`nix build` seems to run with an older cabal version since `cabal-version` and `default-language` can't be updated

[briancarbone]

I have struggled to figure out how to use a cabal-version later than 3.8 and a default-language version later than 2021. I'm using GHC 9.12.2. The shell brings in the latest cabal, but the build process seems to be using an older version... is there a way to update it?

[briancarbone]

Figured it out... build-type: Custom + custom-setup with a constraint on the Cabal version.

[michaelpj]

Also hitting this. Custom setups aren't a good solution. I believe the issue is here:

haskell.nix/builder/hspkg-builder.nix

Line 44 in f7bea98

buildPackages.haskell-nix.nix-tools-unchecked.exes.default-setup // { exeName = "default-setup"; }

This default-setup executable comes from here:

haskell.nix/overlays/default.nix

Line 48 in f7bea98

static-nix-tools-for-default-setup = static-nix-tools' ../nix-tools-static-for-default-setup.nix;

Which just fetches some tarballs that are presumably for nix-tools built with an old GHC and cabal, which don't recognize the new languages.

[michaelpj]

I bumped the contents of nix-tools-static-for-default-setup.nix to match nix-tools-static.nix and that fixed it. I don't really know why we have two and there's no explanation so I have no idea if this is going to break anything 🤷

[hamishmack]

The reason for having two is that updating things like make-install-plan often only require all the plans to rebuild (unless the is a change to the plan that results in change to derivations based on it), but any change to the default-setup rebuilds everything (including all the GHCs). Since all the static nix-tools binaries are in a single derivation it was easiest just add a copy of the file.

I should have remembered to update the default-setup one after bumping the Cabal version we were using in nix-tools.

I'll merge #2402 once hydra builds everything.