context: //
  // import.cs: System.Reflection conversions
  //
  // Authors: Marek Safar (marek.safar@gmail.com)
  //
  // Dual licensed under the terms of the MIT X11 or GNU GPL
  //
  // Copyright 2009-2011 Novell, Inc
  // Copyright 2011-2012 Xamarin, Inc (http://www.xamarin.com)
  //
  
  using System;
  using System.Runtime.CompilerServices;
  using System.Linq;
  using System.Collections.Generic;
  
  #if STATIC
  using MetaType = IKVM.Reflection.Type;
  using IKVM.Reflection;
  using IKVM.Reflection.Emit;
  #else
  using MetaType = System.Type;
  using System.Reflection;
  using System.Reflection.Emit;
  #endif
  
  namespace Mono.CSharp
  {
  	public abstract class MetadataImporter
  	{
  		//
  		// Dynamic types reader with additional logic to reconstruct a dynamic
  		// type using DynamicAttribute values
  		//
  		protected struct DynamicTypeReader
  		{
  			static readonly bool[] single_attribute = { true };
  
  			public int Position;
  			bool[] flags;
  
  			// There is no common type for CustomAttributeData and we cannot
  			// use ICustomAttributeProvider
  			object provider;
  
  			//
  			// A member provider which can be used to get CustomAttributeData
  			//
  			public DynamicTypeReader (object provider)
  			{
  				Position = 0;
  				flags = null;
  				this.provider = provider;
  			}
  
  			//
  			// Returns true when object at local position has dynamic attribute flag
  			//
  			public bool IsDynamicObject ()
  			{
  				if (provider != null)
  					ReadAttribute ();
  
  				return flags != null && Position < flags.Length && flags[Position];
  			}
  
  			//
  			// Returns true when DynamicAttribute exists
  			//
  			public bool HasDynamicAttribute ()
  			{
  				if (provider != null)
  					ReadAttribute ();
  
  				return flags != null;
  			}
  
  			IList<CustomAttributeData> GetCustomAttributes ()
  			{
  				var mi = provider as MemberInfo;
  				if (mi != null)
  					return CustomAttributeData.GetCustomAttributes (mi);
  
  				var pi = provider as ParameterInfo;
  				if (pi != null)
  					return CustomAttributeData.GetCustomAttributes (pi);
  
  				provider = null;
  				return null;
  			}
  
  			void ReadAttribute ()
  			{
  				var cad = GetCustomAttributes ();
  				if (cad == null) {
  					return;
  				}
  
  				if (cad.Count > 0) {
  					foreach (var ca in cad) {
  						var dt = ca.Constructor.DeclaringType;
  						if (dt.Name != "DynamicAttribute" || dt.Namespace != CompilerServicesNamespace)
  							continue;
  
  						if (ca.ConstructorArguments.Count == 0) {
  							flags = single_attribute;
  							break;
  						}
  
  						var arg_type = ca.ConstructorArguments[0].ArgumentType;
  
  						if (arg_type.IsArray && MetaType.GetTypeCode (arg_type.GetElementType ()) == TypeCode.Boolean) {
  							var carg = (IList<CustomAttributeTypedArgument>) ca.ConstructorArguments[0].Value;
  							flags = new bool[carg.Count];
  							for (int i = 0; i < flags.Length; ++i) {
  								if (MetaType.GetTypeCode (carg[i].ArgumentType) == TypeCode.Boolean)
  									flags[i] = (bool) carg[i].Value;
  							}
  
  							break;
  						}
  					}
  				}
  
  				provider = null;
  			}
  		}
  
  		protected readonly Dictionary<MetaType, TypeSpec> import_cache;
  		protected readonly Dictionary<MetaType, TypeSpec> compiled_types;
  		protected readonly Dictionary<Assembly, IAssemblyDefinition> assembly_2_definition;
  		protected readonly ModuleContainer module;
  
  		public static readonly string CompilerServicesNamespace = "System.Runtime.CompilerServices";
  
  		protected MetadataImporter (ModuleContainer module)
  		{
  			this.module = module;
  
  			import_cache = new Dictionary<MetaType, TypeSpec> (1024, ReferenceEquality<MetaType>.Default);
  			compiled_types = new Dictionary<MetaType, TypeSpec> (40, ReferenceEquality<MetaType>.Default);
  			assembly_2_definition = new Dictionary<Assembly, IAssemblyDefinition> (ReferenceEquality<Assembly>.Default);
  			IgnorePrivateMembers = true;
  		}
  
  		#region Properties
  
  		public ICollection<IAssemblyDefinition> Assemblies {
  			get {
  				return assembly_2_definition.Values;
  			}
  		}
  
  		public bool IgnorePrivateMembers { get; set; }
  
  		#endregion
  
  		public abstract void AddCompiledType (TypeBuilder builder, TypeSpec spec);
  		protected abstract MemberKind DetermineKindFromBaseType (MetaType baseType);
  		protected abstract bool HasVolatileModifier (MetaType[] modifiers);
  
  		public FieldSpec CreateField (FieldInfo fi, TypeSpec declaringType)
  		{
  			Modifiers mod;
  			var fa = fi.Attributes;
  			switch (fa & FieldAttributes.FieldAccessMask) {
  				case FieldAttributes.Public:
  					mod = Modifiers.PUBLIC;
  					break;
  				case FieldAttributes.Assembly:
  					mod = Modifiers.INTERNAL;
  					break;
  				case FieldAttributes.Family:
  					mod = Modifiers.PROTECTED;
  					break;
  				case FieldAttributes.FamORAssem:
  					mod = Modifiers.PROTECTED | Modifiers.INTERNAL;
  					break;
  				default:
  					// Ignore private fields (even for error reporting) to not require extra dependencies
  					if ((IgnorePrivateMembers && !declaringType.IsStruct) ||
  						HasAttribute (CustomAttributeData.GetCustomAttributes (fi), "CompilerGeneratedAttribute", CompilerServicesNamespace))
  						return null;
  
  					mod = Modifiers.PRIVATE;
  					break;
  			}
  
  			TypeSpec field_type;
  
  			try {
  				field_type = ImportType (fi.FieldType, new DynamicTypeReader (fi));
  
  				//
  				// Private field has private type which is not fixed buffer
  				//
  				if (field_type == null)
  					return null;
  			} catch (Exception e) {
  				// TODO: I should construct fake TypeSpec based on TypeRef signature
  				// but there is no way to do it with System.Reflection
  				throw new InternalErrorException (e, "Cannot import field `{0}.{1}' referenced in assembly `{2}'",
  					declaringType.GetSignatureForError (), fi.Name, declaringType.MemberDefinition.DeclaringAssembly);
  			}
  
  			var definition = new ImportedMemberDefinition (fi, field_type, this);
  
  			if ((fa & FieldAttributes.Literal) != 0) {
  				Constant c = field_type.Kind == MemberKind.MissingType ?
  					new NullConstant (InternalType.ErrorType, Location.Null) :
  					Constant.CreateConstantFromValue (field_type, fi.GetRawConstantValue (), Location.Null);
  				return new ConstSpec (declaringType, definition, field_type, fi, mod, c);
  			}
  
  			if ((fa & FieldAttributes.InitOnly) != 0) {
  				if (field_type.BuiltinType == BuiltinTypeSpec.Type.Decimal) {
  					var dc = ReadDecimalConstant (CustomAttributeData.GetCustomAttributes (fi));
  					if (dc != null)
  						return new ConstSpec (declaringType, definition, field_type, fi, mod, dc);
  				}
  
  				mod |= Modifiers.READONLY;
  			} else {
  				var req_mod = fi.GetRequiredCustomModifiers ();
  				if (req_mod.Length > 0 && HasVolatileModifier (req_mod))
  					mod |= Modifiers.VOLATILE;
  			}
  
  			if ((fa & FieldAttributes.Static) != 0) {
  				mod |= Modifiers.STATIC;
  			} else {
  				// Fixed buffers cannot be static
  				if (declaringType.IsStruct && field_type.IsStruct && field_type.IsNested &&
  					HasAttribute (CustomAttributeData.GetCustomAttributes (fi), "FixedBufferAttribute", CompilerServicesNamespace)) {
  
