lanx@nc10-ubuntu:~$ cat >tst.pl
use strict;
$a=A;
lanx@nc10-ubuntu:~$ perl tst.pl
Bareword "A" not allowed while "strict subs" in use at tst.pl line 2.
Execution of tst.pl aborted due to compilation errors.
lanx@nc10-ubuntu:~$ perl -e'
>     $SIG{__WARN__} = sub {
>         local ( $/, $,, $! );
>         print STDERR "(W) ", @_, "\n";
>     };
> 
>     eval { do shift; 1 } or die("(F) $@");
> ' tst.pl
lanx@nc10-ubuntu:~$