search.c

GUN开源阻止下的编译器GCC

    }

  /* must reverse more than one element */
  basetype_path = reverse_path (basetype_path);
  types = basetype_path;
  via_protected = 0;
  access = access_default;
  protected_ok = static_mem && current_class_type
    && ACCESSIBLY_DERIVED_FROM_P (BINFO_TYPE (types), current_class_type);

  while (1)
    {
      tree member;
      tree binfo = types;
      tree type = BINFO_TYPE (binfo);
      int private_ok = 0;

      /* Friends of a class can see protected members of its bases.
         Note that classes are their own friends.  */
      if (is_friend (type, previous_scope))
	{
	  protected_ok = 1;
	  private_ok = 1;
	}

      member = purpose_member (type, DECL_ACCESS (field));
      if (member)
	{
	  access = (enum access_type) TREE_VALUE (member);
	  break;
	}

      types = BINFO_INHERITANCE_CHAIN (types);

      /* If the next type was VIA_PROTECTED, then fields of all remaining
	 classes past that one are *at least* protected.  */
      if (types)
	{
	  if (TREE_VIA_PROTECTED (types))
	    via_protected = 1;
	  else if (! TREE_VIA_PUBLIC (types) && ! private_ok)
	    {
	      access = access_private;
	      break;
	    }
	}
      else
	break;
    }
  reverse_path (basetype_path);

  /* No special visibilities apply.  Use normal rules.  */

  if (access == access_default)
    {
      if (is_friend (context, previous_scope))
	access = access_public;
      else if (TREE_PRIVATE (field))
	access = access_private;
      else if (TREE_PROTECTED (field))
	access = access_protected;
      else
	access = access_public;
    }

  if (access == access_public && via_protected)
    access = access_protected;

  if (access == access_protected && protected_ok)
    access = access_public;

#if 0
  if (access == access_public)
    DECL_PUBLIC (field) = 1;
  else if (access == access_protected)
    DECL_PROTECTED (field) = 1;
  else if (access == access_private)
    DECL_PRIVATE (field) = 1;
  else my_friendly_abort (96);
#endif
  return access;
}

/* Routine to see if the sub-object denoted by the binfo PARENT can be
   found as a base class and sub-object of the object denoted by
   BINFO.  This routine relies upon binfos not being shared, except
   for binfos for virtual bases.  */
static int
is_subobject_of_p (parent, binfo)
     tree parent, binfo;
{
  tree binfos = BINFO_BASETYPES (binfo);
  int i, n_baselinks = binfos ? TREE_VEC_LENGTH (binfos) : 0;

  if (parent == binfo)
    return 1;

  /* Process and/or queue base types.  */
  for (i = 0; i < n_baselinks; i++)
    {
      tree base_binfo = TREE_VEC_ELT (binfos, i);
      if (TREE_VIA_VIRTUAL (base_binfo))
	base_binfo = TYPE_BINFO (BINFO_TYPE (base_binfo));
      if (is_subobject_of_p (parent, base_binfo))
	return 1;
    }
  return 0;
}

/* See if a one FIELD_DECL hides another.  This routine is meant to
   correspond to ANSI working paper Sept 17, 1992 10p4.  The two
   binfos given are the binfos corresponding to the particular places
   the FIELD_DECLs are found.  This routine relies upon binfos not
   being shared, except for virtual bases. */
static int
hides (hider_binfo, hidee_binfo)
     tree hider_binfo, hidee_binfo;
{
  /* hider hides hidee, if hider has hidee as a base class and
     the instance of hidee is a sub-object of hider.  The first
     part is always true is the second part is true.

     When hider and hidee are the same (two ways to get to the exact
     same member) we consider either one as hiding the other. */
  return is_subobject_of_p (hidee_binfo, hider_binfo);
}

/* Very similar to lookup_fnfields_1 but it ensures that at least one
   function was declared inside the class given by TYPE.  It really should
   only return functions that match the given TYPE.  */
static int
lookup_fnfields_here (type, name)
     tree type, name;
{
  int index = lookup_fnfields_1 (type, name);
  tree fndecls;

  if (index <= 0)
    return index;
  fndecls = TREE_VEC_ELT (CLASSTYPE_METHOD_VEC (type), index);
  while (fndecls)
    {
      if (TYPE_MAIN_VARIANT (DECL_CLASS_CONTEXT (fndecls))
	  == TYPE_MAIN_VARIANT (type))
	return index;
      fndecls = TREE_CHAIN (fndecls);
    }
  return -1;
}

/* Look for a field named NAME in an inheritance lattice dominated by
   XBASETYPE.  PROTECT is zero if we can avoid computing access
   information, otherwise it is 1.  WANT_TYPE is 1 when we should only
   return TYPE_DECLs, if no TYPE_DECL can be found return NULL_TREE.

