[GHC] #15881: GHC Panic: data A n (a :: n) :: a -> Type

[GHC]

#15881: GHC Panic: data A n (a :: n) :: a -> Type
-------------------------------------+-------------------------------------
           Reporter:  Iceland_jack   |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  8.6.3
          Component:  Compiler       |           Version:  8.6.2
           Keywords:  TypeInType     |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 {{{#!hs
 {-# Language KindSignatures #-}
 {-# Language PolyKinds      #-}

 import Data.Kind

 data A n (a :: n) :: a -> Type
 }}}

 causes a panic on 8.7.20181017

 {{{
 $ ~/code/headghc/inplace/bin/ghc-stage2 --interactive -ignore-dot-ghci
 665_bug.hs
 GHCi, version 8.7.20181017: http://www.haskell.org/ghc/  :? for help
 [1 of 1] Compiling Main             ( 665_bug.hs, interpreted )
 ghc-stage2: panic! (the 'impossible' happened)
   (GHC version 8.7.20181017 for x86_64-unknown-linux):
         ASSERT failed!
   Type-correct unfilled coercion hole {co_a1xR}
   Call stack:
       CallStack (from HasCallStack):
         callStackDoc, called at compiler/utils/Outputable.hs:1160:37 in
 ghc:Outputable
         pprPanic, called at compiler/utils/Outputable.hs:1219:5 in
 ghc:Outputable
         assertPprPanic, called at compiler/typecheck/TcHsSyn.hs:1805:99 in
 ghc:TcHsSyn

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

 >
 }}}

 and an assertion failure in 8.7.20181029
 {{{
 $ ~/code/unmodifiedghc/inplace/bin/ghc-stage2 --interactive -ignore-dot-
 ghci 665_bug.hs
 GHCi, version 8.7.20181029: http://www.haskell.org/ghc/  :? for help
 [1 of 1] Compiling Main             ( 665_bug.hs, interpreted )
 *** Exception: ASSERT failed! file compiler/types/TyCon.hs, line 420
 >
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15881>
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