nix develop shell incompatible with Cabal 3.12.1.0?

[peterbecich]

cabal and cabal-syntax have been recently updated to 3.12.1.0 on NixPkgs.

cabal and cabal-syntax build successfully themselves:

nix build nixpkgs/haskell-updates#haskellPackages.Cabal_3_12_1_0
nix build nixpkgs/haskell-updates#haskellPackages.Cabal-syntax_3_12_1_0

Would you help me with this error?
On
https://github.com/peterbecich/hackage-server/tree/nix-cabal-3.12

nix develop yields an error building cabal-install-3.12.1.0

src/Distribution/Client/Glob.hs:24:1: error:
    Could not find module ‘Distribution.Simple.Glob.Internal’
    Perhaps you meant
      Distribution.Simple.GHC.Internal
      Distribution.Simple.GHC.Internal
      Distribution.Simple.Program.Internal (needs flag -package-id Cabal-3.10.3.0)
    Use -v (or `:set -v` in ghci) to see a list of the files searched for.
   |
24 | import Distribution.Simple.Glob.Internal
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

and

src/Distribution/Client/Errors.hs:861:21: error: [GHC-76037]
    Not in scope: type constructor or class ‘VerboseException’
    |
861 | instance Exception (VerboseException CabalInstallException) where
    |                     ^^^^^^^^^^^^^^^^

src/Distribution/Client/Errors.hs:862:23: error: [GHC-76037]
    Not in scope: type constructor or class ‘VerboseException’
    |
862 |   displayException :: VerboseException CabalInstallException -> [Char]
    |                       ^^^^^^^^^^^^^^^^

src/Distribution/Client/Errors.hs:863:21: error: [GHC-76037]
    Not in scope: data constructor ‘VerboseException’
    |
863 |   displayException (VerboseException stack timestamp verb cabalInstallException) =
    |                     ^^^^^^^^^^^^^^^^

[srid]

Just a quick suggestion, since I recall facing similar issues.

peterbecich/hackage-server@c0de63c#diff-206b9ce276ab5971a2489d75eb1b12999d4bf3843b7988cbe8d687cfde61dea0R51-R54

It probably is not a good idea to override cabal packages in the package set (i.e., settings). If you just want to use the newer cabal, maybe best to specify them directly in the devShell (or haskell-flake's devShell.tools).

[srid]

@locallycompact - any ideas?

(As an aside: haskell-flake also supports horizon package sets).

[peterbecich]

Thanks @srid, here is the error reproduced in Github Actions:
https://github.com/haskell/hackage-server/actions/runs/10023429550/job/27704328133?pr=1323
haskell/hackage-server#1323

[peterbecich]

Maybe this will make a difference: NixOS/nixpkgs#328757 it does not

[srid]

As far as I can see, the fix for this nevertheless can only happen on upstream, since haskell-flake simply wraps whatever nixpkgs provides. settings & packages are transformed into an overlay and then added to basePackages using extend:

haskell-flake/nix/modules/project/outputs.nix

Lines 86 to 91 in cd449f1

	finalOverlay = lib.composeManyExtensions ([
	config.packagesOverlay
	config.settingsOverlay
	] ++ config.otherOverlays);
	finalPackages = config.basePackages.extend finalOverlay;

[peterbecich]

Very good, I'll try to define a derivation that reproduces the issue minimally and bring it up there, thanks again @srid

[peterbecich]

Bingo, this reproduces it

nix build nixpkgs/haskell-updates#haskellPackages.cabal-install 

great

filed issue NixOS/nixpkgs#328765

[locallycompact]

Yeah we get this occasionally but horizon will catch it in CI. nixpkgs doesn't seem to build haskellPackages before merging PRs which leads to this.