Re: [RFA/stabs] Fix gdb/280 infinite loop in userdef.exp

[Jim Blandy <jimb at zwingli dot cygnus dot com>]

Approved.  Could you also put a comment in the stabs reader saying
that this isn't really a kosher way to construct types?

Daniel Jacobowitz <drow@mvista.com> writes:

> Another problem exposed by the way the stabs reader handles types.  It does
> '*type = *xtype' at one point, which dies horribly for qualified types (and
> messes up pointer types, too...).  I don't immediately see a way to get rid
> of that line, so I made an interface to do the copy correctly.
> 
> For reference, that appears to be the only place in GDB this is actually
> done.  Other readers must handle forward-referenced types somehow...
> 
> Without this patch we enter an infinite loop because the cv-chain is
> corrupted.
> 
> OK to commit?
> 
> -- 
> Daniel Jacobowitz                           Carnegie Mellon University
> MontaVista Software                         Debian GNU/Linux Developer
> 
> 2002-02-01  Daniel Jacobowitz  <drow@mvista.com>
> 
> 	PR gdb/280
> 	* gdbtypes.c (replace_type): New function.
> 	* gdbtypes.h (replace_type): Add prototype.
> 	* stabsread.c (read_type): Use replace_type.
> 
> Index: gdbtypes.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/gdbtypes.c,v
> retrieving revision 1.38
> diff -u -p -r1.38 gdbtypes.c
> --- gdbtypes.c	2002/01/22 19:57:40	1.38
> +++ gdbtypes.c	2002/02/01 23:48:45
> @@ -519,6 +519,32 @@ finish_cv_type (struct type *type)
>      }
>  }
>  
> +/* 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)
> +{
> +  struct type *cv_chain, *as_chain, *ptr, *ref;
> +
> +  cv_chain = TYPE_CV_TYPE (ntype);
> +  as_chain = TYPE_AS_TYPE (ntype);
> +  ptr = TYPE_POINTER_TYPE (ntype);
> +  ref = TYPE_REFERENCE_TYPE (ntype);
> +
> +  *ntype = *type;
> +
> +  TYPE_POINTER_TYPE (ntype) = ptr;
> +  TYPE_REFERENCE_TYPE (ntype) = ref;
> +  TYPE_CV_TYPE (ntype) = cv_chain;
> +  TYPE_AS_TYPE (ntype) = as_chain;
> +
> +  finish_cv_type (ntype);
> +}
> +
>  /* Implement direct support for MEMBER_TYPE in GNU C++.
>     May need to construct such a type if this is the first use.
>     The TYPE is the type of the member.  The DOMAIN is the type
> Index: gdbtypes.h
> ===================================================================
> RCS file: /cvs/src/src/gdb/gdbtypes.h,v
> retrieving revision 1.25
> diff -u -p -r1.25 gdbtypes.h
> --- gdbtypes.h	2002/01/20 19:42:04	1.25
> +++ gdbtypes.h	2002/02/01 23:48:45
> @@ -1062,6 +1062,8 @@ extern struct type *make_cv_type (int, i
>  
>  extern void finish_cv_type (struct type *);
>  
> +extern void replace_type (struct type *, struct type *);
> +
>  extern int address_space_name_to_int (char *);
>  
>  extern char *address_space_int_to_name (int);
> Index: stabsread.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/stabsread.c,v
> retrieving revision 1.23
> diff -u -p -r1.23 stabsread.c
> --- stabsread.c	2002/01/20 19:12:23	1.23
> +++ stabsread.c	2002/02/01 23:48:46
> @@ -2531,7 +2531,7 @@ again:
>  	  }
>  	else if (type_size >= 0 || is_string)
>  	  {
> -	    *type = *xtype;
> +	    replace_type (type, xtype);
>  	    TYPE_NAME (type) = NULL;
>  	    TYPE_TAG_NAME (type) = NULL;
>  	  }