improve the check for a working C compiler

[Paul Eggert]

This improves the check for a working C compiler; one of Nelson
H. F. Beebe's tests actually failed because his Portland Group C
compiler wasn't properly configured.  I think this finishes up all of
Beebe's reports, so I plan to generate Bison test version 2.1a soon.

2006-02-11  Paul Eggert  <address@hidden>

        * m4/c-working.m4: New file.
        * configure.ac (BISON_TEST_FOR_WORKING_C_COMPILER): Use it.

--- configure.ac        20 Jan 2006 00:08:30 -0000      1.62
+++ configure.ac        12 Feb 2006 02:13:09 -0000
@@ -64,6 +64,8 @@ if test "${enableval}" = yes; then
   AC_DEFINE([lint], 1, [Define to 1 if the compiler is checking for lint.])
 fi
 
+BISON_TEST_FOR_WORKING_C_COMPILER
+
 AC_ARG_ENABLE([yacc],
   [AC_HELP_STRING([--disable-yacc],
      [do not build a yacc command or an -ly library])],
--- /dev/null   2005-09-24 22:00:15.000000000 -0700
+++ m4/c-working.m4     2006-02-11 18:05:24.000000000 -0800
@@ -0,0 +1,29 @@
+# Sanity test a C compiler.
+
+# Copyright (C) 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 Paul Eggert.
+
+AC_DEFUN([BISON_TEST_FOR_WORKING_C_COMPILER], [
+  AC_COMPILE_IFELSE(
+    [AC_LANG_PROGRAM(
+       [[#include <limits.h>
+        int test_array[CHAR_BIT];]])],
+    [],
+    [AC_MSG_FAILURE([cannot compile a simple C program])])
+])