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[8.6] ModOrigin: hidden module redefined

    • Closed Issue created by jwaldmann @jwaldmann

    Summary

    ghci crashes when I try to TAB-complete an import list

    Steps to reproduce

    I am typing "import Data.List (isS" and then press TAB

    /opt/ghc/ghc-8.6.5/bin/ghci
GHCi, version 8.6.5: http://www.haskell.org/ghc/  :? for help
Prelude> import Data.List (isSghc: panic! (the 'impossible' happened)
  (GHC version 8.6.5 for x86_64-unknown-linux):
	ModOrigin: hidden module redefined

    Expected behavior

    suggest completions (or do nothing - as 8.6.4 does)

    Environment

    • GHC version used: 8.6.5

    Optional:

    • Operating System: GNU/Linux Fedora 30
    • System Architecture: x86_64
    Edited
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    Child items ...

    • Activity

    • ghc-triage-bot added needs triage label

      added needs triage label

    • Ryan Scott
      Ryan Scott @RyanGlScott ·
      Maintainer

      I am unable to reproduce this, using essentially the same system environment as you are (I'm on Ubuntu 18.04 instead of Fedora 30, but I doubt that is important).

      Are you running GHCi in a particular directory by any chance? I tried to create a Data/List.hs file and run GHCi in the directory above that (so that if you tried to import Data.List, you'd get the usual attempting to use module ‘main:Data.List’ (./Data/List.hs) which is not loaded message), but I was still unable to observe the panic.

    • jwaldmann
      jwaldmann @jwaldmann ·
      Author

      I crashes repeatedly for me (even with "import ", and in an empty directory). It must have something to do with the environment, because when I do

      stack exec -- ghci

      (in a random project) it does not crash. It also does not crash with

      ghci -no-user-package-db

      Now indeed ghc-pkg check tells me I have broken packages. Ah- and when I ghc-pkg unregister them, then the error goes away.

      Edited by jwaldmann
    • Ryan Scott
      Ryan Scott @RyanGlScott ·
      Maintainer

      #11050 (closed) might be related.

    • Ryan Scott marked this issue as related to #11050 (closed)

      marked this issue as related to #11050 (closed)

    • Ben Gamari added GHCi Tbug compiler crash labels and removed needs triage label

      added GHCi Tbug compiler crash labels and removed needs triage label

    • Ben Gamari
      Ben Gamari @bgamari ·
      Maintainer

      What did ghc-pkg check claim the reason for the breakage was?

    • Ben Gamari added Pnormal label

      added Pnormal label

    • acoret
      acoret @acoret ·

      it happend at

      • system:Linux Reaker 5.2.11-arch1-1-ARCH #1 SMP PREEMPT Thu Aug 29 08:09:36 UTC 2019 x86_64 GNU/Linux

      archlinux use a dynamic linked ghc

      System Architecture: x86_64

      • ghc-version: The Glorious Glasgow Haskell Compilation System, version 8.6.5
      • environment:
        • installed haskell-yesod and so on package by pacman.
        • cabal get zeromq4-haskell or just use it at deps
      • trigger: cabal v2-repl and put import System. then press Tab it crashed

      it's pretty weird that cabal repl will not trigger the bug

      • ghc-pkg: very-long warn (archlinux won't install haddock?i dont know),
      The following packages are broken, either because they have a problem
listed above, or because they depend on a broken package.
mongoDB-2.5.0.0
tls-1.5.1
conduit-extra-1.3.4
conduit-1.3.1.1
nonce-1.0.7
resourcet-1.2.2
bson-0.3.2.8
streaming-commons-0.2.1.1
yesod-1.6.0
yesod-persistent-1.6.0.2
yesod-form-1.6.6
yesod-core-1.6.16
yaml-0.11.1.2
warp-3.3.0
wai-extra-3.0.28
persistent-2.10.1
persistent-template-2.7.2
monad-logger-0.3.30
libyaml-0.1.1.0

      the broken yesod? maybe because i tried to install yesod by cabal,but it failed,then i install it by pacman,and in ghci import Yesod does work,and so does the warp,wai etc (which is deps of yesod).
      other broken package is installed and does work before i upgrade system package(and install yesod by pacman),maybe it's another story.

      dose it help?

