--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+2011-02-05  Bruno Haible  <bruno@clisp.org>
+
+	New module 'wmemcmp'.
+	* modules/wmemcmp: New file.
+	* lib/wchar.in.h (wmemcmp): New declaration.
+	* lib/wmemcmp.c: New file.
+	* lib/wmemcmp-impl.h: New file, from libutf8 with modifications.
+	* m4/wmemcmp.m4: New file.
+	* m4/wchar_h.m4 (gl_WCHAR_H): Test whether wmemcmp is declared.
+	(gl_WCHAR_H_DEFAULTS): Initialize GNULIB_WMEMCMP, HAVE_WMEMCMP.
+	* modules/wchar (Makefile.am): Substitute GNULIB_WMEMCMP, HAVE_WMEMCMP.
+	* tests/test-wchar-c++.cc: Test the declaration of wmemcmp.
+	* doc/posix-functions/wmemcmp.texi: Mention the new module.
+
 2011-02-07  Jim Meyering  <meyering@redhat.com>
 
 	di-set, ino-map: new modules, from coreutils

--- a/doc/posix-functions/wmemcmp.texi
+++ b/doc/posix-functions/wmemcmp.texi
@@ -4,18 +4,18 @@
 
 POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/wmemcmp.html}
 
-Gnulib module: ---
+Gnulib module: wmemcmp
 
 Portability problems fixed by Gnulib:
 @itemize
+@item
+This function is missing on some platforms:
+HP-UX 11.00, IRIX 6.5, Solaris 2.6, Interix 3.5.
 @end itemize
 
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on some platforms:
-HP-UX 11.00, IRIX 6.5, Solaris 2.6, Interix 3.5.
-@item
 On AIX and Windows platforms, @code{wchar_t} is a 16-bit type and therefore cannot
 accommodate all Unicode characters.
 @end itemize

--- a/lib/wchar.in.h
+++ b/lib/wchar.in.h
@@ -446,6 +446,24 @@
 #endif
 
 
+/* Compare N wide characters of S1 and S2.  */
+#if @GNULIB_WMEMCMP@
+# if !@HAVE_WMEMCMP@
+_GL_FUNCDECL_SYS (wmemcmp, int,
+                  (const wchar_t *s1, const wchar_t *s2, size_t n));
+# endif
+_GL_CXXALIAS_SYS (wmemcmp, int,
+                  (const wchar_t *s1, const wchar_t *s2, size_t n));
+_GL_CXXALIASWARN (wmemcmp);
+#elif defined GNULIB_POSIXCHECK
+# undef wmemcmp
+# if HAVE_RAW_DECL_WMEMCMP
+_GL_WARN_ON_USE (wmemcmp, "wmemcmp is unportable - "
+                 "use gnulib module wmemcmp for portability");
+# endif
+#endif
+
+
 #endif /* _GL_WCHAR_H */
 #endif /* _GL_WCHAR_H */
 #endif

new file mode 100644
--- /dev/null
+++ b/lib/wmemcmp-impl.h
@@ -0,0 +1,35 @@
+/* Compare wide character arrays.
+   Copyright (C) 1999, 2011 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 1999.
+
+   This program 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 of the License, or
+   (at your option) any later version.
+
+   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+int
+wmemcmp (const wchar_t *s1, const wchar_t *s2, size_t n)
+{
+  for (; n > 0;)
+    {
+      wchar_t wc1 = *s1++;
+      wchar_t wc2 = *s2++;
+      if (wc1 == wc2)
+        {
+          n--;
+          continue;
+        }
+      /* Note that wc1 and wc2 each have at most 31 bits.  */
+      return (int)wc1 - (int)wc2;
+             /* > 0 if wc1 > wc2, < 0 if wc1 < wc2.  */
+    }
+  return 0;
+}

new file mode 100644
--- /dev/null
+++ b/lib/wmemcmp.c
@@ -0,0 +1,23 @@
+/* Compare wide character arrays.
+   Copyright (C) 2011 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2011.
+
+   This program 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 of the License, or
+   (at your option) any later version.
+
+   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <wchar.h>
+
+#include "wmemcmp-impl.h"

--- a/m4/wchar_h.m4
+++ b/m4/wchar_h.m4
@@ -50,7 +50,7 @@
 #include <wchar.h>
     ]],
     [btowc wctob mbsinit mbrtowc mbrlen mbsrtowcs mbsnrtowcs wcrtomb
-     wcsrtombs wcsnrtombs wcwidth wmemchr
+     wcsrtombs wcsnrtombs wcwidth wmemchr wmemcmp
     ])
 ])
 
