In our production code, warnings are always left on by default. Before releasing code into production all warnings errors are identified via unit tests & the QA group. However that doesn't mean that something didn't get missed.

Our production Perl code consists of cron jobs or daemons and we redirect STDOUT and STDERR to program specific "programmer" log files. These "programmer" log files are then scanned by another cron job for the presence of warnings. If any warnings are present then this indicates a problem. The error is then e-mailed to the programmer group who can research/fix the error.

-- vek --