diff options
Diffstat (limited to 'compiler/GHC/Tc/TyCl.hs')
| -rw-r--r-- | compiler/GHC/Tc/TyCl.hs | 46 |
1 files changed, 1 insertions, 45 deletions
diff --git a/compiler/GHC/Tc/TyCl.hs b/compiler/GHC/Tc/TyCl.hs index 19b19e36c7..25900f2103 100644 --- a/compiler/GHC/Tc/TyCl.hs +++ b/compiler/GHC/Tc/TyCl.hs @@ -4408,10 +4408,7 @@ checkValidDataCon dflags existential_ok tc con -- e.g. reject this: MkT :: T (forall a. a->a) -- Reason: it's really the argument of an equality constraint ; checkValidMonoType orig_res_ty - - -- Check for an escaping result kind - -- See Note [Check for escaping result kind] - ; checkEscapingKind con + ; checkEscapingKind (dataConWrapperType con) -- For /data/ types check that each argument has a fixed runtime rep -- If we are dealing with a /newtype/, we allow representation @@ -4576,47 +4573,6 @@ checkNewDataCon con ok_mult OneTy = True ok_mult _ = False - --- | Reject nullary data constructors where a type variable --- would escape through the result kind --- See Note [Check for escaping result kind] -checkEscapingKind :: DataCon -> TcM () -checkEscapingKind data_con - | null eq_spec, null theta, null arg_tys - , let tau_kind = typeKind res_ty - , Nothing <- occCheckExpand (univ_tvs ++ ex_tvs) tau_kind - -- Ensure that none of the tvs occur in the kind of the forall - -- /after/ expanding type synonyms. - -- See Note [Phantom type variables in kinds] in GHC.Core.Type - = failWithTc $ TcRnForAllEscapeError (dataConWrapperType data_con) tau_kind - | otherwise - = return () - where - (univ_tvs, ex_tvs, eq_spec, theta, arg_tys, res_ty) - = dataConFullSig data_con - -{- Note [Check for escaping result kind] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -Consider: - type T :: TYPE (BoxedRep l) - data T = MkT -This is not OK: we get - MkT :: forall l. T @l :: TYPE (BoxedRep l) -which is ill-kinded. - -For ordinary type signatures f :: blah, we make this check as part of kind-checking -the type signature; see Note [Escaping kind in type signatures] in GHC.Tc.Gen.HsType. -But for data constructors we check the type piecemeal, and there is no very -convenient place to do it. For example, note that it only applies for /nullary/ -constructors. If we had - data T = MkT Int -then the type of MkT would be MkT :: forall l. Int -> T @l, which is fine. - -So we make the check in checkValidDataCon. - -Historical note: we used to do the check in checkValidType (#20929 discusses). --} - ------------------------------- checkValidClass :: Class -> TcM () checkValidClass cls |