mcs/mbas/ecore.cs

   1 //
   2 // ecore.cs: Core of the Expression representation for the intermediate tree.
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Manjula GHM (mmanjula@novell.com)
   7 //
   8 // (C) 2001 Ximian, Inc.
   9 //
  10 //
  11
  12 namespace Mono.MonoBASIC {
  13         using System;
  14         using System.Collections;
  15         using System.Diagnostics;
  16         using System.Reflection;
  17         using System.Reflection.Emit;
  18         using System.Text;
  19
  20         /// <remarks>
  21         ///   The ExprClass class contains the is used to pass the
  22         ///   classification of an expression (value, variable, namespace,
  23         ///   type, method group, property access, event access, indexer access,
  24         ///   nothing).
  25         /// </remarks>
  26         public enum ExprClass : byte {
  27                 Invalid,
  28
  29                 Value,
  30                 Variable,
  31                 Namespace,
  32                 Type,
  33                 MethodGroup,
  34                 PropertyAccess,
  35                 EventAccess,
  36                 IndexerAccess,
  37                 Nothing,
  38         }
  39
  40         /// <remarks>
  41         ///   This is used to tell Resolve in which types of expressions we're
  42         ///   interested.
  43         /// </remarks>
  44         [Flags]
  45         public enum ResolveFlags {
  46                 // Returns Value, Variable, PropertyAccess, EventAccess or IndexerAccess.
  47                 VariableOrValue         = 1,
  48
  49                 // Returns a type expression.
  50                 Type                    = 2,
  51
  52                 // Returns a method group.
  53                 MethodGroup             = 4,
  54
  55                 // Allows SimpleNames to be returned.
  56                 // This is used by MemberAccess to construct long names that can not be
  57                 // partially resolved (namespace-qualified names for example).
  58                 SimpleName              = 8,
  59
  60                 // Mask of all the expression class flags.
  61                 MaskExprClass           = 15,
  62
  63                 // Disable control flow analysis while resolving the expression.
  64                 // This is used when resolving the instance expression of a field expression.
  65                 DisableFlowAnalysis     = 16
  66         }
  67
  68         //
  69         // This is just as a hint to AddressOf of what will be done with the
  70         // address.
  71         [Flags]
  72         public enum AddressOp {
  73                 Store = 1,
  74                 Load  = 2,
  75                 LoadStore = 3
  76         };
  77
  78         /// <summary>
  79         ///   This interface is implemented by variables
  80         /// </summary>
  81         public interface IMemoryLocation {
  82                 /// <summary>
  83                 ///   The AddressOf method should generate code that loads
  84                 ///   the address of the object and leaves it on the stack.
  85                 ///
  86                 ///   The 'mode' argument is used to notify the expression
  87                 ///   of whether this will be used to read from the address or
  88                 ///   write to the address.
  89                 ///
  90                 ///   This is just a hint that can be used to provide good error
  91                 ///   reporting, and should have no other side effects.
  92                 /// </summary>
  93                 void AddressOf (EmitContext ec, AddressOp mode);
  94         }
  95
  96         /// <summary>
  97         ///   This interface is implemented by variables
  98         /// </summary>
  99         public interface IVariable {
 100                 /// <summary>
 101                 ///   Checks whether the variable has already been assigned at
 102                 ///   the current position of the method's control flow and
 103                 ///   reports an appropriate error message if not.
 104                 ///
 105                 ///   If the variable is a struct, then this call checks whether
 106                 ///   all of its fields (including all private ones) have been
 107                 ///   assigned.
 108                 /// </summary>
 109                 bool IsAssigned (EmitContext ec, Location loc);
 110
 111                 /// <summary>
 112                 ///   Checks whether field 'name' in this struct has been assigned.
 113                 /// </summary>
 114                 bool IsFieldAssigned (EmitContext ec, string name, Location loc);
 115
 116                 /// <summary>
 117                 ///   Tells the flow analysis code that the variable has already
 118                 ///   been assigned at the current code position.
 119                 ///
 120                 ///   If the variable is a struct, this call marks all its fields
 121                 ///   (including private fields) as being assigned.
 122                 /// </summary>
 123                 void SetAssigned (EmitContext ec);
 124
 125                 /// <summary>
 126                 ///   Tells the flow analysis code that field 'name' in this struct
 127                 ///   has already been assigned atthe current code position.
 128                 /// </summary>
 129                 void SetFieldAssigned (EmitContext ec, string name);
 130         }
 131
 132         /// <summary>
 133         ///   This interface denotes an expression which evaluates to a member
 134         ///   of a struct or a class.
 135         /// </summary>
 136         public interface IMemberExpr
 137         {
 138                 /// <summary>
 139                 ///   The name of this member.
 140                 /// </summary>
 141                 string Name {
 142                         get;
 143                 }
 144
 145                 /// <summary>
 146                 ///   Whether this is an instance member.
 147                 /// </summary>
 148                 bool IsInstance {
 149                         get;
 150                 }
 151
 152                 /// <summary>
 153                 ///   Whether this is a static member.
 154                 /// </summary>
 155                 bool IsStatic {
 156                         get;
 157                 }
 158
 159                 /// <summary>
 160                 ///   The type which declares this member.
 161                 /// </summary>
 162                 Type DeclaringType {
 163                         get;
 164                 }
 165
 166                 /// <summary>
 167                 ///   The instance expression associated with this member, if it's a
 168                 ///   non-static member.
 169                 /// </summary>
 170                 Expression InstanceExpression {
 171                         get; set;
 172                 }
 173         }
 174
 175         /// <summary>
 176         ///   Expression which resolves to a type.
 177         /// </summary>
 178         public interface ITypeExpression
 179         {
 180                 /// <summary>
 181                 ///   Resolve the expression, but only lookup types.
 182                 /// </summary>
 183                 Expression DoResolveType (EmitContext ec);
 184         }
 185
 186         /// <remarks>
 187         ///   Base class for expressions
 188         /// </remarks>
 189         public abstract class Expression {
 190                 public ExprClass eclass;
 191                 protected Type type;
 192                 protected Location loc;
 193
 194                 public Type Type {
 195                         get {
 196                                 return type;
 197                         }
 198
 199                         set {
 200                                 type = value;
 201                         }
 202                 }
 203
 204                 public Location Location {
 205                         get {
 206                                 return loc;
 207                         }
 208                 }
 209
 210                 /// <summary>
 211                 ///   Utility wrapper routine for Error, just to beautify the code
 212                 /// </summary>
 213                 public void Error (int error, string s)
 214                 {
 215                         if (!Location.IsNull (loc))
 216                                 Report.Error (error, loc, s);
 217                         else
 218                                 Report.Error (error, s);
 219                 }
 220
 221                 /// <summary>
 222                 ///   Utility wrapper routine for Warning, just to beautify the code
 223                 /// </summary>
 224                 public void Warning (int warning, string s)
 225                 {
 226                         if (!Location.IsNull (loc))
 227                                 Report.Warning (warning, loc, s);
 228                         else
 229                                 Report.Warning (warning, s);
 230                 }
 231
 232                 /// <summary>
 233                 ///   Utility wrapper routine for Warning, only prints the warning if
 234                 ///   warnings of level 'level' are enabled.
 235                 /// </summary>
 236                 public void Warning (int warning, int level, string s)
 237                 {
 238                         if (level <= RootContext.WarningLevel)
 239                                 Warning (warning, s);
 240                 }
 241
 242                 static public void Error_CannotConvertType (Location loc, Type source, Type target)
 243                 {
 244                         Report.Error (30, loc, "Cannot convert type '" +
 245                                       TypeManager.MonoBASIC_Name (source) + "' to '" +
 246                                       TypeManager.MonoBASIC_Name (target) + "'");
 247                 }
 248
 249                 /// <summary>
 250                 ///   Performs semantic analysis on the Expression
 251                 /// </summary>
 252                 ///
 253                 /// <remarks>
 254                 ///   The Resolve method is invoked to perform the semantic analysis
 255                 ///   on the node.
 256                 ///
 257                 ///   The return value is an expression (it can be the
 258                 ///   same expression in some cases) or a new
 259                 ///   expression that better represents this node.
 260                 ///
 261                 ///   For example, optimizations of Unary (LiteralInt)
 262                 ///   would return a new LiteralInt with a negated
 263                 ///   value.
 264                 ///
 265                 ///   If there is an error during semantic analysis,
 266                 ///   then an error should be reported (using Report)
 267                 ///   and a null value should be returned.
 268                 ///
 269                 ///   There are two side effects expected from calling
 270                 ///   Resolve(): the the field variable "eclass" should
 271                 ///   be set to any value of the enumeration
 272                 ///   'ExprClass' and the type variable should be set
 273                 ///   to a valid type (this is the type of the
 274                 ///   expression).
 275                 /// </remarks>
 276                 public abstract Expression DoResolve (EmitContext ec);
 277
 278                 public virtual Expression DoResolveLValue (EmitContext ec, Expression right_side)
 279                 {
 280                         return DoResolve (ec);
 281                 }
 282
 283                 /// <summary>
 284                 ///   Resolves an expression and performs semantic analysis on it.
 285                 /// </summary>
 286                 ///
 287                 /// <remarks>
 288                 ///   Currently Resolve wraps DoResolve to perform sanity
 289                 ///   checking and assertion checking on what we expect from Resolve.
 290                 /// </remarks>
 291                 public Expression Resolve (EmitContext ec, ResolveFlags flags)
 292                 {
 293                         // Are we doing a types-only search ?
 294                         if ((flags & ResolveFlags.MaskExprClass) == ResolveFlags.Type) {
 295                                 ITypeExpression type_expr = this as ITypeExpression;
 296
 297                                 if (type_expr == null)
 298                                         return null;
 299
 300                                 return type_expr.DoResolveType (ec);
 301                         }
 302
 303                         bool old_do_flow_analysis = ec.DoFlowAnalysis;
 304                         if ((flags & ResolveFlags.DisableFlowAnalysis) != 0)
 305                                 ec.DoFlowAnalysis = false;
 306
 307                         Expression e;
 308                         try {
 309                                 if (this is SimpleName)
 310                                         e = ((SimpleName) this).DoResolveAllowStatic (ec);
 311                                 else
 312                                         e = DoResolve (ec);
 313                         } finally {
 314                                 ec.DoFlowAnalysis = old_do_flow_analysis;
 315                         }
 316
 317                         if (e == null)
 318                                 return null;
 319
 320                         if (e is SimpleName){
 321                                 SimpleName s = (SimpleName) e;
 322
 323                                 if ((flags & ResolveFlags.SimpleName) == 0) {
 324
 325                                         object lookup = TypeManager.MemberLookup (
 326                                                 ec.ContainerType, ec.ContainerType, AllMemberTypes,
 327                                                 AllBindingFlags | BindingFlags.NonPublic, s.Name);
 328                                         if (lookup != null)
 329                                                 Error (30390, "'" + s.Name + "' " +
 330                                                        "is inaccessible because of its protection level");
 331                                         else
 332                                                 Error (30451, "The name '" + s.Name + "' could not be " +
 333                                                        "found in '" + ec.DeclSpace.Name + "'");
 334                                         return null;
 335                                 }
 336
 337                                 return s;
 338                         }
 339
 340                         if ((e is TypeExpr) || (e is ComposedCast)) {
 341                                 if ((flags & ResolveFlags.Type) == 0) {
 342                                         e.Error118 (flags);
 343                                         return null;
 344                                 }
 345
 346                                 return e;
 347                         }
 348
 349                         switch (e.eclass) {
 350                         case ExprClass.Type:
 351                                 if ((flags & ResolveFlags.VariableOrValue) == 0) {
 352                                         e.Error118 (flags);
 353                                         return null;
 354                                 }
 355                                 break;
 356
 357                         case ExprClass.MethodGroup:
 358                                 if ((flags & ResolveFlags.MethodGroup) == 0) {
 359                                         MethodGroupExpr mg = (MethodGroupExpr) e;
 360                                         Invocation i = new Invocation (mg, new ArrayList(), Location.Null);
 361                                         Expression te = i.Resolve(ec);
 362                                         //((MethodGroupExpr) e).ReportUsageError ();
 363                                         //return null;
 364                                         return te;
 365                                 }
 366                                 break;
 367
 368                         case ExprClass.Value:
 369                         case ExprClass.Variable:
 370                         case ExprClass.PropertyAccess:
 371                         case ExprClass.EventAccess:
 372                         case ExprClass.IndexerAccess:
 373                                 if ((flags & ResolveFlags.VariableOrValue) == 0) {
 374                                         e.Error118 (flags);
 375                                         return null;
 376                                 }
 377                                 break;
 378
 379                         default:
 380                                 throw new Exception ("Expression " + e.GetType () +
 381                                                      " ExprClass is Invalid after resolve");
 382                         }
 383
 384                         if (e.type == null)
 385                                 throw new Exception (
 386                                         "Expression " + e.GetType () +
 387                                         " did not set its type after Resolve\n" +
 388                                         "called from: " + this.GetType ());
 389
 390                         return e;
 391                 }
 392
 393                 /// <summary>
 394                 ///   Resolves an expression and performs semantic analysis on it.
 395                 /// </summary>
 396                 public Expression Resolve (EmitContext ec)
 397                 {
 398                         return Resolve (ec, ResolveFlags.VariableOrValue);
 399                 }
 400
 401                 /// <summary>
 402                 ///   Resolves an expression for LValue assignment
 403                 /// </summary>
 404                 ///
 405                 /// <remarks>
 406                 ///   Currently ResolveLValue wraps DoResolveLValue to perform sanity
 407                 ///   checking and assertion checking on what we expect from Resolve
 408                 /// </remarks>
 409                 public Expression ResolveLValue (EmitContext ec, Expression right_side)
 410                 {
 411                         Expression e = DoResolveLValue (ec, right_side);
 412
 413                         if (e != null){
 414                                 if (e is SimpleName){
 415                                         SimpleName s = (SimpleName) e;
 416
 417                                         Report.Error (
 418                                                 30451, loc,
 419                                                 "The name '" + s.Name + "' could not be found in '" +
 420                                                 ec.DeclSpace.Name + "'");
 421                                         return null;
 422                                 }
 423
 424                                 if (e.eclass == ExprClass.Invalid)
 425                                         throw new Exception ("Expression " + e +
 426                                                              " ExprClass is Invalid after resolve");
 427
 428                                 if (e.eclass == ExprClass.MethodGroup) {
 429                                         MethodGroupExpr mg = (MethodGroupExpr) e;
 430                                         Invocation i = new Invocation (mg, new ArrayList(), Location.Null);
 431                                         Expression te = i.Resolve(ec);
 432                                         return te;
 433                                         //((MethodGroupExpr) e).ReportUsageError ();
 434                                         //return null;
 435                                 }
 436
 437                                 if (e.type == null)
 438                                         throw new Exception ("Expression " + e +
 439                                                              " did not set its type after Resolve");
 440                         }
 441
 442                         return e;
 443                 }
 444
 445                 /// <summary>
 446                 ///   Emits the code for the expression
 447                 /// </summary>
 448                 ///
 449                 /// <remarks>
 450                 ///   The Emit method is invoked to generate the code
 451                 ///   for the expression.
 452                 /// </remarks>
 453                 public abstract void Emit (EmitContext ec);
 454
 455                 /// <summary>
 456                 ///   Protected constructor.  Only derivate types should
 457                 ///   be able to be created
 458                 /// </summary>
 459
 460                 protected Expression ()
 461                 {
 462                         eclass = ExprClass.Invalid;
 463                         type = null;
 464                 }
 465
 466                 /// <summary>
 467                 ///   Returns a literalized version of a literal FieldInfo
 468                 /// </summary>
 469                 ///
 470                 /// <remarks>
 471                 ///   The possible return values are:
 472                 ///      IntConstant, UIntConstant
 473                 ///      LongLiteral, ULongConstant
 474                 ///      FloatConstant, DoubleConstant
 475                 ///      StringConstant
 476                 ///
 477                 ///   The value returned is already resolved.
 478                 /// </remarks>
 479                 public static Constant Constantify (object v, Type t)
 480                 {
 481                         if (t == TypeManager.int32_type)
 482                                 return new IntConstant ((int) v);
 483                         else if (t == TypeManager.uint32_type)
 484                                 return new UIntConstant ((uint) v);
 485                         else if (t == TypeManager.int64_type)
 486                                 return new LongConstant ((long) v);
 487                         else if (t == TypeManager.uint64_type)
 488                                 return new ULongConstant ((ulong) v);
 489                         else if (t == TypeManager.float_type)
 490                                 return new FloatConstant ((float) v);
 491                         else if (t == TypeManager.double_type)
 492                                 return new DoubleConstant ((double) v);
 493                         else if (t == TypeManager.string_type)
 494                                 return new StringConstant ((string) v);
 495                         else if (t == TypeManager.short_type)
 496                                 return new ShortConstant ((short)v);
 497                         else if (t == TypeManager.ushort_type)
 498                                 return new UShortConstant ((ushort)v);
 499                         else if (t == TypeManager.sbyte_type)
 500                                 return new SByteConstant (((sbyte)v));
 501                         else if (t == TypeManager.byte_type)
 502                                 return new ByteConstant ((byte)v);
 503                         else if (t == TypeManager.char_type)
 504                                 return new CharConstant ((char)v);
 505                         else if (t == TypeManager.bool_type)
 506                                 return new BoolConstant ((bool) v);
 507                         else if (TypeManager.IsEnumType (t)){
 508                                 Constant e = Constantify (v, TypeManager.TypeToCoreType (v.GetType ()));
 509
 510                                 return new EnumConstant (e, t);
 511                         } else
 512                                 throw new Exception ("Unknown type for constant (" + t +
 513                                                      "), details: " + v);
 514                 }
 515
 516                 /// <summary>
 517                 ///   Returns a fully formed expression after a MemberLookup
 518                 /// </summary>
 519                 public static Expression ExprClassFromMemberInfo (EmitContext ec, MemberInfo mi, Location loc)
 520                 {
 521                         if (mi is EventInfo)
 522                                 return new EventExpr ((EventInfo) mi, loc);
 523                         else if (mi is FieldInfo)
 524                                 return new FieldExpr ((FieldInfo) mi, loc);
 525                         else if (mi is PropertyInfo)
 526                                 return new PropertyExpr (ec, (PropertyInfo) mi, loc);
 527                         else if (mi is Type){
 528                                 return new TypeExpr ((System.Type) mi, loc);
 529                         }
 530
 531                         return null;
 532                 }
 533
 534                 //
 535                 // FIXME: Probably implement a cache for (t,name,current_access_set)?
 536                 //
 537                 // This code could use some optimizations, but we need to do some
 538                 // measurements.  For example, we could use a delegate to 'flag' when
 539                 // something can not any longer be a method-group (because it is something
 540                 // else).
 541                 //
 542                 // Return values:
 543                 //     If the return value is an Array, then it is an array of
 544                 //     MethodBases
 545                 //
 546                 //     If the return value is an MemberInfo, it is anything, but a Method
 547                 //
 548                 //     null on error.
 549                 //
 550                 // FIXME: When calling MemberLookup inside an 'Invocation', we should pass
 551                 // the arguments here and have MemberLookup return only the methods that
 552                 // match the argument count/type, unlike we are doing now (we delay this
 553                 // decision).
 554                 //
 555                 // This is so we can catch correctly attempts to invoke instance methods
 556                 // from a static body (scan for error 120 in ResolveSimpleName).
 557                 //
 558                 //
 559                 // FIXME: Potential optimization, have a static ArrayList
 560                 //
 561
 562                 public static Expression MemberLookup (EmitContext ec, Type t, string name,
 563                                                        MemberTypes mt, BindingFlags bf, Location loc)
 564                 {
 565                         return MemberLookup (ec, ec.ContainerType, t, name, mt, bf, loc);
 566                 }
 567
 568                 //
 569                 // Lookup type 't' for code in class 'invocation_type'.  Note that it's important
 570                 // to set 'invocation_type' correctly since this method also checks whether the
 571                 // invoking class is allowed to access the member in class 't'.  When you want to
 572                 // explicitly do a lookup in the base class, you must set both 't' and 'invocation_type'
 573                 // to the base class (although a derived class can access protected members of its base
 574                 // class it cannot do so through an instance of the base class (error CS1540)).
 575                 //
 576
 577                 public static Expression MemberLookup (EmitContext ec, Type invocation_type, Type t,
 578                                                        string name, MemberTypes mt, BindingFlags bf,
 579                                                        Location loc)
 580                 {
 581                         MemberInfo [] mi = TypeManager.MemberLookup (invocation_type, t, mt, bf, name);
 582
 583                         if (mi == null)
 584                                 return null;
 585
 586                         int count = mi.Length;
 587
 588                         if (count > 1)
 589                                 return new MethodGroupExpr (mi, loc);
 590
 591                         if (mi [0] is MethodBase)
 592                                 return new MethodGroupExpr (mi, loc);
 593
 594                         return ExprClassFromMemberInfo (ec, mi [0], loc);
 595                 }
 596
 597                 public const MemberTypes AllMemberTypes =
 598                         MemberTypes.Constructor |
 599                         MemberTypes.Event       |
 600                         MemberTypes.Field       |
 601                         MemberTypes.Method      |
 602                         MemberTypes.NestedType  |
 603                         MemberTypes.Property;
 604
 605                 public const BindingFlags AllBindingFlags =
 606                         BindingFlags.Public |
 607                         BindingFlags.Static |
 608                         BindingFlags.Instance |
 609                         BindingFlags.IgnoreCase;
 610
 611                 public static Expression MemberLookup (EmitContext ec, Type t, string name, Location loc)
 612                 {
 613                         return MemberLookup (ec, ec.ContainerType, t, name, AllMemberTypes, AllBindingFlags, loc);
 614                 }
 615
 616                 public static Expression MethodLookup (EmitContext ec, Type t, string name, Location loc)
 617                 {
 618                         return MemberLookup (ec, ec.ContainerType, t, name,
 619                                              MemberTypes.Method, AllBindingFlags, loc);
 620                 }
 621
 622                 /// <summary>
 623                 ///   This is a wrapper for MemberLookup that is not used to "probe", but
 624                 ///   to find a final definition.  If the final definition is not found, we
 625                 ///   look for private members and display a useful debugging message if we
 626                 ///   find it.
 627                 /// </summary>
 628                 public static Expression MemberLookupFinal (EmitContext ec, Type t, string name,
 629                                                             Location loc)
 630                 {
 631                         return MemberLookupFinal (ec, t, name, MemberTypes.Method, AllBindingFlags, loc);
 632                 }
 633
 634                 public static Expression MemberLookupFinal (EmitContext ec, Type t, string name,
 635                                                             MemberTypes mt, BindingFlags bf, Location loc)
 636                 {
 637                         Expression e;
 638
 639                         int errors = Report.Errors;
 640
 641                         e = MemberLookup (ec, ec.ContainerType, t, name, mt, bf, loc);
 642
 643                         if (e != null)
 644                                 return e;
 645
 646                         // Error has already been reported.
 647                         if (errors < Report.Errors)
 648                                 return null;
 649
 650                         e = MemberLookup (ec, t, name, AllMemberTypes,
 651                                           AllBindingFlags | BindingFlags.NonPublic, loc);
 652                         if (e == null){
 653                                 Report.Error (
 654                                         30456, loc, "'" + t + "' does not contain a definition " +
 655                                         "for '" + name + "'");
 656                         } else {
 657                                         Report.Error (
 658                                                 30390, loc, "'" + t + "." + name +
 659                                                 "' is inaccessible due to its protection level");
 660                         }
 661
 662                         return null;
 663                 }
 664
 665                 static public MemberInfo GetFieldFromEvent (EventExpr event_expr)
 666                 {
 667                         EventInfo ei = event_expr.EventInfo;
 668
 669                         return TypeManager.GetPrivateFieldOfEvent (ei);
 670                 }
 671
 672                 static EmptyExpression MyEmptyExpr;
 673                 static public Expression ImplicitReferenceConversion (Expression expr, Type target_type)
 674                 {
 675                         Type expr_type = expr.Type;
 676
 677                         if (expr_type == null && expr.eclass == ExprClass.MethodGroup){
 678                                 // if we are a method group, emit a warning
 679
 680                                 expr.Emit (null);
 681                         }
 682
 683                         //
 684                         // notice that it is possible to write "ValueType v = 1", the ValueType here
 685                         // is an abstract class, and not really a value type, so we apply the same rules.
