error.c:366
static VALUE
exc_inspect(exc)
    VALUE exc;
{
    VALUE str, klass;

    klass = CLASS_OF(exc);
    exc = rb_obj_as_string(exc);
    if (RSTRING(exc)->len == 0) {
	return rb_str_dup(rb_class_path(klass));
    }

    str = rb_str_buf_new2("#<");
    klass = rb_class_path(klass);
    rb_str_buf_append(str, klass);
    rb_str_buf_cat(str, ": ", 2);
    rb_str_buf_append(str, exc);
    rb_str_buf_cat(str, ">", 1);

    return str;
}
