JSDoc spread-annotations messes with code generation

[Victorystick]

TypeScript Version:

1.8.7

Code

Transpiling _apply.js of lodash-es@4.6.1 with the command

tsc --allowJs _apply.js --out apply.js -m amd

breaks the code. Apparently, the (arguably invalid) @param {...*} args JSDoc comment causes the TypeScript compiler to generate code as if the parameter declaration was apply(func, thisArg, ...args), although it is not.

/**
 * A faster alternative to `Function#apply`, this function invokes `func`
 * with the `this` binding of `thisArg` and the arguments of `args`.
 *
 * @private
 * @param {Function} func The function to invoke.
 * @param {*} thisArg The `this` binding of `func`.
 * @param {...*} args The arguments to invoke `func` with.
 * @returns {*} Returns the result of `func`.
 */
function apply(func, thisArg, args) {
  var length = args.length;
  switch (length) {
    case 0: return func.call(thisArg);
    case 1: return func.call(thisArg, args[0]);
    case 2: return func.call(thisArg, args[0], args[1]);
    case 3: return func.call(thisArg, args[0], args[1], args[2]);
  }
  return func.apply(thisArg, args);
}

export default apply;

Expected behavior:

define("_apply", ["require", "exports"], function (require, exports) {
    "use strict";
    /**
     * A faster alternative to `Function#apply`, this function invokes `func`
     * with the `this` binding of `thisArg` and the arguments of `args`.
     *
     * @private
     * @param {Function} func The function to invoke.
     * @param {*} thisArg The `this` binding of `func`.
     * @param {...*} args The arguments to invoke `func` with.
     * @returns {*} Returns the result of `func`.
     */
    function apply(func, thisArg, args) {
        var length = args.length;
        switch (length) {
            case 0: return func.call(thisArg);
            case 1: return func.call(thisArg, args[0]);
            case 2: return func.call(thisArg, args[0], args[1]);
            case 3: return func.call(thisArg, args[0], args[1], args[2]);
        }
        return func.apply(thisArg, args);
    }
    exports.__esModule = true;
    exports["default"] = apply;
});

Actual behavior:

define("_apply", ["require", "exports"], function (require, exports) {
    "use strict";
    /**
     * A faster alternative to `Function#apply`, this function invokes `func`
     * with the `this` binding of `thisArg` and the arguments of `args`.
     *
     * @private
     * @param {Function} func The function to invoke.
     * @param {*} thisArg The `this` binding of `func`.
     * @param {...*} args The arguments to invoke `func` with.
     * @returns {*} Returns the result of `func`.
     */
    function apply(func, thisArg) {
        var args = [];
        for (var _i = 2; _i < arguments.length; _i++) {
            args[_i - 2] = arguments[_i];
        }
        var length = args.length;
        switch (length) {
            case 0: return func.call(thisArg);
            case 1: return func.call(thisArg, args[0]);
            case 2: return func.call(thisArg, args[0], args[1]);
            case 3: return func.call(thisArg, args[0], args[1], args[2]);
        }
        return func.apply(thisArg, args);
    }
    exports.__esModule = true;
    exports["default"] = apply;
});

I've not been able to reproduce this in the TypeScript playground (currently running 1.8.2), which suggests a regression somewhere between 1.8.2 and 1.8.7.

[sheetalkamat]

@Victorystick

Your annotation is for variable number of arguments:

    /**
     * A faster alternative to `Function#apply`, this function invokes `func`
     * with the `this` binding of `thisArg` and the arguments of `args`.
     *
     * @private
     * @param {Function} func The function to invoke.
     * @param {*} thisArg The `this` binding of `func`.
     * @param {...*} args The arguments to invoke `func` with.
     * @returns {*} Returns the result of `func`.
     */

May be using this instead is what you want to make args as array?:

    /**
     * A faster alternative to `Function#apply`, this function invokes `func`
     * with the `this` binding of `thisArg` and the arguments of `args`.
     *
     * @private
     * @param {Function} func The function to invoke.
     * @param {*} thisArg The `this` binding of `func`.
     * @param {Array<*>} args The arguments to invoke `func` with.
     * @returns {*} Returns the result of `func`.
     */

[mhegazy]

@sheetalkamat, we should not use the JSDoc comments for emit transformations. this is not what the user expects. the work around is fine, but we need to fix this for the compiler.

[sheetalkamat]

@mhegazy, noted, will work on the fix.