  					// TODO: Sanity check on field_type (only few types are allowed)
  					var element_field = CreateField (fi.FieldType.GetField (FixedField.FixedElementName), declaringType);
  					return new FixedFieldSpec (module, declaringType, definition, fi, element_field, mod);
  				}
  			}
  
  			return new FieldSpec (declaringType, definition, field_type, fi, mod);
  		}
  
  		public EventSpec CreateEvent (EventInfo ei, TypeSpec declaringType, MethodSpec add, MethodSpec remove)
  		{
  			add.IsAccessor = true;
  			remove.IsAccessor = true;
  
  			if (add.Modifiers != remove.Modifiers)
  				throw new NotImplementedException ("Different accessor modifiers " + ei.Name);
  
  			var event_type = ImportType (ei.EventHandlerType, new DynamicTypeReader (ei));
  			var definition = new ImportedMemberDefinition (ei, event_type,  this);
  			return new EventSpec (declaringType, definition, event_type, add.Modifiers, add, remove);
  		}
  
  		TypeParameterSpec[] CreateGenericParameters (MetaType type, TypeSpec declaringType)
  		{
  			var tparams = type.GetGenericArguments ();
  
  			int parent_owned_count;
  			if (type.IsNested) {
  				parent_owned_count = type.DeclaringType.GetGenericArguments ().Length;
  
  				//
  				// System.Reflection duplicates parent type parameters for each
  				// nested type with slightly modified properties (eg. different owner)
  				// This just makes things more complicated (think of cloned constraints)
  				// therefore we remap any nested type owned by parent using `type_cache'
  				// to the single TypeParameterSpec
  				//
  				if (declaringType != null && parent_owned_count > 0) {
  					int read_count = 0;
  					while (read_count != parent_owned_count) {
  						var tparams_count = declaringType.Arity;
  						if (tparams_count != 0) {
  							var parent_tp = declaringType.MemberDefinition.TypeParameters;
  							read_count += tparams_count;
  							for (int i = 0; i < tparams_count; i++) {
  								import_cache.Add (tparams[parent_owned_count - read_count + i], parent_tp[i]);
  							}
  						}
  
  						declaringType = declaringType.DeclaringType;
  					}
  				}			
  			} else {
  				parent_owned_count = 0;
  			}
  
  			if (tparams.Length - parent_owned_count == 0)
  				return null;
  
  			return CreateGenericParameters (parent_owned_count, tparams);
  		}
  
  		TypeParameterSpec[] CreateGenericParameters (int first, MetaType[] tparams)
  		{
  			var tspec = new TypeParameterSpec[tparams.Length - first];
  			for (int pos = first; pos < tparams.Length; ++pos) {
  				var type = tparams[pos];
  				int index = pos - first;
  
  				tspec[index] = (TypeParameterSpec) CreateType (type, new DynamicTypeReader (), false);
  			}
  
  			return tspec;
  		}
  
  		TypeSpec[] CreateGenericArguments (int first, MetaType[] tparams, DynamicTypeReader dtype)
  		{
  			++dtype.Position;
  
  			var tspec = new TypeSpec [tparams.Length - first];
  			for (int pos = first; pos < tparams.Length; ++pos) {
  				var type = tparams[pos];
  				int index = pos - first;
  
  				TypeSpec spec;
  				if (type.HasElementType) {
  					var element = type.GetElementType ();
  					++dtype.Position;
  					spec = ImportType (element, dtype);
  
  					if (!type.IsArray) {
  						throw new NotImplementedException ("Unknown element type " + type.ToString ());
  					}
  
  					spec = ArrayContainer.MakeType (module, spec, type.GetArrayRank ());
  				} else {
  					spec = CreateType (type, dtype, true);
  
  					//
  					// We treat nested generic types as inflated internally where
  					// reflection uses type definition
  					//
  					// class A<T> {
  					//    IFoo<A<T>> foo;	// A<T> is definition in this case
  					// }
  					//
  					if (!IsMissingType (type) && type.IsGenericTypeDefinition) {
  						var start_pos = spec.DeclaringType == null ? 0 : spec.DeclaringType.MemberDefinition.TypeParametersCount;
  						var targs = CreateGenericArguments (start_pos, type.GetGenericArguments (), dtype);
  						spec = spec.MakeGenericType (module, targs);
  					}
  				}
  
  				if (spec == null)
  					return null;
  
  				++dtype.Position;
  				tspec[index] = spec;
  			}
  
  			return tspec;
  		}
  
  		public MethodSpec CreateMethod (MethodBase mb, TypeSpec declaringType)
  		{
  			Modifiers mod = ReadMethodModifiers (mb, declaringType);
  			TypeParameterSpec[] tparams;
  
  			var parameters = CreateParameters (declaringType, mb.GetParameters (), mb);
  
  			if (mb.IsGenericMethod) {
  				if (!mb.IsGenericMethodDefinition)
  					throw new NotSupportedException ("assert");
  
  				tparams = CreateGenericParameters (0, mb.GetGenericArguments ());
  			} else {
  				tparams = null;
  			}
  
  			MemberKind kind;
  			TypeSpec returnType;
  			if (mb.MemberType == MemberTypes.Constructor) {
  				kind = MemberKind.Constructor;
  				returnType = module.Compiler.BuiltinTypes.Void;
  			} else {
  				//
  				// Detect operators and destructors
  				//
  				string name = mb.Name;
  				kind = MemberKind.Method;
  				if (tparams == null && !mb.DeclaringType.IsInterface && name.Length > 6) {
  					if ((mod & (Modifiers.STATIC | Modifiers.PUBLIC)) == (Modifiers.STATIC | Modifiers.PUBLIC)) {
  						if (name[2] == '_' && name[1] == 'p' && name[0] == 'o' && (mb.Attributes & MethodAttributes.SpecialName) != 0) {
  							var op_type = Operator.GetType (name);
  							if (op_type.HasValue && parameters.Count > 0 && parameters.Count < 3) {
  								kind = MemberKind.Operator;
  							}
  						}
  					} else if (parameters.IsEmpty && name == Destructor.MetadataName) {
  						kind = MemberKind.Destructor;
  						if (declaringType.BuiltinType == BuiltinTypeSpec.Type.Object) {
  							mod &= ~Modifiers.OVERRIDE;
  							mod |= Modifiers.VIRTUAL;
  						}
  					}
  				}
  
  				var mi = (MethodInfo) mb;
  				returnType = ImportType (mi.ReturnType, new DynamicTypeReader (mi.ReturnParameter));
  
  				// Cannot set to OVERRIDE without full hierarchy checks
  				// this flag indicates that the method could be override
  				// but further validation is needed
  				if ((mod & Modifiers.OVERRIDE) != 0) {
  					bool is_real_override = false;
  					if (kind == MemberKind.Method && declaringType.BaseType != null) {
  						var btype = declaringType.BaseType;
  						if (IsOverrideMethodBaseTypeAccessible (btype)) {
  							var filter = MemberFilter.Method (name, tparams != null ? tparams.Length : 0, parameters, null);
  							var candidate = MemberCache.FindMember (btype, filter, BindingRestriction.None);
  
  							//
  							// For imported class method do additional validation to be sure that metadata
  							// override flag was correct
  							// 
  							// Difference between protected internal and protected is ok
  							//
  							const Modifiers conflict_mask = Modifiers.AccessibilityMask & ~Modifiers.INTERNAL;
  							if (candidate != null && (candidate.Modifiers & conflict_mask) == (mod & conflict_mask) && !candidate.IsStatic) {
  								is_real_override = true;
  							}
  						}
  					}
  
  					if (!is_real_override) {
  						mod &= ~Modifiers.OVERRIDE;
  						if ((mod & Modifiers.SEALED) != 0)
  							mod &= ~Modifiers.SEALED;
  						else
  							mod |= Modifiers.VIRTUAL;
  					}
  				} else if (parameters.HasExtensionMethodType) {
  					mod |= Modifiers.METHOD_EXTENSION;
  				}
  			}
  
  			IMethodDefinition definition;
  			if (tparams != null) {
  				var gmd = new ImportedGenericMethodDefinition ((MethodInfo) mb, returnType, parameters, tparams, this);
  				foreach (var tp in gmd.TypeParameters) {
  					ImportTypeParameterTypeConstraints (tp, tp.GetMetaInfo ());
  				}
  
  				definition = gmd;
  			} else {
  				definition = new ImportedMethodDefinition (mb, returnType, parameters, this);
  			}
  
  			MethodSpec ms = new MethodSpec (kind, declaringType, definition, returnType, parameters, mod);
  			if (tparams != null)
  				ms.IsGeneric = true;
  
  			return ms;
  		}
  
  		bool IsOverrideMethodBaseTypeAccessible (TypeSpec baseType)
  		{
  			switch (baseType.Modifiers & Modifiers.AccessibilityMask) {
  			case Modifiers.PUBLIC:
  				return true;
  			case Modifiers.INTERNAL:
  				//
  				// Check whether imported method in base type is accessible from compiled
  				// context
  				//
  				return baseType.MemberDefinition.IsInternalAsPublic (module.DeclaringAssembly);
  			case Modifiers.PRIVATE:
  				return false;
  			default:
  				// protected
  				// protected internal
  				// 
  				// Method accessibility checks will be done later based on context
  				// where the method is called (CS0122 error will be reported for inaccessible)
  				//
  				return true;
  			}
  		}
  
  		//
  		// Imports System.Reflection parameters
  		//
  		AParametersCollection CreateParameters (TypeSpec parent, ParameterInfo[] pi, MethodBase method)
  		{
  			int varargs = method != null && (method.CallingConvention & CallingConventions.VarArgs) != 0 ? 1 : 0;
  
  			if (pi.Length == 0 && varargs == 0)
  				return ParametersCompiled.EmptyReadOnlyParameters;
  
  			TypeSpec[] types = new TypeSpec[pi.Length + varargs];
  			IParameterData[] par = new IParameterData[pi.Length + varargs];
  			bool is_params = false;
  			for (int i = 0; i < pi.Length; i++) {
  				ParameterInfo p = pi[i];
  				Parameter.Modifier mod = 0;
  				Expression default_value = null;
  				if (p.ParameterType.IsByRef) {
  					if ((p.Attributes & (ParameterAttributes.Out | ParameterAttributes.In)) == ParameterAttributes.Out)
  						mod = Parameter.Modifier.OUT;
  					else
  						mod = Parameter.Modifier.REF;
  
  					//
  					// Strip reference wrapping
  					//
  					var el = p.ParameterType.GetElementType ();
  					types[i] = ImportType (el, new DynamicTypeReader (p));	// TODO: 1-based positio to be csc compatible
  				} else if (i == 0 && method.IsStatic && (parent.Modifiers & Modifiers.METHOD_EXTENSION) != 0 &&
  					HasAttribute (CustomAttributeData.GetCustomAttributes (method), "ExtensionAttribute", CompilerServicesNamespace)) {
  					mod = Parameter.Modifier.This;
  					types[i] = ImportType (p.ParameterType, new DynamicTypeReader (p));
  				} else {
  					types[i] = ImportType (p.ParameterType, new DynamicTypeReader (p));
  
  					if (i >= pi.Length - 2 && types[i] is ArrayContainer) {
  						if (HasAttribute (CustomAttributeData.GetCustomAttributes (p), "ParamArrayAttribute", "System")) {
  							mod = Parameter.Modifier.PARAMS;
  							is_params = true;
  						}
  					}
  
  					if (!is_params && p.IsOptional) {
  						object value = p.RawDefaultValue;
  						var ptype = types[i];
  						if ((p.Attributes & ParameterAttributes.HasDefault) != 0 && ptype.Kind != MemberKind.TypeParameter && (value != null || TypeSpec.IsReferenceType (ptype))) {
  							if (value == null) {
  								default_value = Constant.CreateConstantFromValue (ptype, null, Location.Null);
  							} else {
  								default_value = ImportParameterConstant (value);
  
  								if (ptype.IsEnum) {
  									default_value = new EnumConstant ((Constant) default_value, ptype);
  								}
  							}
  
  							var attrs = CustomAttributeData.GetCustomAttributes (p);
  							for (int ii = 0; ii < attrs.Count; ++ii) {
  								var attr = attrs[ii];
  								var dt = attr.Constructor.DeclaringType;
  								if (dt.Namespace != CompilerServicesNamespace)
  									continue;
  
  								if (dt.Name == "CallerLineNumberAttribute" && (ptype.BuiltinType == BuiltinTypeSpec.Type.Int || Convert.ImplicitNumericConversionExists (module.Compiler.BuiltinTypes.Int, ptype)))
  									mod |= Parameter.Modifier.CallerLineNumber;
  								else if (dt.Name == "CallerFilePathAttribute" && Convert.ImplicitReferenceConversionExists (module.Compiler.BuiltinTypes.String, ptype))
  									mod |= Parameter.Modifier.CallerFilePath;
  								else if (dt.Name == "CallerMemberNameAttribute" && Convert.ImplicitReferenceConversionExists (module.Compiler.BuiltinTypes.String, ptype))
  									mod |= Parameter.Modifier.CallerMemberName;
  							}
  						} else if (value == Missing.Value) {
  							default_value = EmptyExpression.MissingValue;
  						} else if (value == null) {
  							default_value = new DefaultValueExpression (new TypeExpression (ptype, Location.Null), Location.Null);
  						} else if (ptype.BuiltinType == BuiltinTypeSpec.Type.Decimal) {
  							default_value = ImportParameterConstant (value);
  						}
  					}
  				}
  
  				par[i] = new ParameterData (p.Name, mod, default_value);
  			}
  
  			if (varargs != 0) {
  				par[par.Length - 1] = new ArglistParameter (Location.Null);
  				types[types.Length - 1] = InternalType.Arglist;
  			}
  
  			return method != null ?
  				new ParametersImported (par, types, varargs != 0, is_params) :
  				new ParametersImported (par, types, is_params);
  		}
  
  		//
  		// Returns null when the property is not valid C# property
  		//
  		public PropertySpec CreateProperty (PropertyInfo pi, TypeSpec declaringType, MethodSpec get, MethodSpec set)
  		{
  			Modifiers mod = 0;
  			AParametersCollection param = null;
  			TypeSpec type = null;
  			if (get != null) {
  				mod = get.Modifiers;
  				param = get.Parameters;
  				type = get.ReturnType;
  			}
  
  			bool is_valid_property = true;
  			if (set != null) {
  				if (set.ReturnType.Kind != MemberKind.Void)
  					is_valid_property = false;
  
  				var set_param_count = set.Parameters.Count - 1;
  
  				if (set_param_count < 0) {
  					set_param_count = 0;
  					is_valid_property = false;
  				}
  
  				var set_type = set.Parameters.Types[set_param_count];
  
  				if (mod == 0) {
  					AParametersCollection set_based_param;
  
  					if (set_param_count == 0) {
  						set_based_param = ParametersCompiled.EmptyReadOnlyParameters;
  					} else {
  						//
  						// Create indexer parameters based on setter method parameters (the last parameter has to be removed)
  						//
  						var data = new IParameterData[set_param_count];
  						var types = new TypeSpec[set_param_count];
  						Array.Copy (set.Parameters.FixedParameters, data, set_param_count);
  						Array.Copy (set.Parameters.Types, types, set_param_count);
  						set_based_param = new ParametersImported (data, types, set.Parameters.HasParams);
  					}
  
  					mod = set.Modifiers;
  					param = set_based_param;
  					type = set_type;
  				} else {
  					if (set_param_count != get.Parameters.Count)
  						is_valid_property = false;
  
  					if (get.ReturnType != set_type)
  						is_valid_property = false;
  
