$ perl -le " while ( my $line = <> ) { 1 } print $. "
0
0
0
0
^Z
4

$ perl -MO=Deparse -le " while ( my $line = <> ) { 1 } print $. "
BEGIN { $/ = "\n"; $\ = "\n"; }
while (defined(my $line = <ARGV>)) {
    do {
        '???'
    };
}
print $.;
-e syntax OK