[Bug other/21350] New: configure reports only a warning when bison is not installed

["peter dot pirkelbauer at tamu dot edu" <gcc-bugzilla at gcc dot gnu dot org>]

when bison is not installed, configure reports only a warning, instead of an error.

Consequently, the following make-command fails.

-- 
           Summary: configure reports only a warning when bison is not
                    installed
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P2
         Component: other
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: peter dot pirkelbauer at tamu dot edu
                CC: gcc-bugs at gcc dot gnu dot org,gdr at cs dot tamu dot
                    edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21350