      Edited by acoret
    • Ryan Scott marked #18058 (closed) as a duplicate of this issue

      marked #18058 (closed) as a duplicate of this issue

    • Ryan Scott marked this issue as related to #18058 (closed)

      marked this issue as related to #18058 (closed)

    • Ryan Scott mentioned in issue #18058 (closed)

      mentioned in issue #18058 (closed)

    • Jens Petersen
      Jens Petersen @juhp ·
      Developer

      I have been hitting this for while now, but only in cabal new-repl sessions.

      Edited by Jens Petersen
    • Jens Petersen
      Jens Petersen @juhp ·
      Developer

      I haven't seen this since moving from Fedora ghc-8.6 to 8.8.

    • Jens Petersen changed title from ModOrigin: hidden module redefined to [8.6] ModOrigin: hidden module redefined

      changed title from ModOrigin: hidden module redefined to [8.6] ModOrigin: hidden module redefined

      • Manuel Bärenz
        Manuel Bärenz @turion1 ·

        I've recently observed this in 8.8.4:

        *Data.Data.Util> import Livghc: panic! (the 'impossible' happened)
  (GHC version 8.8.4 for x86_64-unknown-linux):
        ModOrigin: hidden module redefined

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

Leaving GHCi.

        Reproduce

      • Ryan Scott
        Ryan Scott @RyanGlScott ·
        Maintainer

        I'm still unable to reproduce the bug, even with the instructions above. (I am using this commit, if that is relevant.) When I hit Tab, it simply autocompletes to import LiveCoding. What am I doing wrong?

        One observation is that nix-shell gives me a different version of GHC that what you reported in #16996 (comment 302660):

        $ ghc --version
The Glorious Glasgow Haskell Compilation System, version 8.8.3
      • Manuel Bärenz
        Manuel Bärenz @turion1 ·

        @RyanGlScott Good catch! I had some minor changes in my working tree. Can you pull the latest master and try again?

      • Ryan Scott
        Ryan Scott @RyanGlScott ·
        Maintainer

        I still can't reproduce the bug on commit fd3c78ff795b8e1e0a9ac4b5104971dc4b466202.

      • Manuel Bärenz
        Manuel Bärenz @turion1 ·

        That's surprising. Is there a way to be absolutely certain that we're using the same GHC binary? (We should, given that we're both using a nix-shell with a pinned nixpkgs.)

        What other files could possibly make a difference? I did cabal clean and can still reproduce. At some point I did gen-hie > hie.yaml or similar, maybe that makes a difference? (Although it only should have an effect for the Haskell Language Server, I believe.)

        Are you using NixOS or another system? Even Linux? That might have an influence on the GHC binary.

        (Thanks for pinning the commit hash, I forgot that.)

      • Ryan Scott
        Ryan Scott @RyanGlScott ·
        Maintainer

        Just to make sure we're doing the exact same steps, here is what I tried:

