source: trunk/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Parser/mcs/method.cs @ 16240

//
// method.cs: Method based declarations
//
// Authors: Miguel de Icaza (miguel@gnu.org)
//          Martin Baulig (martin@ximian.com)
//          Marek Safar (marek.safar@gmail.com)
//
// Dual licensed under the terms of the MIT X11 or GNU GPL
//
// Copyright 2001, 2002, 2003 Ximian, Inc (http://www.ximian.com)
// Copyright 2004-2008 Novell, Inc
// Copyright 2011 Xamarin Inc.
//

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

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

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

namespace Mono.CSharp {

  public abstract class MethodCore : InterfaceMemberBase, IParametersMember
  {
    protected ParametersCompiled parameters;
    protected ToplevelBlock block;
    protected MethodSpec spec;

    protected MethodCore (TypeDefinition parent, FullNamedExpression type, Modifiers mod, Modifiers allowed_mod,
      MemberName name, Attributes attrs, ParametersCompiled parameters)
      : base (parent, type, mod, allowed_mod, name, attrs)
    {
      this.parameters = parameters;
    }

    public override Variance ExpectedMemberTypeVariance {
      get {
        return Variance.Covariant;
      }
    }

    //
    //  Returns the System.Type array for the parameters of this method
    //
    public TypeSpec [] ParameterTypes {
      get {
        return parameters.Types;
      }
    }

    public ParametersCompiled ParameterInfo {
      get {
        return parameters;
      }
    }

    AParametersCollection IParametersMember.Parameters {
      get { return parameters; }
    }
    
    public ToplevelBlock Block {
      get {
        return block;
      }

      set {
        block = value;
      }
    }

    public CallingConventions CallingConventions {
      get {
        CallingConventions cc = parameters.CallingConvention;
        if (!IsInterface)
          if ((ModFlags & Modifiers.STATIC) == 0)
            cc |= CallingConventions.HasThis;

        // FIXME: How is `ExplicitThis' used in C#?
      
        return cc;
      }
    }

    protected override bool CheckOverrideAgainstBase (MemberSpec base_member)
    {
      bool res = base.CheckOverrideAgainstBase (base_member);

      //
      // Check that the permissions are not being changed
      //
      if (!CheckAccessModifiers (this, base_member)) {
        Error_CannotChangeAccessModifiers (this, base_member);
        res = false;
      }

      return res;
    }

    protected override bool CheckBase ()
    {
      // Check whether arguments were correct.
      if (!DefineParameters (parameters))
        return false;

      return base.CheckBase ();
    }

    //
    //   Represents header string for documentation comment.
    //
    public override string DocCommentHeader 
    {
      get { return "M:"; }
    }

    public override void Emit ()
    {
      if ((ModFlags & Modifiers.COMPILER_GENERATED) == 0) {
        parameters.CheckConstraints (this);
      }

      base.Emit ();
    }

    public override bool EnableOverloadChecks (MemberCore overload)
    {
      if (overload is MethodCore) {
        caching_flags |= Flags.MethodOverloadsExist;
        return true;
      }

      if (overload is AbstractPropertyEventMethod)
        return true;

      return base.EnableOverloadChecks (overload);
    }

    public override string GetSignatureForDocumentation ()
    {
      string s = base.GetSignatureForDocumentation ();
      if (MemberName.Arity > 0)
        s += "``" + MemberName.Arity.ToString ();

      return s + parameters.GetSignatureForDocumentation ();
    }

    public MethodSpec Spec {
      get { return spec; }
    }

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

      if (parameters.HasArglist) {
        Report.Warning (3000, 1, Location, "Methods with variable arguments are not CLS-compliant");
      }

      if (member_type != null && !member_type.IsCLSCompliant ()) {
        Report.Warning (3002, 1, Location, "Return type of `{0}' is not CLS-compliant",
          GetSignatureForError ());
      }

      parameters.VerifyClsCompliance (this);
      return true;
    }
  }

  public interface IGenericMethodDefinition : IMethodDefinition
  {
    TypeParameterSpec[] TypeParameters { get; }
    int TypeParametersCount { get; }

//    MethodInfo MakeGenericMethod (TypeSpec[] targs);
  }

  public sealed class MethodSpec : MemberSpec, IParametersMember
  {
    MethodBase inflatedMetaInfo;
    AParametersCollection parameters;
    TypeSpec returnType;

    TypeSpec[] targs;
    TypeParameterSpec[] constraints;

    public static readonly MethodSpec Excluded = new MethodSpec (MemberKind.Method, InternalType.FakeInternalType, null, null, ParametersCompiled.EmptyReadOnlyParameters, 0);

    public MethodSpec (MemberKind kind, TypeSpec declaringType, IMethodDefinition details, TypeSpec returnType,
      AParametersCollection parameters, Modifiers modifiers)
      : base (kind, declaringType, details, modifiers)
    {
      this.parameters = parameters;
      this.returnType = returnType;
    }

    #region Properties

    public override int Arity {
      get {
        return IsGeneric ? GenericDefinition.TypeParametersCount : 0;
      }
    }

    public TypeParameterSpec[] Constraints {
      get {
        if (constraints == null && IsGeneric)
          constraints = GenericDefinition.TypeParameters;

        return constraints;
      }
    }

    public bool IsConstructor {
      get {
        return Kind == MemberKind.Constructor;
      }
    }

    public new IMethodDefinition MemberDefinition {
      get {
        return (IMethodDefinition) definition;
      }
    }

    public IGenericMethodDefinition GenericDefinition {
      get {
        return (IGenericMethodDefinition) definition;
      }
    }

    public bool IsAsync {
      get {
        return (Modifiers & Modifiers.ASYNC) != 0;
      }
    }

    public bool IsExtensionMethod {
      get {
        return IsStatic && parameters.HasExtensionMethodType;
      }
    }

    public bool IsSealed {
      get {
        return (Modifiers & Modifiers.SEALED) != 0;
      }
    }

    // When is virtual or abstract
    public bool IsVirtual {
      get {
        return (Modifiers & (Modifiers.VIRTUAL | Modifiers.ABSTRACT | Modifiers.OVERRIDE)) != 0;
      }
    }

    public bool IsReservedMethod {
      get {
        return Kind == MemberKind.Operator || IsAccessor;
      }
    }

    TypeSpec IInterfaceMemberSpec.MemberType {
      get {
        return returnType;
      }
    }

    public AParametersCollection Parameters {
      get { 
        return parameters;
      }
    }

    public TypeSpec ReturnType {
      get {
        return returnType;
      }
    }

    public TypeSpec[] TypeArguments {
      get {
        return targs;
      }
    }

    #endregion

    public MethodSpec GetGenericMethodDefinition ()
    {
      if (!IsGeneric && !DeclaringType.IsGeneric)
        return this;

      return MemberCache.GetMember (declaringType, this);
    }

    public MethodBase GetMetaInfo ()
    {
      //
      // inflatedMetaInfo is extra field needed for cases where we
      // inflate method but another nested type can later inflate
      // again (the cache would be build with inflated metaInfo) and
      // TypeBuilder can work with method definitions only
      //
      if (inflatedMetaInfo == null) {
        if ((state & StateFlags.PendingMetaInflate) != 0) {
          var dt_meta = DeclaringType.GetMetaInfo ();

          if (DeclaringType.IsTypeBuilder) {
            if (IsConstructor)
              inflatedMetaInfo = TypeBuilder.GetConstructor (dt_meta, (ConstructorInfo) MemberDefinition.Metadata);
            else
              inflatedMetaInfo = TypeBuilder.GetMethod (dt_meta, (MethodInfo) MemberDefinition.Metadata);
          } else {
#if STATIC
            // it should not be reached
            throw new NotImplementedException ();
#else
            inflatedMetaInfo = MethodInfo.GetMethodFromHandle (MemberDefinition.Metadata.MethodHandle, dt_meta.TypeHandle);
#endif
          }

          state &= ~StateFlags.PendingMetaInflate;
        } else {
          inflatedMetaInfo = MemberDefinition.Metadata;
        }
      }

      if ((state & StateFlags.PendingMakeMethod) != 0) {
        var sre_targs = new MetaType[targs.Length];
        for (int i = 0; i < sre_targs.Length; ++i)
          sre_targs[i] = targs[i].GetMetaInfo ();

        inflatedMetaInfo = ((MethodInfo) inflatedMetaInfo).MakeGenericMethod (sre_targs);
        state &= ~StateFlags.PendingMakeMethod;
      }

      return inflatedMetaInfo;
    }

    public override string GetSignatureForDocumentation ()
    {
      string name;
      switch (Kind) {
      case MemberKind.Constructor:
        name = "#ctor";
        break;
      case MemberKind.Method:
        if (Arity > 0)
          name = Name + "``" + Arity.ToString ();
        else
          name = Name;

        break;
      default:
        name = Name;
        break;
      }

      name = DeclaringType.GetSignatureForDocumentation () + "." + name + parameters.GetSignatureForDocumentation ();
      if (Kind == MemberKind.Operator) {
        var op = Operator.GetType (Name).Value;
        if (op == Operator.OpType.Explicit || op == Operator.OpType.Implicit) {
          name += "~" + ReturnType.GetSignatureForDocumentation ();
        }
      }

      return name;
    }

    public override string GetSignatureForError ()
    {
      string name;
      if (IsConstructor) {
        name = DeclaringType.GetSignatureForError () + "." + DeclaringType.Name;
      } else if (Kind == MemberKind.Operator) {
        var op = Operator.GetType (Name).Value;
        if (op == Operator.OpType.Implicit || op == Operator.OpType.Explicit) {
          name = DeclaringType.GetSignatureForError () + "." + Operator.GetName (op) + " operator " + returnType.GetSignatureForError ();
        } else {
          name = DeclaringType.GetSignatureForError () + ".operator " + Operator.GetName (op);
        }
      } else if (IsAccessor) {
        int split = Name.IndexOf ('_');
        name = Name.Substring (split + 1);
        var postfix = Name.Substring (0, split);
        if (split == 3) {
          var pc = parameters.Count;
          if (pc > 0 && postfix == "get") {
            name = "this" + parameters.GetSignatureForError ("[", "]", pc);
          } else if (pc > 1 && postfix == "set") {
            name = "this" + parameters.GetSignatureForError ("[", "]", pc - 1);
          }
        }

        return DeclaringType.GetSignatureForError () + "." + name + "." + postfix;
      } else {
        name = base.GetSignatureForError ();
        if (targs != null)
          name += "<" + TypeManager.CSharpName (targs) + ">";
        else if (IsGeneric)
          name += "<" + TypeManager.CSharpName (GenericDefinition.TypeParameters) + ">";
      }

      return name + parameters.GetSignatureForError ();
    }

    public override MemberSpec InflateMember (TypeParameterInflator inflator)
    {
      var ms = (MethodSpec) base.InflateMember (inflator);
      ms.inflatedMetaInfo = null;
      ms.returnType = inflator.Inflate (returnType);
      ms.parameters = parameters.Inflate (inflator);
      if (IsGeneric)
        ms.constraints = TypeParameterSpec.InflateConstraints (inflator, Constraints);

      return ms;
    }

    public MethodSpec MakeGenericMethod (IMemberContext context, params TypeSpec[] targs)
    {
      if (targs == null)
        throw new ArgumentNullException ();
// TODO MemberCache
//      if (generic_intances != null && generic_intances.TryGetValue (targs, out ginstance))
//        return ginstance;

      //if (generic_intances == null)
      //    generic_intances = new Dictionary<TypeSpec[], Method> (TypeSpecArrayComparer.Default);

      var inflator = new TypeParameterInflator (context, DeclaringType, GenericDefinition.TypeParameters, targs);

      var inflated = (MethodSpec) MemberwiseClone ();
      inflated.declaringType = inflator.TypeInstance;
      inflated.returnType = inflator.Inflate (returnType);
      inflated.parameters = parameters.Inflate (inflator);
      inflated.targs = targs;
      inflated.constraints = TypeParameterSpec.InflateConstraints (inflator, constraints ?? GenericDefinition.TypeParameters);
      inflated.state |= StateFlags.PendingMakeMethod;

      //      if (inflated.parent == null)
      //        inflated.parent = parent;

      //generic_intances.Add (targs, inflated);
      return inflated;
    }

    public MethodSpec Mutate (TypeParameterMutator mutator)
    {
      var targs = TypeArguments;
      if (targs != null)
        targs = mutator.Mutate (targs);

      var decl = DeclaringType;
      if (DeclaringType.IsGenericOrParentIsGeneric) {
        decl = mutator.Mutate (decl);
      }

      if (targs == TypeArguments && decl == DeclaringType)
        return this;

      var ms = (MethodSpec) MemberwiseClone ();
      if (decl != DeclaringType) {
        ms.inflatedMetaInfo = null;
        ms.declaringType = decl;
        ms.state |= StateFlags.PendingMetaInflate;
      }

      if (targs != null) {
        ms.targs = targs;
        ms.state |= StateFlags.PendingMakeMethod;
      }

      return ms;
    }

    public override List<MissingTypeSpecReference> ResolveMissingDependencies (MemberSpec caller)
    {
      var missing = returnType.ResolveMissingDependencies (this);
      foreach (var pt in parameters.Types) {
        var m = pt.GetMissingDependencies (this);
        if (m == null)
          continue;

        if (missing == null)
          missing = new List<MissingTypeSpecReference> ();

        missing.AddRange (m);
      }

      if (Arity > 0) {
        foreach (var tp in GenericDefinition.TypeParameters) {
          var m = tp.GetMissingDependencies (this);

          if (m == null)
            continue;

          if (missing == null)
            missing = new List<MissingTypeSpecReference> ();

          missing.AddRange (m);
        }
      }

      return missing;     
    }
  }

  public abstract class MethodOrOperator : MethodCore, IMethodData, IMethodDefinition
  {
    ReturnParameter return_attributes;
    SecurityType declarative_security;
    protected MethodData MethodData;

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

    protected MethodOrOperator (TypeDefinition parent, FullNamedExpression type, Modifiers mod, Modifiers allowed_mod, MemberName name,
        Attributes attrs, ParametersCompiled parameters)
      : base (parent, type, mod, allowed_mod, name, attrs, parameters)
    {
    }

    public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
    {
      if (a.Target == AttributeTargets.ReturnValue) {
        if (return_attributes == null)
          return_attributes = new ReturnParameter (this, MethodBuilder, Location);

        return_attributes.ApplyAttributeBuilder (a, ctor, cdata, pa);
        return;
      }

      if (a.Type == pa.MethodImpl) {
        if ((ModFlags & Modifiers.ASYNC) != 0 && (a.GetMethodImplOptions () & MethodImplOptions.Synchronized) != 0) {
          Report.Error (4015, a.Location, "`{0}': Async methods cannot use `MethodImplOptions.Synchronized'",
            GetSignatureForError ());
        }

        is_external_implementation = a.IsInternalCall ();
      } else if (a.Type == pa.DllImport) {
        const Modifiers extern_static = Modifiers.EXTERN | Modifiers.STATIC;
        if ((ModFlags & extern_static) != extern_static) {
          Report.Error (601, a.Location, "The DllImport attribute must be specified on a method marked `static' and `extern'");
        }

        if (MemberName.IsGeneric || Parent.IsGenericOrParentIsGeneric) {
          Report.Error (7042, a.Location, 
            "The DllImport attribute cannot be applied to a method that is generic or contained in a generic type");
        }

        is_external_implementation = true;
      }

      if (a.IsValidSecurityAttribute ()) {
        a.ExtractSecurityPermissionSet (ctor, ref declarative_security);
        return;
      }

      if (MethodBuilder != null)
        MethodBuilder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), cdata);
    }

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

    MethodBase IMethodDefinition.Metadata {
      get {
        return MethodData.MethodBuilder;
      }
    }

    // TODO: Remove and use MethodData abstraction
    public MethodBuilder MethodBuilder {
      get {
        return MethodData.MethodBuilder;
      }
    }

    protected override bool CheckForDuplications ()
    {
      return Parent.MemberCache.CheckExistingMembersOverloads (this, parameters);
    }

    public virtual EmitContext CreateEmitContext (ILGenerator ig, SourceMethodBuilder sourceMethod)
    {
      return new EmitContext (this, ig, MemberType, sourceMethod);
    }

    public override bool Define ()
    {
      if (!base.Define ())
        return false;

      if (!CheckBase ())
        return false;

      MemberKind kind;
      if (this is Operator)
        kind = MemberKind.Operator;
      else if (this is Destructor)
        kind = MemberKind.Destructor;
      else
        kind = MemberKind.Method;

      string explicit_name;

      if (IsPartialDefinition) {
        caching_flags &= ~Flags.Excluded_Undetected;
        caching_flags |= Flags.Excluded;

        // Add to member cache only when a partial method implementation has not been found yet
        if ((caching_flags & Flags.PartialDefinitionExists) != 0)
          return true;

        if (IsExplicitImpl)
          return true;

        explicit_name = null;
      } else {
        MethodData = new MethodData (this, ModFlags, flags, this, base_method);

        if (!MethodData.Define (Parent.PartialContainer, GetFullName (MemberName)))
          return false;

        explicit_name = MethodData.MetadataName;
      }

      spec = new MethodSpec (kind, Parent.Definition, this, ReturnType, parameters, ModFlags);
      if (MemberName.Arity > 0)
        spec.IsGeneric = true;

      Parent.MemberCache.AddMember (this, explicit_name, spec);

      return true;
    }

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

      CheckAbstractAndExtern (block != null);

      if ((ModFlags & Modifiers.PARTIAL) != 0) {
        for (int i = 0; i < parameters.Count; ++i) {
          IParameterData p = parameters.FixedParameters [i];
          if ((p.ModFlags & Parameter.Modifier.OUT) != 0) {
            Report.Error (752, Location, "`{0}': A partial method parameters cannot use `out' modifier",
              GetSignatureForError ());
          }

          if (p.HasDefaultValue && IsPartialImplementation)
            ((Parameter) p).Warning_UselessOptionalParameter (Report);
        }
      }
    }

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

      if (MemberType.IsStatic) {
        Error_StaticReturnType ();
      }
    }

    public override void Emit ()
    {
      if ((ModFlags & Modifiers.COMPILER_GENERATED) != 0 && !Parent.IsCompilerGenerated)
        Module.PredefinedAttributes.CompilerGenerated.EmitAttribute (MethodBuilder);
      if ((ModFlags & Modifiers.DEBUGGER_HIDDEN) != 0)
        Module.PredefinedAttributes.DebuggerHidden.EmitAttribute (MethodBuilder);
      if ((ModFlags & Modifiers.DEBUGGER_STEP_THROUGH) != 0)
        Module.PredefinedAttributes.DebuggerStepThrough.EmitAttribute (MethodBuilder);

      if (ReturnType.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
        return_attributes = new ReturnParameter (this, MethodBuilder, Location);
        Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder);
      } else if (ReturnType.HasDynamicElement) {
        return_attributes = new ReturnParameter (this, MethodBuilder, Location);
        Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder, ReturnType, Location);
      }

      if (OptAttributes != null)
        OptAttributes.Emit ();

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

      if (type_expr != null)
        ConstraintChecker.Check (this, member_type, type_expr.Location);

      base.Emit ();

      if (MethodData != null)
        MethodData.Emit (Parent);

      if (block != null && block.StateMachine is AsyncTaskStorey) {
        var psm = Module.PredefinedAttributes.AsyncStateMachine;
        psm.EmitAttribute (MethodBuilder, block.StateMachine);
      }

      if ((ModFlags & Modifiers.PARTIAL) == 0)
        Block = null;
    }

    protected void Error_ConditionalAttributeIsNotValid ()
    {
      Report.Error (577, Location,
        "Conditional not valid on `{0}' because it is a constructor, destructor, operator or explicit interface implementation",
        GetSignatureForError ());
    }

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

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

    public override string[] ValidAttributeTargets {
      get {
        return attribute_targets;
      }
    }

    #region IMethodData Members

    bool IMethodData.IsAccessor {
      get {
        return false;
      }
    }

    public TypeSpec ReturnType {
      get {
        return MemberType;
      }
    }

    public MemberName MethodName {
      get {
        return MemberName;
      }
    }

    /// <summary>
    /// Returns true if method has conditional attribute and the conditions is not defined (method is excluded).
    /// </summary>
    public override string[] ConditionalConditions ()
    {
      if ((caching_flags & (Flags.Excluded_Undetected | Flags.Excluded)) == 0)
        return null;

      if ((ModFlags & Modifiers.PARTIAL) != 0 && (caching_flags & Flags.Excluded) != 0)
        return new string [0];

      caching_flags &= ~Flags.Excluded_Undetected;
      string[] conditions;

      if (base_method == null) {
        if (OptAttributes == null)
          return null;

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

        conditions = new string[attrs.Length];
        for (int i = 0; i < conditions.Length; ++i)
          conditions[i] = attrs[i].GetConditionalAttributeValue ();
      } else {
        conditions = base_method.MemberDefinition.ConditionalConditions();
      }

      if (conditions != null)
        caching_flags |= Flags.Excluded;

      return conditions;
    }

    #endregion

    public virtual void PrepareEmit ()
    {
      var mb = MethodData.DefineMethodBuilder (Parent);

      if (CurrentTypeParameters != null) {
        string[] gnames = new string[CurrentTypeParameters.Count];
        for (int i = 0; i < gnames.Length; ++i) {
          gnames[i] = CurrentTypeParameters[i].Name;
        }

        var gen_params = MethodBuilder.DefineGenericParameters (gnames);

        for (int i = 0; i < CurrentTypeParameters.Count; ++i) {
          var tp = CurrentTypeParameters[i];

          tp.Define (gen_params[i]);
        }
      }

      //
      // Generic method has been already defined to resolve method parameters
      // correctly when they use type parameters
      //
      mb.SetParameters (parameters.GetMetaInfo ());
      mb.SetReturnType (ReturnType.GetMetaInfo ());
    }

    public override void WriteDebugSymbol (MonoSymbolFile file)
    {
      if (MethodData != null && !IsPartialDefinition)
        MethodData.WriteDebugSymbol (file);
    }
  }

  public class Method : MethodOrOperator, IGenericMethodDefinition
  {
    Method partialMethodImplementation;

    public Method (TypeDefinition parent, FullNamedExpression return_type, Modifiers mod, MemberName name, ParametersCompiled parameters, Attributes attrs)
      : base (parent, return_type, mod,
        parent.PartialContainer.Kind == MemberKind.Interface ? AllowedModifiersInterface :
        parent.PartialContainer.Kind == MemberKind.Struct ? AllowedModifiersStruct | Modifiers.ASYNC :
        AllowedModifiersClass | Modifiers.ASYNC,
        name, attrs, parameters)
    {
    }

    protected Method (TypeDefinition parent, FullNamedExpression return_type, Modifiers mod, Modifiers amod,
          MemberName name, ParametersCompiled parameters, Attributes attrs)
      : base (parent, return_type, mod, amod, name, attrs, parameters)
    {
    }

    #region Properties

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

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

    public int TypeParametersCount {
      get {
        return CurrentTypeParameters == null ? 0 : CurrentTypeParameters.Count;
      }
    }

    #endregion

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

    public static Method Create (TypeDefinition parent, FullNamedExpression returnType, Modifiers mod,
           MemberName name, ParametersCompiled parameters, Attributes attrs)
    {
      var m = new Method (parent, returnType, mod, name, parameters, attrs);

      if ((mod & Modifiers.PARTIAL) != 0) {
        const Modifiers invalid_partial_mod = Modifiers.AccessibilityMask | Modifiers.ABSTRACT | Modifiers.EXTERN |
          Modifiers.NEW | Modifiers.OVERRIDE | Modifiers.SEALED | Modifiers.VIRTUAL;

        if ((mod & invalid_partial_mod) != 0) {
          m.Report.Error (750, m.Location,
            "A partial method cannot define access modifier or any of abstract, extern, new, override, sealed, or virtual modifiers");
          mod &= ~invalid_partial_mod;
        }

        if ((parent.ModFlags & Modifiers.PARTIAL) == 0) {
          m.Report.Error (751, m.Location, 
            "A partial method must be declared within a partial class or partial struct");
        }
      }

      if ((mod & Modifiers.STATIC) == 0 && parameters.HasExtensionMethodType) {
        m.Report.Error (1105, m.Location, "`{0}': Extension methods must be declared static",
          m.GetSignatureForError ());
      }


      return m;
    }

    public override string GetSignatureForError()
    {
      return base.GetSignatureForError () + parameters.GetSignatureForError ();
    }

    void Error_DuplicateEntryPoint (Method b)
    {
      Report.Error (17, b.Location,
        "Program `{0}' has more than one entry point defined: `{1}'",
        b.Module.Builder.ScopeName, b.GetSignatureForError ());
    }

    bool IsEntryPoint ()
    {
      if (ReturnType.Kind != MemberKind.Void && ReturnType.BuiltinType != BuiltinTypeSpec.Type.Int)
        return false;

      if (parameters.IsEmpty)
        return true;

      if (parameters.Count > 1)
        return false;

      var ac = parameters.Types [0] as ArrayContainer;
      return ac != null && ac.Rank == 1 && ac.Element.BuiltinType == BuiltinTypeSpec.Type.String &&
          (parameters[0].ModFlags & Parameter.Modifier.RefOutMask) == 0;
    }

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

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

    public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
    {
      if (a.Type == pa.Conditional) {
        if (IsExplicitImpl) {
          Error_ConditionalAttributeIsNotValid ();
          return;
        }

        if ((ModFlags & Modifiers.OVERRIDE) != 0) {
          Report.Error (243, Location, "Conditional not valid on `{0}' because it is an override method", GetSignatureForError ());
          return;
        }

        if (ReturnType.Kind != MemberKind.Void) {
          Report.Error (578, Location, "Conditional not valid on `{0}' because its return type is not void", GetSignatureForError ());
          return;
        }

        if (IsInterface) {
          Report.Error (582, Location, "Conditional not valid on interface members");
          return;
        }

        if (MethodData.implementing != null) {
          Report.SymbolRelatedToPreviousError (MethodData.implementing.DeclaringType);
          Report.Error (629, Location, "Conditional member `{0}' cannot implement interface member `{1}'",
            GetSignatureForError (), TypeManager.CSharpSignature (MethodData.implementing));
          return;
        }

        for (int i = 0; i < parameters.Count; ++i) {
          if ((parameters.FixedParameters [i].ModFlags & Parameter.Modifier.OUT) != 0) {
            Report.Error (685, Location, "Conditional method `{0}' cannot have an out parameter", GetSignatureForError ());
            return;
          }
        }
      }

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

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

    void CreateTypeParameters ()
    {
      var tparams = MemberName.TypeParameters;
      var parent_tparams = Parent.TypeParametersAll;

      for (int i = 0; i < MemberName.Arity; i++) {
        string type_argument_name = tparams[i].MemberName.Name;

        if (block == null) {
          int idx = parameters.GetParameterIndexByName (type_argument_name);
          if (idx >= 0) {
            var b = block;
            if (b == null)
              b = new ToplevelBlock (Compiler, Location);

            b.Error_AlreadyDeclaredTypeParameter (type_argument_name, parameters[i].Location);
          }
        } else {
          INamedBlockVariable variable = null;
          block.GetLocalName (type_argument_name, block, ref variable);
          if (variable != null)
            variable.Block.Error_AlreadyDeclaredTypeParameter (type_argument_name, variable.Location);
        }

        if (parent_tparams != null) {
          var tp = parent_tparams.Find (type_argument_name);
          if (tp != null) {
            tparams[i].WarningParentNameConflict (tp);
          }
        }
      }

      tparams.Create (null, 0, Parent);
    }

    protected virtual void DefineTypeParameters ()
    {
      var tparams = CurrentTypeParameters;

      TypeParameterSpec[] base_tparams = null;
      TypeParameterSpec[] base_decl_tparams = TypeParameterSpec.EmptyTypes;
      TypeSpec[] base_targs = TypeSpec.EmptyTypes;
      if (((ModFlags & Modifiers.OVERRIDE) != 0 || IsExplicitImpl)) {
        MethodSpec base_override = base_method ?? MethodData.implementing;

        if (base_override != null) {
          base_tparams = base_override.GenericDefinition.TypeParameters;

          if (base_override.DeclaringType.IsGeneric) {
            base_decl_tparams = base_override.DeclaringType.MemberDefinition.TypeParameters;

            if (base_method != null) {
              var base_type_parent = CurrentType;
              while (base_type_parent.BaseType != base_override.DeclaringType) {
                base_type_parent = base_type_parent.BaseType;
              }

              base_targs = base_type_parent.BaseType.TypeArguments;
            } else {
              foreach (var iface in Parent.CurrentType.Interfaces) {
                if (iface == base_override.DeclaringType) {
                  base_targs = iface.TypeArguments;
                  break;
                }
              }
            }
          }

          if (base_override.IsGeneric) {
            ObsoleteAttribute oa;
            foreach (var base_tp in base_tparams) {
              oa = base_tp.BaseType.GetAttributeObsolete ();
              if (oa != null) {
                AttributeTester.Report_ObsoleteMessage (oa, base_tp.BaseType.GetSignatureForError (), Location, Report);
              }

              if (base_tp.InterfacesDefined != null) {
                foreach (var iface in base_tp.InterfacesDefined) {
                  oa = iface.GetAttributeObsolete ();
                  if (oa != null) {
                    AttributeTester.Report_ObsoleteMessage (oa, iface.GetSignatureForError (), Location, Report);
                  }
                }
              }
            }

            if (base_decl_tparams.Length != 0) {
              base_decl_tparams = base_decl_tparams.Concat (base_tparams).ToArray ();
              base_targs = base_targs.Concat (tparams.Types).ToArray ();
            } else {
              base_decl_tparams = base_tparams;
              base_targs = tparams.Types;
            }
          }
        }
      }

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

        if (base_tparams == null) {
          tp.ResolveConstraints (this);
          continue;
        }

        //
        // Copy base constraints for override/explicit methods
        //
        var base_tparam = base_tparams [i];
        var local_tparam = tp.Type;
        local_tparam.SpecialConstraint = base_tparam.SpecialConstraint;

        var inflator = new TypeParameterInflator (this, CurrentType, base_decl_tparams, base_targs);
        base_tparam.InflateConstraints (inflator, local_tparam);

        //
        // Check all type argument constraints for possible collision or unification
        // introduced by inflating inherited constraints in this context
        //
        // Conflict example:
        //
        // class A<T> { virtual void Foo<U> () where U : class, T {} }
        // class B : A<int> { override void Foo<U> {} }
        //
        var local_tparam_targs = local_tparam.TypeArguments;
        if (local_tparam_targs != null) {
          for (int ii = 0; ii < local_tparam_targs.Length; ++ii) {
            var ta = local_tparam_targs [ii];
            if (!ta.IsClass && !ta.IsStruct)
              continue;

