Packages built with `haskellPackages.callHackage` won't be rebuilt when
updating `all-cabal-hashes`.
The removed comment was keeping a reference to the `cabal2nix` call,
which itself depends on `all-cabal-hashes`, in order to keep this file
during a garbage collection.
The tradeoff is between:
- The current behavior: a mass rebuild, any change of `all-cabal-hashes`
triggers a rebuild of all the packages built with `callHackage` and
packages which depend on them. This can take hours, and may happen
after a "small" unrelated change (i.e. an user is bumping
`all-cabal-hashes` in order to use a new package from hackage). It
also have global impacts in a project (long rebuild in CI, new entries
in cache, developers need to fetch the new entries, ...). In this
context, `cabal2nix` entries are not garbage collected.
- The new behavior: No mass rebuild, but `cabal2nix` derivations need to
be recomputed after a garbage collection. This is usually fast (a few
seconds by call), linear with the number of calls and should not
happen a lot (i.e. users are not garbage collecting everyday).
See https://github.com/NixOS/nixpkgs/issues/194751 for details.
This also removes automatic enablement/mounting of instance store swap
devices and ext3 filesystems. This behaviour is strongly opinionated
and shouldn't be enabled by default.
The unionfs behaviour never took effect anyway, because the AMI
manifest path only exists for instance store-backed AMIs, which have
not been supported by nixpkgs since
84742e2293 (2019).
Enabling Wayland support by default prevents use of XWayland on Wayland
systems, while correctly falling back to X11 when Wayland is
unavailable in the current session.
With the current packaging many people unnecessarily rely on the
`firefox` attribute, which is suggested by nixos-generate-config, which
in turn makes their Firefox use XWayland, when it shouldn't, which
causes bugs with GNOME on Wayland:
https://discourse.nixos.org/t/firefox-all-black-when-first-launched-after-login/21143
Using the Wayland-enabled Firefox was tested on pure X11 systems by
contributors on the #nix-mozilla:nixos.org room and we are confident
this change will not cause severe regressions.
Even better, people can now toggle `MOZ_ENABLE_WAYLAND=<0|1>` in their
environment to override this decision, should they feel the need to do
so.