        $ git clone https://github.com/turion/essence-of-live-coding
$ cd essence-of-live-coding/
$ git reset --hard fd3c78ff795b8e1e0a9ac4b5104971dc4b466202
$ nix-shell
$ cd essence-of-live-coding
$ cabal repl
Build profile: -w ghc-8.8.4 -O1
In order, the following will be built (use -v for more details):
 - essence-of-live-coding-0.2.4 (lib) (first run)
Preprocessing library for essence-of-live-coding-0.2.4..
GHCi, version 8.8.4: https://www.haskell.org/ghc/  :? for help
[ 1 of 38] Compiling LiveCoding.LiveProgram ( src/LiveCoding/LiveProgram.lhs, interpreted )
[ 2 of 38] Compiling LiveCoding.Cell  ( src/LiveCoding/Cell.lhs, interpreted )
[ 3 of 38] Compiling LiveCoding.Debugger ( src/LiveCoding/Debugger.lhs, interpreted )
[ 4 of 38] Compiling LiveCoding.Coalgebra ( src/LiveCoding/Coalgebra.lhs, interpreted )
[ 5 of 38] Compiling LiveCoding.Cell.Monad ( src/LiveCoding/Cell/Monad.hs, interpreted )
[ 6 of 38] Compiling LiveCoding.Cell.Resample ( src/LiveCoding/Cell/Resample.hs, interpreted )
[ 7 of 38] Compiling LiveCoding.Cell.Monad.Trans ( src/LiveCoding/Cell/Monad/Trans.hs, interpreted )
[ 8 of 38] Compiling LiveCoding.Exceptions.Finite ( src/LiveCoding/Exceptions/Finite.lhs, interpreted )
[ 9 of 38] Compiling LiveCoding.Exceptions ( src/LiveCoding/Exceptions.lhs, interpreted )
[10 of 38] Compiling LiveCoding.External ( src/LiveCoding/External.hs, interpreted )
[11 of 38] Compiling LiveCoding.CellExcept ( src/LiveCoding/CellExcept.lhs, interpreted )
[12 of 38] Compiling LiveCoding.Cell.Feedback ( src/LiveCoding/Cell/Feedback.lhs, interpreted )
[13 of 38] Compiling LiveCoding.Cell.Util ( src/LiveCoding/Cell/Util.hs, interpreted )
[14 of 38] Compiling LiveCoding.Bind  ( src/LiveCoding/Bind.lhs, interpreted )
[15 of 38] Compiling LiveCoding.Forever ( src/LiveCoding/Forever.lhs, interpreted )
[16 of 38] Compiling LiveCoding.Debugger.StatePrint ( src/LiveCoding/Debugger/StatePrint.hs, interpreted )
[17 of 38] Compiling LiveCoding.LiveProgram.Monad.Trans ( src/LiveCoding/LiveProgram/Monad/Trans.hs, interpreted )
[18 of 38] Compiling LiveCoding.Handle ( src/LiveCoding/Handle.hs, interpreted )
[19 of 38] Compiling LiveCoding.Handle.Examples ( src/LiveCoding/Handle/Examples.hs, interpreted )
[20 of 38] Compiling LiveCoding.Cell.NonBlocking ( src/LiveCoding/Cell/NonBlocking.hs, interpreted )
[21 of 38] Compiling LiveCoding.Migrate.Migration ( src/LiveCoding/Migrate/Migration.hs, interpreted )
[22 of 38] Compiling LiveCoding.Migrate.Debugger ( src/LiveCoding/Migrate/Debugger.hs, interpreted )
[23 of 38] Compiling LiveCoding.Migrate.Cell ( src/LiveCoding/Migrate/Cell.hs, interpreted )
[24 of 38] Compiling LiveCoding.Migrate.Monad.Trans ( src/LiveCoding/Migrate/Monad/Trans.hs, interpreted )
[25 of 38] Compiling LiveCoding.Migrate ( src/LiveCoding/Migrate.lhs, interpreted )
[26 of 38] Compiling LiveCoding.LiveProgram.HotCodeSwap ( src/LiveCoding/LiveProgram/HotCodeSwap.lhs, interpreted )
[27 of 38] Compiling LiveCoding.Cell.HotCodeSwap ( src/LiveCoding/Cell/HotCodeSwap.hs, interpreted )
[28 of 38] Compiling LiveCoding.Preliminary.CellExcept.Applicative ( src/LiveCoding/Preliminary/CellExcept/Applicative.lhs, interpreted )
[29 of 38] Compiling LiveCoding.Preliminary.CellExcept ( src/LiveCoding/Preliminary/CellExcept.lhs, interpreted )
[30 of 38] Compiling LiveCoding.Preliminary.CellExcept.Monad ( src/LiveCoding/Preliminary/CellExcept/Monad.lhs, interpreted )
[31 of 38] Compiling LiveCoding.Preliminary.CellExcept.Newtype ( src/LiveCoding/Preliminary/CellExcept/Newtype.lhs, interpreted )
[32 of 38] Compiling LiveCoding.Preliminary.LiveProgram.LiveProgram2 ( src/LiveCoding/Preliminary/LiveProgram/LiveProgram2.lhs, interpreted )
[33 of 38] Compiling LiveCoding.Preliminary.LiveProgram.LiveProgramPreliminary ( src/LiveCoding/Preliminary/LiveProgram/LiveProgramPreliminary.lhs, interpreted )
[34 of 38] Compiling LiveCoding.Preliminary.LiveProgram.HotCodeSwap ( src/LiveCoding/Preliminary/LiveProgram/HotCodeSwap.lhs, interpreted )
[35 of 38] Compiling LiveCoding.RuntimeIO.Launch ( src/LiveCoding/RuntimeIO/Launch.hs, interpreted )
[36 of 38] Compiling LiveCoding.RuntimeIO ( src/LiveCoding/RuntimeIO.lhs, interpreted )
[37 of 38] Compiling LiveCoding.GHCi  ( src/LiveCoding/GHCi.hs, interpreted )
[38 of 38] Compiling LiveCoding       ( src/LiveCoding.hs, interpreted )
Ok, 38 modules loaded.
*LiveCoding>

        I then type:

        *LiveCoding> import Liv

        And hit the Tab key, which autocompletes to:

        *LiveCoding> import LiveCoding

        I thought it worth being explicit about this, since you say "Enter the nix-shell", but I'm not entirely sure if I'm doing so in accordance with your expectations. (I don't use Nix to do daily development, so I might be using it differently than you are.)

        Is there a way to be absolutely certain that we're using the same GHC binary?

        Here is what type ghc reports within the Nix shell:

        $ type ghc
ghc is /nix/store/smk3b8yj4c50643f4nsn6dyy7wzrvqzy-ghc-8.8.4-with-packages/bin/ghc

$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 8.8.4

        At some point I did gen-hie > hie.yaml or similar, maybe that makes a difference?

        I'm not sure. As noted above, I followed your instructions using a clean checkout with no other changes, so it may be worth verifying that you trigger the panic using the same steps that I undertook.

        Are you using NixOS or another system? Even Linux?

        I am using Nix on Ubuntu:

        $ nix --version
nix (Nix) 2.3.7

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.5 LTS
Release:        18.04
Codename:       bionic
      • Manuel Bärenz
        Manuel Bärenz @turion1 ·

        I believe your way to reproduce, in particular your nix usage, is correct. I have exactly the same GHC binary (unless nix is broken, which I don't believe in this case):

        $ type ghc
ghc is /nix/store/smk3b8yj4c50643f4nsn6dyy7wzrvqzy-ghc-8.8.4-with-packages/bin/ghc
$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 8.8.4

        My call to cabal repl looks pretty much like yours, and the error persists even if I do rm -rf dist* && cabal clean first. I also had two files, hie.yaml and .ghci, in the root directory, which I removed, with no effect.

        $ cabal repl
Warning: The package list for 'hackage.haskell.org' is 15 days old.
Run 'cabal update' to get the latest list of available packages.
Resolving dependencies...
Build profile: -w ghc-8.8.4 -O1
In order, the following will be built (use -v for more details):
 - essence-of-live-coding-0.2.4 (lib) (first run)
Configuring library for essence-of-live-coding-0.2.4..
Preprocessing library for essence-of-live-coding-0.2.4..
GHCi, version 8.8.4: https://www.haskell.org/ghc/  :? for help
[ 1 of 38] Compiling LiveCoding.LiveProgram ( src/LiveCoding/LiveProgram.lhs, interpreted )
[ 2 of 38] Compiling LiveCoding.Cell  ( src/LiveCoding/Cell.lhs, interpreted )
[ 3 of 38] Compiling LiveCoding.Debugger ( src/LiveCoding/Debugger.lhs, interpreted )
[ 4 of 38] Compiling LiveCoding.Coalgebra ( src/LiveCoding/Coalgebra.lhs, interpreted )
[ 5 of 38] Compiling LiveCoding.Cell.Monad ( src/LiveCoding/Cell/Monad.hs, interpreted )
[ 6 of 38] Compiling LiveCoding.Cell.Resample ( src/LiveCoding/Cell/Resample.hs, interpreted )
[ 7 of 38] Compiling LiveCoding.Cell.Monad.Trans ( src/LiveCoding/Cell/Monad/Trans.hs, interpreted )
[ 8 of 38] Compiling LiveCoding.Exceptions.Finite ( src/LiveCoding/Exceptions/Finite.lhs, interpreted )
[ 9 of 38] Compiling LiveCoding.Exceptions ( src/LiveCoding/Exceptions.lhs, interpreted )
[10 of 38] Compiling LiveCoding.External ( src/LiveCoding/External.hs, interpreted )
[11 of 38] Compiling LiveCoding.CellExcept ( src/LiveCoding/CellExcept.lhs, interpreted )
[12 of 38] Compiling LiveCoding.Cell.Feedback ( src/LiveCoding/Cell/Feedback.lhs, interpreted )
[13 of 38] Compiling LiveCoding.Cell.Util ( src/LiveCoding/Cell/Util.hs, interpreted )
[14 of 38] Compiling LiveCoding.Bind  ( src/LiveCoding/Bind.lhs, interpreted )
[15 of 38] Compiling LiveCoding.Forever ( src/LiveCoding/Forever.lhs, interpreted )
[16 of 38] Compiling LiveCoding.Debugger.StatePrint ( src/LiveCoding/Debugger/StatePrint.hs, interpreted )
[17 of 38] Compiling LiveCoding.LiveProgram.Monad.Trans ( src/LiveCoding/LiveProgram/Monad/Trans.hs, interpreted )
[18 of 38] Compiling LiveCoding.Handle ( src/LiveCoding/Handle.hs, interpreted )
[19 of 38] Compiling LiveCoding.Handle.Examples ( src/LiveCoding/Handle/Examples.hs, interpreted )
[20 of 38] Compiling LiveCoding.Cell.NonBlocking ( src/LiveCoding/Cell/NonBlocking.hs, interpreted )
[21 of 38] Compiling LiveCoding.Migrate.Migration ( src/LiveCoding/Migrate/Migration.hs, interpreted )
[22 of 38] Compiling LiveCoding.Migrate.Debugger ( src/LiveCoding/Migrate/Debugger.hs, interpreted )
[23 of 38] Compiling LiveCoding.Migrate.Cell ( src/LiveCoding/Migrate/Cell.hs, interpreted )
[24 of 38] Compiling LiveCoding.Migrate.Monad.Trans ( src/LiveCoding/Migrate/Monad/Trans.hs, interpreted )
[25 of 38] Compiling LiveCoding.Migrate ( src/LiveCoding/Migrate.lhs, interpreted )
[26 of 38] Compiling LiveCoding.LiveProgram.HotCodeSwap ( src/LiveCoding/LiveProgram/HotCodeSwap.lhs, interpreted )
[27 of 38] Compiling LiveCoding.Cell.HotCodeSwap ( src/LiveCoding/Cell/HotCodeSwap.hs, interpreted )
[28 of 38] Compiling LiveCoding.Preliminary.CellExcept.Applicative ( src/LiveCoding/Preliminary/CellExcept/Applicative.lhs, interpreted )
[29 of 38] Compiling LiveCoding.Preliminary.CellExcept ( src/LiveCoding/Preliminary/CellExcept.lhs, interpreted )
[30 of 38] Compiling LiveCoding.Preliminary.CellExcept.Monad ( src/LiveCoding/Preliminary/CellExcept/Monad.lhs, interpreted )
[31 of 38] Compiling LiveCoding.Preliminary.CellExcept.Newtype ( src/LiveCoding/Preliminary/CellExcept/Newtype.lhs, interpreted )
[32 of 38] Compiling LiveCoding.Preliminary.LiveProgram.LiveProgram2 ( src/LiveCoding/Preliminary/LiveProgram/LiveProgram2.lhs, interpreted )
[33 of 38] Compiling LiveCoding.Preliminary.LiveProgram.LiveProgramPreliminary ( src/LiveCoding/Preliminary/LiveProgram/LiveProgramPreliminary.lhs, interpreted )
[34 of 38] Compiling LiveCoding.Preliminary.LiveProgram.HotCodeSwap ( src/LiveCoding/Preliminary/LiveProgram/HotCodeSwap.lhs, interpreted )
[35 of 38] Compiling LiveCoding.RuntimeIO.Launch ( src/LiveCoding/RuntimeIO/Launch.hs, interpreted )
[36 of 38] Compiling LiveCoding.RuntimeIO ( src/LiveCoding/RuntimeIO.lhs, interpreted )
[37 of 38] Compiling LiveCoding.GHCi  ( src/LiveCoding/GHCi.hs, interpreted )
[38 of 38] Compiling LiveCoding       ( src/LiveCoding.hs, interpreted )
Ok, 38 modules loaded.
*LiveCoding> import Livghc: panic! (the 'impossible' happened)
  (GHC version 8.8.4 for x86_64-unknown-linux):
        ModOrigin: hidden module redefined

