search.c

gcc-2.95.3 Linux下最常用的C编译器

   ambiguous lookup, we return NULL.  If PROTECT is 1, we issue an
   error message.  If PROTECT is 2, we return a TREE_LIST whose
   TREEE_TYPE is error_mark_node and whose TREE_VALUEs are the list of
   ambiguous candidates.

   WANT_TYPE is 1 when we should only return TYPE_DECLs, if no
   TYPE_DECL can be found return NULL_TREE.  */

tree
lookup_member (xbasetype, name, protect, want_type)
     register tree xbasetype, name;
     int protect, want_type;
{
  tree rval, rval_binfo = NULL_TREE;
  tree type = NULL_TREE, basetype_path = NULL_TREE;
  struct lookup_field_info lfi;

  /* rval_binfo is the binfo associated with the found member, note,
     this can be set with useful information, even when rval is not
     set, because it must deal with ALL members, not just non-function
     members.  It is used for ambiguity checking and the hidden
     checks.  Whereas rval is only set if a proper (not hidden)
     non-function member is found.  */

  const char *errstr = 0;

  if (xbasetype == current_class_type && TYPE_BEING_DEFINED (xbasetype)
      && IDENTIFIER_CLASS_VALUE (name))
    {
      tree field = IDENTIFIER_CLASS_VALUE (name);
      if (TREE_CODE (field) != FUNCTION_DECL
	  && ! (want_type && TREE_CODE (field) != TYPE_DECL))
	/* We're in the scope of this class, and the value has already
	   been looked up.  Just return the cached value.  */
	return field;
    }

  if (TREE_CODE (xbasetype) == TREE_VEC)
    {
      type = BINFO_TYPE (xbasetype);
      basetype_path = xbasetype;
    }
  else if (IS_AGGR_TYPE_CODE (TREE_CODE (xbasetype)))
    {
      type = xbasetype;
      basetype_path = TYPE_BINFO (type);
      my_friendly_assert (BINFO_INHERITANCE_CHAIN (basetype_path) == NULL_TREE,
			  980827);
    }
  else
    my_friendly_abort (97);

  complete_type (type);

#ifdef GATHER_STATISTICS
  n_calls_lookup_field++;
#endif /* GATHER_STATISTICS */

  bzero ((PTR) &lfi, sizeof (lfi));
  lfi.type = type;
  lfi.name = name;
  lfi.want_type = want_type;
  bfs_walk (basetype_path, &lookup_field_r, &lookup_field_queue_p, &lfi);
  rval = lfi.rval;
  rval_binfo = lfi.rval_binfo;
  if (rval_binfo)
    type = BINFO_TYPE (rval_binfo);
  errstr = lfi.errstr;

  /* If we are not interested in ambiguities, don't report them;
     just return NULL_TREE.  */
  if (!protect && lfi.ambiguous)
    return NULL_TREE;
  
  if (protect == 2) 
    {
      if (lfi.ambiguous)
	return lfi.ambiguous;
      else
	protect = 0;
    }

  /* [class.access]

     In the case of overloaded function names, access control is
     applied to the function selected by overloaded resolution.  */
  if (rval && protect && !is_overloaded_fn (rval)
      && !IS_SIGNATURE_POINTER (DECL_REAL_CONTEXT (rval))
      && !IS_SIGNATURE_REFERENCE (DECL_REAL_CONTEXT (rval))
      && !enforce_access (xbasetype, rval))
    return error_mark_node;

  if (errstr && protect)
    {
      cp_error (errstr, name, type);
      if (lfi.ambiguous)
        print_candidates (lfi.ambiguous);
      rval = error_mark_node;
    }

  /* If the thing we found was found via the implicit typename
     extension, build the typename type.  */
  if (rval && lfi.from_dep_base_p && !DECL_CLASS_TEMPLATE_P (rval))
    rval = TYPE_STUB_DECL (build_typename_type (BINFO_TYPE (basetype_path),
						name, name,
						TREE_TYPE (rval)));

  if (rval && is_overloaded_fn (rval)) 
    {
      rval = scratch_tree_cons (basetype_path, rval, NULL_TREE);
      SET_BASELINK_P (rval);
    }

  return rval;
}

/* Like lookup_member, except that if we find a function member we
   return NULL_TREE.  */

tree
lookup_field (xbasetype, name, protect, want_type)
     register tree xbasetype, name;
     int protect, want_type;
{
  tree rval = lookup_member (xbasetype, name, protect, want_type);
  
  /* Ignore functions.  */
  if (rval && TREE_CODE (rval) == TREE_LIST)
    return NULL_TREE;

  return rval;
}

/* Like lookup_member, except that if we find a non-function member we
   return NULL_TREE.  */

tree
lookup_fnfields (xbasetype, name, protect)
     register tree xbasetype, name;
     int protect;
{
  tree rval = lookup_member (xbasetype, name, protect, /*want_type=*/0);

