mcs/mbas/ecore.cs

   1 //
   2 // ecore.cs: Core of the Expression representation for the intermediate tree.
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //
   7 // (C) 2001 Ximian, Inc.
   8 //
   9 //
  10
  11 namespace Mono.CSharp {
  12         using System;
  13         using System.Collections;
  14         using System.Diagnostics;
  15         using System.Reflection;
  16         using System.Reflection.Emit;
  17         using System.Text;
  18
  19         /// <remarks>
  20         ///   The ExprClass class contains the is used to pass the
  21         ///   classification of an expression (value, variable, namespace,
  22         ///   type, method group, property access, event access, indexer access,
  23         ///   nothing).
  24         /// </remarks>
  25         public enum ExprClass : byte {
  26                 Invalid,
  27
  28                 Value,
  29                 Variable,
  30                 Namespace,
  31                 Type,
  32                 MethodGroup,
  33                 PropertyAccess,
  34                 EventAccess,
  35                 IndexerAccess,
  36                 Nothing,
  37         }
  38
  39         /// <remarks>
  40         ///   This is used to tell Resolve in which types of expressions we're
  41         ///   interested.
  42         /// </remarks>
  43         [Flags]
  44         public enum ResolveFlags {
  45                 // Returns Value, Variable, PropertyAccess, EventAccess or IndexerAccess.
  46                 VariableOrValue         = 1,
  47
  48                 // Returns a type expression.
  49                 Type                    = 2,
  50
  51                 // Returns a method group.
  52                 MethodGroup             = 4,
  53
  54                 // Allows SimpleNames to be returned.
  55                 // This is used by MemberAccess to construct long names that can not be
  56                 // partially resolved (namespace-qualified names for example).
  57                 SimpleName              = 8,
  58
  59                 // Mask of all the expression class flags.
  60                 MaskExprClass           = 15,
  61
  62                 // Disable control flow analysis while resolving the expression.
  63                 // This is used when resolving the instance expression of a field expression.
  64                 DisableFlowAnalysis     = 16
  65         }
  66
  67         //
  68         // This is just as a hint to AddressOf of what will be done with the
  69         // address.
  70         [Flags]
  71         public enum AddressOp {
  72                 Store = 1,
  73                 Load  = 2,
  74                 LoadStore = 3
  75         };
  76
  77         /// <summary>
  78         ///   This interface is implemented by variables
  79         /// </summary>
  80         public interface IMemoryLocation {
  81                 /// <summary>
  82                 ///   The AddressOf method should generate code that loads
  83                 ///   the address of the object and leaves it on the stack.
  84                 ///
  85                 ///   The `mode' argument is used to notify the expression
  86                 ///   of whether this will be used to read from the address or
  87                 ///   write to the address.
  88                 ///
  89                 ///   This is just a hint that can be used to provide good error
  90                 ///   reporting, and should have no other side effects.
  91                 /// </summary>
  92                 void AddressOf (EmitContext ec, AddressOp mode);
  93         }
  94
  95         /// <summary>
  96         ///   This interface is implemented by variables
  97         /// </summary>
  98         public interface IVariable {
  99                 /// <summary>
 100                 ///   Checks whether the variable has already been assigned at
 101                 ///   the current position of the method's control flow and
 102                 ///   reports an appropriate error message if not.
 103                 ///
 104                 ///   If the variable is a struct, then this call checks whether
 105                 ///   all of its fields (including all private ones) have been
 106                 ///   assigned.
 107                 /// </summary>
 108                 bool IsAssigned (EmitContext ec, Location loc);
 109
 110                 /// <summary>
 111                 ///   Checks whether field `name' in this struct has been assigned.
 112                 /// </summary>
 113                 bool IsFieldAssigned (EmitContext ec, string name, Location loc);
 114
 115                 /// <summary>
 116                 ///   Tells the flow analysis code that the variable has already
 117                 ///   been assigned at the current code position.
 118                 ///
 119                 ///   If the variable is a struct, this call marks all its fields
 120                 ///   (including private fields) as being assigned.
 121                 /// </summary>
 122                 void SetAssigned (EmitContext ec);
 123
 124                 /// <summary>
 125                 ///   Tells the flow analysis code that field `name' in this struct
 126                 ///   has already been assigned atthe current code position.
 127                 /// </summary>
 128                 void SetFieldAssigned (EmitContext ec, string name);
 129         }
 130
 131         /// <summary>
 132         ///   This interface denotes an expression which evaluates to a member
 133         ///   of a struct or a class.
 134         /// </summary>
 135         public interface IMemberExpr
 136         {
 137                 /// <summary>
 138                 ///   The name of this member.
 139                 /// </summary>
 140                 string Name {
 141                         get;
 142                 }
 143
 144                 /// <summary>
 145                 ///   Whether this is an instance member.
 146                 /// </summary>
 147                 bool IsInstance {
 148                         get;
 149                 }
 150
 151                 /// <summary>
 152                 ///   Whether this is a static member.
 153                 /// </summary>
 154                 bool IsStatic {
 155                         get;
 156                 }
 157
 158                 /// <summary>
 159                 ///   The type which declares this member.
 160                 /// </summary>
 161                 Type DeclaringType {
 162                         get;
 163                 }
 164
 165                 /// <summary>
 166                 ///   The instance expression associated with this member, if it's a
 167                 ///   non-static member.
 168                 /// </summary>
 169                 Expression InstanceExpression {
 170                         get; set;
 171                 }
 172         }
 173
 174         /// <summary>
 175         ///   Expression which resolves to a type.
 176         /// </summary>
 177         public interface ITypeExpression
 178         {
 179                 /// <summary>
 180                 ///   Resolve the expression, but only lookup types.
 181                 /// </summary>
 182                 Expression DoResolveType (EmitContext ec);
 183         }
 184
 185         /// <remarks>
 186         ///   Base class for expressions
 187         /// </remarks>
 188         public abstract class Expression {
 189                 public ExprClass eclass;
 190                 protected Type type;
 191                 protected Location loc;
 192
 193                 public Type Type {
 194                         get {
 195                                 return type;
 196                         }
 197
 198                         set {
 199                                 type = value;
 200                         }
 201                 }
 202
 203                 public Location Location {
 204                         get {
 205                                 return loc;
 206                         }
 207                 }
 208
 209                 /// <summary>
 210                 ///   Utility wrapper routine for Error, just to beautify the code
 211                 /// </summary>
 212                 public void Error (int error, string s)
 213                 {
 214                         if (!Location.IsNull (loc))
 215                                 Report.Error (error, loc, s);
 216                         else
 217                                 Report.Error (error, s);
 218                 }
 219
 220                 /// <summary>
 221                 ///   Utility wrapper routine for Warning, just to beautify the code
 222                 /// </summary>
 223                 public void Warning (int warning, string s)
 224                 {
 225                         if (!Location.IsNull (loc))
 226                                 Report.Warning (warning, loc, s);
 227                         else
 228                                 Report.Warning (warning, s);
 229                 }
 230
 231                 /// <summary>
 232                 ///   Utility wrapper routine for Warning, only prints the warning if
 233                 ///   warnings of level `level' are enabled.
 234                 /// </summary>
 235                 public void Warning (int warning, int level, string s)
 236                 {
 237                         if (level <= RootContext.WarningLevel)
 238                                 Warning (warning, s);
 239                 }
 240
 241                 static public void Error_CannotConvertType (Location loc, Type source, Type target)
 242                 {
 243                         Report.Error (30, loc, "Cannot convert type '" +
 244                                       TypeManager.CSharpName (source) + "' to '" +
 245                                       TypeManager.CSharpName (target) + "'");
 246                 }
 247
 248                 /// <summary>
 249                 ///   Performs semantic analysis on the Expression
 250                 /// </summary>
 251                 ///
 252                 /// <remarks>
 253                 ///   The Resolve method is invoked to perform the semantic analysis
 254                 ///   on the node.
 255                 ///
 256                 ///   The return value is an expression (it can be the
 257                 ///   same expression in some cases) or a new
 258                 ///   expression that better represents this node.
 259                 ///
 260                 ///   For example, optimizations of Unary (LiteralInt)
 261                 ///   would return a new LiteralInt with a negated
 262                 ///   value.
 263                 ///
 264                 ///   If there is an error during semantic analysis,
 265                 ///   then an error should be reported (using Report)
 266                 ///   and a null value should be returned.
 267                 ///
 268                 ///   There are two side effects expected from calling
 269                 ///   Resolve(): the the field variable "eclass" should
 270                 ///   be set to any value of the enumeration
 271                 ///   `ExprClass' and the type variable should be set
 272                 ///   to a valid type (this is the type of the
 273                 ///   expression).
 274                 /// </remarks>
 275                 public abstract Expression DoResolve (EmitContext ec);
 276
 277                 public virtual Expression DoResolveLValue (EmitContext ec, Expression right_side)
 278                 {
 279                         return DoResolve (ec);
 280                 }
 281
 282                 /// <summary>
 283                 ///   Resolves an expression and performs semantic analysis on it.
 284                 /// </summary>
 285                 ///
 286                 /// <remarks>
 287                 ///   Currently Resolve wraps DoResolve to perform sanity
 288                 ///   checking and assertion checking on what we expect from Resolve.
 289                 /// </remarks>
 290                 public Expression Resolve (EmitContext ec, ResolveFlags flags)
 291                 {
 292                         // Are we doing a types-only search ?
 293                         if ((flags & ResolveFlags.MaskExprClass) == ResolveFlags.Type) {
 294                                 ITypeExpression type_expr = this as ITypeExpression;
 295
 296                                 if (type_expr == null)
 297                                         return null;
 298
 299                                 return type_expr.DoResolveType (ec);
 300                         }
 301
 302                         bool old_do_flow_analysis = ec.DoFlowAnalysis;
 303                         if ((flags & ResolveFlags.DisableFlowAnalysis) != 0)
 304                                 ec.DoFlowAnalysis = false;
 305
 306                         Expression e;
 307                         if (this is SimpleName)
 308                                 e = ((SimpleName) this).DoResolveAllowStatic (ec);
 309                         else
 310                                 e = DoResolve (ec);
 311
 312                         ec.DoFlowAnalysis = old_do_flow_analysis;
 313
 314                         if (e == null)
 315                                 return null;
 316
 317                         if (e is SimpleName){
 318                                 SimpleName s = (SimpleName) e;
 319
 320                                 if ((flags & ResolveFlags.SimpleName) == 0) {
 321
 322                                         object lookup = TypeManager.MemberLookup (
 323                                                 ec.ContainerType, ec.ContainerType, AllMemberTypes,
 324                                                 AllBindingFlags | BindingFlags.NonPublic, s.Name);
 325                                         if (lookup != null)
 326                                                 Error (122, "`" + s.Name + "' " +
 327                                                        "is inaccessible because of its protection level");
 328                                         else
 329                                                 Error (103, "The name `" + s.Name + "' could not be " +
 330                                                        "found in `" + ec.DeclSpace.Name + "'");
 331                                         return null;
 332                                 }
 333
 334                                 return s;
 335                         }
 336
 337                         if ((e is TypeExpr) || (e is ComposedCast)) {
 338                                 if ((flags & ResolveFlags.Type) == 0) {
 339                                         e.Error118 (flags);
 340                                         return null;
 341                                 }
 342
 343                                 return e;
 344                         }
 345
 346                         switch (e.eclass) {
 347                         case ExprClass.Type:
 348                                 if ((flags & ResolveFlags.VariableOrValue) == 0) {
 349                                         e.Error118 (flags);
 350                                         return null;
 351                                 }
 352                                 break;
 353
 354                         case ExprClass.MethodGroup:
 355                                 if ((flags & ResolveFlags.MethodGroup) == 0) {
 356                                         ((MethodGroupExpr) e).ReportUsageError ();
 357                                         return null;
 358                                 }
 359                                 break;
 360
 361                         case ExprClass.Value:
 362                         case ExprClass.Variable:
 363                         case ExprClass.PropertyAccess:
 364                         case ExprClass.EventAccess:
 365                         case ExprClass.IndexerAccess:
 366                                 if ((flags & ResolveFlags.VariableOrValue) == 0) {
 367                                         e.Error118 (flags);
 368                                         return null;
 369                                 }
 370                                 break;
 371
 372                         default:
 373                                 throw new Exception ("Expression " + e.GetType () +
 374                                                      " ExprClass is Invalid after resolve");
 375                         }
 376
 377                         if (e.type == null)
 378                                 throw new Exception (
 379                                         "Expression " + e.GetType () +
 380                                         " did not set its type after Resolve\n" +
 381                                         "called from: " + this.GetType ());
 382
 383                         return e;
 384                 }
 385
 386                 /// <summary>
 387                 ///   Resolves an expression and performs semantic analysis on it.
 388                 /// </summary>
 389                 public Expression Resolve (EmitContext ec)
 390                 {
 391                         return Resolve (ec, ResolveFlags.VariableOrValue);
 392                 }
 393
 394                 /// <summary>
 395                 ///   Resolves an expression for LValue assignment
 396                 /// </summary>
 397                 ///
 398                 /// <remarks>
 399                 ///   Currently ResolveLValue wraps DoResolveLValue to perform sanity
 400                 ///   checking and assertion checking on what we expect from Resolve
 401                 /// </remarks>
 402                 public Expression ResolveLValue (EmitContext ec, Expression right_side)
 403                 {
 404                         Expression e = DoResolveLValue (ec, right_side);
 405
 406                         if (e != null){
 407                                 if (e is SimpleName){
 408                                         SimpleName s = (SimpleName) e;
 409
 410                                         Report.Error (
 411                                                 103, loc,
 412                                                 "The name `" + s.Name + "' could not be found in `" +
 413                                                 ec.DeclSpace.Name + "'");
 414                                         return null;
 415                                 }
 416
 417                                 if (e.eclass == ExprClass.Invalid)
 418                                         throw new Exception ("Expression " + e +
 419                                                              " ExprClass is Invalid after resolve");
 420
 421                                 if (e.eclass == ExprClass.MethodGroup) {
 422                                         ((MethodGroupExpr) e).ReportUsageError ();
 423                                         return null;
 424                                 }
 425
 426                                 if (e.type == null)
 427                                         throw new Exception ("Expression " + e +
 428                                                              " did not set its type after Resolve");
 429                         }
 430
 431                         return e;
 432                 }
 433
 434                 /// <summary>
 435                 ///   Emits the code for the expression
 436                 /// </summary>
 437                 ///
 438                 /// <remarks>
 439                 ///   The Emit method is invoked to generate the code
 440                 ///   for the expression.
 441                 /// </remarks>
 442                 public abstract void Emit (EmitContext ec);
 443
 444                 /// <summary>
 445                 ///   Protected constructor.  Only derivate types should
 446                 ///   be able to be created
 447                 /// </summary>
 448
 449                 protected Expression ()
 450                 {
 451                         eclass = ExprClass.Invalid;
 452                         type = null;
 453                 }
 454
 455                 /// <summary>
 456                 ///   Returns a literalized version of a literal FieldInfo
 457                 /// </summary>
 458                 ///
 459                 /// <remarks>
 460                 ///   The possible return values are:
 461                 ///      IntConstant, UIntConstant
 462                 ///      LongLiteral, ULongConstant
 463                 ///      FloatConstant, DoubleConstant
 464                 ///      StringConstant
 465                 ///
 466                 ///   The value returned is already resolved.
 467                 /// </remarks>
 468                 public static Constant Constantify (object v, Type t)
 469                 {
 470                         if (t == TypeManager.int32_type)
 471                                 return new IntConstant ((int) v);
 472                         else if (t == TypeManager.uint32_type)
 473                                 return new UIntConstant ((uint) v);
 474                         else if (t == TypeManager.int64_type)
 475                                 return new LongConstant ((long) v);
 476                         else if (t == TypeManager.uint64_type)
 477                                 return new ULongConstant ((ulong) v);
 478                         else if (t == TypeManager.float_type)
 479                                 return new FloatConstant ((float) v);
 480                         else if (t == TypeManager.double_type)
 481                                 return new DoubleConstant ((double) v);
 482                         else if (t == TypeManager.string_type)
 483                                 return new StringConstant ((string) v);
 484                         else if (t == TypeManager.short_type)
 485                                 return new ShortConstant ((short)v);
 486                         else if (t == TypeManager.ushort_type)
 487                                 return new UShortConstant ((ushort)v);
 488                         else if (t == TypeManager.sbyte_type)
 489                                 return new SByteConstant (((sbyte)v));
 490                         else if (t == TypeManager.byte_type)
 491                                 return new ByteConstant ((byte)v);
 492                         else if (t == TypeManager.char_type)
 493                                 return new CharConstant ((char)v);
 494                         else if (t == TypeManager.bool_type)
 495                                 return new BoolConstant ((bool) v);
 496                         else if (TypeManager.IsEnumType (t)){
 497                                 Constant e = Constantify (v, TypeManager.TypeToCoreType (v.GetType ()));
 498
 499                                 return new EnumConstant (e, t);
 500                         } else
 501                                 throw new Exception ("Unknown type for constant (" + t +
 502                                                      "), details: " + v);
 503                 }
 504
 505                 /// <summary>
 506                 ///   Returns a fully formed expression after a MemberLookup
 507                 /// </summary>
 508                 public static Expression ExprClassFromMemberInfo (EmitContext ec, MemberInfo mi, Location loc)
 509                 {
 510                         if (mi is EventInfo)
 511                                 return new EventExpr ((EventInfo) mi, loc);
 512                         else if (mi is FieldInfo)
 513                                 return new FieldExpr ((FieldInfo) mi, loc);
 514                         else if (mi is PropertyInfo)
 515                                 return new PropertyExpr (ec, (PropertyInfo) mi, loc);
 516                         else if (mi is Type){
 517                                 return new TypeExpr ((System.Type) mi, loc);
 518                         }
 519
 520                         return null;
 521                 }
 522
 523                 //
 524                 // FIXME: Probably implement a cache for (t,name,current_access_set)?
 525                 //
 526                 // This code could use some optimizations, but we need to do some
 527                 // measurements.  For example, we could use a delegate to `flag' when
 528                 // something can not any longer be a method-group (because it is something
 529                 // else).
 530                 //
 531                 // Return values:
 532                 //     If the return value is an Array, then it is an array of
 533                 //     MethodBases
 534                 //
 535                 //     If the return value is an MemberInfo, it is anything, but a Method
 536                 //
 537                 //     null on error.
 538                 //
 539                 // FIXME: When calling MemberLookup inside an `Invocation', we should pass
 540                 // the arguments here and have MemberLookup return only the methods that
 541                 // match the argument count/type, unlike we are doing now (we delay this
 542                 // decision).
 543                 //
 544                 // This is so we can catch correctly attempts to invoke instance methods
 545                 // from a static body (scan for error 120 in ResolveSimpleName).
 546                 //
 547                 //
 548                 // FIXME: Potential optimization, have a static ArrayList
 549                 //
 550
 551                 public static Expression MemberLookup (EmitContext ec, Type t, string name,
 552                                                        MemberTypes mt, BindingFlags bf, Location loc)
 553                 {
 554                         return MemberLookup (ec, ec.ContainerType, t, name, mt, bf, loc);
 555                 }
 556
 557                 //
 558                 // Lookup type `t' for code in class `invocation_type'.  Note that it's important
 559                 // to set `invocation_type' correctly since this method also checks whether the
 560                 // invoking class is allowed to access the member in class `t'.  When you want to
 561                 // explicitly do a lookup in the base class, you must set both `t' and `invocation_type'
 562                 // to the base class (although a derived class can access protected members of its base
 563                 // class it cannot do so through an instance of the base class (error CS1540)).
 564                 //
 565
 566                 public static Expression MemberLookup (EmitContext ec, Type invocation_type, Type t,
 567                                                        string name, MemberTypes mt, BindingFlags bf,
 568                                                        Location loc)
 569                 {
 570                         MemberInfo [] mi = TypeManager.MemberLookup (invocation_type, t, mt, bf, name);
 571
 572                         if (mi == null)
 573                                 return null;
 574
 575                         int count = mi.Length;
 576
 577                         if (count > 1)
 578                                 return new MethodGroupExpr (mi, loc);
 579
 580                         if (mi [0] is MethodBase)
 581                                 return new MethodGroupExpr (mi, loc);
 582
 583                         return ExprClassFromMemberInfo (ec, mi [0], loc);
 584                 }
 585
 586                 public const MemberTypes AllMemberTypes =
 587                         MemberTypes.Constructor |
 588                         MemberTypes.Event       |
 589                         MemberTypes.Field       |
 590                         MemberTypes.Method      |
 591                         MemberTypes.NestedType  |
 592                         MemberTypes.Property;
 593
 594                 public const BindingFlags AllBindingFlags =
 595                         BindingFlags.Public |
 596                         BindingFlags.Static |
 597                         BindingFlags.Instance;
 598
 599                 public static Expression MemberLookup (EmitContext ec, Type t, string name, Location loc)
 600                 {
 601                         return MemberLookup (ec, ec.ContainerType, t, name,
 602                                              AllMemberTypes, AllBindingFlags, loc);
 603                 }
 604
 605                 public static Expression MethodLookup (EmitContext ec, Type t, string name, Location loc)
 606                 {
 607                         return MemberLookup (ec, ec.ContainerType, t, name,
 608                                              MemberTypes.Method, AllBindingFlags, loc);
 609                 }
 610
 611                 /// <summary>
 612                 ///   This is a wrapper for MemberLookup that is not used to "probe", but
 613                 ///   to find a final definition.  If the final definition is not found, we
 614                 ///   look for private members and display a useful debugging message if we
 615                 ///   find it.
 616                 /// </summary>
 617                 public static Expression MemberLookupFinal (EmitContext ec, Type t, string name,
 618                                                             Location loc)
 619                 {
 620                         return MemberLookupFinal (ec, t, name, MemberTypes.Method, AllBindingFlags, loc);
 621                 }
 622
 623                 public static Expression MemberLookupFinal (EmitContext ec, Type t, string name,
 624                                                             MemberTypes mt, BindingFlags bf, Location loc)
 625                 {
 626                         Expression e;
 627
 628                         int errors = Report.Errors;
 629
 630                         e = MemberLookup (ec, ec.ContainerType, t, name, mt, bf, loc);
 631
 632                         if (e != null)
 633                                 return e;
 634
 635                         // Error has already been reported.
 636                         if (errors < Report.Errors)
 637                                 return null;
 638
 639                         e = MemberLookup (ec, t, name, AllMemberTypes,
 640                                           AllBindingFlags | BindingFlags.NonPublic, loc);
 641                         if (e == null){
 642                                 Report.Error (
 643                                         117, loc, "`" + t + "' does not contain a definition " +
 644                                         "for `" + name + "'");
 645                         } else {
 646                                 Report.Error (
 647                                         122, loc, "`" + t + "." + name +
 648                                         "' is inaccessible due to its protection level");
 649                         }
 650
 651                         return null;
 652                 }
 653
 654                 static public MemberInfo GetFieldFromEvent (EventExpr event_expr)
 655                 {
 656                         EventInfo ei = event_expr.EventInfo;
 657
 658                         return TypeManager.GetPrivateFieldOfEvent (ei);
 659                 }
 660
 661                 static EmptyExpression MyEmptyExpr;
 662                 static public Expression ImplicitReferenceConversion (Expression expr, Type target_type)
 663                 {
 664                         Type expr_type = expr.Type;
 665
 666                         if (expr_type == null && expr.eclass == ExprClass.MethodGroup){
 667                                 // if we are a method group, emit a warning
 668
 669                                 expr.Emit (null);
 670                         }
 671
 672                         //
 673                         // notice that it is possible to write "ValueType v = 1", the ValueType here
 674                         // is an abstract class, and not really a value type, so we apply the same rules.
 675                         //
 676                         if (target_type == TypeManager.object_type || target_type == TypeManager.value_type) {
 677                                 //
 678                                 // A pointer type cannot be converted to object
 679                                 //
 680                                 if (expr_type.IsPointer)
 681                                         return null;
 682
 683                                 if (expr_type.IsValueType)
 684                                         return new BoxedCast (expr);
 685                                 if (expr_type.IsClass || expr_type.IsInterface)
 686                                         return new EmptyCast (expr, target_type);
 687                         } else if (expr_type.IsSubclassOf (target_type)) {
 688                                 //
 689                                 // Special case: enumeration to System.Enum.
 690                                 // System.Enum is not a value type, it is a class, so we need
 691                                 // a boxing conversion
 692                                 //
 693                                 if (expr_type.IsEnum)
 694                                         return new BoxedCast (expr);
 695
 696                                 return new EmptyCast (expr, target_type);
 697                         } else {
 698
 699                                 // This code is kind of mirrored inside StandardConversionExists
 700                                 // with the small distinction that we only probe there
 701                                 //
 702                                 // Always ensure that the code here and there is in sync
 703
 704                                 // from the null type to any reference-type.
 705                                 if (expr is NullLiteral && !target_type.IsValueType)
 706                                         return new EmptyCast (expr, target_type);
 707
 708                                 // from any class-type S to any interface-type T.
 709                                 if (target_type.IsInterface) {
 710                                         if (TypeManager.ImplementsInterface (expr_type, target_type)){
 711                                                 if (expr_type.IsClass)
 712                                                         return new EmptyCast (expr, target_type);
 713                                                 else if (expr_type.IsValueType)
 714                                                         return new BoxedCast (expr);
 715                                         }
 716                                 }
 717
 718                                 // from any interface type S to interface-type T.
 719                                 if (expr_type.IsInterface && target_type.IsInterface) {
 720                                         if (TypeManager.ImplementsInterface (expr_type, target_type))
 721                                                 return new EmptyCast (expr, target_type);
 722                                         else
 723                                                 return null;
 724                                 }
 725
 726                                 // from an array-type S to an array-type of type T
 727                                 if (expr_type.IsArray && target_type.IsArray) {
 728                                         if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
 729
 730                                                 Type expr_element_type = expr_type.GetElementType ();
 731
 732                                                 if (MyEmptyExpr == null)
 733                                                         MyEmptyExpr = new EmptyExpression ();
 734
 735                                                 MyEmptyExpr.SetType (expr_element_type);
 736                                                 Type target_element_type = target_type.GetElementType ();
 737
 738                                                 if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
 739                                                         if (StandardConversionExists (MyEmptyExpr,
 740                                                                                       target_element_type))
 741                                                                 return new EmptyCast (expr, target_type);
 742                                         }
 743                                 }
 744
 745
 746                                 // from an array-type to System.Array
 747                                 if (expr_type.IsArray && target_type == TypeManager.array_type)
 748                                         return new EmptyCast (expr, target_type);
 749
 750                                 // from any delegate type to System.Delegate
 751                                 if (expr_type.IsSubclassOf (TypeManager.delegate_type) &&
 752                                     target_type == TypeManager.delegate_type)
 753                                         return new EmptyCast (expr, target_type);
 754
 755                                 // from any array-type or delegate type into System.ICloneable.
 756                                 if (expr_type.IsArray || expr_type.IsSubclassOf (TypeManager.delegate_type))
 757                                         if (target_type == TypeManager.icloneable_type)
 758                                                 return new EmptyCast (expr, target_type);
 759
 760                                 return null;
 761
 762                         }
 763
 764                         return null;
 765                 }
 766
 767                 /// <summary>
 768                 ///   Implicit Numeric Conversions.
 769                 ///
 770                 ///   expr is the expression to convert, returns a new expression of type
 771                 ///   target_type or null if an implicit conversion is not possible.
 772                 /// </summary>
 773                 static public Expression ImplicitNumericConversion (EmitContext ec, Expression expr,
 774                                                                     Type target_type, Location loc)
 775                 {
 776                         Type expr_type = expr.Type;
 777
 778                         //
 779                         // Attempt to do the implicit constant expression conversions
 780
 781                         if (expr is IntConstant){
 782                                 Expression e;
 783
 784                                 e = TryImplicitIntConversion (target_type, (IntConstant) expr);
 785
 786                                 if (e != null)
 787                                         return e;
 788                         } else if (expr is LongConstant && target_type == TypeManager.uint64_type){
 789                                 //
 790                                 // Try the implicit constant expression conversion
 791                                 // from long to ulong, instead of a nice routine,
 792                                 // we just inline it
 793                                 //
 794                                 long v = ((LongConstant) expr).Value;
 795                                 if (v > 0)
 796                                         return new ULongConstant ((ulong) v);
 797                         }
 798
 799                         Type real_target_type = target_type;
 800
 801                         if (expr_type == TypeManager.sbyte_type){
 802                                 //
 803                                 // From sbyte to short, int, long, float, double.
 804                                 //
 805                                 if (real_target_type == TypeManager.int32_type)
 806                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 807                                 if (real_target_type == TypeManager.int64_type)
 808                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 809                                 if (real_target_type == TypeManager.double_type)
 810                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 811                                 if (real_target_type == TypeManager.float_type)
 812                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 813                                 if (real_target_type == TypeManager.short_type)
 814                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
 815                         } else if (expr_type == TypeManager.byte_type){
 816                                 //
 817                                 // From byte to short, ushort, int, uint, long, ulong, float, double
 818                                 //
 819                                 if ((real_target_type == TypeManager.short_type) ||
 820                                     (real_target_type == TypeManager.ushort_type) ||
 821                                     (real_target_type == TypeManager.int32_type) ||
 822                                     (real_target_type == TypeManager.uint32_type))
 823                                         return new EmptyCast (expr, target_type);
 824
 825                                 if (real_target_type == TypeManager.uint64_type)
 826                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 827                                 if (real_target_type == TypeManager.int64_type)
 828                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 829                                 if (real_target_type == TypeManager.float_type)
 830                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 831                                 if (real_target_type == TypeManager.double_type)
 832                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 833                         } else if (expr_type == TypeManager.short_type){
 834                                 //
 835                                 // From short to int, long, float, double
 836                                 //
 837                                 if (real_target_type == TypeManager.int32_type)
 838                                         return new EmptyCast (expr, target_type);
 839                                 if (real_target_type == TypeManager.int64_type)
 840                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 841                                 if (real_target_type == TypeManager.double_type)
 842                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 843                                 if (real_target_type == TypeManager.float_type)
 844                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 845                         } else if (expr_type == TypeManager.ushort_type){
 846                                 //
 847                                 // From ushort to int, uint, long, ulong, float, double
 848                                 //
 849                                 if (real_target_type == TypeManager.uint32_type)
 850                                         return new EmptyCast (expr, target_type);
 851
 852                                 if (real_target_type == TypeManager.uint64_type)
 853                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 854                                 if (real_target_type == TypeManager.int32_type)
 855                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 856                                 if (real_target_type == TypeManager.int64_type)
 857                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 858                                 if (real_target_type == TypeManager.double_type)
 859                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 860                                 if (real_target_type == TypeManager.float_type)
 861                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 862                         } else if (expr_type == TypeManager.int32_type){
 863                                 //
 864                                 // From int to long, float, double
 865                                 //
 866                                 if (real_target_type == TypeManager.int64_type)
 867                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 868                                 if (real_target_type == TypeManager.double_type)
 869                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 870                                 if (real_target_type == TypeManager.float_type)
 871                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 872                         } else if (expr_type == TypeManager.uint32_type){
 873                                 //
 874                                 // From uint to long, ulong, float, double
 875                                 //
 876                                 if (real_target_type == TypeManager.int64_type)
 877                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 878                                 if (real_target_type == TypeManager.uint64_type)
 879                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 880                                 if (real_target_type == TypeManager.double_type)
 881                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 882                                                                OpCodes.Conv_R8);
 883                                 if (real_target_type == TypeManager.float_type)
 884                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 885                                                                OpCodes.Conv_R4);
 886                         } else if (expr_type == TypeManager.int64_type){
 887                                 //
 888                                 // From long/ulong to float, double
 889                                 //
 890                                 if (real_target_type == TypeManager.double_type)
 891                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 892                                 if (real_target_type == TypeManager.float_type)
 893                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 894                         } else if (expr_type == TypeManager.uint64_type){
 895                                 //
 896                                 // From ulong to float, double
 897                                 //
 898                                 if (real_target_type == TypeManager.double_type)
 899                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 900                                                                OpCodes.Conv_R8);
 901                                 if (real_target_type == TypeManager.float_type)
 902                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 903                                                                OpCodes.Conv_R4);
 904                         } else if (expr_type == TypeManager.char_type){
 905                                 //
 906                                 // From char to ushort, int, uint, long, ulong, float, double
 907                                 //
 908                                 if ((real_target_type == TypeManager.ushort_type) ||
 909                                     (real_target_type == TypeManager.int32_type) ||
 910                                     (real_target_type == TypeManager.uint32_type))
 911                                         return new EmptyCast (expr, target_type);
 912                                 if (real_target_type == TypeManager.uint64_type)
 913                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 914                                 if (real_target_type == TypeManager.int64_type)
 915                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 916                                 if (real_target_type == TypeManager.float_type)
 917                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 918                                 if (real_target_type == TypeManager.double_type)
 919                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 920                         } else if (expr_type == TypeManager.float_type){
 921                                 //
 922                                 // float to double
 923                                 //
 924                                 if (real_target_type == TypeManager.double_type)
 925                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 926                         }
 927
 928                         return null;
 929                 }
 930
 931                 //
 932                 // Tests whether an implicit reference conversion exists between expr_type
 933                 // and target_type
 934                 //
 935                 public static bool ImplicitReferenceConversionExists (Expression expr, Type target_type)
 936                 {
 937                         Type expr_type = expr.Type;
 938
 939                         //
 940                         // This is the boxed case.
 941                         //
 942                         if (target_type == TypeManager.object_type) {
 943                                 if ((expr_type.IsClass) ||
 944                                     (expr_type.IsValueType) ||
 945                                     (expr_type.IsInterface))
 946                                         return true;
 947
 948                         } else if (expr_type.IsSubclassOf (target_type)) {
 949                                 return true;
 950                         } else {
 951                                 // Please remember that all code below actually comes
 952                                 // from ImplicitReferenceConversion so make sure code remains in sync
 953
 954                                 // from any class-type S to any interface-type T.
 955                                 if (target_type.IsInterface) {
 956                                         if (TypeManager.ImplementsInterface (expr_type, target_type))
 957                                                 return true;
 958                                 }
 959
 960                                 // from any interface type S to interface-type T.
 961                                 if (expr_type.IsInterface && target_type.IsInterface)
 962                                         if (TypeManager.ImplementsInterface (expr_type, target_type))
 963                                                 return true;
 964
 965                                 // from an array-type S to an array-type of type T
 966                                 if (expr_type.IsArray && target_type.IsArray) {
 967                                         if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
 968
 969                                                 Type expr_element_type = expr_type.GetElementType ();
 970
 971                                                 if (MyEmptyExpr == null)
 972                                                         MyEmptyExpr = new EmptyExpression ();
 973
 974                                                 MyEmptyExpr.SetType (expr_element_type);
 975                                                 Type target_element_type = target_type.GetElementType ();
 976
 977                                                 if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
 978                                                         if (StandardConversionExists (MyEmptyExpr,
 979                                                                                       target_element_type))
 980                                                                 return true;
 981                                         }
 982                                 }
 983
 984                                 // from an array-type to System.Array
 985                                 if (expr_type.IsArray && (target_type == TypeManager.array_type))
 986                                         return true;
 987
 988                                 // from any delegate type to System.Delegate
 989                                 if (expr_type.IsSubclassOf (TypeManager.delegate_type) &&
 990                                     target_type == TypeManager.delegate_type)
 991                                         if (target_type.IsAssignableFrom (expr_type))
 992                                                 return true;
 993
 994                                 // from any array-type or delegate type into System.ICloneable.
 995                                 if (expr_type.IsArray || expr_type.IsSubclassOf (TypeManager.delegate_type))
 996                                         if (target_type == TypeManager.icloneable_type)
 997                                                 return true;
 998
 999                                 // from the null type to any reference-type.
1000                                 if (expr is NullLiteral && !target_type.IsValueType &&
1001                                     !TypeManager.IsEnumType (target_type))
1002                                         return true;
1003
1004                         }
1005
1006                         return false;
1007                 }
1008
1009                 /// <summary>
1010                 ///  Same as StandardConversionExists except that it also looks at
1011                 ///  implicit user defined conversions - needed for overload resolution
1012                 /// </summary>
1013                 public static bool ImplicitConversionExists (EmitContext ec, Expression expr, Type target_type)
1014                 {
1015                         if (StandardConversionExists (expr, target_type) == true)
1016                                 return true;
1017
1018                         Expression dummy = ImplicitUserConversion (ec, expr, target_type, Location.Null);
1019
1020                         if (dummy != null)
1021                                 return true;
1022
1023                         return false;
1024                 }
1025
1026                 /// <summary>
1027                 ///  Determines if a standard implicit conversion exists from
1028                 ///  expr_type to target_type
1029                 /// </summary>
1030                 public static bool StandardConversionExists (Expression expr, Type target_type)
1031                 {
1032                         Type expr_type = expr.Type;
1033
1034                         if (expr_type == TypeManager.void_type)
1035                                 return false;
1036
1037                         if (expr_type == target_type)
1038                                 return true;
1039
1040                         // First numeric conversions
1041
1042                         if (expr_type == TypeManager.sbyte_type){
1043                                 //
1044                                 // From sbyte to short, int, long, float, double.
1045                                 //
1046                                 if ((target_type == TypeManager.int32_type) ||
1047                                     (target_type == TypeManager.int64_type) ||
1048                                     (target_type == TypeManager.double_type) ||
1049                                     (target_type == TypeManager.float_type)  ||
1050                                     (target_type == TypeManager.short_type) ||
1051                                     (target_type == TypeManager.decimal_type))
1052                                         return true;
1053
1054                         } else if (expr_type == TypeManager.byte_type){
1055                                 //
1056                                 // From byte to short, ushort, int, uint, long, ulong, float, double
1057                                 //
1058                                 if ((target_type == TypeManager.short_type) ||
1059                                     (target_type == TypeManager.ushort_type) ||
1060                                     (target_type == TypeManager.int32_type) ||
1061                                     (target_type == TypeManager.uint32_type) ||
1062                                     (target_type == TypeManager.uint64_type) ||
1063                                     (target_type == TypeManager.int64_type) ||
1064                                     (target_type == TypeManager.float_type) ||
1065                                     (target_type == TypeManager.double_type) ||
1066                                     (target_type == TypeManager.decimal_type))
1067                                         return true;
1068
1069                         } else if (expr_type == TypeManager.short_type){
1070                                 //
1071                                 // From short to int, long, float, double
1072                                 //
1073                                 if ((target_type == TypeManager.int32_type) ||
1074                                     (target_type == TypeManager.int64_type) ||
1075                                     (target_type == TypeManager.double_type) ||
1076                                     (target_type == TypeManager.float_type) ||
1077                                     (target_type == TypeManager.decimal_type))
1078                                         return true;
1079
1080                         } else if (expr_type == TypeManager.ushort_type){
1081                                 //
1082                                 // From ushort to int, uint, long, ulong, float, double
1083                                 //
1084                                 if ((target_type == TypeManager.uint32_type) ||
1085                                     (target_type == TypeManager.uint64_type) ||
1086                                     (target_type == TypeManager.int32_type) ||
1087                                     (target_type == TypeManager.int64_type) ||
1088                                     (target_type == TypeManager.double_type) ||
1089                                     (target_type == TypeManager.float_type) ||
1090                                     (target_type == TypeManager.decimal_type))
1091                                         return true;
1092
1093                         } else if (expr_type == TypeManager.int32_type){
1094                                 //
1095                                 // From int to long, float, double
1096                                 //
1097                                 if ((target_type == TypeManager.int64_type) ||
1098                                     (target_type == TypeManager.double_type) ||
1099                                     (target_type == TypeManager.float_type) ||
1100                                     (target_type == TypeManager.decimal_type))
1101                                         return true;
1102
1103                         } else if (expr_type == TypeManager.uint32_type){
1104                                 //
1105                                 // From uint to long, ulong, float, double
1106                                 //
1107                                 if ((target_type == TypeManager.int64_type) ||
1108                                     (target_type == TypeManager.uint64_type) ||
1109                                     (target_type == TypeManager.double_type) ||
1110                                     (target_type == TypeManager.float_type) ||
1111                                     (target_type == TypeManager.decimal_type))
1112                                         return true;
1113
1114                         } else if ((expr_type == TypeManager.uint64_type) ||
1115                                    (expr_type == TypeManager.int64_type)) {
1116                                 //
1117                                 // From long/ulong to float, double
1118                                 //
1119                                 if ((target_type == TypeManager.double_type) ||
1120                                     (target_type == TypeManager.float_type) ||
1121                                     (target_type == TypeManager.decimal_type))
1122                                         return true;
1123
1124                         } else if (expr_type == TypeManager.char_type){
1125                                 //
1126                                 // From char to ushort, int, uint, long, ulong, float, double
1127                                 //
1128                                 if ((target_type == TypeManager.ushort_type) ||
1129                                     (target_type == TypeManager.int32_type) ||
1130                                     (target_type == TypeManager.uint32_type) ||
1131                                     (target_type == TypeManager.uint64_type) ||
1132                                     (target_type == TypeManager.int64_type) ||
1133                                     (target_type == TypeManager.float_type) ||
1134                                     (target_type == TypeManager.double_type) ||
1135                                     (target_type == TypeManager.decimal_type))
1136                                         return true;
1137
1138                         } else if (expr_type == TypeManager.float_type){
1139                                 //
1140                                 // float to double
1141                                 //
1142                                 if (target_type == TypeManager.double_type)
1143                                         return true;
1144                         }
1145
1146                         if (ImplicitReferenceConversionExists (expr, target_type))
1147                                 return true;
1148
1149                         if (expr is IntConstant){
1150                                 int value = ((IntConstant) expr).Value;
1151
1152                                 if (target_type == TypeManager.sbyte_type){
1153                                         if (value >= SByte.MinValue && value <= SByte.MaxValue)
1154                                                 return true;
1155                                 } else if (target_type == TypeManager.byte_type){
1156                                         if (Byte.MinValue >= 0 && value <= Byte.MaxValue)
1157                                                 return true;
1158                                 } else if (target_type == TypeManager.short_type){
1159                                         if (value >= Int16.MinValue && value <= Int16.MaxValue)
1160                                                 return true;
1161                                 } else if (target_type == TypeManager.ushort_type){
1162                                         if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
1163                                                 return true;
1164                                 } else if (target_type == TypeManager.uint32_type){
1165                                         if (value >= 0)
1166                                                 return true;
1167                                 } else if (target_type == TypeManager.uint64_type){
1168                                          //
1169                                          // we can optimize this case: a positive int32
1170                                          // always fits on a uint64.  But we need an opcode
1171                                          // to do it.
1172                                          //
1173                                         if (value >= 0)
1174                                                 return true;
1175                                 }
1176
1177                                 if (value == 0 && expr is IntLiteral && TypeManager.IsEnumType (target_type))
1178                                         return true;
1179                         }
1180
1181                         if (expr is LongConstant && target_type == TypeManager.uint64_type){
1182                                 //
1183                                 // Try the implicit constant expression conversion
1184                                 // from long to ulong, instead of a nice routine,
1185                                 // we just inline it
1186                                 //
1187                                 long v = ((LongConstant) expr).Value;
1188                                 if (v > 0)
1189                                         return true;
1190                         }
1191
1192                         if (target_type.IsSubclassOf (TypeManager.enum_type) && expr is IntLiteral){
1193                                 IntLiteral i = (IntLiteral) expr;
1194
1195                                 if (i.Value == 0)
1196                                         return true;
1197                         }
1198
1199                         if (target_type == TypeManager.void_ptr_type && expr_type.IsPointer)
1200                                 return true;
1201
1202                         return false;
1203                 }
1204
1205                 //
1206                 // Used internally by FindMostEncompassedType, this is used
1207                 // to avoid creating lots of objects in the tight loop inside
1208                 // FindMostEncompassedType
1209                 //
1210                 static EmptyExpression priv_fmet_param;
1211
1212                 /// <summary>
1213                 ///  Finds "most encompassed type" according to the spec (13.4.2)
1214                 ///  amongst the methods in the MethodGroupExpr
1215                 /// </summary>
1216                 static Type FindMostEncompassedType (ArrayList types)
1217                 {
1218                         Type best = null;
1219
1220                         if (priv_fmet_param == null)
1221                                 priv_fmet_param = new EmptyExpression ();
1222
1223                         foreach (Type t in types){
1224                                 priv_fmet_param.SetType (t);
1225
1226                                 if (best == null) {
1227                                         best = t;
1228                                         continue;
1229                                 }
1230
1231                                 if (StandardConversionExists (priv_fmet_param, best))
1232                                         best = t;
1233                         }
1234
1235                         return best;
1236                 }
1237
1238                 //
1239                 // Used internally by FindMostEncompassingType, this is used
1240                 // to avoid creating lots of objects in the tight loop inside
1241                 // FindMostEncompassingType
1242                 //
1243                 static EmptyExpression priv_fmee_ret;
1244
1245                 /// <summary>
1246                 ///  Finds "most encompassing type" according to the spec (13.4.2)
1247                 ///  amongst the types in the given set
1248                 /// </summary>
1249                 static Type FindMostEncompassingType (ArrayList types)
1250                 {
1251                         Type best = null;
1252
1253                         if (priv_fmee_ret == null)
1254                                 priv_fmee_ret = new EmptyExpression ();
1255
1256                         foreach (Type t in types){
1257                                 priv_fmee_ret.SetType (best);
1258
1259                                 if (best == null) {
1260                                         best = t;
1261                                         continue;
1262                                 }
1263
1264                                 if (StandardConversionExists (priv_fmee_ret, t))
1265                                         best = t;
1266                         }
1267
1268                         return best;
1269                 }
1270
1271                 //
1272                 // Used to avoid creating too many objects
1273                 //
1274                 static EmptyExpression priv_fms_expr;
1275
1276                 /// <summary>
1277                 ///   Finds the most specific source Sx according to the rules of the spec (13.4.4)
1278                 ///   by making use of FindMostEncomp* methods. Applies the correct rules separately
1279                 ///   for explicit and implicit conversion operators.
1280                 /// </summary>
1281                 static public Type FindMostSpecificSource (MethodGroupExpr me, Expression source,
1282                                                            bool apply_explicit_conv_rules,
1283                                                            Location loc)
1284                 {
1285                         ArrayList src_types_set = new ArrayList ();
1286
1287                         if (priv_fms_expr == null)
1288                                 priv_fms_expr = new EmptyExpression ();
1289
1290                         //
1291                         // If any operator converts from S then Sx = S
1292                         //
1293                         Type source_type = source.Type;
1294                         foreach (MethodBase mb in me.Methods){
1295                                 ParameterData pd = Invocation.GetParameterData (mb);
1296                                 Type param_type = pd.ParameterType (0);
1297
1298                                 if (param_type == source_type)
1299                                         return param_type;
1300
1301                                 if (apply_explicit_conv_rules) {
1302                                         //
1303                                         // From the spec :
1304                                         // Find the set of applicable user-defined conversion operators, U.  This set
1305                                         // consists of the
1306                                         // user-defined implicit or explicit conversion operators declared by
1307                                         // the classes or structs in D that convert from a type encompassing
1308                                         // or encompassed by S to a type encompassing or encompassed by T
1309                                         //
1310                                         priv_fms_expr.SetType (param_type);
1311                                         if (StandardConversionExists (priv_fms_expr, source_type))
1312                                                 src_types_set.Add (param_type);
1313                                         else {
1314                                                 if (StandardConversionExists (source, param_type))
1315                                                         src_types_set.Add (param_type);
1316                                         }
1317                                 } else {
1318                                         //
1319                                         // Only if S is encompassed by param_type
1320                                         //
1321                                         if (StandardConversionExists (source, param_type))
1322                                                 src_types_set.Add (param_type);
1323                                 }
1324                         }
1325
1326                         //
1327                         // Explicit Conv rules
1328                         //
1329                         if (apply_explicit_conv_rules) {
1330                                 ArrayList candidate_set = new ArrayList ();
1331
1332                                 foreach (Type param_type in src_types_set){
1333                                         if (StandardConversionExists (source, param_type))
1334                                                 candidate_set.Add (param_type);
1335                                 }
1336
1337                                 if (candidate_set.Count != 0)
1338                                         return FindMostEncompassedType (candidate_set);
1339                         }
1340
1341                         //
1342                         // Final case
1343                         //
1344                         if (apply_explicit_conv_rules)
1345                                 return FindMostEncompassingType (src_types_set);
1346                         else
1347                                 return FindMostEncompassedType (src_types_set);
1348                 }
1349
1350                 //
1351                 // Useful in avoiding proliferation of objects
1352                 //
1353                 static EmptyExpression priv_fmt_expr;
1354
1355                 /// <summary>
1356                 ///  Finds the most specific target Tx according to section 13.4.4
1357                 /// </summary>
1358                 static public Type FindMostSpecificTarget (MethodGroupExpr me, Type target,
1359                                                            bool apply_explicit_conv_rules,
1360                                                            Location loc)
1361                 {
1362                         ArrayList tgt_types_set = new ArrayList ();
1363
1364                         if (priv_fmt_expr == null)
1365                                 priv_fmt_expr = new EmptyExpression ();
1366
1367                         //
1368                         // If any operator converts to T then Tx = T
1369                         //
1370                         foreach (MethodInfo mi in me.Methods){
1371                                 Type ret_type = mi.ReturnType;
1372
1373                                 if (ret_type == target)
1374                                         return ret_type;
1375
1376                                 if (apply_explicit_conv_rules) {
1377                                         //
1378                                         // From the spec :
1379                                         // Find the set of applicable user-defined conversion operators, U.
1380                                         //
1381                                         // This set consists of the
1382                                         // user-defined implicit or explicit conversion operators declared by
1383                                         // the classes or structs in D that convert from a type encompassing
1384                                         // or encompassed by S to a type encompassing or encompassed by T
1385                                         //
1386                                         priv_fms_expr.SetType (ret_type);
1387                                         if (StandardConversionExists (priv_fms_expr, target))
1388                                                 tgt_types_set.Add (ret_type);
1389                                         else {
1390                                                 priv_fms_expr.SetType (target);
1391                                                 if (StandardConversionExists (priv_fms_expr, ret_type))
1392                                                         tgt_types_set.Add (ret_type);
1393                                         }
1394                                 } else {
1395                                         //
1396                                         // Only if T is encompassed by param_type
1397                                         //
1398                                         priv_fms_expr.SetType (ret_type);
1399                                         if (StandardConversionExists (priv_fms_expr, target))
1400                                                 tgt_types_set.Add (ret_type);
1401                                 }
1402                         }
1403
1404                         //
1405                         // Explicit conv rules
1406                         //
1407                         if (apply_explicit_conv_rules) {
1408                                 ArrayList candidate_set = new ArrayList ();
1409
1410                                 foreach (Type ret_type in tgt_types_set){
1411                                         priv_fmt_expr.SetType (ret_type);
1412
1413                                         if (StandardConversionExists (priv_fmt_expr, target))
1414                                                 candidate_set.Add (ret_type);
1415                                 }
1416
1417                                 if (candidate_set.Count != 0)
1418                                         return FindMostEncompassingType (candidate_set);
1419                         }
1420
1421                         //
1422                         // Okay, final case !
1423                         //
1424                         if (apply_explicit_conv_rules)
1425                                 return FindMostEncompassedType (tgt_types_set);
1426                         else
1427                                 return FindMostEncompassingType (tgt_types_set);
1428                 }
1429
1430                 /// <summary>
1431                 ///  User-defined Implicit conversions
1432                 /// </summary>
1433                 static public Expression ImplicitUserConversion (EmitContext ec, Expression source,
1434                                                                  Type target, Location loc)
1435                 {
1436                         return UserDefinedConversion (ec, source, target, loc, false);
1437                 }
1438
1439                 /// <summary>
1440                 ///  User-defined Explicit conversions
1441                 /// </summary>
1442                 static public Expression ExplicitUserConversion (EmitContext ec, Expression source,
1443                                                                  Type target, Location loc)
1444                 {
1445                         return UserDefinedConversion (ec, source, target, loc, true);
1446                 }
1447
1448                 /// <summary>
1449                 ///   Computes the MethodGroup for the user-defined conversion
1450                 ///   operators from source_type to target_type.  `look_for_explicit'
1451                 ///   controls whether we should also include the list of explicit
1452                 ///   operators
1453                 /// </summary>
1454                 static MethodGroupExpr GetConversionOperators (EmitContext ec,
1455                                                                Type source_type, Type target_type,
1456                                                                Location loc, bool look_for_explicit)
1457                 {
1458                         Expression mg1 = null, mg2 = null;
1459                         Expression mg5 = null, mg6 = null, mg7 = null, mg8 = null;
1460                         string op_name;
1461
1462                         //
1463                         // FIXME : How does the False operator come into the picture ?
1464                         // This doesn't look complete and very correct !
1465                         //
1466                         if (target_type == TypeManager.bool_type && !look_for_explicit)
1467                                 op_name = "op_True";
1468                         else
1469                                 op_name = "op_Implicit";
1470
1471                         MethodGroupExpr union3;
1472
1473                         mg1 = MethodLookup (ec, source_type, op_name, loc);
1474                         if (source_type.BaseType != null)
1475                                 mg2 = MethodLookup (ec, source_type.BaseType, op_name, loc);
1476
1477                         if (mg1 == null)
1478                                 union3 = (MethodGroupExpr) mg2;
1479                         else if (mg2 == null)
1480                                 union3 = (MethodGroupExpr) mg1;
1481                         else
1482                                 union3 = Invocation.MakeUnionSet (mg1, mg2, loc);
1483
1484                         mg1 = MethodLookup (ec, target_type, op_name, loc);
1485                         if (mg1 != null){
1486                                 if (union3 != null)
1487                                         union3 = Invocation.MakeUnionSet (union3, mg1, loc);
1488                                 else
1489                                         union3 = (MethodGroupExpr) mg1;
1490                         }
1491
1492                         if (target_type.BaseType != null)
1493                                 mg1 = MethodLookup (ec, target_type.BaseType, op_name, loc);
1494
1495                         if (mg1 != null){
1496                                 if (union3 != null)
1497                                         union3 = Invocation.MakeUnionSet (union3, mg1, loc);
1498                                 else
1499                                         union3 = (MethodGroupExpr) mg1;
1500                         }
1501
1502                         MethodGroupExpr union4 = null;
1503
1504                         if (look_for_explicit) {
1505                                 op_name = "op_Explicit";
1506
1507                                 mg5 = MemberLookup (ec, source_type, op_name, loc);
1508                                 if (source_type.BaseType != null)
1509                                         mg6 = MethodLookup (ec, source_type.BaseType, op_name, loc);
1510
1511                                 mg7 = MemberLookup (ec, target_type, op_name, loc);
1512                                 if (target_type.BaseType != null)
1513                                         mg8 = MethodLookup (ec, target_type.BaseType, op_name, loc);
1514
1515                                 MethodGroupExpr union5 = Invocation.MakeUnionSet (mg5, mg6, loc);
1516                                 MethodGroupExpr union6 = Invocation.MakeUnionSet (mg7, mg8, loc);
1517
1518                                 union4 = Invocation.MakeUnionSet (union5, union6, loc);
1519                         }
1520
1521                         return Invocation.MakeUnionSet (union3, union4, loc);
1522                 }
1523
1524                 /// <summary>
1525                 ///   User-defined conversions
1526                 /// </summary>
1527                 static public Expression UserDefinedConversion (EmitContext ec, Expression source,
1528                                                                 Type target, Location loc,
1529                                                                 bool look_for_explicit)
1530                 {
1531                         MethodGroupExpr union;
1532                         Type source_type = source.Type;
1533                         MethodBase method = null;
1534
1535                         union = GetConversionOperators (ec, source_type, target, loc, look_for_explicit);
1536                         if (union == null)
1537                                 return null;
1538
1539                         Type most_specific_source, most_specific_target;
1540
1541 #if BLAH
1542                         foreach (MethodBase m in union.Methods){
1543                                 Console.WriteLine ("Name: " + m.Name);
1544                                 Console.WriteLine ("    : " + ((MethodInfo)m).ReturnType);
1545                         }
1546 #endif
1547
1548                         most_specific_source = FindMostSpecificSource (union, source, look_for_explicit, loc);
1549                         if (most_specific_source == null)
1550                                 return null;
1551
1552                         most_specific_target = FindMostSpecificTarget (union, target, look_for_explicit, loc);
1553                         if (most_specific_target == null)
1554                                 return null;
1555
1556                         int count = 0;
1557
1558                         foreach (MethodBase mb in union.Methods){
1559                                 ParameterData pd = Invocation.GetParameterData (mb);
1560                                 MethodInfo mi = (MethodInfo) mb;
1561
1562                                 if (pd.ParameterType (0) == most_specific_source &&
1563                                     mi.ReturnType == most_specific_target) {
1564                                         method = mb;
1565                                         count++;
1566                                 }
1567                         }
1568
1569                         if (method == null || count > 1)
1570                                 return null;
1571
1572
1573                         //
1574                         // This will do the conversion to the best match that we
1575                         // found.  Now we need to perform an implict standard conversion
1576                         // if the best match was not the type that we were requested
1577                         // by target.
1578                         //
1579                         if (look_for_explicit)
1580                                 source = ConvertExplicitStandard (ec, source, most_specific_source, loc);
1581                         else
1582                                 source = ConvertImplicitStandard (ec, source, most_specific_source, loc);
1583
1584                         if (source == null)
1585                                 return null;
1586
1587                         Expression e;
1588                         e =  new UserCast ((MethodInfo) method, source, loc);
1589                         if (e.Type != target){
1590                                 if (!look_for_explicit)
1591                                         e = ConvertImplicitStandard (ec, e, target, loc);
1592                                 else
1593                                         e = ConvertExplicitStandard (ec, e, target, loc);
1594                         }
1595                         return e;
1596                 }
1597
1598                 /// <summary>
1599                 ///   Converts implicitly the resolved expression `expr' into the
1600                 ///   `target_type'.  It returns a new expression that can be used
1601                 ///   in a context that expects a `target_type'.
