error: the `-Z unstable-options` flag must also be passed to enable the flag `check-cfg`

[grinapo]

Tried from source, tried from release (though I'm not convinced those steps are working), but the result is the same:

error: the '-Z unstable-options' flag must also be passed to enable the flag 'check-cfg'

It feels like a problem about the user user stable rust while you're using a 2023 nightly and things get really messy.

[grinapo]

(Playground also unbuildable due to outdated dependencies like cosmicconfig 8.0 which has a file path bug, but apart from that it throws plenty of errors of non-exising files and dies. But that's javascript, it's expected not to work.)