nix flake update & bump ghc 921 -> 922 (nix only)

[smunix]

ghc921 is no longer available on nixpkgs-unstable, so moving to ghc922

Edit: see haskell.compiler: ghc921 -> ghc922

[smunix]

Apologies, I have to close this. @guibou is already working on a similar fix (#2832)

[guibou]

Please, continue your MR or take ownership of #2832, I'm not sure I'll have time to fix #2832 soon.

[smunix]

It looks like this is working now, but the nix build phases are taking long to complete. This can be explained by the fact we're building off of new source versions that aren't in cachix caches yet.

Also, the build all binaries stage builds all the dependencies found for multiple GHC versions: 8.8.4, 8.10.7, 9.0.2, 9.2.2. Each of these versions are no longer hosted into nix caches, so we're building all of these dependencies from scratch again and again.

Lastly, for each of the steps above, we do build each Haskell module twice: the profiling and the non-profiling (this is set so by default in nix).

Anyone has suggestions for what can be done to reduce the build time?

[smunix]

It looks like this is working now, but the nix build phases are taking long to complete.
...
Anyone has suggestions for what can be done to reduce the build time?

These builds got cancelled after running for 6 hours.

[michaelpj]

Hmm, then maybe something is wrong with the cachix setup? It should be pushing things there.

[smunix]

Hmm, then maybe something is wrong with the cachix setup? It should be pushing things there.

It may also be that only specific accounts have that token available to push to haskell-language-server. Mine certainly can't push to cachix.

[michaelpj]

I think the GHA runners should be able to, although you probably can't do it locally yourself...

[michaelpj]

It looks like the cachix push step is succeeding, but I also don't get anything when I try to build locally.

I'm a bit baffled, perhaps we can summon @domenkozar for ideas on debugging the cachix setup?

[domenkozar]

If the person submitting the PR doesn't have write permissions then nothing will be pushed.

[michaelpj]

Well, that explains it! @domenkozar it would be great if the CLI said something in this case, it looks like we just get empty output in the logs. A "not pushing since I don't have keys" message would have been handy!

Okay, I'm going to try something:

• Close this PR
• Open a new PR (as me) from the same branch
  • That way you should still be able to push to the same branch and have it update.
• See if that does anything with caching.

[michaelpj]

Argh, it's skipping the job because it thinks it should be a no-op, and I can't push to your branch. Could you push a commit please @smunix ?

[michaelpj]

#2892