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

Leaving GHCi.

        I have this:

        $ ghc-pkg check
Warning: haddock-interfaces: /nix/store/sj101xblxzrp331xxcl7xiph5nwfq4bx-nats-1.1.2/share/doc/x86_64-linux-ghc-8.8.4/nats-1.1.2/html/nats.haddock doesn't exist or isn't a file
Warning: haddock-html: /nix/store/sj101xblxzrp331xxcl7xiph5nwfq4bx-nats-1.1.2/share/doc/x86_64-linux-ghc-8.8.4/nats-1.1.2/html doesn't exist or isn't a directory
Warning: haddock-interfaces: /nix/store/jb1pdmbhvknjlb0nqlrwx4fmqvqh5pw0-vault-0.3.1.4/share/doc/x86_64-linux-ghc-8.8.4/vault-0.3.1.4/html/vault.haddock doesn't exist or isn't a file
Warning: haddock-html: /nix/store/jb1pdmbhvknjlb0nqlrwx4fmqvqh5pw0-vault-0.3.1.4/share/doc/x86_64-linux-ghc-8.8.4/vault-0.3.1.4/html doesn't exist or isn't a directory

        But to be honest I don't know what it means or how I can deal with it.

      • Ryan Scott
        Ryan Scott @RyanGlScott ·
        Maintainer

        I have the same ghc-pkg check warnings, so I doubt that this is the culprit. And since the original reporter was using GHC 8.6, which predates .hie files, I doubt that hie.yaml is to blame. Nor do I strongly suspect .ghci, as I was unable to reproduce the bug with or without my own ~/.ghci file present. It's definitely a good idea to remove them for testing purposes, however.

        Just to be clear, are you able to reproducing the bug from a 100% clean checkout, like I do in #16996 (comment 302756)? The fact that you mention hie.yaml and .ghci files (which aren't checked in to the repo, AFAICT) makes me believe that you performed some other steps that are critical to triggering this bug, so I want to make sure that we are on the same page.

      • Manuel Bärenz
        Manuel Bärenz @turion1 ·

        Yes, even from a 100% clean checkout, the error occurs.

