Try building with GHC 9.4 / HEAD in CI

[robx]

Bit unclear to me what haskell/actions/setup supports precisely, so let's just try it.

(I think it has special support for HEAD, and would use ghcup else which should fail for 9.4.1-alpha2...)

Compare #8230.

[robx]

HEAD jobs fails due to haskell/actions#93.

[robx]

I filed this PR to hopefully add support for prereleases to haskell/actions/setup: haskell/actions#107.

[Mikolaj]

After you do ghcup config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.7.yaml`, it has GHC 9.4 in it.

[robx]

After you do ghcup config add-release-channel https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-prereleases-0.0.7.yaml`, it has GHC 9.4 in it.

Unfortunately, we don't call ghcup directly... Let's see if the haskell setup action maintainers are responsive, otherwise I suppose we could drop that action entirely and just call ghcup directly as happens in the bootstrap workflow?

[robx]

Closing this for the moment, since it's blocked on the haskell setup action and I don't see myself pushing this through.