**** Merged r37880 from MCS ****
[mono.git] / mcs / gmcs / rootcontext.cs
1 //
2 // rootcontext.cs: keeps track of our tree representation, and assemblies loaded.
3 //
4 // Author: Miguel de Icaza (miguel@ximian.com)
5 //         Ravi Pratap     (ravi@ximian.com)
6 //
7 // Licensed under the terms of the GNU GPL
8 //
9 // (C) 2001 Ximian, Inc (http://www.ximian.com)
10 // (C) 2004 Novell, Inc
11
12 using System;
13 using System.Collections;
14 using System.Reflection;
15 using System.Reflection.Emit;
16 using System.Diagnostics;
17 using System.Xml;
18
19 namespace Mono.CSharp {
20
21         public enum LanguageVersion
22         {
23                 Default = 0,
24                 ISO_1   = 1
25         }
26
27         public class RootContext {
28
29                 //
30                 // Contains the parsed tree
31                 //
32                 static Tree tree;
33
34                 //
35                 // This hashtable contains all of the #definitions across the source code
36                 // it is used by the ConditionalAttribute handler.
37                 //
38                 public static Hashtable AllDefines = new Hashtable ();
39                 
40                 //
41                 // Whether we are being linked against the standard libraries.
42                 // This is only used to tell whether `System.Object' should
43                 // have a base class or not.
44                 //
45                 public static bool StdLib = true;
46
47                 //
48                 // This keeps track of the order in which classes were defined
49                 // so that we can poulate them in that order.
50                 //
51                 // Order is important, because we need to be able to tell, by
52                 // examining the list of methods of the base class, which ones are virtual
53                 // or abstract as well as the parent names (to implement new, 
54                 // override).
55                 //
56                 static ArrayList type_container_resolve_order;
57                 static ArrayList attribute_types;
58
59                 //
60                 // Holds a reference to the Private Implementation Details
61                 // class.
62                 //
63                 static ArrayList helper_classes;
64                 
65                 static TypeBuilder impl_details_class;
66
67                 public static int WarningLevel = 3;
68
69                 public static Target Target = Target.Exe;
70                 public static string TargetExt = ".exe";
71
72                 public static bool VerifyClsCompliance = true;
73
74                 public static LanguageVersion Version = LanguageVersion.Default;
75
76                 //
77                 // We keep strongname related info here because
78                 // it's also used as complier options from CSC 8.x
79                 //
80                 public static string StrongNameKeyFile;
81                 public static string StrongNameKeyContainer;
82                 public static bool StrongNameDelaySign = false;
83
84                 //
85                 // If set, enable XML documentation generation
86                 //
87                 public static Documentation Documentation;
88
89                 //
90                 // Constructor
91                 //
92                 static RootContext ()
93                 {
94                         tree = new Tree ();
95                         type_container_resolve_order = new ArrayList ();
96                 }
97
98                 public static bool NeedsEntryPoint {
99                         get {
100                                 return RootContext.Target == Target.Exe || RootContext.Target == Target.WinExe;
101                         }
102                 }
103
104                 static public Tree Tree {
105                         get {
106                                 return tree;
107                         }
108                 }
109
110                 static public string MainClass;
111                 
112                 public static void RegisterOrder (TypeContainer tc)
113                 {
114                         type_container_resolve_order.Add (tc);
115                 }
116
117                 public static void RegisterAttribute (TypeContainer tc)
118                 {
119                         if (attribute_types == null)
120                                 attribute_types = new ArrayList ();
121                         
122                         attribute_types.Add (tc);
123                 }
124                 
125                 // 
126                 // The default compiler checked state
127                 //
128                 static public bool Checked = false;
129
130                 //
131                 // Whether to allow Unsafe code
132                 //
133                 static public bool Unsafe = false;
134                 
135                 static string MakeFQN (string nsn, string name)
136                 {
137                         if (nsn == "")
138                                 return name;
139                         return String.Concat (nsn, ".", name);
140                 }
141
142                 // <remarks>
143                 //   This function is used to resolve the hierarchy tree.
144                 //   It processes interfaces, structs and classes in that order.
145                 //
146                 //   It creates the TypeBuilder's as it processes the user defined
147                 //   types.  
148                 // </remarks>
149                 static public void ResolveTree ()
150                 {
151                         //
152                         // Process the attribute types separately and before anything else
153                         //
154                         if (attribute_types != null)
155                                 foreach (TypeContainer tc in attribute_types)
156                                         tc.DefineType ();
157                         
158                         //
159                         // Interfaces are processed next, as classes and
160                         // structs might inherit from an object or implement
161                         // a set of interfaces, we need to be able to tell
162                         // them appart by just using the TypeManager.
163                         //
164                         TypeContainer root = Tree.Types;
165
166                         ArrayList ifaces = root.Interfaces;
167                         if (ifaces != null){
168                                 foreach (Interface i in ifaces) 
169                                         i.DefineType ();
170                         }
171
172                         foreach (TypeContainer tc in root.Types)
173                                 tc.DefineType ();
174
175                         if (root.Delegates != null)
176                                 foreach (Delegate d in root.Delegates) 
177                                         d.DefineType ();
178
179                         if (root.Enums != null)
180                                 foreach (Enum e in root.Enums)
181                                         e.DefineType ();
182                 }
183
184                 static void Error_TypeConflict (string name, Location loc)
185                 {
186                         Report.Error (
187                                 520, loc, "`" + name + "' conflicts with a predefined type");
188                 }
189
190                 static void Error_TypeConflict (string name)
191                 {
192                         Report.Error (
193                                 520, "`" + name + "' conflicts with a predefined type");
194                 }
195
196                 //
197                 // Resolves a single class during the corlib bootstrap process
198                 //
199                 static TypeBuilder BootstrapCorlib_ResolveClass (TypeContainer root, string name)
200                 {
201                         object o = root.GetDefinition (name);
202                         if (o == null){
203                                 Report.Error (518, "The predefined type `" + name + "' is not defined");
204                                 return null;
205                         }
206
207                         if (!(o is Class)){
208                                 if (o is DeclSpace){
209                                         DeclSpace d = (DeclSpace) o;
210
211                                         Error_TypeConflict (name, d.Location);
212                                 } else
213                                         Error_TypeConflict (name);
214
215                                 return null;
216                         }
217
218                         return ((DeclSpace) o).DefineType ();
219                 }
220
221                 //
222                 // Resolves a struct during the corlib bootstrap process
223                 //
224                 static void BootstrapCorlib_ResolveStruct (TypeContainer root, string name)
225                 {
226                         object o = root.GetDefinition (name);
227                         if (o == null){
228                                 Report.Error (518, "The predefined type `" + name + "' is not defined");
229                                 return;
230                         }
231
232                         if (!(o is Struct)){
233                                 if (o is DeclSpace){
234                                         DeclSpace d = (DeclSpace) o;
235
236                                         Error_TypeConflict (name, d.Location);
237                                 } else
238                                         Error_TypeConflict (name);
239
240                                 return;
241                         }
242
243                         ((DeclSpace) o).DefineType ();
244                 }
245
246                 //
247                 // Resolves a struct during the corlib bootstrap process
248                 //
249                 static void BootstrapCorlib_ResolveInterface (TypeContainer root, string name)
250                 {
251                         object o = root.GetDefinition (name);
252                         if (o == null){
253                                 Report.Error (518, "The predefined type `" + name + "' is not defined");
254                                 return;
255                         }
256
257                         if (!(o is Interface)){
258                                 if (o is DeclSpace){
259                                         DeclSpace d = (DeclSpace) o;
260
261                                         Error_TypeConflict (name, d.Location);
262                                 } else
263                                         Error_TypeConflict (name);
264
265                                 return;
266                         }
267
268                         ((DeclSpace) o).DefineType ();
269                 }
270
271                 //
272                 // Resolves a delegate during the corlib bootstrap process
273                 //
274                 static void BootstrapCorlib_ResolveDelegate (TypeContainer root, string name)
275                 {
276                         object o = root.GetDefinition (name);
277                         if (o == null){
278                                 Report.Error (518, "The predefined type `" + name + "' is not defined");
279                                 Environment.Exit (1);
280                         }
281
282                         if (!(o is Delegate)){
283                                 Error_TypeConflict (name);
284                                 return;
285                         }
286
287                         ((DeclSpace) o).DefineType ();
288                 }
289                 
290
291                 /// <summary>
292                 ///    Resolves the core types in the compiler when compiling with --nostdlib
293                 /// </summary>
294                 static public void ResolveCore ()
295                 {
296                         TypeContainer root = Tree.Types;
297
298                         TypeManager.object_type = BootstrapCorlib_ResolveClass (root, "System.Object");
299                         TypeManager.value_type = BootstrapCorlib_ResolveClass (root, "System.ValueType");
300                         TypeManager.attribute_type = BootstrapCorlib_ResolveClass (root, "System.Attribute");
301                         
302                         string [] interfaces_first_stage = {
303                                 "System.IComparable", "System.ICloneable",
304                                 "System.IConvertible",
305                                 
306                                 "System.Collections.IEnumerable",
307                                 "System.Collections.ICollection",
308                                 "System.Collections.IEnumerator",
309                                 "System.Collections.IList", 
310                                 "System.IAsyncResult",
311                                 "System.IDisposable",
312                                 
313                                 "System.Runtime.Serialization.ISerializable",
314                                 "System.Runtime.InteropServices._Exception",
315
316                                 "System.Reflection.IReflect",
317                                 "System.Reflection.ICustomAttributeProvider",
318
319                                 //
320                                 // Generic types
321                                 //
322                                 "System.Collections.Generic.IEnumerator`1",
323                                 "System.Collections.Generic.IEnumerable`1"
324                         };
325
326                         foreach (string iname in interfaces_first_stage)
327                                 BootstrapCorlib_ResolveInterface (root, iname);
328
329                         //
330                         // These are the base value types
331                         //
332                         string [] structs_first_stage = {
333                                 "System.Byte",    "System.SByte",
334                                 "System.Int16",   "System.UInt16",
335                                 "System.Int32",   "System.UInt32",
336                                 "System.Int64",   "System.UInt64",
337                         };
338
339                         foreach (string cname in structs_first_stage)
340                                 BootstrapCorlib_ResolveStruct (root, cname);
341
342                         //
343                         // Now, we can load the enumerations, after this point,
344                         // we can use enums.
345                         //
346                         TypeManager.InitEnumUnderlyingTypes ();
347
348                         string [] structs_second_stage = {
349                                 "System.Single",  "System.Double",
350                                 "System.Char",    "System.Boolean",
351                                 "System.Decimal", "System.Void",
352                                 "System.RuntimeFieldHandle",
353                                 "System.RuntimeArgumentHandle",
354                                 "System.RuntimeTypeHandle",
355                                 "System.IntPtr",
356                                 "System.TypedReference",
357                                 "System.ArgIterator"
358                         };
359                         
360                         foreach (string cname in structs_second_stage)
361                                 BootstrapCorlib_ResolveStruct (root, cname);
362                         
363                         //
364                         // These are classes that depends on the core interfaces
365                         //
366                         string [] classes_second_stage = {
367                                 "System.Reflection.MemberInfo",
368                                 "System.Type",
369                                 "System.Exception",
370                                 "System.Activator",
371
372                                 //
373                                 // These are not really important in the order, but they
374                                 // are used by the compiler later on (typemanager/CoreLookupType-d)
375                                 //
376                                 "System.Runtime.CompilerServices.RuntimeHelpers",
377                                 "System.Reflection.DefaultMemberAttribute",
378                                 "System.Threading.Monitor",
379                                 
380                                 "System.AttributeUsageAttribute",
381                                 "System.Runtime.InteropServices.DllImportAttribute",
382                                 "System.Runtime.CompilerServices.MethodImplAttribute",
383                                 "System.Runtime.InteropServices.MarshalAsAttribute",
384                                 "System.Runtime.CompilerServices.NewConstraintAttribute",
385                                 "System.Diagnostics.ConditionalAttribute",
386                                 "System.ObsoleteAttribute",
387                                 "System.ParamArrayAttribute",
388                                 "System.CLSCompliantAttribute",
389                                 "System.Security.UnverifiableCodeAttribute",
390                                 "System.Security.Permissions.SecurityAttribute",
391                                 "System.Runtime.CompilerServices.IndexerNameAttribute",
392                                 "System.Runtime.CompilerServices.DecimalConstantAttribute",
393                                 "System.Runtime.InteropServices.InAttribute",
394                                 "System.Runtime.InteropServices.OutAttribute",
395                                 "System.Runtime.InteropServices.StructLayoutAttribute",
396                                 "System.Runtime.InteropServices.FieldOffsetAttribute",
397                                 "System.InvalidOperationException",
398                                 "System.NotSupportedException",
399                                 "System.MarshalByRefObject",
400                                 "System.Security.CodeAccessPermission"
401                         };
402
403                         // We must store them here before calling BootstrapCorlib_ResolveDelegate.
