Nixpkgs: Significant number of Haskell packages unnecessarily marked as broken in 19.03

[bgamari]

Issue description

For some reason https://github.com/NixOS/nixpkgs/commit/9e7acf8b255fb4aa36d4539f49ecd5d3cca17c7b added broken=true to many packages in the default haskellPackages package set. haskellPackages.threadscope is one example, although there are many others.

Steps to reproduce

nix run nixpkgs.haskellPackages.threadscope

Technical details

 - system: `"x86_64-linux"`
 - host os: `Linux 4.19.34, NixOS, 19.03.172138.5c52b25283a (Koi)`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.2`
 - channels(root): `"nixos-19.03.172138.5c52b25283a, nixpkgs-19.03"`
 - channels(ben): `"nixpkgs-19.03.172138.5c52b25283a, nixpkgs-unstable-19.09pre174594.0c0954781e2"`
 - nixpkgs: `/home/ben/.nix-defexpr/channels/nixpkgs`

[bgamari]

In the case of threadscope this may be due to unsolvable version constraints:

$ nix run '(with (import <nixpkgs> {}); haskellPackages.callHackage "threadscope" "0.2.11.1" {})'
error: build of '/nix/store/z33jk3ddk150fvlblnfggys56c92w146-threadscope-0.2.11.1.drv' on 'ssh://[email protected]' failed: builder for '/nix/store/z33jk3ddk150fvlblnfggys56c92w146-threadscope-0.2.11.1.drv' failed with exit code 1
builder for '/nix/store/z33jk3ddk150fvlblnfggys56c92w146-threadscope-0.2.11.1.drv' failed with exit code 1; last 10 log lines:
    configureFinalizedPackage, called at libraries/Cabal/Cabal/Distribution/Simple/Configure.hs:460:12 in Cabal-2.4.0.1:Distribution.Simple.Configure
    configure, called at libraries/Cabal/Cabal/Distribution/Simple.hs:596:20 in Cabal-2.4.0.1:Distribution.Simple
    confHook, called at libraries/Cabal/Cabal/Distribution/Simple/UserHooks.hs:67:5 in Cabal-2.4.0.1:Distribution.Simple.UserHooks
    configureAction, called at libraries/Cabal/Cabal/Distribution/Simple.hs:178:19 in Cabal-2.4.0.1:Distribution.Simple
    defaultMainHelper, called at libraries/Cabal/Cabal/Distribution/Simple.hs:115:27 in Cabal-2.4.0.1:Distribution.Simple
    defaultMain, called at Setup.hs:2:8 in main:Main
  Setup: Encountered missing dependencies:
  gtk >=0.12 && <0.15, template-haskell <2.14

However, I don't recall such cases being marked as broken in the past. In any event, doJailbreaking threadscope works fine so marking it as broken seems rather harsh.

[bgamari]

@peti, do you know what is going on here?

[matthewbauer]

It would be good to get these resolved on hackage first before we add doJailbreak arbitrarily. Hackage trustees can make these changes IIRC.

[peti]

What do you mean those builds are marked broken "unnecessarily"? Those builds that are marked as broken fail.

[bgamari]

I suppose a more correct way of phasing this would have been rather "newly marked as broken". The point being that this seems to be a change and one that makes it a fair bit harder to use Haskell packages on a one-off basis. Previously it was very easy to apply haskell.lib.doJailbreak and the result would usually work. As far as I know there is no analogous combinator to unmark a package as broken. Perhaps we should add one.

[peti]

I suppose a more correct way of phasing this would have been rather "newly marked as broken". The point being that this seems to be a change and one that makes it a fair bit harder to use Haskell packages on a one-off basis.

The change prevents people from wasting half an hour of their lives trying to compile a package that we already know will not succeed.

Previously it was very easy to apply haskell.lib.doJailbreak and the result would usually work. As far as I know there is no analogous combinator to unmark a package as broken. Perhaps we should add one.

There is always overrideCabal, which allows you to modify the any attribute you see fit. Having a special unmarkBroken helper certainly wouldn't hurt, though. Would you like to suggest a PR?

[pjones]

@peti How do patches get created? I think they may be causing some of the packages to get marked as broken when they are not.

For example, in unstable, beam-core-0.8.0.0 is marked as broken. However if you override it and set broken=true; patches=[]; it builds just fine.

[peti]

@peti How do patches get created? I think they may be causing some of the packages to get marked as broken when they are not.

For example, in unstable, beam-core-0.8.0.0 is marked as broken. However if you override it and set broken=true; patches=[]; it builds just fine.

These patches were added by @endgame in https://github.com/NixOS/nixpkgs/pull/53680.

[pjones]

Thanks @peti! I really appreciate all the work you've done for the community.

[peti]

@pjones, thank you very much. :-)