed;
        }
        
        public static bool IsInterfaceType (Type t)
        {
                TypeContainer tc = (TypeContainer) builder_to_declspace [t];
                if (tc == null)
                        return false;

                return tc.Kind == Kind.Interface;
        }

        public static bool IsSubclassOf (Type type, Type base_type)
        {
                TypeParameter tparam = LookupTypeParameter (type);
                TypeParameter pparam = LookupTypeParameter (base_type);

                if ((tparam != null) && (pparam != null)) {
                        if (tparam == pparam)
                                return true;

                        return tparam.IsSubclassOf (base_type);
                }

#if MS_COMPATIBLE
                if (tparam != pparam)
                        return false;

                if (type.IsGenericType)
                        type = type.GetGenericTypeDefinition ();
#endif

                if (type.IsSubclassOf (base_type))
                        return true;

                do {
                        if (IsEqual (type, base_type))
                                return true;

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

                return false;
        }

        public static bool IsPrivateAccessible (Type type, Type parent)
        {
                if (type == null)
                        return false;

                if (type.Equals (parent))
                        return true;

                return DropGenericTypeArguments (type) == DropGenericTypeArguments (parent);
        }

        public static bool IsFamilyAccessible (Type type, Type parent)
        {
                TypeParameter tparam = LookupTypeParameter (type);
                TypeParameter pparam = LookupTypeParameter (parent);

                if ((tparam != null) && (pparam != null)) {
                        if (tparam == pparam)
                                return true;

                        return tparam.IsSubclassOf (parent);
                }

                do {
                        if (IsInstantiationOfSameGenericType (type, parent))
                                return true;

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

                return false;
        }

        //
        // Checks whether `type' is a subclass or nested child of `base_type'.
        //
        public static bool IsNestedFamilyAccessible (Type type, Type base_type)
        {
                do {
                        if (IsFamilyAccessible (type, base_type))
                                return true;

                        // Handle nested types.
                        type = type.DeclaringType;
                } while (type != null);

                return false;
        }

        //
        // Checks whether `type' is a nested child of `parent'.
        //
        public static bool IsNestedChildOf (Type type, Type parent)
        {
                if (type == null)
                        return false;

                type = DropGenericTypeArguments (type);
                parent = DropGenericTypeArguments (parent);

                if (IsEqual (type, parent))
                        return false;

                type = type.DeclaringType;
                while (type != null) {
                        if (IsEqual (type, parent))
                                return true;

                        type = type.DeclaringType;
                }

                return false;
        }

        public static bool IsSpecialType (Type t)
        {
                return t == arg_iterator_type || t == typed_reference_type;
        }

        //
        // Checks whether `invocationAssembly' is same or a friend of the assembly
        //
        public static bool IsThisOrFriendAssembly (Assembly invocationAssembly, Assembly assembly)
        {
                if (assembly == null)
                        throw new ArgumentNullException ("assembly");

                // TODO: This can happen for constants used at assembly level and
                // predefined members
                // But there is no way to test for it for now, so it could be abused
                // elsewhere too.
                if (invocationAssembly == null)
                        invocationAssembly = CodeGen.Assembly.Builder;

                if (invocationAssembly == assembly)
                        return true;

                if (assembly_internals_vis_attrs.Contains (assembly))
                        return (bool)(assembly_internals_vis_attrs [assembly]);

                PredefinedAttribute pa = PredefinedAttributes.Get.InternalsVisibleTo;
                // HACK: Do very early resolve of SRE type checking
                if (pa.Type == null)
                        pa.Resolve (true);

                if (!pa.IsDefined)
                        return false;
                
                object [] attrs = assembly.GetCustomAttributes (pa.Type, false);
                if (attrs.Length == 0) {
                        assembly_internals_vis_attrs.Add (assembly, false);
                        return false;
                }

                bool is_friend = false;

                AssemblyName this_name = CodeGen.Assembly.Name;
                byte [] this_token = this_name.GetPublicKeyToken ();
                foreach (InternalsVisibleToAttribute attr in attrs) {
                        if (attr.AssemblyName == null || attr.AssemblyName.Length == 0)
                                continue;
                        
                        AssemblyName aname = null;
                        try {
                                aname = new AssemblyName (attr.AssemblyName);
                        } catch (FileLoadException) {
                        } catch (ArgumentException) {
                        }

                        if (aname == null || aname.Name != this_name.Name)
                                continue;
                        
                        byte [] key_token = aname.GetPublicKeyToken ();
                        if (key_token != null) {
                                if (this_token.Length == 0) {
                                        // Same name, but assembly is not strongnamed
                                        Error_FriendAccessNameNotMatching (aname.FullName, RootContext.ToplevelTypes.Compiler.Report);
                                        break;
                                }
                                
                                if (!CompareKeyTokens (this_token, key_token))
                                        continue;
                        }

                        is_friend = true;
                        break;
                }

                assembly_internals_vis_attrs.Add (assembly, is_friend);
                return is_friend;
        }

        static bool CompareKeyTokens (byte [] token1, byte [] token2)
        {
                for (int i = 0; i < token1.Length; i++)
                        if (token1 [i] != token2 [i])
                                return false;

                return true;
        }

        static void Error_FriendAccessNameNotMatching (string other_name, Report Report)
        {
                Report.Error (281,
                        "Friend access was granted to `{0}', but the output assembly is named `{1}'. Try adding a reference to `{0}' or change the output assembly name to match it",
                        other_name, CodeGen.Assembly.Name.FullName);
        }

        //
        // Do the right thing when returning the element type of an
        // array type based on whether we are compiling corlib or not
        //
        public static Type GetElementType (Type t)
        {
                if (RootContext.StdLib)
                        return t.GetElementType ();
                else
                        return TypeToCoreType (t.GetElementType ());
        }

        /// <summary>
        /// This method is not implemented by MS runtime for dynamic types
        /// </summary>
        public static bool HasElementType (Type t)
        {
                return t.IsArray || t.IsPointer || t.IsByRef;
        }

        public static Type GetEnumUnderlyingType (Type t)
        {
                t = DropGenericTypeArguments (t);
                Enum e = LookupTypeContainer (t) as Enum;
                if (e != null)
                        return e.UnderlyingType;

                // TODO: cache it ?
                FieldInfo fi = GetPredefinedField (t, Enum.UnderlyingValueField, Location.Null, Type.EmptyTypes);
                if (fi == null)
                        return TypeManager.int32_type;

                return TypeToCoreType (fi.FieldType);
        }
        
        /// <summary>
        ///   Gigantic work around for missing features in System.Reflection.Emit follows.
        /// </summary>
        ///
        /// <remarks>
        ///   Since System.Reflection.Emit can not return MethodBase.GetParameters
        ///   for anything which is dynamic, and we need this in a number of places,
        ///   we register this information here, and use it afterwards.
        /// </remarks>
        static public void RegisterMethod (MethodBase mb, AParametersCollection ip)
        {
                method_params.Add (mb, ip);
        }

        static public void RegisterIndexer (PropertyBuilder pb, AParametersCollection p)
        {
                method_params.Add (pb, p);
        }
        
        static public AParametersCollection GetParameterData (MethodBase mb)
        {
                AParametersCollection pd = (AParametersCollection) method_params [mb];
                if (pd == null) {
#if MS_COMPATIBLE
                        if (mb.IsGenericMethod && !mb.IsGenericMethodDefinition) {
                                MethodInfo mi = ((MethodInfo) mb).GetGenericMethodDefinition ();
                                pd = GetParameterData (mi);
                                /*
                                if (mi.IsGenericMethod)
                                        pd = pd.InflateTypes (mi.GetGenericArguments (), mb.GetGenericArguments ());
                                else
                                        pd = pd.InflateTypes (mi.DeclaringType.GetGenericArguments (), mb.GetGenericArguments ());
                                */
                                method_params.Add (mb, pd);
                                return pd;
                        }

                        if (mb.DeclaringType.Assembly == CodeGen.Assembly.Builder) {
                                throw new InternalErrorException ("Parameters are not registered for method `{0}'",
                                        TypeManager.CSharpName (mb.DeclaringType) + "." + mb.Name);
                        }

                        pd = ParametersImported.Create (mb);
#else
                        MethodBase generic = TypeManager.DropGenericMethodArguments (mb);
                        if (generic != mb) {
                                pd = TypeManager.GetParameterData (generic);
                                pd = ParametersImported.Create (pd, mb);
                        } else {
                                pd = ParametersImported.Create (mb);
                        }
#endif
                        method_params.Add (mb, pd);
                }
                return pd;
        }

        public static AParametersCollection GetParameterData (PropertyInfo pi)
        {
                AParametersCollection pd = (AParametersCollection)method_params [pi];
                if (pd == null) {
                        if (pi is PropertyBuilder)
                                return ParametersCompiled.EmptyReadOnlyParameters;

                        ParameterInfo [] p = pi.GetIndexParameters ();
                        if (p == null)
                                return ParametersCompiled.EmptyReadOnlyParameters;

                        pd = ParametersImported.Create (p, null);
                        method_params.Add (pi, pd);
                }

                return pd;
        }

        public static AParametersCollection GetDelegateParameters (ResolveContext ec, Type t)
        {
                Delegate d = builder_to_declspace [t] as Delegate;
                if (d != null)
                        return d.Parameters;

                MethodInfo invoke_mb = Delegate.GetInvokeMethod (ec.Compiler, t, t);
                return GetParameterData (invoke_mb);
        }

        static public void RegisterOverride (MethodBase override_method, MethodBase base_method)
        {
                if (!method_overrides.Contains (override_method))
                        method_overrides [override_method] = base_method;
                if (method_overrides [override_method] != base_method)
                        throw new InternalErrorException ("Override mismatch: " + override_method);
        }

        static public bool IsOverride (MethodBase m)
        {
                m = DropGenericMethodArguments (m);

                return m.IsVirtual &&
                        (m.Attributes & MethodAttributes.NewSlot) == 0 &&
                        (m is MethodBuilder || method_overrides.Contains (m));
        }

        static public MethodBase TryGetBaseDefinition (MethodBase m)
        {
                m = DropGenericMethodArguments (m);

                return (MethodBase) method_overrides [m];
        }

        public static void RegisterConstant (FieldInfo fb, IConstant ic)
        {
                fields.Add (fb, ic);
        }

        public static IConstant GetConstant (FieldInfo fb)
        {
                if (fb == null)
                        return null;

                return (IConstant)fields [fb];
        }

        public static void RegisterProperty (PropertyInfo pi, PropertyBase pb)
        {
                propertybuilder_to_property.Add (pi, pb);
        }

        public static PropertyBase GetProperty (PropertyInfo pi)
        {
                return (PropertyBase)propertybuilder_to_property [pi];
        }

        static public void RegisterFieldBase (FieldBuilder fb, FieldBase f)
        {
                fieldbuilders_to_fields.Add (fb, f);
        }

        //
        // The return value can be null;  This will be the case for
        // auxiliary FieldBuilders created by the compiler that have no
        // real field being declared on the source code
        //
        static public FieldBase GetField (FieldInfo fb)
        {
                fb = GetGenericFieldDefinition (fb);
                return (FieldBase) fieldbuilders_to_fields [fb];
        }

        static public MethodInfo GetAddMethod (EventInfo ei)
        {
                if (ei is MyEventBuilder) {
                        return ((MyEventBuilder)ei).GetAddMethod (true);
                }
                return ei.GetAddMethod (true);
        }

        static public MethodInfo GetRemoveMethod (EventInfo ei)
        {
                if (ei is MyEventBuilder) {
                        return ((MyEventBuilder)ei).GetRemoveMethod (true);
                }
                return ei.GetRemoveMethod (true);
        }

        static public void RegisterEventField (EventInfo einfo, EventField e)
        {
                if (events == null)
                        events = new Hashtable ();

                events.Add (einfo, e);
        }

        static public EventField GetEventField (EventInfo ei)
        {
                if (events == null)
                        return null;

                return (EventField) events [ei];
        }

        public static bool CheckStructCycles (TypeContainer tc, Hashtable seen)
        {
                Hashtable hash = new Hashtable ();
                return CheckStructCycles (tc, seen, hash);
        }

        public static bool CheckStructCycles (TypeContainer tc, Hashtable seen,
                                              Hashtable hash)
        {
                if ((tc.Kind != Kind.Struct) || IsBuiltinType (tc.TypeBuilder))
                        return true;

                //
                // `seen' contains all types we've already visited.
                //
                if (seen.Contains (tc))
                        return true;
                seen.Add (tc, null);

                if (tc.Fields == null)
                        return true;

                foreach (FieldBase field in tc.Fields) {
                        if (field.FieldBuilder == null || field.FieldBuilder.IsStatic)
                                continue;

                        Type ftype = field.FieldBuilder.FieldType;
                        TypeContainer ftc = LookupTypeContainer (ftype);
                        if (ftc == null)
                                continue;

                        if (hash.Contains (ftc)) {
                                RootContext.ToplevelTypes.Compiler.Report.Error (523, tc.Location,
                                              "Struct member `{0}.{1}' of type `{2}' " +
                                              "causes a cycle in the struct layout",
                                              tc.Name, field.Name, ftc.Name);
                                return false;
                        }

                        //
                        // `hash' contains all types in the current path.
                        //
                        hash.Add (tc, null);

                        bool ok = CheckStructCycles (ftc, seen, hash);

                        hash.Remove (tc);

                        if (!ok)
                                return false;

                        if (!seen.Contains (ftc))
                                seen.Add (ftc, null);
                }

                return true;
        }

        /// <summary>
        ///   Given an array of interface types, expand and eliminate repeated ocurrences
        ///   of an interface.  
        /// </summary>
        ///
        /// <remarks>
        ///   This expands in context like: IA; IB : IA; IC : IA, IB; the interface "IC" to
        ///   be IA, IB, IC.
        /// </remarks>
        public static Type[] ExpandInterfaces (TypeExpr [] base_interfaces)
        {
                ArrayList new_ifaces = new ArrayList ();

                foreach (TypeExpr iface in base_interfaces){
                        Type itype = iface.Type;

                        if (new_ifaces.Contains (itype))
                                continue;

                        new_ifaces.Add (itype);
                        
                        Type [] implementing = GetInterfaces (itype);

                        foreach (Type imp in implementing){
                                if (!new_ifaces.Contains (imp))
                                        new_ifaces.Add (imp);
                        }
                }
                Type [] ret = new Type [new_ifaces.Count];
                new_ifaces.CopyTo (ret, 0);
                return ret;
        }

        public static Type[] ExpandInterfaces (Type [] base_interfaces)
        {
                ArrayList new_ifaces = new ArrayList ();

                foreach (Type itype in base_interfaces){
                        if (new_ifaces.Contains (itype))
                                continue;

                        new_ifaces.Add (itype);
                        
                        Type [] implementing = GetInterfaces (itype);

                        foreach (Type imp in implementing){
                                if (!new_ifaces.Contains (imp))
                                        new_ifaces.Add (imp);
                        }
                }
                Type [] ret = new Type [new_ifaces.Count];
                new_ifaces.CopyTo (ret, 0);
                return ret;
        }
                
        static PtrHashtable iface_cache;
                
        /// <summary>
        ///   This function returns the interfaces in the type `t'.  Works with
        ///   both types and TypeBuilders.
        /// </summary>
        public static Type [] GetInterfaces (Type t)
        {
                Type [] cached = iface_cache [t] as Type [];
                if (cached != null)
                        return cached;
                
                //
                // The reason for catching the Array case is that Reflection.Emit
                // will not return a TypeBuilder for Array types of TypeBuilder types,
                // but will still throw an exception if we try to call GetInterfaces
                // on the type.
                //
                // Since the array interfaces are always constant, we return those for
                // the System.Array
                //
                
                if (t.IsArray)
                        t = TypeManager.array_type;
                
                if ((t is TypeBuilder) || IsGenericType (t)) {
                        Type [] base_ifaces;
                        
                        if (t.BaseType == null)
                                base_ifaces = Type.EmptyTypes;
                        else
                                base_ifaces = GetInterfaces (t.BaseType);
                        Type[] type_ifaces;
                        if (IsGenericType (t))
#if MS_COMPATIBLE
                                type_ifaces = t.GetGenericTypeDefinition().GetInterfaces ();
#else
                                type_ifaces = t.GetInterfaces ();
#endif
                        else
                                type_ifaces = (Type []) builder_to_ifaces [t];
                        if (type_ifaces == null || type_ifaces.Length == 0)
                                type_ifaces = Type.EmptyTypes;

                        int base_count = base_ifaces.Length;
                        Type [] result = new Type [base_count + type_ifaces.Length];
                        base_ifaces.CopyTo (result, 0);
                        type_ifaces.CopyTo (result, base_count);

                        iface_cache [t] = result;
                        return result;
                } else if (t is GenericTypeParameterBuilder){
                        Type[] type_ifaces = (Type []) builder_to_ifaces [t];
                        if (type_ifaces == null || type_ifaces.Length == 0)
                                type_ifaces = Type.EmptyTypes;

                        iface_cache [t] = type_ifaces;
                        return type_ifaces;
                } else {
                        Type[] ifaces = t.GetInterfaces ();
                        iface_cache [t] = ifaces;
                        return ifaces;
                }
        }
        
        //
        // gets the interfaces that are declared explicitly on t
        //
        public static Type [] GetExplicitInterfaces (TypeBuilder t)
        {
                return (Type []) builder_to_ifaces [t];
        }
        
        /// <remarks>
        ///  The following is used to check if a given type implements an interface.
        ///  The cache helps us reduce the expense of hitting Type.GetInterfaces everytime.
        /// </remarks>
        public static bool ImplementsInterface (Type t, Type iface)
        {
                Type [] interfaces;

                //
                // FIXME OPTIMIZATION:
                // as soon as we hit a non-TypeBuiler in the interface
                // chain, we could return, as the `Type.GetInterfaces'
                // will return all the interfaces implement by the type
                // or its bases.
                //
                do {
                        interfaces = GetInterfaces (t);

                        if (interfaces != null){
                                foreach (Type i in interfaces){
                                        if (i == iface || IsVariantOf (i, iface))
                                                return true;
                                }
                        }
                        
                        t = t.BaseType;
                } while (t != null);
                
                return false;
        }

        static NumberFormatInfo nf_provider = CultureInfo.CurrentCulture.NumberFormat;

        // This is a custom version of Convert.ChangeType() which works
        // with the TypeBuilder defined types when compiling corlib.
        public static object ChangeType (object value, Type conversionType, out bool error)
        {
                IConvertible convert_value = value as IConvertible;
                
                if (convert_value == null){
                        error = true;
                        return null;
                }
                
                //
                // NOTE 1:
                // We must use Type.Equals() here since `conversionType' is
                // the TypeBuilder created version of a system type and not
                // the system type itself.  You cannot use Type.GetTypeCode()
                // on such a type - it'd always return TypeCode.Object.
                //
                // NOTE 2:
                // We cannot rely on build-in type conversions as they are
                // more limited than what C# supports.
                // See char -> float/decimal/double conversion
                //

                error = false;
                try {
                        if (conversionType.Equals (typeof (Boolean)))
                                return (object)(convert_value.ToBoolean (nf_provider));
                        if (conversionType.Equals (typeof (Byte)))
                                return (object)(convert_value.ToByte (nf_provider));
                        if (conversionType.Equals (typeof (Char)))
                                return (object)(convert_value.ToChar (nf_provider));
                        if (conversionType.Equals (typeof (DateTime)))
                                return (object)(convert_value.ToDateTime (nf_provider));

                        if (conversionType.Equals (decimal_type)) {
                                if (convert_value.GetType () == TypeManager.char_type)
                                        return (decimal)convert_value.ToInt32 (nf_provider);
                                return convert_value.ToDecimal (nf_provider);
                        }

                        if (conversionType.Equals (typeof (Double))) {
                                if (convert_value.GetType () == TypeManager.char_type)
                                        return (double)convert_value.ToInt32 (nf_provider);
                                return convert_value.ToDouble (nf_provider);
                        }

                        if (conversionType.Equals (typeof (Int16)))
                                return (object)(convert_value.ToInt16 (nf_provider));
                        if (conversionType.Equals (int32_type))
                                return (object)(convert_value.ToInt32 (nf_provider));
                        if (conversionType.Equals (int64_type))
                                return (object)(convert_value.ToInt64 (nf_provider));
                        if (conversionType.Equals (typeof (SByte)))
                                return (object)(convert_value.ToSByte (nf_provider));

                        if (conversionType.Equals (typeof (Single))) {
                                if (convert_value.GetType () == TypeManager.char_type)
                                        return (float)convert_value.ToInt32 (nf_provider);
                                return convert_value.ToSingle (nf_provider);
                        }

                        if (conversionType.Equals (typeof (String)))
                                return (object)(convert_value.ToString (nf_provider));
                        if (conversionType.Equals (typeof (UInt16)))
                                return (object)(convert_value.ToUInt16 (nf_provider));
                        if (conversionType.Equals (typeof (UInt32)))
                                return (object)(convert_value.ToUInt32 (nf_provider));
                        if (conversionType.Equals (typeof (UInt64)))
                                return (object)(convert_value.ToUInt64 (nf_provider));
                        if (conversionType.Equals (typeof (Object)))
                                return (object)(value);
                        else 
                                error = true;
                } catch {
                        error = true;
                }
                return null;
        }

        //
        // When compiling with -nostdlib and the type is imported from an external assembly
        // SRE uses "wrong" type and we have to convert it to the right compiler instance.
        //
        public static Type TypeToCoreType (Type t)
        {
                if (RootContext.StdLib || t.Module != typeof (object).Module)
                        return t;
                        
                // TODO: GetTypeCode returns underlying type for enums !!
                TypeCode tc = Type.GetTypeCode (t);

                switch (tc){
                case TypeCode.Boolean:
                        return TypeManager.bool_type;
                case TypeCode.Byte:
                        return TypeManager.byte_type;
                case TypeCode.SByte:
                        return TypeManager.sbyte_type;
                case TypeCode.Char:
                        return TypeManager.char_type;
                case TypeCode.Int16:
                        return TypeManager.short_type;
                case TypeCode.UInt16:
                        return TypeManager.ushort_type;
                case TypeCode.Int32:
                        return TypeManager.int32_type;
                case TypeCode.UInt32:
                        return TypeManager.uint32_type;
                case TypeCode.Int64:
                        return TypeManager.int64_type;
                case TypeCode.UInt64:
                        return TypeManager.uint64_type;
                case TypeCode.Single:
                        return TypeManager.float_type;
                case TypeCode.Double:
                        return TypeManager.double_type;
                case TypeCode.String:
                        return TypeManager.string_type;
                case TypeCode.Decimal:
                        return TypeManager.decimal_type;
                }

                if (t == typeof (void))
                        return TypeManager.void_type;
                if (t == typeof (object))
                        return TypeManager.object_type;
                if (t == typeof (System.Type))
                        return TypeManager.type_type;
                if (t == typeof (System.IntPtr))
                        return TypeManager.intptr_type;
                if (t == typeof (System.UIntPtr))
                        return TypeManager.uintptr_type;

                if (t.IsArray) {
                        int dim = t.GetArrayRank ();
                        t = GetElementType (t);
                        return t.MakeArrayType (dim);
                }
                if (t.IsByRef) {
                        t = GetElementType (t);
                        return t.MakeByRefType ();
                }
                if (t.IsPointer) {
                        t = GetElementType (t);
                        return t.MakePointerType ();
                }

                return t;
        }

        //
        // Converts any type to reflection supported type
        //
        public static Type TypeToReflectionType (Type type)
        {
                // TODO: Very lame and painful, GetReference () is enough for mcs-cecil
                if (IsDynamicType (type))
                        return object_type;

                if (type is DynamicArrayType)
                        return type.UnderlyingSystemType;

                return type;
        }

        /// <summary>
        ///   Utility function that can be used to probe whether a type
        ///   is managed or not.  
        /// </summary>
        public static bool VerifyUnManaged (Type t, Location loc)
        {
                if (IsUnmanagedType (t))
                        return true;

                while (t.IsPointer)
                        t = GetElementType (t);

                RootContext.ToplevelTypes.Compiler.Report.SymbolRelatedToPreviousError (t);
                RootContext.ToplevelTypes.Compiler.Report.Error (208, loc,
                        "Cannot take the address of, get the size of, or declare a pointer to a managed type `{0}'",
                        CSharpName (t));

                return false;   
        }
        
        /// <summary>
        ///   Returns the name of the indexer in a given type.
        /// </summary>
        /// <remarks>
        ///   The default is not always `Item'.  The user can change this behaviour by
        ///   using the IndexerNameAttribute in the container.
        ///   For example, the String class indexer is named `Chars' not `Item' 
        /// </remarks>
        public static string IndexerPropertyName (Type t)
        {
                t = DropGenericTypeArguments (t);
                if (t is TypeBuilder) {
                        TypeContainer tc = t.IsInterface ? LookupInterface (t) : LookupTypeContainer (t);
                        return tc == null ? TypeContainer.DefaultIndexerName : tc.IndexerName;
                }

                PredefinedAttribute pa = PredefinedAttributes.Get.DefaultMember;
                if (pa.IsDefined) {
                        System.Attribute attr = System.Attribute.GetCustomAttribute (
                                t, pa.Type);
                        if (attr != null) {
                                DefaultMemberAttribute dma = (DefaultMemberAttribute) attr;
                                return dma.MemberName;
                        }
                }

                return TypeContainer.DefaultIndexerName;
        }

        static MethodInfo declare_local_method = null;
        
        public static LocalBuilder DeclareLocalPinned (ILGenerator ig, Type t)
        {
                if (declare_local_method == null){
                        declare_local_method = typeof (ILGenerator).GetMethod (
                                "DeclareLocal",
                                BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic,
                                null, 
                                new Type [] { typeof (Type), typeof (bool)},
                                null);
                        if (declare_local_method == null){
                                RootContext.ToplevelTypes.Compiler.Report.RuntimeMissingSupport (Location.Null, "pinned local variables");
                                return ig.DeclareLocal (t);
                        }
                }
                return (LocalBuilder) declare_local_method.Invoke (ig, new object [] { t, true });
        }

        private static bool IsSignatureEqual (Type a, Type b)
        {
                ///
                /// Consider the following example (bug #77674):
                ///
                ///     public abstract class A
                ///     {
                ///        public abstract T Foo<T> ();
                ///     }
                ///
                ///     public abstract class B : A
                ///     {
                ///        public override U Foo<T> ()
                ///        { return default (U); }
                ///     }
                ///
                /// Here, `T' and `U' are method type parameters from different methods
                /// (A.Foo and B.Foo), so both `==' and Equals() will fail.
                ///
                /// However, since we're determining whether B.Foo() overrides A.Foo(),
                /// we need to do a signature based comparision and consider them equal.

                if (a == b)
                        return true;

                if (a.IsGenericParameter && b.IsGenericParameter &&
                    (a.DeclaringMethod != null) && (b.DeclaringMethod != null)) {
                        return a.GenericParameterPosition == b.GenericParameterPosition;
                }

                if (a.IsArray && b.IsArray) {
                        if (a.GetArrayRank () != b.GetArrayRank ())
                                return false;

                        return IsSignatureEqual (GetElementType (a), GetElementType (b));
                }

                if (a.IsByRef && b.IsByRef)
                        return IsSignatureEqual (GetElementType (a), GetElementType (b));

                if (IsGenericType (a) && IsGenericType (b)) {
                        if (DropGenericTypeArguments (a) != DropGenericTypeArguments (b))
                                return false;

                        Type[] aargs = GetTypeArguments (a);
                        Type[] bargs = GetTypeArguments (b);

                        if (aargs.Length != bargs.Length)
                                return false;

                        for (int i = 0; i < aargs.Length; i++) {
                                if (!IsSignatureEqual (aargs [i], bargs [i]))
                                        return false;
                        }

                        return true;
                }

                return false;
        }

        //
        // Returns whether the array of memberinfos contains the given method
        //
        public static bool ArrayContainsMethod (MemberInfo [] array, MethodBase new_method, bool ignoreDeclType)
        {
                Type [] new_args = TypeManager.GetParameterData (new_method).Types;
                
                foreach (MethodBase method in array) {
                        if (!ignoreDeclType && method.DeclaringType != new_method.DeclaringType)
                                continue;
                
                        if (method.Name != new_method.Name)
                                continue;

                        if (method is MethodInfo && new_method is MethodInfo &&
                                !IsSignatureEqual (
                                        TypeToCoreType (((MethodInfo) method).ReturnType),
                                        TypeToCoreType (((MethodInfo) new_method).ReturnType)))
                                continue;
                        
                        Type [] old_args = TypeManager.GetParameterData (method).Types;
                        int old_count = old_args.Length;
                        int i;
                        
                        if (new_args.Length != old_count)
                                continue;
                        
                        for (i = 0; i < old_count; i++){
                                if (!IsSignatureEqual (old_args [i], new_args [i]))
                                        break;
                        }
                        if (i != old_count)
                                continue;

                        return true;
                }
                
                return false;
        }
        
        //
        // We copy methods from `new_members' into `target_list' if the signature
        // for the method from in the new list does not exist in the target_list
        //
        // The name is assumed to be the same.
        //
        public static ArrayList CopyNewMethods (ArrayList target_list, IList new_members)
        {
                if (target_list == null){
                        target_list = new ArrayList ();

                        foreach (MemberInfo mi in new_members){
                                if (mi is MethodBase)
                                        target_list.Add (mi);
                        }
                        return target_list;
                }
                
                MemberInfo [] target_array = new MemberInfo [target_list.Count];
                target_list.CopyTo (target_array, 0);
                
                foreach (MemberInfo mi in new_members){
                        MethodBase new_method = (MethodBase) mi;
                        
                        if (!ArrayContainsMethod (target_array, new_method, true))
                                target_list.Add (new_method);
                }
                return target_list;
        }

#region Generics
        // <remarks>
        //   Tracks the generic parameters.
        // </remarks>
        static PtrHashtable builder_to_type_param;

        public static void AddTypeParameter (Type t, TypeParameter tparam)
        {
                if (!builder_to_type_param.Contains (t))
                        builder_to_type_param.Add (t, tparam);
        }

        public static TypeParameter LookupTypeParameter (Type t)
        {
                return (TypeParameter) builder_to_type_param [t];
        }

        // This method always return false for non-generic compiler,
        // while Type.IsGenericParameter is returned if it is supported.
        public static bool IsGenericParameter (Type type)
        {
                return type.IsGenericParameter;
        }

        public static int GenericParameterPosition (Type type)
        {
                return type.GenericParameterPosition;
        }

        public static bool IsGenericType (Type type)
        {
                return type.IsGenericType;
        }

        public static bool IsGenericTypeDefinition (Type type)
        {
                return type.IsGenericTypeDefinition;
        }

        public static bool ContainsGenericParameters (Type type)
        {
                return type.ContainsGenericParameters;
        }

        public static FieldInfo GetGenericFieldDefinition (FieldInfo fi)
        {
                if (fi.DeclaringType.IsGenericTypeDefinition ||
                    !fi.DeclaringType.IsGenericType)
                        return fi;

                Type t = fi.DeclaringType.GetGenericTypeDefinition ();
                BindingFlags bf = BindingFlags.Public | BindingFlags.NonPublic |
                        BindingFlags.Static | BindingFlags.Instance | BindingFlags.DeclaredOnly;

                // TODO: use CodeGen.Module.Builder.ResolveField (fi.MetadataToken);
                foreach (FieldInfo f in t.GetFields (bf))
                        if (f.MetadataToken == fi.MetadataToken)
                                return f;

                return fi;
        }

        public static bool IsEqual (Type a, Type b)
        {
                if (a.Equals (b)) {
                        // MS BCL returns true even if enum types are different
                        if (a.BaseType == TypeManager.enum_type || b.BaseType == TypeManager.enum_type)
                                return a.FullName == b.FullName;

                        // Some types are never equal
                        if (a == TypeManager.null_type || a == InternalType.AnonymousMethod)
                                return false;

                        return true;
                }

                if (IsGenericParameter (a) && IsGenericParameter (b)) {
                        // TODO: needs more testing before cleaning up
                        //if (a.DeclaringMethod != b.DeclaringMethod &&
                        //    (a.DeclaringMethod == null || b.DeclaringMethod == null))
                        //      return false;
                        return a.GenericParameterPosition == b.GenericParameterPosition;
                }

                if (a.IsArray && b.IsArray) {
                        if (a.GetArrayRank () != b.GetArrayRank ())
                                return false;
                        return IsEqual (GetElementType (a), GetElementType (b));
                }

                if (a.IsByRef && b.IsByRef)
                        return IsEqual (a.GetElementType (), b.GetElementType ());

                if (IsGenericType (a) && IsGenericType (b)) {
                        Type adef = DropGenericTypeArguments (a);
                        Type bdef = DropGenericTypeArguments (b);

                        if (adef != bdef)
                                return false;

                        if (adef.IsEnum && bdef.IsEnum)
                                return true;

                        Type[] aargs = GetTypeArguments (a);
                        Type[] bargs = GetTypeArguments (b);

                        if (aargs.Length != bargs.Length)
                                return false;

                        for (int i = 0; i < aargs.Length; i++) {
                                if (!IsEqual (aargs [i], bargs [i]))
                                        return false;
                        }

                        return true;
                }

                return false;
        }

        public static bool IsEqual (Type[] a, Type[] b)
        {
                if (a == null || b == null || a.Length != b.Length)
                        return false;

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

                                return false;
                        }
                
                        if (!IsEqual (a [i], b [i]))
                                return false;
                }

                return true;
        }

        public static Type DropGenericTypeArguments (Type t)
        {
                if (!t.IsGenericType)
                        return t;
                // Micro-optimization: a generic typebuilder is always a generic type definition
                if (t is TypeBuilder)
                        return t;
                return t.GetGenericTypeDefinition ();
        }

        public static MethodBase DropGenericMethodArguments (MethodBase m)
        {
                if (m.IsGenericMethod)
                  m = ((MethodInfo) m).GetGenericMethodDefinition ();

                Type t = m.DeclaringType;
                if (!t.IsGenericType || t.IsGenericTypeDefinition)
                        return m;

                t = t.GetGenericTypeDefinition ();
                BindingFlags bf = BindingFlags.Public | BindingFlags.NonPublic |
                        BindingFlags.Static | BindingFlags.Instance | BindingFlags.DeclaredOnly;

#if MS_COMPATIBLE
                // TODO: use CodeGen.Module.Builder.ResolveMethod ()
                return m;
#endif

                if (m is ConstructorInfo) {
                        foreach (ConstructorInfo c in t.GetConstructors (bf))
                                if (c.MetadataToken == m.MetadataToken)
                                        return c;
                } else {
                        foreach (MethodBase mb in t.GetMethods (bf))
                                if (mb.MetadataToken == m.MetadataToken)
                                        return mb;
                }

                return m;
        }

        public static Type[] GetGenericArguments (MethodBase mi)
        {
                return mi.GetGenericArguments () ?? Type.EmptyTypes;
        }

        public static Type[] GetTypeArguments (Type t)
        {
                DeclSpace tc = LookupDeclSpace (t);
                if (tc != null) {
                        if (!tc.IsGeneric)
                                return Type.EmptyTypes;

                        TypeParameter[] tparam = tc.TypeParameters;
                        Type[] ret = new Type [tparam.Length];
                        for (int i = 0; i < tparam.Length; i++) {
                                ret [i] = tparam [i].Type;
                                if (ret [i] == null)
                                        throw new InternalErrorException ();
                        }

                        return ret;
                } else
                        return t.GetGenericArguments ();
        }
                        
        public static GenericConstraints GetTypeParameterConstraints (Type t)
        {
                if (!t.IsGenericParameter)
                        throw new InvalidOperationException ();

                TypeParameter tparam = LookupTypeParameter (t);
                if (tparam != null)
                        return tparam.GenericConstraints;

                return ReflectionConstraints.GetConstraints (t);
        }

        public static bool HasGenericArguments (Type t)
        {
                return GetNumberOfTypeArguments (t) > 0;
        }

        public static int GetNumberOfTypeArguments (Type t)
        {
                if (t.IsGenericParameter)
                        return 0;
                DeclSpace tc = LookupDeclSpace (t);
                if (tc != null)
                        return tc.IsGeneric ? tc.CountTypeParameters : 0;
                else
                        return t.IsGenericType ? t.GetGenericArguments ().Length : 0;
        }

        /// <summary>
        ///   Check whether `type' and `parent' are both instantiations of the same
        ///   generic type.  Note that we do not check the type parameters here.
        /// </summary>
        public static bool IsInstantiationOfSameGenericType (Type type, Type parent)
        {
                int tcount = GetNumberOfTypeArguments (type);
                int pcount = GetNumberOfTypeArguments (parent);

                if (tcount != pcount)
                        return false;

                type = DropGenericTypeArguments (type);
                parent = DropGenericTypeArguments (parent);

                return type.Equals (parent);
        }

        /// <summary>
        ///   Whether `mb' is a generic method definition.
        /// </summary>
        public static bool IsGenericMethodDefinition (MethodBase mb)
        {
                if (mb.DeclaringType is TypeBuilder) {
                        IMethodData method = (IMethodData) builder_to_method [mb];
                        if (method == null)
                                return false;

                        return method.GenericMethod != null;
                }

                return mb.IsGenericMethodDefinition;
        }

        /// <summary>
        ///   Whether `mb' is a generic method.
        /// </summary>
        public static bool IsGenericMethod (MethodBase mb)
        {
                return mb.IsGenericMethod;
        }

        public static bool IsNullableType (Type t)
        {
                return generic_nullable_type == DropGenericTypeArguments (t);
        }
#endregion

#region MemberLookup implementation
        
        //
        // Whether we allow private members in the result (since FindMembers
        // uses NonPublic for both protected and private), we need to distinguish.
        //

        internal class Closure {
                internal bool     private_ok;

                // Who is invoking us and which type is being queried currently.
                internal Type     invocation_type;
                internal Type     qualifier_type;

                // The assembly that defines the type is that is calling us
                internal Assembly invocation_assembly;
                internal IList almost_match;

                private bool CheckValidFamilyAccess (bool is_static, MemberInfo m)
                {
                        if (invocation_type == null)
                                return false;

                        if (is_static && qualifier_type == null)
                                // It resolved from a simple name, so it should be visible.
                                return true;

                        if (IsNestedChildOf (invocation_type, m.DeclaringType))
                                return true;

                        for (Type t = invocation_type; t != null; t = t.DeclaringType) {
                                if (!IsFamilyAccessible (t, m.DeclaringType))
                                        continue;

                                // Although a derived class can access protected members of its base class
                                // it cannot do so through an instance of the base class (CS1540).
                                // => Ancestry should be: declaring_type ->* invocation_type ->*  qualified_type
                                if (is_static || qualifier_type == null ||
                                    IsInstantiationOfSameGenericType (t, qualifier_type) ||
                                    IsFamilyAccessible (qualifier_type, t))
                                        return true;
                        }

                        if (almost_match != null)
                                almost_match.Add (m);

                        return false;
                }
                
                //
                // This filter filters by name + whether it is ok to include private
                // members in the search
                //
                internal bool Filter (MemberInfo m, object filter_criteria)
                {
                        //
                        // Hack: we know that the filter criteria will always be in the
                        // `closure' // fields. 
                        //

                        if ((filter_criteria != null) && (m.Name != (string) filter_criteria))
                                return false;

                        if (((qualifier_type == null) || (qualifier_type == invocation_type)) &&
                            (invocation_type != null) &&
                            IsPrivateAccessible (m.DeclaringType, invocation_type))
                                return true;

                        //
                        // Ugly: we need to find out the type of `m', and depending
                        // on this, tell whether we accept or not
                        //
                        if (m is MethodBase){
                                MethodBase mb = (MethodBase) m;
                                MethodAttributes ma = mb.Attributes & MethodAttributes.MemberAccessMask;

                                if (ma == MethodAttributes.Public)
                                        return true;

                                if (ma == MethodAttributes.PrivateScope)
                                        return false;

                                if (ma == MethodAttributes.Private)
                                        return private_ok ||
                                                IsPrivateAccessible (invocation_type, m.DeclaringType) ||
                                                IsNestedChildOf (invocation_type, m.DeclaringType);

                                if (TypeManager.IsThisOrFriendAssembly (invocation_assembly, mb.DeclaringType.Assembly)) {
                                        if (ma == MethodAttributes.Assembly || ma == MethodAttributes.FamORAssem)
                                                return true;
                                } else {
                                        if (ma == MethodAttributes.Assembly || ma == MethodAttributes.FamANDAssem)
                                                return false;
                                }

                                // Family, FamORAssem or FamANDAssem
                                return CheckValidFamilyAccess (mb.IsStatic, m);
                        }
                        
                        if (m is FieldInfo){
                                FieldInfo fi = (FieldInfo) m;
                                FieldAttributes fa = fi.Attributes & FieldAttributes.FieldAccessMask;

                                if (fa == FieldAttributes.Public)
                                        return true;

                                if (fa == FieldAttributes.PrivateScope)
                                        return false;

                                if (fa == FieldAttributes.Private)
                                        return private_ok ||
                                                IsPrivateAccessible (invocation_type, m.DeclaringType) ||
                                                IsNestedChildOf (invocation_type, m.DeclaringType);

                                if (TypeManager.IsThisOrFriendAssembly (invocation_assembly, fi.DeclaringType.Assembly)) {
                                        if ((fa == FieldAttributes.Assembly) ||
                                            (fa == FieldAttributes.FamORAssem))
                                                return true;
                                } else {
                                        if ((fa == FieldAttributes.Assembly) ||
                                            (fa == FieldAttributes.FamANDAssem))
                                                return false;
                                }

                                // Family, FamORAssem or FamANDAssem
                                return CheckValidFamilyAccess (fi.IsStatic, m);
                        }

                        //
                        // EventInfos and PropertyInfos, return true because they lack
                        // permission information, so we need to check later on the methods.
                        //
                        return true;
                }
        }

        static Closure closure;
        static MemberFilter FilterWithClosure_delegate;

