Initial work to support Webpack 5

[jacob-ebey]

All tests are passing locally but some touch-up work needs to be done.

Docs need to be updated and migration strategy / tests need to also be updated.

[jacob-ebey]

@eliperelman @edmorley

[edmorley]

@jacob-ebey Hi! Thank you for opening this :-) I'll take a closer look over the weekend (work keeps me busy during the week), but for now some initial thoughts:

• it might be worth having an issue filed where we can have a checklist of the tasks/blockers remaining (for example we'll need to check all of the webpack plugins are compatible + file upstream issues for them to add webpack 5 to their CI matrix etc)
• it would be good to identify any parts of webpack 5 support that are non-breaking that could be landed separately (and sooner) to reduce the size of the final PR. A good example of this would be the devtool name changes to make them match the webpack 5 stricter naming regex (since the new names are backwards compat). I'm a big fan of small PRs fwiw!
• I took a glance at webpack 5 compat in December (https://github.com/neutrinojs/neutrino/compare/webpack-5) - there were a few other issues that I found then (eg the webpack-cli arg changes) but some might have been mitigated since then (IMO the CLI should ideally support the old syntax in parallel at least for a while to ease transition; perhaps we could persuade them to do so?)

[edmorley]

Also:

• master is currently still Neutrino 9, so we've been making sure changes there are non-breaking. At some point we'll want to make a breaking release (Neutrino 10), at which point we can land all of the PRs currently labelled as breaking (plus likely some more, such as "drop support for all the old versions of ESLint/mocha/..." and maybe even "drop support for Node 10"). We'll need to decide whether it's viable to support both webpack 4 and 5 in Neutrino 9 (eg using conditionals for the config changes in this PR), or whether to just release as Neutrino 10.

[ScriptedAlchemy]

Some options here. At Next.js i introduced version detection and if you installed WP5, the conditionals would switch between the not config formats.

Is there a set list of plugins that are used? Those can be checked and in my experience its about 20 min per plugin to provide wp4 - Wp5 compatibility

[edmorley]

and if you installed WP5, the conditionals would switch between the not config formats.

Yeah that's the approach I'd like us to take if it's not too much hassle.

Is there a set list of plugins that are used?

All dependencies in this monorepo unfortunately - so that both CI will pass and end-users don't get surprises when using any of the official Neutrino presets.

[edmorley]

Closing since unfortunately this project is no longer maintained. See:
#1707
neutrinojs/webpack-chain#358