mcs/linq.cs

   1 //
   2 // linq.cs: support for query expressions
   3 //
   4 // Authors: Marek Safar (marek.safar@gmail.com)
   5 //
   6 // Dual licensed under the terms of the MIT X11 or GNU GPL
   7 //
   8 // Copyright 2007-2008 Novell, Inc
   9 //
  10
  11 using System;
  12 using System.Reflection;
  13 using System.Collections;
  14
  15 namespace Mono.CSharp.Linq
  16 {
  17         // NOTES:
  18         // Expression should be IExpression to save some memory and make a few things
  19         // easier to read
  20         //
  21         //
  22
  23         class QueryExpression : AQueryClause
  24         {
  25                 public QueryExpression (Block block, AQueryClause query)
  26                         : base (null, null, query.Location)
  27                 {
  28                         this.next = query;
  29                 }
  30
  31                 public override Expression BuildQueryClause (ResolveContext ec, Expression lSide)
  32                 {
  33                         return next.BuildQueryClause (ec, lSide);
  34                 }
  35
  36                 public override Expression DoResolve (ResolveContext ec)
  37                 {
  38                         int counter = QueryBlock.TransparentParameter.Counter;
  39
  40                         Expression e = BuildQueryClause (ec, null);
  41                         e = e.Resolve (ec);
  42
  43                         //
  44                         // Reset counter in probing mode to ensure that all transparent
  45                         // identifier anonymous types are created only once
  46                         //
  47                         if (ec.IsInProbingMode)
  48                                 QueryBlock.TransparentParameter.Counter = counter;
  49
  50                         return e;
  51                 }
  52
  53                 protected override string MethodName {
  54                         get { throw new NotSupportedException (); }
  55                 }
  56         }
  57
  58         abstract class AQueryClause : Expression
  59         {
  60                 class QueryExpressionAccess : MemberAccess
  61                 {
  62                         public QueryExpressionAccess (Expression expr, string methodName, Location loc)
  63                                 : base (expr, methodName, loc)
  64                         {
  65                         }
  66
  67                         public QueryExpressionAccess (Expression expr, string methodName, TypeArguments typeArguments, Location loc)
  68                                 : base (expr, methodName, typeArguments, loc)
  69                         {
  70                         }
  71
  72                         protected override Expression Error_MemberLookupFailed (ResolveContext ec, Type container_type, Type qualifier_type,
  73                                 Type queried_type, string name, string class_name, MemberTypes mt, BindingFlags bf)
  74                         {
  75                                 ec.Report.Error (1935, loc, "An implementation of `{0}' query expression pattern could not be found. " +
  76                                         "Are you missing `System.Linq' using directive or `System.Core.dll' assembly reference?",
  77                                         name);
  78                                 return null;
  79                         }
  80                 }
  81
  82                 class QueryExpressionInvocation : Invocation, MethodGroupExpr.IErrorHandler
  83                 {
  84                         public QueryExpressionInvocation (QueryExpressionAccess expr, Arguments arguments)
  85                                 : base (expr, arguments)
  86                         {
  87                         }
  88
  89                         protected override MethodGroupExpr DoResolveOverload (ResolveContext ec)
  90                         {
  91                                 mg.CustomErrorHandler = this;
  92                                 MethodGroupExpr rmg = mg.OverloadResolve (ec, ref arguments, false, loc);
  93                                 return rmg;
  94                         }
  95
  96                         public bool AmbiguousCall (ResolveContext ec, MethodBase ambiguous)
  97                         {
  98                                 ec.Report.SymbolRelatedToPreviousError ((MethodInfo) mg);
  99                                 ec.Report.SymbolRelatedToPreviousError (ambiguous);
 100                                 ec.Report.Error (1940, loc, "Ambiguous implementation of the query pattern `{0}' for source type `{1}'",
 101                                         mg.Name, mg.InstanceExpression.GetSignatureForError ());
 102                                 return true;
 103                         }
 104
 105                         public bool NoExactMatch (ResolveContext ec, MethodBase method)
 106                         {
 107                                 AParametersCollection pd = TypeManager.GetParameterData (method);
 108                                 Type source_type = pd.ExtensionMethodType;
 109                                 if (source_type != null) {
 110                                         Argument a = arguments [0];
 111
 112                                         if (TypeManager.IsGenericType (source_type) && TypeManager.ContainsGenericParameters (source_type)) {
 113 #if GMCS_SOURCE
 114                                                 TypeInferenceContext tic = new TypeInferenceContext (TypeManager.GetTypeArguments (source_type));
 115                                                 tic.OutputTypeInference (ec, a.Expr, source_type);
 116                                                 if (tic.FixAllTypes (ec)) {
 117                                                         source_type = TypeManager.DropGenericTypeArguments (source_type).MakeGenericType (tic.InferredTypeArguments);
 118                                                 }
 119 #else
 120                                                 throw new NotSupportedException ();
 121 #endif
 122                                         }
 123
 124                                         if (!Convert.ImplicitConversionExists (ec, a.Expr, source_type)) {
 125                                                 ec.Report.Error (1936, loc, "An implementation of `{0}' query expression pattern for source type `{1}' could not be found",
 126                                                         mg.Name, TypeManager.CSharpName (a.Type));
 127                                                 return true;
 128                                         }
 129                                 }
 130
 131                                 if (!TypeManager.IsGenericMethod (method))
 132                                         return false;
 133
 134                                 if (mg.Name == "SelectMany") {
 135                                         ec.Report.Error (1943, loc,
 136                                                 "An expression type is incorrect in a subsequent `from' clause in a query expression with source type `{0}'",
 137                                                 arguments [0].GetSignatureForError ());
 138                                 } else {
 139                                         ec.Report.Error (1942, loc,
 140                                                 "An expression type in `{0}' clause is incorrect. Type inference failed in the call to `{1}'",
 141                                                 mg.Name.ToLower (), mg.Name);
 142                                 }
 143
 144                                 return true;
 145                         }
 146                 }
 147
 148                 // TODO: protected
 149                 public AQueryClause next;
 150                 public Expression expr;
 151                 protected ToplevelBlock block;
 152
 153                 protected AQueryClause (ToplevelBlock block, Expression expr, Location loc)
 154                 {
 155                         this.block = block;
 156                         this.expr = expr;
 157                         this.loc = loc;
 158                 }
 159
 160                 protected override void CloneTo (CloneContext clonectx, Expression target)
 161                 {
 162                         AQueryClause t = (AQueryClause) target;
 163                         if (expr != null)
 164                                 t.expr = expr.Clone (clonectx);
 165
 166                         if (block != null)
 167                                 t.block = (ToplevelBlock) block.Clone (clonectx);
 168
 169                         if (next != null)
 170                                 t.next = (AQueryClause) next.Clone (clonectx);
 171                 }
 172
 173                 public override Expression CreateExpressionTree (ResolveContext ec)
 174                 {
 175                         // Should not be reached
 176                         throw new NotSupportedException ("ET");
 177                 }
 178
 179                 public override Expression DoResolve (ResolveContext ec)
 180                 {
 181                         return expr.DoResolve (ec);
 182                 }
 183
 184                 public virtual Expression BuildQueryClause (ResolveContext ec, Expression lSide)
 185                 {
 186                         Arguments args;
 187                         CreateArguments (ec, out args);
 188                         lSide = CreateQueryExpression (lSide, args);
 189                         if (next != null) {
 190                                 Select s = next as Select;
 191                                 if (s == null || s.IsRequired)
 192                                         return next.BuildQueryClause (ec, lSide);
 193
 194                                 // Skip transparent select clause if any clause follows
 195                                 if (next.next != null)
 196                                         return next.next.BuildQueryClause (ec, lSide);
 197                         }
 198
 199                         return lSide;
 200                 }
 201
 202                 protected virtual void CreateArguments (ResolveContext ec, out Arguments args)
 203                 {
 204                         args = new Arguments (2);
 205
 206                         LambdaExpression selector = new LambdaExpression (loc);
 207                         selector.Block = block;
 208                         selector.Block.AddStatement (new ContextualReturn (expr));
 209
 210                         args.Add (new Argument (selector));
 211                 }
 212
 213                 protected Invocation CreateQueryExpression (Expression lSide, Arguments arguments)
 214                 {
 215                         return new QueryExpressionInvocation (
 216                                 new QueryExpressionAccess (lSide, MethodName, loc), arguments);
 217                 }
 218
 219                 protected Invocation CreateQueryExpression (Expression lSide, TypeArguments typeArguments, Arguments arguments)
 220                 {
 221                         return new QueryExpressionInvocation (
 222                                 new QueryExpressionAccess (lSide, MethodName, typeArguments, loc), arguments);
 223                 }
 224
 225                 public override void Emit (EmitContext ec)
 226                 {
 227                         throw new NotSupportedException ();
 228                 }
 229
 230                 protected abstract string MethodName { get; }
 231
 232                 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
 233                 {
 234                         // Nothing to mutate
 235                 }
 236
 237                 public virtual AQueryClause Next {
 238                         set {
 239                                 next = value;
 240                         }
 241                 }
 242
 243                 public AQueryClause Tail {
 244                         get {
 245                                 return next == null ? this : next.Tail;
 246                         }
 247                 }
 248         }
 249
 250         //
 251         // A query clause with an identifier (range variable)
 252         //
 253         abstract class ARangeVariableQueryClause : AQueryClause
 254         {
 255                 sealed class RangeAnonymousTypeParameter : AnonymousTypeParameter
 256                 {
 257                         public RangeAnonymousTypeParameter (Expression initializer, LocatedToken parameter)
 258                                 : base (initializer, parameter.Value, parameter.Location)
 259                         {
 260                         }
 261
 262                         protected override void Error_InvalidInitializer (ResolveContext ec, string initializer)
 263                         {
 264                                 ec.Report.Error (1932, loc, "A range variable `{0}' cannot be initialized with `{1}'",
 265                                         Name, initializer);
 266                         }
 267                 }
 268
 269                 protected ARangeVariableQueryClause (ToplevelBlock block, Expression expr)
 270                         : base (block, expr, expr.Location)
 271                 {
 272                 }
 273
 274                 protected static Expression CreateRangeVariableType (ToplevelBlock block, IMemberContext context, LocatedToken name, Expression init)
 275                 {
 276                         ArrayList args = new ArrayList (2);
 277                         args.Add (new AnonymousTypeParameter (block.Parameters [0]));
 278                         args.Add (new RangeAnonymousTypeParameter (init, name));
 279                         return new NewAnonymousType (args, context.CurrentTypeDefinition, name.Location);
 280                 }
 281         }
 282
 283         class QueryStartClause : AQueryClause
 284         {
 285                 public QueryStartClause (Expression expr)
 286                         : base (null, expr, expr.Location)
 287                 {
 288                 }
 289
 290                 public override Expression BuildQueryClause (ResolveContext ec, Expression lSide)
 291                 {
 292                         return next.BuildQueryClause (ec, expr);
 293                 }
 294
 295                 public override Expression DoResolve (ResolveContext ec)
 296                 {
 297                         Expression e = BuildQueryClause (ec, null);
 298                         return e.Resolve (ec);
 299                 }
 300
 301                 protected override string MethodName {
 302                         get { throw new NotSupportedException (); }
 303                 }
 304         }
 305
 306         class Cast : QueryStartClause
 307         {
 308                 // We don't have to clone cast type
 309                 readonly FullNamedExpression type_expr;
 310
 311                 public Cast (FullNamedExpression type, Expression expr)
 312                         : base (expr)
 313                 {
 314                         this.type_expr = type;
 315                 }
 316
 317                 public override Expression BuildQueryClause (ResolveContext ec, Expression lSide)
 318                 {
 319                         lSide = CreateQueryExpression (expr, new TypeArguments (type_expr), null);
 320                         if (next != null)
 321                                 return next.BuildQueryClause (ec, lSide);
 322
 323                         return lSide;
 324                 }
 325
 326                 protected override string MethodName {
 327                         get { return "Cast"; }
 328                 }
 329         }
 330
 331         class GroupBy : AQueryClause
 332         {
 333                 Expression element_selector;
 334                 ToplevelBlock element_block;
 335
 336                 public GroupBy (ToplevelBlock block, Expression elementSelector, ToplevelBlock elementBlock, Expression keySelector, Location loc)
 337                         : base (block, keySelector, loc)
 338                 {
 339                         //
 340                         // Optimizes clauses like `group A by A'
 341                         //
 342                         if (!elementSelector.Equals (keySelector)) {
 343                                 this.element_selector = elementSelector;
 344                                 this.element_block = elementBlock;
 345                         }
 346                 }
 347
 348                 protected override void CreateArguments (ResolveContext ec, out Arguments args)
 349                 {
 350                         base.CreateArguments (ec, out args);
 351
 352                         if (element_selector != null) {
 353                                 LambdaExpression lambda = new LambdaExpression (element_selector.Location);
 354                                 lambda.Block = element_block;
 355                                 lambda.Block.AddStatement (new ContextualReturn (element_selector));
 356                                 args.Add (new Argument (lambda));
 357                         }
 358                 }
 359
 360                 protected override void CloneTo (CloneContext clonectx, Expression target)
 361                 {
 362                         GroupBy t = (GroupBy) target;
 363                         if (element_selector != null) {
 364                                 t.element_selector = element_selector.Clone (clonectx);
 365                                 t.element_block = (ToplevelBlock) element_block.Clone (clonectx);
 366                         }
 367
 368                         base.CloneTo (clonectx, t);
 369                 }
 370
 371                 protected override string MethodName {
 372                         get { return "GroupBy"; }
 373                 }
 374         }
 375
 376         class Join : ARangeVariableQueryClause
 377         {
 378                 readonly LocatedToken lt;
 379                 ToplevelBlock inner_selector, outer_selector;
 380
 381                 public Join (ToplevelBlock block, LocatedToken lt, Expression inner, ToplevelBlock outerSelector, ToplevelBlock innerSelector, Location loc)
 382                         : base (block, inner)
 383                 {
 384                         this.lt = lt;
 385                         this.outer_selector = outerSelector;
 386                         this.inner_selector = innerSelector;
 387                 }
 388
 389                 protected override void CreateArguments (ResolveContext ec, out Arguments args)
 390                 {
 391                         args = new Arguments (4);
 392
 393                         args.Add (new Argument (expr));
 394
 395                         LambdaExpression lambda = new LambdaExpression (outer_selector.StartLocation);
 396                         lambda.Block = outer_selector;
 397                         args.Add (new Argument (lambda));
 398
 399                         lambda = new LambdaExpression (inner_selector.StartLocation);
 400                         lambda.Block = inner_selector;
 401                         args.Add (new Argument (lambda));
 402
 403                         Expression result_selector_expr;
 404                         LocatedToken into_variable = GetIntoVariable ();
 405                         //
 406                         // When select follows use is as result selector
 407                         //
 408                         if (next is Select) {
 409                                 result_selector_expr = next.expr;
 410                                 next = next.next;
 411                         } else {
 412                                 result_selector_expr = CreateRangeVariableType (block, ec.MemberContext, into_variable,
 413                                         new SimpleName (into_variable.Value, into_variable.Location));
 414                         }
 415
 416                         LambdaExpression result_selector = new LambdaExpression (lt.Location);
 417                         result_selector.Block = new QueryBlock (ec.Compiler, block.Parent, block.Parameters, into_variable, block.StartLocation);
 418                         result_selector.Block.AddStatement (new ContextualReturn (result_selector_expr));
 419
 420                         args.Add (new Argument (result_selector));
 421                 }
 422
 423                 protected virtual LocatedToken GetIntoVariable ()
 424                 {
 425                         return lt;
 426                 }
 427
 428                 protected override void CloneTo (CloneContext clonectx, Expression target)
 429                 {
 430                         Join t = (Join) target;
 431                         t.inner_selector = (ToplevelBlock) inner_selector.Clone (clonectx);
 432                         t.outer_selector = (ToplevelBlock) outer_selector.Clone (clonectx);
 433                         base.CloneTo (clonectx, t);
 434                 }
 435
 436                 protected override string MethodName {
 437                         get { return "Join"; }
 438                 }
 439         }
 440
 441         class GroupJoin : Join
 442         {
 443                 readonly LocatedToken into;
 444
 445                 public GroupJoin (ToplevelBlock block, LocatedToken lt, Expression inner,
 446                         ToplevelBlock outerSelector, ToplevelBlock innerSelector, LocatedToken into, Location loc)
 447                         : base (block, lt, inner, outerSelector, innerSelector, loc)
 448                 {
 449                         this.into = into;
 450                 }
 451
 452                 protected override LocatedToken GetIntoVariable ()
 453                 {
 454                         return into;
 455                 }
 456
 457                 protected override string MethodName {
 458                         get { return "GroupJoin"; }
 459                 }
 460         }
 461
 462         class Let : ARangeVariableQueryClause
 463         {
 464                 public Let (ToplevelBlock block, TypeContainer container, LocatedToken identifier, Expression expr)
 465                         : base (block, CreateRangeVariableType (block, container, identifier, expr))
 466                 {
 467                 }
 468
 469                 protected override string MethodName {
 470                         get { return "Select"; }
 471                 }
 472         }
 473
 474         class Select : AQueryClause
 475         {
 476                 public Select (ToplevelBlock block, Expression expr, Location loc)
 477                         : base (block, expr, loc)
 478                 {
 479                 }
 480
 481                 //
 482                 // For queries like `from a orderby a select a'
 483                 // the projection is transparent and select clause can be safely removed
 484                 //
 485                 public bool IsRequired {
 486                         get {
 487                                 SimpleName sn = expr as SimpleName;
 488                                 if (sn == null)
 489                                         return true;
 490
 491                                 return sn.Name != block.Parameters.FixedParameters [0].Name;
 492                         }
 493                 }
 494
 495                 protected override string MethodName {
 496                         get { return "Select"; }
 497                 }
 498         }
 499
 500         class SelectMany : ARangeVariableQueryClause
 501         {
 502                 LocatedToken lt;
 503
 504                 public SelectMany (ToplevelBlock block, LocatedToken lt, Expression expr)
 505                         : base (block, expr)
 506                 {
 507                         this.lt = lt;
 508                 }
 509
 510                 protected override void CreateArguments (ResolveContext ec, out Arguments args)
 511                 {
 512                         base.CreateArguments (ec, out args);
 513
 514                         Expression result_selector_expr;
 515                         //
 516                         // When select follow use is as result selector
 517                         //
 518                         if (next is Select) {
 519                                 result_selector_expr = next.expr;
 520                                 next = next.next;
 521                         } else {
 522                                 result_selector_expr = CreateRangeVariableType (block, ec.MemberContext, lt, new SimpleName (lt.Value, lt.Location));
 523                         }
 524
 525                         LambdaExpression result_selector = new LambdaExpression (lt.Location);
 526                         result_selector.Block = new QueryBlock (ec.Compiler, block.Parent, block.Parameters, lt, block.StartLocation);
 527                         result_selector.Block.AddStatement (new ContextualReturn (result_selector_expr));
 528
 529                         args.Add (new Argument (result_selector));
 530                 }
 531
 532                 protected override string MethodName {
 533                         get { return "SelectMany"; }
 534                 }
 535         }
 536
 537         class Where : AQueryClause
 538         {
 539                 public Where (ToplevelBlock block, Expression expr, Location loc)
 540                         : base (block, expr, loc)
 541                 {
 542                 }
 543
 544                 protected override string MethodName {
 545                         get { return "Where"; }
 546                 }
 547         }
 548
 549         class OrderByAscending : AQueryClause
 550         {
 551                 public OrderByAscending (ToplevelBlock block,Expression expr)
 552                         : base (block, expr, expr.Location)
 553                 {
 554                 }
 555
 556                 protected override string MethodName {
 557                         get { return "OrderBy"; }
 558                 }
 559         }
 560
 561         class OrderByDescending : AQueryClause
 562         {
 563                 public OrderByDescending (ToplevelBlock block, Expression expr)
 564                         : base (block, expr, expr.Location)
 565                 {
 566                 }
 567
 568                 protected override string MethodName {
 569                         get { return "OrderByDescending"; }
 570                 }
 571         }
 572
 573         class ThenByAscending : OrderByAscending
 574         {
 575                 public ThenByAscending (ToplevelBlock block, Expression expr)
 576                         : base (block, expr)
 577                 {
 578                 }
 579
 580                 protected override string MethodName {
 581                         get { return "ThenBy"; }
 582                 }
 583         }
 584
 585         class ThenByDescending : OrderByDescending
 586         {
 587                 public ThenByDescending (ToplevelBlock block, Expression expr)
 588                         : base (block, expr)
 589                 {
 590                 }
 591
 592                 protected override string MethodName {
 593                         get { return "ThenByDescending"; }
 594                 }
 595         }
 596
 597         //
 598         // Implicit query block
 599         //
 600         class QueryBlock : ToplevelBlock
 601         {
 602                 //
 603                 // Transparent parameters are used to package up the intermediate results
 604                 // and pass them onto next clause
 605                 //
 606                 public sealed class TransparentParameter : ImplicitLambdaParameter
 607                 {
 608                         public static int Counter;