        //
        // Looks up a member called `name' in the `queried_type'.  This lookup
        // is done by code that is contained in the definition for `invocation_type'
        // through a qualifier of type `qualifier_type' (or null if there is no qualifier).
        //
        // `invocation_type' is used to check whether we're allowed to access the requested
        // member wrt its protection level.
        //
        // When called from MemberAccess, `qualifier_type' is the type which is used to access
        // the requested member (`class B { A a = new A (); a.foo = 5; }'; here invocation_type
        // is B and qualifier_type is A).  This is used to do the CS1540 check.
        //
        // When resolving a SimpleName, `qualifier_type' is null.
        //
        // The `qualifier_type' is used for the CS1540 check; it's normally either null or
        // the same than `queried_type' - except when we're being called from BaseAccess;
        // in this case, `invocation_type' is the current type and `queried_type' the base
        // type, so this'd normally trigger a CS1540.
        //
        // The binding flags are `bf' and the kind of members being looked up are `mt'
        //
        // The return value always includes private members which code in `invocation_type'
        // is allowed to access (using the specified `qualifier_type' if given); only use
        // BindingFlags.NonPublic to bypass the permission check.
        //
        // The 'almost_match' argument is used for reporting error CS1540.
        //
        // Returns an array of a single element for everything but Methods/Constructors
        // that might return multiple matches.
        //
        public static MemberInfo [] MemberLookup (Type invocation_type, Type qualifier_type,
                                                  Type queried_type, MemberTypes mt,
                                                  BindingFlags original_bf, string name, IList almost_match)
        {
                Timer.StartTimer (TimerType.MemberLookup);

                MemberInfo[] retval = RealMemberLookup (invocation_type, qualifier_type,
                                                        queried_type, mt, original_bf, name, almost_match);

                Timer.StopTimer (TimerType.MemberLookup);

                return retval;
        }

        static MemberInfo [] RealMemberLookup (Type invocation_type, Type qualifier_type,
                                               Type queried_type, MemberTypes mt,
                                               BindingFlags original_bf, string name, IList almost_match)
        {
                BindingFlags bf = original_bf;
                
                ArrayList method_list = null;
                Type current_type = queried_type;
                bool searching = (original_bf & BindingFlags.DeclaredOnly) == 0;
                bool skip_iface_check = true, used_cache = false;
                bool always_ok_flag = invocation_type != null && IsNestedChildOf (invocation_type, queried_type);

                closure.invocation_type = invocation_type;
                closure.invocation_assembly = invocation_type != null ? invocation_type.Assembly : null;
                closure.qualifier_type = qualifier_type;
                closure.almost_match = almost_match;

                // This is from the first time we find a method
                // in most cases, we do not actually find a method in the base class
                // so we can just ignore it, and save the arraylist allocation
                MemberInfo [] first_members_list = null;
                bool use_first_members_list = false;
                
                do {
                        MemberInfo [] list;

                        //
                        // `NonPublic' is lame, because it includes both protected and
                        // private methods, so we need to control this behavior by
                        // explicitly tracking if a private method is ok or not.
                        //
                        // The possible cases are:
                        //    public, private and protected (internal does not come into the
                        //    equation)
                        //
                        if ((invocation_type != null) &&
                            ((invocation_type == current_type) ||
                             IsNestedChildOf (invocation_type, current_type)) ||
                            always_ok_flag)
                                bf = original_bf | BindingFlags.NonPublic;
                        else
                                bf = original_bf;

                        closure.private_ok = (original_bf & BindingFlags.NonPublic) != 0;

                        Timer.StopTimer (TimerType.MemberLookup);

                        list = MemberLookup_FindMembers (current_type, mt, bf, name, out used_cache);

                        Timer.StartTimer (TimerType.MemberLookup);

                        //
                        // When queried for an interface type, the cache will automatically check all
                        // inherited members, so we don't need to do this here.  However, this only
                        // works if we already used the cache in the first iteration of this loop.
                        //
                        // If we used the cache in any further iteration, we can still terminate the
                        // loop since the cache always looks in all base classes.
                        //

                        if (used_cache)
                                searching = false;
                        else
                                skip_iface_check = false;

                        if (current_type == TypeManager.object_type)
                                searching = false;
                        else {
                                current_type = current_type.BaseType;
                                
                                //
                                // This happens with interfaces, they have a null
                                // basetype.  Look members up in the Object class.
                                //
                                if (current_type == null) {
                                        current_type = TypeManager.object_type;
                                        searching = true;
                                }
                        }
                        
                        if (list.Length == 0)
                                continue;

                        //
                        // Events and types are returned by both `static' and `instance'
                        // searches, which means that our above FindMembers will
                        // return two copies of the same.
                        //
                        if (list.Length == 1 && !(list [0] is MethodBase)){
                                return list;
                        }

                        //
                        // Multiple properties: we query those just to find out the indexer
                        // name
                        //
                        if (list [0] is PropertyInfo)
                                return list;

                        //
                        // We found an event: the cache lookup returns both the event and
                        // its private field.
                        //
                        if (list [0] is EventInfo) {
                                if ((list.Length == 2) && (list [1] is FieldInfo))
                                        return new MemberInfo [] { list [0] };

                                return list;
                        }

                        //
                        // We found methods, turn the search into "method scan"
                        // mode.
                        //

                        if (first_members_list != null) {
                                if (use_first_members_list) {
                                        method_list = CopyNewMethods (method_list, first_members_list);
                                        use_first_members_list = false;
                                }
                                
                                method_list = CopyNewMethods (method_list, list);
                        } else {
                                first_members_list = list;
                                use_first_members_list = true;
                                mt &= (MemberTypes.Method | MemberTypes.Constructor);
                        }
                } while (searching);

                if (use_first_members_list)
                        return first_members_list;

                if (method_list != null && method_list.Count > 0) {
                        return (MemberInfo []) method_list.ToArray (typeof (MemberInfo));
                }
                //
                // This happens if we already used the cache in the first iteration, in this case
                // the cache already looked in all interfaces.
                //
                if (skip_iface_check)
                        return null;

                //
                // Interfaces do not list members they inherit, so we have to
                // scan those.
                // 
                if (!queried_type.IsInterface)
                        return null;

                if (queried_type.IsArray)
                        queried_type = TypeManager.array_type;
                
                Type [] ifaces = GetInterfaces (queried_type);
                if (ifaces == null)
                        return null;
                
                foreach (Type itype in ifaces){
                        MemberInfo [] x;

                        x = MemberLookup (null, null, itype, mt, bf, name, null);
                        if (x != null)
                                return x;
                }
                                        
                return null;
        }

        public const BindingFlags AllMembers = BindingFlags.Public | BindingFlags.NonPublic |
                                                                        BindingFlags.Static | BindingFlags.Instance | 
                                                                        BindingFlags.DeclaredOnly;

        // Currently is designed to work with external types only
        public static PropertyInfo GetPropertyFromAccessor (MethodBase mb)
        {
                if (!mb.IsSpecialName)
                        return null;

                string name = mb.Name;
                if (name.Length < 5)
                        return null;

                if (name [3] != '_')
                        return null;

                if (name.StartsWith ("get") || name.StartsWith ("set")) {
                        MemberInfo[] pi = mb.DeclaringType.FindMembers (MemberTypes.Property, AllMembers,
                                Type.FilterName, name.Substring (4));

                        if (pi == null)
                                return null;

