Too many warnings about consistentCafInfo

Building GHC with debug on yields 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.