 609                         const string ParameterNamePrefix = "<>__TranspIdent";
 610
 611                         public readonly ParametersCompiled Parent;
 612                         public readonly string Identifier;
 613
 614                         public TransparentParameter (ParametersCompiled parent, LocatedToken identifier)
 615                                 : base (ParameterNamePrefix + Counter++, identifier.Location)
 616                         {
 617                                 Parent = parent;
 618                                 Identifier = identifier.Value;
 619                         }
 620
 621                         public static void Reset ()
 622                         {
 623                                 Counter = 0;
 624                         }
 625                 }
 626
 627                 public sealed class ImplicitQueryParameter : ImplicitLambdaParameter
 628                 {
 629                         public ImplicitQueryParameter (string name, Location loc)
 630                                 : base (name, loc)
 631                         {
 632                         }
 633                 }
 634
 635                 public QueryBlock (CompilerContext ctx, Block parent, LocatedToken lt, Location start)
 636                         : base (ctx, parent, new ParametersCompiled (new ImplicitQueryParameter (lt.Value, lt.Location)), start)
 637                 {
 638                         if (parent != null)
 639                                 base.CheckParentConflictName (parent.Toplevel, lt.Value, lt.Location);
 640                 }
 641
 642                 public QueryBlock (CompilerContext ctx, Block parent, ParametersCompiled parameters, LocatedToken lt, Location start)
 643                         : base (ctx, parent, new ParametersCompiled (parameters [0].Clone (), new ImplicitQueryParameter (lt.Value, lt.Location)), start)
 644                 {
 645                 }
 646
 647                 public QueryBlock (CompilerContext ctx, Block parent, Location start)
 648                         : base (ctx, parent, parent.Toplevel.Parameters.Clone (), start)
 649                 {
 650                 }
 651
 652                 public void AddTransparentParameter (LocatedToken name)
 653                 {
 654                         base.CheckParentConflictName (this, name.Value, name.Location);
 655
 656                         parameters = new ParametersCompiled (new TransparentParameter (parameters, name));
 657                 }
 658
 659                 protected override bool CheckParentConflictName (ToplevelBlock block, string name, Location l)
 660                 {
 661                         return true;
 662                 }
 663
 664                 //
 665                 // Query parameter reference can include transparent parameters
 666                 //
 667                 protected override Expression GetParameterReferenceExpression (string name, Location loc)
 668                 {
 669                         Expression expr = base.GetParameterReferenceExpression (name, loc);
 670                         if (expr != null)
 671                                 return expr;
 672
 673                         TransparentParameter tp = parameters [0] as TransparentParameter;
 674                         while (tp != null) {
 675                                 if (tp.Identifier == name)
 676                                         break;
 677
 678                                 TransparentParameter tp_next = tp.Parent [0] as TransparentParameter;
 679                                 if (tp_next == null) {
 680                                         if (tp.Parent.GetParameterIndexByName (name) >= 0)
 681                                                 break;
 682                                 }
 683
 684                                 tp = tp_next;
 685                         }
 686
 687                         if (tp != null) {
 688                                 expr = new SimpleName (parameters[0].Name, loc);
 689                                 TransparentParameter tp_cursor = (TransparentParameter) parameters[0];
 690                                 while (tp_cursor != tp) {
 691                                         tp_cursor = (TransparentParameter) tp_cursor.Parent[0];
 692                                         expr = new MemberAccess (expr, tp_cursor.Name);
 693                                 }
 694
 695                                 return new MemberAccess (expr, name);
 696                         }
 697
 698                         return null;
 699                 }
 700
 701                 protected override void Error_AlreadyDeclared (Location loc, string var, string reason)
 702                 {
 703                         Report.Error (1931, loc, "A range variable `{0}' conflicts with a previous declaration of `{0}'",
 704                                 var);
 705                 }
 706
 707                 protected override void Error_AlreadyDeclared (Location loc, string var)
 708                 {
 709                         Report.Error (1930, loc, "A range variable `{0}' has already been declared in this scope",
 710                                 var);
 711                 }
 712
 713                 public override void Error_AlreadyDeclaredTypeParameter (Report r, Location loc, string name, string conflict)
 714                 {
 715                         r.Error (1948, loc, "A range variable `{0}' conflicts with a method type parameter",
 716                                 name);
 717                 }
 718         }
 719 }