comparisons compression option in uglifyjs webpack prod config breaks on react-mapbox-gl

[davidascher]

Can you reproduce the problem with latest npm?

Yes (including npm 5).

Description

There seems to be an incompatibility between CRA 1.0+ and the react-mapbox-gl component. This bug was not present before CRA 1.0, and only shows up in production mode, which makes me think it's a webpack 2.0 related issue.

Expected behavior

See https://github.com/davidascher/mapbox-repro-bug for a minimal test case (single component render -- works in development mode, doesn't work in production mode)

Actual behavior

In production mode (yarn build + serve -s build) , the map doesn't show and there's an incomprehensible traceback (as it's minified).

Environment

Run these commands in the project folder and fill in their results:

1. npm ls react-scripts (if you haven’t ejected): react-scripts@1.0.6
2. node -v: v7.9.0
3. npm -v: 5.0.0 (but it happened with 4.x as well)

Then, specify:

1. Operating system: OSX
2. Browser and version: Chrome 58.0.3029.110

Reproducible Demo

Source: https://github.com/davidascher/mapbox-repro-bug

(trivial CRA repo with one dependency).

Live site showing bug: https://build-wnyrhmqiph.now.sh/

/cc @alex3165 as he is the maintainer of react-mapbox-gl AFAICT.

[davidascher]

Aside: confirmed with the repo above that downgrading to react-scripts 0.9.5 fixes the problem.

[davidascher]

Confirmed that if I eject, and change the build step to use the webpack.config.dev config, the bug goes away.

[davidascher]

If I eject and simply comment out the UglifyJsPlugin from the plugins list in the production config, the bug goes away. Live site showing this: https://build-ijvjggnled.now.sh/

[davidascher]

With @kzc's help, this has been traced it down to an uglify option (see mishoo/UglifyJS#2011 (comment)).

Setting

   compress: {
        comparisons: false
   }

in the webpack prod config for the UglifyJS plugin fixes the problem.

I'll see if I can figure out how to override the webpack configs, I vaguely remember a bug going by about that new capability.

[gaearon]

Want to send a PR disabling that option?

[davidascher]

Happy to.

…

On Fri, May 26, 2017, 5:13 PM Dan Abramov, ***@***.***> wrote: Want to send a PR disabling that option? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#2376 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AADITnwK1R3KcuKOrJ5WW8Cj3YUASRRnks5r92qTgaJpZM4Nn2TZ> .

[gaearon]

Please let us know if Uglify fixes this!