[GHC] #8355: Core lint error/warnings with `primitive-0.5.1.0`

[GHC]

#8355: Core lint error/warnings with `primitive-0.5.1.0`
----------------------------+----------------------------------------------
       Reporter:  hvr       |             Owner:
           Type:  bug       |            Status:  new
       Priority:  highest   |         Milestone:  7.8.1
      Component:  Compiler  |           Version:  7.6.3
       Keywords:            |  Operating System:  Unknown/Multiple
   Architecture:            |   Type of failure:  GHC rejects valid program
  Unknown/Multiple          |         Test Case:
     Difficulty:  Unknown   |          Blocking:
     Blocked By:            |
Related Tickets:            |
----------------------------+----------------------------------------------
 When compiling [http://hackage.haskell.org/package/primitive-0.5.1.0
 primitive-0.5.1.0] with `--ghc-option=-dcore-lint`,

 GHC 7.4.2 just emits a single warning:

 {{{
 [10 of 10] Compiling Data.Primitive.MutVar ( Data/Primitive/MutVar.hs,
 dist/build/Data/Primitive/MutVar.o )
 *** Core Lint warnings : in result of Desugar (after optimization) ***
 <no location info>:
     [RHS of $c/=_a724 :: forall s_a70h a_a70i.
                          Data.Primitive.MutVar.MutVar s_a70h a_a70i
                          -> Data.Primitive.MutVar.MutVar s_a70h a_a70i ->
 GHC.Types.Bool]
     INLINE binder is (non-rule) loop breaker: $c/=_a724
 }}}

 However, with GHC 7.6.3, an error is produced:
 {{{
 [ 5 of 10] Compiling Data.Primitive.Types ( Data/Primitive/Types.hs,
 dist/build/Data/Primitive/Types.o )
 *** Core Lint errors : in result of Desugar (after optimization) ***
 <no location info>: Warning:
     In the type `GHC.Prim.State# GHC.Prim.RealWorld
                  ~ GHC.Prim.State# (Control.Monad.Primitive.PrimState
 GHC.Types.IO)'
     Kind application error in
       type `GHC.Prim.State# GHC.Prim.RealWorld
             ~ GHC.Prim.State# (Control.Monad.Primitive.PrimState
 GHC.Types.IO)'
       Function kind = forall (k_1c :: BOX). k_1c -> k_1c -> Constraint
       Arg kinds = [(*, BOX), (GHC.Prim.State# GHC.Prim.RealWorld, #),
                    (GHC.Prim.State# (Control.Monad.Primitive.PrimState
 GHC.Types.IO),
                     #)]
 <no location info>: Warning:
     In the type `GHC.Prim.State# GHC.Prim.RealWorld
                  ~ GHC.Prim.State# (Control.Monad.Primitive.PrimState
 GHC.Types.IO)'
     Kind application error in
       type `GHC.Prim.State# GHC.Prim.RealWorld
             ~ GHC.Prim.State# (Control.Monad.Primitive.PrimState
 GHC.Types.IO)'
       Function kind = forall (k_1c :: BOX). k_1c -> k_1c -> Constraint
       Arg kinds = [(*, BOX), (GHC.Prim.State# GHC.Prim.RealWorld, #),
                    (GHC.Prim.State# (Control.Monad.Primitive.PrimState
 GHC.Types.IO),
                     #)]
 {-# LINE 142 "Data/Primitive/Types.hs #-}: Warning:
     [RHS of cobox_a2gR :: GHC.Prim.State# GHC.Prim.RealWorld
                           ~ GHC.Prim.State#
 (Control.Monad.Primitive.PrimState GHC.Types.IO)]
     The type of this binder doesn't match the type of its RHS: cobox_a2gR
     Binder's type: GHC.Prim.State# GHC.Prim.RealWorld
                    ~ GHC.Prim.State# (Control.Monad.Primitive.PrimState
 GHC.Types.IO)
     Rhs type: GHC.Prim.State# GHC.Prim.RealWorld
               ~ GHC.Prim.State# (Control.Monad.Primitive.PrimState
 GHC.Types.IO)
 }}}

 The core-lint error persists in GHC HEAD/7.7, blocking us from updating
 GHC's in-tree `primitive`/`vector` packages.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8355>
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