haskellPackages: unbreak bson and mongoDB

[NorfairKing]

Motivation for this change

Unbreaking bson and mongoDB.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Questions:

1. The problem is that the network/network-bsd dependency flag is not picked up correctly. Is this the correct place to fix it?
2. Is there a nicer way to 'replace' network by network-bsd than to re-enumerate all the dependencies and omit network?

[NorfairKing]

cc @peti

[maralorn]

Suggested change

	# We replace 'network' by 'network-bsd' because cabal2nix cannot correctly that pick up.
	# We replace 'network' by 'network-bsd' because cabal2nix cannot correctly pick that up.

[maralorn]

How is it possible that the cabal file does not declare the correct package name?

[NorfairKing]

@maralorn https://github.com/mongodb-haskell/bson/blob/d8e70185fb34a9e92aa98f17bf6a8c6bc1dc651d/bson.cabal#L40-L45 have a look here, a flag is used to choose between two packages and it looks like cabal2nix chooses the wrong one.

[NorfairKing]

Oh I just noticed that this flag is on by default: https://github.com/mongodb-haskell/bson/blob/d8e70185fb34a9e92aa98f17bf6a8c6bc1dc651d/bson.cabal#L28 Maybe if I just set the flag differently, cabal2Nix will pick it up correctly. How do I do that?

[maralorn]

haskell.lib.enableCabalFlag and haskell.lib.disableCabalFlag

[NorfairKing]

haskell.lib.enableCabalFlag and haskell.lib.disableCabalFlag

Yes but that doesn't fix the dependencies. I'd want to set this flag when callCabal2Nix is called, not afterwards.

[NorfairKing]

https://github.com/NixOS/cabal2nix/blob/e18310f2eae5d2d7b73512b0b75396224fbf76ca/src/Distribution/Nixpkgs/Haskell/FromCabal/PostProcess.hs#L83 Does it need to be added in here?
I don't see anything flag-related in this dir: https://github.com/NixOS/nixpkgs/tree/0b973eaa9441f894c65e5008a042b21025f6ff44/pkgs/development/haskell-modules/configuration-hackage2nix

[NorfairKing]

We could also just apply this patch instead: aske/bson@288cfac

[sternenseemann]

I think this should go into configure-nix.nix. I don't think we'll get rid of this in the near future since it'd require us to implement some generation-time configuration mechanism for hackage2nix.

[sternenseemann]

This should be much simpler and not require us to maintain a list of dependencies

Suggested change

	bson = overrideCabal super.bson (drv: {
	# We replace 'network' by 'network-bsd' because cabal2nix cannot correctly that pick up.
	libraryHaskellDepends = with pkgs.haskellPackages; [
	base
	binary
	bytestring
	cryptohash-md5
	data-binary-ieee754
	mtl
	network-bsd # network-bsd AND NOT network
	text
	time
	];
	});
	bson = appendConfigureFlag (super.bson.override { network = self.network-bsd; }) "-f-_old_network";

[sternenseemann]

We could also just apply this patch instead: aske/bson@288cfac

This won't work I'm afraid since the patch is only applied after we already resolve the dependencies. We should ask upstream to release a new version or update the cabal file on hackage though.

[NorfairKing]

@sternenseemann I already made this: mongodb-haskell/bson#26

[NorfairKing]

@sternenseemann what can we do in the meantime?
EDIT: just saw your suggestion, if that works then it's fine by me, feel free to replace my commit by your suggestion and merge at your discretion.

[sternenseemann]

Done in 978f8b381f2eb0900d27b0e6ae52e919695b8fc6.

[NorfairKing]

@sternenseemann mongoDB should also be unbroken now.

[sternenseemann]

Yeah, it is! We've reworked how this works in haskellPackages, so it does evaluate again and we'll do an automatic sweep to make it being built by hydra again.