source: branches/CodeEditor/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Parser/mcs/attribute.cs @ 11700

//
// attribute.cs: Attributes handling
//
// Author: Ravi Pratap (ravi@ximian.com)
//         Marek Safar (marek.safar@gmail.com)
//
// 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.
// Copyright 2011-2013 Xamarin Inc
//

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;
using System.Security; 
using System.Security.Permissions;
using System.Text;
using System.IO;

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

namespace Mono.CSharp {

  /// <summary>
  ///   Base class for objects that can have Attributes applied to them.
  /// </summary>
  public abstract class Attributable {
    //
    // Holds all attributes attached to this element
    //
    protected Attributes attributes;

    public void AddAttributes (Attributes attrs, IMemberContext context)
    {
      if (attrs == null)
        return;
    
      if (attributes == null)
        attributes = attrs;
      else
        attributes.AddAttributes (attrs.Attrs);
      attrs.AttachTo (this, context);
    }

    public Attributes OptAttributes {
      get {
        return attributes;
      }
      set {
        attributes = value;
      }
    }

    /// <summary>
    /// Use member-specific procedure to apply attribute @a in @cb to the entity being built in @builder
    /// </summary>
    public abstract void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa);

    /// <summary>
    /// Returns one AttributeTarget for this element.
    /// </summary>
    public abstract AttributeTargets AttributeTargets { get; }

    public abstract bool IsClsComplianceRequired ();

    /// <summary>
    /// Gets list of valid attribute targets for explicit target declaration.
    /// The first array item is default target. Don't break this rule.
    /// </summary>
    public abstract string[] ValidAttributeTargets { get; }
  };

  public class Attribute
  {
    public readonly string ExplicitTarget;
    public AttributeTargets Target;
    readonly ATypeNameExpression expression;

    Arguments pos_args, named_args;

    bool resolve_error;
    bool arg_resolved;
    readonly bool nameEscaped;
    readonly Location loc;
    public TypeSpec Type; 

    //
    // An attribute can be attached to multiple targets (e.g. multiple fields)
    //
    Attributable[] targets;

    //
    // A member context for the attribute, it's much easier to hold it here
    // than trying to pull it during resolve
    //
    IMemberContext context;

    public static readonly AttributeUsageAttribute DefaultUsageAttribute = new AttributeUsageAttribute (AttributeTargets.All);
    public static readonly object[] EmptyObject = new object [0];

    List<KeyValuePair<MemberExpr, NamedArgument>> named_values;

    public Attribute (string target, ATypeNameExpression expr, Arguments[] args, Location loc, bool nameEscaped)
    {
      this.expression = expr;
      if (args != null) {
        pos_args = args[0];
        named_args = args[1];
      }
      this.loc = loc;
      ExplicitTarget = target;
      this.nameEscaped = nameEscaped;
    }

    public Location Location {
      get {
        return loc;
      }
    }

    public Arguments NamedArguments {
      get {
        return named_args;
      }
    }

    public Arguments PositionalArguments {
      get {
        return pos_args;
      }
    }

    public bool ResolveError {
      get {
        return resolve_error;
      }
    }

    public ATypeNameExpression TypeExpression {
      get {
        return expression;
      }
    }

    void AddModuleCharSet (ResolveContext rc)
    {
      const string dll_import_char_set = "CharSet";

      //
      // Only when not customized by user
      //
      if (HasField (dll_import_char_set))
        return;

      if (!rc.Module.PredefinedTypes.CharSet.Define ()) {
        return;
      }

      if (NamedArguments == null)
        named_args = new Arguments (1);

      var value = Constant.CreateConstantFromValue (rc.Module.PredefinedTypes.CharSet.TypeSpec, rc.Module.DefaultCharSet, Location);
      NamedArguments.Add (new NamedArgument (dll_import_char_set, loc, value));
    }

    public Attribute Clone ()
    {
      Attribute a = new Attribute (ExplicitTarget, expression, null, loc, nameEscaped);
      a.pos_args = pos_args;
      a.named_args = NamedArguments;
      return a;
    }

    //
    // When the same attribute is attached to multiple fiels
    // we use @target field as a list of targets. The attribute
    // has to be resolved only once but emitted for each target.
    //
    public void AttachTo (Attributable target, IMemberContext context)
    {
      if (this.targets == null) {
        this.targets = new Attributable[] { target };
        this.context = context;
        return;
      }

      // When re-attaching global attributes
      if (context is NamespaceContainer) {
        this.targets[0] = target;
        this.context = context;
        return;
      }

      // Resize target array
      Attributable[] new_array = new Attributable [this.targets.Length + 1];
      targets.CopyTo (new_array, 0);
      new_array [targets.Length] = target;
      this.targets = new_array;

      // No need to update context, different targets cannot have
      // different contexts, it's enough to remove same attributes
      // from secondary members.

      target.OptAttributes = null;
    }

    public ResolveContext CreateResolveContext ()
    {
      return new ResolveContext (context, ResolveContext.Options.ConstantScope);
    }

    static void Error_InvalidNamedArgument (ResolveContext rc, NamedArgument name)
    {
      rc.Report.Error (617, name.Location, "`{0}' is not a valid named attribute argument. Named attribute arguments " +
              "must be fields which are not readonly, static, const or read-write properties which are " +
              "public and not static",
            name.Name);
    }

    static void Error_InvalidNamedArgumentType (ResolveContext rc, NamedArgument name)
    {
      rc.Report.Error (655, name.Location,
        "`{0}' is not a valid named attribute argument because it is not a valid attribute parameter type",
        name.Name);
    }

    public static void Error_AttributeArgumentIsDynamic (IMemberContext context, Location loc)
    {
      context.Module.Compiler.Report.Error (1982, loc, "An attribute argument cannot be dynamic expression");
    }
    
    public void Error_MissingGuidAttribute ()
    {
      Report.Error (596, Location, "The Guid attribute must be specified with the ComImport attribute");
    }

    public void Error_MisusedExtensionAttribute ()
    {
      Report.Error (1112, Location, "Do not use `{0}' directly. Use parameter modifier `this' instead", GetSignatureForError ());
    }

    public void Error_MisusedDynamicAttribute ()
    {
      Report.Error (1970, loc, "Do not use `{0}' directly. Use `dynamic' keyword instead", GetSignatureForError ());
    }

    void Error_AttributeEmitError (string inner)
    {
      Report.Error (647, Location, "Error during emitting `{0}' attribute. The reason is `{1}'",
              Type.GetSignatureForError (), inner);
    }

    public void Error_InvalidArgumentValue (TypeSpec attributeType)
    {
      Report.Error (591, Location, "Invalid value for argument to `{0}' attribute", attributeType.GetSignatureForError ());
    }

    public void Error_InvalidSecurityParent ()
    {
      Report.Error (7070, Location,
        "Security attribute `{0}' is not valid on this declaration type. Security attributes are only valid on assembly, type and method declarations",
        Type.GetSignatureForError ());
    }

    Attributable Owner {
      get {
        return targets [0];
      }
    }

    /// <summary>
    ///   Tries to resolve the type of the attribute. Flags an error if it can't, and complain is true.
    /// </summary>
    void ResolveAttributeType (bool comparisonOnly)
    {
      var resolve_printer = new SessionReportPrinter ();
      SessionReportPrinter secondary_printer = null;
      ReportPrinter prev_recorder = Report.SetPrinter (resolve_printer);

      bool t1_is_attr = false;
      bool t2_is_attr = false;
      TypeSpec t1, t2;
      ATypeNameExpression expanded = null;

      // TODO: Additional warnings such as CS0436 are swallowed because we don't
      // print on success

      try {
        t1 = expression.ResolveAsType (context);
        resolve_printer.EndSession ();

        if (t1 != null && resolve_printer.ErrorsCount == 0)
          t1_is_attr = t1.IsAttribute;

        if (nameEscaped) {
          t2 = null;
        } else {
          expanded = (ATypeNameExpression) expression.Clone (null);
          expanded.Name += "Attribute";

          secondary_printer = new SessionReportPrinter ();
          Report.SetPrinter (secondary_printer);
          t2 = expanded.ResolveAsType (context);
          secondary_printer.EndSession ();
          if (t2 != null && secondary_printer.ErrorsCount == 0)
            t2_is_attr = t2.IsAttribute;

          secondary_printer.EndSession ();
        }
      } finally {
        context.Module.Compiler.Report.SetPrinter (prev_recorder);
      }

      if (t1_is_attr && t2_is_attr && t1 != t2) {
        if (!comparisonOnly) {
          Report.Error (1614, Location, "`{0}' is ambiguous between `{1}' and `{2}'. Use either `@{0}' or `{0}Attribute'",
            GetSignatureForError (), expression.GetSignatureForError (), expanded.GetSignatureForError ());
          resolve_error = true;
        }

        return;
      }

      if (t1_is_attr) {
        Type = t1;
        return;
      }

      if (t2_is_attr) {
        Type = t2;
        return;
      }

      if (comparisonOnly)
        return;

      resolve_error = true;

      if (t1 != null) { 
        if (resolve_printer.IsEmpty) {
          Report.SymbolRelatedToPreviousError (t1);
          Report.Error (616, Location, "`{0}': is not an attribute class", t1.GetSignatureForError ());
        } else {
          resolve_printer.Merge (prev_recorder);
        }

        return;
      }

      if (t2 != null) {
        if (secondary_printer.IsEmpty) {
          Report.SymbolRelatedToPreviousError (t2);
          Report.Error (616, Location, "`{0}': is not an attribute class", t2.GetSignatureForError ());
        } else {
          secondary_printer.Merge (prev_recorder);
        }

        return;
      }

      resolve_printer.Merge (prev_recorder);
    }

    public TypeSpec ResolveTypeForComparison ()
    {
      if (Type == null && !resolve_error)
        ResolveAttributeType (true);
      return Type;
    }

    public string GetSignatureForError ()
    {
      if (Type != null)
        return Type.GetSignatureForError ();

      return expression.GetSignatureForError ();
    }

    public bool HasSecurityAttribute {
      get {
        PredefinedAttribute pa = context.Module.PredefinedAttributes.Security;
        return pa.IsDefined && TypeSpec.IsBaseClass (Type, pa.TypeSpec, false);
      }
    }

    public bool IsValidSecurityAttribute ()
    {
      return HasSecurityAttribute && IsSecurityActionValid ();
    }

    static bool IsValidMethodImplOption (int value)
    {
      //
      // Allow to use AggressiveInlining on any runtime/corlib
      //
      MethodImplOptions all = (MethodImplOptions) 256;
      foreach (MethodImplOptions v in System.Enum.GetValues (typeof (MethodImplOptions))) {
        all |= v;
      }

      return ((MethodImplOptions) value | all) == all;
    }

    public static bool IsValidArgumentType (TypeSpec t)
    {
      if (t.IsArray) {
        var ac = (ArrayContainer) t;
        if (ac.Rank > 1)
          return false;

        t = ac.Element;
      }

      switch (t.BuiltinType) {
      case BuiltinTypeSpec.Type.Int:
      case BuiltinTypeSpec.Type.UInt:
      case BuiltinTypeSpec.Type.Long:
      case BuiltinTypeSpec.Type.ULong:
      case BuiltinTypeSpec.Type.Float:
      case BuiltinTypeSpec.Type.Double:
      case BuiltinTypeSpec.Type.Char:
      case BuiltinTypeSpec.Type.Short:
      case BuiltinTypeSpec.Type.Bool:
      case BuiltinTypeSpec.Type.SByte:
      case BuiltinTypeSpec.Type.Byte:
      case BuiltinTypeSpec.Type.UShort:

      case BuiltinTypeSpec.Type.String:
      case BuiltinTypeSpec.Type.Object:
      case BuiltinTypeSpec.Type.Dynamic:
      case BuiltinTypeSpec.Type.Type:
        return true;
      }

      return t.IsEnum;
    }

    // TODO: Don't use this ambiguous value
    public string Name {
      get { return expression.Name; }
    }

    public ATypeNameExpression TypeNameExpression {
      get {
        return expression;
      }
    }

    public Report Report {
      get { return context.Module.Compiler.Report; }
    }

    public MethodSpec Resolve ()
    {
      if (resolve_error)
        return null;

      resolve_error = true;
      arg_resolved = true;

      if (Type == null) {
        ResolveAttributeType (false);
        if (Type == null)
          return null;
      }

      if (Type.IsAbstract) {
        Report.Error (653, Location, "Cannot apply attribute class `{0}' because it is abstract", GetSignatureForError ());
        return null;
      }

      ObsoleteAttribute obsolete_attr = Type.GetAttributeObsolete ();
      if (obsolete_attr != null) {
        AttributeTester.Report_ObsoleteMessage (obsolete_attr, Type.GetSignatureForError (), Location, Report);
      }

      ResolveContext rc = null;

      MethodSpec ctor;
      // Try if the attribute is simple and has been resolved before
      if (pos_args != null || !context.Module.AttributeConstructorCache.TryGetValue (Type, out ctor)) {
        rc = CreateResolveContext ();
        ctor = ResolveConstructor (rc);
        if (ctor == null) {
          return null;
        }

        if (pos_args == null && ctor.Parameters.IsEmpty)
          context.Module.AttributeConstructorCache.Add (Type, ctor);
      }

      //
      // Add [module: DefaultCharSet] to all DllImport import attributes
      //
      var module = context.Module;
      if ((Type == module.PredefinedAttributes.DllImport || Type == module.PredefinedAttributes.UnmanagedFunctionPointer) && module.HasDefaultCharSet) {
        if (rc == null)
          rc = CreateResolveContext ();

        AddModuleCharSet (rc);
      }

      if (NamedArguments != null) {
        if (rc == null)
          rc = CreateResolveContext ();

        if (!ResolveNamedArguments (rc))
          return null;
      }

      resolve_error = false;
      return ctor;
    }

    MethodSpec ResolveConstructor (ResolveContext ec)
    {
      if (pos_args != null) {
        bool dynamic;
        pos_args.Resolve (ec, out dynamic);
        if (dynamic) {
          Error_AttributeArgumentIsDynamic (ec.MemberContext, loc);
          return null;
        }
      }

      return Expression.ConstructorLookup (ec, Type, ref pos_args, loc);
    }

    bool ResolveNamedArguments (ResolveContext ec)
    {
      int named_arg_count = NamedArguments.Count;
      var seen_names = new List<string> (named_arg_count);

      named_values = new List<KeyValuePair<MemberExpr, NamedArgument>> (named_arg_count);
      
      foreach (NamedArgument a in NamedArguments) {
        string name = a.Name;
        if (seen_names.Contains (name)) {
          ec.Report.Error (643, a.Location, "Duplicate named attribute `{0}' argument", name);
          continue;
        }     
  
        seen_names.Add (name);

        a.Resolve (ec);

        Expression member = Expression.MemberLookup (ec, false, Type, name, 0, Expression.MemberLookupRestrictions.ExactArity, loc);

        if (member == null) {
          member = Expression.MemberLookup (ec, true, Type, name, 0, Expression.MemberLookupRestrictions.ExactArity, loc);

          if (member != null) {
            // TODO: ec.Report.SymbolRelatedToPreviousError (member);
            Expression.ErrorIsInaccesible (ec, member.GetSignatureForError (), loc);
            return false;
          }
        }

        if (member == null){
          Expression.Error_TypeDoesNotContainDefinition (ec, Location, Type, name);
          return false;
        }
        
        if (!(member is PropertyExpr || member is FieldExpr)) {
          Error_InvalidNamedArgument (ec, a);
          return false;
        }

