mcs/gmcs/generic.cs

   1 //
   2 // generic.cs: Generics support
   3 //
   4 // Authors: Martin Baulig (martin@ximian.com)
   5 //          Miguel de Icaza (miguel@ximian.com)
   6 //
   7 // Licensed under the terms of the GNU GPL
   8 //
   9 // (C) 2001, 2002, 2003 Ximian, Inc (http://www.ximian.com)
  10 // (C) 2004 Novell, Inc
  11 //
  12 using System;
  13 using System.Reflection;
  14 using System.Reflection.Emit;
  15 using System.Globalization;
  16 using System.Collections;
  17 using System.Text;
  18 using System.Text.RegularExpressions;
  19
  20 namespace Mono.CSharp {
  21
  22         /// <summary>
  23         ///   Abstract base class for type parameter constraints.
  24         ///   The type parameter can come from a generic type definition or from reflection.
  25         /// </summary>
  26         public abstract class GenericConstraints {
  27                 public abstract string TypeParameter {
  28                         get;
  29                 }
  30
  31                 public abstract GenericParameterAttributes Attributes {
  32                         get;
  33                 }
  34
  35                 public bool HasConstructorConstraint {
  36                         get { return (Attributes & GenericParameterAttributes.DefaultConstructorConstraint) != 0; }
  37                 }
  38
  39                 public bool HasReferenceTypeConstraint {
  40                         get { return (Attributes & GenericParameterAttributes.ReferenceTypeConstraint) != 0; }
  41                 }
  42
  43                 public bool HasValueTypeConstraint {
  44                         get { return (Attributes & GenericParameterAttributes.NotNullableValueTypeConstraint) != 0; }
  45                 }
  46
  47                 public virtual bool HasClassConstraint {
  48                         get { return ClassConstraint != null; }
  49                 }
  50
  51                 public abstract Type ClassConstraint {
  52                         get;
  53                 }
  54
  55                 public abstract Type[] InterfaceConstraints {
  56                         get;
  57                 }
  58
  59                 public abstract Type EffectiveBaseClass {
  60                         get;
  61                 }
  62
  63                 // <summary>
  64                 //   Returns whether the type parameter is "known to be a reference type".
  65                 // </summary>
  66                 public virtual bool IsReferenceType {
  67                         get {
  68                                 if (HasReferenceTypeConstraint)
  69                                         return true;
  70                                 if (HasValueTypeConstraint)
  71                                         return false;
  72
  73                                 if (ClassConstraint != null) {
  74                                         if (ClassConstraint.IsValueType)
  75                                                 return false;
  76
  77                                         if (ClassConstraint != TypeManager.object_type)
  78                                                 return true;
  79                                 }
  80
  81                                 foreach (Type t in InterfaceConstraints) {
  82                                         if (!t.IsGenericParameter)
  83                                                 continue;
  84
  85                                         GenericConstraints gc = TypeManager.GetTypeParameterConstraints (t);
  86                                         if ((gc != null) && gc.IsReferenceType)
  87                                                 return true;
  88                                 }
  89
  90                                 return false;
  91                         }
  92                 }
  93
  94                 // <summary>
  95                 //   Returns whether the type parameter is "known to be a value type".
  96                 // </summary>
  97                 public virtual bool IsValueType {
  98                         get {
  99                                 if (HasValueTypeConstraint)
 100                                         return true;
 101                                 if (HasReferenceTypeConstraint)
 102                                         return false;
 103
 104                                 if (ClassConstraint != null) {
 105                                         if (!ClassConstraint.IsValueType)
 106                                                 return false;
 107
 108                                         if (ClassConstraint != TypeManager.value_type)
 109                                                 return true;
 110                                 }
 111
 112                                 foreach (Type t in InterfaceConstraints) {
 113                                         if (!t.IsGenericParameter)
 114                                                 continue;
 115
 116                                         GenericConstraints gc = TypeManager.GetTypeParameterConstraints (t);
 117                                         if ((gc != null) && gc.IsValueType)
 118                                                 return true;
 119                                 }
 120
 121                                 return false;
 122                         }
 123                 }
 124         }
 125
 126         public enum SpecialConstraint
 127         {
 128                 Constructor,
 129                 ReferenceType,
 130                 ValueType
 131         }
 132
 133         /// <summary>
 134         ///   Tracks the constraints for a type parameter from a generic type definition.
 135         /// </summary>
 136         public class Constraints : GenericConstraints {
 137                 string name;
 138                 ArrayList constraints;
 139                 Location loc;
 140
 141                 //
 142                 // name is the identifier, constraints is an arraylist of
 143                 // Expressions (with types) or `true' for the constructor constraint.
 144                 //
 145                 public Constraints (string name, ArrayList constraints,
 146                                     Location loc)
 147                 {
 148                         this.name = name;
 149                         this.constraints = constraints;
 150                         this.loc = loc;
 151                 }
 152
 153                 public override string TypeParameter {
 154                         get {
 155                                 return name;
 156                         }
 157                 }
 158
 159                 public Constraints Clone ()
 160                 {
 161                         return new Constraints (name, constraints, loc);
 162                 }
 163
 164                 GenericParameterAttributes attrs;
 165                 TypeExpr class_constraint;
 166                 ArrayList iface_constraints;
 167                 ArrayList type_param_constraints;
 168                 int num_constraints;
 169                 Type class_constraint_type;
 170                 Type[] iface_constraint_types;
 171                 Type effective_base_type;
 172                 bool resolved;
 173                 bool resolved_types;
 174
 175                 /// <summary>
 176                 ///   Resolve the constraints - but only resolve things into Expression's, not
 177                 ///   into actual types.
 178                 /// </summary>
 179                 public bool Resolve (IResolveContext ec)
 180                 {
 181                         if (resolved)
 182                                 return true;
 183
 184                         iface_constraints = new ArrayList ();
 185                         type_param_constraints = new ArrayList ();
 186
 187                         foreach (object obj in constraints) {
 188                                 if (HasConstructorConstraint) {
 189                                         Report.Error (401, loc,
 190                                                       "The new() constraint must be the last constraint specified");
 191                                         return false;
 192                                 }
 193
 194                                 if (obj is SpecialConstraint) {
 195                                         SpecialConstraint sc = (SpecialConstraint) obj;
 196
 197                                         if (sc == SpecialConstraint.Constructor) {
 198                                                 if (!HasValueTypeConstraint) {
 199                                                         attrs |= GenericParameterAttributes.DefaultConstructorConstraint;
 200                                                         continue;
 201                                                 }
 202
 203                                                 Report.Error (451, loc, "The `new()' constraint " +
 204                                                         "cannot be used with the `struct' constraint");
 205                                                 return false;
 206                                         }
 207
 208                                         if ((num_constraints > 0) || HasReferenceTypeConstraint || HasValueTypeConstraint) {
 209                                                 Report.Error (449, loc, "The `class' or `struct' " +
 210                                                               "constraint must be the first constraint specified");
 211                                                 return false;
 212                                         }
 213
 214                                         if (sc == SpecialConstraint.ReferenceType)
 215                                                 attrs |= GenericParameterAttributes.ReferenceTypeConstraint;
 216                                         else
 217                                                 attrs |= GenericParameterAttributes.NotNullableValueTypeConstraint;
 218                                         continue;
 219                                 }
 220
 221                                 int errors = Report.Errors;
 222                                 FullNamedExpression fn = ((Expression) obj).ResolveAsTypeStep (ec, false);
 223
 224                                 if (fn == null) {
 225                                         if (errors != Report.Errors)
 226                                                 return false;
 227
 228                                         NamespaceEntry.Error_NamespaceNotFound (loc, ((Expression)obj).GetSignatureForError ());
 229                                         return false;
 230                                 }
 231
 232                                 TypeExpr expr;
 233                                 ConstructedType cexpr = fn as ConstructedType;
 234                                 if (cexpr != null) {
 235                                         if (!cexpr.ResolveConstructedType (ec))
 236                                                 return false;
 237
 238                                         expr = cexpr;
 239                                 } else
 240                                         expr = ((Expression) obj).ResolveAsTypeTerminal (ec, false);
 241
 242                                 if ((expr == null) || (expr.Type == null))
 243                                         return false;
 244
 245                                 // TODO: It's aleady done in ResolveAsBaseTerminal
 246                                 if (!ec.GenericDeclContainer.AsAccessible (fn.Type, ec.GenericDeclContainer.ModFlags)) {
 247                                         Report.SymbolRelatedToPreviousError (fn.Type);
 248                                         Report.Error (703, loc,
 249                                                 "Inconsistent accessibility: constraint type `{0}' is less accessible than `{1}'",
 250                                                 fn.GetSignatureForError (), ec.GenericDeclContainer.GetSignatureForError ());
 251                                         return false;
 252                                 }
 253
 254                                 TypeParameterExpr texpr = expr as TypeParameterExpr;
 255                                 if (texpr != null)
 256                                         type_param_constraints.Add (expr);
 257                                 else if (expr.IsInterface)
 258                                         iface_constraints.Add (expr);
 259                                 else if (class_constraint != null) {
 260                                         Report.Error (406, loc,
 261                                                       "`{0}': the class constraint for `{1}' " +
 262                                                       "must come before any other constraints.",
 263                                                       expr.Name, name);
 264                                         return false;
 265                                 } else if (HasReferenceTypeConstraint || HasValueTypeConstraint) {
 266                                         Report.Error (450, loc, "`{0}': cannot specify both " +
 267                                                       "a constraint class and the `class' " +
 268                                                       "or `struct' constraint", expr.GetSignatureForError ());
 269                                         return false;
 270                                 } else
 271                                         class_constraint = expr;
 272
 273                                 num_constraints++;
 274                         }
 275
 276                         ArrayList list = new ArrayList ();
 277                         foreach (TypeExpr iface_constraint in iface_constraints) {
 278                                 foreach (Type type in list) {
 279                                         if (!type.Equals (iface_constraint.Type))
 280                                                 continue;
 281
 282                                         Report.Error (405, loc,
 283                                                       "Duplicate constraint `{0}' for type " +
 284                                                       "parameter `{1}'.", iface_constraint.GetSignatureForError (),
 285                                                       name);
 286                                         return false;
 287                                 }
 288
 289                                 list.Add (iface_constraint.Type);
 290                         }
 291
 292                         foreach (TypeParameterExpr expr in type_param_constraints) {
 293                                 foreach (Type type in list) {
 294                                         if (!type.Equals (expr.Type))
 295                                                 continue;
 296
 297                                         Report.Error (405, loc,
 298                                                       "Duplicate constraint `{0}' for type " +
 299                                                       "parameter `{1}'.", expr.GetSignatureForError (), name);
 300                                         return false;
 301                                 }
 302
 303                                 list.Add (expr.Type);
 304                         }
 305
 306                         iface_constraint_types = new Type [list.Count];
 307                         list.CopyTo (iface_constraint_types, 0);
 308
 309                         if (class_constraint != null) {
 310                                 class_constraint_type = class_constraint.Type;
 311                                 if (class_constraint_type == null)
 312                                         return false;
 313
 314                                 if (class_constraint_type.IsSealed) {
 315                                         if (class_constraint_type.IsAbstract)
 316                                         {
 317                                                 Report.Error (717, loc, "`{0}' is not a valid constraint. Static classes cannot be used as constraints",
 318                                                         TypeManager.CSharpName (class_constraint_type));
 319                                         }
 320                                         else
 321                                         {
 322                                                 Report.Error (701, loc, "`{0}' is not a valid constraint. A constraint must be an interface, " +
 323                                                         "a non-sealed class or a type parameter", TypeManager.CSharpName(class_constraint_type));
 324                                         }
 325                                         return false;
 326                                 }
 327
 328                                 if ((class_constraint_type == TypeManager.array_type) ||
 329                                     (class_constraint_type == TypeManager.delegate_type) ||
 330                                     (class_constraint_type == TypeManager.enum_type) ||
 331                                     (class_constraint_type == TypeManager.value_type) ||
 332                                     (class_constraint_type == TypeManager.object_type)) {
 333                                         Report.Error (702, loc,
 334                                                       "Bound cannot be special class `{0}'",
 335                                                       TypeManager.CSharpName (class_constraint_type));
 336                                         return false;
 337                                 }
 338                         }
 339
 340                         if (class_constraint_type != null)
 341                                 effective_base_type = class_constraint_type;
 342                         else if (HasValueTypeConstraint)
 343                                 effective_base_type = TypeManager.value_type;
 344                         else
 345                                 effective_base_type = TypeManager.object_type;
 346
 347                         resolved = true;
 348                         return true;
 349                 }
 350
 351                 bool CheckTypeParameterConstraints (TypeParameter tparam, Hashtable seen)
 352                 {
 353                         seen.Add (tparam, true);
 354
 355                         Constraints constraints = tparam.Constraints;
 356                         if (constraints == null)
 357                                 return true;
 358
 359                         if (constraints.HasValueTypeConstraint) {
 360                                 Report.Error (456, loc, "Type parameter `{0}' has " +
 361                                               "the `struct' constraint, so it cannot " +
 362                                               "be used as a constraint for `{1}'",
 363                                               tparam.Name, name);
 364                                 return false;
 365                         }
 366
 367                         if (constraints.type_param_constraints == null)
 368                                 return true;
 369
 370                         foreach (TypeParameterExpr expr in constraints.type_param_constraints) {
 371                                 if (seen.Contains (expr.TypeParameter)) {
 372                                         Report.Error (454, loc, "Circular constraint " +
 373                                                       "dependency involving `{0}' and `{1}'",
 374                                                       tparam.Name, expr.Name);
 375                                         return false;
 376                                 }
 377
 378                                 if (!CheckTypeParameterConstraints (expr.TypeParameter, seen))
 379                                         return false;
 380                         }
 381
 382                         return true;
 383                 }
 384
 385                 /// <summary>
 386                 ///   Resolve the constraints into actual types.
 387                 /// </summary>
 388                 public bool ResolveTypes (IResolveContext ec)
 389                 {
 390                         if (resolved_types)
 391                                 return true;
 392
 393                         resolved_types = true;
 394
 395                         foreach (object obj in constraints) {
 396                                 ConstructedType cexpr = obj as ConstructedType;
 397                                 if (cexpr == null)
 398                                         continue;
 399
 400                                 if (!cexpr.CheckConstraints (ec))
 401                                         return false;
 402                         }
 403
 404                         foreach (TypeParameterExpr expr in type_param_constraints) {
 405                                 Hashtable seen = new Hashtable ();
 406                                 if (!CheckTypeParameterConstraints (expr.TypeParameter, seen))
 407                                         return false;
 408                         }
 409
 410                         for (int i = 0; i < iface_constraints.Count; ++i) {
 411                                 TypeExpr iface_constraint = (TypeExpr) iface_constraints [i];
 412                                 iface_constraint = iface_constraint.ResolveAsTypeTerminal (ec, false);
 413                                 if (iface_constraint == null)
 414                                         return false;
 415                                 iface_constraints [i] = iface_constraint;
 416                         }
 417
 418                         if (class_constraint != null) {
 419                                 class_constraint = class_constraint.ResolveAsTypeTerminal (ec, false);
 420                                 if (class_constraint == null)
 421                                         return false;
 422                         }
 423
 424                         return true;
 425                 }
 426
 427                 /// <summary>
 428                 ///   Check whether there are no conflicts in our type parameter constraints.