  					// Possible custom accessor modifiers
  					if ((mod & Modifiers.AccessibilityMask) != (set.Modifiers & Modifiers.AccessibilityMask)) {
  						var get_acc = mod & Modifiers.AccessibilityMask;
  						if (get_acc != Modifiers.PUBLIC) {
  							var set_acc = set.Modifiers & Modifiers.AccessibilityMask;
  							// If the accessor modifiers are not same, do extra restriction checks
  							if (get_acc != set_acc) {
  								var get_restr = ModifiersExtensions.IsRestrictedModifier (get_acc, set_acc);
  								var set_restr = ModifiersExtensions.IsRestrictedModifier (set_acc, get_acc);
  								if (get_restr && set_restr) {
  									is_valid_property = false; // Neither is more restrictive
  								}
  
  								if (get_restr) {
  									mod &= ~Modifiers.AccessibilityMask;
  									mod |= set_acc;
  								}
  							}
  						}
  					}
  				}
  			}
  
  			PropertySpec spec = null;
  			if (!param.IsEmpty) {
  				if (is_valid_property) {
  					var index_name = declaringType.MemberDefinition.GetAttributeDefaultMember ();
  					if (index_name == null) {
  						is_valid_property = false;
  					} else {
  						if (get != null) {
  							if (get.IsStatic)
  								is_valid_property = false;
  							if (get.Name.IndexOf (index_name, StringComparison.Ordinal) != 4)
  								is_valid_property = false;
  						}
  						if (set != null) {
  							if (set.IsStatic)
  								is_valid_property = false;
  							if (set.Name.IndexOf (index_name, StringComparison.Ordinal) != 4)
  								is_valid_property = false;
  						}
  					}
  
  					if (is_valid_property) {
  						spec = new IndexerSpec (declaringType, new ImportedParameterMemberDefinition (pi, type, param, this), type, param, pi, mod);
  					} else if (declaringType.MemberDefinition.IsComImport && param.FixedParameters[0].HasDefaultValue) {
  						//
  						// Enables support for properties with parameters (must have default value) of COM-imported types
  						//
  						is_valid_property = true;
  
  						for (int i = 0; i < param.FixedParameters.Length; ++i) {
  							if (!param.FixedParameters[i].HasDefaultValue) {
  								is_valid_property = false;
  								break;
  							}
  						}
  					}
  				}
  			}
  
  			if (spec == null)
  				spec = new PropertySpec (MemberKind.Property, declaringType, new ImportedMemberDefinition (pi, type, this), type, pi, mod);
  
  			if (!is_valid_property) {
  				spec.IsNotCSharpCompatible = true;
  				return spec;
  			}
  
  			if (set != null)
  				spec.Set = set;
  			if (get != null)
  				spec.Get = get;
  
  			return spec;
  		}
  
  		public TypeSpec CreateType (MetaType type)
  		{
  			return CreateType (type, new DynamicTypeReader (), true);
  		}
  
  		public TypeSpec CreateNestedType (MetaType type, TypeSpec declaringType)
  		{
  			return CreateType (type, declaringType, new DynamicTypeReader (type), false);
  		}
  
  		TypeSpec CreateType (MetaType type, DynamicTypeReader dtype, bool canImportBaseType)
  		{
  			TypeSpec declaring_type;
  			if (type.IsNested && !type.IsGenericParameter)
  				declaring_type = CreateType (type.DeclaringType, new DynamicTypeReader (type.DeclaringType), true);
  			else
  				declaring_type = null;
  
  			return CreateType (type, declaring_type, dtype, canImportBaseType);
  		}
  
  		protected TypeSpec CreateType (MetaType type, TypeSpec declaringType, DynamicTypeReader dtype, bool canImportBaseType)
  		{
  			TypeSpec spec;
  			if (import_cache.TryGetValue (type, out spec)) {
  				if (spec.BuiltinType == BuiltinTypeSpec.Type.Object) {
  					if (dtype.IsDynamicObject ())
  						return module.Compiler.BuiltinTypes.Dynamic;
  
  					return spec;
  				}
  
  				if (!spec.IsGeneric || type.IsGenericTypeDefinition)
  					return spec;
  
  				if (!dtype.HasDynamicAttribute ())
  					return spec;
  
  				// We've found same object in the cache but this one has a dynamic custom attribute
  				// and it's most likely dynamic version of same type IFoo<object> agains IFoo<dynamic>
  				// Do type resolve process again in that case
  
  				// TODO: Handle cases where they still unify
  			}
  
  			if (IsMissingType (type)) {
  				spec = new TypeSpec (MemberKind.MissingType, declaringType, new ImportedTypeDefinition (type, this), type, Modifiers.PUBLIC);
  				spec.MemberCache = MemberCache.Empty;
  				import_cache.Add (type, spec);
  				return spec;
  			}
  
  			if (type.IsGenericType && !type.IsGenericTypeDefinition) {
  				var type_def = type.GetGenericTypeDefinition ();
  
  				// Generic type definition can also be forwarded
  				if (compiled_types.TryGetValue (type_def, out spec))
  					return spec;
  
  				var targs = CreateGenericArguments (0, type.GetGenericArguments (), dtype);
  				if (targs == null)
  					return null;
  				if (declaringType == null) {
  					// Simple case, no nesting
  					spec = CreateType (type_def, null, new DynamicTypeReader (), canImportBaseType);
  					spec = spec.MakeGenericType (module, targs);
  				} else {
  					//
  					// Nested type case, converting .NET types like
  					// A`1.B`1.C`1<int, long, string> to typespec like
  					// A<int>.B<long>.C<string>
  					//
  					var nested_hierarchy = new List<TypeSpec> ();
  					while (declaringType.IsNested) {
  						nested_hierarchy.Add (declaringType);
  						declaringType = declaringType.DeclaringType;
  					}
  
  					int targs_pos = 0;
  					if (declaringType.Arity > 0) {
  						spec = declaringType.MakeGenericType (module, targs.Skip (targs_pos).Take (declaringType.Arity).ToArray ());
  						targs_pos = spec.Arity;
  					} else {
  						spec = declaringType;
  					}
  
  					for (int i = nested_hierarchy.Count; i != 0; --i) {
  						var t = nested_hierarchy [i - 1];
  						if (t.Kind == MemberKind.MissingType)
  							spec = t;
  						else
  							spec = MemberCache.FindNestedType (spec, t.Name, t.Arity);
  
  						if (t.Arity > 0) {
  							spec = spec.MakeGenericType (module, targs.Skip (targs_pos).Take (spec.Arity).ToArray ());
  							targs_pos += t.Arity;
  						}
  					}
  
  					if (spec.Kind == MemberKind.MissingType) {
  						spec = new TypeSpec (MemberKind.MissingType, spec, new ImportedTypeDefinition (type_def, this), type_def, Modifiers.PUBLIC);
  						spec.MemberCache = MemberCache.Empty;
  					} else {
  						if ((type_def.Attributes & TypeAttributes.VisibilityMask) == TypeAttributes.NestedPrivate && IgnorePrivateMembers)
  							return null;
  
  						string name = type.Name;
  						int index = name.IndexOf ('`');
  						if (index > 0)
  							name = name.Substring (0, index);
  
  						spec = MemberCache.FindNestedType (spec, name, targs.Length - targs_pos);
  
  						if (spec.Arity > 0) {
  							spec = spec.MakeGenericType (module, targs.Skip (targs_pos).ToArray ());
  						}
  					}
  				}
  
  				// Don't add generic type with dynamic arguments, they can interfere with same type
  				// using object type arguments
  				if (!spec.HasDynamicElement) {
  
  					// Add to reading cache to speed up reading
  					if (!import_cache.ContainsKey (type))
  						import_cache.Add (type, spec);
  				}
  
  				return spec;
  			}
  
  			Modifiers mod;
  			MemberKind kind;
  
  			var ma = type.Attributes;
  			switch (ma & TypeAttributes.VisibilityMask) {
  			case TypeAttributes.Public:
  			case TypeAttributes.NestedPublic:
  				mod = Modifiers.PUBLIC;
  				break;
  			case TypeAttributes.NestedPrivate:
  				mod = Modifiers.PRIVATE;
  				break;
  			case TypeAttributes.NestedFamily:
  				mod = Modifiers.PROTECTED;
  				break;
  			case TypeAttributes.NestedFamORAssem:
  				mod = Modifiers.PROTECTED | Modifiers.INTERNAL;
  				break;
  			default:
  				mod = Modifiers.INTERNAL;
  				break;
  			}
  
  			if ((ma & TypeAttributes.Interface) != 0) {
  				kind = MemberKind.Interface;
  			} else if (type.IsGenericParameter) {
  				kind = MemberKind.TypeParameter;
  			} else {
  				var base_type = type.BaseType;
  				if (base_type == null || (ma & TypeAttributes.Abstract) != 0) {
  					kind = MemberKind.Class;
  				} else {
  					kind = DetermineKindFromBaseType (base_type);
  					if (kind == MemberKind.Struct || kind == MemberKind.Delegate) {
  						mod |= Modifiers.SEALED;
  					}
  				}
  
  				if (kind == MemberKind.Class) {
  					if ((ma & TypeAttributes.Sealed) != 0) {
  						if ((ma & TypeAttributes.Abstract) != 0)
  							mod |= Modifiers.STATIC;
  						else
  							mod |= Modifiers.SEALED;
  					} else if ((ma & TypeAttributes.Abstract) != 0) {
  						mod |= Modifiers.ABSTRACT;
  					}
  				}
  			}
  
  			var definition = new ImportedTypeDefinition (type, this);
  			TypeSpec pt;
  
  			if (kind == MemberKind.Enum) {
  				const BindingFlags underlying_member = BindingFlags.DeclaredOnly |
  					BindingFlags.Instance |
  					BindingFlags.Public | BindingFlags.NonPublic;
  
  				var type_members = type.GetFields (underlying_member);
  				foreach (var type_member in type_members) {
  					spec = new EnumSpec (declaringType, definition, CreateType (type_member.FieldType), type, mod);
  					break;
  				}
  
  				if (spec == null)
  					kind = MemberKind.Class;
  
  			} else if (kind == MemberKind.TypeParameter) {
  				spec = CreateTypeParameter (type, declaringType);
  			} else if (type.IsGenericTypeDefinition) {
  				definition.TypeParameters = CreateGenericParameters (type, declaringType);
  			} else if (compiled_types.TryGetValue (type, out pt)) {
  				//
  				// Same type was found in inside compiled types. It's
  				// either build-in type or forward referenced typed
  				// which point into just compiled assembly.
  				//
  				spec = pt;
  				BuiltinTypeSpec bts = pt as BuiltinTypeSpec;
  				if (bts != null)
  					bts.SetDefinition (definition, type, mod);
  			}
  
  			if (spec == null)
  				spec = new TypeSpec (kind, declaringType, definition, type, mod);
  
  			import_cache.Add (type, spec);
  
  			if (kind == MemberKind.TypeParameter) {
  				if (canImportBaseType)
  					ImportTypeParameterTypeConstraints ((TypeParameterSpec) spec, type);
  
  				return spec;
  			}
  
  			//
  			// Two stage setup as the base type can be inflated declaring type or
  			// another nested type inside same declaring type which has not been
  			// loaded, therefore we can import a base type of nested types once
  			// the types have been imported
  			//
  			if (canImportBaseType)
  				ImportTypeBase (spec, type);
  
  			return spec;
  		}
  
  		public IAssemblyDefinition GetAssemblyDefinition (Assembly assembly)
  		{
  			IAssemblyDefinition found;
  			if (!assembly_2_definition.TryGetValue (assembly, out found)) {
  
  				// This can happen in dynamic context only
  				var def = new ImportedAssemblyDefinition (assembly);
  				assembly_2_definition.Add (assembly, def);
  				def.ReadAttributes ();
  				found = def;
  			}
  
  			return found;
  		}
  
  		public void ImportTypeBase (MetaType type)
  		{
  			TypeSpec spec = import_cache[type];
  			if (spec != null)
  				ImportTypeBase (spec, type);
  		}
  
  		TypeParameterSpec CreateTypeParameter (MetaType type, TypeSpec declaringType)
  		{
  			Variance variance;
  			switch (type.GenericParameterAttributes & GenericParameterAttributes.VarianceMask) {
  			case GenericParameterAttributes.Covariant:
  				variance = Variance.Covariant;
  				break;
  			case GenericParameterAttributes.Contravariant:
  				variance = Variance.Contravariant;
  				break;
  			default:
  				variance = Variance.None;
  				break;
  			}
  
  			SpecialConstraint special = SpecialConstraint.None;
  			var import_special = type.GenericParameterAttributes & GenericParameterAttributes.SpecialConstraintMask;
  
  			if ((import_special & GenericParameterAttributes.NotNullableValueTypeConstraint) != 0) {
  				special |= SpecialConstraint.Struct;
  			} else if ((import_special & GenericParameterAttributes.DefaultConstructorConstraint) != 0) {
  				special = SpecialConstraint.Constructor;
  			}
  
  			if ((import_special & GenericParameterAttributes.ReferenceTypeConstraint) != 0) {
  				special |= SpecialConstraint.Class;
  			}
  
  			TypeParameterSpec spec;
  			var def = new ImportedTypeParameterDefinition (type, this);
  			if (type.DeclaringMethod != null) {
  				spec = new TypeParameterSpec (type.GenericParameterPosition, def, special, variance, type);
  			} else {
  				spec = new TypeParameterSpec (declaringType, type.GenericParameterPosition, def, special, variance, type);
  			}
  
  			return spec;
  		}
  
  		//
  		// Test for a custom attribute type match. Custom attributes are not really predefined globaly 
  		// they can be assembly specific therefore we do check based on names only
  		//
  		public static bool HasAttribute (IList<CustomAttributeData> attributesData, string attrName, string attrNamespace)
  		{
  			if (attributesData.Count == 0)
  				return false;
  
  			foreach (var attr in attributesData) {
  				var dt = attr.Constructor.DeclaringType;
  				if (dt.Name == attrName && dt.Namespace == attrNamespace)
  					return true;
  			}
  
  			return false;
  		}
  
  		void ImportTypeBase (TypeSpec spec, MetaType type)
  		{
  			if (spec.Kind == MemberKind.Interface)
  				spec.BaseType = module.Compiler.BuiltinTypes.Object;
  			else if (type.BaseType != null) {
  				TypeSpec base_type;
  				if (!IsMissingType (type.BaseType) && type.BaseType.IsGenericType)
  					base_type = CreateType (type.BaseType, new DynamicTypeReader (type), true);
  				else
  					base_type = CreateType (type.BaseType);
  
  				spec.BaseType = base_type;
  			}
  
  			if (spec.MemberDefinition.TypeParametersCount > 0) {
  				foreach (var tp in spec.MemberDefinition.TypeParameters) {
  					ImportTypeParameterTypeConstraints (tp, tp.GetMetaInfo ());
  				}
  			}
  		}
  
  		protected void ImportTypes (MetaType[] types, Namespace targetNamespace, bool importExtensionTypes)
  		{
  			Namespace ns = targetNamespace;
  			string prev_namespace = null;
  			foreach (var t in types) {
  				if (t == null)
  					continue;
  