        ObsoleteAttribute obsolete_attr;

        if (member is PropertyExpr) {
          var pi = ((PropertyExpr) member).PropertyInfo;

          if (!pi.HasSet || !pi.HasGet || pi.IsStatic || !pi.Get.IsPublic || !pi.Set.IsPublic) {
            ec.Report.SymbolRelatedToPreviousError (pi);
            Error_InvalidNamedArgument (ec, a);
            return false;
          }

          if (!IsValidArgumentType (member.Type)) {
            ec.Report.SymbolRelatedToPreviousError (pi);
            Error_InvalidNamedArgumentType (ec, a);
            return false;
          }

          obsolete_attr = pi.GetAttributeObsolete ();
          pi.MemberDefinition.SetIsAssigned ();
        } else {
          var fi = ((FieldExpr) member).Spec;

          if (fi.IsReadOnly || fi.IsStatic || !fi.IsPublic) {
            Error_InvalidNamedArgument (ec, a);
            return false;
          }

          if (!IsValidArgumentType (member.Type)) {
            ec.Report.SymbolRelatedToPreviousError (fi);
            Error_InvalidNamedArgumentType (ec, a);
            return false;
          }

          obsolete_attr = fi.GetAttributeObsolete ();
          fi.MemberDefinition.SetIsAssigned ();
        }

        if (obsolete_attr != null && !context.IsObsolete)
          AttributeTester.Report_ObsoleteMessage (obsolete_attr, member.GetSignatureForError (), member.Location, Report);

        if (a.Type != member.Type) {
          a.Expr = Convert.ImplicitConversionRequired (ec, a.Expr, member.Type, a.Expr.Location);
        }

        if (a.Expr != null)
          named_values.Add (new KeyValuePair<MemberExpr, NamedArgument> ((MemberExpr) member, a));
      }

      return true;
    }

    /// <summary>
    ///   Get a string containing a list of valid targets for the attribute 'attr'
    /// </summary>
    public string GetValidTargets ()
    {
      StringBuilder sb = new StringBuilder ();
      AttributeTargets targets = Type.GetAttributeUsage (context.Module.PredefinedAttributes.AttributeUsage).ValidOn;

      if ((targets & AttributeTargets.Assembly) != 0)
        sb.Append ("assembly, ");

      if ((targets & AttributeTargets.Module) != 0)
        sb.Append ("module, ");

      if ((targets & AttributeTargets.Class) != 0)
        sb.Append ("class, ");

      if ((targets & AttributeTargets.Struct) != 0)
        sb.Append ("struct, ");

      if ((targets & AttributeTargets.Enum) != 0)
        sb.Append ("enum, ");

      if ((targets & AttributeTargets.Constructor) != 0)
        sb.Append ("constructor, ");

      if ((targets & AttributeTargets.Method) != 0)
        sb.Append ("method, ");

      if ((targets & AttributeTargets.Property) != 0)
        sb.Append ("property, indexer, ");

      if ((targets & AttributeTargets.Field) != 0)
        sb.Append ("field, ");

      if ((targets & AttributeTargets.Event) != 0)
        sb.Append ("event, ");

      if ((targets & AttributeTargets.Interface) != 0)
        sb.Append ("interface, ");

      if ((targets & AttributeTargets.Parameter) != 0)
        sb.Append ("parameter, ");

      if ((targets & AttributeTargets.Delegate) != 0)
        sb.Append ("delegate, ");

      if ((targets & AttributeTargets.ReturnValue) != 0)
        sb.Append ("return, ");

      if ((targets & AttributeTargets.GenericParameter) != 0)
        sb.Append ("type parameter, ");

      return sb.Remove (sb.Length - 2, 2).ToString ();
    }

    public AttributeUsageAttribute GetAttributeUsageAttribute ()
    {
      if (!arg_resolved)
        // TODO: It is not neccessary to call whole Resolve (ApplyAttribute does it now) we need only ctor args.
        // But because a lot of attribute class code must be rewritten will be better to wait...
        Resolve ();

      if (resolve_error)
        return DefaultUsageAttribute;

      AttributeUsageAttribute usage_attribute = new AttributeUsageAttribute ((AttributeTargets) ((Constant) pos_args[0].Expr).GetValue ());

      var field = GetNamedValue ("AllowMultiple") as BoolConstant;
      if (field != null)
        usage_attribute.AllowMultiple = field.Value;

      field = GetNamedValue ("Inherited") as BoolConstant;
      if (field != null)
        usage_attribute.Inherited = field.Value;

      return usage_attribute;
    }

    /// <summary>
    /// Returns custom name of indexer
    /// </summary>
    public string GetIndexerAttributeValue ()
    {
      if (!arg_resolved)
        // TODO: It is not neccessary to call whole Resolve (ApplyAttribute does it now) we need only ctor args.
        // But because a lot of attribute class code must be rewritten will be better to wait...
        Resolve ();

      if (resolve_error || pos_args.Count != 1 || !(pos_args[0].Expr is Constant))
        return null;

      return ((Constant) pos_args[0].Expr).GetValue () as string;
    }

    /// <summary>
    /// Returns condition of ConditionalAttribute
    /// </summary>
    public string GetConditionalAttributeValue ()
    {
      if (!arg_resolved)
        // TODO: It is not neccessary to call whole Resolve (ApplyAttribute does it now) we need only ctor args.
        // But because a lot of attribute class code must be rewritten will be better to wait...
        Resolve ();

      if (resolve_error)
        return null;

      return ((Constant) pos_args[0].Expr).GetValue () as string;
    }

    /// <summary>
    /// Creates the instance of ObsoleteAttribute from this attribute instance
    /// </summary>
    public ObsoleteAttribute GetObsoleteAttribute ()
    {
      if (!arg_resolved) {
        // corlib only case when obsolete is used before is resolved
        var c = Type.MemberDefinition as Class;
        if (c != null && !c.HasMembersDefined)
          c.Define ();
        
        // TODO: It is not neccessary to call whole Resolve (ApplyAttribute does it now) we need only ctor args.
        // But because a lot of attribute class code must be rewritten will be better to wait...
        Resolve ();
      }

      if (resolve_error)
        return null;

      if (pos_args == null)
        return new ObsoleteAttribute ();

      string msg = ((Constant) pos_args[0].Expr).GetValue () as string;
      if (pos_args.Count == 1)
        return new ObsoleteAttribute (msg);

      return new ObsoleteAttribute (msg, ((BoolConstant) pos_args[1].Expr).Value);
    }

    /// <summary>
    /// Returns value of CLSCompliantAttribute contructor parameter but because the method can be called
    /// before ApplyAttribute. We need to resolve the arguments.
    /// This situation occurs when class deps is differs from Emit order.  
    /// </summary>
    public bool GetClsCompliantAttributeValue ()
    {
      if (!arg_resolved)
        // TODO: It is not neccessary to call whole Resolve (ApplyAttribute does it now) we need only ctor args.
        // But because a lot of attribute class code must be rewritten will be better to wait...
        Resolve ();

      if (resolve_error)
        return false;

      return ((BoolConstant) pos_args[0].Expr).Value;
    }

    public TypeSpec GetCoClassAttributeValue ()
    {
      if (!arg_resolved)
        Resolve ();

      if (resolve_error)
        return null;

      return GetArgumentType ();
    }

    public bool CheckTarget ()
    {
      string[] valid_targets = Owner.ValidAttributeTargets;
      if (ExplicitTarget == null || ExplicitTarget == valid_targets [0]) {
        Target = Owner.AttributeTargets;
        return true;
      }

      // TODO: we can skip the first item
      if (Array.Exists (valid_targets, i => i == ExplicitTarget)) {
        switch (ExplicitTarget) {
        case "return": Target = AttributeTargets.ReturnValue; return true;
        case "param": Target = AttributeTargets.Parameter; return true;
        case "field": Target = AttributeTargets.Field; return true;
        case "method": Target = AttributeTargets.Method; return true;
        case "property": Target = AttributeTargets.Property; return true;
        case "module": Target = AttributeTargets.Module; return true;
        }
        throw new InternalErrorException ("Unknown explicit target: " + ExplicitTarget);
      }
        
      StringBuilder sb = new StringBuilder ();
      foreach (string s in valid_targets) {
        sb.Append (s);
        sb.Append (", ");
      }
      sb.Remove (sb.Length - 2, 2);
      Report.Warning (657, 1, Location,
        "`{0}' is not a valid attribute location for this declaration. Valid attribute locations for this declaration are `{1}'. All attributes in this section will be ignored",
        ExplicitTarget, sb.ToString ());
      return false;
    }

