[GHC] #7235: "panic!" when compiling happstack-server-7.0.4

[GHC]

#7235: "panic!" when compiling happstack-server-7.0.4
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 Reporter:  guest                      |          Owner:                  
     Type:  bug                        |         Status:  new             
 Priority:  normal                     |      Component:  Compiler        
  Version:  7.4.2                      |       Keywords:                  
       Os:  Linux                      |   Architecture:  Unknown/Multiple
  Failure:  GHC rejects valid program  |       Testcase:                  
Blockedby:                             |       Blocking:                  
  Related:                             |  
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 I wanted to install happstack-server-7.0.4 for a project, then the
 compiler told me to file this as a bug:


 {{{
 $ cabal-dev install happstack-server-7.0.4
 Resolving dependencies...
 Configuring happstack-server-7.0.4...
 Building happstack-server-7.0.4...
 Preprocessing library happstack-server-7.0.4...
 [ 1 of 38] Compiling Happstack.Server.Internal.LazyLiner (
 src/Happstack/Server/Internal/LazyLiner.hs,
 dist/build/Happstack/Server/Internal/LazyLiner.o )
 [ 2 of 38] Compiling Happstack.Server.Internal.SocketTH (
 src/Happstack/Server/Internal/SocketTH.hs,
 dist/build/Happstack/Server/Internal/SocketTH.o )
 Loading package ghc-prim ... linking ... done.
 Loading package integer-gmp ... linking ... done.
 Loading package base ... linking ... done.
 Loading package bytestring-0.9.2.1 ... linking ... done.
 Loading package zlib-0.5.3.3 ... linking ... done.
 Loading package xhtml-3000.2.1 ... linking ... done.
 Loading package utf8-string-0.3.7 ... linking ... done.
 Loading package array-0.4.0.0 ... linking ... done.
 Loading package deepseq-1.3.0.0 ... linking ... done.
 Loading package containers-0.5.0.0 ... linking ... done.
 Loading package pretty-1.1.1.0 ... linking ... done.
 Loading package template-haskell ... linking ... done.
 Loading package text-0.11.2.3 ... linking ... done.
 Loading package system-filepath-0.4.7 ... linking ... done.
 Loading package syb-0.3.7 ... linking ... done.
 Loading package transformers-0.3.0.0 ... linking ... done.
 Loading package mtl-2.1.2 ... linking ... done.
 Loading package parsec-3.1.3 ... linking ... done.
 Loading package unix-2.5.1.1 ... linking ... done.
 Loading package network-2.3.1.0 ... linking ... done.
 Loading package sendfile-0.7.6 ... linking ... done.
 Loading package base-unicode-symbols-0.2.2.4 ... linking ... done.
 Loading package transformers-base-0.4.1 ... linking ... done.
 Loading package monad-control-0.3.1.4 ... linking ... done.
 Loading package html-1.0.1.2 ... linking ... done.
 Loading package filepath-1.3.0.0 ... linking ... done.
 Loading package old-locale-1.0.0.4 ... linking ... done.
 Loading package old-time-1.1.0.0 ... linking ... done.
 Loading package directory-1.1.0.2 ... linking ... done.
 Loading package process-1.1.0.1 ... linking ... done.
 Loading package time-1.4 ... linking ... done.
 Loading package hslogger-1.2.0 ... linking ... done.
 Loading package extensible-exceptions-0.1.1.4 ... linking ... done.
 Loading package blaze-builder-0.3.1.0 ... linking ... done.
 Loading package blaze-markup-0.5.1.0 ... linking ... done.
 Loading package blaze-html-0.5.1.0 ... linking ... done.
 Loading package base64-bytestring-0.1.2.0 ... linking ... done.
 [ 3 of 38] Compiling Happstack.Server.Internal.Socket (
 src/Happstack/Server/Internal/Socket.hs,
 dist/build/Happstack/Server/Internal/Socket.o )

 src/Happstack/Server/Internal/Socket.hs:66:7:ghc: panic! (the 'impossible'
 happened)
   (GHC version 7.4.2 for x86_64-unknown-linux):
         Can't happen: pprExp (CompExp [])

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

 cabal: Error: some packages failed to install:
 happstack-server-7.0.4 failed during the building phase. The exception
 was:
 ExitFailure 1
 }}}

 I get the exact same output for happstack-server-7.0.3 as well. I am quite
 stumped with this one because just minutes ago, I was able to compile it
 just fine.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7235>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler