[Feature idea] Have a way to prevent yarn cache clean

[jakub-g]

Context

(For context: we have a huge repo with 1000s of deps, use pnp mode, and commit .yarn/cache to git).

For some reason, some folks in my company, whenever having an issue, try yarn cache clean as a general troubleshooting option (perhaps they're used to rm -rf node_modules from old times of npm; also, they might be conflating yarn cache clean with some other commands).

This creates more problems than it solves:

• it creates a massive git diff on .yarn/cache
• things generally get more broken than before, and running yarn install is not fixing it.
  • It takes a lot of time to fetch all deps, run scripts, and eventually it fails.
  • This is e.g. because some of the deps deep in the dependency chain have scripts which no longer work etc. so a fresh install from scratch with zero disk cache does not work anymore.
    • (This is a separate thing that perhaps should be fixed on our side internally... But as you can imagine, fixing outdated deps-of-deps-of-deps is tricky)
• so the folks don't know what to do, and come to ask for support
• the proper way to fix things it to undo the changes in .yarn/cache first, and from there, try to fix the original problem they had.

The bottom line is, yarn cache clean is never a solution to the problems folks have, and it actually makes things worse.

Potential solution

• perhaps yarn cache clean (especially in pnp mode) should show a confirmation prompt? (or require --force)
  • might be a semver-major for yarn5
• having possibility to disable it (or require confirmation) via a yarnrc entry could also be an option.

[jakub-g]

Addressed in #6610