    /// <summary>
    /// Tests permitted SecurityAction for assembly or other types
    /// </summary>
    bool IsSecurityActionValid ()
    {
      SecurityAction action = GetSecurityActionValue ();
      bool for_assembly = Target == AttributeTargets.Assembly || Target == AttributeTargets.Module;
      var c = (Constant)pos_args [0].Expr;

      switch (action) {
#pragma warning disable 618
      case SecurityAction.Demand:
      case SecurityAction.Assert:
      case SecurityAction.Deny:
      case SecurityAction.PermitOnly:
      case SecurityAction.LinkDemand:
      case SecurityAction.InheritanceDemand:
        if (!for_assembly)
          return true;
        break;

      case SecurityAction.RequestMinimum:
      case SecurityAction.RequestOptional:
      case SecurityAction.RequestRefuse:
        if (for_assembly)
          return true;
        break;
#pragma warning restore 618

      default:
        Report.Error (7049, c.Location, "Security attribute `{0}' has an invalid SecurityAction value `{1}'",
          Type.GetSignatureForError (), c.GetValueAsLiteral());
        return false;
      }

      switch (Target) {
      case AttributeTargets.Assembly:
        Report.Error (7050, c.Location, "SecurityAction value `{0}' is invalid for security attributes applied to an assembly",
          c.GetSignatureForError ());
        break;
      default:
        Report.Error (7051, c.Location, "SecurityAction value `{0}' is invalid for security attributes applied to a type or a method",
          c.GetSignatureForError ());
        break;
      }

      return false;
    }

    System.Security.Permissions.SecurityAction GetSecurityActionValue ()
    {
      return (SecurityAction) ((Constant) pos_args[0].Expr).GetValue ();
    }

    /// <summary>
    /// Creates instance of SecurityAttribute class and add result of CreatePermission method to permission table.
    /// </summary>
    /// <returns></returns>
    public void ExtractSecurityPermissionSet (MethodSpec ctor, ref SecurityType permissions)
    {
#if STATIC
      object[] values = new object[pos_args.Count];
      for (int i = 0; i < values.Length; ++i)
        values[i] = ((Constant) pos_args[i].Expr).GetValue ();

      PropertyInfo[] prop;
      object[] prop_values;
      if (named_values == null) {
        prop = null;
        prop_values = null;
      } else {
        prop = new PropertyInfo[named_values.Count];
        prop_values = new object [named_values.Count];
        for (int i = 0; i < prop.Length; ++i) {
          prop [i] = ((PropertyExpr) named_values [i].Key).PropertyInfo.MetaInfo;
          prop_values [i] = ((Constant) named_values [i].Value.Expr).GetValue ();
        }
      }

      if (permissions == null)
        permissions = new SecurityType ();

      var cab = new CustomAttributeBuilder ((ConstructorInfo) ctor.GetMetaInfo (), values, prop, prop_values);
      permissions.Add (cab);
#else
      throw new NotSupportedException ();
#endif
    }

    public Constant GetNamedValue (string name)
    {
      if (named_values == null)
        return null;

      for (int i = 0; i < named_values.Count; ++i) {
        if (named_values [i].Value.Name == name)
          return named_values [i].Value.Expr as Constant;
      }

      return null;
    }

    public CharSet GetCharSetValue ()
    {
      return (CharSet) System.Enum.Parse (typeof (CharSet), ((Constant) pos_args[0].Expr).GetValue ().ToString ());
    }

    public bool HasField (string fieldName)
    {
      if (named_values == null)
        return false;

      foreach (var na in named_values) {
        if (na.Value.Name == fieldName)
          return true;
      }

      return false;
    }

    //
    // Returns true for MethodImplAttribute with MethodImplOptions.InternalCall value
    // 
    public bool IsInternalCall ()
    {
      return (GetMethodImplOptions () & MethodImplOptions.InternalCall) != 0;
    }

    public MethodImplOptions GetMethodImplOptions ()
    {
      MethodImplOptions options = 0;
      if (pos_args.Count == 1) {
        options = (MethodImplOptions) System.Enum.Parse (typeof (MethodImplOptions), ((Constant) pos_args[0].Expr).GetValue ().ToString ());
      } else if (HasField ("Value")) {
        var named = GetNamedValue ("Value");
        options = (MethodImplOptions) System.Enum.Parse (typeof (MethodImplOptions), named.GetValue ().ToString ());
      }

      return options;
    }

    //
    // Returns true for StructLayoutAttribute with LayoutKind.Explicit value
    // 
    public bool IsExplicitLayoutKind ()
    {
      if (pos_args == null || pos_args.Count != 1)
        return false;

      var value = (LayoutKind) System.Enum.Parse (typeof (LayoutKind), ((Constant) pos_args[0].Expr).GetValue ().ToString ());
      return value == LayoutKind.Explicit;
    }

    public Expression GetParameterDefaultValue ()
    {
      if (pos_args == null)
        return null;

      return pos_args[0].Expr;
    }

    public override bool Equals (object obj)
    {
      Attribute a = obj as Attribute;
      if (a == null)
        return false;

      return Type == a.Type && Target == a.Target;
    }

    public override int GetHashCode ()
    {
      return Type.GetHashCode () ^ Target.GetHashCode ();
    }

    /// <summary>
    /// Emit attribute for Attributable symbol
    /// </summary>
    public void Emit (Dictionary<Attribute, List<Attribute>> allEmitted)
    {
      var ctor = Resolve ();
      if (ctor == null)
        return;

      var predefined = context.Module.PredefinedAttributes;

      AttributeUsageAttribute usage_attr = Type.GetAttributeUsage (predefined.AttributeUsage);
      if ((usage_attr.ValidOn & Target) == 0) {
        Report.Error (592, Location, "The attribute `{0}' is not valid on this declaration type. " +
                "It is valid on `{1}' declarations only",
          GetSignatureForError (), GetValidTargets ());
        return;
      }

      byte[] cdata;
      if (pos_args == null && named_values == null) {
        cdata = AttributeEncoder.Empty;
      } else {
        AttributeEncoder encoder = new AttributeEncoder ();

        if (pos_args != null) {
          var param_types = ctor.Parameters.Types;
          for (int j = 0; j < pos_args.Count; ++j) {
            var pt = param_types[j];
            var arg_expr = pos_args[j].Expr;
            if (j == 0) {
              if ((Type == predefined.IndexerName || Type == predefined.Conditional) && arg_expr is Constant) {
                string v = ((Constant) arg_expr).GetValue () as string;
                if (!Tokenizer.IsValidIdentifier (v) || (Type == predefined.IndexerName && Tokenizer.IsKeyword (v))) {
                  context.Module.Compiler.Report.Error (633, arg_expr.Location,
                    "The argument to the `{0}' attribute must be a valid identifier", GetSignatureForError ());
                  return;
                }
              } else if (Type == predefined.Guid) {
                string v = ((StringConstant) arg_expr).Value;
                try {
                  new Guid (v);
                } catch {
                  Error_InvalidArgumentValue (Type);
                  return;
                }
              } else if (Type == predefined.AttributeUsage) {
                int v = ((IntConstant) ((EnumConstant) arg_expr).Child).Value;
                if (v == 0)
                  Error_InvalidArgumentValue (Type);
              } else if (Type == predefined.MarshalAs) {
                if (pos_args.Count == 1) {
                  var u_type = (UnmanagedType) System.Enum.Parse (typeof (UnmanagedType), ((Constant) pos_args[0].Expr).GetValue ().ToString ());
                  if (u_type == UnmanagedType.ByValArray && !(Owner is FieldBase)) {
                    Report.Error (7055, pos_args [0].Expr.Location, "Unmanaged type `ByValArray' is only valid for fields");
                  }
                }
              } else if (Type == predefined.DllImport) {
                if (pos_args.Count == 1 && pos_args[0].Expr is Constant) {
                  var value = ((Constant) pos_args[0].Expr).GetValue () as string;
                  if (string.IsNullOrEmpty (value))
                    Error_InvalidArgumentValue (Type);
                }
              } else if (Type == predefined.MethodImpl) {
                if (pos_args.Count == 1) {
                  var value = (int) ((Constant) arg_expr).GetValueAsLong ();

                  if (!IsValidMethodImplOption (value)) {
                    Error_InvalidArgumentValue (Type);
                  }
                }
              }
            }

            arg_expr.EncodeAttributeValue (context, encoder, pt, pt);
          }
        }

        if (named_values != null) {
          encoder.Encode ((ushort) named_values.Count);
          foreach (var na in named_values) {
            if (na.Key is FieldExpr)
              encoder.Encode ((byte) 0x53);
            else
              encoder.Encode ((byte) 0x54);

            encoder.Encode (na.Key.Type);
            encoder.Encode (na.Value.Name);
            na.Value.Expr.EncodeAttributeValue (context, encoder, na.Key.Type, na.Key.Type);
          }
        } else {
          encoder.EncodeEmptyNamedArguments ();
        }

        cdata = encoder.ToArray ();
      }

      if (!ctor.DeclaringType.IsConditionallyExcluded (context)) {
        try {
          foreach (Attributable target in targets)
            target.ApplyAttributeBuilder (this, ctor, cdata, predefined);
        } catch (Exception e) {
          if (e is BadImageFormat && Report.Errors > 0)
            return;

          Error_AttributeEmitError (e.Message);
          return;
        }
      }

      if (!usage_attr.AllowMultiple && allEmitted != null) {
        if (allEmitted.ContainsKey (this)) {
          var a = allEmitted [this];
          if (a == null) {
            a = new List<Attribute> (2);
            allEmitted [this] = a;
          }
          a.Add (this);
        } else {
          allEmitted.Add (this, null);
        }
      }

      if (!context.Module.Compiler.Settings.VerifyClsCompliance)
        return;

      // Here we are testing attribute arguments for array usage (error 3016)
      if (Owner.IsClsComplianceRequired ()) {
        if (pos_args != null)
          pos_args.CheckArrayAsAttribute (context.Module.Compiler);
      
        if (NamedArguments == null)
          return;

        NamedArguments.CheckArrayAsAttribute (context.Module.Compiler);
      }
    }

    private Expression GetValue () 
    {
      if (pos_args == null || pos_args.Count < 1)
        return null;

      return pos_args[0].Expr;
    }

    public string GetString () 
    {
      Expression e = GetValue ();
      if (e is StringConstant)
        return ((StringConstant)e).Value;
      return null;
    }

    public bool GetBoolean () 
    {
      Expression e = GetValue ();
      if (e is BoolConstant)
        return ((BoolConstant)e).Value;
      return false;
    }

    public TypeSpec GetArgumentType ()
    {
      TypeOf e = GetValue () as TypeOf;
      if (e == null)
        return null;
      return e.TypeArgument;
    }
  }
  
  public class Attributes
  {
    public readonly List<Attribute> Attrs;
#if FULL_AST
    public readonly List<List<Attribute>> Sections = new List<List<Attribute>> ();
#endif

    public Attributes (Attribute a)
    {
      Attrs = new List<Attribute> ();
      Attrs.Add (a);
      
#if FULL_AST
      Sections.Add (Attrs);
#endif
    }

    public Attributes (List<Attribute> attrs)
    {
      Attrs = attrs ?? new List<Attribute> ();
#if FULL_AST
      Sections.Add (attrs);
#endif
    }

    public void AddAttribute (Attribute attr)
    {
      Attrs.Add (attr);
    }

    public void AddAttributes (List<Attribute> attrs)
    {
#if FULL_AST
      Sections.Add (attrs);
#else
      Attrs.AddRange (attrs);
#endif
    }

    public void AttachTo (Attributable attributable, IMemberContext context)
    {
      foreach (Attribute a in Attrs)
        a.AttachTo (attributable, context);
    }

    public Attributes Clone ()
    {
      var al = new List<Attribute> (Attrs.Count);
      foreach (Attribute a in Attrs)
        al.Add (a.Clone ());

      return new Attributes (al);
    }

    /// <summary>
    /// Checks whether attribute target is valid for the current element
    /// </summary>
    public bool CheckTargets ()
    {
      for (int i = 0; i < Attrs.Count; ++i) {
        if (!Attrs [i].CheckTarget ())
          Attrs.RemoveAt (i--);
      }

      return true;
    }

    public void ConvertGlobalAttributes (TypeContainer member, NamespaceContainer currentNamespace, bool isGlobal)
    {
      var member_explicit_targets = member.ValidAttributeTargets;
      for (int i = 0; i < Attrs.Count; ++i) {
        var attr = Attrs[0];
        if (attr.ExplicitTarget == null)
          continue;

        int ii;
        for (ii = 0; ii < member_explicit_targets.Length; ++ii) {
          if (attr.ExplicitTarget == member_explicit_targets[ii]) {
            ii = -1;
            break;
          }
        }

        if (ii < 0 || !isGlobal)
          continue;

        member.Module.AddAttribute (attr, currentNamespace);
        Attrs.RemoveAt (i);
        --i;
      }
    }

    public bool HasResolveError()
    {
      foreach (var a in Attrs) {
        if (a.ResolveError)
          return true;
      }

      return false;
    }

    public Attribute Search (PredefinedAttribute t)
    {
      return Search (null, t);
    }

    public Attribute Search (string explicitTarget, PredefinedAttribute t)
    {
      foreach (Attribute a in Attrs) {
        if (explicitTarget != null && a.ExplicitTarget != explicitTarget)
          continue;

        if (a.ResolveTypeForComparison () == t)
          return a;
      }
      return null;
    }

    /// <summary>
    /// Returns all attributes of type 't'. Use it when attribute is AllowMultiple = true
    /// </summary>
    public Attribute[] SearchMulti (PredefinedAttribute t)
    {
      List<Attribute> ar = null;

      foreach (Attribute a in Attrs) {
        if (a.ResolveTypeForComparison () == t) {
          if (ar == null)
            ar = new List<Attribute> (Attrs.Count);
          ar.Add (a);
        }
      }

      return ar == null ? null : ar.ToArray ();
    }

    public void Emit ()
    {
      CheckTargets ();

      Dictionary<Attribute, List<Attribute>> ld = Attrs.Count > 1 ? new Dictionary<Attribute, List<Attribute>> () : null;

      foreach (Attribute a in Attrs)
        a.Emit (ld);

      if (ld == null || ld.Count == 0)
        return;

      foreach (var d in ld) {
        if (d.Value == null)
          continue;

        Attribute a = d.Key;

        foreach (Attribute collision in d.Value)
          a.Report.SymbolRelatedToPreviousError (collision.Location, "");

        a.Report.Error (579, a.Location, "The attribute `{0}' cannot be applied multiple times",
          a.GetSignatureForError ());
      }
    }

    public bool Contains (PredefinedAttribute t)
    {
      return Search (t) != null;
    }
  }

  public sealed class AttributeEncoder
  {
    [Flags]
    public enum EncodedTypeProperties
    {
      None = 0,
      DynamicType = 1,
      TypeParameter = 1 << 1
    }

    public static readonly byte[] Empty;

    byte[] buffer;
    int pos;
    const ushort Version = 1;

    static AttributeEncoder ()
    {
      Empty = new byte[4];
      Empty[0] = (byte) Version;
    }

    public AttributeEncoder ()
    {
      buffer = new byte[32];
      Encode (Version);
    }

    public void Encode (bool value)
    {
      Encode (value ? (byte) 1 : (byte) 0);
    }

    public void Encode (byte value)
    {
      if (pos == buffer.Length)
        Grow (1);

      buffer [pos++] = value;
    }

    public void Encode (sbyte value)
    {
      Encode ((byte) value);
    }

    public void Encode (short value)
    {
      if (pos + 2 > buffer.Length)
        Grow (2);

      buffer[pos++] = (byte) value;
      buffer[pos++] = (byte) (value >> 8);
    }

    public void Encode (ushort value)
    {
      Encode ((short) value);
    }

    public void Encode (int value)
    {
      if (pos + 4 > buffer.Length)
        Grow (4);

      buffer[pos++] = (byte) value;
      buffer[pos++] = (byte) (value >> 8);
      buffer[pos++] = (byte) (value >> 16);
      buffer[pos++] = (byte) (value >> 24);
    }

    public void Encode (uint value)
    {
      Encode ((int) value);
    }

    public void Encode (long value)
    {
      if (pos + 8 > buffer.Length)
        Grow (8);

      buffer[pos++] = (byte) value;
      buffer[pos++] = (byte) (value >> 8);
      buffer[pos++] = (byte) (value >> 16);
      buffer[pos++] = (byte) (value >> 24);
      buffer[pos++] = (byte) (value >> 32);
      buffer[pos++] = (byte) (value >> 40);
      buffer[pos++] = (byte) (value >> 48);
      buffer[pos++] = (byte) (value >> 56);
    }

    public void Encode (ulong value)
    {
      Encode ((long) value);
    }

    public void Encode (float value)
    {
      Encode (SingleConverter.SingleToInt32Bits (value));
    }

    public void Encode (double value)
    {
      Encode (BitConverter.DoubleToInt64Bits (value));
    }

    public void Encode (string value)
    {
      if (value == null) {
        Encode ((byte) 0xFF);
        return;
      }

      var buf = Encoding.UTF8.GetBytes(value);
      WriteCompressedValue (buf.Length);

      if (pos + buf.Length > buffer.Length)
        Grow (buf.Length);

