Re: [GHC] #15789: GHC panic using visible kind applications and a higher-rank kind

20 Oct 2018

      #15789: GHC panic using visible kind applications and a higher-rank kind
-------------------------------------+-------------------------------------
        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Description changed by Iceland_jack:

Old description:
...
Using visible kind applications (#12045):
{{{#!hs
{-# Language LiberalTypeSynonyms #-}
{-# Language PolyKinds          #-}
{-# Language RankNTypes          #-}
{-# Language DataKinds           #-}
import Data.Kind
type Cat ob = ob -> ob -> Type
data Zero :: forall (cat :: forall xx. xx -> Type) a. forall b. Cat
(forall b. cat b u)
}}}
{{{
$ ghci -ignore-dot-ghci 546_bug.hs
GHCi, version 8.7.20181017: http://www.haskell.org/ghc/  :? for help
[1 of 1] Compiling Main             ( 546_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_a1yl}
  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
...
}}}
New description:

 Using visible kind applications (#12045):

 {{{#!hs
 {-# Language LiberalTypeSynonyms #-}
 {-# Language PolyKinds           #-}
 {-# Language RankNTypes          #-}
 {-# Language DataKinds           #-}

 import Data.Kind

 type Cat ob = ob -> ob -> Type

 data Zero :: forall (cat :: forall xx. xx -> Type) a. forall b. Cat
 (forall b. cat b u)
 }}}

 {{{
 $ ghci -ignore-dot-ghci 546_bug.hs
 GHCi, version 8.7.20181017: http://www.haskell.org/ghc/  :? for help
 [1 of 1] Compiling Main             ( 546_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_a1yl}
   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
...
}}}

--

-- 
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15789#comment:2
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler