diff options
Diffstat (limited to 'compiler/GHC/Tc/Gen/HsType.hs')
| -rw-r--r-- | compiler/GHC/Tc/Gen/HsType.hs | 55 |
1 files changed, 1 insertions, 54 deletions
diff --git a/compiler/GHC/Tc/Gen/HsType.hs b/compiler/GHC/Tc/Gen/HsType.hs index 313ae9cf58..a25a7320e4 100644 --- a/compiler/GHC/Tc/Gen/HsType.hs +++ b/compiler/GHC/Tc/Gen/HsType.hs @@ -60,7 +60,7 @@ module GHC.Tc.Gen.HsType ( checkClassKindSig, -- Pattern type signatures - tcHsPatSigType, tcPatSig, + tcHsPatSigType, -- Error messages funAppCtxt, addTyConFlavCtxt @@ -75,7 +75,6 @@ import GHC.Tc.Utils.Monad import GHC.Tc.Types.Origin import GHC.Core.Predicate import GHC.Tc.Types.Constraint -import GHC.Tc.Types.Evidence import GHC.Tc.Utils.Env import GHC.Tc.Utils.TcMType import GHC.Tc.Validity @@ -3390,58 +3389,6 @@ tcHsPatSigType ctxt sig_ty -- NB: tv's Name may be fresh (in the case of newPatSigTyVar) ; return (name, tv) } -tcPatSig :: Bool -- True <=> pattern binding - -> LHsSigWcType GhcRn - -> ExpSigmaType - -> TcM (TcType, -- The type to use for "inside" the signature - [(Name,TcTyVar)], -- The new bit of type environment, binding - -- the scoped type variables - [(Name,TcTyVar)], -- The wildcards - HsWrapper) -- Coercion due to unification with actual ty - -- Of shape: res_ty ~ sig_ty -tcPatSig in_pat_bind sig res_ty - = do { (sig_wcs, sig_tvs, sig_ty) <- tcHsPatSigType PatSigCtxt sig - -- sig_tvs are the type variables free in 'sig', - -- and not already in scope. These are the ones - -- that should be brought into scope - - ; if null sig_tvs then do { - -- Just do the subsumption check and return - wrap <- addErrCtxtM (mk_msg sig_ty) $ - tcSubTypeET PatSigOrigin PatSigCtxt res_ty sig_ty - ; return (sig_ty, [], sig_wcs, wrap) - } else do - -- Type signature binds at least one scoped type variable - - -- A pattern binding cannot bind scoped type variables - -- It is more convenient to make the test here - -- than in the renamer - { when in_pat_bind (addErr (patBindSigErr sig_tvs)) - - -- Now do a subsumption check of the pattern signature against res_ty - ; wrap <- addErrCtxtM (mk_msg sig_ty) $ - tcSubTypeET PatSigOrigin PatSigCtxt res_ty sig_ty - - -- Phew! - ; return (sig_ty, sig_tvs, sig_wcs, wrap) - } } - where - mk_msg sig_ty tidy_env - = do { (tidy_env, sig_ty) <- zonkTidyTcType tidy_env sig_ty - ; res_ty <- readExpType res_ty -- should be filled in by now - ; (tidy_env, res_ty) <- zonkTidyTcType tidy_env res_ty - ; let msg = vcat [ hang (text "When checking that the pattern signature:") - 4 (ppr sig_ty) - , nest 2 (hang (text "fits the type of its context:") - 2 (ppr res_ty)) ] - ; return (tidy_env, msg) } - -patBindSigErr :: [(Name,TcTyVar)] -> SDoc -patBindSigErr sig_tvs - = hang (text "You cannot bind scoped type variable" <> plural sig_tvs - <+> pprQuotedList (map fst sig_tvs)) - 2 (text "in a pattern binding signature") - {- Note [Pattern signature binders] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ See also Note [Type variables in the type environment] in GHC.Tc.Utils. |