      Buffer.BlockCopy (buf, 0, buffer, pos, buf.Length);
      pos += buf.Length;
    }

    public EncodedTypeProperties Encode (TypeSpec type)
    {
      switch (type.BuiltinType) {
      case BuiltinTypeSpec.Type.Bool:
        Encode ((byte) 0x02);
        break;
      case BuiltinTypeSpec.Type.Char:
        Encode ((byte) 0x03);
        break;
      case BuiltinTypeSpec.Type.SByte:
        Encode ((byte) 0x04);
        break;
      case BuiltinTypeSpec.Type.Byte:
        Encode ((byte) 0x05);
        break;
      case BuiltinTypeSpec.Type.Short:
        Encode ((byte) 0x06);
        break;
      case BuiltinTypeSpec.Type.UShort:
        Encode ((byte) 0x07);
        break;
      case BuiltinTypeSpec.Type.Int:
        Encode ((byte) 0x08);
        break;
      case BuiltinTypeSpec.Type.UInt:
        Encode ((byte) 0x09);
        break;
      case BuiltinTypeSpec.Type.Long:
        Encode ((byte) 0x0A);
        break;
      case BuiltinTypeSpec.Type.ULong:
        Encode ((byte) 0x0B);
        break;
      case BuiltinTypeSpec.Type.Float:
        Encode ((byte) 0x0C);
        break;
      case BuiltinTypeSpec.Type.Double:
        Encode ((byte) 0x0D);
        break;
      case BuiltinTypeSpec.Type.String:
        Encode ((byte) 0x0E);
        break;
      case BuiltinTypeSpec.Type.Type:
        Encode ((byte) 0x50);
        break;
      case BuiltinTypeSpec.Type.Object:
        Encode ((byte) 0x51);
        break;
      case BuiltinTypeSpec.Type.Dynamic:
        Encode ((byte) 0x51);
        return EncodedTypeProperties.DynamicType;
      default:
        if (type.IsArray) {
          Encode ((byte) 0x1D);
          return Encode (TypeManager.GetElementType (type));
        }

        if (type.Kind == MemberKind.Enum) {
          Encode ((byte) 0x55);
          EncodeTypeName (type);
        }

        break;
      }

      return EncodedTypeProperties.None;
    }

    public void EncodeTypeName (TypeSpec type)
    {
      var old_type = type.GetMetaInfo ();
      Encode (type.MemberDefinition.IsImported ? old_type.AssemblyQualifiedName : old_type.FullName);
    }

    public void EncodeTypeName (TypeContainer type)
    {
      Encode (type.GetSignatureForMetadata ());
    }


    //
    // Encodes single property named argument per call
    //
    public void EncodeNamedPropertyArgument (PropertySpec property, Constant value)
    {
      Encode ((ushort) 1);  // length
      Encode ((byte) 0x54); // property
      Encode (property.MemberType);
      Encode (property.Name);
      value.EncodeAttributeValue (null, this, property.MemberType, property.MemberType);
    }

    //
    // Encodes single field named argument per call
    //
    public void EncodeNamedFieldArgument (FieldSpec field, Constant value)
    {
      Encode ((ushort) 1);  // length
      Encode ((byte) 0x53); // field
      Encode (field.MemberType);
      Encode (field.Name);
      value.EncodeAttributeValue (null, this, field.MemberType, field.MemberType);
    }

    public void EncodeNamedArguments<T> (T[] members, Constant[] values) where T : MemberSpec, IInterfaceMemberSpec
    {
      Encode ((ushort) members.Length);

      for (int i = 0; i < members.Length; ++i)
      {
        var member = members[i];

        if (member.Kind == MemberKind.Field)
          Encode ((byte) 0x53);
        else if (member.Kind == MemberKind.Property)
          Encode ((byte) 0x54);
        else
          throw new NotImplementedException (member.Kind.ToString ());

        Encode (member.MemberType);
        Encode (member.Name);
        values [i].EncodeAttributeValue (null, this, member.MemberType, member.MemberType);
      }
    }

    public void EncodeEmptyNamedArguments ()
    {
      Encode ((ushort) 0);
    }

    void Grow (int inc)
    {
      int size = System.Math.Max (pos * 4, pos + inc + 2);
      Array.Resize (ref buffer, size);
    }

    void WriteCompressedValue (int value)
    {
      if (value < 0x80) {
        Encode ((byte) value);
        return;
      }

      if (value < 0x4000) {
        Encode ((byte) (0x80 | (value >> 8)));
        Encode ((byte) value);
        return;
      }

      Encode (value);
    }

    public byte[] ToArray ()
    {
      byte[] buf = new byte[pos];
      Array.Copy (buffer, buf, pos);
      return buf;
    }
  }


  /// <summary>
  /// Helper class for attribute verification routine.
  /// </summary>
  static class AttributeTester
  {
    /// <summary>
    /// Common method for Obsolete error/warning reporting.
    /// </summary>
    public static void Report_ObsoleteMessage (ObsoleteAttribute oa, string member, Location loc, Report Report)
    {
      if (oa.IsError) {
        Report.Error (619, loc, "`{0}' is obsolete: `{1}'", member, oa.Message);
        return;
      }

      if (oa.Message == null || oa.Message.Length == 0) {
        Report.Warning (612, 1, loc, "`{0}' is obsolete", member);
        return;
      }
      Report.Warning (618, 2, loc, "`{0}' is obsolete: `{1}'", member, oa.Message);
    }
  }

  //
  // Predefined attribute types
  //
  public class PredefinedAttributes
  {
    // Build-in attributes
    public readonly PredefinedAttribute ParamArray;
    public readonly PredefinedAttribute Out;

    // Optional attributes
    public readonly PredefinedAttribute Obsolete;
    public readonly PredefinedAttribute DllImport;
    public readonly PredefinedAttribute MethodImpl;
    public readonly PredefinedAttribute MarshalAs;
    public readonly PredefinedAttribute In;
    public readonly PredefinedAttribute IndexerName;
    public readonly PredefinedAttribute Conditional;
    public readonly PredefinedAttribute CLSCompliant;
    public readonly PredefinedAttribute Security;
    public readonly PredefinedAttribute Required;
    public readonly PredefinedAttribute Guid;
    public readonly PredefinedAttribute AssemblyCulture;
    public readonly PredefinedAttribute AssemblyVersion;
    public readonly PredefinedAttribute AssemblyAlgorithmId;
    public readonly PredefinedAttribute AssemblyFlags;
    public readonly PredefinedAttribute AssemblyFileVersion;
    public readonly PredefinedAttribute ComImport;
    public readonly PredefinedAttribute CoClass;
    public readonly PredefinedAttribute AttributeUsage;
    public readonly PredefinedAttribute DefaultParameterValue;
    public readonly PredefinedAttribute OptionalParameter;
    public readonly PredefinedAttribute UnverifiableCode;
    public readonly PredefinedAttribute DefaultCharset;
    public readonly PredefinedAttribute TypeForwarder;
    public readonly PredefinedAttribute FixedBuffer;
    public readonly PredefinedAttribute CompilerGenerated;
    public readonly PredefinedAttribute InternalsVisibleTo;
    public readonly PredefinedAttribute RuntimeCompatibility;
    public readonly PredefinedAttribute DebuggerHidden;
    public readonly PredefinedAttribute UnsafeValueType;
    public readonly PredefinedAttribute UnmanagedFunctionPointer;
    public readonly PredefinedDebuggerBrowsableAttribute DebuggerBrowsable;
    public readonly PredefinedAttribute DebuggerStepThrough;
    public readonly PredefinedDebuggableAttribute Debuggable;

    // New in .NET 3.5
    public readonly PredefinedAttribute Extension;

    // New in .NET 4.0
    public readonly PredefinedDynamicAttribute Dynamic;

    // New in .NET 4.5
    public readonly PredefinedStateMachineAttribute AsyncStateMachine;

    //
    // Optional types which are used as types and for member lookup
    //
    public readonly PredefinedAttribute DefaultMember;
    public readonly PredefinedDecimalAttribute DecimalConstant;
    public readonly PredefinedAttribute StructLayout;
    public readonly PredefinedAttribute FieldOffset;
    public readonly PredefinedAttribute AssemblyProduct;
    public readonly PredefinedAttribute AssemblyCompany;
    public readonly PredefinedAttribute AssemblyDescription;
    public readonly PredefinedAttribute AssemblyCopyright;
    public readonly PredefinedAttribute AssemblyTrademark;
    public readonly PredefinedAttribute CallerMemberNameAttribute;
    public readonly PredefinedAttribute CallerLineNumberAttribute;
    public readonly PredefinedAttribute CallerFilePathAttribute;

    public PredefinedAttributes (ModuleContainer module)
    {
      ParamArray = new PredefinedAttribute (module, "System", "ParamArrayAttribute");
      Out = new PredefinedAttribute (module, "System.Runtime.InteropServices", "OutAttribute");
      ParamArray.Resolve ();
      Out.Resolve ();

      Obsolete = new PredefinedAttribute (module, "System", "ObsoleteAttribute");
      DllImport = new PredefinedAttribute (module, "System.Runtime.InteropServices", "DllImportAttribute");
      MethodImpl = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "MethodImplAttribute");
      MarshalAs = new PredefinedAttribute (module, "System.Runtime.InteropServices", "MarshalAsAttribute");
      In = new PredefinedAttribute (module, "System.Runtime.InteropServices", "InAttribute");
      IndexerName = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "IndexerNameAttribute");
      Conditional = new PredefinedAttribute (module, "System.Diagnostics", "ConditionalAttribute");
      CLSCompliant = new PredefinedAttribute (module, "System", "CLSCompliantAttribute");
      Security = new PredefinedAttribute (module, "System.Security.Permissions", "SecurityAttribute");
      Required = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "RequiredAttributeAttribute");
      Guid = new PredefinedAttribute (module, "System.Runtime.InteropServices", "GuidAttribute");
      AssemblyCulture = new PredefinedAttribute (module, "System.Reflection", "AssemblyCultureAttribute");
      AssemblyVersion = new PredefinedAttribute (module, "System.Reflection", "AssemblyVersionAttribute");
      AssemblyAlgorithmId = new PredefinedAttribute (module, "System.Reflection", "AssemblyAlgorithmIdAttribute");
      AssemblyFlags = new PredefinedAttribute (module, "System.Reflection", "AssemblyFlagsAttribute");
      AssemblyFileVersion = new PredefinedAttribute (module, "System.Reflection", "AssemblyFileVersionAttribute");
      ComImport = new PredefinedAttribute (module, "System.Runtime.InteropServices", "ComImportAttribute");
      CoClass = new PredefinedAttribute (module, "System.Runtime.InteropServices", "CoClassAttribute");
      AttributeUsage = new PredefinedAttribute (module, "System", "AttributeUsageAttribute");
      DefaultParameterValue = new PredefinedAttribute (module, "System.Runtime.InteropServices", "DefaultParameterValueAttribute");
      OptionalParameter = new PredefinedAttribute (module, "System.Runtime.InteropServices", "OptionalAttribute");
      UnverifiableCode = new PredefinedAttribute (module, "System.Security", "UnverifiableCodeAttribute");

      DefaultCharset = new PredefinedAttribute (module, "System.Runtime.InteropServices", "DefaultCharSetAttribute");
      TypeForwarder = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "TypeForwardedToAttribute");
      FixedBuffer = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "FixedBufferAttribute");
      CompilerGenerated = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "CompilerGeneratedAttribute");
      InternalsVisibleTo = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "InternalsVisibleToAttribute");
      RuntimeCompatibility = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "RuntimeCompatibilityAttribute");
      DebuggerHidden = new PredefinedAttribute (module, "System.Diagnostics", "DebuggerHiddenAttribute");
      UnsafeValueType = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "UnsafeValueTypeAttribute");
      UnmanagedFunctionPointer = new PredefinedAttribute (module, "System.Runtime.InteropServices", "UnmanagedFunctionPointerAttribute");
      DebuggerBrowsable = new PredefinedDebuggerBrowsableAttribute (module, "System.Diagnostics", "DebuggerBrowsableAttribute");
      DebuggerStepThrough = new PredefinedAttribute (module, "System.Diagnostics", "DebuggerStepThroughAttribute");
      Debuggable = new PredefinedDebuggableAttribute (module, "System.Diagnostics", "DebuggableAttribute");

      Extension = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "ExtensionAttribute");

      Dynamic = new PredefinedDynamicAttribute (module, "System.Runtime.CompilerServices", "DynamicAttribute");

      DefaultMember = new PredefinedAttribute (module, "System.Reflection", "DefaultMemberAttribute");
      DecimalConstant = new PredefinedDecimalAttribute (module, "System.Runtime.CompilerServices", "DecimalConstantAttribute");
      StructLayout = new PredefinedAttribute (module, "System.Runtime.InteropServices", "StructLayoutAttribute");
      FieldOffset = new PredefinedAttribute (module, "System.Runtime.InteropServices", "FieldOffsetAttribute");
      AssemblyProduct = new PredefinedAttribute (module, "System.Reflection", "AssemblyProductAttribute");
      AssemblyCompany = new PredefinedAttribute (module, "System.Reflection", "AssemblyCompanyAttribute");
      AssemblyDescription = new PredefinedAttribute (module, "System.Reflection", "AssemblyDescriptionAttribute");
      AssemblyCopyright = new PredefinedAttribute (module, "System.Reflection", "AssemblyCopyrightAttribute");
      AssemblyTrademark = new PredefinedAttribute (module, "System.Reflection", "AssemblyTrademarkAttribute");

      AsyncStateMachine = new PredefinedStateMachineAttribute (module, "System.Runtime.CompilerServices", "AsyncStateMachineAttribute");

      CallerMemberNameAttribute = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "CallerMemberNameAttribute");
      CallerLineNumberAttribute = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "CallerLineNumberAttribute");
      CallerFilePathAttribute = new PredefinedAttribute (module, "System.Runtime.CompilerServices", "CallerFilePathAttribute");

      // TODO: Should define only attributes which are used for comparison
      const System.Reflection.BindingFlags all_fields = System.Reflection.BindingFlags.Public |
        System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.DeclaredOnly;

      foreach (var fi in GetType ().GetFields (all_fields)) {
        ((PredefinedAttribute) fi.GetValue (this)).Define ();
      }
    }
  }

  public class PredefinedAttribute : PredefinedType
  {
    protected MethodSpec ctor;

    public PredefinedAttribute (ModuleContainer module, string ns, string name)
      : base (module, MemberKind.Class, ns, name)
    {
    }

    #region Properties

    public MethodSpec Constructor {
      get {
        return ctor;
      }
    }

    #endregion

    public static bool operator == (TypeSpec type, PredefinedAttribute pa)
    {
      return type == pa.type && pa.type != null;
    }

    public static bool operator != (TypeSpec type, PredefinedAttribute pa)
    {
      return type != pa.type;
    }

    public override int GetHashCode ()
    {
      return base.GetHashCode ();
    }

    public override bool Equals (object obj)
    {
      throw new NotSupportedException ();
    }

    public void EmitAttribute (ConstructorBuilder builder)
    {
      if (ResolveBuilder ())
        builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
    }

    public void EmitAttribute (MethodBuilder builder)
    {
      if (ResolveBuilder ())
        builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
    }

    public void EmitAttribute (PropertyBuilder builder)
    {
      if (ResolveBuilder ())
        builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
    }

    public void EmitAttribute (FieldBuilder builder)
    {
      if (ResolveBuilder ())
        builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
    }

    public void EmitAttribute (TypeBuilder builder)
    {
      if (ResolveBuilder ())
        builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
    }

    public void EmitAttribute (AssemblyBuilder builder)
    {
      if (ResolveBuilder ())
        builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
    }

    public void EmitAttribute (ModuleBuilder builder)
    {
      if (ResolveBuilder ())
        builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
    }

    public void EmitAttribute (ParameterBuilder builder)
    {
      if (ResolveBuilder ())
        builder.SetCustomAttribute (GetCtorMetaInfo (), AttributeEncoder.Empty);
    }

