Function generate_macro_def_id_path 

fn generate_macro_def_id_path(
    def_id: DefId,
    cx: &Context<'_>,
    jump_to_def_path_depth: Option<usize>,
) -> Result<HrefInfo, HrefError>

This function is to get the external macro path because they are not in the cache used in href_with_jump_to_def_path_depth.