            TypeSpec[] unique_tparams = null;
            for (int iii = ii + 1; iii < local_tparam_targs.Length; ++iii) {
              //
              // Remove any identical or unified constraint types
              //
              var tparam_checked = local_tparam_targs [iii];
              if (TypeSpecComparer.IsEqual (ta, tparam_checked) || TypeSpec.IsBaseClass (ta, tparam_checked, false)) {
                unique_tparams = new TypeSpec[local_tparam_targs.Length - 1];
                Array.Copy (local_tparam_targs, 0, unique_tparams, 0, iii);
                Array.Copy (local_tparam_targs, iii + 1, unique_tparams, iii, local_tparam_targs.Length - iii - 1);
              } else if (!TypeSpec.IsBaseClass (tparam_checked, ta, false)) {
                Constraints.Error_ConflictingConstraints (this, local_tparam, ta, tparam_checked, Location);
              }
            }

            if (unique_tparams != null) {
              local_tparam_targs = unique_tparams;
              local_tparam.TypeArguments = local_tparam_targs;
              continue;
            }

            Constraints.CheckConflictingInheritedConstraint (local_tparam, ta, this, Location);
          }
        }
      }

      if (base_tparams == null && MethodData != null && MethodData.implementing != null) {
        CheckImplementingMethodConstraints (Parent, spec, MethodData.implementing);
      }
    }

    public static bool CheckImplementingMethodConstraints (TypeContainer container, MethodSpec method, MethodSpec baseMethod)
    {
      var tparams = method.Constraints;
      var base_tparams = baseMethod.Constraints;
      for (int i = 0; i < tparams.Length; ++i) {
        if (!tparams[i].HasSameConstraintsImplementation (base_tparams[i])) {
          container.Compiler.Report.SymbolRelatedToPreviousError (method);
          container.Compiler.Report.SymbolRelatedToPreviousError (baseMethod);

          // Using container location because the interface can be implemented
          // by base class
          var tp = (tparams [i].MemberDefinition as MemberCore) ?? container;
          container.Compiler.Report.Error (425, tp.Location,
            "The constraints for type parameter `{0}' of method `{1}' must match the constraints for type parameter `{2}' of interface method `{3}'. Consider using an explicit interface implementation instead",
            tparams[i].GetSignatureForError (), method.GetSignatureForError (),
            base_tparams[i].GetSignatureForError (), baseMethod.GetSignatureForError ());
 
          return false;
        }
      }

      return true;
    }

    //
    // Creates the type
    //
    public override bool Define ()
    {
      if (!base.Define ())
        return false;

      if (member_type.Kind == MemberKind.Void && parameters.IsEmpty && MemberName.Arity == 0 && MemberName.Name == Destructor.MetadataName) {
        Report.Warning (465, 1, Location,
          "Introducing `Finalize' method can interfere with destructor invocation. Did you intend to declare a destructor?");
      }

      if (Compiler.Settings.StdLib && ReturnType.IsSpecialRuntimeType) {
        Error1599 (Location, ReturnType, Report);
        return false;
      }

      if (CurrentTypeParameters == null) {
        if (base_method != null && !IsExplicitImpl) {
          if (parameters.Count == 1 && ParameterTypes[0].BuiltinType == BuiltinTypeSpec.Type.Object && MemberName.Name == "Equals")
            Parent.PartialContainer.Mark_HasEquals ();
          else if (parameters.IsEmpty && MemberName.Name == "GetHashCode")
            Parent.PartialContainer.Mark_HasGetHashCode ();
        }
          
      } else {
        DefineTypeParameters ();
      }

      if (block != null) {
        if (block.IsIterator) {
          //
          // Current method is turned into automatically generated
          // wrapper which creates an instance of iterator
          //
          Iterator.CreateIterator (this, Parent.PartialContainer, ModFlags);
          ModFlags |= Modifiers.DEBUGGER_HIDDEN;
        }

        if ((ModFlags & Modifiers.ASYNC) != 0) {
          if (ReturnType.Kind != MemberKind.Void &&
            ReturnType != Module.PredefinedTypes.Task.TypeSpec &&
            !ReturnType.IsGenericTask) {
            Report.Error (1983, Location, "The return type of an async method must be void, Task, or Task<T>");
          }

          block = (ToplevelBlock) block.ConvertToAsyncTask (this, Parent.PartialContainer, parameters, ReturnType, null, Location);
          ModFlags |= Modifiers.DEBUGGER_STEP_THROUGH;
        }

        if (Compiler.Settings.WriteMetadataOnly)
          block = null;
      }

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

      if (parameters.HasExtensionMethodType) {
        if (Parent.PartialContainer.IsStatic && !Parent.IsGenericOrParentIsGeneric) {
          if (!Parent.IsTopLevel)
            Report.Error (1109, Location, "`{0}': Extension methods cannot be defined in a nested class",
              GetSignatureForError ());

          PredefinedAttribute pa = Module.PredefinedAttributes.Extension;
          if (!pa.IsDefined) {
            Report.Error (1110, Location,
              "`{0}': Extension methods require `System.Runtime.CompilerServices.ExtensionAttribute' type to be available. Are you missing an assembly reference?",
              GetSignatureForError ());
          }

          ModFlags |= Modifiers.METHOD_EXTENSION;
          Parent.PartialContainer.ModFlags |= Modifiers.METHOD_EXTENSION;
          Spec.DeclaringType.SetExtensionMethodContainer ();
          Parent.Module.HasExtensionMethod = true;
        } else {
          Report.Error (1106, Location, "`{0}': Extension methods must be defined in a non-generic static class",
            GetSignatureForError ());
        }
      }

      //
      // This is used to track the Entry Point,
      //
      var settings = Compiler.Settings;
      if (settings.NeedsEntryPoint && MemberName.Name == "Main" && !IsPartialDefinition && (settings.MainClass == null || settings.MainClass == Parent.TypeBuilder.FullName)) {
        if (IsEntryPoint ()) {
          if (Parent.DeclaringAssembly.EntryPoint == null) {
            if (Parent.IsGenericOrParentIsGeneric || MemberName.IsGeneric) {
              Report.Warning (402, 4, Location, "`{0}': an entry point cannot be generic or in a generic type",
                GetSignatureForError ());
            } else if ((ModFlags & Modifiers.ASYNC) != 0) {
              Report.Error (4009, Location, "`{0}': an entry point cannot be async method",
                GetSignatureForError ());
            } else {
              SetIsUsed ();
              Parent.DeclaringAssembly.EntryPoint = this;
            }
          } else {
            Error_DuplicateEntryPoint (Parent.DeclaringAssembly.EntryPoint);
            Error_DuplicateEntryPoint (this);
          }
        } else {
          Report.Warning (28, 4, Location, "`{0}' has the wrong signature to be an entry point",
            GetSignatureForError ());
        }
      }

      return true;
    }

    public override void PrepareEmit ()
    {
      if (IsPartialDefinition) {
        //
        // Use partial method implementation builder for partial method declaration attributes
        //
        if (partialMethodImplementation != null) {
          MethodData = partialMethodImplementation.MethodData;
        }

        return;
      }

      base.PrepareEmit ();
    }

    //
    // Emits the code
    // 
    public override void Emit ()
    {
      try {
        if (IsPartialDefinition) {
          if (partialMethodImplementation != null && CurrentTypeParameters != null) {
            CurrentTypeParameters.CheckPartialConstraints (partialMethodImplementation);

            var otp = partialMethodImplementation.CurrentTypeParameters;
            for (int i = 0; i < CurrentTypeParameters.Count; ++i) {
              var tp = CurrentTypeParameters [i];
              tp.Define (otp[i]);
            }
          }

          return;
        }
        
        if ((ModFlags & Modifiers.PARTIAL) != 0 && (caching_flags & Flags.PartialDefinitionExists) == 0) {
          Report.Error (759, Location, "A partial method `{0}' implementation is missing a partial method declaration",
            GetSignatureForError ());
        }

        if (CurrentTypeParameters != null) {
          for (int i = 0; i < CurrentTypeParameters.Count; ++i) {
            var tp = CurrentTypeParameters [i];

            tp.CheckGenericConstraints (false);
            tp.Emit ();
          }
        }

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

        base.Emit ();
      } catch (Exception e) {
        throw new InternalErrorException (this, e);
      }
    }

    public override bool EnableOverloadChecks (MemberCore overload)
    {
      if (overload is Indexer)
        return false;

      return base.EnableOverloadChecks (overload);
    }

    public static void Error1599 (Location loc, TypeSpec t, Report Report)
    {
      Report.Error (1599, loc, "Method or delegate cannot return type `{0}'", t.GetSignatureForError ());
    }

    protected override bool ResolveMemberType ()
    {
      if (CurrentTypeParameters != null) {
        CreateTypeParameters ();
      }

      return base.ResolveMemberType ();
    }

    public void SetPartialDefinition (Method methodDefinition)
    {
      caching_flags |= Flags.PartialDefinitionExists;
      methodDefinition.partialMethodImplementation = this;

      // Ensure we are always using method declaration parameters
      for (int i = 0; i < methodDefinition.parameters.Count; ++i ) {
        var md_p = methodDefinition.parameters [i];
        var p = parameters [i];
        p.Name = md_p.Name;
        p.DefaultValue = md_p.DefaultValue;
        if (md_p.OptAttributes != null) {
          if (p.OptAttributes == null) {
            p.OptAttributes = md_p.OptAttributes;
          } else {
            p.OptAttributes.Attrs.AddRange (md_p.OptAttributes.Attrs);
          }
        }
      }

      if (methodDefinition.attributes != null) {
        if (attributes == null) {
          attributes = methodDefinition.attributes;
        } else {
          attributes.Attrs.AddRange (methodDefinition.attributes.Attrs);
        }
      }

      if (CurrentTypeParameters != null) {
        for (int i = 0; i < CurrentTypeParameters.Count; ++i) {
          var tp_other = methodDefinition.CurrentTypeParameters [i];
          if (tp_other.OptAttributes == null)
            continue;

          var tp = CurrentTypeParameters [i];
          if (tp.OptAttributes == null) {
            tp.OptAttributes = tp_other.OptAttributes;
          } else {
            tp.OptAttributes.Attrs.AddRange (tp.OptAttributes.Attrs);
          }
        }
      }
    }
  }

  public abstract class ConstructorInitializer : ExpressionStatement
  {
    Arguments argument_list;
    MethodSpec base_ctor;

    protected ConstructorInitializer (Arguments argument_list, Location loc)
    {
      this.argument_list = argument_list;
      this.loc = loc;
    }

    public Arguments Arguments {
      get {
        return argument_list;
      }
    }

    public override bool ContainsEmitWithAwait ()
    {
      throw new NotSupportedException ();
    }

    public override Expression CreateExpressionTree (ResolveContext ec)
    {
      throw new NotSupportedException ("ET");
    }

    protected override Expression DoResolve (ResolveContext ec)
    {
      eclass = ExprClass.Value;

