perl -version

This is perl, v5.10.0 built for i486-linux-gnu-thread-multi

##</code><code>##

BEGIN {
    $SIG{__WARN__}=sub { print "WARNING: $_[0] \n" };
}

$|=1;

sub fn1($);
fn1("output1");
sub fn1 (\@) {
    print while $_ = shift;
}


sub fn2($);
fn2("output2");
sub fn2 (\@) {
    print $_,$/ for @_;
}

##</code><code>##

$ perl /tmp/proto.pl 
WARNING: Prototype mismatch: sub main::fn1 ($) vs (\@) at /tmp/proto.pl line 11.
 
WARNING: Prototype mismatch: sub main::fn2 ($) vs (\@) at /tmp/proto.pl line 18.
 
output1output2