404                         TypeManager.string_type = BootstrapCorlib_ResolveClass (root, "System.String");
405                         TypeManager.enum_type = BootstrapCorlib_ResolveClass (root, "System.Enum");
406                         TypeManager.array_type = BootstrapCorlib_ResolveClass (root, "System.Array");
407                         TypeManager.multicast_delegate_type = BootstrapCorlib_ResolveClass (root, "System.MulticastDelegate");
408                         TypeManager.delegate_type = BootstrapCorlib_ResolveClass (root, "System.Delegate");
409                         
410                         foreach (string cname in classes_second_stage)
411                                 BootstrapCorlib_ResolveClass (root, cname);
412
413                         BootstrapCorlib_ResolveDelegate (root, "System.AsyncCallback");
414                 }
415                         
416                 // <summary>
417                 //   Closes all open types
418                 // </summary>
419                 //
420                 // <remarks>
421                 //   We usually use TypeBuilder types.  When we are done
422                 //   creating the type (which will happen after we have added
423                 //   methods, fields, etc) we need to "Define" them before we
424                 //   can save the Assembly
425                 // </remarks>
426                 static public void CloseTypes ()
427                 {
428                         TypeContainer root = Tree.Types;
429                         
430                         if (root.Enums != null)
431                                 foreach (Enum en in root.Enums)
432                                         en.CloseType ();
433
434                         if (attribute_types != null)
435                                 foreach (TypeContainer tc in attribute_types)
436                                         tc.CloseType ();
437                         
438                         //
439                         // We do this in two passes, first we close the structs,
440                         // then the classes, because it seems the code needs it this
441                         // way.  If this is really what is going on, we should probably
442                         // make sure that we define the structs in order as well.
443                         //
444                         foreach (TypeContainer tc in type_container_resolve_order){
445                                 if (tc.Kind == Kind.Struct && tc.Parent == tree.Types){
446                                         tc.CloseType ();
447                                 }
448                         }
449
450                         foreach (TypeContainer tc in type_container_resolve_order){
451                                 if (!(tc.Kind == Kind.Struct && tc.Parent == tree.Types))
452                                         tc.CloseType ();                                        
453                         }
454                         
455                         if (root.Delegates != null)
456                                 foreach (Delegate d in root.Delegates)
457                                         d.CloseType ();
458
459
460                         //
461                         // If we have a <PrivateImplementationDetails> class, close it
462                         //
463                         if (helper_classes != null){
464                                 foreach (TypeBuilder type_builder in helper_classes)
465                                         type_builder.CreateType ();
466                         }
467                         
468                         attribute_types = null;
469                         type_container_resolve_order = null;
470                         helper_classes = null;
471                         //tree = null;
472                         TypeManager.CleanUp ();
473                 }
474
475                 /// <summary>
476                 ///   Used to register classes that need to be closed after all the
477                 ///   user defined classes
478                 /// </summary>
479                 public static void RegisterHelperClass (TypeBuilder helper_class)
480                 {
481                         if (helper_classes == null)
482                                 helper_classes = new ArrayList ();
483                         helper_classes.Add (helper_class);
484                 }
485                 
486                 static Type NamespaceLookup (DeclSpace ds, string name, int num_type_args, Location loc)
487                 {
488                         IAlias result = ds.NamespaceEntry.LookupNamespaceOrType (ds, name, loc);
489                         if (result == null)
490                                 return null;
491
492                         if (!result.IsType)
493                                 return null;
494
495                         TypeExpr texpr = result.ResolveAsType (ds.EmitContext);
496                         if (texpr == null)
497                                 return null;
498
499                         return texpr.Type;
500                 }
501                 
502                 static public Type LookupType (DeclSpace ds, string name, bool silent, Location loc)
503                 {
504                         return LookupType (ds, name, silent, 0, loc);
505                 }
506
507                 //
508                 // Public function used to locate types, this can only
509                 // be used after the ResolveTree function has been invoked.
510                 //
511                 // Returns: Type or null if they type can not be found.
512                 //
513                 // Come to think of it, this should be a DeclSpace
514                 //
515                 static public Type LookupType (DeclSpace ds, string name, bool silent,
516                                                int num_type_params, Location loc)
517                 {
518                         Type t;
519
520                         if (ds.Cache.Contains (name)){
521                                 t = (Type) ds.Cache [name];
522                                 if (t != null)
523                                         return t;
524                         } else {
525                                 //
526                                 // For the case the type we are looking for is nested within this one
527                                 // or is in any base class
528                                 //
529                                 DeclSpace containing_ds = ds;
530                                 while (containing_ds != null){
531                                         Type current_type = containing_ds.TypeBuilder;
532                                         
533                                         while (current_type != null) {
534                                                 //
535                                                 // nested class
536                                                 //
537                                                 Type type = TypeManager.LookupType (current_type.FullName + "." + name);
538                                                 if (type != null){
539                                                         t = ds.ResolveNestedType (type, loc);
540                                                         ds.Cache [name] = t;
541                                                         return t;
542                                                 }
543                                                 
544                                                 current_type = current_type.BaseType;
545                                         }
546                                         
547                                         containing_ds = containing_ds.Parent;
548                                 }
549                                 
550                                 t = NamespaceLookup (ds, name, num_type_params, loc);
551                                 if (!silent || t != null){
552                                         ds.Cache [name] = t;
553                                         return t;
554                                 }
555                         }
556
557                         if (!silent)
558                                 Report.Error (246, loc, "Cannot find type `"+name+"'");
559                         
560                         return null;
561                 }
562
563                 // <summary>
564                 //   This is the silent version of LookupType, you can use this
565                 //   to `probe' for a type
566                 // </summary>
567                 static public Type LookupType (TypeContainer tc, string name, Location loc)
568                 {
569                         return LookupType (tc, name, true, loc);
570                 }
571
572                 static void Report1530 (Location loc)
573                 {
574                         Report.Error (1530, loc, "Keyword new not allowed for namespace elements");
575                 }
576                 
577                 static public void PopulateCoreType (TypeContainer root, string name)
578                 {
579                         DeclSpace ds = (DeclSpace) root.GetDefinition (name);
580
581                         ds.DefineMembers (root);
582                         ds.Define ();
583                 }
584                 
585                 static public void BootCorlib_PopulateCoreTypes ()
586                 {
587                         TypeContainer root = tree.Types;
588
589                         PopulateCoreType (root, "System.Object");
590                         PopulateCoreType (root, "System.ValueType");
591                         PopulateCoreType (root, "System.Attribute");
592                 }
593                 
594                 // <summary>
595                 //   Populates the structs and classes with fields and methods
596                 // </summary>
597                 //
598                 // This is invoked after all interfaces, structs and classes
599                 // have been defined through `ResolveTree' 
600                 static public void PopulateTypes ()
601                 {
602                         TypeContainer root = Tree.Types;
603
604                         if (attribute_types != null)
605                                 foreach (TypeContainer tc in attribute_types)
606                                         tc.DefineMembers (root);
607
608                         if (type_container_resolve_order != null){
609                                 if (RootContext.StdLib){
610                                         foreach (TypeContainer tc in type_container_resolve_order)
611                                                 tc.DefineMembers (root);
612                                 } else {
613                                         foreach (TypeContainer tc in type_container_resolve_order) {
614                                                 // When compiling corlib, these types have already been
615                                                 // populated from BootCorlib_PopulateCoreTypes ().
616                                                 if (((tc.Name == "System.Object") ||
617                                                      (tc.Name == "System.Attribute") ||
618                                                      (tc.Name == "System.ValueType")))
619                                                 continue;
620
621                                                 tc.DefineMembers (root);
622                                         }
623                                 } 
624                         }
625
626                         ArrayList delegates = root.Delegates;
627                         if (delegates != null){
628                                 foreach (Delegate d in delegates)
629                                         if ((d.ModFlags & Modifiers.NEW) == 0)
630                                                 d.DefineMembers (root);
631                                         else
632                                                 Report1530 (d.Location);
633                         }
634
635                         ArrayList enums = root.Enums;
636                         if (enums != null){
637                                 foreach (Enum en in enums)
638                                         if ((en.ModFlags & Modifiers.NEW) == 0)
639                                                 en.DefineMembers (root);
640                                         else
641                                                 Report1530 (en.Location);
642                         }
643
644                         //
645                         // Check for cycles in the struct layout
646                         //
647                         if (type_container_resolve_order != null){
648                                 Hashtable seen = new Hashtable ();
649                                 foreach (TypeContainer tc in type_container_resolve_order)
650                                         TypeManager.CheckStructCycles (tc, seen);
651                         }
652                 }
653
654                 //
655                 // A generic hook delegate
656                 //
657                 public delegate void Hook ();
658
659                 //
660                 // A hook invoked when the code has been generated.
661                 //
662                 public static event Hook EmitCodeHook;
663
664                 //
665                 // DefineTypes is used to fill in the members of each type.
666                 //
667                 static public void DefineTypes ()
668                 {
669                         TypeContainer root = Tree.Types;
670
671                         if (attribute_types != null)
672                                 foreach (TypeContainer tc in attribute_types)
673                                         tc.Define ();
674
675                         if (type_container_resolve_order != null){
676                                 foreach (TypeContainer tc in type_container_resolve_order) {
677                                         // When compiling corlib, these types have already been
678                                         // populated from BootCorlib_PopulateCoreTypes ().
679                                         if (!RootContext.StdLib &&
680                                             ((tc.Name == "System.Object") ||
681                                              (tc.Name == "System.Attribute") ||
682                                              (tc.Name == "System.ValueType")))
683                                                 continue;
684
685                                         if ((tc.ModFlags & Modifiers.NEW) == 0)
686                                                 tc.Define ();
687                                 }
688                         }
689
690                         ArrayList delegates = root.Delegates;
691                         if (delegates != null){
692                                 foreach (Delegate d in delegates)
693                                         if ((d.ModFlags & Modifiers.NEW) == 0)
694                                                 d.Define ();
695                         }
696
697                         ArrayList enums = root.Enums;
698                         if (enums != null){
699                                 foreach (Enum en in enums)
700                                         if ((en.ModFlags & Modifiers.NEW) == 0)
701                                                 en.Define ();
702                         }
703                 }
704
705                 static public void EmitCode ()
706                 {
707                         if (attribute_types != null)
708                                 foreach (TypeContainer tc in attribute_types)
709                                         tc.EmitType ();
710
711                         CodeGen.Assembly.Emit (Tree.Types);
712                         CodeGen.Module.Emit (Tree.Types);
713                         
714                         if (Tree.Types.Enums != null) {
715                                 foreach (Enum e in Tree.Types.Enums)
716                                         e.Emit ();
717                         }
718
719                         if (type_container_resolve_order != null) {
720                                 foreach (TypeContainer tc in type_container_resolve_order)
721                                         tc.EmitType ();
722                         }
723                         
724                         if (Tree.Types.Delegates != null) {
725                                 foreach (Delegate d in Tree.Types.Delegates)
726                                         d.Emit ();
727                         }                       
728                         //
729                         // Run any hooks after all the types have been defined.
730                         // This is used to create nested auxiliary classes for example
731                         //
732
733                         if (EmitCodeHook != null)
734                                 EmitCodeHook ();
735                 }
736                 
737                 //
738                 // Public Field, used to track which method is the public entry
739                 // point.
740                 //
741                 static public MethodInfo EntryPoint;
742
743                 //
744                 // Track the location of the entry point.
745                 //
746                 static public Location EntryPointLocation;
747
748                 //
749                 // These are used to generate unique names on the structs and fields.
750                 //
751                 static int field_count;
752                 
753                 //
754                 // Makes an initialized struct, returns the field builder that
755                 // references the data.  Thanks go to Sergey Chaban for researching
756                 // how to do this.  And coming up with a shorter mechanism than I
757                 // was able to figure out.
758                 //
759                 // This works but makes an implicit public struct $ArrayType$SIZE and
760                 // makes the fields point to it.  We could get more control if we did
761                 // use instead:
762                 //
763                 // 1. DefineNestedType on the impl_details_class with our struct.
764                 //
765                 // 2. Define the field on the impl_details_class
766                 //
767                 static public FieldBuilder MakeStaticData (byte [] data)
768                 {
769                         FieldBuilder fb;
770                         
771                         if (impl_details_class == null){
772                                 impl_details_class = CodeGen.Module.Builder.DefineType (
773                                         "<PrivateImplementationDetails>",
774                                         TypeAttributes.NotPublic,
775                                         TypeManager.object_type);
776                                 
777                                 RegisterHelperClass (impl_details_class);
778                         }
779
780                         fb = impl_details_class.DefineInitializedData (
781                                 "$$field-" + (field_count++), data,
782                                 FieldAttributes.Static | FieldAttributes.Assembly);
783                         
784                         return fb;
785                 }
786         }
787 }
788               
789