[GHC] #10602: ghc panic: Template variable unbound in rewrite rule when compiling with -O2

[GHC]

#10602: ghc panic: Template variable unbound in rewrite rule when compiling with
-O2
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        Reporter:  pacak             |                   Owner:  bgamari
            Type:  bug               |                  Status:  infoneeded
        Priority:  highest           |               Milestone:  7.10.2
       Component:  Compiler          |                 Version:  7.10.2-rc2
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash                              |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by pacak):

 ghc 7.10.1 can compile the same code without any problems. This build of
 rc2 was compiled by ghc 7.10.1 plus a few patches on top related to event
 manager issues. Before submitting the bug I've confirmed that somebody
 from #ghc can reproduce it.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10602#comment:8>
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