use v5.16;
no v5.17;
no strict 'subs';

sub r          { $_[0] } # no-op?
sub rr :lvalue { $_[0] } # no-op?

$_ = 1;
say ( $ ++ _ ) + $_++;

$_ = 1;
say ($_) + $_++;

$_ = 1;
say r($_) + $_++;

$_ = 1;
say $_ + $_++;

$_ = 1;
say $_ + ++$_;

$_ = 1;
say r(++$_) + r(++$_);

$_ = 1;
say ++$_ + ++$_;

$_ = 1;
say rr(++$_) + rr(++$_)++;

$_ = 1;
say ++rr(++$_) + rr(++$_);

$_ = 1;
say ++rr(++$_) + rr(++$_)++;

$_ = 1;
say ++rr(++$_) + ++rr(r(rr(++$_)++));