  				// Be careful not to trigger full parent type loading
  				if (t.MemberType == MemberTypes.NestedType)
  					continue;
  
  				if (t.Name[0] == '<')
  					continue;
  
  				var it = CreateType (t, null, new DynamicTypeReader (t), true);
  				if (it == null)
  					continue;
  
  				if (prev_namespace != t.Namespace) {
  					ns = t.Namespace == null ? targetNamespace : targetNamespace.GetNamespace (t.Namespace, true);
  					prev_namespace = t.Namespace;
  				}
  
  				// Cannot rely on assembly level Extension attribute or static modifier because they
  				// are not followed by other compilers (e.g. F#).
  				if (it.IsClass && it.Arity == 0 && importExtensionTypes &&
  					HasAttribute (CustomAttributeData.GetCustomAttributes (t), "ExtensionAttribute", CompilerServicesNamespace)) {
  					it.SetExtensionMethodContainer ();
  				}
  
  				ns.AddType (module, it);
  			}
  		}
  
  		void ImportTypeParameterTypeConstraints (TypeParameterSpec spec, MetaType type)
  		{
  			var constraints = type.GetGenericParameterConstraints ();
  			List<TypeSpec> tparams = null;
  			foreach (var ct in constraints) {
  				if (ct.IsGenericParameter) {
  					if (tparams == null)
  						tparams = new List<TypeSpec> ();
  
  					tparams.Add (CreateType (ct));
  					continue;
  				}
  
  				var constraint_type = CreateType (ct);
  				if (constraint_type.IsClass) {
  					spec.BaseType = constraint_type;
  					continue;
  				}
  
  				spec.AddInterface (constraint_type);
  			}
  
  			if (spec.BaseType == null)
  				spec.BaseType = module.Compiler.BuiltinTypes.Object;
  
  			if (tparams != null)
  				spec.TypeArguments = tparams.ToArray ();
  		}
  
  		Constant ImportParameterConstant (object value)
  		{
  			//
  			// Get type of underlying value as int constant can be used for object
  			// parameter type. This is not allowed in C# but other languages can do that
  			//
  			var types = module.Compiler.BuiltinTypes;
  			switch (System.Type.GetTypeCode (value.GetType ())) {
  			case TypeCode.Boolean:
  				return new BoolConstant (types, (bool) value, Location.Null);
  			case TypeCode.Byte:
  				return new ByteConstant (types, (byte) value, Location.Null);
  			case TypeCode.Char:
  				return new CharConstant (types, (char) value, Location.Null);
  			case TypeCode.Decimal:
  				return new DecimalConstant (types, (decimal) value, Location.Null);
  			case TypeCode.Double:
  				return new DoubleConstant (types, (double) value, Location.Null);
  			case TypeCode.Int16:
  				return new ShortConstant (types, (short) value, Location.Null);
  			case TypeCode.Int32:
  				return new IntConstant (types, (int) value, Location.Null);
  			case TypeCode.Int64:
  				return new LongConstant (types, (long) value, Location.Null);
  			case TypeCode.SByte:
  				return new SByteConstant (types, (sbyte) value, Location.Null);
  			case TypeCode.Single:
  				return new FloatConstant (types, (float) value, Location.Null);
  			case TypeCode.String:
  				return new StringConstant (types, (string) value, Location.Null);
  			case TypeCode.UInt16:
  				return new UShortConstant (types, (ushort) value, Location.Null);
  			case TypeCode.UInt32:
  				return new UIntConstant (types, (uint) value, Location.Null);
  			case TypeCode.UInt64:
  				return new ULongConstant (types, (ulong) value, Location.Null);
  			}
  
  			throw new NotImplementedException (value.GetType ().ToString ());
  		}
  
  		public TypeSpec ImportType (MetaType type)
  		{
  			return ImportType (type, new DynamicTypeReader (type));
  		}
  
  		TypeSpec ImportType (MetaType type, DynamicTypeReader dtype)
  		{
  			if (type.HasElementType) {
  				var element = type.GetElementType ();
  				++dtype.Position;
  				var spec = ImportType (element, dtype);
  
  				if (type.IsArray)
  					return ArrayContainer.MakeType (module, spec, type.GetArrayRank ());
  				if (type.IsByRef)
  					return ReferenceContainer.MakeType (module, spec);
  				if (type.IsPointer)
  					return PointerContainer.MakeType (module, spec);
  
  				throw new NotImplementedException ("Unknown element type " + type.ToString ());
  			}
  
  			TypeSpec compiled_type;
  			if (compiled_types.TryGetValue (type, out compiled_type)) {
  				if (compiled_type.BuiltinType == BuiltinTypeSpec.Type.Object && dtype.IsDynamicObject ())
  					return module.Compiler.BuiltinTypes.Dynamic;
  
  				return compiled_type;
  			}
  
  			return CreateType (type, dtype, true);
  		}
  
  		static bool IsMissingType (MetaType type)
  		{
  #if STATIC
  			return type.__IsMissing;
  #else
  			return false;
  #endif
  		}
  
  		//
  		// Decimal constants cannot be encoded in the constant blob, and thus are marked
  		// as IsInitOnly ('readonly' in C# parlance).  We get its value from the 
  		// DecimalConstantAttribute metadata.
  		//
  		Constant ReadDecimalConstant (IList<CustomAttributeData> attrs)
  		{
  			if (attrs.Count == 0)
  				return null;
  
  			foreach (var ca in attrs) {
  				var dt = ca.Constructor.DeclaringType;
  				if (dt.Name != "DecimalConstantAttribute" || dt.Namespace != CompilerServicesNamespace)
  					continue;
  
  				var value = new decimal (
  					(int) (uint) ca.ConstructorArguments[4].Value,
  					(int) (uint) ca.ConstructorArguments[3].Value,
  					(int) (uint) ca.ConstructorArguments[2].Value,
  					(byte) ca.ConstructorArguments[1].Value != 0,
  					(byte) ca.ConstructorArguments[0].Value);
  
  				return new DecimalConstant (module.Compiler.BuiltinTypes, value, Location.Null);
  			}
  
  			return null;
  		}
  
  		static Modifiers ReadMethodModifiers (MethodBase mb, TypeSpec declaringType)
  		{
  			Modifiers mod;
  			var ma = mb.Attributes;
  			switch (ma & MethodAttributes.MemberAccessMask) {
  			case MethodAttributes.Public:
  				mod = Modifiers.PUBLIC;
  				break;
  			case MethodAttributes.Assembly:
  				mod = Modifiers.INTERNAL;
  				break;
  			case MethodAttributes.Family:
  				mod = Modifiers.PROTECTED;
  				break;
  			case MethodAttributes.FamORAssem:
  				mod = Modifiers.PROTECTED | Modifiers.INTERNAL;
  				break;
  			default:
  				mod = Modifiers.PRIVATE;
  				break;
  			}
  
  			if ((ma & MethodAttributes.Static) != 0) {
  				mod |= Modifiers.STATIC;
  				return mod;
  			}
  			if ((ma & MethodAttributes.Abstract) != 0 && declaringType.IsClass) {
  				mod |= Modifiers.ABSTRACT;
  				return mod;
  			}
  
  			// It can be sealed and override
  			if ((ma & MethodAttributes.Final) != 0)
  				mod |= Modifiers.SEALED;
  
  			if ((ma & MethodAttributes.Virtual) != 0) {
  				// Not every member can be detected based on MethodAttribute, we
  				// set virtual or non-virtual only when we are certain. Further checks
  				// to really find out what `virtual' means for this member are done
  				// later
  				if ((ma & MethodAttributes.NewSlot) != 0) {
  					if ((mod & Modifiers.SEALED) != 0) {
  						mod &= ~Modifiers.SEALED;
  					} else {
  						mod |= Modifiers.VIRTUAL;
  					}
  				} else {
  					mod |= Modifiers.OVERRIDE;
  				}
  			}
  
  			return mod;
  		}
  	}
  
  	abstract class ImportedDefinition : IMemberDefinition
  	{
  		protected class AttributesBag
  		{
  			public static readonly AttributesBag Default = new AttributesBag ();
  
  			public AttributeUsageAttribute AttributeUsage;
  			public ObsoleteAttribute Obsolete;
  			public string[] Conditionals;
  			public string DefaultIndexerName;
  			public bool? CLSAttributeValue;
  			public TypeSpec CoClass;
  			
  			public static AttributesBag Read (MemberInfo mi, MetadataImporter importer)
  			{
  				AttributesBag bag = null;
  				List<string> conditionals = null;
  
