[GHC] #14880: GHC panic: updateRole

[GHC]

#14880: GHC panic: updateRole
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        Reporter:  RyanGlScott       |                Owner:  goldfire
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.2.2
  checker)                           |
      Resolution:                    |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #15076            |  Differential Rev(s):  Phab:D4769
       Wiki Page:                    |
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Comment (by RyanGlScott):

 You should be able to fix that Haddock compilation error with this patch:

 {{{#!diff
 diff --git a/haddock-api/src/Haddock/Convert.hs b/haddock-
 api/src/Haddock/Convert.hs
 index bf6fbab..9f7b15d 100644
 --- a/haddock-api/src/Haddock/Convert.hs
 +++ b/haddock-api/src/Haddock/Convert.hs
 @@ -512,8 +512,7 @@ synifyType _ (TyConApp tc tys)
                    = splitAtList  tys binders
              result_kind  = mkTyConKind remaining_binders res_kind
              result_vars  = tyCoVarsOfType result_kind
 -            dropped_vars = fvVarSet $
 -                           mapUnionFV injectiveVarsOfBinder
 dropped_binders
 +            dropped_vars = mapUnionVarSet injectiveVarsOfBinder
 dropped_binders

          in not (subVarSet result_vars dropped_vars)

 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14880#comment:31>
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