`default.el` behaves subtly differently from `init.el`

[starptr]

When using emacsWithPackagesFromUsePackage, the defaultInitFile option cannot be used as a drop-in replacement for ~/.emacs.d/init.el. There are strange differences in behavior between the default init file (called default.el from now) and the init.el init file such that expressions that work perfectly fine in init.el do not work in default.el. (See noctuid/general.el#549 for just one example. As another example, :bind in a use-package expression does not work in some situations, but I haven't had a chance to triage this issue yet.)

Perhaps this fact is actually obvious to experienced users of emacs. I am not an experienced user, but it would be nice for this to be at least documented somewhere. An even better fix ("hotfix" might be a better word here if this is actually an upstream bug in emacs itself and default.el is supposed to behave exactly the same as init.el) would be to wrap the derivation and use the --init-directory CLI flag to pass in a derivation of the init.el file, avoiding usage of default.el altogether.