[GHC] #15517: -O0 and pattern synonyms triggers panic in trimJoinCont

[GHC]

#15517: -O0 and pattern synonyms triggers panic in trimJoinCont
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        Reporter:  sjakobi           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.4.3
      Resolution:                    |             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):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 I've attached the output of running `/opt/ghc/8.4.3/bin/ghc Bug.hs -dcore-
 lint -O0 -fforce-recomp`. The highlight is:

 {{{
 [1 of 1] Compiling Generics.MRSOP.Examples.RoseTreeTH ( Bug.hs, Bug.o )
 *** Core Lint errors : in result of Simplifier ***
 <no location info>: warning:
     [RHS of fail_a1dN :: Void#
                          -> El FamRoseInt ix_a1en
                          -> Rep Singl (El FamRoseInt) (Lkup ix_a1en
 CodesRoseInt)]
     idArity 2 exceeds arity imposed by the strictness signature <L,U>x:
 fail_a1dN
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15517#comment:3>
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