static bool _blocked_ray(const coord_def &where)

static bool _blocked_ray(const coord_def &where,
                         dungeon_feature_type* feat = NULL)

        {
            if (feat != NULL)
                *feat = grd(ray.pos());

        }

    dungeon_feature_type blocking_feat;
    if (_blocked_ray(mon->pos(), &blocking_feat))
    {
        text += "Your line of fire to " + lowercase_string(pronoun)
              + " is blocked by "
              + feature_description(blocking_feat, NUM_TRAPS, false,
                                    DESC_NOCAP_A)
              + "\n";
    }

    if (is_tracer && YOU_KILL(thrower) && flavour != BEAM_DIGGING
        && flavour <= BEAM_LAST_REAL && pos() != target  && pos() != source
        && !affects_nothing && bounces == 0 && reflections == 0
        && see_grid(target) && !grid_is_solid(grd(target)))
    {
        // Okay, with all those tests passed, this is probably an instance
        // of the player manually targetting something whose line of fire
        // is blocked, even though its line of sight isn't blocked.  Give
        // a warning about this fact.
        std::string prompt = "Your line of fire to ";
        const monsters* mon = monster_at(target);

        if (mon && you.can_see(mon))
            prompt += mon->name(DESC_NOCAP_THE);
        else
        {
            prompt += "the targeted "
                    + feature_description(target, false, DESC_PLAIN, false);
        }
        prompt += " is blocked by "
                + feature_description(pos(), false, DESC_NOCAP_A, false);
        prompt += ". Continue anyway?";
        if (!yesno(prompt.c_str(), false, 'n'))
        {
            beam_cancelled = true;
            finish_beam();
            return;
        }
        // Well, we warned them.
    }