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         //
  40         // This is just as a hint to AddressOf of what will be done with the
  41         // address.
  42         [Flags]
  43         public enum AddressOp {
  44                 Store = 1,
  45                 Load  = 2,
  46                 LoadStore = 3
  47         };
  48
  49         /// <summary>
  50         ///   This interface is implemented by variables
  51         /// </summary>
  52         public interface IMemoryLocation {
  53                 /// <summary>
  54                 ///   The AddressOf method should generate code that loads
  55                 ///   the address of the object and leaves it on the stack.
  56                 ///
  57                 ///   The `mode' argument is used to notify the expression
  58                 ///   of whether this will be used to read from the address or
  59                 ///   write to the address.
  60                 ///
  61                 ///   This is just a hint that can be used to provide good error
  62                 ///   reporting, and should have no other side effects.
  63                 /// </summary>
  64                 void AddressOf (EmitContext ec, AddressOp mode);
  65         }
  66
  67         /// <remarks>
  68         ///   Base class for expressions
  69         /// </remarks>
  70         public abstract class Expression {
  71                 public ExprClass eclass;
  72                 protected Type      type;
  73
  74                 public Type Type {
  75                         get {
  76                                 return type;
  77                         }
  78
  79                         set {
  80                                 type = value;
  81                         }
  82                 }
  83
  84                 /// <summary>
  85                 ///   Utility wrapper routine for Error, just to beautify the code
  86                 /// </summary>
  87                 static protected void Error (int error, string s)
  88                 {
  89                         Report.Error (error, s);
  90                 }
  91
  92                 static protected void Error (int error, Location loc, string s)
  93                 {
  94                         Report.Error (error, loc, s);
  95                 }
  96
  97                 /// <summary>
  98                 ///   Utility wrapper routine for Warning, just to beautify the code
  99                 /// </summary>
 100                 static protected void Warning (int warning, string s)
 101                 {
 102                         Report.Warning (warning, s);
 103                 }
 104
 105                 static public void Error_CannotConvertType (Location loc, Type source, Type target)
 106                 {
 107                         Report.Error (30, loc, "Cannot convert type '" +
 108                                       TypeManager.CSharpName (source) + "' to '" +
 109                                       TypeManager.CSharpName (target) + "'");
 110                 }
 111
 112                 /// <summary>
 113                 ///   Performs semantic analysis on the Expression
 114                 /// </summary>
 115                 ///
 116                 /// <remarks>
 117                 ///   The Resolve method is invoked to perform the semantic analysis
 118                 ///   on the node.
 119                 ///
 120                 ///   The return value is an expression (it can be the
 121                 ///   same expression in some cases) or a new
 122                 ///   expression that better represents this node.
 123                 ///
 124                 ///   For example, optimizations of Unary (LiteralInt)
 125                 ///   would return a new LiteralInt with a negated
 126                 ///   value.
 127                 ///
 128                 ///   If there is an error during semantic analysis,
 129                 ///   then an error should be reported (using Report)
 130                 ///   and a null value should be returned.
 131                 ///
 132                 ///   There are two side effects expected from calling
 133                 ///   Resolve(): the the field variable "eclass" should
 134                 ///   be set to any value of the enumeration
 135                 ///   `ExprClass' and the type variable should be set
 136                 ///   to a valid type (this is the type of the
 137                 ///   expression).
 138                 /// </remarks>
 139                 public abstract Expression DoResolve (EmitContext ec);
 140
 141                 public virtual Expression DoResolveLValue (EmitContext ec, Expression right_side)
 142                 {
 143                         return DoResolve (ec);
 144                 }
 145
 146                 /// <summary>
 147                 ///   Resolves an expression and performs semantic analysis on it.
 148                 /// </summary>
 149                 ///
 150                 /// <remarks>
 151                 ///   Currently Resolve wraps DoResolve to perform sanity
 152                 ///   checking and assertion checking on what we expect from Resolve.
 153                 /// </remarks>
 154                 public Expression Resolve (EmitContext ec)
 155                 {
 156                         Expression e = DoResolve (ec);
 157
 158                         if (e != null){
 159
 160                                 if (e is SimpleName){
 161                                         SimpleName s = (SimpleName) e;
 162
 163                                         Report.Error (
 164                                                       103, s.Location,
 165                                                       "The name `" + s.Name + "' could not be found in `" +
 166                                                       ec.DeclSpace.Name + "'");
 167                                         return null;
 168                                 }
 169
 170                                 if (e.eclass == ExprClass.Invalid)
 171                                         throw new Exception ("Expression " + e.GetType () +
 172                                                              " ExprClass is Invalid after resolve");
 173
 174                                 if (e.eclass != ExprClass.MethodGroup)
 175                                         if (e.type == null)
 176                                                 throw new Exception (
 177                                                         "Expression " + e.GetType () +
 178                                                         " did not set its type after Resolve\n" +
 179                                                         "called from: " + this.GetType ());
 180                         }
 181
 182                         return e;
 183                 }
 184
 185                 /// <summary>
 186                 ///   Performs expression resolution and semantic analysis, but
 187                 ///   allows SimpleNames to be returned.
 188                 /// </summary>
 189                 ///
 190                 /// <remarks>
 191                 ///   This is used by MemberAccess to construct long names that can not be
 192                 ///   partially resolved (namespace-qualified names for example).
 193                 /// </remarks>
 194                 public Expression ResolveWithSimpleName (EmitContext ec)
 195                 {
 196                         Expression e;
 197
 198                         if (this is SimpleName)
 199                                 e = ((SimpleName) this).DoResolveAllowStatic (ec);
 200                         else
 201                                 e = DoResolve (ec);
 202
 203                         if (e != null){
 204                                 if (e is SimpleName)
 205                                         return e;
 206
 207                                 if (e.eclass == ExprClass.Invalid)
 208                                         throw new Exception ("Expression " + e +
 209                                                              " ExprClass is Invalid after resolve");
 210
 211                                 if (e.eclass != ExprClass.MethodGroup)
 212                                         if (e.type == null)
 213                                                 throw new Exception ("Expression " + e +
 214                                                                      " did not set its type after Resolve");
 215                         }
 216
 217                         return e;
 218                 }
 219
 220                 /// <summary>
 221                 ///   Resolves an expression for LValue assignment
 222                 /// </summary>
 223                 ///
 224                 /// <remarks>
 225                 ///   Currently ResolveLValue wraps DoResolveLValue to perform sanity
 226                 ///   checking and assertion checking on what we expect from Resolve
 227                 /// </remarks>
 228                 public Expression ResolveLValue (EmitContext ec, Expression right_side)
 229                 {
 230                         Expression e = DoResolveLValue (ec, right_side);
 231
 232                         if (e != null){
 233                                 if (e is SimpleName){
 234                                         SimpleName s = (SimpleName) e;
 235
 236                                         Report.Error (
 237                                                 103, s.Location,
 238                                                 "The name `" + s.Name + "' could not be found in `" +
 239                                                 ec.DeclSpace.Name + "'");
 240                                         return null;
 241                                 }
 242
 243                                 if (e.eclass == ExprClass.Invalid)
 244                                         throw new Exception ("Expression " + e +
 245                                                              " ExprClass is Invalid after resolve");
 246
 247                                 if (e.eclass != ExprClass.MethodGroup)
 248                                         if (e.type == null)
 249                                                 throw new Exception ("Expression " + e +
 250                                                                      " did not set its type after Resolve");
 251                         }
 252
 253                         return e;
 254                 }
 255
 256                 /// <summary>
 257                 ///   Emits the code for the expression
 258                 /// </summary>
 259                 ///
 260                 /// <remarks>
 261                 ///   The Emit method is invoked to generate the code
 262                 ///   for the expression.
 263                 /// </remarks>
 264                 public abstract void Emit (EmitContext ec);
 265
 266                 /// <summary>
 267                 ///   Protected constructor.  Only derivate types should
 268                 ///   be able to be created
 269                 /// </summary>
 270
 271                 protected Expression ()
 272                 {
 273                         eclass = ExprClass.Invalid;
 274                         type = null;
 275                 }
 276
 277                 /// <summary>
 278                 ///   Returns a literalized version of a literal FieldInfo
 279                 /// </summary>
 280                 ///
 281                 /// <remarks>
 282                 ///   The possible return values are:
 283                 ///      IntConstant, UIntConstant
 284                 ///      LongLiteral, ULongConstant
 285                 ///      FloatConstant, DoubleConstant
 286                 ///      StringConstant
 287                 ///
 288                 ///   The value returned is already resolved.
 289                 /// </remarks>
 290                 public static Constant Constantify (object v, Type t)
 291                 {
 292                         if (t == TypeManager.int32_type)
 293                                 return new IntConstant ((int) v);
 294                         else if (t == TypeManager.uint32_type)
 295                                 return new UIntConstant ((uint) v);
 296                         else if (t == TypeManager.int64_type)
 297                                 return new LongConstant ((long) v);
 298                         else if (t == TypeManager.uint64_type)
 299                                 return new ULongConstant ((ulong) v);
 300                         else if (t == TypeManager.float_type)
 301                                 return new FloatConstant ((float) v);
 302                         else if (t == TypeManager.double_type)
 303                                 return new DoubleConstant ((double) v);
 304                         else if (t == TypeManager.string_type)
 305                                 return new StringConstant ((string) v);
 306                         else if (t == TypeManager.short_type)
 307                                 return new ShortConstant ((short)v);
 308                         else if (t == TypeManager.ushort_type)
 309                                 return new UShortConstant ((ushort)v);
 310                         else if (t == TypeManager.sbyte_type)
 311                                 return new SByteConstant (((sbyte)v));
 312                         else if (t == TypeManager.byte_type)
 313                                 return new ByteConstant ((byte)v);
 314                         else if (t == TypeManager.char_type)
 315                                 return new CharConstant ((char)v);
 316                         else if (t == TypeManager.bool_type)
 317                                 return new BoolConstant ((bool) v);
 318                         else if (TypeManager.IsEnumType (t)){
 319                                 Constant e = Constantify (v, v.GetType ());
 320
 321                                 return new EnumConstant (e, t);
 322                         } else
 323                                 throw new Exception ("Unknown type for constant (" + t +
 324                                                      "), details: " + v);
 325                 }
 326
 327                 /// <summary>
 328                 ///   Returns a fully formed expression after a MemberLookup
 329                 /// </summary>
 330                 public static Expression ExprClassFromMemberInfo (EmitContext ec, MemberInfo mi, Location loc)
 331                 {
 332                         if (mi is EventInfo)
 333                                 return new EventExpr ((EventInfo) mi, loc);
 334                         else if (mi is FieldInfo)
 335                                 return new FieldExpr ((FieldInfo) mi, loc);
 336                         else if (mi is PropertyInfo)
 337                                 return new PropertyExpr ((PropertyInfo) mi, loc);
 338                         else if (mi is Type){
 339                                 return new TypeExpr ((System.Type) mi);
 340                         }
 341
 342                         return null;
 343                 }
 344
 345                 //
 346                 // FIXME: Probably implement a cache for (t,name,current_access_set)?
 347                 //
 348                 // This code could use some optimizations, but we need to do some
 349                 // measurements.  For example, we could use a delegate to `flag' when
 350                 // something can not any longer be a method-group (because it is something
 351                 // else).
 352                 //
 353                 // Return values:
 354                 //     If the return value is an Array, then it is an array of
 355                 //     MethodBases
 356                 //
 357                 //     If the return value is an MemberInfo, it is anything, but a Method
 358                 //
 359                 //     null on error.
 360                 //
 361                 // FIXME: When calling MemberLookup inside an `Invocation', we should pass
 362                 // the arguments here and have MemberLookup return only the methods that
 363                 // match the argument count/type, unlike we are doing now (we delay this
 364                 // decision).
 365                 //
 366                 // This is so we can catch correctly attempts to invoke instance methods
 367                 // from a static body (scan for error 120 in ResolveSimpleName).
 368                 //
 369                 //
 370                 // FIXME: Potential optimization, have a static ArrayList
 371                 //
 372
 373                 public static Expression MemberLookup (EmitContext ec, Type t, string name,
 374                                                        MemberTypes mt, BindingFlags bf, Location loc)
 375                 {
 376                         MemberInfo [] mi = TypeManager.MemberLookup (ec.ContainerType, t, mt, bf, name);
 377
 378                         if (mi == null)
 379                                 return null;
 380
 381                         int count = mi.Length;
 382
 383                         if (count > 1)
 384                                 return new MethodGroupExpr (mi, loc);
 385
 386                         if (mi [0] is MethodBase)
 387                                 return new MethodGroupExpr (mi, loc);
 388
 389                         return ExprClassFromMemberInfo (ec, mi [0], loc);
 390                 }
 391
 392                 public const MemberTypes AllMemberTypes =
 393                         MemberTypes.Constructor |
 394                         MemberTypes.Event       |
 395                         MemberTypes.Field       |
 396                         MemberTypes.Method      |
 397                         MemberTypes.NestedType  |
 398                         MemberTypes.Property;
 399
 400                 public const BindingFlags AllBindingFlags =
 401                         BindingFlags.Public |
 402                         BindingFlags.Static |
 403                         BindingFlags.Instance;
 404
 405                 public static Expression MemberLookup (EmitContext ec, Type t, string name, Location loc)
 406                 {
 407                         return MemberLookup (ec, t, name, AllMemberTypes, AllBindingFlags, loc);
 408                 }
 409
 410                 public static Expression MethodLookup (EmitContext ec, Type t, string name, Location loc)
 411                 {
 412                         return MemberLookup (ec, t, name, MemberTypes.Method, AllBindingFlags, loc);
 413                 }
 414
 415                 /// <summary>
 416                 ///   This is a wrapper for MemberLookup that is not used to "probe", but
 417                 ///   to find a final definition.  If the final definition is not found, we
 418                 ///   look for private members and display a useful debugging message if we
 419                 ///   find it.
 420                 /// </summary>
 421                 public static Expression MemberLookupFinal (EmitContext ec, Type t, string name,
 422                                                             Location loc)
 423                 {
 424                         return MemberLookupFinal (ec, t, name, MemberTypes.Method, AllBindingFlags, loc);
 425                 }
 426
 427                 public static Expression MemberLookupFinal (EmitContext ec, Type t, string name,
 428                                                             MemberTypes mt, BindingFlags bf, Location loc)
 429                 {
 430                         Expression e;
 431
 432                         e = MemberLookup (ec, t, name, mt, bf, loc);
 433
 434                         if (e != null)
 435                                 return e;
 436
 437                         e = MemberLookup (ec, t, name, AllMemberTypes,
 438                                           AllBindingFlags | BindingFlags.NonPublic, loc);
 439                         if (e == null){
 440                                 Report.Error (
 441                                         117, loc, "`" + t + "' does not contain a definition " +
 442                                         "for `" + name + "'");
 443                         } else {
 444                                 Report.Error (
 445                                         122, loc, "`" + t + "." + name +
 446                                         "' is inaccessible due to its protection level");
 447                         }
 448
 449                         return null;
 450                 }
 451
 452                 static EmptyExpression MyEmptyExpr;
 453                 static public Expression ImplicitReferenceConversion (Expression expr, Type target_type)
 454                 {
 455                         Type expr_type = expr.Type;
 456
 457                         if (expr_type == null && expr.eclass == ExprClass.MethodGroup){
 458                                 // if we are a method group, emit a warning
 459
 460                                 expr.Emit (null);
 461                         }
 462
 463                         if (target_type == TypeManager.object_type) {
 464                                 //
 465                                 // A pointer type cannot be converted to object
 466                                 //
 467                                 if (expr_type.IsPointer)
 468                                         return null;
 469
 470                                 if (expr_type.IsValueType)
 471                                         return new BoxedCast (expr);
 472                                 if (expr_type.IsClass || expr_type.IsInterface)
 473                                         return new EmptyCast (expr, target_type);
 474                         } else if (expr_type.IsSubclassOf (target_type)) {
 475                                 return new EmptyCast (expr, target_type);
 476                         } else {
 477
 478                                 // This code is kind of mirrored inside StandardConversionExists
 479                                 // with the small distinction that we only probe there
 480                                 //
 481                                 // Always ensure that the code here and there is in sync
 482
 483                                 // from the null type to any reference-type.
 484                                 if (expr is NullLiteral && !target_type.IsValueType)
 485                                         return new EmptyCast (expr, target_type);
 486
 487                                 // from any class-type S to any interface-type T.
 488                                 if (expr_type.IsClass && target_type.IsInterface) {
 489                                         if (TypeManager.ImplementsInterface (expr_type, target_type))
 490                                                 return new EmptyCast (expr, target_type);
 491                                         else
 492                                                 return null;
 493                                 }
 494
 495                                 // from any interface type S to interface-type T.
