a.js(2,14): error TS1277: 'const' modifier can only appear on a type parameter of a function, method or class
a.js(12,14): error TS1273: 'private' modifier cannot appear on a type parameter


==== a.js (2 errors) ====
    /**
     * @template const T
                 ~~~~~
!!! error TS1277: 'const' modifier can only appear on a type parameter of a function, method or class
     * @typedef {[T]} X
     */
    
    /**
     * @template const T
     */
    class C { }
    
    /**
     * @template private T
                 ~~~~~~~
!!! error TS1273: 'private' modifier cannot appear on a type parameter
     * @param {T} x
     * @returns {T}
     */
    function f(x) {
        return x;
    }
    