Index: lib/string_.h
===================================================================
--- lib/string_.h.orig	2007-09-01 16:44:18.805051431 +0000
+++ lib/string_.h	2007-09-01 16:45:28.184147958 +0000
@@ -19,7 +19,11 @@
 #ifndef _GL_STRING_H
 
 /* The include_next requires a split double-inclusion guard.  */
+#ifdef __cplusplus
address@hidden@ @NEXT_STRING_H_CXX@
+#else
 address@hidden@ @NEXT_STRING_H@
+#endif
 
 #ifndef _GL_STRING_H
 #define _GL_STRING_H
Index: m4/include_next.m4
===================================================================
--- m4/include_next.m4.orig	2007-09-01 16:44:18.868161169 +0000
+++ m4/include_next.m4	2007-09-01 16:45:28.193491133 +0000
@@ -105,3 +105,61 @@
        [AS_VAR_GET([gl_next_header])])
      AS_VAR_POPDEF([gl_next_header])])
 ])
+
+# gl_CHECK_NEXT_HEADERS_CXX(HEADER1 HEADER2 ...)
+# ------------------------------------------
+# For each arg foo.h, if #include_next works, define NEXT_FOO_H to be
+# '<foo.h>'; otherwise define it to be
+# '"///usr/include/foo.h"', or whatever other absolute file name is suitable.
+# That way, a header file with the following line:
+#	address@hidden@ @NEXT_FOO_H_CXX@
+# behaves (after sed substitution) as if it contained
+#	#include_next <foo.h>
+# even if the compiler does not support include_next.
+# The three "///" are to pacify Sun C 5.8, which otherwise would say
+# "warning: #include of /usr/include/... may be non-portable".
+# Use `""', not `<>', so that the /// cannot be confused with a C99 comment.
+AC_DEFUN([gl_CHECK_NEXT_HEADERS_CXX],
+[
+  AC_REQUIRE([gl_INCLUDE_NEXT])
+  AC_CHECK_HEADERS_ONCE([$1])
+
+  AC_FOREACH([gl_HEADER_NAME], [$1],
+    [AS_VAR_PUSHDEF([gl_next_header],
+		    [gl_cv_next_]m4_quote(m4_defn([gl_HEADER_NAME]))[_cxx])
+     AC_LANG_PUSH([C++])
+     if test $gl_cv_have_include_next = yes; then
+       AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
+     else
+       AC_CACHE_CHECK(
+	 [absolute name of C++ <]m4_quote(m4_defn([gl_HEADER_NAME]))[>],
+	 m4_quote(m4_defn([gl_next_header])),
+	 [AS_VAR_PUSHDEF([gl_header_exists],
+			 [ac_cv_header_]m4_quote(m4_defn([gl_HEADER_NAME])))
+	  if test AS_VAR_GET(gl_header_exists) = yes; then
+	    AC_LANG_CONFTEST(
+	      [AC_LANG_SOURCE(
+		 [[#include <]]m4_dquote(m4_defn([gl_HEADER_NAME]))[[>]]
+	       )])
+	    dnl eval is necessary to expand ac_cpp.
+	    dnl Ultrix and Pyramid sh refuse to redirect output of eval,
+	    dnl so use subshell.
+	    AS_VAR_SET([gl_next_header],
+	      ['"'`(eval "$ac_cpp conftest.$ac_ext") 2>&AS_MESSAGE_LOG_FD |
+	       sed -n '\#/]m4_quote(m4_defn([gl_HEADER_NAME]))[#{
+		 s#.*"\(.*/]m4_quote(m4_defn([gl_HEADER_NAME]))[\)".*#\1#
+		 s#^/[^/]#//&#
+		 p
+		 q
+	       }'`'"'])
+	  else
+	    AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
+	  fi
+	  AS_VAR_POPDEF([gl_header_exists])])
+     fi
+     AC_SUBST(
+       AS_TR_CPP([NEXT_]m4_quote(m4_defn([gl_HEADER_NAME]))[_CXX]),
+       [AS_VAR_GET([gl_next_header])])
+     AC_LANG_POP([C++])
+     AS_VAR_POPDEF([gl_next_header])])
+])
Index: m4/string_h.m4
===================================================================
--- m4/string_h.m4.orig	2007-09-01 16:44:18.878137121 +0000
+++ m4/string_h.m4	2007-09-01 16:45:28.200304234 +0000
@@ -19,6 +19,8 @@
   AC_REQUIRE([AC_C_RESTRICT])
   AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
   gl_CHECK_NEXT_HEADERS([string.h])
+  AC_PROVIDE_IFELSE([AC_PROG_CXX],
+    [gl_CHECK_NEXT_HEADERS_CXX([string.h])])
 ])
 
 AC_DEFUN([gl_STRING_MODULE_INDICATOR],