Error building/installing cabal-helper-1.0.0.0

[jneira]

Describe the bug
Alternating cabal v2-buildand cabal v2-install over cabal-helper-1.0.0.0 or a package that depends on it (in my case haskell-ide-engine) with a fresh cabal store throws a build error cause the dependency cabal-plan is added twice when compiling.

It worths to note that cabal-helperis using a private named lib: https://github.com/DanielG/cabal-helper/blob/master/cabal-helper.cabal#L116

The error is:

Preprocessing library for cabal-helper-1.0.0.0..
Building library for cabal-helper-1.0.0.0..
[1 of 3] Compiling Distribution.Helper ( lib\Distribution\Helper.hs, dist\build\Distribution\Helper.o )

lib\Distribution\Helper.hs:591:68: error:
    • Couldn't match expected type ‘cabal-plan-0.6.2.0:Cabal.Plan.PlanJson’
                  with actual type ‘PlanJson’
      NB: ‘PlanJson’
            is defined in ‘Cabal.Plan’ in package ‘cabal-plan-0.6.2.0’
          ‘cabal-plan-0.6.2.0:Cabal.Plan.PlanJson’
            is defined in ‘Cabal.Plan’ in package ‘cabal-plan-0.6.2.0’
    • In the first argument of ‘CabalInstall.planPackages’, namely
        ‘plan’
      In the second argument of ‘(<$>)’, namely
        ‘CabalInstall.planPackages plan’
      In a stmt of a 'do' block:
        Just pkgs <- NonEmpty.nonEmpty <$> CabalInstall.planPackages plan
    |
591 |       Just pkgs <- NonEmpty.nonEmpty <$> CabalInstall.planPackages plan
    |                                                                    ^^^^

To Reproduce
I can't reproduce it locally in a consistent way, but i've triggered it deleting the cabal store and make cabal v2-build and cabal v2-install.
@fendor has experienced the issue in linux and me in windows
However it is reproduced consistently in azure ci for windows (not linux), see for example: https://dev.azure.com/jneira/haskell-ide-engine/_build/results?buildId=502&view=results

Steps to reproduce the behavior:

• removing the existent cabal store
• run cabal v2-build in the haskell-ide-enginerepo
• run cabal v2-install

The azure ci bash scripts of the build: https://github.com/jneira/haskell-ide-engine/blob/azure-cabal/.azure/windows-cabal.yml

Expected behavior

The build should finish correctly

System information

• Several windows systems and linux ones
• cabal-3.0.0.0, ghc-8.6.5 and ghc-8.4.4

Additional context

You can workaround the issue removing the cabal-plan-* dirs inside the cabal store and running @phadej script to fix the store (or removing the entire store)
Related issues: #6412 and #5782

[phadej]

I guess this is the same problem as #6211

Without consistent reproducer, I doubt it can be fixed easily. Note that #6211 uses internal library as well.

[phadej]

I'm closing this as duplicate (I'm pretty sure there is the same root cause).

[phadej]

I'm unable to reproduce #6211 myself anymore using `cabal-install-3.0.1.0 from hvr's ppa, which is https://github.com/haskell/cabal/releases/tag/cabal-install-v3.0.1.0-rc4, but it doesn't mean issue is fixed.

Edit: I recall changing something in install code, maybe fixing #6410, fixed this as well.

[hasufell]

This sounds like a major bug to me if I cannot trust the build-store to be consistent. I just hit this as well in hie. I will try to create a docker container with my state of the .cabal dir.

[Mikolaj]

@hasufell: hi! We guess (#5782 (comment)) this issue is fixed in new stable cabals --- could you perhaps try to reproduce locally your case with new cabal and confirm?

[hasufell]

@hasufell: hi! We guess (#5782 (comment)) this issue is fixed in new stable cabals --- could you perhaps try to reproduce locally your case with new cabal and confirm?

The bug was never easy to reproduce. I haven't hit it in a long time though. Whether that means it's fixed: I don't know.

[Mikolaj]

@hasufell: got it; thank you