uglify-js 3.4.9 broke js-xlsx after #3243, now work just when conditionals is False

[upmauro]

Uglify version (uglifyjs -V)
3.4.9

I'm using a js-xlsx to generate files by javascript, by the way, after 3.4.9 update all XML's generated in client-side in UTF-8 with accents is translated to wrong encode, i'm trying create a separated snippet to demonstrate the problem.

The problem solves when conditionals inside compress is false.

I opened the issue before I got the demo just to get the problem going, which might be the same as other users.

Sorry my english.

[upmauro]

The suspicious file is
https://github.com/SheetJS/js-xlsx/blob/master/dist/cpexcel.js

[victorguimaraessilva]

i have the same issue, in my enterprise we use js-xlsx and when we uglify the lib appears to be broken.

[gil-m]

Having the same problem here. Please fix or rollback!

[shaan1337]

I have a repro here (for at least one case, I don't know if there are others).

This code:

 return t?(e={},e.whatever='hello'):(e={},e.whatever='hello');

is minified to:

var e;return e.whatever=(e={},"hello")

This throws following error (since e.whatever is assigned before e is declared):

TypeError: Cannot set property 'whatever' of undefined
    at test (/home/shaan/.../uglify-bug/dist/file.js:1:103)
    at Object.<anonymous> (/home/shaan/.../uglify-bug/dist/file.js:1:120)
    at Module._compile (module.js:652:30)
    at Object.Module._extensions..js (module.js:663:10)
    at Module.load (module.js:565:32)
    at tryModuleLoad (module.js:505:12)
    at Function.Module._load (module.js:497:3)
    at Function.Module.runMain (module.js:693:10)
    at startup (bootstrap_node.js:191:16)
    at bootstrap_node.js:612:3

Steps:

1. Download and unpack file.js.zip
2. node file.js (no error here)
3. uglifyjs file.js -c > file.min.js
4. node file.min.js (throws e undefined error)

Same code works fine with v3.4.8.

After a git bisect between v3.4.8 and v3.4.9, the following commit is responsible:
2bdaca1