* Makefile: Run "make run-test" or "make run-test-ondotnet" to
[mono.git] / mcs / mcs / 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
11 using System;
12 using System.Collections;
13 using System.Reflection;
14 using System.Reflection.Emit;
15 using System.Diagnostics;
16
17 namespace Mono.CSharp {
18
19         public enum LanguageVersion
20         {
21                 Default = 0,
22                 ISO_1   = 1
23         }
24
25         public class RootContext {
26
27                 //
28                 // Contains the parsed tree
29                 //
30                 static Tree tree;
31
32                 //
33                 // This hashtable contains all of the #definitions across the source code
34                 // it is used by the ConditionalAttribute handler.
35                 //
36                 public static Hashtable AllDefines = new Hashtable ();
37                 
38                 //
39                 // Whether we are being linked against the standard libraries.
40                 // This is only used to tell whether `System.Object' should
41                 // have a parent or not.
42                 //
43                 public static bool StdLib = true;
44
45                 //
46                 // This keeps track of the order in which classes were defined
47                 // so that we can poulate them in that order.
48                 //
49                 // Order is important, because we need to be able to tell by
50                 // examining the parent's list of methods which ones are virtual
51                 // or abstract as well as the parent names (to implement new, 
52                 // override).
53                 //
54                 static ArrayList type_container_resolve_order;
55                 static ArrayList attribute_types;
56
57                 //
58                 // Holds a reference to the Private Implementation Details
59                 // class.
60                 //
61                 static ArrayList helper_classes;
62                 
63                 static TypeBuilder impl_details_class;
64
65                 public static int WarningLevel = 2;
66                 
67                 public static Target Target = Target.Exe;
68                 public static string TargetExt = ".exe";
69
70                 public static bool VerifyClsCompliance = true;
71
72                 public static LanguageVersion Version = LanguageVersion.Default;
73
74                 //
75                 // We keep strongname related info here because
76                 // it's also used as complier options from CSC 8.x
77                 //
78                 public static string StrongNameKeyFile;
79                 public static string StrongNameKeyContainer;
80                 public static bool StrongNameDelaySign = false;
81
82                 //
83                 // Constructor
84                 //
85                 static RootContext ()
86                 {
87                         tree = new Tree ();
88                         type_container_resolve_order = new ArrayList ();
89                 }
90                 
91                 public static bool NeedsEntryPoint {
92                         get {
93                                 return RootContext.Target == Target.Exe || RootContext.Target == Target.WinExe;
94                         }
95                 }
96
97                 static public Tree Tree {
98                         get {
99                                 return tree;
100                         }
101                 }
102
103                 static public string MainClass;
104                 
105                 public static void RegisterOrder (TypeContainer tc)
106                 {
107                         type_container_resolve_order.Add (tc);
108                 }
109
110                 public static void RegisterAttribute (TypeContainer tc)
111                 {
112                         if (attribute_types == null)
113                                 attribute_types = new ArrayList ();
114                         
115                         attribute_types.Add (tc);
116                 }
117                 
118                 // 
119                 // The default compiler checked state
120                 //
121                 static public bool Checked = false;
122
123                 //
124                 // Whether to allow Unsafe code
125                 //
126                 static public bool Unsafe = false;
127                 
128                 static string MakeFQN (string nsn, string name)
129                 {
130                         if (nsn == "")
131                                 return name;
132                         return String.Concat (nsn, ".", name);
133                 }
134
135                 // <remarks>
136                 //   This function is used to resolve the hierarchy tree.
137                 //   It processes interfaces, structs and classes in that order.
138                 //
139                 //   It creates the TypeBuilder's as it processes the user defined
140                 //   types.  
141                 // </remarks>
142                 static public void ResolveTree ()
143                 {
144                         //
145                         // Process the attribute types separately and before anything else
146                         //
147                         if (attribute_types != null)
148                                 foreach (TypeContainer tc in attribute_types)
149                                         tc.DefineType ();
150                         
151                         //
152                         // Interfaces are processed next, as classes and
153                         // structs might inherit from an object or implement
154                         // a set of interfaces, we need to be able to tell
155                         // them appart by just using the TypeManager.
