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Diffstat (limited to 'compiler/GHC/Tc/Utils/Env.hs')
| -rw-r--r-- | compiler/GHC/Tc/Utils/Env.hs | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/compiler/GHC/Tc/Utils/Env.hs b/compiler/GHC/Tc/Utils/Env.hs index 1b13d82869..9c0971aa42 100644 --- a/compiler/GHC/Tc/Utils/Env.hs +++ b/compiler/GHC/Tc/Utils/Env.hs @@ -692,8 +692,11 @@ tcCheckUsage name id_mult thing_inside -- -- It works nicely in practice. (promote_mult, _, _, _) = mapTyCo mapper - mapper = TyCoMapper { tcm_tyvar = \ () tv -> do { _ <- promoteTyVar tv - ; zonkTcTyVar tv } + mapper = TyCoMapper { tcm_tyvar = \ () tv -> if isMetaTyVar tv + then do { tclvl <- getTcLevel + ; _ <- promoteMetaTyVarTo tclvl tv + ; zonkTcTyVar tv } + else return (mkTyVarTy tv) , tcm_covar = \ () cv -> return (mkCoVarCo cv) , tcm_hole = \ () h -> return (mkHoleCo h) , tcm_tycobinder = \ () tcv _flag -> return ((), tcv) |