[GHC] #15862: Panic with promoted types that Typeable doesn't support

[GHC]

#15862: Panic with promoted types that Typeable doesn't support
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.1
      Resolution:                    |             Keywords:  Typeable
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):

 Unboxed sums, too:

 {{{#!hs
 {-# LANGUAGE TypeInType #-}
 {-# LANGUAGE UnboxedSums #-}
 module Bug where

 import Type.Reflection

 data Quux = MkQuux (# Bool | Int #)

 bar :: TypeRep MkQuux
 bar = typeRep
 }}}
 {{{
 $ /opt/ghc/8.6.2/bin/ghc Bug.hs
 [1 of 1] Compiling Bug              ( Bug.hs, Bug.o )
 GHC error in desugarer lookup in Bug:
   attempting to use module ‘main:Bug’ (Bug.hs) which is not loaded
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.6.2 for x86_64-unknown-linux):
         initDs
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15862#comment:5>
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