1602                 /// </summary>
1603                 static public Expression ConvertImplicit (EmitContext ec, Expression expr,
1604                                                           Type target_type, Location loc)
1605                 {
1606                         Type expr_type = expr.Type;
1607                         Expression e;
1608
1609                         if (expr_type == target_type)
1610                                 return expr;
1611
1612                         if (target_type == null)
1613                                 throw new Exception ("Target type is null");
1614
1615                         e = ConvertImplicitStandard (ec, expr, target_type, loc);
1616                         if (e != null)
1617                                 return e;
1618
1619                         e = ImplicitUserConversion (ec, expr, target_type, loc);
1620                         if (e != null)
1621                                 return e;
1622
1623                         return null;
1624                 }
1625
1626
1627                 /// <summary>
1628                 ///   Attempts to apply the `Standard Implicit
1629                 ///   Conversion' rules to the expression `expr' into
1630                 ///   the `target_type'.  It returns a new expression
1631                 ///   that can be used in a context that expects a
1632                 ///   `target_type'.
1633                 ///
1634                 ///   This is different from `ConvertImplicit' in that the
1635                 ///   user defined implicit conversions are excluded.
1636                 /// </summary>
1637                 static public Expression ConvertImplicitStandard (EmitContext ec, Expression expr,
1638                                                                   Type target_type, Location loc)
1639                 {
1640                         Type expr_type = expr.Type;
1641                         Expression e;
1642
1643                         if (expr_type == target_type)
1644                                 return expr;
1645
1646                         e = ImplicitNumericConversion (ec, expr, target_type, loc);
1647                         if (e != null)
1648                                 return e;
1649
1650                         e = ImplicitReferenceConversion (expr, target_type);
1651                         if (e != null)
1652                                 return e;
1653
1654                         if (target_type.IsSubclassOf (TypeManager.enum_type) && expr is IntLiteral){
1655                                 IntLiteral i = (IntLiteral) expr;
1656
1657                                 if (i.Value == 0)
1658                                         return new EmptyCast (expr, target_type);
1659                         }
1660
1661                         if (ec.InUnsafe) {
1662                                 if (expr_type.IsPointer){
1663                                         if (target_type == TypeManager.void_ptr_type)
1664                                                 return new EmptyCast (expr, target_type);
1665
1666                                         //
1667                                         // yep, comparing pointer types cant be done with
1668                                         // t1 == t2, we have to compare their element types.
1669                                         //
1670                                         if (target_type.IsPointer){
1671                                                 if (target_type.GetElementType()==expr_type.GetElementType())
1672                                                         return expr;
1673                                         }
1674                                 }
1675
1676                                 if (target_type.IsPointer){
1677                                         if (expr is NullLiteral)
1678                                                 return new EmptyCast (expr, target_type);
1679                                 }
1680                         }
1681
1682                         return null;
1683                 }
1684
1685                 /// <summary>
1686                 ///   Attemps to perform an implict constant conversion of the IntConstant
1687                 ///   into a different data type using casts (See Implicit Constant
1688                 ///   Expression Conversions)
1689                 /// </summary>
1690                 static protected Expression TryImplicitIntConversion (Type target_type, IntConstant ic)
1691                 {
1692                         int value = ic.Value;
1693
1694                         //
1695                         // FIXME: This could return constants instead of EmptyCasts
1696                         //
1697                         if (target_type == TypeManager.sbyte_type){
1698                                 if (value >= SByte.MinValue && value <= SByte.MaxValue)
1699                                         return new SByteConstant ((sbyte) value);
1700                         } else if (target_type == TypeManager.byte_type){
1701                                 if (Byte.MinValue >= 0 && value <= Byte.MaxValue)
1702                                         return new ByteConstant ((byte) value);
1703                         } else if (target_type == TypeManager.short_type){
1704                                 if (value >= Int16.MinValue && value <= Int16.MaxValue)
1705                                         return new ShortConstant ((short) value);
1706                         } else if (target_type == TypeManager.ushort_type){
1707                                 if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
1708                                         return new UShortConstant ((ushort) value);
1709                         } else if (target_type == TypeManager.uint32_type){
1710                                 if (value >= 0)
1711                                         return new UIntConstant ((uint) value);
1712                         } else if (target_type == TypeManager.uint64_type){
1713                                 //
1714                                 // we can optimize this case: a positive int32
1715                                 // always fits on a uint64.  But we need an opcode
1716                                 // to do it.
1717                                 //
1718                                 if (value >= 0)
1719                                         return new ULongConstant ((ulong) value);
1720                         }
1721
1722                         if (value == 0 && ic is IntLiteral && TypeManager.IsEnumType (target_type)){
1723                                 Type underlying = TypeManager.EnumToUnderlying (target_type);
1724                                 Constant e = (Constant) ic;
1725
1726                                 //
1727                                 // Possibly, we need to create a different 0 literal before passing
1728                                 // to EnumConstant
1729                                 //n
1730                                 if (underlying == TypeManager.int64_type)
1731                                         e = new LongLiteral (0);
1732                                 else if (underlying == TypeManager.uint64_type)
1733                                         e = new ULongLiteral (0);
1734
1735                                 return new EnumConstant (e, target_type);
1736                         }
1737                         return null;
1738                 }
1739
1740                 static public void Error_CannotConvertImplicit (Location loc, Type source, Type target)
1741                 {
1742                         string msg = "Cannot convert implicitly from `"+
1743                                 TypeManager.CSharpName (source) + "' to `" +
1744                                 TypeManager.CSharpName (target) + "'";
1745
1746                         Report.Error (29, loc, msg);
1747                 }
1748
1749                 /// <summary>
1750                 ///   Attemptes to implicityly convert `target' into `type', using
1751                 ///   ConvertImplicit.  If there is no implicit conversion, then
1752                 ///   an error is signaled
1753                 /// </summary>
1754                 static public Expression ConvertImplicitRequired (EmitContext ec, Expression source,
1755                                                                   Type target_type, Location loc)
1756                 {
1757                         Expression e;
1758
1759                         e = ConvertImplicit (ec, source, target_type, loc);
1760                         if (e != null)
1761                                 return e;
1762
1763                         if (source is DoubleLiteral && target_type == TypeManager.float_type){
1764                                 Report.Error (664, loc,
1765                                               "Double literal cannot be implicitly converted to " +
1766                                               "float type, use F suffix to create a float literal");
1767                         }
1768
1769                         Error_CannotConvertImplicit (loc, source.Type, target_type);
1770
1771                         return null;
1772                 }
1773
1774                 /// <summary>
1775                 ///   Performs the explicit numeric conversions
1776                 /// </summary>
1777                 static Expression ConvertNumericExplicit (EmitContext ec, Expression expr, Type target_type, Location loc)
1778                 {
1779                         Type expr_type = expr.Type;
1780
1781                         //
1782                         // If we have an enumeration, extract the underlying type,
1783                         // use this during the comparison, but wrap around the original
1784                         // target_type
1785                         //
1786                         Type real_target_type = target_type;
1787
1788                         if (TypeManager.IsEnumType (real_target_type))
1789                                 real_target_type = TypeManager.EnumToUnderlying (real_target_type);
1790
1791                         if (StandardConversionExists (expr, real_target_type)){
1792                                 Expression ce = ConvertImplicitStandard (ec, expr, real_target_type, loc);
1793
1794                                 if (real_target_type != target_type)
1795                                         return new EmptyCast (ce, target_type);
1796                                 return ce;
1797                         }
1798
1799                         if (expr_type == TypeManager.sbyte_type){
1800                                 //
1801                                 // From sbyte to byte, ushort, uint, ulong, char
1802                                 //
1803                                 if (real_target_type == TypeManager.byte_type)
1804                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U1);
1805                                 if (real_target_type == TypeManager.ushort_type)
1806                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U2);
1807                                 if (real_target_type == TypeManager.uint32_type)
1808                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U4);
1809                                 if (real_target_type == TypeManager.uint64_type)
1810                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U8);
1811                                 if (real_target_type == TypeManager.char_type)
1812                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_CH);
1813                         } else if (expr_type == TypeManager.byte_type){
1814                                 //
1815                                 // From byte to sbyte and char
1816                                 //
1817                                 if (real_target_type == TypeManager.sbyte_type)
1818                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U1_I1);
1819                                 if (real_target_type == TypeManager.char_type)
1820                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U1_CH);
1821                         } else if (expr_type == TypeManager.short_type){
1822                                 //
1823                                 // From short to sbyte, byte, ushort, uint, ulong, char
1824                                 //
1825                                 if (real_target_type == TypeManager.sbyte_type)
1826                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_I1);
1827                                 if (real_target_type == TypeManager.byte_type)
1828                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U1);
1829                                 if (real_target_type == TypeManager.ushort_type)
1830                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U2);
1831                                 if (real_target_type == TypeManager.uint32_type)
1832                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U4);
1833                                 if (real_target_type == TypeManager.uint64_type)
1834                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U8);
1835                                 if (real_target_type == TypeManager.char_type)
1836                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_CH);
1837                         } else if (expr_type == TypeManager.ushort_type){
1838                                 //
1839                                 // From ushort to sbyte, byte, short, char
1840                                 //
1841                                 if (real_target_type == TypeManager.sbyte_type)
1842                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_I1);
1843                                 if (real_target_type == TypeManager.byte_type)
1844                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_U1);
1845                                 if (real_target_type == TypeManager.short_type)
1846                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_I2);
1847                                 if (real_target_type == TypeManager.char_type)
1848                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_CH);
1849                         } else if (expr_type == TypeManager.int32_type){
1850                                 //
1851                                 // From int to sbyte, byte, short, ushort, uint, ulong, char
1852                                 //
1853                                 if (real_target_type == TypeManager.sbyte_type)
1854                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_I1);
1855                                 if (real_target_type == TypeManager.byte_type)
1856                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U1);
1857                                 if (real_target_type == TypeManager.short_type)
1858                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_I2);
1859                                 if (real_target_type == TypeManager.ushort_type)
1860                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U2);
1861                                 if (real_target_type == TypeManager.uint32_type)
1862                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U4);
1863                                 if (real_target_type == TypeManager.uint64_type)
1864                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U8);
1865                                 if (real_target_type == TypeManager.char_type)
1866                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_CH);
1867                         } else if (expr_type == TypeManager.uint32_type){
1868                                 //
1869                                 // From uint to sbyte, byte, short, ushort, int, char
1870                                 //
1871                                 if (real_target_type == TypeManager.sbyte_type)
1872                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_I1);
1873                                 if (real_target_type == TypeManager.byte_type)
1874                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_U1);
1875                                 if (real_target_type == TypeManager.short_type)
1876                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_I2);
1877                                 if (real_target_type == TypeManager.ushort_type)
1878                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_U2);
1879                                 if (real_target_type == TypeManager.int32_type)
1880                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_I4);
1881                                 if (real_target_type == TypeManager.char_type)
1882                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_CH);
1883                         } else if (expr_type == TypeManager.int64_type){
1884                                 //
1885                                 // From long to sbyte, byte, short, ushort, int, uint, ulong, char
1886                                 //
1887                                 if (real_target_type == TypeManager.sbyte_type)
1888                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I1);
1889                                 if (real_target_type == TypeManager.byte_type)
1890                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U1);
1891                                 if (real_target_type == TypeManager.short_type)
1892                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I2);
1893                                 if (real_target_type == TypeManager.ushort_type)
1894                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U2);
1895                                 if (real_target_type == TypeManager.int32_type)
1896                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I4);
1897                                 if (real_target_type == TypeManager.uint32_type)
1898                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U4);
1899                                 if (real_target_type == TypeManager.uint64_type)
1900                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U8);
1901                                 if (real_target_type == TypeManager.char_type)
1902                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_CH);
1903                         } else if (expr_type == TypeManager.uint64_type){
1904                                 //
1905                                 // From ulong to sbyte, byte, short, ushort, int, uint, long, char
1906                                 //
1907                                 if (real_target_type == TypeManager.sbyte_type)
1908                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I1);
1909                                 if (real_target_type == TypeManager.byte_type)
1910                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U1);
1911                                 if (real_target_type == TypeManager.short_type)
1912                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I2);
1913                                 if (real_target_type == TypeManager.ushort_type)
1914                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U2);
1915                                 if (real_target_type == TypeManager.int32_type)
1916                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I4);
1917                                 if (real_target_type == TypeManager.uint32_type)
1918                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U4);
1919                                 if (real_target_type == TypeManager.int64_type)
1920                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I8);
1921                                 if (real_target_type == TypeManager.char_type)
1922                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_CH);
1923                         } else if (expr_type == TypeManager.char_type){
1924                                 //
1925                                 // From char to sbyte, byte, short
1926                                 //
1927                                 if (real_target_type == TypeManager.sbyte_type)
1928                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.CH_I1);
1929                                 if (real_target_type == TypeManager.byte_type)
1930                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.CH_U1);
1931                                 if (real_target_type == TypeManager.short_type)
1932                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.CH_I2);
1933                         } else if (expr_type == TypeManager.float_type){
1934                                 //
1935                                 // From float to sbyte, byte, short,
1936                                 // ushort, int, uint, long, ulong, char
1937                                 // or decimal
1938                                 //
1939                                 if (real_target_type == TypeManager.sbyte_type)
1940                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_I1);
1941                                 if (real_target_type == TypeManager.byte_type)
1942                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_U1);
1943                                 if (real_target_type == TypeManager.short_type)
1944                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_I2);
1945                                 if (real_target_type == TypeManager.ushort_type)
1946                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_U2);
1947                                 if (real_target_type == TypeManager.int32_type)
1948                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_I4);
1949                                 if (real_target_type == TypeManager.uint32_type)
1950                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_U4);
1951                                 if (real_target_type == TypeManager.int64_type)
1952                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_I8);
1953                                 if (real_target_type == TypeManager.uint64_type)
1954                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_U8);
1955                                 if (real_target_type == TypeManager.char_type)
1956                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_CH);
1957                         } else if (expr_type == TypeManager.double_type){
1958                                 //
1959                                 // From double to byte, byte, short,
1960                                 // ushort, int, uint, long, ulong,
1961                                 // char, float or decimal
1962                                 //
1963                                 if (real_target_type == TypeManager.sbyte_type)
1964                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_I1);
1965                                 if (real_target_type == TypeManager.byte_type)
1966                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_U1);
1967                                 if (real_target_type == TypeManager.short_type)
1968                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_I2);
1969                                 if (real_target_type == TypeManager.ushort_type)
1970                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_U2);
1971                                 if (real_target_type == TypeManager.int32_type)
1972                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_I4);
1973                                 if (real_target_type == TypeManager.uint32_type)
1974                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_U4);
1975                                 if (real_target_type == TypeManager.int64_type)
1976                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_I8);
1977                                 if (real_target_type == TypeManager.uint64_type)
1978                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_U8);
1979                                 if (real_target_type == TypeManager.char_type)
1980                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_CH);
1981                                 if (real_target_type == TypeManager.float_type)
1982                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_R4);
1983                         }
1984
1985                         // decimal is taken care of by the op_Explicit methods.
1986
1987                         return null;
1988                 }
1989
1990                 /// <summary>
1991                 ///  Returns whether an explicit reference conversion can be performed
1992                 ///  from source_type to target_type
1993                 /// </summary>
1994                 public static bool ExplicitReferenceConversionExists (Type source_type, Type target_type)
1995                 {
1996                         bool target_is_value_type = target_type.IsValueType;
1997
1998                         if (source_type == target_type)
1999                                 return true;
2000
2001                         //
2002                         // From object to any reference type
2003                         //
2004                         if (source_type == TypeManager.object_type && !target_is_value_type)
2005                                 return true;
2006
2007                         //
2008                         // From any class S to any class-type T, provided S is a base class of T
2009                         //
2010                         if (target_type.IsSubclassOf (source_type))
2011                                 return true;
2012
2013                         //
2014                         // From any interface type S to any interface T provided S is not derived from T
2015                         //
2016                         if (source_type.IsInterface && target_type.IsInterface){
2017                                 if (!target_type.IsSubclassOf (source_type))
2018                                         return true;
2019                         }
2020
2021                         //
2022                         // From any class type S to any interface T, provided S is not sealed
2023                         // and provided S does not implement T.
2024                         //
2025                         if (target_type.IsInterface && !source_type.IsSealed &&
2026                             !TypeManager.ImplementsInterface (source_type, target_type))
2027                                 return true;
2028
2029                         //
2030                         // From any interface-type S to to any class type T, provided T is not
2031                         // sealed, or provided T implements S.
2032                         //
2033                         if (source_type.IsInterface &&
2034                             (!target_type.IsSealed || TypeManager.ImplementsInterface (target_type, source_type)))
2035                                 return true;
2036
2037
2038                         // From an array type S with an element type Se to an array type T with an
2039                         // element type Te provided all the following are true:
2040                         //     * S and T differe only in element type, in other words, S and T
2041                         //       have the same number of dimensions.
2042                         //     * Both Se and Te are reference types
2043                         //     * An explicit referenc conversions exist from Se to Te
2044                         //
2045                         if (source_type.IsArray && target_type.IsArray) {
2046                                 if (source_type.GetArrayRank () == target_type.GetArrayRank ()) {
2047
2048                                         Type source_element_type = source_type.GetElementType ();
2049                                         Type target_element_type = target_type.GetElementType ();
2050
2051                                         if (!source_element_type.IsValueType && !target_element_type.IsValueType)
2052                                                 if (ExplicitReferenceConversionExists (source_element_type,
2053                                                                                        target_element_type))
2054                                                         return true;
2055                                 }
2056                         }
2057
2058
2059                         // From System.Array to any array-type
2060                         if (source_type == TypeManager.array_type &&
2061                             target_type.IsArray){
2062                                 return true;
2063                         }
2064
2065                         //
2066                         // From System delegate to any delegate-type
2067                         //
2068                         if (source_type == TypeManager.delegate_type &&
2069                             target_type.IsSubclassOf (TypeManager.delegate_type))
2070                                 return true;
2071
2072                         //
2073                         // From ICloneable to Array or Delegate types
2074                         //
2075                         if (source_type == TypeManager.icloneable_type &&
2076                             (target_type == TypeManager.array_type ||
2077                              target_type == TypeManager.delegate_type))
2078                                 return true;
2079
2080                         return false;
2081                 }
2082
2083                 /// <summary>
2084                 ///   Implements Explicit Reference conversions
2085                 /// </summary>
2086                 static Expression ConvertReferenceExplicit (Expression source, Type target_type)
2087                 {
2088                         Type source_type = source.Type;
2089                         bool target_is_value_type = target_type.IsValueType;
2090
2091                         //
2092                         // From object to any reference type
2093                         //
2094                         if (source_type == TypeManager.object_type && !target_is_value_type)
2095                                 return new ClassCast (source, target_type);
2096
2097
2098                         //
2099                         // From any class S to any class-type T, provided S is a base class of T
2100                         //
2101                         if (target_type.IsSubclassOf (source_type))
2102                                 return new ClassCast (source, target_type);
2103
2104                         //
2105                         // From any interface type S to any interface T provided S is not derived from T
2106                         //
2107                         if (source_type.IsInterface && target_type.IsInterface){
2108                                 if (TypeManager.ImplementsInterface (source_type, target_type))
2109                                         return null;
2110                                 else
2111                                         return new ClassCast (source, target_type);
2112                         }
2113
2114                         //
2115                         // From any class type S to any interface T, provides S is not sealed
2116                         // and provided S does not implement T.
2117                         //
2118                         if (target_type.IsInterface && !source_type.IsSealed) {
2119                                 if (TypeManager.ImplementsInterface (source_type, target_type))
2120                                         return null;
2121                                 else
2122                                         return new ClassCast (source, target_type);
2123
2124                         }
2125
2126                         //
2127                         // From any interface-type S to to any class type T, provided T is not
2128                         // sealed, or provided T implements S.
2129                         //
2130                         if (source_type.IsInterface) {
2131                                 if (!target_type.IsSealed || TypeManager.ImplementsInterface (target_type, source_type))
2132                                         return new ClassCast (source, target_type);
2133                                 else
2134                                         return null;
2135                         }
2136
2137                         // From an array type S with an element type Se to an array type T with an
2138                         // element type Te provided all the following are true:
2139                         //     * S and T differe only in element type, in other words, S and T
2140                         //       have the same number of dimensions.
2141                         //     * Both Se and Te are reference types
2142                         //     * An explicit referenc conversions exist from Se to Te
2143                         //
2144                         if (source_type.IsArray && target_type.IsArray) {
2145                                 if (source_type.GetArrayRank () == target_type.GetArrayRank ()) {
2146
2147                                         Type source_element_type = source_type.GetElementType ();
2148                                         Type target_element_type = target_type.GetElementType ();
2149
2150                                         if (!source_element_type.IsValueType && !target_element_type.IsValueType)
2151                                                 if (ExplicitReferenceConversionExists (source_element_type,
2152                                                                                        target_element_type))
2153                                                         return new ClassCast (source, target_type);
2154                                 }
2155                         }
2156
2157
2158                         // From System.Array to any array-type
2159                         if (source_type == TypeManager.array_type &&
2160                             target_type.IsArray) {
2161                                 return new ClassCast (source, target_type);
2162                         }
2163
2164                         //
2165                         // From System delegate to any delegate-type
2166                         //
2167                         if (source_type == TypeManager.delegate_type &&
2168                             target_type.IsSubclassOf (TypeManager.delegate_type))
2169                                 return new ClassCast (source, target_type);
2170
2171                         //
2172                         // From ICloneable to Array or Delegate types
2173                         //
2174                         if (source_type == TypeManager.icloneable_type &&
2175                             (target_type == TypeManager.array_type ||
2176                              target_type == TypeManager.delegate_type))
2177                                 return new ClassCast (source, target_type);
2178
2179                         return null;
2180                 }
2181
2182                 /// <summary>
2183                 ///   Performs an explicit conversion of the expression `expr' whose
2184                 ///   type is expr.Type to `target_type'.
2185                 /// </summary>
2186                 static public Expression ConvertExplicit (EmitContext ec, Expression expr,
2187                                                           Type target_type, Location loc)
2188                 {
2189                         Type expr_type = expr.Type;
2190                         Expression ne = ConvertImplicitStandard (ec, expr, target_type, loc);
2191
2192                         if (ne != null)
2193                                 return ne;
2194
2195                         ne = ConvertNumericExplicit (ec, expr, target_type, loc);
2196                         if (ne != null)
2197                                 return ne;
2198
2199                         //
2200                         // Unboxing conversion.
2201                         //
2202                         if (expr_type == TypeManager.object_type && target_type.IsValueType)
2203                                 return new UnboxCast (expr, target_type);
2204
2205                         //
2206                         // Enum types
2207                         //
2208                         if (expr_type.IsSubclassOf (TypeManager.enum_type)) {
2209                                 Expression e;
2210
2211                                 //
2212                                 // FIXME: Is there any reason we should have EnumConstant
2213                                 // dealt with here instead of just using always the
2214                                 // UnderlyingSystemType to wrap the type?
2215                                 //
2216                                 if (expr is EnumConstant)
2217                                         e = ((EnumConstant) expr).Child;
2218                                 else {
2219                                         e = new EmptyCast (expr, TypeManager.EnumToUnderlying (expr_type));
2220                                 }
2221
2222                                 Expression t = ConvertImplicit (ec, e, target_type, loc);
2223                                 if (t != null)
2224                                         return t;
2225
2226                                 t = ConvertNumericExplicit (ec, e, target_type, loc);
2227                                 if (t != null)
2228                                         return t;
2229
2230                                 Error_CannotConvertType (loc, expr_type, target_type);
2231                                 return null;
2232                         }
2233
2234                         ne = ConvertReferenceExplicit (expr, target_type);
2235                         if (ne != null)
2236                                 return ne;
2237
2238                         if (ec.InUnsafe){
2239                                 if (target_type.IsPointer){
2240                                         if (expr_type.IsPointer)
2241                                                 return new EmptyCast (expr, target_type);
2242
2243                                         if (expr_type == TypeManager.sbyte_type ||
2244                                             expr_type == TypeManager.byte_type ||
2245                                             expr_type == TypeManager.short_type ||
2246                                             expr_type == TypeManager.ushort_type ||
2247                                             expr_type == TypeManager.int32_type ||
2248                                             expr_type == TypeManager.uint32_type ||
2249                                             expr_type == TypeManager.uint64_type ||
2250                                             expr_type == TypeManager.int64_type)
2251                                                 return new OpcodeCast (expr, target_type, OpCodes.Conv_U);
2252                                 }
2253                                 if (expr_type.IsPointer){
2254                                         if (target_type == TypeManager.sbyte_type ||
2255                                             target_type == TypeManager.byte_type ||
2256                                             target_type == TypeManager.short_type ||
2257                                             target_type == TypeManager.ushort_type ||
2258                                             target_type == TypeManager.int32_type ||
2259                                             target_type == TypeManager.uint32_type ||
2260                                             target_type == TypeManager.uint64_type ||
2261                                             target_type == TypeManager.int64_type){
2262                                                 Expression e = new EmptyCast (expr, TypeManager.uint32_type);
2263                                                 Expression ci, ce;
2264
2265                                                 ci = ConvertImplicitStandard (ec, e, target_type, loc);
2266
2267                                                 if (ci != null)
2268                                                         return ci;
2269
2270                                                 ce = ConvertNumericExplicit (ec, e, target_type, loc);
2271                                                 if (ce != null)
2272                                                         return ce;
2273                                                 //
2274                                                 // We should always be able to go from an uint32
2275                                                 // implicitly or explicitly to the other integral
2276                                                 // types
2277                                                 //
2278                                                 throw new Exception ("Internal compiler error");
2279                                         }
2280                                 }
2281                         }
2282
2283                         ne = ExplicitUserConversion (ec, expr, target_type, loc);
2284                         if (ne != null)
2285                                 return ne;
2286
2287                         Error_CannotConvertType (loc, expr_type, target_type);
2288                         return null;
2289                 }
2290
2291                 /// <summary>
2292                 ///   Same as ConvertExplicit, only it doesn't include user defined conversions
2293                 /// </summary>
2294                 static public Expression ConvertExplicitStandard (EmitContext ec, Expression expr,
2295                                                                   Type target_type, Location l)
2296                 {
2297                         Expression ne = ConvertImplicitStandard (ec, expr, target_type, l);
2298
2299                         if (ne != null)
2300                                 return ne;
2301
2302                         ne = ConvertNumericExplicit (ec, expr, target_type, l);
2303                         if (ne != null)
2304                                 return ne;
2305
2306                         ne = ConvertReferenceExplicit (expr, target_type);
2307                         if (ne != null)
2308                                 return ne;
2309
2310                         Error_CannotConvertType (l, expr.Type, target_type);
2311                         return null;
2312                 }
2313
2314                 static string ExprClassName (ExprClass c)
2315                 {
2316                         switch (c){
2317                         case ExprClass.Invalid:
2318                                 return "Invalid";
2319                         case ExprClass.Value:
2320                                 return "value";
2321                         case ExprClass.Variable:
2322                                 return "variable";
2323                         case ExprClass.Namespace:
2324                                 return "namespace";
2325                         case ExprClass.Type:
2326                                 return "type";
2327                         case ExprClass.MethodGroup:
2328                                 return "method group";
2329                         case ExprClass.PropertyAccess:
2330                                 return "property access";
2331                         case ExprClass.EventAccess:
2332                                 return "event access";
2333                         case ExprClass.IndexerAccess:
2334                                 return "indexer access";
2335                         case ExprClass.Nothing:
2336                                 return "null";
2337                         }
2338                         throw new Exception ("Should not happen");
2339                 }
2340
2341                 /// <summary>
2342                 ///   Reports that we were expecting `expr' to be of class `expected'
2343                 /// </summary>
2344                 public void Error118 (string expected)
2345                 {
2346                         string kind = "Unknown";
2347
2348                         kind = ExprClassName (eclass);
2349
2350                         Error (118, "Expression denotes a `" + kind +
2351                                "' where a `" + expected + "' was expected");
2352                 }
2353
2354                 public void Error118 (ResolveFlags flags)
2355                 {
2356                         ArrayList valid = new ArrayList (10);
2357
2358                         if ((flags & ResolveFlags.VariableOrValue) != 0) {
2359                                 valid.Add ("variable");
2360                                 valid.Add ("value");
2361                         }
2362
2363                         if ((flags & ResolveFlags.Type) != 0)
2364                                 valid.Add ("type");
2365
2366                         if ((flags & ResolveFlags.MethodGroup) != 0)
2367                                 valid.Add ("method group");
2368
2369                         if ((flags & ResolveFlags.SimpleName) != 0)
2370                                 valid.Add ("simple name");
2371
2372                         if (valid.Count == 0)
2373                                 valid.Add ("unknown");
2374
2375                         StringBuilder sb = new StringBuilder ();
2376                         for (int i = 0; i < valid.Count; i++) {
2377                                 if (i > 0)
2378                                         sb.Append (", ");
2379                                 else if (i == valid.Count)
2380                                         sb.Append (" or ");
2381                                 sb.Append (valid [i]);
2382                         }
2383
2384                         string kind = ExprClassName (eclass);
2385
2386                         Error (119, "Expression denotes a `" + kind + "' where " +
2387                                "a `" + sb.ToString () + "' was expected");
2388                 }
2389
2390                 static void Error_ConstantValueCannotBeConverted (Location l, string val, Type t)
2391                 {
2392                         Report.Error (31, l, "Constant value `" + val + "' cannot be converted to " +
2393                                       TypeManager.CSharpName (t));
2394                 }
2395
2396                 public static void UnsafeError (Location loc)
2397                 {
2398                         Report.Error (214, loc, "Pointers may only be used in an unsafe context");
2399                 }
2400
2401                 /// <summary>
2402                 ///   Converts the IntConstant, UIntConstant, LongConstant or
2403                 ///   ULongConstant into the integral target_type.   Notice
2404                 ///   that we do not return an `Expression' we do return
2405                 ///   a boxed integral type.
2406                 ///
2407                 ///   FIXME: Since I added the new constants, we need to
2408                 ///   also support conversions from CharConstant, ByteConstant,
2409                 ///   SByteConstant, UShortConstant, ShortConstant
2410                 ///
2411                 ///   This is used by the switch statement, so the domain
2412                 ///   of work is restricted to the literals above, and the
2413                 ///   targets are int32, uint32, char, byte, sbyte, ushort,
2414                 ///   short, uint64 and int64
2415                 /// </summary>
2416                 public static object ConvertIntLiteral (Constant c, Type target_type, Location loc)
2417                 {
2418                         string s = "";
2419
2420                         if (c.Type == target_type)
2421                                 return ((Constant) c).GetValue ();
2422
2423                         //
2424                         // Make into one of the literals we handle, we dont really care
2425                         // about this value as we will just return a few limited types
2426                         //
2427                         if (c is EnumConstant)
2428                                 c = ((EnumConstant)c).WidenToCompilerConstant ();
2429
2430                         if (c is IntConstant){
2431                                 int v = ((IntConstant) c).Value;
2432
2433                                 if (target_type == TypeManager.uint32_type){
2434                                         if (v >= 0)
2435                                                 return (uint) v;
2436                                 } else if (target_type == TypeManager.char_type){
2437                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2438                                                 return (char) v;
2439                                 } else if (target_type == TypeManager.byte_type){
2440                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2441                                                 return (byte) v;
2442                                 } else if (target_type == TypeManager.sbyte_type){
2443                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
2444                                                 return (sbyte) v;
2445                                 } else if (target_type == TypeManager.short_type){
2446                                         if (v >= Int16.MinValue && v <= UInt16.MaxValue)
2447                                                 return (short) v;
2448                                 } else if (target_type == TypeManager.ushort_type){
2449                                         if (v >= UInt16.MinValue && v <= UInt16.MaxValue)
2450                                                 return (ushort) v;
2451                                 } else if (target_type == TypeManager.int64_type)
2452                                         return (long) v;
2453                                 else if (target_type == TypeManager.uint64_type){
2454                                         if (v > 0)
2455                                                 return (ulong) v;
2456                                 }
2457
2458                                 s = v.ToString ();
2459                         } else if (c is UIntConstant){
2460                                 uint v = ((UIntConstant) c).Value;
2461
2462                                 if (target_type == TypeManager.int32_type){
2463                                         if (v <= Int32.MaxValue)
2464                                                 return (int) v;
2465                                 } else if (target_type == TypeManager.char_type){
2466                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2467                                                 return (char) v;
2468                                 } else if (target_type == TypeManager.byte_type){
2469                                         if (v <= Byte.MaxValue)
2470                                                 return (byte) v;
2471                                 } else if (target_type == TypeManager.sbyte_type){
2472                                         if (v <= SByte.MaxValue)
2473                                                 return (sbyte) v;
2474                                 } else if (target_type == TypeManager.short_type){
2475                                         if (v <= UInt16.MaxValue)
2476                                                 return (short) v;
2477                                 } else if (target_type == TypeManager.ushort_type){
2478                                         if (v <= UInt16.MaxValue)
2479                                                 return (ushort) v;
2480                                 } else if (target_type == TypeManager.int64_type)
2481                                         return (long) v;
2482                                 else if (target_type == TypeManager.uint64_type)
2483                                         return (ulong) v;
2484                                 s = v.ToString ();
2485                         } else if (c is LongConstant){
2486                                 long v = ((LongConstant) c).Value;
2487
2488                                 if (target_type == TypeManager.int32_type){
2489                                         if (v >= UInt32.MinValue && v <= UInt32.MaxValue)
2490                                                 return (int) v;
2491                                 } else if (target_type == TypeManager.uint32_type){
2492                                         if (v >= 0 && v <= UInt32.MaxValue)
2493                                                 return (uint) v;
2494                                 } else if (target_type == TypeManager.char_type){
2495                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2496                                                 return (char) v;
2497                                 } else if (target_type == TypeManager.byte_type){
2498                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2499                                                 return (byte) v;
2500                                 } else if (target_type == TypeManager.sbyte_type){
2501                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
2502                                                 return (sbyte) v;
2503                                 } else if (target_type == TypeManager.short_type){
2504                                         if (v >= Int16.MinValue && v <= UInt16.MaxValue)
2505                                                 return (short) v;
2506                                 } else if (target_type == TypeManager.ushort_type){
2507                                         if (v >= UInt16.MinValue && v <= UInt16.MaxValue)
2508                                                 return (ushort) v;
2509                                 } else if (target_type == TypeManager.uint64_type){
2510                                         if (v > 0)
2511                                                 return (ulong) v;
2512                                 }
2513                                 s = v.ToString ();
2514                         } else if (c is ULongConstant){
2515                                 ulong v = ((ULongConstant) c).Value;
2516
2517                                 if (target_type == TypeManager.int32_type){
2518                                         if (v <= Int32.MaxValue)
2519                                                 return (int) v;
2520                                 } else if (target_type == TypeManager.uint32_type){
2521                                         if (v <= UInt32.MaxValue)
2522                                                 return (uint) v;
2523                                 } else if (target_type == TypeManager.char_type){
2524                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2525                                                 return (char) v;
2526                                 } else if (target_type == TypeManager.byte_type){
2527                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2528                                                 return (byte) v;
2529                                 } else if (target_type == TypeManager.sbyte_type){
2530                                         if (v <= (int) SByte.MaxValue)
2531                                                 return (sbyte) v;
2532                                 } else if (target_type == TypeManager.short_type){
2533                                         if (v <= UInt16.MaxValue)
2534                                                 return (short) v;
2535                                 } else if (target_type == TypeManager.ushort_type){
2536                                         if (v <= UInt16.MaxValue)
2537                                                 return (ushort) v;
2538                                 } else if (target_type == TypeManager.int64_type){
2539                                         if (v <= Int64.MaxValue)
2540                                                 return (long) v;
2541                                 }
2542                                 s = v.ToString ();
2543                         } else if (c is ByteConstant){
2544                                 byte v = ((ByteConstant) c).Value;
2545
2546                                 if (target_type == TypeManager.int32_type)
2547                                         return (int) v;
2548                                 else if (target_type == TypeManager.uint32_type)
2549                                         return (uint) v;
2550                                 else if (target_type == TypeManager.char_type)
2551                                         return (char) v;
2552                                 else if (target_type == TypeManager.sbyte_type){
2553                                         if (v <= SByte.MaxValue)
2554                                                 return (sbyte) v;
2555                                 } else if (target_type == TypeManager.short_type)
2556                                         return (short) v;
2557                                 else if (target_type == TypeManager.ushort_type)
2558                                         return (ushort) v;
2559                                 else if (target_type == TypeManager.int64_type)
2560                                         return (long) v;
2561                                 else if (target_type == TypeManager.uint64_type)
2562                                         return (ulong) v;
2563                                 s = v.ToString ();
2564                         } else if (c is SByteConstant){
2565                                 sbyte v = ((SByteConstant) c).Value;
2566
2567                                 if (target_type == TypeManager.int32_type)
2568                                         return (int) v;
2569                                 else if (target_type == TypeManager.uint32_type){
2570                                         if (v >= 0)
2571                                                 return (uint) v;
2572                                 } else if (target_type == TypeManager.char_type){
2573                                         if (v >= 0)
2574                                                 return (char) v;
2575                                 } else if (target_type == TypeManager.byte_type){
2576                                         if (v >= 0)
2577                                                 return (byte) v;
2578                                 } else if (target_type == TypeManager.short_type)
2579                                         return (short) v;
2580                                 else if (target_type == TypeManager.ushort_type){
2581                                         if (v >= 0)
2582                                                 return (ushort) v;
2583                                 } else if (target_type == TypeManager.int64_type)
2584                                         return (long) v;
2585                                 else if (target_type == TypeManager.uint64_type){
2586                                         if (v >= 0)
2587                                                 return (ulong) v;
2588                                 }
2589                                 s = v.ToString ();
2590                         } else if (c is ShortConstant){
2591                                 short v = ((ShortConstant) c).Value;
2592
2593                                 if (target_type == TypeManager.int32_type){
2594                                         return (int) v;
2595                                 } else if (target_type == TypeManager.uint32_type){
2596                                         if (v >= 0)
2597                                                 return (uint) v;
2598                                 } else if (target_type == TypeManager.char_type){
2599                                         if (v >= 0)
2600                                                 return (char) v;
2601                                 } else if (target_type == TypeManager.byte_type){
2602                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2603                                                 return (byte) v;
2604                                 } else if (target_type == TypeManager.sbyte_type){
2605                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
2606                                                 return (sbyte) v;
2607                                 } else if (target_type == TypeManager.ushort_type){
2608                                         if (v >= 0)
2609                                                 return (ushort) v;
2610                                 } else if (target_type == TypeManager.int64_type)
2611                                         return (long) v;
2612                                 else if (target_type == TypeManager.uint64_type)
2613                                         return (ulong) v;
2614
2615                                 s = v.ToString ();
2616                         } else if (c is UShortConstant){
2617                                 ushort v = ((UShortConstant) c).Value;
2618
2619                                 if (target_type == TypeManager.int32_type)
2620                                         return (int) v;
2621                                 else if (target_type == TypeManager.uint32_type)
2622                                         return (uint) v;
2623                                 else if (target_type == TypeManager.char_type){
2624                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2625                                                 return (char) v;
2626                                 } else if (target_type == TypeManager.byte_type){
2627                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2628                                                 return (byte) v;
2629                                 } else if (target_type == TypeManager.sbyte_type){
2630                                         if (v <= SByte.MaxValue)
2631                                                 return (byte) v;
2632                                 } else if (target_type == TypeManager.short_type){
2633                                         if (v <= Int16.MaxValue)
2634                                                 return (short) v;
2635                                 } else if (target_type == TypeManager.int64_type)
2636                                         return (long) v;
2637                                 else if (target_type == TypeManager.uint64_type)
2638                                         return (ulong) v;
2639
2640                                 s = v.ToString ();
2641                         } else if (c is CharConstant){
2642                                 char v = ((CharConstant) c).Value;
2643
2644                                 if (target_type == TypeManager.int32_type)
2645                                         return (int) v;
2646                                 else if (target_type == TypeManager.uint32_type)
2647                                         return (uint) v;
2648                                 else if (target_type == TypeManager.byte_type){
2649                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2650                                                 return (byte) v;
2651                                 } else if (target_type == TypeManager.sbyte_type){
2652                                         if (v <= SByte.MaxValue)
2653                                                 return (sbyte) v;
2654                                 } else if (target_type == TypeManager.short_type){
2655                                         if (v <= Int16.MaxValue)
2656                                                 return (short) v;
2657                                 } else if (target_type == TypeManager.ushort_type)
2658                                         return (short) v;
2659                                 else if (target_type == TypeManager.int64_type)
2660                                         return (long) v;
2661                                 else if (target_type == TypeManager.uint64_type)
2662                                         return (ulong) v;
2663
2664                                 s = v.ToString ();
2665                         }
2666                         Error_ConstantValueCannotBeConverted (loc, s, target_type);
2667                         return null;
2668                 }
2669
2670                 //
2671                 // Load the object from the pointer.
2672                 //
2673                 public static void LoadFromPtr (ILGenerator ig, Type t)
2674                 {
2675                         if (t == TypeManager.int32_type)
2676                                 ig.Emit (OpCodes.Ldind_I4);
2677                         else if (t == TypeManager.uint32_type)
2678                                 ig.Emit (OpCodes.Ldind_U4);
2679                         else if (t == TypeManager.short_type)
2680                                 ig.Emit (OpCodes.Ldind_I2);
2681                         else if (t == TypeManager.ushort_type)
2682                                 ig.Emit (OpCodes.Ldind_U2);
2683                         else if (t == TypeManager.char_type)
2684                                 ig.Emit (OpCodes.Ldind_U2);
2685                         else if (t == TypeManager.byte_type)
2686                                 ig.Emit (OpCodes.Ldind_U1);
2687                         else if (t == TypeManager.sbyte_type)
2688                                 ig.Emit (OpCodes.Ldind_I1);
2689                         else if (t == TypeManager.uint64_type)
2690                                 ig.Emit (OpCodes.Ldind_I8);
2691                         else if (t == TypeManager.int64_type)
2692                                 ig.Emit (OpCodes.Ldind_I8);
2693                         else if (t == TypeManager.float_type)
2694                                 ig.Emit (OpCodes.Ldind_R4);
2695                         else if (t == TypeManager.double_type)
2696                                 ig.Emit (OpCodes.Ldind_R8);
2697                         else if (t == TypeManager.bool_type)
2698                                 ig.Emit (OpCodes.Ldind_I1);
2699                         else if (t == TypeManager.intptr_type)
2700                                 ig.Emit (OpCodes.Ldind_I);
2701                         else if (TypeManager.IsEnumType (t)) {
2702                                 if (t == TypeManager.enum_type)
2703                                         ig.Emit (OpCodes.Ldind_Ref);
2704                                 else
2705                                         LoadFromPtr (ig, TypeManager.EnumToUnderlying (t));
2706                         } else if (t.IsValueType)
2707                                 ig.Emit (OpCodes.Ldobj, t);
2708                         else
2709                                 ig.Emit (OpCodes.Ldind_Ref);
2710                 }
2711
2712                 //
2713                 // The stack contains the pointer and the value of type `type'
2714                 //
2715                 public static void StoreFromPtr (ILGenerator ig, Type type)
2716                 {
2717                         if (TypeManager.IsEnumType (type))
2718                                 type = TypeManager.EnumToUnderlying (type);
2719                         if (type == TypeManager.int32_type || type == TypeManager.uint32_type)
2720                                 ig.Emit (OpCodes.Stind_I4);
2721                         else if (type == TypeManager.int64_type || type == TypeManager.uint64_type)
2722                                 ig.Emit (OpCodes.Stind_I8);
2723                         else if (type == TypeManager.char_type || type == TypeManager.short_type ||
2724                                  type == TypeManager.ushort_type)
2725                                 ig.Emit (OpCodes.Stind_I2);
2726                         else if (type == TypeManager.float_type)
2727                                 ig.Emit (OpCodes.Stind_R4);
2728                         else if (type == TypeManager.double_type)
2729                                 ig.Emit (OpCodes.Stind_R8);
2730                         else if (type == TypeManager.byte_type || type == TypeManager.sbyte_type ||
2731                                  type == TypeManager.bool_type)
2732                                 ig.Emit (OpCodes.Stind_I1);
2733                         else if (type == TypeManager.intptr_type)
2734                                 ig.Emit (OpCodes.Stind_I);
2735                         else if (type.IsValueType)
2736                                 ig.Emit (OpCodes.Stobj, type);
2737                         else
2738                                 ig.Emit (OpCodes.Stind_Ref);
2739                 }
2740
2741                 //
2742                 // Returns the size of type `t' if known, otherwise, 0
2743                 //
2744                 public static int GetTypeSize (Type t)
2745                 {
2746                         t = TypeManager.TypeToCoreType (t);
2747                         if (t == TypeManager.int32_type ||
2748                             t == TypeManager.uint32_type ||
2749                             t == TypeManager.float_type)
2750                                 return 4;
2751                         else if (t == TypeManager.int64_type ||
2752                                  t == TypeManager.uint64_type ||
2753                                  t == TypeManager.double_type)
2754                                 return 8;
2755                         else if (t == TypeManager.byte_type ||
2756                                  t == TypeManager.sbyte_type ||
2757                                  t == TypeManager.bool_type)
2758                                 return 1;
2759                         else if (t == TypeManager.short_type ||
2760                                  t == TypeManager.char_type ||
2761                                  t == TypeManager.ushort_type)
2762                                 return 2;
2763                         else if (t == TypeManager.decimal_type)
2764                                 return 16;
2765                         else
2766                                 return 0;
2767                 }
2768
2769                 //
2770                 // Default implementation of IAssignMethod.CacheTemporaries
2771                 //
2772                 public void CacheTemporaries (EmitContext ec)
2773                 {
2774                 }
2775
2776                 static void Error_NegativeArrayIndex (Location loc)
2777                 {
2778                         Report.Error (284, loc, "Can not create array with a negative size");
2779                 }
2780
2781                 //
2782                 // Converts `source' to an int, uint, long or ulong.
2783                 //
2784                 public Expression ExpressionToArrayArgument (EmitContext ec, Expression source, Location loc)
2785                 {
2786                         Expression target;
2787
2788                         bool old_checked = ec.CheckState;
2789                         ec.CheckState = true;
2790
2791                         target = ConvertImplicit (ec, source, TypeManager.int32_type, loc);
2792                         if (target == null){
2793                                 target = ConvertImplicit (ec, source, TypeManager.uint32_type, loc);
2794                                 if (target == null){
2795                                         target = ConvertImplicit (ec, source, TypeManager.int64_type, loc);
2796                                         if (target == null){
2797                                                 target = ConvertImplicit (ec, source, TypeManager.uint64_type, loc);
2798                                                 if (target == null)
2799                                                         Expression.Error_CannotConvertImplicit (loc, source.Type, TypeManager.int32_type);
2800                                         }
2801                                 }
2802                         }
2803                         ec.CheckState = old_checked;
2804
2805                         //
2806                         // Only positive constants are allowed at compile time
2807                         //
2808                         if (target is Constant){
2809                                 if (target is IntConstant){
2810                                         if (((IntConstant) target).Value < 0){
2811                                                 Error_NegativeArrayIndex (loc);
2812                                                 return null;
2813                                         }
2814                                 }
2815
2816                                 if (target is LongConstant){
2817                                         if (((LongConstant) target).Value < 0){
2818                                                 Error_NegativeArrayIndex (loc);
2819                                                 return null;
2820                                         }
2821                                 }
2822
2823                         }
2824
2825                         return target;
2826                 }
2827
2828         }
2829
2830         /// <summary>
2831         ///   This is just a base class for expressions that can
2832         ///   appear on statements (invocations, object creation,
2833         ///   assignments, post/pre increment and decrement).  The idea
2834         ///   being that they would support an extra Emition interface that
2835         ///   does not leave a result on the stack.
2836         /// </summary>
2837         public abstract class ExpressionStatement : Expression {
2838
2839                 /// <summary>
2840                 ///   Requests the expression to be emitted in a `statement'
2841                 ///   context.  This means that no new value is left on the
2842                 ///   stack after invoking this method (constrasted with
2843                 ///   Emit that will always leave a value on the stack).
2844                 /// </summary>
2845                 public abstract void EmitStatement (EmitContext ec);
2846         }
2847
2848         /// <summary>
2849         ///   This kind of cast is used to encapsulate the child
2850         ///   whose type is child.Type into an expression that is
2851         ///   reported to return "return_type".  This is used to encapsulate
2852         ///   expressions which have compatible types, but need to be dealt
2853         ///   at higher levels with.
2854         ///
2855         ///   For example, a "byte" expression could be encapsulated in one
2856         ///   of these as an "unsigned int".  The type for the expression
2857         ///   would be "unsigned int".
2858         ///
2859         /// </summary>
2860         public class EmptyCast : Expression {
2861                 protected Expression child;
2862
2863                 public EmptyCast (Expression child, Type return_type)
2864                 {
2865                         eclass = child.eclass;
2866                         type = return_type;
2867                         this.child = child;
2868                 }
2869
2870                 public override Expression DoResolve (EmitContext ec)
2871                 {
2872                         // This should never be invoked, we are born in fully
2873                         // initialized state.
2874
2875                         return this;
2876                 }
2877
2878                 public override void Emit (EmitContext ec)
2879                 {
2880                         child.Emit (ec);
2881                 }
2882         }
2883
2884         /// <summary>
2885         ///  This class is used to wrap literals which belong inside Enums
2886         /// </summary>
2887         public class EnumConstant : Constant {
2888                 public Constant Child;
2889
2890                 public EnumConstant (Constant child, Type enum_type)
2891                 {
2892                         eclass = child.eclass;
2893                         this.Child = child;
2894                         type = enum_type;
2895                 }
2896
2897                 public override Expression DoResolve (EmitContext ec)
2898                 {
2899                         // This should never be invoked, we are born in fully
2900                         // initialized state.
2901
2902                         return this;
2903                 }
2904
2905                 public override void Emit (EmitContext ec)
2906                 {
2907                         Child.Emit (ec);
2908                 }
2909
2910                 public override object GetValue ()
2911                 {
2912                         return Child.GetValue ();
2913                 }
2914
2915                 //
2916                 // Converts from one of the valid underlying types for an enumeration
2917                 // (int32, uint32, int64, uint64, short, ushort, byte, sbyte) to
2918                 // one of the internal compiler literals: Int/UInt/Long/ULong Literals.
2919                 //
2920                 public Constant WidenToCompilerConstant ()
2921                 {
2922                         Type t = TypeManager.EnumToUnderlying (Child.Type);
2923                         object v = ((Constant) Child).GetValue ();;
2924
2925                         if (t == TypeManager.int32_type)
2926                                 return new IntConstant ((int) v);
2927                         if (t == TypeManager.uint32_type)
2928                                 return new UIntConstant ((uint) v);
2929                         if (t == TypeManager.int64_type)
2930                                 return new LongConstant ((long) v);
2931                         if (t == TypeManager.uint64_type)
2932                                 return new ULongConstant ((ulong) v);
2933                         if (t == TypeManager.short_type)
2934                                 return new ShortConstant ((short) v);
2935                         if (t == TypeManager.ushort_type)
2936                                 return new UShortConstant ((ushort) v);
2937                         if (t == TypeManager.byte_type)
2938                                 return new ByteConstant ((byte) v);
2939                         if (t == TypeManager.sbyte_type)
2940                                 return new SByteConstant ((sbyte) v);
2941
2942                         throw new Exception ("Invalid enumeration underlying type: " + t);
2943                 }
2944
2945                 //
2946                 // Extracts the value in the enumeration on its native representation
2947                 //
2948                 public object GetPlainValue ()
2949                 {
2950                         Type t = TypeManager.EnumToUnderlying (Child.Type);
2951                         object v = ((Constant) Child).GetValue ();;
2952
2953                         if (t == TypeManager.int32_type)
2954                                 return (int) v;
2955                         if (t == TypeManager.uint32_type)
2956                                 return (uint) v;
2957                         if (t == TypeManager.int64_type)
2958                                 return (long) v;
2959                         if (t == TypeManager.uint64_type)
2960                                 return (ulong) v;
2961                         if (t == TypeManager.short_type)
2962                                 return (short) v;
2963                         if (t == TypeManager.ushort_type)
2964                                 return (ushort) v;
2965                         if (t == TypeManager.byte_type)
2966                                 return (byte) v;
2967                         if (t == TypeManager.sbyte_type)
2968                                 return (sbyte) v;
2969
2970                         return null;
2971                 }
2972
2973                 public override string AsString ()
2974                 {
2975                         return Child.AsString ();
2976                 }
2977
2978                 public override DoubleConstant ConvertToDouble ()
2979                 {
2980                         return Child.ConvertToDouble ();
2981                 }
2982
2983                 public override FloatConstant ConvertToFloat ()
2984                 {
2985                         return Child.ConvertToFloat ();
2986                 }
2987
2988                 public override ULongConstant ConvertToULong ()
2989                 {
2990                         return Child.ConvertToULong ();
2991                 }
2992
2993                 public override LongConstant ConvertToLong ()
2994                 {
2995                         return Child.ConvertToLong ();
2996                 }
2997
2998                 public override UIntConstant ConvertToUInt ()
2999                 {
3000                         return Child.ConvertToUInt ();
3001                 }
3002
3003                 public override IntConstant ConvertToInt ()
3004                 {
3005                         return Child.ConvertToInt ();
3006                 }
3007         }
3008
3009         /// <summary>
3010         ///   This kind of cast is used to encapsulate Value Types in objects.
3011         ///
3012         ///   The effect of it is to box the value type emitted by the previous
3013         ///   operation.
3014         /// </summary>
3015         public class BoxedCast : EmptyCast {
3016
3017                 public BoxedCast (Expression expr)
3018                         : base (expr, TypeManager.object_type)
3019                 {
3020                 }
3021
3022                 public override Expression DoResolve (EmitContext ec)
3023                 {
3024                         // This should never be invoked, we are born in fully
3025                         // initialized state.
3026
3027                         return this;
3028                 }
3029
3030                 public override void Emit (EmitContext ec)
3031                 {
3032                         base.Emit (ec);
3033
3034                         ec.ig.Emit (OpCodes.Box, child.Type);
3035                 }
3036         }
3037
3038         public class UnboxCast : EmptyCast {
3039                 public UnboxCast (Expression expr, Type return_type)
3040                         : base (expr, return_type)
3041                 {
3042                 }
3043
3044                 public override Expression DoResolve (EmitContext ec)
3045                 {
3046                         // This should never be invoked, we are born in fully
3047                         // initialized state.
3048
3049                         return this;
3050                 }
3051
3052                 public override void Emit (EmitContext ec)
3053                 {
3054                         Type t = type;
3055                         ILGenerator ig = ec.ig;
3056
3057                         base.Emit (ec);
3058                         ig.Emit (OpCodes.Unbox, t);
3059
3060                         LoadFromPtr (ig, t);
3061                 }
3062         }
3063
3064         /// <summary>
3065         ///   This is used to perform explicit numeric conversions.
3066         ///
3067         ///   Explicit numeric conversions might trigger exceptions in a checked
3068         ///   context, so they should generate the conv.ovf opcodes instead of
3069         ///   conv opcodes.
3070         /// </summary>
3071         public class ConvCast : EmptyCast {
3072                 public enum Mode : byte {
3073                         I1_U1, I1_U2, I1_U4, I1_U8, I1_CH,
3074                         U1_I1, U1_CH,
3075                         I2_I1, I2_U1, I2_U2, I2_U4, I2_U8, I2_CH,
3076                         U2_I1, U2_U1, U2_I2, U2_CH,
3077                         I4_I1, I4_U1, I4_I2, I4_U2, I4_U4, I4_U8, I4_CH,
3078                         U4_I1, U4_U1, U4_I2, U4_U2, U4_I4, U4_CH,
3079                         I8_I1, I8_U1, I8_I2, I8_U2, I8_I4, I8_U4, I8_U8, I8_CH,
3080                         U8_I1, U8_U1, U8_I2, U8_U2, U8_I4, U8_U4, U8_I8, U8_CH,
3081                         CH_I1, CH_U1, CH_I2,
3082                         R4_I1, R4_U1, R4_I2, R4_U2, R4_I4, R4_U4, R4_I8, R4_U8, R4_CH,
3083                         R8_I1, R8_U1, R8_I2, R8_U2, R8_I4, R8_U4, R8_I8, R8_U8, R8_CH, R8_R4
3084                 }
3085
3086                 Mode mode;
3087                 bool checked_state;
3088
3089                 public ConvCast (EmitContext ec, Expression child, Type return_type, Mode m)
3090                         : base (child, return_type)
3091                 {
3092                         checked_state = ec.CheckState;
3093                         mode = m;
3094                 }
3095
3096                 public override Expression DoResolve (EmitContext ec)
3097                 {
3098                         // This should never be invoked, we are born in fully
3099                         // initialized state.
