--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/substring-locations.h	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,102 @@
+/* Source locations within string literals.
+   Copyright (C) 2016-2017 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_SUBSTRING_LOCATIONS_H
+#define GCC_SUBSTRING_LOCATIONS_H
+
+/* The substring_loc class encapsulates information on the source location
+   of a range of characters within a STRING_CST.
+
+   If needed by a diagnostic, the actual location_t of the substring_loc
+   can be calculated by calling its get_location method.  This calls a
+   langhook, since this is inherently frontend-specific.  For the C family
+   of frontends, it calls back into libcpp to reparse the strings.  This
+   gets the location information "on demand", rather than storing the
+   location information in the initial lex for every string.  Thus the
+   substring_loc can also be thought of as a deferred call into libcpp,
+   to allow the non-trivial work of reparsing the string to be delayed
+   until we actually need it (to emit a diagnostic for a particular range
+   of characters).
+
+   substring_loc::get_location returns NULL if it succeeds, or an
+   error message if it fails.  Error messages are intended for GCC
+   developers (to help debugging) rather than for end-users.
+
+   The easiest way to use a substring_loc is via the format_warning_* APIs,
+   which gracefully handle failure of substring_loc::get_location by using
+   the location of the string as a whole if substring-information is
+   unavailable.  */
+
+class substring_loc
+{
+ public:
+  /* Constructor.  FMT_STRING_LOC is the location of the string as
+     a whole.  STRING_TYPE is the type of the string.  It should be an
+     ARRAY_TYPE of INTEGER_TYPE, or a POINTER_TYPE to such an ARRAY_TYPE.
+     CARET_IDX, START_IDX, and END_IDX are offsets from the start
+     of the string data.  */
+  substring_loc (location_t fmt_string_loc, tree string_type,
+		 int caret_idx, int start_idx, int end_idx)
+  : m_fmt_string_loc (fmt_string_loc), m_string_type (string_type),
+    m_caret_idx (caret_idx), m_start_idx (start_idx), m_end_idx (end_idx) {}
+
+  void set_caret_index (int caret_idx) { m_caret_idx = caret_idx; }
+
+  const char *get_location (location_t *out_loc) const;
+
+  location_t get_fmt_string_loc () const { return m_fmt_string_loc; }
+  tree get_string_type () const { return m_string_type; }
+  int get_caret_idx () const { return m_caret_idx; }
+  int get_start_idx () const { return m_start_idx; }
+  int get_end_idx () const { return m_end_idx; }
+
+ private:
+  location_t m_fmt_string_loc;
+  tree m_string_type;
+  int m_caret_idx;
+  int m_start_idx;
+  int m_end_idx;
+};
+
+/* Functions for emitting a warning about a format string.  */
+
+extern bool format_warning_va (const substring_loc &fmt_loc,
+			       location_t param_loc,
+			       const char *corrected_substring,
+			       int opt, const char *gmsgid, va_list *ap)
+  ATTRIBUTE_GCC_DIAG (5,0);
+
+extern bool format_warning_at_substring (const substring_loc &fmt_loc,
+					 location_t param_loc,
+					 const char *corrected_substring,
+					 int opt, const char *gmsgid, ...)
+  ATTRIBUTE_GCC_DIAG (5,0);
+
+/* Implementation detail, for use when implementing
+   LANG_HOOKS_GET_SUBSTRING_LOCATION.  */
+
+extern const char *get_source_location_for_substring (cpp_reader *pfile,
+						      string_concat_db *concats,
+						      location_t strloc,
+						      enum cpp_ttype type,
+						      int caret_idx,
+						      int start_idx, int end_idx,
+						      location_t *out_loc);
+
+#endif /* ! GCC_SUBSTRING_LOCATIONS_H */