How to remove leftover packages from unused layers

Question

An easy example is adding themes-megapack to dotspacemacs-configuration-layers in .spacemacs, then running SPC f e R, and then observing all the added *-theme packages in your package-selected-packages list.

After commenting themes-megapack out of your dotspacemacs-configuration-layers list, then doing SPC f e R and even SPC q r, all the *-theme packages remain, and executing package-autoremove reports "Nothing to autoremove".

How to I clean up all these orphaned packages?

Answer 1

If you did not touch the variable dotspacemacs-install-packages i.e. its value is still 'used-only, then the packages do get removed (i.e. 'physically' from the elpa directory). However, the variable package-selected-packages does not get 'updated' so that it still also shows the uninstalled packages. I guess this could be considered a bug, so you could report it as an issue.

I have only very quickly had a look, but at first glance it looks like doing M-: (package--save-selected-packages (package--find-non-dependencies)) sets the variable to the 'correct' value again (I could be wrong, but I certainly don't expect it to do any harm, as package management is fully 'controlled' from the dotfile).