 496                                 if (expr_type.IsInterface && target_type.IsInterface) {
 497
 498                                         if (TypeManager.ImplementsInterface (expr_type, target_type))
 499                                                 return new EmptyCast (expr, target_type);
 500                                         else
 501                                                 return null;
 502                                 }
 503
 504                                 // from an array-type S to an array-type of type T
 505                                 if (expr_type.IsArray && target_type.IsArray) {
 506                                         if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
 507
 508                                                 Type expr_element_type = expr_type.GetElementType ();
 509
 510                                                 if (MyEmptyExpr == null)
 511                                                         MyEmptyExpr = new EmptyExpression ();
 512
 513                                                 MyEmptyExpr.SetType (expr_element_type);
 514                                                 Type target_element_type = target_type.GetElementType ();
 515
 516                                                 if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
 517                                                         if (StandardConversionExists (MyEmptyExpr,
 518                                                                                       target_element_type))
 519                                                                 return new EmptyCast (expr, target_type);
 520                                         }
 521                                 }
 522
 523
 524                                 // from an array-type to System.Array
 525                                 if (expr_type.IsArray && target_type == TypeManager.array_type)
 526                                         return new EmptyCast (expr, target_type);
 527
 528                                 // from any delegate type to System.Delegate
 529                                 if (expr_type.IsSubclassOf (TypeManager.delegate_type) &&
 530                                     target_type == TypeManager.delegate_type)
 531                                         return new EmptyCast (expr, target_type);
 532
 533                                 // from any array-type or delegate type into System.ICloneable.
 534                                 if (expr_type.IsArray || expr_type.IsSubclassOf (TypeManager.delegate_type))
 535                                         if (target_type == TypeManager.icloneable_type)
 536                                                 return new EmptyCast (expr, target_type);
 537
 538                                 return null;
 539
 540                         }
 541
 542                         return null;
 543                 }
 544
 545                 /// <summary>
 546                 ///   Handles expressions like this: decimal d; d = 1;
 547                 ///   and changes them into: decimal d; d = new System.Decimal (1);
 548                 /// </summary>
 549                 static Expression InternalTypeConstructor (EmitContext ec, Expression expr, Type target)
 550                 {
 551                         ArrayList args = new ArrayList ();
 552
 553                         args.Add (new Argument (expr, Argument.AType.Expression));
 554
 555                         Expression ne = new New (target.FullName, args,
 556                                                  new Location (-1));
 557
 558                         return ne.Resolve (ec);
 559                 }
 560
 561                 /// <summary>
 562                 ///   Implicit Numeric Conversions.
 563                 ///
 564                 ///   expr is the expression to convert, returns a new expression of type
 565                 ///   target_type or null if an implicit conversion is not possible.
 566                 /// </summary>
 567                 static public Expression ImplicitNumericConversion (EmitContext ec, Expression expr,
 568                                                                     Type target_type, Location loc)
 569                 {
 570                         Type expr_type = expr.Type;
 571
 572                         //
 573                         // Attempt to do the implicit constant expression conversions
 574
 575                         if (expr is IntConstant){
 576                                 Expression e;
 577
 578                                 e = TryImplicitIntConversion (target_type, (IntConstant) expr);
 579
 580                                 if (e != null)
 581                                         return e;
 582                         } else if (expr is LongConstant && target_type == TypeManager.uint64_type){
 583                                 //
 584                                 // Try the implicit constant expression conversion
 585                                 // from long to ulong, instead of a nice routine,
 586                                 // we just inline it
 587                                 //
 588                                 long v = ((LongConstant) expr).Value;
 589                                 if (v > 0)
 590                                         return new ULongConstant ((ulong) v);
 591                         }
 592
 593                         //
 594                         // If we have an enumeration, extract the underlying type,
 595                         // use this during the comparission, but wrap around the original
 596                         // target_type
 597                         //
 598                         Type real_target_type = target_type;
 599
 600                         if (TypeManager.IsEnumType (real_target_type))
 601                                 real_target_type = TypeManager.EnumToUnderlying (real_target_type);
 602
 603                         if (expr_type == real_target_type)
 604                                 return new EmptyCast (expr, target_type);
 605
 606                         if (expr_type == TypeManager.sbyte_type){
 607                                 //
 608                                 // From sbyte to short, int, long, float, double.
 609                                 //
 610                                 if (real_target_type == TypeManager.int32_type)
 611                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 612                                 if (real_target_type == TypeManager.int64_type)
 613                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 614                                 if (real_target_type == TypeManager.double_type)
 615                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 616                                 if (real_target_type == TypeManager.float_type)
 617                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 618                                 if (real_target_type == TypeManager.short_type)
 619                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
 620                                 if (real_target_type == TypeManager.decimal_type)
 621                                         return InternalTypeConstructor (ec, expr, target_type);
 622                         } else if (expr_type == TypeManager.byte_type){
 623                                 //
 624                                 // From byte to short, ushort, int, uint, long, ulong, float, double
 625                                 //
 626                                 if ((real_target_type == TypeManager.short_type) ||
 627                                     (real_target_type == TypeManager.ushort_type) ||
 628                                     (real_target_type == TypeManager.int32_type) ||
 629                                     (real_target_type == TypeManager.uint32_type))
 630                                         return new EmptyCast (expr, target_type);
 631
 632                                 if (real_target_type == TypeManager.uint64_type)
 633                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 634                                 if (real_target_type == TypeManager.int64_type)
 635                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 636                                 if (real_target_type == TypeManager.float_type)
 637                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 638                                 if (real_target_type == TypeManager.double_type)
 639                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 640                                 if (real_target_type == TypeManager.decimal_type)
 641                                         return InternalTypeConstructor (ec, expr, target_type);
 642                         } else if (expr_type == TypeManager.short_type){
 643                                 //
 644                                 // From short to int, long, float, double
 645                                 //
 646                                 if (real_target_type == TypeManager.int32_type)
 647                                         return new EmptyCast (expr, target_type);
 648                                 if (real_target_type == TypeManager.int64_type)
 649                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 650                                 if (real_target_type == TypeManager.double_type)
 651                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 652                                 if (real_target_type == TypeManager.float_type)
 653                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 654                                 if (real_target_type == TypeManager.decimal_type)
 655                                         return InternalTypeConstructor (ec, expr, target_type);
 656                         } else if (expr_type == TypeManager.ushort_type){
 657                                 //
 658                                 // From ushort to int, uint, long, ulong, float, double
 659                                 //
 660                                 if (real_target_type == TypeManager.uint32_type)
 661                                         return new EmptyCast (expr, target_type);
 662
 663                                 if (real_target_type == TypeManager.uint64_type)
 664                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 665                                 if (real_target_type == TypeManager.int32_type)
 666                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 667                                 if (real_target_type == TypeManager.int64_type)
 668                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 669                                 if (real_target_type == TypeManager.double_type)
 670                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 671                                 if (real_target_type == TypeManager.float_type)
 672                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 673                                 if (real_target_type == TypeManager.decimal_type)
 674                                         return InternalTypeConstructor (ec, expr, target_type);
 675                         } else if (expr_type == TypeManager.int32_type){
 676                                 //
 677                                 // From int to long, float, double
 678                                 //
 679                                 if (real_target_type == TypeManager.int64_type)
 680                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 681                                 if (real_target_type == TypeManager.double_type)
 682                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 683                                 if (real_target_type == TypeManager.float_type)
 684                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 685                                 if (real_target_type == TypeManager.decimal_type)
 686                                         return InternalTypeConstructor (ec, expr, target_type);
 687                         } else if (expr_type == TypeManager.uint32_type){
 688                                 //
 689                                 // From uint to long, ulong, float, double
 690                                 //
 691                                 if (real_target_type == TypeManager.int64_type)
 692                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 693                                 if (real_target_type == TypeManager.uint64_type)
 694                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 695                                 if (real_target_type == TypeManager.double_type)
 696                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 697                                                                OpCodes.Conv_R8);
 698                                 if (real_target_type == TypeManager.float_type)
 699                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 700                                                                OpCodes.Conv_R4);
 701                                 if (real_target_type == TypeManager.decimal_type)
 702                                         return InternalTypeConstructor (ec, expr, target_type);
 703                         } else if ((expr_type == TypeManager.uint64_type) ||
 704                                    (expr_type == TypeManager.int64_type)){
 705                                 //
 706                                 // From long/ulong to float, double
 707                                 //
 708                                 if (real_target_type == TypeManager.double_type)
 709                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 710                                                                OpCodes.Conv_R8);
 711                                 if (real_target_type == TypeManager.float_type)
 712                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 713                                                                OpCodes.Conv_R4);
 714                                 if (real_target_type == TypeManager.decimal_type)
 715                                         return InternalTypeConstructor (ec, expr, target_type);
 716                         } else if (expr_type == TypeManager.char_type){
 717                                 //
 718                                 // From char to ushort, int, uint, long, ulong, float, double
 719                                 //
 720                                 if ((real_target_type == TypeManager.ushort_type) ||
 721                                     (real_target_type == TypeManager.int32_type) ||
 722                                     (real_target_type == TypeManager.uint32_type))
 723                                         return new EmptyCast (expr, target_type);
 724                                 if (real_target_type == TypeManager.uint64_type)
 725                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 726                                 if (real_target_type == TypeManager.int64_type)
 727                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 728                                 if (real_target_type == TypeManager.float_type)
 729                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 730                                 if (real_target_type == TypeManager.double_type)
 731                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 732                                 if (real_target_type == TypeManager.decimal_type)
 733                                         return InternalTypeConstructor (ec, expr, target_type);
 734                         } else if (expr_type == TypeManager.float_type){
 735                                 //
 736                                 // float to double
 737                                 //
 738                                 if (real_target_type == TypeManager.double_type)
 739                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 740                         }
 741
 742                         return null;
 743                 }
 744
 745                 /// <summary>
 746                 ///  Determines if a standard implicit conversion exists from
 747                 ///  expr_type to target_type
 748                 /// </summary>
 749                 public static bool StandardConversionExists (Expression expr, Type target_type)
 750                 {
 751                         Type expr_type = expr.Type;
 752
 753                         if (expr_type == target_type)
 754                                 return true;
 755
 756                         // First numeric conversions
 757
 758                         if (expr_type == TypeManager.sbyte_type){
 759                                 //
 760                                 // From sbyte to short, int, long, float, double.
 761                                 //
 762                                 if ((target_type == TypeManager.int32_type) ||
 763                                     (target_type == TypeManager.int64_type) ||
 764                                     (target_type == TypeManager.double_type) ||
 765                                     (target_type == TypeManager.float_type)  ||
 766                                     (target_type == TypeManager.short_type) ||
 767                                     (target_type == TypeManager.decimal_type))
 768                                         return true;
 769
 770                         } else if (expr_type == TypeManager.byte_type){
 771                                 //
 772                                 // From byte to short, ushort, int, uint, long, ulong, float, double
 773                                 //
 774                                 if ((target_type == TypeManager.short_type) ||
 775                                     (target_type == TypeManager.ushort_type) ||
 776                                     (target_type == TypeManager.int32_type) ||
 777                                     (target_type == TypeManager.uint32_type) ||
 778                                     (target_type == TypeManager.uint64_type) ||
 779                                     (target_type == TypeManager.int64_type) ||
 780                                     (target_type == TypeManager.float_type) ||
 781                                     (target_type == TypeManager.double_type) ||
 782                                     (target_type == TypeManager.decimal_type))
 783                                         return true;
 784
 785                         } else if (expr_type == TypeManager.short_type){
 786                                 //
 787                                 // From short to int, long, float, double
 788                                 //
 789                                 if ((target_type == TypeManager.int32_type) ||
 790                                     (target_type == TypeManager.int64_type) ||
 791                                     (target_type == TypeManager.double_type) ||
 792                                     (target_type == TypeManager.float_type) ||
 793                                     (target_type == TypeManager.decimal_type))
 794                                         return true;
 795
 796                         } else if (expr_type == TypeManager.ushort_type){
 797                                 //
 798                                 // From ushort to int, uint, long, ulong, float, double
 799                                 //
 800                                 if ((target_type == TypeManager.uint32_type) ||
 801                                     (target_type == TypeManager.uint64_type) ||
 802                                     (target_type == TypeManager.int32_type) ||
 803                                     (target_type == TypeManager.int64_type) ||
 804                                     (target_type == TypeManager.double_type) ||
 805                                     (target_type == TypeManager.float_type) ||
 806                                     (target_type == TypeManager.decimal_type))
 807                                         return true;
 808
 809                         } else if (expr_type == TypeManager.int32_type){
 810                                 //
 811                                 // From int to long, float, double
 812                                 //
 813                                 if ((target_type == TypeManager.int64_type) ||
 814                                     (target_type == TypeManager.double_type) ||
 815                                     (target_type == TypeManager.float_type) ||
 816                                     (target_type == TypeManager.decimal_type))
 817                                         return true;
 818
 819                         } else if (expr_type == TypeManager.uint32_type){
 820                                 //
 821                                 // From uint to long, ulong, float, double
 822                                 //
 823                                 if ((target_type == TypeManager.int64_type) ||
 824                                     (target_type == TypeManager.uint64_type) ||
 825                                     (target_type == TypeManager.double_type) ||
 826                                     (target_type == TypeManager.float_type) ||
 827                                     (target_type == TypeManager.decimal_type))
 828                                         return true;
 829
 830                         } else if ((expr_type == TypeManager.uint64_type) ||
 831                                    (expr_type == TypeManager.int64_type)) {
 832                                 //
 833                                 // From long/ulong to float, double
 834                                 //
 835                                 if ((target_type == TypeManager.double_type) ||
 836                                     (target_type == TypeManager.float_type) ||
 837                                     (target_type == TypeManager.decimal_type))
 838                                         return true;
 839
 840                         } else if (expr_type == TypeManager.char_type){
 841                                 //
 842                                 // From char to ushort, int, uint, long, ulong, float, double
 843                                 //
 844                                 if ((target_type == TypeManager.ushort_type) ||
 845                                     (target_type == TypeManager.int32_type) ||
 846                                     (target_type == TypeManager.uint32_type) ||
 847                                     (target_type == TypeManager.uint64_type) ||
 848                                     (target_type == TypeManager.int64_type) ||
 849                                     (target_type == TypeManager.float_type) ||
 850                                     (target_type == TypeManager.double_type) ||
 851                                     (target_type == TypeManager.decimal_type))
 852                                         return true;
 853
 854                         } else if (expr_type == TypeManager.float_type){
 855                                 //
 856                                 // float to double
 857                                 //
 858                                 if (target_type == TypeManager.double_type)
 859                                         return true;
 860                         }
 861
 862                         // Next reference conversions
 863
 864                         if (target_type == TypeManager.object_type) {
 865                                 if ((expr_type.IsClass) ||
 866                                     (expr_type.IsValueType) ||
 867                                     (expr_type.IsInterface))
 868                                         return true;
 869
 870                         } else if (expr_type.IsSubclassOf (target_type)) {
 871                                 return true;
 872
 873                         } else {
 874                                 // Please remember that all code below actually comes
 875                                 // from ImplicitReferenceConversion so make sure code remains in sync
 876
 877                                 // from any class-type S to any interface-type T.
 878                                 if (expr_type.IsClass && target_type.IsInterface) {
 879                                         if (TypeManager.ImplementsInterface (expr_type, target_type))
 880                                                 return true;
 881                                 }
 882
 883                                 // from any interface type S to interface-type T.
 884                                 // FIXME : Is it right to use IsAssignableFrom ?
 885                                 if (expr_type.IsInterface && target_type.IsInterface)
 886                                         if (target_type.IsAssignableFrom (expr_type))
 887                                                 return true;
 888
 889                                 // from an array-type S to an array-type of type T
 890                                 if (expr_type.IsArray && target_type.IsArray) {
 891                                         if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
 892
 893                                                 Type expr_element_type = expr_type.GetElementType ();
 894
 895                                                 if (MyEmptyExpr == null)
 896                                                         MyEmptyExpr = new EmptyExpression ();
 897
 898                                                 MyEmptyExpr.SetType (expr_element_type);
 899                                                 Type target_element_type = target_type.GetElementType ();
 900
 901                                                 if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
 902                                                         if (StandardConversionExists (MyEmptyExpr,
 903                                                                                       target_element_type))
 904                                                                 return true;
 905                                         }
 906                                 }
 907
 908                                 // from an array-type to System.Array
 909                                 if (expr_type.IsArray && target_type.IsAssignableFrom (expr_type))
 910                                         return true;
 911
 912                                 // from any delegate type to System.Delegate
 913                                 if (expr_type.IsSubclassOf (TypeManager.delegate_type) &&
 914                                     target_type == TypeManager.delegate_type)
 915                                         if (target_type.IsAssignableFrom (expr_type))
 916                                                 return true;
 917
 918                                 // from any array-type or delegate type into System.ICloneable.
 919                                 if (expr_type.IsArray || expr_type.IsSubclassOf (TypeManager.delegate_type))
 920                                         if (target_type == TypeManager.icloneable_type)
 921                                                 return true;
 922
 923                                 // from the null type to any reference-type.
 924                                 if (expr is NullLiteral && !target_type.IsValueType)
 925                                         return true;
 926
 927                         }
 928
 929                         if (expr is IntConstant){
 930                                 int value = ((IntConstant) expr).Value;
 931
 932                                 if (target_type == TypeManager.sbyte_type){
 933                                         if (value >= SByte.MinValue && value <= SByte.MaxValue)
 934                                                 return true;
 935                                 } else if (target_type == TypeManager.byte_type){
 936                                         if (Byte.MinValue >= 0 && value <= Byte.MaxValue)
 937                                                 return true;
 938                                 } else if (target_type == TypeManager.short_type){
 939                                         if (value >= Int16.MinValue && value <= Int16.MaxValue)
 940                                                 return true;
 941                                 } else if (target_type == TypeManager.ushort_type){
 942                                         if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
 943                                                 return true;
 944                                 } else if (target_type == TypeManager.uint32_type){
 945                                         if (value >= 0)
 946                                                 return true;
 947                                 } else if (target_type == TypeManager.uint64_type){
 948                                          //
 949                                          // we can optimize this case: a positive int32
 950                                          // always fits on a uint64.  But we need an opcode
 951                                          // to do it.
 952                                          //
 953                                         if (value >= 0)
 954                                                 return true;
 955                                 }
 956
 957                                 if (value == 0 && expr is IntLiteral && TypeManager.IsEnumType (target_type))
 958                                         return true;
 959                         }
 960
 961                         if (expr is LongConstant && target_type == TypeManager.uint64_type){
 962                                 //
 963                                 // Try the implicit constant expression conversion
 964                                 // from long to ulong, instead of a nice routine,
 965                                 // we just inline it
 966                                 //
 967                                 long v = ((LongConstant) expr).Value;
 968                                 if (v > 0)
 969                                         return true;
 970                         }
 971
 972                         if (target_type.IsSubclassOf (TypeManager.enum_type) && expr is IntLiteral){
 973                                 IntLiteral i = (IntLiteral) expr;
 974
 975                                 if (i.Value == 0)
 976                                         return true;
 977                         }
 978                         return false;
 979                 }
 980
 981                 //
 982                 // Used internally by FindMostEncompassedType, this is used
 983                 // to avoid creating lots of objects in the tight loop inside
 984                 // FindMostEncompassedType
 985                 //
 986                 static EmptyExpression priv_fmet_param;
 987
 988                 /// <summary>
 989                 ///  Finds "most encompassed type" according to the spec (13.4.2)
 990                 ///  amongst the methods in the MethodGroupExpr
 991                 /// </summary>
 992                 static Type FindMostEncompassedType (ArrayList types)
 993                 {
 994                         Type best = null;
 995
 996                         if (priv_fmet_param == null)
 997                                 priv_fmet_param = new EmptyExpression ();
 998
 999                         foreach (Type t in types){
1000                                 priv_fmet_param.SetType (t);
1001
1002                                 if (best == null) {
1003                                         best = t;
1004                                         continue;
1005                                 }
1006
1007                                 if (StandardConversionExists (priv_fmet_param, best))
1008                                         best = t;
1009                         }
1010
1011                         return best;
1012                 }
1013
1014                 //
1015                 // Used internally by FindMostEncompassingType, this is used
1016                 // to avoid creating lots of objects in the tight loop inside
1017                 // FindMostEncompassingType
1018                 //
1019                 static EmptyExpression priv_fmee_ret;
1020
1021                 /// <summary>
1022                 ///  Finds "most encompassing type" according to the spec (13.4.2)
1023                 ///  amongst the types in the given set
1024                 /// </summary>
1025                 static Type FindMostEncompassingType (ArrayList types)
1026                 {
1027                         Type best = null;
1028
1029                         if (priv_fmee_ret == null)
1030                                 priv_fmee_ret = new EmptyExpression ();
1031
1032                         foreach (Type t in types){
1033                                 priv_fmee_ret.SetType (best);
1034
1035                                 if (best == null) {
1036                                         best = t;
1037                                         continue;
1038                                 }
1039
1040                                 if (StandardConversionExists (priv_fmee_ret, t))
1041                                         best = t;
1042                         }
1043
1044                         return best;
1045                 }
1046
1047                 //
1048                 // Used to avoid creating too many objects
1049                 //
1050                 static EmptyExpression priv_fms_expr;
1051
1052                 /// <summary>
1053                 ///   Finds the most specific source Sx according to the rules of the spec (13.4.4)
1054                 ///   by making use of FindMostEncomp* methods. Applies the correct rules separately
1055                 ///   for explicit and implicit conversion operators.
1056                 /// </summary>
1057                 static public Type FindMostSpecificSource (MethodGroupExpr me, Type source_type,
1058                                                            bool apply_explicit_conv_rules,
1059                                                            Location loc)
1060                 {
1061                         ArrayList src_types_set = new ArrayList ();
1062
1063                         if (priv_fms_expr == null)
1064                                 priv_fms_expr = new EmptyExpression ();
1065
1066                         //
1067                         // If any operator converts from S then Sx = S
1068                         //
1069                         foreach (MethodBase mb in me.Methods){
1070                                 ParameterData pd = Invocation.GetParameterData (mb);
1071                                 Type param_type = pd.ParameterType (0);
1072
1073                                 if (param_type == source_type)
1074                                         return param_type;
1075
1076                                 if (apply_explicit_conv_rules) {
1077                                         //
1078                                         // From the spec :
1079                                         // Find the set of applicable user-defined conversion operators, U.  This set
1080                                         // consists of the
1081                                         // user-defined implicit or explicit conversion operators declared by
1082                                         // the classes or structs in D that convert from a type encompassing
1083                                         // or encompassed by S to a type encompassing or encompassed by T
1084                                         //
1085                                         priv_fms_expr.SetType (param_type);
1086                                         if (StandardConversionExists (priv_fms_expr, source_type))
1087                                                 src_types_set.Add (param_type);
1088                                         else {
1089                                                 priv_fms_expr.SetType (source_type);
1090                                                 if (StandardConversionExists (priv_fms_expr, param_type))
1091                                                         src_types_set.Add (param_type);
1092                                         }
1093                                 } else {
1094                                         //
1095                                         // Only if S is encompassed by param_type
1096                                         //
1097                                         priv_fms_expr.SetType (source_type);
1098                                         if (StandardConversionExists (priv_fms_expr, param_type))
1099                                                 src_types_set.Add (param_type);
1100                                 }
1101                         }
1102
1103                         //
1104                         // Explicit Conv rules
1105                         //
1106                         if (apply_explicit_conv_rules) {
1107                                 ArrayList candidate_set = new ArrayList ();
1108
1109                                 foreach (Type param_type in src_types_set){
1110                                         priv_fms_expr.SetType (source_type);
1111
1112                                         if (StandardConversionExists (priv_fms_expr, param_type))
1113                                                 candidate_set.Add (param_type);
1114                                 }
1115
1116                                 if (candidate_set.Count != 0)
1117                                         return FindMostEncompassedType (candidate_set);
1118                         }
1119
1120                         //
1121                         // Final case
1122                         //
1123                         if (apply_explicit_conv_rules)
1124                                 return FindMostEncompassingType (src_types_set);
1125                         else
1126                                 return FindMostEncompassedType (src_types_set);
1127                 }
1128
1129                 //
1130                 // Useful in avoiding proliferation of objects
1131                 //
1132                 static EmptyExpression priv_fmt_expr;
1133
1134                 /// <summary>
1135                 ///  Finds the most specific target Tx according to section 13.4.4
1136                 /// </summary>
1137                 static public Type FindMostSpecificTarget (MethodGroupExpr me, Type target,
1138                                                            bool apply_explicit_conv_rules,
1139                                                            Location loc)
1140                 {
1141                         ArrayList tgt_types_set = new ArrayList ();
1142
1143                         if (priv_fmt_expr == null)
1144                                 priv_fmt_expr = new EmptyExpression ();
1145
1146                         //
1147                         // If any operator converts to T then Tx = T
1148                         //
1149                         foreach (MethodInfo mi in me.Methods){
1150                                 Type ret_type = mi.ReturnType;
1151
1152                                 if (ret_type == target)
1153                                         return ret_type;
1154
1155                                 if (apply_explicit_conv_rules) {
1156                                         //
1157                                         // From the spec :
1158                                         // Find the set of applicable user-defined conversion operators, U.
1159                                         //
1160                                         // This set consists of the
1161                                         // user-defined implicit or explicit conversion operators declared by
1162                                         // the classes or structs in D that convert from a type encompassing
1163                                         // or encompassed by S to a type encompassing or encompassed by T
1164                                         //
1165                                         priv_fms_expr.SetType (ret_type);
1166                                         if (StandardConversionExists (priv_fms_expr, target))
1167                                                 tgt_types_set.Add (ret_type);
1168                                         else {
1169                                                 priv_fms_expr.SetType (target);
1170                                                 if (StandardConversionExists (priv_fms_expr, ret_type))
1171                                                         tgt_types_set.Add (ret_type);
1172                                         }
1173                                 } else {
1174                                         //
1175                                         // Only if T is encompassed by param_type
1176                                         //
1177                                         priv_fms_expr.SetType (ret_type);
1178                                         if (StandardConversionExists (priv_fms_expr, target))
1179                                                 tgt_types_set.Add (ret_type);
1180                                 }
1181                         }
1182
1183                         //
1184                         // Explicit conv rules
1185                         //
1186                         if (apply_explicit_conv_rules) {
1187                                 ArrayList candidate_set = new ArrayList ();
1188
1189                                 foreach (Type ret_type in tgt_types_set){
1190                                         priv_fmt_expr.SetType (ret_type);
1191
1192                                         if (StandardConversionExists (priv_fmt_expr, target))
1193                                                 candidate_set.Add (ret_type);
1194                                 }
1195
1196                                 if (candidate_set.Count != 0)
1197                                         return FindMostEncompassingType (candidate_set);
1198                         }
1199
1200                         //
1201                         // Okay, final case !
1202                         //
1203                         if (apply_explicit_conv_rules)
1204                                 return FindMostEncompassedType (tgt_types_set);
1205                         else
1206                                 return FindMostEncompassingType (tgt_types_set);
1207                 }
1208
1209                 /// <summary>
1210                 ///  User-defined Implicit conversions
1211                 /// </summary>
1212                 static public Expression ImplicitUserConversion (EmitContext ec, Expression source,
1213                                                                  Type target, Location loc)
1214                 {
1215                         return UserDefinedConversion (ec, source, target, loc, false);
1216                 }
1217
1218                 /// <summary>
1219                 ///  User-defined Explicit conversions
1220                 /// </summary>
1221                 static public Expression ExplicitUserConversion (EmitContext ec, Expression source,
1222                                                                  Type target, Location loc)
1223                 {
1224                         return UserDefinedConversion (ec, source, target, loc, true);
1225                 }
1226
1227                 /// <summary>
1228                 ///   Computes the MethodGroup for the user-defined conversion
1229                 ///   operators from source_type to target_type.  `look_for_explicit'
1230                 ///   controls whether we should also include the list of explicit
1231                 ///   operators
1232                 /// </summary>
1233                 static MethodGroupExpr GetConversionOperators (EmitContext ec,
1234                                                                Type source_type, Type target_type,
1235                                                                Location loc, bool look_for_explicit)
1236                 {
1237                         Expression mg1 = null, mg2 = null;
1238                         Expression mg5 = null, mg6 = null, mg7 = null, mg8 = null;
1239                         string op_name;
1240
1241                         //
1242                         // FIXME : How does the False operator come into the picture ?
1243                         // This doesn't look complete and very correct !
1244                         //
1245                         if (target_type == TypeManager.bool_type && !look_for_explicit)
1246                                 op_name = "op_True";
1247                         else
1248                                 op_name = "op_Implicit";
1249
1250                         MethodGroupExpr union3;
1251
1252                         mg1 = MethodLookup (ec, source_type, op_name, loc);
1253                         if (source_type.BaseType != null)
1254                                 mg2 = MethodLookup (ec, source_type.BaseType, op_name, loc);
1255
1256                         if (mg1 == null)
1257                                 union3 = (MethodGroupExpr) mg2;
1258                         else if (mg2 == null)
1259                                 union3 = (MethodGroupExpr) mg1;
1260                         else
1261                                 union3 = Invocation.MakeUnionSet (mg1, mg2, loc);
1262
1263                         mg1 = MethodLookup (ec, target_type, op_name, loc);
1264                         if (mg1 != null){
1265                                 if (union3 != null)
1266                                         union3 = Invocation.MakeUnionSet (union3, mg1, loc);
1267                                 else
1268                                         union3 = (MethodGroupExpr) mg1;
1269                         }
1270
1271                         if (target_type.BaseType != null)
1272                                 mg1 = MethodLookup (ec, target_type.BaseType, op_name, loc);
1273
1274                         if (mg1 != null){
1275                                 if (union3 != null)
1276                                         union3 = Invocation.MakeUnionSet (union3, mg1, loc);
1277                                 else
1278                                         union3 = (MethodGroupExpr) mg1;
1279                         }
1280
1281                         MethodGroupExpr union4 = null;
1282
1283                         if (look_for_explicit) {
1284                                 op_name = "op_Explicit";
1285
1286                                 mg5 = MemberLookup (ec, source_type, op_name, loc);
1287                                 if (source_type.BaseType != null)
1288                                         mg6 = MethodLookup (ec, source_type.BaseType, op_name, loc);
1289
1290                                 mg7 = MemberLookup (ec, target_type, op_name, loc);
1291                                 if (target_type.BaseType != null)
1292                                         mg8 = MethodLookup (ec, target_type.BaseType, op_name, loc);
1293
1294                                 MethodGroupExpr union5 = Invocation.MakeUnionSet (mg5, mg6, loc);
1295                                 MethodGroupExpr union6 = Invocation.MakeUnionSet (mg7, mg8, loc);
1296
1297                                 union4 = Invocation.MakeUnionSet (union5, union6, loc);
1298                         }
1299
1300                         return Invocation.MakeUnionSet (union3, union4, loc);
1301                 }
1302
1303                 /// <summary>
1304                 ///   User-defined conversions
1305                 /// </summary>
1306                 static public Expression UserDefinedConversion (EmitContext ec, Expression source,
1307                                                                 Type target, Location loc,
1308                                                                 bool look_for_explicit)
1309                 {
1310                         MethodGroupExpr union;
1311                         Type source_type = source.Type;
1312                         MethodBase method = null;
1313
1314                         union = GetConversionOperators (ec, source_type, target, loc, look_for_explicit);
1315                         if (union == null)
1316                                 return null;
1317
1318                         Type most_specific_source, most_specific_target;
1319
1320 #if BLAH
1321                         foreach (MethodBase m in union.Methods){
1322                                 Console.WriteLine ("Name: " + m.Name);
1323                                 Console.WriteLine ("    : " + ((MethodInfo)m).ReturnType);
1324                         }
1325 #endif
1326
1327                         most_specific_source = FindMostSpecificSource (union, source_type, look_for_explicit, loc);
1328                         if (most_specific_source == null)
1329                                 return null;
1330
1331                         most_specific_target = FindMostSpecificTarget (union, target, look_for_explicit, loc);
1332                         if (most_specific_target == null)
1333                                 return null;
1334
1335                         Console.WriteLine ("S:T" + most_specific_source + ":" + most_specific_target);
1336                         int count = 0;
1337
1338                         foreach (MethodBase mb in union.Methods){
1339                                 ParameterData pd = Invocation.GetParameterData (mb);
1340                                 MethodInfo mi = (MethodInfo) mb;
1341
1342                                 if (pd.ParameterType (0) == most_specific_source &&
1343                                     mi.ReturnType == most_specific_target) {
1344                                         method = mb;
1345                                         count++;
1346                                 }
1347                         }
1348
1349                         if (method == null || count > 1) {
1350                                 Report.Error (-11, loc, "Ambiguous user defined conversion");
1351                                 return null;
1352                         }
1353
1354                         //
1355                         // This will do the conversion to the best match that we
1356                         // found.  Now we need to perform an implict standard conversion
1357                         // if the best match was not the type that we were requested
1358                         // by target.
1359                         //
1360                         if (look_for_explicit)
1361                                 source = ConvertExplicitStandard (ec, source, most_specific_source, loc);
1362                         else
1363                                 source = ConvertImplicitStandard (ec, source, most_specific_source, loc);
1364
1365                         if (source == null)
1366                                 return null;
1367
1368                         Expression e;
1369                         e =  new UserCast ((MethodInfo) method, source);
1370                         if (e.Type != target){
1371                                 if (!look_for_explicit)
1372                                         e = ConvertImplicitStandard (ec, e, target, loc);
1373                                 else
1374                                         e = ConvertExplicitStandard (ec, e, target, loc);
1375                         }
1376                         return e;
1377                 }
1378
1379                 /// <summary>
1380                 ///   Converts implicitly the resolved expression `expr' into the
1381                 ///   `target_type'.  It returns a new expression that can be used
1382                 ///   in a context that expects a `target_type'.
1383                 /// </summary>
1384                 static public Expression ConvertImplicit (EmitContext ec, Expression expr,
1385                                                           Type target_type, Location loc)
1386                 {
1387                         Type expr_type = expr.Type;
1388                         Expression e;
1389
1390                         if (expr_type == target_type)
1391                                 return expr;
1392
1393                         if (target_type == null)
1394                                 throw new Exception ("Target type is null");
1395
1396                         e = ConvertImplicitStandard (ec, expr, target_type, loc);
1397                         if (e != null)
1398                                 return e;
1399
1400                         e = ImplicitUserConversion (ec, expr, target_type, loc);
1401                         if (e != null)
1402                                 return e;
1403
1404                         return null;
1405                 }
1406
1407
1408                 /// <summary>
1409                 ///   Attempts to apply the `Standard Implicit
1410                 ///   Conversion' rules to the expression `expr' into
1411                 ///   the `target_type'.  It returns a new expression
1412                 ///   that can be used in a context that expects a
1413                 ///   `target_type'.
1414                 ///
1415                 ///   This is different from `ConvertImplicit' in that the
1416                 ///   user defined implicit conversions are excluded.
1417                 /// </summary>
1418                 static public Expression ConvertImplicitStandard (EmitContext ec, Expression expr,
1419                                                                   Type target_type, Location loc)
1420                 {
1421                         Type expr_type = expr.Type;
1422                         Expression e;
1423
1424                         if (expr_type == target_type)
1425                                 return expr;
1426
1427                         e = ImplicitNumericConversion (ec, expr, target_type, loc);
1428                         if (e != null)
1429                                 return e;
1430
1431                         e = ImplicitReferenceConversion (expr, target_type);
1432                         if (e != null)
1433                                 return e;
1434
1435                         if (target_type.IsSubclassOf (TypeManager.enum_type) && expr is IntLiteral){
1436                                 IntLiteral i = (IntLiteral) expr;
1437
1438                                 if (i.Value == 0)
1439                                         return new EmptyCast (expr, target_type);
1440                         }
1441
1442                         if (ec.InUnsafe) {
1443                                 if (expr_type.IsPointer){
1444                                         if (target_type == TypeManager.void_ptr_type)
1445                                                 return new EmptyCast (expr, target_type);
1446
1447                                         //
1448                                         // yep, comparing pointer types cant be done with
1449                                         // t1 == t2, we have to compare their element types.
1450                                         //
1451                                         if (target_type.IsPointer){
1452                                                 if (target_type.GetElementType()==expr_type.GetElementType())
1453                                                         return expr;
1454                                         }
1455                                 }
1456
1457                                 if (target_type.IsPointer){
1458                                         if (expr is NullLiteral)
1459                                                 return new EmptyCast (expr, target_type);
1460                                 }
1461                         }
1462
1463                         return null;
1464                 }
1465
1466                 /// <summary>
1467                 ///   Attemps to perform an implict constant conversion of the IntConstant
1468                 ///   into a different data type using casts (See Implicit Constant
1469                 ///   Expression Conversions)
1470                 /// </summary>
1471                 static protected Expression TryImplicitIntConversion (Type target_type, IntConstant ic)
1472                 {
1473                         int value = ic.Value;
1474
1475                         //
1476                         // FIXME: This could return constants instead of EmptyCasts
1477                         //
1478                         if (target_type == TypeManager.sbyte_type){
1479                                 if (value >= SByte.MinValue && value <= SByte.MaxValue)
1480                                         return new SByteConstant ((sbyte) value);
1481                         } else if (target_type == TypeManager.byte_type){
1482                                 if (Byte.MinValue >= 0 && value <= Byte.MaxValue)
1483                                         return new ByteConstant ((byte) value);
1484                         } else if (target_type == TypeManager.short_type){
1485                                 if (value >= Int16.MinValue && value <= Int16.MaxValue)
1486                                         return new ShortConstant ((short) value);
1487                         } else if (target_type == TypeManager.ushort_type){
1488                                 if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
1489                                         return new UShortConstant ((ushort) value);
1490                         } else if (target_type == TypeManager.uint32_type){
1491                                 if (value >= 0)
1492                                         return new UIntConstant ((uint) value);
1493                         } else if (target_type == TypeManager.uint64_type){
1494                                 //
1495                                 // we can optimize this case: a positive int32
1496                                 // always fits on a uint64.  But we need an opcode
1497                                 // to do it.
1498                                 //
1499                                 if (value >= 0)
1500                                         return new ULongConstant ((ulong) value);
1501                         }
1502
1503                         if (value == 0 && ic is IntLiteral && TypeManager.IsEnumType (target_type))
1504                                 return new EnumConstant (ic, target_type);
1505
1506                         return null;
1507                 }
1508
1509                 static public void Error_CannotConvertImplicit (Location loc, Type source, Type target)
1510                 {
1511                         string msg = "Cannot convert implicitly from `"+
1512                                 TypeManager.CSharpName (source) + "' to `" +
1513                                 TypeManager.CSharpName (target) + "'";
1514
1515                         Error (29, loc, msg);
1516                 }
1517
1518                 /// <summary>
1519                 ///   Attemptes to implicityly convert `target' into `type', using
1520                 ///   ConvertImplicit.  If there is no implicit conversion, then
1521                 ///   an error is signaled
1522                 /// </summary>
1523                 static public Expression ConvertImplicitRequired (EmitContext ec, Expression source,
1524                                                                   Type target_type, Location loc)
1525                 {
1526                         Expression e;
1527
1528                         e = ConvertImplicit (ec, source, target_type, loc);
1529                         if (e != null)
1530                                 return e;
1531
1532                         if (source is DoubleLiteral && target_type == TypeManager.float_type){
1533                                 Error (664, loc,
1534                                        "Double literal cannot be implicitly converted to " +
1535                                        "float type, use F suffix to create a float literal");
1536                         }
1537
1538                         Error_CannotConvertImplicit (loc, source.Type, target_type);
1539
1540                         return null;
1541                 }
1542
1543                 /// <summary>
1544                 ///   Performs the explicit numeric conversions
1545                 /// </summary>
1546                 static Expression ConvertNumericExplicit (EmitContext ec, Expression expr,
1547                                                           Type target_type)
1548                 {
1549                         Type expr_type = expr.Type;
1550
1551                         //
1552                         // If we have an enumeration, extract the underlying type,
1553                         // use this during the comparission, but wrap around the original
1554                         // target_type
1555                         //
1556                         Type real_target_type = target_type;
1557
1558                         if (TypeManager.IsEnumType (real_target_type))
1559                                 real_target_type = TypeManager.EnumToUnderlying (real_target_type);
1560
1561                         if (expr_type == TypeManager.sbyte_type){
1562                                 //
1563                                 // From sbyte to byte, ushort, uint, ulong, char
1564                                 //
1565                                 if (real_target_type == TypeManager.byte_type)
1566                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U1);
1567                                 if (real_target_type == TypeManager.ushort_type)
1568                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U2);
1569                                 if (real_target_type == TypeManager.uint32_type)
1570                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U4);
1571                                 if (real_target_type == TypeManager.uint64_type)
1572                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U8);
1573                                 if (real_target_type == TypeManager.char_type)
1574                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_CH);
1575                         } else if (expr_type == TypeManager.byte_type){
1576                                 //
1577                                 // From byte to sbyte and char
1578                                 //
1579                                 if (real_target_type == TypeManager.sbyte_type)
1580                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U1_I1);
1581                                 if (real_target_type == TypeManager.char_type)
1582                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U1_CH);
1583                         } else if (expr_type == TypeManager.short_type){
1584                                 //
1585                                 // From short to sbyte, byte, ushort, uint, ulong, char
1586                                 //
1587                                 if (real_target_type == TypeManager.sbyte_type)
1588                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_I1);
1589                                 if (real_target_type == TypeManager.byte_type)
1590                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U1);
1591                                 if (real_target_type == TypeManager.ushort_type)
1592                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U2);
1593                                 if (real_target_type == TypeManager.uint32_type)
1594                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U4);
1595                                 if (real_target_type == TypeManager.uint64_type)
1596                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U8);
1597                                 if (real_target_type == TypeManager.char_type)
1598                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_CH);
1599                         } else if (expr_type == TypeManager.ushort_type){
1600                                 //
1601                                 // From ushort to sbyte, byte, short, char
1602                                 //
1603                                 if (real_target_type == TypeManager.sbyte_type)
1604                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_I1);
1605                                 if (real_target_type == TypeManager.byte_type)
1606                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_U1);
1607                                 if (real_target_type == TypeManager.short_type)
1608                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_I2);
1609                                 if (real_target_type == TypeManager.char_type)
1610                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_CH);
1611                         } else if (expr_type == TypeManager.int32_type){
1612                                 //
1613                                 // From int to sbyte, byte, short, ushort, uint, ulong, char
1614                                 //
1615                                 if (real_target_type == TypeManager.sbyte_type)
1616                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_I1);
1617                                 if (real_target_type == TypeManager.byte_type)
1618                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U1);
1619                                 if (real_target_type == TypeManager.short_type)
1620                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_I2);
1621                                 if (real_target_type == TypeManager.ushort_type)
1622                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U2);
1623                                 if (real_target_type == TypeManager.uint32_type)
1624                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U4);
1625                                 if (real_target_type == TypeManager.uint64_type)
1626                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U8);
1627                                 if (real_target_type == TypeManager.char_type)
1628                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_CH);
1629                         } else if (expr_type == TypeManager.uint32_type){
1630                                 //
1631                                 // From uint to sbyte, byte, short, ushort, int, char
1632                                 //
1633                                 if (real_target_type == TypeManager.sbyte_type)
1634                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_I1);
1635                                 if (real_target_type == TypeManager.byte_type)
1636                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_U1);
1637                                 if (real_target_type == TypeManager.short_type)
1638                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_I2);
1639                                 if (real_target_type == TypeManager.ushort_type)
1640                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_U2);
1641                                 if (real_target_type == TypeManager.int32_type)
1642                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_I4);
1643                                 if (real_target_type == TypeManager.char_type)
1644                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_CH);
1645                         } else if (expr_type == TypeManager.int64_type){
1646                                 //
1647                                 // From long to sbyte, byte, short, ushort, int, uint, ulong, char
1648                                 //
1649                                 if (real_target_type == TypeManager.sbyte_type)
1650                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I1);
1651                                 if (real_target_type == TypeManager.byte_type)
1652                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U1);
1653                                 if (real_target_type == TypeManager.short_type)
1654                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I2);
1655                                 if (real_target_type == TypeManager.ushort_type)
1656                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U2);
1657                                 if (real_target_type == TypeManager.int32_type)
1658                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I4);
1659                                 if (real_target_type == TypeManager.uint32_type)
1660                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U4);
1661                                 if (real_target_type == TypeManager.uint64_type)
1662                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U8);
1663                                 if (real_target_type == TypeManager.char_type)
1664                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_CH);
1665                         } else if (expr_type == TypeManager.uint64_type){
1666                                 //
1667                                 // From ulong to sbyte, byte, short, ushort, int, uint, long, char
1668                                 //
1669                                 if (real_target_type == TypeManager.sbyte_type)
1670                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I1);
1671                                 if (real_target_type == TypeManager.byte_type)
1672                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U1);
1673                                 if (real_target_type == TypeManager.short_type)
1674                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I2);
1675                                 if (real_target_type == TypeManager.ushort_type)
1676                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U2);
1677                                 if (real_target_type == TypeManager.int32_type)
1678                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I4);
1679                                 if (real_target_type == TypeManager.uint32_type)
1680                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U4);
1681                                 if (real_target_type == TypeManager.int64_type)
1682                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I8);
1683                                 if (real_target_type == TypeManager.char_type)
1684                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_CH);
1685                         } else if (expr_type == TypeManager.char_type){
1686                                 //
1687                                 // From char to sbyte, byte, short
1688                                 //
1689                                 if (real_target_type == TypeManager.sbyte_type)
1690                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.CH_I1);
1691                                 if (real_target_type == TypeManager.byte_type)
1692                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.CH_U1);
1693                                 if (real_target_type == TypeManager.short_type)
1694                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.CH_I2);
1695                         } else if (expr_type == TypeManager.float_type){
1696                                 //
1697                                 // From float to sbyte, byte, short,
1698                                 // ushort, int, uint, long, ulong, char
1699                                 // or decimal
1700                                 //
1701                                 if (real_target_type == TypeManager.sbyte_type)
1702                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_I1);
1703                                 if (real_target_type == TypeManager.byte_type)
1704                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_U1);
1705                                 if (real_target_type == TypeManager.short_type)
1706                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_I2);
1707                                 if (real_target_type == TypeManager.ushort_type)
1708                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_U2);
1709                                 if (real_target_type == TypeManager.int32_type)
1710                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_I4);
1711                                 if (real_target_type == TypeManager.uint32_type)
1712                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_U4);
1713                                 if (real_target_type == TypeManager.int64_type)
1714                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_I8);
1715                                 if (real_target_type == TypeManager.uint64_type)
1716                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_U8);
1717                                 if (real_target_type == TypeManager.char_type)
1718                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R4_CH);
1719                                 if (real_target_type == TypeManager.decimal_type)
1720                                         return InternalTypeConstructor (ec, expr, target_type);
1721                         } else if (expr_type == TypeManager.double_type){
1722                                 //
1723                                 // From double to byte, byte, short,
1724                                 // ushort, int, uint, long, ulong,
1725                                 // char, float or decimal
1726                                 //
1727                                 if (real_target_type == TypeManager.sbyte_type)
1728                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_I1);
1729                                 if (real_target_type == TypeManager.byte_type)
1730                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_U1);
1731                                 if (real_target_type == TypeManager.short_type)
1732                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_I2);
1733                                 if (real_target_type == TypeManager.ushort_type)
1734                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_U2);
1735                                 if (real_target_type == TypeManager.int32_type)
1736                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_I4);
1737                                 if (real_target_type == TypeManager.uint32_type)
1738                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_U4);
1739                                 if (real_target_type == TypeManager.int64_type)
1740                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_I8);
1741                                 if (real_target_type == TypeManager.uint64_type)
1742                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_U8);
1743                                 if (real_target_type == TypeManager.char_type)
1744                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_CH);
1745                                 if (real_target_type == TypeManager.float_type)
1746                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_R4);
1747                                 if (real_target_type == TypeManager.decimal_type)
1748                                         return InternalTypeConstructor (ec, expr, target_type);
1749                         }
1750
1751                         // decimal is taken care of by the op_Explicit methods.
1752
1753                         return null;
1754                 }
1755
1756                 /// <summary>
1757                 ///  Returns whether an explicit reference conversion can be performed
1758                 ///  from source_type to target_type
1759                 /// </summary>
1760                 static bool ExplicitReferenceConversionExists (Type source_type, Type target_type)
1761                 {
1762                         bool target_is_value_type = target_type.IsValueType;
1763
1764                         if (source_type == target_type)
1765                                 return true;
1766
1767                         //
1768                         // From object to any reference type
1769                         //
1770                         if (source_type == TypeManager.object_type && !target_is_value_type)
1771                                 return true;
1772
1773                         //
1774                         // From any class S to any class-type T, provided S is a base class of T
1775                         //
1776                         if (target_type.IsSubclassOf (source_type))
1777                                 return true;
1778
1779                         //
1780                         // From any interface type S to any interface T provided S is not derived from T
1781                         //
1782                         if (source_type.IsInterface && target_type.IsInterface){
1783                                 if (!target_type.IsSubclassOf (source_type))
1784                                         return true;
1785                         }
1786
1787                         //
1788                         // From any class type S to any interface T, provided S is not sealed
1789                         // and provided S does not implement T.
1790                         //
1791                         if (target_type.IsInterface && !source_type.IsSealed &&
1792                             !TypeManager.ImplementsInterface (source_type, target_type))
1793                                 return true;
1794
1795                         //
1796                         // From any interface-type S to to any class type T, provided T is not
1797                         // sealed, or provided T implements S.
1798                         //
1799                         if (source_type.IsInterface &&
1800                             (!target_type.IsSealed || TypeManager.ImplementsInterface (target_type, source_type)))
1801                                 return true;
1802
1803
1804                         // From an array type S with an element type Se to an array type T with an
1805                         // element type Te provided all the following are true:
1806                         //     * S and T differe only in element type, in other words, S and T
1807                         //       have the same number of dimensions.
1808                         //     * Both Se and Te are reference types
1809                         //     * An explicit referenc conversions exist from Se to Te
1810                         //
1811                         if (source_type.IsArray && target_type.IsArray) {
1812                                 if (source_type.GetArrayRank () == target_type.GetArrayRank ()) {
1813
1814                                         Type source_element_type = source_type.GetElementType ();
1815                                         Type target_element_type = target_type.GetElementType ();
1816
1817                                         if (!source_element_type.IsValueType && !target_element_type.IsValueType)
1818                                                 if (ExplicitReferenceConversionExists (source_element_type,
1819                                                                                        target_element_type))
1820                                                         return true;
1821                                 }
1822                         }
1823
1824
1825                         // From System.Array to any array-type
1826                         if (source_type == TypeManager.array_type &&
1827                             target_type.IsSubclassOf (TypeManager.array_type)){
1828                                 return true;
1829                         }
1830
1831                         //
1832                         // From System delegate to any delegate-type
1833                         //
1834                         if (source_type == TypeManager.delegate_type &&
1835                             target_type.IsSubclassOf (TypeManager.delegate_type))
1836                                 return true;
1837
1838                         //
1839                         // From ICloneable to Array or Delegate types
1840                         //
1841                         if (source_type == TypeManager.icloneable_type &&
1842                             (target_type == TypeManager.array_type ||
1843                              target_type == TypeManager.delegate_type))
1844                                 return true;
1845
1846                         return false;
1847                 }
1848
1849                 /// <summary>
1850                 ///   Implements Explicit Reference conversions
1851                 /// </summary>
1852                 static Expression ConvertReferenceExplicit (Expression source, Type target_type)
1853                 {
1854                         Type source_type = source.Type;
1855                         bool target_is_value_type = target_type.IsValueType;
1856
1857                         //
1858                         // From object to any reference type
1859                         //
1860                         if (source_type == TypeManager.object_type && !target_is_value_type)
1861                                 return new ClassCast (source, target_type);
1862
1863
1864                         //
1865                         // From any class S to any class-type T, provided S is a base class of T
1866                         //
1867                         if (target_type.IsSubclassOf (source_type))
1868                                 return new ClassCast (source, target_type);
1869
1870                         //
1871                         // From any interface type S to any interface T provided S is not derived from T
1872                         //
1873                         if (source_type.IsInterface && target_type.IsInterface){
1874                                 if (TypeManager.ImplementsInterface (source_type, target_type))
1875                                         return null;
1876                                 else
1877                                         return new ClassCast (source, target_type);
1878                         }
1879
1880                         //
1881                         // From any class type S to any interface T, provides S is not sealed
1882                         // and provided S does not implement T.
1883                         //
1884                         if (target_type.IsInterface && !source_type.IsSealed) {
1885                                 if (TypeManager.ImplementsInterface (source_type, target_type))
1886                                         return null;
1887                                 else
1888                                         return new ClassCast (source, target_type);
1889
1890                         }
1891
1892                         //
1893                         // From any interface-type S to to any class type T, provided T is not
1894                         // sealed, or provided T implements S.
1895                         //
1896                         if (source_type.IsInterface) {
1897                                 if (!target_type.IsSealed || TypeManager.ImplementsInterface (target_type, source_type))
1898                                         return new ClassCast (source, target_type);
1899                                 else
1900                                         return null;
1901                         }
1902
1903                         // From an array type S with an element type Se to an array type T with an
1904                         // element type Te provided all the following are true:
1905                         //     * S and T differe only in element type, in other words, S and T
1906                         //       have the same number of dimensions.
1907                         //     * Both Se and Te are reference types
1908                         //     * An explicit referenc conversions exist from Se to Te
1909                         //
1910                         if (source_type.IsArray && target_type.IsArray) {
1911                                 if (source_type.GetArrayRank () == target_type.GetArrayRank ()) {
1912
1913                                         Type source_element_type = source_type.GetElementType ();
1914                                         Type target_element_type = target_type.GetElementType ();
1915
1916                                         if (!source_element_type.IsValueType && !target_element_type.IsValueType)
1917                                                 if (ExplicitReferenceConversionExists (source_element_type,
1918                                                                                        target_element_type))
1919                                                         return new ClassCast (source, target_type);
1920                                 }
1921                         }
1922
1923
1924                         // From System.Array to any array-type
1925                         if (source_type == TypeManager.array_type &&
1926                             target_type.IsSubclassOf (TypeManager.array_type)){
1927                                 return new ClassCast (source, target_type);
1928                         }
1929
1930                         //
1931                         // From System delegate to any delegate-type
1932                         //
1933                         if (source_type == TypeManager.delegate_type &&
1934                             target_type.IsSubclassOf (TypeManager.delegate_type))
1935                                 return new ClassCast (source, target_type);
1936
1937                         //
1938                         // From ICloneable to Array or Delegate types
1939                         //
1940                         if (source_type == TypeManager.icloneable_type &&
1941                             (target_type == TypeManager.array_type ||
1942                              target_type == TypeManager.delegate_type))
1943                                 return new ClassCast (source, target_type);
1944
1945                         return null;
1946                 }
1947
1948                 /// <summary>
1949                 ///   Performs an explicit conversion of the expression `expr' whose
1950                 ///   type is expr.Type to `target_type'.
1951                 /// </summary>
1952                 static public Expression ConvertExplicit (EmitContext ec, Expression expr,
1953                                                           Type target_type, Location loc)
1954                 {
1955                         Type expr_type = expr.Type;
1956                         Expression ne = ConvertImplicitStandard (ec, expr, target_type, loc);
1957
1958                         if (ne != null)
1959                                 return ne;
1960
1961                         ne = ConvertNumericExplicit (ec, expr, target_type);
1962                         if (ne != null)
1963                                 return ne;
1964
1965                         //
1966                         // Unboxing conversion.
1967                         //
1968                         if (expr_type == TypeManager.object_type && target_type.IsValueType)
1969                                 return new UnboxCast (expr, target_type);
1970
1971                         //
1972                         // Enum types
1973                         //
1974                         if (expr_type.IsSubclassOf (TypeManager.enum_type)) {
1975                                 Expression e;
1976
1977                                 //
1978                                 // FIXME: Is there any reason we should have EnumConstant
1979                                 // dealt with here instead of just using always the
1980                                 // UnderlyingSystemType to wrap the type?
1981                                 //
1982                                 if (expr is EnumConstant)
1983                                         e = ((EnumConstant) expr).Child;
1984                                 else {
1985                                         e = new EmptyCast (expr, TypeManager.EnumToUnderlying (expr_type));
1986                                 }
1987
1988                                 Expression t = ConvertImplicit (ec, e, target_type, loc);
1989                                 if (t != null)
1990                                         return t;
1991
1992                                 return ConvertNumericExplicit (ec, e, target_type);
1993                         }
1994
1995                         ne = ConvertReferenceExplicit (expr, target_type);
1996                         if (ne != null)
1997                                 return ne;
1998
1999                         if (ec.InUnsafe){
2000                                 if (target_type.IsPointer){
2001                                         if (expr_type.IsPointer)
2002                                                 return new EmptyCast (expr, target_type);
2003
2004                                         if (expr_type == TypeManager.sbyte_type ||
2005                                             expr_type == TypeManager.byte_type ||
2006                                             expr_type == TypeManager.short_type ||
2007                                             expr_type == TypeManager.ushort_type ||
2008                                             expr_type == TypeManager.int32_type ||
2009                                             expr_type == TypeManager.uint32_type ||
2010                                             expr_type == TypeManager.uint64_type ||
2011                                             expr_type == TypeManager.int64_type)
2012                                                 return new OpcodeCast (expr, target_type, OpCodes.Conv_U);
2013                                 }
2014                                 if (expr_type.IsPointer){
2015                                         if (target_type == TypeManager.sbyte_type ||
2016                                             target_type == TypeManager.byte_type ||
2017                                             target_type == TypeManager.short_type ||
2018                                             target_type == TypeManager.ushort_type ||
2019                                             target_type == TypeManager.int32_type ||
2020                                             target_type == TypeManager.uint32_type ||
2021                                             target_type == TypeManager.uint64_type ||
2022                                             target_type == TypeManager.int64_type){
2023                                                 Expression e = new EmptyCast (expr, TypeManager.uint32_type);
2024                                                 Expression ci, ce;
2025
2026                                                 ci = ConvertImplicitStandard (ec, e, target_type, loc);
2027
2028                                                 if (ci != null)
2029                                                         return ci;
2030
2031                                                 ce = ConvertNumericExplicit (ec, e, target_type);
2032                                                 if (ce != null)
2033                                                         return ce;
2034                                                 //
2035                                                 // We should always be able to go from an uint32
2036                                                 // implicitly or explicitly to the other integral
2037                                                 // types
2038                                                 //
2039                                                 throw new Exception ("Internal compiler error");
2040                                         }
2041                                 }
2042                         }
2043
2044                         ne = ExplicitUserConversion (ec, expr, target_type, loc);
2045                         if (ne != null)
2046                                 return ne;
2047
2048                         Error_CannotConvertType (loc, expr_type, target_type);
2049                         return null;
2050                 }
2051
2052                 /// <summary>
2053                 ///   Same as ConvertExplicit, only it doesn't include user defined conversions
2054                 /// </summary>
2055                 static public Expression ConvertExplicitStandard (EmitContext ec, Expression expr,
2056                                                                   Type target_type, Location l)
2057                 {
2058                         Expression ne = ConvertImplicitStandard (ec, expr, target_type, l);
2059
2060                         if (ne != null)
2061                                 return ne;
2062
2063                         ne = ConvertNumericExplicit (ec, expr, target_type);
2064                         if (ne != null)
2065                                 return ne;
2066
2067                         ne = ConvertReferenceExplicit (expr, target_type);
2068                         if (ne != null)
2069                                 return ne;
2070
2071                         Error_CannotConvertType (l, expr.Type, target_type);
2072                         return null;
2073                 }
2074
2075                 static string ExprClassName (ExprClass c)
2076                 {
2077                         switch (c){
2078                         case ExprClass.Invalid:
2079                                 return "Invalid";
2080                         case ExprClass.Value:
2081                                 return "value";
2082                         case ExprClass.Variable:
2083                                 return "variable";
2084                         case ExprClass.Namespace:
2085                                 return "namespace";
2086                         case ExprClass.Type:
2087                                 return "type";
2088                         case ExprClass.MethodGroup:
2089                                 return "method group";
2090                         case ExprClass.PropertyAccess:
2091                                 return "property access";
2092                         case ExprClass.EventAccess:
2093                                 return "event access";
2094                         case ExprClass.IndexerAccess:
2095                                 return "indexer access";
2096                         case ExprClass.Nothing:
2097                                 return "null";
2098                         }
2099                         throw new Exception ("Should not happen");
2100                 }
2101
2102                 /// <summary>
2103                 ///   Reports that we were expecting `expr' to be of class `expected'
2104                 /// </summary>
2105                 protected void report118 (Location loc, Expression expr, string expected)
2106                 {
2107                         string kind = "Unknown";
2108
2109                         if (expr != null)
2110                                 kind = ExprClassName (expr.eclass);
2111
2112                         Error (118, loc, "Expression denotes a `" + kind +
2113                                "' where a `" + expected + "' was expected");
2114                 }
2115
2116                 static void Error_ConstantValueCannotBeConverted (Location l, string val, Type t)
2117                 {
2118                         Report.Error (31, l, "Constant value `" + val + "' cannot be converted to " +
2119                                       TypeManager.CSharpName (t));
2120                 }
2121
2122                 public static void UnsafeError (Location loc)
2123                 {
2124                         Report.Error (214, loc, "Pointers may only be used in an unsafe context");
2125                 }
2126
2127                 /// <summary>
2128                 ///   Converts the IntConstant, UIntConstant, LongConstant or
2129                 ///   ULongConstant into the integral target_type.   Notice
2130                 ///   that we do not return an `Expression' we do return
2131                 ///   a boxed integral type.
2132                 ///
2133                 ///   FIXME: Since I added the new constants, we need to
2134                 ///   also support conversions from CharConstant, ByteConstant,
2135                 ///   SByteConstant, UShortConstant, ShortConstant
2136                 ///
2137                 ///   This is used by the switch statement, so the domain
2138                 ///   of work is restricted to the literals above, and the
2139                 ///   targets are int32, uint32, char, byte, sbyte, ushort,
2140                 ///   short, uint64 and int64
2141                 /// </summary>
2142                 public static object ConvertIntLiteral (Constant c, Type target_type, Location loc)
2143                 {
2144                         string s = "";
2145
2146                         if (c.Type == target_type)
2147                                 return ((Constant) c).GetValue ();
2148
2149                         //
2150                         // Make into one of the literals we handle, we dont really care
2151                         // about this value as we will just return a few limited types
2152                         //
2153                         if (c is EnumConstant)
2154                                 c = ((EnumConstant)c).WidenToCompilerConstant ();
2155
2156                         if (c is IntConstant){
2157                                 int v = ((IntConstant) c).Value;
2158
2159                                 if (target_type == TypeManager.uint32_type){
2160                                         if (v >= 0)
2161                                                 return (uint) v;
2162                                 } else if (target_type == TypeManager.char_type){
2163                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2164                                                 return (char) v;
2165                                 } else if (target_type == TypeManager.byte_type){
2166                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2167                                                 return (byte) v;
2168                                 } else if (target_type == TypeManager.sbyte_type){
2169                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
2170                                                 return (sbyte) v;
2171                                 } else if (target_type == TypeManager.short_type){
2172                                         if (v >= Int16.MinValue && v <= UInt16.MaxValue)
2173                                                 return (short) v;
2174                                 } else if (target_type == TypeManager.ushort_type){
2175                                         if (v >= UInt16.MinValue && v <= UInt16.MaxValue)
2176                                                 return (ushort) v;
2177                                 } else if (target_type == TypeManager.int64_type)
2178                                         return (long) v;
2179                                 else if (target_type == TypeManager.uint64_type){
2180                                         if (v > 0)
2181                                                 return (ulong) v;
2182                                 }
2183
2184                                 s = v.ToString ();
2185                         } else if (c is UIntConstant){
2186                                 uint v = ((UIntConstant) c).Value;
2187
2188                                 if (target_type == TypeManager.int32_type){
2189                                         if (v <= Int32.MaxValue)
2190                                                 return (int) v;
2191                                 } else if (target_type == TypeManager.char_type){
2192                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2193                                                 return (char) v;
2194                                 } else if (target_type == TypeManager.byte_type){
2195                                         if (v <= Byte.MaxValue)
2196                                                 return (byte) v;
2197                                 } else if (target_type == TypeManager.sbyte_type){
2198                                         if (v <= SByte.MaxValue)
2199                                                 return (sbyte) v;
2200                                 } else if (target_type == TypeManager.short_type){
2201                                         if (v <= UInt16.MaxValue)
2202                                                 return (short) v;
2203                                 } else if (target_type == TypeManager.ushort_type){
2204                                         if (v <= UInt16.MaxValue)
2205                                                 return (ushort) v;
2206                                 } else if (target_type == TypeManager.int64_type)
2207                                         return (long) v;
2208                                 else if (target_type == TypeManager.uint64_type)
2209                                         return (ulong) v;
2210                                 s = v.ToString ();
2211                         } else if (c is LongConstant){
2212                                 long v = ((LongConstant) c).Value;
2213
2214                                 if (target_type == TypeManager.int32_type){
2215                                         if (v >= UInt32.MinValue && v <= UInt32.MaxValue)
2216                                                 return (int) v;
2217                                 } else if (target_type == TypeManager.uint32_type){
2218                                         if (v >= 0 && v <= UInt32.MaxValue)
2219                                                 return (uint) v;
2220                                 } else if (target_type == TypeManager.char_type){
2221                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2222                                                 return (char) v;
2223                                 } else if (target_type == TypeManager.byte_type){
2224                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2225                                                 return (byte) v;
2226                                 } else if (target_type == TypeManager.sbyte_type){
2227                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
2228                                                 return (sbyte) v;
2229                                 } else if (target_type == TypeManager.short_type){
2230                                         if (v >= Int16.MinValue && v <= UInt16.MaxValue)
2231                                                 return (short) v;
2232                                 } else if (target_type == TypeManager.ushort_type){
2233                                         if (v >= UInt16.MinValue && v <= UInt16.MaxValue)
2234                                                 return (ushort) v;
2235                                 } else if (target_type == TypeManager.uint64_type){
2236                                         if (v > 0)
2237                                                 return (ulong) v;
2238                                 }
2239                                 s = v.ToString ();
2240                         } else if (c is ULongConstant){
2241                                 ulong v = ((ULongConstant) c).Value;
2242
2243                                 if (target_type == TypeManager.int32_type){
2244                                         if (v <= Int32.MaxValue)
2245                                                 return (int) v;
2246                                 } else if (target_type == TypeManager.uint32_type){
2247                                         if (v <= UInt32.MaxValue)
2248                                                 return (uint) v;
2249                                 } else if (target_type == TypeManager.char_type){
2250                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2251                                                 return (char) v;
2252                                 } else if (target_type == TypeManager.byte_type){
2253                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2254                                                 return (byte) v;
2255                                 } else if (target_type == TypeManager.sbyte_type){
2256                                         if (v <= (int) SByte.MaxValue)
2257                                                 return (sbyte) v;
2258                                 } else if (target_type == TypeManager.short_type){
2259                                         if (v <= UInt16.MaxValue)
2260                                                 return (short) v;
2261                                 } else if (target_type == TypeManager.ushort_type){
2262                                         if (v <= UInt16.MaxValue)
2263                                                 return (ushort) v;
2264                                 } else if (target_type == TypeManager.int64_type){
2265                                         if (v <= Int64.MaxValue)
2266                                                 return (long) v;
2267                                 }
2268                                 s = v.ToString ();
2269                         } else if (c is ByteConstant){
2270                                 byte v = ((ByteConstant) c).Value;
2271
2272                                 if (target_type == TypeManager.int32_type)
2273                                         return (int) v;
2274                                 else if (target_type == TypeManager.uint32_type)
2275                                         return (uint) v;
2276                                 else if (target_type == TypeManager.char_type)
2277                                         return (char) v;
2278                                 else if (target_type == TypeManager.sbyte_type){
2279                                         if (v <= SByte.MaxValue)
2280                                                 return (sbyte) v;
2281                                 } else if (target_type == TypeManager.short_type)
2282                                         return (short) v;
2283                                 else if (target_type == TypeManager.ushort_type)
2284                                         return (ushort) v;
2285                                 else if (target_type == TypeManager.int64_type)
2286                                         return (long) v;
2287                                 else if (target_type == TypeManager.uint64_type)
2288                                         return (ulong) v;
2289                                 s = v.ToString ();
2290                         } else if (c is SByteConstant){
2291                                 sbyte v = ((SByteConstant) c).Value;
2292
2293                                 if (target_type == TypeManager.int32_type)
2294                                         return (int) v;
2295                                 else if (target_type == TypeManager.uint32_type){
2296                                         if (v >= 0)
2297                                                 return (uint) v;
2298                                 } else if (target_type == TypeManager.char_type){
2299                                         if (v >= 0)
2300                                                 return (char) v;
2301                                 } else if (target_type == TypeManager.byte_type){
2302                                         if (v >= 0)
2303                                                 return (byte) v;
2304                                 } else if (target_type == TypeManager.short_type)
2305                                         return (short) v;
2306                                 else if (target_type == TypeManager.ushort_type){
2307                                         if (v >= 0)
2308                                                 return (ushort) v;
2309                                 } else if (target_type == TypeManager.int64_type)
2310                                         return (long) v;
2311                                 else if (target_type == TypeManager.uint64_type){
2312                                         if (v >= 0)
2313                                                 return (ulong) v;
2314                                 }
2315                                 s = v.ToString ();
2316                         } else if (c is ShortConstant){
2317                                 short v = ((ShortConstant) c).Value;
2318
2319                                 if (target_type == TypeManager.int32_type){
2320                                         return (int) v;
2321                                 } else if (target_type == TypeManager.uint32_type){
2322                                         if (v >= 0)
2323                                                 return (uint) v;
2324                                 } else if (target_type == TypeManager.char_type){
2325                                         if (v >= 0)
2326                                                 return (char) v;
2327                                 } else if (target_type == TypeManager.byte_type){
2328                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2329                                                 return (byte) v;
2330                                 } else if (target_type == TypeManager.sbyte_type){
2331                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
2332                                                 return (sbyte) v;
2333                                 } else if (target_type == TypeManager.ushort_type){
2334                                         if (v >= 0)
2335                                                 return (ushort) v;
2336                                 } else if (target_type == TypeManager.int64_type)
2337                                         return (long) v;
2338                                 else if (target_type == TypeManager.uint64_type)
2339                                         return (ulong) v;
2340
2341                                 s = v.ToString ();
2342                         } else if (c is UShortConstant){
2343                                 ushort v = ((UShortConstant) c).Value;
2344
2345                                 if (target_type == TypeManager.int32_type)
2346                                         return (int) v;
2347                                 else if (target_type == TypeManager.uint32_type)
2348                                         return (uint) v;
2349                                 else if (target_type == TypeManager.char_type){
2350                                         if (v >= Char.MinValue && v <= Char.MaxValue)
2351                                                 return (char) v;
2352                                 } else if (target_type == TypeManager.byte_type){
2353                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2354                                                 return (byte) v;
2355                                 } else if (target_type == TypeManager.sbyte_type){
2356                                         if (v <= SByte.MaxValue)
2357                                                 return (byte) v;
2358                                 } else if (target_type == TypeManager.short_type){
2359                                         if (v <= Int16.MaxValue)
2360                                                 return (short) v;
2361                                 } else if (target_type == TypeManager.int64_type)
2362                                         return (long) v;
2363                                 else if (target_type == TypeManager.uint64_type)
2364                                         return (ulong) v;
2365
2366                                 s = v.ToString ();
2367                         } else if (c is CharConstant){
2368                                 char v = ((CharConstant) c).Value;
2369
2370                                 if (target_type == TypeManager.int32_type)
2371                                         return (int) v;
2372                                 else if (target_type == TypeManager.uint32_type)
2373                                         return (uint) v;
2374                                 else if (target_type == TypeManager.byte_type){
2375                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
2376                                                 return (byte) v;
2377                                 } else if (target_type == TypeManager.sbyte_type){
2378                                         if (v <= SByte.MaxValue)
2379                                                 return (sbyte) v;
2380                                 } else if (target_type == TypeManager.short_type){
2381                                         if (v <= Int16.MaxValue)
2382                                                 return (short) v;
2383                                 } else if (target_type == TypeManager.ushort_type)
2384                                         return (short) v;
2385                                 else if (target_type == TypeManager.int64_type)
2386                                         return (long) v;
2387                                 else if (target_type == TypeManager.uint64_type)
2388                                         return (ulong) v;
2389
2390                                 s = v.ToString ();
2391                         }
2392                         Error_ConstantValueCannotBeConverted (loc, s, target_type);
2393                         return null;
2394                 }
2395
2396                 //
2397                 // Load the object from the pointer.
2398                 //
2399                 public static void LoadFromPtr (ILGenerator ig, Type t)
2400                 {
2401                         if (t == TypeManager.int32_type)
2402                                 ig.Emit (OpCodes.Ldind_I4);
2403                         else if (t == TypeManager.uint32_type)
2404                                 ig.Emit (OpCodes.Ldind_U4);
2405                         else if (t == TypeManager.short_type)
2406                                 ig.Emit (OpCodes.Ldind_I2);
2407                         else if (t == TypeManager.ushort_type)
2408                                 ig.Emit (OpCodes.Ldind_U2);
2409                         else if (t == TypeManager.char_type)
2410                                 ig.Emit (OpCodes.Ldind_U2);
2411                         else if (t == TypeManager.byte_type)
2412                                 ig.Emit (OpCodes.Ldind_U1);
2413                         else if (t == TypeManager.sbyte_type)
2414                                 ig.Emit (OpCodes.Ldind_I1);
2415                         else if (t == TypeManager.uint64_type)
2416                                 ig.Emit (OpCodes.Ldind_I8);
2417                         else if (t == TypeManager.int64_type)
2418                                 ig.Emit (OpCodes.Ldind_I8);
2419                         else if (t == TypeManager.float_type)
2420                                 ig.Emit (OpCodes.Ldind_R4);
2421                         else if (t == TypeManager.double_type)
2422                                 ig.Emit (OpCodes.Ldind_R8);
2423                         else if (t == TypeManager.bool_type)
2424                                 ig.Emit (OpCodes.Ldind_I1);
2425                         else if (t == TypeManager.intptr_type)
2426                                 ig.Emit (OpCodes.Ldind_I);
2427                         else if (TypeManager.IsEnumType (t))
2428                                 LoadFromPtr (ig, TypeManager.EnumToUnderlying (t));
2429                         else if (t.IsValueType)
2430                                 ig.Emit (OpCodes.Ldobj, t);
2431                         else
2432                                 ig.Emit (OpCodes.Ldind_Ref);
2433                 }
2434
2435                 //
2436                 // The stack contains the pointer and the value of type `type'
2437                 //
2438                 public static void StoreFromPtr (ILGenerator ig, Type type)
2439                 {
2440                         if (type == TypeManager.int32_type || type == TypeManager.uint32_type)
2441                                 ig.Emit (OpCodes.Stind_I4);
2442                         else if (type == TypeManager.int64_type || type == TypeManager.uint64_type)
2443                                 ig.Emit (OpCodes.Stind_I8);
2444                         else if (type == TypeManager.char_type || type == TypeManager.short_type ||
2445                                  type == TypeManager.ushort_type)
2446                                 ig.Emit (OpCodes.Stind_I2);
2447                         else if (type == TypeManager.float_type)
2448                                 ig.Emit (OpCodes.Stind_R4);
2449                         else if (type == TypeManager.double_type)
2450                                 ig.Emit (OpCodes.Stind_R8);
2451                         else if (type == TypeManager.byte_type || type == TypeManager.sbyte_type ||
2452                                  type == TypeManager.bool_type)
2453                                 ig.Emit (OpCodes.Stind_I1);
2454                         else if (type == TypeManager.intptr_type)
2455                                 ig.Emit (OpCodes.Stind_I);
2456                         else if (type.IsValueType)
2457                                 ig.Emit (OpCodes.Stobj);
2458                         else
2459                                 ig.Emit (OpCodes.Stind_Ref);
2460                 }
2461
2462                 //
2463                 // Returns the size of type `t' if known, otherwise, 0
2464                 //
2465                 public static int GetTypeSize (Type t)
2466                 {
2467                         if (t == TypeManager.int32_type ||
2468                             t == TypeManager.uint32_type ||
2469                             t == TypeManager.float_type)
2470                                 return 4;
2471                         else if (t == TypeManager.int64_type ||
2472                                  t == TypeManager.uint64_type ||
2473                                  t == TypeManager.double_type)
2474                                 return 8;
2475                         else if (t == TypeManager.byte_type ||
2476                                  t == TypeManager.sbyte_type ||
2477                                  t == TypeManager.bool_type)
2478                                 return 1;
2479                         else if (t == TypeManager.short_type ||
2480                                  t == TypeManager.char_type ||
2481                                  t == TypeManager.ushort_type)
2482                                 return 2;
2483                         else
2484                                 return 0;
2485                 }
2486         }
2487
2488         /// <summary>
2489         ///   This is just a base class for expressions that can
2490         ///   appear on statements (invocations, object creation,
2491         ///   assignments, post/pre increment and decrement).  The idea
2492         ///   being that they would support an extra Emition interface that
2493         ///   does not leave a result on the stack.
2494         /// </summary>
2495         public abstract class ExpressionStatement : Expression {
2496
2497                 /// <summary>
2498                 ///   Requests the expression to be emitted in a `statement'
2499                 ///   context.  This means that no new value is left on the
2500                 ///   stack after invoking this method (constrasted with
2501                 ///   Emit that will always leave a value on the stack).
2502                 /// </summary>
2503                 public abstract void EmitStatement (EmitContext ec);
2504         }
2505
2506         /// <summary>
2507         ///   This kind of cast is used to encapsulate the child
2508         ///   whose type is child.Type into an expression that is
2509         ///   reported to return "return_type".  This is used to encapsulate
2510         ///   expressions which have compatible types, but need to be dealt
2511         ///   at higher levels with.
2512         ///
2513         ///   For example, a "byte" expression could be encapsulated in one
2514         ///   of these as an "unsigned int".  The type for the expression
2515         ///   would be "unsigned int".
2516         ///
2517         /// </summary>
2518         public class EmptyCast : Expression {
2519                 protected Expression child;
2520
2521                 public EmptyCast (Expression child, Type return_type)
2522                 {
2523                         eclass = child.eclass;
2524                         type = return_type;
2525                         this.child = child;
2526                 }
2527
2528                 public override Expression DoResolve (EmitContext ec)
2529                 {
2530                         // This should never be invoked, we are born in fully
2531                         // initialized state.
2532
2533                         return this;
2534                 }
2535
2536                 public override void Emit (EmitContext ec)
2537                 {
2538                         child.Emit (ec);
2539                 }
2540         }
2541
2542         /// <summary>
2543         ///  This class is used to wrap literals which belong inside Enums
2544         /// </summary>
2545         public class EnumConstant : Constant {
2546                 public Constant Child;
2547
2548                 public EnumConstant (Constant child, Type enum_type)
2549                 {
2550                         eclass = child.eclass;
2551                         this.Child = child;
2552                         type = enum_type;
2553                 }
2554
2555                 public override Expression DoResolve (EmitContext ec)
2556                 {
2557                         // This should never be invoked, we are born in fully
2558                         // initialized state.
2559
2560                         return this;
2561                 }
2562
2563                 public override void Emit (EmitContext ec)
2564                 {
2565                         Child.Emit (ec);
2566                 }
2567
2568                 public override object GetValue ()
2569                 {
2570                         return Child.GetValue ();
2571                 }
2572
2573                 //
2574                 // Converts from one of the valid underlying types for an enumeration
2575                 // (int32, uint32, int64, uint64, short, ushort, byte, sbyte) to
2576                 // one of the internal compiler literals: Int/UInt/Long/ULong Literals.
2577                 //
2578                 public Constant WidenToCompilerConstant ()
2579                 {
2580                         Type t = TypeManager.EnumToUnderlying (Child.Type);
2581                         object v = ((Constant) Child).GetValue ();;
2582
2583                         if (t == TypeManager.int32_type)
2584                                 return new IntConstant ((int) v);
2585                         if (t == TypeManager.uint32_type)
2586                                 return new UIntConstant ((uint) v);
2587                         if (t == TypeManager.int64_type)
2588                                 return new LongConstant ((long) v);
2589                         if (t == TypeManager.uint64_type)
2590                                 return new ULongConstant ((ulong) v);
2591                         if (t == TypeManager.short_type)
2592                                 return new ShortConstant ((short) v);
2593                         if (t == TypeManager.ushort_type)
2594                                 return new UShortConstant ((ushort) v);
2595                         if (t == TypeManager.byte_type)
2596                                 return new ByteConstant ((byte) v);
2597                         if (t == TypeManager.sbyte_type)
2598                                 return new SByteConstant ((sbyte) v);
2599
2600                         throw new Exception ("Invalid enumeration underlying type: " + t);
2601                 }
2602
2603                 //
2604                 // Extracts the value in the enumeration on its native representation
2605                 //
2606                 public object GetPlainValue ()
2607                 {
2608                         Type t = TypeManager.EnumToUnderlying (Child.Type);
2609                         object v = ((Constant) Child).GetValue ();;
2610
2611                         if (t == TypeManager.int32_type)
2612                                 return (int) v;
2613                         if (t == TypeManager.uint32_type)
2614                                 return (uint) v;
2615                         if (t == TypeManager.int64_type)
2616                                 return (long) v;
2617                         if (t == TypeManager.uint64_type)
2618                                 return (ulong) v;
2619                         if (t == TypeManager.short_type)
2620                                 return (short) v;
2621                         if (t == TypeManager.ushort_type)
2622                                 return (ushort) v;
2623                         if (t == TypeManager.byte_type)
2624                                 return (byte) v;
2625                         if (t == TypeManager.sbyte_type)
2626                                 return (sbyte) v;
2627
2628                         return null;
2629                 }
2630
2631                 public override string AsString ()
2632                 {
2633                         return Child.AsString ();
2634                 }
2635
2636                 public override DoubleConstant ConvertToDouble ()
2637                 {
2638                         return Child.ConvertToDouble ();
2639                 }
2640
2641                 public override FloatConstant ConvertToFloat ()
2642                 {
2643                         return Child.ConvertToFloat ();
2644                 }
2645
2646                 public override ULongConstant ConvertToULong ()
2647                 {
2648                         return Child.ConvertToULong ();
2649                 }
2650
2651                 public override LongConstant ConvertToLong ()
2652                 {
2653                         return Child.ConvertToLong ();
2654                 }
2655
2656                 public override UIntConstant ConvertToUInt ()
2657                 {
2658                         return Child.ConvertToUInt ();
2659                 }
2660
2661                 public override IntConstant ConvertToInt ()
2662                 {
2663                         return Child.ConvertToInt ();
2664                 }
2665         }
2666
2667         /// <summary>
2668         ///   This kind of cast is used to encapsulate Value Types in objects.
2669         ///
2670         ///   The effect of it is to box the value type emitted by the previous
2671         ///   operation.
2672         /// </summary>
2673         public class BoxedCast : EmptyCast {
2674
2675                 public BoxedCast (Expression expr)
2676                         : base (expr, TypeManager.object_type)
2677                 {
2678                 }
2679
2680                 public override Expression DoResolve (EmitContext ec)
2681                 {
2682                         // This should never be invoked, we are born in fully
2683                         // initialized state.
2684
2685                         return this;
2686                 }
2687
2688                 public override void Emit (EmitContext ec)
2689                 {
2690                         base.Emit (ec);
2691
2692                         ec.ig.Emit (OpCodes.Box, child.Type);
2693                 }
2694         }
2695
2696         public class UnboxCast : EmptyCast {
2697                 public UnboxCast (Expression expr, Type return_type)
2698                         : base (expr, return_type)
2699                 {
2700                 }
2701
2702                 public override Expression DoResolve (EmitContext ec)
2703                 {
2704                         // This should never be invoked, we are born in fully
2705                         // initialized state.
2706
2707                         return this;
2708                 }
2709
2710                 public override void Emit (EmitContext ec)
2711                 {
2712                         Type t = type;
2713                         ILGenerator ig = ec.ig;
2714
2715                         base.Emit (ec);
2716                         ig.Emit (OpCodes.Unbox, t);
2717
2718                         LoadFromPtr (ig, t);
2719                 }
2720         }
2721
2722         /// <summary>
2723         ///   This is used to perform explicit numeric conversions.
2724         ///
2725         ///   Explicit numeric conversions might trigger exceptions in a checked
2726         ///   context, so they should generate the conv.ovf opcodes instead of
2727         ///   conv opcodes.
2728         /// </summary>
2729         public class ConvCast : EmptyCast {
2730                 public enum Mode : byte {
2731                         I1_U1, I1_U2, I1_U4, I1_U8, I1_CH,
2732                         U1_I1, U1_CH,
2733                         I2_I1, I2_U1, I2_U2, I2_U4, I2_U8, I2_CH,
2734                         U2_I1, U2_U1, U2_I2, U2_CH,
2735                         I4_I1, I4_U1, I4_I2, I4_U2, I4_U4, I4_U8, I4_CH,
2736                         U4_I1, U4_U1, U4_I2, U4_U2, U4_I4, U4_CH,
2737                         I8_I1, I8_U1, I8_I2, I8_U2, I8_I4, I8_U4, I8_U8, I8_CH,
2738                         U8_I1, U8_U1, U8_I2, U8_U2, U8_I4, U8_U4, U8_I8, U8_CH,
2739                         CH_I1, CH_U1, CH_I2,
2740                         R4_I1, R4_U1, R4_I2, R4_U2, R4_I4, R4_U4, R4_I8, R4_U8, R4_CH,
2741                         R8_I1, R8_U1, R8_I2, R8_U2, R8_I4, R8_U4, R8_I8, R8_U8, R8_CH, R8_R4
2742                 }
2743
2744                 Mode mode;
2745                 bool checked_state;
2746
2747                 public ConvCast (EmitContext ec, Expression child, Type return_type, Mode m)
2748                         : base (child, return_type)
2749                 {
2750                         mode = m;
2751                         checked_state = ec.CheckState;
2752                 }
2753
2754                 public override Expression DoResolve (EmitContext ec)
2755                 {
2756                         // This should never be invoked, we are born in fully
2757                         // initialized state.
