[GHC] #14765: Levity polymorphism panic

[GHC]

#14765: Levity polymorphism panic
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        Reporter:  dfeuer            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.5
      Resolution:                    |             Keywords:
                                     |  LevityPolymorphism
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 goldfire):

 So are you suggesting that this new `mkCoreApp` doesn't use
 `isUnliftedType`, but instead re-creates it? Who reports the LP error? I
 suppose that could remain the same as it is right now... but then the
 check in `mkCoreApp` will be redundant.

 To be clear, I am OK with having a special `mkCoreApp` that doesn't panic
 on an LP argument used in the desugarer, as long as `isUnliftedType` still
 panics. My worry here is more about performance, but perhaps it would be
 an improvement over the status quo.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14765#comment:5>
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