3100
3101                         return this;
3102                 }
3103
3104                 public override void Emit (EmitContext ec)
3105                 {
3106                         ILGenerator ig = ec.ig;
3107
3108                         base.Emit (ec);
3109
3110                         if (checked_state){
3111                                 switch (mode){
3112                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3113                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3114                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3115                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3116                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3117
3118                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3119                                 case Mode.U1_CH: /* nothing */ break;
3120
3121                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3122                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3123                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3124                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3125                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3126                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3127
3128                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3129                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
3130                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
3131                                 case Mode.U2_CH: /* nothing */ break;
3132
3133                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3134                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3135                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
3136                                 case Mode.I4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3137                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3138                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3139                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3140
3141                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3142                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
3143                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
3144                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
3145                                 case Mode.U4_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
3146                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
3147
3148                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3149                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3150                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
3151                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3152                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
3153                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3154                                 case Mode.I8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3155                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3156
3157                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3158                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
3159                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
3160                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
3161                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
3162                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_Ovf_U4_Un); break;
3163                                 case Mode.U8_I8: ig.Emit (OpCodes.Conv_Ovf_I8_Un); break;
3164                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
3165
3166                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3167                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
3168                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
3169
3170                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3171                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3172                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
3173                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3174                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
3175                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3176                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
3177                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3178                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3179
3180                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3181                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3182                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
3183                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3184                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
3185                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3186                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
3187                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3188                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3189                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
3190                                 }
3191                         } else {
3192                                 switch (mode){
3193                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_U1); break;
3194                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_U2); break;
3195                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_U4); break;
3196                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_I8); break;
3197                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_U2); break;
3198
3199                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_I1); break;
3200                                 case Mode.U1_CH: ig.Emit (OpCodes.Conv_U2); break;
3201
3202                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_I1); break;
3203                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_U1); break;
3204                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_U2); break;
3205                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_U4); break;
3206                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_I8); break;
3207                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_U2); break;
3208
3209                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_I1); break;
3210                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_U1); break;
3211                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_I2); break;
3212                                 case Mode.U2_CH: /* nothing */ break;
3213
3214                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_I1); break;
3215                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_U1); break;
3216                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_I2); break;
3217                                 case Mode.I4_U4: /* nothing */ break;
3218                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_U2); break;
3219                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_I8); break;
3220                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_U2); break;
3221
3222                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_I1); break;
3223                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_U1); break;
3224                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_I2); break;
3225                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_U2); break;
3226                                 case Mode.U4_I4: /* nothing */ break;
3227                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_U2); break;
3228
3229                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_I1); break;
3230                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_U1); break;
3231                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_I2); break;
3232                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_U2); break;
3233                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_I4); break;
3234                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_U4); break;
3235                                 case Mode.I8_U8: /* nothing */ break;
3236                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_U2); break;
3237
3238                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_I1); break;
3239                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_U1); break;
3240                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_I2); break;
3241                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_U2); break;
3242                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_I4); break;
3243                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_U4); break;
3244                                 case Mode.U8_I8: /* nothing */ break;
3245                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_U2); break;
3246
3247                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_I1); break;
3248                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_U1); break;
3249                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_I2); break;
3250
3251                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_I1); break;
3252                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_U1); break;
3253                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_I2); break;
3254                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_U2); break;
3255                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_I4); break;
3256                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_U4); break;
3257                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_I8); break;
3258                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_U8); break;
3259                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_U2); break;
3260
3261                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_I1); break;
3262                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_U1); break;
3263                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_I2); break;
3264                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_U2); break;
3265                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_I4); break;
3266                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_U4); break;
3267                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_I8); break;
3268                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_U8); break;
3269                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_U2); break;
3270                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
3271                                 }
3272                         }
3273                 }
3274         }
3275
3276         public class OpcodeCast : EmptyCast {
3277                 OpCode op, op2;
3278                 bool second_valid;
3279
3280                 public OpcodeCast (Expression child, Type return_type, OpCode op)
3281                         : base (child, return_type)
3282
3283                 {
3284                         this.op = op;
3285                         second_valid = false;
3286                 }
3287
3288                 public OpcodeCast (Expression child, Type return_type, OpCode op, OpCode op2)
3289                         : base (child, return_type)
3290
3291                 {
3292                         this.op = op;
3293                         this.op2 = op2;
3294                         second_valid = true;
3295                 }
3296
3297                 public override Expression DoResolve (EmitContext ec)
3298                 {
3299                         // This should never be invoked, we are born in fully
3300                         // initialized state.
3301
3302                         return this;
3303                 }
3304
3305                 public override void Emit (EmitContext ec)
3306                 {
3307                         base.Emit (ec);
3308                         ec.ig.Emit (op);
3309
3310                         if (second_valid)
3311                                 ec.ig.Emit (op2);
3312                 }
3313         }
3314
3315         /// <summary>
3316         ///   This kind of cast is used to encapsulate a child and cast it
3317         ///   to the class requested
3318         /// </summary>
3319         public class ClassCast : EmptyCast {
3320                 public ClassCast (Expression child, Type return_type)
3321                         : base (child, return_type)
3322
3323                 {
3324                 }
3325
3326                 public override Expression DoResolve (EmitContext ec)
3327                 {
3328                         // This should never be invoked, we are born in fully
3329                         // initialized state.
3330
3331                         return this;
3332                 }
3333
3334                 public override void Emit (EmitContext ec)
3335                 {
3336                         base.Emit (ec);
3337
3338                         ec.ig.Emit (OpCodes.Castclass, type);
3339                 }
3340
3341         }
3342
3343         /// <summary>
3344         ///   SimpleName expressions are initially formed of a single
3345         ///   word and it only happens at the beginning of the expression.
3346         /// </summary>
3347         ///
3348         /// <remarks>
3349         ///   The expression will try to be bound to a Field, a Method
3350         ///   group or a Property.  If those fail we pass the name to our
3351         ///   caller and the SimpleName is compounded to perform a type
3352         ///   lookup.  The idea behind this process is that we want to avoid
3353         ///   creating a namespace map from the assemblies, as that requires
3354         ///   the GetExportedTypes function to be called and a hashtable to
3355         ///   be constructed which reduces startup time.  If later we find
3356         ///   that this is slower, we should create a `NamespaceExpr' expression
3357         ///   that fully participates in the resolution process.
3358         ///
3359         ///   For example `System.Console.WriteLine' is decomposed into
3360         ///   MemberAccess (MemberAccess (SimpleName ("System"), "Console"), "WriteLine")
3361         ///
3362         ///   The first SimpleName wont produce a match on its own, so it will
3363         ///   be turned into:
3364         ///   MemberAccess (SimpleName ("System.Console"), "WriteLine").
3365         ///
3366         ///   System.Console will produce a TypeExpr match.
3367         ///
3368         ///   The downside of this is that we might be hitting `LookupType' too many
3369         ///   times with this scheme.
3370         /// </remarks>
3371         public class SimpleName : Expression, ITypeExpression {
3372                 public readonly string Name;
3373
3374                 public SimpleName (string name, Location l)
3375                 {
3376                         Name = name;
3377                         loc = l;
3378                 }
3379
3380                 public static void Error_ObjectRefRequired (EmitContext ec, Location l, string name)
3381                 {
3382                         if (ec.IsFieldInitializer)
3383                                 Report.Error (
3384                                         236, l,
3385                                         "A field initializer cannot reference the non-static field, " +
3386                                         "method or property `"+name+"'");
3387                         else
3388                                 Report.Error (
3389                                         120, l,
3390                                         "An object reference is required " +
3391                                         "for the non-static field `"+name+"'");
3392                 }
3393
3394                 //
3395                 // Checks whether we are trying to access an instance
3396                 // property, method or field from a static body.
3397                 //
3398                 Expression MemberStaticCheck (EmitContext ec, Expression e)
3399                 {
3400                         if (e is IMemberExpr){
3401                                 IMemberExpr member = (IMemberExpr) e;
3402
3403                                 if (!member.IsStatic){
3404                                         Error_ObjectRefRequired (ec, loc, Name);
3405                                         return null;
3406                                 }
3407                         }
3408
3409                         return e;
3410                 }
3411
3412                 public override Expression DoResolve (EmitContext ec)
3413                 {
3414                         return SimpleNameResolve (ec, null, false);
3415                 }
3416
3417                 public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
3418                 {
3419                         return SimpleNameResolve (ec, right_side, false);
3420                 }
3421
3422
3423                 public Expression DoResolveAllowStatic (EmitContext ec)
3424                 {
3425                         return SimpleNameResolve (ec, null, true);
3426                 }
3427
3428                 public Expression DoResolveType (EmitContext ec)
3429                 {
3430                         //
3431                         // Stage 3: Lookup symbol in the various namespaces.
3432                         //
3433                         DeclSpace ds = ec.DeclSpace;
3434                         Type t;
3435                         string alias_value;
3436
3437                         if (ec.ResolvingTypeTree){
3438                                 int errors = Report.Errors;
3439                                 Type dt = ec.DeclSpace.FindType (loc, Name);
3440                                 if (Report.Errors != errors)
3441                                         return null;
3442
3443                                 if (dt != null)
3444                                         return new TypeExpr (dt, loc);
3445                         }
3446
3447                         if ((t = RootContext.LookupType (ds, Name, true, loc)) != null)
3448                                 return new TypeExpr (t, loc);
3449
3450
3451                         //
3452                         // Stage 2 part b: Lookup up if we are an alias to a type
3453                         // or a namespace.
3454                         //
3455                         // Since we are cheating: we only do the Alias lookup for
3456                         // namespaces if the name does not include any dots in it
3457                         //
3458
3459                         alias_value = ec.DeclSpace.LookupAlias (Name);
3460
3461                         if (Name.IndexOf ('.') == -1 && alias_value != null) {
3462                                 if ((t = RootContext.LookupType (ds, alias_value, true, loc)) != null)
3463                                         return new TypeExpr (t, loc);
3464
3465                                 // we have alias value, but it isn't Type, so try if it's namespace
3466                                 return new SimpleName (alias_value, loc);
3467                         }
3468
3469                         // No match, maybe our parent can compose us
3470                         // into something meaningful.
3471                         return this;
3472                 }
3473
3474                 /// <remarks>
3475                 ///   7.5.2: Simple Names.
3476                 ///
3477                 ///   Local Variables and Parameters are handled at
3478                 ///   parse time, so they never occur as SimpleNames.
3479                 ///
3480                 ///   The `allow_static' flag is used by MemberAccess only
3481                 ///   and it is used to inform us that it is ok for us to
3482                 ///   avoid the static check, because MemberAccess might end
3483                 ///   up resolving the Name as a Type name and the access as
3484                 ///   a static type access.
3485                 ///
3486                 ///   ie: Type Type; .... { Type.GetType (""); }
3487                 ///
3488                 ///   Type is both an instance variable and a Type;  Type.GetType
3489                 ///   is the static method not an instance method of type.
3490                 /// </remarks>
3491                 Expression SimpleNameResolve (EmitContext ec, Expression right_side, bool allow_static)
3492                 {
3493                         Expression e = null;
3494
3495                         //
3496                         // Stage 1: Performed by the parser (binding to locals or parameters).
3497                         //
3498                         Block current_block = ec.CurrentBlock;
3499                         if (current_block != null && current_block.IsVariableDefined (Name)){
3500                                 LocalVariableReference var;
3501
3502                                 var = new LocalVariableReference (ec.CurrentBlock, Name, loc);
3503
3504                                 if (right_side != null)
3505                                         return var.ResolveLValue (ec, right_side);
3506                                 else
3507                                         return var.Resolve (ec);
3508                         }
3509
3510                         if (current_block != null){
3511                                 int idx = -1;
3512                                 Parameter par = null;
3513                                 Parameters pars = current_block.Parameters;
3514                                 if (pars != null)
3515                                         par = pars.GetParameterByName (Name, out idx);
3516
3517                                 if (par != null) {
3518                                         ParameterReference param;
3519
3520                                         param = new ParameterReference (pars, idx, Name, loc);
3521
3522                                         if (right_side != null)
3523                                                 return param.ResolveLValue (ec, right_side);
3524                                         else
3525                                                 return param.Resolve (ec);
3526                                 }
3527                         }
3528
3529                         //
3530                         // Stage 2: Lookup members
3531                         //
3532
3533                         //
3534                         // For enums, the TypeBuilder is not ec.DeclSpace.TypeBuilder
3535                         // Hence we have two different cases
3536                         //
3537
3538                         DeclSpace lookup_ds = ec.DeclSpace;
3539                         do {
3540                                 if (lookup_ds.TypeBuilder == null)
3541                                         break;
3542
3543                                 e = MemberLookup (ec, lookup_ds.TypeBuilder, Name, loc);
3544                                 if (e != null)
3545                                         break;
3546
3547                                 //
3548                                 // Classes/structs keep looking, enums break
3549                                 //
3550                                 if (lookup_ds is TypeContainer)
3551                                         lookup_ds = ((TypeContainer) lookup_ds).Parent;
3552                                 else
3553                                         break;
3554                         } while (lookup_ds != null);
3555
3556                         if (e == null && ec.ContainerType != null)
3557                                 e = MemberLookup (ec, ec.ContainerType, Name, loc);
3558
3559                         if (e == null)
3560                                 return DoResolveType (ec);
3561
3562                         if (e is TypeExpr)
3563                                 return e;
3564
3565                         if (e is IMemberExpr) {
3566                                 e = MemberAccess.ResolveMemberAccess (ec, e, null, loc, this);
3567                                 if (e == null)
3568                                         return null;
3569
3570                                 IMemberExpr me = e as IMemberExpr;
3571                                 if (me == null)
3572                                         return e;
3573
3574                                 // This fails if ResolveMemberAccess() was unable to decide whether
3575                                 // it's a field or a type of the same name.
3576                                 if (!me.IsStatic && (me.InstanceExpression == null))
3577                                         return e;
3578
3579 /* FIXME    If this is not commented out, it seems that it's not possible to reach class members in mBas.
3580             Maybe a grammar-related problem?
3581
3582                                 if (!me.IsStatic &&
3583                                     TypeManager.IsNestedChildOf (me.InstanceExpression.Type, me.DeclaringType)) {
3584                                         Error (38, "Cannot access nonstatic member `" + me.Name + "' of " +
3585                                                "outer type `" + me.DeclaringType + "' via nested type `" +
3586                                                me.InstanceExpression.Type + "'");
3587                                         return null;
3588                                 }
3589 */
3590                                 if (right_side != null)
3591                                         e = e.DoResolveLValue (ec, right_side);
3592                                 else
3593                                         e = e.DoResolve (ec);
3594
3595                                 return e;
3596                         }
3597
3598                         if (ec.IsStatic || ec.IsFieldInitializer){
3599                                 if (allow_static)
3600                                         return e;
3601
3602                                 return MemberStaticCheck (ec, e);
3603                         } else
3604                                 return e;
3605                 }
3606
3607                 public override void Emit (EmitContext ec)
3608                 {
3609                         //
3610                         // If this is ever reached, then we failed to
3611                         // find the name as a namespace
3612                         //
3613
3614                         Error (103, "The name `" + Name +
3615                                "' does not exist in the class `" +
3616                                ec.DeclSpace.Name + "'");
3617                 }
3618
3619                 public override string ToString ()
3620                 {
3621                         return Name;
3622                 }
3623         }
3624
3625         /// <summary>
3626         ///   Fully resolved expression that evaluates to a type
3627         /// </summary>
3628         public class TypeExpr : Expression, ITypeExpression {
3629                 public TypeExpr (Type t, Location l)
3630                 {
3631                         Type = t;
3632                         eclass = ExprClass.Type;
3633                         loc = l;
3634                 }
3635
3636                 public virtual Expression DoResolveType (EmitContext ec)
3637                 {
3638                         return this;
3639                 }
3640
3641                 override public Expression DoResolve (EmitContext ec)
3642                 {
3643                         return this;
3644                 }
3645
3646                 override public void Emit (EmitContext ec)
3647                 {
3648                         throw new Exception ("Should never be called");
3649                 }
3650
3651                 public override string ToString ()
3652                 {
3653                         return Type.ToString ();
3654                 }
3655         }
3656
3657         /// <summary>
3658         ///   Used to create types from a fully qualified name.  These are just used
3659         ///   by the parser to setup the core types.  A TypeLookupExpression is always
3660         ///   classified as a type.
3661         /// </summary>
3662         public class TypeLookupExpression : TypeExpr {
3663                 string name;
3664
3665                 public TypeLookupExpression (string name) : base (null, Location.Null)
3666                 {
3667                         this.name = name;
3668                 }
3669
3670                 public override Expression DoResolveType (EmitContext ec)
3671                 {
3672                         if (type == null)
3673                                 type = RootContext.LookupType (ec.DeclSpace, name, false, Location.Null);
3674                         return this;
3675                 }
3676
3677                 public override Expression DoResolve (EmitContext ec)
3678                 {
3679                         return DoResolveType (ec);
3680                 }
3681
3682                 public override void Emit (EmitContext ec)
3683                 {
3684                         throw new Exception ("Should never be called");
3685                 }
3686
3687                 public override string ToString ()
3688                 {
3689                         return name;
3690                 }
3691         }
3692
3693         /// <summary>
3694         ///   MethodGroup Expression.
3695         ///
3696         ///   This is a fully resolved expression that evaluates to a type
3697         /// </summary>
3698         public class MethodGroupExpr : Expression, IMemberExpr {
3699                 public MethodBase [] Methods;
3700                 Expression instance_expression = null;
3701                 bool is_explicit_impl = false;
3702
3703                 public MethodGroupExpr (MemberInfo [] mi, Location l)
3704                 {
3705                         Methods = new MethodBase [mi.Length];
3706                         mi.CopyTo (Methods, 0);
3707                         eclass = ExprClass.MethodGroup;
3708                         type = TypeManager.object_type;
3709                         loc = l;
3710                 }
3711
3712                 public MethodGroupExpr (ArrayList list, Location l)
3713                 {
3714                         Methods = new MethodBase [list.Count];
3715
3716                         try {
3717                                 list.CopyTo (Methods, 0);
3718                         } catch {
3719                                 foreach (MemberInfo m in list){
3720                                         if (!(m is MethodBase)){
3721                                                 Console.WriteLine ("Name " + m.Name);
3722                                                 Console.WriteLine ("Found a: " + m.GetType ().FullName);
3723                                         }
3724                                 }
3725                                 throw;
3726                         }
3727                         loc = l;
3728                         eclass = ExprClass.MethodGroup;
3729                         type = TypeManager.object_type;
3730                 }
3731
3732                 public Type DeclaringType {
3733                         get {
3734                                 return Methods [0].DeclaringType;
3735                         }
3736                 }
3737
3738                 //
3739                 // `A method group may have associated an instance expression'
3740                 //
3741                 public Expression InstanceExpression {
3742                         get {
3743                                 return instance_expression;
3744                         }
3745
3746                         set {
3747                                 instance_expression = value;
3748                         }
3749                 }
3750
3751                 public bool IsExplicitImpl {
3752                         get {
3753                                 return is_explicit_impl;
3754                         }
3755
3756                         set {
3757                                 is_explicit_impl = value;
3758                         }
3759                 }
3760
3761                 public string Name {
3762                         get {
3763                                 return Methods [0].Name;
3764                         }
3765                 }
3766
3767                 public bool IsInstance {
3768                         get {
3769                                 foreach (MethodBase mb in Methods)
3770                                         if (!mb.IsStatic)
3771                                                 return true;
3772
3773                                 return false;
3774                         }
3775                 }
3776
3777                 public bool IsStatic {
3778                         get {
3779                                 foreach (MethodBase mb in Methods)
3780                                         if (mb.IsStatic)
3781                                                 return true;
3782
3783                                 return false;
3784                         }
3785                 }
3786
3787                 override public Expression DoResolve (EmitContext ec)
3788                 {
3789                         if (instance_expression != null) {
3790                                 instance_expression = instance_expression.DoResolve (ec);
3791                                 if (instance_expression == null)
3792                                         return null;
3793                         }
3794
3795                         return this;
3796                 }
3797
3798                 public void ReportUsageError ()
3799                 {
3800                         Report.Error (654, loc, "Method `" + Methods [0].DeclaringType + "." +
3801                                       Methods [0].Name + "()' is referenced without parentheses");
3802                 }
3803
3804                 override public void Emit (EmitContext ec)
3805                 {
3806                         ReportUsageError ();
3807                 }
3808
3809                 bool RemoveMethods (bool keep_static)
3810                 {
3811                         ArrayList smethods = new ArrayList ();
3812
3813                         foreach (MethodBase mb in Methods){
3814                                 if (mb.IsStatic == keep_static)
3815                                         smethods.Add (mb);
3816                         }
3817
3818                         if (smethods.Count == 0)
3819                                 return false;
3820
3821                         Methods = new MethodBase [smethods.Count];
3822                         smethods.CopyTo (Methods, 0);
3823
3824                         return true;
3825                 }
3826
3827                 /// <summary>
3828                 ///   Removes any instance methods from the MethodGroup, returns
3829                 ///   false if the resulting set is empty.
3830                 /// </summary>
3831                 public bool RemoveInstanceMethods ()
3832                 {
3833                         return RemoveMethods (true);
3834                 }
3835
3836                 /// <summary>
3837                 ///   Removes any static methods from the MethodGroup, returns
3838                 ///   false if the resulting set is empty.
3839                 /// </summary>
3840                 public bool RemoveStaticMethods ()
3841                 {
3842                         return RemoveMethods (false);
3843                 }
3844         }
3845
3846         /// <summary>
3847         ///   Fully resolved expression that evaluates to a Field
3848         /// </summary>
3849         public class FieldExpr : Expression, IAssignMethod, IMemoryLocation, IMemberExpr {
3850                 public readonly FieldInfo FieldInfo;
3851                 Expression instance_expr;
3852
3853                 public FieldExpr (FieldInfo fi, Location l)
3854                 {
3855                         FieldInfo = fi;
3856                         eclass = ExprClass.Variable;
3857                         type = fi.FieldType;
3858                         loc = l;
3859                 }
3860
3861                 public string Name {
3862                         get {
3863                                 return FieldInfo.Name;
3864                         }
3865                 }
3866
3867                 public bool IsInstance {
3868                         get {
3869                                 return !FieldInfo.IsStatic;
3870                         }
3871                 }
3872
3873                 public bool IsStatic {
3874                         get {
3875                                 return FieldInfo.IsStatic;
3876                         }
3877                 }
3878
3879                 public Type DeclaringType {
3880                         get {
3881                                 return FieldInfo.DeclaringType;
3882                         }
3883                 }
3884
3885                 public Expression InstanceExpression {
3886                         get {
3887                                 return instance_expr;
3888                         }
3889
3890                         set {
3891                                 instance_expr = value;
3892                         }
3893                 }
3894
3895                 override public Expression DoResolve (EmitContext ec)
3896                 {
3897                         if (!FieldInfo.IsStatic){
3898                                 if (instance_expr == null){
3899                                         throw new Exception ("non-static FieldExpr without instance var\n" +
3900                                                              "You have to assign the Instance variable\n" +
3901                                                              "Of the FieldExpr to set this\n");
3902                                 }
3903
3904                                 // Resolve the field's instance expression while flow analysis is turned
3905                                 // off: when accessing a field "a.b", we must check whether the field
3906                                 // "a.b" is initialized, not whether the whole struct "a" is initialized.
3907                                 instance_expr = instance_expr.Resolve (ec, ResolveFlags.VariableOrValue |
3908                                                                        ResolveFlags.DisableFlowAnalysis);
3909                                 if (instance_expr == null)
3910                                         return null;
3911                         }
3912
3913                         // If the instance expression is a local variable or parameter.
3914                         IVariable var = instance_expr as IVariable;
3915                         if ((var != null) && !var.IsFieldAssigned (ec, FieldInfo.Name, loc))
3916                                 return null;
3917
3918                         return this;
3919                 }
3920
3921                 void Report_AssignToReadonly (bool is_instance)
3922                 {
3923                         string msg;
3924
3925                         if (is_instance)
3926                                 msg = "Readonly field can not be assigned outside " +
3927                                 "of constructor or variable initializer";
3928                         else
3929                                 msg = "A static readonly field can only be assigned in " +
3930                                 "a static constructor";
3931
3932                         Report.Error (is_instance ? 191 : 198, loc, msg);
3933                 }
3934
3935                 override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
3936                 {
3937                         IVariable var = instance_expr as IVariable;
3938                         if (var != null)
3939                                 var.SetFieldAssigned (ec, FieldInfo.Name);
3940
3941                         Expression e = DoResolve (ec);
3942
3943                         if (e == null)
3944                                 return null;
3945
3946                         if (!FieldInfo.IsInitOnly)
3947                                 return this;
3948
3949                         //
3950                         // InitOnly fields can only be assigned in constructors
3951                         //
3952
3953                         if (ec.IsConstructor)
3954                                 return this;
3955
3956                         Report_AssignToReadonly (true);
3957
3958                         return null;
3959                 }
3960
3961                 override public void Emit (EmitContext ec)
3962                 {
3963                         ILGenerator ig = ec.ig;
3964                         bool is_volatile = false;
3965
3966                         if (FieldInfo is FieldBuilder){
3967                                 FieldBase f = TypeManager.GetField (FieldInfo);
3968
3969                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
3970                                         is_volatile = true;
3971
3972                                 f.status |= Field.Status.USED;
3973                         }
3974
3975                         if (FieldInfo.IsStatic){
3976                                 if (is_volatile)
3977                                         ig.Emit (OpCodes.Volatile);
3978
3979                                 ig.Emit (OpCodes.Ldsfld, FieldInfo);
3980                         } else {
3981                                 if (instance_expr.Type.IsValueType){
3982                                         IMemoryLocation ml;
3983                                         LocalTemporary tempo = null;
3984
3985                                         if (!(instance_expr is IMemoryLocation)){
3986                                                 tempo = new LocalTemporary (
3987                                                         ec, instance_expr.Type);
3988
3989                                                 InstanceExpression.Emit (ec);
3990                                                 tempo.Store (ec);
3991                                                 ml = tempo;
3992                                         } else
3993                                                 ml = (IMemoryLocation) instance_expr;
3994
3995                                         ml.AddressOf (ec, AddressOp.Load);
3996                                 } else
3997                                         instance_expr.Emit (ec);
3998
3999                                 if (is_volatile)
4000                                         ig.Emit (OpCodes.Volatile);
4001
4002                                 ig.Emit (OpCodes.Ldfld, FieldInfo);
4003                         }
4004                 }
4005
4006                 public void EmitAssign (EmitContext ec, Expression source)
4007                 {
4008                         FieldAttributes fa = FieldInfo.Attributes;
4009                         bool is_static = (fa & FieldAttributes.Static) != 0;
4010                         bool is_readonly = (fa & FieldAttributes.InitOnly) != 0;
4011                         ILGenerator ig = ec.ig;
4012
4013                         if (is_readonly && !ec.IsConstructor){
4014                                 Report_AssignToReadonly (!is_static);
4015                                 return;
4016                         }
4017
4018                         if (!is_static){
4019                                 Expression instance = instance_expr;
4020
4021                                 if (instance.Type.IsValueType){
4022                                         if (instance is IMemoryLocation){
4023                                                 IMemoryLocation ml = (IMemoryLocation) instance;
4024
4025                                                 ml.AddressOf (ec, AddressOp.Store);
4026                                         } else
4027                                                 throw new Exception ("The " + instance + " of type " +
4028                                                                      instance.Type +
4029                                                                      " represents a ValueType and does " +
4030                                                                      "not implement IMemoryLocation");
4031                                 } else
4032                                         instance.Emit (ec);
4033                         }
4034                         source.Emit (ec);
4035
4036                         if (FieldInfo is FieldBuilder){
4037                                 FieldBase f = TypeManager.GetField (FieldInfo);
4038
4039                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
4040                                         ig.Emit (OpCodes.Volatile);
4041                         }
4042
4043                         if (is_static)
4044                                 ig.Emit (OpCodes.Stsfld, FieldInfo);
4045                         else
4046                                 ig.Emit (OpCodes.Stfld, FieldInfo);
4047
4048                         if (FieldInfo is FieldBuilder){
4049                                 FieldBase f = TypeManager.GetField (FieldInfo);
4050
4051                                 f.status |= Field.Status.ASSIGNED;
4052                         }
4053                 }
4054
4055                 public void AddressOf (EmitContext ec, AddressOp mode)
4056                 {
4057                         ILGenerator ig = ec.ig;
4058
4059                         if (FieldInfo is FieldBuilder){
4060                                 FieldBase f = TypeManager.GetField (FieldInfo);
4061                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
4062                                         ig.Emit (OpCodes.Volatile);
4063                         }
4064
4065                         if (FieldInfo is FieldBuilder){
4066                                 FieldBase f = TypeManager.GetField (FieldInfo);
4067
4068                                 if ((mode & AddressOp.Store) != 0)
4069                                         f.status |= Field.Status.ASSIGNED;
4070                                 if ((mode & AddressOp.Load) != 0)
4071                                         f.status |= Field.Status.USED;
4072                         }
4073
4074                         //
4075                         // Handle initonly fields specially: make a copy and then
4076                         // get the address of the copy.
4077                         //
4078                         if (FieldInfo.IsInitOnly && !ec.IsConstructor){
4079                                 LocalBuilder local;
4080
4081                                 Emit (ec);
4082                                 local = ig.DeclareLocal (type);
4083                                 ig.Emit (OpCodes.Stloc, local);
4084                                 ig.Emit (OpCodes.Ldloca, local);
4085                                 return;
4086                         }
4087
4088                         if (FieldInfo.IsStatic)
4089                                 ig.Emit (OpCodes.Ldsflda, FieldInfo);
4090                         else {
4091                                 if (instance_expr is IMemoryLocation)
4092                                         ((IMemoryLocation)instance_expr).AddressOf (ec, AddressOp.LoadStore);
4093                                 else
4094                                         instance_expr.Emit (ec);
4095                                 ig.Emit (OpCodes.Ldflda, FieldInfo);
4096                         }
4097                 }
4098         }
4099
4100         /// <summary>
4101         ///   Expression that evaluates to a Property.  The Assign class
4102         ///   might set the `Value' expression if we are in an assignment.
4103         ///
4104         ///   This is not an LValue because we need to re-write the expression, we
4105         ///   can not take data from the stack and store it.
4106         /// </summary>
4107         public class PropertyExpr : ExpressionStatement, IAssignMethod, IMemberExpr {
4108                 public readonly PropertyInfo PropertyInfo;
4109                 public bool IsBase;
4110                 MethodInfo getter, setter;
4111                 bool is_static;
4112                 public ArrayList PropertyArgs;
4113
4114                 Expression instance_expr;
4115
4116                 public PropertyExpr (EmitContext ec, PropertyInfo pi, Location l)
4117                 {
4118                         PropertyInfo = pi;
4119                         eclass = ExprClass.PropertyAccess;
4120                         PropertyArgs = new ArrayList();
4121                         is_static = false;
4122                         loc = l;
4123
4124                         type = TypeManager.TypeToCoreType (pi.PropertyType);
4125
4126                         ResolveAccessors (ec);
4127                 }
4128
4129                 public string Name {
4130                         get {
4131                                 return PropertyInfo.Name;
4132                         }
4133                 }
4134
4135                 public bool IsInstance {
4136                         get {
4137                                 return !is_static;
4138                         }
4139                 }
4140
4141                 public bool IsStatic {
4142                         get {
4143                                 return is_static;
4144                         }
4145                 }
4146
4147                 public Type DeclaringType {
4148                         get {
4149                                 return PropertyInfo.DeclaringType;
4150                         }
4151                 }
4152
4153                 //
4154                 // The instance expression associated with this expression
4155                 //
4156                 public Expression InstanceExpression {
4157                         set {
4158                                 instance_expr = value;
4159                         }
4160
4161                         get {
4162                                 return instance_expr;
4163                         }
4164                 }
4165
4166                 public bool VerifyAssignable ()
4167                 {
4168                         if (!PropertyInfo.CanWrite){
4169                                 Report.Error (200, loc,
4170                                               "The property `" + PropertyInfo.Name +
4171                                               "' can not be assigned to, as it has not set accessor");
4172                                 return false;
4173                         }
4174
4175                         return true;
4176                 }
4177
4178                 void ResolveAccessors (EmitContext ec)
4179                 {
4180                         BindingFlags flags = BindingFlags.Public | BindingFlags.Static | BindingFlags.Instance;
4181                         MemberInfo [] group;
4182
4183                         group = TypeManager.MemberLookup (ec.ContainerType, PropertyInfo.DeclaringType,
4184                                                               MemberTypes.Method, flags, "get_" + PropertyInfo.Name);
4185
4186                         //
4187                         // The first method is the closest to us
4188                         //
4189                         if (group != null && group.Length > 0){
4190                                 getter = (MethodInfo) group [0];
4191
4192                                 if (getter.IsStatic)
4193                                         is_static = true;
4194                         }
4195
4196                         //
4197                         // The first method is the closest to us
4198                         //
4199                         group = TypeManager.MemberLookup (ec.ContainerType, PropertyInfo.DeclaringType,
4200                                                           MemberTypes.Method, flags, "set_" + PropertyInfo.Name);
4201                         if (group != null && group.Length > 0){
4202                                 setter = (MethodInfo) group [0];
4203                                 if (setter.IsStatic)
4204                                         is_static = true;
4205                         }
4206                 }
4207
4208                 override public Expression DoResolve (EmitContext ec)
4209                 {
4210                         if (getter == null){
4211                                 Report.Error (154, loc,
4212                                               "The property `" + PropertyInfo.Name +
4213                                               "' can not be used in " +
4214                                               "this context because it lacks a get accessor");
4215                                 return null;
4216                         }
4217
4218                         if ((instance_expr == null) && ec.IsStatic && !is_static) {
4219                                 SimpleName.Error_ObjectRefRequired (ec, loc, PropertyInfo.Name);
4220                                 return null;
4221                         }
4222
4223                         if (instance_expr != null) {
4224                                 instance_expr = instance_expr.DoResolve (ec);
4225                                 if (instance_expr == null)
4226                                         return null;
4227                         }
4228
4229                         return this;
4230                 }
4231
4232                 override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
4233                 {
4234                         if (setter == null){
4235                                 Report.Error (154, loc,
4236                                               "The property `" + PropertyInfo.Name +
4237                                               "' can not be used in " +
4238                                               "this context because it lacks a set accessor");
4239                                 return null;
4240                         }
4241
4242                         if (instance_expr != null) {
4243                                 instance_expr = instance_expr.DoResolve (ec);
4244                                 if (instance_expr == null)
4245                                         return null;
4246                         }
4247
4248                         return this;
4249                 }
4250
4251                 override public void Emit (EmitContext ec)
4252                 {
4253                         //
4254                         // Special case: length of single dimension array property is turned into ldlen
4255                         //
4256                         if ((getter == TypeManager.system_int_array_get_length) ||
4257                             (getter == TypeManager.int_array_get_length)){
4258                                 Type iet = instance_expr.Type;
4259
4260                                 //
4261                                 // System.Array.Length can be called, but the Type does not
4262                                 // support invoking GetArrayRank, so test for that case first
4263                                 //
4264                                 if (iet != TypeManager.array_type && (iet.GetArrayRank () == 1)){
4265                                         instance_expr.Emit (ec);
4266                                         ec.ig.Emit (OpCodes.Ldlen);
4267                                         return;
4268                                 }
4269                         }
4270                         Invocation.EmitCall (ec, IsBase, IsStatic, instance_expr, getter, null, PropertyArgs, loc);
4271                 }
4272
4273                 //
4274                 // Implements the IAssignMethod interface for assignments
4275                 //
4276                 public void EmitAssign (EmitContext ec, Expression source)
4277                 {
4278                         Argument arg = new Argument (source, Argument.AType.Expression);
4279                         ArrayList args = new ArrayList ();
4280 //HERE
4281                         args.Add (arg);
4282                         Invocation.EmitCall (ec, IsBase, IsStatic, instance_expr, setter, args, PropertyArgs,loc);
4283                 }
4284
4285                 override public void EmitStatement (EmitContext ec)
4286                 {
4287                         Emit (ec);
4288                         ec.ig.Emit (OpCodes.Pop);
4289                 }
4290         }
4291
4292         /// <summary>
4293         ///   Fully resolved expression that evaluates to an Event
4294         /// </summary>
4295         public class EventExpr : Expression, IMemberExpr {
4296                 public readonly EventInfo EventInfo;
4297                 public Expression instance_expr;
4298
4299                 bool is_static;
4300                 MethodInfo add_accessor, remove_accessor;
4301
4302                 public EventExpr (EventInfo ei, Location loc)
4303                 {
4304                         EventInfo = ei;
4305                         this.loc = loc;
4306                         eclass = ExprClass.EventAccess;
4307
4308                         add_accessor = TypeManager.GetAddMethod (ei);
4309                         remove_accessor = TypeManager.GetRemoveMethod (ei);
4310
4311                         if (add_accessor.IsStatic || remove_accessor.IsStatic)
4312                                 is_static = true;
4313
4314                         if (EventInfo is MyEventBuilder)
4315                                 type = ((MyEventBuilder) EventInfo).EventType;
4316                         else
4317                                 type = EventInfo.EventHandlerType;
4318                 }
4319
4320                 public string Name {
4321                         get {
4322                                 return EventInfo.Name;
4323                         }
4324                 }
4325
4326                 public bool IsInstance {
4327                         get {
4328                                 return !is_static;
4329                         }
4330                 }
4331
4332                 public bool IsStatic {
4333                         get {
4334                                 return is_static;
4335                         }
4336                 }
4337
4338                 public Type DeclaringType {
4339                         get {
4340                                 return EventInfo.DeclaringType;
4341                         }
4342                 }
4343
4344                 public Expression InstanceExpression {
4345                         get {
4346                                 return instance_expr;
4347                         }
4348
4349                         set {
4350                                 instance_expr = value;
4351                         }
4352                 }
4353
4354                 public override Expression DoResolve (EmitContext ec)
4355                 {
4356                         if (instance_expr != null) {
4357                                 instance_expr = instance_expr.DoResolve (ec);
4358                                 if (instance_expr == null)
4359                                         return null;
4360                         }
4361
4362                         return this;
4363                 }
4364
4365                 public override void Emit (EmitContext ec)
4366                 {
4367                         Report.Error (70, loc, "The event `" + Name + "' can only appear on the left hand side of += or -= (except on the defining type)");
4368                 }
4369
4370                 public void EmitAddOrRemove (EmitContext ec, Expression source)
4371                 {
4372                         Expression handler = ((Binary) source).Right;
4373
4374                         Argument arg = new Argument (handler, Argument.AType.Expression);
4375                         ArrayList args = new ArrayList ();
4376
4377                         args.Add (arg);
4378
4379                         if (((Binary) source).Oper == Binary.Operator.Addition)
4380                                 Invocation.EmitCall (
4381                                         ec, false, IsStatic, instance_expr, add_accessor, args, loc);
4382                         else
4383                                 Invocation.EmitCall (
4384                                         ec, false, IsStatic, instance_expr, remove_accessor, args, loc);
4385                 }
4386         }
4387 }