2758
2759                         return this;
2760                 }
2761
2762                 public override void Emit (EmitContext ec)
2763                 {
2764                         ILGenerator ig = ec.ig;
2765
2766                         base.Emit (ec);
2767
2768                         if (checked_state){
2769                                 switch (mode){
2770                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
2771                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2772                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
2773                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
2774                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2775
2776                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
2777                                 case Mode.U1_CH: /* nothing */ break;
2778
2779                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
2780                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
2781                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2782                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
2783                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
2784                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2785
2786                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
2787                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
2788                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
2789                                 case Mode.U2_CH: /* nothing */ break;
2790
2791                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
2792                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
2793                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
2794                                 case Mode.I4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
2795                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2796                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
2797                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2798
2799                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
2800                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
2801                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
2802                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
2803                                 case Mode.U4_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
2804                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
2805
2806                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
2807                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
2808                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
2809                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2810                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
2811                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
2812                                 case Mode.I8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
2813                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2814
2815                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
2816                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
2817                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
2818                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
2819                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
2820                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_Ovf_U4_Un); break;
2821                                 case Mode.U8_I8: ig.Emit (OpCodes.Conv_Ovf_I8_Un); break;
2822                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
2823
2824                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
2825                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
2826                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
2827
2828                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
2829                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
2830                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
2831                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2832                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
2833                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
2834                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
2835                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
2836                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2837
2838                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
2839                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
2840                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
2841                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2842                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
2843                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
2844                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
2845                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
2846                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
2847                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
2848                                 }
2849                         } else {
2850                                 switch (mode){
2851                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_U1); break;
2852                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_U2); break;
2853                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_U4); break;
2854                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_I8); break;
2855                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_U2); break;
2856
2857                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_I1); break;
2858                                 case Mode.U1_CH: ig.Emit (OpCodes.Conv_U2); break;
2859
2860                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_I1); break;
2861                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_U1); break;
2862                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_U2); break;
2863                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_U4); break;
2864                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_I8); break;
2865                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_U2); break;
2866
2867                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_I1); break;
2868                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_U1); break;
2869                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_I2); break;
2870                                 case Mode.U2_CH: /* nothing */ break;
2871
2872                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_I1); break;
2873                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_U1); break;
2874                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_I2); break;
2875                                 case Mode.I4_U4: /* nothing */ break;
2876                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_U2); break;
2877                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_I8); break;
2878                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_U2); break;
2879
2880                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_I1); break;
2881                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_U1); break;
2882                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_I2); break;
2883                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_U2); break;
2884                                 case Mode.U4_I4: /* nothing */ break;
2885                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_U2); break;
2886
2887                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_I1); break;
2888                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_U1); break;
2889                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_I2); break;
2890                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_U2); break;
2891                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_I4); break;
2892                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_U4); break;
2893                                 case Mode.I8_U8: /* nothing */ break;
2894                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_U2); break;
2895
2896                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_I1); break;
2897                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_U1); break;
2898                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_I2); break;
2899                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_U2); break;
2900                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_I4); break;
2901                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_U4); break;
2902                                 case Mode.U8_I8: /* nothing */ break;
2903                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_U2); break;
2904
2905                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_I1); break;
2906                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_U1); break;
2907                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_I2); break;
2908
2909                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_I1); break;
2910                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_U1); break;
2911                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_I2); break;
2912                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_U2); break;
2913                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_I4); break;
2914                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_U4); break;
2915                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_I8); break;
2916                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_U8); break;
2917                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_U2); break;
2918
2919                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_I1); break;
2920                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_U1); break;
2921                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_I2); break;
2922                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_U2); break;
2923                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_I4); break;
2924                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_U4); break;
2925                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_I8); break;
2926                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_U8); break;
2927                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_U2); break;
2928                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
2929                                 }
2930                         }
2931                 }
2932         }
2933
2934         public class OpcodeCast : EmptyCast {
2935                 OpCode op, op2;
2936                 bool second_valid;
2937
2938                 public OpcodeCast (Expression child, Type return_type, OpCode op)
2939                         : base (child, return_type)
2940
2941                 {
2942                         this.op = op;
2943                         second_valid = false;
2944                 }
2945
2946                 public OpcodeCast (Expression child, Type return_type, OpCode op, OpCode op2)
2947                         : base (child, return_type)
2948
2949                 {
2950                         this.op = op;
2951                         this.op2 = op2;
2952                         second_valid = true;
2953                 }
2954
2955                 public override Expression DoResolve (EmitContext ec)
2956                 {
2957                         // This should never be invoked, we are born in fully
2958                         // initialized state.
2959
2960                         return this;
2961                 }
2962
2963                 public override void Emit (EmitContext ec)
2964                 {
2965                         base.Emit (ec);
2966                         ec.ig.Emit (op);
2967
2968                         if (second_valid)
2969                                 ec.ig.Emit (op2);
2970                 }
2971         }
2972
2973         /// <summary>
2974         ///   This kind of cast is used to encapsulate a child and cast it
2975         ///   to the class requested
2976         /// </summary>
2977         public class ClassCast : EmptyCast {
2978                 public ClassCast (Expression child, Type return_type)
2979                         : base (child, return_type)
2980
2981                 {
2982                 }
2983
2984                 public override Expression DoResolve (EmitContext ec)
2985                 {
2986                         // This should never be invoked, we are born in fully
2987                         // initialized state.
2988
2989                         return this;
2990                 }
2991
2992                 public override void Emit (EmitContext ec)
2993                 {
2994                         base.Emit (ec);
2995
2996                         ec.ig.Emit (OpCodes.Castclass, type);
2997                 }
2998
2999         }
3000
3001         /// <summary>
3002         ///   SimpleName expressions are initially formed of a single
3003         ///   word and it only happens at the beginning of the expression.
3004         /// </summary>
3005         ///
3006         /// <remarks>
3007         ///   The expression will try to be bound to a Field, a Method
3008         ///   group or a Property.  If those fail we pass the name to our
3009         ///   caller and the SimpleName is compounded to perform a type
3010         ///   lookup.  The idea behind this process is that we want to avoid
3011         ///   creating a namespace map from the assemblies, as that requires
3012         ///   the GetExportedTypes function to be called and a hashtable to
3013         ///   be constructed which reduces startup time.  If later we find
3014         ///   that this is slower, we should create a `NamespaceExpr' expression
3015         ///   that fully participates in the resolution process.
3016         ///
3017         ///   For example `System.Console.WriteLine' is decomposed into
3018         ///   MemberAccess (MemberAccess (SimpleName ("System"), "Console"), "WriteLine")
3019         ///
3020         ///   The first SimpleName wont produce a match on its own, so it will
3021         ///   be turned into:
3022         ///   MemberAccess (SimpleName ("System.Console"), "WriteLine").
3023         ///
3024         ///   System.Console will produce a TypeExpr match.
3025         ///
3026         ///   The downside of this is that we might be hitting `LookupType' too many
3027         ///   times with this scheme.
3028         /// </remarks>
3029         public class SimpleName : Expression {
3030                 public readonly string Name;
3031                 public readonly Location Location;
3032
3033                 public SimpleName (string name, Location l)
3034                 {
3035                         Name = name;
3036                         Location = l;
3037                 }
3038
3039                 public static void Error120 (Location l, string name)
3040                 {
3041                         Report.Error (
3042                                 120, l,
3043                                 "An object reference is required " +
3044                                 "for the non-static field `"+name+"'");
3045                 }
3046
3047                 //
3048                 // Checks whether we are trying to access an instance
3049                 // property, method or field from a static body.
3050                 //
3051                 Expression MemberStaticCheck (Expression e)
3052                 {
3053                         if (e is FieldExpr){
3054                                 FieldInfo fi = ((FieldExpr) e).FieldInfo;
3055
3056                                 if (!fi.IsStatic){
3057                                         Error120 (Location, Name);
3058                                         return null;
3059                                 }
3060                         } else if (e is MethodGroupExpr){
3061                                 MethodGroupExpr mg = (MethodGroupExpr) e;
3062
3063                                 if (!mg.RemoveInstanceMethods ()){
3064                                         Error120 (Location, mg.Methods [0].Name);
3065                                         return null;
3066                                 }
3067                                 return e;
3068                         } else if (e is PropertyExpr){
3069                                 if (!((PropertyExpr) e).IsStatic){
3070                                         Error120 (Location, Name);
3071                                         return null;
3072                                 }
3073                         } else if (e is EventExpr) {
3074                                 if (!((EventExpr) e).IsStatic) {
3075                                         Error120 (Location, Name);
3076                                         return null;
3077                                 }
3078                         }
3079
3080                         return e;
3081                 }
3082
3083                 public override Expression DoResolve (EmitContext ec)
3084                 {
3085                         return SimpleNameResolve (ec, null, false);
3086                 }
3087
3088                 public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
3089                 {
3090                         return SimpleNameResolve (ec, right_side, false);
3091                 }
3092
3093
3094                 public Expression DoResolveAllowStatic (EmitContext ec)
3095                 {
3096                         return SimpleNameResolve (ec, null, true);
3097                 }
3098
3099                 /// <remarks>
3100                 ///   7.5.2: Simple Names.
3101                 ///
3102                 ///   Local Variables and Parameters are handled at
3103                 ///   parse time, so they never occur as SimpleNames.
3104                 ///
3105                 ///   The `allow_static' flag is used by MemberAccess only
3106                 ///   and it is used to inform us that it is ok for us to
3107                 ///   avoid the static check, because MemberAccess might end
3108                 ///   up resolving the Name as a Type name and the access as
3109                 ///   a static type access.
3110                 ///
3111                 ///   ie: Type Type; .... { Type.GetType (""); }
3112                 ///
3113                 ///   Type is both an instance variable and a Type;  Type.GetType
3114                 ///   is the static method not an instance method of type.
3115                 /// </remarks>
3116                 Expression SimpleNameResolve (EmitContext ec, Expression right_side, bool allow_static)
3117                 {
3118                         Expression e = null;
3119
3120                         //
3121                         // Stage 1: Performed by the parser (binding to locals or parameters).
3122                         //
3123                         if (!ec.OnlyLookupTypes){
3124                                 Block current_block = ec.CurrentBlock;
3125                                 if (current_block != null && current_block.IsVariableDefined (Name)){
3126                                         LocalVariableReference var;
3127
3128                                         var = new LocalVariableReference (ec.CurrentBlock, Name, Location);
3129
3130                                         if (right_side != null)
3131                                                 return var.ResolveLValue (ec, right_side);
3132                                         else
3133                                                 return var.Resolve (ec);
3134                                 }
3135
3136                                 //
3137                                 // Stage 2: Lookup members
3138                                 //
3139
3140                                 //
3141                                 // For enums, the TypeBuilder is not ec.DeclSpace.TypeBuilder
3142                                 // Hence we have two different cases
3143                                 //
3144
3145                                 DeclSpace lookup_ds = ec.DeclSpace;
3146                                 do {
3147                                         if (lookup_ds.TypeBuilder == null)
3148                                                 break;
3149
3150                                         e = MemberLookup (ec, lookup_ds.TypeBuilder, Name, Location);
3151                                         if (e != null)
3152                                                 break;
3153
3154                                         //
3155                                         // Classes/structs keep looking, enums break
3156                                         //
3157                                         if (lookup_ds is TypeContainer)
3158                                                 lookup_ds = ((TypeContainer) lookup_ds).Parent;
3159                                         else
3160                                                 break;
3161                                 } while (lookup_ds != null);
3162
3163                                 if (e == null && ec.ContainerType != null)
3164                                         e = MemberLookup (ec, ec.ContainerType, Name, Location);
3165                         }
3166
3167                         // Continuation of stage 2
3168                         if (e == null){
3169                                 //
3170                                 // Stage 3: Lookup symbol in the various namespaces.
3171                                 //
3172                                 DeclSpace ds = ec.DeclSpace;
3173                                 Type t;
3174                                 string alias_value;
3175
3176                                 if ((t = RootContext.LookupType (ds, Name, true, Location)) != null)
3177                                         return new TypeExpr (t);
3178
3179                                 //
3180                                 // Stage 2 part b: Lookup up if we are an alias to a type
3181                                 // or a namespace.
3182                                 //
3183                                 // Since we are cheating: we only do the Alias lookup for
3184                                 // namespaces if the name does not include any dots in it
3185                                 //
3186
3187                                 if (Name.IndexOf ('.') == -1 && (alias_value = ec.TypeContainer.LookupAlias (Name)) != null) {
3188                                 // System.Console.WriteLine (Name + " --> " + alias_value);
3189                                         if ((t = RootContext.LookupType (ds, alias_value, true, Location))
3190                                             != null)
3191                                                 return new TypeExpr (t);
3192
3193                                 // we have alias value, but it isn't Type, so try if it's namespace
3194                                         return new SimpleName (alias_value, Location);
3195                                 }
3196
3197                                 // No match, maybe our parent can compose us
3198                                 // into something meaningful.
3199                                 return this;
3200                         }
3201
3202                         //
3203                         // Stage 2 continues here.
3204                         //
3205                         if (e is TypeExpr)
3206                                 return e;
3207
3208                         if (ec.OnlyLookupTypes)
3209                                 return null;
3210
3211                         if (e is FieldExpr){
3212                                 FieldExpr fe = (FieldExpr) e;
3213                                 FieldInfo fi = fe.FieldInfo;
3214
3215                                 if (fi.FieldType.IsPointer && !ec.InUnsafe){
3216                                         UnsafeError (Location);
3217                                 }
3218
3219                                 if (ec.IsStatic){
3220                                         if (!allow_static && !fi.IsStatic){
3221                                                 Error120 (Location, Name);
3222                                                 return null;
3223                                         }
3224                                 } else {
3225                                         // If we are not in static code and this
3226                                         // field is not static, set the instance to `this'.
3227
3228                                         if (!fi.IsStatic)
3229                                                 fe.InstanceExpression = ec.This;
3230                                 }
3231
3232
3233                                 if (fi is FieldBuilder) {
3234                                         Const c = TypeManager.LookupConstant ((FieldBuilder) fi);
3235
3236                                         if (c != null) {
3237                                                 object o = c.LookupConstantValue (ec);
3238                                                 object real_value = ((Constant)c.Expr).GetValue ();
3239                                                 return Constantify (real_value, fi.FieldType);
3240                                         }
3241                                 }
3242
3243                                 if (fi.IsLiteral) {
3244                                         Type t = fi.FieldType;
3245                                         Type decl_type = fi.DeclaringType;
3246                                         object o;
3247
3248                                         if (fi is FieldBuilder)
3249                                                 o = TypeManager.GetValue ((FieldBuilder) fi);
3250                                         else
3251                                                 o = fi.GetValue (fi);
3252
3253                                         if (decl_type.IsSubclassOf (TypeManager.enum_type)) {
3254                                                 Expression enum_member = MemberLookup (
3255                                                         ec, decl_type, "value__", MemberTypes.Field,
3256                                                         AllBindingFlags, Location);
3257
3258                                                 Enum en = TypeManager.LookupEnum (decl_type);
3259
3260                                                 Constant c;
3261                                                 if (en != null)
3262                                                         c = Constantify (o, en.UnderlyingType);
3263                                                 else
3264                                                         c = Constantify (o, enum_member.Type);
3265
3266                                                 return new EnumConstant (c, decl_type);
3267                                         }
3268
3269                                         Expression exp = Constantify (o, t);
3270                                 }
3271
3272                                 return e;
3273                         }
3274
3275                         if (e is EventExpr) {
3276                                 //
3277                                 // If the event is local to this class, we transform ourselves into
3278                                 // a FieldExpr
3279                                 //
3280                                 EventExpr ee = (EventExpr) e;
3281
3282                                 Expression ml = MemberLookup (
3283                                         ec, ec.DeclSpace.TypeBuilder, ee.EventInfo.Name,
3284                                         MemberTypes.Event, AllBindingFlags, Location);
3285
3286                                 if (ml != null) {
3287                                         MemberInfo mi = ec.TypeContainer.GetFieldFromEvent ((EventExpr) ml);
3288
3289                                         if (mi == null) {
3290                                                 //
3291                                                 // If this happens, then we have an event with its own
3292                                                 // accessors and private field etc so there's no need
3293                                                 // to transform ourselves : we should instead flag an error
3294                                                 //
3295                                                 Assign.error70 (ee.EventInfo, Location);
3296                                                 return null;
3297                                         }
3298
3299                                         ml = ExprClassFromMemberInfo (ec, mi, Location);
3300
3301                                         if (ml == null) {
3302                                                 Report.Error (-200, Location, "Internal error!!");
3303                                                 return null;
3304                                         }
3305
3306                                         Expression instance_expr;
3307
3308                                         FieldInfo fi = ((FieldExpr) ml).FieldInfo;
3309
3310                                         if (fi.IsStatic)
3311                                                 instance_expr = null;
3312                                         else
3313                                                 instance_expr = ec.This;
3314
3315                                         instance_expr = instance_expr.Resolve (ec);
3316
3317                                         if (instance_expr != null)
3318                                                 instance_expr = instance_expr.Resolve (ec);
3319
3320                                         return MemberAccess.ResolveMemberAccess (ec, ml, instance_expr, Location, null);
3321                                 }
3322                         }
3323
3324
3325                         if (ec.IsStatic){
3326                                 if (allow_static)
3327                                         return e;
3328
3329                                 return MemberStaticCheck (e);
3330                         } else
3331                                 return e;
3332                 }
3333
3334                 public override void Emit (EmitContext ec)
3335                 {
3336                         //
3337                         // If this is ever reached, then we failed to
3338                         // find the name as a namespace
3339                         //
3340
3341                         Error (103, Location, "The name `" + Name +
3342                                "' does not exist in the class `" +
3343                                ec.DeclSpace.Name + "'");
3344                 }
3345         }
3346
3347         /// <summary>
3348         ///   Fully resolved expression that evaluates to a type
3349         /// </summary>
3350         public class TypeExpr : Expression {
3351                 public TypeExpr (Type t)
3352                 {
3353                         Type = t;
3354                         eclass = ExprClass.Type;
3355                 }
3356
3357                 override public Expression DoResolve (EmitContext ec)
3358                 {
3359                         return this;
3360                 }
3361
3362                 override public void Emit (EmitContext ec)
3363                 {
3364                         throw new Exception ("Implement me");
3365                 }
3366         }
3367
3368         /// <summary>
3369         ///   MethodGroup Expression.
