The original idea behind this change (described in ticket #11064) was to
improve the assertions to avoid that users of the X server accidentally
forget to configure a DM or WM.
However this caused several issues with setups that require X, but no DM
or WM. The keymap testcases became instable as well as now disabling DMs
needs to be done explicitly.
(see https://github.com/NixOS/nixpkgs/pull/31268#issuecomment-347080036)
In the end the idea behind the change and #11064 was obviously a
mistake, so reverting it completely for now should be fine.
I was mainly considering Jellyfish and Jaguar (and Jackrabbit).
Originally I was inclined for Jellyfish, but then I thought of the
release T-shirts someone makes and it didn't seem suitable...
Jaguar would keep the name referring to a car as well, but as a
not-too-old (Mac) OS version is codenamed that way, I didn't go for it.
Resolved the following conflicts (by carefully applying patches from the both
branches since the fork point):
pkgs/development/libraries/epoxy/default.nix
pkgs/development/libraries/gtk+/3.x.nix
pkgs/development/python-modules/asgiref/default.nix
pkgs/development/python-modules/daphne/default.nix
pkgs/os-specific/linux/systemd/default.nix
Eelco Dolstra wrote:
Hm, this is not really the intended use of stateVersion. From the description:
Every once in a while, a new NixOS release may change
configuration defaults in a way incompatible with stateful
data. For instance, if the default version of PostgreSQL
changes, the new version will probably be unable to read your
existing databases. To prevent such breakage, you can set the
value of this option to the NixOS release with which you want
to be compatible. The effect is that NixOS will option
defaults corresponding to the specified release (such as using
an older version of PostgreSQL).
So this is only intended for options that have some corresponding on-disk state. AFAICT this is not the case for sound. In any case stateVersion is a necessary evil that only exists because we can't just upgrade Postgres databases or change SSH host keys. It's not necessary for things like whether sound is enabled. (If the user discovers that sound is suddenly disabled, they can just enable it.)
I had some vague recollection that we also had a configVersion option setting to control the defaults for non-state-related options, but I can't find it so maybe it was only discussed.