      // FIXME: Hack
      var caller_builder = (Constructor) ec.MemberContext;

      //
      // Spec mandates that constructor initializer will not have `this' access
      //
      using (ec.Set (ResolveContext.Options.BaseInitializer)) {
        if (argument_list != null) {
          bool dynamic;
          argument_list.Resolve (ec, out dynamic);

          if (dynamic) {
            ec.Report.Error (1975, loc,
              "The constructor call cannot be dynamically dispatched within constructor initializer");

            return null;
          }
        }

        type = ec.CurrentType;
        if (this is ConstructorBaseInitializer) {
          if (ec.CurrentType.BaseType == null)
            return this;

          type = ec.CurrentType.BaseType;
          if (ec.CurrentType.IsStruct) {
            ec.Report.Error (522, loc,
              "`{0}': Struct constructors cannot call base constructors", caller_builder.GetSignatureForError ());
            return this;
          }
        } else {
          //
          // It is legal to have "this" initializers that take no arguments
          // in structs
          //
          // struct D { public D (int a) : this () {}
          //
          if (ec.CurrentType.IsStruct && argument_list == null)
            return this;
        }

        base_ctor = ConstructorLookup (ec, type, ref argument_list, loc);
      }
  
      if (base_ctor != null && base_ctor.MemberDefinition == caller_builder.Spec.MemberDefinition) {
        ec.Report.Error (516, loc, "Constructor `{0}' cannot call itself",
          caller_builder.GetSignatureForError ());
      }

      return this;
    }

    public override void Emit (EmitContext ec)
    {
      //
      // It can be null for struct initializers or System.Object
      //
      if (base_ctor == null) {
        if (type == ec.BuiltinTypes.Object)
          return;

        ec.Emit (OpCodes.Ldarg_0);
        ec.Emit (OpCodes.Initobj, type);
        return;
      }
      
      var call = new CallEmitter ();
      call.InstanceExpression = new CompilerGeneratedThis (type, loc); 
      call.EmitPredefined (ec, base_ctor, argument_list, false);
    }

    public override void EmitStatement (EmitContext ec)
    {
      Emit (ec);
    }

    public override void FlowAnalysis (FlowAnalysisContext fc)
    {
      if (argument_list != null)
        argument_list.FlowAnalysis (fc);
    }
  }

  public class ConstructorBaseInitializer : ConstructorInitializer {
    public ConstructorBaseInitializer (Arguments argument_list, Location l) :
      base (argument_list, l)
    {
    }
  }

  class GeneratedBaseInitializer: ConstructorBaseInitializer {
    public GeneratedBaseInitializer (Location loc, Arguments arguments)
      : base (arguments, loc)
    {
    }
  }

  public class ConstructorThisInitializer : ConstructorInitializer {
    public ConstructorThisInitializer (Arguments argument_list, Location l) :
      base (argument_list, l)
    {
    }
  }
  
  public class Constructor : MethodCore, IMethodData, IMethodDefinition
  {
    public ConstructorBuilder ConstructorBuilder;
    public ConstructorInitializer Initializer;
    SecurityType declarative_security;
    bool has_compliant_args;
    SourceMethodBuilder debug_builder;

    // <summary>
    //   Modifiers allowed for a constructor.
    // </summary>
    public const Modifiers AllowedModifiers =
      Modifiers.PUBLIC |
      Modifiers.PROTECTED |
      Modifiers.INTERNAL |
      Modifiers.STATIC |
      Modifiers.UNSAFE |
      Modifiers.EXTERN |    
      Modifiers.PRIVATE;

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

    public static readonly string ConstructorName = ".ctor";
    public static readonly string TypeConstructorName = ".cctor";

    public Constructor (TypeDefinition parent, string name, Modifiers mod, Attributes attrs, ParametersCompiled args, Location loc)
      : base (parent, null, mod, AllowedModifiers, new MemberName (name, loc), attrs, args)
    {
    }

    public bool HasCompliantArgs {
      get {
        return has_compliant_args;
      }
    }

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

    bool IMethodData.IsAccessor {
        get {
            return false;
        }
    }

    public bool IsPrimaryConstructor { get; set; }
    
    MethodBase IMethodDefinition.Metadata {
      get {
        return ConstructorBuilder;
      }
    }

    //
    // Returns true if this is a default constructor
    //
    public bool IsDefault ()
    {
      if ((ModFlags & Modifiers.STATIC) != 0)
        return parameters.IsEmpty;

      return parameters.IsEmpty &&
          (Initializer is ConstructorBaseInitializer) &&
          (Initializer.Arguments == null);
    }

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

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

      if (a.Type == pa.MethodImpl) {
        is_external_implementation = a.IsInternalCall ();
      }

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

    protected override bool CheckBase ()
    {
      if ((ModFlags & Modifiers.STATIC) != 0) {
        if (!parameters.IsEmpty) {
          Report.Error (132, Location, "`{0}': The static constructor must be parameterless",
            GetSignatureForError ());
          return false;
        }

        if ((caching_flags & Flags.MethodOverloadsExist) != 0)
          Parent.MemberCache.CheckExistingMembersOverloads (this, parameters);

        // the rest can be ignored
        return true;
      }

      // Check whether arguments were correct.
      if (!DefineParameters (parameters))
        return false;

      if ((caching_flags & Flags.MethodOverloadsExist) != 0)
        Parent.MemberCache.CheckExistingMembersOverloads (this, parameters);

      if (Parent.PartialContainer.Kind == MemberKind.Struct && parameters.IsEmpty) {
        Report.Error (568, Location, 
          "Structs cannot contain explicit parameterless constructors");
        return false;
      }

      CheckProtectedModifier ();
      
      return true;
    }
    
    //
    // Creates the ConstructorBuilder
    //
    public override bool Define ()
    {
      if (ConstructorBuilder != null)
        return true;

      if (!CheckAbstractAndExtern (block != null))
        return false;
      
      // Check if arguments were correct.
      if (!CheckBase ())
        return false;

      if (Parent.PrimaryConstructorParameters != null && !IsPrimaryConstructor && !IsStatic) {
        if (Parent.Kind == MemberKind.Struct && Initializer is ConstructorThisInitializer && Initializer.Arguments == null) {
          Report.Error (8043, Location, "`{0}': Structs with primary constructor cannot specify default constructor initializer",
            GetSignatureForError ());
        } else if (Initializer == null || Initializer is ConstructorBaseInitializer) {
          Report.Error (8037, Location, "`{0}': Instance constructor of type with primary constructor must specify `this' constructor initializer",
            GetSignatureForError ());
        }
      }

      var ca = ModifiersExtensions.MethodAttr (ModFlags) | MethodAttributes.RTSpecialName | MethodAttributes.SpecialName;

      ConstructorBuilder = Parent.TypeBuilder.DefineConstructor (
        ca, CallingConventions,
        parameters.GetMetaInfo ());

      spec = new MethodSpec (MemberKind.Constructor, Parent.Definition, this, Compiler.BuiltinTypes.Void, parameters, ModFlags);
      
      Parent.MemberCache.AddMember (spec);
      
      if (block != null) {
        // It's here only to report an error
        if (block.IsIterator) {
          member_type = Compiler.BuiltinTypes.Void;
          Iterator.CreateIterator (this, Parent.PartialContainer, ModFlags);
        }

        if (Compiler.Settings.WriteMetadataOnly)
          block = null;
      }

      return true;
    }

    //
    // Emits the code
    //
    public override void Emit ()
    {
      if (Parent.PartialContainer.IsComImport) {
        if (!IsDefault ()) {
          Report.Error (669, Location, "`{0}': A class with the ComImport attribute cannot have a user-defined constructor",
            Parent.GetSignatureForError ());
        }

        // Set as internal implementation and reset block data
        // to ensure no IL is generated
        ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.InternalCall);
        block = null;
      }

      if ((ModFlags & Modifiers.DEBUGGER_HIDDEN) != 0)
        Module.PredefinedAttributes.DebuggerHidden.EmitAttribute (ConstructorBuilder);

      if (OptAttributes != null)
        OptAttributes.Emit ();

      base.Emit ();
      parameters.ApplyAttributes (this, ConstructorBuilder);


      BlockContext bc = new BlockContext (this, block, Compiler.BuiltinTypes.Void);
      bc.Set (ResolveContext.Options.ConstructorScope);

      if (block != null) {
        if (!IsStatic && Initializer == null && Parent.PartialContainer.Kind == MemberKind.Struct) {
          //
          // If this is a non-static `struct' constructor and doesn't have any
          // initializer, it must initialize all of the struct's fields.
          //
          block.AddThisVariable (bc);
        }

        //
        // If we use a "this (...)" constructor initializer, then
        // do not emit field initializers, they are initialized in the other constructor
        //
        if (!(Initializer is ConstructorThisInitializer))
          Parent.PartialContainer.ResolveFieldInitializers (bc);

        if (!IsStatic) {
          if (Initializer == null && Parent.PartialContainer.Kind == MemberKind.Class) {
            Initializer = new GeneratedBaseInitializer (Location, null);
          }

          if (Initializer != null) {
            //
            // mdb format does not support reqions. Try to workaround this by emitting the
            // sequence point at initializer. Any breakpoint at constructor header should
            // be adjusted to this sequence point as it's the next one which follows.
            //
            block.AddScopeStatement (new StatementExpression (Initializer));
          }
        }

        if (block.Resolve (bc, this)) {
          debug_builder = Parent.CreateMethodSymbolEntry ();
          EmitContext ec = new EmitContext (this, ConstructorBuilder.GetILGenerator (), bc.ReturnType, debug_builder);
          ec.With (EmitContext.Options.ConstructorScope, true);

          block.Emit (ec);
        }
      }

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

      block = null;
    }

    protected override MemberSpec FindBaseMember (out MemberSpec bestCandidate, ref bool overrides)
    {
      // Is never override
      bestCandidate = null;
      return null;
    }

    public override string GetCallerMemberName ()
    {
      return IsStatic ? TypeConstructorName : ConstructorName;
    }

    public override string GetSignatureForDocumentation ()
    {
      return Parent.GetSignatureForDocumentation () + ".#ctor" + parameters.GetSignatureForDocumentation ();
    }

    public override string GetSignatureForError()
    {
      return base.GetSignatureForError () + parameters.GetSignatureForError ();
    }

    public override string[] ValidAttributeTargets {
      get {
        return attribute_targets;
      }
    }