   It was not clear what should happen if WANT_TYPE is set, and an
   ambiguity is found.  At least one use (lookup_name) to not see
   the error.  */
tree
lookup_field (xbasetype, name, protect, want_type)
     register tree xbasetype, name;
     int protect, want_type;
{
  int head = 0, tail = 0;
  tree rval, rval_binfo = NULL_TREE, rval_binfo_h;
  tree type, basetype_chain, basetype_path;
  enum access_type this_v = access_default;
  tree entry, binfo, binfo_h;
  enum access_type own_access = access_default;
  int vbase_name_p = VBASE_NAME_P (name);

  /* 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.  */

  /* rval_binfo_h and binfo_h are binfo values used when we perform the
     hiding checks, as virtual base classes may not be shared.  The strategy
     is we always go into the the binfo hierarchy owned by TYPE_BINFO of
     virtual base classes, as we cross virtual base class lines.  This way
     we know that binfo of a virtual base class will always == itself when
     found along any line.  (mrs)  */

  char *errstr = 0;

  /* Set this to nonzero if we don't know how to compute
     accurate error messages for access control.  */
  int index = MEMOIZED_HASH_FN (name);

  /* If we are looking for a constructor in a templated type, use the
     unspecialized name, as that is how we store it.  */
  if (IDENTIFIER_TEMPLATE (name))
    name = constructor_name (name);

  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 (xbasetype);
      BINFO_VIA_PUBLIC (basetype_path) = 1;
      BINFO_INHERITANCE_CHAIN (basetype_path) = NULL_TREE;
    }
  else my_friendly_abort (97);

  if (CLASSTYPE_MTABLE_ENTRY (type))
    {
      tree tem = MEMOIZED_FIELDS (CLASSTYPE_MTABLE_ENTRY (type), index);

      while (tem && TREE_PURPOSE (tem) != name)
	{
	  memoized_fields_searched[0]++;
	  tem = TREE_CHAIN (tem);
	}
      if (tem)
	{
	  if (protect && TREE_TYPE (tem))
	    {
	      error (TREE_STRING_POINTER (TREE_TYPE (tem)),
		     IDENTIFIER_POINTER (name),
		     TYPE_NAME_STRING (DECL_FIELD_CONTEXT (TREE_VALUE (tem))));
	      return error_mark_node;
	    }
	  if (TREE_VALUE (tem) == NULL_TREE)
	    memoized_fast_rejects[0] += 1;
	  else
	    memoized_fast_finds[0] += 1;
	  return TREE_VALUE (tem);
	}
    }

#ifdef GATHER_STATISTICS
  n_calls_lookup_field++;
#endif
  if (protect && flag_memoize_lookups && ! global_bindings_p ())
    entry = make_memoized_table_entry (type, name, 0);
  else
    entry = 0;

  rval = lookup_field_1 (type, name);

  if (rval || lookup_fnfields_here (type, name) >= 0)
    {
      if (rval)
	{
	  if (want_type)
	    {
	      if (TREE_CODE (rval) != TYPE_DECL)
		{
		  rval = purpose_member (name, CLASSTYPE_TAGS (type));
		  if (rval)
		    rval = TYPE_MAIN_DECL (TREE_VALUE (rval));
		}
	    }
	  else
	    {
	      if (TREE_CODE (rval) == TYPE_DECL
		  && lookup_fnfields_here (type, name) >= 0)
		rval = NULL_TREE;
	    }
	}

      if (protect && rval)
	{
	  if (TREE_PRIVATE (rval) | TREE_PROTECTED (rval))
	    this_v = compute_access (basetype_path, rval);
	  if (TREE_CODE (rval) == CONST_DECL)
	    {
	      if (this_v == access_private)
		errstr = "enum `%D' is a private value of class `%T'";
	      else if (this_v == access_protected)
		errstr = "enum `%D' is a protected value of class `%T'";
	    }
	  else
	    {
	      if (this_v == access_private)
		errstr = "member `%D' is a private member of class `%T'";
	      else if (this_v == access_protected)
		errstr = "member `%D' is a protected member of class `%T'";
	    }
	}

      if (entry)
	{
	  if (errstr)
	    {
	      /* This depends on behavior of lookup_field_1!  */
	      tree error_string = my_build_string (errstr);
	      TREE_TYPE (entry) = error_string;
	    }
	  else
	    {
	      /* Let entry know there is no problem with this access.  */
	      TREE_TYPE (entry) = NULL_TREE;
	    }
	  TREE_VALUE (entry) = rval;
	}

      if (errstr && protect)
	{
	  cp_error (errstr, name, type);
	  return error_mark_node;
	}
      return rval;
    }

  basetype_chain = build_tree_list (NULL_TREE, basetype_path);
  TREE_VIA_PUBLIC (basetype_chain) = TREE_VIA_PUBLIC (basetype_path);
  TREE_VIA_PROTECTED (basetype_chain) = TREE_VIA_PROTECTED (basetype_path);
  TREE_VIA_VIRTUAL (basetype_chain) = TREE_VIA_VIRTUAL (basetype_path);

  /* The ambiguity check relies upon breadth first searching. */

  search_stack = push_search_level (search_stack, &search_obstack);
  binfo = basetype_path;
  binfo_h = binfo;

  while (1)
    {
      tree binfos = BINFO_BASETYPES (binfo);
      int i, n_baselinks = binfos ? TREE_VEC_LENGTH (binfos) : 0;
      tree nval;

      /* Process and/or queue base types.  */
      for (i = 0; i < n_baselinks; i++)
	{
	  tree base_binfo = TREE_VEC_ELT (binfos, i);
	  if (BINFO_FIELDS_MARKED (base_binfo) == 0)
	    {
	      tree btypes;

	      SET_BINFO_FIELDS_MARKED (base_binfo);
	      btypes = my_tree_cons (NULL_TREE, base_binfo, basetype_chain);
	      TREE_VIA_PUBLIC (btypes) = TREE_VIA_PUBLIC (base_binfo);
	      TREE_VIA_PROTECTED (btypes) = TREE_VIA_PROTECTED (base_binfo);
	      TREE_VIA_VIRTUAL (btypes) = TREE_VIA_VIRTUAL (base_binfo);
	      if (TREE_VIA_VIRTUAL (base_binfo))
		btypes = tree_cons (NULL_TREE,
				    TYPE_BINFO (BINFO_TYPE (TREE_VEC_ELT (BINFO_BASETYPES (binfo_h), i))),
				    btypes);
	      else
		btypes = tree_cons (NULL_TREE,
				    TREE_VEC_ELT (BINFO_BASETYPES (binfo_h), i),
				    btypes);
	      obstack_ptr_grow (&search_obstack, btypes);
	      tail += 1;
	      if (tail >= search_stack->limit)
		my_friendly_abort (98);
	    }
	}

      /* Process head of queue, if one exists.  */
      if (head >= tail)
	break;

      basetype_chain = search_stack->first[head++];
      binfo_h = TREE_VALUE (basetype_chain);
      basetype_chain = TREE_CHAIN (basetype_chain);
      basetype_path = TREE_VALUE (basetype_chain);
      if (TREE_CHAIN (basetype_chain))
	BINFO_INHERITANCE_CHAIN (basetype_path) = TREE_VALUE (TREE_CHAIN (basetype_chain));
      else
	BINFO_INHERITANCE_CHAIN (basetype_path) = NULL_TREE;

      binfo = basetype_path;
      type = BINFO_TYPE (binfo);

      /* See if we can find NAME in TYPE.  If RVAL is nonzero,
	 and we do find NAME in TYPE, verify that such a second
	 sighting is in fact valid.  */

      nval = lookup_field_1 (type, name);

      if (nval || lookup_fnfields_here (type, name)>=0)
	{
	  if (nval && nval == rval && SHARED_MEMBER_P (nval))
	    {
	      /* This is ok, the member found is the same [class.ambig] */
	    }
	  else if (rval_binfo && hides (rval_binfo_h, binfo_h))
	    {
	      /* This is ok, the member found is in rval_binfo, not
		 here (binfo). */
	    }
	  else if (rval_binfo==NULL_TREE || hides (binfo_h, rval_binfo_h))
	    {
	      /* This is ok, the member found is here (binfo), not in
		 rval_binfo. */
	      if (nval)
		{
		  rval = nval;
		  if (entry || protect)
		    this_v = compute_access (basetype_path, rval);
		  /* These may look ambiguous, but they really are not.  */
		  if (vbase_name_p)
		    break;
		}
	      else
		{
		  /* Undo finding it before, as something else hides it. */
		  rval = NULL_TREE;
		}
	      rval_binfo = binfo;
	      rval_binfo_h = binfo_h;
	    }
	  else
	    {
	      /* This is ambiguous. */
	      errstr = "request for member `%D' is ambiguous";
	      protect = 2;
	      break;
	    }
	}
    }
  {
    tree *tp = search_stack->first;
    tree *search_tail = tp + tail;

    if (entry)
      TREE_VALUE (entry) = rval;

    if (rval_binfo)
      {
	type = BINFO_TYPE (rval_binfo);

	if (rval)
	  {
	    if (want_type)
	      {
		if (TREE_CODE (rval) != TYPE_DECL)
		  {
		    rval = purpose_member (name, CLASSTYPE_TAGS (type));
		    if (rval)
		      rval = TYPE_MAIN_DECL (TREE_VALUE (rval));
		  }
	      }
	    else
	      {
		if (TREE_CODE (rval) == TYPE_DECL
		    && lookup_fnfields_here (type, name) >= 0)
		  rval = NULL_TREE;
	      }
	  }
      }

    if (rval == NULL_TREE)
      errstr = 0;

    /* If this FIELD_DECL defines its own access level, deal with that.  */