 686                         //
 687                         if (target_type == TypeManager.object_type || target_type == TypeManager.value_type) {
 688                                 //
 689                                 // A pointer type cannot be converted to object
 690                                 //
 691                                 if (expr_type.IsPointer)
 692                                         return null;
 693
 694                                 if (expr_type.IsValueType)
 695                                         return new BoxedCast (expr);
 696                                 if (expr_type.IsClass || expr_type.IsInterface)
 697                                         return new EmptyCast (expr, target_type);
 698                         } else if (expr_type.IsSubclassOf (target_type)) {
 699                                 //
 700                                 // Special case: enumeration to System.Enum.
 701                                 // System.Enum is not a value type, it is a class, so we need
 702                                 // a boxing conversion
 703                                 //
 704                                 if (expr_type.IsEnum)
 705                                         return new BoxedCast (expr);
 706
 707                                 return new EmptyCast (expr, target_type);
 708                         } else {
 709
 710                                 // This code is kind of mirrored inside StandardConversionExists
 711                                 // with the small distinction that we only probe there
 712                                 //
 713                                 // Always ensure that the code here and there is in sync
 714
 715                                 // from the null type to any reference-type.
 716                                 if (expr is NullLiteral && !target_type.IsValueType)
 717                                         return new EmptyCast (expr, target_type);
 718
 719                                 // from any class-type S to any interface-type T.
 720                                 if (target_type.IsInterface) {
 721                                         if (TypeManager.ImplementsInterface (expr_type, target_type)){
 722                                                 if (expr_type.IsClass)
 723                                                         return new EmptyCast (expr, target_type);
 724                                                 else if (expr_type.IsValueType)
 725                                                         return new BoxedCast (expr);
 726                                         }
 727                                 }
 728
 729                                 // from any interface type S to interface-type T.
 730                                 if (expr_type.IsInterface && target_type.IsInterface) {
 731                                         if (TypeManager.ImplementsInterface (expr_type, target_type))
 732                                                 return new EmptyCast (expr, target_type);
 733                                         else
 734                                                 return null;
 735                                 }
 736
 737                                 // from an array-type S to an array-type of type T
 738                                 if (expr_type.IsArray && target_type.IsArray) {
 739                                         if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
 740
 741                                                 Type expr_element_type = expr_type.GetElementType ();
 742
 743                                                 if (MyEmptyExpr == null)
 744                                                         MyEmptyExpr = new EmptyExpression ();
 745
 746                                                 MyEmptyExpr.SetType (expr_element_type);
 747                                                 Type target_element_type = target_type.GetElementType ();
 748
 749                                                 if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
 750                                                         if (StandardConversionExists (MyEmptyExpr,
 751                                                                                       target_element_type))
 752                                                                 return new EmptyCast (expr, target_type);
 753                                         }
 754                                 }
 755
 756
 757                                 // from an array-type to System.Array
 758                                 if (expr_type.IsArray && target_type == TypeManager.array_type)
 759                                         return new EmptyCast (expr, target_type);
 760
 761                                 // from any delegate type to System.Delegate
 762                                 if (expr_type.IsSubclassOf (TypeManager.delegate_type) &&
 763                                     target_type == TypeManager.delegate_type)
 764                                         return new EmptyCast (expr, target_type);
 765
 766                                 // from any array-type or delegate type into System.ICloneable.
 767                                 if (expr_type.IsArray || expr_type.IsSubclassOf (TypeManager.delegate_type))
 768                                         if (target_type == TypeManager.icloneable_type)
 769                                                 return new EmptyCast (expr, target_type);
 770
 771                                 return null;
 772
 773                         }
 774
 775                         return null;
 776                 }
 777
 778                 /// <summary>
 779                 ///   Implicit Numeric Conversions.
 780                 ///
 781                 ///   expr is the expression to convert, returns a new expression of type
 782                 ///   target_type or null if an implicit conversion is not possible.
 783                 /// </summary>
 784                 static public Expression ImplicitNumericConversion (EmitContext ec, Expression expr,
 785                                                                     Type target_type, Location loc)
 786                 {
 787                         Type expr_type = expr.Type;
 788
 789                         //
 790                         // Attempt to do the implicit constant expression conversions
 791
 792                         if (expr is BoolConstant || expr is IntConstant || expr is LongConstant || expr is DoubleConstant || expr is FloatConstant){
 793                                 Expression e;
 794
 795                                 e = TryImplicitNumericConversion (target_type, (Constant) expr);
 796
 797                                 if (e != null)
 798                                         return e;
 799                                 if (target_type == TypeManager.byte_type ||
 800                                     target_type == TypeManager.short_type ||
 801                                     target_type == TypeManager.int32_type ||
 802                                     target_type == TypeManager.int64_type ||
 803                                     target_type == TypeManager.float_type) {
 804
 805                                         string val = null;
 806                                         if (expr is IntConstant)
 807                                                 val = ((IntConstant) expr).Value.ToString();
 808                                         if (expr is LongConstant)
 809                                                 val = ((LongConstant) expr).Value.ToString();
 810                                         if (expr is FloatConstant)
 811                                                 val = ((FloatConstant) expr).Value.ToString();
 812                                         if (expr is DoubleConstant)
 813                                                 val = ((DoubleConstant) expr).Value.ToString();
 814                                         Error_ConstantValueCannotBeConverted(loc, val, target_type);
 815                                         return null;
 816                                 }
 817                         } else if (expr is LongConstant && target_type == TypeManager.uint64_type) {
 818                                 //
 819                                 // Try the implicit constant expression conversion
 820                                 // from long to ulong, instead of a nice routine,
 821                                 // we just inline it
 822                                 //
 823                                 long v = ((LongConstant) expr).Value;
 824                                 if (v > 0)
 825                                         return new ULongConstant ((ulong) v);
 826                         }
 827
 828                         Type real_target_type = target_type;
 829
 830                         if (target_type == TypeManager.bool_type) {
 831
 832                                 if (expr_type == TypeManager.decimal_type) {
 833                                         return RTConversionExpression (ec, "System.Convert",".ToBoolean" , expr, loc);
 834                                 }
 835
 836                                 if ((expr_type != TypeManager.char_type) &&
 837                                     (expr_type != TypeManager.string_type))
 838                                         return new NumericToBoolCast (expr, expr.Type);
 839                         }
 840
 841                         if (expr_type == TypeManager.bool_type){
 842                                 //
 843                                 if (real_target_type == TypeManager.sbyte_type)
 844                                         return new BoolToNumericCast (expr, target_type);
 845                                 if (real_target_type == TypeManager.byte_type)
 846                                         return new BoolToNumericCast (expr, target_type);
 847                                 if (real_target_type == TypeManager.int32_type)
 848                                         return new BoolToNumericCast (expr, target_type);
 849                                 if (real_target_type == TypeManager.int64_type)
 850                                         return new BoolToNumericCast (expr, target_type);
 851                                 if (real_target_type == TypeManager.double_type)
 852                                         return new BoolToNumericCast (expr, target_type);
 853                                 if (real_target_type == TypeManager.float_type)
 854                                         return new BoolToNumericCast (expr, target_type);
 855                                 if (real_target_type == TypeManager.short_type)
 856                                         return new BoolToNumericCast (expr, target_type);
 857                                 if (real_target_type == TypeManager.decimal_type)
 858                                         return RTConversionExpression(ec, "DecimalType.FromBoolean", expr, loc);
 859                         } else if (expr_type == TypeManager.sbyte_type){
 860                                 //
 861                                 // From sbyte to short, int, long, float, double.
 862                                 //
 863                                 if (real_target_type == TypeManager.int32_type)
 864                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 865                                 if (real_target_type == TypeManager.int64_type)
 866                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 867                                 if (real_target_type == TypeManager.double_type)
 868                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 869                                 if (real_target_type == TypeManager.float_type)
 870                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 871                                 if (real_target_type == TypeManager.short_type)
 872                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I2);
 873                         } else if (expr_type == TypeManager.byte_type){
 874                                 //
 875                                 // From byte to short, ushort, int, uint, long, ulong, float, double
 876                                 //
 877                                 if ((real_target_type == TypeManager.short_type) ||
 878                                     (real_target_type == TypeManager.ushort_type) ||
 879                                     (real_target_type == TypeManager.int32_type) ||
 880                                     (real_target_type == TypeManager.uint32_type))
 881                                         return new EmptyCast (expr, target_type);
 882
 883                                 if (real_target_type == TypeManager.uint64_type)
 884                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 885                                 if (real_target_type == TypeManager.int64_type)
 886                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 887                                 if (real_target_type == TypeManager.float_type)
 888                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 889                                 if (real_target_type == TypeManager.double_type)
 890                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 891                         } else if (expr_type == TypeManager.short_type){
 892                                 //
 893                                 // From short to int, long, float, double
 894                                 //
 895                                 if (real_target_type == TypeManager.int32_type)
 896                                         return new EmptyCast (expr, target_type);
 897                                 if (real_target_type == TypeManager.int64_type)
 898                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 899                                 if (real_target_type == TypeManager.double_type)
 900                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 901                                 if (real_target_type == TypeManager.float_type)
 902                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 903                         } else if (expr_type == TypeManager.ushort_type){
 904                                 //
 905                                 // From ushort to int, uint, long, ulong, float, double
 906                                 //
 907                                 if (real_target_type == TypeManager.uint32_type)
 908                                         return new EmptyCast (expr, target_type);
 909
 910                                 if (real_target_type == TypeManager.uint64_type)
 911                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 912                                 if (real_target_type == TypeManager.int32_type)
 913                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I4);
 914                                 if (real_target_type == TypeManager.int64_type)
 915                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 916                                 if (real_target_type == TypeManager.double_type)
 917                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 918                                 if (real_target_type == TypeManager.float_type)
 919                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 920                         } else if (expr_type == TypeManager.int32_type){
 921                                 //
 922                                 // From int to long, float, double
 923                                 //
 924                                 if (real_target_type == TypeManager.int64_type)
 925                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 926                                 if (real_target_type == TypeManager.double_type)
 927                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 928                                 if (real_target_type == TypeManager.float_type)
 929                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 930                         } else if (expr_type == TypeManager.uint32_type){
 931                                 //
 932                                 // From uint to long, ulong, float, double
 933                                 //
 934                                 if (real_target_type == TypeManager.int64_type)
 935                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 936                                 if (real_target_type == TypeManager.uint64_type)
 937                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 938                                 if (real_target_type == TypeManager.double_type)
 939                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 940                                                                OpCodes.Conv_R8);
 941                                 if (real_target_type == TypeManager.float_type)
 942                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 943                                                                OpCodes.Conv_R4);
 944                         } else if (expr_type == TypeManager.int64_type){
 945                                 //
 946                                 // From long/ulong to float, double
 947                                 //
 948                                 if (real_target_type == TypeManager.double_type)
 949                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 950                                 if (real_target_type == TypeManager.float_type)
 951                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 952                         } else if (expr_type == TypeManager.uint64_type){
 953                                 //
 954                                 // From ulong to float, double
 955                                 //
 956                                 if (real_target_type == TypeManager.double_type)
 957                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 958                                                                OpCodes.Conv_R8);
 959                                 if (real_target_type == TypeManager.float_type)
 960                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R_Un,
 961                                                                OpCodes.Conv_R4);
 962                         } else if (expr_type == TypeManager.char_type){
 963                                 //
 964                                 // From char to ushort, int, uint, long, ulong, float, double
 965                                 //
 966                                 if ((real_target_type == TypeManager.ushort_type) ||
 967                                     (real_target_type == TypeManager.int32_type) ||
 968                                     (real_target_type == TypeManager.uint32_type))
 969                                         return new EmptyCast (expr, target_type);
 970                                 if (real_target_type == TypeManager.uint64_type)
 971                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_U8);
 972                                 if (real_target_type == TypeManager.int64_type)
 973                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_I8);
 974                                 if (real_target_type == TypeManager.float_type)
 975                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R4);
 976                                 if (real_target_type == TypeManager.double_type)
 977                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
 978                         } else if (expr_type == TypeManager.string_type){
 979
 980                                 if (real_target_type == TypeManager.bool_type)
 981                                         return RTConversionExpression (ec, "BooleanType.FromString" , expr, loc);
 982                                 if (real_target_type == TypeManager.decimal_type)
 983                                         return RTConversionExpression (ec, "DecimalType.FromString" , expr, loc);
 984                                 if (real_target_type == TypeManager.float_type)
 985                                         return RTConversionExpression (ec, "SingleType.FromString" , expr, loc);
 986                                 if (real_target_type == TypeManager.short_type)
 987                                         return RTConversionExpression (ec, "ShortType.FromString" , expr, loc);
 988                                 if (real_target_type == TypeManager.int64_type)
 989                                         return RTConversionExpression (ec, "LongType.FromString" , expr, loc);
 990                                 if (real_target_type == TypeManager.int32_type)
 991                                         return RTConversionExpression (ec, "IntegerType.FromString" , expr, loc);
 992                                 if (real_target_type == TypeManager.double_type)
 993                                         return RTConversionExpression (ec, "DoubleType.FromString" , expr, loc);
 994                                 if (real_target_type == TypeManager.byte_type)
 995                                         return RTConversionExpression (ec, "ByteType.FromString" , expr, loc);
 996                         } else if (expr_type == TypeManager.float_type){
 997                                 //
 998                                 // float to double
 999                                 //
1000                                 if (real_target_type == TypeManager.decimal_type)
1001                                         return RTConversionExpression (ec, "System.Convert", ".ToDecimal" , expr, loc);
1002                                 if (real_target_type == TypeManager.double_type)
1003                                         return new OpcodeCast (expr, target_type, OpCodes.Conv_R8);
1004
1005                         } else if (expr_type == TypeManager.double_type){
1006
1007                                 if (real_target_type == TypeManager.decimal_type)
1008                                         return RTConversionExpression (ec, "System.Convert", ".ToDecimal" , expr, loc);
1009                         } else if (expr_type == TypeManager.decimal_type){
1010
1011                                 if (real_target_type == TypeManager.bool_type)
1012                                         return RTConversionExpression (ec, "BooleanType.FromDecimal" , expr, loc);
1013                                 if (real_target_type == TypeManager.short_type)
1014                                         return RTConversionExpression(ec, "System.Convert", ".ToInt16", expr, loc);
1015                                 if (real_target_type == TypeManager.byte_type)
1016                                         return RTConversionExpression(ec, "System.Convert", ".ToByte", expr, loc);
1017                                 if (real_target_type == TypeManager.int32_type)
1018                                         return RTConversionExpression(ec, "System.Convert", ".ToInt32", expr, loc);
1019                                 if (real_target_type == TypeManager.int64_type)
1020                                         return RTConversionExpression(ec, "System.Convert", ".ToInt64", expr, loc);
1021                                 if (real_target_type == TypeManager.float_type)
1022                                         return RTConversionExpression(ec, "System.Convert", ".ToSingle", expr, loc);
1023                                 if (real_target_type == TypeManager.double_type)
1024                                         return RTConversionExpression(ec, "System.Convert", ".ToDouble", expr, loc);
1025                                 if (real_target_type == TypeManager.char_type)
1026                                         return RTConversionExpression(ec, "System.Convert", ".ToChar", expr, loc);
1027                         }
1028
1029                         return null;
1030                 }
1031
1032                 //
1033                 // Tests whether an implicit reference conversion exists between expr_type
1034                 // and target_type
1035                 //
1036                 public static bool ImplicitReferenceConversionExists (Expression expr, Type expr_type, Type target_type)
1037                 {
1038                         //
1039                         // This is the boxed case.
1040                         //
1041                         if (target_type == TypeManager.object_type) {
1042                                 if ((expr_type.IsClass) ||
1043                                     (expr_type.IsValueType) ||
1044                                     (expr_type.IsInterface))
1045                                         return true;
1046
1047                         } else if (expr_type.IsSubclassOf (target_type)) {
1048                                 return true;
1049                         } else {
1050                                 // Please remember that all code below actually comes
1051                                 // from ImplicitReferenceConversion so make sure code remains in sync
1052
1053                                 // from any class-type S to any interface-type T.
1054                                 if (target_type.IsInterface) {
1055                                         if (TypeManager.ImplementsInterface (expr_type, target_type))
1056                                                 return true;
1057                                 }
1058
1059                                 // from any interface type S to interface-type T.
1060                                 if (expr_type.IsInterface && target_type.IsInterface)
1061                                         if (TypeManager.ImplementsInterface (expr_type, target_type))
1062                                                 return true;
1063
1064                                 // from an array-type S to an array-type of type T
1065                                 if (expr_type.IsArray && target_type.IsArray) {
1066                                         if (expr_type.GetArrayRank () == target_type.GetArrayRank ()) {
1067
1068                                                 Type expr_element_type = expr_type.GetElementType ();
1069
1070                                                 if (MyEmptyExpr == null)
1071                                                         MyEmptyExpr = new EmptyExpression ();
1072
1073                                                 MyEmptyExpr.SetType (expr_element_type);
1074                                                 Type target_element_type = target_type.GetElementType ();
1075
1076                                                 if (!expr_element_type.IsValueType && !target_element_type.IsValueType)
1077                                                         if (StandardConversionExists (MyEmptyExpr,
1078                                                                                       target_element_type))
1079                                                                 return true;
1080                                         }
1081                                 }
1082
1083                                 // from an array-type to System.Array
1084                                 if (expr_type.IsArray && (target_type == TypeManager.array_type))
1085                                         return true;
1086
1087                                 // from any delegate type to System.Delegate
1088                                 if (expr_type.IsSubclassOf (TypeManager.delegate_type) &&
1089                                     target_type == TypeManager.delegate_type)
1090                                         if (target_type.IsAssignableFrom (expr_type))
1091                                                 return true;
1092
1093                                 // from any array-type or delegate type into System.ICloneable.
1094                                 if (expr_type.IsArray || expr_type.IsSubclassOf (TypeManager.delegate_type))
1095                                         if (target_type == TypeManager.icloneable_type)
1096                                                 return true;
1097
1098                                 // from the null type to any reference-type.
1099                                 if (expr is NullLiteral && !target_type.IsValueType &&
1100                                     !TypeManager.IsEnumType (target_type))
1101                                         return true;
1102
1103                         }
1104
1105                         return false;
1106                 }
1107
1108                 /// <summary>
1109                 ///  Same as StandardConversionExists except that it also looks at
1110                 ///  implicit user defined conversions - needed for overload resolution
1111                 /// </summary>
1112                 public static bool ImplicitConversionExists (EmitContext ec, Expression expr, Type target_type)
1113                 {
1114                         if (StandardConversionExists (expr, target_type) == true)
1115                                 return true;
1116
1117 #if false
1118                         Expression dummy = ImplicitUserConversion (ec, expr, target_type, Location.Null);
1119
1120                         if (dummy != null)
1121                                 return true;
1122 #endif
1123
1124                         return false;
1125                 }
1126
1127                 /// <summary>
1128                 ///  Determines if a standard implicit conversion exists from
1129                 ///  expr_type to target_type
1130                 /// </summary>
1131                 public static bool StandardConversionExists (Expression expr, Type target_type)
1132                 {
1133                         return WideningConversionExists (expr, expr.type, target_type);
1134                 }
1135
1136                 public static bool WideningConversionExists (Type expr_type, Type target_type)
1137                 {
1138                         return WideningConversionExists (null, expr_type, target_type);
1139                 }
1140
1141                 public static bool WideningConversionExists (Expression expr, Type target_type)
1142                 {
1143                         return WideningConversionExists (expr, expr.Type, target_type);
1144                 }
1145
1146                 public static bool WideningConversionExists (Expression expr, Type expr_type, Type target_type)
1147                 {
1148
1149                         if (expr_type == null || expr_type == TypeManager.void_type)
1150                                 return false;
1151
1152                         if (expr_type == target_type)
1153                                 return true;
1154
1155                         // Conversions from enum to underlying type are widening.
1156                         if (expr_type.IsSubclassOf (TypeManager.enum_type))
1157                                 expr_type = TypeManager.EnumToUnderlying (expr_type);
1158
1159                         if (expr_type == target_type)
1160                                 return true;
1161
1162                         // First numeric conversions
1163
1164                         if (expr_type == TypeManager.sbyte_type){
1165                                 //
1166                                 // From sbyte to short, int, long, float, double.
1167                                 //
1168                                 if ((target_type == TypeManager.int32_type) ||
1169                                     (target_type == TypeManager.int64_type) ||
1170                                     (target_type == TypeManager.double_type) ||
1171                                     (target_type == TypeManager.float_type)  ||
1172                                     (target_type == TypeManager.short_type) ||
1173                                     (target_type == TypeManager.decimal_type))
1174                                         return true;
1175
1176                         } else if (expr_type == TypeManager.byte_type){
1177                                 //
1178                                 // From byte to short, ushort, int, uint, long, ulong, float, double
1179                                 //
1180                                 if ((target_type == TypeManager.short_type) ||
1181                                     (target_type == TypeManager.bool_type) ||
1182                                     (target_type == TypeManager.ushort_type) ||
1183                                     (target_type == TypeManager.int32_type) ||
1184                                     (target_type == TypeManager.uint32_type) ||
1185                                     (target_type == TypeManager.uint64_type) ||
1186                                     (target_type == TypeManager.int64_type) ||
1187                                     (target_type == TypeManager.float_type) ||
1188                                     (target_type == TypeManager.double_type) ||
1189                                     (target_type == TypeManager.decimal_type))
1190                                         return true;
1191
1192                         } else if (expr_type == TypeManager.short_type){
1193                                 //
1194                                 // From short to int, long, float, double
1195                                 //
1196                                 if ((target_type == TypeManager.int32_type) ||
1197                                     (target_type == TypeManager.bool_type) ||
1198                                     (target_type == TypeManager.int64_type) ||
1199                                     (target_type == TypeManager.double_type) ||
1200                                     (target_type == TypeManager.float_type) ||
1201                                     (target_type == TypeManager.decimal_type))
1202                                         return true;
1203
1204                         } else if (expr_type == TypeManager.ushort_type){
1205                                 //
1206                                 // From ushort to int, uint, long, ulong, float, double
1207                                 //
1208                                 if ((target_type == TypeManager.uint32_type) ||
1209                                     (target_type == TypeManager.uint64_type) ||
1210                                     (target_type == TypeManager.int32_type) ||
1211                                     (target_type == TypeManager.int64_type) ||
1212                                     (target_type == TypeManager.double_type) ||
1213                                     (target_type == TypeManager.float_type) ||
1214                                     (target_type == TypeManager.decimal_type))
1215                                         return true;
1216
1217                         } else if (expr_type == TypeManager.int32_type){
1218                                 //
1219                                 // From int to long, float, double
1220                                 //
1221                                 if ((target_type == TypeManager.int64_type) ||
1222                                     (target_type == TypeManager.bool_type) ||
1223                                     (target_type == TypeManager.double_type) ||
1224                                     (target_type == TypeManager.float_type) ||
1225                                     (target_type == TypeManager.decimal_type))
1226                                         return true;
1227
1228                         } else if (expr_type == TypeManager.uint32_type){
1229                                 //
1230                                 // From uint to long, ulong, float, double
1231                                 //
1232                                 if ((target_type == TypeManager.int64_type) ||
1233                                     (target_type == TypeManager.bool_type) ||
1234                                     (target_type == TypeManager.uint64_type) ||
1235                                     (target_type == TypeManager.double_type) ||
1236                                     (target_type == TypeManager.float_type) ||
1237                                     (target_type == TypeManager.decimal_type))
1238                                         return true;
1239
1240                         } else if ((expr_type == TypeManager.uint64_type) ||
1241                                    (expr_type == TypeManager.int64_type)) {
1242                                 //
1243                                 // From long/ulong to float, double
1244                                 //
1245                                 if ((target_type == TypeManager.double_type) ||
1246                                     (target_type == TypeManager.bool_type) ||
1247                                     (target_type == TypeManager.float_type) ||
1248                                     (target_type == TypeManager.decimal_type))
1249                                         return true;
1250
1251                         } else if (expr_type == TypeManager.char_type){
1252                                 //
1253                                 // From char to ushort, int, uint, long, ulong, float, double
1254                                 //
1255                                 if ((target_type == TypeManager.ushort_type) ||
1256                                     (target_type == TypeManager.int32_type) ||
1257                                     (target_type == TypeManager.uint32_type) ||
1258                                     (target_type == TypeManager.uint64_type) ||
1259                                     (target_type == TypeManager.int64_type) ||
1260                                     (target_type == TypeManager.float_type) ||
1261                                     (target_type == TypeManager.double_type) ||
1262                                     (target_type == TypeManager.string_type) ||
1263                                     (target_type == TypeManager.decimal_type))
1264                                         return true;
1265
1266                         } else if (expr_type == TypeManager.decimal_type) {
1267                                 if (target_type == TypeManager.float_type ||
1268                                     target_type == TypeManager.double_type)
1269                                         return true;
1270                         } else if (expr_type == TypeManager.float_type){
1271                                 //
1272                                 // float to double, decimal
1273                                 //
1274                                 if (target_type == TypeManager.double_type)
1275                                         return true;
1276                         } else if (expr_type == TypeManager.double_type){
1277
1278                                 if ((target_type == TypeManager.bool_type))
1279                                         return true;
1280                         }
1281
1282                         if (ImplicitReferenceConversionExists (expr, expr_type, target_type))
1283                                 return true;
1284
1285                         if (expr is IntConstant){
1286                                 int value = ((IntConstant) expr).Value;
1287
1288                                 if (target_type == TypeManager.sbyte_type){
1289                                         if (value >= SByte.MinValue && value <= SByte.MaxValue)
1290                                                 return true;
1291                                 } else if (target_type == TypeManager.byte_type){
1292                                         if (Byte.MinValue >= 0 && value <= Byte.MaxValue)
1293                                                 return true;
1294                                 } else if (target_type == TypeManager.short_type){
1295                                         if (value >= Int16.MinValue && value <= Int16.MaxValue)
1296                                                 return true;
1297                                 } else if (target_type == TypeManager.ushort_type){
1298                                         if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
1299                                                 return true;
1300                                 } else if (target_type == TypeManager.uint32_type){
1301                                         if (value >= 0)
1302                                                 return true;
1303                                 } else if (target_type == TypeManager.uint64_type){
1304                                          //
1305                                          // we can optimize this case: a positive int32
1306                                          // always fits on a uint64.  But we need an opcode
1307                                          // to do it.
1308                                          //
1309                                         if (value >= 0)
1310                                                 return true;
1311                                 }
1312
1313                                 if (value == 0 && expr is IntLiteral && TypeManager.IsEnumType (target_type))
1314                                         return true;
1315                         }
1316
1317                         if (expr is LongConstant && target_type == TypeManager.uint64_type){
1318                                 //
1319                                 // Try the implicit constant expression conversion
1320                                 // from long to ulong, instead of a nice routine,
1321                                 // we just inline it
1322                                 //
1323                                 long v = ((LongConstant) expr).Value;
1324                                 if (v > 0)
1325                                         return true;
1326                         }
1327
1328                         if (target_type.IsSubclassOf (TypeManager.enum_type) && expr is IntLiteral){
1329                                 IntLiteral i = (IntLiteral) expr;
1330
1331                                 if (i.Value == 0)
1332                                         return true;
1333                         }
1334
1335                         if (target_type == TypeManager.void_ptr_type && expr_type.IsPointer)
1336                                 return true;
1337
1338                         return false;
1339                 }
1340
1341                 //
1342                 // Used internally by FindMostEncompassedType, this is used
1343                 // to avoid creating lots of objects in the tight loop inside
1344                 // FindMostEncompassedType
1345                 //
1346                 static EmptyExpression priv_fmet_param;
1347
1348                 /// <summary>
1349                 ///  Finds "most encompassed type" according to the spec (13.4.2)
1350                 ///  amongst the methods in the MethodGroupExpr
1351                 /// </summary>
1352                 static Type FindMostEncompassedType (ArrayList types)
1353                 {
1354                         Type best = null;
1355
1356                         if (priv_fmet_param == null)
1357                                 priv_fmet_param = new EmptyExpression ();
1358
1359                         foreach (Type t in types){
1360                                 priv_fmet_param.SetType (t);
1361
1362                                 if (best == null) {
1363                                         best = t;
1364                                         continue;
1365                                 }
1366
1367                                 if (StandardConversionExists (priv_fmet_param, best))
1368                                         best = t;
1369                         }
1370
1371                         return best;
1372                 }
1373
1374                 //
1375                 // Used internally by FindMostEncompassingType, this is used
1376                 // to avoid creating lots of objects in the tight loop inside
1377                 // FindMostEncompassingType
1378                 //
1379                 static EmptyExpression priv_fmee_ret;
1380
1381                 /// <summary>
1382                 ///  Finds "most encompassing type" according to the spec (13.4.2)
1383                 ///  amongst the types in the given set
1384                 /// </summary>
1385                 static Type FindMostEncompassingType (ArrayList types)
1386                 {
1387                         Type best = null;
1388
1389                         if (priv_fmee_ret == null)
1390                                 priv_fmee_ret = new EmptyExpression ();
1391
1392                         foreach (Type t in types){
1393                                 priv_fmee_ret.SetType (best);
1394
1395                                 if (best == null) {
1396                                         best = t;
1397                                         continue;
1398                                 }
1399
1400                                 if (StandardConversionExists (priv_fmee_ret, t))
1401                                         best = t;
1402                         }
1403
1404                         return best;
1405                 }
1406
1407                 //
1408                 // Used to avoid creating too many objects
1409                 //
1410                 static EmptyExpression priv_fms_expr;
1411
1412                 /// <summary>
1413                 ///   Finds the most specific source Sx according to the rules of the spec (13.4.4)
1414                 ///   by making use of FindMostEncomp* methods. Applies the correct rules separately
1415                 ///   for explicit and implicit conversion operators.
1416                 /// </summary>
1417                 static public Type FindMostSpecificSource (MethodGroupExpr me, Expression source,
1418                                                            bool apply_explicit_conv_rules,
1419                                                            Location loc)
1420                 {
1421                         ArrayList src_types_set = new ArrayList ();
1422
1423                         if (priv_fms_expr == null)
1424                                 priv_fms_expr = new EmptyExpression ();
1425
1426                         //
1427                         // If any operator converts from S then Sx = S
1428                         //
1429                         Type source_type= source.Type;
1430                         foreach (MethodBase mb in me.Methods){
1431                                 ParameterData pd = Invocation.GetParameterData (mb);
1432                                 Type param_type = pd.ParameterType (0);
1433
1434                                 if (param_type == source_type)
1435                                         return param_type;
1436
1437                                 if (apply_explicit_conv_rules) {
1438                                         //
1439                                         // From the spec :
1440                                         // Find the set of applicable user-defined conversion operators, U.  This set
1441                                         // consists of the
1442                                         // user-defined implicit or explicit conversion operators declared by
1443                                         // the classes or structs in D that convert from a type encompassing
1444                                         // or encompassed by S to a type encompassing or encompassed by T
1445                                         //
1446                                         priv_fms_expr.SetType (param_type);
1447                                         if (StandardConversionExists (priv_fms_expr, source_type))
1448                                                 src_types_set.Add (param_type);
1449                                         else {
1450                                                 if (StandardConversionExists (source, param_type))
1451                                                         src_types_set.Add (param_type);
1452                                         }
1453                                 } else {
1454                                         //
1455                                         // Only if S is encompassed by param_type
1456                                         //
1457                                         if (StandardConversionExists (source, param_type))
1458                                                 src_types_set.Add (param_type);
1459                                 }
1460                         }
1461
1462                         //
1463                         // Explicit Conv rules
1464                         //
1465                         if (apply_explicit_conv_rules) {
1466                                 ArrayList candidate_set = new ArrayList ();
1467
1468                                 foreach (Type param_type in src_types_set){
1469                                         if (StandardConversionExists (source, param_type))
1470                                                 candidate_set.Add (param_type);
1471                                 }
1472
1473                                 if (candidate_set.Count != 0)
1474                                         return FindMostEncompassedType (candidate_set);
1475                         }
1476
1477                         //
1478                         // Final case
1479                         //
1480                         if (apply_explicit_conv_rules)
1481                                 return FindMostEncompassingType (src_types_set);
1482                         else
1483                                 return FindMostEncompassedType (src_types_set);
1484                 }
1485
1486                 //
1487                 // Useful in avoiding proliferation of objects
1488                 //
1489                 static EmptyExpression priv_fmt_expr;
1490
1491                 /// <summary>
1492                 ///  Finds the most specific target Tx according to section 13.4.4
1493                 /// </summary>
1494                 static public Type FindMostSpecificTarget (MethodGroupExpr me, Type target,
1495                                                            bool apply_explicit_conv_rules,
1496                                                            Location loc)
1497                 {
1498                         ArrayList tgt_types_set = new ArrayList ();
1499
1500                         if (priv_fmt_expr == null)
1501                                 priv_fmt_expr = new EmptyExpression ();
1502
1503                         //
1504                         // If any operator converts to T then Tx = T
1505                         //
1506                         foreach (MethodInfo mi in me.Methods){
1507                                 Type ret_type = mi.ReturnType;
1508
1509                                 if (ret_type == target)
1510                                         return ret_type;
1511
1512                                 if (apply_explicit_conv_rules) {
1513                                         //
1514                                         // From the spec :
1515                                         // Find the set of applicable user-defined conversion operators, U.
1516                                         //
1517                                         // This set consists of the
1518                                         // user-defined implicit or explicit conversion operators declared by
1519                                         // the classes or structs in D that convert from a type encompassing
1520                                         // or encompassed by S to a type encompassing or encompassed by T
1521                                         //
1522                                         priv_fms_expr.SetType (ret_type);
1523                                         if (StandardConversionExists (priv_fms_expr, target))
1524                                                 tgt_types_set.Add (ret_type);
1525                                         else {
1526                                                 priv_fms_expr.SetType (target);
1527                                                 if (StandardConversionExists (priv_fms_expr, ret_type))
1528                                                         tgt_types_set.Add (ret_type);
1529                                         }
1530                                 } else {
1531                                         //
1532                                         // Only if T is encompassed by param_type
1533                                         //
1534                                         priv_fms_expr.SetType (ret_type);
1535                                         if (StandardConversionExists (priv_fms_expr, target))
1536                                                 tgt_types_set.Add (ret_type);
1537                                 }
1538                         }
1539
1540                         //
1541                         // Explicit conv rules
1542                         //
1543                         if (apply_explicit_conv_rules) {
1544                                 ArrayList candidate_set = new ArrayList ();
1545
1546                                 foreach (Type ret_type in tgt_types_set){
1547                                         priv_fmt_expr.SetType (ret_type);
1548
1549                                         if (StandardConversionExists (priv_fmt_expr, target))
1550                                                 candidate_set.Add (ret_type);
1551                                 }
1552
1553                                 if (candidate_set.Count != 0)
1554                                         return FindMostEncompassingType (candidate_set);
1555                         }
1556
1557                         //
1558                         // Okay, final case !
1559                         //
1560                         if (apply_explicit_conv_rules)
1561                                 return FindMostEncompassedType (tgt_types_set);
1562                         else
1563                                 return FindMostEncompassingType (tgt_types_set);
1564                 }
1565
1566                 /// <summary>
1567                 ///  User-defined Implicit conversions
1568                 /// </summary>
1569                 static public Expression ImplicitUserConversion (EmitContext ec, Expression source,
1570                                                                  Type target, Location loc)
1571                 {
1572                         return UserDefinedConversion (ec, source, target, loc, false);
1573                 }
1574
1575                 /// <summary>
1576                 ///  User-defined Explicit conversions
1577                 /// </summary>
1578                 static public Expression ExplicitUserConversion (EmitContext ec, Expression source,
1579                                                                  Type target, Location loc)
1580                 {
1581                         return UserDefinedConversion (ec, source, target, loc, true);
1582                 }
1583
1584                 /// <summary>
1585                 ///   Computes the MethodGroup for the user-defined conversion
1586                 ///   operators from source_type to target_type.  'look_for_explicit'
1587                 ///   controls whether we should also include the list of explicit
1588                 ///   operators
1589                 /// </summary>
1590                 static MethodGroupExpr GetConversionOperators (EmitContext ec,
1591                                                                Type source_type, Type target_type,
1592                                                                Location loc, bool look_for_explicit)
1593                 {
1594                         Expression mg1 = null, mg2 = null;
1595                         Expression mg5 = null, mg6 = null, mg7 = null, mg8 = null;
1596                         string op_name;
1597
1598                         //
1599                         // FIXME : How does the False operator come into the picture ?
1600                         // This doesn't look complete and very correct !
1601                         //
1602                         if (target_type == TypeManager.bool_type && !look_for_explicit)
1603                                 op_name = "op_True";
1604                         else
1605                                 op_name = "op_Implicit";
1606
1607                         MethodGroupExpr union3;
1608
1609                         mg1 = MethodLookup (ec, source_type, op_name, loc);
1610                         if (source_type.BaseType != null)
1611                                 mg2 = MethodLookup (ec, source_type.BaseType, op_name, loc);
1612
1613                         if (mg1 == null)
1614                                 union3 = (MethodGroupExpr) mg2;
1615                         else if (mg2 == null)
1616                                 union3 = (MethodGroupExpr) mg1;
1617                         else
1618                                 union3 = Invocation.MakeUnionSet (mg1, mg2, loc);
1619
1620                         mg1 = MethodLookup (ec, target_type, op_name, loc);
1621                         if (mg1 != null){
1622                                 if (union3 != null)
1623                                         union3 = Invocation.MakeUnionSet (union3, mg1, loc);
1624                                 else
1625                                         union3 = (MethodGroupExpr) mg1;
1626                         }
1627
1628                         if (target_type.BaseType != null)
1629                                 mg1 = MethodLookup (ec, target_type.BaseType, op_name, loc);
1630
1631                         if (mg1 != null){
1632                                 if (union3 != null)
1633                                         union3 = Invocation.MakeUnionSet (union3, mg1, loc);
1634                                 else
1635                                         union3 = (MethodGroupExpr) mg1;
1636                         }
1637
1638                         MethodGroupExpr union4 = null;
1639
1640                         if (look_for_explicit) {
1641                                 op_name = "op_Explicit";
1642
1643                                 mg5 = MemberLookup (ec, source_type, op_name, loc);
1644                                 if (source_type.BaseType != null)
1645                                         mg6 = MethodLookup (ec, source_type.BaseType, op_name, loc);
1646
1647                                 mg7 = MemberLookup (ec, target_type, op_name, loc);
1648                                 if (target_type.BaseType != null)
1649                                         mg8 = MethodLookup (ec, target_type.BaseType, op_name, loc);
1650
1651                                 MethodGroupExpr union5 = Invocation.MakeUnionSet (mg5, mg6, loc);
1652                                 MethodGroupExpr union6 = Invocation.MakeUnionSet (mg7, mg8, loc);
1653
1654                                 union4 = Invocation.MakeUnionSet (union5, union6, loc);
1655                         }
1656
1657                         return Invocation.MakeUnionSet (union3, union4, loc);
1658                 }
1659
1660                 /// <summary>
1661                 ///   User-defined conversions
1662                 /// </summary>
1663                 static public Expression UserDefinedConversion (EmitContext ec, Expression source,
1664                                                                 Type target, Location loc,
1665                                                                 bool look_for_explicit)
1666                 {
1667                         MethodGroupExpr union;
1668                         Type source_type = source.Type;
1669                         MethodBase method = null;
1670
1671                         union = GetConversionOperators (ec, source_type, target, loc, look_for_explicit);
1672                         if (union == null)
1673                                 return null;
1674
1675                         Type most_specific_source, most_specific_target;
1676
1677 #if BLAH
1678                         foreach (MethodBase m in union.Methods){
1679                                 Console.WriteLine ("Name: " + m.Name);
1680                                 Console.WriteLine ("    : " + ((MethodInfo)m).ReturnType);
1681                         }
1682 #endif
1683
1684                         most_specific_source = FindMostSpecificSource (union, source, look_for_explicit, loc);
1685                         if (most_specific_source == null)
1686                                 return null;
1687
1688                         most_specific_target = FindMostSpecificTarget (union, target, look_for_explicit, loc);
1689                         if (most_specific_target == null)
1690                                 return null;
1691
1692                         int count = 0;
1693
1694                         foreach (MethodBase mb in union.Methods){
1695                                 ParameterData pd = Invocation.GetParameterData (mb);
1696                                 MethodInfo mi = (MethodInfo) mb;
1697
1698                                 if (pd.ParameterType (0) == most_specific_source &&
1699                                     mi.ReturnType == most_specific_target) {
1700                                         method = mb;
1701                                         count++;
1702                                 }
1703                         }
1704
1705                         if (method == null || count > 1)
1706                                 return null;
1707
1708
1709                         //
1710                         // This will do the conversion to the best match that we
1711                         // found.  Now we need to perform an implict standard conversion
1712                         // if the best match was not the type that we were requested
1713                         // by target.
1714                         //
1715                         if (look_for_explicit)
1716                                 source = ConvertExplicitStandard (ec, source, most_specific_source, loc);
1717                         else
1718                                 source = ConvertImplicitStandard (ec, source, most_specific_source, loc);
1719
1720                         if (source == null)
1721                                 return null;
1722
1723                         Expression e;
1724                         e =  new UserCast ((MethodInfo) method, source, loc);
1725                         if (e.Type != target){
1726                                 if (!look_for_explicit)
1727                                         e = ConvertImplicitStandard (ec, e, target, loc);
1728                                 else
1729                                         e = ConvertExplicitStandard (ec, e, target, loc);
1730                         }
1731                         return e;
1732                 }
1733
1734                 /// <summary>
1735                 ///   Converts implicitly the resolved expression 'expr' into the
1736                 ///   'target_type'.  It returns a new expression that can be used
1737                 ///   in a context that expects a 'target_type'.
1738                 /// </summary>
1739                 static public Expression ConvertImplicit (EmitContext ec, Expression expr,
1740                                                           Type target_type, Location loc)
1741                 {
1742                         Type expr_type = expr.Type;
1743                         Expression e;
1744
1745
1746                         if (expr_type == target_type)
1747                                 return expr;
1748
1749                         if (target_type == null)
1750                                 throw new Exception ("Target type is null");
1751
1752                         e = ConvertImplicitStandard (ec, expr, target_type, loc);
1753                         if (e != null)
1754                                 return e;
1755
1756                         e = ImplicitUserConversion (ec, expr, target_type, loc);
1757
1758                         if (e != null)
1759                                 return e;
1760
1761                         e = NarrowingConversion (ec, expr, target_type, loc);
1762                         if (e != null)
1763                                 return e;
1764
1765                         return null;
1766                 }
1767
1768                 /// <summary>
1769                 ///   Converts the resolved expression 'expr' into the
1770                 ///   'target_type' using the Microsoft.VisualBasic runtime.
1771                 ///   It returns a new expression that can be used
1772                 ///   in a context that expects a 'target_type'.
1773                 /// </summary>
1774                 static private Expression RTConversionExpression (EmitContext ec, string s, Expression expr, Location loc)
1775                 {
1776                         Expression etmp, e;
1777                         ArrayList args;
1778                         Argument arg;
1779
1780                         etmp = Mono.MonoBASIC.Parser.DecomposeQI("Microsoft.VisualBasic.CompilerServices." + s, loc);
1781                         args = new ArrayList();
1782                         arg = new Argument (expr, Argument.AType.Expression);
1783                         args.Add (arg);
1784                         e = (Expression) new Invocation (etmp, args, loc);
1785                         e = e.Resolve(ec);
1786                         return (e);
1787                 }
1788
1789                 static private Expression RTConversionExpression (EmitContext ec, string ns, string method, Expression expr, Location loc)
1790                 {
1791                         Expression etmp, e;
1792                         ArrayList args;
1793                         Argument arg;
1794
1795                         etmp = Mono.MonoBASIC.Parser.DecomposeQI(ns+method, loc);
1796                         args = new ArrayList();
1797                         arg = new Argument (expr, Argument.AType.Expression);
1798                         args.Add (arg);
1799                         e = (Expression) new Invocation (etmp, args, loc);
1800                         e = e.Resolve(ec);
1801                         return (e);
1802                 }
1803
1804
1805                 static public bool NarrowingConversionExists (EmitContext ec, Expression expr, Type target_type)
1806                 {
1807                         Type expr_type = expr.Type;
1808
1809                         if (target_type == TypeManager.sbyte_type){
1810                                 //
1811                                 // To sbyte from short, int, long, float, double.
1812                                 //
1813                                 if ((expr_type == TypeManager.int32_type) ||
1814                                     (expr_type == TypeManager.int64_type) ||
1815                                     (expr_type == TypeManager.double_type) ||
1816                                     (expr_type == TypeManager.float_type)  ||
1817                                     (expr_type == TypeManager.short_type) ||
1818                                     (expr_type == TypeManager.decimal_type))
1819                                         return true;
1820
1821                         } else if (target_type == TypeManager.byte_type){
1822                                 //
1823                                 // To byte from short, ushort, int, uint, long, ulong, float, double
1824                                 //
1825                                 if ((expr_type == TypeManager.short_type) ||
1826                                     (expr_type == TypeManager.ushort_type) ||
1827                                     (expr_type == TypeManager.int32_type) ||
1828                                     (expr_type == TypeManager.uint32_type) ||
1829                                     (expr_type == TypeManager.uint64_type) ||
1830                                     (expr_type == TypeManager.int64_type) ||
1831                                     (expr_type == TypeManager.float_type) ||
1832                                     (expr_type == TypeManager.double_type) ||
1833                                     (expr_type == TypeManager.decimal_type))
1834                                         return true;
1835
1836                         } else if (target_type == TypeManager.short_type){
1837                                 //
1838                                 // To short from int, long, float, double
1839                                 //
1840                                 if ((expr_type == TypeManager.int32_type) ||
1841                                     (expr_type == TypeManager.int64_type) ||
1842                                     (expr_type == TypeManager.double_type) ||
1843                                     (expr_type == TypeManager.float_type) ||
1844                                     (expr_type == TypeManager.decimal_type))
1845                                         return true;
1846
1847                         } else if (target_type == TypeManager.ushort_type){
1848                                 //
1849                                 // To ushort from int, uint, long, ulong, float, double
1850                                 //
1851                                 if ((expr_type == TypeManager.uint32_type) ||
1852                                     (expr_type == TypeManager.uint64_type) ||
1853                                     (expr_type == TypeManager.int32_type) ||
1854                                     (expr_type == TypeManager.int64_type) ||
1855                                     (expr_type == TypeManager.double_type) ||
1856                                     (expr_type == TypeManager.float_type) ||
1857                                     (expr_type == TypeManager.decimal_type))
1858                                         return true;
1859
1860                         } else if (target_type == TypeManager.int32_type){
1861                                 //
1862                                 // To int from long, float, double
1863                                 //
1864                                 if ((expr_type == TypeManager.int64_type) ||
1865                                     (expr_type == TypeManager.double_type) ||
1866                                     (expr_type == TypeManager.float_type) ||
1867                                     (expr_type == TypeManager.decimal_type))
1868                                         return true;
1869
1870                         } else if (target_type == TypeManager.uint32_type){
1871                                 //
1872                                 // To uint from long, ulong, float, double
1873                                 //
1874                                 if ((expr_type == TypeManager.int64_type) ||
1875                                     (expr_type == TypeManager.uint64_type) ||
1876                                     (expr_type == TypeManager.double_type) ||
1877                                     (expr_type == TypeManager.float_type) ||
1878                                     (expr_type == TypeManager.decimal_type))
1879                                         return true;
1880
1881                         } else if ((target_type == TypeManager.uint64_type) ||
1882                                    (target_type == TypeManager.int64_type)) {
1883                                 //
1884                                 // To long/ulong from float, double
1885                                 //
1886                                 if ((expr_type == TypeManager.double_type) ||
1887                                     (expr_type == TypeManager.float_type) ||
1888                                     (expr_type == TypeManager.decimal_type))
1889                                         return true;
1890
1891                         } else if (target_type == TypeManager.char_type){
1892                                 //
1893                                 // To char from ushort, int, uint, long, ulong, float, double, decimal,string
1894                                 //
1895                                 if ((expr_type == TypeManager.ushort_type) ||
1896                                     (expr_type == TypeManager.int32_type) ||
1897                                     (expr_type == TypeManager.uint32_type) ||
1898                                     (expr_type == TypeManager.uint64_type) ||
1899                                     (expr_type == TypeManager.int64_type) ||
1900                                     (expr_type == TypeManager.float_type) ||
1901                                     (expr_type == TypeManager.double_type) ||
1902                                     (expr_type == TypeManager.decimal_type) ||
1903                                     (expr_type == TypeManager.string_type))
1904
1905                                         return true;
1906
1907                         } else if (target_type == TypeManager.float_type){
1908                                 //
1909                                 // To float from double
1910                                 //
1911                                 if (expr_type == TypeManager.double_type)
1912                                         return true;
1913                         }
1914
1915                         return (NarrowingConversion (ec, expr, target_type,Location.Null)) != null;
1916                 }
1917
1918                 static public Expression NarrowingConversion (EmitContext ec, Expression expr,
1919                                                                 Type target_type, Location loc)
1920                 {
1921                         Type expr_type = expr.Type;
1922
1923                         if (target_type == TypeManager.sbyte_type){
1924                                 //
1925                                 // To sbyte from short, int, long, float, double.
1926                                 //
1927                                 if (expr_type == TypeManager.int32_type)
1928                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_I1);
1929                                 if (expr_type == TypeManager.int64_type)
1930                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I1);
1931                                 if (expr_type == TypeManager.short_type)
1932                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_I1);
1933
1934                                 if (expr_type == TypeManager.float_type) {
1935                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
1936                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_I1);
1937                                 }
1938                                 if (expr_type == TypeManager.double_type) {
1939                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
1940                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_I1);
1941                                 }
1942
1943                         } else if (target_type == TypeManager.byte_type){
1944                                 //
1945                                 // To byte from short, ushort, int, uint, long, ulong, float, double
1946                                 //
1947                                 if (expr_type == TypeManager.short_type)
1948                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U1);
1949                                 if (expr_type == TypeManager.ushort_type)
1950                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_U1);
1951                                 if (expr_type == TypeManager.int32_type)
1952                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U1);
1953                                 if (expr_type == TypeManager.uint32_type)
1954                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_U1);
1955                                 if (expr_type == TypeManager.uint64_type)
1956                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U1);
1957                                 if (expr_type == TypeManager.int64_type)
1958                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U1);
1959
1960                                 if (expr_type == TypeManager.float_type) {
1961                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
1962                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_U1);
1963                                 }
1964                                 if (expr_type == TypeManager.double_type) {
1965                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
1966                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_U1);
1967                                 }
1968
1969                         } else if (target_type == TypeManager.short_type) {
1970                                 //
1971                                 // To short from int, long, float, double
1972                                 //
1973                                 if (expr_type == TypeManager.int32_type)
1974                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_I2);
1975                                 if (expr_type == TypeManager.int64_type)
1976                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I2);
1977
1978                                 if (expr_type == TypeManager.float_type) {
1979                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
1980                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_I2);
1981                                 }
1982                                 if (expr_type == TypeManager.double_type) {
1983                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
1984                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_I2);
1985                                 }
1986
1987                         } else if (target_type == TypeManager.ushort_type) {
1988                                 //
1989                                 // To ushort from int, uint, long, ulong, float, double
1990                                 //
1991                                 if (expr_type == TypeManager.uint32_type)
1992                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_U2);
1993                                 if (expr_type == TypeManager.uint64_type)
1994                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U2);
1995                                 if (expr_type == TypeManager.int32_type)
1996                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U2);
1997                                 if (expr_type == TypeManager.int64_type)
1998                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U2);
1999
2000                                 if (expr_type == TypeManager.float_type) {
2001                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
2002                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_U2);
2003                                 }
2004
2005                                 if (expr_type == TypeManager.double_type) {
2006                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
2007                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_U2);
2008                                 }
2009
2010                         } else if (target_type == TypeManager.int32_type){
2011                                 //
2012                                 // To int from long, float, double
2013                                 //
2014                                 if (expr_type == TypeManager.int64_type)
2015                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I4);
2016
2017                                 if (expr_type == TypeManager.float_type) {
2018                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
2019                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_I4);
2020                                 }
2021                                 if (expr_type == TypeManager.double_type) {
2022                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
2023                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_I4);
2024                                 }
2025
2026                         } else if (target_type == TypeManager.uint32_type){
2027                                 //
2028                                 // To uint from long, ulong, float, double
2029                                 //
2030                                 if (expr_type == TypeManager.int64_type)
2031                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U4);
2032                                 if (expr_type == TypeManager.uint64_type)
2033                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I4);
2034                                 if (expr_type == TypeManager.float_type) {
2035                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
2036                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_U4);
2037                                 }
2038                                 if (expr_type == TypeManager.double_type) {
2039                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
2040                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_U4);
2041                                 }
2042
2043                         } else if (target_type == TypeManager.uint64_type) {
2044                                 //
2045                                 // To long/ulong from float, double
2046                                 //
2047                                 if (expr_type == TypeManager.float_type) {
2048                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
2049                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_U8);
2050                                 }
2051                                 if (expr_type == TypeManager.double_type) {
2052                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
2053                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_U8);
2054                                 }
2055
2056                         } else if (target_type == TypeManager.int64_type) {
2057                                 //
2058                                 // To long/ulong from float, double
2059                                 //
2060                                 if (expr_type == TypeManager.float_type) {
2061                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
2062                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_I8);
2063                                 }
2064                                 if (expr_type == TypeManager.double_type) {
2065                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
2066                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_I8);
2067                                 }
2068
2069                         } else if (target_type == TypeManager.char_type){
2070                                 //
2071                                 // To char from ushort, int, uint, long, ulong, float, double
2072                                 //
2073                                 if (expr_type == TypeManager.ushort_type)
2074                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_CH);
2075                                 if (expr_type == TypeManager.int32_type)
2076                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_CH);
2077                                 if (expr_type == TypeManager.uint32_type)
2078                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_CH);
2079                                 if (expr_type == TypeManager.uint64_type)
2080                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_CH);
2081                                 if (expr_type == TypeManager.int64_type)
2082                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_CH);
2083
2084                                 if (expr_type == TypeManager.float_type) {
2085                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
2086                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_CH);
2087                                 }
2088                                 if (expr_type == TypeManager.double_type) {
2089                                         Expression rounded_expr = RTConversionExpression(ec, "System.Math", ".Round", expr, loc);
2090                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_CH);
2091                                 }
2092
2093                         } else if (target_type == TypeManager.float_type){
2094                                 //
2095                                 // To float from double
2096                                 //
2097                                 if (expr_type == TypeManager.double_type)
2098                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.R8_R4);
2099                         }
2100
2101                         TypeCode dest_type = Type.GetTypeCode (target_type);
2102                         TypeCode src_type = Type.GetTypeCode (expr_type);
2103                         Expression e = null;
2104
2105                         switch (dest_type) {
2106                                 case TypeCode.String:
2107                                         switch (src_type) {
2108                                                 case TypeCode.SByte:
2109                                                 case TypeCode.Byte:
2110                                                         e = RTConversionExpression(ec, "StringType.FromByte", expr, loc);
2111                                                         break;
2112                                                 case TypeCode.UInt16:
2113                                                 case TypeCode.Int16:
2114                                                         e = RTConversionExpression(ec, "StringType.FromShort", expr, loc);
2115                                                         break;
2116                                                 case TypeCode.UInt32:
2117                                                 case TypeCode.Int32:
2118                                                         e = RTConversionExpression(ec, "StringType.FromInteger", expr, loc);
2119                                                         break;
2120                                                 case TypeCode.UInt64:
2121                                                 case TypeCode.Int64:
2122                                                         e = RTConversionExpression(ec, "StringType.FromLong", expr, loc);
2123                                                         break;
2124                                                 case TypeCode.Char:
2125                                                         e = RTConversionExpression(ec, "StringType.FromChar", expr, loc);
2126                                                         break;
2127                                                 case TypeCode.Single:
2128                                                         e = RTConversionExpression(ec, "StringType.FromSingle", expr, loc);
2129                                                         break;
2130                                                 case TypeCode.Double:
2131                                                         e = RTConversionExpression(ec, "StringType.FromDouble", expr, loc);
2132                                                         break;
2133                                                 case TypeCode.Boolean:
2134                                                         e = RTConversionExpression(ec, "StringType.FromBoolean", expr, loc);
2135                                                         break;
2136                                                 case TypeCode.DateTime:
2137                                                         e = RTConversionExpression(ec, "StringType.FromDate", expr, loc);
2138                                                         break;
2139                                                 case TypeCode.Decimal:
2140                                                         e = RTConversionExpression(ec, "StringType.FromDecimal", expr, loc);
2141                                                         break;
2142                                                 case TypeCode.Object:
2143                                                         e = RTConversionExpression(ec, "StringType.FromObject", expr, loc);
2144                                                         break;
2145                                         }
2146                                         break;
2147
2148                                 case TypeCode.Int32:
2149                                 case TypeCode.UInt32:
2150                                         switch (src_type) {
2151                                                 case TypeCode.String:
2152                                                         e = RTConversionExpression(ec, "IntegerType.FromString", expr, loc);
2153                                                         break;
2154                                                 case TypeCode.Object:
2155                                                         e = RTConversionExpression(ec, "IntegerType.FromObject", expr, loc);
2156                                                         break;
2157                                         }
2158                                         break;
2159
2160                                 case TypeCode.Int16:
2161                                 case TypeCode.UInt16:
2162                                         switch (src_type) {
2163                                                 case TypeCode.String:
2164                                                         e = RTConversionExpression(ec, "ShortType.FromString", expr, loc);
2165                                                         break;
2166                                                 case TypeCode.Object:
2167                                                         e = RTConversionExpression(ec, "ShortType.FromObject", expr, loc);
2168                                                         break;
2169                                         }
2170                                         break;
2171                                 case TypeCode.Byte:
2172                                         // Ok, this *is* broken
2173                                         e = RTConversionExpression(ec, "ByteType.FromObject", expr, loc);
2174                                         break;
2175                                 case TypeCode.DateTime:
2176                                         switch (src_type) {
2177                                                 case TypeCode.String:
2178                                                         e = RTConversionExpression(ec, "DateType.FromString", expr, loc);
2179                                                         break;
2180                                                 case TypeCode.Object:
2181                                                         e = RTConversionExpression(ec, "DateType.FromObject", expr, loc);
2182                                                         break;
2183                                         }
2184                                         break;
2185                                 case TypeCode.Char:
2186                                         switch (src_type) {
2187
2188                                                 case TypeCode.String:
2189                                                         e = RTConversionExpression(ec, "CharType.FromString", expr, loc);
2190                                                         break;
2191
2192                                 }
2193                                 break;
2194                         }
2195
2196                         // We must examine separately some types that
2197                         // don't have a TypeCode but are supported
2198                         // in the runtime
2199                         if (expr_type == typeof(System.String) && target_type == typeof (System.Char[])) {
2200                                 e = RTConversionExpression(ec, "CharArrayType.FromString", expr, loc);
2201                         }
2202                         if (e != null)
2203                                 return e;
2204                         // VB.NET Objects can be converted to anything by default
2205                         // unless, that is, an exception at runtime blows it all
2206                         if (src_type == TypeCode.Object) {
2207                                 Expression cast_type = Mono.MonoBASIC.Parser.DecomposeQI(target_type.ToString(), loc);
2208                                 Cast ce = new Cast (cast_type, expr, loc);
2209                                 ce.IsRuntimeCast = true;
2210                                 return ce.Resolve (ec);
2211                         }
2212                       return null;
2213                 }
2214
2215                 static public Expression ConvertNothingToDefaultValues (EmitContext ec, Expression expr,
2216                                                                         Type target_type, Location loc)
2217                 {
2218                         switch (Type.GetTypeCode (target_type)) {
2219                         case TypeCode.Boolean  :
2220                                 return new BoolConstant (false);
2221                         case TypeCode.Byte  :
2222                                 return new ByteConstant (0);
2223                         case TypeCode.Char  :
2224                                 return new CharConstant ((char)0);
2225                         case TypeCode.SByte :
2226                                 return new SByteConstant (0);
2227                         case TypeCode.Int16 :
2228                                 return new ShortConstant (0);
2229                         case TypeCode.Int32 :
2230                                 return new IntConstant (0);
2231                         case TypeCode.Int64 :
2232                                 return new LongConstant (0);
2233                         case TypeCode.Decimal :
2234                                 return new DecimalConstant (System.Decimal.Zero);
2235                         case TypeCode.Single :
2236                                 return new FloatConstant (0.0F);
2237                         case TypeCode.Double :
2238                                 return new DoubleConstant (0.0);
2239                         }
2240
2241                         return null;
2242                 }
2243
2244                 /// <summary>
2245                 ///   Attempts to apply the 'Standard Implicit
2246                 ///   Conversion' rules to the expression 'expr' into
2247                 ///   the 'target_type'.  It returns a new expression
2248                 ///   that can be used in a context that expects a
2249                 ///   'target_type'.
2250                 ///
2251                 ///   This is different from 'ConvertImplicit' in that the
2252                 ///   user defined implicit conversions are excluded.
2253                 /// </summary>
2254                 static public Expression ConvertImplicitStandard (EmitContext ec, Expression expr,
2255                                                                   Type target_type, Location loc)
2256                 {
2257                         Type expr_type = expr.Type;
2258                         Expression e;
2259
2260                         if (expr is NullLiteral) {
2261                                 if (target_type == TypeManager.string_type)
2262                                         return expr;
2263                                 e = ConvertNothingToDefaultValues (ec, expr, target_type, loc);
2264                                 if (e != null)
2265                                         return e;
2266                         }
2267
2268                         if (expr_type == target_type)
2269                                 return expr;
2270
2271                         e = ImplicitNumericConversion (ec, expr, target_type, loc);
2272
2273                         if (e != null)
2274                                 return e;
2275
2276                         e = ImplicitReferenceConversion (expr, target_type);
2277                         if (e != null)
2278                                 return e;
2279
2280                         if (expr.Type.IsSubclassOf (TypeManager.enum_type)) {
2281                                 expr_type = TypeManager.EnumToUnderlying (expr.Type);
2282                                 expr = new EmptyCast (expr, expr_type);
2283                                 if (expr_type == target_type)
2284                                         return expr;
2285                                 e = ImplicitNumericConversion (ec, expr, target_type, loc);
2286                                 if (e != null)
2287                                         return e;
2288                         }
2289
2290                         if (ec.InUnsafe) {
2291                                 if (expr_type.IsPointer){
2292                                         if (target_type == TypeManager.void_ptr_type)
2293                                                 return new EmptyCast (expr, target_type);
2294
2295                                         //
2296                                         // yep, comparing pointer types cant be done with
2297                                         // t1 == t2, we have to compare their element types.
2298                                         //
2299                                         if (target_type.IsPointer){
2300                                                 if (target_type.GetElementType()==expr_type.GetElementType())
2301                                                         return expr;
2302                                         }
2303                                 }
2304
2305                                 if (target_type.IsPointer){
2306                                         if (expr is NullLiteral)
2307                                                 return new EmptyCast (expr, target_type);
2308                                 }
2309                         }
2310
2311                         return null;
2312                 }
2313
2314                 /// <summary>
2315                 ///   Attemps to perform an implict constant conversion of the any Numeric Constant
2316                 ///   into a different data type using casts (See Implicit Constant
2317                 ///   Expression Conversions)
2318                 /// </summary>
2319                 static protected Expression TryImplicitNumericConversion (Type target_type, Constant ic)
2320                 {
2321                         double value = 0;
2322                         if (ic is BoolConstant) {
2323                                 bool val = (bool) ((BoolConstant)ic).Value;
2324                                 if (val) {
2325                                         if (target_type == TypeManager.byte_type)
2326                                                 value = Byte.MaxValue;
2327                                         else
2328                                                 value = -1;
2329                                 }
2330                         }
2331                         if (ic is IntConstant)
2332                                 value = (double)((IntConstant)ic).Value;
2333
2334                         if (ic is LongConstant)
2335                                 value = (double) ((LongConstant)ic).Value;
2336
2337                         if (ic is FloatConstant) {
2338                                 value = (double) ((FloatConstant)ic).Value;
2339                         }
2340
2341                         if (ic is DoubleConstant) {
2342                                 value = ((DoubleConstant)ic).Value;
2343                         }
2344
2345                         //
2346                         // FIXME: This could return constants instead of EmptyCasts
2347                         //
2348                         if (target_type == TypeManager.bool_type){
2349                                 if (value != 0)
2350                                         return new BoolConstant (true);
2351                                 return new BoolConstant (false);
2352                         } else if (target_type == TypeManager.sbyte_type){
2353                                 if (value >= SByte.MinValue && value <= SByte.MaxValue)
2354                                         return new SByteConstant ((sbyte) System.Math.Round (value));
2355                         } else if (target_type == TypeManager.byte_type){
2356                                 if (value >= Byte.MinValue && value <= Byte.MaxValue)
2357                                         return new ByteConstant ((byte) System.Math.Round (value));
2358                         } else if (target_type == TypeManager.short_type){
2359                                 if (value >= Int16.MinValue && value <= Int16.MaxValue)
2360                                         return new ShortConstant ((short) System.Math.Round (value));
2361                         } else if (target_type == TypeManager.ushort_type){
2362                                 if (value >= UInt16.MinValue && value <= UInt16.MaxValue)
2363                                         return new UShortConstant ((ushort) System.Math.Round (value));
2364                         } else if (target_type == TypeManager.int32_type){
2365                                 if (value >= Int32.MinValue && value <= Int32.MaxValue)
2366                                         return new IntConstant ((int) System.Math.Round (value));
2367                         } else if (target_type == TypeManager.uint32_type){
2368                                 if (value >= 0)
2369                                         return new UIntConstant ((uint) System.Math.Round (value));
2370                         } else if (target_type == TypeManager.int64_type){
2371                                         return new LongConstant ((long) System.Math.Round (value));
2372                         } else if (target_type == TypeManager.uint64_type){
2373                                 //
2374                                 // we can optimize this case: a positive int32
2375                                 // always fits on a uint64.  But we need an opcode
2376                                 // to do it.
2377                                 //
2378                                 if (value >= 0)
2379                                         return new ULongConstant ((ulong)System.Math.Round ( value));
2380                         } else if (target_type == TypeManager.float_type){
2381                                         return new FloatConstant ((float) value);
2382                         } else if (target_type == TypeManager.double_type){
2383                                         return new DoubleConstant ((double) value);
2384                         }
2385
2386                         if (value == 0 && ic is IntLiteral && TypeManager.IsEnumType (target_type)){
2387                                 Type underlying = TypeManager.EnumToUnderlying (target_type);
2388                                 Constant e = (Constant) ic;
2389
2390                                 //
2391                                 // Possibly, we need to create a different 0 literal before passing
2392                                 // to EnumConstant
2393                                 //n
2394                                 if (underlying == TypeManager.int64_type)
2395                                         e = new LongLiteral (0);
2396                                 else if (underlying == TypeManager.uint64_type)
2397                                         e = new ULongLiteral (0);
2398
2399                                 return new EnumConstant (e, target_type);
2400                         }
2401                         return null;
2402                 }
2403
2404                 static public void Error_CannotConvertImplicit (Location loc, Type source, Type target)
2405                 {
2406                         string msg = "Cannot convert implicitly from '"+
2407                                 TypeManager.MonoBASIC_Name (source) + "' to '" +
2408                                 TypeManager.MonoBASIC_Name (target) + "'";
2409
2410                         throw new Exception (msg);
2411
2412                         // Report.Error (30512, loc, msg);
2413                 }
2414
2415                 /// <summary>
2416                 ///   Attemptes to implicityly convert 'target' into 'type', using
2417                 ///   ConvertImplicit.  If there is no implicit conversion, then
2418                 ///   an error is signaled
2419                 /// </summary>
2420                 static public Expression ConvertImplicitRequired (EmitContext ec, Expression source,
2421                                                                   Type target_type, Location loc)
2422                 {
2423                         Expression e;
2424
2425                         e = ConvertImplicit (ec, source, target_type, loc);
2426
2427                         if (e != null)
2428                                 return e;
2429
2430
2431                         if (source is DoubleLiteral && target_type == TypeManager.float_type){
2432                                 Report.Error (664, loc,
2433                                               "Double literal cannot be implicitly converted to " +
2434                                               "float type, use F suffix to create a float literal");
2435                         }
2436
2437                         Error_CannotConvertImplicit (loc, source.Type, target_type);
2438
2439                         return null;
2440                 }
2441
2442                 /// <summary>
2443                 ///   Performs the explicit numeric conversions
2444                 /// </summary>
2445                 static Expression ConvertNumericExplicit (EmitContext ec, Expression expr, Type target_type, Location loc)
2446                 {
2447                         Type expr_type = expr.Type;
2448
2449                         //
2450                         // If we have an enumeration, extract the underlying type,
2451                         // use this during the comparison, but wrap around the original
2452                         // target_type
2453                         //
2454                         Type real_target_type = target_type;
2455
2456                         if (TypeManager.IsEnumType (real_target_type))
2457                                 real_target_type = TypeManager.EnumToUnderlying (real_target_type);
2458
2459                         if (StandardConversionExists (expr, real_target_type)){
2460                                 Expression ce = ConvertImplicitStandard (ec, expr, real_target_type, loc);
2461
2462                                 if (real_target_type != target_type)
2463                                         return new EmptyCast (ce, target_type);
2464                                 return ce;
2465                         }
2466
2467                         if (expr_type == TypeManager.sbyte_type){
2468                                 //
2469                                 // From sbyte to byte, ushort, uint, ulong, char
2470                                 //
2471                                 if (real_target_type == TypeManager.byte_type)
2472                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U1);
2473                                 if (real_target_type == TypeManager.ushort_type)
2474                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U2);
2475                                 if (real_target_type == TypeManager.uint32_type)
2476                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U4);
2477                                 if (real_target_type == TypeManager.uint64_type)
2478                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_U8);
2479                                 if (real_target_type == TypeManager.char_type)
2480                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I1_CH);
2481                         } else if (expr_type == TypeManager.byte_type){
2482                                 //
2483                                 // From byte to sbyte and char
2484                                 //
2485                                 if (real_target_type == TypeManager.sbyte_type)
2486                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U1_I1);
2487                                 if (real_target_type == TypeManager.char_type)
2488                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U1_CH);
2489                         } else if (expr_type == TypeManager.short_type){
2490                                 //
2491                                 // From short to sbyte, byte, ushort, uint, ulong, char
2492                                 //
2493                                 if (real_target_type == TypeManager.sbyte_type)
2494                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_I1);
2495                                 if (real_target_type == TypeManager.byte_type)
2496                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U1);
2497                                 if (real_target_type == TypeManager.ushort_type)
2498                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U2);
2499                                 if (real_target_type == TypeManager.uint32_type)
2500                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U4);
2501                                 if (real_target_type == TypeManager.uint64_type)
2502                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_U8);
2503                                 if (real_target_type == TypeManager.char_type)
2504                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I2_CH);
2505                         } else if (expr_type == TypeManager.ushort_type){
2506                                 //
2507                                 // From ushort to sbyte, byte, short, char
2508                                 //
2509                                 if (real_target_type == TypeManager.sbyte_type)
2510                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_I1);
2511                                 if (real_target_type == TypeManager.byte_type)
2512                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_U1);
2513                                 if (real_target_type == TypeManager.short_type)
2514                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_I2);
2515                                 if (real_target_type == TypeManager.char_type)
2516                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U2_CH);
2517                         } else if (expr_type == TypeManager.int32_type){
2518                                 //
2519                                 // From int to sbyte, byte, short, ushort, uint, ulong, char
2520                                 //
2521                                 if (real_target_type == TypeManager.sbyte_type)
2522                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_I1);
2523                                 if (real_target_type == TypeManager.byte_type)
2524                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U1);
2525                                 if (real_target_type == TypeManager.short_type)
2526                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_I2);
2527                                 if (real_target_type == TypeManager.ushort_type)
2528                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U2);
2529                                 if (real_target_type == TypeManager.uint32_type)
2530                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U4);
2531                                 if (real_target_type == TypeManager.uint64_type)
2532                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_U8);
2533                                 if (real_target_type == TypeManager.char_type)
2534                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I4_CH);
2535                         } else if (expr_type == TypeManager.uint32_type){
2536                                 //
2537                                 // From uint to sbyte, byte, short, ushort, int, char
2538                                 //
2539                                 if (real_target_type == TypeManager.sbyte_type)
2540                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_I1);
2541                                 if (real_target_type == TypeManager.byte_type)
2542                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_U1);
2543                                 if (real_target_type == TypeManager.short_type)
2544                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_I2);
2545                                 if (real_target_type == TypeManager.ushort_type)
2546                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_U2);
2547                                 if (real_target_type == TypeManager.int32_type)
2548                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_I4);
2549                                 if (real_target_type == TypeManager.char_type)
2550                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U4_CH);
2551                         } else if (expr_type == TypeManager.int64_type){
2552                                 //
2553                                 // From long to sbyte, byte, short, ushort, int, uint, ulong, char
2554                                 //
2555                                 if (real_target_type == TypeManager.sbyte_type)
2556                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I1);
2557                                 if (real_target_type == TypeManager.byte_type)
2558                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U1);
2559                                 if (real_target_type == TypeManager.short_type)
2560                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I2);
2561                                 if (real_target_type == TypeManager.ushort_type)
2562                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U2);
2563                                 if (real_target_type == TypeManager.int32_type)
2564                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_I4);
2565                                 if (real_target_type == TypeManager.uint32_type)
2566                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U4);
2567                                 if (real_target_type == TypeManager.uint64_type)
2568                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_U8);
2569                                 if (real_target_type == TypeManager.char_type)
2570                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.I8_CH);
2571                         } else if (expr_type == TypeManager.uint64_type){
2572                                 //
2573                                 // From ulong to sbyte, byte, short, ushort, int, uint, long, char
2574                                 //
2575                                 if (real_target_type == TypeManager.sbyte_type)
2576                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I1);
2577                                 if (real_target_type == TypeManager.byte_type)
2578                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U1);
2579                                 if (real_target_type == TypeManager.short_type)
2580                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I2);
2581                                 if (real_target_type == TypeManager.ushort_type)
2582                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U2);
2583                                 if (real_target_type == TypeManager.int32_type)
2584                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I4);
2585                                 if (real_target_type == TypeManager.uint32_type)
2586                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_U4);
2587                                 if (real_target_type == TypeManager.int64_type)
2588                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_I8);
2589                                 if (real_target_type == TypeManager.char_type)
2590                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.U8_CH);
2591                         } else if (expr_type == TypeManager.char_type){
2592                                 //
2593                                 // From char to sbyte, byte, short
2594                                 //
2595                                 if (real_target_type == TypeManager.sbyte_type)
2596                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.CH_I1);
2597                                 if (real_target_type == TypeManager.byte_type)
2598                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.CH_U1);
2599                                 if (real_target_type == TypeManager.short_type)
2600                                         return new ConvCast (ec, expr, target_type, ConvCast.Mode.CH_I2);
2601                         } else if (expr_type == TypeManager.float_type){
2602                                 //
2603                                 // From float to sbyte, byte, short,
2604                                 // ushort, int, uint, long, ulong, char
2605                                 // or decimal
2606                                 //
2607                                 Expression rounded_expr = RTConversionExpression(ec, "System.Math",".Round" , expr, loc);
2608                                 if (real_target_type == TypeManager.sbyte_type)
2609                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_I1);
2610                                 if (real_target_type == TypeManager.byte_type)
2611                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_U1);
2612                                 if (real_target_type == TypeManager.short_type)
2613                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_I2);
2614                                 if (real_target_type == TypeManager.ushort_type)
2615                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_U2);
2616                                 if (real_target_type == TypeManager.int32_type)
2617                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_I4);
2618                                 if (real_target_type == TypeManager.uint32_type)
2619                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_U4);
2620                                 if (real_target_type == TypeManager.int64_type)
2621                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_I8);
2622                                 if (real_target_type == TypeManager.uint64_type)
2623                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_U8);
2624                                 if (real_target_type == TypeManager.char_type)
2625                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R4_CH);
2626                         } else if (expr_type == TypeManager.double_type){
2627                                 //
2628                                 // From double to byte, byte, short,
2629                                 // ushort, int, uint, long, ulong,
2630                                 // char, float or decimal
2631                                 //
2632                                 Expression rounded_expr = RTConversionExpression(ec, "System.Math",".Round" , expr, loc);
2633                                 if (real_target_type == TypeManager.sbyte_type)
2634                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_I1);
2635                                 if (real_target_type == TypeManager.byte_type)
2636                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_U1);
2637                                 if (real_target_type == TypeManager.short_type)
2638                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_I2);
2639                                 if (real_target_type == TypeManager.ushort_type)
2640                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_U2);
2641                                 if (real_target_type == TypeManager.int32_type)
2642                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_I4);
2643                                 if (real_target_type == TypeManager.uint32_type)
2644                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_U4);
2645                                 if (real_target_type == TypeManager.int64_type)
2646                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_I8);
2647                                 if (real_target_type == TypeManager.uint64_type)
2648                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_U8);
2649                                 if (real_target_type == TypeManager.char_type)
2650                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_CH);
2651                                 if (real_target_type == TypeManager.float_type)
2652                                         return new ConvCast (ec, rounded_expr, target_type, ConvCast.Mode.R8_R4);
2653                         }
2654
2655                         // decimal is taken care of by the op_Explicit methods.
2656
2657                         return null;
2658                 }
2659
2660                 /// <summary>
2661                 ///  Returns whether an explicit reference conversion can be performed
2662                 ///  from source_type to target_type
2663                 /// </summary>
2664                 public static bool ExplicitReferenceConversionExists (Type source_type, Type target_type)
2665                 {
2666                         bool target_is_value_type = target_type.IsValueType;
2667
2668                         if (source_type == target_type)
2669                                 return true;
2670
2671                         //
2672                         // From object to any reference type
2673                         //
2674                         if (source_type == TypeManager.object_type && !target_is_value_type)
2675                                 return true;
2676
2677                         //
2678                         // From any class S to any class-type T, provided S is a base class of T
2679                         //
2680                         if (target_type.IsSubclassOf (source_type))
2681                                 return true;
2682
2683                         //
2684                         // From any interface type S to any interface T provided S is not derived from T
2685                         //
2686                         if (source_type.IsInterface && target_type.IsInterface){
2687                                 if (!target_type.IsSubclassOf (source_type))
2688                                         return true;
2689                         }
2690
2691                         //
2692                         // From any class type S to any interface T, provided S is not sealed
2693                         // and provided S does not implement T.
2694                         //
2695                         if (target_type.IsInterface && !source_type.IsSealed &&
2696                             !TypeManager.ImplementsInterface (source_type, target_type))
2697                                 return true;
2698
2699                         //
2700                         // From any interface-type S to to any class type T, provided T is not
2701                         // sealed, or provided T implements S.
2702                         //
2703                         if (source_type.IsInterface &&
2704                             (!target_type.IsSealed || TypeManager.ImplementsInterface (target_type, source_type)))
2705                                 return true;
2706
2707
2708                         // From an array type S with an element type Se to an array type T with an
2709                         // element type Te provided all the following are true:
2710                         //     * S and T differe only in element type, in other words, S and T
2711                         //       have the same number of dimensions.
2712                         //     * Both Se and Te are reference types
2713                         //     * An explicit referenc conversions exist from Se to Te
2714                         //
2715                         if (source_type.IsArray && target_type.IsArray) {
2716                                 if (source_type.GetArrayRank () == target_type.GetArrayRank ()) {
2717
2718                                         Type source_element_type = source_type.GetElementType ();
2719                                         Type target_element_type = target_type.GetElementType ();
2720
2721                                         if (!source_element_type.IsValueType && !target_element_type.IsValueType)
2722                                                 if (ExplicitReferenceConversionExists (source_element_type,
2723                                                                                        target_element_type))
2724                                                         return true;
2725                                 }
2726                         }
2727
2728
2729                         // From System.Array to any array-type
2730                         if (source_type == TypeManager.array_type &&
2731                             target_type.IsArray){
2732                                 return true;
2733                         }
2734
2735                         //
2736                         // From System delegate to any delegate-type
2737                         //
2738                         if (source_type == TypeManager.delegate_type &&
2739                             target_type.IsSubclassOf (TypeManager.delegate_type))
2740                                 return true;
2741
2742                         //
2743                         // From ICloneable to Array or Delegate types
2744                         //
2745                         if (source_type == TypeManager.icloneable_type &&
2746                             (target_type == TypeManager.array_type ||
2747                              target_type == TypeManager.delegate_type))
2748                                 return true;
2749
2750                         return false;
2751                 }
2752
2753                 /// <summary>
2754                 ///   Implements Explicit Reference conversions
2755                 /// </summary>
2756                 static Expression ConvertReferenceExplicit (Expression source, Type target_type)
2757                 {
2758                         Type source_type = source.Type;
2759                         bool target_is_value_type = target_type.IsValueType;
2760
2761                         //
2762                         // From object to any reference type
2763                         //
2764                         if (source_type == TypeManager.object_type && !target_is_value_type)
2765                                 return new ClassCast (source, target_type);
2766
2767
2768                         //
2769                         // From any class S to any class-type T, provided S is a base class of T
2770                         //
2771                         if (target_type.IsSubclassOf (source_type))
2772                                 return new ClassCast (source, target_type);
2773
2774                         //
2775                         // From any interface type S to any interface T provided S is not derived from T
2776                         //
2777                         if (source_type.IsInterface && target_type.IsInterface){
2778                                 if (TypeManager.ImplementsInterface (source_type, target_type))
2779                                         return null;
2780                                 else
2781                                         return new ClassCast (source, target_type);
2782                         }
2783
2784                         //
2785                         // From any class type S to any interface T, provides S is not sealed
2786                         // and provided S does not implement T.
2787                         //
2788                         if (target_type.IsInterface && !source_type.IsSealed) {
2789                                 if (TypeManager.ImplementsInterface (source_type, target_type))
2790                                         return null;
2791                                 else
2792                                         return new ClassCast (source, target_type);
2793
2794                         }
2795
2796                         //
2797                         // From any interface-type S to to any class type T, provided T is not
2798                         // sealed, or provided T implements S.
2799                         //
2800                         if (source_type.IsInterface) {
2801                                 if (!target_type.IsSealed || TypeManager.ImplementsInterface (target_type, source_type))
2802                                         return new ClassCast (source, target_type);
2803                                 else
2804                                         return null;
2805                         }
2806
2807                         // From an array type S with an element type Se to an array type T with an
2808                         // element type Te provided all the following are true:
2809                         //     * S and T differe only in element type, in other words, S and T
2810                         //       have the same number of dimensions.
2811                         //     * Both Se and Te are reference types
2812                         //     * An explicit referenc conversions exist from Se to Te
2813                         //
2814                         if (source_type.IsArray && target_type.IsArray) {
2815                                 if (source_type.GetArrayRank () == target_type.GetArrayRank ()) {
2816
2817                                         Type source_element_type = source_type.GetElementType ();
2818                                         Type target_element_type = target_type.GetElementType ();
2819
2820                                         if (!source_element_type.IsValueType && !target_element_type.IsValueType)
2821                                                 if (ExplicitReferenceConversionExists (source_element_type,
2822                                                                                        target_element_type))
2823                                                         return new ClassCast (source, target_type);
2824                                 }
2825                         }
2826
2827
2828                         // From System.Array to any array-type
2829                         if (source_type == TypeManager.array_type &&
2830                             target_type.IsArray) {
2831                                 return new ClassCast (source, target_type);
2832                         }
2833
2834                         //
2835                         // From System delegate to any delegate-type
2836                         //
2837                         if (source_type == TypeManager.delegate_type &&
2838                             target_type.IsSubclassOf (TypeManager.delegate_type))
2839                                 return new ClassCast (source, target_type);
2840
2841                         //
2842                         // From ICloneable to Array or Delegate types
2843                         //
2844                         if (source_type == TypeManager.icloneable_type &&
2845                             (target_type == TypeManager.array_type ||
2846                              target_type == TypeManager.delegate_type))
2847                                 return new ClassCast (source, target_type);
2848
2849                         return null;
2850                 }
2851
2852                 /// <summary>
2853                 ///   Performs an explicit conversion of the expression 'expr' whose
2854                 ///   type is expr.Type to 'target_type'.
2855                 /// </summary>
2856                 static public Expression ConvertExplicit (EmitContext ec, Expression expr,
2857                                                           Type target_type, bool runtimeconv, Location loc)
2858                 {
2859                         Type expr_type = expr.Type;
2860                         Expression ne = ConvertImplicitStandard (ec, expr, target_type, loc);
2861
2862                         if (ne != null)
2863                                 return ne;
2864
2865                         ne = ConvertNumericExplicit (ec, expr, target_type, loc);
2866                         if (ne != null)
2867                                 return ne;
2868
2869                         //
2870                         // Unboxing conversion.
2871                         //
2872                         if (expr_type == TypeManager.object_type && target_type.IsValueType)
2873                                 return new UnboxCast (expr, target_type);
2874
2875                         //
2876                         // Enum types
2877                         //
2878                         if (expr_type.IsSubclassOf (TypeManager.enum_type)) {
2879                                 Expression e;
2880
2881                                 //
2882                                 // FIXME: Is there any reason we should have EnumConstant
2883                                 // dealt with here instead of just using always the
2884                                 // UnderlyingSystemType to wrap the type?
2885                                 //
2886                                 if (expr is EnumConstant)
2887                                         e = ((EnumConstant) expr).Child;
2888                                 else {
2889                                         e = new EmptyCast (expr, TypeManager.EnumToUnderlying (expr_type));
2890                                 }
2891
2892                                 Expression t = ConvertImplicit (ec, e, target_type, loc);
2893                                 if (t != null)
2894                                         return t;
2895
2896                                 t = ConvertNumericExplicit (ec, e, target_type, loc);
2897                                 if (t != null)
2898                                         return t;
2899
2900                                 t = NarrowingConversion (ec, e, target_type, loc);
2901                                 if (t != null)
2902                                         return t;
2903
2904                                 Error_CannotConvertType (loc, expr_type, target_type);
2905                                 return null;
2906                         }
2907
2908                         ne = ConvertReferenceExplicit (expr, target_type);
2909                         if (ne != null)
2910                                 return ne;
2911
2912                         if (ec.InUnsafe){
2913                                 if (target_type.IsPointer){
2914                                         if (expr_type.IsPointer)
2915                                                 return new EmptyCast (expr, target_type);
2916
2917                                         if (expr_type == TypeManager.sbyte_type ||
2918                                             expr_type == TypeManager.byte_type ||
2919                                             expr_type == TypeManager.short_type ||
2920                                             expr_type == TypeManager.ushort_type ||
2921                                             expr_type == TypeManager.int32_type ||
2922                                             expr_type == TypeManager.uint32_type ||
2923                                             expr_type == TypeManager.uint64_type ||
2924                                             expr_type == TypeManager.int64_type)
2925                                                 return new OpcodeCast (expr, target_type, OpCodes.Conv_U);
2926                                 }
2927                                 if (expr_type.IsPointer){
2928                                         if (target_type == TypeManager.sbyte_type ||
2929                                             target_type == TypeManager.byte_type ||
2930                                             target_type == TypeManager.short_type ||
2931                                             target_type == TypeManager.ushort_type ||
2932                                             target_type == TypeManager.int32_type ||
2933                                             target_type == TypeManager.uint32_type ||
2934                                             target_type == TypeManager.uint64_type ||
2935                                             target_type == TypeManager.int64_type){
2936                                                 Expression e = new EmptyCast (expr, TypeManager.uint32_type);
2937                                                 Expression ci, ce;
2938
2939                                                 ci = ConvertImplicitStandard (ec, e, target_type, loc);
2940
2941                                                 if (ci != null)
2942                                                         return ci;
2943
2944                                                 ce = ConvertNumericExplicit (ec, e, target_type, loc);
2945                                                 if (ce != null)
2946                                                         return ce;
2947                                                 //
2948                                                 // We should always be able to go from an uint32
2949                                                 // implicitly or explicitly to the other integral
2950                                                 // types
2951                                                 //
2952                                                 throw new Exception ("Internal compiler error");
2953                                         }
2954                                 }
2955                         }
2956
2957                         ne = ExplicitUserConversion (ec, expr, target_type, loc);
2958                         if (ne != null)
2959                                 return ne;
2960
2961                         if (!(runtimeconv))     {
2962                                 ne = NarrowingConversion (ec, expr, target_type, loc);
2963                                 if (ne != null)
2964                                         return ne;
2965
2966                                 Error_CannotConvertType (loc, expr_type, target_type);
2967                         }
2968                         return null;
2969                 }
2970
2971                 /// <summary>
2972                 ///   Same as ConvertExplicit, only it doesn't include user defined conversions
2973                 /// </summary>
2974                 static public Expression ConvertExplicitStandard (EmitContext ec, Expression expr,
2975                                                                   Type target_type, Location l)
2976                 {
2977                         Expression ne = ConvertImplicitStandard (ec, expr, target_type, l);
2978
2979                         if (ne != null)
2980                                 return ne;
2981
2982                         ne = ConvertNumericExplicit (ec, expr, target_type, l);
2983                         if (ne != null)
2984                                 return ne;
2985
2986                         ne = ConvertReferenceExplicit (expr, target_type);
2987                         if (ne != null)
2988                                 return ne;
2989
2990                         ne = NarrowingConversion (ec, expr, target_type, l);
2991                         if (ne != null)
2992                                 return ne;
2993
2994                         Error_CannotConvertType (l, expr.Type, target_type);
2995                         return null;
2996                 }
2997
2998                 static string ExprClassName (ExprClass c)
2999                 {
3000                         switch (c){
3001                         case ExprClass.Invalid:
3002                                 return "Invalid";
3003                         case ExprClass.Value:
3004                                 return "value";
3005                         case ExprClass.Variable:
3006                                 return "variable";
3007                         case ExprClass.Namespace:
3008                                 return "namespace";
3009                         case ExprClass.Type:
3010                                 return "type";
3011                         case ExprClass.MethodGroup:
3012                                 return "method group";
3013                         case ExprClass.PropertyAccess:
3014                                 return "property access";
3015                         case ExprClass.EventAccess:
3016                                 return "event access";
3017                         case ExprClass.IndexerAccess:
3018                                 return "indexer access";
3019                         case ExprClass.Nothing:
3020                                 return "null";
3021                         }
3022                         throw new Exception ("Should not happen");
3023                 }
3024
3025                 /// <summary>
3026                 ///   Reports that we were expecting 'expr' to be of class 'expected'
3027                 /// </summary>
3028                 public void Error118 (string expected)
3029                 {
3030                         string kind = "Unknown";
3031
3032                         kind = ExprClassName (eclass);
3033
3034                         Error (118, "Expression denotes a '" + kind +
3035                                "' where a '" + expected + "' was expected");
3036                 }
3037
3038                 public void Error118 (ResolveFlags flags)
3039                 {
3040                         ArrayList valid = new ArrayList (10);
3041
3042                         if ((flags & ResolveFlags.VariableOrValue) != 0) {
3043                                 valid.Add ("variable");
3044                                 valid.Add ("value");
3045                         }
3046
3047                         if ((flags & ResolveFlags.Type) != 0)
3048                                 valid.Add ("type");
3049
3050                         if ((flags & ResolveFlags.MethodGroup) != 0)
3051                                 valid.Add ("method group");
3052
3053                         if ((flags & ResolveFlags.SimpleName) != 0)
3054                                 valid.Add ("simple name");
3055
3056                         if (valid.Count == 0)
3057                                 valid.Add ("unknown");
3058
3059                         StringBuilder sb = new StringBuilder ();
3060                         for (int i = 0; i < valid.Count; i++) {
3061                                 if (i > 0)
3062                                         sb.Append (", ");
3063                                 else if (i == valid.Count)
3064                                         sb.Append (" or ");
3065                                 sb.Append (valid [i]);
3066                         }
3067
3068                         string kind = ExprClassName (eclass);
3069
3070                         Error (119, "Expression denotes a '" + kind + "' where " +
3071                                "a '" + sb.ToString () + "' was expected");
3072                 }
3073
3074                 static void Error_ConstantValueCannotBeConverted (Location l, string val, Type t)
3075                 {
3076                         Report.Error (31, l, "Constant value '" + val + "' cannot be converted to " +
3077                                       TypeManager.MonoBASIC_Name (t));
3078                 }
3079
3080                 public static void UnsafeError (Location loc)
3081                 {
3082                         Report.Error (214, loc, "Pointers may only be used in an unsafe context");
3083                 }
3084
3085                 /// <summary>
3086                 ///   Converts the IntConstant, UIntConstant, LongConstant or
3087                 ///   ULongConstant,Double into the integral target_type.   Notice
3088                 ///   that we do not return an 'Expression' we do return
3089                 ///   a boxed integral type.
3090                 ///
3091                 ///   FIXME: Since I added the new constants, we need to
3092                 ///   also support conversions from CharConstant, ByteConstant,
3093                 ///   SByteConstant, UShortConstant, ShortConstant
3094                 ///
3095                 ///   This is used by the switch statement, so the domain
3096                 ///   of work is restricted to the literals above, and the
3097                 ///   targets are int32, uint32, char, byte, sbyte, ushort,
3098                 ///   short, uint64 and int64
3099                 /// </summary>
3100                 public static object ConvertIntLiteral (Constant c, Type target_type, Location loc)
3101                 {
3102                         string s = "";
3103
3104                         if (c.Type == target_type)
3105                                 return ((Constant) c).GetValue ();
3106
3107                         //
3108                         // Make into one of the literals we handle, we dont really care
3109                         // about this value as we will just return a few limited types
3110                         //
3111                         if (c is EnumConstant)
3112                                 c = ((EnumConstant)c).WidenToCompilerConstant ();
3113
3114                         if (c is IntConstant){
3115                                 int v = ((IntConstant) c).Value;
3116
3117                                 if (target_type == TypeManager.uint32_type){
3118                                         if (v >= 0)
3119                                                 return (uint) v;
3120                                 } else if (target_type == TypeManager.char_type){
3121                                         if (v >= Char.MinValue && v <= Char.MaxValue)
3122                                                 return (char) v;
3123                                 } else if (target_type == TypeManager.byte_type){
3124                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
3125                                                 return (byte) v;
3126                                 } else if (target_type == TypeManager.sbyte_type){
3127                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
3128                                                 return (sbyte) v;
3129                                 } else if (target_type == TypeManager.short_type){
3130                                         if (v >= Int16.MinValue && v <= UInt16.MaxValue)
3131                                                 return (short) v;
3132                                 } else if (target_type == TypeManager.ushort_type){
3133                                         if (v >= UInt16.MinValue && v <= UInt16.MaxValue)
3134                                                 return (ushort) v;
3135                                 } else if (target_type == TypeManager.int64_type)
3136                                         return (long) v;
3137                                 else if (target_type == TypeManager.uint64_type){
3138                                         if (v > 0)
3139                                                 return (ulong) v;
3140                                 }
3141
3142                                 s = v.ToString ();
3143                         } else if (c is UIntConstant){
3144                                 uint v = ((UIntConstant) c).Value;
3145
3146                                 if (target_type == TypeManager.int32_type){
3147                                         if (v <= Int32.MaxValue)
3148                                                 return (int) v;
3149                                 } else if (target_type == TypeManager.char_type){
3150                                         if (v >= Char.MinValue && v <= Char.MaxValue)
3151                                                 return (char) v;
3152                                 } else if (target_type == TypeManager.byte_type){
3153                                         if (v <= Byte.MaxValue)
3154                                                 return (byte) v;
3155                                 } else if (target_type == TypeManager.sbyte_type){
3156                                         if (v <= SByte.MaxValue)
3157                                                 return (sbyte) v;
3158                                 } else if (target_type == TypeManager.short_type){
3159                                         if (v <= UInt16.MaxValue)
3160                                                 return (short) v;
3161                                 } else if (target_type == TypeManager.ushort_type){
3162                                         if (v <= UInt16.MaxValue)
3163                                                 return (ushort) v;
3164                                 } else if (target_type == TypeManager.int64_type)
3165                                         return (long) v;
3166                                 else if (target_type == TypeManager.uint64_type)
3167                                         return (ulong) v;
3168                                 s = v.ToString ();
3169                         } else if (c is LongConstant){
3170                                 long v = ((LongConstant) c).Value;
3171
3172                                 if (target_type == TypeManager.int32_type){
3173                                         if (v >= UInt32.MinValue && v <= UInt32.MaxValue)
3174                                                 return (int) v;
3175                                 } else if (target_type == TypeManager.uint32_type){
3176                                         if (v >= 0 && v <= UInt32.MaxValue)
3177                                                 return (uint) v;
3178                                 } else if (target_type == TypeManager.char_type){
3179                                         if (v >= Char.MinValue && v <= Char.MaxValue)
3180                                                 return (char) v;
3181                                 } else if (target_type == TypeManager.byte_type){
3182                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
3183                                                 return (byte) v;
3184                                 } else if (target_type == TypeManager.sbyte_type){
3185                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
3186                                                 return (sbyte) v;
3187                                 } else if (target_type == TypeManager.short_type){
3188                                         if (v >= Int16.MinValue && v <= UInt16.MaxValue)
3189                                                 return (short) v;
3190                                 } else if (target_type == TypeManager.ushort_type){
3191                                         if (v >= UInt16.MinValue && v <= UInt16.MaxValue)
3192                                                 return (ushort) v;
3193                                 } else if (target_type == TypeManager.uint64_type){
3194                                         if (v > 0)
3195                                                 return (ulong) v;
3196                                 }
3197                                 s = v.ToString ();
3198                         } else if (c is ULongConstant){
3199                                 ulong v = ((ULongConstant) c).Value;
3200
3201                                 if (target_type == TypeManager.int32_type){
3202                                         if (v <= Int32.MaxValue)
3203                                                 return (int) v;
3204                                 } else if (target_type == TypeManager.uint32_type){
3205                                         if (v <= UInt32.MaxValue)
3206                                                 return (uint) v;
3207                                 } else if (target_type == TypeManager.char_type){
3208                                         if (v >= Char.MinValue && v <= Char.MaxValue)
3209                                                 return (char) v;
3210                                 } else if (target_type == TypeManager.byte_type){
3211                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
3212                                                 return (byte) v;
3213                                 } else if (target_type == TypeManager.sbyte_type){
3214                                         if (v <= (int) SByte.MaxValue)
3215                                                 return (sbyte) v;
3216                                 } else if (target_type == TypeManager.short_type){
3217                                         if (v <= UInt16.MaxValue)
3218                                                 return (short) v;
3219                                 } else if (target_type == TypeManager.ushort_type){
3220                                         if (v <= UInt16.MaxValue)
3221                                                 return (ushort) v;
3222                                 } else if (target_type == TypeManager.int64_type){
3223                                         if (v <= Int64.MaxValue)
3224                                                 return (long) v;
3225                                 }
3226                                 s = v.ToString ();
3227                         } else if (c is ByteConstant){
3228                                 byte v = ((ByteConstant) c).Value;
3229
3230                                 if (target_type == TypeManager.int32_type)
3231                                         return (int) v;
3232                                 else if (target_type == TypeManager.uint32_type)
3233                                         return (uint) v;
3234                                 else if (target_type == TypeManager.char_type)
3235                                         return (char) v;
3236                                 else if (target_type == TypeManager.sbyte_type){
3237                                         if (v <= SByte.MaxValue)
3238                                                 return (sbyte) v;
3239                                 } else if (target_type == TypeManager.short_type)
3240                                         return (short) v;
3241                                 else if (target_type == TypeManager.ushort_type)
3242                                         return (ushort) v;
3243                                 else if (target_type == TypeManager.int64_type)
3244                                         return (long) v;
3245                                 else if (target_type == TypeManager.uint64_type)
3246                                         return (ulong) v;
3247                                 s = v.ToString ();
3248                         } else if (c is SByteConstant){
3249                                 sbyte v = ((SByteConstant) c).Value;
3250
3251                                 if (target_type == TypeManager.int32_type)
3252                                         return (int) v;
3253                                 else if (target_type == TypeManager.uint32_type){
3254                                         if (v >= 0)
3255                                                 return (uint) v;
3256                                 } else if (target_type == TypeManager.char_type){
3257                                         if (v >= 0)
3258                                                 return (char) v;
3259                                 } else if (target_type == TypeManager.byte_type){
3260                                         if (v >= 0)
3261                                                 return (byte) v;
3262                                 } else if (target_type == TypeManager.short_type)
3263                                         return (short) v;
3264                                 else if (target_type == TypeManager.ushort_type){
3265                                         if (v >= 0)
3266                                                 return (ushort) v;
3267                                 } else if (target_type == TypeManager.int64_type)
3268                                         return (long) v;
3269                                 else if (target_type == TypeManager.uint64_type){
3270                                         if (v >= 0)
3271                                                 return (ulong) v;
3272                                 }
3273                                 s = v.ToString ();
3274                         } else if (c is ShortConstant){
3275                                 short v = ((ShortConstant) c).Value;
3276
3277                                 if (target_type == TypeManager.int32_type){
3278                                         return (int) v;
3279                                 } else if (target_type == TypeManager.uint32_type){
3280                                         if (v >= 0)
3281                                                 return (uint) v;
3282                                 } else if (target_type == TypeManager.char_type){
3283                                         if (v >= 0)
3284                                                 return (char) v;
3285                                 } else if (target_type == TypeManager.byte_type){
3286                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
3287                                                 return (byte) v;
3288                                 } else if (target_type == TypeManager.sbyte_type){
3289                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
3290                                                 return (sbyte) v;
3291                                 } else if (target_type == TypeManager.ushort_type){
3292                                         if (v >= 0)
3293                                                 return (ushort) v;
3294                                 } else if (target_type == TypeManager.int64_type)
3295                                         return (long) v;
3296                                 else if (target_type == TypeManager.uint64_type)
3297                                         return (ulong) v;
3298
3299                                 s = v.ToString ();
3300                         } else if (c is UShortConstant){
3301                                 ushort v = ((UShortConstant) c).Value;
3302
3303                                 if (target_type == TypeManager.int32_type)
3304                                         return (int) v;
3305                                 else if (target_type == TypeManager.uint32_type)
3306                                         return (uint) v;
3307                                 else if (target_type == TypeManager.char_type){
3308                                         if (v >= Char.MinValue && v <= Char.MaxValue)
3309                                                 return (char) v;
3310                                 } else if (target_type == TypeManager.byte_type){
3311                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
3312                                                 return (byte) v;
3313                                 } else if (target_type == TypeManager.sbyte_type){
3314                                         if (v <= SByte.MaxValue)
3315                                                 return (byte) v;
3316                                 } else if (target_type == TypeManager.short_type){
3317                                         if (v <= Int16.MaxValue)
3318                                                 return (short) v;
3319                                 } else if (target_type == TypeManager.int64_type)
3320                                         return (long) v;
3321                                 else if (target_type == TypeManager.uint64_type)
3322                                         return (ulong) v;
3323
3324                                 s = v.ToString ();
3325                         } else if (c is CharConstant){
3326                                 char v = ((CharConstant) c).Value;
3327
3328                                 if (target_type == TypeManager.int32_type)
3329                                         return (int) v;
3330                                 else if (target_type == TypeManager.uint32_type)
3331                                         return (uint) v;
3332                                 else if (target_type == TypeManager.byte_type){
3333                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
3334                                                 return (byte) v;
3335                                 } else if (target_type == TypeManager.sbyte_type){
3336                                         if (v <= SByte.MaxValue)
3337                                                 return (sbyte) v;
3338                                 } else if (target_type == TypeManager.short_type){
3339                                         if (v <= Int16.MaxValue)
3340                                                 return (short) v;
3341                                 } else if (target_type == TypeManager.ushort_type)
3342                                         return (short) v;
3343                                 else if (target_type == TypeManager.int64_type)
3344                                         return (long) v;
3345                                 else if (target_type == TypeManager.uint64_type)
3346                                         return (ulong) v;
3347
3348                                 s = v.ToString ();
3349
3350                          } else if (c is DoubleConstant){
3351                                 double v = ((DoubleConstant) c).Value;
3352
3353                                 if (target_type == TypeManager.sbyte_type){
3354                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
3355                                                 return new SByteConstant ((sbyte) System.Math.Round (v));
3356                                 } else if (target_type == TypeManager.byte_type){
3357                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
3358                                                 return new ByteConstant ((byte) System.Math.Round (v));
3359                                 } else if (target_type == TypeManager.char_type){
3360                                         if (v >= Char.MinValue && v <= Char.MaxValue)
3361                                                 return (char) v;
3362                                 } else if (target_type == TypeManager.short_type){
3363                                         if (v >= Int16.MinValue && v <= Int16.MaxValue)
3364                                                 return new ShortConstant ((short) System.Math.Round (v));
3365                                 } else if (target_type == TypeManager.ushort_type){
3366                                         if (v >= UInt16.MinValue && v <= UInt16.MaxValue)
3367                                                  return new UShortConstant ((ushort) System.Math.Round (v));
3368                                 } else if (target_type == TypeManager.int32_type){
3369                                         if (v >= Int32.MinValue && v <= Int32.MaxValue)
3370                                                 return new IntConstant ((int) System.Math.Round (v));
3371                                 } else if (target_type == TypeManager.uint32_type){
3372                                         if (v >= 0 && v <= UInt32.MaxValue)
3373                                                 return new UIntConstant ((uint) System.Math.Round (v));
3374                                 } else if (target_type == TypeManager.uint64_type){
3375                                         if (v > 0)
3376                                                 return new ULongConstant ((ulong) System.Math.Round (v));
3377                                 }
3378                                 s = v.ToString ();
3379                         }
3380
3381                         Error_ConstantValueCannotBeConverted (loc, s, target_type);
3382                         return null;
3383                 }
3384
3385                 //
3386                 // Load the object from the pointer.
3387                 //
3388                 public static void LoadFromPtr (ILGenerator ig, Type t)
3389                 {
3390                         if (t == TypeManager.int32_type)
3391                                 ig.Emit (OpCodes.Ldind_I4);
3392                         else if (t == TypeManager.uint32_type)
3393                                 ig.Emit (OpCodes.Ldind_U4);
3394                         else if (t == TypeManager.short_type)
3395                                 ig.Emit (OpCodes.Ldind_I2);
3396                         else if (t == TypeManager.ushort_type)
3397                                 ig.Emit (OpCodes.Ldind_U2);
3398                         else if (t == TypeManager.char_type)
3399                                 ig.Emit (OpCodes.Ldind_U2);
3400                         else if (t == TypeManager.byte_type)
3401                                 ig.Emit (OpCodes.Ldind_U1);
3402                         else if (t == TypeManager.sbyte_type)
3403                                 ig.Emit (OpCodes.Ldind_I1);
3404                         else if (t == TypeManager.uint64_type)
3405                                 ig.Emit (OpCodes.Ldind_I8);
3406                         else if (t == TypeManager.int64_type)
3407                                 ig.Emit (OpCodes.Ldind_I8);
3408                         else if (t == TypeManager.float_type)
3409                                 ig.Emit (OpCodes.Ldind_R4);
3410                         else if (t == TypeManager.double_type)
3411                                 ig.Emit (OpCodes.Ldind_R8);
3412                         else if (t == TypeManager.bool_type)
3413                                 ig.Emit (OpCodes.Ldind_I1);
3414                         else if (t == TypeManager.intptr_type)
3415                                 ig.Emit (OpCodes.Ldind_I);
3416                         else if (TypeManager.IsEnumType (t)) {
3417                                 if (t == TypeManager.enum_type)
3418                                         ig.Emit (OpCodes.Ldind_Ref);
3419                                 else
3420                                         LoadFromPtr (ig, TypeManager.EnumToUnderlying (t));
3421                         } else if (t.IsValueType)
3422                                 ig.Emit (OpCodes.Ldobj, t);
3423                         else
3424                                 ig.Emit (OpCodes.Ldind_Ref);
3425                 }
3426
3427                 //
3428                 // The stack contains the pointer and the value of type 'type'
3429                 //
3430                 public static void StoreFromPtr (ILGenerator ig, Type type)
3431                 {
3432                         if (TypeManager.IsEnumType (type))
3433                                 type = TypeManager.EnumToUnderlying (type);
3434                         if (type == TypeManager.int32_type || type == TypeManager.uint32_type)
3435                                 ig.Emit (OpCodes.Stind_I4);
3436                         else if (type == TypeManager.int64_type || type == TypeManager.uint64_type)
3437                                 ig.Emit (OpCodes.Stind_I8);
3438                         else if (type == TypeManager.char_type || type == TypeManager.short_type ||
3439                                  type == TypeManager.ushort_type)
3440                                 ig.Emit (OpCodes.Stind_I2);
3441                         else if (type == TypeManager.float_type)
3442                                 ig.Emit (OpCodes.Stind_R4);
3443                         else if (type == TypeManager.double_type)
3444                                 ig.Emit (OpCodes.Stind_R8);
3445                         else if (type == TypeManager.byte_type || type == TypeManager.sbyte_type ||
3446                                  type == TypeManager.bool_type)
3447                                 ig.Emit (OpCodes.Stind_I1);
3448                         else if (type == TypeManager.intptr_type)
3449                                 ig.Emit (OpCodes.Stind_I);
3450                         else if (type.IsValueType)
3451                                 ig.Emit (OpCodes.Stobj, type);
3452                         else
3453                                 ig.Emit (OpCodes.Stind_Ref);
3454                 }
3455
3456                 //
3457                 // Returns the size of type 't' if known, otherwise, 0
3458                 //
3459                 public static int GetTypeSize (Type t)
3460                 {
3461                         t = TypeManager.TypeToCoreType (t);
3462                         if (t == TypeManager.int32_type ||
3463                             t == TypeManager.uint32_type ||
3464                             t == TypeManager.float_type)
3465                                 return 4;
3466                         else if (t == TypeManager.int64_type ||
3467                                  t == TypeManager.uint64_type ||
3468                                  t == TypeManager.double_type)
3469                                 return 8;
3470                         else if (t == TypeManager.byte_type ||
3471                                  t == TypeManager.sbyte_type ||
3472                                  t == TypeManager.bool_type)
3473                                 return 1;
3474                         else if (t == TypeManager.short_type ||
3475                                  t == TypeManager.char_type ||
3476                                  t == TypeManager.ushort_type)
3477                                 return 2;
3478                         else if (t == TypeManager.decimal_type)
3479                                 return 16;
3480                         else
3481                                 return 0;
3482                 }
3483
3484                 //
3485                 // Default implementation of IAssignMethod.CacheTemporaries
3486                 //
3487                 public void CacheTemporaries (EmitContext ec)
3488                 {
3489                 }
3490
3491                 static void Error_NegativeArrayIndex (Location loc)
3492                 {
3493                         Report.Error (284, loc, "Can not create array with a negative size");
3494                 }
3495
3496                 //
3497                 // Converts 'source' to an int, uint, long or ulong.
3498                 //
3499                 public Expression ExpressionToArrayArgument (EmitContext ec, Expression source, Location loc)
3500                 {
3501                         Expression target;
3502
3503                         bool old_checked = ec.CheckState;
3504                         ec.CheckState = true;
3505
3506                         target = ConvertImplicit (ec, source, TypeManager.int32_type, loc);
3507                         if (target == null){
3508                                 target = ConvertImplicit (ec, source, TypeManager.uint32_type, loc);
3509                                 if (target == null){
3510                                         target = ConvertImplicit (ec, source, TypeManager.int64_type, loc);
3511                                         if (target == null){
3512                                                 target = ConvertImplicit (ec, source, TypeManager.uint64_type, loc);
3513                                                 if (target == null)
3514                                                         Expression.Error_CannotConvertImplicit (loc, source.Type, TypeManager.int32_type);
3515                                         }
3516                                 }
3517                         }
3518                         ec.CheckState = old_checked;
3519
3520                         //
3521                         // Only positive constants are allowed at compile time
3522                         //
3523                         if (target is Constant){
3524                                 if (target is IntConstant){
3525                                         if (((IntConstant) target).Value < 0){
3526                                                 Error_NegativeArrayIndex (loc);
3527                                                 return null;
3528                                         }
3529                                 }
3530
3531                                 if (target is LongConstant){
3532                                         if (((LongConstant) target).Value < 0){
3533                                                 Error_NegativeArrayIndex (loc);
3534                                                 return null;
3535                                         }
3536                                 }
3537
3538                         }
3539
3540                         return target;
3541                 }
3542
3543         }
3544
3545         /// <summary>
3546         ///   This is just a base class for expressions that can
3547         ///   appear on statements (invocations, object creation,
3548         ///   assignments, post/pre increment and decrement).  The idea
3549         ///   being that they would support an extra Emition interface that
3550         ///   does not leave a result on the stack.
3551         /// </summary>
3552         public abstract class ExpressionStatement : Expression {
3553
3554                 /// <summary>
3555                 ///   Requests the expression to be emitted in a 'statement'
3556                 ///   context.  This means that no new value is left on the
3557                 ///   stack after invoking this method (constrasted with
3558                 ///   Emit that will always leave a value on the stack).
3559                 /// </summary>
3560                 public abstract void EmitStatement (EmitContext ec);
3561         }
3562
3563         /// <summary>
3564         ///   This kind of cast is used to encapsulate the child
3565         ///   whose type is child.Type into an expression that is
3566         ///   reported to return "return_type".  This is used to encapsulate
3567         ///   expressions which have compatible types, but need to be dealt
3568         ///   at higher levels with.
3569         ///
3570         ///   For example, a "byte" expression could be encapsulated in one
3571         ///   of these as an "unsigned int".  The type for the expression
3572         ///   would be "unsigned int".
3573         ///
3574         /// </summary>
3575         public class EmptyCast : Expression {
3576                 protected Expression child;
3577
3578                 public EmptyCast (Expression child, Type return_type)
3579                 {
3580                         eclass = child.eclass;
3581                         type = return_type;
3582                         this.child = child;
3583                 }
3584
3585                 public override Expression DoResolve (EmitContext ec)
3586                 {
3587                         // This should never be invoked, we are born in fully
3588                         // initialized state.
3589
3590                         return this;
3591                 }
3592
3593                 public override void Emit (EmitContext ec)
3594                 {
3595                         child.Emit (ec);
3596                 }
3597         }
3598
3599         /// <summary>
3600         ///  This class is used to wrap literals which belong inside Enums
3601         /// </summary>
3602         public class EnumConstant : Constant {
3603                 public Constant Child;
3604
3605                 public EnumConstant (Constant child, Type enum_type)
3606                 {
3607                         eclass = child.eclass;
3608                         this.Child = child;
3609                         type = enum_type;
3610                 }
3611
3612                 public override Expression DoResolve (EmitContext ec)
3613                 {
3614                         // This should never be invoked, we are born in fully
3615                         // initialized state.
3616
3617                         return this;
3618                 }
3619
3620                 public override void Emit (EmitContext ec)
3621                 {
3622                         Child.Emit (ec);
3623                 }
3624
3625                 public override object GetValue ()
3626                 {
3627                         return Child.GetValue ();
3628                 }
3629
3630                 //
3631                 // Converts from one of the valid underlying types for an enumeration
3632                 // (int32, uint32, int64, uint64, short, ushort, byte, sbyte) to
3633                 // one of the internal compiler literals: Int/UInt/Long/ULong Literals.
3634                 //
3635                 public Constant WidenToCompilerConstant ()
3636                 {
3637                         Type t = TypeManager.EnumToUnderlying (Child.Type);
3638                         object v = ((Constant) Child).GetValue ();;
3639
3640                         if (t == TypeManager.int32_type)
3641                                 return new IntConstant ((int) v);
3642                         if (t == TypeManager.uint32_type)
3643                                 return new UIntConstant ((uint) v);
3644                         if (t == TypeManager.int64_type)
3645                                 return new LongConstant ((long) v);
3646                         if (t == TypeManager.uint64_type)
3647                                 return new ULongConstant ((ulong) v);
3648                         if (t == TypeManager.short_type)
3649                                 return new ShortConstant ((short) v);
3650                         if (t == TypeManager.ushort_type)
3651                                 return new UShortConstant ((ushort) v);
3652                         if (t == TypeManager.byte_type)
3653                                 return new ByteConstant ((byte) v);
3654                         if (t == TypeManager.sbyte_type)
3655                                 return new SByteConstant ((sbyte) v);
3656
3657                         throw new Exception ("Invalid enumeration underlying type: " + t);
3658                 }
3659
3660                 //
3661                 // Extracts the value in the enumeration on its native representation
3662                 //
3663                 public object GetPlainValue ()
3664                 {
3665                         Type t = TypeManager.EnumToUnderlying (Child.Type);
3666                         object v = ((Constant) Child).GetValue ();;
3667
3668                         if (t == TypeManager.int32_type)
3669                                 return (int) v;
3670                         if (t == TypeManager.uint32_type)
3671                                 return (uint) v;
3672                         if (t == TypeManager.int64_type)
3673                                 return (long) v;
3674                         if (t == TypeManager.uint64_type)
3675                                 return (ulong) v;
3676                         if (t == TypeManager.short_type)
3677                                 return (short) v;
3678                         if (t == TypeManager.ushort_type)
3679                                 return (ushort) v;
3680                         if (t == TypeManager.byte_type)
3681                                 return (byte) v;
3682                         if (t == TypeManager.sbyte_type)
3683                                 return (sbyte) v;
3684
3685                         return null;
3686                 }
3687
3688                 public override string AsString ()
3689                 {
3690                         return Child.AsString ();
3691                 }
3692
3693                 public override DoubleConstant ConvertToDouble ()
3694                 {
3695                         return Child.ConvertToDouble ();
3696                 }
3697
3698                 public override FloatConstant ConvertToFloat ()
3699                 {
3700                         return Child.ConvertToFloat ();
3701                 }
3702
3703                 public override ULongConstant ConvertToULong ()
3704                 {
3705                         return Child.ConvertToULong ();
3706                 }
3707
3708                 public override LongConstant ConvertToLong ()
3709                 {
3710                         return Child.ConvertToLong ();
3711                 }
3712
3713                 public override UIntConstant ConvertToUInt ()
3714                 {
3715                         return Child.ConvertToUInt ();
3716                 }
3717
3718                 public override IntConstant ConvertToInt ()
3719                 {
3720                         return Child.ConvertToInt ();
3721                 }
3722         }
3723
3724         /// <summary>
3725         ///   This kind of cast is used to encapsulate Value Types in objects.
3726         ///
3727         ///   The effect of it is to box the value type emitted by the previous
3728         ///   operation.
3729         /// </summary>
3730         public class BoxedCast : EmptyCast {
3731
3732                 public BoxedCast (Expression expr)
3733                         : base (expr, TypeManager.object_type)
3734                 {
3735                 }
3736
3737                 public override Expression DoResolve (EmitContext ec)
3738                 {
3739                         // This should never be invoked, we are born in fully
3740                         // initialized state.
3741
3742                         return this;
3743                 }
3744
3745                 public override void Emit (EmitContext ec)
3746                 {
3747                         base.Emit (ec);
3748
3749                         ec.ig.Emit (OpCodes.Box, child.Type);
3750                 }
3751         }
3752
3753         public class UnboxCast : EmptyCast {
3754                 public UnboxCast (Expression expr, Type return_type)
3755                         : base (expr, return_type)
3756                 {
3757                 }
3758
3759                 public override Expression DoResolve (EmitContext ec)
3760                 {
3761                         // This should never be invoked, we are born in fully
3762                         // initialized state.
3763
3764                         return this;
3765                 }
3766
3767                 public override void Emit (EmitContext ec)
3768                 {
3769                         Type t = type;
3770                         ILGenerator ig = ec.ig;
3771
3772                         base.Emit (ec);
3773                         ig.Emit (OpCodes.Unbox, t);
3774
3775                         LoadFromPtr (ig, t);
3776                 }
3777         }
3778
3779         /// <summary>
3780         ///   This is used to perform explicit numeric conversions.
3781         ///
3782         ///   Explicit numeric conversions might trigger exceptions in a checked
3783         ///   context, so they should generate the conv.ovf opcodes instead of
3784         ///   conv opcodes.
3785         /// </summary>
3786         public class ConvCast : EmptyCast {
3787                 public enum Mode : byte {
3788                         I1_U1, I1_U2, I1_U4, I1_U8, I1_CH,
3789                         U1_I1, U1_CH,
3790                         I2_I1, I2_U1, I2_U2, I2_U4, I2_U8, I2_CH,
3791                         U2_I1, U2_U1, U2_I2, U2_CH,
3792                         I4_I1, I4_U1, I4_I2, I4_U2, I4_U4, I4_U8, I4_CH,
3793                         U4_I1, U4_U1, U4_I2, U4_U2, U4_I4, U4_CH,
3794                         I8_I1, I8_U1, I8_I2, I8_U2, I8_I4, I8_U4, I8_U8, I8_CH,
3795                         U8_I1, U8_U1, U8_I2, U8_U2, U8_I4, U8_U4, U8_I8, U8_CH,
3796                         CH_I1, CH_U1, CH_I2,
3797                         R4_I1, R4_U1, R4_I2, R4_U2, R4_I4, R4_U4, R4_I8, R4_U8, R4_CH,
3798                         R8_I1, R8_U1, R8_I2, R8_U2, R8_I4, R8_U4, R8_I8, R8_U8, R8_CH, R8_R4
3799                 }
3800
3801                 Mode mode;
3802                 bool checked_state;
3803
3804                 public ConvCast (EmitContext ec, Expression child, Type return_type, Mode m)
3805                         : base (child, return_type)
3806                 {
3807                         checked_state = ec.CheckState;
3808                         mode = m;
3809                 }
3810
3811                 public override Expression DoResolve (EmitContext ec)
3812                 {
3813                         // This should never be invoked, we are born in fully
3814                         // initialized state.
3815
3816                         return this;
3817                 }
3818
3819                 public override void Emit (EmitContext ec)
3820                 {
3821                         ILGenerator ig = ec.ig;
3822
3823                         base.Emit (ec);
3824
3825                         if (checked_state){
3826                                 switch (mode){
3827                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3828                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3829                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3830                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3831                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3832
3833                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3834                                 case Mode.U1_CH: /* nothing */ break;
3835
3836                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3837                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3838                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3839                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3840                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3841                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3842
3843                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3844                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
3845                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
3846                                 case Mode.U2_CH: /* nothing */ break;
3847
3848                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3849                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3850                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
3851                                 case Mode.I4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3852                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3853                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3854                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3855
3856                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3857                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
3858                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
3859                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
3860                                 case Mode.U4_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
3861                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
3862
3863                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3864                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3865                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
3866                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3867                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
3868                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3869                                 case Mode.I8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3870                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3871
3872                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3873                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
3874                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
3875                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
3876                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
3877                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_Ovf_U4_Un); break;
3878                                 case Mode.U8_I8: ig.Emit (OpCodes.Conv_Ovf_I8_Un); break;
3879                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
3880
3881                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
3882                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
3883                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
3884
3885                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3886                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3887                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
3888                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3889                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
3890                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3891                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
3892                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3893                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3894
3895                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
3896                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
3897                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
3898                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3899                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
3900                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
3901                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
3902                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
3903                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
3904                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
3905                                 }
3906                         } else {
3907                                 switch (mode){
3908                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_U1); break;
3909                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_U2); break;
3910                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_U4); break;
3911                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_I8); break;
3912                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_U2); break;
3913
3914                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_I1); break;
3915                                 case Mode.U1_CH: ig.Emit (OpCodes.Conv_U2); break;
3916
3917                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_I1); break;
3918                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_U1); break;
3919                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_U2); break;
3920                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_U4); break;
3921                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_I8); break;
3922                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_U2); break;
3923
3924                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_I1); break;
3925                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_U1); break;
3926                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_I2); break;
3927                                 case Mode.U2_CH: /* nothing */ break;
3928
3929                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_I1); break;
3930                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_U1); break;
3931                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_I2); break;
3932                                 case Mode.I4_U4: /* nothing */ break;
3933                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_U2); break;
3934                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_I8); break;
3935                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_U2); break;
3936
3937                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_I1); break;
3938                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_U1); break;
3939                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_I2); break;
3940                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_U2); break;
3941                                 case Mode.U4_I4: /* nothing */ break;
3942                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_U2); break;
3943
3944                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_I1); break;
3945                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_U1); break;
3946                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_I2); break;
3947                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_U2); break;
3948                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_I4); break;
3949                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_U4); break;
3950                                 case Mode.I8_U8: /* nothing */ break;
3951                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_U2); break;
3952
3953                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_I1); break;
3954                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_U1); break;
3955                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_I2); break;
3956                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_U2); break;
3957                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_I4); break;
3958                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_U4); break;
3959                                 case Mode.U8_I8: /* nothing */ break;
3960                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_U2); break;
3961
3962                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_I1); break;
3963                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_U1); break;
3964                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_I2); break;
3965
3966                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_I1); break;
3967                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_U1); break;
3968                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_I2); break;
3969                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_U2); break;
3970                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_I4); break;
3971                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_U4); break;
3972                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_I8); break;
3973                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_U8); break;
3974                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_U2); break;
3975
3976                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_I1); break;
3977                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_U1); break;
3978                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_I2); break;
3979                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_U2); break;
3980                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_I4); break;
3981                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_U4); break;
3982                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_I8); break;
3983                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_U8); break;
3984                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_U2); break;
3985                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
3986                                 }
3987                         }
3988                 }
3989         }
3990
3991         public class OpcodeCast : EmptyCast {
3992                 OpCode op, op2;
3993                 bool second_valid;
3994
3995                 public OpcodeCast (Expression child, Type return_type, OpCode op)
3996                         : base (child, return_type)
3997
3998                 {
3999                         this.op = op;
4000                         second_valid = false;
4001                 }
4002
4003                 public OpcodeCast (Expression child, Type return_type, OpCode op, OpCode op2)
4004                         : base (child, return_type)
4005
4006                 {
4007                         this.op = op;
4008                         this.op2 = op2;
4009                         second_valid = true;
4010                 }
4011
4012                 public override Expression DoResolve (EmitContext ec)
4013                 {
4014                         // This should never be invoked, we are born in fully
4015                         // initialized state.
4016
4017                         return this;
4018                 }
4019
4020                 public override void Emit (EmitContext ec)
4021                 {
4022                         base.Emit (ec);
4023                         ec.ig.Emit (op);
4024
4025                         if (second_valid)
4026                                 ec.ig.Emit (op2);
4027                 }
4028         }
4029
4030
4031         public class NumericToBoolCast : EmptyCast
4032         {
4033                 Type src_type;
4034
4035                 public NumericToBoolCast (Expression src, Type src_type)
4036                         : base (src, TypeManager.bool_type)
4037
4038                 {
4039                         this.src_type = src_type;
4040                 }
4041
4042                 public override Expression DoResolve (EmitContext ec)
4043                 {
4044                         return this;
4045                 }
4046
4047                 public override void Emit (EmitContext ec)
4048                 {
4049                         base.Emit (ec);
4050
4051                         if (src_type == TypeManager.byte_type ||
4052                                 src_type == TypeManager.short_type ||
4053                                 src_type == TypeManager.int32_type) {
4054
4055                                 ec.ig.Emit (OpCodes.Ldc_I4_0);
4056                                 ec.ig.Emit (OpCodes.Cgt_Un);
4057                                 return;
4058                         }
4059
4060                         if (src_type == TypeManager.int64_type) {
4061                                 ec.ig.Emit (OpCodes.Ldc_I8, (long) 0);
4062                                 ec.ig.Emit (OpCodes.Cgt_Un);
4063                                 return;
4064                         }
4065
4066                         if (src_type == TypeManager.float_type) {
4067                                 ec.ig.Emit (OpCodes.Ldc_R4, (float) 0);
4068                                 ec.ig.Emit (OpCodes.Ceq);
4069                                 ec.ig.Emit (OpCodes.Ldc_I4_0);
4070                                 ec.ig.Emit (OpCodes.Ceq);
4071                                 return;
4072                         }
4073
4074                         if (src_type == TypeManager.double_type) {
4075                                 ec.ig.Emit (OpCodes.Ldc_R8, (double) 0);
4076                                 ec.ig.Emit (OpCodes.Ceq);
4077                                 ec.ig.Emit (OpCodes.Ldc_I4_0);
4078                                 ec.ig.Emit (OpCodes.Ceq);
4079                                 return;
4080                         }
4081                 }
4082         }
4083
4084         public class BoolToNumericCast : EmptyCast
4085         {
4086                 Expression src;
4087                 Type target_type;
4088                 OpCode conv;
4089
4090                 public BoolToNumericCast (Expression src, Type target_type)
4091                         : base (src, target_type)
4092
4093                 {
4094                         this.target_type = target_type;
4095                 }
4096
4097                 public override Expression DoResolve (EmitContext ec)
4098                 {
4099                         return this;
4100                 }
4101
4102                 public override void Emit (EmitContext ec)
4103                 {
4104                         base.Emit (ec);
4105
4106                         if (target_type == TypeManager.byte_type) {
4107                                 conv = OpCodes.Conv_U1;
4108                         } else if (target_type == TypeManager.short_type) {
4109                                 conv = OpCodes.Conv_I2;
4110                         } else if (target_type == TypeManager.int32_type) {
4111                                 conv = OpCodes.Conv_I4;
4112                         } else if (target_type == TypeManager.int64_type) {
4113                                 conv = OpCodes.Conv_I8;
4114                         } else if (target_type == TypeManager.float_type) {
4115                                 conv = OpCodes.Conv_R4;
4116                         } else if (target_type == TypeManager.double_type) {
4117                                 conv = OpCodes.Conv_R8;
4118                         }
4119
4120                         ec.ig.Emit (OpCodes.Ldc_I4_0);
4121                         ec.ig.Emit (OpCodes.Cgt_Un);
4122                         ec.ig.Emit (OpCodes.Neg);
4123                         ec.ig.Emit (conv);
4124                         return;
4125                 }
4126         }
4127
4128         /// <summary>
4129         ///   This kind of cast is used to encapsulate a child and cast it
4130         ///   to the class requested
4131         /// </summary>
4132         public class ClassCast : EmptyCast {
4133                 public ClassCast (Expression child, Type return_type)
4134                         : base (child, return_type)
4135
4136                 {
4137                 }
4138
4139                 public override Expression DoResolve (EmitContext ec)
4140                 {
4141                         // This should never be invoked, we are born in fully
4142                         // initialized state.
4143
4144                         return this;
4145                 }
4146
4147                 public override void Emit (EmitContext ec)
4148                 {
4149                         base.Emit (ec);
4150
4151                         ec.ig.Emit (OpCodes.Castclass, type);
4152                 }
4153
4154         }
4155
4156         /// <summary>
4157         ///   SimpleName expressions are initially formed of a single
4158         ///   word and it only happens at the beginning of the expression.
4159         /// </summary>
4160         ///
4161         /// <remarks>
4162         ///   The expression will try to be bound to a Field, a Method
4163         ///   group or a Property.  If those fail we pass the name to our
4164         ///   caller and the SimpleName is compounded to perform a type
4165         ///   lookup.  The idea behind this process is that we want to avoid
4166         ///   creating a namespace map from the assemblies, as that requires
4167         ///   the GetExportedTypes function to be called and a hashtable to
4168         ///   be constructed which reduces startup time.  If later we find
4169         ///   that this is slower, we should create a 'NamespaceExpr' expression
4170         ///   that fully participates in the resolution process.
4171         ///
4172         ///   For example 'System.Console.WriteLine' is decomposed into
4173         ///   MemberAccess (MemberAccess (SimpleName ("System"), "Console"), "WriteLine")
4174         ///
4175         ///   The first SimpleName wont produce a match on its own, so it will
4176         ///   be turned into:
4177         ///   MemberAccess (SimpleName ("System.Console"), "WriteLine").
4178         ///
4179         ///   System.Console will produce a TypeExpr match.
4180         ///
4181         ///   The downside of this is that we might be hitting 'LookupType' too many
4182         ///   times with this scheme.
4183         /// </remarks>
4184         public class SimpleName : Expression, ITypeExpression {
4185                 public readonly string Name;
4186
4187                 public SimpleName (string name, Location l)
4188                 {
4189                         Name = name;
4190                         loc = l;
4191                 }
4192
4193                 public static void Error_ObjectRefRequired (EmitContext ec, Location l, string name)
4194                 {
4195                         if (ec.IsFieldInitializer)
4196                                 Report.Error (
4197                                         236, l,
4198                                         "A field initializer cannot reference the non-static field, " +
4199                                         "method or property '"+name+"'");
4200                         else
4201                                 Report.Error (
4202                                         120, l,
4203                                         "An object reference is required " +
4204                                         "for the non-static field '"+name+"'");
4205                 }
4206
4207                 //
4208                 // Checks whether we are trying to access an instance
4209                 // property, method or field from a static body.
4210                 //
4211                 Expression MemberStaticCheck (EmitContext ec, Expression e)
4212                 {
4213                         if (e is IMemberExpr){
4214                                 IMemberExpr member = (IMemberExpr) e;
4215
4216                                 if (!member.IsStatic){
4217                                         Error_ObjectRefRequired (ec, loc, Name);
4218                                         return null;
4219                                 }
4220                         }
4221
4222                         return e;
4223                 }
4224
4225                 public override Expression DoResolve (EmitContext ec)
4226                 {
4227                         return SimpleNameResolve (ec, null, false);
4228                 }
4229
4230                 public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
4231                 {
4232                         return SimpleNameResolve (ec, right_side, false);
4233                 }
4234
4235
4236                 public Expression DoResolveAllowStatic (EmitContext ec)
4237                 {
4238                         return SimpleNameResolve (ec, null, true);
4239                 }
4240
4241                 public Expression DoResolveType (EmitContext ec)
4242                 {
4243                         //
4244                         // Stage 3: Lookup symbol in the various namespaces.
4245                         //
4246                         DeclSpace ds = ec.DeclSpace;
4247                         Type t;
4248                         string alias_value;
4249
4250                         if (ec.ResolvingTypeTree){
4251                                 int errors = Report.Errors;
4252                                 Type dt = ec.DeclSpace.FindType (loc, Name);
4253                                 if (Report.Errors != errors)
4254                                         return null;
4255
4256                                 if (dt != null)
4257                                         return new TypeExpr (dt, loc);
4258                         }
4259
4260                         if ((t = RootContext.LookupType (ds, Name, true, loc)) != null)
4261                                 return new TypeExpr (t, loc);
4262
4263
4264                         //
4265                         // Stage 2 part b: Lookup up if we are an alias to a type
4266                         // or a namespace.
4267                         //
4268                         // Since we are cheating: we only do the Alias lookup for
4269                         // namespaces if the name does not include any dots in it
4270                         //
4271
4272                         alias_value = ec.DeclSpace.LookupAlias (Name);
4273
4274                         if (Name.IndexOf ('.') == -1 && alias_value != null) {
4275                                 if ((t = RootContext.LookupType (ds, alias_value, true, loc)) != null)
4276                                         return new TypeExpr (t, loc);
4277
4278                                 // we have alias value, but it isn't Type, so try if it's namespace
4279                                 return new SimpleName (alias_value, loc);
4280                         }
4281
4282                         // No match, maybe our parent can compose us
4283                         // into something meaningful.
4284                         return this;
4285                 }
4286
4287                 /// <remarks>
4288                 ///   7.5.2: Simple Names.
4289                 ///
4290                 ///   Local Variables and Parameters are handled at
4291                 ///   parse time, so they never occur as SimpleNames.
4292                 ///
4293                 ///   The 'allow_static' flag is used by MemberAccess only
4294                 ///   and it is used to inform us that it is ok for us to
4295                 ///   avoid the static check, because MemberAccess might end
4296                 ///   up resolving the Name as a Type name and the access as
4297                 ///   a static type access.
4298                 ///
4299                 ///   ie: Type Type; .... { Type.GetType (""); }
4300                 ///
4301                 ///   Type is both an instance variable and a Type;  Type.GetType
4302                 ///   is the static method not an instance method of type.
4303                 /// </remarks>
4304                 Expression SimpleNameResolve (EmitContext ec, Expression right_side, bool allow_static)
4305                 {
4306                         Expression e = null;
4307
4308                         //
4309                         // Stage 1: Performed by the parser (binding to locals or parameters).
4310                         //
4311                         Block current_block = ec.CurrentBlock;
4312                         if (ec.InvokingOwnOverload == false && current_block != null && current_block.IsVariableDefined (Name)){
4313                                 LocalVariableReference var;
4314
4315                                 var = new LocalVariableReference (ec.CurrentBlock, Name, loc);
4316
4317                                 if (right_side != null)
4318                                         return var.ResolveLValue (ec, right_side);
4319                                 else
4320                                         return var.Resolve (ec);
4321                         }
4322
4323                         if (current_block != null){
4324                                 int idx = -1;
4325                                 Parameter par = null;
4326                                 Parameters pars = current_block.Parameters;
4327                                 if (pars != null)
4328                                         par = pars.GetParameterByName (Name, out idx);
4329
4330                                 if (par != null) {
4331                                         ParameterReference param;
4332
4333                                         param = new ParameterReference (pars, idx, Name, loc);
4334
4335                                         if (right_side != null)
4336                                                 return param.ResolveLValue (ec, right_side);
4337                                         else
4338                                                 return param.Resolve (ec);
4339                                 }
4340                         }
4341
4342                         //
4343                         // Stage 2: Lookup members
4344                         //
4345
4346                         //
4347                         // For enums, the TypeBuilder is not ec.DeclSpace.TypeBuilder
4348                         // Hence we have two different cases
4349                         //
4350
4351                         DeclSpace lookup_ds = ec.DeclSpace;
4352                         do {
4353                                 if (lookup_ds.TypeBuilder == null)
4354                                         break;
4355
4356                                 e = MemberLookup (ec, lookup_ds.TypeBuilder, Name, loc);
4357                                 if (e != null)
4358                                         break;
4359
4360                                 //
4361                                 // Classes/structs keep looking, enums break
4362                                 //
4363                                 if (lookup_ds is TypeContainer)
4364                                         lookup_ds = ((TypeContainer) lookup_ds).Parent;
4365                                 else
4366                                         break;
4367                         } while (lookup_ds != null);
4368
4369                         if (e == null && ec.ContainerType != null)
4370                                 e = MemberLookup (ec, ec.ContainerType, Name, loc);
4371
4372 // #52067 - Start - Trying to solve
4373
4374                         if (e == null) {
4375
4376                                 ArrayList lookups = new ArrayList();
4377                                 ArrayList typelookups = new ArrayList();
4378
4379                                 int split = Name.LastIndexOf('.');
4380                                 if (split != -1) {
4381                                         String nameSpacePart = Name.Substring(0, split);
4382                                         String memberNamePart = Name.Substring(split + 1);
4383                                         foreach(Type type in TypeManager.GetPertinentStandardModules(nameSpacePart)) {
4384                                                 e = MemberLookup(ec, type, memberNamePart, loc);
4385                                                 if (e != null) {
4386                                                         lookups.Add(e);
4387                                                         typelookups.Add(type);
4388                                                 }
4389                                         }
4390                                 }
4391
4392                                 string[] NamespacesInScope = RootContext.SourceBeingCompiled.GetNamespacesInScope(ec.DeclSpace.Namespace.Name);
4393                                 foreach(Type type in TypeManager.GetPertinentStandardModules(NamespacesInScope)) {
4394                                         e = MemberLookup(ec, type, Name, loc);
4395                                         if (e != null) {
4396                                                 lookups.Add(e);
4397                                                 typelookups.Add(type);
4398                                         }
4399                                 }
4400                                 if (lookups.Count == 1) {
4401                                         e = (Expression)lookups[0];
4402                                 } else {
4403                                         if (lookups.Count > 1) {
4404                                                 StringBuilder sb = new StringBuilder();
4405                                                 foreach(Type type in typelookups)
4406                                                         sb.Append("'" + type.FullName + "'");
4407                                                 Error (-1, "The name '" + Name + "' can be resolved to a member of more than one standard module: " + sb.ToString() + ". Please fully qualify it.");
4408                                                 return null;
4409                                         }
4410                                 }
4411                         }
4412
4413 // #52067 - End
4414
4415                         if (e == null)
4416                                 return DoResolveType (ec);
4417
4418                         if (e is TypeExpr)
4419                                 return e;
4420
4421                         if (e is IMemberExpr) {
4422                                 e = MemberAccess.ResolveMemberAccess (ec, e, null, loc, this);
4423                                 if (e == null)
4424                                         return null;
4425
4426                                 IMemberExpr me = e as IMemberExpr;
4427                                 if (me == null)
4428                                         return e;
4429
4430                                 // This fails if ResolveMemberAccess() was unable to decide whether
4431                                 // it's a field or a type of the same name.
4432                                 if (!me.IsStatic && (me.InstanceExpression == null))
4433                                         return e;
4434
4435 /* FIXME    If this is not commented out, it seems that it's not possible to reach class members in mBas.
4436             Maybe a grammar-related problem?
4437
4438                                 if (!me.IsStatic &&
4439                                     TypeManager.IsNestedChildOf (me.InstanceExpression.Type, me.DeclaringType)) {
4440                                         Error (38, "Cannot access nonstatic member '" + me.Name + "' of " +
4441                                                "outer type '" + me.DeclaringType + "' via nested type '" +
4442                                                me.InstanceExpression.Type + "'");
4443                                         return null;
4444                                 }
4445 */
4446                                 if (right_side != null)
4447                                         e = e.DoResolveLValue (ec, right_side);
4448                                 else
4449                                         e = e.DoResolve (ec);
4450
4451                                 return e;
4452                         }
4453
4454                         if (ec.IsStatic || ec.IsFieldInitializer){
4455                                 if (allow_static)
4456                                         return e;
4457
4458                                 return MemberStaticCheck (ec, e);
4459                         } else
4460                                 return e;
4461                 }
4462
4463                 public override void Emit (EmitContext ec)
4464                 {
4465                         //
4466                         // If this is ever reached, then we failed to
4467                         // find the name as a namespace
4468                         //
4469
4470                         Error (30451, "The name '" + Name +
4471                                "' does not exist in the class '" +
4472                                ec.DeclSpace.Name + "'");
4473                 }
4474
4475                 public override string ToString ()
4476                 {
4477                         return Name;
4478                 }
4479         }
4480
4481         /// <summary>
4482         ///   Fully resolved expression that evaluates to a type
4483         /// </summary>
4484         public class TypeExpr : Expression, ITypeExpression {
4485                 public TypeExpr (Type t, Location l)
4486                 {
4487                         Type = t;
4488                         eclass = ExprClass.Type;
4489                         loc = l;
4490                 }
4491
4492                 public virtual Expression DoResolveType (EmitContext ec)
4493                 {
4494                         return this;
4495                 }
4496
4497                 override public Expression DoResolve (EmitContext ec)
4498                 {
4499                         return this;
4500                 }
4501
4502                 override public void Emit (EmitContext ec)
4503                 {
4504                         throw new Exception ("Should never be called");
4505                 }
4506
4507                 public override string ToString ()
4508                 {
4509                         return Type.ToString ();
4510                 }
4511         }
4512
4513         /// <summary>
4514         ///   Used to create types from a fully qualified name.  These are just used
4515         ///   by the parser to setup the core types.  A TypeLookupExpression is always
4516         ///   classified as a type.