156                         //
157                         TypeContainer root = Tree.Types;
158
159                         ArrayList ifaces = root.Interfaces;
160                         if (ifaces != null){
161                                 foreach (Interface i in ifaces) 
162                                         i.DefineType ();
163                         }
164
165                         foreach (TypeContainer tc in root.Types)
166                                 tc.DefineType ();
167
168                         if (root.Delegates != null)
169                                 foreach (Delegate d in root.Delegates) 
170                                         d.DefineType ();
171
172                         if (root.Enums != null)
173                                 foreach (Enum e in root.Enums)
174                                         e.DefineType ();
175                 }
176
177                 static void Error_TypeConflict (string name, Location loc)
178                 {
179                         Report.Error (
180                                 520, loc, "`" + name + "' conflicts with a predefined type");
181                 }
182
183                 static void Error_TypeConflict (string name)
184                 {
185                         Report.Error (
186                                 520, "`" + name + "' conflicts with a predefined type");
187                 }
188
189                 //
190                 // Resolves a single class during the corlib bootstrap process
191                 //
192                 static TypeBuilder BootstrapCorlib_ResolveClass (TypeContainer root, string name)
193                 {
194                         object o = root.GetDefinition (name);
195                         if (o == null){
196                                 Report.Error (518, "The predefined type `" + name + "' is not defined");
197                                 return null;
198                         }
199
200                         if (!(o is Class)){
201                                 if (o is DeclSpace){
202                                         DeclSpace d = (DeclSpace) o;
203
204                                         Error_TypeConflict (name, d.Location);
205                                 } else
206                                         Error_TypeConflict (name);
207
208                                 return null;
209                         }
210
211                         return ((DeclSpace) o).DefineType ();
212                 }
213
214                 //
215                 // Resolves a struct during the corlib bootstrap process
216                 //
217                 static void BootstrapCorlib_ResolveStruct (TypeContainer root, string name)
218                 {
219                         object o = root.GetDefinition (name);
220                         if (o == null){
221                                 Report.Error (518, "The predefined type `" + name + "' is not defined");
222                                 return;
223                         }
224
225                         if (!(o is Struct)){
226                                 if (o is DeclSpace){
227                                         DeclSpace d = (DeclSpace) o;
228
229                                         Error_TypeConflict (name, d.Location);
230                                 } else
231                                         Error_TypeConflict (name);
232
233                                 return;
234                         }
235
236                         ((DeclSpace) o).DefineType ();
237                 }
238
239                 //
240                 // Resolves a struct during the corlib bootstrap process
241                 //
242                 static void BootstrapCorlib_ResolveInterface (TypeContainer root, string name)
243                 {
244                         object o = root.GetDefinition (name);
245                         if (o == null){
246                                 Report.Error (518, "The predefined type `" + name + "' is not defined");
247                                 return;
248                         }
249
250                         if (!(o is Interface)){
251                                 if (o is DeclSpace){
252                                         DeclSpace d = (DeclSpace) o;
253
254                                         Error_TypeConflict (name, d.Location);
255                                 } else
256                                         Error_TypeConflict (name);
257
258                                 return;
259                         }
260
261                         ((DeclSpace) o).DefineType ();
262                 }
263
264                 //
265                 // Resolves a delegate during the corlib bootstrap process
266                 //
267                 static void BootstrapCorlib_ResolveDelegate (TypeContainer root, string name)
268                 {
269                         object o = root.GetDefinition (name);
270                         if (o == null){
271                                 Report.Error (518, "The predefined type `" + name + "' is not defined");
272                                 Environment.Exit (1);
273                         }
274
275                         if (!(o is Delegate)){
276                                 Error_TypeConflict (name);
277                                 return;
278                         }
279
280                         ((DeclSpace) o).DefineType ();
281                 }
282                 
283
284                 /// <summary>
285                 ///    Resolves the core types in the compiler when compiling with --nostdlib
286                 /// </summary>
287                 static public void ResolveCore ()
288                 {
289                         TypeContainer root = Tree.Types;
290
291                         TypeManager.object_type = BootstrapCorlib_ResolveClass (root, "System.Object");
292                         TypeManager.value_type = BootstrapCorlib_ResolveClass (root, "System.ValueType");
293                         TypeManager.attribute_type = BootstrapCorlib_ResolveClass (root, "System.Attribute");
294                         
295                         string [] interfaces_first_stage = {
296                                 "System.IComparable", "System.ICloneable",
297                                 "System.IConvertible",
298                                 
299                                 "System.Collections.IEnumerable",
300                                 "System.Collections.ICollection",
301                                 "System.Collections.IEnumerator",
302                                 "System.Collections.IList", 
303                                 "System.IAsyncResult",
304                                 "System.IDisposable",
305                                 
306                                 "System.Runtime.Serialization.ISerializable",
307
308                                 "System.Reflection.IReflect",
309                                 "System.Reflection.ICustomAttributeProvider"
310                         };
311
312                         foreach (string iname in interfaces_first_stage)
313                                 BootstrapCorlib_ResolveInterface (root, iname);
314
315                         //
316                         // These are the base value types
317                         //
318                         string [] structs_first_stage = {
319                                 "System.Byte",    "System.SByte",
320                                 "System.Int16",   "System.UInt16",
321                                 "System.Int32",   "System.UInt32",
322                                 "System.Int64",   "System.UInt64",
323                         };
324
325                         foreach (string cname in structs_first_stage)
326                                 BootstrapCorlib_ResolveStruct (root, cname);
327
328                         //
329                         // Now, we can load the enumerations, after this point,
330                         // we can use enums.
331                         //
332                         TypeManager.InitEnumUnderlyingTypes ();
333
334                         string [] structs_second_stage = {
335                                 "System.Single",  "System.Double",
336                                 "System.Char",    "System.Boolean",
337                                 "System.Decimal", "System.Void",
338                                 "System.RuntimeFieldHandle",
339                                 "System.RuntimeArgumentHandle",
340                                 "System.RuntimeTypeHandle",
341                                 "System.IntPtr",
342                                 "System.TypedReference",
343                                 "System.ArgIterator"
344                         };
345                         
346                         foreach (string cname in structs_second_stage)
347                                 BootstrapCorlib_ResolveStruct (root, cname);
348                         
349                         //
350                         // These are classes that depends on the core interfaces
351                         //
352                         string [] classes_second_stage = {
353                                 "System.Reflection.MemberInfo",
354                                 "System.Type",
355                                 "System.Exception",
356
357                                 //
358                                 // These are not really important in the order, but they
359                                 // are used by the compiler later on (typemanager/CoreLookupType-d)
360                                 //
361                                 "System.Runtime.CompilerServices.RuntimeHelpers",
362                                 "System.Reflection.DefaultMemberAttribute",
363                                 "System.Threading.Monitor",
364                                 
365                                 "System.AttributeUsageAttribute",
366                                 "System.Runtime.InteropServices.DllImportAttribute",
367                                 "System.Runtime.CompilerServices.MethodImplAttribute",
368                                 "System.Runtime.InteropServices.MarshalAsAttribute",
369                                 "System.Diagnostics.ConditionalAttribute",
370                                 "System.ObsoleteAttribute",
371                                 "System.ParamArrayAttribute",
372                                 "System.CLSCompliantAttribute",
373                                 "System.Security.UnverifiableCodeAttribute",
374                                 "System.Security.Permissions.SecurityAttribute",
375                                 "System.Runtime.CompilerServices.IndexerNameAttribute",
376                                 "System.Runtime.InteropServices.InAttribute",
377                                 "System.Runtime.InteropServices.StructLayoutAttribute",
378                                 "System.Runtime.InteropServices.FieldOffsetAttribute",
379                                 "System.InvalidOperationException",
380                                 "System.NotSupportedException",
381                                 "System.MarshalByRefObject",
382                                 "System.Security.CodeAccessPermission"
383                         };
384
385                         // We must store them here before calling BootstrapCorlib_ResolveDelegate.
386                         TypeManager.string_type = BootstrapCorlib_ResolveClass (root, "System.String");
387                         TypeManager.enum_type = BootstrapCorlib_ResolveClass (root, "System.Enum");
388                         TypeManager.array_type = BootstrapCorlib_ResolveClass (root, "System.Array");
389                         TypeManager.multicast_delegate_type = BootstrapCorlib_ResolveClass (root, "System.MulticastDelegate");
390                         TypeManager.delegate_type = BootstrapCorlib_ResolveClass (root, "System.Delegate");
391                         
392                         foreach (string cname in classes_second_stage)
393                                 BootstrapCorlib_ResolveClass (root, cname);
394
395                         BootstrapCorlib_ResolveDelegate (root, "System.AsyncCallback");
396                 }
397                         
398                 // <summary>
399                 //   Closes all open types
400                 // </summary>
401                 //
402                 // <remarks>
403                 //   We usually use TypeBuilder types.  When we are done
404                 //   creating the type (which will happen after we have added
405                 //   methods, fields, etc) we need to "Define" them before we
406                 //   can save the Assembly
407                 // </remarks>
408                 static public void CloseTypes ()
409                 {
410                         TypeContainer root = Tree.Types;
411                         
412                         if (root.Enums != null)
413                                 foreach (Enum en in root.Enums)
414                                         en.CloseType ();
415
416                         if (attribute_types != null)
417                                 foreach (TypeContainer tc in attribute_types)
418                                         tc.CloseType ();
419                         
420                         //
421                         // We do this in two passes, first we close the structs,
422                         // then the classes, because it seems the code needs it this
423                         // way.  If this is really what is going on, we should probably
424                         // make sure that we define the structs in order as well.
425                         //
426                         foreach (TypeContainer tc in type_container_resolve_order){
427                                 if (tc.Kind == Kind.Struct && tc.Parent == tree.Types){
428                                         tc.CloseType ();
429                                 }
430                         }
431
432                         foreach (TypeContainer tc in type_container_resolve_order){
433                                 if (!(tc.Kind == Kind.Struct && tc.Parent == tree.Types))
434                                         tc.CloseType ();                                        
435                         }
436                         
437                         if (root.Delegates != null)
438                                 foreach (Delegate d in root.Delegates)
439                                         d.CloseType ();
440
441
442                         //
443                         // If we have a <PrivateImplementationDetails> class, close it
444                         //
445                         if (helper_classes != null){
446                                 foreach (TypeBuilder type_builder in helper_classes)
447                                         type_builder.CreateType ();
448                         }
449                         
450                         attribute_types = null;
451                         type_container_resolve_order = null;
452                         helper_classes = null;
453                         //tree = null;
454                         TypeManager.CleanUp ();
455                 }
456
457                 /// <summary>
458                 ///   Used to register classes that need to be closed after all the
459                 ///   user defined classes
460                 /// </summary>
461                 public static void RegisterHelperClass (TypeBuilder helper_class)
462                 {
463                         if (helper_classes == null)
464                                 helper_classes = new ArrayList ();
465                         helper_classes.Add (helper_class);
466                 }
467                 
468                 //
469                 // This idea is from Felix Arrese-Igor
470                 //
471                 // Returns : the implicit parent of a composite namespace string
472                 //   eg. Implicit parent of A.B is A
473                 //
474                 static public string ImplicitParent (string ns)
475                 {
476                         int i = ns.LastIndexOf ('.');
477                         if (i < 0)
478                                 return null;
479                         
480                         return ns.Substring (0, i);
481                 }
482
483                 static Type NamespaceLookup (DeclSpace ds, string name, Location loc)
484                 {
485                         //
486                         // Try in the current namespace and all its implicit parents
487                         //
488                         for (NamespaceEntry ns = ds.NamespaceEntry; ns != null; ns = ns.ImplicitParent) {
489                                 object result = ns.Lookup (ds, name, false, loc);
490                                 if (result == null)
491                                         continue;
492
493                                 if (result is Type)
494                                         return (Type) result;
495
496                                 return null;
497                         }
498
499                         return null;
500                 }
501                 
502                 //
503                 // Public function used to locate types, this can only
504                 // be used after the ResolveTree function has been invoked.
505                 //
506                 // Returns: Type or null if they type can not be found.
507                 //
508                 // Come to think of it, this should be a DeclSpace
509                 //
510                 static public Type LookupType (DeclSpace ds, string name, bool silent, Location loc)
511                 {
512                         Type t;
513
514                         if (ds.Cache.Contains (name)) {
515                                 t = (Type) ds.Cache [name];
516                         } else {
517                                 //
518                                 // For the case the type we are looking for is nested within this one
519                                 // or is in any base class
520                                 //
521                                 DeclSpace containing_ds = ds;
522                                 while (containing_ds != null){
523                                         
524                                         // if the member cache has been created, lets use it.
525                                         // the member cache is MUCH faster.
526                                         if (containing_ds.MemberCache != null) {
527                                                 t = containing_ds.MemberCache.FindNestedType (name);
528                                                 if (t == null) {
529                                                         containing_ds = containing_ds.Parent;
530                                                         continue;
531                                                 }
532                                                 
533                                                 ds.Cache [name] = t;
534                                                 return t;
535                                         }
536                                         
537                                         // no member cache. Do it the hard way -- reflection
538                                         Type current_type = containing_ds.TypeBuilder;
539                                         
540                                         while (current_type != null &&
541                                                current_type != TypeManager.object_type) {
542                                                 //
543                                                 // nested class
544                                                 //
545                                                 t = TypeManager.LookupType (current_type.FullName + "." + name);
546                                                 if (t != null){
547                                                         ds.Cache [name] = t;
548                                                         return t;
549                                                 }
550                                                 
551                                                 current_type = current_type.BaseType;
552                                         }
553                                         
554                                         containing_ds = containing_ds.Parent;
555                                 }
556                                 
557                                 t = NamespaceLookup (ds, name, loc);
558                                 if (!silent)
559                                         ds.Cache [name] = t;
560                         }
561
562                         if (t == null && !silent)
563                                 Report.Error (246, loc, "Cannot find type `"+name+"'");
564                         
565                         return t;
566                 }
567
568                 // <summary>
569                 //   This is the silent version of LookupType, you can use this
570                 //   to `probe' for a type
571                 // </summary>
572                 static public Type LookupType (TypeContainer tc, string name, Location loc)
573                 {
574                         return LookupType (tc, name, true, loc);
575                 }
576
577                 static void Report1530 (Location loc)
578                 {
579                         Report.Error (1530, loc, "Keyword new not allowed for namespace elements");
580                 }
581                 
582                 static public void PopulateCoreType (TypeContainer root, string name)
583                 {
584                         DeclSpace ds = (DeclSpace) root.GetDefinition (name);
585
586                         ds.DefineMembers (root);
587                         ds.Define ();
588                 }
589                 
590                 static public void BootCorlib_PopulateCoreTypes ()
591                 {
592                         TypeContainer root = tree.Types;
593
594                         PopulateCoreType (root, "System.Object");
595                         PopulateCoreType (root, "System.ValueType");
596                         PopulateCoreType (root, "System.Attribute");
597                 }
598                 
599                 // <summary>
600                 //   Populates the structs and classes with fields and methods
601                 // </summary>
602                 //
603                 // This is invoked after all interfaces, structs and classes
604                 // have been defined through `ResolveTree' 
605                 static public void PopulateTypes ()
606                 {
607                         TypeContainer root = Tree.Types;
608
609                         if (attribute_types != null)
610                                 foreach (TypeContainer tc in attribute_types)
611                                         tc.DefineMembers (root);
612                         
613                         if (type_container_resolve_order != null){
614                                 if (RootContext.StdLib){
615                                         foreach (TypeContainer tc in type_container_resolve_order)
616                                                 tc.DefineMembers (root);
617                                 } else {
618                                         foreach (TypeContainer tc in type_container_resolve_order) {
619                                                 // When compiling corlib, these types have already been
620                                                 // populated from BootCorlib_PopulateCoreTypes ().
621                                                 if (((tc.Name == "System.Object") ||
622                                                      (tc.Name == "System.Attribute") ||
623                                                      (tc.Name == "System.ValueType")))
624                                                 continue;
625
626                                                 tc.DefineMembers (root);
627                                         }
628                                 } 
629                         }
630
631                         ArrayList delegates = root.Delegates;
632                         if (delegates != null){
633                                 foreach (Delegate d in delegates)
634                                         if ((d.ModFlags & Modifiers.NEW) == 0)
635                                                 d.DefineMembers (root);
636                                         else
637                                                 Report1530 (d.Location);
638                         }
639
640                         ArrayList enums = root.Enums;
641                         if (enums != null){
642                                 foreach (Enum en in enums)
643                                         if ((en.ModFlags & Modifiers.NEW) == 0)
644                                                 en.DefineMembers (root);
645                                         else
646                                                 Report1530 (en.Location);
647                         }
648
649                         //
650                         // Check for cycles in the struct layout
651                         //
652                         if (type_container_resolve_order != null){
653                                 Hashtable seen = new Hashtable ();
654                                 foreach (TypeContainer tc in type_container_resolve_order)
655                                         TypeManager.CheckStructCycles (tc, seen);
656                         }
657                 }
658
659                 //
660                 // A generic hook delegate
661                 //
662                 public delegate void Hook ();
663
664                 //
665                 // A hook invoked when the code has been generated.
666                 //
667                 public static event Hook EmitCodeHook;
668
669                 //
670                 // DefineTypes is used to fill in the members of each type.
671                 //
672                 static public void DefineTypes ()
673                 {
674                         TypeContainer root = Tree.Types;
675
676                         if (attribute_types != null)
677                                 foreach (TypeContainer tc in attribute_types)
678                                         tc.Define ();
679                         
680                         if (type_container_resolve_order != null){
681                                 foreach (TypeContainer tc in type_container_resolve_order) {
682                                         // When compiling corlib, these types have already been
683                                         // populated from BootCorlib_PopulateCoreTypes ().
684                                         if (!RootContext.StdLib &&
685                                             ((tc.Name == "System.Object") ||
686                                              (tc.Name == "System.Attribute") ||
687                                              (tc.Name == "System.ValueType")))
688                                                 continue;
689
690                                         if ((tc.ModFlags & Modifiers.NEW) == 0)
691                                                 tc.Define ();
692                                 }
693                         }
694
695                         ArrayList delegates = root.Delegates;
696                         if (delegates != null){
697                                 foreach (Delegate d in delegates)
698                                         if ((d.ModFlags & Modifiers.NEW) == 0)
699                                                 d.Define ();
700                         }
701
702                         ArrayList enums = root.Enums;
703                         if (enums != null){
704                                 foreach (Enum en in enums)
705                                         if ((en.ModFlags & Modifiers.NEW) == 0)
706                                                 en.Define ();
707                         }
708                 }
709
710                 static public void EmitCode ()
711                 {
712                         if (attribute_types != null)
713                                 foreach (TypeContainer tc in attribute_types)
714                                         tc.EmitType ();
715
716                         CodeGen.Assembly.Emit (Tree.Types);
717                         CodeGen.Module.Emit (Tree.Types);
718                         
719                         if (Tree.Types.Enums != null) {
720                                 foreach (Enum e in Tree.Types.Enums)
721                                         e.Emit ();
722                         }
723
724                         if (type_container_resolve_order != null) {
725                                 foreach (TypeContainer tc in type_container_resolve_order)
726                                         tc.EmitType ();
727                         }
728                         
729                         if (Tree.Types.Delegates != null) {
730                                 foreach (Delegate d in Tree.Types.Delegates)
731                                         d.Emit ();
732                         }                       
733                         //
734                         // Run any hooks after all the types have been defined.
735                         // This is used to create nested auxiliary classes for example
736                         //
737
738                         if (EmitCodeHook != null)
739                                 EmitCodeHook ();
740                 }
741                 
742                 //
743                 // Public Field, used to track which method is the public entry
744                 // point.
745                 //
746                 static public MethodInfo EntryPoint;
747
748                 //
749                 // Track the location of the entry point.
750                 //
751                 static public Location EntryPointLocation;
752
753                 //
754                 // These are used to generate unique names on the structs and fields.
755                 //
756                 static int field_count;
757                 
758                 //
759                 // Makes an initialized struct, returns the field builder that
760                 // references the data.  Thanks go to Sergey Chaban for researching
761                 // how to do this.  And coming up with a shorter mechanism than I
762                 // was able to figure out.
763                 //
764                 // This works but makes an implicit public struct $ArrayType$SIZE and
765                 // makes the fields point to it.  We could get more control if we did
766                 // use instead:
767                 //
768                 // 1. DefineNestedType on the impl_details_class with our struct.
769                 //
770                 // 2. Define the field on the impl_details_class
771                 //
772                 static public FieldBuilder MakeStaticData (byte [] data)
773                 {
774                         FieldBuilder fb;
775                         
776                         if (impl_details_class == null){
777                                 impl_details_class = CodeGen.Module.Builder.DefineType (
778                                         "<PrivateImplementationDetails>",
779                                         TypeAttributes.NotPublic,
780                                         TypeManager.object_type);
781                                 
782                                 RegisterHelperClass (impl_details_class);
783                         }
784
785                         fb = impl_details_class.DefineInitializedData (
786                                 "$$field-" + (field_count++), data,
787                                 FieldAttributes.Static | FieldAttributes.Assembly);
788                         
789                         return fb;
790                 }
791         }
792 }
793               
794