[GHC] #12650: Too many warnigns about consistentCafInfo

[GHC]

#12650: Too many warnigns about consistentCafInfo
-------------------------------------+-------------------------------------
           Reporter:  nomeata        |             Owner:
               Type:  task           |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 Building GHC with debug on yiedls in many (97!) warnings of the form
 {{{
 WARNING: file compiler/stgSyn/CoreToStg.hs, line 252
   $fFunctorIOEnv True False
 }}}

 The code in question is
 {{{
 -- Assertion helper: this checks that the CafInfo on the Id matches
 -- what CoreToStg has figured out about the binding's SRT.  The
 -- CafInfo will be exact in all cases except when CorePrep has
 -- floated out a binding, in which case it will be approximate.
 consistentCafInfo :: Id -> GenStgBinding Var Id -> Bool
 consistentCafInfo id bind
   = WARN( not (exact || is_sat_thing) , ppr id <+> ppr id_marked_caffy <+>
 ppr binding_is_caffy )
     safe
   where
     safe  = id_marked_caffy || not binding_is_caffy
     exact = id_marked_caffy == binding_is_caffy
     id_marked_caffy  = mayHaveCafRefs (idCafInfo id)
     binding_is_caffy = topStgBindHasCafRefs bind
     is_sat_thing = occNameFS (nameOccName (idName id)) == fsLit "sat"
 }}}

 It would be nice to have less warnings, to make them more useful. I don’t
 know if the warning is not right, or if there is something that can be
 fixed about the thing it is warning about.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12650>
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