4517         /// </summary>
4518         public class TypeLookupExpression : TypeExpr {
4519                 string name;
4520
4521                 public TypeLookupExpression (string name) : base (null, Location.Null)
4522                 {
4523                         this.name = name;
4524                 }
4525
4526                 public override Expression DoResolveType (EmitContext ec)
4527                 {
4528                         if (type == null)
4529                                 type = RootContext.LookupType (ec.DeclSpace, name, false, Location.Null);
4530                         return this;
4531                 }
4532
4533                 public override Expression DoResolve (EmitContext ec)
4534                 {
4535                         return DoResolveType (ec);
4536                 }
4537
4538                 public override void Emit (EmitContext ec)
4539                 {
4540                         throw new Exception ("Should never be called");
4541                 }
4542
4543                 public override string ToString ()
4544                 {
4545                         return name;
4546                 }
4547         }
4548
4549         /// <summary>
4550         ///   MethodGroup Expression.
4551         ///
4552         ///   This is a fully resolved expression that evaluates to a type
4553         /// </summary>
4554         public class MethodGroupExpr : Expression, IMemberExpr {
4555                 public MethodBase [] Methods;
4556                 Expression instance_expression = null;
4557                 bool is_explicit_impl = false;
4558
4559                 public MethodGroupExpr (MemberInfo [] mi, Location l)
4560                 {
4561                         Methods = new MethodBase [mi.Length];
4562                         mi.CopyTo (Methods, 0);
4563                         eclass = ExprClass.MethodGroup;
4564                         type = TypeManager.object_type;
4565                         loc = l;
4566                 }
4567
4568                 public MethodGroupExpr (ArrayList list, Location l)
4569                 {
4570                         Methods = new MethodBase [list.Count];
4571
4572                         try {
4573                                 list.CopyTo (Methods, 0);
4574                         } catch {
4575                                 foreach (MemberInfo m in list){
4576                                         if (!(m is MethodBase)){
4577                                                 Console.WriteLine ("Name " + m.Name);
4578                                                 Console.WriteLine ("Found a: " + m.GetType ().FullName);
4579                                         }
4580                                 }
4581                                 throw;
4582                         }
4583                         loc = l;
4584                         eclass = ExprClass.MethodGroup;
4585                         type = TypeManager.object_type;
4586                 }
4587
4588                 public Type DeclaringType {
4589                         get {
4590                                 return Methods [0].DeclaringType;
4591                         }
4592                 }
4593
4594                 //
4595                 // 'A method group may have associated an instance expression'
4596                 //
4597                 public Expression InstanceExpression {
4598                         get {
4599                                 return instance_expression;
4600                         }
4601
4602                         set {
4603                                 instance_expression = value;
4604                         }
4605                 }
4606
4607                 public bool IsExplicitImpl {
4608                         get {
4609                                 return is_explicit_impl;
4610                         }
4611
4612                         set {
4613                                 is_explicit_impl = value;
4614                         }
4615                 }
4616
4617                 public string Name {
4618                         get {
4619                                 return Methods [0].Name;
4620                         }
4621                 }
4622
4623                 public bool IsInstance {
4624                         get {
4625                                 foreach (MethodBase mb in Methods)
4626                                         if (!mb.IsStatic)
4627                                                 return true;
4628
4629                                 return false;
4630                         }
4631                 }
4632
4633                 public bool IsStatic {
4634                         get {
4635                                 foreach (MethodBase mb in Methods)
4636                                         if (mb.IsStatic)
4637                                                 return true;
4638
4639                                 return false;
4640                         }
4641                 }
4642
4643                 override public Expression DoResolve (EmitContext ec)
4644                 {
4645                         if (instance_expression != null) {
4646                                 instance_expression = instance_expression.DoResolve (ec);
4647                                 if (instance_expression == null)
4648                                         return null;
4649                         }
4650
4651                         return this;
4652                 }
4653
4654                 public void ReportUsageError ()
4655                 {
4656                         Report.Error (654, loc, "Method '" + Methods [0].DeclaringType + "." +
4657                                       Methods [0].Name + "()' is referenced without parentheses");
4658                 }
4659
4660                 override public void Emit (EmitContext ec)
4661                 {
4662                         ReportUsageError ();
4663                 }
4664
4665                 bool RemoveMethods (bool keep_static)
4666                 {
4667                         ArrayList smethods = new ArrayList ();
4668
4669                         foreach (MethodBase mb in Methods){
4670                                 if (mb.IsStatic == keep_static)
4671                                         smethods.Add (mb);
4672                         }
4673
4674                         if (smethods.Count == 0)
4675                                 return false;
4676
4677                         Methods = new MethodBase [smethods.Count];
4678                         smethods.CopyTo (Methods, 0);
4679
4680                         return true;
4681                 }
4682
4683                 /// <summary>
4684                 ///   Removes any instance methods from the MethodGroup, returns
4685                 ///   false if the resulting set is empty.
4686                 /// </summary>
4687                 public bool RemoveInstanceMethods ()
4688                 {
4689                         return RemoveMethods (true);
4690                 }
4691
4692                 /// <summary>
4693                 ///   Removes any static methods from the MethodGroup, returns
4694                 ///   false if the resulting set is empty.
4695                 /// </summary>
4696                 public bool RemoveStaticMethods ()
4697                 {
4698                         return RemoveMethods (false);
4699                 }
4700         }
4701
4702         /// <summary>
4703         ///   Fully resolved expression that evaluates to a Field
4704         /// </summary>
4705         public class FieldExpr : Expression, IAssignMethod, IMemoryLocation, IMemberExpr {
4706                 public readonly FieldInfo FieldInfo;
4707                 Expression instance_expr;
4708
4709                 public FieldExpr (FieldInfo fi, Location l)
4710                 {
4711                         FieldInfo = fi;
4712                         eclass = ExprClass.Variable;
4713                         type = fi.FieldType;
4714                         loc = l;
4715                 }
4716
4717                 public string Name {
4718                         get {
4719                                 return FieldInfo.Name;
4720                         }
4721                 }
4722
4723                 public bool IsInstance {
4724                         get {
4725                                 return !FieldInfo.IsStatic;
4726                         }
4727                 }
4728
4729                 public bool IsStatic {
4730                         get {
4731                                 return FieldInfo.IsStatic;
4732                         }
4733                 }
4734
4735                 public Type DeclaringType {
4736                         get {
4737                                 return FieldInfo.DeclaringType;
4738                         }
4739                 }
4740
4741                 public Expression InstanceExpression {
4742                         get {
4743                                 return instance_expr;
4744                         }
4745
4746                         set {
4747                                 instance_expr = value;
4748                         }
4749                 }
4750
4751                 override public Expression DoResolve (EmitContext ec)
4752                 {
4753                         if (!FieldInfo.IsStatic){
4754                                 if (instance_expr == null){
4755                                         throw new Exception ("non-static FieldExpr without instance var\n" +
4756                                                              "You have to assign the Instance variable\n" +
4757                                                              "Of the FieldExpr to set this\n");
4758                                 }
4759
4760                                 // Resolve the field's instance expression while flow analysis is turned
4761                                 // off: when accessing a field "a.b", we must check whether the field
4762                                 // "a.b" is initialized, not whether the whole struct "a" is initialized.
4763                                 instance_expr = instance_expr.Resolve (ec, ResolveFlags.VariableOrValue |
4764                                                                        ResolveFlags.DisableFlowAnalysis);
4765                                 if (instance_expr == null)
4766                                         return null;
4767                         }
4768
4769                         // If the instance expression is a local variable or parameter.
4770                         IVariable var = instance_expr as IVariable;
4771                         if ((var != null) && !var.IsFieldAssigned (ec, FieldInfo.Name, loc))
4772                                 return null;
4773
4774                         return this;
4775                 }
4776
4777                 void Report_AssignToReadonly (bool is_instance)
4778                 {
4779                         string msg;
4780
4781                         if (is_instance)
4782                                 msg = "Readonly field can not be assigned outside " +
4783                                 "of constructor or variable initializer";
4784                         else
4785                                 msg = "A static readonly field can only be assigned in " +
4786                                 "a static constructor";
4787
4788                         Report.Error (is_instance ? 191 : 198, loc, msg);
4789                 }
4790
4791                 override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
4792                 {
4793                         IVariable var = instance_expr as IVariable;
4794                         if (var != null)
4795                                 var.SetFieldAssigned (ec, FieldInfo.Name);
4796
4797                         Expression e = DoResolve (ec);
4798
4799                         if (e == null)
4800                                 return null;
4801
4802                         if (!FieldInfo.IsInitOnly)
4803                                 return this;
4804
4805                         //
4806                         // InitOnly fields can only be assigned in constructors
4807                         //
4808
4809                         if (ec.IsConstructor)
4810                                 return this;
4811
4812                         Report_AssignToReadonly (true);
4813
4814                         return null;
4815                 }
4816
4817                 override public void Emit (EmitContext ec)
4818                 {
4819                         ILGenerator ig = ec.ig;
4820                         bool is_volatile = false;
4821
4822                         if (FieldInfo is FieldBuilder){
4823                                 FieldBase f = TypeManager.GetField (FieldInfo);
4824
4825                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
4826                                         is_volatile = true;
4827
4828                                 f.status |= Field.Status.USED;
4829                         }
4830
4831                         if (FieldInfo.IsStatic){
4832                                 if (is_volatile)
4833                                         ig.Emit (OpCodes.Volatile);
4834
4835                                 ig.Emit (OpCodes.Ldsfld, FieldInfo);
4836                         } else {
4837                                 if (instance_expr.Type.IsValueType){
4838                                         IMemoryLocation ml;
4839                                         LocalTemporary tempo = null;
4840
4841                                         if (!(instance_expr is IMemoryLocation)){
4842                                                 tempo = new LocalTemporary (
4843                                                         ec, instance_expr.Type);
4844
4845                                                 InstanceExpression.Emit (ec);
4846                                                 tempo.Store (ec);
4847                                                 ml = tempo;
4848                                         } else
4849                                                 ml = (IMemoryLocation) instance_expr;
4850
4851                                         ml.AddressOf (ec, AddressOp.Load);
4852                                 } else
4853                                         instance_expr.Emit (ec);
4854
4855                                 if (is_volatile)
4856                                         ig.Emit (OpCodes.Volatile);
4857
4858                                 ig.Emit (OpCodes.Ldfld, FieldInfo);
4859                         }
4860                 }
4861
4862                 public void EmitAssign (EmitContext ec, Expression source)
4863                 {
4864                         FieldAttributes fa = FieldInfo.Attributes;
4865                         bool is_static = (fa & FieldAttributes.Static) != 0;
4866                         bool is_readonly = (fa & FieldAttributes.InitOnly) != 0;
4867                         ILGenerator ig = ec.ig;
4868
4869                         if (is_readonly && !ec.IsConstructor){
4870                                 Report_AssignToReadonly (!is_static);
4871                                 return;
4872                         }
4873
4874                         if (!is_static){
4875                                 Expression instance = instance_expr;
4876
4877                                 if (instance.Type.IsValueType){
4878                                         if (instance is IMemoryLocation){
4879                                                 IMemoryLocation ml = (IMemoryLocation) instance;
4880
4881                                                 ml.AddressOf (ec, AddressOp.Store);
4882                                         } else
4883                                                 throw new Exception ("The " + instance + " of type " +
4884                                                                      instance.Type +
4885                                                                      " represents a ValueType and does " +
4886                                                                      "not implement IMemoryLocation");
4887                                 } else
4888                                         instance.Emit (ec);
4889                         }
4890                         source.Emit (ec);
4891
4892                         if (FieldInfo is FieldBuilder){
4893                                 FieldBase f = TypeManager.GetField (FieldInfo);
4894
4895                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
4896                                         ig.Emit (OpCodes.Volatile);
4897                         }
4898
4899                         if (is_static)
4900                                 ig.Emit (OpCodes.Stsfld, FieldInfo);
4901                         else
4902                                 ig.Emit (OpCodes.Stfld, FieldInfo);
4903
4904                         if (FieldInfo is FieldBuilder){
4905                                 FieldBase f = TypeManager.GetField (FieldInfo);
4906
4907                                 f.status |= Field.Status.ASSIGNED;
4908                         }
4909                 }
4910
4911                 public void AddressOf (EmitContext ec, AddressOp mode)
4912                 {
4913                         ILGenerator ig = ec.ig;
4914
4915                         if (FieldInfo is FieldBuilder){
4916                                 FieldBase f = TypeManager.GetField (FieldInfo);
4917                                 if ((f.ModFlags & Modifiers.VOLATILE) != 0)
4918                                         ig.Emit (OpCodes.Volatile);
4919                         }
4920
4921                         if (FieldInfo is FieldBuilder){
4922                                 FieldBase f = TypeManager.GetField (FieldInfo);
4923
4924                                 if ((mode & AddressOp.Store) != 0)
4925                                         f.status |= Field.Status.ASSIGNED;
4926                                 if ((mode & AddressOp.Load) != 0)
4927                                         f.status |= Field.Status.USED;
4928                         }
4929
4930                         //
4931                         // Handle initonly fields specially: make a copy and then
4932                         // get the address of the copy.
4933                         //
4934                         if (FieldInfo.IsInitOnly && !ec.IsConstructor){
4935                                 LocalBuilder local;
4936
4937                                 Emit (ec);
4938                                 local = ig.DeclareLocal (type);
4939                                 ig.Emit (OpCodes.Stloc, local);
4940                                 ig.Emit (OpCodes.Ldloca, local);
4941                                 return;
4942                         }
4943
4944                         if (FieldInfo.IsStatic)
4945                                 ig.Emit (OpCodes.Ldsflda, FieldInfo);
4946                         else {
4947                                 if (instance_expr is IMemoryLocation)
4948                                         ((IMemoryLocation)instance_expr).AddressOf (ec, AddressOp.LoadStore);
4949                                 else
4950                                         instance_expr.Emit (ec);
4951                                 ig.Emit (OpCodes.Ldflda, FieldInfo);
4952                         }
4953                 }
4954         }
4955
4956         /// <summary>
4957         ///   Expression that evaluates to a Property.  The Assign class
4958         ///   might set the 'Value' expression if we are in an assignment.
4959         ///
4960         ///   This is not an LValue because we need to re-write the expression, we
4961         ///   can not take data from the stack and store it.
4962         /// </summary>
4963         public class PropertyExpr : ExpressionStatement, IAssignMethod, IMemberExpr {
4964                 public readonly PropertyInfo PropertyInfo;
4965                 public bool IsBase;
4966                 MethodInfo getter, setter;
4967                 bool is_static;
4968                 public ArrayList PropertyArgs;
4969
4970                 Expression instance_expr;
4971
4972                 public PropertyExpr (EmitContext ec, PropertyInfo pi, Location l)
4973                 {
4974                         PropertyInfo = pi;
4975                         eclass = ExprClass.PropertyAccess;
4976                         PropertyArgs = null;
4977                         is_static = false;
4978                         loc = l;
4979
4980                         type = TypeManager.TypeToCoreType (pi.PropertyType);
4981
4982                         ResolveAccessors (ec);
4983                 }
4984
4985                 public string Name {
4986                         get {
4987                                 return PropertyInfo.Name;
4988                         }
4989                 }
4990
4991                 public bool IsInstance {
4992                         get {
4993                                 return !is_static;
4994                         }
4995                 }
4996
4997                 public bool IsStatic {
4998                         get {
4999                                 return is_static;
5000                         }
5001                 }
5002
5003                 public Type DeclaringType {
5004                         get {
5005                                 return PropertyInfo.DeclaringType;
5006                         }
5007                 }
5008
5009                 //
5010                 // The instance expression associated with this expression
5011                 //
5012                 public Expression InstanceExpression {
5013                         set {
5014                                 instance_expr = value;
5015                         }
5016
5017                         get {
5018                                 return instance_expr;
5019                         }
5020                 }
5021
5022                 public bool VerifyAssignable ()
5023                 {
5024                         if (!PropertyInfo.CanWrite){
5025                                 Report.Error (200, loc,
5026                                               "The property '" + PropertyInfo.Name +
5027                                               "' can not be assigned to, as it has not set accessor");
5028                                 return false;
5029                         }
5030
5031                         return true;
5032                 }
5033
5034                 void ResolveAccessors (EmitContext ec)
5035                 {
5036                         BindingFlags flags = BindingFlags.Public | BindingFlags.Static | BindingFlags.Instance;
5037                         MemberInfo [] group;
5038
5039                         group = TypeManager.MemberLookup (ec.ContainerType, PropertyInfo.DeclaringType,
5040                                                               MemberTypes.Method, flags, "get_" + PropertyInfo.Name);
5041
5042                         //
5043                         // The first method is the closest to us
5044                         //
5045                         if (group != null && group.Length > 0){
5046                                 getter = (MethodInfo) group [0];
5047
5048                                 if (getter.IsStatic)
5049                                         is_static = true;
5050                         }
5051
5052                         //
5053                         // The first method is the closest to us
5054                         //
5055                         group = TypeManager.MemberLookup (ec.ContainerType, PropertyInfo.DeclaringType,
5056                                                           MemberTypes.Method, flags, "set_" + PropertyInfo.Name);
5057                         if (group != null && group.Length > 0){
5058                                 setter = (MethodInfo) group [0];
5059                                 if (setter.IsStatic)
5060                                         is_static = true;
5061                         }
5062                 }
5063
5064                 override public Expression DoResolve (EmitContext ec)
5065                 {
5066                         if (getter == null){
5067                                 Report.Error (30524, loc,
5068                                               "The property '" + PropertyInfo.Name +
5069                                               "' can not be used in " +
5070                                               "this context because it lacks a get accessor");
5071                                 return null;
5072                         }
5073
5074                         if ((instance_expr == null) && ec.IsStatic && !is_static) {
5075                                 SimpleName.Error_ObjectRefRequired (ec, loc, PropertyInfo.Name);
5076                                 return null;
5077                         }
5078
5079                         if (instance_expr != null) {
5080                                 instance_expr = instance_expr.DoResolve (ec);
5081                                 if (instance_expr == null)
5082                                         return null;
5083                         }
5084
5085                         return this;
5086                 }
5087
5088                 override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
5089                 {
5090                         if (setter == null){
5091                                 Report.Error (30526, loc,
5092                                               "The property '" + PropertyInfo.Name +
5093                                               "' can not be used in " +
5094                                               "this context because it lacks a set accessor");
5095                                 return null;
5096                         }
5097
5098                         if (instance_expr != null) {
5099                                 instance_expr = instance_expr.DoResolve (ec);
5100                                 if (instance_expr == null)
5101                                         return null;
5102                         }
5103
5104                         return this;
5105                 }
5106
5107                 override public void Emit (EmitContext ec)
5108                 {
5109                         //
5110                         // Special case: length of single dimension array property is turned into ldlen
5111                         //
5112                         if ((getter == TypeManager.system_int_array_get_length) ||
5113                             (getter == TypeManager.int_array_get_length)){
5114                                 Type iet = instance_expr.Type;
5115
5116                                 //
5117                                 // System.Array.Length can be called, but the Type does not
5118                                 // support invoking GetArrayRank, so test for that case first
5119                                 //
5120                                 if (iet != TypeManager.array_type && (iet.GetArrayRank () == 1)){
5121                                         instance_expr.Emit (ec);
5122                                         ec.ig.Emit (OpCodes.Ldlen);
5123                                         return;
5124                                 }
5125                         }
5126                         if (PropertyArgs == null)
5127                                 PropertyArgs = new ArrayList ();
5128                         Invocation.EmitCall (ec, IsBase, IsStatic, instance_expr, getter, null, PropertyArgs, loc);
5129                 }
5130
5131                 //
5132                 // Implements the IAssignMethod interface for assignments
5133                 //
5134                 public void EmitAssign (EmitContext ec, Expression source)
5135                 {
5136                         Argument arg = new Argument (source, Argument.AType.Expression);
5137                         ArrayList args = new ArrayList ();
5138 //HERE
5139                         args.Add (arg);
5140                         Invocation.EmitCall (ec, IsBase, IsStatic, instance_expr, setter, args, PropertyArgs,loc);
5141                 }
5142
5143                 override public void EmitStatement (EmitContext ec)
5144                 {
5145                         Emit (ec);
5146                         ec.ig.Emit (OpCodes.Pop);
5147                 }
5148         }
5149
5150         /// <summary>
5151         ///   Fully resolved expression that evaluates to an Event
5152         /// </summary>
5153         public class EventExpr : Expression, IMemberExpr {
5154                 public readonly EventInfo EventInfo;
5155                 public Expression instance_expr;
5156
5157                 bool is_static;
5158                 MethodInfo add_accessor, remove_accessor;
5159
5160                 public EventExpr (EventInfo ei, Location loc)
5161                 {
5162                         EventInfo = ei;
5163                         this.loc = loc;
5164                         eclass = ExprClass.EventAccess;
5165
5166                         add_accessor = TypeManager.GetAddMethod (ei);
5167                         remove_accessor = TypeManager.GetRemoveMethod (ei);
5168
5169                         if (add_accessor.IsStatic || remove_accessor.IsStatic)
5170                                 is_static = true;
5171
5172                         if (EventInfo is MyEventBuilder)
5173                                 type = ((MyEventBuilder) EventInfo).EventType;
5174                         else
5175                                 type = EventInfo.EventHandlerType;
5176                 }
5177
5178                 public string Name {
5179                         get {
5180                                 return EventInfo.Name;
5181                         }
5182                 }
5183
5184                 public bool IsInstance {
5185                         get {
5186                                 return !is_static;
5187                         }
5188                 }
5189
5190                 public bool IsStatic {
5191                         get {
5192                                 return is_static;
5193                         }
5194                 }
5195
5196                 public Type DeclaringType {
5197                         get {
5198                                 return EventInfo.DeclaringType;
5199                         }
5200                 }
5201
5202                 public Expression InstanceExpression {
5203                         get {
5204                                 return instance_expr;
5205                         }
5206
5207                         set {
5208                                 instance_expr = value;
5209                         }
5210                 }
5211
5212                 Expression field_expr = null;
5213
5214                 public override Expression DoResolve (EmitContext ec)
5215                 {
5216                         if (instance_expr != null) {
5217                                 instance_expr = instance_expr.DoResolve (ec);
5218                                 if (instance_expr == null)
5219                                         return null;
5220                         }
5221
5222                         if (this.DeclaringType == ec.ContainerType)     {
5223                                 MemberInfo mi = GetFieldFromEvent (this);
5224                                 if (mi == null)
5225                                         return null;
5226                                 field_expr = ExprClassFromMemberInfo (ec, mi, loc);
5227                                 ((FieldExpr) field_expr).InstanceExpression = instance_expr;
5228                                 field_expr = field_expr.DoResolve (ec);
5229                                 if (field_expr == null)
5230                                         return null;
5231                         }
5232
5233                         return this;
5234                 }
5235
5236                 public override void Emit (EmitContext ec)
5237                 {
5238                         if (field_expr != null)
5239                                 field_expr.Emit (ec);
5240                 }
5241
5242                 public void EmitAddOrRemove (EmitContext ec, Expression source)
5243                 {
5244                         Expression handler = ((Binary) source).Right;
5245
5246                         Argument arg = new Argument (handler, Argument.AType.Expression);
5247                         ArrayList args = new ArrayList ();
5248
5249                         args.Add (arg);
5250
5251                         if (((Binary) source).Oper == Binary.Operator.Addition)
5252                                 Invocation.EmitCall (
5253                                         ec, false, IsStatic, instance_expr, add_accessor, args, loc);
5254                         else
5255                                 Invocation.EmitCall (
5256                                         ec, false, IsStatic, instance_expr, remove_accessor, args, loc);
5257                 }
5258         }
5259 }