[GHC] #8484: Compile-time panic

[GHC]

#8484: Compile-time panic
-------------------------------------+-------------------------------------
        Reporter:  Taymon            |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.6.3
      Resolution:                    |                Keywords:
Operating System:  Linux             |            Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash                              |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------
Changes (by zilinc):

 * status:  closed => new
 * resolution:  worksforme =>


Comment:

 {{{
 zilinc at zilinc-dell-xps:~/research/haskell/panic-parsing$ cabal build
 --with-ghc=ghc-7.8.4
 Building panic-parsing-0.1.0.0...
 Preprocessing executable 'panic-parsing' for panic-parsing-0.1.0.0...
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.8.4 for x86_64-unknown-linux):
         While parsing "/home/zilinc/research/haskell/panic-parsing/.cabal-
 sandbox/x86_64-linux-ghc-7.10.2-packages.conf.d/package.cache":
 demandInput: not enough bytes

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

 To reproduce it, I did:
 * create a new cabal package (`cabal init`), with a sandbox (`cabal
 sandbox init`)
 * create a Main module, can be as simple as:
 {{{#!hs
 module Main where
 main = putStrLn "done"
 }}}
 * create a `cabal.config` file, with
 {{{
 with-compiler: ghc-7.10.2
 with-hc-pkg: ghc-pkg-7.10.2
 }}}
 * `cabal configure && cabal build`. everything should be okay so far
 * do `cabal build --with-ghc=ghc-7.8.4`, then I got panic

 What I did may not be correct, but either way `impossible` should not
 happen.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8484#comment:3>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler