Re: c++/1553: gdb confused in namespace / subclass

[Dirk-Jan Jongeneel <dirkjjn at cobalt dot et dot tudelft dot nl>]

The following reply was made to PR c++/1553; it has been noted by GNATS.

From: Dirk-Jan Jongeneel <dirkjjn@cobalt.et.tudelft.nl>
To: David Carlton <carlton@kealia.com>
Cc: gdb-gnats@sources.redhat.com
Subject: Re: c++/1553: gdb confused in namespace / subclass
Date: Tue, 24 Feb 2004 11:49:42 +0100

 It seems to work very well for me. Wow this is a HUGE improvement in 
 debug experience. Thanks a lot!
 
 The only main problem left with confusion I see is with variables in 
 constructors. It seems to be confused there too or completely missing, 
 but thats likely related to the problem of not being able to stop in 
 constructors. (PR 1281/1091 ?).
 
 Again thanks a lot!
 
 Dirk-Jan Jongeneel
 
 David Carlton wrote:
 > Thanks for the excellent test cases.  This patch seems to work for
 > those cases; can you see if it helps in the other places where you're
 > having problems?
 > 
 > David Carlton
 > carlton@kealia.com
 > 
 > Index: dwarf2read.c
 > ===================================================================
 > RCS file: /cvs/src/src/gdb/dwarf2read.c,v
 > retrieving revision 1.135
 > diff -u -p -r1.135 dwarf2read.c
 > --- dwarf2read.c	21 Feb 2004 02:13:35 -0000	1.135
 > +++ dwarf2read.c	24 Feb 2004 01:29:22 -0000
 > @@ -806,6 +806,8 @@ static void dwarf2_attach_fn_fields_to_t
 >  
 >  static void read_structure_scope (struct die_info *, struct dwarf2_cu *);
 >  
 > +static char *determine_class_name (struct die_info *die, struct dwarf2_cu *cu);
 > +
 >  static void read_common_block (struct die_info *, struct dwarf2_cu *);
 >  
 >  static void read_namespace (struct die_info *die, struct dwarf2_cu *);
 > @@ -3000,13 +3002,8 @@ read_structure_scope (struct die_info *d
 >    struct objfile *objfile = cu->objfile;
 >    struct type *type;
 >    struct attribute *attr;
 > -  const char *name = NULL;
 >    const char *previous_prefix = processing_current_prefix;
 >    struct cleanup *back_to = NULL;
 > -  /* This says whether or not we want to try to update the structure's
 > -     name to include enclosing namespace/class information, if
 > -     any.  */
 > -  int need_to_update_name = 0;
 >  
 >    type = alloc_type (objfile);
 >  
 > @@ -3014,40 +3011,21 @@ read_structure_scope (struct die_info *d
 >    attr = dwarf2_attr (die, DW_AT_name, cu);
 >    if (attr && DW_STRING (attr))
 >      {
 > -      name = DW_STRING (attr);
 > -
 >        if (cu->language == language_cplus)
 >  	{
 > -	  struct die_info *spec_die = die_specification (die, cu);
 > -
 > -	  if (spec_die != NULL)
 > -	    {
 > -	      char *specification_prefix = determine_prefix (spec_die, cu);
 > -	      processing_current_prefix = specification_prefix;
 > -	      back_to = make_cleanup (xfree, specification_prefix);
 > -	    }
 > -	}
 > -
 > -      if (processing_has_namespace_info)
 > -	{
 > -	  /* FIXME: carlton/2003-11-10: This variable exists only for
 > -	     const-correctness reasons.  When I tried to change
 > -	     TYPE_TAG_NAME to be a const char *, I ran into a cascade
 > -	     of changes which would have forced decode_line_1 to take
 > -	     a const char **.  */
 > -	  char *new_prefix = obconcat (&objfile->objfile_obstack,
 > -				       processing_current_prefix,
 > -				       processing_current_prefix[0] == '\0'
 > -				       ? "" : "::",
 > -				       name);
 > -	  TYPE_TAG_NAME (type) = new_prefix;
 > +	  char *new_prefix = determine_class_name (die, cu);
 > +	  TYPE_TAG_NAME (type) = obsavestring (new_prefix,
 > +					       strlen (new_prefix),
 > +					       &objfile->objfile_obstack);
 > +	  back_to = make_cleanup (xfree, new_prefix);
 >  	  processing_current_prefix = new_prefix;
 >  	}
 >        else
 >  	{
 > +	  const char *name = DW_STRING (attr);
 > +
 >  	  TYPE_TAG_NAME (type) = obsavestring (name, strlen (name),
 >  					       &objfile->objfile_obstack);
 > -	  need_to_update_name = (cu->language == language_cplus);
 >  	}
 >      }
 >  
 > @@ -3108,41 +3086,6 @@ read_structure_scope (struct die_info *d
 >  	      /* C++ member function. */
 >  	      process_die (child_die, cu);
 >  	      dwarf2_add_member_fn (&fi, child_die, type, cu);
 > -	      if (need_to_update_name)
 > -		{
 > -		  /* The demangled names of member functions contain
 > -		     information about enclosing namespaces/classes,
 > -		     if any.  */
 > -
 > -		  /* FIXME: carlton/2003-11-10: The excessive
 > -		     demangling here is a bit wasteful, as is the
 > -		     memory usage for names.  */
 > -
 > -		  /* NOTE: carlton/2003-11-10: As commented in
 > -		     add_partial_structure, the demangler sometimes
 > -		     prints the type info in a different form from the
 > -		     debug info.  We could solve this by using the
 > -		     demangled name to get the prefix; if doing so,
 > -		     however, we'd need to be careful when reading a
 > -		     class that's nested inside a template class.
 > -		     That would also cause problems when trying to
 > -		     determine RTTI information, since we use the
 > -		     demangler to determine the appropriate class
 > -		     name.  */
 > -		  char *actual_class_name
 > -		    = class_name_from_physname (dwarf2_linkage_name
 > -						(child_die, cu));
 > -		  if (actual_class_name != NULL
 > -		      && strcmp (actual_class_name, name) != 0)
 > -		    {
 > -		      TYPE_TAG_NAME (type)
 > -			= obsavestring (actual_class_name,
 > -					strlen (actual_class_name),
 > -					&objfile->objfile_obstack);
 > -		    }
 > -		  xfree (actual_class_name);
 > -		  need_to_update_name = 0;
 > -		}
 >  	    }
 >  	  else if (child_die->tag == DW_TAG_inheritance)
 >  	    {
 > @@ -3222,6 +3165,59 @@ read_structure_scope (struct die_info *d
 >    processing_current_prefix = previous_prefix;
 >    if (back_to != NULL)
 >      do_cleanups (back_to);
 > +}
 > +
 > +/* Determine the name of the type represented by DIE, which should be
 > +   a named C++ compound type.  Return the name in question; the caller
 > +   is responsible for xfree()'ing it.  */
 > +
 > +static char *
 > +determine_class_name (struct die_info *die, struct dwarf2_cu *cu)
 > +{
 > +  struct cleanup *back_to = NULL;
 > +  struct die_info *spec_die = die_specification (die, cu);
 > +  char *new_prefix = NULL;
 > +
 > +  /* If this is the definition of a class that is declared by another
 > +     die, then processing_current_prefix may not be accurate; see
 > +     read_func_scope for a similar example.  */
 > +  if (spec_die != NULL)
 > +    {
 > +      char *specification_prefix = determine_prefix (spec_die, cu);
 > +      processing_current_prefix = specification_prefix;
 > +      back_to = make_cleanup (xfree, specification_prefix);
 > +    }
 > +
 > +  /* If we don't have namespace debug info, guess the name by trying
 > +     to demangle the names of members, just like we did in
 > +     add_partial_structure.  */
 > +  if (!processing_has_namespace_info)
 > +    {
 > +      struct die_info *child;
 > +
 > +      for (child = die->child;
 > +	   child != NULL && child->tag != 0;
 > +	   child = sibling_die (child))
 > +	{
 > +	  if (child->tag == DW_TAG_subprogram)
 > +	    {
 > +	      new_prefix = class_name_from_physname (dwarf2_linkage_name
 > +						     (child, cu));
 > +
 > +	      if (new_prefix != NULL)
 > +		break;
 > +	    }
 > +	}
 > +    }
 > +
 > +  if (new_prefix == NULL)
 > +    new_prefix = typename_concat (processing_current_prefix,
 > +				  dwarf2_name (die, cu));
 > +
 > +  if (back_to != NULL)
 > +    do_cleanups (back_to);
 > +
 > +  return new_prefix;
 >  }
 >  
 >  /* Given a pointer to a die which begins an enumeration, process all