diff options
Diffstat (limited to 'compiler/GHC/Tc/Instance/FunDeps.hs')
| -rw-r--r-- | compiler/GHC/Tc/Instance/FunDeps.hs | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/compiler/GHC/Tc/Instance/FunDeps.hs b/compiler/GHC/Tc/Instance/FunDeps.hs index 4b45f2fa38..cfbebcd368 100644 --- a/compiler/GHC/Tc/Instance/FunDeps.hs +++ b/compiler/GHC/Tc/Instance/FunDeps.hs @@ -227,11 +227,12 @@ improveFromInstEnv inst_env mk_loc cls tys where (cls_tvs, cls_fds) = classTvsFds cls instances = classInstances inst_env cls - rough_tcs = roughMatchTcs tys + rough_tcs = RM_KnownTc (className cls) : roughMatchTcs tys pred = mkClassPred cls tys + improveClsFD :: [TyVar] -> FunDep TyVar -- One functional dependency from the class -> ClsInst -- An instance template -> [Type] -> [RoughMatchTc] -- Arguments of this (C tys) predicate @@ -673,8 +674,9 @@ trimRoughMatchTcs :: [TyVar] -> FunDep TyVar -> [RoughMatchTc] -> [RoughMatchTc] -- Hence, we Nothing-ise the tb and tc types right here -- -- Result list is same length as input list, just with more Nothings -trimRoughMatchTcs clas_tvs (ltvs, _) mb_tcs - = zipWith select clas_tvs mb_tcs +trimRoughMatchTcs _clas_tvs _ [] = panic "trimRoughMatchTcs: nullary [RoughMatchTc]" +trimRoughMatchTcs clas_tvs (ltvs, _) (cls:mb_tcs) + = cls : zipWith select clas_tvs mb_tcs where select clas_tv mb_tc | clas_tv `elem` ltvs = mb_tc - | otherwise = OtherTc + | otherwise = RM_WildCard |