3370         ///
3371         ///   This is a fully resolved expression that evaluates to a type
3372         /// </summary>
3373         public class MethodGroupExpr : Expression {
3374                 public MethodBase [] Methods;
3375                 Location loc;
3376                 Expression instance_expression = null;
3377
3378                 public MethodGroupExpr (MemberInfo [] mi, Location l)
3379                 {
3380                         Methods = new MethodBase [mi.Length];
3381                         mi.CopyTo (Methods, 0);
3382                         eclass = ExprClass.MethodGroup;
3383                         type = TypeManager.object_type;
3384                         loc = l;
3385                 }
3386
3387                 public MethodGroupExpr (ArrayList list, Location l)
3388                 {
3389                         Methods = new MethodBase [list.Count];
3390
3391                         try {
3392                                 list.CopyTo (Methods, 0);
3393                         } catch {
3394                                 foreach (MemberInfo m in list){
3395                                         if (!(m is MethodBase)){
3396                                                 Console.WriteLine ("Name " + m.Name);
3397                                                 Console.WriteLine ("Found a: " + m.GetType ().FullName);
3398                                         }
3399                                 }
3400                                 throw;
3401                         }
3402                         loc = l;
3403                         eclass = ExprClass.MethodGroup;
3404                         type = TypeManager.object_type;
3405                 }
3406
3407                 //
3408                 // `A method group may have associated an instance expression'
3409                 //
3410                 public Expression InstanceExpression {
3411                         get {
3412                                 return instance_expression;
3413                         }
3414
3415                         set {
3416                                 instance_expression = value;
3417                         }
3418                 }
3419
3420                 override public Expression DoResolve (EmitContext ec)
3421                 {
3422                         return this;
3423                 }
3424
3425                 public void ReportUsageError ()
3426                 {
3427                         Report.Error (654, loc, "Method `" + Methods [0].DeclaringType + "." +
3428                                       Methods [0].Name + "()' is referenced without parentheses");
3429                 }
3430
3431                 override public void Emit (EmitContext ec)
3432                 {
3433                         ReportUsageError ();
3434                 }
3435
3436                 bool RemoveMethods (bool keep_static)
3437                 {
3438                         ArrayList smethods = new ArrayList ();
3439
3440                         foreach (MethodBase mb in Methods){
3441                                 if (mb.IsStatic == keep_static)
3442                                         smethods.Add (mb);
3443                         }
3444
3445                         if (smethods.Count == 0)
3446                                 return false;
3447
3448                         Methods = new MethodBase [smethods.Count];
3449                         smethods.CopyTo (Methods, 0);
3450
3451                         return true;
3452                 }
3453
3454                 /// <summary>
3455                 ///   Removes any instance methods from the MethodGroup, returns
3456                 ///   false if the resulting set is empty.
3457                 /// </summary>
3458                 public bool RemoveInstanceMethods ()
3459                 {
3460                         return RemoveMethods (true);
3461                 }
3462
3463                 /// <summary>
3464                 ///   Removes any static methods from the MethodGroup, returns
3465                 ///   false if the resulting set is empty.
3466                 /// </summary>
3467                 public bool RemoveStaticMethods ()
3468                 {
3469                         return RemoveMethods (false);
3470                 }
3471         }
3472
3473         /// <summary>
3474         ///   Fully resolved expression that evaluates to a Field
3475         /// </summary>
3476         public class FieldExpr : Expression, IAssignMethod, IMemoryLocation {
3477                 public readonly FieldInfo FieldInfo;
3478                 public Expression InstanceExpression;
3479                 Location loc;
3480
3481                 public FieldExpr (FieldInfo fi, Location l)
3482                 {
3483                         FieldInfo = fi;
3484                         eclass = ExprClass.Variable;
3485                         type = fi.FieldType;
3486                         loc = l;
3487                 }
3488
3489                 override public Expression DoResolve (EmitContext ec)
3490                 {
3491                         if (!FieldInfo.IsStatic){
3492                                 if (InstanceExpression == null){
3493                                         throw new Exception ("non-static FieldExpr without instance var\n" +
3494                                                              "You have to assign the Instance variable\n" +
3495                                                              "Of the FieldExpr to set this\n");
3496                                 }
3497
3498                                 InstanceExpression = InstanceExpression.Resolve (ec);
3499                                 if (InstanceExpression == null)
3500                                         return null;
3501                         }
3502
3503                         return this;
3504                 }
3505
3506                 void Report_AssignToReadonly (bool is_instance)
3507                 {
3508                         string msg;
3509
3510                         if (is_instance)
3511                                 msg = "Readonly field can not be assigned outside " +
3512                                 "of constructor or variable initializer";
3513                         else
3514                                 msg = "A static readonly field can only be assigned in " +
3515                                 "a static constructor";
3516
3517                         Report.Error (is_instance ? 191 : 198, loc, msg);
3518                 }
3519
3520                 override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
3521                 {
3522                         Expression e = DoResolve (ec);
3523
3524                         if (e == null)
3525                                 return null;
3526
3527                         if (!FieldInfo.IsInitOnly)
3528                                 return this;
3529
3530                         //
3531                         // InitOnly fields can only be assigned in constructors
3532                         //
3533
3534                         if (ec.IsConstructor)
3535                                 return this;
3536
3537                         Report_AssignToReadonly (true);
3538
3539                         return null;
3540                 }
3541
3542                 override public void Emit (EmitContext ec)
3543                 {
3544                         ILGenerator ig = ec.ig;
3545                         bool is_volatile = false;
3546
3547                         if (FieldInfo is FieldBuilder){
3548                                 FieldBase f = TypeManager.GetField (FieldInfo);
3549
3550                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
3551                                         is_volatile = true;
3552
3553                                 f.status |= Field.Status.USED;
3554                         }
3555
3556                         if (FieldInfo.IsStatic){
3557                                 if (is_volatile)
3558                                         ig.Emit (OpCodes.Volatile);
3559
3560                                 ig.Emit (OpCodes.Ldsfld, FieldInfo);
3561                         } else {
3562                                 if (InstanceExpression.Type.IsValueType){
3563                                         IMemoryLocation ml;
3564                                         LocalTemporary tempo = null;
3565
3566                                         if (!(InstanceExpression is IMemoryLocation)){
3567                                                 tempo = new LocalTemporary (
3568                                                         ec, InstanceExpression.Type);
3569
3570                                                 InstanceExpression.Emit (ec);
3571                                                 tempo.Store (ec);
3572                                                 ml = tempo;
3573                                         } else
3574                                                 ml = (IMemoryLocation) InstanceExpression;
3575
3576                                         ml.AddressOf (ec, AddressOp.Load);
3577                                 } else
3578                                         InstanceExpression.Emit (ec);
3579
3580                                 if (is_volatile)
3581                                         ig.Emit (OpCodes.Volatile);
3582
3583                                 ig.Emit (OpCodes.Ldfld, FieldInfo);
3584                         }
3585                 }
3586
3587                 public void EmitAssign (EmitContext ec, Expression source)
3588                 {
3589                         FieldAttributes fa = FieldInfo.Attributes;
3590                         bool is_static = (fa & FieldAttributes.Static) != 0;
3591                         bool is_readonly = (fa & FieldAttributes.InitOnly) != 0;
3592                         ILGenerator ig = ec.ig;
3593
3594                         if (is_readonly && !ec.IsConstructor){
3595                                 Report_AssignToReadonly (!is_static);
3596                                 return;
3597                         }
3598
3599                         if (!is_static){
3600                                 Expression instance = InstanceExpression;
3601
3602                                 if (instance.Type.IsValueType){
3603                                         if (instance is IMemoryLocation){
3604                                                 IMemoryLocation ml = (IMemoryLocation) instance;
3605
3606                                                 ml.AddressOf (ec, AddressOp.Store);
3607                                         } else
3608                                                 throw new Exception ("The " + instance + " of type " +
3609                                                                      instance.Type +
3610                                                                      " represents a ValueType and does " +
3611                                                                      "not implement IMemoryLocation");
3612                                 } else
3613                                         instance.Emit (ec);
3614                         }
3615                         source.Emit (ec);
3616
3617                         if (FieldInfo is FieldBuilder){
3618                                 FieldBase f = TypeManager.GetField (FieldInfo);
3619
3620                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
3621                                         ig.Emit (OpCodes.Volatile);
3622                         }
3623
3624                         if (is_static)
3625                                 ig.Emit (OpCodes.Stsfld, FieldInfo);
3626                         else
3627                                 ig.Emit (OpCodes.Stfld, FieldInfo);
3628
3629                         if (FieldInfo is FieldBuilder){
3630                                 FieldBase f = TypeManager.GetField (FieldInfo);
3631
3632                                 f.status |= Field.Status.ASSIGNED;
3633                         }
3634                 }
3635
3636                 public void AddressOf (EmitContext ec, AddressOp mode)
3637                 {
3638                         ILGenerator ig = ec.ig;
3639
3640                         if (FieldInfo is FieldBuilder){
3641                                 FieldBase f = TypeManager.GetField (FieldInfo);
3642                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
3643                                         ig.Emit (OpCodes.Volatile);
3644                         }
3645
3646                         if (FieldInfo is FieldBuilder){
3647                                 FieldBase f = TypeManager.GetField (FieldInfo);
3648
3649                                 if ((mode & AddressOp.Store) != 0)
3650                                         f.status |= Field.Status.ASSIGNED;
3651                                 if ((mode & AddressOp.Load) != 0)
3652                                         f.status |= Field.Status.USED;
3653                         }
3654
3655                         //
3656                         // Handle initonly fields specially: make a copy and then
3657                         // get the address of the copy.
3658                         //
3659                         if (FieldInfo.IsInitOnly){
3660                                 LocalBuilder local;
3661
3662                                 Emit (ec);
3663                                 local = ig.DeclareLocal (type);
3664                                 ig.Emit (OpCodes.Stloc, local);
3665                                 ig.Emit (OpCodes.Ldloca, local);
3666                                 return;
3667                         }
3668
3669                         if (FieldInfo.IsStatic)
3670                                 ig.Emit (OpCodes.Ldsflda, FieldInfo);
3671                         else {
3672                                 InstanceExpression.Emit (ec);
3673                                 ig.Emit (OpCodes.Ldflda, FieldInfo);
3674                         }
3675                 }
3676         }
3677
3678         /// <summary>
3679         ///   Expression that evaluates to a Property.  The Assign class
3680         ///   might set the `Value' expression if we are in an assignment.
3681         ///
3682         ///   This is not an LValue because we need to re-write the expression, we
3683         ///   can not take data from the stack and store it.
3684         /// </summary>
3685         public class PropertyExpr : ExpressionStatement, IAssignMethod {
3686                 public readonly PropertyInfo PropertyInfo;
3687                 public readonly bool IsStatic;
3688                 public bool IsBase;
3689                 MethodInfo [] Accessors;
3690                 Location loc;
3691
3692                 Expression instance_expr;
3693
3694                 public PropertyExpr (PropertyInfo pi, Location l)
3695                 {
3696                         PropertyInfo = pi;
3697                         eclass = ExprClass.PropertyAccess;
3698                         IsStatic = false;
3699                         loc = l;
3700                         Accessors = TypeManager.GetAccessors (pi);
3701
3702                         if (Accessors != null)
3703                                 foreach (MethodInfo mi in Accessors){
3704                                         if (mi != null)
3705                                                 if (mi.IsStatic)
3706                                                         IsStatic = true;
3707                                 }
3708                         else
3709                                 Accessors = new MethodInfo [2];
3710
3711                         type = pi.PropertyType;
3712                 }
3713
3714                 //
3715                 // The instance expression associated with this expression
3716                 //
3717                 public Expression InstanceExpression {
3718                         set {
3719                                 instance_expr = value;
3720                         }
3721
3722                         get {
3723                                 return instance_expr;
3724                         }
3725                 }
3726
3727                 public bool VerifyAssignable ()
3728                 {
3729                         if (!PropertyInfo.CanWrite){
3730                                 Report.Error (200, loc,
3731                                               "The property `" + PropertyInfo.Name +
3732                                               "' can not be assigned to, as it has not set accessor");
3733                                 return false;
3734                         }
3735
3736                         return true;
3737                 }
3738
3739                 override public Expression DoResolve (EmitContext ec)
3740                 {
3741                         if (!PropertyInfo.CanRead){
3742                                 Report.Error (154, loc,
3743                                               "The property `" + PropertyInfo.Name +
3744                                               "' can not be used in " +
3745                                               "this context because it lacks a get accessor");
3746                                 return null;
3747                         }
3748
3749                         type = PropertyInfo.PropertyType;
3750
3751                         return this;
3752                 }
3753
3754                 override public void Emit (EmitContext ec)
3755                 {
3756                         MethodInfo method = Accessors [0];
3757
3758                         //
3759                         // Special case: length of single dimension array is turned into ldlen
3760                         //
3761                         if (method == TypeManager.int_array_get_length){
3762                                 Type iet = instance_expr.Type;
3763
3764                                 if (iet.GetArrayRank () == 1){
3765                                         instance_expr.Emit (ec);
3766                                         ec.ig.Emit (OpCodes.Ldlen);
3767                                         return;
3768                                 }
3769                         }
3770
3771                         Invocation.EmitCall (ec, IsBase, IsStatic, instance_expr, method, null);
3772
3773                 }
3774
3775                 //
3776                 // Implements the IAssignMethod interface for assignments
3777                 //
3778                 public void EmitAssign (EmitContext ec, Expression source)
3779                 {
3780                         Argument arg = new Argument (source, Argument.AType.Expression);
3781                         ArrayList args = new ArrayList ();
3782
3783                         args.Add (arg);
3784                         Invocation.EmitCall (ec, false, IsStatic, instance_expr, Accessors [1], args);
3785                 }
3786
3787                 override public void EmitStatement (EmitContext ec)
3788                 {
3789                         Emit (ec);
3790                         ec.ig.Emit (OpCodes.Pop);
3791                 }
3792         }
3793
3794         /// <summary>
3795         ///   Fully resolved expression that evaluates to an Event
3796         /// </summary>
3797         public class EventExpr : Expression {
3798                 public readonly EventInfo EventInfo;
3799                 Location loc;
3800                 public Expression InstanceExpression;
3801
3802                 public readonly bool IsStatic;
3803
3804                 MethodInfo add_accessor, remove_accessor;
3805
3806                 public EventExpr (EventInfo ei, Location loc)
3807                 {
3808                         EventInfo = ei;
3809                         this.loc = loc;
3810                         eclass = ExprClass.EventAccess;
3811
3812                         add_accessor = TypeManager.GetAddMethod (ei);
3813                         remove_accessor = TypeManager.GetRemoveMethod (ei);
3814
3815                         if (add_accessor.IsStatic || remove_accessor.IsStatic)
3816                                         IsStatic = true;
3817
3818                         if (EventInfo is MyEventBuilder)
3819                                 type = ((MyEventBuilder) EventInfo).EventType;
3820                         else
3821                                 type = EventInfo.EventHandlerType;
3822                 }
3823
3824                 override public Expression DoResolve (EmitContext ec)
3825                 {
3826                         // We are born fully resolved
3827                         return this;
3828                 }
3829
3830                 override public void Emit (EmitContext ec)
3831                 {
3832                         throw new Exception ("Should not happen I think");
3833                 }
3834
3835                 public void EmitAddOrRemove (EmitContext ec, Expression source)
3836                 {
3837                         Expression handler = ((Binary) source).Right;
3838
3839                         Argument arg = new Argument (handler, Argument.AType.Expression);
3840                         ArrayList args = new ArrayList ();
3841
3842                         args.Add (arg);
3843
3844                         if (((Binary) source).Oper == Binary.Operator.Addition)
3845                                 Invocation.EmitCall (
3846                                         ec, false, IsStatic, InstanceExpression, add_accessor, args);
3847                         else
3848                                 Invocation.EmitCall (
3849                                         ec, false, IsStatic, InstanceExpression, remove_accessor, args);
3850                 }
3851         }
3852 }