bug#38529: Make --pure the default for `guix environment'?

[Jesse Gibbons]

On Sun, 2019-12-08 at 16:42 +0100, Pierre Neidhardt wrote:
> --pure seems to be the more sensible behaviour.  "Impure" environments
> can have unexpected behaviours, so it makes sense to only allow them
> when the user explicitly asks for it.
> 
--pure environments sometimes miss important environment variables. Try
running any app that depends on X and doesn't fallback to a console mode in
a pure environment.
for example, "guix environment --pure --ad-hoc pavucontrol -- pavucontrol"
gives me an error: 
No protocol specified
Unable to init server: Could not connect: Connection
refused



Similarly, "guix environment --pure --ad-hoc gnubik -- gnubik" gives me an
error:
No protocol specified

(gnubik:29707): Gtk-WARNING **: 10:03:28.753: cannot open display: :1





"guix environment --pure --ad-hoc gedit -- gedit":
No protocol specified
Unable to init server: Could not connect: Connection refused

(org.gnome.gedit:31542): Gtk-WARNING **: 10:08:07.401: cannot open display:
:1



Making --pure the default for "guix environment" would make things more
complicated for users wanting to temporarily run GUI apps unless we fix this
issue first. I furthermore suspect some tests fail because of this issue.