[GHC] #8205: the 'impossible' happened : expectJust block_order

[GHC]

#8205: the 'impossible' happened : expectJust block_order
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        Reporter:  erikd                |            Owner:  jstolarek
            Type:  bug                  |           Status:  closed
        Priority:  normal               |        Milestone:
       Component:  Compiler             |          Version:  7.7
      Resolution:  fixed                |         Keywords:
Operating System:  Unknown/Multiple     |     Architecture:
 Type of failure:  Building GHC failed  |  Unknown/Multiple
       Test Case:                       |       Difficulty:  Unknown
        Blocking:                       |       Blocked By:
                                        |  Related Tickets:
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Comment (by kazu-yamamoto):

 I installed GHC head on 32bit Linux today and tried to install mighttpd2.
 But I got the following error:

 {{{
 Building vault-0.2.0.4...
 Failed to install vault-0.2.0.4
 Last 10 lines of the build log ( /home/kazu/work/mighttpd2/.cabal-
 sandbox/logs/vault-0.2.0.4.log ):
 Preprocessing library vault-0.2.0.4...
 [1 of 4] Compiling Data.Unique.Really ( src/Data/Unique/Really.hs, dist
 /dist-sandbox-a79d14af/build/Data/Unique/Really.o )
 [2 of 4] Compiling Data.Vault.ST_GHC ( src/Data/Vault/ST_GHC.hs, dist
 /dist-sandbox-a79d14af/build/Data/Vault/ST_GHC.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.7.20130920 for i386-unknown-linux):
         allocateRegsAndSpill: Cannot read from uninitialized register
     %vI_s4Zf

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

 What should I do?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8205#comment:36>
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