--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/spellcheck-tree.h	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,77 @@
+/* Find near-matches for identifiers.
+   Copyright (C) 2015-2017 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#ifndef GCC_SPELLCHECK_TREE_H
+#define GCC_SPELLCHECK_TREE_H
+
+#include "spellcheck.h"
+
+/* spellcheck-tree.c  */
+
+extern edit_distance_t
+levenshtein_distance (tree ident_s, tree ident_t);
+
+extern tree
+find_closest_identifier (tree target, const auto_vec<tree> *candidates);
+
+/* Specialization of edit_distance_traits for identifiers.  */
+
+template <>
+struct edit_distance_traits<tree>
+{
+  static size_t get_length (tree id)
+  {
+    gcc_assert (TREE_CODE (id) == IDENTIFIER_NODE);
+    return IDENTIFIER_LENGTH (id);
+  }
+
+  static const char *get_string (tree id)
+  {
+    gcc_assert (TREE_CODE (id) == IDENTIFIER_NODE);
+    return IDENTIFIER_POINTER (id);
+  }
+};
+
+/* Specialization of edit_distance_traits for preprocessor macros.  */
+
+template <>
+struct edit_distance_traits<cpp_hashnode *>
+{
+  static size_t get_length (cpp_hashnode *hashnode)
+  {
+    return hashnode->ident.len;
+  }
+
+  static const char *get_string (cpp_hashnode *hashnode)
+  {
+    return (const char *)hashnode->ident.str;
+  }
+};
+
+/* Specialization of best_match<> for finding the closest preprocessor
+   macro to a given identifier.  */
+
+class best_macro_match : public best_match<tree, cpp_hashnode *>
+{
+ public:
+  best_macro_match (tree goal, edit_distance_t best_distance_so_far,
+		    cpp_reader *reader);
+};
+
+#endif  /* GCC_SPELLCHECK_TREE_H  */