[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
-------------------------------------+-------------------------------------
        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:
                                     |  Unknown/Multiple
 Type of failure:  Compile-time      |            Test Case:
  crash or panic                     |  deSugar/should_compile/T12944
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2844
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by simonpj):

 * testcase:   => deSugar/should_compile/T12944


--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12944#comment:15>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler