Inline function optimization fails to define some arguments

[jamesopti]

This issue appears to be similar/related to #264 but without any variable name clashing, which I think would make it more likely to come across and thus I'm reporting it as a separate issue.
(also filed issue #3012 with Uglify-es)

When only a single occurrence of a method happens, Uglify-es is attempting to inline the only usage of the function, but is failing to declare the second variable, causing an uncaught exception.

Using:
Webpack @4.1.1
Uglifyjs-webpack-plugin @1.2.4

Minimally reproducible main.js:

(function(mod) {
  mod();
})(function() {
  function getMaxSeverity(ax, bx) {
    if (ax === "error") {
      return ax;
    } else {
      return bx;
    }
  }
  function main() {
    var arr = ['test'];
    for (var i = 0; i < arr.length; i++) {
      console.log(getMaxSeverity('one', 'two'));
    }
  }
  main();
});

Minifies to:

function(o, n) {
    !function() {
        !function() {
            for (var o = ["hey"], n = 0; n < o.length; n++)
                console.log("error" === (e = "one") ? e : bx);
            var e
        }()
    }()
}

Expected
two

Actual
Uncaught exception bx is not defined

More reproducible test cases here showing working versions of inlining:
https://github.com/jamesopti/uglifyjs-webpack-issue

[alexander-akait]

@jamesopti Duplicate #265?

[sirreal]

Duplicate #265?

I think you mean #264 (this is 265)

[alexander-akait]

@sirreal yep, duplicate?

[sirreal]

Maybe not 😕

Here's a chain of references starting with the description of this issue:

• [ES5] Inline function optimization fails to define some arguments mishoo/UglifyJS#3012
• uglify-es compress conditionals: increment erroneously not reached mishoo/UglifyJS#3010 (comment)
• bug with collapse_vars mishoo/UglifyJS#2908

The workaround here seems to be disabling collapse_vars (or maybe conditionals -- mishoo/UglifyJS#3010)

---

#264 on the other hand references mishoo/UglifyJS#2842

This workaround for this seems to be disabling inline.

---

They may be different uglify-es-side issues and require different workarounds 🙁

I'd say overall this indicates that #262 needs to be discussed.

[alexander-akait]

A lot of problem with uglify-es 😞 Ways:

1. Found contributor(s) for uglify-es and fix some problem asap
2. Release major version where switch to uglify-js with note about it is require babel-loader for es5+ syntax
3. Migrate cache and parallel and some other option to babel-minify plugin asap and recommandate use their instead uglify plugin.

[kzc]

uglifyjs-webpack-plugin should consider supporting passing in a custom uglify minify function similar to how rollup-plugin-uglify does it:

https://github.com/TrySound/rollup-plugin-uglify#options

That way users could choose any uglify-es or uglify-js@3.x API compatible version they like - even a custom version.

[alexander-akait]

@kzc 👍
@michael-ciniawsky what about union with babel-minify using custom function (by default use uglify)? It is allow have one plugin for uglifyjs, maybe rename plugin to more common name

[kzc]

what about union with babel-minify using custom function (by default use uglify)? It is allow have one plugin for uglifyjs, maybe rename plugin to more common name

Just from a usability perspective I wouldn't recommend mixing babel-minify and uglify into a single plugin. Their options are completely different. Use one or the other.

uglify-es's API is a superset of uglify-js@3's API, so you can get away with that.

[alexander-akait]

Close in favor #264, inline doesn't work correctly in many places in uglify-es. Solution:

1. Switch on terser (PR Update uglify-es dependency to use maintained terser module #296) will be merged in new future
2. Allow custom minify function, will be done in near future