mcs/gmcs/ecore.cs

   1 //
   2 // ecore.cs: Core of the Expression representation for the intermediate tree.
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //
   7 // (C) 2001, 2002, 2003 Ximian, Inc.
   8 //
   9 //
  10
  11 namespace Mono.CSharp {
  12         using System;
  13         using System.Collections;
  14         using System.Diagnostics;
  15         using System.Reflection;
  16         using System.Reflection.Emit;
  17         using System.Text;
  18
  19         /// <remarks>
  20         ///   The ExprClass class contains the is used to pass the
  21         ///   classification of an expression (value, variable, namespace,
  22         ///   type, method group, property access, event access, indexer access,
  23         ///   nothing).
  24         /// </remarks>
  25         public enum ExprClass : byte {
  26                 Invalid,
  27
  28                 Value,
  29                 Variable,
  30                 Namespace,
  31                 Type,
  32                 MethodGroup,
  33                 PropertyAccess,
  34                 EventAccess,
  35                 IndexerAccess,
  36                 Nothing,
  37         }
  38
  39         /// <remarks>
  40         ///   This is used to tell Resolve in which types of expressions we're
  41         ///   interested.
  42         /// </remarks>
  43         [Flags]
  44         public enum ResolveFlags {
  45                 // Returns Value, Variable, PropertyAccess, EventAccess or IndexerAccess.
  46                 VariableOrValue         = 1,
  47
  48                 // Returns a type expression.
  49                 Type                    = 2,
  50
  51                 // Returns a method group.
  52                 MethodGroup             = 4,
  53
  54                 // Allows SimpleNames to be returned.
  55                 // This is used by MemberAccess to construct long names that can not be
  56                 // partially resolved (namespace-qualified names for example).
  57                 SimpleName              = 8,
  58
  59                 // Mask of all the expression class flags.
  60                 MaskExprClass           = 15,
  61
  62                 // Disable control flow analysis while resolving the expression.
  63                 // This is used when resolving the instance expression of a field expression.
  64                 DisableFlowAnalysis     = 16
  65         }
  66
  67         //
  68         // This is just as a hint to AddressOf of what will be done with the
  69         // address.
  70         [Flags]
  71         public enum AddressOp {
  72                 Store = 1,
  73                 Load  = 2,
  74                 LoadStore = 3
  75         };
  76
  77         /// <summary>
  78         ///   This interface is implemented by variables
  79         /// </summary>
  80         public interface IMemoryLocation {
  81                 /// <summary>
  82                 ///   The AddressOf method should generate code that loads
  83                 ///   the address of the object and leaves it on the stack.
  84                 ///
  85                 ///   The `mode' argument is used to notify the expression
  86                 ///   of whether this will be used to read from the address or
  87                 ///   write to the address.
  88                 ///
  89                 ///   This is just a hint that can be used to provide good error
  90                 ///   reporting, and should have no other side effects.
  91                 /// </summary>
  92                 void AddressOf (EmitContext ec, AddressOp mode);
  93         }
  94
  95         /// <summary>
  96         ///   This interface is implemented by variables
  97         /// </summary>
  98         public interface IVariable {
  99                 VariableInfo VariableInfo {
 100                         get;
 101                 }
 102
 103                 bool VerifyFixed (bool is_expression);
 104         }
 105
 106         /// <summary>
 107         ///   This interface denotes an expression which evaluates to a member
 108         ///   of a struct or a class.
 109         /// </summary>
 110         public interface IMemberExpr
 111         {
 112                 /// <summary>
 113                 ///   The name of this member.
 114                 /// </summary>
 115                 string Name {
 116                         get;
 117                 }
 118
 119                 /// <summary>
 120                 ///   Whether this is an instance member.
 121                 /// </summary>
 122                 bool IsInstance {
 123                         get;
 124                 }
 125
 126                 /// <summary>
 127                 ///   Whether this is a static member.
 128                 /// </summary>
 129                 bool IsStatic {
 130                         get;
 131                 }
 132
 133                 /// <summary>
 134                 ///   The type which declares this member.
 135                 /// </summary>
 136                 Type DeclaringType {
 137                         get;
 138                 }
 139
 140                 /// <summary>
 141                 ///   The instance expression associated with this member, if it's a
 142                 ///   non-static member.
 143                 /// </summary>
 144                 Expression InstanceExpression {
 145                         get; set;
 146                 }
 147         }
 148
 149         /// <remarks>
 150         ///   Base class for expressions
 151         /// </remarks>
 152         public abstract class Expression {
 153                 public ExprClass eclass;
 154                 protected Type type;
 155                 protected Location loc;
 156
 157                 public Type Type {
 158                         get {
 159                                 return type;
 160                         }
 161
 162                         set {
 163                                 type = value;
 164                         }
 165                 }
 166
 167                 public Location Location {
 168                         get {
 169                                 return loc;
 170                         }
 171                 }
 172
 173                 /// <summary>
 174                 ///   Utility wrapper routine for Error, just to beautify the code
 175                 /// </summary>
 176                 public void Error (int error, string s)
 177                 {
 178                         if (!Location.IsNull (loc))
 179                                 Report.Error (error, loc, s);
 180                         else
 181                                 Report.Error (error, s);
 182                 }
 183
 184                 /// <summary>
 185                 ///   Utility wrapper routine for Warning, just to beautify the code
 186                 /// </summary>
 187                 public void Warning (int warning, string s)
 188                 {
 189                         if (!Location.IsNull (loc))
 190                                 Report.Warning (warning, loc, s);
 191                         else
 192                                 Report.Warning (warning, s);
 193                 }
 194
 195                 /// <summary>
 196                 ///   Utility wrapper routine for Warning, only prints the warning if
 197                 ///   warnings of level `level' are enabled.
 198                 /// </summary>
 199                 public void Warning (int warning, int level, string s)
 200                 {
 201                         if (level <= RootContext.WarningLevel)
 202                                 Warning (warning, s);
 203                 }
 204
 205                 /// <summary>
 206                 ///   Performs semantic analysis on the Expression
 207                 /// </summary>
 208                 ///
 209                 /// <remarks>
 210                 ///   The Resolve method is invoked to perform the semantic analysis
 211                 ///   on the node.
 212                 ///
 213                 ///   The return value is an expression (it can be the
 214                 ///   same expression in some cases) or a new
 215                 ///   expression that better represents this node.
 216                 ///
 217                 ///   For example, optimizations of Unary (LiteralInt)
 218                 ///   would return a new LiteralInt with a negated
 219                 ///   value.
 220                 ///
 221                 ///   If there is an error during semantic analysis,
 222                 ///   then an error should be reported (using Report)
 223                 ///   and a null value should be returned.
 224                 ///
 225                 ///   There are two side effects expected from calling
 226                 ///   Resolve(): the the field variable "eclass" should
 227                 ///   be set to any value of the enumeration
 228                 ///   `ExprClass' and the type variable should be set
 229                 ///   to a valid type (this is the type of the
 230                 ///   expression).
 231                 /// </remarks>
 232                 public abstract Expression DoResolve (EmitContext ec);
 233
 234                 public virtual Expression DoResolveLValue (EmitContext ec, Expression right_side)
 235                 {
 236                         return DoResolve (ec);
 237                 }
 238
 239                 //
 240                 // This is used if the expression should be resolved as a type.
 241                 // the default implementation fails.   Use this method in
 242                 // those participants in the SimpleName chain system.
 243                 //
 244                 public virtual Expression ResolveAsTypeStep (EmitContext ec)
 245                 {
 246                         return null;
 247                 }
 248
 249                 //
 250                 // This is used to resolve the expression as a type, a null
 251                 // value will be returned if the expression is not a type
 252                 // reference
 253                 //
 254                 public TypeExpr ResolveAsTypeTerminal (EmitContext ec)
 255                 {
 256                         return ResolveAsTypeStep (ec) as TypeExpr;
 257                 }
 258
 259                 /// <summary>
 260                 ///   Resolves an expression and performs semantic analysis on it.
 261                 /// </summary>
 262                 ///
 263                 /// <remarks>
 264                 ///   Currently Resolve wraps DoResolve to perform sanity
 265                 ///   checking and assertion checking on what we expect from Resolve.
 266                 /// </remarks>
 267                 public Expression Resolve (EmitContext ec, ResolveFlags flags)
 268                 {
 269                         if ((flags & ResolveFlags.MaskExprClass) == ResolveFlags.Type)
 270                                 return ResolveAsTypeStep (ec);
 271
 272                         bool old_do_flow_analysis = ec.DoFlowAnalysis;
 273                         if ((flags & ResolveFlags.DisableFlowAnalysis) != 0)
 274                                 ec.DoFlowAnalysis = false;
 275
 276                         Expression e;
 277                         if (this is SimpleName)
 278                                 e = ((SimpleName) this).DoResolveAllowStatic (ec);
 279                         else
 280                                 e = DoResolve (ec);
 281
 282                         ec.DoFlowAnalysis = old_do_flow_analysis;
 283
 284                         if (e == null)
 285                                 return null;
 286
 287                         if (e is SimpleName){
 288                                 SimpleName s = (SimpleName) e;
 289
 290                                 if ((flags & ResolveFlags.SimpleName) == 0) {
 291                                         MemberLookupFailed (ec, null, ec.ContainerType, s.Name,
 292                                                             ec.DeclSpace.Name, loc);
 293                                         return null;
 294                                 }
 295
 296                                 return s;
 297                         }
 298
 299                         if ((e is TypeExpr) || (e is ComposedCast)) {
 300                                 if ((flags & ResolveFlags.Type) == 0) {
 301                                         e.Error_UnexpectedKind (flags);
 302                                         return null;
 303                                 }
 304
 305                                 return e;
 306                         }
 307
 308                         switch (e.eclass) {
 309                         case ExprClass.Type:
 310                                 if ((flags & ResolveFlags.VariableOrValue) == 0) {
 311                                         e.Error_UnexpectedKind (flags);
 312                                         return null;
 313                                 }
 314                                 break;
 315
 316                         case ExprClass.MethodGroup:
 317                                 if ((flags & ResolveFlags.MethodGroup) == 0) {
 318                                         ((MethodGroupExpr) e).ReportUsageError ();
 319                                         return null;
 320                                 }
 321                                 break;
 322
 323                         case ExprClass.Value:
 324                         case ExprClass.Variable:
 325                         case ExprClass.PropertyAccess:
 326                         case ExprClass.EventAccess:
 327                         case ExprClass.IndexerAccess:
 328                                 if ((flags & ResolveFlags.VariableOrValue) == 0) {
 329                                         Console.WriteLine ("I got: {0} and {1}", e.GetType (), e);
 330                                         Console.WriteLine ("I am {0} and {1}", this.GetType (), this);
 331                                         FieldInfo fi = ((FieldExpr) e).FieldInfo;
 332
 333                                         Console.WriteLine ("{0} and {1}", fi.DeclaringType, fi.Name);
 334                                         e.Error_UnexpectedKind (flags);
 335                                         return null;
 336                                 }
 337                                 break;
 338
 339                         default:
 340                                 throw new Exception ("Expression " + e.GetType () +
 341                                                      " ExprClass is Invalid after resolve");
 342                         }
 343
 344                         if (e.type == null)
 345                                 throw new Exception (
 346                                         "Expression " + e.GetType () +
 347                                         " did not set its type after Resolve\n" +
 348                                         "called from: " + this.GetType ());
 349
 350                         return e;
 351                 }
 352
 353                 /// <summary>
 354                 ///   Resolves an expression and performs semantic analysis on it.
 355                 /// </summary>
 356                 public Expression Resolve (EmitContext ec)
 357                 {
 358                         return Resolve (ec, ResolveFlags.VariableOrValue);
 359                 }
 360
 361                 /// <summary>
 362                 ///   Resolves an expression for LValue assignment
 363                 /// </summary>
 364                 ///
 365                 /// <remarks>
 366                 ///   Currently ResolveLValue wraps DoResolveLValue to perform sanity
 367                 ///   checking and assertion checking on what we expect from Resolve
 368                 /// </remarks>
 369                 public Expression ResolveLValue (EmitContext ec, Expression right_side)
 370                 {
 371                         Expression e = DoResolveLValue (ec, right_side);
 372
 373                         if (e != null){
 374                                 if (e is SimpleName){
 375                                         SimpleName s = (SimpleName) e;
 376                                         MemberLookupFailed (ec, null, ec.ContainerType, s.Name,
 377                                                             ec.DeclSpace.Name, loc);
 378                                         return null;
 379                                 }
 380
 381                                 if (e.eclass == ExprClass.Invalid)
 382                                         throw new Exception ("Expression " + e +
 383                                                              " ExprClass is Invalid after resolve");
 384
 385                                 if (e.eclass == ExprClass.MethodGroup) {
 386                                         ((MethodGroupExpr) e).ReportUsageError ();
 387                                         return null;
 388                                 }
 389
 390                                 if (e.type == null)
 391                                         throw new Exception ("Expression " + e +
 392                                                              " did not set its type after Resolve");
 393                         }
 394
 395                         return e;
 396                 }
 397
 398                 /// <summary>
 399                 ///   Emits the code for the expression
 400                 /// </summary>
 401                 ///
 402                 /// <remarks>
 403                 ///   The Emit method is invoked to generate the code
 404                 ///   for the expression.
 405                 /// </remarks>
 406                 public abstract void Emit (EmitContext ec);
 407
 408                 /// <summary>
 409                 ///   Protected constructor.  Only derivate types should
 410                 ///   be able to be created
 411                 /// </summary>
 412
 413                 protected Expression ()
 414                 {
 415                         eclass = ExprClass.Invalid;
 416                         type = null;
 417                 }
 418
 419                 /// <summary>
 420                 ///   Returns a literalized version of a literal FieldInfo
 421                 /// </summary>
 422                 ///
 423                 /// <remarks>
 424                 ///   The possible return values are:
 425                 ///      IntConstant, UIntConstant
 426                 ///      LongLiteral, ULongConstant
 427                 ///      FloatConstant, DoubleConstant
 428                 ///      StringConstant
 429                 ///
 430                 ///   The value returned is already resolved.
 431                 /// </remarks>
 432                 public static Constant Constantify (object v, Type t)
 433                 {
 434                         if (t == TypeManager.int32_type)
 435                                 return new IntConstant ((int) v);
 436                         else if (t == TypeManager.uint32_type)
 437                                 return new UIntConstant ((uint) v);
 438                         else if (t == TypeManager.int64_type)
 439                                 return new LongConstant ((long) v);
 440                         else if (t == TypeManager.uint64_type)
 441                                 return new ULongConstant ((ulong) v);
 442                         else if (t == TypeManager.float_type)
 443                                 return new FloatConstant ((float) v);
 444                         else if (t == TypeManager.double_type)
 445                                 return new DoubleConstant ((double) v);
 446                         else if (t == TypeManager.string_type)
 447                                 return new StringConstant ((string) v);
 448                         else if (t == TypeManager.short_type)
 449                                 return new ShortConstant ((short)v);
 450                         else if (t == TypeManager.ushort_type)
 451                                 return new UShortConstant ((ushort)v);
 452                         else if (t == TypeManager.sbyte_type)
 453                                 return new SByteConstant (((sbyte)v));
 454                         else if (t == TypeManager.byte_type)
 455                                 return new ByteConstant ((byte)v);
 456                         else if (t == TypeManager.char_type)
 457                                 return new CharConstant ((char)v);
 458                         else if (t == TypeManager.bool_type)
 459                                 return new BoolConstant ((bool) v);
 460                         else if (TypeManager.IsEnumType (t)){
 461                                 Constant e = Constantify (v, TypeManager.TypeToCoreType (v.GetType ()));
 462
 463                                 return new EnumConstant (e, t);
 464                         } else
 465                                 throw new Exception ("Unknown type for constant (" + t +
 466                                                      "), details: " + v);
 467                 }
 468
 469                 /// <summary>
 470                 ///   Returns a fully formed expression after a MemberLookup
 471                 /// </summary>
 472                 public static Expression ExprClassFromMemberInfo (EmitContext ec, MemberInfo mi, Location loc)
 473                 {
 474                         if (mi is EventInfo)
 475                                 return new EventExpr ((EventInfo) mi, loc);
 476                         else if (mi is FieldInfo)
 477                                 return new FieldExpr ((FieldInfo) mi, loc);
 478                         else if (mi is PropertyInfo)
 479                                 return new PropertyExpr (ec, (PropertyInfo) mi, loc);
 480                         else if (mi is Type){
 481                                 return new TypeExpression ((System.Type) mi, loc);
 482                         }
 483
 484                         return null;
 485                 }
 486
 487                 //
 488                 // FIXME: Probably implement a cache for (t,name,current_access_set)?
 489                 //
 490                 // This code could use some optimizations, but we need to do some
 491                 // measurements.  For example, we could use a delegate to `flag' when
 492                 // something can not any longer be a method-group (because it is something
 493                 // else).
 494                 //
 495                 // Return values:
 496                 //     If the return value is an Array, then it is an array of
 497                 //     MethodBases
 498                 //
 499                 //     If the return value is an MemberInfo, it is anything, but a Method
 500                 //
 501                 //     null on error.
 502                 //
 503                 // FIXME: When calling MemberLookup inside an `Invocation', we should pass
 504                 // the arguments here and have MemberLookup return only the methods that
 505                 // match the argument count/type, unlike we are doing now (we delay this
 506                 // decision).
 507                 //
 508                 // This is so we can catch correctly attempts to invoke instance methods
 509                 // from a static body (scan for error 120 in ResolveSimpleName).
 510                 //
 511                 //
 512                 // FIXME: Potential optimization, have a static ArrayList
 513                 //
 514
 515                 public static Expression MemberLookup (EmitContext ec, Type queried_type, string name,
 516                                                        MemberTypes mt, BindingFlags bf, Location loc)
 517                 {
 518                         return MemberLookup (ec, ec.ContainerType, null, queried_type, name, mt, bf, loc);
 519                 }
 520
 521                 //
 522                 // Lookup type `queried_type' for code in class `container_type' with a qualifier of
 523                 // `qualifier_type' or null to lookup members in the current class.
 524                 //
 525
 526                 public static Expression MemberLookup (EmitContext ec, Type container_type,
 527                                                        Type qualifier_type, Type queried_type,
 528                                                        string name, MemberTypes mt,
 529                                                        BindingFlags bf, Location loc)
 530                 {
 531                         MemberInfo [] mi = TypeManager.MemberLookup (container_type, qualifier_type,
 532                                                                      queried_type, mt, bf, name);
 533
 534                         if (mi == null)
 535                                 return null;
 536
 537                         int count = mi.Length;
 538
 539                         if (mi [0] is MethodBase)
 540                                 return new MethodGroupExpr (mi, loc);
 541
 542                         if (count > 1)
 543                                 return null;
 544
 545                         return ExprClassFromMemberInfo (ec, mi [0], loc);
 546                 }
 547
 548                 public const MemberTypes AllMemberTypes =
 549                         MemberTypes.Constructor |
 550                         MemberTypes.Event       |
 551                         MemberTypes.Field       |
 552                         MemberTypes.Method      |
 553                         MemberTypes.NestedType  |
 554                         MemberTypes.Property;
 555
 556                 public const BindingFlags AllBindingFlags =
 557                         BindingFlags.Public |
 558                         BindingFlags.Static |
 559                         BindingFlags.Instance;
 560
 561                 public static Expression MemberLookup (EmitContext ec, Type queried_type,
 562                                                        string name, Location loc)
 563                 {
 564                         return MemberLookup (ec, ec.ContainerType, null, queried_type, name,
 565                                              AllMemberTypes, AllBindingFlags, loc);
 566                 }
 567
 568                 public static Expression MemberLookup (EmitContext ec, Type qualifier_type,
 569                                                        Type queried_type, string name, Location loc)
 570                 {
 571                         return MemberLookup (ec, ec.ContainerType, qualifier_type, queried_type,
 572                                              name, AllMemberTypes, AllBindingFlags, loc);
 573                 }
 574
 575                 public static Expression MethodLookup (EmitContext ec, Type queried_type,
 576                                                        string name, Location loc)
 577                 {
 578                         return MemberLookup (ec, ec.ContainerType, null, queried_type, name,
 579                                              MemberTypes.Method, AllBindingFlags, loc);
 580                 }
 581
 582                 /// <summary>
 583                 ///   This is a wrapper for MemberLookup that is not used to "probe", but
 584                 ///   to find a final definition.  If the final definition is not found, we
 585                 ///   look for private members and display a useful debugging message if we
 586                 ///   find it.
 587                 /// </summary>
 588                 public static Expression MemberLookupFinal (EmitContext ec, Type qualifier_type,
 589                                                             Type queried_type, string name, Location loc)
 590                 {
 591                         return MemberLookupFinal (ec, qualifier_type, queried_type, name,
 592                                                   AllMemberTypes, AllBindingFlags, loc);
 593                 }
 594
 595                 public static Expression MemberLookupFinal (EmitContext ec, Type qualifier_type,
 596                                                             Type queried_type, string name,
 597                                                             MemberTypes mt, BindingFlags bf,
 598                                                             Location loc)
 599                 {
 600                         Expression e;
 601
 602                         int errors = Report.Errors;
 603
 604                         e = MemberLookup (ec, ec.ContainerType, qualifier_type, queried_type,
 605                                           name, mt, bf, loc);
 606
 607                         if (e != null)
 608                                 return e;
 609
 610                         // Error has already been reported.
 611                         if (errors < Report.Errors)
 612                                 return null;
 613
 614                         MemberLookupFailed (ec, qualifier_type, queried_type, name, null, loc);
 615                         return null;
 616                 }
 617
 618                 public static void MemberLookupFailed (EmitContext ec, Type qualifier_type,
 619                                                        Type queried_type, string name,
 620                                                        string class_name, Location loc)
 621                 {
 622                         object lookup = TypeManager.MemberLookup (queried_type, null, queried_type,
 623                                                                   AllMemberTypes, AllBindingFlags |
 624                                                                   BindingFlags.NonPublic, name);
 625
 626                         if (lookup == null) {
 627                                 if (class_name != null)
 628                                         Report.Error (103, loc, "The name `" + name + "' could not be " +
 629                                                       "found in `" + class_name + "'");
 630                                 else
 631                                         Report.Error (
 632                                                 117, loc, "`" + queried_type + "' does not contain a " +
 633                                                 "definition for `" + name + "'");
 634                                 return;
 635                         }
 636
 637                         if ((qualifier_type != null) && (qualifier_type != ec.ContainerType) &&
 638                             ec.ContainerType.IsSubclassOf (qualifier_type)) {
 639                                 // Although a derived class can access protected members of
 640                                 // its base class it cannot do so through an instance of the
 641                                 // base class (CS1540).  If the qualifier_type is a parent of the
 642                                 // ec.ContainerType and the lookup succeeds with the latter one,
 643                                 // then we are in this situation.
 644
 645                                 lookup = TypeManager.MemberLookup (
 646                                         ec.ContainerType, ec.ContainerType, ec.ContainerType,
 647                                         AllMemberTypes, AllBindingFlags, name);
 648
 649                                 if (lookup != null) {
 650                                         Report.Error (
 651                                                 1540, loc, "Cannot access protected member `" +
 652                                                 TypeManager.CSharpName (qualifier_type) + "." +
 653                                                 name + "' " + "via a qualifier of type `" +
 654                                                 TypeManager.CSharpName (qualifier_type) + "'; the " +
 655                                                 "qualifier must be of type `" +
 656                                                 TypeManager.CSharpName (ec.ContainerType) + "' " +
 657                                                 "(or derived from it)");
 658                                         return;
 659                                 }
 660                         }
 661
 662                         if (qualifier_type != null)
 663                                 Report.Error (
 664                                         122, loc, "`" + TypeManager.CSharpName (qualifier_type) + "." +
 665                                         name + "' is inaccessible due to its protection level");
 666                         else
 667                                 Report.Error (
 668                                         122, loc, "`" + name + "' is inaccessible due to its " +
 669                                         "protection level");
 670                 }
 671
 672                 static public MemberInfo GetFieldFromEvent (EventExpr event_expr)
 673                 {
 674                         EventInfo ei = event_expr.EventInfo;
 675
 676                         return TypeManager.GetPrivateFieldOfEvent (ei);
 677                 }
 678
 679                 /// <summary>
 680                 ///   Returns an expression that can be used to invoke operator true
 681                 ///   on the expression if it exists.
 682                 /// </summary>
 683                 static public StaticCallExpr GetOperatorTrue (EmitContext ec, Expression e, Location loc)
 684                 {
 685                         return GetOperatorTrueOrFalse (ec, e, true, loc);
 686                 }
 687
 688                 /// <summary>
 689                 ///   Returns an expression that can be used to invoke operator false
 690                 ///   on the expression if it exists.
 691                 /// </summary>
 692                 static public StaticCallExpr GetOperatorFalse (EmitContext ec, Expression e, Location loc)
 693                 {
 694                         return GetOperatorTrueOrFalse (ec, e, false, loc);
 695                 }
 696
 697                 static StaticCallExpr GetOperatorTrueOrFalse (EmitContext ec, Expression e, bool is_true, Location loc)
 698                 {
 699                         MethodBase method;
 700                         Expression operator_group;
 701
 702                         operator_group = MethodLookup (ec, e.Type, is_true ? "op_True" : "op_False", loc);
 703                         if (operator_group == null)
 704                                 return null;
 705
 706                         ArrayList arguments = new ArrayList ();
 707                         arguments.Add (new Argument (e, Argument.AType.Expression));
 708                         method = Invocation.OverloadResolve (ec, (MethodGroupExpr) operator_group, arguments, loc);
 709
 710                         if (method == null)
 711                                 return null;
 712
 713                         return new StaticCallExpr ((MethodInfo) method, arguments, loc);
 714                 }
 715
 716                 /// <summary>
 717                 ///   Resolves the expression `e' into a boolean expression: either through
 718                 ///   an implicit conversion, or through an `operator true' invocation
 719                 /// </summary>
 720                 public static Expression ResolveBoolean (EmitContext ec, Expression e, Location loc)
 721                 {
 722                         e = e.Resolve (ec);
 723                         if (e == null)
 724                                 return null;
 725
 726                         Expression converted = e;
 727                         if (e.Type != TypeManager.bool_type)
 728                                 converted = Convert.ImplicitConversion (ec, e, TypeManager.bool_type, new Location (-1));
 729
 730                         //
 731                         // If no implicit conversion to bool exists, try using `operator true'
 732                         //
 733                         if (converted == null){
 734                                 Expression operator_true = Expression.GetOperatorTrue (ec, e, loc);
 735                                 if (operator_true == null){
 736                                         Report.Error (
 737                                                 31, loc, "Can not convert the expression to a boolean");
 738                                         return null;
 739                                 }
 740                                 e = operator_true;
 741                         } else
 742                                 e = converted;
 743
 744                         return e;
 745                 }
 746
 747                 static string ExprClassName (ExprClass c)
 748                 {
 749                         switch (c){
 750                         case ExprClass.Invalid:
 751                                 return "Invalid";
 752                         case ExprClass.Value:
 753                                 return "value";
 754                         case ExprClass.Variable:
 755                                 return "variable";
 756                         case ExprClass.Namespace:
 757                                 return "namespace";
 758                         case ExprClass.Type:
 759                                 return "type";
 760                         case ExprClass.MethodGroup:
 761                                 return "method group";
 762                         case ExprClass.PropertyAccess:
 763                                 return "property access";
 764                         case ExprClass.EventAccess:
 765                                 return "event access";
 766                         case ExprClass.IndexerAccess:
 767                                 return "indexer access";
 768                         case ExprClass.Nothing:
 769                                 return "null";
 770                         }
 771                         throw new Exception ("Should not happen");
 772                 }
 773
 774                 /// <summary>
 775                 ///   Reports that we were expecting `expr' to be of class `expected'
 776                 /// </summary>
 777                 public void Error_UnexpectedKind (string expected)
 778                 {
 779                         string kind = "Unknown";
 780
 781                         kind = ExprClassName (eclass);
 782
 783                         Error (118, "Expression denotes a `" + kind +
 784                                "' where a `" + expected + "' was expected");
 785                 }
 786
 787                 public void Error_UnexpectedKind (ResolveFlags flags)
 788                 {
 789                         ArrayList valid = new ArrayList (10);
 790
 791                         if ((flags & ResolveFlags.VariableOrValue) != 0) {
 792                                 valid.Add ("variable");
 793                                 valid.Add ("value");
 794                         }
 795
 796                         if ((flags & ResolveFlags.Type) != 0)
 797                                 valid.Add ("type");
 798
 799                         if ((flags & ResolveFlags.MethodGroup) != 0)
 800                                 valid.Add ("method group");
 801
 802                         if ((flags & ResolveFlags.SimpleName) != 0)
 803                                 valid.Add ("simple name");
 804
 805                         if (valid.Count == 0)
 806                                 valid.Add ("unknown");
 807
 808                         StringBuilder sb = new StringBuilder ();
 809                         for (int i = 0; i < valid.Count; i++) {
 810                                 if (i > 0)
 811                                         sb.Append (", ");
 812                                 else if (i == valid.Count)
 813                                         sb.Append (" or ");
 814                                 sb.Append (valid [i]);
 815                         }
 816
 817                         string kind = ExprClassName (eclass);
 818
 819                         Error (119, "Expression denotes a `" + kind + "' where " +
 820                                "a `" + sb.ToString () + "' was expected");
 821                 }
 822
 823                 static void Error_ConstantValueCannotBeConverted (Location l, string val, Type t)
 824                 {
 825                         Report.Error (31, l, "Constant value `" + val + "' cannot be converted to " +
 826                                       TypeManager.CSharpName (t));
 827                 }
 828
 829                 public static void UnsafeError (Location loc)
 830                 {
 831                         Report.Error (214, loc, "Pointers may only be used in an unsafe context");
 832                 }
 833
 834                 /// <summary>
 835                 ///   Converts the IntConstant, UIntConstant, LongConstant or
 836                 ///   ULongConstant into the integral target_type.   Notice
 837                 ///   that we do not return an `Expression' we do return
 838                 ///   a boxed integral type.
