Re: [GHC] #15979: Core Lint error with LiberalTypeSynonyms

7 Dec 2018

      #15979: Core Lint error with LiberalTypeSynonyms
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler          |              Version:  8.6.2
      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):

 Another one:

 {{{#!hs
 {-# LANGUAGE KindSignatures #-}
 {-# LANGUAGE RankNTypes #-}
 module Bug where

 import Data.Kind

 type Foo = forall (f :: Type -> Type). f

 f :: Foo Int -> Foo Int
 f x = x
 }}}
 {{{
 $ /opt/ghc/8.6.2/bin/ghc Bug.hs -dcore-lint
 [1 of 1] Compiling Bug              ( Bug.hs, Bug.o )
 *** Core Lint errors : in result of Desugar (before optimization) ***
 <no location info>: warning:
     In the type ‘Foo Int -> Foo Int’
     Non-*-like kind when *-like expected: * -> *
     when checking the body of forall: forall (f :: * -> *). f
 *** Offending Program ***
 Rec {
 $trModule :: Module
 [LclIdX]
 $trModule = Module (TrNameS "main"#) (TrNameS "Bug"#)

 f :: Foo Int -> Foo Int
 [LclIdX]
 f = \ (x_aWa :: Foo Int) -> x_aWa
 end Rec }

 *** End of Offense ***

 <no location info>: error:
 Compilation had errors
 }}}

-- 
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15979#comment:5
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