mcs/mcs/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 ((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                         if (target_type == TypeManager.object_type) {
 673                                 //
 674                                 // A pointer type cannot be converted to object
 675                                 //
 676                                 if (expr_type.IsPointer)
 677                                         return null;
 678
 679                                 if (expr_type.IsValueType)
 680                                         return new BoxedCast (expr);
 681                                 if (expr_type.IsClass || expr_type.IsInterface)
 682                                         return new EmptyCast (expr, target_type);
 683                         } else if (expr_type.IsSubclassOf (target_type)) {
 684                                 return new EmptyCast (expr, target_type);
 685                         } else {
 686
 687                                 // This code is kind of mirrored inside StandardConversionExists
 688                                 // with the small distinction that we only probe there
 689                                 //
 690                                 // Always ensure that the code here and there is in sync
 691
 692                                 // from the null type to any reference-type.
 693                                 if (expr is NullLiteral && !target_type.IsValueType)
 694                                         return new EmptyCast (expr, target_type);
 695
 696                                 // from any class-type S to any interface-type T.
 697                                 if (expr_type.IsClass && target_type.IsInterface) {
 698                                         if (TypeManager.ImplementsInterface (expr_type, target_type))
 699                                                 return new EmptyCast (expr, target_type);
 700                                         else
 701                                                 return null;
 702                                 }
 703
 704                                 // from any interface type S to interface-type T.
 705                                 if (expr_type.IsInterface && target_type.IsInterface) {
 706
 707                                         if (TypeManager.ImplementsInterface (expr_type, target_type))
 708                                                 return new EmptyCast (expr, target_type);
 709                                         else
 710                                                 return null;
 711                                 }
 712
 713                                 // from an array-type S to an array-type of type T
 714                                 if (expr_type.IsArray && target_type.IsArray) {
 715                                         if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
 716
 717                                                 Type expr_element_type = expr_type.GetElementType ();
 718
 719                                                 if (MyEmptyExpr == null)
 720                                                         MyEmptyExpr = new EmptyExpression ();
 721
 722                                                 MyEmptyExpr.SetType (expr_element_type);
 723                                                 Type target_element_type = target_type.GetElementType ();
 724
 725                                                 if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
 726                                                         if (StandardConversionExists (MyEmptyExpr,
 727                                                                                       target_element_type))
 728                                                                 return new EmptyCast (expr, target_type);
 729                                         }
 730                                 }
 731
 732
 733                                 // from an array-type to System.Array
 734                                 if (expr_type.IsArray && target_type == TypeManager.array_type)
 735                                         return new EmptyCast (expr, target_type);
 736
 737                                 // from any delegate type to System.Delegate
 738                                 if (expr_type.IsSubclassOf (TypeManager.delegate_type) &&
 739                                     target_type == TypeManager.delegate_type)
 740                                         return new EmptyCast (expr, target_type);
 741
 742                                 // from any array-type or delegate type into System.ICloneable.
 743                                 if (expr_type.IsArray || expr_type.IsSubclassOf (TypeManager.delegate_type))
 744                                         if (target_type == TypeManager.icloneable_type)
 745                                                 return new EmptyCast (expr, target_type);
 746
 747                                 return null;
 748
 749                         }
 750
 751                         return null;
 752                 }
 753
 754                 /// <summary>
 755                 ///   Handles expressions like this: decimal d; d = 1;
 756                 ///   and changes them into: decimal d; d = new System.Decimal (1);
 757                 /// </summary>
 758                 static Expression InternalTypeConstructor (EmitContext ec, Expression expr, Type target)
 759                 {
 760                         ArrayList args = new ArrayList ();
 761
 762                         args.Add (new Argument (expr, Argument.AType.Expression));
 763
 764                         Expression ne = new New (new TypeExpr (target, Location.Null), args, Location.Null);
 765
 766                         return ne.Resolve (ec);
 767                 }
 768
 769                 /// <summary>
 770                 ///   Implicit Numeric Conversions.
 771                 ///
 772                 ///   expr is the expression to convert, returns a new expression of type
 773                 ///   target_type or null if an implicit conversion is not possible.
 774                 /// </summary>
 775                 static public Expression ImplicitNumericConversion (EmitContext ec, Expression expr,
 776                                                                     Type target_type, Location loc)
 777                 {
 778                         Type expr_type = expr.Type;
 779
 780                         //
 781                         // Attempt to do the implicit constant expression conversions
 782
 783                         if (expr is IntConstant){
 784                                 Expression e;
 785
 786                                 e = TryImplicitIntConversion (target_type, (IntConstant) expr);
 787
 788                                 if (e != null)
 789                                         return e;
 790                         } else if (expr is LongConstant && target_type == TypeManager.uint64_type){
 791                                 //
 792                                 // Try the implicit constant expression conversion
 793                                 // from long to ulong, instead of a nice routine,
 794                                 // we just inline it
 795                                 //
 796                                 long v = ((LongConstant) expr).Value;
 797                                 if (v > 0)
 798                                         return new ULongConstant ((ulong) v);
 799                         }
 800
 801                         Type real_target_type = target_type;
 802
 803                         if (expr_type == TypeManager.sbyte_type){
 804                                 //
 805                                 // From sbyte to short, int, long, float, double.
 806                                 //
 807                                 if (real_target_type == TypeManager.int32_type)
 808                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 809                                 if (real_target_type == TypeManager.int64_type)
 810                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 811                                 if (real_target_type == TypeManager.double_type)
 812                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 813                                 if (real_target_type == TypeManager.float_type)
 814                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 815                                 if (real_target_type == TypeManager.short_type)
 816                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
 817                                 if (real_target_type == TypeManager.decimal_type)
 818                                         return InternalTypeConstructor (ec, expr, target_type);
 819                         } else if (expr_type == TypeManager.byte_type){
 820                                 //
 821                                 // From byte to short, ushort, int, uint, long, ulong, float, double
 822                                 //
 823                                 if ((real_target_type == TypeManager.short_type) ||
 824                                     (real_target_type == TypeManager.ushort_type) ||
 825                                     (real_target_type == TypeManager.int32_type) ||
 826                                     (real_target_type == TypeManager.uint32_type))
 827                                         return new EmptyCast (expr, target_type);
 828
 829                                 if (real_target_type == TypeManager.uint64_type)
 830                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 831                                 if (real_target_type == TypeManager.int64_type)
 832                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 833                                 if (real_target_type == TypeManager.float_type)
 834                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 835                                 if (real_target_type == TypeManager.double_type)
 836                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 837                                 if (real_target_type == TypeManager.decimal_type)
 838                                         return InternalTypeConstructor (ec, expr, target_type);
 839                         } else if (expr_type == TypeManager.short_type){
 840                                 //
 841                                 // From short to int, long, float, double
 842                                 //
 843                                 if (real_target_type == TypeManager.int32_type)
 844                                         return new EmptyCast (expr, target_type);
 845                                 if (real_target_type == TypeManager.int64_type)
 846                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 847                                 if (real_target_type == TypeManager.double_type)
 848                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 849                                 if (real_target_type == TypeManager.float_type)
 850                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 851                                 if (real_target_type == TypeManager.decimal_type)
 852                                         return InternalTypeConstructor (ec, expr, target_type);
 853                         } else if (expr_type == TypeManager.ushort_type){
 854                                 //
 855                                 // From ushort to int, uint, long, ulong, float, double
 856                                 //
 857                                 if (real_target_type == TypeManager.uint32_type)
 858                                         return new EmptyCast (expr, target_type);
 859
 860                                 if (real_target_type == TypeManager.uint64_type)
 861                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 862                                 if (real_target_type == TypeManager.int32_type)
 863                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 864                                 if (real_target_type == TypeManager.int64_type)
 865                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 866                                 if (real_target_type == TypeManager.double_type)
 867                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 868                                 if (real_target_type == TypeManager.float_type)
 869                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 870                                 if (real_target_type == TypeManager.decimal_type)
 871                                         return InternalTypeConstructor (ec, expr, target_type);
 872                         } else if (expr_type == TypeManager.int32_type){
 873                                 //
 874                                 // From int to long, float, double
 875                                 //
 876                                 if (real_target_type == TypeManager.int64_type)
 877                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 878                                 if (real_target_type == TypeManager.double_type)
 879                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 880                                 if (real_target_type == TypeManager.float_type)
 881                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 882                                 if (real_target_type == TypeManager.decimal_type)
 883                                         return InternalTypeConstructor (ec, expr, target_type);
 884                         } else if (expr_type == TypeManager.uint32_type){
 885                                 //
 886                                 // From uint to long, ulong, float, double
 887                                 //
 888                                 if (real_target_type == TypeManager.int64_type)
 889                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 890                                 if (real_target_type == TypeManager.uint64_type)
 891                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 892                                 if (real_target_type == TypeManager.double_type)
 893                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 894                                                                OpCodes.Conv_R8);
 895                                 if (real_target_type == TypeManager.float_type)
 896                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 897                                                                OpCodes.Conv_R4);
 898                                 if (real_target_type == TypeManager.decimal_type)
 899                                         return InternalTypeConstructor (ec, expr, target_type);
 900                         } else if (expr_type == TypeManager.int64_type){
 901                                 //
 902                                 // From long/ulong to float, double
 903                                 //
 904                                 if (real_target_type == TypeManager.double_type)
 905                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 906                                 if (real_target_type == TypeManager.float_type)
 907                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 908                                 if (real_target_type == TypeManager.decimal_type)
 909                                         return InternalTypeConstructor (ec, expr, target_type);
 910                         } else if (expr_type == TypeManager.uint64_type){
 911                                 //
 912                                 // From ulong to float, double
 913                                 //
 914                                 if (real_target_type == TypeManager.double_type)
 915                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 916                                                                OpCodes.Conv_R8);
 917                                 if (real_target_type == TypeManager.float_type)
 918                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 919                                                                OpCodes.Conv_R4);
 920                                 if (real_target_type == TypeManager.decimal_type)
 921                                         return InternalTypeConstructor (ec, expr, target_type);
 922                         } else if (expr_type == TypeManager.char_type){
 923                                 //
 924                                 // From char to ushort, int, uint, long, ulong, float, double
 925                                 //
 926                                 if ((real_target_type == TypeManager.ushort_type) ||
 927                                     (real_target_type == TypeManager.int32_type) ||
 928                                     (real_target_type == TypeManager.uint32_type))
 929                                         return new EmptyCast (expr, target_type);
 930                                 if (real_target_type == TypeManager.uint64_type)
 931                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 932                                 if (real_target_type == TypeManager.int64_type)
 933                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 934                                 if (real_target_type == TypeManager.float_type)
 935                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 936                                 if (real_target_type == TypeManager.double_type)
 937                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 938                                 if (real_target_type == TypeManager.decimal_type)
 939                                         return InternalTypeConstructor (ec, expr, target_type);
 940                         } else if (expr_type == TypeManager.float_type){
 941                                 //
 942                                 // float to double
 943                                 //
 944                                 if (real_target_type == TypeManager.double_type)
 945                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 946                         }
 947
 948                         return null;
 949                 }
 950
 951                 //
 952                 // Tests whether an implicit reference conversion exists between expr_type
 953                 // and target_type
 954                 //
 955                 public static bool ImplicitReferenceConversionExists (Expression expr, Type target_type)
 956                 {
 957                         Type expr_type = expr.Type;
 958
 959                         //
 960                         // This is the boxed case.
 961                         //
 962                         if (target_type == TypeManager.object_type) {
 963                                 if ((expr_type.IsClass) ||
 964                                     (expr_type.IsValueType) ||
 965                                     (expr_type.IsInterface))
 966                                         return true;
 967
 968                         } else if (expr_type.IsSubclassOf (target_type)) {
 969                                 return true;
 970
 971                         } else {
 972                                 // Please remember that all code below actually comes
 973                                 // from ImplicitReferenceConversion so make sure code remains in sync
 974
 975                                 // from any class-type S to any interface-type T.
 976                                 if (expr_type.IsClass && target_type.IsInterface) {
 977                                         if (TypeManager.ImplementsInterface (expr_type, target_type))
 978                                                 return true;
 979                                 }
 980
 981                                 // from any interface type S to interface-type T.
 982                                 if (expr_type.IsInterface && target_type.IsInterface)
 983                                         if (TypeManager.ImplementsInterface (expr_type, target_type))
 984                                                 return true;
 985
 986                                 // from an array-type S to an array-type of type T
 987                                 if (expr_type.IsArray && target_type.IsArray) {
 988                                         if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
 989
 990                                                 Type expr_element_type = expr_type.GetElementType ();
 991
 992                                                 if (MyEmptyExpr == null)
 993                                                         MyEmptyExpr = new EmptyExpression ();
 994
 995                                                 MyEmptyExpr.SetType (expr_element_type);
 996                                                 Type target_element_type = target_type.GetElementType ();
 997
 998                                                 if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
 999                                                         if (StandardConversionExists (MyEmptyExpr,
1000                                                                                       target_element_type))
1001                                                                 return true;
1002                                         }
1003                                 }
1004
1005                                 // from an array-type to System.Array
1006                                 if (expr_type.IsArray && (target_type == TypeManager.array_type))
1007                                         return true;
1008
1009                                 // from any delegate type to System.Delegate
1010                                 if (expr_type.IsSubclassOf (TypeManager.delegate_type) &&
1011                                     target_type == TypeManager.delegate_type)
1012                                         if (target_type.IsAssignableFrom (expr_type))
1013                                                 return true;
1014
1015                                 // from any array-type or delegate type into System.ICloneable.
1016                                 if (expr_type.IsArray || expr_type.IsSubclassOf (TypeManager.delegate_type))
1017                                         if (target_type == TypeManager.icloneable_type)
1018                                                 return true;
1019
1020                                 // from the null type to any reference-type.
1021                                 if (expr is NullLiteral && !target_type.IsValueType &&
1022                                     !TypeManager.IsEnumType (target_type))
1023                                         return true;
1024
1025                         }
1026
1027                         return false;
1028                 }
1029
1030                 /// <summary>
1031                 ///  Same as StandardConversionExists except that it also looks at
1032                 ///  implicit user defined conversions - needed for overload resolution
1033                 /// </summary>
1034                 public static bool ImplicitConversionExists (EmitContext ec, Expression expr, Type target_type)
1035                 {
1036                         if (StandardConversionExists (expr, target_type) == true)
1037                                 return true;
1038
1039                         Expression dummy = ImplicitUserConversion (ec, expr, target_type, Location.Null);
1040
1041                         if (dummy != null)
1042                                 return true;
1043
1044                         return false;
1045                 }
1046
1047                 /// <summary>
1048                 ///  Determines if a standard implicit conversion exists from
1049                 ///  expr_type to target_type
1050                 /// </summary>
1051                 public static bool StandardConversionExists (Expression expr, Type target_type)
1052                 {
1053                         Type expr_type = expr.Type;
1054
1055                         if (expr_type == TypeManager.void_type)
1056                                 return false;
1057
1058                         if (expr_type == target_type)
1059                                 return true;
1060
1061                         // First numeric conversions
1062
1063                         if (expr_type == TypeManager.sbyte_type){
1064                                 //
1065                                 // From sbyte to short, int, long, float, double.
1066                                 //
1067                                 if ((target_type == TypeManager.int32_type) ||
1068                                     (target_type == TypeManager.int64_type) ||
1069                                     (target_type == TypeManager.double_type) ||
1070                                     (target_type == TypeManager.float_type)  ||
1071                                     (target_type == TypeManager.short_type) ||
1072                                     (target_type == TypeManager.decimal_type))
1073                                         return true;
1074
1075                         } else if (expr_type == TypeManager.byte_type){
1076                                 //
1077                                 // From byte to short, ushort, int, uint, long, ulong, float, double
1078                                 //
1079                                 if ((target_type == TypeManager.short_type) ||
1080                                     (target_type == TypeManager.ushort_type) ||
1081                                     (target_type == TypeManager.int32_type) ||
1082                                     (target_type == TypeManager.uint32_type) ||
1083                                     (target_type == TypeManager.uint64_type) ||
1084                                     (target_type == TypeManager.int64_type) ||
1085                                     (target_type == TypeManager.float_type) ||
1086                                     (target_type == TypeManager.double_type) ||
1087                                     (target_type == TypeManager.decimal_type))
1088                                         return true;
1089
1090                         } else if (expr_type == TypeManager.short_type){
1091                                 //
1092                                 // From short to int, long, float, double
1093                                 //
1094                                 if ((target_type == TypeManager.int32_type) ||
1095                                     (target_type == TypeManager.int64_type) ||
1096                                     (target_type == TypeManager.double_type) ||
1097                                     (target_type == TypeManager.float_type) ||
1098                                     (target_type == TypeManager.decimal_type))
1099                                         return true;
1100
1101                         } else if (expr_type == TypeManager.ushort_type){
1102                                 //
1103                                 // From ushort to int, uint, long, ulong, float, double
1104                                 //
1105                                 if ((target_type == TypeManager.uint32_type) ||
1106                                     (target_type == TypeManager.uint64_type) ||
1107                                     (target_type == TypeManager.int32_type) ||
1108                                     (target_type == TypeManager.int64_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.int32_type){
1115                                 //
1116                                 // From int to long, float, double
1117                                 //
1118                                 if ((target_type == TypeManager.int64_type) ||
1119                                     (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.uint32_type){
1125                                 //
1126                                 // From uint to long, ulong, float, double
1127                                 //
1128                                 if ((target_type == TypeManager.int64_type) ||
1129                                     (target_type == TypeManager.uint64_type) ||
1130                                     (target_type == TypeManager.double_type) ||
1131                                     (target_type == TypeManager.float_type) ||
1132                                     (target_type == TypeManager.decimal_type))
1133                                         return true;
1134
1135                         } else if ((expr_type == TypeManager.uint64_type) ||
1136                                    (expr_type == TypeManager.int64_type)) {
1137                                 //
1138                                 // From long/ulong to float, double
1139                                 //
1140                                 if ((target_type == TypeManager.double_type) ||
1141                                     (target_type == TypeManager.float_type) ||
1142                                     (target_type == TypeManager.decimal_type))
1143                                         return true;
1144
1145                         } else if (expr_type == TypeManager.char_type){
1146                                 //
1147                                 // From char to ushort, int, uint, long, ulong, float, double
1148                                 //
1149                                 if ((target_type == TypeManager.ushort_type) ||
1150                                     (target_type == TypeManager.int32_type) ||
1151                                     (target_type == TypeManager.uint32_type) ||
1152                                     (target_type == TypeManager.uint64_type) ||
1153                                     (target_type == TypeManager.int64_type) ||
1154                                     (target_type == TypeManager.float_type) ||
1155                                     (target_type == TypeManager.double_type) ||
1156                                     (target_type == TypeManager.decimal_type))
1157                                         return true;
1158
1159                         } else if (expr_type == TypeManager.float_type){
1160                                 //
1161                                 // float to double
1162                                 //
1163                                 if (target_type == TypeManager.double_type)
1164                                         return true;
1165                         }
1166
1167                         if (ImplicitReferenceConversionExists (expr, target_type))
1168                                 return true;
1169
1170                         if (expr is IntConstant){
1171                                 int value = ((IntConstant) expr).Value;
1172
1173                                 if (target_type == TypeManager.sbyte_type){
1174                                         if (value >= SByte.MinValue && value <= SByte.MaxValue)
1175                                                 return true;
1176                                 } else if (target_type == TypeManager.byte_type){
1177                                         if (Byte.MinValue >= 0 && value <= Byte.MaxValue)
1178                                                 return true;
1179                                 } else if (target_type == TypeManager.short_type){
1180                                         if (value >= Int16.MinValue && value <= Int16.MaxValue)
1181                                                 return true;
1182                                 } else if (target_type == TypeManager.ushort_type){
1183                                         if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
1184                                                 return true;
1185                                 } else if (target_type == TypeManager.uint32_type){
1186                                         if (value >= 0)
1187                                                 return true;
1188                                 } else if (target_type == TypeManager.uint64_type){
1189                                          //
1190                                          // we can optimize this case: a positive int32
1191                                          // always fits on a uint64.  But we need an opcode
1192                                          // to do it.
1193                                          //
1194                                         if (value >= 0)
1195                                                 return true;
1196                                 }
1197
1198                                 if (value == 0 && expr is IntLiteral && TypeManager.IsEnumType (target_type))
1199                                         return true;
1200                         }
1201
1202                         if (expr is LongConstant && target_type == TypeManager.uint64_type){
1203                                 //
1204                                 // Try the implicit constant expression conversion
1205                                 // from long to ulong, instead of a nice routine,
1206                                 // we just inline it
1207                                 //
1208                                 long v = ((LongConstant) expr).Value;
1209                                 if (v > 0)
1210                                         return true;
1211                         }
1212
1213                         if (target_type.IsSubclassOf (TypeManager.enum_type) && expr is IntLiteral){
1214                                 IntLiteral i = (IntLiteral) expr;
1215
1216                                 if (i.Value == 0)
1217                                         return true;
1218                         }
1219
1220                         return false;
1221                 }
1222
1223                 //
1224                 // Used internally by FindMostEncompassedType, this is used
1225                 // to avoid creating lots of objects in the tight loop inside
1226                 // FindMostEncompassedType
1227                 //
1228                 static EmptyExpression priv_fmet_param;
1229
1230                 /// <summary>
1231                 ///  Finds "most encompassed type" according to the spec (13.4.2)
1232                 ///  amongst the methods in the MethodGroupExpr
1233                 /// </summary>
1234                 static Type FindMostEncompassedType (ArrayList types)
1235                 {
1236                         Type best = null;
1237
1238                         if (priv_fmet_param == null)
1239                                 priv_fmet_param = new EmptyExpression ();
1240
1241                         foreach (Type t in types){
1242                                 priv_fmet_param.SetType (t);
1243
1244                                 if (best == null) {
1245                                         best = t;
1246                                         continue;
1247                                 }
1248
1249                                 if (StandardConversionExists (priv_fmet_param, best))
1250                                         best = t;
1251                         }
1252
1253                         return best;
1254                 }
1255
1256                 //
1257                 // Used internally by FindMostEncompassingType, this is used
1258                 // to avoid creating lots of objects in the tight loop inside
1259                 // FindMostEncompassingType
1260                 //
1261                 static EmptyExpression priv_fmee_ret;
1262
1263                 /// <summary>
1264                 ///  Finds "most encompassing type" according to the spec (13.4.2)
1265                 ///  amongst the types in the given set
1266                 /// </summary>
1267                 static Type FindMostEncompassingType (ArrayList types)
1268                 {
1269                         Type best = null;
1270
1271                         if (priv_fmee_ret == null)
1272                                 priv_fmee_ret = new EmptyExpression ();
1273
1274                         foreach (Type t in types){
1275                                 priv_fmee_ret.SetType (best);
1276
1277                                 if (best == null) {
1278                                         best = t;
1279                                         continue;
1280                                 }
1281
1282                                 if (StandardConversionExists (priv_fmee_ret, t))
1283                                         best = t;
1284                         }
1285
1286                         return best;
1287                 }
1288
1289                 //
1290                 // Used to avoid creating too many objects
1291                 //
1292                 static EmptyExpression priv_fms_expr;
1293
1294                 /// <summary>
1295                 ///   Finds the most specific source Sx according to the rules of the spec (13.4.4)
1296                 ///   by making use of FindMostEncomp* methods. Applies the correct rules separately
1297                 ///   for explicit and implicit conversion operators.
1298                 /// </summary>
1299                 static public Type FindMostSpecificSource (MethodGroupExpr me, Expression source,
1300                                                            bool apply_explicit_conv_rules,
1301                                                            Location loc)
1302                 {
1303                         ArrayList src_types_set = new ArrayList ();
1304
1305                         if (priv_fms_expr == null)
1306                                 priv_fms_expr = new EmptyExpression ();
1307
1308                         //
1309                         // If any operator converts from S then Sx = S
1310                         //
1311                         Type source_type = source.Type;
1312                         foreach (MethodBase mb in me.Methods){
1313                                 ParameterData pd = Invocation.GetParameterData (mb);
1314                                 Type param_type = pd.ParameterType (0);
1315
1316                                 if (param_type == source_type)
1317                                         return param_type;
1318
1319                                 if (apply_explicit_conv_rules) {
1320                                         //
1321                                         // From the spec :
1322                                         // Find the set of applicable user-defined conversion operators, U.  This set
1323                                         // consists of the
1324                                         // user-defined implicit or explicit conversion operators declared by
1325                                         // the classes or structs in D that convert from a type encompassing
1326                                         // or encompassed by S to a type encompassing or encompassed by T
1327                                         //
1328                                         priv_fms_expr.SetType (param_type);
1329                                         if (StandardConversionExists (priv_fms_expr, source_type))
1330                                                 src_types_set.Add (param_type);
1331                                         else {
1332                                                 if (StandardConversionExists (source, param_type))
1333                                                         src_types_set.Add (param_type);
1334                                         }
1335                                 } else {
1336                                         //
1337                                         // Only if S is encompassed by param_type
1338                                         //
1339                                         if (StandardConversionExists (source, param_type))
1340                                                 src_types_set.Add (param_type);
1341                                 }
1342                         }
1343
1344                         //
1345                         // Explicit Conv rules
1346                         //
1347                         if (apply_explicit_conv_rules) {
1348                                 ArrayList candidate_set = new ArrayList ();
1349
1350                                 foreach (Type param_type in src_types_set){
1351                                         if (StandardConversionExists (source, param_type))
1352                                                 candidate_set.Add (param_type);
1353                                 }
1354
1355                                 if (candidate_set.Count != 0)
1356                                         return FindMostEncompassedType (candidate_set);
1357                         }
1358
1359                         //
1360                         // Final case
1361                         //
1362                         if (apply_explicit_conv_rules)
1363                                 return FindMostEncompassingType (src_types_set);
1364                         else
1365                                 return FindMostEncompassedType (src_types_set);
1366                 }
1367
1368                 //
1369                 // Useful in avoiding proliferation of objects
1370                 //
1371                 static EmptyExpression priv_fmt_expr;
1372
1373                 /// <summary>
1374                 ///  Finds the most specific target Tx according to section 13.4.4
1375                 /// </summary>
1376                 static public Type FindMostSpecificTarget (MethodGroupExpr me, Type target,
1377                                                            bool apply_explicit_conv_rules,
1378                                                            Location loc)
1379                 {
1380                         ArrayList tgt_types_set = new ArrayList ();
1381
1382                         if (priv_fmt_expr == null)
1383                                 priv_fmt_expr = new EmptyExpression ();
1384
1385                         //
1386                         // If any operator converts to T then Tx = T
1387                         //
1388                         foreach (MethodInfo mi in me.Methods){
1389                                 Type ret_type = mi.ReturnType;
1390
1391                                 if (ret_type == target)
1392                                         return ret_type;
1393
1394                                 if (apply_explicit_conv_rules) {
1395                                         //
1396                                         // From the spec :
1397                                         // Find the set of applicable user-defined conversion operators, U.
1398                                         //
1399                                         // This set consists of the
1400                                         // user-defined implicit or explicit conversion operators declared by
1401                                         // the classes or structs in D that convert from a type encompassing
1402                                         // or encompassed by S to a type encompassing or encompassed by T
1403                                         //
1404                                         priv_fms_expr.SetType (ret_type);
1405                                         if (StandardConversionExists (priv_fms_expr, target))
1406                                                 tgt_types_set.Add (ret_type);
1407                                         else {
1408                                                 priv_fms_expr.SetType (target);
1409                                                 if (StandardConversionExists (priv_fms_expr, ret_type))
1410                                                         tgt_types_set.Add (ret_type);
1411                                         }
1412                                 } else {
1413                                         //
1414                                         // Only if T is encompassed by param_type
1415                                         //
1416                                         priv_fms_expr.SetType (ret_type);
1417                                         if (StandardConversionExists (priv_fms_expr, target))
1418                                                 tgt_types_set.Add (ret_type);
1419                                 }
1420                         }
1421
1422                         //
1423                         // Explicit conv rules
1424                         //
1425                         if (apply_explicit_conv_rules) {
1426                                 ArrayList candidate_set = new ArrayList ();
1427
1428                                 foreach (Type ret_type in tgt_types_set){
1429                                         priv_fmt_expr.SetType (ret_type);
1430
1431                                         if (StandardConversionExists (priv_fmt_expr, target))
1432                                                 candidate_set.Add (ret_type);
1433                                 }
1434
1435                                 if (candidate_set.Count != 0)
1436                                         return FindMostEncompassingType (candidate_set);
1437                         }
1438
1439                         //
1440                         // Okay, final case !
1441                         //
1442                         if (apply_explicit_conv_rules)
1443                                 return FindMostEncompassedType (tgt_types_set);
1444                         else {
1445                                 Console.WriteLine ("Here with: " + tgt_types_set.Count);
1446                                 return FindMostEncompassingType (tgt_types_set);
1447                         }
1448                 }
1449
1450                 /// <summary>
1451                 ///  User-defined Implicit conversions
1452                 /// </summary>
1453                 static public Expression ImplicitUserConversion (EmitContext ec, Expression source,
1454                                                                  Type target, Location loc)
1455                 {
1456                         return UserDefinedConversion (ec, source, target, loc, false);
1457                 }
1458
1459                 /// <summary>
1460                 ///  User-defined Explicit conversions
1461                 /// </summary>
1462                 static public Expression ExplicitUserConversion (EmitContext ec, Expression source,
1463                                                                  Type target, Location loc)
1464                 {
1465                         return UserDefinedConversion (ec, source, target, loc, true);
1466                 }
1467
1468                 /// <summary>
1469                 ///   Computes the MethodGroup for the user-defined conversion
1470                 ///   operators from source_type to target_type.  `look_for_explicit'
1471                 ///   controls whether we should also include the list of explicit
1472                 ///   operators
1473                 /// </summary>
1474                 static MethodGroupExpr GetConversionOperators (EmitContext ec,
1475                                                                Type source_type, Type target_type,
1476                                                                Location loc, bool look_for_explicit)
1477                 {
1478                         Expression mg1 = null, mg2 = null;
1479                         Expression mg5 = null, mg6 = null, mg7 = null, mg8 = null;
1480                         string op_name;
1481
1482                         //
1483                         // FIXME : How does the False operator come into the picture ?
1484                         // This doesn't look complete and very correct !
1485                         //
1486                         if (target_type == TypeManager.bool_type && !look_for_explicit)
1487                                 op_name = "op_True";
1488                         else
1489                                 op_name = "op_Implicit";
1490
1491                         MethodGroupExpr union3;
1492
1493                         mg1 = MethodLookup (ec, source_type, op_name, loc);
1494                         if (source_type.BaseType != null)
1495                                 mg2 = MethodLookup (ec, source_type.BaseType, op_name, loc);
1496
1497                         if (mg1 == null)
1498                                 union3 = (MethodGroupExpr) mg2;
1499                         else if (mg2 == null)
1500                                 union3 = (MethodGroupExpr) mg1;
1501                         else
1502                                 union3 = Invocation.MakeUnionSet (mg1, mg2, loc);
1503
1504                         mg1 = MethodLookup (ec, target_type, op_name, loc);
1505                         if (mg1 != null){
1506                                 if (union3 != null)
1507                                         union3 = Invocation.MakeUnionSet (union3, mg1, loc);
1508                                 else
1509                                         union3 = (MethodGroupExpr) mg1;
1510                         }
1511
1512                         if (target_type.BaseType != null)
1513                                 mg1 = MethodLookup (ec, target_type.BaseType, op_name, loc);
1514
1515                         if (mg1 != null){
1516                                 if (union3 != null)
1517                                         union3 = Invocation.MakeUnionSet (union3, mg1, loc);
1518                                 else
1519                                         union3 = (MethodGroupExpr) mg1;
1520                         }
1521
1522                         MethodGroupExpr union4 = null;
1523
1524                         if (look_for_explicit) {
1525                                 op_name = "op_Explicit";
1526
1527                                 mg5 = MemberLookup (ec, source_type, op_name, loc);
1528                                 if (source_type.BaseType != null)
1529                                         mg6 = MethodLookup (ec, source_type.BaseType, op_name, loc);
1530
1531                                 mg7 = MemberLookup (ec, target_type, op_name, loc);
1532                                 if (target_type.BaseType != null)
1533                                         mg8 = MethodLookup (ec, target_type.BaseType, op_name, loc);
1534
1535                                 MethodGroupExpr union5 = Invocation.MakeUnionSet (mg5, mg6, loc);
1536                                 MethodGroupExpr union6 = Invocation.MakeUnionSet (mg7, mg8, loc);
1537
1538                                 union4 = Invocation.MakeUnionSet (union5, union6, loc);
1539                         }
1540
1541                         return Invocation.MakeUnionSet (union3, union4, loc);
1542                 }
1543
1544                 /// <summary>
1545                 ///   User-defined conversions
1546                 /// </summary>
1547                 static public Expression UserDefinedConversion (EmitContext ec, Expression source,
1548                                                                 Type target, Location loc,
1549                                                                 bool look_for_explicit)
1550                 {
1551                         MethodGroupExpr union;
1552                         Type source_type = source.Type;
1553                         MethodBase method = null;
1554
1555                         union = GetConversionOperators (ec, source_type, target, loc, look_for_explicit);
1556                         if (union == null)
1557                                 return null;
1558
1559                         Type most_specific_source, most_specific_target;
1560
1561 #if BLAH
1562                         foreach (MethodBase m in union.Methods){
1563                                 Console.WriteLine ("Name: " + m.Name);
1564                                 Console.WriteLine ("    : " + ((MethodInfo)m).ReturnType);
1565                         }
1566 #endif
1567
1568                         most_specific_source = FindMostSpecificSource (union, source, look_for_explicit, loc);
1569                         if (most_specific_source == null)
1570                                 return null;
1571
1572                         most_specific_target = FindMostSpecificTarget (union, target, look_for_explicit, loc);
1573                         if (most_specific_target == null)
1574                                 return null;
1575
1576                         int count = 0;
1577
1578                         foreach (MethodBase mb in union.Methods){
1579                                 ParameterData pd = Invocation.GetParameterData (mb);
1580                                 MethodInfo mi = (MethodInfo) mb;
1581
1582                                 if (pd.ParameterType (0) == most_specific_source &&
1583                                     mi.ReturnType == most_specific_target) {
1584                                         method = mb;
1585                                         count++;
1586                                 }
1587                         }
1588
1589                         if (method == null || count > 1) {
1590                                 Report.Error (-11, loc, "Ambiguous user defined conversion");
1591                                 return null;
1592                         }
1593
1594                         //
1595                         // This will do the conversion to the best match that we
1596                         // found.  Now we need to perform an implict standard conversion
1597                         // if the best match was not the type that we were requested
1598                         // by target.