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

      if (!parameters.IsEmpty && Parent.Definition.IsAttribute) {
        foreach (TypeSpec param in parameters.Types) {
          if (param.IsArray) {
            return true;
          }
        }
      }

      has_compliant_args = true;
      return true;
    }

    public override void WriteDebugSymbol (MonoSymbolFile file)
    {
      if (debug_builder == null)
        return;

      var token = ConstructorBuilder.GetToken ();
      int t = token.Token;
#if STATIC
      if (ModuleBuilder.IsPseudoToken (t))
        t = Module.Builder.ResolvePseudoToken (t);
#endif

      debug_builder.DefineMethod (file, t);
    }

    #region IMethodData Members

    public MemberName MethodName {
      get {
        return MemberName;
      }
    }

    public TypeSpec ReturnType {
      get {
        return MemberType;
      }
    }

    EmitContext IMethodData.CreateEmitContext (ILGenerator ig, SourceMethodBuilder sourceMethod)
    {
      throw new NotImplementedException ();
    }

    #endregion
  }

  /// <summary>
  /// Interface for MethodData class. Holds links to parent members to avoid member duplication.
  /// </summary>
  public interface IMethodData : IMemberContext
  {
    CallingConventions CallingConventions { get; }
    Location Location { get; }
    MemberName MethodName { get; }
    TypeSpec ReturnType { get; }
    ParametersCompiled ParameterInfo { get; }
    MethodSpec Spec { get; }
    bool IsAccessor { get; }

    Attributes OptAttributes { get; }
    ToplevelBlock Block { get; set; }

    EmitContext CreateEmitContext (ILGenerator ig, SourceMethodBuilder sourceMethod);
  }

  //
  // Encapsulates most of the Method's state
  //
  public class MethodData
  {
    public readonly IMethodData method;

    //
    // Are we implementing an interface ?
    //
    public MethodSpec implementing;

    //
    // Protected data.
    //
    protected InterfaceMemberBase member;
    protected Modifiers modifiers;
    protected MethodAttributes flags;
    protected TypeSpec declaring_type;
    protected MethodSpec parent_method;
    SourceMethodBuilder debug_builder;
    string full_name;

    MethodBuilder builder;
    public MethodBuilder MethodBuilder {
      get {
        return builder;
      }
    }

    public TypeSpec DeclaringType {
      get {
        return declaring_type;
      }
    }

    public string MetadataName {
      get {
        return full_name;
      }
    }

    public MethodData (InterfaceMemberBase member,
           Modifiers modifiers, MethodAttributes flags, IMethodData method)
    {
      this.member = member;
      this.modifiers = modifiers;
      this.flags = flags;

      this.method = method;
    }

    public MethodData (InterfaceMemberBase member,
           Modifiers modifiers, MethodAttributes flags, 
           IMethodData method,
           MethodSpec parent_method)
      : this (member, modifiers, flags, method)
    {
      this.parent_method = parent_method;
    }

    public bool Define (TypeDefinition container, string method_full_name)
    {
      PendingImplementation pending = container.PendingImplementations;
      MethodSpec ambig_iface_method;
      bool optional = false;

      if (pending != null) {
        implementing = pending.IsInterfaceMethod (method.MethodName, member.InterfaceType, this, out ambig_iface_method, ref optional);

        if (member.InterfaceType != null) {
          if (implementing == null) {
            if (member is PropertyBase) {
              container.Compiler.Report.Error (550, method.Location,
                "`{0}' is an accessor not found in interface member `{1}{2}'",
                    method.GetSignatureForError (), member.InterfaceType.GetSignatureForError (),
                    member.GetSignatureForError ().Substring (member.GetSignatureForError ().LastIndexOf ('.')));

            } else {
              container.Compiler.Report.Error (539, method.Location,
                    "`{0}.{1}' in explicit interface declaration is not a member of interface",
                    member.InterfaceType.GetSignatureForError (), member.ShortName);
            }
            return false;
          }
          if (implementing.IsAccessor && !method.IsAccessor) {
            container.Compiler.Report.SymbolRelatedToPreviousError (implementing);
            container.Compiler.Report.Error (683, method.Location,
              "`{0}' explicit method implementation cannot implement `{1}' because it is an accessor",
              member.GetSignatureForError (), implementing.GetSignatureForError ());
            return false;
          }
        } else {
          if (implementing != null && !optional) {
            if (!method.IsAccessor) {
              if (implementing.IsAccessor) {
                container.Compiler.Report.SymbolRelatedToPreviousError (implementing);
                container.Compiler.Report.Error (470, method.Location,
                  "Method `{0}' cannot implement interface accessor `{1}'",
                  method.GetSignatureForError (), TypeManager.CSharpSignature (implementing));
              }
            } else if (implementing.DeclaringType.IsInterface) {
              if (!implementing.IsAccessor) {
                container.Compiler.Report.SymbolRelatedToPreviousError (implementing);
                container.Compiler.Report.Error (686, method.Location,
                  "Accessor `{0}' cannot implement interface member `{1}' for type `{2}'. Use an explicit interface implementation",
                  method.GetSignatureForError (), TypeManager.CSharpSignature (implementing), container.GetSignatureForError ());
              } else {
                PropertyBase.PropertyMethod pm = method as PropertyBase.PropertyMethod;
                if (pm != null && pm.HasCustomAccessModifier && (pm.ModFlags & Modifiers.PUBLIC) == 0) {
                  container.Compiler.Report.SymbolRelatedToPreviousError (implementing);
                  container.Compiler.Report.Error (277, method.Location,
                    "Accessor `{0}' must be declared public to implement interface member `{1}'",
                    method.GetSignatureForError (), implementing.GetSignatureForError ());
                }
              }
            }
          }
        }
      } else {
        ambig_iface_method = null;
      }

      //
      // For implicit implementations, make sure we are public, for
      // explicit implementations, make sure we are private.
      //
      if (implementing != null){
        if (member.IsExplicitImpl) {
          if (method.ParameterInfo.HasParams && !implementing.Parameters.HasParams) {
            container.Compiler.Report.SymbolRelatedToPreviousError (implementing);
            container.Compiler.Report.Error (466, method.Location,
              "`{0}': the explicit interface implementation cannot introduce the params modifier",
              method.GetSignatureForError ());
          }

          if (ambig_iface_method != null) {
            container.Compiler.Report.SymbolRelatedToPreviousError (ambig_iface_method);
            container.Compiler.Report.SymbolRelatedToPreviousError (implementing);
            container.Compiler.Report.Warning (473, 2, method.Location,
              "Explicit interface implementation `{0}' matches more than one interface member. Consider using a non-explicit implementation instead",
              method.GetSignatureForError ());
          }
        } else {
          //
          // Setting implementin to null inside this block will trigger a more
          // verbose error reporting for missing interface implementations
          //
          if (implementing.DeclaringType.IsInterface) {
            //
            // If this is an interface method implementation,
            // check for public accessibility
            //
            if ((flags & MethodAttributes.MemberAccessMask) != MethodAttributes.Public) {
              implementing = null;
            } else if (optional && (container.Interfaces == null || !container.Definition.Interfaces.Contains (implementing.DeclaringType))) {
              //
              // We are not implementing interface when base class already implemented it
              //
              implementing = null;
            }
          } else if ((flags & MethodAttributes.MemberAccessMask) == MethodAttributes.Private) {
            // We may never be private.
            implementing = null;

          } else if ((modifiers & Modifiers.OVERRIDE) == 0) {
            //
            // We may be protected if we're overriding something.
            //
            implementing = null;
          }
        }
          
        //
        // Static is not allowed
        //
        if ((modifiers & Modifiers.STATIC) != 0){
          implementing = null;
        }
      }
      
      //
      // If implementing is still valid, set flags
      //
      if (implementing != null){
        //
        // When implementing interface methods, set NewSlot
        // unless, we are overwriting a method.
        //
        if ((modifiers & Modifiers.OVERRIDE) == 0 && implementing.DeclaringType.IsInterface) {
          flags |= MethodAttributes.NewSlot;
        }

        flags |= MethodAttributes.Virtual | MethodAttributes.HideBySig;

        // Set Final unless we're virtual, abstract or already overriding a method.
        if ((modifiers & (Modifiers.VIRTUAL | Modifiers.ABSTRACT | Modifiers.OVERRIDE)) == 0)
          flags |= MethodAttributes.Final;

        //
        // clear the pending implementation flag (requires explicit methods to be defined first)
        //
        pending.ImplementMethod (method.MethodName,
          member.InterfaceType, this, member.IsExplicitImpl, out ambig_iface_method, ref optional);

        //
        // Update indexer accessor name to match implementing abstract accessor
        //
        if (!implementing.DeclaringType.IsInterface && !member.IsExplicitImpl && implementing.IsAccessor)
          method_full_name = implementing.MemberDefinition.Name;
      }

      full_name = method_full_name;
      declaring_type = container.Definition;

      return true;
    }

    void DefineOverride (TypeDefinition container)
    {
      if (implementing == null)
        return;

      if (!member.IsExplicitImpl)
        return;

      container.TypeBuilder.DefineMethodOverride (builder, (MethodInfo) implementing.GetMetaInfo ());
    }

    //
    // Creates partial MethodBuilder for the method when has generic parameters used
    // as arguments or return type
    //
    public MethodBuilder DefineMethodBuilder (TypeDefinition container)
    {
      if (builder != null)
        throw new InternalErrorException ();

      builder = container.TypeBuilder.DefineMethod (full_name, flags, method.CallingConventions);
      return builder;
    }

    //
    // Creates full MethodBuilder for the method 
    //
    public MethodBuilder DefineMethodBuilder (TypeDefinition container, ParametersCompiled param)
    {
      DefineMethodBuilder (container);
      builder.SetReturnType (method.ReturnType.GetMetaInfo ());
      builder.SetParameters (param.GetMetaInfo ());
      return builder;
    }

    //
    // Emits the code
    // 
    public void Emit (TypeDefinition parent)
    {
      DefineOverride (parent);

      method.ParameterInfo.ApplyAttributes (method, MethodBuilder);

      ToplevelBlock block = method.Block;
      if (block != null) {
        BlockContext bc = new BlockContext (method, block, method.ReturnType);
        if (block.Resolve (bc, method)) {
          debug_builder = member.Parent.CreateMethodSymbolEntry ();
          EmitContext ec = method.CreateEmitContext (MethodBuilder.GetILGenerator (), debug_builder);

          block.Emit (ec);
        }
      }
    }

    public void WriteDebugSymbol (MonoSymbolFile file)
    {
      if (debug_builder == null)
        return;

      var token = builder.GetToken ();
      int t = token.Token;
#if STATIC
      if (ModuleBuilder.IsPseudoToken (t))
        t = member.Module.Builder.ResolvePseudoToken (t);
#endif

      debug_builder.DefineMethod (file, t);
    }
  }

  public class Destructor : MethodOrOperator
  {
    const Modifiers AllowedModifiers =
      Modifiers.UNSAFE |
      Modifiers.EXTERN;

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

    public static readonly string MetadataName = "Finalize";

    public string Identifier {
      get;
      set;
    }
    
    public Destructor (TypeDefinition parent, Modifiers mod, ParametersCompiled parameters, Attributes attrs, Location l)
      : base (parent, null, mod, AllowedModifiers, new MemberName (MetadataName, l), attrs, parameters)
    {
      ModFlags &= ~Modifiers.PRIVATE;
      ModFlags |= Modifiers.PROTECTED | Modifiers.OVERRIDE;
    }

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

    public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
    {
      if (a.Type == pa.Conditional) {
        Error_ConditionalAttributeIsNotValid ();
        return;
      }

      base.ApplyAttributeBuilder (a, ctor, cdata, pa);
    }
    
    protected override bool CheckBase ()
    {
      if ((caching_flags & Flags.MethodOverloadsExist) != 0)
        CheckForDuplications ();

      // Don't check base, destructors have special syntax
      return true;
    }

    public override bool Define ()
    {
      base.Define ();

      if (Compiler.Settings.WriteMetadataOnly)
        block = null;

      return true;
    }

    public override void Emit()
    {
      var base_type = Parent.PartialContainer.BaseType;
      if (base_type != null && Block != null) {
        var base_dtor = MemberCache.FindMember (base_type,
          new MemberFilter (MetadataName, 0, MemberKind.Destructor, null, null), BindingRestriction.InstanceOnly) as MethodSpec;

        if (base_dtor == null)
          throw new NotImplementedException ();

        MethodGroupExpr method_expr = MethodGroupExpr.CreatePredefined (base_dtor, base_type, Location);
        method_expr.InstanceExpression = new BaseThis (base_type, Location);

        var try_block = new ExplicitBlock (block, block.StartLocation, block.EndLocation) {
          IsCompilerGenerated = true
        };
        var finaly_block = new ExplicitBlock (block, Location, Location) {
          IsCompilerGenerated = true
        };

        //
        // 0-size arguments to avoid CS0250 error
        // TODO: Should use AddScopeStatement or something else which emits correct
        // debugger scope
        //
        finaly_block.AddStatement (new StatementExpression (new Invocation (method_expr, new Arguments (0)), Location.Null));

        var tf = new TryFinally (try_block, finaly_block, Location);
        block.WrapIntoDestructor (tf, try_block);
      }

      base.Emit ();
    }

    public override string GetSignatureForError ()
    {
      return Parent.GetSignatureForError () + ".~" + Parent.MemberName.Name + "()";
    }

    protected override bool ResolveMemberType ()
    {
      member_type = Compiler.BuiltinTypes.Void;
      return true;
    }

    public override string[] ValidAttributeTargets {
      get {
        return attribute_targets;
      }
    }
  }

  // Ooouh Martin, templates are missing here.
  // When it will be possible move here a lot of child code and template method type.
  public abstract class AbstractPropertyEventMethod : MemberCore, IMethodData, IMethodDefinition {
    protected MethodData method_data;
    protected ToplevelBlock block;
    protected SecurityType declarative_security;

    protected readonly string prefix;

    ReturnParameter return_attributes;

    protected AbstractPropertyEventMethod (InterfaceMemberBase member, string prefix, Attributes attrs, Location loc)
      : base (member.Parent, SetupName (prefix, member, loc), attrs)
    {
      this.prefix = prefix;
    }

    static MemberName SetupName (string prefix, InterfaceMemberBase member, Location loc)
    {
      return new MemberName (member.MemberName.Left, prefix + member.ShortName, member.MemberName.ExplicitInterface, loc);
    }

    public void UpdateName (InterfaceMemberBase member)
    {
      SetMemberName (SetupName (prefix, member, Location));
    }

    #region IMethodData Members

    public ToplevelBlock Block {
      get {
        return block;
      }

      set {
        block = value;
      }
    }

    public CallingConventions CallingConventions {
      get {
        return CallingConventions.Standard;
      }
    }

    public EmitContext CreateEmitContext (ILGenerator ig, SourceMethodBuilder sourceMethod)
    {
      return new EmitContext (this, ig, ReturnType, sourceMethod);
    }

    public bool IsAccessor {
      get {
        return true;
      }
    }

    public MemberName MethodName {
      get {
        return MemberName;
      }
    }

    public TypeSpec[] ParameterTypes { 
      get {
        return ParameterInfo.Types;
      }
    }

    MethodBase IMethodDefinition.Metadata {
      get {
        return method_data.MethodBuilder;
      }
    }

    public abstract ParametersCompiled ParameterInfo { get ; }
    public abstract TypeSpec ReturnType { get; }

    #endregion

    public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
    {
      if (a.Type == pa.CLSCompliant || a.Type == pa.Obsolete || a.Type == pa.Conditional) {
        Report.Error (1667, a.Location,
          "Attribute `{0}' is not valid on property or event accessors. It is valid on `{1}' declarations only",
          a.Type.GetSignatureForError (), a.GetValidTargets ());
        return;
      }

      if (a.IsValidSecurityAttribute ()) {
        a.ExtractSecurityPermissionSet (ctor, ref declarative_security);
        return;
      }

      if (a.Target == AttributeTargets.Method) {
        method_data.MethodBuilder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), cdata);
        return;
      }

      if (a.Target == AttributeTargets.ReturnValue) {
        if (return_attributes == null)
          return_attributes = new ReturnParameter (this, method_data.MethodBuilder, Location);

        return_attributes.ApplyAttributeBuilder (a, ctor, cdata, pa);
        return;
      }

      ApplyToExtraTarget (a, ctor, cdata, pa);
    }

    protected virtual void ApplyToExtraTarget (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
    {
      throw new NotSupportedException ("You forgot to define special attribute target handling");
    }

    // It is not supported for the accessors
    public sealed override bool Define()
    {
      throw new NotSupportedException ();
    }

    public virtual void Emit (TypeDefinition parent)
    {
      method_data.Emit (parent);

      if ((ModFlags & Modifiers.COMPILER_GENERATED) != 0 && !Parent.IsCompilerGenerated)
        Module.PredefinedAttributes.CompilerGenerated.EmitAttribute (method_data.MethodBuilder);
      if (((ModFlags & Modifiers.DEBUGGER_HIDDEN) != 0))
        Module.PredefinedAttributes.DebuggerHidden.EmitAttribute (method_data.MethodBuilder);

      if (ReturnType.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
        return_attributes = new ReturnParameter (this, method_data.MethodBuilder, Location);
        Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder);
      } else if (ReturnType.HasDynamicElement) {
        return_attributes = new ReturnParameter (this, method_data.MethodBuilder, Location);
        Module.PredefinedAttributes.Dynamic.EmitAttribute (return_attributes.Builder, ReturnType, Location);
      }

      if (OptAttributes != null)
        OptAttributes.Emit ();

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

      block = null;
    }

    public override bool EnableOverloadChecks (MemberCore overload)
    {
      if (overload is MethodCore) {
        caching_flags |= Flags.MethodOverloadsExist;
        return true;
      }

      // This can only happen with indexers and it will
      // be catched as indexer difference
      if (overload is AbstractPropertyEventMethod)
        return true;

      return false;
    }

    public override string GetCallerMemberName ()
    {
      return base.GetCallerMemberName ().Substring (prefix.Length);
    }

    public override string GetSignatureForDocumentation ()
    {
      // should not be called
      throw new NotSupportedException ();
    }

    public override bool IsClsComplianceRequired()
    {
      return false;
    }

    public void PrepareEmit ()
    {
      method_data.DefineMethodBuilder (Parent.PartialContainer, ParameterInfo);
    }

    public override void WriteDebugSymbol (MonoSymbolFile file)
    {
      if (method_data != null)
        method_data.WriteDebugSymbol (file);
    }

    public MethodSpec Spec { get; protected set; }

    //
    //   Represents header string for documentation comment.
    //
    public override string DocCommentHeader {
      get { throw new InvalidOperationException ("Unexpected attempt to get doc comment from " + this.GetType () + "."); }
    }
  }

  public class Operator : MethodOrOperator {

    const Modifiers AllowedModifiers =
      Modifiers.PUBLIC |
      Modifiers.UNSAFE |
      Modifiers.EXTERN |
      Modifiers.STATIC;

    public enum OpType : byte {

      // Unary operators
      LogicalNot,
      OnesComplement,
      Increment,
      Decrement,
      True,
      False,

      // Unary and Binary operators
      Addition,
      Subtraction,

      UnaryPlus,
      UnaryNegation,
      
      // Binary operators
      Multiply,
      Division,
      Modulus,
      BitwiseAnd,
      BitwiseOr,
      ExclusiveOr,
      LeftShift,
      RightShift,
      Equality,
      Inequality,
      GreaterThan,
      LessThan,
      GreaterThanOrEqual,
      LessThanOrEqual,