  				// It should not throw any loading exception
  				IList<CustomAttributeData> attrs = CustomAttributeData.GetCustomAttributes (mi);
  
  				foreach (var a in attrs) {
  					var dt = a.Constructor.DeclaringType;
  					string name = dt.Name;
  					if (name == "ObsoleteAttribute") {
  						if (dt.Namespace != "System")
  							continue;
  
  						if (bag == null)
  							bag = new AttributesBag ();
  
  						var args = a.ConstructorArguments;
  
  						if (args.Count == 1) {
  							bag.Obsolete = new ObsoleteAttribute ((string) args[0].Value);
  						} else if (args.Count == 2) {
  							bag.Obsolete = new ObsoleteAttribute ((string) args[0].Value, (bool) args[1].Value);
  						} else {
  							bag.Obsolete = new ObsoleteAttribute ();
  						}
  
  						continue;
  					}
  
  					if (name == "ConditionalAttribute") {
  						if (dt.Namespace != "System.Diagnostics")
  							continue;
  
  						if (bag == null)
  							bag = new AttributesBag ();
  
  						if (conditionals == null)
  							conditionals = new List<string> (2);
  
  						conditionals.Add ((string) a.ConstructorArguments[0].Value);
  						continue;
  					}
  
  					if (name == "CLSCompliantAttribute") {
  						if (dt.Namespace != "System")
  							continue;
  
  						if (bag == null)
  							bag = new AttributesBag ();
  
  						bag.CLSAttributeValue = (bool) a.ConstructorArguments[0].Value;
  						continue;
  					}
  
  					// Type only attributes
  					if (mi.MemberType == MemberTypes.TypeInfo || mi.MemberType == MemberTypes.NestedType) {
  						if (name == "DefaultMemberAttribute") {
  							if (dt.Namespace != "System.Reflection")
  								continue;
  
  							if (bag == null)
  								bag = new AttributesBag ();
  
  							bag.DefaultIndexerName = (string) a.ConstructorArguments[0].Value;
  							continue;
  						}
  
  						if (name == "AttributeUsageAttribute") {
  							if (dt.Namespace != "System")
  								continue;
  
  							if (bag == null)
  								bag = new AttributesBag ();
  
  							bag.AttributeUsage = new AttributeUsageAttribute ((AttributeTargets) a.ConstructorArguments[0].Value);
  							foreach (var named in a.NamedArguments) {
  								if (named.MemberInfo.Name == "AllowMultiple")
  									bag.AttributeUsage.AllowMultiple = (bool) named.TypedValue.Value;
  								else if (named.MemberInfo.Name == "Inherited")
  									bag.AttributeUsage.Inherited = (bool) named.TypedValue.Value;
  							}
  							continue;
  						}
  
  						// Interface only attribute
  						if (name == "CoClassAttribute") {
  							if (dt.Namespace != "System.Runtime.InteropServices")
  								continue;
  
  							if (bag == null)
  								bag = new AttributesBag ();
  
  							bag.CoClass = importer.ImportType ((MetaType) a.ConstructorArguments[0].Value);
  							continue;
  						}
  					}
  				}
  
  				if (bag == null)
  					return Default;
  
  				if (conditionals != null)
  					bag.Conditionals = conditionals.ToArray ();
  				
  				return bag;
  			}
  		}
  
  		protected readonly MemberInfo provider;
  		protected AttributesBag cattrs;
  		protected readonly MetadataImporter importer;
  
  		protected ImportedDefinition (MemberInfo provider, MetadataImporter importer)
  		{
  			this.provider = provider;
  			this.importer = importer;
  		}
  
  		#region Properties
  
  		public bool IsImported {
  			get {
  				return true;
  			}
  		}
  
  		public virtual string Name {
  			get {
  				return provider.Name;
  			}
  		}
  
  		#endregion
  
  		public string[] ConditionalConditions ()
  		{
  			if (cattrs == null)
  				ReadAttributes ();
  
  			return cattrs.Conditionals;
  		}
  
  		public ObsoleteAttribute GetAttributeObsolete ()
  		{
  			if (cattrs == null)
  				ReadAttributes ();
  
  			return cattrs.Obsolete;
  		}
  
  		public bool? CLSAttributeValue {
  			get {
  				if (cattrs == null)
  					ReadAttributes ();
  
  				return cattrs.CLSAttributeValue;
  			}
  		}
  
  		protected void ReadAttributes ()
  		{
  			cattrs = AttributesBag.Read (provider, importer);
  		}
  
  		public void SetIsAssigned ()
  		{
  			// Unused for imported members
  		}
  
  		public void SetIsUsed ()
  		{
  			// Unused for imported members
  		}
  	}
  
  	public class ImportedModuleDefinition
  	{
  		readonly Module module;
  		bool cls_compliant;
  		
  		public ImportedModuleDefinition (Module module)
  		{
  			this.module = module;
  		}
  
  		#region Properties
  
  		public bool IsCLSCompliant {
  			get {
  				return cls_compliant;
  			}
  		}
  
  		public string Name {
  			get {
  				return module.Name;
  			}
  		}
  
  		#endregion
  
  		public void ReadAttributes ()
  		{
  			IList<CustomAttributeData> attrs = CustomAttributeData.GetCustomAttributes (module);
  
  			foreach (var a in attrs) {
  				var dt = a.Constructor.DeclaringType;
  				if (dt.Name == "CLSCompliantAttribute") {
  					if (dt.Namespace != "System")
  						continue;
  
  					cls_compliant = (bool) a.ConstructorArguments[0].Value;
  					continue;
  				}
  			}
  		}
  
  		//
  		// Reads assembly attributes which where attached to a special type because
  		// module does have assembly manifest
  		//
  		public List<Attribute> ReadAssemblyAttributes ()
  		{
  			var t = module.GetType (AssemblyAttributesPlaceholder.GetGeneratedName (Name));
  			if (t == null)
  				return null;
  
  			var field = t.GetField (AssemblyAttributesPlaceholder.AssemblyFieldName, BindingFlags.NonPublic | BindingFlags.Static);
  			if (field == null)
  				return null;
  
  			// TODO: implement, the idea is to fabricate specil Attribute class and
  			// add it to OptAttributes before resolving the source code attributes
  			// Need to build module location as well for correct error reporting
  
  			//var assembly_attributes = CustomAttributeData.GetCustomAttributes (field);
  			//var attrs = new List<Attribute> (assembly_attributes.Count);
  			//foreach (var a in assembly_attributes)
  			//{
  			//    var type = metaImporter.ImportType (a.Constructor.DeclaringType);
  			//    var ctor = metaImporter.CreateMethod (a.Constructor, type);
  
  			//    foreach (var carg in a.ConstructorArguments) {
  			//        carg.Value
  			//    }
  
  			//    attrs.Add (new Attribute ("assembly", ctor, null, Location.Null, true));
  			//}
  
  			return null;
  		}
  	}
  
  	public class ImportedAssemblyDefinition : IAssemblyDefinition
  	{
  		readonly Assembly assembly;
  		readonly AssemblyName aname;
  		bool cls_compliant;
  
