Move `doomdirs/example/` to just `doomdir/`, and rename the package
using it from `doom-example` to `doom-emacs`.
I do not expect to need multiple doomdirs checked in again, and I can
unclutter the packages provided by the flake a bit now that most of them
are checks.
This seems to be much more space-efficient: ~/.cache/nix/tarball-cache
is about 700MiB uncompressed, under 300MiB as tzst (using tar's
defaults, CI uses zstdmt but I assume will be in the same ballpark). The
gitv3 cache is multiple GiB.
CI will still build doom-example using fetchGit. I intend to shrink the
number of modules enabled in the example to keep gitv3 cache size under
control.
The doom profile is a non-negligible fraction of the cachix binary size,
that will only get worse (any dependency change will trigger a rebuild),
and caching them is essentially useless.
Expose emacsWithPackages so we can push just that. Skip
emacsWithPackages itself and push just the -deps derivation while we're
at it: caching either emacsWithPackages or -deps is similarly useless,
but they are a bit smaller.
When I say "non-negligible", it's about 1 MiB per "full" profile: much
larger than most individual libraries but not actually large. So this is
really a micro-optimization.
This is only a starting point. For this to be more useful, we need to
build for multiple Emacsen. But I want to get a baseline for the size of
the closure first (as well as confirming it works in the first place).
Although a completely empty DOOMDIR seems to work (at least for build
purposes), I doubt Doom actually supports this. And it requires some
extra checks on our side as well.
Just check in a trivial DOOMDIR and use that instead.
Exposing it as a package was (at least according to `nix flake check`)
incorrect.
This means we now use the user's nixpkgs's `pkgs.callPackage` instead of
our own, but I think that's ok.
Although not used much with doomProfile set, the default (.local in the
Doom source tree) will not work.
Currently straight-base-dir ends up relative to this, although that may
change.
Having this empty only really makes sense for minimal/full test builds.
Also, /var/empty was not doing what it looks like (it's not accessible
from inside the build sandbox). Use nixpkgs's emptyDirectory instead.
I was hoping to avoid this but it does not seem practical: I'm pretty
sure I need the user module in the store to override its packages.el,
and Doom does not separate the user module and doom-user-dir.