  /* Ignore non-functions.  */
  if (rval && TREE_CODE (rval) != TREE_LIST)
    return NULL_TREE;

  return rval;
}

/* TYPE is a class type. Return the index of the fields within
   the method vector with name NAME, or -1 is no such field exists.  */

int
lookup_fnfields_1 (type, name)
     tree type, name;
{
  register tree method_vec 
    = CLASS_TYPE_P (type) ? CLASSTYPE_METHOD_VEC (type) : NULL_TREE;

  if (method_vec != 0)
    {
      register tree *methods = &TREE_VEC_ELT (method_vec, 0);
      register tree *end = TREE_VEC_END (method_vec);

#ifdef GATHER_STATISTICS
      n_calls_lookup_fnfields_1++;
#endif /* GATHER_STATISTICS */

      /* Constructors are first...  */
      if (*methods && name == ctor_identifier)
	return 0;

      /* and destructors are second.  */
      if (*++methods && name == dtor_identifier)
	return 1;

      while (++methods != end && *methods)
	{
#ifdef GATHER_STATISTICS
	  n_outer_fields_searched++;
#endif /* GATHER_STATISTICS */
	  if (DECL_NAME (OVL_CURRENT (*methods)) == name)
	    break;
	}

      /* If we didn't find it, it might have been a template
	 conversion operator.  (Note that we don't look for this case
	 above so that we will always find specializations first.)  */
      if ((methods == end || !*methods)
	  && IDENTIFIER_TYPENAME_P (name)) 
	{
	  methods = &TREE_VEC_ELT (method_vec, 0) + 1;
	  
	  while (++methods != end && *methods)
	    {
	      tree method_name = DECL_NAME (OVL_CURRENT (*methods));

	      if (!IDENTIFIER_TYPENAME_P (method_name))
		{
		  /* Since all conversion operators come first, we know
		     there is no such operator.  */
		  methods = end;
		  break;
		}
	      else if (TREE_CODE (OVL_CURRENT (*methods)) == TEMPLATE_DECL)
		break;
	    }
	}

      if (methods != end && *methods)
	return methods - &TREE_VEC_ELT (method_vec, 0);
    }

  return -1;
}

/* Walk the class hierarchy dominated by TYPE.  FN is called for each
   type in the hierarchy, in a breadth-first preorder traversal.  .
   If it ever returns a non-NULL value, that value is immediately
   returned and the walk is terminated.  At each node FN, is passed a
   BINFO indicating the path from the curently visited base-class to
   TYPE.  The TREE_CHAINs of the BINFOs may be used for scratch space;
   they are otherwise unused.  Before each base-class is walked QFN is
   called.  If the value returned is non-zero, the base-class is
   walked; otherwise it is not.  If QFN is NULL, it is treated as a
   function which always returns 1.  Both FN and QFN are passed the
   DATA whenever they are called.  */

static tree
bfs_walk (binfo, fn, qfn, data)
     tree binfo;
     tree (*fn) PROTO((tree, void *));
     tree (*qfn) PROTO((tree, void *));
     void *data;
{
  size_t head;
  size_t tail;
  tree rval = NULL_TREE;
  /* An array of the base classes of BINFO.  These will be built up in
     breadth-first order, except where QFN prunes the search.  */
  varray_type bfs_bases;

  /* Start with enough room for ten base classes.  That will be enough
     for most hierarchies.  */
  VARRAY_TREE_INIT (bfs_bases, 10, "search_stack");

  /* Put the first type into the stack.  */
  VARRAY_TREE (bfs_bases, 0) = binfo;
  tail = 1;

  for (head = 0; head < tail; ++head)
    {
      int i;
      int n_baselinks;
      tree binfos;

      /* Pull the next type out of the queue.  */
      binfo = VARRAY_TREE (bfs_bases, head);

      /* If this is the one we're looking for, we're done.  */
      rval = (*fn) (binfo, data);
      if (rval)
	break;

      /* Queue up the base types.  */
      binfos = BINFO_BASETYPES (binfo);
      n_baselinks = binfos ? TREE_VEC_LENGTH (binfos): 0;
      for (i = 0; i < n_baselinks; i++)
	{
	  tree base_binfo = TREE_VEC_ELT (binfos, i);

	  if (qfn)
	    base_binfo = (*qfn) (base_binfo, data);

	  if (base_binfo)
	    {
	      if (tail == VARRAY_SIZE (bfs_bases))
		VARRAY_GROW (bfs_bases, 2 * VARRAY_SIZE (bfs_bases));
	      VARRAY_TREE (bfs_bases, tail) = base_binfo;
	      ++tail;
	    }
	}
    }

