diff options
| -rw-r--r-- | ghc/compiler/hsSyn/HsTypes.lhs | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/ghc/compiler/hsSyn/HsTypes.lhs b/ghc/compiler/hsSyn/HsTypes.lhs index 76076ff495..f1343a39ef 100644 --- a/ghc/compiler/hsSyn/HsTypes.lhs +++ b/ghc/compiler/hsSyn/HsTypes.lhs @@ -177,10 +177,14 @@ mkHsForAllTy exp tvs (L _ []) ty = mk_forall_ty exp tvs ty mkHsForAllTy exp tvs ctxt ty = HsForAllTy exp tvs ctxt ty -- mk_forall_ty makes a pure for-all type (no context) -mk_forall_ty Explicit [] ty = unLoc ty -- Explicit for-all with no tyvars -mk_forall_ty exp tvs (L _ (HsParTy ty)) = mk_forall_ty exp tvs ty +mk_forall_ty exp tvs (L _ (HsParTy ty)) = mk_forall_ty exp tvs ty mk_forall_ty exp1 tvs1 (L _ (HsForAllTy exp2 tvs2 ctxt ty)) = mkHsForAllTy (exp1 `plus` exp2) (tvs1 ++ tvs2) ctxt ty -mk_forall_ty exp tvs ty = HsForAllTy exp tvs (L noSrcSpan []) ty +mk_forall_ty exp tvs ty = HsForAllTy exp tvs (L noSrcSpan []) ty + -- Even if tvs is empty, we still make a HsForAll! + -- In the Implicit case, this signals the place to do implicit quantification + -- In the Explicit case, it prevents implicit quantification + -- (see the sigtype production in Parser.y.pp) + -- so that (forall. ty) isn't implicitly quantified Implicit `plus` Implicit = Implicit exp1 `plus` exp2 = Explicit |