New file, derived from bison's file by the same name.

diff --git a/m4/warning.m4 b/m4/warning.m4
new file mode 100644 (file)
index 0000000..ba49e68
--- /dev/null
+++ b/m4/warning.m4
@@ -0,0 +1,34 @@
+# serial 3
+# Find valid warning flags for the C Compiler.           -*-Autoconf-*-
+#
+# Copyright (C) 2001, 2002, 2006 Free Software Foundation, Inc.
+#
+# 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 2 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, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301  USA
+
+# Written by Jesse Thilo.
+
+AC_DEFUN([gl_WARNING_CFLAGS],
+  [AC_MSG_CHECKING(whether compiler accepts $1)
+   AC_SUBST(WARNING_CFLAGS)
+   ac_save_CFLAGS="$CFLAGS"
+   CFLAGS="$CFLAGS $1"
+   AC_TRY_COMPILE(,
+    [int x;],
+    WARNING_CFLAGS="$WARNING_CFLAGS $1"
+    AC_MSG_RESULT(yes),
+    AC_MSG_RESULT(no))
+  CFLAGS="$ac_save_CFLAGS"
+ ])