    ConstructorInfo GetCtorMetaInfo ()
    {
      return (ConstructorInfo) ctor.GetMetaInfo ();
    }

    public bool ResolveBuilder ()
    {
      if (ctor != null)
        return true;

      //
      // Handle all parameter-less attributes as optional
      //
      if (!Define ())
        return false;

      ctor = (MethodSpec) MemberCache.FindMember (type, MemberFilter.Constructor (ParametersCompiled.EmptyReadOnlyParameters), BindingRestriction.DeclaredOnly);
      return ctor != null;
    }
  }

  public class PredefinedDebuggerBrowsableAttribute : PredefinedAttribute
  {
    public PredefinedDebuggerBrowsableAttribute (ModuleContainer module, string ns, string name)
      : base (module, ns, name)
    {
    }

    public void EmitAttribute (FieldBuilder builder, System.Diagnostics.DebuggerBrowsableState state)
    {
      var ctor = module.PredefinedMembers.DebuggerBrowsableAttributeCtor.Get ();
      if (ctor == null)
        return;

      AttributeEncoder encoder = new AttributeEncoder ();
      encoder.Encode ((int) state);
      encoder.EncodeEmptyNamedArguments ();

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

  public class PredefinedDebuggableAttribute : PredefinedAttribute
  {
    public PredefinedDebuggableAttribute (ModuleContainer module, string ns, string name)
      : base (module, ns, name)
    {
    }

    public void EmitAttribute (AssemblyBuilder builder, System.Diagnostics.DebuggableAttribute.DebuggingModes modes)
    {
      var atype = module.PredefinedAttributes.Debuggable;
      if (!atype.Define ())
        return;

      MethodSpec ctor = null;
      foreach (MethodSpec m in MemberCache.FindMembers (atype.TypeSpec, CSharp.Constructor.ConstructorName, true)) {
        if (m.Parameters.Count != 1)
          continue;

        if (m.Parameters.Types[0].Kind == MemberKind.Enum) {
          ctor = m;
        }
      }

      if (ctor == null)
        return;

      AttributeEncoder encoder = new AttributeEncoder ();
      encoder.Encode ((int) modes);
      encoder.EncodeEmptyNamedArguments ();

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

  public class PredefinedDecimalAttribute : PredefinedAttribute
  {
    public PredefinedDecimalAttribute (ModuleContainer module, string ns, string name)
      : base (module, ns, name)
    {
    }

    public void EmitAttribute (ParameterBuilder builder, decimal value, Location loc)
    {
      var ctor = module.PredefinedMembers.DecimalConstantAttributeCtor.Resolve (loc);
      if (ctor == null)
        return;

      int[] bits = decimal.GetBits (value);
      AttributeEncoder encoder = new AttributeEncoder ();
      encoder.Encode ((byte) (bits[3] >> 16));
      encoder.Encode ((byte) (bits[3] >> 31));
      encoder.Encode ((uint) bits[2]);
      encoder.Encode ((uint) bits[1]);
      encoder.Encode ((uint) bits[0]);
      encoder.EncodeEmptyNamedArguments ();

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

    public void EmitAttribute (FieldBuilder builder, decimal value, Location loc)
    {
      var ctor = module.PredefinedMembers.DecimalConstantAttributeCtor.Resolve (loc);
      if (ctor == null)
        return;

      int[] bits = decimal.GetBits (value);
      AttributeEncoder encoder = new AttributeEncoder ();
      encoder.Encode ((byte) (bits[3] >> 16));
      encoder.Encode ((byte) (bits[3] >> 31));
      encoder.Encode ((uint) bits[2]);
      encoder.Encode ((uint) bits[1]);
      encoder.Encode ((uint) bits[0]);
      encoder.EncodeEmptyNamedArguments ();

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

  public class PredefinedStateMachineAttribute : PredefinedAttribute
  {
    public PredefinedStateMachineAttribute (ModuleContainer module, string ns, string name)
      : base (module, ns, name)
    {
    }

    public void EmitAttribute (MethodBuilder builder, StateMachine type)
    {
      var predefined_ctor = module.PredefinedMembers.AsyncStateMachineAttributeCtor;

      var ctor = predefined_ctor.Get ();

      if (ctor == null)
        return;

      AttributeEncoder encoder = new AttributeEncoder ();
      encoder.EncodeTypeName (type);
      encoder.EncodeEmptyNamedArguments ();

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

  public class PredefinedDynamicAttribute : PredefinedAttribute
  {
    MethodSpec tctor;

    public PredefinedDynamicAttribute (ModuleContainer module, string ns, string name)
      : base (module, ns, name)
    {
    }

    public void EmitAttribute (FieldBuilder builder, TypeSpec type, Location loc)
    {
      if (ResolveTransformationCtor (loc)) {
        var cab = new CustomAttributeBuilder ((ConstructorInfo) tctor.GetMetaInfo (), new object[] { GetTransformationFlags (type) });
        builder.SetCustomAttribute (cab);
      }
    }

    public void EmitAttribute (ParameterBuilder builder, TypeSpec type, Location loc)
    {
      if (ResolveTransformationCtor (loc)) {
        var cab = new CustomAttributeBuilder ((ConstructorInfo) tctor.GetMetaInfo (), new object[] { GetTransformationFlags (type) });
        builder.SetCustomAttribute (cab);
      }
    }

    public void EmitAttribute (PropertyBuilder builder, TypeSpec type, Location loc)
    {
      if (ResolveTransformationCtor (loc)) {
        var cab = new CustomAttributeBuilder ((ConstructorInfo) tctor.GetMetaInfo (), new object[] { GetTransformationFlags (type) });
        builder.SetCustomAttribute (cab);
      }
    }

    public void EmitAttribute (TypeBuilder builder, TypeSpec type, Location loc)
    {
      if (ResolveTransformationCtor (loc)) {
        var cab = new CustomAttributeBuilder ((ConstructorInfo) tctor.GetMetaInfo (), new object[] { GetTransformationFlags (type) });
        builder.SetCustomAttribute (cab);
      }
    }

    //
    // When any element of the type is a dynamic type
    //
    // This method builds a transformation array for dynamic types
    // used in places where DynamicAttribute cannot be applied to.
    // It uses bool flag when type is of dynamic type and each
    // section always starts with "false" for some reason.
    //
    // LAMESPEC: This should be part of C# specification
    // 
    // Example: Func<dynamic, int, dynamic[]>
    // Transformation: { false, true, false, false, true }
    //
    static bool[] GetTransformationFlags (TypeSpec t)
    {
      bool[] element;
      var ac = t as ArrayContainer;
      if (ac != null) {
        element = GetTransformationFlags (ac.Element);
        if (element == null)
          return new bool[] { false, false };

        bool[] res = new bool[element.Length + 1];
        res[0] = false;
        Array.Copy (element, 0, res, 1, element.Length);
        return res;
      }

      if (t == null)
        return null;

      if (t.IsGeneric) {
        List<bool> transform = null;
        var targs = t.TypeArguments;
        for (int i = 0; i < targs.Length; ++i) {
          element = GetTransformationFlags (targs[i]);
          if (element != null) {
            if (transform == null) {
              transform = new List<bool> ();
              for (int ii = 0; ii <= i; ++ii)
                transform.Add (false);
            }

            transform.AddRange (element);
          } else if (transform != null) {
            transform.Add (false);
          }
        }

        if (transform != null)
          return transform.ToArray ();
      }

      if (t.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
        return new bool[] { true };

      return null;
    }

    bool ResolveTransformationCtor (Location loc)
    {
      if (tctor != null)
        return true;

      tctor = module.PredefinedMembers.DynamicAttributeCtor.Resolve (loc);
      return tctor != null;
    }
  }
}