Ghc crashes when compiling happstack-server on ubuntu-docker

I am trying to install a package that requires happstack on docker. I recieved the following error:

src/Happstack/Server/Internal/Socket.hs:61:7:ghc: panic! (the 'impossible' happened)
  (GHC version 7.4.1 for x86_64-unknown-linux):
        Can't happen: pprExp (CompExp [])

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

It appears I am not the first to receive this error as I found the following paste on lpaste: http://lpaste.net/report/99343

This bug is hard to reproduce. I tried making a minimal case for it in which only haskell-platform was installed. In the minimal case, ghc DOES NOT crash.

This works:

FROM ubuntu
RUN apt-get update
RUN apt-get install -y haskell-platform
RUN cabal update
RUN cabal install --global happstack-server-7.3.3 

However, if you run the following docker file, ghc will crash:

FROM ubuntu
RUN apt-get update
RUN apt-get install -y haskell-platform git libghc-terminfo-dev libghc-haskeline-dev
RUN cabal update
RUN git clone --branch dev https://github.com/evancz/Elm.git
RUN git clone --branch dev https://github.com/evancz/elm-repl.git
RUN git clone  https://github.com/evancz/elm-get.git
RUN cd Elm; git checkout a815b2fbd00e76c0109b1ab916fe5d0eb184648c
RUN cd elm-repl; git checkout 6ab74981363e8e7fabc05083539891568e3c4f17
RUN cd elm-get ; git checkout c67a8ba285f6bfde0a520da1552c4c3443cfab8e
RUN cabal install --global Elm elm-repl elm-get Elm/server

Crashes with attached output.

Trac metadata

Trac field	Value
Version	7.4.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	low
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

changed weight to 3

added Tbug Trac import labels

closed

Closing as 'fixed' since the issue is fixed in upcoming template-haskell-2.9:

https://github.com/ghc/packages-template-haskell/commit/d7b864b7ddb0e8c2f58d08dfd50e843eb8966b90

However, that fix will be present only in GHC 7.8, AFAIK 7.6 (or 7.4) is not going to have another bugfix release. Probably you can pester happstack's maintainers, a workaround should be easy.

PS. Regarding reproduction: pprExp 0 (CompE []) in GHCi with TH should work.

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed

added Plow label