 839                 ///
 840                 ///   FIXME: Since I added the new constants, we need to
 841                 ///   also support conversions from CharConstant, ByteConstant,
 842                 ///   SByteConstant, UShortConstant, ShortConstant
 843                 ///
 844                 ///   This is used by the switch statement, so the domain
 845                 ///   of work is restricted to the literals above, and the
 846                 ///   targets are int32, uint32, char, byte, sbyte, ushort,
 847                 ///   short, uint64 and int64
 848                 /// </summary>
 849                 public static object ConvertIntLiteral (Constant c, Type target_type, Location loc)
 850                 {
 851                         if (!Convert.ImplicitStandardConversionExists (c, target_type)){
 852                                 Convert.Error_CannotImplicitConversion (loc, c.Type, target_type);
 853                                 return null;
 854                         }
 855
 856                         string s = "";
 857
 858                         if (c.Type == target_type)
 859                                 return ((Constant) c).GetValue ();
 860
 861                         //
 862                         // Make into one of the literals we handle, we dont really care
 863                         // about this value as we will just return a few limited types
 864                         //
 865                         if (c is EnumConstant)
 866                                 c = ((EnumConstant)c).WidenToCompilerConstant ();
 867
 868                         if (c is IntConstant){
 869                                 int v = ((IntConstant) c).Value;
 870
 871                                 if (target_type == TypeManager.uint32_type){
 872                                         if (v >= 0)
 873                                                 return (uint) v;
 874                                 } else if (target_type == TypeManager.char_type){
 875                                         if (v >= Char.MinValue && v <= Char.MaxValue)
 876                                                 return (char) v;
 877                                 } else if (target_type == TypeManager.byte_type){
 878                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
 879                                                 return (byte) v;
 880                                 } else if (target_type == TypeManager.sbyte_type){
 881                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
 882                                                 return (sbyte) v;
 883                                 } else if (target_type == TypeManager.short_type){
 884                                         if (v >= Int16.MinValue && v <= UInt16.MaxValue)
 885                                                 return (short) v;
 886                                 } else if (target_type == TypeManager.ushort_type){
 887                                         if (v >= UInt16.MinValue && v <= UInt16.MaxValue)
 888                                                 return (ushort) v;
 889                                 } else if (target_type == TypeManager.int64_type)
 890                                         return (long) v;
 891                                 else if (target_type == TypeManager.uint64_type){
 892                                         if (v > 0)
 893                                                 return (ulong) v;
 894                                 }
 895
 896                                 s = v.ToString ();
 897                         } else if (c is UIntConstant){
 898                                 uint v = ((UIntConstant) c).Value;
 899
 900                                 if (target_type == TypeManager.int32_type){
 901                                         if (v <= Int32.MaxValue)
 902                                                 return (int) v;
 903                                 } else if (target_type == TypeManager.char_type){
 904                                         if (v >= Char.MinValue && v <= Char.MaxValue)
 905                                                 return (char) v;
 906                                 } else if (target_type == TypeManager.byte_type){
 907                                         if (v <= Byte.MaxValue)
 908                                                 return (byte) v;
 909                                 } else if (target_type == TypeManager.sbyte_type){
 910                                         if (v <= SByte.MaxValue)
 911                                                 return (sbyte) v;
 912                                 } else if (target_type == TypeManager.short_type){
 913                                         if (v <= UInt16.MaxValue)
 914                                                 return (short) v;
 915                                 } else if (target_type == TypeManager.ushort_type){
 916                                         if (v <= UInt16.MaxValue)
 917                                                 return (ushort) v;
 918                                 } else if (target_type == TypeManager.int64_type)
 919                                         return (long) v;
 920                                 else if (target_type == TypeManager.uint64_type)
 921                                         return (ulong) v;
 922                                 s = v.ToString ();
 923                         } else if (c is LongConstant){
 924                                 long v = ((LongConstant) c).Value;
 925
 926                                 if (target_type == TypeManager.int32_type){
 927                                         if (v >= UInt32.MinValue && v <= UInt32.MaxValue)
 928                                                 return (int) v;
 929                                 } else if (target_type == TypeManager.uint32_type){
 930                                         if (v >= 0 && v <= UInt32.MaxValue)
 931                                                 return (uint) v;
 932                                 } else if (target_type == TypeManager.char_type){
 933                                         if (v >= Char.MinValue && v <= Char.MaxValue)
 934                                                 return (char) v;
 935                                 } else if (target_type == TypeManager.byte_type){
 936                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
 937                                                 return (byte) v;
 938                                 } else if (target_type == TypeManager.sbyte_type){
 939                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
 940                                                 return (sbyte) v;
 941                                 } else if (target_type == TypeManager.short_type){
 942                                         if (v >= Int16.MinValue && v <= UInt16.MaxValue)
 943                                                 return (short) v;
 944                                 } else if (target_type == TypeManager.ushort_type){
 945                                         if (v >= UInt16.MinValue && v <= UInt16.MaxValue)
 946                                                 return (ushort) v;
 947                                 } else if (target_type == TypeManager.uint64_type){
 948                                         if (v > 0)
 949                                                 return (ulong) v;
 950                                 }
 951                                 s = v.ToString ();
 952                         } else if (c is ULongConstant){
 953                                 ulong v = ((ULongConstant) c).Value;
 954
 955                                 if (target_type == TypeManager.int32_type){
 956                                         if (v <= Int32.MaxValue)
 957                                                 return (int) v;
 958                                 } else if (target_type == TypeManager.uint32_type){
 959                                         if (v <= UInt32.MaxValue)
 960                                                 return (uint) v;
 961                                 } else if (target_type == TypeManager.char_type){
 962                                         if (v >= Char.MinValue && v <= Char.MaxValue)
 963                                                 return (char) v;
 964                                 } else if (target_type == TypeManager.byte_type){
 965                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
 966                                                 return (byte) v;
 967                                 } else if (target_type == TypeManager.sbyte_type){
 968                                         if (v <= (int) SByte.MaxValue)
 969                                                 return (sbyte) v;
 970                                 } else if (target_type == TypeManager.short_type){
 971                                         if (v <= UInt16.MaxValue)
 972                                                 return (short) v;
 973                                 } else if (target_type == TypeManager.ushort_type){
 974                                         if (v <= UInt16.MaxValue)
 975                                                 return (ushort) v;
 976                                 } else if (target_type == TypeManager.int64_type){
 977                                         if (v <= Int64.MaxValue)
 978                                                 return (long) v;
 979                                 }
 980                                 s = v.ToString ();
 981                         } else if (c is ByteConstant){
 982                                 byte v = ((ByteConstant) c).Value;
 983
 984                                 if (target_type == TypeManager.int32_type)
 985                                         return (int) v;
 986                                 else if (target_type == TypeManager.uint32_type)
 987                                         return (uint) v;
 988                                 else if (target_type == TypeManager.char_type)
 989                                         return (char) v;
 990                                 else if (target_type == TypeManager.sbyte_type){
 991                                         if (v <= SByte.MaxValue)
 992                                                 return (sbyte) v;
 993                                 } else if (target_type == TypeManager.short_type)
 994                                         return (short) v;
 995                                 else if (target_type == TypeManager.ushort_type)
 996                                         return (ushort) v;
 997                                 else if (target_type == TypeManager.int64_type)
 998                                         return (long) v;
 999                                 else if (target_type == TypeManager.uint64_type)
1000                                         return (ulong) v;
1001                                 s = v.ToString ();
1002                         } else if (c is SByteConstant){
1003                                 sbyte v = ((SByteConstant) c).Value;
1004
1005                                 if (target_type == TypeManager.int32_type)
1006                                         return (int) v;
1007                                 else if (target_type == TypeManager.uint32_type){
1008                                         if (v >= 0)
1009                                                 return (uint) v;
1010                                 } else if (target_type == TypeManager.char_type){
1011                                         if (v >= 0)
1012                                                 return (char) v;
1013                                 } else if (target_type == TypeManager.byte_type){
1014                                         if (v >= 0)
1015                                                 return (byte) v;
1016                                 } else if (target_type == TypeManager.short_type)
1017                                         return (short) v;
1018                                 else if (target_type == TypeManager.ushort_type){
1019                                         if (v >= 0)
1020                                                 return (ushort) v;
1021                                 } else if (target_type == TypeManager.int64_type)
1022                                         return (long) v;
1023                                 else if (target_type == TypeManager.uint64_type){
1024                                         if (v >= 0)
1025                                                 return (ulong) v;
1026                                 }
1027                                 s = v.ToString ();
1028                         } else if (c is ShortConstant){
1029                                 short v = ((ShortConstant) c).Value;
1030
1031                                 if (target_type == TypeManager.int32_type){
1032                                         return (int) v;
1033                                 } else if (target_type == TypeManager.uint32_type){
1034                                         if (v >= 0)
1035                                                 return (uint) v;
1036                                 } else if (target_type == TypeManager.char_type){
1037                                         if (v >= 0)
1038                                                 return (char) v;
1039                                 } else if (target_type == TypeManager.byte_type){
1040                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
1041                                                 return (byte) v;
1042                                 } else if (target_type == TypeManager.sbyte_type){
1043                                         if (v >= SByte.MinValue && v <= SByte.MaxValue)
1044                                                 return (sbyte) v;
1045                                 } else if (target_type == TypeManager.ushort_type){
1046                                         if (v >= 0)
1047                                                 return (ushort) v;
1048                                 } else if (target_type == TypeManager.int64_type)
1049                                         return (long) v;
1050                                 else if (target_type == TypeManager.uint64_type)
1051                                         return (ulong) v;
1052
1053                                 s = v.ToString ();
1054                         } else if (c is UShortConstant){
1055                                 ushort v = ((UShortConstant) c).Value;
1056
1057                                 if (target_type == TypeManager.int32_type)
1058                                         return (int) v;
1059                                 else if (target_type == TypeManager.uint32_type)
1060                                         return (uint) v;
1061                                 else if (target_type == TypeManager.char_type){
1062                                         if (v >= Char.MinValue && v <= Char.MaxValue)
1063                                                 return (char) v;
1064                                 } else if (target_type == TypeManager.byte_type){
1065                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
1066                                                 return (byte) v;
1067                                 } else if (target_type == TypeManager.sbyte_type){
1068                                         if (v <= SByte.MaxValue)
1069                                                 return (byte) v;
1070                                 } else if (target_type == TypeManager.short_type){
1071                                         if (v <= Int16.MaxValue)
1072                                                 return (short) v;
1073                                 } else if (target_type == TypeManager.int64_type)
1074                                         return (long) v;
1075                                 else if (target_type == TypeManager.uint64_type)
1076                                         return (ulong) v;
1077
1078                                 s = v.ToString ();
1079                         } else if (c is CharConstant){
1080                                 char v = ((CharConstant) c).Value;
1081
1082                                 if (target_type == TypeManager.int32_type)
1083                                         return (int) v;
1084                                 else if (target_type == TypeManager.uint32_type)
1085                                         return (uint) v;
1086                                 else if (target_type == TypeManager.byte_type){
1087                                         if (v >= Byte.MinValue && v <= Byte.MaxValue)
1088                                                 return (byte) v;
1089                                 } else if (target_type == TypeManager.sbyte_type){
1090                                         if (v <= SByte.MaxValue)
1091                                                 return (sbyte) v;
1092                                 } else if (target_type == TypeManager.short_type){
1093                                         if (v <= Int16.MaxValue)
1094                                                 return (short) v;
1095                                 } else if (target_type == TypeManager.ushort_type)
1096                                         return (short) v;
1097                                 else if (target_type == TypeManager.int64_type)
1098                                         return (long) v;
1099                                 else if (target_type == TypeManager.uint64_type)
1100                                         return (ulong) v;
1101
1102                                 s = v.ToString ();
1103                         }
1104                         Error_ConstantValueCannotBeConverted (loc, s, target_type);
1105                         return null;
1106                 }
1107
1108                 //
1109                 // Load the object from the pointer.
1110                 //
1111                 public static void LoadFromPtr (ILGenerator ig, Type t)
1112                 {
1113                         if (t == TypeManager.int32_type)
1114                                 ig.Emit (OpCodes.Ldind_I4);
1115                         else if (t == TypeManager.uint32_type)
1116                                 ig.Emit (OpCodes.Ldind_U4);
1117                         else if (t == TypeManager.short_type)
1118                                 ig.Emit (OpCodes.Ldind_I2);
1119                         else if (t == TypeManager.ushort_type)
1120                                 ig.Emit (OpCodes.Ldind_U2);
1121                         else if (t == TypeManager.char_type)
1122                                 ig.Emit (OpCodes.Ldind_U2);
1123                         else if (t == TypeManager.byte_type)
1124                                 ig.Emit (OpCodes.Ldind_U1);
1125                         else if (t == TypeManager.sbyte_type)
1126                                 ig.Emit (OpCodes.Ldind_I1);
1127                         else if (t == TypeManager.uint64_type)
1128                                 ig.Emit (OpCodes.Ldind_I8);
1129                         else if (t == TypeManager.int64_type)
1130                                 ig.Emit (OpCodes.Ldind_I8);
1131                         else if (t == TypeManager.float_type)
1132                                 ig.Emit (OpCodes.Ldind_R4);
1133                         else if (t == TypeManager.double_type)
1134                                 ig.Emit (OpCodes.Ldind_R8);
1135                         else if (t == TypeManager.bool_type)
1136                                 ig.Emit (OpCodes.Ldind_I1);
1137                         else if (t == TypeManager.intptr_type)
1138                                 ig.Emit (OpCodes.Ldind_I);
1139                         else if (TypeManager.IsEnumType (t)) {
1140                                 if (t == TypeManager.enum_type)
1141                                         ig.Emit (OpCodes.Ldind_Ref);
1142                                 else
1143                                         LoadFromPtr (ig, TypeManager.EnumToUnderlying (t));
1144                         } else if (t.IsValueType)
1145                                 ig.Emit (OpCodes.Ldobj, t);
1146                         else if (t.IsPointer)
1147                                 ig.Emit (OpCodes.Ldind_I);
1148                         else
1149                                 ig.Emit (OpCodes.Ldind_Ref);
1150                 }
1151
1152                 //
1153                 // The stack contains the pointer and the value of type `type'
1154                 //
1155                 public static void StoreFromPtr (ILGenerator ig, Type type)
1156                 {
1157                         if (TypeManager.IsEnumType (type))
1158                                 type = TypeManager.EnumToUnderlying (type);
1159                         if (type == TypeManager.int32_type || type == TypeManager.uint32_type)
1160                                 ig.Emit (OpCodes.Stind_I4);
1161                         else if (type == TypeManager.int64_type || type == TypeManager.uint64_type)
1162                                 ig.Emit (OpCodes.Stind_I8);
1163                         else if (type == TypeManager.char_type || type == TypeManager.short_type ||
1164                                  type == TypeManager.ushort_type)
1165                                 ig.Emit (OpCodes.Stind_I2);
1166                         else if (type == TypeManager.float_type)
1167                                 ig.Emit (OpCodes.Stind_R4);
1168                         else if (type == TypeManager.double_type)
1169                                 ig.Emit (OpCodes.Stind_R8);
1170                         else if (type == TypeManager.byte_type || type == TypeManager.sbyte_type ||
1171                                  type == TypeManager.bool_type)
1172                                 ig.Emit (OpCodes.Stind_I1);
1173                         else if (type == TypeManager.intptr_type)
1174                                 ig.Emit (OpCodes.Stind_I);
1175                         else if (type.IsValueType)
1176                                 ig.Emit (OpCodes.Stobj, type);
1177                         else
1178                                 ig.Emit (OpCodes.Stind_Ref);
1179                 }
1180
1181                 //
1182                 // Returns the size of type `t' if known, otherwise, 0
1183                 //
1184                 public static int GetTypeSize (Type t)
1185                 {
1186                         t = TypeManager.TypeToCoreType (t);
1187                         if (t == TypeManager.int32_type ||
1188                             t == TypeManager.uint32_type ||
1189                             t == TypeManager.float_type)
1190                                 return 4;
1191                         else if (t == TypeManager.int64_type ||
1192                                  t == TypeManager.uint64_type ||
1193                                  t == TypeManager.double_type)
1194                                 return 8;
1195                         else if (t == TypeManager.byte_type ||
1196                                  t == TypeManager.sbyte_type ||
1197                                  t == TypeManager.bool_type)
1198                                 return 1;
1199                         else if (t == TypeManager.short_type ||
1200                                  t == TypeManager.char_type ||
1201                                  t == TypeManager.ushort_type)
1202                                 return 2;
1203                         else if (t == TypeManager.decimal_type)
1204                                 return 16;
1205                         else
1206                                 return 0;
1207                 }
1208
1209                 //
1210                 // Default implementation of IAssignMethod.CacheTemporaries
1211                 //
1212                 public void CacheTemporaries (EmitContext ec)
1213                 {
1214                 }
1215
1216                 static void Error_NegativeArrayIndex (Location loc)
1217                 {
1218                         Report.Error (284, loc, "Can not create array with a negative size");
1219                 }
1220
1221                 //
1222                 // Converts `source' to an int, uint, long or ulong.
1223                 //
1224                 public Expression ExpressionToArrayArgument (EmitContext ec, Expression source, Location loc)
1225                 {
1226                         Expression target;
1227
1228                         bool old_checked = ec.CheckState;
1229                         ec.CheckState = true;
1230
1231                         target = Convert.ImplicitConversion (ec, source, TypeManager.int32_type, loc);
1232                         if (target == null){
1233                                 target = Convert.ImplicitConversion (ec, source, TypeManager.uint32_type, loc);
1234                                 if (target == null){
1235                                         target = Convert.ImplicitConversion (ec, source, TypeManager.int64_type, loc);
1236                                         if (target == null){
1237                                                 target = Convert.ImplicitConversion (ec, source, TypeManager.uint64_type, loc);
1238                                                 if (target == null)
1239                                                         Convert.Error_CannotImplicitConversion (loc, source.Type, TypeManager.int32_type);
1240                                         }
1241                                 }
1242                         }
1243                         ec.CheckState = old_checked;
1244
1245                         //
1246                         // Only positive constants are allowed at compile time
1247                         //
1248                         if (target is Constant){
1249                                 if (target is IntConstant){
1250                                         if (((IntConstant) target).Value < 0){
1251                                                 Error_NegativeArrayIndex (loc);
1252                                                 return null;
1253                                         }
1254                                 }
1255
1256                                 if (target is LongConstant){
1257                                         if (((LongConstant) target).Value < 0){
1258                                                 Error_NegativeArrayIndex (loc);
1259                                                 return null;
1260                                         }
1261                                 }
1262
1263                         }
1264
1265                         return target;
1266                 }
1267
1268         }
1269
1270         /// <summary>
1271         ///   This is just a base class for expressions that can
1272         ///   appear on statements (invocations, object creation,
1273         ///   assignments, post/pre increment and decrement).  The idea
1274         ///   being that they would support an extra Emition interface that
1275         ///   does not leave a result on the stack.
1276         /// </summary>
1277         public abstract class ExpressionStatement : Expression {
1278
1279                 public virtual ExpressionStatement ResolveStatement (EmitContext ec)
1280                 {
1281                         Expression e = Resolve (ec);
1282                         if (e == null)
1283                                 return null;
1284
1285                         ExpressionStatement es = e as ExpressionStatement;
1286                         if (es == null)
1287                                 Error (201, "Only assignment, call, increment, decrement and new object " +
1288                                        "expressions can be used as a statement");
1289
1290                         return es;
1291                 }
1292
1293                 /// <summary>
1294                 ///   Requests the expression to be emitted in a `statement'
1295                 ///   context.  This means that no new value is left on the
1296                 ///   stack after invoking this method (constrasted with
1297                 ///   Emit that will always leave a value on the stack).
1298                 /// </summary>
1299                 public abstract void EmitStatement (EmitContext ec);
1300         }
1301
1302         /// <summary>
1303         ///   This kind of cast is used to encapsulate the child
1304         ///   whose type is child.Type into an expression that is
1305         ///   reported to return "return_type".  This is used to encapsulate
1306         ///   expressions which have compatible types, but need to be dealt
1307         ///   at higher levels with.
1308         ///
1309         ///   For example, a "byte" expression could be encapsulated in one
1310         ///   of these as an "unsigned int".  The type for the expression
1311         ///   would be "unsigned int".
1312         ///
1313         /// </summary>
1314         public class EmptyCast : Expression {
1315                 protected Expression child;
1316
1317                 public EmptyCast (Expression child, Type return_type)
1318                 {
1319                         eclass = child.eclass;
1320                         type = return_type;
1321                         this.child = child;
1322                 }
1323
1324                 public override Expression DoResolve (EmitContext ec)
1325                 {
1326                         // This should never be invoked, we are born in fully
1327                         // initialized state.
1328
1329                         return this;
1330                 }
1331
1332                 public override void Emit (EmitContext ec)
1333                 {
1334                         child.Emit (ec);
1335                 }
1336         }
1337
1338         //
1339         // We need to special case this since an empty cast of
1340         // a NullLiteral is still a Constant
1341         //
1342         public class NullCast : Constant {
1343                 protected Expression child;
1344
1345                 public NullCast (Expression child, Type return_type)
1346                 {
1347                         eclass = child.eclass;
1348                         type = return_type;
1349                         this.child = child;
1350                 }
1351
1352                 override public string AsString ()
1353                 {
1354                         return "null";
1355                 }
1356
1357                 public override object GetValue ()
1358                 {
1359                         return null;
1360                 }
1361
1362                 public override Expression DoResolve (EmitContext ec)
1363                 {
1364                         // This should never be invoked, we are born in fully
1365                         // initialized state.
1366
1367                         return this;
1368                 }
1369
1370                 public override void Emit (EmitContext ec)
1371                 {
1372                         child.Emit (ec);
1373                 }
1374         }
1375
1376
1377         /// <summary>
1378         ///  This class is used to wrap literals which belong inside Enums
1379         /// </summary>
1380         public class EnumConstant : Constant {
1381                 public Constant Child;
1382
1383                 public EnumConstant (Constant child, Type enum_type)
1384                 {
1385                         eclass = child.eclass;
1386                         this.Child = child;
1387                         type = enum_type;
1388                 }
1389
1390                 public override Expression DoResolve (EmitContext ec)
1391                 {
1392                         // This should never be invoked, we are born in fully
1393                         // initialized state.
1394
1395                         return this;
1396                 }
1397
1398                 public override void Emit (EmitContext ec)
1399                 {
1400                         Child.Emit (ec);
1401                 }
1402
1403                 public override object GetValue ()
1404                 {
1405                         return Child.GetValue ();
1406                 }
1407
1408                 //
1409                 // Converts from one of the valid underlying types for an enumeration
1410                 // (int32, uint32, int64, uint64, short, ushort, byte, sbyte) to
1411                 // one of the internal compiler literals: Int/UInt/Long/ULong Literals.
1412                 //
1413                 public Constant WidenToCompilerConstant ()
1414                 {
1415                         Type t = TypeManager.EnumToUnderlying (Child.Type);
1416                         object v = ((Constant) Child).GetValue ();;
1417
1418                         if (t == TypeManager.int32_type)
1419                                 return new IntConstant ((int) v);
1420                         if (t == TypeManager.uint32_type)
1421                                 return new UIntConstant ((uint) v);
1422                         if (t == TypeManager.int64_type)
1423                                 return new LongConstant ((long) v);
1424                         if (t == TypeManager.uint64_type)
1425                                 return new ULongConstant ((ulong) v);
1426                         if (t == TypeManager.short_type)
1427                                 return new ShortConstant ((short) v);
1428                         if (t == TypeManager.ushort_type)
1429                                 return new UShortConstant ((ushort) v);
1430                         if (t == TypeManager.byte_type)
1431                                 return new ByteConstant ((byte) v);
1432                         if (t == TypeManager.sbyte_type)
1433                                 return new SByteConstant ((sbyte) v);
1434
1435                         throw new Exception ("Invalid enumeration underlying type: " + t);
1436                 }
1437
1438                 //
1439                 // Extracts the value in the enumeration on its native representation
1440                 //
1441                 public object GetPlainValue ()
1442                 {
1443                         Type t = TypeManager.EnumToUnderlying (Child.Type);
1444                         object v = ((Constant) Child).GetValue ();;
1445
1446                         if (t == TypeManager.int32_type)
1447                                 return (int) v;
1448                         if (t == TypeManager.uint32_type)
1449                                 return (uint) v;
1450                         if (t == TypeManager.int64_type)
1451                                 return (long) v;
1452                         if (t == TypeManager.uint64_type)
1453                                 return (ulong) v;
1454                         if (t == TypeManager.short_type)
1455                                 return (short) v;
1456                         if (t == TypeManager.ushort_type)
1457                                 return (ushort) v;
1458                         if (t == TypeManager.byte_type)
1459                                 return (byte) v;
1460                         if (t == TypeManager.sbyte_type)
1461                                 return (sbyte) v;
1462
1463                         return null;
1464                 }
1465
1466                 public override string AsString ()
1467                 {
1468                         return Child.AsString ();
1469                 }
1470
1471                 public override DoubleConstant ConvertToDouble ()
1472                 {
1473                         return Child.ConvertToDouble ();
1474                 }
1475
1476                 public override FloatConstant ConvertToFloat ()
1477                 {
1478                         return Child.ConvertToFloat ();
1479                 }
1480
1481                 public override ULongConstant ConvertToULong ()
1482                 {
1483                         return Child.ConvertToULong ();
1484                 }
1485
1486                 public override LongConstant ConvertToLong ()
1487                 {
1488                         return Child.ConvertToLong ();
1489                 }
1490
1491                 public override UIntConstant ConvertToUInt ()
1492                 {
1493                         return Child.ConvertToUInt ();
1494                 }
1495
1496                 public override IntConstant ConvertToInt ()
1497                 {
1498                         return Child.ConvertToInt ();
1499                 }
1500         }
1501
1502         /// <summary>
1503         ///   This kind of cast is used to encapsulate Value Types in objects.
1504         ///
1505         ///   The effect of it is to box the value type emitted by the previous
1506         ///   operation.
1507         /// </summary>
1508         public class BoxedCast : EmptyCast {
1509
1510                 public BoxedCast (Expression expr)
1511                         : base (expr, TypeManager.object_type)
1512                 {
1513                 }
1514
1515                 public BoxedCast (Expression expr, Type target_type)
1516                         : base (expr, target_type)
1517                 {
1518                 }
1519
1520                 public override Expression DoResolve (EmitContext ec)
1521                 {
1522                         // This should never be invoked, we are born in fully
1523                         // initialized state.
1524
1525                         return this;
1526                 }
1527
1528                 public override void Emit (EmitContext ec)
1529                 {
1530                         base.Emit (ec);
1531
1532                         ec.ig.Emit (OpCodes.Box, child.Type);
1533                 }
1534         }
1535
1536         public class UnboxCast : EmptyCast {
1537                 public UnboxCast (Expression expr, Type return_type)
1538                         : base (expr, return_type)
1539                 {
1540                 }
1541
1542                 public override Expression DoResolve (EmitContext ec)
1543                 {
1544                         // This should never be invoked, we are born in fully
1545                         // initialized state.
1546
1547                         return this;
1548                 }
1549
1550                 public override void Emit (EmitContext ec)
1551                 {
1552                         Type t = type;
1553                         ILGenerator ig = ec.ig;
1554
1555                         base.Emit (ec);
1556                         ig.Emit (OpCodes.Unbox, t);
1557
1558                         LoadFromPtr (ig, t);
1559                 }
1560         }
1561
1562         /// <summary>
1563         ///   This is used to perform explicit numeric conversions.
1564         ///
1565         ///   Explicit numeric conversions might trigger exceptions in a checked
1566         ///   context, so they should generate the conv.ovf opcodes instead of
1567         ///   conv opcodes.
1568         /// </summary>
1569         public class ConvCast : EmptyCast {
1570                 public enum Mode : byte {
1571                         I1_U1, I1_U2, I1_U4, I1_U8, I1_CH,
1572                         U1_I1, U1_CH,
1573                         I2_I1, I2_U1, I2_U2, I2_U4, I2_U8, I2_CH,
1574                         U2_I1, U2_U1, U2_I2, U2_CH,
1575                         I4_I1, I4_U1, I4_I2, I4_U2, I4_U4, I4_U8, I4_CH,
1576                         U4_I1, U4_U1, U4_I2, U4_U2, U4_I4, U4_CH,
1577                         I8_I1, I8_U1, I8_I2, I8_U2, I8_I4, I8_U4, I8_U8, I8_CH,
1578                         U8_I1, U8_U1, U8_I2, U8_U2, U8_I4, U8_U4, U8_I8, U8_CH,
1579                         CH_I1, CH_U1, CH_I2,
1580                         R4_I1, R4_U1, R4_I2, R4_U2, R4_I4, R4_U4, R4_I8, R4_U8, R4_CH,
1581                         R8_I1, R8_U1, R8_I2, R8_U2, R8_I4, R8_U4, R8_I8, R8_U8, R8_CH, R8_R4
1582                 }
1583
1584                 Mode mode;
1585                 bool checked_state;
1586
1587                 public ConvCast (EmitContext ec, Expression child, Type return_type, Mode m)
1588                         : base (child, return_type)
1589                 {
1590                         checked_state = ec.CheckState;
1591                         mode = m;
1592                 }
1593
1594                 public override Expression DoResolve (EmitContext ec)
1595                 {
1596                         // This should never be invoked, we are born in fully
1597                         // initialized state.
1598
1599                         return this;
1600                 }
1601
1602                 public override string ToString ()
1603                 {
1604                         return String.Format ("ConvCast ({0}, {1})", mode, child);
1605                 }
1606
1607                 public override void Emit (EmitContext ec)
1608                 {
1609                         ILGenerator ig = ec.ig;
1610
1611                         base.Emit (ec);
1612
1613                         if (checked_state){
1614                                 switch (mode){
1615                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1616                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1617                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1618                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1619                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1620
1621                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1622                                 case Mode.U1_CH: /* nothing */ break;
1623
1624                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1625                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1626                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1627                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1628                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1629                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1630
1631                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1632                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1633                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1634                                 case Mode.U2_CH: /* nothing */ break;
1635
1636                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1637                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1638                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
1639                                 case Mode.I4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1640                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1641                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1642                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1643
1644                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1645                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1646                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1647                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1648                                 case Mode.U4_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1649                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1650
1651                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1652                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1653                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
1654                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1655                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
1656                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1657                                 case Mode.I8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1658                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1659
1660                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1661                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1662                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1663                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1664                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_Ovf_I4_Un); break;
1665                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_Ovf_U4_Un); break;
1666                                 case Mode.U8_I8: ig.Emit (OpCodes.Conv_Ovf_I8_Un); break;
1667                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_Ovf_U2_Un); break;
1668
1669                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_Ovf_I1_Un); break;
1670                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_Ovf_U1_Un); break;
1671                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_Ovf_I2_Un); break;
1672
1673                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1674                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1675                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
1676                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1677                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
1678                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1679                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
1680                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1681                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1682
1683                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_Ovf_I1); break;
1684                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_Ovf_U1); break;
1685                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_Ovf_I2); break;
1686                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1687                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_Ovf_I4); break;
1688                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_Ovf_U4); break;
1689                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_Ovf_I8); break;
1690                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_Ovf_U8); break;
1691                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_Ovf_U2); break;
1692                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
1693                                 }
1694                         } else {
1695                                 switch (mode){
1696                                 case Mode.I1_U1: ig.Emit (OpCodes.Conv_U1); break;
1697                                 case Mode.I1_U2: ig.Emit (OpCodes.Conv_U2); break;
1698                                 case Mode.I1_U4: ig.Emit (OpCodes.Conv_U4); break;
1699                                 case Mode.I1_U8: ig.Emit (OpCodes.Conv_I8); break;
1700                                 case Mode.I1_CH: ig.Emit (OpCodes.Conv_U2); break;
1701
1702                                 case Mode.U1_I1: ig.Emit (OpCodes.Conv_I1); break;
1703                                 case Mode.U1_CH: ig.Emit (OpCodes.Conv_U2); break;
1704
1705                                 case Mode.I2_I1: ig.Emit (OpCodes.Conv_I1); break;
1706                                 case Mode.I2_U1: ig.Emit (OpCodes.Conv_U1); break;
1707                                 case Mode.I2_U2: ig.Emit (OpCodes.Conv_U2); break;
1708                                 case Mode.I2_U4: ig.Emit (OpCodes.Conv_U4); break;
1709                                 case Mode.I2_U8: ig.Emit (OpCodes.Conv_I8); break;
1710                                 case Mode.I2_CH: ig.Emit (OpCodes.Conv_U2); break;
1711
1712                                 case Mode.U2_I1: ig.Emit (OpCodes.Conv_I1); break;
1713                                 case Mode.U2_U1: ig.Emit (OpCodes.Conv_U1); break;
1714                                 case Mode.U2_I2: ig.Emit (OpCodes.Conv_I2); break;
1715                                 case Mode.U2_CH: /* nothing */ break;
1716
1717                                 case Mode.I4_I1: ig.Emit (OpCodes.Conv_I1); break;
1718                                 case Mode.I4_U1: ig.Emit (OpCodes.Conv_U1); break;
1719                                 case Mode.I4_I2: ig.Emit (OpCodes.Conv_I2); break;
1720                                 case Mode.I4_U4: /* nothing */ break;
1721                                 case Mode.I4_U2: ig.Emit (OpCodes.Conv_U2); break;
1722                                 case Mode.I4_U8: ig.Emit (OpCodes.Conv_I8); break;
1723                                 case Mode.I4_CH: ig.Emit (OpCodes.Conv_U2); break;
1724
1725                                 case Mode.U4_I1: ig.Emit (OpCodes.Conv_I1); break;
1726                                 case Mode.U4_U1: ig.Emit (OpCodes.Conv_U1); break;
1727                                 case Mode.U4_I2: ig.Emit (OpCodes.Conv_I2); break;
1728                                 case Mode.U4_U2: ig.Emit (OpCodes.Conv_U2); break;
1729                                 case Mode.U4_I4: /* nothing */ break;
1730                                 case Mode.U4_CH: ig.Emit (OpCodes.Conv_U2); break;
1731
1732                                 case Mode.I8_I1: ig.Emit (OpCodes.Conv_I1); break;
1733                                 case Mode.I8_U1: ig.Emit (OpCodes.Conv_U1); break;
1734                                 case Mode.I8_I2: ig.Emit (OpCodes.Conv_I2); break;
1735                                 case Mode.I8_U2: ig.Emit (OpCodes.Conv_U2); break;
1736                                 case Mode.I8_I4: ig.Emit (OpCodes.Conv_I4); break;
1737                                 case Mode.I8_U4: ig.Emit (OpCodes.Conv_U4); break;
1738                                 case Mode.I8_U8: /* nothing */ break;
1739                                 case Mode.I8_CH: ig.Emit (OpCodes.Conv_U2); break;
1740
1741                                 case Mode.U8_I1: ig.Emit (OpCodes.Conv_I1); break;
1742                                 case Mode.U8_U1: ig.Emit (OpCodes.Conv_U1); break;
1743                                 case Mode.U8_I2: ig.Emit (OpCodes.Conv_I2); break;
1744                                 case Mode.U8_U2: ig.Emit (OpCodes.Conv_U2); break;
1745                                 case Mode.U8_I4: ig.Emit (OpCodes.Conv_I4); break;
1746                                 case Mode.U8_U4: ig.Emit (OpCodes.Conv_U4); break;
1747                                 case Mode.U8_I8: /* nothing */ break;
1748                                 case Mode.U8_CH: ig.Emit (OpCodes.Conv_U2); break;
1749
1750                                 case Mode.CH_I1: ig.Emit (OpCodes.Conv_I1); break;
1751                                 case Mode.CH_U1: ig.Emit (OpCodes.Conv_U1); break;
1752                                 case Mode.CH_I2: ig.Emit (OpCodes.Conv_I2); break;
1753
1754                                 case Mode.R4_I1: ig.Emit (OpCodes.Conv_I1); break;
1755                                 case Mode.R4_U1: ig.Emit (OpCodes.Conv_U1); break;
1756                                 case Mode.R4_I2: ig.Emit (OpCodes.Conv_I2); break;
1757                                 case Mode.R4_U2: ig.Emit (OpCodes.Conv_U2); break;
1758                                 case Mode.R4_I4: ig.Emit (OpCodes.Conv_I4); break;
1759                                 case Mode.R4_U4: ig.Emit (OpCodes.Conv_U4); break;
1760                                 case Mode.R4_I8: ig.Emit (OpCodes.Conv_I8); break;
1761                                 case Mode.R4_U8: ig.Emit (OpCodes.Conv_U8); break;
1762                                 case Mode.R4_CH: ig.Emit (OpCodes.Conv_U2); break;
1763
1764                                 case Mode.R8_I1: ig.Emit (OpCodes.Conv_I1); break;
1765                                 case Mode.R8_U1: ig.Emit (OpCodes.Conv_U1); break;
1766                                 case Mode.R8_I2: ig.Emit (OpCodes.Conv_I2); break;
1767                                 case Mode.R8_U2: ig.Emit (OpCodes.Conv_U2); break;
1768                                 case Mode.R8_I4: ig.Emit (OpCodes.Conv_I4); break;
1769                                 case Mode.R8_U4: ig.Emit (OpCodes.Conv_U4); break;
1770                                 case Mode.R8_I8: ig.Emit (OpCodes.Conv_I8); break;
1771                                 case Mode.R8_U8: ig.Emit (OpCodes.Conv_U8); break;
1772                                 case Mode.R8_CH: ig.Emit (OpCodes.Conv_U2); break;
1773                                 case Mode.R8_R4: ig.Emit (OpCodes.Conv_R4); break;
1774                                 }
1775                         }
1776                 }
1777         }
1778
1779         public class OpcodeCast : EmptyCast {
1780                 OpCode op, op2;
1781                 bool second_valid;
1782
1783                 public OpcodeCast (Expression child, Type return_type, OpCode op)
1784                         : base (child, return_type)
1785
1786                 {
1787                         this.op = op;
1788                         second_valid = false;
1789                 }
1790
1791                 public OpcodeCast (Expression child, Type return_type, OpCode op, OpCode op2)
1792                         : base (child, return_type)
1793
1794                 {
1795                         this.op = op;
1796                         this.op2 = op2;
1797                         second_valid = true;
1798                 }
1799
1800                 public override Expression DoResolve (EmitContext ec)
1801                 {
1802                         // This should never be invoked, we are born in fully
1803                         // initialized state.
1804
1805                         return this;
1806                 }
1807
1808                 public override void Emit (EmitContext ec)
1809                 {
1810                         base.Emit (ec);
1811                         ec.ig.Emit (op);
1812
1813                         if (second_valid)
1814                                 ec.ig.Emit (op2);
1815                 }
1816         }
1817
1818         /// <summary>
1819         ///   This kind of cast is used to encapsulate a child and cast it
1820         ///   to the class requested
1821         /// </summary>
1822         public class ClassCast : EmptyCast {
1823                 public ClassCast (Expression child, Type return_type)
1824                         : base (child, return_type)
1825
1826                 {
1827                 }
1828
1829                 public override Expression DoResolve (EmitContext ec)
1830                 {
1831                         // This should never be invoked, we are born in fully
1832                         // initialized state.
1833
1834                         return this;
1835                 }
1836
1837                 public override void Emit (EmitContext ec)
1838                 {
1839                         base.Emit (ec);
1840
1841                         ec.ig.Emit (OpCodes.Castclass, type);
1842                 }
1843
1844         }
1845
1846         /// <summary>
1847         ///   SimpleName expressions are initially formed of a single
1848         ///   word and it only happens at the beginning of the expression.
1849         /// </summary>
1850         ///
1851         /// <remarks>
1852         ///   The expression will try to be bound to a Field, a Method
1853         ///   group or a Property.  If those fail we pass the name to our
1854         ///   caller and the SimpleName is compounded to perform a type
1855         ///   lookup.  The idea behind this process is that we want to avoid
1856         ///   creating a namespace map from the assemblies, as that requires
1857         ///   the GetExportedTypes function to be called and a hashtable to
1858         ///   be constructed which reduces startup time.  If later we find
1859         ///   that this is slower, we should create a `NamespaceExpr' expression
1860         ///   that fully participates in the resolution process.
1861         ///
1862         ///   For example `System.Console.WriteLine' is decomposed into
1863         ///   MemberAccess (MemberAccess (SimpleName ("System"), "Console"), "WriteLine")
1864         ///
1865         ///   The first SimpleName wont produce a match on its own, so it will
1866         ///   be turned into:
1867         ///   MemberAccess (SimpleName ("System.Console"), "WriteLine").
1868         ///
1869         ///   System.Console will produce a TypeExpr match.
1870         ///
1871         ///   The downside of this is that we might be hitting `LookupType' too many
1872         ///   times with this scheme.
1873         /// </remarks>
1874         public class SimpleName : Expression {
1875                 public string Name;
1876
1877                 //
1878                 // If true, then we are a simple name, not composed with a ".
1879                 //
1880                 bool is_base;
1881
1882                 public SimpleName (string a, string b, Location l)
1883                 {
1884                         Name = String.Concat (a, ".", b);
1885                         loc = l;
1886                         is_base = false;
1887                 }
1888
1889                 public SimpleName (string name, Location l)
1890                 {
1891                         Name = name;
1892                         loc = l;
1893                         is_base = true;
1894                 }
1895
1896                 public static void Error_ObjectRefRequired (EmitContext ec, Location l, string name)
1897                 {
1898                         if (ec.IsFieldInitializer)
1899                                 Report.Error (
1900                                         236, l,
1901                                         "A field initializer cannot reference the non-static field, " +
1902                                         "method or property `"+name+"'");
1903                         else
1904                                 Report.Error (
1905                                         120, l,
1906                                         "An object reference is required " +
1907                                         "for the non-static field `"+name+"'");
1908                 }
1909
1910                 //
1911                 // Checks whether we are trying to access an instance
1912                 // property, method or field from a static body.
1913                 //
1914                 Expression MemberStaticCheck (EmitContext ec, Expression e)
1915                 {
1916                         if (e is IMemberExpr){
1917                                 IMemberExpr member = (IMemberExpr) e;
1918
1919                                 if (!member.IsStatic){
1920                                         Error_ObjectRefRequired (ec, loc, Name);
1921                                         return null;
1922                                 }
1923                         }
1924
1925                         return e;
1926                 }
1927
1928                 public override Expression DoResolve (EmitContext ec)
1929                 {
1930                         return SimpleNameResolve (ec, null, false);
1931                 }
1932
1933                 public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
1934                 {
1935                         return SimpleNameResolve (ec, right_side, false);
1936                 }
1937
1938
1939                 public Expression DoResolveAllowStatic (EmitContext ec)
1940                 {
1941                         return SimpleNameResolve (ec, null, true);
1942                 }
1943
1944                 public override Expression ResolveAsTypeStep (EmitContext ec)
1945                 {
1946                         DeclSpace ds = ec.DeclSpace;
1947                         NamespaceEntry ns = ds.NamespaceEntry;
1948                         Type t;
1949                         string alias_value;
1950
1951                         //
1952                         // Since we are cheating: we only do the Alias lookup for
1953                         // namespaces if the name does not include any dots in it
1954                         //
1955                         if (ns != null && is_base)
1956                                 alias_value = ns.LookupAlias (Name);
1957                         else
1958                                 alias_value = null;
1959
1960                         if (ec.ResolvingTypeTree){
1961                                 if (alias_value != null){
1962                                         if ((t = RootContext.LookupType (ds, alias_value, true, loc)) != null)
1963                                                 return new TypeExpression (t, loc);
1964                                 }
1965
1966                                 int errors = Report.Errors;
1967                                 Type dt = ec.DeclSpace.FindType (loc, Name);
1968
1969                                 if (Report.Errors != errors)
1970                                         return null;
1971
1972                                 if (dt != null)
1973                                         return new TypeExpression (dt, loc);
1974                         }
1975
1976                         //
1977                         // First, the using aliases
1978                         //
1979                         if (alias_value != null){
1980                                 if ((t = RootContext.LookupType (ds, alias_value, true, loc)) != null)
1981                                         return new TypeExpression (t, loc);
1982
1983                                 // we have alias value, but it isn't Type, so try if it's namespace
1984                                 return new SimpleName (alias_value, loc);
1985                         }
1986
1987                         if (ec.IsGeneric){
1988                                 TypeParameterExpr generic_type = ds.LookupGeneric (Name, loc);
1989
1990                                 if (generic_type != null)
1991                                         return generic_type.ResolveAsTypeTerminal (ec);
1992                         }
1993
1994                         //
1995                         // Stage 2: Lookup up if we are an alias to a type
1996                         // or a namespace.
1997                         //
1998
1999                         if ((t = RootContext.LookupType (ds, Name, true, loc)) != null)
2000                                 return new TypeExpression (t, loc);
2001
2002                         // No match, maybe our parent can compose us
2003                         // into something meaningful.
2004                         return this;
2005                 }
2006
2007                 /// <remarks>
2008                 ///   7.5.2: Simple Names.
2009                 ///
2010                 ///   Local Variables and Parameters are handled at
2011                 ///   parse time, so they never occur as SimpleNames.
2012                 ///
2013                 ///   The `allow_static' flag is used by MemberAccess only
2014                 ///   and it is used to inform us that it is ok for us to
2015                 ///   avoid the static check, because MemberAccess might end
2016                 ///   up resolving the Name as a Type name and the access as
2017                 ///   a static type access.
2018                 ///
2019                 ///   ie: Type Type; .... { Type.GetType (""); }
2020                 ///
2021                 ///   Type is both an instance variable and a Type;  Type.GetType
2022                 ///   is the static method not an instance method of type.
2023                 /// </remarks>
2024                 Expression SimpleNameResolve (EmitContext ec, Expression right_side, bool allow_static)
2025                 {
2026                         Expression e = null;
2027
2028                         //
2029                         // Stage 1: Performed by the parser (binding to locals or parameters).
2030                         //
2031                         Block current_block = ec.CurrentBlock;
2032                         if (current_block != null){
2033                                 LocalInfo vi = current_block.GetLocalInfo (Name);
2034                                 if (vi != null){
2035                                         Expression var;
2036
2037                                         var = new LocalVariableReference (ec.CurrentBlock, Name, loc);
2038
2039                                         if (right_side != null)
2040                                                 return var.ResolveLValue (ec, right_side);
2041                                         else
2042                                                 return var.Resolve (ec);
2043                                 }
2044
2045                                 int idx = -1;
2046                                 Parameter par = null;
2047                                 Parameters pars = current_block.Parameters;
2048                                 if (pars != null)
2049                                         par = pars.GetParameterByName (Name, out idx);
2050
2051                                 if (par != null) {
2052                                         ParameterReference param;
2053
2054                                         param = new ParameterReference (pars, current_block, idx, Name, loc);
2055
2056                                         if (right_side != null)
2057                                                 return param.ResolveLValue (ec, right_side);
2058                                         else
2059                                                 return param.Resolve (ec);
2060                                 }
2061                         }
2062
2063                         //
2064                         // Stage 2: Lookup members
2065                         //
2066
2067                         DeclSpace lookup_ds = ec.DeclSpace;
2068                         do {
2069                                 if (lookup_ds.TypeBuilder == null)
2070                                         break;
2071
2072                                 e = MemberLookup (ec, lookup_ds.TypeBuilder, Name, loc);
2073                                 if (e != null)
2074                                         break;
2075
2076                                 lookup_ds =lookup_ds.Parent;
2077                         } while (lookup_ds != null);
2078
2079                         if (e == null && ec.ContainerType != null)
2080                                 e = MemberLookup (ec, ec.ContainerType, Name, loc);
2081
2082                         if (e == null) {
2083                                 //
2084                                 // Since we are cheating (is_base is our hint
2085                                 // that we are the beginning of the name): we
2086                                 // only do the Alias lookup for namespaces if
2087                                 // the name does not include any dots in it
2088                                 //
2089                                 NamespaceEntry ns = ec.DeclSpace.NamespaceEntry;
2090                                 if (is_base && ns != null){
2091                                         string alias_value = ns.LookupAlias (Name);
2092                                         if (alias_value != null){
2093                                                 Name = alias_value;
2094                                                 Type t;
2095
2096                                                 if ((t = TypeManager.LookupType (Name)) != null)
2097                                                         return new TypeExpression (t, loc);
2098
2099                                                 // No match, maybe our parent can compose us
2100                                                 // into something meaningful.
2101                                                 return this;
2102                                         }
2103                                 }
2104
2105                                 return ResolveAsTypeStep (ec);
2106                         }
2107
2108                         if (e is TypeExpr)
2109                                 return e;
2110
2111                         if (e is IMemberExpr) {
2112                                 e = MemberAccess.ResolveMemberAccess (ec, e, null, loc, this);
2113                                 if (e == null)
2114                                         return null;
2115
2116                                 IMemberExpr me = e as IMemberExpr;
2117                                 if (me == null)
2118                                         return e;
2119
2120                                 // This fails if ResolveMemberAccess() was unable to decide whether
2121                                 // it's a field or a type of the same name.
2122                                 if (!me.IsStatic && (me.InstanceExpression == null))
2123                                         return e;
2124
2125                                 if (!me.IsStatic &&
2126                                     TypeManager.IsNestedChildOf (me.InstanceExpression.Type, me.DeclaringType) &&
2127                                     !me.InstanceExpression.Type.IsSubclassOf (me.DeclaringType)) {
2128                                         Error (38, "Cannot access nonstatic member `" + me.Name + "' of " +
2129                                                "outer type `" + me.DeclaringType + "' via nested type `" +
2130                                                me.InstanceExpression.Type + "'");
2131                                         return null;
2132                                 }
2133
2134                                 if (right_side != null)
2135                                         e = e.DoResolveLValue (ec, right_side);
2136                                 else
2137                                         e = e.DoResolve (ec);
2138
2139                                 return e;
2140                         }
2141
2142                         if (ec.IsStatic || ec.IsFieldInitializer){
2143                                 if (allow_static)
2144                                         return e;
2145
2146                                 return MemberStaticCheck (ec, e);
2147                         } else
2148                                 return e;
2149                 }
2150
2151                 public override void Emit (EmitContext ec)
2152                 {
2153                         //
2154                         // If this is ever reached, then we failed to
2155                         // find the name as a namespace
2156                         //
2157
2158                         Error (103, "The name `" + Name +
2159                                "' does not exist in the class `" +
2160                                ec.DeclSpace.Name + "'");
2161                 }
2162
2163                 public override string ToString ()
2164                 {
2165                         return Name;
2166                 }
2167         }
2168
2169         /// <summary>
2170         ///   Fully resolved expression that evaluates to a type
2171         /// </summary>
2172         public abstract class TypeExpr : Expression {
2173                 override public Expression ResolveAsTypeStep (EmitContext ec)
2174                 {
2175                         TypeExpr t = DoResolveAsTypeStep (ec);
2176                         if (t == null)
2177                                 return null;
2178
2179                         eclass = ExprClass.Type;
2180                         return t;
2181                 }
2182
2183                 override public Expression DoResolve (EmitContext ec)
2184                 {
2185                         return ResolveAsTypeTerminal (ec);
2186                 }
2187
2188                 override public void Emit (EmitContext ec)
2189                 {
2190                         throw new Exception ("Should never be called");
2191                 }
2192
2193                 public virtual bool CheckAccessLevel (DeclSpace ds)
2194                 {
2195                         return ds.CheckAccessLevel (Type);
2196                 }
2197
2198                 public virtual bool AsAccessible (DeclSpace ds, int flags)
2199                 {
2200                         return ds.AsAccessible (Type, flags);
2201                 }
2202
2203                 public virtual bool IsClass {
2204                         get { return Type.IsClass; }
2205                 }
2206
2207                 public virtual bool IsValueType {
2208                         get { return Type.IsValueType; }
2209                 }
2210
2211                 public virtual bool IsInterface {
2212                         get { return Type.IsInterface; }
2213                 }
2214
2215                 public virtual bool IsSealed {
2216                         get { return Type.IsSealed; }
2217                 }
2218
2219                 public virtual bool CanInheritFrom ()
2220                 {
2221                         if (Type == TypeManager.enum_type ||
2222                             (Type == TypeManager.value_type && RootContext.StdLib) ||
2223                             Type == TypeManager.delegate_type ||
2224                             Type == TypeManager.array_type)
2225                                 return false;
2226
2227                         return true;
2228                 }
2229
2230                 public virtual bool IsAttribute {
2231                         get {
2232                                 return Type == TypeManager.attribute_type ||
2233                                         Type.IsSubclassOf (TypeManager.attribute_type);
2234                         }
2235                 }
2236
2237                 public virtual TypeExpr[] GetInterfaces ()
2238                 {
2239                         return TypeManager.GetInterfaces (Type);
2240                 }
2241
2242                 public abstract TypeExpr DoResolveAsTypeStep (EmitContext ec);
2243
2244                 public virtual Type ResolveType (EmitContext ec)
2245                 {
2246                         TypeExpr t = ResolveAsTypeTerminal (ec);
2247                         if (t == null)
2248                                 return null;
2249
2250                         return t.Type;
2251                 }
2252
2253                 public abstract string Name {
2254                         get;
2255                 }
2256
2257                 public override bool Equals (object obj)
2258                 {
2259                         TypeExpr tobj = obj as TypeExpr;
2260                         if (tobj == null)
2261                                 return false;
2262
2263                         return Type == tobj.Type;
2264                 }
2265
2266                 public override string ToString ()
2267                 {
2268                         return Name;
2269                 }
2270         }
2271
2272         public class TypeExpression : TypeExpr {
2273                 public TypeExpression (Type t, Location l)
2274                 {
2275                         Type = t;
2276                         eclass = ExprClass.Type;
2277                         loc = l;
2278                 }
2279
2280                 public override TypeExpr DoResolveAsTypeStep (EmitContext ec)
2281                 {
2282                         return this;
2283                 }
2284
2285                 public override string Name {
2286                         get {
2287                                 return Type.ToString ();
2288                         }
2289                 }
2290         }
2291
2292         /// <summary>
2293         ///   Used to create types from a fully qualified name.  These are just used
2294         ///   by the parser to setup the core types.  A TypeLookupExpression is always
2295         ///   classified as a type.
2296         /// </summary>
2297         public class TypeLookupExpression : TypeExpr {
2298                 string name;
2299
2300                 public TypeLookupExpression (string name)
2301                 {
2302                         this.name = name;
2303                 }
2304
2305                 public override TypeExpr DoResolveAsTypeStep (EmitContext ec)
2306                 {
2307                         if (type == null)
2308                                 type = RootContext.LookupType (ec.DeclSpace, name, false, Location.Null);
2309                         return this;
2310                 }
2311
2312                 public override string Name {
2313                         get {
2314                                 return name;
2315                         }
2316                 }
2317         }
2318
2319         /// <summary>
2320         ///   MethodGroup Expression.
2321         ///
2322         ///   This is a fully resolved expression that evaluates to a type
2323         /// </summary>
2324         public class MethodGroupExpr : Expression, IMemberExpr {
2325                 public MethodBase [] Methods;
2326                 Expression instance_expression = null;
2327                 bool is_explicit_impl = false;
2328
2329                 public MethodGroupExpr (MemberInfo [] mi, Location l)
2330                 {
2331                         Methods = new MethodBase [mi.Length];
2332                         mi.CopyTo (Methods, 0);
2333                         eclass = ExprClass.MethodGroup;
2334                         type = TypeManager.object_type;
2335                         loc = l;
2336                 }
2337
2338                 public MethodGroupExpr (ArrayList list, Location l)
2339                 {
2340                         Methods = new MethodBase [list.Count];
2341
2342                         try {
2343                                 list.CopyTo (Methods, 0);
2344                         } catch {
2345                                 foreach (MemberInfo m in list){
2346                                         if (!(m is MethodBase)){
2347                                                 Console.WriteLine ("Name " + m.Name);
2348                                                 Console.WriteLine ("Found a: " + m.GetType ().FullName);
2349                                         }
2350                                 }
2351                                 throw;
2352                         }
2353
2354                         loc = l;
2355                         eclass = ExprClass.MethodGroup;
2356                         type = TypeManager.object_type;
2357                 }
2358
2359                 public Type DeclaringType {
2360                         get {
2361                                 //
2362                                 // We assume that the top-level type is in the end
2363                                 //
2364                                 return Methods [Methods.Length - 1].DeclaringType;
2365                                 //return Methods [0].DeclaringType;
2366                         }
2367                 }
2368
2369                 //
2370                 // `A method group may have associated an instance expression'
2371                 //
2372                 public Expression InstanceExpression {
2373                         get {
2374                                 return instance_expression;
2375                         }
2376
2377                         set {
2378                                 instance_expression = value;
2379                         }
2380                 }
2381
2382                 public bool IsExplicitImpl {
2383                         get {
2384                                 return is_explicit_impl;
2385                         }
2386
2387                         set {
2388                                 is_explicit_impl = value;
2389                         }
2390                 }
2391
2392                 public string Name {
2393                         get {
2394                                 //return Methods [0].Name;
2395                                 return Methods [Methods.Length - 1].Name;
2396                         }
2397                 }
2398
2399                 public bool IsInstance {
2400                         get {
2401                                 foreach (MethodBase mb in Methods)
2402                                         if (!mb.IsStatic)
2403                                                 return true;
2404
2405                                 return false;
2406                         }
2407                 }
2408
2409                 public bool IsStatic {
2410                         get {
2411                                 foreach (MethodBase mb in Methods)
2412                                         if (mb.IsStatic)
2413                                                 return true;
2414
2415                                 return false;
2416                         }
2417                 }
2418
2419                 override public Expression DoResolve (EmitContext ec)
2420                 {
2421                         if (!IsInstance)
2422                                 instance_expression = null;
2423
2424                         if (instance_expression != null) {
2425                                 instance_expression = instance_expression.DoResolve (ec);
2426                                 if (instance_expression == null)
2427                                         return null;
2428                         }
2429
2430                         return this;
2431                 }
2432
2433                 public void ReportUsageError ()
2434                 {
2435                         Report.Error (654, loc, "Method `" + DeclaringType + "." +
2436                                       Name + "()' is referenced without parentheses");
2437                 }
2438
2439                 override public void Emit (EmitContext ec)
2440                 {
2441                         ReportUsageError ();
2442                 }
2443
2444                 bool RemoveMethods (bool keep_static)
2445                 {
2446                         ArrayList smethods = new ArrayList ();
2447
2448                         foreach (MethodBase mb in Methods){
2449                                 if (mb.IsStatic == keep_static)
2450                                         smethods.Add (mb);
2451                         }
2452
2453                         if (smethods.Count == 0)
2454                                 return false;
2455
2456                         Methods = new MethodBase [smethods.Count];
2457                         smethods.CopyTo (Methods, 0);
2458
2459                         return true;
2460                 }
2461
2462                 /// <summary>
2463                 ///   Removes any instance methods from the MethodGroup, returns
2464                 ///   false if the resulting set is empty.
2465                 /// </summary>
2466                 public bool RemoveInstanceMethods ()
2467                 {
2468                         return RemoveMethods (true);
2469                 }
2470
2471                 /// <summary>
2472                 ///   Removes any static methods from the MethodGroup, returns
2473                 ///   false if the resulting set is empty.
2474                 /// </summary>
2475                 public bool RemoveStaticMethods ()
2476                 {
2477                         return RemoveMethods (false);
2478                 }
2479         }
2480
2481         /// <summary>
2482         ///   Fully resolved expression that evaluates to a Field
2483         /// </summary>
2484         public class FieldExpr : Expression, IAssignMethod, IMemoryLocation, IMemberExpr, IVariable {
2485                 public readonly FieldInfo FieldInfo;
2486                 Expression instance_expr;
2487                 VariableInfo variable_info;
2488
2489                 public FieldExpr (FieldInfo fi, Location l)
2490                 {
2491                         FieldInfo = fi;
2492                         eclass = ExprClass.Variable;
2493                         type = fi.FieldType;
2494                         loc = l;
2495                 }
2496
2497                 public string Name {
2498                         get {
2499                                 return FieldInfo.Name;
2500                         }
2501                 }
2502
2503                 public bool IsInstance {
2504                         get {
2505                                 return !FieldInfo.IsStatic;
2506                         }
2507                 }
2508
2509                 public bool IsStatic {
2510                         get {
2511                                 return FieldInfo.IsStatic;
2512                         }
2513                 }
2514
2515                 public Type DeclaringType {
2516                         get {
2517                                 return FieldInfo.DeclaringType;
2518                         }
2519                 }
2520
2521                 public Expression InstanceExpression {
2522                         get {
2523                                 return instance_expr;
2524                         }
2525
2526                         set {
2527                                 instance_expr = value;
2528                         }
2529                 }
2530
2531                 public VariableInfo VariableInfo {
2532                         get {
2533                                 return variable_info;
2534                         }
2535                 }
2536
2537                 override public Expression DoResolve (EmitContext ec)
2538                 {
2539                         if (!FieldInfo.IsStatic){
2540                                 if (instance_expr == null){
2541                                         //
2542                                         // This can happen when referencing an instance field using
2543                                         // a fully qualified type expression: TypeName.InstanceField = xxx
2544                                         //
2545                                         SimpleName.Error_ObjectRefRequired (ec, loc, FieldInfo.Name);
2546                                         return null;
2547                                 }
2548
2549                                 // Resolve the field's instance expression while flow analysis is turned
2550                                 // off: when accessing a field "a.b", we must check whether the field
2551                                 // "a.b" is initialized, not whether the whole struct "a" is initialized.
2552                                 instance_expr = instance_expr.Resolve (ec, ResolveFlags.VariableOrValue |
2553                                                                        ResolveFlags.DisableFlowAnalysis);
2554                                 if (instance_expr == null)
2555                                         return null;
2556                         }
2557
2558                         // If the instance expression is a local variable or parameter.
2559                         IVariable var = instance_expr as IVariable;
2560                         if ((var == null) || (var.VariableInfo == null))
2561                                 return this;
2562
2563                         VariableInfo vi = var.VariableInfo;
2564                         if (!vi.IsFieldAssigned (ec, FieldInfo.Name, loc))
2565                                 return null;
2566
2567                         variable_info = vi.GetSubStruct (FieldInfo.Name);
2568                         return this;
2569                 }
2570
2571                 void Report_AssignToReadonly (bool is_instance)
2572                 {
2573                         string msg;
2574
2575                         if (is_instance)
2576                                 msg = "Readonly field can not be assigned outside " +
2577                                 "of constructor or variable initializer";
2578                         else
2579                                 msg = "A static readonly field can only be assigned in " +
2580                                 "a static constructor";
2581
2582                         Report.Error (is_instance ? 191 : 198, loc, msg);
2583                 }
2584
2585                 override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
2586                 {
2587                         IVariable var = instance_expr as IVariable;
2588                         if ((var != null) && (var.VariableInfo != null))
2589                                 var.VariableInfo.SetFieldAssigned (ec, FieldInfo.Name);
2590
2591                         Expression e = DoResolve (ec);
2592
2593                         if (e == null)
2594                                 return null;
2595
2596                         if (!FieldInfo.IsStatic && (instance_expr.Type.IsValueType && !(instance_expr is IMemoryLocation))) {
2597                                 // FIXME: Provide better error reporting.
2598                                 Error (1612, "Cannot modify expression because it is not a variable.");
2599                                 return null;
2600                         }
2601
2602                         if (!FieldInfo.IsInitOnly)
2603                                 return this;
2604
2605                         FieldBase fb = TypeManager.GetField (FieldInfo);
2606                         if (fb != null)
2607                                 fb.IsAssigned = true;
2608
2609                         //
2610                         // InitOnly fields can only be assigned in constructors
2611                         //
2612
2613                         if (ec.IsConstructor){
2614                                 if (IsStatic && !ec.IsStatic)
2615                                         Report_AssignToReadonly (false);
2616
2617                                 if (ec.ContainerType == FieldInfo.DeclaringType)
2618                                         return this;
2619                         }
2620
2621                         Report_AssignToReadonly (true);
2622
2623                         return null;
2624                 }
2625
2626                 public bool VerifyFixed (bool is_expression)
2627                 {
2628                         IVariable variable = instance_expr as IVariable;
2629                         if ((variable == null) || !variable.VerifyFixed (true))
2630                                 return false;
2631
2632                         return true;
2633                 }
2634
2635                 override public void Emit (EmitContext ec)
2636                 {
2637                         ILGenerator ig = ec.ig;
2638                         bool is_volatile = false;
2639
2640                         if (FieldInfo is FieldBuilder){
2641                                 FieldBase f = TypeManager.GetField (FieldInfo);
2642                                 if (f != null){
2643                                         if ((f.ModFlags & Modifiers.VOLATILE) != 0)
2644                                                 is_volatile = true;
2645
2646                                         f.status |= Field.Status.USED;
2647                                 }
2648                         }
2649
2650                         if (FieldInfo.IsStatic){
2651                                 if (is_volatile)
2652                                         ig.Emit (OpCodes.Volatile);
2653
2654                                 ig.Emit (OpCodes.Ldsfld, FieldInfo);
2655                                 return;
2656                         }
2657
2658                         if (instance_expr.Type.IsValueType){
2659                                 IMemoryLocation ml;
2660                                 LocalTemporary tempo = null;
2661
2662                                 if (!(instance_expr is IMemoryLocation)){
2663                                         tempo = new LocalTemporary (ec, instance_expr.Type);
2664
2665                                         if (ec.RemapToProxy)
2666                                                 ec.EmitThis ();
2667
2668                                         InstanceExpression.Emit (ec);
2669                                         tempo.Store (ec);
2670                                         ml = tempo;
2671                                 } else
2672                                         ml = (IMemoryLocation) instance_expr;
2673
2674                                 ml.AddressOf (ec, AddressOp.Load);
2675                         } else {
2676                                 if (ec.RemapToProxy)
2677                                         ec.EmitThis ();
2678                                 else
2679                                         instance_expr.Emit (ec);
2680                         }
2681                         if (is_volatile)
2682                                 ig.Emit (OpCodes.Volatile);
2683
2684                         ig.Emit (OpCodes.Ldfld, FieldInfo);
2685                 }
2686
2687                 public void EmitAssign (EmitContext ec, Expression source)
2688                 {
2689                         FieldAttributes fa = FieldInfo.Attributes;
2690                         bool is_static = (fa & FieldAttributes.Static) != 0;
2691                         bool is_readonly = (fa & FieldAttributes.InitOnly) != 0;
2692                         ILGenerator ig = ec.ig;
2693
2694                         if (is_readonly && !ec.IsConstructor){
2695                                 Report_AssignToReadonly (!is_static);
2696                                 return;
2697                         }
2698
2699                         if (!is_static){
2700                                 Expression instance = instance_expr;
2701
2702                                 if (instance.Type.IsValueType){
2703                                         IMemoryLocation ml = (IMemoryLocation) instance;
2704
2705                                         ml.AddressOf (ec, AddressOp.Store);
2706                                 } else {
2707                                         if (ec.RemapToProxy)
2708                                                 ec.EmitThis ();
2709                                         else
2710                                                 instance.Emit (ec);
2711                                 }
2712                         }
2713
2714                         source.Emit (ec);
2715
2716                         if (FieldInfo is FieldBuilder){
2717                                 FieldBase f = TypeManager.GetField (FieldInfo);
2718                                 if (f != null){
2719                                         if ((f.ModFlags & Modifiers.VOLATILE) != 0)
2720                                                 ig.Emit (OpCodes.Volatile);
2721
2722                                         f.status |= Field.Status.ASSIGNED;
2723                                 }
2724                         }
2725
2726                         if (is_static)
2727                                 ig.Emit (OpCodes.Stsfld, FieldInfo);
2728                         else
2729                                 ig.Emit (OpCodes.Stfld, FieldInfo);
2730                 }
2731
2732                 public void AddressOf (EmitContext ec, AddressOp mode)
2733                 {
2734                         ILGenerator ig = ec.ig;
2735
2736                         if (FieldInfo is FieldBuilder){
2737                                 FieldBase f = TypeManager.GetField (FieldInfo);
2738                                 if (f != null){
2739                                         if ((f.ModFlags & Modifiers.VOLATILE) != 0){
2740                                                 Error (676, "volatile variable: can not take its address, or pass as ref/out parameter");
2741                                                 return;
2742                                         }
2743
2744                                         if ((mode & AddressOp.Store) != 0)
2745                                                 f.status |= Field.Status.ASSIGNED;
2746                                         if ((mode & AddressOp.Load) != 0)
2747                                                 f.status |= Field.Status.USED;
2748                                 }
2749                         }
2750
2751                         //
2752                         // Handle initonly fields specially: make a copy and then
2753                         // get the address of the copy.
2754                         //
2755                         if (FieldInfo.IsInitOnly && !ec.IsConstructor){
2756                                 LocalBuilder local;
2757
2758                                 Emit (ec);
2759                                 local = ig.DeclareLocal (type);
2760                                 ig.Emit (OpCodes.Stloc, local);
2761                                 ig.Emit (OpCodes.Ldloca, local);
2762                                 return;
2763                         }
2764
2765                         if (FieldInfo.IsStatic)
2766                                 ig.Emit (OpCodes.Ldsflda, FieldInfo);
2767                         else {
2768                                 //
2769                                 // In the case of `This', we call the AddressOf method, which will
2770                                 // only load the pointer, and not perform an Ldobj immediately after
2771                                 // the value has been loaded into the stack.
2772                                 //
2773                                 if (instance_expr is This)
2774                                         ((This)instance_expr).AddressOf (ec, AddressOp.LoadStore);
2775                                 else if (instance_expr.Type.IsValueType && instance_expr is IMemoryLocation){
2776                                         IMemoryLocation ml = (IMemoryLocation) instance_expr;
2777
2778                                         ml.AddressOf (ec, AddressOp.LoadStore);
2779                                 } else
2780                                         instance_expr.Emit (ec);
2781                                 ig.Emit (OpCodes.Ldflda, FieldInfo);
2782                         }
2783                 }
2784         }
2785
2786         //
2787         // A FieldExpr whose address can not be taken
2788         //
2789         public class FieldExprNoAddress : FieldExpr, IMemoryLocation {
2790                 public FieldExprNoAddress (FieldInfo fi, Location loc) : base (fi, loc)
2791                 {
2792                 }
2793
2794                 public new void AddressOf (EmitContext ec, AddressOp mode)
2795                 {
2796                         Report.Error (-215, "Report this: Taking the address of a remapped parameter not supported");
2797                 }
2798         }
2799
2800         /// <summary>
2801         ///   Expression that evaluates to a Property.  The Assign class
2802         ///   might set the `Value' expression if we are in an assignment.
2803         ///
2804         ///   This is not an LValue because we need to re-write the expression, we
2805         ///   can not take data from the stack and store it.
2806         /// </summary>
2807         public class PropertyExpr : ExpressionStatement, IAssignMethod, IMemberExpr {
2808                 public readonly PropertyInfo PropertyInfo;
2809
2810                 //
2811                 // This is set externally by the  `BaseAccess' class
2812                 //
2813                 public bool IsBase;
2814                 MethodInfo getter, setter;
2815                 bool is_static;
2816                 bool must_do_cs1540_check;
2817
2818                 Expression instance_expr;
2819
2820                 public PropertyExpr (EmitContext ec, PropertyInfo pi, Location l)
2821                 {
2822                         PropertyInfo = pi;
2823                         eclass = ExprClass.PropertyAccess;
2824                         is_static = false;
2825                         loc = l;
2826
2827                         type = TypeManager.TypeToCoreType (pi.PropertyType);
2828
2829                         ResolveAccessors (ec);
2830                 }
2831
2832                 public string Name {
2833                         get {
2834                                 return PropertyInfo.Name;
2835                         }
2836                 }
2837
2838                 public bool IsInstance {
2839                         get {
2840                                 return !is_static;
2841                         }
2842                 }
2843
2844                 public bool IsStatic {
2845                         get {
2846                                 return is_static;
2847                         }
2848                 }
2849
2850                 public Type DeclaringType {
2851                         get {
2852                                 return PropertyInfo.DeclaringType;
2853                         }
2854                 }
2855
2856                 //
2857                 // The instance expression associated with this expression
2858                 //
2859                 public Expression InstanceExpression {
2860                         set {
2861                                 instance_expr = value;
2862                         }
2863
2864                         get {
2865                                 return instance_expr;
2866                         }
2867                 }
2868
2869                 public bool VerifyAssignable ()
2870                 {
2871                         if (setter == null) {
2872                                 Report.Error (200, loc,
2873                                               "The property `" + PropertyInfo.Name +
2874                                               "' can not be assigned to, as it has not set accessor");
2875                                 return false;
2876                         }
2877
2878                         return true;
2879                 }
2880
2881                 MethodInfo GetAccessor (Type invocation_type, string accessor_name)
2882                 {
2883                         BindingFlags flags = BindingFlags.Public | BindingFlags.NonPublic |
2884                                 BindingFlags.Static | BindingFlags.Instance;
2885                         MemberInfo[] group;
2886
2887                         group = TypeManager.MemberLookup (
2888                                 invocation_type, invocation_type, PropertyInfo.DeclaringType,
2889                                 MemberTypes.Method, flags, accessor_name + "_" + PropertyInfo.Name);
2890
2891                         //
2892                         // The first method is the closest to us
2893                         //
2894                         if (group == null)
2895                                 return null;
2896
2897                         foreach (MethodInfo mi in group) {
2898                                 MethodAttributes ma = mi.Attributes & MethodAttributes.MemberAccessMask;
2899
2900                                 //
2901                                 // If only accessible to the current class or children
2902                                 //
2903                                 if (ma == MethodAttributes.Private) {
2904                                         Type declaring_type = mi.DeclaringType;
2905
2906                                         if (invocation_type != declaring_type){
2907                                                 if (TypeManager.IsSubclassOrNestedChildOf (invocation_type, mi.DeclaringType))
2908                                                         return mi;
2909                                                 else
2910                                                         continue;
2911                                         } else
2912                                                 return mi;
2913                                 }
2914                                 //
2915                                 // FamAndAssem requires that we not only derivate, but we are on the
2916                                 // same assembly.
2917                                 //
2918                                 if (ma == MethodAttributes.FamANDAssem){
2919                                         if (mi.DeclaringType.Assembly != invocation_type.Assembly)
2920                                                 continue;
2921                                         else
2922                                                 return mi;
2923                                 }
2924
2925                                 // Assembly and FamORAssem succeed if we're in the same assembly.
2926                                 if ((ma == MethodAttributes.Assembly) || (ma == MethodAttributes.FamORAssem)){
2927                                         if (mi.DeclaringType.Assembly == invocation_type.Assembly)
2928                                                 return mi;
2929                                 }
2930
2931                                 // We already know that we aren't in the same assembly.
2932                                 if (ma == MethodAttributes.Assembly)
2933                                         continue;
2934
2935                                 // Family and FamANDAssem require that we derive.
2936                                 if ((ma == MethodAttributes.Family) || (ma == MethodAttributes.FamANDAssem) || (ma == MethodAttributes.FamORAssem)){
2937                                         if (!TypeManager.IsSubclassOrNestedChildOf (invocation_type, mi.DeclaringType))
2938                                                 continue;
2939                                         else {
2940                                                 must_do_cs1540_check = true;
2941
2942                                                 return mi;
2943                                         }
2944                                 }
2945
2946                                 return mi;
2947                         }
2948
2949                         return null;
2950                 }
2951
2952                 //
2953                 // We also perform the permission checking here, as the PropertyInfo does not
2954                 // hold the information for the accessibility of its setter/getter
2955                 //
2956                 void ResolveAccessors (EmitContext ec)
2957                 {
2958                         getter = GetAccessor (ec.ContainerType, "get");
2959                         if ((getter != null) && getter.IsStatic)
2960                                 is_static = true;
2961
2962                         setter = GetAccessor (ec.ContainerType, "set");
2963                         if ((setter != null) && setter.IsStatic)
2964                                 is_static = true;
2965
2966                         if (setter == null && getter == null){
2967                                 Error (122, "`" + PropertyInfo.Name + "' " +
2968                                        "is inaccessible because of its protection level");
2969
2970                         }
2971                 }
2972
2973                 bool InstanceResolve (EmitContext ec)
2974                 {
2975                         if ((instance_expr == null) && ec.IsStatic && !is_static) {
2976                                 SimpleName.Error_ObjectRefRequired (ec, loc, PropertyInfo.Name);
2977                                 return false;
2978                         }
2979
2980                         if (instance_expr != null) {
2981                                 instance_expr = instance_expr.DoResolve (ec);
2982                                 if (instance_expr == null)
2983                                         return false;
2984                         }
2985
2986                         if (must_do_cs1540_check && (instance_expr != null)) {
2987                                 if ((instance_expr.Type != ec.ContainerType) &&
2988                                     ec.ContainerType.IsSubclassOf (instance_expr.Type)) {
2989                                         Report.Error (1540, loc, "Cannot access protected member `" +
2990                                                       PropertyInfo.DeclaringType + "." + PropertyInfo.Name +
2991                                                       "' via a qualifier of type `" +
2992                                                       TypeManager.CSharpName (instance_expr.Type) +
2993                                                       "'; the qualifier must be of type `" +
2994                                                       TypeManager.CSharpName (ec.ContainerType) +
2995                                                       "' (or derived from it)");
2996                                         return false;
2997                                 }
2998                         }
2999
3000                         return true;
3001                 }
3002
3003                 override public Expression DoResolve (EmitContext ec)
3004                 {
3005                         if (getter == null){
3006                                 //
3007                                 // The following condition happens if the PropertyExpr was
3008                                 // created, but is invalid (ie, the property is inaccessible),
3009                                 // and we did not want to embed the knowledge about this in
3010                                 // the caller routine.  This only avoids double error reporting.
3011                                 //
3012                                 if (setter == null)
3013                                         return null;
3014
3015                                 Report.Error (154, loc,
3016                                               "The property `" + PropertyInfo.Name +
3017                                               "' can not be used in " +
3018                                               "this context because it lacks a get accessor");
3019                                 return null;
3020                         }
3021
3022                         if (!InstanceResolve (ec))
3023                                 return null;
3024
3025                         //
3026                         // Only base will allow this invocation to happen.
3027                         //
3028                         if (IsBase && getter.IsAbstract){
3029                                 Report.Error (205, loc, "Cannot call an abstract base property: " +
3030                                               PropertyInfo.DeclaringType + "." +PropertyInfo.Name);
3031                                 return null;
3032                         }
3033
3034                         return this;
3035                 }
3036
3037                 override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
3038                 {
3039                         if (setter == null){
3040                                 //
3041                                 // The following condition happens if the PropertyExpr was
3042                                 // created, but is invalid (ie, the property is inaccessible),
3043                                 // and we did not want to embed the knowledge about this in
3044                                 // the caller routine.  This only avoids double error reporting.
3045                                 //
3046                                 if (getter == null)
3047                                         return null;
3048
3049                                 Report.Error (154, loc,
3050                                               "The property `" + PropertyInfo.Name +
3051                                               "' can not be used in " +
3052                                               "this context because it lacks a set accessor");
3053                                 return null;
3054                         }
3055
3056                         if (!InstanceResolve (ec))
3057                                 return null;
3058
3059                         //
3060                         // Only base will allow this invocation to happen.
3061                         //
3062                         if (IsBase && setter.IsAbstract){
3063                                 Report.Error (205, loc, "Cannot call an abstract base property: " +
3064                                               PropertyInfo.DeclaringType + "." +PropertyInfo.Name);
3065                                 return null;
3066                         }
3067                         return this;
3068                 }
3069
3070                 override public void Emit (EmitContext ec)
3071                 {
3072                         //
3073                         // Special case: length of single dimension array property is turned into ldlen
3074                         //
3075                         if ((getter == TypeManager.system_int_array_get_length) ||
3076                             (getter == TypeManager.int_array_get_length)){
3077                                 Type iet = instance_expr.Type;
3078
3079                                 //
3080                                 // System.Array.Length can be called, but the Type does not
3081                                 // support invoking GetArrayRank, so test for that case first
3082                                 //
3083                                 if (iet != TypeManager.array_type && (iet.GetArrayRank () == 1)){
3084                                         instance_expr.Emit (ec);
3085                                         ec.ig.Emit (OpCodes.Ldlen);
3086                                         ec.ig.Emit (OpCodes.Conv_I4);
3087                                         return;
3088                                 }
3089                         }
3090
3091                         Invocation.EmitCall (ec, IsBase, IsStatic, instance_expr, getter, null, loc);
3092
3093                 }
3094
3095                 //
3096                 // Implements the IAssignMethod interface for assignments
3097                 //
3098                 public void EmitAssign (EmitContext ec, Expression source)
3099                 {
3100                         Argument arg = new Argument (source, Argument.AType.Expression);
3101                         ArrayList args = new ArrayList ();
3102
3103                         args.Add (arg);
3104                         Invocation.EmitCall (ec, IsBase, IsStatic, instance_expr, setter, args, loc);
3105                 }
3106
3107                 override public void EmitStatement (EmitContext ec)
3108                 {
3109                         Emit (ec);
3110                         ec.ig.Emit (OpCodes.Pop);
3111                 }
3112         }
3113
3114         /// <summary>
3115         ///   Fully resolved expression that evaluates to an Event
3116         /// </summary>
3117         public class EventExpr : Expression, IMemberExpr {
3118                 public readonly EventInfo EventInfo;
3119                 public Expression instance_expr;
3120
3121                 bool is_static;
3122                 MethodInfo add_accessor, remove_accessor;
3123
3124                 public EventExpr (EventInfo ei, Location loc)
3125                 {
3126                         EventInfo = ei;
3127                         this.loc = loc;
3128                         eclass = ExprClass.EventAccess;
3129
3130                         add_accessor = TypeManager.GetAddMethod (ei);
3131                         remove_accessor = TypeManager.GetRemoveMethod (ei);
3132
3133                         if (add_accessor.IsStatic || remove_accessor.IsStatic)
3134                                 is_static = true;
3135
3136                         if (EventInfo is MyEventBuilder){
3137                                 MyEventBuilder eb = (MyEventBuilder) EventInfo;
3138                                 type = eb.EventType;
3139                                 eb.SetUsed ();
3140                         } else
3141                                 type = EventInfo.EventHandlerType;
3142                 }
3143
3144                 public string Name {
3145                         get {
3146                                 return EventInfo.Name;
3147                         }
3148                 }
3149
3150                 public bool IsInstance {
3151                         get {
3152                                 return !is_static;
3153                         }
3154                 }
3155
3156                 public bool IsStatic {
3157                         get {
3158                                 return is_static;
3159                         }
3160                 }
3161
3162                 public Type DeclaringType {
3163                         get {
3164                                 return EventInfo.DeclaringType;
3165                         }
3166                 }
3167
3168                 public Expression InstanceExpression {
3169                         get {
3170                                 return instance_expr;
3171                         }
3172
3173                         set {
3174                                 instance_expr = value;
3175                         }
3176                 }
3177
3178                 public override Expression DoResolve (EmitContext ec)
3179                 {
3180                         if (instance_expr != null) {
3181                                 instance_expr = instance_expr.DoResolve (ec);
3182                                 if (instance_expr == null)
3183                                         return null;
3184                         }
3185
3186
3187                         return this;
3188                 }
3189
3190                 public override void Emit (EmitContext ec)
3191                 {
3192                         Report.Error (70, loc, "The event `" + Name + "' can only appear on the left hand side of += or -= (except on the defining type)");
3193                 }
3194
3195                 public void EmitAddOrRemove (EmitContext ec, Expression source)
3196                 {
3197                         BinaryDelegate source_del = (BinaryDelegate) source;
3198                         Expression handler = source_del.Right;
3199
3200                         Argument arg = new Argument (handler, Argument.AType.Expression);
3201                         ArrayList args = new ArrayList ();
3202
3203                         args.Add (arg);
3204
3205                         if (source_del.IsAddition)
3206                                 Invocation.EmitCall (
3207                                         ec, false, IsStatic, instance_expr, add_accessor, args, loc);
3208                         else
3209                                 Invocation.EmitCall (
3210                                         ec, false, IsStatic, instance_expr, remove_accessor, args, loc);
3211                 }
3212         }
3213 }