1599                         //
1600                         if (look_for_explicit)
1601                                 source = ConvertExplicitStandard (ec, source, most_specific_source, loc);
1602                         else
1603                                 source = ConvertImplicitStandard (ec, source, most_specific_source, loc);
1604
1605                         if (source == null)
1606                                 return null;
1607
1608                         Expression e;
1609                         e =  new UserCast ((MethodInfo) method, source, loc);
1610                         if (e.Type != target){
1611                                 if (!look_for_explicit)
1612                                         e = ConvertImplicitStandard (ec, e, target, loc);
1613                                 else
1614                                         e = ConvertExplicitStandard (ec, e, target, loc);
1615                         }
1616                         return e;
1617                 }
1618
1619                 /// <summary>
1620                 ///   Converts implicitly the resolved expression `expr' into the
1621                 ///   `target_type'.  It returns a new expression that can be used
1622                 ///   in a context that expects a `target_type'.
1623                 /// </summary>
1624                 static public Expression ConvertImplicit (EmitContext ec, Expression expr,
1625                                                           Type target_type, Location loc)
1626                 {
1627                         Type expr_type = expr.Type;
1628                         Expression e;
1629
1630                         if (expr_type == target_type)
1631                                 return expr;
1632
1633                         if (target_type == null)
1634                                 throw new Exception ("Target type is null");
1635
1636                         e = ConvertImplicitStandard (ec, expr, target_type, loc);
1637                         if (e != null)
1638                                 return e;
1639
1640                         e = ImplicitUserConversion (ec, expr, target_type, loc);
1641                         if (e != null)
1642                                 return e;
1643
1644                         return null;
1645                 }
1646
1647
1648                 /// <summary>
1649                 ///   Attempts to apply the `Standard Implicit
1650                 ///   Conversion' rules to the expression `expr' into
1651                 ///   the `target_type'.  It returns a new expression
1652                 ///   that can be used in a context that expects a
1653                 ///   `target_type'.
1654                 ///
1655                 ///   This is different from `ConvertImplicit' in that the
1656                 ///   user defined implicit conversions are excluded.
1657                 /// </summary>
1658                 static public Expression ConvertImplicitStandard (EmitContext ec, Expression expr,
1659                                                                   Type target_type, Location loc)
1660                 {
1661                         Type expr_type = expr.Type;
1662                         Expression e;
1663
1664                         if (expr_type == target_type)
1665                                 return expr;
1666
1667                         e = ImplicitNumericConversion (ec, expr, target_type, loc);
1668                         if (e != null)
1669                                 return e;
1670
1671                         e = ImplicitReferenceConversion (expr, target_type);
1672                         if (e != null)
1673                                 return e;
1674
1675                         if (target_type.IsSubclassOf (TypeManager.enum_type) && expr is IntLiteral){
1676                                 IntLiteral i = (IntLiteral) expr;
1677
1678                                 if (i.Value == 0)
1679                                         return new EmptyCast (expr, target_type);
1680                         }
1681
1682                         if (ec.InUnsafe) {
1683                                 if (expr_type.IsPointer){
1684                                         if (target_type == TypeManager.void_ptr_type)
1685                                                 return new EmptyCast (expr, target_type);
1686
1687                                         //
1688                                         // yep, comparing pointer types cant be done with
1689                                         // t1 == t2, we have to compare their element types.
1690                                         //
1691                                         if (target_type.IsPointer){
1692                                                 if (target_type.GetElementType()==expr_type.GetElementType())
1693                                                         return expr;
1694                                         }
1695                                 }
1696
1697                                 if (target_type.IsPointer){
1698                                         if (expr is NullLiteral)
1699                                                 return new EmptyCast (expr, target_type);
1700                                 }
1701                         }
1702
1703                         return null;
1704                 }
1705
1706                 /// <summary>
1707                 ///   Attemps to perform an implict constant conversion of the IntConstant
1708                 ///   into a different data type using casts (See Implicit Constant
1709                 ///   Expression Conversions)
1710                 /// </summary>
1711                 static protected Expression TryImplicitIntConversion (Type target_type, IntConstant ic)
1712                 {
1713                         int value = ic.Value;
1714
1715                         //
1716                         // FIXME: This could return constants instead of EmptyCasts
1717                         //
1718                         if (target_type == TypeManager.sbyte_type){
1719                                 if (value >= SByte.MinValue && value <= SByte.MaxValue)
1720                                         return new SByteConstant ((sbyte) value);
1721                         } else if (target_type == TypeManager.byte_type){
1722                                 if (Byte.MinValue >= 0 && value <= Byte.MaxValue)
1723                                         return new ByteConstant ((byte) value);
1724                         } else if (target_type == TypeManager.short_type){
1725                                 if (value >= Int16.MinValue && value <= Int16.MaxValue)
1726                                         return new ShortConstant ((short) value);
1727                         } else if (target_type == TypeManager.ushort_type){
1728                                 if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
1729                                         return new UShortConstant ((ushort) value);
1730                         } else if (target_type == TypeManager.uint32_type){
1731                                 if (value >= 0)
1732                                         return new UIntConstant ((uint) value);
1733                         } else if (target_type == TypeManager.uint64_type){
1734                                 //
1735                                 // we can optimize this case: a positive int32
1736                                 // always fits on a uint64.  But we need an opcode
1737                                 // to do it.
1738                                 //
1739                                 if (value >= 0)
1740                                         return new ULongConstant ((ulong) value);
1741                         }
1742
1743                         if (value == 0 && ic is IntLiteral && TypeManager.IsEnumType (target_type))
1744                                 return new EnumConstant (ic, target_type);
1745
1746                         return null;
1747                 }
1748
1749                 static public void Error_CannotConvertImplicit (Location loc, Type source, Type target)
1750                 {
1751                         string msg = "Cannot convert implicitly from `"+
1752                                 TypeManager.CSharpName (source) + "' to `" +
1753                                 TypeManager.CSharpName (target) + "'";
1754
1755                         Report.Error (29, loc, msg);
1756                 }
1757
1758                 /// <summary>
1759                 ///   Attemptes to implicityly convert `target' into `type', using
1760                 ///   ConvertImplicit.  If there is no implicit conversion, then
1761                 ///   an error is signaled
1762                 /// </summary>
1763                 static public Expression ConvertImplicitRequired (EmitContext ec, Expression source,
1764                                                                   Type target_type, Location loc)
1765                 {
1766                         Expression e;
1767
1768                         e = ConvertImplicit (ec, source, target_type, loc);
1769                         if (e != null)
1770                                 return e;
1771
1772                         if (source is DoubleLiteral && target_type == TypeManager.float_type){
1773                                 Report.Error (664, loc,
1774                                               "Double literal cannot be implicitly converted to " +
1775                                               "float type, use F suffix to create a float literal");
1776                         }
1777
1778                         Error_CannotConvertImplicit (loc, source.Type, target_type);
1779
1780                         return null;
1781                 }
1782
1783                 /// <summary>
1784                 ///   Performs the explicit numeric conversions
1785                 /// </summary>
1786                 static Expression ConvertNumericExplicit (EmitContext ec, Expression expr, Type target_type)
1787                 {
1788                         Type expr_type = expr.Type;
1789
1790                         //
1791                         // If we have an enumeration, extract the underlying type,
1792                         // use this during the comparison, but wrap around the original
1793                         // target_type
1794                         //
1795                         Type real_target_type = target_type;
1796
1797                         if (TypeManager.IsEnumType (real_target_type))
1798                                 real_target_type = TypeManager.EnumToUnderlying (real_target_type);
1799
1800                         if (StandardConversionExists (expr, real_target_type))
1801                                 return new EmptyCast (expr, target_type);
1802
1803                         if (expr_type == TypeManager.sbyte_type){
1804                                 //
1805                                 // From sbyte to byte, ushort, uint, ulong, char
1806                                 //
1807                                 if (real_target_type == TypeManager.byte_type)
1808                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U1);
1809                                 if (real_target_type == TypeManager.ushort_type)
1810                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U2);
1811                                 if (real_target_type == TypeManager.uint32_type)
1812                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U4);
1813                                 if (real_target_type == TypeManager.uint64_type)
1814                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U8);
1815                                 if (real_target_type == TypeManager.char_type)
1816                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_CH);
1817                         } else if (expr_type == TypeManager.byte_type){
1818                                 //
1819                                 // From byte to sbyte and char
1820                                 //
1821                                 if (real_target_type == TypeManager.sbyte_type)
1822                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U1_I1);
1823                                 if (real_target_type == TypeManager.char_type)
1824                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U1_CH);
1825                         } else if (expr_type == TypeManager.short_type){
1826                                 //
1827                                 // From short to sbyte, byte, ushort, uint, ulong, char
1828                                 //
1829                                 if (real_target_type == TypeManager.sbyte_type)
1830                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_I1);
1831                                 if (real_target_type == TypeManager.byte_type)
1832                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U1);
1833                                 if (real_target_type == TypeManager.ushort_type)
1834                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U2);
1835                                 if (real_target_type == TypeManager.uint32_type)
1836                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U4);
1837                                 if (real_target_type == TypeManager.uint64_type)
1838                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U8);
1839                                 if (real_target_type == TypeManager.char_type)
1840                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_CH);
1841                         } else if (expr_type == TypeManager.ushort_type){
1842                                 //
1843                                 // From ushort to sbyte, byte, short, char
1844                                 //
1845                                 if (real_target_type == TypeManager.sbyte_type)
1846                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_I1);
1847                                 if (real_target_type == TypeManager.byte_type)
1848                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_U1);
1849                                 if (real_target_type == TypeManager.short_type)
1850                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_I2);
1851                                 if (real_target_type == TypeManager.char_type)
1852                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_CH);
1853                         } else if (expr_type == TypeManager.int32_type){
1854                                 //
1855                                 // From int to sbyte, byte, short, ushort, uint, ulong, char
1856                                 //
1857                                 if (real_target_type == TypeManager.sbyte_type)
1858                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_I1);
1859                                 if (real_target_type == TypeManager.byte_type)
1860                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U1);
1861                                 if (real_target_type == TypeManager.short_type)
1862                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_I2);
1863                                 if (real_target_type == TypeManager.ushort_type)
1864                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U2);
1865                                 if (real_target_type == TypeManager.uint32_type)
1866                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U4);
1867                                 if (real_target_type == TypeManager.uint64_type)
1868                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U8);
1869                                 if (real_target_type == TypeManager.char_type)
1870                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_CH);
1871                         } else if (expr_type == TypeManager.uint32_type){
1872                                 //
1873                                 // From uint to sbyte, byte, short, ushort, int, char
1874                                 //
1875                                 if (real_target_type == TypeManager.sbyte_type)
1876                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_I1);
1877                                 if (real_target_type == TypeManager.byte_type)
1878                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_U1);
1879                                 if (real_target_type == TypeManager.short_type)
1880                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_I2);
1881                                 if (real_target_type == TypeManager.ushort_type)
1882                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_U2);
1883                                 if (real_target_type == TypeManager.int32_type)
1884                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_I4);
1885                                 if (real_target_type == TypeManager.char_type)
1886                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_CH);
1887                         } else if (expr_type == TypeManager.int64_type){
1888                                 //
1889                                 // From long to sbyte, byte, short, ushort, int, uint, ulong, char
1890                                 //
1891                                 if (real_target_type == TypeManager.sbyte_type)
1892                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I1);
1893                                 if (real_target_type == TypeManager.byte_type)
1894                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U1);
1895                                 if (real_target_type == TypeManager.short_type)
1896                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I2);
1897                                 if (real_target_type == TypeManager.ushort_type)
1898                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U2);
1899                                 if (real_target_type == TypeManager.int32_type)
1900                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I4);
1901                                 if (real_target_type == TypeManager.uint32_type)
1902                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U4);
1903                                 if (real_target_type == TypeManager.uint64_type)
1904                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U8);
1905                                 if (real_target_type == TypeManager.char_type)
1906                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_CH);
1907                         } else if (expr_type == TypeManager.uint64_type){
1908                                 //
1909                                 // From ulong to sbyte, byte, short, ushort, int, uint, long, char
1910                                 //
1911                                 if (real_target_type == TypeManager.sbyte_type)
1912                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I1);
1913                                 if (real_target_type == TypeManager.byte_type)
1914                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U1);
1915                                 if (real_target_type == TypeManager.short_type)
1916                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I2);
1917                                 if (real_target_type == TypeManager.ushort_type)
1918                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U2);
1919                                 if (real_target_type == TypeManager.int32_type)
1920                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I4);
1921                                 if (real_target_type == TypeManager.uint32_type)
1922                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U4);
1923                                 if (real_target_type == TypeManager.int64_type)
1924                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I8);
1925                                 if (real_target_type == TypeManager.char_type)
1926                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_CH);
1927                         } else if (expr_type == TypeManager.char_type){
1928                                 //
1929                                 // From char to sbyte, byte, short
1930                                 //
1931                                 if (real_target_type == TypeManager.sbyte_type)
1932                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.CH_I1);
1933                                 if (real_target_type == TypeManager.byte_type)
1934                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.CH_U1);
1935                                 if (real_target_type == TypeManager.short_type)
1936                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.CH_I2);
1937                         } else if (expr_type == TypeManager.float_type){
1938                                 //
1939                                 // From float to sbyte, byte, short,
1940                                 // ushort, int, uint, long, ulong, char
1941                                 // or decimal
1942                                 //
1943                                 if (real_target_type == TypeManager.sbyte_type)
1944                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_I1);
1945                                 if (real_target_type == TypeManager.byte_type)
1946                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_U1);
1947                                 if (real_target_type == TypeManager.short_type)
1948                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_I2);
1949                                 if (real_target_type == TypeManager.ushort_type)
1950                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_U2);
1951                                 if (real_target_type == TypeManager.int32_type)
1952                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_I4);
1953                                 if (real_target_type == TypeManager.uint32_type)
1954                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_U4);
1955                                 if (real_target_type == TypeManager.int64_type)
1956                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_I8);
1957                                 if (real_target_type == TypeManager.uint64_type)
1958                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_U8);
1959                                 if (real_target_type == TypeManager.char_type)
1960                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_CH);
1961                                 if (real_target_type == TypeManager.decimal_type)
1962                                         return InternalTypeConstructor (ec, expr, target_type);
1963                         } else if (expr_type == TypeManager.double_type){
1964                                 //
1965                                 // From double to byte, byte, short,
1966                                 // ushort, int, uint, long, ulong,
1967                                 // char, float or decimal
1968                                 //
1969                                 if (real_target_type == TypeManager.sbyte_type)
1970                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_I1);
1971                                 if (real_target_type == TypeManager.byte_type)
1972                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_U1);
1973                                 if (real_target_type == TypeManager.short_type)
1974                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_I2);
1975                                 if (real_target_type == TypeManager.ushort_type)
1976                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_U2);
1977                                 if (real_target_type == TypeManager.int32_type)
1978                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_I4);
1979                                 if (real_target_type == TypeManager.uint32_type)
1980                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_U4);
1981                                 if (real_target_type == TypeManager.int64_type)
1982                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_I8);
1983                                 if (real_target_type == TypeManager.uint64_type)
1984                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_U8);
1985                                 if (real_target_type == TypeManager.char_type)
1986                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_CH);
1987                                 if (real_target_type == TypeManager.float_type)
1988                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_R4);
1989                                 if (real_target_type == TypeManager.decimal_type)
1990                                         return InternalTypeConstructor (ec, expr, target_type);
1991                         }
1992
1993                         // decimal is taken care of by the op_Explicit methods.
1994
1995                         return null;
1996                 }
1997
1998                 /// <summary>
1999                 ///  Returns whether an explicit reference conversion can be performed
2000                 ///  from source_type to target_type
2001                 /// </summary>
2002                 public static bool ExplicitReferenceConversionExists (Type source_type, Type target_type)
2003                 {
2004                         bool target_is_value_type = target_type.IsValueType;
2005
2006                         if (source_type == target_type)
2007                                 return true;
2008
2009                         //
2010                         // From object to any reference type
2011                         //
2012                         if (source_type == TypeManager.object_type && !target_is_value_type)
2013                                 return true;
2014
2015                         //
2016                         // From any class S to any class-type T, provided S is a base class of T
2017                         //
2018                         if (target_type.IsSubclassOf (source_type))
2019                                 return true;
2020
2021                         //
2022                         // From any interface type S to any interface T provided S is not derived from T
2023                         //
2024                         if (source_type.IsInterface && target_type.IsInterface){
2025                                 if (!target_type.IsSubclassOf (source_type))
2026                                         return true;
2027                         }
2028
2029                         //
2030                         // From any class type S to any interface T, provided S is not sealed
2031                         // and provided S does not implement T.
2032                         //
2033                         if (target_type.IsInterface && !source_type.IsSealed &&
2034                             !TypeManager.ImplementsInterface (source_type, target_type))
2035                                 return true;
2036
2037                         //
2038                         // From any interface-type S to to any class type T, provided T is not
2039                         // sealed, or provided T implements S.
2040                         //
2041                         if (source_type.IsInterface &&
2042                             (!target_type.IsSealed || TypeManager.ImplementsInterface (target_type, source_type)))
2043                                 return true;
2044
2045
2046                         // From an array type S with an element type Se to an array type T with an
2047                         // element type Te provided all the following are true:
2048                         //     * S and T differe only in element type, in other words, S and T
2049                         //       have the same number of dimensions.
2050                         //     * Both Se and Te are reference types
2051                         //     * An explicit referenc conversions exist from Se to Te
2052                         //
2053                         if (source_type.IsArray && target_type.IsArray) {
2054                                 if (source_type.GetArrayRank () == target_type.GetArrayRank ()) {
2055
2056                                         Type source_element_type = source_type.GetElementType ();
2057                                         Type target_element_type = target_type.GetElementType ();
2058
2059                                         if (!source_element_type.IsValueType && !target_element_type.IsValueType)
2060                                                 if (ExplicitReferenceConversionExists (source_element_type,
2061                                                                                        target_element_type))
2062                                                         return true;
2063                                 }
2064                         }
2065
2066
2067                         // From System.Array to any array-type
2068                         if (source_type == TypeManager.array_type &&
2069                             target_type.IsArray){
2070                                 return true;
2071                         }
2072
2073                         //
2074                         // From System delegate to any delegate-type
2075                         //
2076                         if (source_type == TypeManager.delegate_type &&
2077                             target_type.IsSubclassOf (TypeManager.delegate_type))
2078                                 return true;
2079
2080                         //
2081                         // From ICloneable to Array or Delegate types
2082                         //
2083                         if (source_type == TypeManager.icloneable_type &&
2084                             (target_type == TypeManager.array_type ||
2085                              target_type == TypeManager.delegate_type))
2086                                 return true;
2087
2088                         return false;
2089                 }
2090
2091                 /// <summary>
2092                 ///   Implements Explicit Reference conversions
2093                 /// </summary>
2094                 static Expression ConvertReferenceExplicit (Expression source, Type target_type)
2095                 {
2096                         Type source_type = source.Type;
2097                         bool target_is_value_type = target_type.IsValueType;
2098
2099                         //
2100                         // From object to any reference type
2101                         //
2102                         if (source_type == TypeManager.object_type && !target_is_value_type)
2103                                 return new ClassCast (source, target_type);
2104
2105
2106                         //
2107                         // From any class S to any class-type T, provided S is a base class of T
2108                         //
2109                         if (target_type.IsSubclassOf (source_type))
2110                                 return new ClassCast (source, target_type);
2111
2112                         //
2113                         // From any interface type S to any interface T provided S is not derived from T
2114                         //
2115                         if (source_type.IsInterface && target_type.IsInterface){
2116                                 if (TypeManager.ImplementsInterface (source_type, target_type))
2117                                         return null;
2118                                 else
2119                                         return new ClassCast (source, target_type);
2120                         }
2121
2122                         //
2123                         // From any class type S to any interface T, provides S is not sealed
2124                         // and provided S does not implement T.
2125                         //
2126                         if (target_type.IsInterface && !source_type.IsSealed) {
2127                                 if (TypeManager.ImplementsInterface (source_type, target_type))
2128                                         return null;
2129                                 else
2130                                         return new ClassCast (source, target_type);
2131
2132                         }
2133
2134                         //
2135                         // From any interface-type S to to any class type T, provided T is not
2136                         // sealed, or provided T implements S.
2137                         //
2138                         if (source_type.IsInterface) {
2139                                 if (!target_type.IsSealed || TypeManager.ImplementsInterface (target_type, source_type))
2140                                         return new ClassCast (source, target_type);
2141                                 else
2142                                         return null;
2143                         }
2144
2145                         // From an array type S with an element type Se to an array type T with an
2146                         // element type Te provided all the following are true:
2147                         //     * S and T differe only in element type, in other words, S and T
2148                         //       have the same number of dimensions.
2149                         //     * Both Se and Te are reference types
2150                         //     * An explicit referenc conversions exist from Se to Te
2151                         //
2152                         if (source_type.IsArray && target_type.IsArray) {
2153                                 if (source_type.GetArrayRank () == target_type.GetArrayRank ()) {
2154
2155                                         Type source_element_type = source_type.GetElementType ();
2156                                         Type target_element_type = target_type.GetElementType ();
2157
2158                                         if (!source_element_type.IsValueType && !target_element_type.IsValueType)
2159                                                 if (ExplicitReferenceConversionExists (source_element_type,
2160                                                                                        target_element_type))
2161                                                         return new ClassCast (source, target_type);
2162                                 }
2163                         }
2164
2165
2166                         // From System.Array to any array-type
2167                         if (source_type == TypeManager.array_type &&
2168                             target_type.IsArray) {
2169                                 return new ClassCast (source, target_type);
2170                         }
2171
2172                         //
2173                         // From System delegate to any delegate-type
2174                         //
2175                         if (source_type == TypeManager.delegate_type &&
2176                             target_type.IsSubclassOf (TypeManager.delegate_type))
2177                                 return new ClassCast (source, target_type);
2178
2179                         //
2180                         // From ICloneable to Array or Delegate types
2181                         //
2182                         if (source_type == TypeManager.icloneable_type &&
2183                             (target_type == TypeManager.array_type ||
2184                              target_type == TypeManager.delegate_type))
2185                                 return new ClassCast (source, target_type);
2186
2187                         return null;
2188                 }
2189
2190                 /// <summary>
2191                 ///   Performs an explicit conversion of the expression `expr' whose
2192                 ///   type is expr.Type to `target_type'.
2193                 /// </summary>
2194                 static public Expression ConvertExplicit (EmitContext ec, Expression expr,
2195                                                           Type target_type, Location loc)
2196                 {
2197                         Type expr_type = expr.Type;
2198                         Expression ne = ConvertImplicitStandard (ec, expr, target_type, loc);
2199
2200                         if (ne != null)
2201                                 return ne;
2202
2203                         ne = ConvertNumericExplicit (ec, expr, target_type);
2204                         if (ne != null)
2205                                 return ne;
2206
2207                         //
2208                         // Unboxing conversion.
2209                         //
2210                         if (expr_type == TypeManager.object_type && target_type.IsValueType)
2211                                 return new UnboxCast (expr, target_type);
2212
2213                         //
2214                         // Enum types
2215                         //
2216                         if (expr_type.IsSubclassOf (TypeManager.enum_type)) {
2217                                 Expression e;
2218
2219                                 //
2220                                 // FIXME: Is there any reason we should have EnumConstant
2221                                 // dealt with here instead of just using always the
2222                                 // UnderlyingSystemType to wrap the type?
2223                                 //
2224                                 if (expr is EnumConstant)
2225                                         e = ((EnumConstant) expr).Child;
2226                                 else {
2227                                         e = new EmptyCast (expr, TypeManager.EnumToUnderlying (expr_type));
2228                                 }
2229
2230                                 Expression t = ConvertImplicit (ec, e, target_type, loc);
2231                                 if (t != null)
2232                                         return t;
2233
2234                                 return ConvertNumericExplicit (ec, e, target_type);
2235                         }
2236
2237                         ne = ConvertReferenceExplicit (expr, target_type);
2238                         if (ne != null)
2239                                 return ne;
2240
2241                         if (ec.InUnsafe){
2242                                 if (target_type.IsPointer){
2243                                         if (expr_type.IsPointer)
2244                                                 return new EmptyCast (expr, target_type);
2245
2246                                         if (expr_type == TypeManager.sbyte_type ||
2247                                             expr_type == TypeManager.byte_type ||
2248                                             expr_type == TypeManager.short_type ||
2249                                             expr_type == TypeManager.ushort_type ||
2250                                             expr_type == TypeManager.int32_type ||
2251                                             expr_type == TypeManager.uint32_type ||
2252                                             expr_type == TypeManager.uint64_type ||
2253                                             expr_type == TypeManager.int64_type)
2254                                                 return new OpcodeCast (expr, target_type, OpCodes.Conv_U);
2255                                 }
2256                                 if (expr_type.IsPointer){
2257                                         if (target_type == TypeManager.sbyte_type ||
2258                                             target_type == TypeManager.byte_type ||
2259                                             target_type == TypeManager.short_type ||
2260                                             target_type == TypeManager.ushort_type ||
2261                                             target_type == TypeManager.int32_type ||
2262                                             target_type == TypeManager.uint32_type ||
2263                                             target_type == TypeManager.uint64_type ||
2264                                             target_type == TypeManager.int64_type){
2265                                                 Expression e = new EmptyCast (expr, TypeManager.uint32_type);
2266                                                 Expression ci, ce;
2267
2268                                                 ci = ConvertImplicitStandard (ec, e, target_type, loc);
2269
2270                                                 if (ci != null)
2271                                                         return ci;
2272
2273                                                 ce = ConvertNumericExplicit (ec, e, target_type);
2274                                                 if (ce != null)
2275                                                         return ce;
2276                                                 //
2277                                                 // We should always be able to go from an uint32
2278                                                 // implicitly or explicitly to the other integral
2279                                                 // types
2280                                                 //
2281                                                 throw new Exception ("Internal compiler error");
2282                                         }
2283                                 }
2284                         }
2285
2286                         ne = ExplicitUserConversion (ec, expr, target_type, loc);
2287                         if (ne != null)
2288                                 return ne;
2289
2290                         Error_CannotConvertType (loc, expr_type, target_type);
2291                         return null;
2292                 }
2293
2294                 /// <summary>
2295                 ///   Same as ConvertExplicit, only it doesn't include user defined conversions
2296                 /// </summary>
2297                 static public Expression ConvertExplicitStandard (EmitContext ec, Expression expr,
2298                                                                   Type target_type, Location l)
2299                 {
2300                         Expression ne = ConvertImplicitStandard (ec, expr, target_type, l);
2301
2302                         if (ne != null)
2303                                 return ne;
2304
2305                         ne = ConvertNumericExplicit (ec, expr, target_type);
2306                         if (ne != null)
2307                                 return ne;
2308
2309                         ne = ConvertReferenceExplicit (expr, target_type);
2310                         if (ne != null)
2311                                 return ne;
2312
2313                         Error_CannotConvertType (l, expr.Type, target_type);
2314                         return null;
2315                 }
2316
2317                 static string ExprClassName (ExprClass c)
2318                 {
2319                         switch (c){
2320                         case ExprClass.Invalid:
2321                                 return "Invalid";
2322                         case ExprClass.Value:
2323                                 return "value";
2324                         case ExprClass.Variable:
2325                                 return "variable";
2326                         case ExprClass.Namespace:
2327                                 return "namespace";
2328                         case ExprClass.Type:
2329                                 return "type";
2330                         case ExprClass.MethodGroup:
2331                                 return "method group";
2332                         case ExprClass.PropertyAccess:
2333                                 return "property access";
2334                         case ExprClass.EventAccess:
2335                                 return "event access";
2336                         case ExprClass.IndexerAccess:
2337                                 return "indexer access";
2338                         case ExprClass.Nothing:
2339                                 return "null";
2340                         }
2341                         throw new Exception ("Should not happen");
2342                 }
2343
2344                 /// <summary>
2345                 ///   Reports that we were expecting `expr' to be of class `expected'
2346                 /// </summary>
2347                 public void Error118 (string expected)
2348                 {
2349                         string kind = "Unknown";
2350
2351                         kind = ExprClassName (eclass);
2352
2353                         Error (118, "Expression denotes a `" + kind +
2354                                "' where a `" + expected + "' was expected");
2355                 }
2356
2357                 public void Error118 (ResolveFlags flags)
2358                 {
2359                         ArrayList valid = new ArrayList (10);
2360
2361                         if ((flags & ResolveFlags.VariableOrValue) != 0) {
2362                                 valid.Add ("variable");
2363                                 valid.Add ("value");
2364                         }
2365
2366                         if ((flags & ResolveFlags.Type) != 0)
2367                                 valid.Add ("type");
2368
2369                         if ((flags & ResolveFlags.MethodGroup) != 0)
2370                                 valid.Add ("method group");
2371
2372                         if ((flags & ResolveFlags.SimpleName) != 0)
2373                                 valid.Add ("simple name");
2374
2375                         if (valid.Count == 0)
2376                                 valid.Add ("unknown");
2377
2378                         StringBuilder sb = new StringBuilder ();
2379                         for (int i = 0; i < valid.Count; i++) {
2380                                 if (i > 0)
2381                                         sb.Append (", ");
2382                                 else if (i == valid.Count)
2383                                         sb.Append (" or ");
2384                                 sb.Append (valid [i]);
2385                         }
2386
2387                         string kind = ExprClassName (eclass);
2388
2389                         Error (119, "Expression denotes a `" + kind + "' where " +
2390                                "a `" + sb.ToString () + "' was expected");
2391                 }
2392
2393                 static void Error_ConstantValueCannotBeConverted (Location l, string val, Type t)
2394                 {
2395                         Report.Error (31, l, "Constant value `" + val + "' cannot be converted to " +
2396                                       TypeManager.CSharpName (t));
2397                 }
2398
2399                 public static void UnsafeError (Location loc)
2400                 {
2401                         Report.Error (214, loc, "Pointers may only be used in an unsafe context");
2402                 }
2403
2404                 /// <summary>
2405                 ///   Converts the IntConstant, UIntConstant, LongConstant or
2406                 ///   ULongConstant into the integral target_type.   Notice
2407                 ///   that we do not return an `Expression' we do return
2408                 ///   a boxed integral type.
2409                 ///
2410                 ///   FIXME: Since I added the new constants, we need to
2411                 ///   also support conversions from CharConstant, ByteConstant,
2412                 ///   SByteConstant, UShortConstant, ShortConstant
2413                 ///
2414                 ///   This is used by the switch statement, so the domain
2415                 ///   of work is restricted to the literals above, and the
2416                 ///   targets are int32, uint32, char, byte, sbyte, ushort,
2417                 ///   short, uint64 and int64
2418                 /// </summary>
2419                 public static object ConvertIntLiteral (Constant c, Type target_type, Location loc)
2420                 {
2421                         string s = "";
2422
2423                         if (c.Type == target_type)
2424                                 return ((Constant) c).GetValue ();
2425
2426                         //
2427                         // Make into one of the literals we handle, we dont really care
2428                         // about this value as we will just return a few limited types
2429                         //
2430                         if (c is EnumConstant)
2431                                 c = ((EnumConstant)c).WidenToCompilerConstant ();
2432
2433                         if (c is IntConstant){
2434                                 int v = ((IntConstant) c).Value;
2435
2436                                 if (target_type == TypeManager.uint32_type){
2437                                         if (v >= 0)
2438                                                 return (uint) v;
2439                                 } else if (target_type == TypeManager.char_type){
2440                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2441                                                 return (char) v;
2442                                 } else if (target_type == TypeManager.byte_type){
2443                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2444                                                 return (byte) v;
2445                                 } else if (target_type == TypeManager.sbyte_type){
2446                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
2447                                                 return (sbyte) v;
2448                                 } else if (target_type == TypeManager.short_type){
2449                                         if (v >= Int16.MinValue && v <= UInt16.MaxValue)
2450                                                 return (short) v;
2451                                 } else if (target_type == TypeManager.ushort_type){
2452                                         if (v >= UInt16.MinValue && v <= UInt16.MaxValue)
2453                                                 return (ushort) v;
2454                                 } else if (target_type == TypeManager.int64_type)
2455                                         return (long) v;
2456                                 else if (target_type == TypeManager.uint64_type){
2457                                         if (v > 0)
2458                                                 return (ulong) v;
2459                                 }
2460
2461                                 s = v.ToString ();
2462                         } else if (c is UIntConstant){
2463                                 uint v = ((UIntConstant) c).Value;
2464
2465                                 if (target_type == TypeManager.int32_type){
2466                                         if (v <= Int32.MaxValue)
2467                                                 return (int) v;
2468                                 } else if (target_type == TypeManager.char_type){
2469                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2470                                                 return (char) v;
2471                                 } else if (target_type == TypeManager.byte_type){
2472                                         if (v <= Byte.MaxValue)
2473                                                 return (byte) v;
2474                                 } else if (target_type == TypeManager.sbyte_type){
2475                                         if (v <= SByte.MaxValue)
2476                                                 return (sbyte) v;
2477                                 } else if (target_type == TypeManager.short_type){
2478                                         if (v <= UInt16.MaxValue)
2479                                                 return (short) v;
2480                                 } else if (target_type == TypeManager.ushort_type){
2481                                         if (v <= UInt16.MaxValue)
2482                                                 return (ushort) v;
2483                                 } else if (target_type == TypeManager.int64_type)
2484                                         return (long) v;
2485                                 else if (target_type == TypeManager.uint64_type)
2486                                         return (ulong) v;
2487                                 s = v.ToString ();
2488                         } else if (c is LongConstant){
2489                                 long v = ((LongConstant) c).Value;
2490
2491                                 if (target_type == TypeManager.int32_type){
2492                                         if (v >= UInt32.MinValue && v <= UInt32.MaxValue)
2493                                                 return (int) v;
2494                                 } else if (target_type == TypeManager.uint32_type){
2495                                         if (v >= 0 && v <= UInt32.MaxValue)
2496                                                 return (uint) v;
2497                                 } else if (target_type == TypeManager.char_type){
2498                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2499                                                 return (char) v;
2500                                 } else if (target_type == TypeManager.byte_type){
2501                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2502                                                 return (byte) v;
2503                                 } else if (target_type == TypeManager.sbyte_type){
2504                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
2505                                                 return (sbyte) v;
2506                                 } else if (target_type == TypeManager.short_type){
2507                                         if (v >= Int16.MinValue && v <= UInt16.MaxValue)
2508                                                 return (short) v;
2509                                 } else if (target_type == TypeManager.ushort_type){
2510                                         if (v >= UInt16.MinValue && v <= UInt16.MaxValue)
2511                                                 return (ushort) v;
2512                                 } else if (target_type == TypeManager.uint64_type){
2513                                         if (v > 0)
2514                                                 return (ulong) v;
2515                                 }
2516                                 s = v.ToString ();
2517                         } else if (c is ULongConstant){
2518                                 ulong v = ((ULongConstant) c).Value;
2519
2520                                 if (target_type == TypeManager.int32_type){
2521                                         if (v <= Int32.MaxValue)
2522                                                 return (int) v;
2523                                 } else if (target_type == TypeManager.uint32_type){
2524                                         if (v <= UInt32.MaxValue)
2525                                                 return (uint) v;
2526                                 } else if (target_type == TypeManager.char_type){
2527                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2528                                                 return (char) v;
2529                                 } else if (target_type == TypeManager.byte_type){
2530                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2531                                                 return (byte) v;
2532                                 } else if (target_type == TypeManager.sbyte_type){
2533                                         if (v <= (int) SByte.MaxValue)
2534                                                 return (sbyte) v;
2535                                 } else if (target_type == TypeManager.short_type){
2536                                         if (v <= UInt16.MaxValue)
2537                                                 return (short) v;
2538                                 } else if (target_type == TypeManager.ushort_type){
2539                                         if (v <= UInt16.MaxValue)
2540                                                 return (ushort) v;
2541                                 } else if (target_type == TypeManager.int64_type){
2542                                         if (v <= Int64.MaxValue)
2543                                                 return (long) v;
2544                                 }
2545                                 s = v.ToString ();
2546                         } else if (c is ByteConstant){
2547                                 byte v = ((ByteConstant) c).Value;
2548
2549                                 if (target_type == TypeManager.int32_type)
2550                                         return (int) v;
2551                                 else if (target_type == TypeManager.uint32_type)
2552                                         return (uint) v;
2553                                 else if (target_type == TypeManager.char_type)
2554                                         return (char) v;
2555                                 else if (target_type == TypeManager.sbyte_type){
2556                                         if (v <= SByte.MaxValue)
2557                                                 return (sbyte) v;
2558                                 } else if (target_type == TypeManager.short_type)
2559                                         return (short) v;
2560                                 else if (target_type == TypeManager.ushort_type)
2561                                         return (ushort) v;
2562                                 else if (target_type == TypeManager.int64_type)
2563                                         return (long) v;
2564                                 else if (target_type == TypeManager.uint64_type)
2565                                         return (ulong) v;
2566                                 s = v.ToString ();
2567                         } else if (c is SByteConstant){
2568                                 sbyte v = ((SByteConstant) c).Value;
2569
2570                                 if (target_type == TypeManager.int32_type)
2571                                         return (int) v;
2572                                 else if (target_type == TypeManager.uint32_type){
2573                                         if (v >= 0)
2574                                                 return (uint) v;
2575                                 } else if (target_type == TypeManager.char_type){
2576                                         if (v >= 0)
2577                                                 return (char) v;
2578                                 } else if (target_type == TypeManager.byte_type){
2579                                         if (v >= 0)
2580                                                 return (byte) v;
2581                                 } else if (target_type == TypeManager.short_type)
2582                                         return (short) v;
2583                                 else if (target_type == TypeManager.ushort_type){
2584                                         if (v >= 0)
2585                                                 return (ushort) v;
2586                                 } else if (target_type == TypeManager.int64_type)
2587                                         return (long) v;
2588                                 else if (target_type == TypeManager.uint64_type){
2589                                         if (v >= 0)
2590                                                 return (ulong) v;
2591                                 }
2592                                 s = v.ToString ();
2593                         } else if (c is ShortConstant){
2594                                 short v = ((ShortConstant) c).Value;
2595
2596                                 if (target_type == TypeManager.int32_type){
2597                                         return (int) v;
2598                                 } else if (target_type == TypeManager.uint32_type){
2599                                         if (v >= 0)
2600                                                 return (uint) v;
2601                                 } else if (target_type == TypeManager.char_type){
2602                                         if (v >= 0)
2603                                                 return (char) v;
2604                                 } else if (target_type == TypeManager.byte_type){
2605                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2606                                                 return (byte) v;
2607                                 } else if (target_type == TypeManager.sbyte_type){
2608                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
2609                                                 return (sbyte) v;
2610                                 } else if (target_type == TypeManager.ushort_type){
2611                                         if (v >= 0)
2612                                                 return (ushort) v;
2613                                 } else if (target_type == TypeManager.int64_type)
2614                                         return (long) v;
2615                                 else if (target_type == TypeManager.uint64_type)
2616                                         return (ulong) v;
2617
2618                                 s = v.ToString ();
2619                         } else if (c is UShortConstant){
2620                                 ushort v = ((UShortConstant) c).Value;
2621
2622                                 if (target_type == TypeManager.int32_type)
2623                                         return (int) v;
2624                                 else if (target_type == TypeManager.uint32_type)
2625                                         return (uint) v;
2626                                 else if (target_type == TypeManager.char_type){
2627                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2628                                                 return (char) v;
2629                                 } else if (target_type == TypeManager.byte_type){
2630                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2631                                                 return (byte) v;
2632                                 } else if (target_type == TypeManager.sbyte_type){
2633                                         if (v <= SByte.MaxValue)
2634                                                 return (byte) v;
2635                                 } else if (target_type == TypeManager.short_type){
2636                                         if (v <= Int16.MaxValue)
2637                                                 return (short) v;
2638                                 } else if (target_type == TypeManager.int64_type)
2639                                         return (long) v;
2640                                 else if (target_type == TypeManager.uint64_type)
2641                                         return (ulong) v;
2642
2643                                 s = v.ToString ();
2644                         } else if (c is CharConstant){
2645                                 char v = ((CharConstant) c).Value;
2646
2647                                 if (target_type == TypeManager.int32_type)
2648                                         return (int) v;
2649                                 else if (target_type == TypeManager.uint32_type)
2650                                         return (uint) v;
2651                                 else if (target_type == TypeManager.byte_type){
2652                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2653                                                 return (byte) v;
2654                                 } else if (target_type == TypeManager.sbyte_type){
2655                                         if (v <= SByte.MaxValue)
2656                                                 return (sbyte) v;
2657                                 } else if (target_type == TypeManager.short_type){
2658                                         if (v <= Int16.MaxValue)
2659                                                 return (short) v;
2660                                 } else if (target_type == TypeManager.ushort_type)
2661                                         return (short) v;
2662                                 else if (target_type == TypeManager.int64_type)
2663                                         return (long) v;
2664                                 else if (target_type == TypeManager.uint64_type)
2665                                         return (ulong) v;
2666
2667                                 s = v.ToString ();
2668                         }
2669                         Error_ConstantValueCannotBeConverted (loc, s, target_type);
2670                         return null;
2671                 }
2672
2673                 //
2674                 // Load the object from the pointer.
2675                 //
2676                 public static void LoadFromPtr (ILGenerator ig, Type t)
2677                 {
2678                         if (t == TypeManager.int32_type)
2679                                 ig.Emit (OpCodes.Ldind_I4);
2680                         else if (t == TypeManager.uint32_type)
2681                                 ig.Emit (OpCodes.Ldind_U4);
2682                         else if (t == TypeManager.short_type)
2683                                 ig.Emit (OpCodes.Ldind_I2);
2684                         else if (t == TypeManager.ushort_type)
2685                                 ig.Emit (OpCodes.Ldind_U2);
2686                         else if (t == TypeManager.char_type)
2687                                 ig.Emit (OpCodes.Ldind_U2);
2688                         else if (t == TypeManager.byte_type)
2689                                 ig.Emit (OpCodes.Ldind_U1);
2690                         else if (t == TypeManager.sbyte_type)
2691                                 ig.Emit (OpCodes.Ldind_I1);
2692                         else if (t == TypeManager.uint64_type)
2693                                 ig.Emit (OpCodes.Ldind_I8);
2694                         else if (t == TypeManager.int64_type)
2695                                 ig.Emit (OpCodes.Ldind_I8);
2696                         else if (t == TypeManager.float_type)
2697                                 ig.Emit (OpCodes.Ldind_R4);
2698                         else if (t == TypeManager.double_type)
2699                                 ig.Emit (OpCodes.Ldind_R8);
2700                         else if (t == TypeManager.bool_type)
2701                                 ig.Emit (OpCodes.Ldind_I1);
2702                         else if (t == TypeManager.intptr_type)
2703                                 ig.Emit (OpCodes.Ldind_I);
2704                         else if (TypeManager.IsEnumType (t)) {
2705                                 if (t == TypeManager.enum_type)
2706                                         ig.Emit (OpCodes.Ldind_Ref);
2707                                 else
2708                                         LoadFromPtr (ig, TypeManager.EnumToUnderlying (t));
2709                         } else if (t.IsValueType)
2710                                 ig.Emit (OpCodes.Ldobj, t);
2711                         else
2712                                 ig.Emit (OpCodes.Ldind_Ref);
2713                 }
2714
2715                 //
2716                 // The stack contains the pointer and the value of type `type'
2717                 //
2718                 public static void StoreFromPtr (ILGenerator ig, Type type)
2719                 {
2720                         if (type.IsEnum)
2721                                 type = TypeManager.EnumToUnderlying (type);
2722                         if (type == TypeManager.int32_type || type == TypeManager.uint32_type)
2723                                 ig.Emit (OpCodes.Stind_I4);
2724                         else if (type == TypeManager.int64_type || type == TypeManager.uint64_type)
2725                                 ig.Emit (OpCodes.Stind_I8);
2726                         else if (type == TypeManager.char_type || type == TypeManager.short_type ||
2727                                  type == TypeManager.ushort_type)
2728                                 ig.Emit (OpCodes.Stind_I2);
2729                         else if (type == TypeManager.float_type)
2730                                 ig.Emit (OpCodes.Stind_R4);
2731                         else if (type == TypeManager.double_type)
2732                                 ig.Emit (OpCodes.Stind_R8);
2733                         else if (type == TypeManager.byte_type || type == TypeManager.sbyte_type ||
2734                                  type == TypeManager.bool_type)
2735                                 ig.Emit (OpCodes.Stind_I1);
2736                         else if (type == TypeManager.intptr_type)
2737                                 ig.Emit (OpCodes.Stind_I);
2738                         else if (type.IsValueType)
2739                                 ig.Emit (OpCodes.Stobj, type);
2740                         else
2741                                 ig.Emit (OpCodes.Stind_Ref);
2742                 }
2743
2744                 //
2745                 // Returns the size of type `t' if known, otherwise, 0
2746                 //
2747                 public static int GetTypeSize (Type t)
2748                 {
2749                         t = TypeManager.TypeToCoreType (t);
2750                         if (t == TypeManager.int32_type ||
2751                             t == TypeManager.uint32_type ||
2752                             t == TypeManager.float_type)
2753                                 return 4;
2754                         else if (t == TypeManager.int64_type ||
2755                                  t == TypeManager.uint64_type ||
2756                                  t == TypeManager.double_type)
2757                                 return 8;
2758                         else if (t == TypeManager.byte_type ||
2759                                  t == TypeManager.sbyte_type ||
2760                                  t == TypeManager.bool_type)
2761                                 return 1;
2762                         else if (t == TypeManager.short_type ||
2763                                  t == TypeManager.char_type ||
2764                                  t == TypeManager.ushort_type)
2765                                 return 2;
2766                         else
2767                                 return 0;
2768                 }
2769
2770                 //
2771                 // Default implementation of IAssignMethod.CacheTemporaries
2772                 //
2773                 public void CacheTemporaries (EmitContext ec)
2774                 {
2775                 }
2776
2777                 static void Error_NegativeArrayIndex (Location loc)
2778                 {
2779                         Report.Error (284, loc, "Can not create array with a negative size");
2780                 }
2781
2782                 //
2783                 // Converts `source' to an int, uint, long or ulong.
2784                 //
2785                 public Expression ExpressionToArrayArgument (EmitContext ec, Expression source, Location loc)
2786                 {
2787                         Expression target;
2788
2789                         bool old_checked = ec.CheckState;
2790                         ec.CheckState = true;
2791
2792                         target = ConvertImplicit (ec, source, TypeManager.int32_type, loc);
2793                         if (target == null){
2794                                 target = ConvertImplicit (ec, source, TypeManager.uint32_type, loc);
2795                                 if (target == null){
2796                                         target = ConvertImplicit (ec, source, TypeManager.int64_type, loc);
2797                                         if (target == null){
2798                                                 target = ConvertImplicit (ec, source, TypeManager.uint64_type, loc);
2799                                                 if (target == null)
2800                                                         Expression.Error_CannotConvertImplicit (loc, source.Type, TypeManager.int32_type);
2801                                         }
2802                                 }
2803                         }
2804                         ec.CheckState = old_checked;
2805
2806                         //
2807                         // Only positive constants are allowed at compile time
2808                         //
2809                         if (target is Constant){
2810                                 if (target is IntConstant){
2811                                         if (((IntConstant) target).Value < 0){
2812                                                 Error_NegativeArrayIndex (loc);
2813                                                 return null;
2814                                         }
2815                                 }
2816
2817                                 if (target is LongConstant){
2818                                         if (((LongConstant) target).Value < 0){
2819                                                 Error_NegativeArrayIndex (loc);
2820                                                 return null;
2821                                         }
2822                                 }
2823
2824                         }
2825
2826                         return target;
2827                 }
2828
2829         }
2830
2831         /// <summary>
2832         ///   This is just a base class for expressions that can
2833         ///   appear on statements (invocations, object creation,
2834         ///   assignments, post/pre increment and decrement).  The idea
2835         ///   being that they would support an extra Emition interface that
2836         ///   does not leave a result on the stack.
2837         /// </summary>
2838         public abstract class ExpressionStatement : Expression {
2839
2840                 /// <summary>
2841                 ///   Requests the expression to be emitted in a `statement'
2842                 ///   context.  This means that no new value is left on the
2843                 ///   stack after invoking this method (constrasted with
2844                 ///   Emit that will always leave a value on the stack).
2845                 /// </summary>
2846                 public abstract void EmitStatement (EmitContext ec);
2847         }
2848
2849         /// <summary>
2850         ///   This kind of cast is used to encapsulate the child
2851         ///   whose type is child.Type into an expression that is
2852         ///   reported to return "return_type".  This is used to encapsulate
2853         ///   expressions which have compatible types, but need to be dealt
2854         ///   at higher levels with.
2855         ///
2856         ///   For example, a "byte" expression could be encapsulated in one
2857         ///   of these as an "unsigned int".  The type for the expression
2858         ///   would be "unsigned int".
2859         ///
2860         /// </summary>
2861         public class EmptyCast : Expression {
2862                 protected Expression child;
2863
2864                 public EmptyCast (Expression child, Type return_type)
2865                 {
2866                         eclass = child.eclass;
2867                         type = return_type;
2868                         this.child = child;
2869                 }
2870
2871                 public override Expression DoResolve (EmitContext ec)
2872                 {
2873                         // This should never be invoked, we are born in fully
2874                         // initialized state.
2875
2876                         return this;
2877                 }
2878
2879                 public override void Emit (EmitContext ec)
2880                 {
2881                         child.Emit (ec);
2882                 }
2883         }
2884
2885         /// <summary>
2886         ///  This class is used to wrap literals which belong inside Enums
2887         /// </summary>
2888         public class EnumConstant : Constant {
2889                 public Constant Child;
2890
2891                 public EnumConstant (Constant child, Type enum_type)
2892                 {
2893                         eclass = child.eclass;
2894                         this.Child = child;
2895                         type = enum_type;
2896                 }
2897
2898                 public override Expression DoResolve (EmitContext ec)
2899                 {
2900                         // This should never be invoked, we are born in fully
2901                         // initialized state.
2902
2903                         return this;
2904                 }
2905
2906                 public override void Emit (EmitContext ec)
2907                 {
2908                         Child.Emit (ec);
2909                 }
2910
2911                 public override object GetValue ()
2912                 {
2913                         return Child.GetValue ();
2914                 }
2915
2916                 //
2917                 // Converts from one of the valid underlying types for an enumeration
2918                 // (int32, uint32, int64, uint64, short, ushort, byte, sbyte) to
2919                 // one of the internal compiler literals: Int/UInt/Long/ULong Literals.
2920                 //
2921                 public Constant WidenToCompilerConstant ()
2922                 {
2923                         Type t = TypeManager.EnumToUnderlying (Child.Type);
2924                         object v = ((Constant) Child).GetValue ();;
2925
2926                         if (t == TypeManager.int32_type)
2927                                 return new IntConstant ((int) v);
2928                         if (t == TypeManager.uint32_type)
2929                                 return new UIntConstant ((uint) v);
2930                         if (t == TypeManager.int64_type)
2931                                 return new LongConstant ((long) v);
2932                         if (t == TypeManager.uint64_type)
2933                                 return new ULongConstant ((ulong) v);
2934                         if (t == TypeManager.short_type)
2935                                 return new ShortConstant ((short) v);
2936                         if (t == TypeManager.ushort_type)
2937                                 return new UShortConstant ((ushort) v);
2938                         if (t == TypeManager.byte_type)
2939                                 return new ByteConstant ((byte) v);
2940                         if (t == TypeManager.sbyte_type)
2941                                 return new SByteConstant ((sbyte) v);
2942
2943                         throw new Exception ("Invalid enumeration underlying type: " + t);
2944                 }
2945
2946                 //
2947                 // Extracts the value in the enumeration on its native representation
2948                 //
2949                 public object GetPlainValue ()
2950                 {
2951                         Type t = TypeManager.EnumToUnderlying (Child.Type);
2952                         object v = ((Constant) Child).GetValue ();;
2953
2954                         if (t == TypeManager.int32_type)
2955                                 return (int) v;
2956                         if (t == TypeManager.uint32_type)
2957                                 return (uint) v;
2958                         if (t == TypeManager.int64_type)
2959                                 return (long) v;
2960                         if (t == TypeManager.uint64_type)
2961                                 return (ulong) v;
2962                         if (t == TypeManager.short_type)
2963                                 return (short) v;
2964                         if (t == TypeManager.ushort_type)
2965                                 return (ushort) v;
2966                         if (t == TypeManager.byte_type)
2967                                 return (byte) v;
2968                         if (t == TypeManager.sbyte_type)
2969                                 return (sbyte) v;
2970
2971                         return null;
2972                 }
2973
2974                 public override string AsString ()
2975                 {
2976                         return Child.AsString ();
2977                 }
2978
2979                 public override DoubleConstant ConvertToDouble ()
2980                 {
2981                         return Child.ConvertToDouble ();
2982                 }
2983
2984                 public override FloatConstant ConvertToFloat ()
2985                 {
2986                         return Child.ConvertToFloat ();
2987                 }
2988
2989                 public override ULongConstant ConvertToULong ()
2990                 {
2991                         return Child.ConvertToULong ();
2992                 }
2993
2994                 public override LongConstant ConvertToLong ()
2995                 {
2996                         return Child.ConvertToLong ();
2997                 }
2998
2999                 public override UIntConstant ConvertToUInt ()
3000                 {
3001                         return Child.ConvertToUInt ();
3002                 }
3003
3004                 public override IntConstant ConvertToInt ()
3005                 {
3006                         return Child.ConvertToInt ();
3007                 }
3008         }
3009
3010         /// <summary>
3011         ///   This kind of cast is used to encapsulate Value Types in objects.
3012         ///
3013         ///   The effect of it is to box the value type emitted by the previous
3014         ///   operation.
3015         /// </summary>
3016         public class BoxedCast : EmptyCast {
3017
3018                 public BoxedCast (Expression expr)
3019                         : base (expr, TypeManager.object_type)
3020                 {
3021                 }
3022
3023                 public override Expression DoResolve (EmitContext ec)
3024                 {
3025                         // This should never be invoked, we are born in fully
3026                         // initialized state.
3027
3028                         return this;
3029                 }
3030
3031                 public override void Emit (EmitContext ec)
3032                 {
3033                         base.Emit (ec);
3034
3035                         ec.ig.Emit (OpCodes.Box, child.Type);
3036                 }
3037         }
3038
3039         public class UnboxCast : EmptyCast {
3040                 public UnboxCast (Expression expr, Type return_type)
3041                         : base (expr, return_type)
3042                 {
3043                 }
3044
3045                 public override Expression DoResolve (EmitContext ec)
3046                 {
3047                         // This should never be invoked, we are born in fully
3048                         // initialized state.
3049
3050                         return this;
3051                 }
3052
3053                 public override void Emit (EmitContext ec)
3054                 {
3055                         Type t = type;
3056                         ILGenerator ig = ec.ig;
3057
3058                         base.Emit (ec);
3059                         ig.Emit (OpCodes.Unbox, t);
3060
3061                         LoadFromPtr (ig, t);
3062                 }
3063         }
3064
3065         /// <summary>
3066         ///   This is used to perform explicit numeric conversions.
3067         ///
3068         ///   Explicit numeric conversions might trigger exceptions in a checked
3069         ///   context, so they should generate the conv.ovf opcodes instead of
3070         ///   conv opcodes.
3071         /// </summary>
3072         public class ConvCast : EmptyCast {
3073                 public enum Mode : byte {
3074                         I1_U1, I1_U2, I1_U4, I1_U8, I1_CH,
3075                         U1_I1, U1_CH,
3076                         I2_I1, I2_U1, I2_U2, I2_U4, I2_U8, I2_CH,
3077                         U2_I1, U2_U1, U2_I2, U2_CH,
3078                         I4_I1, I4_U1, I4_I2, I4_U2, I4_U4, I4_U8, I4_CH,
3079                         U4_I1, U4_U1, U4_I2, U4_U2, U4_I4, U4_CH,
3080                         I8_I1, I8_U1, I8_I2, I8_U2, I8_I4, I8_U4, I8_U8, I8_CH,
3081                         U8_I1, U8_U1, U8_I2, U8_U2, U8_I4, U8_U4, U8_I8, U8_CH,
3082                         CH_I1, CH_U1, CH_I2,
3083                         R4_I1, R4_U1, R4_I2, R4_U2, R4_I4, R4_U4, R4_I8, R4_U8, R4_CH,
3084                         R8_I1, R8_U1, R8_I2, R8_U2, R8_I4, R8_U4, R8_I8, R8_U8, R8_CH, R8_R4
3085                 }
3086
3087                 Mode mode;
3088                 bool checked_state;
3089
3090                 public ConvCast (EmitContext ec, Expression child, Type return_type, Mode m)
3091                         : base (child, return_type)
3092                 {
3093                         checked_state = ec.CheckState;
3094                         mode = m;
3095                 }
3096
3097                 public override Expression DoResolve (EmitContext ec)
3098                 {
3099                         // This should never be invoked, we are born in fully
3100                         // initialized state.
3101
3102                         return this;
3103                 }
3104
3105                 public override void Emit (EmitContext ec)
3106                 {
3107                         ILGenerator ig = ec.ig;
3108
3109                         base.Emit (ec);
3110
3111                         if (checked_state){
3112                                 switch (mode){
3113                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3114                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3115                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3116                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3117                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3118
3119                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3120                                 case Mode.U1_CH: /* nothing */ break;
3121
3122                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3123                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3124                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3125                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3126                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3127                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3128
3129                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3130                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
3131                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
3132                                 case Mode.U2_CH: /* nothing */ break;
3133
3134                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3135                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3136                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
3137                                 case Mode.I4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3138                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3139                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3140                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3141
3142                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3143                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
3144                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
3145                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
3146                                 case Mode.U4_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
3147                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
3148
3149                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3150                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3151                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
3152                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3153                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
3154                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3155                                 case Mode.I8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3156                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3157
3158                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3159                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
3160                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
3161                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
3162                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
3163                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_Ovf_U4_Un); break;
3164                                 case Mode.U8_I8: ig.Emit (OpCodes.Conv_Ovf_I8_Un); break;
3165                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
3166
3167                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3168                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
3169                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
3170
3171                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3172                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3173                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
3174                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3175                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
3176                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3177                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
3178                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3179                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3180
3181                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3182                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3183                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
3184                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3185                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
3186                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3187                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
3188                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3189                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3190                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
3191                                 }
3192                         } else {
3193                                 switch (mode){
3194                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_U1); break;
3195                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_U2); break;
3196                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_U4); break;
3197                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_I8); break;
3198                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_U2); break;
3199
3200                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_I1); break;
3201                                 case Mode.U1_CH: ig.Emit (OpCodes.Conv_U2); break;
3202
3203                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_I1); break;
3204                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_U1); break;
3205                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_U2); break;
3206                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_U4); break;
3207                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_I8); break;
3208                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_U2); break;
3209
3210                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_I1); break;
3211                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_U1); break;
3212                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_I2); break;
3213                                 case Mode.U2_CH: /* nothing */ break;
3214
3215                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_I1); break;
3216                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_U1); break;
3217                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_I2); break;
3218                                 case Mode.I4_U4: /* nothing */ break;
3219                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_U2); break;
3220                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_I8); break;
3221                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_U2); break;
3222
3223                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_I1); break;
3224                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_U1); break;
3225                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_I2); break;
3226                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_U2); break;
3227                                 case Mode.U4_I4: /* nothing */ break;
3228                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_U2); break;
3229
3230                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_I1); break;
3231                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_U1); break;
3232                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_I2); break;
3233                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_U2); break;
3234                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_I4); break;
3235                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_U4); break;
3236                                 case Mode.I8_U8: /* nothing */ break;
3237                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_U2); break;
3238
3239                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_I1); break;
3240                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_U1); break;
3241                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_I2); break;
3242                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_U2); break;
3243                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_I4); break;
3244                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_U4); break;
3245                                 case Mode.U8_I8: /* nothing */ break;
3246                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_U2); break;
3247
3248                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_I1); break;
3249                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_U1); break;
3250                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_I2); break;
3251
3252                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_I1); break;
3253                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_U1); break;
3254                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_I2); break;
3255                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_U2); break;
3256                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_I4); break;
3257                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_U4); break;
3258                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_I8); break;
3259                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_U8); break;
3260                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_U2); break;
3261
3262                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_I1); break;
3263                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_U1); break;
3264                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_I2); break;
3265                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_U2); break;
3266                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_I4); break;
3267                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_U4); break;
3268                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_I8); break;
3269                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_U8); break;
3270                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_U2); break;
3271                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
3272                                 }
3273                         }
3274                 }
3275         }
3276
3277         public class OpcodeCast : EmptyCast {
3278                 OpCode op, op2;
3279                 bool second_valid;
3280
3281                 public OpcodeCast (Expression child, Type return_type, OpCode op)
3282                         : base (child, return_type)
3283
3284                 {
3285                         this.op = op;
3286                         second_valid = false;
3287                 }
3288
3289                 public OpcodeCast (Expression child, Type return_type, OpCode op, OpCode op2)
3290                         : base (child, return_type)
3291
3292                 {
3293                         this.op = op;
3294                         this.op2 = op2;
3295                         second_valid = true;
3296                 }
3297
3298                 public override Expression DoResolve (EmitContext ec)
3299                 {
3300                         // This should never be invoked, we are born in fully
3301                         // initialized state.
3302
3303                         return this;
3304                 }
3305
3306                 public override void Emit (EmitContext ec)
3307                 {
3308                         base.Emit (ec);
3309                         ec.ig.Emit (op);
3310
3311                         if (second_valid)
3312                                 ec.ig.Emit (op2);
3313                 }
3314         }
3315
3316         /// <summary>
3317         ///   This kind of cast is used to encapsulate a child and cast it
3318         ///   to the class requested
3319         /// </summary>
3320         public class ClassCast : EmptyCast {
3321                 public ClassCast (Expression child, Type return_type)
3322                         : base (child, return_type)
3323
3324                 {
3325                 }
3326
3327                 public override Expression DoResolve (EmitContext ec)
3328                 {
3329                         // This should never be invoked, we are born in fully
3330                         // initialized state.
3331
3332                         return this;
3333                 }
3334
3335                 public override void Emit (EmitContext ec)
3336                 {
3337                         base.Emit (ec);
3338
3339                         ec.ig.Emit (OpCodes.Castclass, type);
3340                 }
3341
3342         }
3343
3344         /// <summary>
3345         ///   SimpleName expressions are initially formed of a single
3346         ///   word and it only happens at the beginning of the expression.
3347         /// </summary>
3348         ///
3349         /// <remarks>
3350         ///   The expression will try to be bound to a Field, a Method
3351         ///   group or a Property.  If those fail we pass the name to our
3352         ///   caller and the SimpleName is compounded to perform a type
3353         ///   lookup.  The idea behind this process is that we want to avoid
3354         ///   creating a namespace map from the assemblies, as that requires
3355         ///   the GetExportedTypes function to be called and a hashtable to
3356         ///   be constructed which reduces startup time.  If later we find
3357         ///   that this is slower, we should create a `NamespaceExpr' expression
3358         ///   that fully participates in the resolution process.
3359         ///
3360         ///   For example `System.Console.WriteLine' is decomposed into
3361         ///   MemberAccess (MemberAccess (SimpleName ("System"), "Console"), "WriteLine")
3362         ///
3363         ///   The first SimpleName wont produce a match on its own, so it will
3364         ///   be turned into:
3365         ///   MemberAccess (SimpleName ("System.Console"), "WriteLine").
3366         ///
3367         ///   System.Console will produce a TypeExpr match.
3368         ///
3369         ///   The downside of this is that we might be hitting `LookupType' too many
3370         ///   times with this scheme.
3371         /// </remarks>
3372         public class SimpleName : Expression, ITypeExpression {
3373                 public readonly string Name;
3374
3375                 public SimpleName (string name, Location l)
3376                 {
3377                         Name = name;
3378                         loc = l;
3379                 }
3380
3381                 public static void Error_ObjectRefRequired (EmitContext ec, Location l, string name)
3382                 {
3383                         if (ec.IsFieldInitializer)
3384                                 Report.Error (
3385                                         236, l,
3386                                         "A field initializer cannot reference the non-static field, " +
3387                                         "method or property `"+name+"'");
3388                         else
3389                                 Report.Error (
3390                                         120, l,
3391                                         "An object reference is required " +
3392                                         "for the non-static field `"+name+"'");
3393                 }
3394
3395                 //
3396                 // Checks whether we are trying to access an instance
3397                 // property, method or field from a static body.
3398                 //
3399                 Expression MemberStaticCheck (EmitContext ec, Expression e)
3400                 {
3401                         if (e is IMemberExpr){
3402                                 IMemberExpr member = (IMemberExpr) e;
3403
3404                                 if (!member.IsStatic){
3405                                         Error_ObjectRefRequired (ec, loc, Name);
3406                                         return null;
3407                                 }
3408                         }
3409
3410                         return e;
3411                 }
3412
3413                 public override Expression DoResolve (EmitContext ec)
3414                 {
3415                         return SimpleNameResolve (ec, null, false);
3416                 }
3417
3418                 public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
3419                 {
3420                         return SimpleNameResolve (ec, right_side, false);
3421                 }
3422
3423
3424                 public Expression DoResolveAllowStatic (EmitContext ec)
3425                 {
3426                         return SimpleNameResolve (ec, null, true);
3427                 }
3428
3429                 public Expression DoResolveType (EmitContext ec)
3430                 {
3431                         //
3432                         // Stage 3: Lookup symbol in the various namespaces.
3433                         //
3434                         DeclSpace ds = ec.DeclSpace;
3435                         Type t;
3436                         string alias_value;
3437
3438                         if ((t = RootContext.LookupType (ds, Name, true, loc)) != null)
3439                                 return new TypeExpr (t, loc);
3440
3441                         //
3442                         // Stage 2 part b: Lookup up if we are an alias to a type
3443                         // or a namespace.
3444                         //
3445                         // Since we are cheating: we only do the Alias lookup for
3446                         // namespaces if the name does not include any dots in it
3447                         //
3448
3449                         alias_value = ec.DeclSpace.LookupAlias (Name);
3450
3451                         if (Name.IndexOf ('.') == -1 && alias_value != null) {
3452                                 if ((t = RootContext.LookupType (ds, alias_value, true, loc)) != null)
3453                                         return new TypeExpr (t, loc);
3454
3455                                 // we have alias value, but it isn't Type, so try if it's namespace
3456                                 return new SimpleName (alias_value, loc);
3457                         }
3458
3459                         if (ec.ResolvingTypeTree){
3460                                 Type dt = ec.DeclSpace.FindType (Name);
3461                                 if (dt != null)
3462                                         return new TypeExpr (dt, loc);
3463                         }
3464
3465                         // No match, maybe our parent can compose us
3466                         // into something meaningful.
3467                         return this;
3468                 }
3469
3470                 /// <remarks>
3471                 ///   7.5.2: Simple Names.
3472                 ///
3473                 ///   Local Variables and Parameters are handled at
3474                 ///   parse time, so they never occur as SimpleNames.
3475                 ///
3476                 ///   The `allow_static' flag is used by MemberAccess only
3477                 ///   and it is used to inform us that it is ok for us to
3478                 ///   avoid the static check, because MemberAccess might end
3479                 ///   up resolving the Name as a Type name and the access as
3480                 ///   a static type access.
3481                 ///
3482                 ///   ie: Type Type; .... { Type.GetType (""); }
3483                 ///
3484                 ///   Type is both an instance variable and a Type;  Type.GetType
3485                 ///   is the static method not an instance method of type.
3486                 /// </remarks>
3487                 Expression SimpleNameResolve (EmitContext ec, Expression right_side, bool allow_static)
3488                 {
3489                         Expression e = null;
3490
3491                         //
3492                         // Stage 1: Performed by the parser (binding to locals or parameters).
3493                         //
3494                         Block current_block = ec.CurrentBlock;
3495                         if (current_block != null && current_block.IsVariableDefined (Name)){
3496                                 LocalVariableReference var;
3497
3498                                 var = new LocalVariableReference (ec.CurrentBlock, Name, loc);
3499
3500                                 if (right_side != null)
3501                                         return var.ResolveLValue (ec, right_side);
3502                                 else
3503                                         return var.Resolve (ec);
3504                         }
3505
3506                         if (current_block != null){
3507                                 int idx = -1;
3508                                 Parameter par = null;
3509                                 Parameters pars = current_block.Parameters;
3510                                 if (pars != null)
3511                                         par = pars.GetParameterByName (Name, out idx);
3512
3513                                 if (par != null) {
3514                                         ParameterReference param;
3515
3516                                         param = new ParameterReference (pars, idx, Name, loc);
3517
3518                                         if (right_side != null)
3519                                                 return param.ResolveLValue (ec, right_side);
3520                                         else
3521                                                 return param.Resolve (ec);
3522                                 }
3523                         }
3524
3525                         //
3526                         // Stage 2: Lookup members
3527                         //
3528
3529                         //
3530                         // For enums, the TypeBuilder is not ec.DeclSpace.TypeBuilder
3531                         // Hence we have two different cases
3532                         //
3533
3534                         DeclSpace lookup_ds = ec.DeclSpace;
3535                         do {
3536                                 if (lookup_ds.TypeBuilder == null)
3537                                         break;
3538
3539                                 e = MemberLookup (ec, lookup_ds.TypeBuilder, Name, loc);
3540                                 if (e != null)
3541                                         break;
3542
3543                                 //
3544                                 // Classes/structs keep looking, enums break
3545                                 //
3546                                 if (lookup_ds is TypeContainer)
3547                                         lookup_ds = ((TypeContainer) lookup_ds).Parent;
3548                                 else
3549                                         break;
3550                         } while (lookup_ds != null);
3551
3552                         if (e == null && ec.ContainerType != null)
3553                                 e = MemberLookup (ec, ec.ContainerType, Name, loc);
3554
3555                         if (e == null)
3556                                 return DoResolveType (ec);
3557
3558                         if (e is TypeExpr)
3559                                 return e;
3560
3561                         if (e is IMemberExpr) {
3562                                 e = MemberAccess.ResolveMemberAccess (ec, e, null, loc, this);
3563                                 if (e == null)
3564                                         return null;
3565
3566                                 IMemberExpr me = e as IMemberExpr;
3567                                 if (me == null)
3568                                         return e;
3569
3570                                 // This fails if ResolveMemberAccess() was unable to decide whether
3571                                 // it's a field or a type of the same name.
3572                                 if (!me.IsStatic && (me.InstanceExpression == null))
3573                                         return e;
3574
3575                                 if (!me.IsStatic &&
3576                                     TypeManager.IsNestedChildOf (me.InstanceExpression.Type, me.DeclaringType)) {
3577                                         Error (38, "Cannot access nonstatic member `" + me.Name + "' of " +
3578                                                "outer type `" + me.DeclaringType + "' via nested type `" +
3579                                                me.InstanceExpression.Type + "'");
3580                                         return null;
3581                                 }
3582
3583                                 if (right_side != null)
3584                                         e = e.DoResolveLValue (ec, right_side);
3585                                 else
3586                                         e = e.DoResolve (ec);
3587
3588                                 return e;
3589                         }
3590
3591                         if (ec.IsStatic || ec.IsFieldInitializer){
3592                                 if (allow_static)
3593                                         return e;
3594
3595                                 return MemberStaticCheck (ec, e);
3596                         } else
3597                                 return e;
3598                 }
3599
3600                 public override void Emit (EmitContext ec)
3601                 {
3602                         //
3603                         // If this is ever reached, then we failed to
3604                         // find the name as a namespace
3605                         //
3606
3607                         Error (103, "The name `" + Name +
3608                                "' does not exist in the class `" +
3609                                ec.DeclSpace.Name + "'");
3610                 }
3611
3612                 public override string ToString ()
3613                 {
3614                         return Name;
3615                 }
3616         }
3617
3618         /// <summary>
3619         ///   Fully resolved expression that evaluates to a type
3620         /// </summary>
3621         public class TypeExpr : Expression, ITypeExpression {
3622                 public TypeExpr (Type t, Location l)
3623                 {
3624                         Type = t;
3625                         eclass = ExprClass.Type;
3626                         loc = l;
3627                 }
3628
3629                 public virtual Expression DoResolveType (EmitContext ec)
3630                 {
3631                         return this;
3632                 }
3633
3634                 override public Expression DoResolve (EmitContext ec)
3635                 {
3636                         return this;
3637                 }
3638
3639                 override public void Emit (EmitContext ec)
3640                 {
3641                         throw new Exception ("Should never be called");
3642                 }
3643
3644                 public override string ToString ()
3645                 {
3646                         return Type.ToString ();
3647                 }
3648         }
3649
3650         /// <summary>
3651         ///   Used to create types from a fully qualified name.  These are just used
3652         ///   by the parser to setup the core types.  A TypeLookupExpression is always
3653         ///   classified as a type.
3654         /// </summary>
3655         public class TypeLookupExpression : TypeExpr {
3656                 string name;
3657
3658                 public TypeLookupExpression (string name) : base (null, Location.Null)
3659                 {
3660                         this.name = name;
3661                 }
3662
3663                 public override Expression DoResolveType (EmitContext ec)
3664                 {
3665                         if (type == null)
3666                                 type = RootContext.LookupType (ec.DeclSpace, name, false, Location.Null);
3667                         return this;
3668                 }
3669
3670                 public override Expression DoResolve (EmitContext ec)
3671                 {
3672                         return DoResolveType (ec);
3673                 }
3674
3675                 public override void Emit (EmitContext ec)
3676                 {
3677                         throw new Exception ("Should never be called");
3678                 }
3679
3680                 public override string ToString ()
3681                 {
3682                         return name;
3683                 }
3684         }
3685
3686         /// <summary>
3687         ///   MethodGroup Expression.
3688         ///
3689         ///   This is a fully resolved expression that evaluates to a type
3690         /// </summary>
3691         public class MethodGroupExpr : Expression, IMemberExpr {
3692                 public MethodBase [] Methods;
3693                 Expression instance_expression = null;
3694                 bool is_explicit_impl = false;
3695
3696                 public MethodGroupExpr (MemberInfo [] mi, Location l)
3697                 {
3698                         Methods = new MethodBase [mi.Length];
3699                         mi.CopyTo (Methods, 0);
3700                         eclass = ExprClass.MethodGroup;
3701                         type = TypeManager.object_type;
3702                         loc = l;
3703                 }
3704
3705                 public MethodGroupExpr (ArrayList list, Location l)
3706                 {
3707                         Methods = new MethodBase [list.Count];
3708
3709                         try {
3710                                 list.CopyTo (Methods, 0);
3711                         } catch {
3712                                 foreach (MemberInfo m in list){
3713                                         if (!(m is MethodBase)){
3714                                                 Console.WriteLine ("Name " + m.Name);
3715                                                 Console.WriteLine ("Found a: " + m.GetType ().FullName);
3716                                         }
3717                                 }
3718                                 throw;
3719                         }
3720                         loc = l;
3721                         eclass = ExprClass.MethodGroup;
3722                         type = TypeManager.object_type;
3723                 }
3724
3725                 public Type DeclaringType {
3726                         get {
3727                                 return Methods [0].DeclaringType;
3728                         }
3729                 }
3730
3731                 //
3732                 // `A method group may have associated an instance expression'
3733                 //
3734                 public Expression InstanceExpression {
3735                         get {
3736                                 return instance_expression;
3737                         }
3738
3739                         set {
3740                                 instance_expression = value;
3741                         }
3742                 }
3743
3744                 public bool IsExplicitImpl {
3745                         get {
3746                                 return is_explicit_impl;
3747                         }
3748
3749                         set {
3750                                 is_explicit_impl = value;
3751                         }
3752                 }
3753
3754                 public string Name {
3755                         get {
3756                                 return Methods [0].Name;
3757                         }
3758                 }
3759
3760                 public bool IsInstance {
3761                         get {
3762                                 foreach (MethodBase mb in Methods)
3763                                         if (!mb.IsStatic)
3764                                                 return true;
3765
3766                                 return false;
3767                         }
3768                 }
3769
3770                 public bool IsStatic {
3771                         get {
3772                                 foreach (MethodBase mb in Methods)
3773                                         if (mb.IsStatic)
3774                                                 return true;
3775
3776                                 return false;
3777                         }
3778                 }
3779
3780                 override public Expression DoResolve (EmitContext ec)
3781                 {
3782                         if (instance_expression != null) {
3783                                 instance_expression = instance_expression.DoResolve (ec);
3784                                 if (instance_expression == null)
3785                                         return null;
3786                         }
3787
3788                         return this;
3789                 }
3790
3791                 public void ReportUsageError ()
3792                 {
3793                         Report.Error (654, loc, "Method `" + Methods [0].DeclaringType + "." +
3794                                       Methods [0].Name + "()' is referenced without parentheses");
3795                 }
3796
3797                 override public void Emit (EmitContext ec)
3798                 {
3799                         ReportUsageError ();
3800                 }
3801
3802                 bool RemoveMethods (bool keep_static)
3803                 {
3804                         ArrayList smethods = new ArrayList ();
3805
3806                         foreach (MethodBase mb in Methods){
3807                                 if (mb.IsStatic == keep_static)
3808                                         smethods.Add (mb);
3809                         }
3810
3811                         if (smethods.Count == 0)
3812                                 return false;
3813
3814                         Methods = new MethodBase [smethods.Count];
3815                         smethods.CopyTo (Methods, 0);
3816
3817                         return true;
3818                 }
3819
3820                 /// <summary>
3821                 ///   Removes any instance methods from the MethodGroup, returns
3822                 ///   false if the resulting set is empty.
3823                 /// </summary>
3824                 public bool RemoveInstanceMethods ()
3825                 {
3826                         return RemoveMethods (true);
3827                 }
3828
3829                 /// <summary>
3830                 ///   Removes any static methods from the MethodGroup, returns
3831                 ///   false if the resulting set is empty.
3832                 /// </summary>
3833                 public bool RemoveStaticMethods ()
3834                 {
3835                         return RemoveMethods (false);
3836                 }
3837         }
3838
3839         /// <summary>
3840         ///   Fully resolved expression that evaluates to a Field
3841         /// </summary>
3842         public class FieldExpr : Expression, IAssignMethod, IMemoryLocation, IMemberExpr {
3843                 public readonly FieldInfo FieldInfo;
3844                 Expression instance_expr;
3845
3846                 public FieldExpr (FieldInfo fi, Location l)
3847                 {
3848                         FieldInfo = fi;
3849                         eclass = ExprClass.Variable;
3850                         type = fi.FieldType;
3851                         loc = l;
3852                 }
3853
3854                 public string Name {
3855                         get {
3856                                 return FieldInfo.Name;
3857                         }
3858                 }
3859
3860                 public bool IsInstance {
3861                         get {
3862                                 return !FieldInfo.IsStatic;
3863                         }
3864                 }
3865
3866                 public bool IsStatic {
3867                         get {
3868                                 return FieldInfo.IsStatic;
3869                         }
3870                 }
3871
3872                 public Type DeclaringType {
3873                         get {
3874                                 return FieldInfo.DeclaringType;
3875                         }
3876                 }
3877
3878                 public Expression InstanceExpression {
3879                         get {
3880                                 return instance_expr;
3881                         }
3882
3883                         set {
3884                                 instance_expr = value;
3885                         }
3886                 }
3887
3888                 override public Expression DoResolve (EmitContext ec)
3889                 {
3890                         if (!FieldInfo.IsStatic){
3891                                 if (instance_expr == null){
3892                                         throw new Exception ("non-static FieldExpr without instance var\n" +
3893                                                              "You have to assign the Instance variable\n" +
3894                                                              "Of the FieldExpr to set this\n");
3895                                 }
3896
3897                                 // Resolve the field's instance expression while flow analysis is turned
3898                                 // off: when accessing a field "a.b", we must check whether the field
3899                                 // "a.b" is initialized, not whether the whole struct "a" is initialized.
3900                                 instance_expr = instance_expr.Resolve (ec, ResolveFlags.VariableOrValue |
3901                                                                        ResolveFlags.DisableFlowAnalysis);
3902                                 if (instance_expr == null)
3903                                         return null;
3904                         }
3905
3906                         // If the instance expression is a local variable or parameter.
3907                         IVariable var = instance_expr as IVariable;
3908                         if ((var != null) && !var.IsFieldAssigned (ec, FieldInfo.Name, loc))
3909                                 return null;
3910
3911                         return this;
3912                 }
3913
3914                 void Report_AssignToReadonly (bool is_instance)
3915                 {
3916                         string msg;
3917
3918                         if (is_instance)
3919                                 msg = "Readonly field can not be assigned outside " +
3920                                 "of constructor or variable initializer";
3921                         else
3922                                 msg = "A static readonly field can only be assigned in " +
3923                                 "a static constructor";
3924
3925                         Report.Error (is_instance ? 191 : 198, loc, msg);
3926                 }
3927
3928                 override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
3929                 {
3930                         IVariable var = instance_expr as IVariable;
3931                         if (var != null)
3932                                 var.SetFieldAssigned (ec, FieldInfo.Name);
3933
3934                         Expression e = DoResolve (ec);
3935
3936                         if (e == null)
3937                                 return null;
3938
3939                         if (!FieldInfo.IsInitOnly)
3940                                 return this;
3941
3942                         //
3943                         // InitOnly fields can only be assigned in constructors
3944                         //
3945
3946                         if (ec.IsConstructor)
3947                                 return this;
3948
3949                         Report_AssignToReadonly (true);
3950
3951                         return null;
3952                 }
3953
3954                 override public void Emit (EmitContext ec)
3955                 {
3956                         ILGenerator ig = ec.ig;
3957                         bool is_volatile = false;
3958
3959                         if (FieldInfo is FieldBuilder){
3960                                 FieldBase f = TypeManager.GetField (FieldInfo);
3961
3962                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
3963                                         is_volatile = true;
3964
3965                                 f.status |= Field.Status.USED;
3966                         }
3967
3968                         if (FieldInfo.IsStatic){
3969                                 if (is_volatile)
3970                                         ig.Emit (OpCodes.Volatile);
3971
3972                                 ig.Emit (OpCodes.Ldsfld, FieldInfo);
3973                         } else {
3974                                 if (instance_expr.Type.IsValueType){
3975                                         IMemoryLocation ml;
3976                                         LocalTemporary tempo = null;
3977
3978                                         if (!(instance_expr is IMemoryLocation)){
3979                                                 tempo = new LocalTemporary (
3980                                                         ec, instance_expr.Type);
3981
3982                                                 InstanceExpression.Emit (ec);
3983                                                 tempo.Store (ec);
3984                                                 ml = tempo;
3985                                         } else
3986                                                 ml = (IMemoryLocation) instance_expr;
3987
3988                                         ml.AddressOf (ec, AddressOp.Load);
3989                                 } else
3990                                         instance_expr.Emit (ec);
3991
3992                                 if (is_volatile)
3993                                         ig.Emit (OpCodes.Volatile);
3994
3995                                 ig.Emit (OpCodes.Ldfld, FieldInfo);
3996                         }
3997                 }
3998
3999                 public void EmitAssign (EmitContext ec, Expression source)
4000                 {
4001                         FieldAttributes fa = FieldInfo.Attributes;
4002                         bool is_static = (fa & FieldAttributes.Static) != 0;
4003                         bool is_readonly = (fa & FieldAttributes.InitOnly) != 0;
4004                         ILGenerator ig = ec.ig;
4005
4006                         if (is_readonly && !ec.IsConstructor){
4007                                 Report_AssignToReadonly (!is_static);
4008                                 return;
4009                         }
4010
4011                         if (!is_static){
4012                                 Expression instance = instance_expr;
4013
4014                                 if (instance.Type.IsValueType){
4015                                         if (instance is IMemoryLocation){
4016                                                 IMemoryLocation ml = (IMemoryLocation) instance;
4017
4018                                                 ml.AddressOf (ec, AddressOp.Store);
4019                                         } else
4020                                                 throw new Exception ("The " + instance + " of type " +
4021                                                                      instance.Type +
4022                                                                      " represents a ValueType and does " +
4023                                                                      "not implement IMemoryLocation");
4024                                 } else
4025                                         instance.Emit (ec);
4026                         }
4027                         source.Emit (ec);
4028
4029                         if (FieldInfo is FieldBuilder){
4030                                 FieldBase f = TypeManager.GetField (FieldInfo);
4031
4032                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
4033                                         ig.Emit (OpCodes.Volatile);
4034                         }
4035
4036                         if (is_static)
4037                                 ig.Emit (OpCodes.Stsfld, FieldInfo);
4038                         else
4039                                 ig.Emit (OpCodes.Stfld, FieldInfo);
4040
4041                         if (FieldInfo is FieldBuilder){
4042                                 FieldBase f = TypeManager.GetField (FieldInfo);
4043
4044                                 f.status |= Field.Status.ASSIGNED;
4045                         }
4046                 }
4047
4048                 public void AddressOf (EmitContext ec, AddressOp mode)
4049                 {
4050                         ILGenerator ig = ec.ig;
4051
4052                         if (FieldInfo is FieldBuilder){
4053                                 FieldBase f = TypeManager.GetField (FieldInfo);
4054                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
4055                                         ig.Emit (OpCodes.Volatile);
4056                         }
4057
4058                         if (FieldInfo is FieldBuilder){
4059                                 FieldBase f = TypeManager.GetField (FieldInfo);
4060
4061                                 if ((mode & AddressOp.Store) != 0)
4062                                         f.status |= Field.Status.ASSIGNED;
4063                                 if ((mode & AddressOp.Load) != 0)
4064                                         f.status |= Field.Status.USED;
4065                         }
4066
4067                         //
4068                         // Handle initonly fields specially: make a copy and then
4069                         // get the address of the copy.
4070                         //
4071                         if (FieldInfo.IsInitOnly){
4072                                 if (ec.IsConstructor) {
4073                                         ig.Emit (OpCodes.Ldsflda, FieldInfo);
4074                                 } else {
4075                                         LocalBuilder local;
4076
4077                                         Emit (ec);
4078                                         local = ig.DeclareLocal (type);
4079                                         ig.Emit (OpCodes.Stloc, local);
4080                                         ig.Emit (OpCodes.Ldloca, local);
4081                                 }
4082                                 return;
4083                         }
4084
4085                         if (FieldInfo.IsStatic)
4086                                 ig.Emit (OpCodes.Ldsflda, FieldInfo);
4087                         else {
4088                                 if (instance_expr is IMemoryLocation)
4089                                         ((IMemoryLocation)instance_expr).AddressOf (ec, AddressOp.LoadStore);
4090                                 else
4091                                         instance_expr.Emit (ec);
4092                                 ig.Emit (OpCodes.Ldflda, FieldInfo);
4093                         }
4094                 }
4095         }
4096
4097         /// <summary>
4098         ///   Expression that evaluates to a Property.  The Assign class
4099         ///   might set the `Value' expression if we are in an assignment.
4100         ///
4101         ///   This is not an LValue because we need to re-write the expression, we
4102         ///   can not take data from the stack and store it.
4103         /// </summary>
4104         public class PropertyExpr : ExpressionStatement, IAssignMethod, IMemberExpr {
4105                 public readonly PropertyInfo PropertyInfo;
4106                 public bool IsBase;
4107                 MethodInfo [] Accessors;
4108                 bool is_static;
4109
4110                 Expression instance_expr;
4111
4112                 public PropertyExpr (PropertyInfo pi, Location l)
4113                 {
4114                         PropertyInfo = pi;
4115                         eclass = ExprClass.PropertyAccess;
4116                         is_static = false;
4117                         loc = l;
4118                         Accessors = TypeManager.GetAccessors (pi);
4119
4120                         if (Accessors != null)
4121                                 foreach (MethodInfo mi in Accessors){
4122                                         if (mi != null)
4123                                                 if (mi.IsStatic)
4124                                                         is_static = true;
4125                                 }
4126                         else
4127                                 Accessors = new MethodInfo [2];
4128
4129                         type = TypeManager.TypeToCoreType (pi.PropertyType);
4130                 }
4131
4132                 public string Name {
4133                         get {
4134                                 return PropertyInfo.Name;
4135                         }
4136                 }
4137
4138                 public bool IsInstance {
4139                         get {
4140                                 return !is_static;
4141                         }
4142                 }
4143
4144                 public bool IsStatic {
4145                         get {
4146                                 return is_static;
4147                         }
4148                 }
4149
4150                 public Type DeclaringType {
4151                         get {
4152                                 return PropertyInfo.DeclaringType;
4153                         }
4154                 }
4155
4156                 //
4157                 // The instance expression associated with this expression
4158                 //
4159                 public Expression InstanceExpression {
4160                         set {
4161                                 instance_expr = value;
4162                         }
4163
4164                         get {
4165                                 return instance_expr;
4166                         }
4167                 }
4168
4169                 public bool VerifyAssignable ()
4170                 {
4171                         if (!PropertyInfo.CanWrite){
4172                                 Report.Error (200, loc,
4173                                               "The property `" + PropertyInfo.Name +
4174                                               "' can not be assigned to, as it has not set accessor");
4175                                 return false;
4176                         }
4177
4178                         return true;
4179                 }
4180
4181                 override public Expression DoResolve (EmitContext ec)
4182                 {
4183                         if (!PropertyInfo.CanRead){
4184                                 Report.Error (154, loc,
4185                                               "The property `" + PropertyInfo.Name +
4186                                               "' can not be used in " +
4187                                               "this context because it lacks a get accessor");
4188                                 return null;
4189                         }
4190
4191                         if ((instance_expr == null) && ec.IsStatic && !is_static) {
4192                                 SimpleName.Error_ObjectRefRequired (ec, loc, PropertyInfo.Name);
4193                                 return null;
4194                         }
4195
4196                         if (instance_expr != null) {
4197                                 instance_expr = instance_expr.DoResolve (ec);
4198                                 if (instance_expr == null)
4199                                         return null;
4200                         }
4201
4202                         return this;
4203                 }
4204
4205                 override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
4206                 {
4207                         if (!PropertyInfo.CanWrite){
4208                                 Report.Error (154, loc,
4209                                               "The property `" + PropertyInfo.Name +
4210                                               "' can not be used in " +
4211                                               "this context because it lacks a set accessor");
4212                                 return null;
4213                         }
4214
4215                         if (instance_expr != null) {
4216                                 instance_expr = instance_expr.DoResolve (ec);
4217                                 if (instance_expr == null)
4218                                         return null;
4219                         }
4220
4221                         return this;
4222                 }
4223
4224                 override public void Emit (EmitContext ec)
4225                 {
4226                         MethodInfo method = Accessors [0];
4227
4228                         //
4229                         // Special case: length of single dimension array is turned into ldlen
4230                         //
4231                         if ((method == TypeManager.system_int_array_get_length) ||
4232                             (method == TypeManager.int_array_get_length)){
4233                                 Type iet = instance_expr.Type;
4234
4235                                 //
4236                                 // System.Array.Length can be called, but the Type does not
4237                                 // support invoking GetArrayRank, so test for that case first
4238                                 //
4239                                 if (iet != TypeManager.array_type && (iet.GetArrayRank () == 1)){
4240                                         instance_expr.Emit (ec);
4241                                         ec.ig.Emit (OpCodes.Ldlen);
4242                                         return;
4243                                 }
4244                         }
4245
4246                         Invocation.EmitCall (ec, IsBase, IsStatic, instance_expr, method, null, loc);
4247
4248                 }
4249
4250                 //
4251                 // Implements the IAssignMethod interface for assignments
4252                 //
4253                 public void EmitAssign (EmitContext ec, Expression source)
4254                 {
4255                         Argument arg = new Argument (source, Argument.AType.Expression);
4256                         ArrayList args = new ArrayList ();
4257
4258                         args.Add (arg);
4259                         Invocation.EmitCall (ec, false, IsStatic, instance_expr, Accessors [1], args, loc);
4260                 }
4261
4262                 override public void EmitStatement (EmitContext ec)
4263                 {
4264                         Emit (ec);
4265                         ec.ig.Emit (OpCodes.Pop);
4266                 }
4267         }
4268
4269         /// <summary>
4270         ///   Fully resolved expression that evaluates to an Event
4271         /// </summary>
4272         public class EventExpr : Expression, IMemberExpr {
4273                 public readonly EventInfo EventInfo;
4274                 public Expression instance_expr;
4275
4276                 bool is_static;
4277                 MethodInfo add_accessor, remove_accessor;
4278
4279                 public EventExpr (EventInfo ei, Location loc)
4280                 {
4281                         EventInfo = ei;
4282                         this.loc = loc;
4283                         eclass = ExprClass.EventAccess;
4284
4285                         add_accessor = TypeManager.GetAddMethod (ei);
4286                         remove_accessor = TypeManager.GetRemoveMethod (ei);
4287
4288                         if (add_accessor.IsStatic || remove_accessor.IsStatic)
4289                                 is_static = true;
4290
4291                         if (EventInfo is MyEventBuilder)
4292                                 type = ((MyEventBuilder) EventInfo).EventType;
4293                         else
4294                                 type = EventInfo.EventHandlerType;
4295                 }
4296
4297                 public string Name {
4298                         get {
4299                                 return EventInfo.Name;
4300                         }
4301                 }
4302
4303                 public bool IsInstance {
4304                         get {
4305                                 return !is_static;
4306                         }
4307                 }
4308
4309                 public bool IsStatic {
4310                         get {
4311                                 return is_static;
4312                         }
4313                 }
4314
4315                 public Type DeclaringType {
4316                         get {
4317                                 return EventInfo.DeclaringType;
4318                         }
4319                 }
4320
4321                 public Expression InstanceExpression {
4322                         get {
4323                                 return instance_expr;
4324                         }
4325
4326                         set {
4327                                 instance_expr = value;
4328                         }
4329                 }
4330
4331                 public override Expression DoResolve (EmitContext ec)
4332                 {
4333                         if (instance_expr != null) {
4334                                 instance_expr = instance_expr.DoResolve (ec);
4335                                 if (instance_expr == null)
4336                                         return null;
4337                         }
4338
4339                         return this;
4340                 }
4341
4342                 public override void Emit (EmitContext ec)
4343                 {
4344                         throw new Exception ("Should not happen I think");
4345                 }
4346
4347                 public void EmitAddOrRemove (EmitContext ec, Expression source)
4348                 {
4349                         Expression handler = ((Binary) source).Right;
4350
4351                         Argument arg = new Argument (handler, Argument.AType.Expression);
4352                         ArrayList args = new ArrayList ();
4353
4354                         args.Add (arg);
4355
4356                         if (((Binary) source).Oper == Binary.Operator.Addition)
4357                                 Invocation.EmitCall (
4358                                         ec, false, IsStatic, instance_expr, add_accessor, args, loc);
4359                         else
4360                                 Invocation.EmitCall (
4361                                         ec, false, IsStatic, instance_expr, remove_accessor, args, loc);
4362                 }
4363         }
4364 }