@@ -146,6 +146,7 @@
   GNULIB_WCSNRTOMBS=0; AC_SUBST([GNULIB_WCSNRTOMBS])
   GNULIB_WCWIDTH=0;    AC_SUBST([GNULIB_WCWIDTH])
   GNULIB_WMEMCHR=0;    AC_SUBST([GNULIB_WMEMCHR])
+  GNULIB_WMEMCMP=0;    AC_SUBST([GNULIB_WMEMCMP])
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_BTOWC=1;         AC_SUBST([HAVE_BTOWC])
   HAVE_MBSINIT=1;       AC_SUBST([HAVE_MBSINIT])
@@ -157,6 +158,7 @@
   HAVE_WCSRTOMBS=1;     AC_SUBST([HAVE_WCSRTOMBS])
   HAVE_WCSNRTOMBS=1;    AC_SUBST([HAVE_WCSNRTOMBS])
   HAVE_WMEMCHR=1;       AC_SUBST([HAVE_WMEMCHR])
+  HAVE_WMEMCMP=1;       AC_SUBST([HAVE_WMEMCMP])
   HAVE_DECL_WCTOB=1;    AC_SUBST([HAVE_DECL_WCTOB])
   HAVE_DECL_WCWIDTH=1;  AC_SUBST([HAVE_DECL_WCWIDTH])
   REPLACE_MBSTATE_T=0;  AC_SUBST([REPLACE_MBSTATE_T])

new file mode 100644
--- /dev/null
+++ b/m4/wmemcmp.m4
@@ -0,0 +1,15 @@
+# wmemcmp.m4 serial 1
+dnl Copyright (C) 2011 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.
+
+AC_DEFUN([gl_FUNC_WMEMCMP],
+[
+  AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
+  AC_CHECK_FUNCS_ONCE([wmemcmp])
+  if test $ac_cv_func_wmemcmp = no; then
+    HAVE_WMEMCMP=0
+    AC_LIBOBJ([wmemcmp])
+  fi
+])

--- a/modules/wchar
+++ b/modules/wchar
@@ -42,6 +42,7 @@
 	      -e 's|@''GNULIB_WCSNRTOMBS''@|$(GNULIB_WCSNRTOMBS)|g' \
 	      -e 's|@''GNULIB_WCWIDTH''@|$(GNULIB_WCWIDTH)|g' \
 	      -e 's|@''GNULIB_WMEMCHR''@|$(GNULIB_WMEMCHR)|g' \
+	      -e 's|@''GNULIB_WMEMCMP''@|$(GNULIB_WMEMCMP)|g' \
 	      -e 's|@''HAVE_WINT_T''@|$(HAVE_WINT_T)|g' \
 	      -e 's|@''HAVE_BTOWC''@|$(HAVE_BTOWC)|g' \
 	      -e 's|@''HAVE_MBSINIT''@|$(HAVE_MBSINIT)|g' \
@@ -53,6 +54,7 @@
 	      -e 's|@''HAVE_WCSRTOMBS''@|$(HAVE_WCSRTOMBS)|g' \
 	      -e 's|@''HAVE_WCSNRTOMBS''@|$(HAVE_WCSNRTOMBS)|g' \
 	      -e 's|@''HAVE_WMEMCHR''@|$(HAVE_WMEMCHR)|g' \
+	      -e 's|@''HAVE_WMEMCMP''@|$(HAVE_WMEMCMP)|g' \
 	      -e 's|@''HAVE_DECL_WCTOB''@|$(HAVE_DECL_WCTOB)|g' \
 	      -e 's|@''HAVE_DECL_WCWIDTH''@|$(HAVE_DECL_WCWIDTH)|g' \
 	      -e 's|@''REPLACE_MBSTATE_T''@|$(REPLACE_MBSTATE_T)|g' \

new file mode 100644
--- /dev/null
+++ b/modules/wmemcmp
@@ -0,0 +1,25 @@
+Description:
+wmemcmp() function: compare wide character arrays.
+
+Files:
+lib/wmemcmp.c
+lib/wmemcmp-impl.h
+m4/wmemcmp.m4
+
+Depends-on:
+wchar
+
+configure.ac:
+gl_FUNC_WMEMCMP
+gl_WCHAR_MODULE_INDICATOR([wmemcmp])
+
+Makefile.am:
+
+Include:
+<wchar.h>
+
+License:
+LGPL
+
+Maintainer:
+Bruno Haible

--- a/tests/test-wchar-c++.cc
+++ b/tests/test-wchar-c++.cc
@@ -80,6 +80,11 @@
                  (const wchar_t *, wchar_t, size_t));
 #endif
 
+#if GNULIB_TEST_WMEMCMP
+SIGNATURE_CHECK (GNULIB_NAMESPACE::wmemcmp, int,
+                 (const wchar_t *, const wchar_t *, size_t));
+#endif
+
 
 int
 main ()