entity ent7 is
  generic (
    WIDTH : natural := 1);
end;

architecture ent of ent7 is
  type data_t is record
    t : bit_vector;
  end record;
  type bv_array_t is array (natural range <>) of data_t;
  subtype bv_array2_t is bv_array_t(open)(t(WIDTH - 1 downto 0));

  procedure write_data (constant c : bv_array2_t) is
  begin
    for i in c'range loop
      report integer'image(i) & " =>" & to_string(c(i).t);
    end loop;

    assert c(1).t(0) = '1'; -- <<<<<====== This should not fail
  end procedure;

begin
  process
    variable data2 : bv_array2_t(0 to 1);
  begin
    data2(0).t := "0";
    data2(1).t := "1";
    write_data(data2);
    wait;
  end process;
end ent;