  /* Clean up.  */
  VARRAY_FREE (bfs_bases);

  return rval;
}

/* Exactly like bfs_walk, except that a depth-first traversal is
   performed, and PREFN is called in preorder, while POSTFN is called
   in postorder.  */

static tree
dfs_walk_real (binfo, prefn, postfn, qfn, data)
     tree binfo;
     tree (*prefn) PROTO((tree, void *));
     tree (*postfn) PROTO((tree, void *));
     tree (*qfn) PROTO((tree, void *));
     void *data;
{
  int i;
  int n_baselinks;
  tree binfos;
  tree rval = NULL_TREE;

  /* Call the pre-order walking function.  */
  if (prefn)
    {
      rval = (*prefn) (binfo, data);
      if (rval)
	return rval;
    }

  /* Process the basetypes.  */
  binfos = BINFO_BASETYPES (binfo);
  n_baselinks = binfos ? TREE_VEC_LENGTH (binfos): 0;
  for (i = 0; i < n_baselinks; i++)
    {
      tree base_binfo = TREE_VEC_ELT (binfos, i);
      
      if (qfn)
	base_binfo = (*qfn) (base_binfo, data);

      if (base_binfo)
	{
	  rval = dfs_walk_real (base_binfo, prefn, postfn, qfn, data);
	  if (rval)
	    return rval;
	}
    }

  /* Call the post-order walking function.  */
  if (postfn)
    rval = (*postfn) (binfo, data);
  
  return rval;
}

/* Exactly like bfs_walk, except that a depth-first post-order traversal is
   performed.  */

tree
dfs_walk (binfo, fn, qfn, data)
     tree binfo;
     tree (*fn) PROTO((tree, void *));
     tree (*qfn) PROTO((tree, void *));
     void *data;
{
  return dfs_walk_real (binfo, 0, fn, qfn, data);
}

struct gvnt_info 
{
  /* The name of the function we are looking for.  */
  tree name;
  /* The overloaded functions we have found.  */
  tree fields;
};

/* Called from get_virtuals_named_this via bfs_walk.  */

static tree
get_virtuals_named_this_r (binfo, data)
     tree binfo;
     void *data;
{
  struct gvnt_info *gvnti = (struct gvnt_info *) data;
  tree type = BINFO_TYPE (binfo);
  int idx;

  idx = lookup_fnfields_here (BINFO_TYPE (binfo), gvnti->name);
  if (idx >= 0)
    gvnti->fields
      = scratch_tree_cons (binfo, 
			   TREE_VEC_ELT (CLASSTYPE_METHOD_VEC (type),
					 idx),
			   gvnti->fields);

  return NULL_TREE;
}

/* Return the virtual functions with the indicated NAME in the type
   indicated by BINFO.  The result is a TREE_LIST whose TREE_PURPOSE
   indicates the base class from which the TREE_VALUE (an OVERLOAD or
   just a FUNCTION_DECL) originated.  */

static tree
get_virtuals_named_this (binfo, name)
     tree binfo;
     tree name;
{
  struct gvnt_info gvnti;
  tree fields;

  gvnti.name = name;
  gvnti.fields = NULL_TREE;

  bfs_walk (binfo, get_virtuals_named_this_r, 0, &gvnti);

  /* Get to the function decls, and return the first virtual function
     with this name, if there is one.  */
  for (fields = gvnti.fields; fields; fields = next_baselink (fields))
    {
      tree fndecl;

      for (fndecl = TREE_VALUE (fields); fndecl; fndecl = OVL_NEXT (fndecl))
	if (DECL_VINDEX (OVL_CURRENT (fndecl)))
	  return fields;
    }
  return NULL_TREE;
}

static tree
get_virtual_destructor (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  tree type = BINFO_TYPE (binfo);
  if (TYPE_HAS_DESTRUCTOR (type)
      && DECL_VINDEX (TREE_VEC_ELT (CLASSTYPE_METHOD_VEC (type), 1)))
    return TREE_VEC_ELT (CLASSTYPE_METHOD_VEC (type), 1);
  return 0;
}

static tree
tree_has_any_destructor_p (binfo, data)
     tree binfo;
     void *data ATTRIBUTE_UNUSED;
{
  tree type = BINFO_TYPE (binfo);
  return TYPE_NEEDS_DESTRUCTOR (type) ? binfo : NULL_TREE;
}

/* Returns > 0 if a function with type DRETTYPE overriding a function
   with type BRETTYPE is covariant, as defined in [class.virtual].

   Returns 1 if trivial covariance, 2 if non-trivial (requiring runtime
   adjustment), or -1 if pedantically invalid covariance.  */

static int
covariant_return_p (brettype, drettype)
     tree brettype, drettype;
{
  tree binfo;

  if (TREE_CODE (brettype) == FUNCTION_DECL
      || TREE_CODE (brettype) == THUNK_DECL)