                        // This can happen when property is indexer (it can have same name but different parameters)
                        foreach (PropertyInfo p in pi) {
                                foreach (MethodInfo p_mi in p.GetAccessors (true)) {
                                        if (p_mi == mb || TypeManager.GetParameterData (p_mi).Equals (TypeManager.GetParameterData (mb)))
                                                return p;
                                }
                        }
                }

                return null;
        }

        // Currently is designed to work with external types only
        public static MemberInfo GetEventFromAccessor (MethodBase mb)
        {
                if (!mb.IsSpecialName)
                        return null;

                string name = mb.Name;
                if (name.Length < 5)
                        return null;

                if (name.StartsWith ("add_"))
                        return mb.DeclaringType.GetEvent (name.Substring (4), AllMembers);

                if (name.StartsWith ("remove_"))
                        return mb.DeclaringType.GetEvent (name.Substring (7), AllMembers);

                return null;
        }

        // Tests whether external method is really special
        public static bool IsSpecialMethod (MethodBase mb)
        {
                if (!mb.IsSpecialName)
                        return false;

                IMethodData md = TypeManager.GetMethod (mb);
                if (md != null) 
                        return (md is AbstractPropertyEventMethod || md is Operator);

                PropertyInfo pi = GetPropertyFromAccessor (mb);
                if (pi != null)
                        return IsValidProperty (pi);
                                
                if (GetEventFromAccessor (mb) != null)
                        return true;

                string name = mb.Name;
                if (name.StartsWith ("op_"))
                        return Operator.GetName (name) != null;

                return false;
        }

        // Tests whether imported property is valid C# property.
        // TODO: It seems to me that we should do a lot of sanity tests before
        // we accept property as C# property
        static bool IsValidProperty (PropertyInfo pi)
        {
                MethodInfo get_method = pi.GetGetMethod (true);
                MethodInfo set_method = pi.GetSetMethod (true);
                int g_count = 0;
                int s_count = 0;
                if (get_method != null && set_method != null) {
                        g_count = get_method.GetParameters ().Length;
                        s_count = set_method.GetParameters ().Length;
                        if (g_count + 1 != s_count)
                                return false;
                } else if (get_method != null) {
                        g_count = get_method.GetParameters ().Length;
                } else if (set_method != null) {
                        s_count = set_method.GetParameters ().Length;
                }

                //
                // DefaultMemberName and indexer name has to match to identify valid C# indexer
                //
                PredefinedAttribute pa = PredefinedAttributes.Get.DefaultMember;
                if ((s_count > 1 || g_count > 0) && pa.IsDefined) {
                        object[] o = pi.DeclaringType.GetCustomAttributes (pa.Type, false);
                        if (o.Length == 0)
                                return false;
                        
                        DefaultMemberAttribute dma = (DefaultMemberAttribute) o [0];
                        if (dma.MemberName != pi.Name)
                                return false;
                        if (get_method != null && "get_" + dma.MemberName != get_method.Name)
                                return false;
                        if (set_method != null && "set_" + dma.MemberName != set_method.Name)
                                return false;
                }

                return true;
        }

#endregion
        
}

        class InternalType
        {
                public static readonly Type AnonymousMethod = typeof (AnonymousMethodBody);
                public static readonly Type Arglist = typeof (ArglistAccess);
                public static readonly Type Dynamic = new DynamicType ();
                public static readonly Type MethodGroup = typeof (MethodGroupExpr);
        }

/// <summary>
///   There is exactly one instance of this class per type.
/// </summary>
public sealed class TypeHandle : IMemberContainer {
        public readonly IMemberContainer BaseType;

        readonly int id = ++next_id;
        static int next_id = 0;

        static TypeHandle ()
        {
                Reset ();
        }

        /// <summary>
        ///   Lookup a TypeHandle instance for the given type.  If the type doesn't have
        ///   a TypeHandle yet, a new instance of it is created.  This static method
        ///   ensures that we'll only have one TypeHandle instance per type.
        /// </summary>
        private static TypeHandle GetTypeHandle (Type t)
        {
                TypeHandle handle = (TypeHandle) type_hash [t];
                if (handle != null)
                        return handle;

                handle = new TypeHandle (t);
                type_hash.Add (t, handle);
                return handle;
        }

        public static MemberCache GetMemberCache (Type t)
        {
                return GetTypeHandle (t).MemberCache;
        }
        
        public static void CleanUp ()
        {
                type_hash = null;
        }

        public static void Reset ()
        {
                type_hash = new PtrHashtable ();
        }

        /// <summary>
        ///   Returns the TypeHandle for TypeManager.object_type.
        /// </summary>
        public static IMemberContainer ObjectType {
                get {
                        if (object_type != null)
                                return object_type;

                        object_type = GetTypeHandle (TypeManager.object_type);

                        return object_type;
                }
        }

        /// <summary>
        ///   Returns the TypeHandle for TypeManager.array_type.
        /// </summary>
        public static TypeHandle ArrayType {
                get {
                        if (array_type != null)
                                return array_type;

                        array_type = GetTypeHandle (TypeManager.array_type);

                        return array_type;
                }
        }

        private static PtrHashtable type_hash;

        private static TypeHandle object_type = null;
        private static TypeHandle array_type = null;

        private Type type;
        private string full_name;
        private bool is_interface;
        private MemberCache member_cache;
        private MemberCache base_cache;

        private TypeHandle (Type type)
        {
                this.type = type;
                full_name = type.FullName != null ? type.FullName : type.Name;
                if (type.BaseType != null) {
                        base_cache = TypeManager.LookupMemberCache (type.BaseType);
                        BaseType = base_cache.Container;
                } else if (type.IsInterface)
                        base_cache = TypeManager.LookupBaseInterfacesCache (type);
                this.is_interface = type.IsInterface || TypeManager.IsGenericParameter (type);
                this.member_cache = new MemberCache (this);
        }

        // IMemberContainer methods

        public string Name {
                get {
                        return full_name;
                }
        }

        public Type Type {
                get {
                        return type;
                }
        }

        public MemberCache BaseCache {
                get {
                        return base_cache;
                }
        }

        public bool IsInterface {
                get {
                        return is_interface;
                }
        }

        public MemberList GetMembers (MemberTypes mt, BindingFlags bf)
        {
                MemberInfo [] members;

                if (type is GenericTypeParameterBuilder)
                        return MemberList.Empty;

#if MS_COMPATIBLE
                type = TypeManager.DropGenericTypeArguments (type);
#endif
                if (mt == MemberTypes.Event)
                        members = type.GetEvents (bf | BindingFlags.DeclaredOnly);
                else
                        members = type.FindMembers (mt, bf | BindingFlags.DeclaredOnly,
                                                                                null, null);

                if (members.Length == 0)
                        return MemberList.Empty;

                Array.Reverse (members);
                return new MemberList (members);
        }

        // IMemberFinder methods

        public MemberList FindMembers (MemberTypes mt, BindingFlags bf, string name,
                                       MemberFilter filter, object criteria)
        {
                return new MemberList (member_cache.FindMembers (mt, bf, name, filter, criteria));
        }

        public MemberCache MemberCache {
                get {
                        return member_cache;
                }
        }

        public override string ToString ()
        {
                if (BaseType != null)
                        return "TypeHandle (" + id + "," + Name + " : " + BaseType + ")";
                else
                        return "TypeHandle (" + id + "," + Name + ")";
        }
}
}