 429                 ///
 430                 ///   This is an example:
 431                 ///
 432                 ///   class Foo<T,U>
 433                 ///      where T : class
 434                 ///      where U : T, struct
 435                 /// </summary>
 436                 public bool CheckDependencies ()
 437                 {
 438                         foreach (TypeParameterExpr expr in type_param_constraints) {
 439                                 if (!CheckDependencies (expr.TypeParameter))
 440                                         return false;
 441                         }
 442
 443                         return true;
 444                 }
 445
 446                 bool CheckDependencies (TypeParameter tparam)
 447                 {
 448                         Constraints constraints = tparam.Constraints;
 449                         if (constraints == null)
 450                                 return true;
 451
 452                         if (HasValueTypeConstraint && constraints.HasClassConstraint) {
 453                                 Report.Error (455, loc, "Type parameter `{0}' inherits " +
 454                                               "conflicting constraints `{1}' and `{2}'",
 455                                               name, TypeManager.CSharpName (constraints.ClassConstraint),
 456                                               "System.ValueType");
 457                                 return false;
 458                         }
 459
 460                         if (HasClassConstraint && constraints.HasClassConstraint) {
 461                                 Type t1 = ClassConstraint;
 462                                 TypeExpr e1 = class_constraint;
 463                                 Type t2 = constraints.ClassConstraint;
 464                                 TypeExpr e2 = constraints.class_constraint;
 465
 466                                 if (!Convert.ImplicitReferenceConversionExists (e1, t2) &&
 467                                     !Convert.ImplicitReferenceConversionExists (e2, t1)) {
 468                                         Report.Error (455, loc,
 469                                                       "Type parameter `{0}' inherits " +
 470                                                       "conflicting constraints `{1}' and `{2}'",
 471                                                       name, TypeManager.CSharpName (t1), TypeManager.CSharpName (t2));
 472                                         return false;
 473                                 }
 474                         }
 475
 476                         if (constraints.type_param_constraints == null)
 477                                 return true;
 478
 479                         foreach (TypeParameterExpr expr in constraints.type_param_constraints) {
 480                                 if (!CheckDependencies (expr.TypeParameter))
 481                                         return false;
 482                         }
 483
 484                         return true;
 485                 }
 486
 487                 public override GenericParameterAttributes Attributes {
 488                         get { return attrs; }
 489                 }
 490
 491                 public override bool HasClassConstraint {
 492                         get { return class_constraint != null; }
 493                 }
 494
 495                 public override Type ClassConstraint {
 496                         get { return class_constraint_type; }
 497                 }
 498
 499                 public override Type[] InterfaceConstraints {
 500                         get { return iface_constraint_types; }
 501                 }
 502
 503                 public override Type EffectiveBaseClass {
 504                         get { return effective_base_type; }
 505                 }
 506
 507                 public bool IsSubclassOf (Type t)
 508                 {
 509                         if ((class_constraint_type != null) &&
 510                             class_constraint_type.IsSubclassOf (t))
 511                                 return true;
 512
 513                         if (iface_constraint_types == null)
 514                                 return false;
 515
 516                         foreach (Type iface in iface_constraint_types) {
 517                                 if (TypeManager.IsSubclassOf (iface, t))
 518                                         return true;
 519                         }
 520
 521                         return false;
 522                 }
 523
 524                 public Location Location {
 525                         get {
 526                                 return loc;
 527                         }
 528                 }
 529
 530                 /// <summary>
 531                 ///   This is used when we're implementing a generic interface method.
 532                 ///   Each method type parameter in implementing method must have the same
 533                 ///   constraints than the corresponding type parameter in the interface
 534                 ///   method.  To do that, we're called on each of the implementing method's
 535                 ///   type parameters.
 536                 /// </summary>
 537                 public bool CheckInterfaceMethod (GenericConstraints gc)
 538                 {
 539                         if (gc.Attributes != attrs)
 540                                 return false;
 541
 542                         if (HasClassConstraint != gc.HasClassConstraint)
 543                                 return false;
 544                         if (HasClassConstraint && !TypeManager.IsEqual (gc.ClassConstraint, ClassConstraint))
 545                                 return false;
 546
 547                         int gc_icount = gc.InterfaceConstraints != null ?
 548                                 gc.InterfaceConstraints.Length : 0;
 549                         int icount = InterfaceConstraints != null ?
 550                                 InterfaceConstraints.Length : 0;
 551
 552                         if (gc_icount != icount)
 553                                 return false;
 554
 555                         foreach (Type iface in gc.InterfaceConstraints) {
 556                                 bool ok = false;
 557                                 foreach (Type check in InterfaceConstraints) {
 558                                         if (TypeManager.IsEqual (iface, check)) {
 559                                                 ok = true;
 560                                                 break;
 561                                         }
 562                                 }
 563
 564                                 if (!ok)
 565                                         return false;
 566                         }
 567
 568                         return true;
 569                 }
 570
 571                 public void VerifyClsCompliance ()
 572                 {
 573                         if (class_constraint_type != null && !AttributeTester.IsClsCompliant (class_constraint_type))
 574                                 Warning_ConstrainIsNotClsCompliant (class_constraint_type, class_constraint.Location);
 575
 576                         if (iface_constraint_types != null) {
 577                                 for (int i = 0; i < iface_constraint_types.Length; ++i) {
 578                                         if (!AttributeTester.IsClsCompliant (iface_constraint_types [i]))
 579                                                 Warning_ConstrainIsNotClsCompliant (iface_constraint_types [i],
 580                                                         ((TypeExpr)iface_constraints [i]).Location);
 581                                 }
 582                         }
 583                 }
 584
 585                 void Warning_ConstrainIsNotClsCompliant (Type t, Location loc)
 586                 {
 587                         Report.SymbolRelatedToPreviousError (t);
 588                         Report.Warning (3024, 1, loc, "Constraint type `{0}' is not CLS-compliant",
 589                                 TypeManager.CSharpName (t));
 590                 }
 591         }
 592
 593         /// <summary>
 594         ///   A type parameter from a generic type definition.
 595         /// </summary>
 596         public class TypeParameter : MemberCore, IMemberContainer {
 597                 string name;
 598                 DeclSpace decl;
 599                 GenericConstraints gc;
 600                 Constraints constraints;
 601                 Location loc;
 602                 GenericTypeParameterBuilder type;
 603
 604                 public TypeParameter (DeclSpace parent, DeclSpace decl, string name,
 605                                       Constraints constraints, Attributes attrs, Location loc)
 606                         : base (parent, new MemberName (name, loc), attrs)
 607                 {
 608                         this.name = name;
 609                         this.decl = decl;
 610                         this.constraints = constraints;
 611                         this.loc = loc;
 612                 }
 613
 614                 public GenericConstraints GenericConstraints {
 615                         get { return gc != null ? gc : constraints; }
 616                 }
 617
 618                 public Constraints Constraints {
 619                         get { return constraints; }
 620                 }
 621
 622                 public bool HasConstructorConstraint {
 623                         get { return constraints != null && constraints.HasConstructorConstraint; }
 624                 }
 625
 626                 public DeclSpace DeclSpace {
 627                         get { return decl; }
 628                 }
 629
 630                 public Type Type {
 631                         get { return type; }
 632                 }
 633
 634                 /// <summary>
 635                 ///   This is the first method which is called during the resolving
 636                 ///   process; we're called immediately after creating the type parameters
 637                 ///   with SRE (by calling `DefineGenericParameters()' on the TypeBuilder /
 638                 ///   MethodBuilder).
 639                 ///
 640                 ///   We're either called from TypeContainer.DefineType() or from
 641                 ///   GenericMethod.Define() (called from Method.Define()).
 642                 /// </summary>
 643                 public void Define (GenericTypeParameterBuilder type)
 644                 {
 645                         if (this.type != null)
 646                                 throw new InvalidOperationException ();
 647
 648                         this.type = type;
 649                         TypeManager.AddTypeParameter (type, this);
 650                 }
 651
 652                 /// <summary>
 653                 ///   This is the second method which is called during the resolving
 654                 ///   process - in case of class type parameters, we're called from
 655                 ///   TypeContainer.ResolveType() - after it resolved the class'es
 656                 ///   base class and interfaces. For method type parameters, we're
 657                 ///   called immediately after Define().
 658                 ///
 659                 ///   We're just resolving the constraints into expressions here, we
 660                 ///   don't resolve them into actual types.
 661                 ///
 662                 ///   Note that in the special case of partial generic classes, we may be
 663                 ///   called _before_ Define() and we may also be called multiple types.
 664                 /// </summary>
 665                 public bool Resolve (DeclSpace ds)
 666                 {
 667                         if (constraints != null) {
 668                                 if (!constraints.Resolve (ds)) {
 669                                         constraints = null;
 670                                         return false;
 671                                 }
 672                         }
 673
 674                         return true;
 675                 }
 676
 677                 /// <summary>
 678                 ///   This is the third method which is called during the resolving
 679                 ///   process.  We're called immediately after calling DefineConstraints()
 680                 ///   on all of the current class'es type parameters.
 681                 ///
 682                 ///   Our job is to resolve the constraints to actual types.
 683                 ///
 684                 ///   Note that we may have circular dependencies on type parameters - this
 685                 ///   is why Resolve() and ResolveType() are separate.
 686                 /// </summary>
 687                 public bool ResolveType (IResolveContext ec)
 688                 {
 689                         if (constraints != null) {
 690                                 if (!constraints.ResolveTypes (ec)) {
 691                                         constraints = null;
 692                                         return false;
 693                                 }
 694                         }
 695
 696                         return true;
 697                 }
 698
 699                 /// <summary>
 700                 ///   This is the fourth and last method which is called during the resolving
 701                 ///   process.  We're called after everything is fully resolved and actually
 702                 ///   register the constraints with SRE and the TypeManager.
 703                 /// </summary>
 704                 public bool DefineType (IResolveContext ec)
 705                 {
 706                         return DefineType (ec, null, null, false);
 707                 }
 708
 709                 /// <summary>
 710                 ///   This is the fith and last method which is called during the resolving
 711                 ///   process.  We're called after everything is fully resolved and actually
 712                 ///   register the constraints with SRE and the TypeManager.
 713                 ///
 714                 ///   The `builder', `implementing' and `is_override' arguments are only
 715                 ///   applicable to method type parameters.
 716                 /// </summary>
 717                 public bool DefineType (IResolveContext ec, MethodBuilder builder,
 718                                         MethodInfo implementing, bool is_override)
 719                 {
 720                         if (!ResolveType (ec))
 721                                 return false;
 722
 723                         if (implementing != null) {
 724                                 if (is_override && (constraints != null)) {
 725                                         Report.Error (460, loc,
 726                                                 "`{0}': Cannot specify constraints for overrides or explicit interface implementation methods",
 727                                                 TypeManager.CSharpSignature (builder));
 728                                         return false;
 729                                 }
 730
 731                                 MethodBase mb = TypeManager.DropGenericMethodArguments (implementing);
 732
 733                                 int pos = type.GenericParameterPosition;
 734                                 Type mparam = mb.GetGenericArguments () [pos];
 735                                 GenericConstraints temp_gc = ReflectionConstraints.GetConstraints (mparam);
 736
 737                                 if (temp_gc != null)
 738                                         gc = new InflatedConstraints (temp_gc, implementing.DeclaringType);
 739                                 else if (constraints != null)
 740                                         gc = new InflatedConstraints (constraints, implementing.DeclaringType);
 741
 742                                 bool ok = true;
 743                                 if (constraints != null) {
 744                                         if (temp_gc == null)
 745                                                 ok = false;
 746                                         else if (!constraints.CheckInterfaceMethod (gc))
 747                                                 ok = false;
 748                                 } else {
 749                                         if (!is_override && (temp_gc != null))
 750                                                 ok = false;
 751                                 }
 752
 753                                 if (!ok) {
 754                                         Report.SymbolRelatedToPreviousError (implementing);
 755
 756                                         Report.Error (
 757                                                 425, loc, "The constraints for type " +
 758                                                 "parameter `{0}' of method `{1}' must match " +
 759                                                 "the constraints for type parameter `{2}' " +
 760                                                 "of interface method `{3}'. Consider using " +
 761                                                 "an explicit interface implementation instead",
 762                                                 Name, TypeManager.CSharpSignature (builder),
 763                                                 TypeManager.CSharpName (mparam), TypeManager.CSharpSignature (mb));
 764                                         return false;
 765                                 }
 766                         } else if (DeclSpace is CompilerGeneratedClass) {
 767                                 TypeParameter[] tparams = DeclSpace.TypeParameters;
 768                                 Type[] types = new Type [tparams.Length];
 769                                 for (int i = 0; i < tparams.Length; i++)
 770                                         types [i] = tparams [i].Type;
 771
 772                                 if (constraints != null)
 773                                         gc = new InflatedConstraints (constraints, types);
 774                         } else {
 775                                 gc = (GenericConstraints) constraints;
 776                         }
 777
 778                         if (gc == null)
 779                                 return true;
 780
 781                         if (gc.HasClassConstraint)
 782                                 type.SetBaseTypeConstraint (gc.ClassConstraint);
 783
 784                         type.SetInterfaceConstraints (gc.InterfaceConstraints);
 785                         type.SetGenericParameterAttributes (gc.Attributes);
 786                         TypeManager.RegisterBuilder (type, gc.InterfaceConstraints);
 787
 788                         return true;
 789                 }
 790
 791                 /// <summary>
 792                 ///   Check whether there are no conflicts in our type parameter constraints.
 793                 ///
 794                 ///   This is an example:
 795                 ///
 796                 ///   class Foo<T,U>
 797                 ///      where T : class
 798                 ///      where U : T, struct
 799                 /// </summary>
 800                 public bool CheckDependencies ()
 801                 {
 802                         if (constraints != null)
 803                                 return constraints.CheckDependencies ();
 804
 805                         return true;
 806                 }
 807
 808                 /// <summary>
 809                 ///   This is called for each part of a partial generic type definition.
 810                 ///
 811                 ///   If `new_constraints' is not null and we don't already have constraints,
 812                 ///   they become our constraints.  If we already have constraints, we must
 813                 ///   check that they're the same.
 814                 ///   con
 815                 /// </summary>
 816                 public bool UpdateConstraints (IResolveContext ec, Constraints new_constraints)
 817                 {
 818                         if (type == null)
 819                                 throw new InvalidOperationException ();
 820
 821                         if (new_constraints == null)
 822                                 return true;
 823
 824                         if (!new_constraints.Resolve (ec))
 825                                 return false;
 826                         if (!new_constraints.ResolveTypes (ec))
 827                                 return false;
 828
 829                         if (constraints != null)
 830                                 return constraints.CheckInterfaceMethod (new_constraints);
 831
 832                         constraints = new_constraints;
 833                         return true;
 834                 }
 835
 836                 public void EmitAttributes ()
 837                 {
 838                         if (OptAttributes != null)
 839                                 OptAttributes.Emit ();
 840                 }
 841
 842                 public override string DocCommentHeader {
 843                         get {
 844                                 throw new InvalidOperationException (
 845                                         "Unexpected attempt to get doc comment from " + this.GetType () + ".");
 846                         }
 847                 }
 848
 849                 //
 850                 // MemberContainer
 851                 //
 852
 853                 public override bool Define ()
 854                 {
 855                         return true;
 856                 }
 857
 858                 public override void ApplyAttributeBuilder (Attribute a,
 859                                                             CustomAttributeBuilder cb)
 860                 {
 861                         type.SetCustomAttribute (cb);
 862                 }
 863
 864                 public override AttributeTargets AttributeTargets {
 865                         get {
 866                                 return (AttributeTargets) AttributeTargets.GenericParameter;
 867                         }
 868                 }
 869
 870                 public override string[] ValidAttributeTargets {
 871                         get {
 872                                 return new string [] { "type parameter" };
 873                         }
 874                 }
 875
 876                 //
 877                 // IMemberContainer
 878                 //
 879
 880                 string IMemberContainer.Name {
 881                         get { return Name; }
 882                 }
 883
 884                 MemberCache IMemberContainer.BaseCache {
 885                         get { return null; }
 886                 }
 887
 888                 bool IMemberContainer.IsInterface {
 889                         get { return true; }
 890                 }
 891
 892                 MemberList IMemberContainer.GetMembers (MemberTypes mt, BindingFlags bf)
 893                 {
 894                         return FindMembers (mt, bf, null, null);
 895                 }
 896
 897                 MemberCache IMemberContainer.MemberCache {
 898                         get { return null; }
 899                 }
 900
 901                 public MemberList FindMembers (MemberTypes mt, BindingFlags bf,
 902                                                MemberFilter filter, object criteria)
 903                 {
 904                         if (gc == null)
 905                                 return MemberList.Empty;
 906
 907                         ArrayList members = new ArrayList ();
 908
 909                         if (gc.HasClassConstraint) {
 910                                 MemberList list = TypeManager.FindMembers (
 911                                         gc.ClassConstraint, mt, bf, filter, criteria);
 912
 913                                 members.AddRange (list);
 914                         }
 915
 916                         Type[] ifaces = TypeManager.ExpandInterfaces (gc.InterfaceConstraints);
 917                         foreach (Type t in ifaces) {
 918                                 MemberList list = TypeManager.FindMembers (
 919                                         t, mt, bf, filter, criteria);
 920
 921                                 members.AddRange (list);
 922                         }
 923
 924                         return new MemberList (members);
 925                 }
 926
 927                 public bool IsSubclassOf (Type t)
 928                 {
 929                         if (type.Equals (t))
 930                                 return true;
 931
 932                         if (constraints != null)
 933                                 return constraints.IsSubclassOf (t);
 934
 935                         return false;
 936                 }
 937
 938                 public override string ToString ()
 939                 {
 940                         return "TypeParameter[" + name + "]";
 941                 }
 942
 943                 public static string GetSignatureForError (TypeParameter[] tp)
 944                 {
 945                         if (tp == null || tp.Length == 0)
 946                                 return "";
 947
 948                         StringBuilder sb = new StringBuilder ("<");
 949                         for (int i = 0; i < tp.Length; ++i) {
 950                                 if (i > 0)
 951                                         sb.Append (",");
 952                                 sb.Append (tp[i].GetSignatureForError ());
 953                         }
 954                         sb.Append ('>');
 955                         return sb.ToString ();
 956                 }
 957
 958                 public void InflateConstraints (Type declaring)
 959                 {
 960                         if (constraints != null)
 961                                 gc = new InflatedConstraints (constraints, declaring);
 962                 }
 963
 964                 protected class InflatedConstraints : GenericConstraints
 965                 {
 966                         GenericConstraints gc;
 967                         Type base_type;
 968                         Type class_constraint;
 969                         Type[] iface_constraints;
 970                         Type[] dargs;
 971
 972                         public InflatedConstraints (GenericConstraints gc, Type declaring)
 973                                 : this (gc, TypeManager.GetTypeArguments (declaring))
 974                         { }
 975
 976                         public InflatedConstraints (GenericConstraints gc, Type[] dargs)
 977                         {
 978                                 this.gc = gc;
 979                                 this.dargs = dargs;
 980
 981                                 ArrayList list = new ArrayList ();
 982                                 if (gc.HasClassConstraint)
 983                                         list.Add (inflate (gc.ClassConstraint));
 984                                 foreach (Type iface in gc.InterfaceConstraints)
 985                                         list.Add (inflate (iface));
 986
 987                                 bool has_class_constr = false;
 988                                 if (list.Count > 0) {
 989                                         Type first = (Type) list [0];
 990                                         has_class_constr = !first.IsInterface && !first.IsGenericParameter;
 991                                 }
 992
 993                                 if ((list.Count > 0) && has_class_constr) {
 994                                         class_constraint = (Type) list [0];
 995                                         iface_constraints = new Type [list.Count - 1];
 996                                         list.CopyTo (1, iface_constraints, 0, list.Count - 1);
 997                                 } else {
 998                                         iface_constraints = new Type [list.Count];
 999                                         list.CopyTo (iface_constraints, 0);
1000                                 }
1001
1002                                 if (HasValueTypeConstraint)
1003                                         base_type = TypeManager.value_type;
1004                                 else if (class_constraint != null)
1005                                         base_type = class_constraint;
1006                                 else
1007                                         base_type = TypeManager.object_type;
1008                         }
1009
1010                         Type inflate (Type t)
1011                         {
1012                                 if (t == null)
1013                                         return null;
1014                                 if (t.IsGenericParameter)
1015                                         return dargs [t.GenericParameterPosition];
1016                                 if (t.IsGenericType) {
1017                                         Type[] args = t.GetGenericArguments ();
1018                                         Type[] inflated = new Type [args.Length];
1019
1020                                         for (int i = 0; i < args.Length; i++)
1021                                                 inflated [i] = inflate (args [i]);
1022
1023                                         t = t.GetGenericTypeDefinition ();
1024                                         t = t.MakeGenericType (inflated);
1025                                 }
1026
1027                                 return t;
1028                         }
1029
1030                         public override string TypeParameter {
1031                                 get { return gc.TypeParameter; }
1032                         }
1033
1034                         public override GenericParameterAttributes Attributes {
1035                                 get { return gc.Attributes; }
1036                         }
1037
1038                         public override Type ClassConstraint {
1039                                 get { return class_constraint; }
1040                         }
1041
1042                         public override Type EffectiveBaseClass {
1043                                 get { return base_type; }
1044                         }
1045
1046                         public override Type[] InterfaceConstraints {
1047                                 get { return iface_constraints; }
1048                         }
1049                 }
1050         }
1051
1052         /// <summary>
1053         ///   A TypeExpr which already resolved to a type parameter.
1054         /// </summary>
1055         public class TypeParameterExpr : TypeExpr {
1056                 TypeParameter type_parameter;
1057
1058                 public override string Name {
1059                         get {
1060                                 return type_parameter.Name;
1061                         }
1062                 }
1063
1064                 public override string FullName {
1065                         get {
1066                                 return type_parameter.Name;
1067                         }
1068                 }
1069
1070                 public TypeParameter TypeParameter {
1071                         get {
1072                                 return type_parameter;
1073                         }
1074                 }
1075
1076                 public TypeParameterExpr (TypeParameter type_parameter, Location loc)
1077                 {
1078                         this.type_parameter = type_parameter;
1079                         this.loc = loc;
1080                 }
1081
1082                 protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
1083                 {
1084                         type = type_parameter.Type;
1085
1086                         return this;
1087                 }
1088
1089                 public override bool IsInterface {
1090                         get { return false; }
1091                 }
1092
1093                 public override bool CheckAccessLevel (DeclSpace ds)
1094                 {
1095                         return true;
1096                 }
1097
1098                 public void Error_CannotUseAsUnmanagedType (Location loc)
1099                 {
1100                         Report.Error (-203, loc, "Can not use type parameter as unmanaged type");
1101                 }
1102         }
1103
1104         /// <summary>
1105         ///   Tracks the type arguments when instantiating a generic type.  We're used in
1106         ///   ConstructedType.
1107         /// </summary>
1108         public class TypeArguments {
1109                 public readonly Location Location;
1110                 ArrayList args;
1111                 Type[] atypes;
1112                 int dimension;
1113                 bool has_type_args;
1114                 bool created;
1115
1116                 public TypeArguments (Location loc)
1117                 {
1118                         args = new ArrayList ();
1119                         this.Location = loc;
1120                 }
1121
1122                 public TypeArguments (int dimension, Location loc)
1123                 {
1124                         this.dimension = dimension;
1125                         this.Location = loc;
1126                 }
1127
1128                 public void Add (Expression type)
1129                 {
1130                         if (created)
1131                                 throw new InvalidOperationException ();
1132
1133                         args.Add (type);
1134                 }
1135
1136                 public void Add (TypeArguments new_args)
1137                 {
1138                         if (created)
1139                                 throw new InvalidOperationException ();
1140
1141                         args.AddRange (new_args.args);
1142                 }
1143
1144                 /// <summary>
1145                 ///   We're used during the parsing process: the parser can't distinguish
1146                 ///   between type parameters and type arguments.  Because of that, the
1147                 ///   parser creates a `MemberName' with `TypeArguments' for both cases and
1148                 ///   in case of a generic type definition, we call GetDeclarations().
1149                 /// </summary>
1150                 public TypeParameterName[] GetDeclarations ()
1151                 {
1152                         TypeParameterName[] ret = new TypeParameterName [args.Count];
1153                         for (int i = 0; i < args.Count; i++) {
1154                                 TypeParameterName name = args [i] as TypeParameterName;
1155                                 if (name != null) {
1156                                         ret [i] = name;
1157                                         continue;
1158                                 }
1159                                 SimpleName sn = args [i] as SimpleName;
1160                                 if (sn != null) {
1161                                         ret [i] = new TypeParameterName (sn.Name, null, sn.Location);
1162                                         continue;
1163                                 }
1164
1165                                 Report.Error (81, Location, "Type parameter declaration " +
1166                                               "must be an identifier not a type");
1167                                 return null;
1168                         }
1169                         return ret;
1170                 }
1171
1172                 /// <summary>
1173                 ///   We may only be used after Resolve() is called and return the fully
1174                 ///   resolved types.
1175                 /// </summary>
1176                 public Type[] Arguments {
1177                         get {
1178                                 return atypes;
1179                         }
1180                 }
1181
1182                 public bool HasTypeArguments {
1183                         get {
1184                                 return has_type_args;
1185                         }
1186                 }
1187
1188                 public int Count {
1189                         get {
1190                                 if (dimension > 0)
1191                                         return dimension;
1192                                 else
1193                                         return args.Count;
1194                         }
1195                 }
1196
1197                 public bool IsUnbound {
1198                         get {
1199                                 return dimension > 0;
1200                         }
1201                 }
1202
1203                 public override string ToString ()
1204                 {
1205                         StringBuilder s = new StringBuilder ();
1206
1207                         int count = Count;
1208                         for (int i = 0; i < count; i++){
1209                                 //
1210                                 // FIXME: Use TypeManager.CSharpname once we have the type
1211                                 //
1212                                 if (args != null)
1213                                         s.Append (args [i].ToString ());
1214                                 if (i+1 < count)
1215                                         s.Append (",");
1216                         }
1217                         return s.ToString ();
1218                 }
1219
1220                 public string GetSignatureForError()
1221                 {
1222                         StringBuilder sb = new StringBuilder();
1223                         for (int i = 0; i < Count; ++i)
1224                         {
1225                                 Expression expr = (Expression)args [i];
1226                                 sb.Append(expr.GetSignatureForError());
1227                                 if (i + 1 < Count)
1228                                         sb.Append(',');
1229                         }
1230                         return sb.ToString();
1231                 }
1232
1233                 /// <summary>
1234                 ///   Resolve the type arguments.
1235                 /// </summary>
1236                 public bool Resolve (IResolveContext ec)
1237                 {
1238                         int count = args.Count;
1239                         bool ok = true;
1240
1241                         atypes = new Type [count];
1242
1243                         for (int i = 0; i < count; i++){
1244                                 TypeExpr te = ((Expression) args [i]).ResolveAsTypeTerminal (ec, false);
1245                                 if (te == null) {
1246                                         ok = false;
1247                                         continue;
1248                                 }
1249                                 if (te is TypeParameterExpr)
1250                                         has_type_args = true;
1251
1252 #if !MS_COMPATIBLE
1253                                 if (te.Type.IsSealed && te.Type.IsAbstract) {
1254                                         Report.Error (718, Location, "`{0}': static classes cannot be used as generic arguments",
1255                                                 te.GetSignatureForError ());
1256                                         return false;
1257                                 }
1258 #endif
1259                                 if (te.Type.IsPointer) {
1260                                         Report.Error (306, Location, "The type `{0}' may not be used " +
1261                                                           "as a type argument", TypeManager.CSharpName (te.Type));
1262                                         return false;
1263                                 }
1264
1265                                 if (te.Type == TypeManager.void_type) {
1266                                         Expression.Error_VoidInvalidInTheContext (Location);
1267                                         return false;
1268                                 }
1269
1270                                 atypes [i] = te.Type;
1271                         }
1272                         return ok;
1273                 }
1274         }
1275
1276         public class TypeParameterName : SimpleName
1277         {
1278                 Attributes attributes;
1279
1280                 public TypeParameterName (string name, Attributes attrs, Location loc)
1281                         : base (name, loc)
1282                 {
1283                         attributes = attrs;
1284                 }
1285
1286                 public Attributes OptAttributes {
1287                         get {
1288                                 return attributes;
1289                         }
1290                 }
1291         }
1292
1293         /// <summary>
1294         ///   An instantiation of a generic type.
1295         /// </summary>
1296         public class ConstructedType : TypeExpr {
1297                 string full_name;
1298                 FullNamedExpression name;
1299                 TypeArguments args;
1300                 Type[] gen_params, atypes;
1301                 Type gt;
1302
1303                 /// <summary>
1304                 ///   Instantiate the generic type `fname' with the type arguments `args'.
1305                 /// </summary>
1306                 public ConstructedType (FullNamedExpression fname, TypeArguments args, Location l)
1307                 {
1308                         loc = l;
1309                         this.name = fname;
1310                         this.args = args;
1311
1312                         eclass = ExprClass.Type;
1313                         full_name = name + "<" + args.ToString () + ">";
1314                 }
1315
1316                 protected ConstructedType (TypeArguments args, Location l)
1317                 {
1318                         loc = l;
1319                         this.args = args;
1320
1321                         eclass = ExprClass.Type;
1322                 }
1323
1324                 protected ConstructedType (TypeParameter[] type_params, Location l)
1325                 {
1326                         loc = l;
1327
1328                         args = new TypeArguments (l);
1329                         foreach (TypeParameter type_param in type_params)
1330                                 args.Add (new TypeParameterExpr (type_param, l));
1331
1332                         eclass = ExprClass.Type;
1333                 }
1334
1335                 /// <summary>
1336                 ///   This is used to construct the `this' type inside a generic type definition.
1337                 /// </summary>
1338                 public ConstructedType (Type t, TypeParameter[] type_params, Location l)
1339                         : this (type_params, l)
1340                 {
1341                         gt = t.GetGenericTypeDefinition ();
1342
1343                         this.name = new TypeExpression (gt, l);
1344                         full_name = gt.FullName + "<" + args.ToString () + ">";
1345                 }
1346
1347                 /// <summary>
1348                 ///   Instantiate the generic type `t' with the type arguments `args'.
1349                 ///   Use this constructor if you already know the fully resolved
1350                 ///   generic type.
1351                 /// </summary>
1352                 public ConstructedType (Type t, TypeArguments args, Location l)
1353                         : this (args, l)
1354                 {
1355                         gt = t.GetGenericTypeDefinition ();
1356
1357                         this.name = new TypeExpression (gt, l);
1358                         full_name = gt.FullName + "<" + args.ToString () + ">";
1359                 }
1360
1361                 public TypeArguments TypeArguments {
1362                         get { return args; }
1363                 }
1364
1365                 public override string GetSignatureForError ()
1366                 {
1367                         return TypeManager.RemoveGenericArity (gt.FullName) + "<" + args.GetSignatureForError () + ">";
1368                 }
1369
1370                 protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
1371                 {
1372                         if (!ResolveConstructedType (ec))
1373                                 return null;
1374
1375                         return this;
1376                 }
1377
1378                 /// <summary>
1379                 ///   Check the constraints; we're called from ResolveAsTypeTerminal()
1380                 ///   after fully resolving the constructed type.
1381                 /// </summary>
1382                 public bool CheckConstraints (IResolveContext ec)
1383                 {
1384                         return ConstraintChecker.CheckConstraints (ec, gt, gen_params, atypes, loc);
1385                 }
1386
1387                 /// <summary>
1388                 ///   Resolve the constructed type, but don't check the constraints.
1389                 /// </summary>
1390                 public bool ResolveConstructedType (IResolveContext ec)
1391                 {
1392                         if (type != null)
1393                                 return true;
1394                         // If we already know the fully resolved generic type.
1395                         if (gt != null)
1396                                 return DoResolveType (ec);
1397
1398                         int num_args;
1399                         Type t = name.Type;
1400
1401                         if (t == null) {
1402                                 Report.Error (246, loc, "Cannot find type `{0}'<...>", Name);
1403                                 return false;
1404                         }
1405
1406                         num_args = TypeManager.GetNumberOfTypeArguments (t);
1407                         if (num_args == 0) {
1408                                 Report.Error (308, loc,
1409                                               "The non-generic type `{0}' cannot " +
1410                                               "be used with type arguments.",
1411                                               TypeManager.CSharpName (t));
1412                                 return false;
1413                         }
1414
1415                         gt = t.GetGenericTypeDefinition ();
1416                         return DoResolveType (ec);
1417                 }
1418
1419                 bool DoResolveType (IResolveContext ec)
1420                 {
1421                         //
1422                         // Resolve the arguments.
1423                         //
1424                         if (args.Resolve (ec) == false)
1425                                 return false;
1426
1427                         gen_params = gt.GetGenericArguments ();
1428                         atypes = args.Arguments;
1429
1430                         if (atypes.Length != gen_params.Length) {
1431                                 Report.Error (305, loc,
1432                                               "Using the generic type `{0}' " +
1433                                               "requires {1} type arguments",
1434                                               TypeManager.CSharpName (gt),
1435                                               gen_params.Length.ToString ());
1436                                 return false;
1437                         }
1438
1439                         //
1440                         // Now bind the parameters.
1441                         //
1442                         type = gt.MakeGenericType (atypes);
1443                         return true;
1444                 }
1445
1446                 public Expression GetSimpleName (EmitContext ec)
1447                 {
1448                         return this;
1449                 }
1450
1451                 public override bool CheckAccessLevel (DeclSpace ds)
1452                 {
1453                         return ds.CheckAccessLevel (gt);
1454                 }
1455
1456                 public override bool AsAccessible (DeclSpace ds, int flags)
1457                 {
1458                         foreach (Type t in atypes) {
1459                                 if (!ds.AsAccessible (t, flags))
1460                                         return false;
1461                         }
1462
1463                         return ds.AsAccessible (gt, flags);
1464                 }
1465
1466                 public override bool IsClass {
1467                         get { return gt.IsClass; }
1468                 }
1469
1470                 public override bool IsValueType {
1471                         get { return gt.IsValueType; }
1472                 }
1473
1474                 public override bool IsInterface {
1475                         get { return gt.IsInterface; }
1476                 }
1477
1478                 public override bool IsSealed {
1479                         get { return gt.IsSealed; }
1480                 }
1481
1482                 public override bool Equals (object obj)
1483                 {
1484                         ConstructedType cobj = obj as ConstructedType;
1485                         if (cobj == null)
1486                                 return false;
1487
1488                         if ((type == null) || (cobj.type == null))
1489                                 return false;
1490
1491                         return type == cobj.type;
1492                 }
1493
1494                 public override int GetHashCode ()
1495                 {
1496                         return base.GetHashCode ();
1497                 }
1498
1499                 public override string Name {
1500                         get {
1501                                 return full_name;
1502                         }
1503                 }
1504
1505                 public override string FullName {
1506                         get {
1507                                 return full_name;
1508                         }
1509                 }
1510         }
1511
1512         public abstract class ConstraintChecker
1513         {
1514                 protected readonly Type[] gen_params;
1515                 protected readonly Type[] atypes;
1516                 protected readonly Location loc;
1517
1518                 protected ConstraintChecker (Type[] gen_params, Type[] atypes, Location loc)
1519                 {
1520                         this.gen_params = gen_params;
1521                         this.atypes = atypes;
1522                         this.loc = loc;
1523                 }
1524
1525                 /// <summary>
1526                 ///   Check the constraints; we're called from ResolveAsTypeTerminal()
1527                 ///   after fully resolving the constructed type.
1528                 /// </summary>
1529                 public bool CheckConstraints (IResolveContext ec)
1530                 {
1531                         for (int i = 0; i < gen_params.Length; i++) {
1532                                 if (!CheckConstraints (ec, i))
1533                                         return false;
1534                         }
1535
1536                         return true;
1537                 }
1538
1539                 protected bool CheckConstraints (IResolveContext ec, int index)
1540                 {
1541                         Type atype = atypes [index];
1542                         Type ptype = gen_params [index];
1543
1544                         if (atype == ptype)
1545                                 return true;
1546
1547                         Expression aexpr = new EmptyExpression (atype);
1548
1549                         GenericConstraints gc = TypeManager.GetTypeParameterConstraints (ptype);
1550                         if (gc == null)
1551                                 return true;
1552
1553                         bool is_class, is_struct;
1554                         if (atype.IsGenericParameter) {
1555                                 GenericConstraints agc = TypeManager.GetTypeParameterConstraints (atype);
1556                                 if (agc != null) {
1557                                         if (agc is Constraints)
1558                                                 ((Constraints) agc).Resolve (ec);
1559                                         is_class = agc.IsReferenceType;
1560                                         is_struct = agc.IsValueType;
1561                                 } else {
1562                                         is_class = is_struct = false;
1563                                 }
1564                         } else {
1565 #if MS_COMPATIBLE
1566                                 is_class = false;
1567                                 if (!atype.IsGenericType)
1568 #endif
1569                                 is_class = atype.IsClass || atype.IsInterface;
1570                                 is_struct = atype.IsValueType && !TypeManager.IsNullableType (atype);
1571                         }
1572
1573                         //
1574                         // First, check the `class' and `struct' constraints.
1575                         //
1576                         if (gc.HasReferenceTypeConstraint && !is_class) {
1577                                 Report.Error (452, loc, "The type `{0}' must be " +
1578                                               "a reference type in order to use it " +
1579                                               "as type parameter `{1}' in the " +
1580                                               "generic type or method `{2}'.",
1581                                               TypeManager.CSharpName (atype),
1582                                               TypeManager.CSharpName (ptype),
1583                                               GetSignatureForError ());
1584                                 return false;
1585                         } else if (gc.HasValueTypeConstraint && !is_struct) {
1586                                 Report.Error (453, loc, "The type `{0}' must be a " +
1587                                               "non-nullable value type in order to use it " +
1588                                               "as type parameter `{1}' in the " +
1589                                               "generic type or method `{2}'.",
1590                                               TypeManager.CSharpName (atype),
1591                                               TypeManager.CSharpName (ptype),
1592                                               GetSignatureForError ());
1593                                 return false;
1594                         }
1595
1596                         //
1597                         // The class constraint comes next.
1598                         //
1599                         if (gc.HasClassConstraint) {
1600                                 if (!CheckConstraint (ec, ptype, aexpr, gc.ClassConstraint))
1601                                         return false;
1602                         }
1603
1604                         //
1605                         // Now, check the interface constraints.
1606                         //
1607                         if (gc.InterfaceConstraints != null) {
1608                                 foreach (Type it in gc.InterfaceConstraints) {
1609                                         if (!CheckConstraint (ec, ptype, aexpr, it))
1610                                                 return false;
1611                                 }
1612                         }
1613
1614                         //
1615                         // Finally, check the constructor constraint.
1616                         //
1617
1618                         if (!gc.HasConstructorConstraint)
1619                                 return true;
1620
1621                         if (TypeManager.IsBuiltinType (atype) || atype.IsValueType)
1622                                 return true;
1623
1624                         if (HasDefaultConstructor (ec.DeclContainer.TypeBuilder, atype))
1625                                 return true;
1626
1627                         Report_SymbolRelatedToPreviousError ();
1628                         Report.SymbolRelatedToPreviousError (atype);
1629                         Report.Error (310, loc, "The type `{0}' must have a public " +
1630                                       "parameterless constructor in order to use it " +
1631                                       "as parameter `{1}' in the generic type or " +
1632                                       "method `{2}'",
1633                                       TypeManager.CSharpName (atype),
1634                                       TypeManager.CSharpName (ptype),
1635                                       GetSignatureForError ());
1636                         return false;
1637                 }
1638
1639                 protected bool CheckConstraint (IResolveContext ec, Type ptype, Expression expr,
1640                                                 Type ctype)
1641                 {
1642                         if (TypeManager.HasGenericArguments (ctype)) {
1643                                 Type[] types = TypeManager.GetTypeArguments (ctype);
1644
1645                                 TypeArguments new_args = new TypeArguments (loc);
1646
1647                                 for (int i = 0; i < types.Length; i++) {
1648                                         Type t = types [i];
1649
1650                                         if (t.IsGenericParameter) {
1651                                                 int pos = t.GenericParameterPosition;
1652                                                 t = atypes [pos];
1653                                         }
1654                                         new_args.Add (new TypeExpression (t, loc));
1655                                 }
1656
1657                                 TypeExpr ct = new ConstructedType (ctype, new_args, loc);
1658                                 if (ct.ResolveAsTypeStep (ec, false) == null)
1659                                         return false;
1660                                 ctype = ct.Type;
1661                         } else if (ctype.IsGenericParameter) {
1662                                 int pos = ctype.GenericParameterPosition;
1663                                 ctype = atypes [pos];
1664                         }
1665
1666                         if (Convert.ImplicitStandardConversionExists (expr, ctype))
1667                                 return true;
1668
1669                         Error_TypeMustBeConvertible (expr.Type, ctype, ptype);
1670                         return false;
1671                 }
1672
1673                 bool HasDefaultConstructor (Type containerType, Type atype)
1674                 {
1675                         if (atype.IsAbstract)
1676                                 return false;
1677
1678                 again:
1679                         atype = TypeManager.DropGenericTypeArguments (atype);
1680                         if (atype is TypeBuilder) {
1681                                 TypeContainer tc = TypeManager.LookupTypeContainer (atype);
1682                                 if (tc.InstanceConstructors == null) {
1683                                         atype = atype.BaseType;
1684                                         goto again;
1685                                 }
1686
1687                                 foreach (Constructor c in tc.InstanceConstructors) {
1688                                         if ((c.ModFlags & Modifiers.PUBLIC) == 0)
1689                                                 continue;
1690                                         if ((c.Parameters.FixedParameters != null) &&
1691                                             (c.Parameters.FixedParameters.Length != 0))
1692                                                 continue;
1693                                         if (c.Parameters.HasArglist || c.Parameters.HasParams)
1694                                                 continue;
1695
1696                                         return true;
1697                                 }
1698                         }
1699
1700                         TypeParameter tparam = TypeManager.LookupTypeParameter (atype);
1701                         if (tparam != null)
1702                                 return tparam.HasConstructorConstraint;
1703
1704                         MemberList list = TypeManager.FindMembers (
1705                                 atype, MemberTypes.Constructor,
1706                                 BindingFlags.Public | BindingFlags.Instance |
1707                                 BindingFlags.DeclaredOnly, null, null);
1708
1709                         if (atype.IsAbstract || (list == null))
1710                                 return false;
1711
1712                         foreach (MethodBase mb in list) {
1713                                 ParameterData pd = TypeManager.GetParameterData (mb);
1714                                 if ((pd.Count == 0) && mb.IsPublic && !mb.IsStatic)
1715                                         return true;
1716                         }
1717
1718                         return false;
1719                 }
1720
1721                 protected abstract string GetSignatureForError ();
1722                 protected abstract void Report_SymbolRelatedToPreviousError ();
1723
1724                 void Error_TypeMustBeConvertible (Type atype, Type gc, Type ptype)
1725                 {
1726                         Report_SymbolRelatedToPreviousError ();
1727                         Report.SymbolRelatedToPreviousError (atype);
1728                         Report.Error (309, loc,
1729                                       "The type `{0}' must be convertible to `{1}' in order to " +
1730                                       "use it as parameter `{2}' in the generic type or method `{3}'",
1731                                       TypeManager.CSharpName (atype), TypeManager.CSharpName (gc),
1732                                       TypeManager.CSharpName (ptype), GetSignatureForError ());
1733                 }
1734
1735                 public static bool CheckConstraints (EmitContext ec, MethodBase definition,
1736                                                      MethodBase instantiated, Location loc)
1737                 {
1738                         MethodConstraintChecker checker = new MethodConstraintChecker (
1739                                 definition, definition.GetGenericArguments (),
1740                                 instantiated.GetGenericArguments (), loc);
1741
1742                         return checker.CheckConstraints (ec);
1743                 }
1744
1745                 public static bool CheckConstraints (IResolveContext ec, Type gt, Type[] gen_params,
1746                                                      Type[] atypes, Location loc)
1747                 {
1748                         TypeConstraintChecker checker = new TypeConstraintChecker (
1749                                 gt, gen_params, atypes, loc);
1750
1751                         return checker.CheckConstraints (ec);
1752                 }
1753
1754                 protected class MethodConstraintChecker : ConstraintChecker
1755                 {
1756                         MethodBase definition;
1757
1758                         public MethodConstraintChecker (MethodBase definition, Type[] gen_params,
1759                                                         Type[] atypes, Location loc)
1760                                 : base (gen_params, atypes, loc)
1761                         {
1762                                 this.definition = definition;
1763                         }
1764
1765                         protected override string GetSignatureForError ()
1766                         {
1767                                 return TypeManager.CSharpSignature (definition);
1768                         }
1769
1770                         protected override void Report_SymbolRelatedToPreviousError ()
1771                         {
1772                                 Report.SymbolRelatedToPreviousError (definition);
1773                         }
1774                 }
1775
1776                 protected class TypeConstraintChecker : ConstraintChecker
1777                 {
1778                         Type gt;
1779
1780                         public TypeConstraintChecker (Type gt, Type[] gen_params, Type[] atypes,
1781                                                       Location loc)
1782                                 : base (gen_params, atypes, loc)
1783                         {
1784                                 this.gt = gt;
1785                         }
1786
1787                         protected override string GetSignatureForError ()
1788                         {
1789                                 return TypeManager.CSharpName (gt);
1790                         }
1791
1792                         protected override void Report_SymbolRelatedToPreviousError ()
1793                         {
1794                                 Report.SymbolRelatedToPreviousError (gt);
1795                         }
1796                 }
1797         }
1798
1799         /// <summary>
1800         ///   A generic method definition.
1801         /// </summary>
1802         public class GenericMethod : DeclSpace
1803         {
1804                 Expression return_type;
1805                 Parameters parameters;
1806
1807                 public GenericMethod (NamespaceEntry ns, DeclSpace parent, MemberName name,
1808                                       Expression return_type, Parameters parameters)
1809                         : base (ns, parent, name, null)
1810                 {
1811                         this.return_type = return_type;
1812                         this.parameters = parameters;
1813                 }
1814
1815                 public override TypeBuilder DefineType ()
1816                 {
1817                         throw new Exception ();
1818                 }
1819
1820                 public override bool Define ()
1821                 {
1822                         for (int i = 0; i < TypeParameters.Length; i++)
1823                                 if (!TypeParameters [i].Resolve (this))
1824                                         return false;
1825
1826                         return true;
1827                 }
1828
1829                 /// <summary>
1830                 ///   Define and resolve the type parameters.
1831                 ///   We're called from Method.Define().
1832                 /// </summary>
1833                 public bool Define (MethodBuilder mb, ToplevelBlock block)
1834                 {
1835                         TypeParameterName[] names = MemberName.TypeArguments.GetDeclarations ();
1836                         string[] snames = new string [names.Length];
1837                         for (int i = 0; i < names.Length; i++) {
1838                                 string type_argument_name = names[i].Name;
1839                                 Parameter p = parameters.GetParameterByName (type_argument_name);
1840                                 if (p != null) {
1841                                         Error_ParameterNameCollision (p.Location, type_argument_name, "method parameter");
1842                                         return false;
1843                                 }
1844                                 if (block != null) {
1845                                         LocalInfo li = (LocalInfo)block.Variables[type_argument_name];
1846                                         if (li != null) {
1847                                                 Error_ParameterNameCollision (li.Location, type_argument_name, "local variable");
1848                                                 return false;
1849                                         }
1850                                 }
1851                                 snames[i] = type_argument_name;
1852                         }
1853
1854                         GenericTypeParameterBuilder[] gen_params = mb.DefineGenericParameters (snames);
1855                         for (int i = 0; i < TypeParameters.Length; i++)
1856                                 TypeParameters [i].Define (gen_params [i]);
1857
1858                         if (!Define ())
1859                                 return false;
1860
1861                         for (int i = 0; i < TypeParameters.Length; i++) {
1862                                 if (!TypeParameters [i].ResolveType (this))
1863                                         return false;
1864                         }
1865
1866                         return true;
1867                 }
1868
1869                 static void Error_ParameterNameCollision (Location loc, string name, string collisionWith)
1870                 {
1871                         Report.Error (412, loc, "The type parameter name `{0}' is the same as `{1}'",
1872                                 name, collisionWith);
1873                 }
1874
1875                 /// <summary>
1876                 ///   We're called from MethodData.Define() after creating the MethodBuilder.
1877                 /// </summary>
1878                 public bool DefineType (EmitContext ec, MethodBuilder mb,
1879                                         MethodInfo implementing, bool is_override)
1880                 {
1881                         for (int i = 0; i < TypeParameters.Length; i++)
1882                                 if (!TypeParameters [i].DefineType (
1883                                             ec, mb, implementing, is_override))
1884                                         return false;
1885
1886                         bool ok = true;
1887                         foreach (Parameter p in parameters.FixedParameters){
1888                                 if (!p.Resolve (ec))
1889                                         ok = false;
1890                         }
1891                         if ((return_type != null) && (return_type.ResolveAsTypeTerminal (ec, false) == null))
1892                                 ok = false;
1893
1894                         return ok;
1895                 }
1896
1897                 public void EmitAttributes ()
1898                 {
1899                         for (int i = 0; i < TypeParameters.Length; i++)
1900                                 TypeParameters [i].EmitAttributes ();
1901
1902                         if (OptAttributes != null)
1903                                 OptAttributes.Emit ();
1904                 }
1905
1906                 public override bool DefineMembers ()
1907                 {
1908                         return true;
1909                 }
1910
1911                 public override MemberList FindMembers (MemberTypes mt, BindingFlags bf,
1912                                                         MemberFilter filter, object criteria)
1913                 {
1914                         throw new Exception ();
1915                 }
1916
1917                 public override MemberCache MemberCache {
1918                         get {
1919                                 return null;
1920                         }
1921                 }
1922
1923                 public override AttributeTargets AttributeTargets {
1924                         get {
1925                                 return AttributeTargets.Method | AttributeTargets.ReturnValue;
1926                         }
1927                 }
1928
1929                 public override string DocCommentHeader {
1930                         get { return "M:"; }
1931                 }
1932
1933                 public new void VerifyClsCompliance ()
1934                 {
1935                         foreach (TypeParameter tp in TypeParameters) {
1936                                 if (tp.Constraints == null)
1937                                         continue;
1938
1939                                 tp.Constraints.VerifyClsCompliance ();
1940                         }
1941                 }
1942         }
1943
1944         public class DefaultValueExpression : Expression
1945         {
1946                 Expression expr;
1947
1948                 public DefaultValueExpression (Expression expr, Location loc)
1949                 {
1950                         this.expr = expr;
1951                         this.loc = loc;
1952                 }
1953
1954                 public override Expression DoResolve (EmitContext ec)
1955                 {
1956                         TypeExpr texpr = expr.ResolveAsTypeTerminal (ec, false);
1957                         if (texpr == null)
1958                                 return null;
1959
1960                         type = texpr.Type;
1961
1962                         if (type == TypeManager.void_type) {
1963                                 Error_VoidInvalidInTheContext (loc);
1964                                 return null;
1965                         }
1966
1967                         if (type.IsGenericParameter)
1968                         {
1969                                 GenericConstraints constraints = TypeManager.GetTypeParameterConstraints(type);
1970                                 if (constraints != null && constraints.IsReferenceType)
1971                                         return new NullDefault (new NullLiteral (Location), type);
1972                         }
1973                         else
1974                         {
1975                                 Constant c = New.Constantify(type);
1976                                 if (c != null)
1977                                         return new NullDefault (c, type);
1978
1979                                 if (!TypeManager.IsValueType (type))
1980                                         return new NullDefault (new NullLiteral (Location), type);
1981                         }
1982                         eclass = ExprClass.Variable;
1983                         return this;
1984                 }
1985
1986                 public override void Emit (EmitContext ec)
1987                 {
1988                         LocalTemporary temp_storage = new LocalTemporary(type);
1989
1990                         temp_storage.AddressOf(ec, AddressOp.LoadStore);
1991                         ec.ig.Emit(OpCodes.Initobj, type);
1992                         temp_storage.Emit(ec);
1993                 }
1994         }
1995
1996         public class NullableType : TypeExpr
1997         {
1998                 Expression underlying;
1999
2000                 public NullableType (Expression underlying, Location l)
2001                 {
2002                         this.underlying = underlying;
2003                         loc = l;
2004
2005                         eclass = ExprClass.Type;
2006                 }
2007
2008                 public NullableType (Type type, Location loc)
2009                         : this (new TypeExpression (type, loc), loc)
2010                 { }
2011
2012                 public override string Name {
2013                         get { return underlying.ToString () + "?"; }
2014                 }
2015
2016                 public override string FullName {
2017                         get { return underlying.ToString () + "?"; }
2018                 }
2019
2020                 protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
2021                 {
2022                         TypeArguments args = new TypeArguments (loc);
2023                         args.Add (underlying);
2024
2025                         ConstructedType ctype = new ConstructedType (TypeManager.generic_nullable_type, args, loc);
2026                         return ctype.ResolveAsTypeTerminal (ec, false);
2027                 }
2028         }
2029
2030         public partial class TypeManager
2031         {
2032                 //
2033                 // A list of core types that the compiler requires or uses
2034                 //
2035                 static public Type activator_type;
2036                 static public Type generic_ilist_type;
2037                 static public Type generic_icollection_type;
2038                 static public Type generic_ienumerator_type;
2039                 static public Type generic_ienumerable_type;
2040                 static public Type generic_nullable_type;
2041
2042                 //
2043                 // These methods are called by code generated by the compiler
2044                 //
2045                 static public MethodInfo activator_create_instance;
2046
2047                 static void InitGenericCoreTypes ()
2048                 {
2049                         activator_type = CoreLookupType ("System", "Activator");
2050
2051                         generic_ilist_type = CoreLookupType (
2052                                 "System.Collections.Generic", "IList", 1);
2053                         generic_icollection_type = CoreLookupType (
2054                                 "System.Collections.Generic", "ICollection", 1);
2055                         generic_ienumerator_type = CoreLookupType (
2056                                 "System.Collections.Generic", "IEnumerator", 1);
2057                         generic_ienumerable_type = CoreLookupType (
2058                                 "System.Collections.Generic", "IEnumerable", 1);
2059                         generic_nullable_type = CoreLookupType (
2060                                 "System", "Nullable", 1);
2061                 }
2062
2063                 static void InitGenericCodeHelpers ()
2064                 {
2065                         // Activator
2066                         Type [] type_arg = { type_type };
2067                         activator_create_instance = GetMethod (
2068                                 activator_type, "CreateInstance", type_arg);
2069                 }
2070
2071                 static Type CoreLookupType (string ns, string name, int arity)
2072                 {
2073                         return CoreLookupType (ns, MemberName.MakeName (name, arity));
2074                 }
2075
2076                 public static TypeContainer LookupGenericTypeContainer (Type t)
2077                 {
2078                         t = DropGenericTypeArguments (t);
2079                         return LookupTypeContainer (t);
2080                 }
2081
2082                 public static GenericConstraints GetTypeParameterConstraints (Type t)
2083                 {
2084                         if (!t.IsGenericParameter)
2085                                 throw new InvalidOperationException ();
2086
2087                         TypeParameter tparam = LookupTypeParameter (t);
2088                         if (tparam != null)
2089                                 return tparam.GenericConstraints;
2090
2091                         return ReflectionConstraints.GetConstraints (t);
2092                 }
2093
2094                 /// <summary>
2095                 ///   Check whether `a' and `b' may become equal generic types.
2096                 ///   The algorithm to do that is a little bit complicated.
2097                 /// </summary>
2098                 public static bool MayBecomeEqualGenericTypes (Type a, Type b, Type[] class_inferred,
2099                                                                Type[] method_inferred)
2100                 {
2101                         if (a.IsGenericParameter) {
2102                                 //
2103                                 // If a is an array of a's type, they may never
2104                                 // become equal.
2105                                 //
2106                                 while (b.IsArray) {
2107                                         b = b.GetElementType ();
2108                                         if (a.Equals (b))
2109                                                 return false;
2110                                 }
2111
2112                                 //
2113                                 // If b is a generic parameter or an actual type,
2114                                 // they may become equal:
2115                                 //
2116                                 //    class X<T,U> : I<T>, I<U>
2117                                 //    class X<T> : I<T>, I<float>
2118                                 //
2119                                 if (b.IsGenericParameter || !b.IsGenericType) {
2120                                         int pos = a.GenericParameterPosition;
2121                                         Type[] args = a.DeclaringMethod != null ? method_inferred : class_inferred;
2122                                         if (args [pos] == null) {
2123                                                 args [pos] = b;
2124                                                 return true;
2125                                         }
2126
2127                                         return args [pos] == a;
2128                                 }
2129
2130                                 //
2131                                 // We're now comparing a type parameter with a
2132                                 // generic instance.  They may become equal unless
2133                                 // the type parameter appears anywhere in the
2134                                 // generic instance:
2135                                 //
2136                                 //    class X<T,U> : I<T>, I<X<U>>
2137                                 //        -> error because you could instanciate it as
2138                                 //           X<X<int>,int>
2139                                 //
2140                                 //    class X<T> : I<T>, I<X<T>> -> ok
2141                                 //
2142
2143                                 Type[] bargs = GetTypeArguments (b);
2144                                 for (int i = 0; i < bargs.Length; i++) {
2145                                         if (a.Equals (bargs [i]))
2146                                                 return false;
2147                                 }
2148
2149                                 return true;
2150                         }
2151
2152                         if (b.IsGenericParameter)
2153                                 return MayBecomeEqualGenericTypes (b, a, class_inferred, method_inferred);
2154
2155                         //
2156                         // At this point, neither a nor b are a type parameter.
2157                         //
2158                         // If one of them is a generic instance, let
2159                         // MayBecomeEqualGenericInstances() compare them (if the
2160                         // other one is not a generic instance, they can never
2161                         // become equal).
2162                         //
2163
2164                         if (a.IsGenericType || b.IsGenericType)
2165                                 return MayBecomeEqualGenericInstances (a, b, class_inferred, method_inferred);
2166
2167                         //
2168                         // If both of them are arrays.
2169                         //
2170
2171                         if (a.IsArray && b.IsArray) {
2172                                 if (a.GetArrayRank () != b.GetArrayRank ())
2173                                         return false;
2174
2175                                 a = a.GetElementType ();
2176                                 b = b.GetElementType ();
2177
2178                                 return MayBecomeEqualGenericTypes (a, b, class_inferred, method_inferred);
2179                         }
2180
2181                         //
2182                         // Ok, two ordinary types.
2183                         //
2184
2185                         return a.Equals (b);
2186                 }
2187
2188                 //
2189                 // Checks whether two generic instances may become equal for some
2190                 // particular instantiation (26.3.1).
2191                 //
2192                 public static bool MayBecomeEqualGenericInstances (Type a, Type b,
2193                                                                    Type[] class_inferred,
2194                                                                    Type[] method_inferred)
2195                 {
2196                         if (!a.IsGenericType || !b.IsGenericType)
2197                                 return false;
2198                         if (a.GetGenericTypeDefinition () != b.GetGenericTypeDefinition ())
2199                                 return false;
2200
2201                         return MayBecomeEqualGenericInstances (
2202                                 GetTypeArguments (a), GetTypeArguments (b), class_inferred, method_inferred);
2203                 }
2204
2205                 public static bool MayBecomeEqualGenericInstances (Type[] aargs, Type[] bargs,
2206                                                                    Type[] class_inferred,
2207                                                                    Type[] method_inferred)
2208                 {
2209                         if (aargs.Length != bargs.Length)
2210                                 return false;
2211
2212                         for (int i = 0; i < aargs.Length; i++) {
2213                                 if (!MayBecomeEqualGenericTypes (aargs [i], bargs [i], class_inferred, method_inferred))
2214                                         return false;
2215                         }
2216
2217                         return true;
2218                 }
2219
2220                 //
2221                 // Type inference.
2222                 //
2223
2224                 static bool InferType (Type pt, Type at, Type[] inferred)
2225                 {
2226                         if (pt.IsGenericParameter) {
2227                                 if (pt.DeclaringMethod == null)
2228                                         return pt == at;
2229
2230                                 int pos = pt.GenericParameterPosition;
2231
2232                                 if (inferred [pos] == null) {
2233                                         inferred [pos] = at;
2234                                         return true;
2235                                 }
2236
2237                                 if (inferred [pos] != at)
2238                                         return false;
2239
2240                                 return true;
2241                         }
2242
2243                         if (!pt.ContainsGenericParameters) {
2244                                 if (at.ContainsGenericParameters)
2245                                         return InferType (at, pt, inferred);
2246                                 else
2247                                         return true;
2248                         }
2249
2250                         if (at.IsArray) {
2251                                 if (pt.IsArray) {
2252                                         if (at.GetArrayRank () != pt.GetArrayRank ())
2253                                                 return false;
2254
2255                                         return InferType (pt.GetElementType (), at.GetElementType (), inferred);
2256                                 }
2257
2258                                 if (!pt.IsGenericType)
2259                                         return false;
2260
2261                                 Type gt = pt.GetGenericTypeDefinition ();
2262                                 if ((gt != generic_ilist_type) && (gt != generic_icollection_type) &&
2263                                     (gt != generic_ienumerable_type))
2264                                         return false;
2265
2266                                 Type[] args = GetTypeArguments (pt);
2267                                 return InferType (args [0], at.GetElementType (), inferred);
2268                         }
2269
2270                         if (pt.IsArray) {
2271                                 if (!at.IsArray ||
2272                                     (pt.GetArrayRank () != at.GetArrayRank ()))
2273                                         return false;
2274
2275                                 return InferType (pt.GetElementType (), at.GetElementType (), inferred);
2276                         }
2277
2278                         if (pt.IsByRef && at.IsByRef)
2279                                 return InferType (pt.GetElementType (), at.GetElementType (), inferred);
2280                         ArrayList list = new ArrayList ();
2281                         if (at.IsGenericType)
2282                                 list.Add (at);
2283                         for (Type bt = at.BaseType; bt != null; bt = bt.BaseType)
2284                                 list.Add (bt);
2285
2286                         list.AddRange (TypeManager.GetInterfaces (at));
2287
2288                         bool found_one = false;
2289
2290                         foreach (Type type in list) {
2291                                 if (!type.IsGenericType)
2292                                         continue;
2293
2294                                 Type[] inferred_types = new Type [inferred.Length];
2295
2296                                 if (!InferGenericInstance (pt, type, inferred_types))
2297                                         continue;
2298
2299                                 for (int i = 0; i < inferred_types.Length; i++) {
2300                                         if (inferred [i] == null) {
2301                                                 inferred [i] = inferred_types [i];
2302                                                 continue;
2303                                         }
2304
2305                                         if (inferred [i] != inferred_types [i])
2306                                                 return false;
2307                                 }
2308
2309                                 found_one = true;
2310                         }
2311
2312                         return found_one;
2313                 }
2314
2315                 static bool InferGenericInstance (Type pt, Type at, Type[] inferred_types)
2316                 {
2317                         Type[] at_args = at.GetGenericArguments ();
2318                         Type[] pt_args = pt.GetGenericArguments ();
2319
2320                         if (at_args.Length != pt_args.Length)
2321                                 return false;
2322
2323                         for (int i = 0; i < at_args.Length; i++) {
2324                                 if (!InferType (pt_args [i], at_args [i], inferred_types))
2325                                         return false;
2326                         }
2327
2328                         for (int i = 0; i < inferred_types.Length; i++) {
2329                                 if (inferred_types [i] == null)
2330                                         return false;
2331                         }
2332
2333                         return true;
2334                 }
2335
2336                 /// <summary>
2337                 ///   Type inference.  Try to infer the type arguments from the params method
2338                 ///   `method', which is invoked with the arguments `arguments'.  This is used
2339                 ///   when resolving an Invocation or a DelegateInvocation and the user
2340                 ///   did not explicitly specify type arguments.
2341                 /// </summary>
2342                 public static bool InferParamsTypeArguments (EmitContext ec, ArrayList arguments,
2343                                                              ref MethodBase method)
2344                 {
2345                         if (!TypeManager.IsGenericMethod (method))
2346                                 return true;
2347
2348                         // if there are no arguments, there's no way to infer the type-arguments
2349                         if (arguments == null || arguments.Count == 0)
2350                                 return false;
2351
2352                         ParameterData pd = TypeManager.GetParameterData (method);
2353                         int pd_count = pd.Count;
2354                         int arg_count = arguments.Count;
2355
2356                         if (pd_count == 0)
2357                                 return false;
2358
2359                         if (pd.ParameterModifier (pd_count - 1) != Parameter.Modifier.PARAMS)
2360                                 return false;
2361
2362                         if (pd_count - 1 > arg_count)
2363                                 return false;
2364
2365                         Type[] method_args = method.GetGenericArguments ();
2366                         Type[] inferred_types = new Type [method_args.Length];
2367
2368                         //
2369                         // If we have come this far, the case which
2370                         // remains is when the number of parameters is
2371                         // less than or equal to the argument count.
2372                         //
2373                         for (int i = 0; i < pd_count - 1; ++i) {
2374                                 Argument a = (Argument) arguments [i];
2375
2376                                 if ((a.Expr is NullLiteral) || (a.Expr is MethodGroupExpr))
2377                                         continue;
2378
2379                                 Type pt = pd.ParameterType (i);
2380                                 Type at = a.Type;
2381
2382                                 if (!InferType (pt, at, inferred_types))
2383                                         return false;
2384                         }
2385
2386                         Type element_type = TypeManager.GetElementType (pd.ParameterType (pd_count - 1));
2387
2388                         for (int i = pd_count - 1; i < arg_count; i++) {
2389                                 Argument a = (Argument) arguments [i];
2390
2391                                 if ((a.Expr is NullLiteral) || (a.Expr is MethodGroupExpr))
2392                                         continue;
2393
2394                                 if (!InferType (element_type, a.Type, inferred_types))
2395                                         return false;
2396                         }
2397
2398                         for (int i = 0; i < inferred_types.Length; i++)
2399                                 if (inferred_types [i] == null)
2400                                         return false;
2401
2402                         method = ((MethodInfo)method).MakeGenericMethod (inferred_types);
2403                         return true;
2404                 }
2405
2406                 static bool InferTypeArguments (Type[] param_types, Type[] arg_types,
2407                                                 Type[] inferred_types)
2408                 {
2409                         if (inferred_types == null)
2410                                 return false;
2411
2412                         for (int i = 0; i < arg_types.Length; i++) {
2413                                 if (arg_types [i] == null)
2414                                         continue;
2415
2416                                 if (!InferType (param_types [i], arg_types [i], inferred_types))
2417                                         return false;
2418                         }
2419
2420                         for (int i = 0; i < inferred_types.Length; i++)
2421                                 if (inferred_types [i] == null)
2422                                         return false;
2423
2424                         return true;
2425                 }
2426
2427                 /// <summary>
2428                 ///   Type inference.  Try to infer the type arguments from `method',
2429                 ///   which is invoked with the arguments `arguments'.  This is used
2430                 ///   when resolving an Invocation or a DelegateInvocation and the user
2431                 ///   did not explicitly specify type arguments.
2432                 /// </summary>
2433                 public static bool InferTypeArguments (ArrayList arguments,
2434                                                        ref MethodBase method)
2435                 {
2436                         if (!TypeManager.IsGenericMethod (method))
2437                                 return true;
2438
2439                         int arg_count;
2440                         if (arguments != null)
2441                                 arg_count = arguments.Count;
2442                         else
2443                                 arg_count = 0;
2444
2445                         ParameterData pd = TypeManager.GetParameterData (method);
2446                         if (arg_count != pd.Count)
2447                                 return false;
2448
2449                         Type[] method_args = method.GetGenericArguments ();
2450
2451                         bool is_open = false;
2452                         for (int i = 0; i < method_args.Length; i++) {
2453                                 if (method_args [i].IsGenericParameter) {
2454                                         is_open = true;
2455                                         break;
2456                                 }
2457                         }
2458
2459                         // If none of the method parameters mention a generic parameter, we can't infer the generic parameters
2460                         if (!is_open)
2461                                 return !TypeManager.IsGenericMethodDefinition (method);
2462
2463                         Type[] inferred_types = new Type [method_args.Length];
2464
2465                         Type[] param_types = new Type [pd.Count];
2466                         Type[] arg_types = new Type [pd.Count];
2467
2468                         for (int i = 0; i < arg_count; i++) {
2469                                 param_types [i] = pd.ParameterType (i);
2470
2471                                 Argument a = (Argument) arguments [i];
2472                                 if ((a.Expr is NullLiteral) || (a.Expr is MethodGroupExpr) ||
2473                                     (a.Expr is AnonymousMethodExpression))
2474                                         continue;
2475
2476                                 arg_types [i] = a.Type;
2477                         }
2478
2479                         if (!InferTypeArguments (param_types, arg_types, inferred_types))
2480                                 return false;
2481
2482                         method = ((MethodInfo)method).MakeGenericMethod (inferred_types);
2483                         return true;
2484                 }
2485
2486                 /// <summary>
2487                 ///   Type inference.
