Function check_impl 

fn check_impl(
    root_path: &Path,
    outdir: &Path,
    ci_info: &CiInfo,
    librustdoc_path: &Path,
    tools_path: &Path,
    npm: &Path,
    cargo: &Path,
    extra_checks: Option<&str>,
    pos_args: &[String],
    tidy_ctx: &TidyCtx,
) -> Result<(), Error>