with function parameter 'private' in ES5 script

[alexander-akait]

Bug report or Feature request?

Fails when function parameter has private name

webpack/webpack#13859

Version (complete output of terser -V or specific git commit)

latest (5.7.1)

Complete CLI command or minify() options used

terser input

const myMixin = function(private, public) {
  private.something = "some value";
}

terser output or error

ERROR in frag.min.js from Terser
Unexpected token: name (private) [webpack://./src/Cameras/cameraMixin.js:1,0][frag.min.js:1018,43]
    at js_error (./node_modules/terser/dist/bundle.min.js:550:11)
    at croak (./node_modules/terser/dist/bundle.min.js:1274:9)
    at token_error (./node_modules/terser/dist/bundle.min.js:1282:9)
    at unexpected (./node_modules/terser/dist/bundle.min.js:1288:9)
    at Object.add_parameter (./node_modules/terser/dist/bundle.min.js:1766:33)
    at binding_element (./node_modules/terser/dist/bundle.min.js:2023:29)
    at parameter (./node_modules/terser/dist/bundle.min.js:1830:17)
    at parameters (./node_modules/terser/dist/bundle.min.js:1804:25)
    at _function_body (./node_modules/terser/dist/bundle.min.js:2077:19)
    at function_ (./node_modules/terser/dist/bundle.min.js:1728:20)

Expected result

No errors

[fabiosantoscode]

This shouldn't crash indeed.

It's still technically correct though. The token private is a reserved word in strict mode.

If you run this in your browser (() => { 'use strict'; private })() you'll see an error about it.