($msg:literal $(,)?) => {
        return std::result::Result::Err($crate::anyhow!($msg));
    };

    ($cond:expr, $msg:literal $(,)?) => {
        if !$cond {
            return std::result::Result::Err($crate::anyhow!($msg));
        }
    };

    ($msg:expr $(,)?) => ({

    ($msg:literal $(,)?) => {
        // Handle $:literal as a special case to make cargo-expanded code more
        // concise in the common case.
        $crate::private::new_adhoc($msg)
    };
    ($err:expr $(,)?) => ({

        let error = $msg;

        let error = $err;