2488                 /// </summary>
2489                 public static bool InferTypeArguments (ParameterData apd,
2490                                                        ref MethodBase method)
2491                 {
2492                         if (!TypeManager.IsGenericMethod (method))
2493                                 return true;
2494
2495                         ParameterData pd = TypeManager.GetParameterData (method);
2496                         if (apd.Count != pd.Count)
2497                                 return false;
2498
2499                         Type[] method_args = method.GetGenericArguments ();
2500                         Type[] inferred_types = new Type [method_args.Length];
2501
2502                         Type[] param_types = new Type [pd.Count];
2503                         Type[] arg_types = new Type [pd.Count];
2504
2505                         for (int i = 0; i < apd.Count; i++) {
2506                                 param_types [i] = pd.ParameterType (i);
2507                                 arg_types [i] = apd.ParameterType (i);
2508                         }
2509
2510                         if (!InferTypeArguments (param_types, arg_types, inferred_types))
2511                                 return false;
2512
2513                         method = ((MethodInfo)method).MakeGenericMethod (inferred_types);
2514                         return true;
2515                 }
2516         }
2517
2518         public abstract class Nullable
2519         {
2520                 public sealed class NullableInfo
2521                 {
2522                         public readonly Type Type;
2523                         public readonly Type UnderlyingType;
2524                         public readonly MethodInfo HasValue;
2525                         public readonly MethodInfo Value;
2526                         public readonly ConstructorInfo Constructor;
2527
2528                         public NullableInfo (Type type)
2529                         {
2530                                 Type = type;
2531                                 UnderlyingType = TypeManager.GetTypeArguments (type) [0];
2532
2533                                 PropertyInfo has_value_pi = TypeManager.GetProperty (type, "HasValue");
2534                                 PropertyInfo value_pi = TypeManager.GetProperty (type, "Value");
2535
2536                                 HasValue = has_value_pi.GetGetMethod (false);
2537                                 Value = value_pi.GetGetMethod (false);
2538                                 Constructor = type.GetConstructor (new Type[] { UnderlyingType });
2539                         }
2540                 }
2541
2542                 public class Unwrap : Expression, IMemoryLocation, IAssignMethod
2543                 {
2544                         Expression expr;
2545                         NullableInfo info;
2546
2547                         LocalTemporary temp;
2548                         bool has_temp;
2549
2550                         protected Unwrap (Expression expr)
2551                         {
2552                                 this.expr = expr;
2553                                 this.loc = expr.Location;
2554                         }
2555
2556                         public static Unwrap Create (Expression expr, EmitContext ec)
2557                         {
2558                                 return new Unwrap (expr).Resolve (ec) as Unwrap;
2559                         }
2560
2561                         public override Expression DoResolve (EmitContext ec)
2562                         {
2563                                 expr = expr.Resolve (ec);
2564                                 if (expr == null)
2565                                         return null;
2566
2567                                 temp = new LocalTemporary (expr.Type);
2568
2569                                 info = new NullableInfo (expr.Type);
2570                                 type = info.UnderlyingType;
2571                                 eclass = expr.eclass;
2572                                 return this;
2573                         }
2574
2575                         public override void Emit (EmitContext ec)
2576                         {
2577                                 AddressOf (ec, AddressOp.LoadStore);
2578                                 ec.ig.EmitCall (OpCodes.Call, info.Value, null);
2579                         }
2580
2581                         public void EmitCheck (EmitContext ec)
2582                         {
2583                                 AddressOf (ec, AddressOp.LoadStore);
2584                                 ec.ig.EmitCall (OpCodes.Call, info.HasValue, null);
2585                         }
2586
2587                         public void Store (EmitContext ec)
2588                         {
2589                                 create_temp (ec);
2590                         }
2591
2592                         void create_temp (EmitContext ec)
2593                         {
2594                                 if ((temp != null) && !has_temp) {
2595                                         expr.Emit (ec);
2596                                         temp.Store (ec);
2597                                         has_temp = true;
2598                                 }
2599                         }
2600
2601                         public void AddressOf (EmitContext ec, AddressOp mode)
2602                         {
2603                                 create_temp (ec);
2604                                 if (temp != null)
2605                                         temp.AddressOf (ec, AddressOp.LoadStore);
2606                                 else
2607                                         ((IMemoryLocation) expr).AddressOf (ec, AddressOp.LoadStore);
2608                         }
2609
2610                         public void Emit (EmitContext ec, bool leave_copy)
2611                         {
2612                                 create_temp (ec);
2613                                 if (leave_copy) {
2614                                         if (temp != null)
2615                                                 temp.Emit (ec);
2616                                         else
2617                                                 expr.Emit (ec);
2618                                 }
2619
2620                                 Emit (ec);
2621                         }
2622
2623                         public void EmitAssign (EmitContext ec, Expression source,
2624                                                 bool leave_copy, bool prepare_for_load)
2625                         {
2626                                 InternalWrap wrap = new InternalWrap (source, info, loc);
2627                                 ((IAssignMethod) expr).EmitAssign (ec, wrap, leave_copy, false);
2628                         }
2629
2630                         protected class InternalWrap : Expression
2631                         {
2632                                 public Expression expr;
2633                                 public NullableInfo info;
2634
2635                                 public InternalWrap (Expression expr, NullableInfo info, Location loc)
2636                                 {
2637                                         this.expr = expr;
2638                                         this.info = info;
2639                                         this.loc = loc;
2640
2641                                         type = info.Type;
2642                                         eclass = ExprClass.Value;
2643                                 }
2644
2645                                 public override Expression DoResolve (EmitContext ec)
2646                                 {
2647                                         return this;
2648                                 }
2649
2650                                 public override void Emit (EmitContext ec)
2651                                 {
2652                                         expr.Emit (ec);
2653                                         ec.ig.Emit (OpCodes.Newobj, info.Constructor);
2654                                 }
2655                         }
2656                 }
2657
2658                 public class Wrap : Expression
2659                 {
2660                         Expression expr;
2661                         NullableInfo info;
2662
2663                         protected Wrap (Expression expr)
2664                         {
2665                                 this.expr = expr;
2666                                 this.loc = expr.Location;
2667                         }
2668
2669                         public static Wrap Create (Expression expr, EmitContext ec)
2670                         {
2671                                 return new Wrap (expr).Resolve (ec) as Wrap;
2672                         }
2673
2674                         public override Expression DoResolve (EmitContext ec)
2675                         {
2676                                 expr = expr.Resolve (ec);
2677                                 if (expr == null)
2678                                         return null;
2679
2680                                 TypeExpr target_type = new NullableType (expr.Type, loc);
2681                                 target_type = target_type.ResolveAsTypeTerminal (ec, false);
2682                                 if (target_type == null)
2683                                         return null;
2684
2685                                 type = target_type.Type;
2686                                 info = new NullableInfo (type);
2687                                 eclass = ExprClass.Value;
2688                                 return this;
2689                         }
2690
2691                         public override void Emit (EmitContext ec)
2692                         {
2693                                 expr.Emit (ec);
2694                                 ec.ig.Emit (OpCodes.Newobj, info.Constructor);
2695                         }
2696                 }
2697
2698                 public class NullableLiteral : NullLiteral, IMemoryLocation {
2699                         public NullableLiteral (Type target_type, Location loc)
2700                                 : base (loc)
2701                         {
2702                                 this.type = target_type;
2703
2704                                 eclass = ExprClass.Value;
2705                         }
2706
2707                         public override Expression DoResolve (EmitContext ec)
2708                         {
2709                                 return this;
2710                         }
2711
2712                         public override void Emit (EmitContext ec)
2713                         {
2714                                 LocalTemporary value_target = new LocalTemporary (type);
2715
2716                                 value_target.AddressOf (ec, AddressOp.Store);
2717                                 ec.ig.Emit (OpCodes.Initobj, type);
2718                                 value_target.Emit (ec);
2719                         }
2720
2721                         public void AddressOf (EmitContext ec, AddressOp Mode)
2722                         {
2723                                 LocalTemporary value_target = new LocalTemporary (type);
2724
2725                                 value_target.AddressOf (ec, AddressOp.Store);
2726                                 ec.ig.Emit (OpCodes.Initobj, type);
2727                                 ((IMemoryLocation) value_target).AddressOf (ec, Mode);
2728                         }
2729                 }
2730
2731                 public abstract class Lifted : Expression, IMemoryLocation
2732                 {
2733                         Expression expr, underlying, wrap, null_value;
2734                         Unwrap unwrap;
2735
2736                         protected Lifted (Expression expr, Location loc)
2737                         {
2738                                 this.expr = expr;
2739                                 this.loc = loc;
2740                         }
2741
2742                         public override Expression DoResolve (EmitContext ec)
2743                         {
2744                                 expr = expr.Resolve (ec);
2745                                 if (expr == null)
2746                                         return null;
2747
2748                                 unwrap = Unwrap.Create (expr, ec);
2749                                 if (unwrap == null)
2750                                         return null;
2751
2752                                 underlying = ResolveUnderlying (unwrap, ec);
2753                                 if (underlying == null)
2754                                         return null;
2755
2756                                 wrap = Wrap.Create (underlying, ec);
2757                                 if (wrap == null)
2758                                         return null;
2759
2760                                 null_value = new NullableLiteral (wrap.Type, loc).Resolve (ec);
2761                                 if (null_value == null)
2762                                         return null;
2763
2764                                 type = wrap.Type;
2765                                 eclass = ExprClass.Value;
2766                                 return this;
2767                         }
2768
2769                         protected abstract Expression ResolveUnderlying (Expression unwrap, EmitContext ec);
2770
2771                         public override void Emit (EmitContext ec)
2772                         {
2773                                 ILGenerator ig = ec.ig;
2774                                 Label is_null_label = ig.DefineLabel ();
2775                                 Label end_label = ig.DefineLabel ();
2776
2777                                 unwrap.EmitCheck (ec);
2778                                 ig.Emit (OpCodes.Brfalse, is_null_label);
2779
2780                                 wrap.Emit (ec);
2781                                 ig.Emit (OpCodes.Br, end_label);
2782
2783                                 ig.MarkLabel (is_null_label);
2784                                 null_value.Emit (ec);
2785
2786                                 ig.MarkLabel (end_label);
2787                         }
2788
2789                         public void AddressOf (EmitContext ec, AddressOp mode)
2790                         {
2791                                 unwrap.AddressOf (ec, mode);
2792                         }
2793                 }
2794
2795                 public class LiftedConversion : Lifted
2796                 {
2797                         public readonly bool IsUser;
2798                         public readonly bool IsExplicit;
2799                         public readonly Type TargetType;
2800
2801                         public LiftedConversion (Expression expr, Type target_type, bool is_user,
2802                                                  bool is_explicit, Location loc)
2803                                 : base (expr, loc)
2804                         {
2805                                 this.IsUser = is_user;
2806                                 this.IsExplicit = is_explicit;
2807                                 this.TargetType = target_type;
2808                         }
2809
2810                         protected override Expression ResolveUnderlying (Expression unwrap, EmitContext ec)
2811                         {
2812                                 Type type = TypeManager.GetTypeArguments (TargetType) [0];
2813
2814                                 if (IsUser) {
2815                                         return Convert.UserDefinedConversion (ec, unwrap, type, loc, IsExplicit);
2816                                 } else {
2817                                         if (IsExplicit)
2818                                                 return Convert.ExplicitConversion (ec, unwrap, type, loc);
2819                                         else
2820                                                 return Convert.ImplicitConversion (ec, unwrap, type, loc);
2821                                 }
2822                         }
2823                 }
2824
2825                 public class LiftedUnaryOperator : Lifted
2826                 {
2827                         public readonly Unary.Operator Oper;
2828
2829                         public LiftedUnaryOperator (Unary.Operator op, Expression expr, Location loc)
2830                                 : base (expr, loc)
2831                         {
2832                                 this.Oper = op;
2833                         }
2834
2835                         protected override Expression ResolveUnderlying (Expression unwrap, EmitContext ec)
2836                         {
2837                                 return new Unary (Oper, unwrap, loc);
2838                         }
2839                 }
2840
2841                 public class LiftedConditional : Lifted
2842                 {
2843                         Expression true_expr, false_expr;
2844
2845                         public LiftedConditional (Expression expr, Expression true_expr, Expression false_expr,
2846                                                   Location loc)
2847                                 : base (expr, loc)
2848                         {
2849                                 this.true_expr = true_expr;
2850                                 this.false_expr = false_expr;
2851                         }
2852
2853                         protected override Expression ResolveUnderlying (Expression unwrap, EmitContext ec)
2854                         {
2855                                 return new Conditional (unwrap, true_expr, false_expr);
2856                         }
2857                 }
2858
2859                 public class LiftedBinaryOperator : Expression
2860                 {
2861                         public readonly Binary.Operator Oper;
2862
2863                         Expression left, right, original_left, original_right;
2864                         Expression underlying, null_value, bool_wrap;
2865                         Unwrap left_unwrap, right_unwrap;
2866                         bool is_equality, is_comparision, is_boolean;
2867
2868                         public LiftedBinaryOperator (Binary.Operator op, Expression left, Expression right,
2869                                                      Location loc)
2870                         {
2871                                 this.Oper = op;
2872                                 this.left = original_left = left;
2873                                 this.right = original_right = right;
2874                                 this.loc = loc;
2875                         }
2876
2877                         public override Expression DoResolve (EmitContext ec)
2878                         {
2879                                 if (TypeManager.IsNullableType (left.Type)) {
2880                                         left = left_unwrap = Unwrap.Create (left, ec);
2881                                         if (left == null)
2882                                                 return null;
2883                                 }
2884
2885                                 if (TypeManager.IsNullableType (right.Type)) {
2886                                         right = right_unwrap = Unwrap.Create (right, ec);
2887                                         if (right == null)
2888                                                 return null;
2889                                 }
2890
2891                                 if ((Oper == Binary.Operator.LogicalAnd) ||
2892                                     (Oper == Binary.Operator.LogicalOr)) {
2893                                         Binary.Error_OperatorCannotBeApplied (
2894                                                 loc, Binary.OperName (Oper),
2895                                                 original_left.GetSignatureForError (),
2896                                                 original_right.GetSignatureForError ());
2897                                         return null;
2898                                 }
2899
2900                                 if (((Oper == Binary.Operator.BitwiseAnd) || (Oper == Binary.Operator.BitwiseOr)) &&
2901                                     ((left.Type == TypeManager.bool_type) && (right.Type == TypeManager.bool_type))) {
2902                                         Expression empty = new EmptyExpression (TypeManager.bool_type);
2903                                         bool_wrap = Wrap.Create (empty, ec);
2904                                         null_value = new NullableLiteral (bool_wrap.Type, loc).Resolve (ec);
2905
2906                                         type = bool_wrap.Type;
2907                                         is_boolean = true;
2908                                 } else if ((Oper == Binary.Operator.Equality) || (Oper == Binary.Operator.Inequality)) {
2909                                         if (!(left is NullLiteral) && !(right is NullLiteral)) {
2910                                                 underlying = new Binary (Oper, left, right).Resolve (ec);
2911                                                 if (underlying == null)
2912                                                         return null;
2913                                         }
2914
2915                                         type = TypeManager.bool_type;
2916                                         is_equality = true;
2917                                 } else if ((Oper == Binary.Operator.LessThan) ||
2918                                            (Oper == Binary.Operator.GreaterThan) ||
2919                                            (Oper == Binary.Operator.LessThanOrEqual) ||
2920                                            (Oper == Binary.Operator.GreaterThanOrEqual)) {
2921                                         underlying = new Binary (Oper, left, right).Resolve (ec);
2922                                         if (underlying == null)
2923                                                 return null;
2924
2925                                         type = TypeManager.bool_type;
2926                                         is_comparision = true;
2927                                 } else {
2928                                         underlying = new Binary (Oper, left, right).Resolve (ec);
2929                                         if (underlying == null)
2930                                                 return null;
2931
2932                                         underlying = Wrap.Create (underlying, ec);
2933                                         if (underlying == null)
2934                                                 return null;
2935
2936                                         type = underlying.Type;
2937                                         null_value = new NullableLiteral (type, loc).Resolve (ec);
2938                                 }
2939
2940                                 eclass = ExprClass.Value;
2941                                 return this;
2942                         }
2943
2944                         void EmitBoolean (EmitContext ec)
2945                         {
2946                                 ILGenerator ig = ec.ig;
2947
2948                                 Label left_is_null_label = ig.DefineLabel ();
2949                                 Label right_is_null_label = ig.DefineLabel ();
2950                                 Label is_null_label = ig.DefineLabel ();
2951                                 Label wrap_label = ig.DefineLabel ();
2952                                 Label end_label = ig.DefineLabel ();
2953
2954                                 if (left_unwrap != null) {
2955                                         left_unwrap.EmitCheck (ec);
2956                                         ig.Emit (OpCodes.Brfalse, left_is_null_label);
2957                                 }
2958
2959                                 left.Emit (ec);
2960                                 ig.Emit (OpCodes.Dup);
2961                                 if ((Oper == Binary.Operator.BitwiseOr) || (Oper == Binary.Operator.LogicalOr))
2962                                         ig.Emit (OpCodes.Brtrue, wrap_label);
2963                                 else
2964                                         ig.Emit (OpCodes.Brfalse, wrap_label);
2965
2966                                 if (right_unwrap != null) {
2967                                         right_unwrap.EmitCheck (ec);
2968                                         ig.Emit (OpCodes.Brfalse, right_is_null_label);
2969                                 }
2970
2971                                 if ((Oper == Binary.Operator.LogicalAnd) || (Oper == Binary.Operator.LogicalOr))
2972                                         ig.Emit (OpCodes.Pop);
2973
2974                                 right.Emit (ec);
2975                                 if (Oper == Binary.Operator.BitwiseOr)
2976                                         ig.Emit (OpCodes.Or);
2977                                 else if (Oper == Binary.Operator.BitwiseAnd)
2978                                         ig.Emit (OpCodes.And);
2979                                 ig.Emit (OpCodes.Br, wrap_label);
2980
2981                                 ig.MarkLabel (left_is_null_label);
2982                                 if (right_unwrap != null) {
2983                                         right_unwrap.EmitCheck (ec);
2984                                         ig.Emit (OpCodes.Brfalse, is_null_label);
2985                                 }
2986
2987                                 right.Emit (ec);
2988                                 ig.Emit (OpCodes.Dup);
2989                                 if ((Oper == Binary.Operator.BitwiseOr) || (Oper == Binary.Operator.LogicalOr))
2990                                         ig.Emit (OpCodes.Brtrue, wrap_label);
2991                                 else
2992                                         ig.Emit (OpCodes.Brfalse, wrap_label);
2993
2994                                 ig.MarkLabel (right_is_null_label);
2995                                 ig.Emit (OpCodes.Pop);
2996                                 ig.MarkLabel (is_null_label);
2997                                 null_value.Emit (ec);
2998                                 ig.Emit (OpCodes.Br, end_label);
2999
3000                                 ig.MarkLabel (wrap_label);
3001                                 ig.Emit (OpCodes.Nop);
3002                                 bool_wrap.Emit (ec);
3003                                 ig.Emit (OpCodes.Nop);
3004
3005                                 ig.MarkLabel (end_label);
3006                         }
3007
3008                         void EmitEquality (EmitContext ec)
3009                         {
3010                                 ILGenerator ig = ec.ig;
3011
3012                                 // Given 'X? x;' for any value type X: 'x != null' is the same as 'x.HasValue'
3013                                 if (left is NullLiteral) {
3014                                         if (right_unwrap == null)
3015                                                 throw new InternalErrorException ();
3016                                         right_unwrap.EmitCheck (ec);
3017                                         if (Oper == Binary.Operator.Equality) {
3018                                                 ig.Emit (OpCodes.Ldc_I4_0);
3019                                                 ig.Emit (OpCodes.Ceq);
3020                                         }
3021                                         return;
3022                                 }
3023
3024                                 if (right is NullLiteral) {
3025                                         if (left_unwrap == null)
3026                                                 throw new InternalErrorException ();
3027                                         left_unwrap.EmitCheck (ec);
3028                                         if (Oper == Binary.Operator.Equality) {
3029                                                 ig.Emit (OpCodes.Ldc_I4_0);
3030                                                 ig.Emit (OpCodes.Ceq);
3031                                         }
3032                                         return;
3033                                 }
3034
3035                                 Label both_have_value_label = ig.DefineLabel ();
3036                                 Label end_label = ig.DefineLabel ();
3037
3038                                 if (left_unwrap != null && right_unwrap != null) {
3039                                         Label dissimilar_label = ig.DefineLabel ();
3040
3041                                         left_unwrap.EmitCheck (ec);
3042                                         ig.Emit (OpCodes.Dup);
3043                                         right_unwrap.EmitCheck (ec);
3044                                         ig.Emit (OpCodes.Bne_Un, dissimilar_label);
3045
3046                                         ig.Emit (OpCodes.Brtrue, both_have_value_label);
3047
3048                                         // both are null
3049                                         if (Oper == Binary.Operator.Equality)
3050                                                 ig.Emit (OpCodes.Ldc_I4_1);
3051                                         else
3052                                                 ig.Emit (OpCodes.Ldc_I4_0);
3053                                         ig.Emit (OpCodes.Br, end_label);
3054
3055                                         ig.MarkLabel (dissimilar_label);
3056                                         ig.Emit (OpCodes.Pop);
3057                                 } else if (left_unwrap != null) {
3058                                         left_unwrap.EmitCheck (ec);
3059                                         ig.Emit (OpCodes.Brtrue, both_have_value_label);
3060                                 } else if (right_unwrap != null) {
3061                                         right_unwrap.EmitCheck (ec);
3062                                         ig.Emit (OpCodes.Brtrue, both_have_value_label);
3063                                 } else {
3064                                         throw new InternalErrorException ("shouldn't get here");
3065                                 }
3066
3067                                 // one is null while the other isn't
3068                                 if (Oper == Binary.Operator.Equality)
3069                                         ig.Emit (OpCodes.Ldc_I4_0);
3070                                 else
3071                                         ig.Emit (OpCodes.Ldc_I4_1);
3072                                 ig.Emit (OpCodes.Br, end_label);
3073
3074                                 ig.MarkLabel (both_have_value_label);
3075                                 underlying.Emit (ec);
3076
3077                                 ig.MarkLabel (end_label);
3078                         }
3079
3080                         void EmitComparision (EmitContext ec)
3081                         {
3082                                 ILGenerator ig = ec.ig;
3083
3084                                 Label is_null_label = ig.DefineLabel ();
3085                                 Label end_label = ig.DefineLabel ();
3086
3087                                 if (left_unwrap != null) {
3088                                         left_unwrap.EmitCheck (ec);
3089                                         ig.Emit (OpCodes.Brfalse, is_null_label);
3090                                 }
3091
3092                                 if (right_unwrap != null) {
3093                                         right_unwrap.EmitCheck (ec);
3094                                         ig.Emit (OpCodes.Brfalse, is_null_label);
3095                                 }
3096
3097                                 underlying.Emit (ec);
3098                                 ig.Emit (OpCodes.Br, end_label);
3099
3100                                 ig.MarkLabel (is_null_label);
3101                                 ig.Emit (OpCodes.Ldc_I4_0);
3102
3103                                 ig.MarkLabel (end_label);
3104                         }
3105
3106                         public override void Emit (EmitContext ec)
3107                         {
3108                                 if (left_unwrap != null)
3109                                         left_unwrap.Store (ec);
3110                                 if (right_unwrap != null)
3111                                         right_unwrap.Store (ec);
3112
3113                                 if (is_boolean) {
3114                                         EmitBoolean (ec);
3115                                         return;
3116                                 } else if (is_equality) {
3117                                         EmitEquality (ec);
3118                                         return;
3119                                 } else if (is_comparision) {
3120                                         EmitComparision (ec);
3121                                         return;
3122                                 }
3123
3124                                 ILGenerator ig = ec.ig;
3125
3126                                 Label is_null_label = ig.DefineLabel ();
3127                                 Label end_label = ig.DefineLabel ();
3128
3129                                 if (left_unwrap != null) {
3130                                         left_unwrap.EmitCheck (ec);
3131                                         ig.Emit (OpCodes.Brfalse, is_null_label);
3132                                 }
3133
3134                                 if (right_unwrap != null) {
3135                                         right_unwrap.EmitCheck (ec);
3136                                         ig.Emit (OpCodes.Brfalse, is_null_label);
3137                                 }
3138
3139                                 underlying.Emit (ec);
3140                                 ig.Emit (OpCodes.Br, end_label);
3141
3142                                 ig.MarkLabel (is_null_label);
3143                                 null_value.Emit (ec);
3144
3145                                 ig.MarkLabel (end_label);
3146                         }
3147                 }
3148
3149                 public class OperatorTrueOrFalse : Expression
3150                 {
3151                         public readonly bool IsTrue;
3152
3153                         Expression expr;
3154                         Unwrap unwrap;
3155
3156                         public OperatorTrueOrFalse (Expression expr, bool is_true, Location loc)
3157                         {
3158                                 this.IsTrue = is_true;
3159                                 this.expr = expr;
3160                                 this.loc = loc;
3161                         }
3162
3163                         public override Expression DoResolve (EmitContext ec)
3164                         {
3165                                 unwrap = Unwrap.Create (expr, ec);
3166                                 if (unwrap == null)
3167                                         return null;
3168
3169                                 if (unwrap.Type != TypeManager.bool_type)
3170                                         return null;
3171
3172                                 type = TypeManager.bool_type;
3173                                 eclass = ExprClass.Value;
3174                                 return this;
3175                         }
3176
3177                         public override void Emit (EmitContext ec)
3178                         {
3179                                 ILGenerator ig = ec.ig;
3180
3181                                 Label is_null_label = ig.DefineLabel ();
3182                                 Label end_label = ig.DefineLabel ();
3183
3184                                 unwrap.EmitCheck (ec);
3185                                 ig.Emit (OpCodes.Brfalse, is_null_label);
3186
3187                                 unwrap.Emit (ec);
3188                                 if (!IsTrue) {
3189                                         ig.Emit (OpCodes.Ldc_I4_0);
3190                                         ig.Emit (OpCodes.Ceq);
3191                                 }
3192                                 ig.Emit (OpCodes.Br, end_label);
3193
3194                                 ig.MarkLabel (is_null_label);
3195                                 ig.Emit (OpCodes.Ldc_I4_0);
3196
3197                                 ig.MarkLabel (end_label);
3198                         }
3199                 }
3200
3201                 public class NullCoalescingOperator : Expression
3202                 {
3203                         Expression left, right;
3204                         Expression expr;
3205                         Unwrap unwrap;
3206
3207                         public NullCoalescingOperator (Expression left, Expression right, Location loc)
3208                         {
3209                                 this.left = left;
3210                                 this.right = right;
3211                                 this.loc = loc;
3212
3213                                 eclass = ExprClass.Value;
3214                         }
3215
3216                         public override Expression DoResolve (EmitContext ec)
3217                         {
3218                                 if (type != null)
3219                                         return this;
3220
3221                                 left = left.Resolve (ec);
3222                                 if (left == null)
3223                                         return null;
3224
3225                                 right = right.Resolve (ec);
3226                                 if (right == null)
3227                                         return null;
3228
3229                                 Type ltype = left.Type, rtype = right.Type;
3230
3231                                 if (!TypeManager.IsNullableType (ltype) && ltype.IsValueType) {
3232                                         Binary.Error_OperatorCannotBeApplied (loc, "??", ltype, rtype);
3233                                         return null;
3234                                 }
3235
3236                                 if (TypeManager.IsNullableType (ltype)) {
3237                                         NullableInfo info = new NullableInfo (ltype);
3238
3239                                         unwrap = Unwrap.Create (left, ec);
3240                                         if (unwrap == null)
3241                                                 return null;
3242
3243                                         expr = Convert.ImplicitConversion (ec, right, info.UnderlyingType, loc);
3244                                         if (expr != null) {
3245                                                 left = unwrap;
3246                                                 type = expr.Type;
3247                                                 return this;
3248                                         }
3249                                 }
3250
3251                                 expr = Convert.ImplicitConversion (ec, right, ltype, loc);
3252                                 if (expr != null) {
3253                                         type = expr.Type;
3254                                         return this;
3255                                 }
3256
3257                                 Expression left_null = unwrap != null ? unwrap : left;
3258                                 expr = Convert.ImplicitConversion (ec, left_null, rtype, loc);
3259                                 if (expr != null) {
3260                                         left = expr;
3261                                         expr = right;
3262                                         type = rtype;
3263                                         return this;
3264                                 }
3265
3266                                 Binary.Error_OperatorCannotBeApplied (loc, "??", ltype, rtype);
3267                                 return null;
3268                         }
3269
3270                         public override void Emit (EmitContext ec)
3271                         {
3272                                 ILGenerator ig = ec.ig;
3273
3274                                 Label is_null_label = ig.DefineLabel ();
3275                                 Label end_label = ig.DefineLabel ();
3276
3277                                 if (unwrap != null) {
3278                                         unwrap.EmitCheck (ec);
3279                                         ig.Emit (OpCodes.Brfalse, is_null_label);
3280
3281                                         left.Emit (ec);
3282                                         ig.Emit (OpCodes.Br, end_label);
3283
3284                                         ig.MarkLabel (is_null_label);
3285                                         expr.Emit (ec);
3286
3287                                         ig.MarkLabel (end_label);
3288                                 } else {
3289                                         left.Emit (ec);
3290                                         ig.Emit (OpCodes.Dup);
3291                                         ig.Emit (OpCodes.Brtrue, end_label);
3292
3293                                         ig.MarkLabel (is_null_label);
3294
3295                                         ig.Emit (OpCodes.Pop);
3296                                         expr.Emit (ec);
3297
3298                                         ig.MarkLabel (end_label);
3299                                 }
3300                         }
3301                 }
3302
3303                 public class LiftedUnaryMutator : ExpressionStatement
3304                 {
3305                         public readonly UnaryMutator.Mode Mode;
3306                         Expression expr, null_value;
3307                         UnaryMutator underlying;
3308                         Unwrap unwrap;
3309
3310                         public LiftedUnaryMutator (UnaryMutator.Mode mode, Expression expr, Location loc)
3311                         {
3312                                 this.expr = expr;
3313                                 this.Mode = mode;
3314                                 this.loc = loc;
3315
3316                                 eclass = ExprClass.Value;
3317                         }
3318
3319                         public override Expression DoResolve (EmitContext ec)
3320                         {
3321                                 expr = expr.Resolve (ec);
3322                                 if (expr == null)
3323                                         return null;
3324
3325                                 unwrap = Unwrap.Create (expr, ec);
3326                                 if (unwrap == null)
3327                                         return null;
3328
3329                                 underlying = (UnaryMutator) new UnaryMutator (Mode, unwrap, loc).Resolve (ec);
3330                                 if (underlying == null)
3331                                         return null;
3332
3333                                 null_value = new NullableLiteral (expr.Type, loc).Resolve (ec);
3334                                 if (null_value == null)
3335                                         return null;
3336
3337                                 type = expr.Type;
3338                                 return this;
3339                         }
3340
3341                         void DoEmit (EmitContext ec, bool is_expr)
3342                         {
3343                                 ILGenerator ig = ec.ig;
3344                                 Label is_null_label = ig.DefineLabel ();
3345                                 Label end_label = ig.DefineLabel ();
3346
3347                                 unwrap.EmitCheck (ec);
3348                                 ig.Emit (OpCodes.Brfalse, is_null_label);
3349
3350                                 if (is_expr)
3351                                         underlying.Emit (ec);
3352                                 else
3353                                         underlying.EmitStatement (ec);
3354                                 ig.Emit (OpCodes.Br, end_label);
3355
3356                                 ig.MarkLabel (is_null_label);
3357                                 if (is_expr)
3358                                         null_value.Emit (ec);
3359
3360                                 ig.MarkLabel (end_label);
3361                         }
3362
3363                         public override void Emit (EmitContext ec)
3364                         {
3365                                 DoEmit (ec, true);
3366                         }
3367
3368                         public override void EmitStatement (EmitContext ec)
3369                         {
3370                                 DoEmit (ec, false);
3371                         }
3372                 }
3373         }
3374 }