[GHC] #16152: Core lint error from PartialTypeSignatures

8 Jan 2019


      #16152: Core lint error from PartialTypeSignatures
-------------------------------------+-------------------------------------
           Reporter:  Iceland_jack   |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.7
           Keywords:                 |  Operating System:  Unknown/Multiple
  PartialTypeSignatures              |
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 {{{#!hs
 {-# Language PartialTypeSignatures #-}
 {-# Language PolyKinds             #-}
 {-# Language ScopedTypeVariables   #-}

 {-# Options_GHC -dcore-lint #-}

 top :: forall f. _
 top = undefined where

   x :: forall a. f a
   x = undefined
 }}}

 causes Core lint errors:

 {{{
 $ ~/../inplace/bin/ghc-stage2 --interactive -ignore-dot-ghci 922_bug.hs
 GHCi, version 8.7.20181230: https://www.haskell.org/ghc/  :? for help
 [1 of 1] Compiling Main             ( 922_bug.hs, interpreted )
 *** Core Lint errors : in result of Desugar (before optimization) ***
 <no location info>: warning:
     In the type ‘forall (f :: k_a1z6 -> *) w. w’
     @ k_a1z6 is out of scope
 *** Offending Program ***
 Rec {
 $trModule :: Module
 [LclIdX]
 $trModule = Module (TrNameS "main"#) (TrNameS "Main"#)

 top :: forall (f :: k_a1z6 -> *) w. w
 [LclIdX]
 top
   = \ (@ (f_a2BY :: k_a1z6 -> *)) (@ w_a2BZ) ->
       (\ (@ k_a1z6) (@ (f_a1yV :: k_a1z6 -> *)) (@ w_a1yN) ->
          let {
            $dIP_a2BO :: ?callStack::CallStack
            [LclId]
            $dIP_a2BO
              = emptyCallStack
                `cast` (Sym (N:IP[0] <"callStack">_N <CallStack>_N)
                        :: CallStack ~R# (?callStack::CallStack)) } in
          let {
            $dIP_a2BD :: HasCallStack
            [LclId]
            $dIP_a2BD
              = (pushCallStack
                   (unpackCString# "undefined"#,
                    SrcLoc
                      (unpackCString# "main"#)
                      (unpackCString# "Main"#)
                      (unpackCString# "922_bug.hs"#)
                      (I# 8#)
                      (I# 7#)
                      (I# 8#)
                      (I# 16#))
                   ($dIP_a2BO
                    `cast` (N:IP[0] <"callStack">_N <CallStack>_N
                            :: (?callStack::CallStack) ~R# CallStack)))
                `cast` (Sym (N:IP[0] <"callStack">_N <CallStack>_N)
                        :: CallStack ~R# (?callStack::CallStack)) } in
          letrec {
            top_a1yW :: w_a1yN
            [LclId]
            top_a1yW
              = letrec {
                  x_a1yv :: forall (a :: k_a1z6). f_a1yV a
                  [LclId]
                  x_a1yv
                    = \ (@ (a_a1zd :: k_a1z6)) ->
                        let {
                          $dIP_a2BP :: ?callStack::CallStack
                          [LclId]
                          $dIP_a2BP
                            = emptyCallStack
                              `cast` (Sym (N:IP[0] <"callStack">_N
 <CallStack>_N)
                                      :: CallStack ~R#
 (?callStack::CallStack)) } in
                        let {
                          $dIP_a2Bz :: HasCallStack
                          [LclId]
                          $dIP_a2Bz
                            = (pushCallStack
                                 (unpackCString# "undefined"#,
                                  SrcLoc
                                    (unpackCString# "main"#)
                                    (unpackCString# "Main"#)
                                    (unpackCString# "922_bug.hs"#)
                                    (I# 11#)
                                    (I# 7#)
                                    (I# 11#)
                                    (I# 16#))
                                 ($dIP_a2BP
                                  `cast` (N:IP[0] <"callStack">_N
 <CallStack>_N
                                          :: (?callStack::CallStack) ~R#
 CallStack)))
                              `cast` (Sym (N:IP[0] <"callStack">_N
 <CallStack>_N)
                                      :: CallStack ~R#
 (?callStack::CallStack)) } in
                        break<0>() undefined @ 'LiftedRep @ (f_a1yV a_a1zd)
 $dIP_a2Bz; } in
                break<1>() undefined @ 'LiftedRep @ w_a1yN $dIP_a2BD; } in
          top_a1yW)
         @ Any @ Any @ w_a2BZ
 end Rec }

 *** End of Offense ***


 <no location info>: error:
 Compilation had errors


 *** Exception: ExitFailure 1
...
}}}

-- 
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16152
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