From 426e29f364b47d640df072e1a949caae688d1578 Mon Sep 17 00:00:00 2001
From: Bruno Haible <bruno@clisp.org>
Date: Tue, 4 Oct 2011 01:49:09 +0200
Subject: [PATCH] wmemcmp: Support for MSVC.

* m4/wmemcmp.m4 (gl_FUNC_WMEMCMP): Use a small test program to test
whether wmemcmp() exists.
---
 ChangeLog     |  6 ++++++
 m4/wmemcmp.m4 | 24 +++++++++++++++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index f1d7592f8..861eb7d6d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2011-10-03  Bruno Haible  <bruno@clisp.org>
 
+	wmemcmp: Support for MSVC.
+	* m4/wmemcmp.m4 (gl_FUNC_WMEMCMP): Use a small test program to test
+	whether wmemcmp() exists.
+
+2011-10-03  Bruno Haible  <bruno@clisp.org>
+
 	wmemchr: Support for MSVC.
 	* m4/wmemchr.m4 (gl_FUNC_WMEMCHR): Use a small test program to test
 	whether wmemchr() exists.
diff --git a/m4/wmemcmp.m4 b/m4/wmemcmp.m4
index ec86e4222..4e6e34171 100644
--- a/m4/wmemcmp.m4
+++ b/m4/wmemcmp.m4
@@ -1,4 +1,4 @@
-# wmemcmp.m4 serial 2
+# wmemcmp.m4 serial 3
 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,
@@ -7,8 +7,26 @@ 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
+  dnl We cannot use AC_CHECK_FUNCS here, because the MSVC 9 header files
+  dnl provide this function as an inline function definition.
+  AC_CACHE_CHECK([for wmemcmp], [gl_cv_func_wmemcmp],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM([[
+/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
+   <wchar.h>.
+   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be included
+   before <wchar.h>.  */
+#include <stddef.h>
+#include <stdio.h>
+#include <time.h>
+#include <wchar.h>
+]],
+          [[return ! wmemcmp ((const wchar_t *) 0, (const wchar_t *) 0, 0);]])
+       ],
+       [gl_cv_func_wmemcmp=yes],
+       [gl_cv_func_wmemcmp=no])
+    ])
+  if test $gl_cv_func_wmemcmp = no; then
     HAVE_WMEMCMP=0
   fi
 ])
-- 
2.11.0