[GHC] #12944: ghc master (8.1.20161206) panics with assertion failure with devel2 flavor and -O

[GHC]

#12944: ghc master (8.1.20161206) panics with assertion failure with devel2 flavor
and -O
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        Reporter:  pacak             |                Owner:
            Type:  bug               |               Status:  closed
        Priority:  highest           |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  8.1
  (CodeGen)                          |
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2844
       Wiki Page:                    |
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Comment (by simonpj):

 I know exactly what is going on here, thanks to the nice example in the
 Description. It's a long-standing bug in the implementation of `{-#
 SPECIALISE instance ... #-}`. Core Lint nails it instantly.

 I'll look at this early next week.

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12944#comment:11>
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