search.c

gcc-2.95.3 Linux下最常用的C编译器

    {
      brettype = TREE_TYPE (TREE_TYPE (brettype));
      drettype = TREE_TYPE (TREE_TYPE (drettype));
    }
  else if (TREE_CODE (brettype) == METHOD_TYPE)
    {
      brettype = TREE_TYPE (brettype);
      drettype = TREE_TYPE (drettype);
    }

  if (same_type_p (brettype, drettype))
    return 0;

  if (! (TREE_CODE (brettype) == TREE_CODE (drettype)
	 && (TREE_CODE (brettype) == POINTER_TYPE
	     || TREE_CODE (brettype) == REFERENCE_TYPE)
	 && TYPE_QUALS (brettype) == TYPE_QUALS (drettype)))
    return 0;

  if (! can_convert (brettype, drettype))
    return 0;

  brettype = TREE_TYPE (brettype);
  drettype = TREE_TYPE (drettype);

  /* If not pedantic, allow any standard pointer conversion.  */
  if (! IS_AGGR_TYPE (drettype) || ! IS_AGGR_TYPE (brettype))
    return -1;

  binfo = get_binfo (brettype, drettype, 1);

  /* If we get an error_mark_node from get_binfo, it already complained,
     so let's just succeed.  */
  if (binfo == error_mark_node)
    return 1;

  if (! BINFO_OFFSET_ZEROP (binfo) || TREE_VIA_VIRTUAL (binfo))
    return 2;
  return 1;
}

/* Given a class type TYPE, and a function decl FNDECL, look for a
   virtual function in TYPE's hierarchy which FNDECL could match as a
   virtual function.  It doesn't matter which one we find.

   DTORP is nonzero if we are looking for a destructor.  Destructors
   need special treatment because they do not match by name.  */

tree
get_matching_virtual (binfo, fndecl, dtorp)
     tree binfo, fndecl;
     int dtorp;
{
  tree tmp = NULL_TREE;
  int i;

  if (TREE_CODE (fndecl) == TEMPLATE_DECL)
    /* In [temp.mem] we have:

         A specialization of a member function template does not
         override a virtual function from a base class.  */
    return NULL_TREE;

  /* Breadth first search routines start searching basetypes
     of TYPE, so we must perform first ply of search here.  */
  if (dtorp)
    return bfs_walk (binfo, get_virtual_destructor,
		     tree_has_any_destructor_p, 0);
  else
    {
      tree drettype, dtypes, btypes, instptr_type;
      tree basetype = DECL_CLASS_CONTEXT (fndecl);
      tree baselink, best = NULL_TREE;
      tree name = DECL_ASSEMBLER_NAME (fndecl);
      tree declarator = DECL_NAME (fndecl);
      if (IDENTIFIER_VIRTUAL_P (declarator) == 0)
	return NULL_TREE;

      baselink = get_virtuals_named_this (binfo, declarator);
      if (baselink == NULL_TREE)
	return NULL_TREE;

      drettype = TREE_TYPE (TREE_TYPE (fndecl));
      dtypes = TYPE_ARG_TYPES (TREE_TYPE (fndecl));
      if (DECL_STATIC_FUNCTION_P (fndecl))
	instptr_type = NULL_TREE;
      else
	instptr_type = TREE_TYPE (TREE_VALUE (dtypes));

      for (; baselink; baselink = next_baselink (baselink))
	{
	  tree tmps;
	  for (tmps = TREE_VALUE (baselink); tmps; tmps = OVL_NEXT (tmps))
	    {
	      tmp = OVL_CURRENT (tmps);
	      if (! DECL_VINDEX (tmp))
		continue;

	      btypes = TYPE_ARG_TYPES (TREE_TYPE (tmp));
	      if (instptr_type == NULL_TREE)
		{
		  if (compparms (TREE_CHAIN (btypes), dtypes))
		    /* Caller knows to give error in this case.  */
		    return tmp;
		  return NULL_TREE;
		}

	      if (/* The first parameter is the `this' parameter,
		     which has POINTER_TYPE, and we can therefore
		     safely use TYPE_QUALS, rather than
		     CP_TYPE_QUALS.  */
		  (TYPE_QUALS (TREE_TYPE (TREE_VALUE (btypes)))
		   == TYPE_QUALS (instptr_type))
		  && compparms (TREE_CHAIN (btypes), TREE_CHAIN (dtypes)))
		{
		  tree brettype = TREE_TYPE (TREE_TYPE (tmp));
		  if (same_type_p (brettype, drettype))
		    /* OK */;
		  else if ((i = covariant_return_p (brettype, drettype)))
		    {
		      if (i == 2)
			sorry ("adjusting pointers for covariant returns");

		      if (pedantic && i == -1)
			{
			  cp_pedwarn_at ("invalid covariant return type for `%#D' (must be pointer or reference to class)", fndecl);
			  cp_pedwarn_at ("  overriding `%#D'", tmp);
			}
		    }
		  else if (IS_AGGR_TYPE_2 (brettype, drettype)
			   && same_or_base_type_p (brettype, drettype))
		    {
		      error ("invalid covariant return type (must use pointer or reference)");
		      cp_error_at ("  overriding `%#D'", tmp);
		      cp_error_at ("  with `%#D'", fndecl);
		    }
		  else if (IDENTIFIER_ERROR_LOCUS (name) == NULL_TREE)
		    {
		      cp_error_at ("conflicting return type specified for virtual function `%#D'", fndecl);
		      cp_error_at ("  overriding definition as `%#D'", tmp);
		      SET_IDENTIFIER_ERROR_LOCUS (name, basetype);
		    }

