--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2006-06-28  Bruno Haible  <bruno@clisp.org>
+
+	* modules/wcwidth (Files): Add m4/wchar_t.m4.
+
 2006-06-28  Eric Blake  <ebb9@byu.net>
 
 	* modules/wcwidth: New file.

--- a/lib/ChangeLog
+++ b/lib/ChangeLog
@@ -1,3 +1,9 @@
+2006-06-28  Bruno Haible  <bruno@clisp.org>
+
+	* wcwidth.h: Declare nothing if !HAVE_WCHAR_T. Provide a fallback
+	declaration for wcwidth.
+	* mbswidth.c: Restore the includes of <wchar.h> and <wctypes.h>.
+
 2006-06-28  Eric Blake  <ebb9@byu.net>
 
 	* xvasprintf.h: Fix comments.

--- a/lib/mbswidth.c
+++ b/lib/mbswidth.c
@@ -32,10 +32,24 @@
 /* Get isprint().  */
 #include <ctype.h>
 
-/* Get mbstate_t, mbrtowc(), mbsinit(), wcwidth().  */
+/* Get mbstate_t, mbrtowc(), mbsinit().  */
+#if HAVE_WCHAR_H
+/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
+   <wchar.h>.
+   BSD/OS 4.1 has a bug: <stdio.h> and <time.h> must be included before
+   <wchar.h>.  */
+# include <stdio.h>
+# include <time.h>
+# include <wchar.h>
+#endif
+
+/* Get wcwidth().  */
 #include "wcwidth.h"
 
 /* Get iswcntrl().  */
+#if HAVE_WCTYPE_H
+# include <wctype.h>
+#endif
 #if !defined iswcntrl && !HAVE_ISWCNTRL
 # define iswcntrl(wc) 0
 #endif

--- a/lib/wcwidth.h
+++ b/lib/wcwidth.h
@@ -18,26 +18,32 @@
 #ifndef _gl_WCWIDTH_H
 #define _gl_WCWIDTH_H
 
+#if HAVE_WCHAR_T
+
 /* Get wcwidth if available, along with wchar_t.  */
-#if HAVE_WCHAR_H
+# if HAVE_WCHAR_H
 /* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
    <wchar.h>.
    BSD/OS 4.1 has a bug: <stdio.h> and <time.h> must be included before
    <wchar.h>.  */
-# include <stdio.h>
-# include <time.h>
-# include <wchar.h>
-#endif
+#  include <stdio.h>
+#  include <time.h>
+#  include <wchar.h>
+# endif
 
 /* Get iswprint.  */
-#if HAVE_WCTYPE_H
-# include <wctype.h>
-#endif
-#if !defined iswprint && !HAVE_ISWPRINT
-# define iswprint(wc) 1
-#endif
+# if HAVE_WCTYPE_H
+#  include <wctype.h>
+# endif
+# if !defined iswprint && !HAVE_ISWPRINT
+#  define iswprint(wc) 1
+# endif
 
-#if !defined wcwidth && !HAVE_WCWIDTH
+# ifndef HAVE_DECL_WCWIDTH
+"this configure-time declaration test was not run"
+# endif
+# ifndef wcwidth
+#  if !HAVE_WCWIDTH
 
 /* wcwidth doesn't exist, so assume all printable characters have
    width 1.  */
@@ -47,6 +53,18 @@
   return wc == 0 ? 0 : iswprint (wc) ? 1 : -1;
 }
 
-#endif
+#  elif !HAVE_DECL_WCWIDTH
+
+/* wcwidth exists but is not declared.  */
+extern
+#   ifdef __cplusplus
+"C"
+#   endif
+int wcwidth (int /* actually wchar_t */);
+
+#  endif
+# endif
+
+#endif /* HAVE_WCHAR_H */
 
 #endif /* _gl_WCWIDTH_H */

--- a/m4/ChangeLog
+++ b/m4/ChangeLog
@@ -1,3 +1,8 @@
+2006-06-28  Bruno Haible  <bruno@clisp.org>
+
+	* wcwidth.m4 (gl_FUNC_WCWIDTH): Also require AC_C_INLINE and
+	gt_TYPE_WCHAR_T.
+
 2006-06-28  Eric Blake  <ebb9@byu.net>
 
 	* mbswidth.m4 (gl_MBSDWIDTH): Move wcwidth from here...

--- a/m4/wcwidth.m4
+++ b/m4/wcwidth.m4
@@ -1,17 +1,20 @@
-# wcwidth.m4 serial 1
+# wcwidth.m4 serial 2
 dnl Copyright (C) 2006 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
 
-dnl autoconf tests required for use of mbswidth.c
+AC_DEFUN([gl_FUNC_WCWIDTH],
+[
+  dnl Persuade glibc <wchar.h> to declare wcwidth().
+  AC_REQUIRE([AC_GNU_SOURCE])
 
-AC_DEFUN([gl_FUNC_WCWIDTH],
-[ AC_CHECK_HEADERS_ONCE([wchar.h wctype.h])
+  AC_REQUIRE([AC_C_INLINE])
+  AC_REQUIRE([gt_TYPE_WCHAR_T])
+
+  AC_CHECK_HEADERS_ONCE([wchar.h wctype.h])
   AC_CHECK_FUNCS_ONCE([iswprint wcwidth])
 
-  AC_REQUIRE([AC_GNU_SOURCE])
-
   AC_CACHE_CHECK([whether wcwidth is declared], [ac_cv_have_decl_wcwidth],
     [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([
 /* AIX 3.2.5 declares wcwidth in <string.h>. */

--- a/modules/wcwidth
+++ b/modules/wcwidth
@@ -4,6 +4,7 @@
 Files:
 lib/wcwidth.h
 m4/wcwidth.m4
+m4/wchar_t.m4
 
 Depends-on: