search.c

GUN开源阻止下的编译器GCC

    {
      tree binfos = BINFO_BASETYPES (TYPE_BINFO (type));
      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);

	  if (parent == BINFO_TYPE (base_binfo))
	    return 1;
	}
    }
  return 0;
}
#endif

/* Check whether the type given in BINFO is derived from PARENT.  If
   it isn't, return 0.  If it is, but the derivation is MI-ambiguous
   AND protect != 0, emit an error message and return error_mark_node.

   Otherwise, if TYPE is derived from PARENT, return the actual base
   information, unless a one of the protection violations below
   occurs, in which case emit an error message and return error_mark_node.

   If PROTECT is 1, then check if access to a public field of PARENT
   would be private.  Also check for ambiguity.  */

tree
get_binfo (parent, binfo, protect)
     register tree parent, binfo;
     int protect;
{
  tree type;
  int dist;
  tree rval = NULL_TREE;
  
  if (TREE_CODE (parent) == TREE_VEC)
    parent = BINFO_TYPE (parent);
  else if (! IS_AGGR_TYPE_CODE (TREE_CODE (parent)))
    my_friendly_abort (89);

  if (TREE_CODE (binfo) == TREE_VEC)
    type = BINFO_TYPE (binfo);
  else if (IS_AGGR_TYPE_CODE (TREE_CODE (binfo)))
    type = binfo;
  else
    my_friendly_abort (90);
  
  dist = get_base_distance (parent, binfo, protect, &rval);

  if (dist == -3)
    {
      cp_error ("fields of `%T' are inaccessible in `%T' due to private inheritance",
		parent, type);
      return error_mark_node;
    }
  else if (dist == -2 && protect)
    {
      cp_error ("type `%T' is ambiguous base class for type `%T'", parent,
		type);
      return error_mark_node;
    }

  return rval;
}

/* This is the newer depth first get_base_distance routine.  */
static int
get_base_distance_recursive (binfo, depth, is_private, basetype_path, rval,
			     rval_private_ptr, new_binfo_ptr, parent, path_ptr,
			     protect, via_virtual_ptr, via_virtual)
     tree binfo, basetype_path, *new_binfo_ptr, parent, *path_ptr;
     int *rval_private_ptr, depth, is_private, rval, protect, *via_virtual_ptr,
       via_virtual;
{
  tree binfos;
  int i, n_baselinks;

  if (BINFO_TYPE (binfo) == parent || binfo == parent)
    {
      if (rval == -1)
	{
	  rval = depth;
	  *rval_private_ptr = is_private;
	  *new_binfo_ptr = binfo;
	  *via_virtual_ptr = via_virtual;
	}
      else
	{
	  int same_object = (tree_int_cst_equal (BINFO_OFFSET (*new_binfo_ptr),
						 BINFO_OFFSET (binfo))
			     && *via_virtual_ptr && via_virtual);
			     
	  if (*via_virtual_ptr && via_virtual==0)
	    {
	      *rval_private_ptr = is_private;
	      *new_binfo_ptr = binfo;
	      *via_virtual_ptr = via_virtual;
	    }
	  else if (same_object)
	    {
	      if (*rval_private_ptr && ! is_private)
		{
		  *rval_private_ptr = is_private;
		  *new_binfo_ptr = binfo;
		  *via_virtual_ptr = via_virtual;
		}
	      return rval;
	    }

	  rval = -2;
	}
      return rval;
    }

  binfos = BINFO_BASETYPES (binfo);
  n_baselinks = binfos ? TREE_VEC_LENGTH (binfos) : 0;
  depth += 1;

  /* Process base types.  */
  for (i = 0; i < n_baselinks; i++)
    {
      tree base_binfo = TREE_VEC_ELT (binfos, i);

      /* Find any specific instance of a virtual base, when searching with
	 a binfo... */
      if (BINFO_MARKED (base_binfo) == 0 || TREE_CODE (parent) == TREE_VEC)
	{
	  int via_private
	    = (protect
	       && (is_private
		   || (!TREE_VIA_PUBLIC (base_binfo)
		       && !is_friend (BINFO_TYPE (binfo), current_scope ()))));
	  int this_virtual = via_virtual || TREE_VIA_VIRTUAL (base_binfo);
	  int was;

	  /* When searching for a non-virtual, we cannot mark
	     virtually found binfos. */
	  if (! this_virtual)
	    SET_BINFO_MARKED (base_binfo);

#define WATCH_VALUES(rval, via_private) (rval == -1 ? 3 : via_private)

	  was = WATCH_VALUES (rval, *via_virtual_ptr);
	  rval = get_base_distance_recursive (base_binfo, depth, via_private,
					      binfo, rval, rval_private_ptr,
					      new_binfo_ptr, parent, path_ptr,
					      protect, via_virtual_ptr,
					      this_virtual);
	  /* watch for updates; only update if path is good. */
	  if (path_ptr && WATCH_VALUES (rval, *via_virtual_ptr) != was)
	    BINFO_INHERITANCE_CHAIN (base_binfo) = binfo;
	  if (rval == -2 && *via_virtual_ptr == 0)
	    return rval;

#undef WATCH_VALUES

	}
    }

  return rval;
}

/* Return the number of levels between type PARENT and the type given
   in BINFO, following the leftmost path to PARENT not found along a
   virtual path, if there are no real PARENTs (all come from virtual
   base classes), then follow the leftmost path to PARENT.

   Return -1 if TYPE is not derived from PARENT.
   Return -2 if PARENT is an ambiguous base class of TYPE, and PROTECT is
    non-negative.
   Return -3 if PARENT is private to TYPE, and PROTECT is non-zero.

   If PATH_PTR is non-NULL, then also build the list of types
   from PARENT to TYPE, with TREE_VIA_VIRTUAL and TREE_VIA_PUBLIC
   set.

   PARENT can also be a binfo, in which case that exact parent is found
   and no other.  convert_pointer_to_real uses this functionality.

   If BINFO is a binfo, its BINFO_INHERITANCE_CHAIN will be left alone.  */

int
get_base_distance (parent, binfo, protect, path_ptr)
     register tree parent, binfo;
     int protect;
     tree *path_ptr;
{
  int rval;
  int rval_private = 0;
  tree type;
  tree new_binfo = NULL_TREE;
  int via_virtual;
  int watch_access = protect;

  if (TREE_CODE (parent) != TREE_VEC)
    parent = TYPE_MAIN_VARIANT (parent);

  if (TREE_CODE (binfo) == TREE_VEC)
    type = BINFO_TYPE (binfo);
  else if (IS_AGGR_TYPE_CODE (TREE_CODE (binfo)))
    {
      type = binfo;
      binfo = TYPE_BINFO (type);

      if (path_ptr)
	BINFO_INHERITANCE_CHAIN (binfo) = NULL_TREE;
    }
  else
    my_friendly_abort (92);

  if (parent == type || parent == binfo)
    {
      /* If the distance is 0, then we don't really need
	 a path pointer, but we shouldn't let garbage go back.  */
      if (path_ptr)
	*path_ptr = binfo;
      return 0;
    }

  if (path_ptr)
    watch_access = 1;

  rval = get_base_distance_recursive (binfo, 0, 0, NULL_TREE, -1,
				      &rval_private, &new_binfo, parent,
				      path_ptr, watch_access, &via_virtual, 0);

  dfs_walk (binfo, dfs_unmark, markedp);

  /* Access restrictions don't count if we found an ambiguous basetype.  */
  if (rval == -2 && protect >= 0)
    rval_private = 0;

  if (rval && protect && rval_private)
    return -3;

  /* find real virtual base classes. */
  if (rval == -1 && TREE_CODE (parent) == TREE_VEC
      && parent == binfo_member (BINFO_TYPE (parent),
				 CLASSTYPE_VBASECLASSES (type)))
    {
      BINFO_INHERITANCE_CHAIN (parent) = binfo;
      new_binfo = parent;
      rval = 1;
    }

  if (path_ptr)
    *path_ptr = new_binfo;
  return rval;
}

/* Search for a member with name NAME in a multiple inheritance lattice
   specified by TYPE.  If it does not exist, return NULL_TREE.
   If the member is ambiguously referenced, return `error_mark_node'.
   Otherwise, return the FIELD_DECL.  */

/* Do a 1-level search for NAME as a member of TYPE.  The caller must
   figure out whether it can access this field.  (Since it is only one
   level, this is reasonable.)  */
static tree
lookup_field_1 (type, name)
     tree type, name;
{
  register tree field = TYPE_FIELDS (type);

#ifdef GATHER_STATISTICS
  n_calls_lookup_field_1++;
#endif
  while (field)
    {
#ifdef GATHER_STATISTICS
      n_fields_searched++;
#endif
      if (DECL_NAME (field) == NULL_TREE
	  && TREE_CODE (TREE_TYPE (field)) == UNION_TYPE)
	{
	  tree temp = lookup_field_1 (TREE_TYPE (field), name);
	  if (temp)
	    return temp;
	}
      if (DECL_NAME (field) == name)
	{
	  if ((TREE_CODE(field) == VAR_DECL || TREE_CODE(field) == CONST_DECL)
	      && DECL_ASSEMBLER_NAME (field) != NULL)
	    GNU_xref_ref(current_function_decl,
			 IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (field)));
	  return field;
	}
      field = TREE_CHAIN (field);
    }
  /* Not found.  */
  if (name == _vptr_name)
    {
      /* Give the user what s/he thinks s/he wants.  */
      if (TYPE_VIRTUAL_P (type))
	return CLASSTYPE_VFIELD (type);
    }
  return NULL_TREE;
}

/* There are a number of cases we need to be aware of here:
			 current_class_type	current_function_decl
   * global			NULL			NULL
   * fn-local			NULL			SET
   * class-local		SET			NULL
   * class->fn			SET			SET
   * fn->class			SET			SET

   Those last two make life interesting.  If we're in a function which is
   itself inside a class, we need decls to go into the fn's decls (our
   second case below).  But if we're in a class and the class itself is
   inside a function, we need decls to go into the decls for the class.  To
   achieve this last goal, we must see if, when both current_class_decl and
   current_function_decl are set, the class was declared inside that
   function.  If so, we know to put the decls into the class's scope.  */

tree
current_scope ()
{
  if (current_function_decl == NULL_TREE)
    return current_class_type;
  if (current_class_type == NULL_TREE)
    return current_function_decl;
  if (DECL_CLASS_CONTEXT (current_function_decl) == current_class_type)
    return current_function_decl;

  return current_class_type;
}

/* Compute the access of FIELD.  This is done by computing
   the access available to each type in BASETYPES (which comes
   as a list of [via_public/basetype] in reverse order, namely base
   class before derived class).  The first one which defines a
   access defines the access for the field.  Otherwise, the
   access of the field is that which occurs normally.

   Uses global variables CURRENT_CLASS_TYPE and
   CURRENT_FUNCTION_DECL to use friend relationships
   if necessary.

   This will be static when lookup_fnfield comes into this file.

   access_public means that the field can be accessed by the current lexical
   scope.

   access_protected means that the field cannot be accessed by the current
   lexical scope because it is protected.

   access_private means that the field cannot be accessed by the current
   lexical scope because it is private. */

#if 0
#define PUBLIC_RETURN return (DECL_PUBLIC (field) = 1), access_public
#define PROTECTED_RETURN return (DECL_PROTECTED (field) = 1), access_protected
#define PRIVATE_RETURN return (DECL_PRIVATE (field) = 1), access_private
#else
#define PUBLIC_RETURN return access_public
#define PROTECTED_RETURN return access_protected
#define PRIVATE_RETURN return access_private
#endif

#if 0
/* Disabled with DECL_PUBLIC &c.  */
static tree previous_scope = NULL_TREE;
#endif

enum access_type
compute_access (basetype_path, field)
     tree basetype_path, field;
{
  enum access_type access;
  tree types;
  tree context;
  int protected_ok, via_protected;
  extern int flag_access_control;
#if 1
  /* Replaces static decl above.  */
  tree previous_scope;
#endif
  int static_mem =
    ((TREE_CODE (field) == FUNCTION_DECL && DECL_STATIC_FUNCTION_P (field))
     || (TREE_CODE (field) != FUNCTION_DECL && TREE_STATIC (field)));

  if (! flag_access_control)
    return access_public;

  /* The field lives in the current class.  */
  if (BINFO_TYPE (basetype_path) == current_class_type)
    return access_public;

#if 0
  /* Disabled until pushing function scope clears these out.  If ever.  */
  /* Make these special cases fast.  */
  if (current_scope () == previous_scope)
    {
      if (DECL_PUBLIC (field))
	return access_public;
      if (DECL_PROTECTED (field))
	return access_protected;
      if (DECL_PRIVATE (field))
	return access_private;
    }
#endif

  /* We don't currently support access control on nested types.  */
  if (TREE_CODE (field) == TYPE_DECL)
    return access_public;

  previous_scope = current_scope ();
  
  context = DECL_CLASS_CONTEXT (field);
  if (context == NULL_TREE)
    context = DECL_CONTEXT (field);

  /* Fields coming from nested anonymous unions have their DECL_CLASS_CONTEXT
     slot set to the union type rather than the record type containing
     the anonymous union.  In this case, DECL_FIELD_CONTEXT is correct.  */
  if (context && TREE_CODE (context) == UNION_TYPE
      && ANON_AGGRNAME_P (TYPE_IDENTIFIER (context)))
    context = DECL_FIELD_CONTEXT (field);

  /* Virtual function tables are never private.  But we should know that
     we are looking for this, and not even try to hide it.  */
  if (DECL_NAME (field) && VFIELD_NAME_P (DECL_NAME (field)) == 1)
    PUBLIC_RETURN;

  /* Member found immediately within object.  */
  if (BINFO_INHERITANCE_CHAIN (basetype_path) == NULL_TREE)
    {
      /* Are we (or an enclosing scope) friends with the class that has
         FIELD? */
      if (is_friend (context, previous_scope))
	PUBLIC_RETURN;

      /* If it's private, it's private, you letch.  */
      if (TREE_PRIVATE (field))
	PRIVATE_RETURN;

      /* ARM $11.5.  Member functions of a derived class can access the
	 non-static protected members of a base class only through a
	 pointer to the derived class, a reference to it, or an object
	 of it. Also any subsequently derived classes also have
	 access.  */
      else if (TREE_PROTECTED (field))
	{
	  if (current_class_type
	      && static_mem
  	      && ACCESSIBLY_DERIVED_FROM_P (context, current_class_type))
	    PUBLIC_RETURN;
	  else
	    PROTECTED_RETURN;
	}
      else
	PUBLIC_RETURN;