# file proto.pl
sub fn($);
fn("no bug.");
sub fn (\@) {
    print while $_ = shift;
}
__END__
Prototype mismatch: sub main::fn ($) vs (\@) at proto.pl line 6.

##</code><code>##

# file proto.pl
sub fn($);
fn("bug!");
sub fn (\@) {
    print $_,$/ for @_;
}
__END__
Prototype mismatch: sub main::fn ($) vs (\@) at proto.pl line 6.
bug!