Add pointers in each file to the other, since they contain respectively

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runtime/mercury_type_info.h:
runtime/mercury_typeclass_info.h:
	Add pointers in each file to the other, since they contain respectively
	the current and prospective new designs for the implementation of
	typeclass_infos.

	Add a XXX for missing documentation.

runtime/mercury_type_info.h

@@ -2,24 +2,28 @@
 ** vim: ts=4 sw=4 expandtab
 */
 /*
-** Copyright (C) 1995-2007, 2009, 2011 The University of Melbourne.
+** Copyright (C) 1995-2007, 2009, 2011-2012 The University of Melbourne.
 ** This file may only be copied under the terms of the GNU Library General
 ** Public License - see the file COPYING.LIB in the Mercury distribution.
 */
 
 /*
-** mercury_type_info.h -
-**  Definitions for accessing the type_infos, type_layouts, and
-**  type_functors tables generated by the Mercury compiler.
+** Definitions of the types defining the type_ctor_infos, type_infos,
+** pseudo_type_infos, base_typeclass_infos and typeclass_infos generated
+** by the Mercury compiler, together with the macros and functions for
+** manipulating them.
 **
-**  Changes to the structures of type_infos and pseudo_type_infos
-**  may also require changes in:
+** There is a newer and better design for representing typeclass_infos
+** in mercury_typeclass_info.h, but it is not used yet.
+**
+** Changes to the structures of type_infos and pseudo_type_infos
+** may also require changes in:
 **
 **      compiler/polymorphism.m
 **      compiler/pseudo_type_info.m
 **      compiler/higher_order.m
 **
-**  Changes to the structures of type_ctor_infos may require changes in:
+** Changes to the structures of type_ctor_infos may require changes in:
 **
 **      compiler/type_ctor_info.m
 **      compiler/rtti.m
@@ -37,8 +41,8 @@
 **          (for updating the hand-written RTTI
 **          structures)
 **
-**  Both kinds of changes will of course also require changes to the code
-**  that traverses type_infos and type_ctor_infos:
+** Both kinds of changes will of course also require changes to the code
+** that traverses type_infos and type_ctor_infos:
 **
 **      runtime/mercury_deep_copy_body.h
 **      runtime/mercury_table_type_body.h
@@ -47,6 +51,9 @@
 **
 **      java/ *.java
 **          (for updating the Java backend RTTI structures)
+**
+** XXX Document what files changes may be required in after changes to the
+** structures of base_typeclass_infos and typeclass_infos.
 */
 
 #ifndef MERCURY_TYPE_INFO_H

runtime/mercury_typeclass_info.h

@@ -2,15 +2,17 @@
 ** vim: ts=4 sw=4 expandtab
 */
 /*
-** Copyright (C) 2002-2005, 2007 The University of Melbourne.
+** Copyright (C) 2002-2005, 2007, 2012 The University of Melbourne.
 ** This file may only be copied under the terms of the GNU Library General
 ** Public License - see the file COPYING.LIB in the Mercury distribution.
 */
 
 /*
 ** This file contains design for a new runtime representation of typeclass
-** information. It is not used yet. The mail that introduced this file
-** follows.
+** information. It is not used yet; the design we DO use is implemented
+** in mercury_type_info.h.
+**
+** The mail that introduced this file follows.
 */
 
 /*
@@ -50,7 +52,7 @@ the growth is mostly in statically allocated data structures. Also, the new
 design is in type-safe C, for ease of debugging its implementation. There
 should be a type-safe Mercury version of it as well, for future use in the
 Java and IL backends. The reason why there isn't one yet is that some these
-structures must contain references to polymporphic procedures, since methods
+structures must contain references to polymorphic procedures, since methods
 may be polymorphic. Mercury doesn't (yet) support polymorphic procedures,
 even if (as here) only the compiler can create them.