$dbh->do(q{
    CREATE FUNCTION poo (INTEGER) RETURNS INTEGER AS $func$
    DECLARE
      val ALIAS FOR $1;
    BEGIN
      RETURN val * 2;
    END
  });

  # Error:
  DBD::Pg::db do failed: execute called with an unbound placeholder [for Statement "
    CREATE FUNCTION poo (INTEGER) RETURNS INTEGER AS $func$
    DECLARE
        val ALIAS FOR $1;
    BEGIN
        RETURN val * 2;
    END
"]