/** @constructor */
var foo = function() {};

/** @interface */
var hasFoobar = function() {};

/** @param {foo} a */
hasFoobar.prototype.foobar = function(a) {};

/**
 * @constructor
 * @extends {foo}
 * @implements {hasFoobar}
 */
var bar = function() {};

bar.prototype = new foo();

/** @param {bar} a */
bar.prototype.foobar = function(a) {};