Switch gem RBI regeneration to RubyGems plugin

[alexcrocha]

Motivation

Current implementation

The current implementation has a few issues:

1. Relies on git, which is an external tool and not at all required to use Tapioca
2. Relies on the Ruby LSP's life cycle, which is not a great point to hook onto since when dependencies change the LSP is fully killed and respawned
3. We end up doing the work to check dependencies every time the LSP is booted, even though that's not really tied to a gem upgrade

Bundler plugins

In the past, we explored Bundler plugins and couldn't make it work. We tried again and indeed something is quite odd about how the Bundler plugin hooks are emitted. The plugin seems to be required too late in the process and the before-install-all event is never invoked either during bundle install or bundle update.

Implementation

We found another way that we might be able to make this work with the experience we want to provide, which is RubyGems plugins. These are similar to Bundler plugins, but associated to RubyGems events. To create a plugin, we just need to export a file ending with _plugin.rb and then we can hook to whatever we need.

We are not interested in the RubyGems events themselves, but rather two "Bundler" events: when it started running and when it finished running. If the lockfile ended up in a different state between these two points in time, then we can run Tapioca gem to ensure that the RBIs are up to date.

The approach we took here is to gather the contents of the lockfile when the plugin gets required (before any installations happen or the lockfile is committed) and then we register an at_exit hook to run Tapioca if necessary at the end of running bundle update. The plugin file is commented with more design information.

Consensus

If we agree with this direction, we can get rid of all of the code related to gem RBI generation in the Ruby LSP add-on and simply rely on the RubyGems plugin to keep those up to date.

That will not only reduce the amount of code we have to maintain, but it will better adhere to Tapioca's own logic and mechanisms.

Experience difference

If we run bundle update on a codebase that has gem RBIs that are out of sync, gem RBIs will be generated for dependencies that are not related to the updated gems.

[alexcrocha]

• Switch gem RBI regeneration to RubyGems plugin #2343 👈 (View in Graphite)
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