mcs/mcs/parameter.cs

   1 //
   2 // parameter.cs: Parameter definition.
   3 //
   4 // Author: Miguel de Icaza (miguel@gnu.org)
   5 //         Marek Safar (marek.safar@seznam.cz)
   6 //
   7 // Dual licensed under the terms of the MIT X11 or GNU GPL
   8 //
   9 // Copyright 2001-2003 Ximian, Inc (http://www.ximian.com)
  10 // Copyright 2003-2008 Novell, Inc.
  11 // Copyright 2011 Xamarin Inc
  12 //
  13 //
  14 using System;
  15 using System.Text;
  16
  17 #if STATIC
  18 using MetaType = IKVM.Reflection.Type;
  19 using IKVM.Reflection;
  20 using IKVM.Reflection.Emit;
  21 #else
  22 using MetaType = System.Type;
  23 using System.Reflection;
  24 using System.Reflection.Emit;
  25 #endif
  26
  27 namespace Mono.CSharp {
  28
  29         /// <summary>
  30         ///   Abstract Base class for parameters of a method.
  31         /// </summary>
  32         public abstract class ParameterBase : Attributable
  33         {
  34                 protected ParameterBuilder builder;
  35
  36                 public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
  37                 {
  38 #if false
  39                         if (a.Type == pa.MarshalAs) {
  40                                 UnmanagedMarshal marshal = a.GetMarshal (this);
  41                                 if (marshal != null) {
  42                                         builder.SetMarshal (marshal);
  43                                 }
  44                                 return;
  45                         }
  46 #endif
  47                         if (a.HasSecurityAttribute) {
  48                                 a.Error_InvalidSecurityParent ();
  49                                 return;
  50                         }
  51
  52                         if (a.Type == pa.Dynamic) {
  53                                 a.Error_MisusedDynamicAttribute ();
  54                                 return;
  55                         }
  56
  57                         builder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), cdata);
  58                 }
  59
  60                 public ParameterBuilder Builder {
  61                         get {
  62                                 return builder;
  63                         }
  64                 }
  65
  66                 public override bool IsClsComplianceRequired()
  67                 {
  68                         return false;
  69                 }
  70         }
  71
  72         /// <summary>
  73         /// Class for applying custom attributes on the return type
  74         /// </summary>
  75         public class ReturnParameter : ParameterBase
  76         {
  77                 MemberCore method;
  78
  79                 // TODO: merge method and mb
  80                 public ReturnParameter (MemberCore method, MethodBuilder mb, Location location)
  81                 {
  82                         this.method = method;
  83                         try {
  84                                 builder = mb.DefineParameter (0, ParameterAttributes.None, "");
  85                         }
  86                         catch (ArgumentOutOfRangeException) {
  87                                 method.Compiler.Report.RuntimeMissingSupport (location, "custom attributes on the return type");
  88                         }
  89                 }
  90
  91                 public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
  92                 {
  93                         if (a.Type == pa.CLSCompliant) {
  94                                 method.Compiler.Report.Warning (3023, 1, a.Location,
  95                                         "CLSCompliant attribute has no meaning when applied to return types. Try putting it on the method instead");
  96                         }
  97
  98                         // This occurs after Warning -28
  99                         if (builder == null)
 100                                 return;
 101
 102                         base.ApplyAttributeBuilder (a, ctor, cdata, pa);
 103                 }
 104
 105                 public override AttributeTargets AttributeTargets {
 106                         get {
 107                                 return AttributeTargets.ReturnValue;
 108                         }
 109                 }
 110
 111                 /// <summary>
 112                 /// Is never called
 113                 /// </summary>
 114                 public override string[] ValidAttributeTargets {
 115                         get {
 116                                 return null;
 117                         }
 118                 }
 119         }
 120
 121         public class ImplicitLambdaParameter : Parameter
 122         {
 123                 public ImplicitLambdaParameter (string name, Location loc)
 124                         : base (null, name, Modifier.NONE, null, loc)
 125                 {
 126                 }
 127
 128                 public override TypeSpec Resolve (IMemberContext ec, int index)
 129                 {
 130                         if (parameter_type == null)
 131                                 throw new InternalErrorException ("A type of implicit lambda parameter `{0}' is not set",
 132                                         Name);
 133
 134                         base.idx = index;
 135                         return parameter_type;
 136                 }
 137
 138                 public void SetParameterType (TypeSpec type)
 139                 {
 140                         parameter_type = type;
 141                 }
 142         }
 143
 144         public class ParamsParameter : Parameter {
 145                 public ParamsParameter (FullNamedExpression type, string name, Attributes attrs, Location loc):
 146                         base (type, name, Parameter.Modifier.PARAMS, attrs, loc)
 147                 {
 148                 }
 149
 150                 public override TypeSpec Resolve (IMemberContext ec, int index)
 151                 {
 152                         if (base.Resolve (ec, index) == null)
 153                                 return null;
 154
 155                         var ac = parameter_type as ArrayContainer;
 156                         if (ac == null || ac.Rank != 1) {
 157                                 ec.Module.Compiler.Report.Error (225, Location, "The params parameter must be a single dimensional array");
 158                                 return null;
 159                         }
 160
 161                         return parameter_type;
 162                 }
 163
 164                 public override void ApplyAttributes (MethodBuilder mb, ConstructorBuilder cb, int index, PredefinedAttributes pa)
 165                 {
 166                         base.ApplyAttributes (mb, cb, index, pa);
 167                         pa.ParamArray.EmitAttribute (builder);
 168                 }
 169         }
 170
 171         public class ArglistParameter : Parameter {
 172                 // Doesn't have proper type because it's never chosen for better conversion
 173                 public ArglistParameter (Location loc) :
 174                         base (null, String.Empty, Parameter.Modifier.NONE, null, loc)
 175                 {
 176                         parameter_type = InternalType.Arglist;
 177                 }
 178
 179                 public override void  ApplyAttributes (MethodBuilder mb, ConstructorBuilder cb, int index, PredefinedAttributes pa)
 180                 {
 181                         // Nothing to do
 182                 }
 183
 184                 public override bool CheckAccessibility (InterfaceMemberBase member)
 185                 {
 186                         return true;
 187                 }
 188
 189                 public override TypeSpec Resolve (IMemberContext ec, int index)
 190                 {
 191                         return parameter_type;
 192                 }
 193         }
 194
 195         public interface IParameterData
 196         {
 197                 Expression DefaultValue { get; }
 198                 bool HasExtensionMethodModifier { get; }
 199                 bool HasDefaultValue { get; }
 200                 Parameter.Modifier ModFlags { get; }
 201                 string Name { get; }
 202         }
 203
 204         //
 205         // Parameter information created by parser
 206         //
 207         public class Parameter : ParameterBase, IParameterData, ILocalVariable // TODO: INamedBlockVariable
 208         {
 209                 [Flags]
 210                 public enum Modifier : byte {
 211                         NONE    = 0,
 212                         PARAMS  = 1 << 0,
 213                         REF = 1 << 1,
 214                         OUT = 1 << 2,
 215                         This = 1 << 3,
 216                         CallerMemberName = 1 << 4,
 217                         CallerLineNumber = 1 << 5,
 218                         CallerFilePath = 1 << 6,
 219
 220                         RefOutMask = REF | OUT,
 221                         ModifierMask = PARAMS | REF | OUT | This,
 222                         CallerMask = CallerMemberName | CallerLineNumber | CallerFilePath
 223                 }
 224
 225                 static readonly string[] attribute_targets = new string[] { "param" };
 226                 static readonly string[] attribute_targets_primary = new string[] { "param", "field" };
 227
 228                 FullNamedExpression texpr;
 229                 Modifier modFlags;
 230                 string name;
 231                 Expression default_expr;
 232                 protected TypeSpec parameter_type;
 233                 readonly Location loc;
 234                 protected int idx;
 235                 public bool HasAddressTaken;
 236
 237                 Constructor primary_constructor;
 238                 TemporaryVariableReference expr_tree_variable;
 239
 240                 HoistedParameter hoisted_variant;
 241
 242                 public Parameter (FullNamedExpression type, string name, Modifier mod, Attributes attrs, Location loc)
 243                 {
 244                         this.name = name;
 245                         modFlags = mod;
 246                         this.loc = loc;
 247                         texpr = type;
 248
 249                         // Only assign, attributes will be attached during resolve
 250                         base.attributes = attrs;
 251                 }
 252
 253                 #region Properties
 254
 255                 public Expression DefaultExpression {
 256                         get {
 257                                 return default_expr;
 258                         }
 259                 }
 260
 261                 public DefaultParameterValueExpression DefaultValue {
 262                         get {
 263                                 return default_expr as DefaultParameterValueExpression;
 264                         }
 265                         set {
 266                                 default_expr = value;
 267                         }
 268                 }
 269
 270                 Expression IParameterData.DefaultValue {
 271                         get {
 272                                 var expr = default_expr as DefaultParameterValueExpression;
 273                                 return expr == null ? default_expr : expr.Child;
 274                         }
 275                 }
 276
 277                 bool HasOptionalExpression {
 278                         get {
 279                                 return default_expr is DefaultParameterValueExpression;
 280                         }
 281                 }
 282
 283                 public Location Location {
 284                         get {
 285                                 return loc;
 286                         }
 287                 }
 288
 289                 public Modifier ParameterModifier {
 290                         get {
 291                                 return modFlags;
 292                         }
 293                 }
 294
 295                 public TypeSpec Type {
 296                         get {
 297                                 return parameter_type;
 298                         }
 299                         set {
 300                                 parameter_type = value;
 301                         }
 302                 }
 303
 304                 public FullNamedExpression TypeExpression  {
 305                         get {
 306                                 return texpr;
 307                         }
 308                 }
 309
 310                 public override string[] ValidAttributeTargets {
 311                         get {
 312                                 return primary_constructor != null ? attribute_targets_primary : attribute_targets;
 313                         }
 314                 }
 315
 316                 #endregion
 317
 318                 public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
 319                 {
 320                         if (a.Target == AttributeTargets.Field) {
 321                                 var field = MemberCache.FindMember (primary_constructor.Spec.DeclaringType, MemberFilter.Field (name, parameter_type), BindingRestriction.DeclaredOnly);
 322                                 ((Field)field.MemberDefinition).ApplyAttributeBuilder (a, ctor, cdata, pa);
 323                                 return;
 324                         }
 325
 326                         if (a.Type == pa.In && ModFlags == Modifier.OUT) {
 327                                 a.Report.Error (36, a.Location, "An out parameter cannot have the `In' attribute");
 328                                 return;
 329                         }
 330
 331                         if (a.Type == pa.ParamArray) {
 332                                 a.Report.Error (674, a.Location, "Do not use `System.ParamArrayAttribute'. Use the `params' keyword instead");
 333                                 return;
 334                         }
 335
 336                         if (a.Type == pa.Out && (ModFlags & Modifier.REF) != 0 &&
 337                             !OptAttributes.Contains (pa.In)) {
 338                                 a.Report.Error (662, a.Location,
 339                                         "Cannot specify only `Out' attribute on a ref parameter. Use both `In' and `Out' attributes or neither");
 340                                 return;
 341                         }
 342
 343                         if (a.Type == pa.CLSCompliant) {
 344                                 a.Report.Warning (3022, 1, a.Location, "CLSCompliant attribute has no meaning when applied to parameters. Try putting it on the method instead");
 345                         } else if (a.Type == pa.DefaultParameterValue || a.Type == pa.OptionalParameter) {
 346                                 if (HasOptionalExpression) {
 347                                         a.Report.Error (1745, a.Location,
 348                                                 "Cannot specify `{0}' attribute on optional parameter `{1}'",
 349                                                 a.Type.GetSignatureForError ().Replace ("Attribute", ""), Name);
 350                                 }
 351
 352                                 if (a.Type == pa.DefaultParameterValue)
 353                                         return;
 354                         } else if (a.Type == pa.CallerMemberNameAttribute) {
 355                                 if ((modFlags & Modifier.CallerMemberName) == 0) {
 356                                         a.Report.Error (4022, a.Location,
 357                                                 "The CallerMemberName attribute can only be applied to parameters with default value");
 358                                 }
 359                         } else if (a.Type == pa.CallerLineNumberAttribute) {
 360                                 if ((modFlags & Modifier.CallerLineNumber) == 0) {
 361                                         a.Report.Error (4020, a.Location,
 362                                                 "The CallerLineNumber attribute can only be applied to parameters with default value");
 363                                 }
 364                         } else if (a.Type == pa.CallerFilePathAttribute) {
 365                                 if ((modFlags & Modifier.CallerFilePath) == 0) {
 366                                         a.Report.Error (4021, a.Location,
 367                                                 "The CallerFilePath attribute can only be applied to parameters with default value");
 368                                 }
 369                         }
 370
 371                         base.ApplyAttributeBuilder (a, ctor, cdata, pa);
 372                 }
 373
 374                 public virtual bool CheckAccessibility (InterfaceMemberBase member)
 375                 {
 376                         if (parameter_type == null)
 377                                 return true;
 378
 379                         return member.IsAccessibleAs (parameter_type);
 380                 }
 381
 382                 bool IsValidCallerContext (MemberCore memberContext)
 383                 {
 384                         var m = memberContext as Method;
 385                         if (m != null)
 386                                 return !m.IsPartialImplementation;
 387
 388                         return true;
 389                 }
 390
 391                 // <summary>
 392                 //   Resolve is used in method definitions
 393                 // </summary>
 394                 public virtual TypeSpec Resolve (IMemberContext rc, int index)
 395                 {
 396                         if (parameter_type != null)
 397                                 return parameter_type;
 398
 399                         if (attributes != null)
 400                                 attributes.AttachTo (this, rc);
 401
 402                         var ctor = rc.CurrentMemberDefinition as Constructor;
 403                         if (ctor != null && ctor.IsPrimaryConstructor)
 404                                 primary_constructor = ctor;
 405
 406                         parameter_type = texpr.ResolveAsType (rc);
 407                         if (parameter_type == null)
 408                                 return null;
 409
 410                         this.idx = index;
 411
 412                         if ((modFlags & Parameter.Modifier.RefOutMask) != 0 && parameter_type.IsSpecialRuntimeType) {
 413                                 rc.Module.Compiler.Report.Error (1601, Location, "Method or delegate parameter cannot be of type `{0}'",
 414                                         GetSignatureForError ());
 415                                 return null;
 416                         }
 417
 418                         VarianceDecl.CheckTypeVariance (parameter_type,
 419                                 (modFlags & Parameter.Modifier.RefOutMask) != 0 ? Variance.None : Variance.Contravariant,
 420                                 rc);
 421
 422                         if (parameter_type.IsStatic) {
 423                                 rc.Module.Compiler.Report.Error (721, Location, "`{0}': static types cannot be used as parameters",
 424                                         texpr.GetSignatureForError ());
 425                                 return parameter_type;
 426                         }
 427
 428                         if ((modFlags & Modifier.This) != 0 && (parameter_type.IsPointer || parameter_type.BuiltinType == BuiltinTypeSpec.Type.Dynamic)) {
 429                                 rc.Module.Compiler.Report.Error (1103, Location, "The extension method cannot be of type `{0}'",
 430                                         parameter_type.GetSignatureForError ());
 431                         }
 432
 433                         return parameter_type;
 434                 }
 435
 436                 void ResolveCallerAttributes (ResolveContext rc)
 437                 {
 438                         var pa = rc.Module.PredefinedAttributes;
 439                         TypeSpec caller_type;
 440                         Attribute callerMemberName = null, callerFilePath = null;
 441
 442                         foreach (var attr in attributes.Attrs) {
 443                                 var atype = attr.ResolveTypeForComparison ();
 444                                 if (atype == null)
 445                                         continue;
 446
 447                                 if (atype == pa.CallerMemberNameAttribute) {
 448                                         caller_type = rc.BuiltinTypes.String;
 449                                         if (caller_type != parameter_type && !Convert.ImplicitReferenceConversionExists (caller_type, parameter_type)) {
 450                                                 rc.Report.Error (4019, attr.Location,
 451                                                         "The CallerMemberName attribute cannot be applied because there is no standard conversion from `{0}' to `{1}'",
 452                                                         caller_type.GetSignatureForError (), parameter_type.GetSignatureForError ());
 453                                         }
 454
 455                                         if (!IsValidCallerContext (rc.CurrentMemberDefinition)) {
 456                                                 rc.Report.Warning (4026, 1, attr.Location,
 457                                                         "The CallerMemberName applied to parameter `{0}' will have no effect because it applies to a member that is used in context that do not allow optional arguments",
 458                                                         name);
 459                                         }
 460
 461                                         modFlags |= Modifier.CallerMemberName;
 462                                         callerMemberName = attr;
 463                                         continue;
 464                                 }
 465
 466                                 if (atype == pa.CallerLineNumberAttribute) {
 467                                         caller_type = rc.BuiltinTypes.Int;
 468                                         if (caller_type != parameter_type && !Convert.ImplicitNumericConversionExists (caller_type, parameter_type)) {
 469                                                 rc.Report.Error (4017, attr.Location,
 470                                                         "The CallerLineNumberAttribute attribute cannot be applied because there is no standard conversion from `{0}' to `{1}'",
 471                                                         caller_type.GetSignatureForError (), parameter_type.GetSignatureForError ());
 472                                         }
 473
 474                                         if (!IsValidCallerContext (rc.CurrentMemberDefinition)) {
 475                                                 rc.Report.Warning (4024, 1, attr.Location,
 476                                                         "The CallerLineNumberAttribute applied to parameter `{0}' will have no effect because it applies to a member that is used in context that do not allow optional arguments",
 477                                                         name);
 478                                         }
 479
 480                                         modFlags |= Modifier.CallerLineNumber;
 481                                         continue;
 482                                 }
 483
 484                                 if (atype == pa.CallerFilePathAttribute) {
 485                                         caller_type = rc.BuiltinTypes.String;
 486                                         if (caller_type != parameter_type && !Convert.ImplicitReferenceConversionExists (caller_type, parameter_type)) {
 487                                                 rc.Report.Error (4018, attr.Location,
 488                                                         "The CallerFilePath attribute cannot be applied because there is no standard conversion from `{0}' to `{1}'",
 489                                                         caller_type.GetSignatureForError (), parameter_type.GetSignatureForError ());
 490                                         }
 491
 492                                         if (!IsValidCallerContext (rc.CurrentMemberDefinition)) {
 493                                                 rc.Report.Warning (4025, 1, attr.Location,
 494                                                         "The CallerFilePath applied to parameter `{0}' will have no effect because it applies to a member that is used in context that do not allow optional arguments",
 495                                                         name);
 496                                         }
 497
 498                                         modFlags |= Modifier.CallerFilePath;
 499                                         callerFilePath = attr;
 500                                         continue;
 501                                 }
 502                         }
 503
 504                         if ((modFlags & Modifier.CallerLineNumber) != 0) {
 505                                 if (callerMemberName != null) {
 506                                         rc.Report.Warning (7081, 1, callerMemberName.Location,
 507                                                 "The CallerMemberNameAttribute applied to parameter `{0}' will have no effect. It is overridden by the CallerLineNumberAttribute",
 508                                                 Name);
 509                                 }
 510
 511                                 if (callerFilePath != null) {
 512                                         rc.Report.Warning (7082, 1, callerFilePath.Location,
 513                                                 "The CallerFilePathAttribute applied to parameter `{0}' will have no effect. It is overridden by the CallerLineNumberAttribute",
 514                                                 name);
 515                                 }
 516                         }
 517
 518                         if ((modFlags & Modifier.CallerMemberName) != 0) {
 519                                 if (callerFilePath != null) {
 520                                         rc.Report.Warning (7080, 1, callerFilePath.Location,
 521                                                 "The CallerMemberNameAttribute applied to parameter `{0}' will have no effect. It is overridden by the CallerFilePathAttribute",
 522                                                 name);
 523                                 }
 524
 525                         }
 526                 }
 527
 528                 public void ResolveDefaultValue (ResolveContext rc)
 529                 {
 530                         //
 531                         // Default value was specified using an expression
 532                         //
 533                         if (default_expr != null) {
 534                                 ((DefaultParameterValueExpression)default_expr).Resolve (rc, this);
 535                                 if (attributes != null)
 536                                         ResolveCallerAttributes (rc);
 537
 538                                 return;
 539                         }
 540
 541                         if (attributes == null)
 542                                 return;
 543
 544                         var pa = rc.Module.PredefinedAttributes;
 545                         var def_attr = attributes.Search (pa.DefaultParameterValue);
 546                         if (def_attr != null) {
 547                                 if (def_attr.Resolve () == null)
 548                                         return;
 549
 550                                 var default_expr_attr = def_attr.GetParameterDefaultValue ();
 551                                 if (default_expr_attr == null)
 552                                         return;
 553
 554                                 var dpa_rc = def_attr.CreateResolveContext ();
 555                                 default_expr = default_expr_attr.Resolve (dpa_rc);
 556
 557                                 if (default_expr is BoxedCast)
 558                                         default_expr = ((BoxedCast) default_expr).Child;
 559
 560                                 Constant c = default_expr as Constant;
 561                                 if (c == null) {
 562                                         if (parameter_type.BuiltinType == BuiltinTypeSpec.Type.Object) {
 563                                                 rc.Report.Error (1910, default_expr.Location,
 564                                                         "Argument of type `{0}' is not applicable for the DefaultParameterValue attribute",
 565                                                         default_expr.Type.GetSignatureForError ());
 566                                         } else {
 567                                                 rc.Report.Error (1909, default_expr.Location,
 568                                                         "The DefaultParameterValue attribute is not applicable on parameters of type `{0}'",
 569                                                         default_expr.Type.GetSignatureForError ());
 570                                         }
 571
 572                                         default_expr = null;
 573                                         return;
 574                                 }
 575
 576                                 if (TypeSpecComparer.IsEqual (default_expr.Type, parameter_type) ||
 577                                         (default_expr is NullConstant && TypeSpec.IsReferenceType (parameter_type) && !parameter_type.IsGenericParameter) ||
 578                                         parameter_type.BuiltinType == BuiltinTypeSpec.Type.Object) {
 579                                         return;
 580                                 }
 581
 582                                 //
 583                                 // LAMESPEC: Some really weird csc behaviour which we have to mimic
 584                                 // User operators returning same type as parameter type are considered
 585                                 // valid for this attribute only
 586                                 //
 587                                 // struct S { public static implicit operator S (int i) {} }
 588                                 //
 589                                 // void M ([DefaultParameterValue (3)]S s)
 590                                 //
 591                                 var expr = Convert.ImplicitUserConversion (dpa_rc, default_expr, parameter_type, loc);
 592                                 if (expr != null && TypeSpecComparer.IsEqual (expr.Type, parameter_type)) {
 593                                         return;
 594                                 }
 595
 596                                 rc.Report.Error (1908, default_expr.Location, "The type of the default value should match the type of the parameter");
 597                                 return;
 598                         }
 599
 600                         var opt_attr = attributes.Search (pa.OptionalParameter);
 601                         if (opt_attr != null) {
 602                                 default_expr = EmptyExpression.MissingValue;
 603                         }
 604                 }
 605
 606                 public bool HasDefaultValue {
 607                         get { return default_expr != null; }
 608                 }
 609
 610                 public bool HasExtensionMethodModifier {
 611                         get { return (modFlags & Modifier.This) != 0; }
 612                 }
 613
 614                 //
 615                 // Hoisted parameter variant
 616                 //
 617                 public HoistedParameter HoistedVariant {
 618                         get {
 619                                 return hoisted_variant;
 620                         }
 621                         set {
 622                                 hoisted_variant = value;
 623                         }
 624                 }
 625
 626                 public Modifier ModFlags {
 627                         get { return modFlags & ~Modifier.This; }
 628                 }
 629
 630                 public string Name {
 631                         get { return name; }
 632                         set { name = value; }
 633                 }
 634
 635                 public override AttributeTargets AttributeTargets {
 636                         get {
 637                                 return AttributeTargets.Parameter;
 638                         }
 639                 }
 640
 641                 public void Error_DuplicateName (Report r)
 642                 {
 643                         r.Error (100, Location, "The parameter name `{0}' is a duplicate", Name);
 644                 }
 645
 646                 public virtual string GetSignatureForError ()
 647                 {
 648                         string type_name;
 649                         if (parameter_type != null)
 650                                 type_name = parameter_type.GetSignatureForError ();
 651                         else
 652                                 type_name = texpr.GetSignatureForError ();
 653
 654                         string mod = GetModifierSignature (modFlags);
 655                         if (mod.Length > 0)
 656                                 return String.Concat (mod, " ", type_name);
 657
 658                         return type_name;
 659                 }
 660
 661                 public static string GetModifierSignature (Modifier mod)
 662                 {
 663                         switch (mod) {
 664                         case Modifier.OUT:
 665                                 return "out";
 666                         case Modifier.PARAMS:
 667                                 return "params";
 668                         case Modifier.REF:
 669                                 return "ref";
 670                         case Modifier.This:
 671                                 return "this";
 672                         default:
 673                                 return "";
 674                         }
 675                 }
 676
 677                 public void IsClsCompliant (IMemberContext ctx)
 678                 {
 679                         if (parameter_type.IsCLSCompliant ())
 680                                 return;
 681
 682                         ctx.Module.Compiler.Report.Warning (3001, 1, Location,
 683                                 "Argument type `{0}' is not CLS-compliant", parameter_type.GetSignatureForError ());
 684                 }
 685
 686                 public virtual void ApplyAttributes (MethodBuilder mb, ConstructorBuilder cb, int index, PredefinedAttributes pa)
 687                 {
 688                         if (builder != null)
 689                                 throw new InternalErrorException ("builder already exists");
 690
 691                         var pattrs = ParametersCompiled.GetParameterAttribute (modFlags);
 692                         if (HasOptionalExpression)
 693                                 pattrs |= ParameterAttributes.Optional;
 694
 695                         if (mb == null)
 696                                 builder = cb.DefineParameter (index, pattrs, Name);
 697                         else
 698                                 builder = mb.DefineParameter (index, pattrs, Name);
 699
 700                         if (OptAttributes != null)
 701                                 OptAttributes.Emit ();
 702
 703                         if (HasDefaultValue && default_expr.Type != null) {
 704                                 //
 705                                 // Emit constant values for true constants only, the other
 706                                 // constant-like expressions will rely on default value expression
 707                                 //
 708                                 var def_value = DefaultValue;
 709                                 Constant c = def_value != null ? def_value.Child as Constant : default_expr as Constant;
 710                                 if (c != null) {
 711                                         if (c.Type.BuiltinType == BuiltinTypeSpec.Type.Decimal) {
 712                                                 pa.DecimalConstant.EmitAttribute (builder, (decimal) c.GetValue (), c.Location);
 713                                         } else {
 714                                                 builder.SetConstant (c.GetValue ());
 715                                         }
 716                                 } else if (default_expr.Type.IsStruct || default_expr.Type.IsGenericParameter) {
 717                                         //
 718                                         // Handles special case where default expression is used with value-type or type parameter
 719                                         //
 720                                         // void Foo (S s = default (S)) {}
 721                                         //
 722                                         builder.SetConstant (null);
 723                                 }
 724                         }
 725
 726                         if (parameter_type != null) {
 727                                 if (parameter_type.BuiltinType == BuiltinTypeSpec.Type.Dynamic) {
 728                                         pa.Dynamic.EmitAttribute (builder);
 729                                 } else if (parameter_type.HasDynamicElement) {
 730                                         pa.Dynamic.EmitAttribute (builder, parameter_type, Location);
 731                                 }
 732                         }
 733                 }
 734
 735                 public Parameter Clone ()
 736                 {
 737                         Parameter p = (Parameter) MemberwiseClone ();
 738                         if (attributes != null)
 739                                 p.attributes = attributes.Clone ();
 740
 741                         return p;
 742                 }
 743
 744                 public ExpressionStatement CreateExpressionTreeVariable (BlockContext ec)
 745                 {
 746                         if ((modFlags & Modifier.RefOutMask) != 0)
 747                                 ec.Report.Error (1951, Location, "An expression tree parameter cannot use `ref' or `out' modifier");
 748
 749                         expr_tree_variable = TemporaryVariableReference.Create (ResolveParameterExpressionType (ec, Location).Type, ec.CurrentBlock.ParametersBlock, Location);
 750                         expr_tree_variable = (TemporaryVariableReference) expr_tree_variable.Resolve (ec);
 751
 752                         Arguments arguments = new Arguments (2);
 753                         arguments.Add (new Argument (new TypeOf (parameter_type, Location)));
 754                         arguments.Add (new Argument (new StringConstant (ec.BuiltinTypes, Name, Location)));
 755                         return new SimpleAssign (ExpressionTreeVariableReference (),
 756                                 Expression.CreateExpressionFactoryCall (ec, "Parameter", null, arguments, Location));
 757                 }
 758
 759                 public void Emit (EmitContext ec)
 760                 {
 761                         ec.EmitArgumentLoad (idx);
 762                 }
 763
 764                 public void EmitAssign (EmitContext ec)
 765                 {
 766                         ec.EmitArgumentStore (idx);
 767                 }
 768
 769                 public void EmitAddressOf (EmitContext ec)
 770                 {
 771                         if ((ModFlags & Modifier.RefOutMask) != 0) {
 772                                 ec.EmitArgumentLoad (idx);
 773                         } else {
 774                                 ec.EmitArgumentAddress (idx);
 775                         }
 776                 }
 777
 778                 public TemporaryVariableReference ExpressionTreeVariableReference ()
 779                 {
 780                         return expr_tree_variable;
 781                 }
 782
 783                 //
 784                 // System.Linq.Expressions.ParameterExpression type
 785                 //
 786                 public static TypeExpr ResolveParameterExpressionType (IMemberContext ec, Location location)
 787                 {
 788                         TypeSpec p_type = ec.Module.PredefinedTypes.ParameterExpression.Resolve ();
 789                         return new TypeExpression (p_type, location);
 790                 }
 791
 792                 public void Warning_UselessOptionalParameter (Report Report)
 793                 {
 794                         Report.Warning (1066, 1, Location,
 795                                 "The default value specified for optional parameter `{0}' will never be used",
 796                                 Name);
 797                 }
 798         }
 799
 800         //
 801         // Imported or resolved parameter information
 802         //
 803         public class ParameterData : IParameterData
 804         {
 805                 readonly string name;
 806                 readonly Parameter.Modifier modifiers;
 807                 readonly Expression default_value;
 808
 809                 public ParameterData (string name, Parameter.Modifier modifiers)
 810                 {
 811                         this.name = name;
 812                         this.modifiers = modifiers;
 813                 }
 814
 815                 public ParameterData (string name, Parameter.Modifier modifiers, Expression defaultValue)
 816                         : this (name, modifiers)
 817                 {
 818                         this.default_value = defaultValue;
 819                 }
 820
 821                 #region IParameterData Members
 822
 823                 public Expression DefaultValue {
 824                         get { return default_value; }
 825                 }
 826
 827                 public bool HasExtensionMethodModifier {
 828                         get { return (modifiers & Parameter.Modifier.This) != 0; }
 829                 }
 830
 831                 public bool HasDefaultValue {
 832                         get { return default_value != null; }
 833                 }
 834
 835                 public Parameter.Modifier ModFlags {
 836                         get { return modifiers; }
 837                 }
 838
 839                 public string Name {
 840                         get { return name; }
 841                 }
 842
 843                 #endregion
 844         }
 845
 846         public abstract class AParametersCollection
 847         {
 848                 protected bool has_arglist;
 849                 protected bool has_params;
 850
 851                 // Null object pattern
 852                 protected IParameterData [] parameters;
 853                 protected TypeSpec [] types;
 854
 855                 public CallingConventions CallingConvention {
 856                         get {
 857                                 return has_arglist ?
 858                                         CallingConventions.VarArgs :
 859                                         CallingConventions.Standard;
 860                         }
 861                 }
 862
 863                 public int Count {
 864                         get { return parameters.Length; }
 865                 }
 866
 867                 public TypeSpec ExtensionMethodType {
 868                         get {
 869                                 if (Count == 0)
 870                                         return null;
 871
 872                                 return FixedParameters [0].HasExtensionMethodModifier ?
 873                                         types [0] : null;
 874                         }
 875                 }
 876
 877                 public IParameterData [] FixedParameters {
 878                         get {
 879                                 return parameters;
 880                         }
 881                 }
 882
 883                 public static ParameterAttributes GetParameterAttribute (Parameter.Modifier modFlags)
 884                 {
 885                         return (modFlags & Parameter.Modifier.OUT) != 0 ?
 886                                 ParameterAttributes.Out : ParameterAttributes.None;
 887                 }
 888
 889                 // Very expensive operation
 890                 public MetaType[] GetMetaInfo ()
 891                 {
 892                         MetaType[] types;
 893                         if (has_arglist) {
 894                                 if (Count == 1)
 895                                         return MetaType.EmptyTypes;
 896
 897                                 types = new MetaType[Count - 1];
 898                         } else {
 899                                 if (Count == 0)
 900                                         return MetaType.EmptyTypes;
 901
 902                                 types = new MetaType[Count];
 903                         }
 904
 905                         for (int i = 0; i < types.Length; ++i) {
 906                                 types[i] = Types[i].GetMetaInfo ();
 907
 908                                 if ((FixedParameters[i].ModFlags & Parameter.Modifier.RefOutMask) == 0)
 909                                         continue;
 910
 911                                 // TODO MemberCache: Should go to MetaInfo getter
 912                                 types [i] = types [i].MakeByRefType ();
 913                         }
 914
 915                         return types;
 916                 }
 917
 918                 //
 919                 // Returns the parameter information based on the name
 920                 //
 921                 public int GetParameterIndexByName (string name)
 922                 {
 923                         for (int idx = 0; idx < Count; ++idx) {
 924                                 if (parameters [idx].Name == name)
 925                                         return idx;
 926                         }
 927
 928                         return -1;
 929                 }
 930
 931                 public string GetSignatureForDocumentation ()
 932                 {
 933                         if (IsEmpty)
 934                                 return string.Empty;
 935
 936                         StringBuilder sb = new StringBuilder ("(");
 937                         for (int i = 0; i < Count; ++i) {
 938                                 if (i != 0)
 939                                         sb.Append (",");
 940
 941                                 sb.Append (types [i].GetSignatureForDocumentation ());
 942
 943                                 if ((parameters[i].ModFlags & Parameter.Modifier.RefOutMask) != 0)
 944                                         sb.Append ("@");
 945                         }
 946                         sb.Append (")");
 947
 948                         return sb.ToString ();
 949                 }
 950
 951                 public string GetSignatureForError ()
 952                 {
 953                         return GetSignatureForError ("(", ")", Count);
 954                 }
 955
 956                 public string GetSignatureForError (string start, string end, int count)
 957                 {
 958                         StringBuilder sb = new StringBuilder (start);
 959                         for (int i = 0; i < count; ++i) {
 960                                 if (i != 0)
 961                                         sb.Append (", ");
 962                                 sb.Append (ParameterDesc (i));
 963                         }
 964                         sb.Append (end);
 965                         return sb.ToString ();
 966                 }
 967
 968                 public bool HasArglist {
 969                         get { return has_arglist; }
 970                 }
 971
 972                 public bool HasExtensionMethodType {
 973                         get {
 974                                 if (Count == 0)
 975                                         return false;
 976
 977                                 return FixedParameters [0].HasExtensionMethodModifier;
 978                         }
 979                 }
 980
 981                 public bool HasParams {
 982                         get { return has_params; }
 983                 }
 984
 985                 public bool IsEmpty {
 986                         get { return parameters.Length == 0; }
 987                 }
 988
 989                 public AParametersCollection Inflate (TypeParameterInflator inflator)
 990                 {
 991                         TypeSpec[] inflated_types = null;
 992                         bool default_value = false;
 993
 994                         for (int i = 0; i < Count; ++i) {
 995                                 var inflated_param = inflator.Inflate (types[i]);
 996                                 if (inflated_types == null) {
 997                                         if (inflated_param == types[i])
 998                                                 continue;
 999
1000                                         default_value |= FixedParameters[i].HasDefaultValue;
1001                                         inflated_types = new TypeSpec[types.Length];
1002                                         Array.Copy (types, inflated_types, types.Length);
1003                                 } else {
1004                                         if (inflated_param == types[i])
1005                                                 continue;
1006
1007                                         default_value |= FixedParameters[i].HasDefaultValue;
1008                                 }
1009
1010                                 inflated_types[i] = inflated_param;
1011                         }
1012
1013                         if (inflated_types == null)
1014                                 return this;
1015
1016                         var clone = (AParametersCollection) MemberwiseClone ();
1017                         clone.types = inflated_types;
1018
1019                         //
1020                         // Default expression is original expression from the parameter
1021                         // declaration context which can be of nested enum in generic class type.
1022                         // In such case we end up with expression type of G<T>.E and e.g. parameter
1023                         // type of G<int>.E and conversion would fail without inflate in this
1024                         // context.
1025                         //
1026                         if (default_value) {
1027                                 clone.parameters = new IParameterData[Count];
1028                                 for (int i = 0; i < Count; ++i) {
1029                                         var fp = FixedParameters[i];
1030                                         clone.FixedParameters[i] = fp;
1031
1032                                         if (!fp.HasDefaultValue)
1033                                                 continue;
1034
1035                                         var expr = fp.DefaultValue;
1036
1037                                         if (inflated_types[i] == expr.Type)
1038                                                 continue;
1039
1040                                         var c = expr as Constant;
1041                                         if (c != null) {
1042                                                 //
1043                                                 // It may fail we are inflating before type validation is done
1044                                                 //
1045                                                 c = Constant.ExtractConstantFromValue (inflated_types[i], c.GetValue (), expr.Location);
1046                                                 if (c == null)
1047                                                         expr = new DefaultValueExpression (new TypeExpression (inflated_types[i], expr.Location), expr.Location);
1048                                                 else
1049                                                         expr = c;
1050                                         } else if (expr is DefaultValueExpression)
1051                                                 expr = new DefaultValueExpression (new TypeExpression (inflated_types[i], expr.Location), expr.Location);
1052
1053                                         clone.FixedParameters[i] = new ParameterData (fp.Name, fp.ModFlags, expr);
1054                                 }
1055                         }
1056
1057                         return clone;
1058                 }
1059
1060                 public string ParameterDesc (int pos)
1061                 {
1062                         if (types == null || types [pos] == null)
1063                                 return ((Parameter)FixedParameters [pos]).GetSignatureForError ();
1064
1065                         string type = types [pos].GetSignatureForError ();
1066                         if (FixedParameters [pos].HasExtensionMethodModifier)
1067                                 return "this " + type;
1068
1069                         var mod = FixedParameters[pos].ModFlags & Parameter.Modifier.ModifierMask;
1070                         if (mod == 0)
1071                                 return type;
1072
1073                         return Parameter.GetModifierSignature (mod) + " " + type;
1074                 }
1075
1076                 public TypeSpec[] Types {
1077                         get { return types; }
1078                         set { types = value; }
1079                 }
1080         }
1081
1082         //
1083         // A collection of imported or resolved parameters
1084         //
1085         public class ParametersImported : AParametersCollection
1086         {
1087                 public ParametersImported (IParameterData [] parameters, TypeSpec [] types, bool hasArglist, bool hasParams)
1088                 {
1089                         this.parameters = parameters;
1090                         this.types = types;
1091                         this.has_arglist = hasArglist;
1092                         this.has_params = hasParams;
1093                 }
1094
1095                 public ParametersImported (IParameterData[] param, TypeSpec[] types, bool hasParams)
1096                 {
1097                         this.parameters = param;
1098                         this.types = types;
1099                         this.has_params = hasParams;
1100                 }
1101         }
1102
1103         /// <summary>
1104         ///   Represents the methods parameters
1105         /// </summary>
1106         public class ParametersCompiled : AParametersCollection
1107         {
1108                 public static readonly ParametersCompiled EmptyReadOnlyParameters = new ParametersCompiled ();
1109
1110                 // Used by C# 2.0 delegates
1111                 public static readonly ParametersCompiled Undefined = new ParametersCompiled ();
1112
1113                 private ParametersCompiled ()
1114                 {
1115                         parameters = new Parameter [0];
