when @babel/polyfill is used with webpack 5 it throws a ReferenceError: global is not defined

[capaj]

Bug Report

Current Behavior
on startup, I get the ReferenceError

index.js:25 Uncaught ReferenceError: global is not defined
    at Object.../node_modules/@babel/polyfill/lib/index.js (index.js:25)
    at __webpack_require__ (bootstrap:22)
    at fn (hot module replacement:64)
    at Module../src/index/globals-import.ts (error-handler.js:37)
    at __webpack_require__ (bootstrap:22)
    at fn (hot module replacement:64)
    at Module../src/index/index.js (globals-import.ts:15)
    at __webpack_require__ (bootstrap:22)
    at bootstrap:47
    at bootstrap:47

Expected behavior/code
no ReferenceError is thrown

Environment

• Babel version(s): "@babel/polyfill": "^7.2.5"
• Node/npm version: Node 8/npm 6.4.1
• OS: ubuntu
• Monorepo: no
• How you are using Babel: [loader]

I understand that I probably should just provide a global and that could mitigate the startup issue, but I also wanted to ask why?
Isn't babel polyfill primarily targeted at old browsers? Why is it that it relies on global to bootstrap itself when it's obviously not going to be there? Unless using webpack 1-4 obviously....

[babel-bot]

Hey @capaj! We really appreciate you taking the time to report an issue. The collaborators
on this project attempt to help as many people as possible, but we're a limited number of volunteers,
so it's possible this won't be addressed swiftly.

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[nicolo-ribaudo]

I think that this has something to do with the fact that webpack 5 doesn't polyfill any node feature (i.e. global) by default anymore.

[nicolo-ribaudo]

Does webpack/webpack#8537 (comment) work for you?

[capaj]

@nicolo-ribaudo just tested adding:

module.exports = {
  node: {
    global: true
  },

and yeah that works nicely. I'd still be interested to know why babel polyfill relies on the global in the first place? Wouldn't it be nicer to first check if there's a window object and if it is, use it instead of global?

[nicolo-ribaudo]

Yeah, or we could just use the global polyfill from core-js

[andersk]

The documentation recommends using @babel/preset-env with the useBuiltIns option set to 'entry' or 'usage'. In that case the top-level @babel/polyfill module isn’t used and this bug doesn’t appear.

We should still fix @babel/polyfill, but at least the useBuiltIns workaround is something you might want to be doing anyway.