学习RTGUI中遇到IAR编译问题，请教求助！

static rt_uint8_t* _font_cache_get(struct rtgui_hz_file_font* font, rt_uint16_t hz_id)
{
    rt_uint32_t seek;
    struct hz_cache *cache, search;
    search.hz_id = hz_id;
    cache = SPLAY_FIND(cache_tree, &(font->cache_root), &search);//这条语句编译出错
    if (cache != RT_NULL)
    {
        /* find it */
        return (rt_uint8_t*)(cache + 1);
    }