Turn off inlining in optimization until UglifyJS issue is fixed.

[webpack-bot]

This minimization bug has been open for almost two months: mishoo/UglifyJS#2842. It has been referenced here elsewhere. The bug occurs when UglifyJS attempts to inline a call to a function with a variable of the same name as a variable in the calling function. Symptoms usually include "is not defined" or "assignment to constant variable".

In my experience, it's both easy to fall into and extremely time-consuming to diagnose.

I'd suggest turning inline: false in Webpack 4 until this is fixed. From the comments, it looks like UglifyJS2 is suffering from a lack of contributors with the skills and bandwidth needed to deal with things like this.

All of the Webpack 4 blogging has been about "Just let us do it for you." IMHO, to fulfill the implied promise, I think you need to be reactive to component issues like this.

Related: optimization.minimize and optimization.minimizer (along with the rest of optimization) need documenting.

For this particular issue, I'm using:

{
optimization:
            minimizer: [
               
                new UglifyJsPlugin({
                    parallel: true,  // Webpack default
                    cache: true      // Webpack default
                    uglifyOptions: {
                        /*
                            inlining is broken sometimes where inlined function uses the same variable name as inlining function.
                            See https://github.com/mishoo/UglifyJS2/issues/2842, https://github.com/mishoo/UglifyJS2/issues/2843
                         */
                        compress: { inline:false },
                    },
                })
            ],
}

---

This issue was moved from webpack/webpack#6798 by @evilebottnawi. Original issue was by @estaub.

[alexander-akait]

/cc @michael-ciniawsky what do you think about this?

[gil0mendes]

Today I ran over this issue, this would be nice to be fixed. Until then, disabling the minification is a good temporary workaround.

[jamesopti]

All of the Webpack 4 blogging has been about "Just let us do it for you." IMHO, to fulfill the implied promise, I think you need to be reactive to component issues like this.

+100 Couldn't agree more.

[michael-ciniawsky]

@evilebottnawi We can disable inlining by default, there will likely be no other option in the near future 😞. This plugin will definitely become obsolete anyways if uglify won't actually be maintained for ES2015+ code

[alexander-akait]

@michael-ciniawsky yep, let's do this, and we can improve babel-minify plugin for future 👍

[alexander-akait]

@michael-ciniawsky i can migrate cache and parallel options very fast 😄

[Reinmar]

We've run into this issue when trying to add support for building CKEditor 5 with webpack 4 (https://github.com/ckeditor/ckeditor5-dev/issues/371).

What I found is that uglify-es is not supported anymore (#262).

So, in the light of this, I'd say that disabling inlining misses the point. We may soon run into another issue with uglify-es and what's then? Will we be disabling next uglify's features?

[alexander-akait]

@Reinmar we can:

1. Migrate on uglify-js
2. Disable some option by default, but uglify looks very buggy and in long/mid term it is not solve
3. Migrate on babel-minify (looks it is time for this).

[Reinmar]

I commented on that in #262. I know that the decision is hard, though...

[estaub]

Turning off inlining by default doesn't preclude a better, longer-term solution.
By way of motivation... for other victims like me:

How long did it take you to figure out what's wrong?

I have no opinion on whether to move off uglify-es; it may make sense to stay there if there's some way to bring it back into a supported status. Regardless, identifying a different ongoing solution will take time, and switching to it may require, semver-wise, a major release.

(Probably) every day, poor slobs like us are losing hours of our lives chasing this down. Doesn't it make sense to put a bandaid on this now, and not make it contingent on identifying a long-term solution?

Note that there's already a babel-minify-webpack-plugin, which folks may want to kick the tires on. I haven't yet.

[alexander-akait]

@estaub @Reinmar can you test this using this branch #296?

[rdsedmundo]

People, just an insight: I spent 15 hours (literally) trying to resolve a problem on my build, and I just realized that it could be Uglify after noticing that the build was working in mode: development but not on mode: production - so I was deactivating one option at a time from Uglify until I discovered that it was compress: { inline: true } being bugged.

This is critical. Builds of everyone that relies on Webpack v4 and use mode: production could break anytime - as it has happened to me suddenly after some code changes (it was fine before).

The error that happens is completely random, in my case, it was from React, saying: Uncaught TypeError: Super expression must either be null or a function, not undefined.

This either needs to be disabled here or even directly in Webpack source code while including the plugin in case of the mode: production. @sokra

[estaub]

@rdsedmundo Can you help @evilebottnawi test? I'm stuck in back-end work.

[rdsedmundo]

Not sure what was supposed to be tested.

But I installed the uglifyjs-webpack-plugin dependency with the branch from that PR. It still doesn't work. If I provide the compress: { inline: false } though it works (nothing different then comparing to the normal version).

[alexander-akait]

Should be solved after merge #296

[alexander-akait]

Please who faced with problem test this branch, if all good please write about this here

[rdsedmundo]

Should be solved after merge #296

No, it isn't working.

[alexander-akait]

@rdsedmundo can you create issue in https://github.com/fabiosantoscode/terser?

[Reinmar]

@evilebottnawi, everything seems to work fine on our side (https://github.com/ckeditor/ckeditor5-dev/issues/371#issuecomment-394361235). Thanks!

[alexander-akait]

👍 i think we can release new version in near future, btw feel free to feedback

[jri]

What does this fix actually do? Does uglifyjs-webpack-plugin now call UglifyJS2 with compress: { inline: false } by default, or is the underlying UglifyJS2 bug fixed?

[kzc]

Bug workaround for yarn users:

https://github.com/fabiosantoscode/terser#replacing-uglify-es-with-terser-in-a-project-using-yarn

[Reinmar]

👍 i think we can release new version in near future, btw feel free to feedback

When do you plan to release a new version?