  		List<AssemblyName> internals_visible_to;
  		Dictionary<IAssemblyDefinition, AssemblyName> internals_visible_to_cache;
  
  		public ImportedAssemblyDefinition (Assembly assembly)
  		{
  			this.assembly = assembly;
  			this.aname = assembly.GetName ();
  		}
  
  		#region Properties
  
  		public Assembly Assembly {
  			get {
  				return assembly;
  			}
  		}
  
  		public string FullName {
  			get {
  				return aname.FullName;
  			}
  		}
  
  		public bool HasStrongName {
  			get {
  				return aname.GetPublicKey ().Length != 0;
  			}
  		}
  
  		public bool IsMissing {
  			get {
  #if STATIC
  				return assembly.__IsMissing;
  #else
  				return false;
  #endif
  			}
  		}
  
  		public bool IsCLSCompliant {
  			get {
  				return cls_compliant;
  			}
  		}
  
  		public string Location {
  			get {
  				return assembly.Location;
  			}
  		}
  
  		public string Name {
  			get {
  				return aname.Name;
  			}
  		}
  
  		#endregion
  
  		public byte[] GetPublicKeyToken ()
  		{
  			return aname.GetPublicKeyToken ();
  		}
  
  		public AssemblyName GetAssemblyVisibleToName (IAssemblyDefinition assembly)
  		{
  			return internals_visible_to_cache [assembly];
  		}
  
  		public bool IsFriendAssemblyTo (IAssemblyDefinition assembly)
  		{
  			if (internals_visible_to == null)
  				return false;
  
  			AssemblyName is_visible = null;
  			if (internals_visible_to_cache == null) {
  				internals_visible_to_cache = new Dictionary<IAssemblyDefinition, AssemblyName> ();
  			} else {
  				if (internals_visible_to_cache.TryGetValue (assembly, out is_visible))
  					return is_visible != null;
  			}
  
  			var token = assembly.GetPublicKeyToken ();
  			if (token != null && token.Length == 0)
  				token = null;
  
  			foreach (var internals in internals_visible_to) {
  				if (internals.Name != assembly.Name)
  					continue;
  
  				if (token == null && assembly is AssemblyDefinition) {
  					is_visible = internals;
  					break;
  				}
  
  				if (!ArrayComparer.IsEqual (token, internals.GetPublicKeyToken ()))
  					continue;
  
  				is_visible = internals;
  				break;
  			}
  
  			internals_visible_to_cache.Add (assembly, is_visible);
  			return is_visible != null;
  		}
  
  		public void ReadAttributes ()
  		{
  #if STATIC
  			if (assembly.__IsMissing)
  				return;
  #endif
  
  			IList<CustomAttributeData> attrs = CustomAttributeData.GetCustomAttributes (assembly);
  
  			foreach (var a in attrs) {
  				var dt = a.Constructor.DeclaringType;
  				var name = dt.Name;
  				if (name == "CLSCompliantAttribute") {
  					if (dt.Namespace == "System") {
  						cls_compliant = (bool) a.ConstructorArguments[0].Value;
  					}
  					continue;
  				}
  
  				if (name == "InternalsVisibleToAttribute") {
  					if (dt.Namespace != MetadataImporter.CompilerServicesNamespace)
  						continue;
  
  					string s = a.ConstructorArguments[0].Value as string;
  					if (s == null)
  						continue;
  
  					var an = new AssemblyName (s);
  					if (internals_visible_to == null)
  						internals_visible_to = new List<AssemblyName> ();
  
  					internals_visible_to.Add (an);
  					continue;
  				}
  			}
  		}
  
  		public override string ToString ()
  		{
  			return FullName;
  		}
  	}
  
  	class ImportedMemberDefinition : ImportedDefinition
  	{
  		readonly TypeSpec type;
  
  		public ImportedMemberDefinition (MemberInfo member, TypeSpec type, MetadataImporter importer)
  			: base (member, importer)
  		{
  			this.type = type;
  		}
  
  		#region Properties
  
  		public TypeSpec MemberType {
  			get {
  				return type;
  			}
  		}
  
  		#endregion
  	}
  
  	class ImportedParameterMemberDefinition : ImportedMemberDefinition, IParametersMember
  	{
  		readonly AParametersCollection parameters;
  
  		protected ImportedParameterMemberDefinition (MethodBase provider, TypeSpec type, AParametersCollection parameters, MetadataImporter importer)
  			: base (provider, type, importer)
  		{
  			this.parameters = parameters;
  		}
  
  		public ImportedParameterMemberDefinition (PropertyInfo provider, TypeSpec type, AParametersCollection parameters, MetadataImporter importer)
  			: base (provider, type, importer)
  		{
  			this.parameters = parameters;
  		}
  
  		#region Properties
  
  		public AParametersCollection Parameters {
  			get {
  				return parameters;
  			}
  		}
  
  		#endregion
  	}
  
  	class ImportedMethodDefinition : ImportedParameterMemberDefinition, IMethodDefinition
  	{
  		public ImportedMethodDefinition (MethodBase provider, TypeSpec type, AParametersCollection parameters, MetadataImporter importer)
  			: base (provider, type, parameters, importer)
  		{
  		}
  
  		MethodBase IMethodDefinition.Metadata {
  			get {
  				return (MethodBase) provider;
  			}
  		}
  	}
  
  	class ImportedGenericMethodDefinition : ImportedMethodDefinition, IGenericMethodDefinition
  	{
  		readonly TypeParameterSpec[] tparams;
  
  		public ImportedGenericMethodDefinition (MethodInfo provider, TypeSpec type, AParametersCollection parameters, TypeParameterSpec[] tparams, MetadataImporter importer)
  			: base (provider, type, parameters, importer)
  		{
  			this.tparams = tparams;
  		}
  
  		#region Properties
  
  		public TypeParameterSpec[] TypeParameters {
  			get {
  				return tparams;
  			}
  		}
  
  		public int TypeParametersCount {
  			get {
  				return tparams.Length;
  			}
  		}
  
  		#endregion
  	}
  
  	class ImportedTypeDefinition : ImportedDefinition, ITypeDefinition
  	{
  		TypeParameterSpec[] tparams;
  		string name;
  
  		public ImportedTypeDefinition (MetaType type, MetadataImporter importer)
  			: base (type, importer)
  		{
  		}
  
  		#region Properties
  
  		public IAssemblyDefinition DeclaringAssembly {
  			get {
  				return importer.GetAssemblyDefinition (provider.Module.Assembly);
  			}
  		}
  
  		bool ITypeDefinition.IsComImport {
  			get {
  				return ((MetaType) provider).IsImport;
  			}
  		}
  
  
  		bool ITypeDefinition.IsPartial {
  			get {
  				return false;
  			}
  		}
  
  		bool ITypeDefinition.IsTypeForwarder {
  			get {
  #if STATIC
  				return ((MetaType) provider).__IsTypeForwarder;
  #else
  				return false;
  #endif
  			}
  		}
  
  		bool ITypeDefinition.IsCyclicTypeForwarder {
  			get {
  #if STATIC
  				return ((MetaType) provider).__IsCyclicTypeForwarder;
  #else
  				return false;
  #endif
  			}
  		}
  
  		public override string Name {
  			get {
  				if (name == null) {
  					name = base.Name;
  					if (tparams != null) {
  						int arity_start = name.IndexOf ('`');
  						if (arity_start > 0)
  							name = name.Substring (0, arity_start);
  					}
  				}
  
  				return name;
  			}
  		}
  
  		public string Namespace {
  			get {
  				return ((MetaType) provider).Namespace;
  			}
  		}
  
  		public int TypeParametersCount {
  			get {
  				return tparams == null ? 0 : tparams.Length;
  			}
  		}
  
  		public TypeParameterSpec[] TypeParameters {
  			get {
  				return tparams;
  			}
  			set {
  				tparams = value;
  			}
  		}
  
  		#endregion
  
  		public void DefineInterfaces (TypeSpec spec)
  		{
  
gt: 			var type = (MetaType) provider;