		  /* FNDECL overrides this function.  We continue to
		     check all the other functions in order to catch
		     errors; it might be that in some other baseclass
		     a virtual function was declared with the same
		     parameter types, but a different return type.  */
		  best = tmp;
		}
	    }
	}

      return best;
    }
}

/* Return the list of virtual functions which are abstract in type
   TYPE that come from non virtual base classes.  See
   expand_direct_vtbls_init for the style of search we do.  */

static tree
get_abstract_virtuals_1 (binfo, do_self, abstract_virtuals)
     tree binfo;
     int do_self;
     tree abstract_virtuals;
{
  tree binfos = BINFO_BASETYPES (binfo);
  int i, n_baselinks = binfos ? TREE_VEC_LENGTH (binfos) : 0;

  for (i = 0; i < n_baselinks; i++)
    {
      tree base_binfo = TREE_VEC_ELT (binfos, i);
      int is_not_base_vtable
	= i != CLASSTYPE_VFIELD_PARENT (BINFO_TYPE (binfo));
      if (! TREE_VIA_VIRTUAL (base_binfo))
	abstract_virtuals
	  = get_abstract_virtuals_1 (base_binfo, is_not_base_vtable,
				     abstract_virtuals);
    }
  /* Should we use something besides CLASSTYPE_VFIELDS? */
  if (do_self && CLASSTYPE_VFIELDS (BINFO_TYPE (binfo)))
    {
      tree virtuals = BINFO_VIRTUALS (binfo);

      skip_rtti_stuff (&virtuals, BINFO_TYPE (binfo));

      while (virtuals)
	{
	  tree base_pfn = FNADDR_FROM_VTABLE_ENTRY (TREE_VALUE (virtuals));
	  tree base_fndecl = TREE_OPERAND (base_pfn, 0);
	  if (DECL_ABSTRACT_VIRTUAL_P (base_fndecl))
	    abstract_virtuals = tree_cons (NULL_TREE, base_fndecl, abstract_virtuals);
	  virtuals = TREE_CHAIN (virtuals);
	}
    }
  return abstract_virtuals;
}

/* Return the list of virtual functions which are abstract in type TYPE.
   This information is cached, and so must be built on a
   non-temporary obstack.  */

tree
get_abstract_virtuals (type)
     tree type;
{
  tree vbases;
  tree abstract_virtuals = NULL;

  /* First get all from non-virtual bases.  */
  abstract_virtuals
    = get_abstract_virtuals_1 (TYPE_BINFO (type), 1, abstract_virtuals);
					       
  for (vbases = CLASSTYPE_VBASECLASSES (type); vbases; vbases = TREE_CHAIN (vbases))
    {
      tree virtuals = BINFO_VIRTUALS (vbases);

      skip_rtti_stuff (&virtuals, type);

      while (virtuals)
	{
	  tree base_pfn = FNADDR_FROM_VTABLE_ENTRY (TREE_VALUE (virtuals));
	  tree base_fndecl = TREE_OPERAND (base_pfn, 0);
	  if (DECL_NEEDS_FINAL_OVERRIDER_P (base_fndecl))
	    cp_error ("`%#D' needs a final overrider", base_fndecl);
	  else if (DECL_ABSTRACT_VIRTUAL_P (base_fndecl))
	    abstract_virtuals = tree_cons (NULL_TREE, base_fndecl, abstract_virtuals);
	  virtuals = TREE_CHAIN (virtuals);
	}
    }
  return nreverse (abstract_virtuals);
}

static tree
next_baselink (baselink)
     tree baselink;
{
  tree tmp = TREE_TYPE (baselink);
  baselink = TREE_CHAIN (baselink);
  while (tmp)
    {
      /* @@ does not yet add previous base types.  */
      baselink = tree_cons (TREE_PURPOSE (tmp), TREE_VALUE (tmp),
			    baselink);
      TREE_TYPE (baselink) = TREE_TYPE (tmp);
      tmp = TREE_CHAIN (tmp);
    }
  return baselink;
}

/* DEPTH-FIRST SEARCH ROUTINES.  */

/* This routine converts a pointer to be a pointer of an immediate
   base class.  The normal convert_pointer_to routine would diagnose
   the conversion as ambiguous, under MI code that has the base class
   as an ambiguous base class.  */

static tree
convert_pointer_to_single_level (to_type, expr)
     tree to_type, expr;
{
  tree derived;
  tree binfo_of_derived;
  int i;

  derived = TREE_TYPE (TREE_TYPE (expr));
  binfo_of_derived = TYPE_BINFO (derived);
  my_friendly_assert (BINFO_INHERITANCE_CHAIN (binfo_of_derived) == NULL_TREE,
		      980827);
  for (i = CLASSTYPE_N_BASECLASSES (derived) - 1; i >= 0; --i)
    {
      tree binfo = BINFO_BASETYPE (binfo_of_derived, i);
      my_friendly_assert (BINFO_INHERITANCE_CHAIN (binfo) == binfo_of_derived,
			  980827);
      if (same_type_p (BINFO_TYPE (binfo), to_type))
	return build_vbase_path (PLUS_EXPR, 
				 build_pointer_type (to_type), 
				 expr, binfo, 1);
    }

  my_friendly_abort (19990607);

  /* NOTREACHED */
  return NULL_TREE;
}

tree markedp (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  return BINFO_MARKED (binfo) ? binfo : NULL_TREE; 
}

static tree
unmarkedp (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  return !BINFO_MARKED (binfo) ? binfo : NULL_TREE;
}

static tree
marked_vtable_pathp (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  return BINFO_VTABLE_PATH_MARKED (binfo) ? binfo : NULL_TREE; 
}

static tree
unmarked_vtable_pathp (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  return !BINFO_VTABLE_PATH_MARKED (binfo) ? binfo : NULL_TREE; 
}

static tree 
marked_new_vtablep (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  return BINFO_NEW_VTABLE_MARKED (binfo) ? binfo : NULL_TREE; 
}

static tree
unmarked_new_vtablep (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  return !BINFO_NEW_VTABLE_MARKED (binfo) ? binfo : NULL_TREE; 
}

static tree
marked_pushdecls_p (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  return (CLASS_TYPE_P (BINFO_TYPE (binfo))
	  && BINFO_PUSHDECLS_MARKED (binfo)) ? binfo : NULL_TREE; 
}

static tree
unmarked_pushdecls_p (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  return (CLASS_TYPE_P (BINFO_TYPE (binfo))
	  && !BINFO_PUSHDECLS_MARKED (binfo)) ? binfo : NULL_TREE;
}

#if 0
static int dfs_search_slot_nonempty_p (binfo) tree binfo;
{ return CLASSTYPE_SEARCH_SLOT (BINFO_TYPE (binfo)) != 0; }
#endif

static tree 
dfs_debug_unmarkedp (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  return (!CLASSTYPE_DEBUG_REQUESTED (BINFO_TYPE (binfo)) 
	  ? binfo : NULL_TREE);
}

/* The worker functions for `dfs_walk'.  These do not need to
   test anything (vis a vis marking) if they are paired with
   a predicate function (above).  */

#if 0
static void
dfs_mark (binfo) tree binfo;
{ SET_BINFO_MARKED (binfo); }
#endif

tree
dfs_unmark (binfo, data) 
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{ 
  CLEAR_BINFO_MARKED (binfo); 
  return NULL_TREE;
}

#if 0
static void
dfs_mark_vtable_path (binfo) tree binfo;
{ SET_BINFO_VTABLE_PATH_MARKED (binfo); }

static void
dfs_unmark_vtable_path (binfo) tree binfo;
{ CLEAR_BINFO_VTABLE_PATH_MARKED (binfo); }

static void
dfs_mark_new_vtable (binfo) tree binfo;
{ SET_BINFO_NEW_VTABLE_MARKED (binfo); }

static void
dfs_unmark_new_vtable (binfo) tree binfo;
{ CLEAR_BINFO_NEW_VTABLE_MARKED (binfo); }

static void
dfs_clear_search_slot (binfo) tree binfo;
{ CLASSTYPE_SEARCH_SLOT (BINFO_TYPE (binfo)) = 0; }
#endif

static tree
dfs_debug_mark (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  tree t = BINFO_TYPE (binfo);

  /* Use heuristic that if there are virtual functions,
     ignore until we see a non-inline virtual function.  */
  tree methods = CLASSTYPE_METHOD_VEC (t);

  CLASSTYPE_DEBUG_REQUESTED (t) = 1;

  if (methods == 0)
    return NULL_TREE;

  /* If interface info is known, either we've already emitted the debug
     info or we don't need to.  */
  if (CLASSTYPE_INTERFACE_KNOWN (t))
    return NULL_TREE;

  /* If debug info is requested from this context for this type, supply it.
     If debug info is requested from another context for this type,
     see if some third context can supply it.  */
  if (current_function_decl == NULL_TREE
      || DECL_CLASS_CONTEXT (current_function_decl) != t)
    {
      if (TREE_VEC_ELT (methods, 1))
	methods = TREE_VEC_ELT (methods, 1);
      else if (TREE_VEC_ELT (methods, 0))
	methods = TREE_VEC_ELT (methods, 0);
      else
	methods = TREE_VEC_ELT (methods, 2);
      methods = OVL_CURRENT (methods);
      while (methods)
	{
	  if (DECL_VINDEX (methods)
	      && DECL_THIS_INLINE (methods) == 0
	      && DE