package Perl::Critic::Policy::ValuesAndExpressions::UndefinedBehaviour
+MaybeQuoteit;
our $VERSION = '0.01';
use strict;
use warnings;
use Readonly;
use parent 'Perl::Critic::Policy';
use Perl::Critic::Utils qw{ :severities  };
sub supported_parameters { return ()                     }
sub default_severity     { return $SEVERITY_MEDIUM       }
sub default_themes       { return qw< bugs maintenance > }
sub applies_to           { return qw/PPI::Statement/     }
Readonly::Scalar my $DESC => q{$1 not quoted (value not frozen) undefi
+ned behaviour};
Readonly::Scalar my $EXPL => q{Maybe $1 should be quoted ( "$1" ) to p
+revent undefined behaviour (to freeze the value)};

sub violates {
    my ( $self, $elem, undef ) = @_;
    return if ref($elem) !~ m{^(?:PPI::Statement::Variable|PPI::Statem
+ent::Expression|PPI::Statement)$};
    my $magic    = $elem->find('PPI::Token::Magic');
    my $operator = $elem->find('PPI::Token::Operator');
    my $word     = $elem->find('PPI::Token::Word');
    if( $magic ){
        my $dollar = 0;
        for my $mag ( @$magic ){
            $dollar++ if $mag->content =~ m/^\$\d+$/;
        }
        if( $dollar and ( $word or $operator )  ){
            return $self->violation( $DESC, $EXPL, $elem );
        }
    }
    return;
}

1; # End of Perl::Critic::Policy::ValuesAndExpressions::UndefinedBehav
+iourMaybeQuoteit

[download]

Warns/Criticizes on  Foo( $1 ); or  $1 + Foo();

Why? See $1 not "freezing" in an addition

I tested it with perlcritic -3 foo.pl

Seems to work :)