iswblank: Detect declaration correctly.

[gnulib.git] / m4 / iswblank.m4

diff --git a/m4/iswblank.m4 b/m4/iswblank.m4
index 275f131..750e1d3 100644 (file)
--- a/m4/iswblank.m4
+++ b/m4/iswblank.m4
@@ -1,4 +1,4 @@
-# iswblank.m4 serial 3
+# iswblank.m4 serial 4
 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,
@@ -11,7 +11,17 @@ AC_DEFUN([gl_FUNC_ISWBLANK],
   dnl Persuade glibc <wctype.h> to declare iswblank().
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
   AC_CHECK_FUNCS_ONCE([iswblank])
-  AC_CHECK_DECLS_ONCE([iswblank])
+  AC_CHECK_DECLS([iswblank], , , [[
+/* 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>
+#include <wctype.h>
+]])
   if test $ac_cv_func_iswblank = no; then
     HAVE_ISWBLANK=0
     if test $ac_cv_have_decl_iswblank = yes; then