Add configure warning to check for bison version >= 1.875.

configure

@@ -4424,6 +4424,19 @@ fi
   test -n "$YACC" && break
 done
 
+
+if test "$YACC"; then
+  if bison --version | sed q | $AWK '{ if ($4 < 1.875) exit 0; else exit 1;}'; then
+    { echo "$as_me:$LINENO: WARNING:
+*** The installed version of Bison is too old.  PostgreSQL needs
+*** Bison version 1.875 or later." >&5
+echo "$as_me: WARNING:
+*** The installed version of Bison is too old.  PostgreSQL needs
+*** Bison version 1.875 or later." >&2;}
+    unset YACC
+  fi
+fi
+
 if test -z "$YACC"; then
   { echo "$as_me:$LINENO: WARNING:
 *** Without Bison you will not be able to build PostgreSQL from CVS or

configure.in

@@ -1,5 +1,5 @@
 dnl Process this file with autoconf to produce a configure script.
-dnl $Header: /cvsroot/pgsql/configure.in,v 1.254 2003/05/27 16:36:50 momjian Exp $
+dnl $Header: /cvsroot/pgsql/configure.in,v 1.255 2003/06/06 19:11:55 momjian Exp $
 dnl
 dnl Developers, please strive to achieve this order:
 dnl
@@ -585,6 +585,16 @@ AC_PATH_PROG(TAR, tar)
 PGAC_CHECK_STRIP
 
 AC_CHECK_PROGS(YACC, ['bison -y'])
+
+if test "$YACC"; then
+  if bison --version | sed q | $AWK '{ if ($4 < 1.875) exit 0; else exit 1;}'; then
+    AC_MSG_WARN([
+*** The installed version of Bison is too old.  PostgreSQL needs
+*** Bison version 1.875 or later.])
+    unset YACC
+  fi
+fi
+
 if test -z "$YACC"; then
   AC_MSG_WARN([
 *** Without Bison you will not be able to build PostgreSQL from CVS or