Nixpkgs: Stack on 17.09 #c882c4d fails on `stack new` complaining about AesonException

[CMCDragonkai]

Issue description

When using 17.09 https://github.com/NixOS/nixpkgs-channels/commit/c882c4dd55e36dda57532fb830fad0882c4d770b and running stack new inside a nix-shell, it reports:

AesonException "Error in $.packages.cassava.constraints.flags['bytestring--lt-0_10_4']: Invalid flag name: \"bytestring--lt-0_10_4\""

When I made my nix-shell instead use the latest commit hash in nixpkgs-unstable https://github.com/NixOS/nixpkgs-channels/commit/8b1cf100cd8badad6e1b6d4650b904b88aa870db, it works without problems.

The main issue appears that stack 1.5.1 simply has this error, and they recommend people to update their stack. Perhaps 17.09 should have its stack upgraded? https://github.com/fpco/stackage/issues/3132

Technical details

Please run nix-shell -p nix-info --run "nix-info -m" and paste the
results.

 - system: `"x86_64-linux"`
 - host os: `Linux 4.14.11, Matrix Central, noversion`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 1.11.16`
 - channels(cmcdragonkai): `""`
 - channels(root): `""`
 - nixpkgs: `/nix/nixpkgs`

[bjornfor]

(Funny, I hit this yesterday.) I worked around it by specifying --resolver=lts-9.14.

[rsoeldner]

@bjornfor this works for me.

Can we update stack for nixos - I'm a second day nixos user, if someone help me I try to do it :+1:

[bjornfor]

I think @peti is the right person to answer that.

[peti]

Updating stack is no trivial matter, unfortunately, because it has a rather large and complex dependency tree. There's a decent chance that we'd have to update other packages, too, to accommodate the new stack version. But then we run the risk of breaking other build that share the same dependencies but which cannot cope with the new versions. This gets messy quick.

I'll give it a shot and try whether an update is easy. If it's not, however, then I'd rather spend my time working on the release-18.03 release which is going to come out in ~4 weeks anyway.

[peti]

Fixed by https://github.com/NixOS/nixpkgs/pull/36204.