      // Implicit and Explicit
      Implicit,
      Explicit,

      // Just because of enum
      TOP
    };

    public readonly OpType OperatorType;

    static readonly string [] [] names;

    static Operator ()
    {
      names = new string[(int)OpType.TOP][];
      names [(int) OpType.LogicalNot] = new string [] { "!", "op_LogicalNot" };
      names [(int) OpType.OnesComplement] = new string [] { "~", "op_OnesComplement" };
      names [(int) OpType.Increment] = new string [] { "++", "op_Increment" };
      names [(int) OpType.Decrement] = new string [] { "--", "op_Decrement" };
      names [(int) OpType.True] = new string [] { "true", "op_True" };
      names [(int) OpType.False] = new string [] { "false", "op_False" };
      names [(int) OpType.Addition] = new string [] { "+", "op_Addition" };
      names [(int) OpType.Subtraction] = new string [] { "-", "op_Subtraction" };
      names [(int) OpType.UnaryPlus] = new string [] { "+", "op_UnaryPlus" };
      names [(int) OpType.UnaryNegation] = new string [] { "-", "op_UnaryNegation" };
      names [(int) OpType.Multiply] = new string [] { "*", "op_Multiply" };
      names [(int) OpType.Division] = new string [] { "/", "op_Division" };
      names [(int) OpType.Modulus] = new string [] { "%", "op_Modulus" };
      names [(int) OpType.BitwiseAnd] = new string [] { "&", "op_BitwiseAnd" };
      names [(int) OpType.BitwiseOr] = new string [] { "|", "op_BitwiseOr" };
      names [(int) OpType.ExclusiveOr] = new string [] { "^", "op_ExclusiveOr" };
      names [(int) OpType.LeftShift] = new string [] { "<<", "op_LeftShift" };
      names [(int) OpType.RightShift] = new string [] { ">>", "op_RightShift" };
      names [(int) OpType.Equality] = new string [] { "==", "op_Equality" };
      names [(int) OpType.Inequality] = new string [] { "!=", "op_Inequality" };
      names [(int) OpType.GreaterThan] = new string [] { ">", "op_GreaterThan" };
      names [(int) OpType.LessThan] = new string [] { "<", "op_LessThan" };
      names [(int) OpType.GreaterThanOrEqual] = new string [] { ">=", "op_GreaterThanOrEqual" };
      names [(int) OpType.LessThanOrEqual] = new string [] { "<=", "op_LessThanOrEqual" };
      names [(int) OpType.Implicit] = new string [] { "implicit", "op_Implicit" };
      names [(int) OpType.Explicit] = new string [] { "explicit", "op_Explicit" };
    }

    public Operator (TypeDefinition parent, OpType type, FullNamedExpression ret_type, Modifiers mod_flags, ParametersCompiled parameters,
         ToplevelBlock block, Attributes attrs, Location loc)
      : base (parent, ret_type, mod_flags, AllowedModifiers, new MemberName (GetMetadataName (type), loc), attrs, parameters)
    {
      OperatorType = type;
      Block = block;
    }

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

    public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
    {
      if (a.Type == pa.Conditional) {
        Error_ConditionalAttributeIsNotValid ();
        return;
      }

      base.ApplyAttributeBuilder (a, ctor, cdata, pa);
    }
    
    public override bool Define ()
    {
      const Modifiers RequiredModifiers = Modifiers.PUBLIC | Modifiers.STATIC;
      if ((ModFlags & RequiredModifiers) != RequiredModifiers){
        Report.Error (558, Location, "User-defined operator `{0}' must be declared static and public", GetSignatureForError ());
      }

      if (!base.Define ())
        return false;

      if (block != null) {
        if (block.IsIterator) {
          //
          // Current method is turned into automatically generated
          // wrapper which creates an instance of iterator
          //
          Iterator.CreateIterator (this, Parent.PartialContainer, ModFlags);
          ModFlags |= Modifiers.DEBUGGER_HIDDEN;
        }

        if (Compiler.Settings.WriteMetadataOnly)
          block = null;
      }

      // imlicit and explicit operator of same types are not allowed
      if (OperatorType == OpType.Explicit)
        Parent.MemberCache.CheckExistingMembersOverloads (this, GetMetadataName (OpType.Implicit), parameters);
      else if (OperatorType == OpType.Implicit)
        Parent.MemberCache.CheckExistingMembersOverloads (this, GetMetadataName (OpType.Explicit), parameters);

      TypeSpec declaring_type = Parent.CurrentType;
      TypeSpec return_type = MemberType;
      TypeSpec first_arg_type = ParameterTypes [0];
      
      TypeSpec first_arg_type_unwrap = first_arg_type;
      if (first_arg_type.IsNullableType)
        first_arg_type_unwrap = Nullable.NullableInfo.GetUnderlyingType (first_arg_type);
      
      TypeSpec return_type_unwrap = return_type;
      if (return_type.IsNullableType)
        return_type_unwrap = Nullable.NullableInfo.GetUnderlyingType (return_type);

      //
      // Rules for conversion operators
      //
      if (OperatorType == OpType.Implicit || OperatorType == OpType.Explicit) {
        if (first_arg_type_unwrap == return_type_unwrap && first_arg_type_unwrap == declaring_type) {
          Report.Error (555, Location,
            "User-defined operator cannot take an object of the enclosing type and convert to an object of the enclosing type");
          return false;
        }

        TypeSpec conv_type;
        if (declaring_type == return_type || declaring_type == return_type_unwrap) {
          conv_type = first_arg_type;
        } else if (declaring_type == first_arg_type || declaring_type == first_arg_type_unwrap) {
          conv_type = return_type;
        } else {
          Report.Error (556, Location,
            "User-defined conversion must convert to or from the enclosing type");
          return false;
        }

        if (conv_type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
          Report.Error (1964, Location,
            "User-defined conversion `{0}' cannot convert to or from the dynamic type",
            GetSignatureForError ());

          return false;
        }

        if (conv_type.IsInterface) {
          Report.Error (552, Location, "User-defined conversion `{0}' cannot convert to or from an interface type",
            GetSignatureForError ());
          return false;
        }

        if (conv_type.IsClass) {
          if (TypeSpec.IsBaseClass (declaring_type, conv_type, true)) {
            Report.Error (553, Location, "User-defined conversion `{0}' cannot convert to or from a base class",
              GetSignatureForError ());
            return false;
          }

          if (TypeSpec.IsBaseClass (conv_type, declaring_type, false)) {
            Report.Error (554, Location, "User-defined conversion `{0}' cannot convert to or from a derived class",
              GetSignatureForError ());
            return false;
          }
        }
      } else if (OperatorType == OpType.LeftShift || OperatorType == OpType.RightShift) {
        if (first_arg_type != declaring_type || parameters.Types[1].BuiltinType != BuiltinTypeSpec.Type.Int) {
          Report.Error (564, Location, "Overloaded shift operator must have the type of the first operand be the containing type, and the type of the second operand must be int");
          return false;
        }
      } else if (parameters.Count == 1) {
        // Checks for Unary operators

        if (OperatorType == OpType.Increment || OperatorType == OpType.Decrement) {
          if (return_type != declaring_type && !TypeSpec.IsBaseClass (return_type, declaring_type, false)) {
            Report.Error (448, Location,
              "The return type for ++ or -- operator must be the containing type or derived from the containing type");
            return false;
          }
          if (first_arg_type != declaring_type) {
            Report.Error (
              559, Location, "The parameter type for ++ or -- operator must be the containing type");
            return false;
          }
        }

        if (first_arg_type_unwrap != declaring_type) {
          Report.Error (562, Location,
            "The parameter type of a unary operator must be the containing type");
          return false;
        }

        if (OperatorType == OpType.True || OperatorType == OpType.False) {
          if (return_type.BuiltinType != BuiltinTypeSpec.Type.Bool) {
            Report.Error (
              215, Location,
              "The return type of operator True or False " +
              "must be bool");
            return false;
          }
        }

      } else if (first_arg_type_unwrap != declaring_type) {
        // Checks for Binary operators

        var second_arg_type = ParameterTypes[1];
        if (second_arg_type.IsNullableType)
          second_arg_type = Nullable.NullableInfo.GetUnderlyingType (second_arg_type);

        if (second_arg_type != declaring_type) {
          Report.Error (563, Location,
            "One of the parameters of a binary operator must be the containing type");
          return false;
        }
      }

      return true;
    }

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

      flags |= MethodAttributes.SpecialName | MethodAttributes.HideBySig;
      return true;
    }

    protected override MemberSpec FindBaseMember (out MemberSpec bestCandidate, ref bool overrides)
    {
      // Operator cannot be override
      bestCandidate = null;
      return null;
    }

    public static string GetName (OpType ot)
    {
      return names [(int) ot] [0];
    }

    public static string GetName (string metadata_name)
    {
      for (int i = 0; i < names.Length; ++i) {
        if (names [i] [1] == metadata_name)
          return names [i] [0];
      }
      return null;
    }

    public static string GetMetadataName (OpType ot)
    {
      return names [(int) ot] [1];
    }

    public static string GetMetadataName (string name)
    {
      for (int i = 0; i < names.Length; ++i) {
        if (names [i] [0] == name)
          return names [i] [1];
      }
      return null;
    }

    public static OpType? GetType (string metadata_name)
    {
      for (int i = 0; i < names.Length; ++i) {
        if (names[i][1] == metadata_name)
          return (OpType) i;
      }

      return null;
    }

    public OpType GetMatchingOperator ()
    {
      switch (OperatorType) {
      case OpType.Equality:
        return OpType.Inequality;
      case OpType.Inequality:
        return OpType.Equality;
      case OpType.True:
        return OpType.False;
      case OpType.False:
        return OpType.True;
      case OpType.GreaterThan:
        return OpType.LessThan;
      case OpType.LessThan:
        return OpType.GreaterThan;
      case OpType.GreaterThanOrEqual:
        return OpType.LessThanOrEqual;
      case OpType.LessThanOrEqual:
        return OpType.GreaterThanOrEqual;
      default:
        return OpType.TOP;
      }
    }

    public override string GetSignatureForDocumentation ()
    {
      string s = base.GetSignatureForDocumentation ();
      if (OperatorType == OpType.Implicit || OperatorType == OpType.Explicit) {
        s = s + "~" + ReturnType.GetSignatureForDocumentation ();
      }

      return s;
    }

    public override string GetSignatureForError ()
    {
      StringBuilder sb = new StringBuilder ();
      if (OperatorType == OpType.Implicit || OperatorType == OpType.Explicit) {
        sb.AppendFormat ("{0}.{1} operator {2}",
          Parent.GetSignatureForError (), GetName (OperatorType),
          member_type == null ? type_expr.GetSignatureForError () : member_type.GetSignatureForError ());
      }
      else {
        sb.AppendFormat ("{0}.operator {1}", Parent.GetSignatureForError (), GetName (OperatorType));
      }

      sb.Append (parameters.GetSignatureForError ());
      return sb.ToString ();
    }
  }
}