ModuleConcatenationPlugin bailout because of undefined injected global

[ludekstepan]

Bug report

What is the current behavior?

The ModuleConcatenationPlugin fails to hoist modules that use a global variable even when the global variable is undefined in the target environment.

The example is process, __dirname and other variables from Module Variables

Steps to reproduce.

Please see a gist: https://gist.github.com/ludekstepan/368d5f56afc195e473a6a9d897a5e164

When compiled, the webpack outputs:

[./index.js] 64 bytes {0} [built]
    ModuleConcatenation bailout: Module is an entry point
[./some-dep.js] 98 bytes {0} [built]
    ModuleConcatenation bailout: Module uses injected variables (__dirname)

And the compiled dist/main.js contains two modules:

If I change the__dirname in the dependency module to some other undefined global (like: __foo), the concatenation works as expected.

I want to optimize for size and performance as much as possible, and the concrete application that causes me trouble is: use of process in @most/scheduler

What is the expected behavior?

I expect the ModuleConcatenationPlugin to consider only global variables specific to the target environment.

Other relevant information:
webpack version: 4.20.2

[sokra]

webpack <= 4 doesn't support concatenation of injected variables. webpack 5 does support it.

[ludekstepan]

Wow! I've just tried the Webpack 5 and the module got concatenated. However, Webpack included some process shim in the output and that's not something that I want. Is it some new feature? Can I turn it off?

[sokra]

This is not new. node.process: false should disable it. node: false should disable all node polyfills.

[ludekstepan]

Thank you very much for reply! I'm closing this issue as this feature will be coming in Webpack 5.