[Nix-dev] "nix-env --set-flag priority NUMBER PKGNAME" not working?

[Bjørn Forsman]

Hi all,

I cannot get "nix-env --set-flag priority NUMBER PKGNAME" to work.
I've already installed "quassel" and when installing "quassel-client"
I get this conflict:

$ nix-env -i quassel-client
installing `quassel-client-0.9.2'
building path(s) `/nix/store/vvmhida83hw4kd6979gqrp05nnlz368v-user-environment'
collision between
`/nix/store/ck2ka99rbc17x6na5znpi8wpa6ryc5zb-quassel-client-0.9.2/share/apps/quassel/icons/oxygen/16x16/status/irc-channel-active.png'
and `/nix/store/c1f6czwdv0falg2wdcgplm2skg22jb82-quassel-0.9.2/share/apps/quassel/icons/oxygen/16x16/status/irc-channel-active.png';
use `nix-env --set-flag priority NUMBER PKGNAME' to change the
priority of one of the conflicting packages
builder for `/nix/store/bwqskb01y70hfhymprs101c47h56jily-user-environment.drv'
failed with exit code 255
error: build of
`/nix/store/bwqskb01y70hfhymprs101c47h56jily-user-environment.drv'
failed

Now set priority like the above printout suggests and retry:

$ nix-env --set-flag priority 1 quassel-client
$ nix-env -i quassel-client
installing `quassel-client-0.9.2'
building path(s) `/nix/store/vvmhida83hw4kd6979gqrp05nnlz368v-user-environment'
collision between
`/nix/store/ck2ka99rbc17x6na5znpi8wpa6ryc5zb-quassel-client-0.9.2/share/apps/quassel/icons/oxygen/16x16/status/irc-channel-active.png'
and `/nix/store/c1f6czwdv0falg2wdcgplm2skg22jb82-quassel-0.9.2/share/apps/quassel/icons/oxygen/16x16/status/irc-channel-active.png';
use `nix-env --set-flag priority NUMBER PKGNAME' to change the
priority of one of the conflicting packages
builder for `/nix/store/bwqskb01y70hfhymprs101c47h56jily-user-environment.drv'
failed with exit code 255
error: build of
`/nix/store/bwqskb01y70hfhymprs101c47h56jily-user-environment.drv'
failed

Hm, same error. I also tried with priority 10, 100, 1000.

I tried replacing the package name with the attribute path
"quasselClient", and with varying amount of prefixes such as "pkgs."
and "nixos.pkgs.". No change. It seems nix-env doesn't really care
whether the package exist or not:

$ nix-env --set-flag priority 1 does-not-exist && echo success
success

What is wrong here?

Best regards,
Bjørn Forsman