        But I have to name a success though: When I move away my ~/.cabal folder and reinitialize it, the error goes away! So apparently some state in there messed up my system.

        Do you want me to share the old folder, or look for something specific in there?

      • Ryan Scott
        Ryan Scott @RyanGlScott ·
        Maintainer

        But I have to name a success though: When I move away my ~/.cabal folder and reinitialize it, the error goes away! So apparently some state in there messed up my system.

        Interesting. I'm not sure if it's feasible to share your entire ~/.cabal folder (they typically grow to be quite large), but if you can, that would be one possible way to debug this further. In addition to that, you might also try migrating specific files from your moved-away ~/.cabal folder back to ~/.cabal to see if you can pinpoint which thing in particular is causing the panic.

      • Ellie Hermaszewska
        Ellie Hermaszewska @expipiplus1 ·

        If you do share your .cabal directory, make sure to censor your password if you have it stored in .cabal/config.

      • Please register or sign in to reply
    • Josh Freckleton
      Josh Freckleton @freckletonj ·

      Just confirming, I had Ryan Scott's identical bug, and reinitializing ~/.cabal fixes it for me.

    • Ryan Scott marked this issue as related to #19330 (closed)

      marked this issue as related to #19330 (closed)

    • Ryan Scott mentioned in issue #19330 (closed)

      mentioned in issue #19330 (closed)

    • Potato Hatsue
      Potato Hatsue @berberman ·

      I encountered this bug recently, and I found a way to reproduce it constantly (at least on my machine).

      • system: NixOS
      • ghc version: 8.10.3

      There is no global installed ghc or cabal-install on the system.

      steps to reproduce:

      • $ rm -r ~/.cabal/store (to make sure the environment is clean)
      • $ git clone https://github.com/haskell/haskell-language-server
      • $ cd haskell-language-server
      • $ cachix use haskell-language-server
      • $ nix-shell --command "cabal update && cabal build"
      • switch to an empty directory, then use $ nix-shell -p "haskellPackages.ghcWithPackages (p: with p; [ base cabal-install ])" to create a development shell
      • in the shell just created: $ cabal init && cabal repl

      In ghci, type :m , then press Tab as discussed above:

      λ> :m ghc: panic! (the 'impossible' happened)
  (GHC version 8.10.3:
	ModOrigin: hidden module redefined

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

Leaving GHCi.

      The error will disappear if I remove ~/.cabal/store.

      I suspect it was caused by mixing packages in nix environment and cabal store though without sufficient evidence.

      Haskell packages in new created nix shell:

      $ ghc-pkg list
/nix/store/fd7fp408bzmhpxy8mmcfznggw309mzwn-ghc-8.10.3-with-packages/lib/ghc-8.10.3/package.conf.d
    Cabal-3.2.1.0
    array-0.5.4.0
    base-4.14.1.0
    binary-0.8.8.0
    bytestring-0.10.12.0
    containers-0.6.2.1
    deepseq-1.4.4.0
    directory-1.3.6.0
    exceptions-0.10.4
    filepath-1.4.2.1
    ghc-8.10.3
    ghc-boot-8.10.3
    ghc-boot-th-8.10.3
    ghc-compact-0.1.0.0
    ghc-heap-8.10.3
    ghc-prim-0.6.1
    ghci-8.10.3
    haskeline-0.8.0.1
    hpc-0.6.1.0
    integer-gmp-1.0.3.0
    libiserv-8.10.3
    mtl-2.2.2
    parsec-3.1.14.0
    pretty-1.1.3.6
    process-1.6.9.0
    rts-1.0
    stm-2.5.0.0
    template-haskell-2.16.0.0
    terminfo-0.4.1.4
    text-1.2.4.1
    time-1.9.3
    transformers-0.5.6.2
    unix-2.7.2.2
    xhtml-3000.2.2.1

      This is my cabal store, which expires in one week (generated by following the above steps): https://we.tl/t-HKqoKmJN7t

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