1116                         types = TypeSpec.EmptyTypes;
1117                 }
1118
1119                 private ParametersCompiled (IParameterData[] parameters, TypeSpec[] types)
1120                 {
1121                         this.parameters = parameters;
1122                     this.types = types;
1123                 }
1124
1125                 public ParametersCompiled (params Parameter[] parameters)
1126                 {
1127                         if (parameters == null || parameters.Length == 0)
1128                                 throw new ArgumentException ("Use EmptyReadOnlyParameters");
1129
1130                         this.parameters = parameters;
1131                         int count = parameters.Length;
1132
1133                         for (int i = 0; i < count; i++){
1134                                 has_params |= (parameters [i].ModFlags & Parameter.Modifier.PARAMS) != 0;
1135                         }
1136                 }
1137
1138                 public ParametersCompiled (Parameter [] parameters, bool has_arglist) :
1139                         this (parameters)
1140                 {
1141                         this.has_arglist = has_arglist;
1142                 }
1143
1144                 public static ParametersCompiled CreateFullyResolved (Parameter p, TypeSpec type)
1145                 {
1146                         return new ParametersCompiled (new Parameter [] { p }, new TypeSpec [] { type });
1147                 }
1148
1149                 public static ParametersCompiled CreateFullyResolved (Parameter[] parameters, TypeSpec[] types)
1150                 {
1151                         return new ParametersCompiled (parameters, types);
1152                 }
1153
1154                 //
1155                 // TODO: This does not fit here, it should go to different version of AParametersCollection
1156                 // as the underlying type is not Parameter and some methods will fail to cast
1157                 //
1158                 public static AParametersCollection CreateFullyResolved (params TypeSpec[] types)
1159                 {
1160                         var pd = new ParameterData [types.Length];
1161                         for (int i = 0; i < pd.Length; ++i)
1162                                 pd[i] = new ParameterData (null, Parameter.Modifier.NONE, null);
1163
1164                         return new ParametersCompiled (pd, types);
1165                 }
1166
1167                 public static ParametersCompiled CreateImplicitParameter (FullNamedExpression texpr, Location loc)
1168                 {
1169                         return new ParametersCompiled (
1170                                 new[] { new Parameter (texpr, "value", Parameter.Modifier.NONE, null, loc) },
1171                                 null);
1172                 }
1173
1174                 public void CheckConstraints (IMemberContext mc)
1175                 {
1176                         foreach (Parameter p in parameters) {
1177                                 //
1178                                 // It's null for compiler generated types or special types like __arglist
1179                                 //
1180                                 if (p.TypeExpression != null)
1181                                         ConstraintChecker.Check (mc, p.Type, p.TypeExpression.Location);
1182                         }
1183                 }
1184
1185                 //
1186                 // Returns non-zero value for equal CLS parameter signatures
1187                 //
1188                 public static int IsSameClsSignature (AParametersCollection a, AParametersCollection b)
1189                 {
1190                         int res = 0;
1191
1192                         for (int i = 0; i < a.Count; ++i) {
1193                                 var a_type = a.Types[i];
1194                                 var b_type = b.Types[i];
1195                                 if (TypeSpecComparer.Override.IsEqual (a_type, b_type)) {
1196                                         if ((a.FixedParameters[i].ModFlags & Parameter.Modifier.RefOutMask) != (b.FixedParameters[i].ModFlags & Parameter.Modifier.RefOutMask))
1197                                                 res |= 1;
1198
1199                                         continue;
1200                                 }
1201
1202                                 var ac_a = a_type as ArrayContainer;
1203                                 if (ac_a == null)
1204                                         return 0;
1205
1206                                 var ac_b = b_type as ArrayContainer;
1207                                 if (ac_b == null)
1208                                         return 0;
1209
1210                                 if (ac_a.Element is ArrayContainer || ac_b.Element is ArrayContainer) {
1211                                         res |= 2;
1212                                         continue;
1213                                 }
1214
1215                                 if (ac_a.Rank != ac_b.Rank && TypeSpecComparer.Override.IsEqual (ac_a.Element, ac_b.Element)) {
1216                                         res |= 1;
1217                                         continue;
1218                                 }
1219
1220                                 return 0;
1221                         }
1222
1223                         return res;
1224                 }
1225
1226                 public static ParametersCompiled MergeGenerated (CompilerContext ctx, ParametersCompiled userParams, bool checkConflicts, Parameter compilerParams, TypeSpec compilerTypes)
1227                 {
1228                         return MergeGenerated (ctx, userParams, checkConflicts,
1229                                 new Parameter [] { compilerParams },
1230                                 new TypeSpec [] { compilerTypes });
1231                 }
1232
1233                 //
1234                 // Use this method when you merge compiler generated parameters with user parameters
1235                 //
1236                 public static ParametersCompiled MergeGenerated (CompilerContext ctx, ParametersCompiled userParams, bool checkConflicts, Parameter[] compilerParams, TypeSpec[] compilerTypes)
1237                 {
1238                         Parameter[] all_params = new Parameter [userParams.Count + compilerParams.Length];
1239                         userParams.FixedParameters.CopyTo(all_params, 0);
1240
1241                         TypeSpec [] all_types;
1242                         if (userParams.types != null) {
1243                                 all_types = new TypeSpec [all_params.Length];
1244                                 userParams.Types.CopyTo (all_types, 0);
1245                         } else {
1246                                 all_types = null;
1247                         }
1248
1249                         int last_filled = userParams.Count;
1250                         int index = 0;
1251                         foreach (Parameter p in compilerParams) {
1252                                 for (int i = 0; i < last_filled; ++i) {
1253                                         while (p.Name == all_params [i].Name) {
1254                                                 if (checkConflicts && i < userParams.Count) {
1255                                                         ctx.Report.Error (316, userParams[i].Location,
1256                                                                 "The parameter name `{0}' conflicts with a compiler generated name", p.Name);
1257                                                 }
1258                                                 p.Name = '_' + p.Name;
1259                                         }
1260                                 }
1261                                 all_params [last_filled] = p;
1262                                 if (all_types != null)
1263                                         all_types [last_filled] = compilerTypes [index++];
1264                                 ++last_filled;
1265                         }
1266
1267                         ParametersCompiled parameters = new ParametersCompiled (all_params, all_types);
1268                         parameters.has_params = userParams.has_params;
1269                         return parameters;
1270                 }
1271
1272                 //
1273                 // Parameters checks for members which don't have a block
1274                 //
1275                 public void CheckParameters (MemberCore member)
1276                 {
1277                         for (int i = 0; i < parameters.Length; ++i) {
1278                                 var name = parameters[i].Name;
1279                                 for (int ii = i + 1; ii < parameters.Length; ++ii) {
1280                                         if (parameters[ii].Name == name)
1281                                                 this[ii].Error_DuplicateName (member.Compiler.Report);
1282                                 }
1283                         }
1284                 }
1285
1286                 public bool Resolve (IMemberContext ec)
1287                 {
1288                         if (types != null)
1289                                 return true;
1290
1291                         types = new TypeSpec [Count];
1292
1293                         bool ok = true;
1294                         Parameter p;
1295                         for (int i = 0; i < FixedParameters.Length; ++i) {
1296                                 p = this [i];
1297                                 TypeSpec t = p.Resolve (ec, i);
1298                                 if (t == null) {
1299                                         ok = false;
1300                                         continue;
1301                                 }
1302
1303                                 types [i] = t;
1304                         }
1305
1306                         return ok;
1307                 }
1308
1309                 public void ResolveDefaultValues (MemberCore m)
1310                 {
1311                         ResolveContext rc = null;
1312                         for (int i = 0; i < parameters.Length; ++i) {
1313                                 Parameter p = (Parameter) parameters [i];
1314
1315                                 //
1316                                 // Try not to enter default values resolution if there are is not any default value possible
1317                                 //
1318                                 if (p.HasDefaultValue || p.OptAttributes != null) {
1319                                         if (rc == null)
1320                                                 rc = new ResolveContext (m);
1321
1322                                         p.ResolveDefaultValue (rc);
1323                                 }
1324                         }
1325                 }
1326
1327                 // Define each type attribute (in/out/ref) and
1328                 // the argument names.
1329                 public void ApplyAttributes (IMemberContext mc, MethodBase builder)
1330                 {
1331                         if (Count == 0)
1332                                 return;
1333
1334                         MethodBuilder mb = builder as MethodBuilder;
1335                         ConstructorBuilder cb = builder as ConstructorBuilder;
1336                         var pa = mc.Module.PredefinedAttributes;
1337
1338                         for (int i = 0; i < Count; i++) {
1339                                 this [i].ApplyAttributes (mb, cb, i + 1, pa);
1340                         }
1341                 }
1342
1343                 public void VerifyClsCompliance (IMemberContext ctx)
1344                 {
1345                         foreach (Parameter p in FixedParameters)
1346                                 p.IsClsCompliant (ctx);
1347                 }
1348
1349                 public Parameter this [int pos] {
1350                         get { return (Parameter) parameters [pos]; }
1351                 }
1352
1353                 public Expression CreateExpressionTree (BlockContext ec, Location loc)
1354                 {
1355                         var initializers = new ArrayInitializer (Count, loc);
1356                         foreach (Parameter p in FixedParameters) {
1357                                 //
1358                                 // Each parameter expression is stored to local variable
1359                                 // to save some memory when referenced later.
1360                                 //
1361                                 StatementExpression se = new StatementExpression (p.CreateExpressionTreeVariable (ec), Location.Null);
1362                                 if (se.Resolve (ec)) {
1363                                         ec.CurrentBlock.AddScopeStatement (new TemporaryVariableReference.Declarator (p.ExpressionTreeVariableReference ()));
1364                                         ec.CurrentBlock.AddScopeStatement (se);
1365                                 }
1366
1367                                 initializers.Add (p.ExpressionTreeVariableReference ());
1368                         }
1369
1370                         return new ArrayCreation (
1371                                 Parameter.ResolveParameterExpressionType (ec, loc),
1372                                 initializers, loc);
1373                 }
1374
1375                 public ParametersCompiled Clone ()
1376                 {
1377                         ParametersCompiled p = (ParametersCompiled) MemberwiseClone ();
1378
1379                         p.parameters = new IParameterData [parameters.Length];
1380                         for (int i = 0; i < Count; ++i)
1381                                 p.parameters [i] = this [i].Clone ();
1382
1383                         return p;
1384                 }
1385         }
1386
1387         //
1388         // Default parameter value expression. We need this wrapper to handle
1389         // default parameter values of folded constants (e.g. indexer parameters).
1390         // The expression is resolved only once but applied to two methods which
1391         // both share reference to this expression and we ensure that resolving
1392         // this expression always returns same instance
1393         //
1394         public class DefaultParameterValueExpression : CompositeExpression
1395         {
1396                 public DefaultParameterValueExpression (Expression expr)
1397                         : base (expr)
1398                 {
1399                 }
1400
1401                 public void Resolve (ResolveContext rc, Parameter p)
1402                 {
1403                         var expr = Resolve (rc);
1404                         if (expr == null) {
1405                                 this.expr = ErrorExpression.Instance;
1406                                 return;
1407                         }
1408
1409                         expr = Child;
1410
1411                         if (!(expr is Constant || expr is DefaultValueExpression || (expr is New && ((New) expr).IsDefaultStruct))) {
1412                                 rc.Report.Error (1736, Location,
1413                                         "The expression being assigned to optional parameter `{0}' must be a constant or default value",
1414                                         p.Name);
1415
1416                                 return;
1417                         }
1418
1419                         var parameter_type = p.Type;
1420                         if (type == parameter_type)
1421                                 return;
1422
1423                         var res = Convert.ImplicitConversionStandard (rc, expr, parameter_type, Location);
1424                         if (res != null) {
1425                                 if (parameter_type.IsNullableType && res is Nullable.Wrap) {
1426                                         Nullable.Wrap wrap = (Nullable.Wrap) res;
1427                                         res = wrap.Child;
1428                                         if (!(res is Constant)) {
1429                                                 rc.Report.Error (1770, Location,
1430                                                         "The expression being assigned to nullable optional parameter `{0}' must be default value",
1431                                                         p.Name);
1432                                                 return;
1433                                         }
1434                                 }
1435
1436                                 if (!expr.IsNull && TypeSpec.IsReferenceType (parameter_type) && parameter_type.BuiltinType != BuiltinTypeSpec.Type.String) {
1437                                         rc.Report.Error (1763, Location,
1438                                                 "Optional parameter `{0}' of type `{1}' can only be initialized with `null'",
1439                                                 p.Name, parameter_type.GetSignatureForError ());
1440
1441                                         return;
1442                                 }
1443
1444                                 this.expr = res;
1445                                 return;
1446                         }
1447
1448                         rc.Report.Error (1750, Location,
1449                                 "Optional parameter expression of type `{0}' cannot be converted to parameter type `{1}'",
1450                                 type.GetSignatureForError (), parameter_type.GetSignatureForError ());
1451
1452                         this.expr = ErrorExpression.Instance;
1453                 }
1454
1455                 public override object Accept (StructuralVisitor visitor)
1456                 {
1457                         return visitor.Visit (this);
1458                 }
1459         }
1460 }