PATCH: don't corrupt cv_type chain

[Jim Blandy <jimb@redhat.com>]

This fixes the second failure in hang.exp.

2002-05-03  Jim Blandy  <jimb@redhat.com>

	* stabsread.c (cleanup_undefined_types): Use replace_type, not memcpy.
	(read_type): Doc fix.
	* gdbtypes.c (replace_type): Doc fix.

Index: gdb/gdbtypes.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbtypes.c,v
retrieving revision 1.44
diff -c -r1.44 gdbtypes.c
*** gdb/gdbtypes.c	26 Apr 2002 20:08:18 -0000	1.44
--- gdb/gdbtypes.c	4 May 2002 00:18:05 -0000
***************
*** 521,530 ****
  
  /* Replace the contents of ntype with the type *type.
  
!    This function should not be necessary, but is due to quirks in the stabs
!    reader.  This should go away.  It does not handle the replacement type
!    being cv-qualified; it could be easily fixed to, but it should go away,
!    remember?  */
  void
  replace_type (struct type *ntype, struct type *type)
  {
--- 521,530 ----
  
  /* Replace the contents of ntype with the type *type.
  
!    When building recursive types, it is necessary to update a type's
!    definition after people already have references to it.  The C
!    language's concept of an `incomplete type' is an acknowledgement of
!    this.  */
  void
  replace_type (struct type *ntype, struct type *type)
  {
Index: gdb/stabsread.c
===================================================================
RCS file: /cvs/src/src/gdb/stabsread.c,v
retrieving revision 1.31
diff -c -r1.31 stabsread.c
*** gdb/stabsread.c	4 May 2002 00:02:50 -0000	1.31
--- gdb/stabsread.c	4 May 2002 00:18:08 -0000
***************
*** 2537,2543 ****
  	       the related problems with unnecessarily stubbed types;
  	       someone motivated should attempt to clean up the issue
  	       here as well.  Once a type pointed to has been created it
! 	       should not be modified.  */
  	    replace_type (type, xtype);
  	    TYPE_NAME (type) = NULL;
  	    TYPE_TAG_NAME (type) = NULL;
--- 2537,2560 ----
  	       the related problems with unnecessarily stubbed types;
  	       someone motivated should attempt to clean up the issue
  	       here as well.  Once a type pointed to has been created it
! 	       should not be modified.
! 
!                Well, it's not *absolutely* wrong.  Constructing recursive
!                types (trees, linked lists) necessarily entails modifying
!                types after creating them.  Constructing any loop structure
!                entails side effects.  The Dwarf 2 reader does handle this
!                more gracefully (it never constructs more than once
!                instance of a type object, so it doesn't have to copy type
!                objects wholesale), but it still mutates type objects after
!                other folks have references to them.
! 
!                Keep in mind that this circularity/mutation issue shows up
!                at the source language level, too: C's "incomplete types",
!                for example.  So the proper cleanup, I think, would be to
!                limit GDB's type smashing to match exactly those required
!                by the source language.  So GDB could have a
!                "complete_this_type" function, but never create unnecessary
!                copies of a type otherwise.  */
  	    replace_type (type, xtype);
  	    TYPE_NAME (type) = NULL;
  	    TYPE_TAG_NAME (type) = NULL;
***************
*** 5122,5131 ****
  			    && (TYPE_CODE (SYMBOL_TYPE (sym)) ==
  				TYPE_CODE (*type))
  			    && STREQ (SYMBOL_NAME (sym), typename))
! 			  {
! 			    memcpy (*type, SYMBOL_TYPE (sym),
! 				    sizeof (struct type));
! 			  }
  		      }
  		  }
  	      }
--- 5139,5145 ----
  			    && (TYPE_CODE (SYMBOL_TYPE (sym)) ==
  				TYPE_CODE (*type))
  			    && STREQ (SYMBOL_NAME (sym), typename))
!                           replace_type (*type, SYMBOL_TYPE (sym));
  		      }
  		  }
  	      }