Functions containing eval() where this or arguments are accessible allows eval() code to access temp vars

[overlookmotel]

Input:

export default (function() {
  return () => eval('[typeof _this, typeof _arguments]');
}).call({});

Current output:

module.exports = (0, eval)(`
  "use strict";
  (_this, _arguments) => function () {
    return () => eval('[typeof _this, typeof _arguments]');
  }.apply(_this, _arguments);
`)( {}, function () { return arguments; }() );

Original function returns ['undefined', 'undefined'] whereas output function returns ['object', 'object']. This is because eval() can access the temp vars which don't exist in the original.

The temp vars can be removed, solving this problem, by outputting:

export default (0, eval)(`
  "use strict";
  (function() {
    function() {
      return () => eval('[typeof _this, typeof _arguments]');
    }.apply(arguments[0], arguments[1]);
  })
`)( {}, function() { return arguments; }() );

or even something very close to the original:

export default (0, eval)(`
  "use strict";
  (function() {
    return () => eval('[typeof _this, typeof _arguments]');
  });
`).call({});

In this simple case where there are no other vars defined in the file, and output is ESM format (so no module or exports vars), output could also be identical to input. There's no need for (eval, 0)(...) wrapper, because there are no local vars to shield the eval() code from.