panic! ModOrigin: hidden module redefined

[hololeap]

I'm getting this error on a couple packages:

dev-haskell/lsp-types
dev-haskell/optics-extra:

./setup haddock --hyperlink-source

...

haddock: While creating Haddock interface for Data.Text.Optics:

While creating Haddock interface for Data.Text.Optics:

haddock: panic! (the 'impossible' happened)
  (GHC version 8.10.6:
        ModOrigin: hidden module redefined

x: unusable module
y: unusable module
Call stack:
    CallStack (from HasCallStack):
      callStackDoc, called at compiler/utils/Outputable.hs:1179:37 in ghc:Outputable
      pprPanic, called at compiler/main/Packages.hs:228:14 in ghc:Packages

Please report this as a GHC bug:  https://www.haskell.org/ghc/reportabug

This error even crops up if you try it as a normal user using cabal
(only using v1 commands; v2 doesn't seem to have the issue):

$ cabal unpack optics-extra
$ cd optics-extra-*
$ cabal v1-build
$ cabal v1-haddock

---

Strangely, the workaround seems to be:

1. emerge the package with USE="-doc"
2. emerge the package normally

After this, everything works normally.

[solpeth]

Does the use-after-doc-workaround CABAL_FEATURES option work? The naming might be wrong here, but I'm afk.

[hololeap]

These packages have worked fine for me so far, but they suddenly started failing during a big haskell-updater run, and now they are working again after that little workaround. I just wanted to document this behavior because I think I saw it once before a while back, and others might run into the same thing.

[hololeap]

dev-haskell/lsp-types likes to do this.

[...]
    HasResultId (src/Language/LSP/Types/Lens.hs:379)
    HasDeleteCount (src/Language/LSP/Types/Lens.hs:381)
    HasRefreshSupport (src/Language/LSP/Types/Lens.hs:384)
  97% ( 43 / 44) in 'Language.LSP.Types'
  Missing documentation for:
  Module header
  'Language.LSP.Types.Capabilities'
  Missing documentation for:
    Module header
haddock: While creating Haddock interface for Language.LSP.VFS:
While creating Haddock interface for Language.LSP.VFS:
haddock: panic! (the 'impossible' happened)
(GHC version 8.10.6:
ModOrigin: hidden module redefined

x: unusable module
y: unusable module
Call stack:
    CallStack (from HasCallStack):
      callStackDoc, called at compiler/utils/Outputable.hs:1179:37 in ghc:Outputable
      pprPanic, called at compiler/main/Packages.hs:228:14 in ghc:Packages

Please report this as a GHC bug:  https://www.haskell.org/ghc/reportabug


 * ERROR: dev-haskell/lsp-types-1.3.0.1::haskell failed (compile phase):
 *   failed: ./setup haddock --hyperlink-source --haddock-options=--show-all --haddock-options=--pretty-html

[solpeth]

Closing as assumed to be fixed by upstream ghc patch landed in dev-lang/ghc-9.0.2-r1.

[hololeap]

This bug is actually separate. I'm not 100% sure of the cause, but it happened even with that patch in dev-lang/ghc-9.0.2-r1. It seems to have something to do with the packages being already installed on the system, but in a broken state due to a bumped/changed dependency (pending a haskell-updater run). This is likely something we will have to fix on our end, as this is essentially an undefined state according to ghc devs.

[hololeap]

I'm working on a more manageable solution for several issues, such as this one, which would benefit from having a more slimmed-down/isolated ghc package index during build. Creating a temporary package index which only includes the packages needed for the build, but not the package being built, should allow us to sidestep this issue.

[l29ah]

I get this when i hit tab in ghci after import :

ghc: panic! (the 'impossible' happened)
  (GHC version 9.2.4:
	ModOrigin: hidden module redefined

x: unusable module
y: unusable module
Call stack:
    CallStack (from HasCallStack):
      callStackDoc, called at compiler/GHC/Utils/Panic.hs:181:37 in ghc:GHC.Utils.Panic
      pprPanic, called at compiler/GHC/Unit/State.hs:238:14 in ghc:GHC.Unit.State

Please report this as a GHC bug:  https://www.haskell.org/ghc/reportabug

Leaving GHCi.

No lsp or optics here.

[hololeap]

@l29ah have you run haskell-updater and/or emerge @preserved-rebuild?

[l29ah]

Sure i did, i can't recompile a bunch of stuff, for instance skylighting-core:

>>> Compiling source in /var/tmp/portage/dev-haskell/skylighting-core-0.12.3.1/work/skylighting-core-0.12.3.1 ...
./setup build
Preprocessing library for skylighting-core-0.12.3.1..
Building library for skylighting-core-0.12.3.1..
ghc: panic! (the 'impossible' happened)
  (GHC version 9.2.4:
	ModOrigin: hidden module redefined
  x: unusable module
  y: unusable module
  Call stack:
      CallStack (from HasCallStack):
        callStackDoc, called at compiler/GHC/Utils/Panic.hs:181:37 in ghc:GHC.Utils.Panic
        pprPanic, called at compiler/GHC/Unit/State.hs:238:14 in ghc:GHC.Unit.State

Please report this as a GHC bug:  https://www.haskell.org/ghc/reportabug

[l29ah]

Manually removing skylighting-core and reinstalling fixed all the problems.

[hololeap]

This probably is just a dupe of #1250 at this point. I thought it was separate since we applied the patch.

[hololeap]

Reported by Arsen on #gentoo-haskell:

Building library for skylighting-core-0.13.2..
ghc: panic! (the 'impossible' happened)
  (GHC version 9.2.7:
        ModOrigin: hidden module redefined
  x: unusable module
  y: unusable module
  Call stack:
      CallStack (from HasCallStack):
        callStackDoc, called at compiler/GHC/Utils/Panic.hs:181:37 in ghc:GHC.Utils.Panic
        pprPanic, called at compiler/GHC/Unit/State.hs:238:14 in ghc:GHC.Unit.State