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-rw-r--r--compiler/GHC/Tc/Gen/Arrow.hs18
-rw-r--r--compiler/GHC/Tc/Gen/Bind.hs10
-rw-r--r--compiler/GHC/Tc/Gen/Expr.hs804
-rw-r--r--compiler/GHC/Tc/Gen/Expr.hs-boot27
-rw-r--r--compiler/GHC/Tc/Gen/Foreign.hs2
-rw-r--r--compiler/GHC/Tc/Gen/HsType.hs55
-rw-r--r--compiler/GHC/Tc/Gen/Match.hs63
-rw-r--r--compiler/GHC/Tc/Gen/Pat.hs138
-rw-r--r--compiler/GHC/Tc/Gen/Rule.hs2
-rw-r--r--compiler/GHC/Tc/Gen/Splice.hs10
-rw-r--r--compiler/GHC/Tc/Module.hs38
-rw-r--r--compiler/GHC/Tc/TyCl/PatSyn.hs9
-rw-r--r--compiler/GHC/Tc/Types/Origin.hs2
-rw-r--r--compiler/GHC/Tc/Utils/Instantiate.hs4
-rw-r--r--compiler/GHC/Tc/Utils/Monad.hs3
-rw-r--r--compiler/GHC/Tc/Utils/TcMType.hs17
-rw-r--r--compiler/GHC/Tc/Utils/TcType.hs12
-rw-r--r--compiler/GHC/Tc/Utils/Unify.hs255
-rw-r--r--compiler/GHC/Tc/Utils/Zonk.hs5
19 files changed, 762 insertions, 712 deletions
diff --git a/compiler/GHC/Tc/Gen/Arrow.hs b/compiler/GHC/Tc/Gen/Arrow.hs
index 58bbb40da2..94e90acd24 100644
--- a/compiler/GHC/Tc/Gen/Arrow.hs
+++ b/compiler/GHC/Tc/Gen/Arrow.hs
@@ -14,7 +14,7 @@ module GHC.Tc.Gen.Arrow ( tcProc ) where
import GhcPrelude
-import {-# SOURCE #-} GHC.Tc.Gen.Expr( tcMonoExpr, tcInferRho, tcSyntaxOp, tcCheckId, tcPolyExpr )
+import {-# SOURCE #-} GHC.Tc.Gen.Expr( tcLExpr, tcInferRho, tcSyntaxOp, tcCheckId, tcCheckExpr )
import GHC.Hs
import GHC.Tc.Gen.Match
@@ -91,7 +91,7 @@ tcProc pat cmd exp_ty
; (co, (exp_ty1, res_ty)) <- matchExpectedAppTy exp_ty
; (co1, (arr_ty, arg_ty)) <- matchExpectedAppTy exp_ty1
; let cmd_env = CmdEnv { cmd_arr = arr_ty }
- ; (pat', cmd') <- tcPat ProcExpr pat (mkCheckExpType arg_ty) $
+ ; (pat', cmd') <- tcCheckPat ProcExpr pat arg_ty $
tcCmdTop cmd_env cmd (unitTy, res_ty)
; let res_co = mkTcTransCo co
(mkTcAppCo co1 (mkTcNomReflCo res_ty))
@@ -160,7 +160,7 @@ tc_cmd env in_cmd@(HsCmdCase x scrut matches) (stk, res_ty)
; tcCmd env body (stk, res_ty') }
tc_cmd env (HsCmdIf x NoSyntaxExprRn pred b1 b2) res_ty -- Ordinary 'if'
- = do { pred' <- tcMonoExpr pred (mkCheckExpType boolTy)
+ = do { pred' <- tcLExpr pred (mkCheckExpType boolTy)
; b1' <- tcCmd env b1 res_ty
; b2' <- tcCmd env b2 res_ty
; return (HsCmdIf x NoSyntaxExprTc pred' b1' b2')
@@ -178,7 +178,7 @@ tc_cmd env (HsCmdIf x fun@(SyntaxExprRn {}) pred b1 b2) res_ty -- Rebindable syn
; (pred', fun')
<- tcSyntaxOp IfOrigin fun (map synKnownType [pred_ty, r_ty, r_ty])
(mkCheckExpType r_ty) $ \ _ ->
- tcMonoExpr pred (mkCheckExpType pred_ty)
+ tcLExpr pred (mkCheckExpType pred_ty)
; b1' <- tcCmd env b1 res_ty
; b2' <- tcCmd env b2 res_ty
@@ -205,9 +205,9 @@ tc_cmd env cmd@(HsCmdArrApp _ fun arg ho_app lr) (_, res_ty)
= addErrCtxt (cmdCtxt cmd) $
do { arg_ty <- newOpenFlexiTyVarTy
; let fun_ty = mkCmdArrTy env arg_ty res_ty
- ; fun' <- select_arrow_scope (tcMonoExpr fun (mkCheckExpType fun_ty))
+ ; fun' <- select_arrow_scope (tcLExpr fun (mkCheckExpType fun_ty))
- ; arg' <- tcMonoExpr arg (mkCheckExpType arg_ty)
+ ; arg' <- tcLExpr arg (mkCheckExpType arg_ty)
; return (HsCmdArrApp fun_ty fun' arg' ho_app lr) }
where
@@ -232,7 +232,7 @@ tc_cmd env cmd@(HsCmdApp x fun arg) (cmd_stk, res_ty)
= addErrCtxt (cmdCtxt cmd) $
do { arg_ty <- newOpenFlexiTyVarTy
; fun' <- tcCmd env fun (mkPairTy arg_ty cmd_stk, res_ty)
- ; arg' <- tcMonoExpr arg (mkCheckExpType arg_ty)
+ ; arg' <- tcLExpr arg (mkCheckExpType arg_ty)
; return (HsCmdApp x fun' arg') }
-------------------------------------------
@@ -309,7 +309,7 @@ tc_cmd env cmd@(HsCmdArrForm x expr f fixity cmd_args) (cmd_stk, res_ty)
; let e_ty = mkInvForAllTy alphaTyVar $
mkVisFunTys cmd_tys $
mkCmdArrTy env (mkPairTy alphaTy cmd_stk) res_ty
- ; expr' <- tcPolyExpr expr e_ty
+ ; expr' <- tcCheckExpr expr e_ty
; return (HsCmdArrForm x expr' f fixity cmd_args') }
where
@@ -366,7 +366,7 @@ tcArrDoStmt env _ (BodyStmt _ rhs _ _) res_ty thing_inside
tcArrDoStmt env ctxt (BindStmt _ pat rhs) res_ty thing_inside
= do { (rhs', pat_ty) <- tc_arr_rhs env rhs
- ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat (mkCheckExpType pat_ty) $
+ ; (pat', thing) <- tcCheckPat (StmtCtxt ctxt) pat pat_ty $
thing_inside res_ty
; return (mkTcBindStmt pat' rhs', thing) }
diff --git a/compiler/GHC/Tc/Gen/Bind.hs b/compiler/GHC/Tc/Gen/Bind.hs
index 0773e943c7..a8a8d027f0 100644
--- a/compiler/GHC/Tc/Gen/Bind.hs
+++ b/compiler/GHC/Tc/Gen/Bind.hs
@@ -23,7 +23,7 @@ where
import GhcPrelude
import {-# SOURCE #-} GHC.Tc.Gen.Match ( tcGRHSsPat, tcMatchesFun )
-import {-# SOURCE #-} GHC.Tc.Gen.Expr ( tcMonoExpr )
+import {-# SOURCE #-} GHC.Tc.Gen.Expr ( tcLExpr )
import {-# SOURCE #-} GHC.Tc.TyCl.PatSyn ( tcPatSynDecl, tcPatSynBuilderBind )
import GHC.Core (Tickish (..))
import GHC.Types.CostCentre (mkUserCC, CCFlavour(DeclCC))
@@ -354,7 +354,7 @@ tcLocalBinds (HsIPBinds x (IPBinds _ ip_binds)) thing_inside
= do { ty <- newOpenFlexiTyVarTy
; let p = mkStrLitTy $ hsIPNameFS ip
; ip_id <- newDict ipClass [ p, ty ]
- ; expr' <- tcMonoExpr expr (mkCheckExpType ty)
+ ; expr' <- tcLExpr expr (mkCheckExpType ty)
; let d = toDict ipClass p ty `fmap` expr'
; return (ip_id, (IPBind noExtField (Right ip_id) d)) }
tc_ip_bind _ (IPBind _ (Right {}) _) = panic "tc_ip_bind"
@@ -1263,9 +1263,7 @@ tcMonoBinds is_rec sig_fn no_gen
-- We want to infer a higher-rank type for f
setSrcSpan b_loc $
do { ((co_fn, matches'), rhs_ty)
- <- tcInferInst $ \ exp_ty ->
- -- tcInferInst: see GHC.Tc.Utils.Unify,
- -- Note [Deep instantiation of InferResult] in GHC.Tc.Utils.Unify
+ <- tcInfer $ \ exp_ty ->
tcExtendBinderStack [TcIdBndr_ExpType name exp_ty NotTopLevel] $
-- We extend the error context even for a non-recursive
-- function so that in type error messages we show the
@@ -1362,7 +1360,7 @@ tcLhs sig_fn no_gen (PatBind { pat_lhs = pat, pat_rhs = grhss })
-- See Note [Existentials in pattern bindings]
; ((pat', nosig_mbis), pat_ty)
<- addErrCtxt (patMonoBindsCtxt pat grhss) $
- tcInferNoInst $ \ exp_ty ->
+ tcInfer $ \ exp_ty ->
tcLetPat inst_sig_fun no_gen pat exp_ty $
mapM lookup_info nosig_names
diff --git a/compiler/GHC/Tc/Gen/Expr.hs b/compiler/GHC/Tc/Gen/Expr.hs
index 3048b78afa..70201773b9 100644
--- a/compiler/GHC/Tc/Gen/Expr.hs
+++ b/compiler/GHC/Tc/Gen/Expr.hs
@@ -7,25 +7,22 @@
{-# LANGUAGE CPP, TupleSections, ScopedTypeVariables #-}
{-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE TypeFamilies, DataKinds, TypeApplications #-}
+{-# LANGUAGE UndecidableInstances #-} -- Wrinkle in Note [Trees That Grow]
+ -- in module GHC.Hs.Extension
{-# OPTIONS_GHC -Wno-incomplete-uni-patterns #-}
-- | Typecheck an expression
module GHC.Tc.Gen.Expr
- ( tcPolyExpr
- , tcMonoExpr
- , tcMonoExprNC
+ ( tcCheckExpr
+ , tcLExpr, tcLExprNC, tcExpr
, tcInferSigma
- , tcInferSigmaNC
- , tcInferRho
- , tcInferRhoNC
- , tcSyntaxOp
- , tcSyntaxOpGen
+ , tcInferRho, tcInferRhoNC
+ , tcSyntaxOp, tcSyntaxOpGen
, SyntaxOpType(..)
, synKnownType
, tcCheckId
- , addExprErrCtxt
, addAmbiguousNameErr
, getFixedTyVars
)
@@ -48,7 +45,7 @@ import GHC.Tc.Utils.Instantiate
import GHC.Tc.Gen.Bind ( chooseInferredQuantifiers, tcLocalBinds )
import GHC.Tc.Gen.Sig ( tcUserTypeSig, tcInstSig )
import GHC.Tc.Solver ( simplifyInfer, InferMode(..) )
-import GHC.Tc.Instance.Family ( tcGetFamInstEnvs, tcLookupDataFamInst )
+import GHC.Tc.Instance.Family ( tcGetFamInstEnvs, tcLookupDataFamInst, tcLookupDataFamInst_maybe )
import GHC.Core.FamInstEnv ( FamInstEnvs )
import GHC.Rename.Env ( addUsedGRE )
import GHC.Rename.Utils ( addNameClashErrRn, unknownSubordinateErr )
@@ -78,7 +75,6 @@ import GHC.Core.Type
import GHC.Tc.Types.Evidence
import GHC.Types.Var.Set
import GHC.Builtin.Types
-import GHC.Builtin.Types.Prim( intPrimTy )
import GHC.Builtin.PrimOps( tagToEnumKey )
import GHC.Builtin.Names
import GHC.Driver.Session
@@ -106,69 +102,47 @@ import qualified Data.Set as Set
************************************************************************
-}
-tcPolyExpr, tcPolyExprNC
+tcCheckExpr, tcCheckExprNC
:: LHsExpr GhcRn -- Expression to type check
-> TcSigmaType -- Expected type (could be a polytype)
- -> TcM (LHsExpr GhcTcId) -- Generalised expr with expected type
+ -> TcM (LHsExpr GhcTc) -- Generalised expr with expected type
--- tcPolyExpr is a convenient place (frequent but not too frequent)
+-- tcCheckExpr is a convenient place (frequent but not too frequent)
-- place to add context information.
-- The NC version does not do so, usually because the caller wants
-- to do so himself.
-tcPolyExpr expr res_ty = tc_poly_expr expr (mkCheckExpType res_ty)
-tcPolyExprNC expr res_ty = tc_poly_expr_nc expr (mkCheckExpType res_ty)
+tcCheckExpr expr res_ty
+ = addExprCtxt expr $
+ tcCheckExprNC expr res_ty
--- these versions take an ExpType
-tc_poly_expr, tc_poly_expr_nc :: LHsExpr GhcRn -> ExpSigmaType
- -> TcM (LHsExpr GhcTcId)
-tc_poly_expr expr res_ty
- = addExprErrCtxt expr $
- do { traceTc "tcPolyExpr" (ppr res_ty); tc_poly_expr_nc expr res_ty }
-
-tc_poly_expr_nc (L loc expr) res_ty
+tcCheckExprNC (L loc expr) res_ty
= setSrcSpan loc $
- do { traceTc "tcPolyExprNC" (ppr res_ty)
- ; (wrap, expr')
- <- tcSkolemiseET GenSigCtxt res_ty $ \ res_ty ->
- tcExpr expr res_ty
+ do { traceTc "tcCheckExprNC" (ppr res_ty)
+ ; (wrap, expr') <- tcSkolemise GenSigCtxt res_ty $ \ _ res_ty ->
+ tcExpr expr (mkCheckExpType res_ty)
; return $ L loc (mkHsWrap wrap expr') }
---------------
-tcMonoExpr, tcMonoExprNC
- :: LHsExpr GhcRn -- Expression to type check
- -> ExpRhoType -- Expected type
- -- Definitely no foralls at the top
- -> TcM (LHsExpr GhcTcId)
-
-tcMonoExpr expr res_ty
- = addErrCtxt (exprCtxt expr) $
- tcMonoExprNC expr res_ty
-
-tcMonoExprNC (L loc expr) res_ty
- = setSrcSpan loc $
- do { expr' <- tcExpr expr res_ty
- ; return (L loc expr') }
+tcInferSigma :: LHsExpr GhcRn -> TcM (LHsExpr GhcTc, TcSigmaType)
+-- Used by tcRnExpr to implement GHCi :type
+-- It goes against the principle of eager instantiation,
+-- so we expect very very few calls to this function
+-- Most clients will want tcInferRho
+tcInferSigma le@(L loc expr)
+ = addExprCtxt le $ setSrcSpan loc $
+ do { (fun, args, ty) <- tcInferApp expr
+ ; return (L loc (applyHsArgs fun args), ty) }
---------------
-tcInferSigma, tcInferSigmaNC :: LHsExpr GhcRn -> TcM ( LHsExpr GhcTcId
- , TcSigmaType )
--- Infer a *sigma*-type.
-tcInferSigma expr = addErrCtxt (exprCtxt expr) (tcInferSigmaNC expr)
+tcInferRho, tcInferRhoNC :: LHsExpr GhcRn -> TcM (LHsExpr GhcTc, TcRhoType)
+-- Infer a *rho*-type. The return type is always instantiated.
+tcInferRho le = addExprCtxt le (tcInferRhoNC le)
-tcInferSigmaNC (L loc expr)
+tcInferRhoNC (L loc expr)
= setSrcSpan loc $
- do { (expr', sigma) <- tcInferNoInst (tcExpr expr)
- ; return (L loc expr', sigma) }
-
-tcInferRho, tcInferRhoNC :: LHsExpr GhcRn -> TcM (LHsExpr GhcTcId, TcRhoType)
--- Infer a *rho*-type. The return type is always (shallowly) instantiated.
-tcInferRho expr = addErrCtxt (exprCtxt expr) (tcInferRhoNC expr)
-
-tcInferRhoNC expr
- = do { (expr', sigma) <- tcInferSigmaNC expr
- ; (wrap, rho) <- topInstantiate (lexprCtOrigin expr) sigma
- ; return (mkLHsWrap wrap expr', rho) }
+ do { (expr', rho) <- tcInfer (tcExpr expr)
+ ; return (L loc expr', rho) }
{-
@@ -181,28 +155,37 @@ tcInferRhoNC expr
NB: The res_ty is always deeply skolemised.
-}
-tcExpr :: HsExpr GhcRn -> ExpRhoType -> TcM (HsExpr GhcTcId)
+tcLExpr, tcLExprNC
+ :: LHsExpr GhcRn -- Expression to type check
+ -> ExpRhoType -- Expected type
+ -- Definitely no foralls at the top
+ -> TcM (LHsExpr GhcTc)
+
+tcLExpr expr res_ty
+ = addExprCtxt expr (tcLExprNC expr res_ty)
+
+tcLExprNC (L loc expr) res_ty
+ = setSrcSpan loc $
+ do { expr' <- tcExpr expr res_ty
+ ; return (L loc expr') }
+
+tcExpr :: HsExpr GhcRn -> ExpRhoType -> TcM (HsExpr GhcTc)
tcExpr (HsVar _ (L _ name)) res_ty = tcCheckId name res_ty
tcExpr e@(HsUnboundVar _ uv) res_ty = tcUnboundId e uv res_ty
-tcExpr e@(HsApp {}) res_ty = tcApp1 e res_ty
-tcExpr e@(HsAppType {}) res_ty = tcApp1 e res_ty
+tcExpr e@(HsApp {}) res_ty = tcApp e res_ty
+tcExpr e@(HsAppType {}) res_ty = tcApp e res_ty
tcExpr e@(HsLit x lit) res_ty
= do { let lit_ty = hsLitType lit
; tcWrapResult e (HsLit x (convertLit lit)) lit_ty res_ty }
-tcExpr (HsPar x expr) res_ty = do { expr' <- tcMonoExprNC expr res_ty
+tcExpr (HsPar x expr) res_ty = do { expr' <- tcLExprNC expr res_ty
; return (HsPar x expr') }
tcExpr (HsPragE x prag expr) res_ty
- = do { expr' <- tcMonoExpr expr res_ty
- ; return (HsPragE x (tc_prag prag) expr') }
- where
- tc_prag :: HsPragE GhcRn -> HsPragE GhcTc
- tc_prag (HsPragSCC x1 src ann) = HsPragSCC x1 src ann
- tc_prag (HsPragCore x1 src lbl) = HsPragCore x1 src lbl
- tc_prag (HsPragTick x1 src info srcInfo) = HsPragTick x1 src info srcInfo
+ = do { expr' <- tcLExpr expr res_ty
+ ; return (HsPragE x (tcExprPrag prag) expr') }
tcExpr (HsOverLit x lit) res_ty
= do { lit' <- newOverloadedLit lit res_ty
@@ -212,7 +195,7 @@ tcExpr (NegApp x expr neg_expr) res_ty
= do { (expr', neg_expr')
<- tcSyntaxOp NegateOrigin neg_expr [SynAny] res_ty $
\[arg_ty] ->
- tcMonoExpr expr (mkCheckExpType arg_ty)
+ tcLExpr expr (mkCheckExpType arg_ty)
; return (NegApp x expr' neg_expr') }
tcExpr e@(HsIPVar _ x) res_ty
@@ -280,13 +263,9 @@ tcExpr e@(HsLamCase x matches) res_ty
, text "requires"]
match_ctxt = MC { mc_what = CaseAlt, mc_body = tcBody }
-tcExpr e@(ExprWithTySig _ expr sig_ty) res_ty
- = do { let loc = getLoc (hsSigWcType sig_ty)
- ; sig_info <- checkNoErrs $ -- Avoid error cascade
- tcUserTypeSig loc sig_ty Nothing
- ; (expr', poly_ty) <- tcExprSig expr sig_info
- ; let expr'' = ExprWithTySig noExtField expr' sig_ty
- ; tcWrapResult e expr'' poly_ty res_ty }
+tcExpr e@(ExprWithTySig _ expr hs_ty) res_ty
+ = do { (expr', poly_ty) <- tcExprWithSig expr hs_ty
+ ; tcWrapResult e expr' poly_ty res_ty }
{-
Note [Type-checking overloaded labels]
@@ -351,7 +330,8 @@ tcExpr expr@(OpApp fix arg1 op arg2) res_ty
| (L loc (HsVar _ (L lv op_name))) <- op
, op_name `hasKey` dollarIdKey -- Note [Typing rule for ($)]
= do { traceTc "Application rule" (ppr op)
- ; (arg1', arg1_ty) <- tcInferSigma arg1
+ ; (arg1', arg1_ty) <- addErrCtxt (funAppCtxt op arg1 1) $
+ tcInferRhoNC arg1
; let doc = text "The first argument of ($) takes"
orig1 = lexprCtOrigin arg1
@@ -362,7 +342,7 @@ tcExpr expr@(OpApp fix arg1 op arg2) res_ty
-- So: arg1_ty = arg2_ty -> op_res_ty
-- where arg2_sigma maybe polymorphic; that's the point
- ; arg2' <- tcArg op arg2 arg2_sigma 2
+ ; arg2' <- tcArg nl_op arg2 arg2_sigma 2
-- Make sure that the argument type has kind '*'
-- ($) :: forall (r:RuntimeRep) (a:*) (b:TYPE r). (a->b) -> a -> b
@@ -392,7 +372,7 @@ tcExpr expr@(OpApp fix arg1 op arg2) res_ty
; tcWrapResult expr expr' op_res_ty res_ty }
- | (L loc (HsRecFld _ (Ambiguous _ lbl))) <- op
+ | L loc (HsRecFld _ (Ambiguous _ lbl)) <- op
, Just sig_ty <- obviousSig (unLoc arg1)
-- See Note [Disambiguating record fields]
= do { sig_tc_ty <- tcHsSigWcType ExprSigCtxt sig_ty
@@ -403,21 +383,33 @@ tcExpr expr@(OpApp fix arg1 op arg2) res_ty
| otherwise
= do { traceTc "Non Application rule" (ppr op)
- ; (wrap, op', [HsValArg arg1', HsValArg arg2'])
- <- tcApp (Just $ mk_op_msg op)
- op [HsValArg arg1, HsValArg arg2] res_ty
- ; return (mkHsWrap wrap $ OpApp fix arg1' op' arg2') }
+ ; (op', op_ty) <- tcInferRhoNC op
+
+ ; (wrap_fun, [arg1_ty, arg2_ty], op_res_ty)
+ <- matchActualFunTys (mk_op_msg op) fn_orig (Just (unLoc op)) 2 op_ty
+ -- You might think we should use tcInferApp here, but there is
+ -- too much impedance-matching, because tcApp may return wrappers as
+ -- well as type-checked arguments.
+
+ ; arg1' <- tcArg nl_op arg1 arg1_ty 1
+ ; arg2' <- tcArg nl_op arg2 arg2_ty 2
+
+ ; let expr' = OpApp fix arg1' (mkLHsWrap wrap_fun op') arg2'
+ ; tcWrapResult expr expr' op_res_ty res_ty }
+ where
+ fn_orig = exprCtOrigin nl_op
+ nl_op = unLoc op
-- Right sections, equivalent to \ x -> x `op` expr, or
-- \ x -> op x expr
tcExpr expr@(SectionR x op arg2) res_ty
- = do { (op', op_ty) <- tcInferFun op
+ = do { (op', op_ty) <- tcInferRhoNC op
; (wrap_fun, [arg1_ty, arg2_ty], op_res_ty)
<- matchActualFunTys (mk_op_msg op) fn_orig (Just (unLoc op)) 2 op_ty
; wrap_res <- tcSubTypeHR SectionOrigin (Just expr)
(mkVisFunTy arg1_ty op_res_ty) res_ty
- ; arg2' <- tcArg op arg2 arg2_ty 2
+ ; arg2' <- tcArg (unLoc op) arg2 arg2_ty 2
; return ( mkHsWrap wrap_res $
SectionR x (mkLHsWrap wrap_fun op') arg2' ) }
where
@@ -427,7 +419,7 @@ tcExpr expr@(SectionR x op arg2) res_ty
-- See #13285
tcExpr expr@(SectionL x arg1 op) res_ty
- = do { (op', op_ty) <- tcInferFun op
+ = do { (op', op_ty) <- tcInferRhoNC op
; dflags <- getDynFlags -- Note [Left sections]
; let n_reqd_args | xopt LangExt.PostfixOperators dflags = 1
| otherwise = 2
@@ -437,7 +429,7 @@ tcExpr expr@(SectionL x arg1 op) res_ty
n_reqd_args op_ty
; wrap_res <- tcSubTypeHR SectionOrigin (Just expr)
(mkVisFunTys arg_tys op_res_ty) res_ty
- ; arg1' <- tcArg op arg1 arg1_ty 1
+ ; arg1' <- tcArg (unLoc op) arg1 arg1_ty 1
; return ( mkHsWrap wrap_res $
SectionL x arg1' (mkLHsWrap wrap_fn op') ) }
where
@@ -489,7 +481,7 @@ tcExpr (ExplicitSum _ alt arity expr) res_ty
; (coi, arg_tys) <- matchExpectedTyConApp sum_tc res_ty
; -- Drop levity vars, we don't care about them here
let arg_tys' = drop arity arg_tys
- ; expr' <- tcPolyExpr expr (arg_tys' `getNth` (alt - 1))
+ ; expr' <- tcCheckExpr expr (arg_tys' `getNth` (alt - 1))
; return $ mkHsWrapCo coi (ExplicitSum arg_tys' alt arity expr' ) }
-- This will see the empty list only when -XOverloadedLists.
@@ -511,7 +503,7 @@ tcExpr (ExplicitList _ witness exprs) res_ty
; return (exprs', elt_ty) }
; return $ ExplicitList elt_ty (Just fln') exprs' }
- where tc_elt elt_ty expr = tcPolyExpr expr elt_ty
+ where tc_elt elt_ty expr = tcCheckExpr expr elt_ty
{-
************************************************************************
@@ -523,7 +515,7 @@ tcExpr (ExplicitList _ witness exprs) res_ty
tcExpr (HsLet x (L l binds) expr) res_ty
= do { (binds', expr') <- tcLocalBinds binds $
- tcMonoExpr expr res_ty
+ tcLExpr expr res_ty
; return (HsLet x (L l binds') expr') }
tcExpr (HsCase x scrut matches) res_ty
@@ -546,22 +538,22 @@ tcExpr (HsCase x scrut matches) res_ty
mc_body = tcBody }
tcExpr (HsIf x NoSyntaxExprRn pred b1 b2) res_ty -- Ordinary 'if'
- = do { pred' <- tcMonoExpr pred (mkCheckExpType boolTy)
+ = do { pred' <- tcLExpr pred (mkCheckExpType boolTy)
; res_ty <- tauifyExpType res_ty
-- Just like Note [Case branches must never infer a non-tau type]
-- in GHC.Tc.Gen.Match (See #10619)
- ; b1' <- tcMonoExpr b1 res_ty
- ; b2' <- tcMonoExpr b2 res_ty
+ ; b1' <- tcLExpr b1 res_ty
+ ; b2' <- tcLExpr b2 res_ty
; return (HsIf x NoSyntaxExprTc pred' b1' b2') }
tcExpr (HsIf x fun@(SyntaxExprRn {}) pred b1 b2) res_ty
= do { ((pred', b1', b2'), fun')
<- tcSyntaxOp IfOrigin fun [SynAny, SynAny, SynAny] res_ty $
\ [pred_ty, b1_ty, b2_ty] ->
- do { pred' <- tcPolyExpr pred pred_ty
- ; b1' <- tcPolyExpr b1 b1_ty
- ; b2' <- tcPolyExpr b2 b2_ty
+ do { pred' <- tcCheckExpr pred pred_ty
+ ; b1' <- tcCheckExpr b1 b1_ty
+ ; b2' <- tcCheckExpr b2 b2_ty
; return (pred', b1', b2') }
; return (HsIf x fun' pred' b1' b2') }
@@ -600,7 +592,7 @@ tcExpr (HsStatic fvs expr) res_ty
addErrCtxt (hang (text "In the body of a static form:")
2 (ppr expr)
) $
- tcPolyExprNC expr expr_ty
+ tcCheckExprNC expr expr_ty
-- Check that the free variables of the static form are closed.
-- It's OK to use nonDetEltsUniqSet here as the only side effects of
@@ -1004,10 +996,39 @@ tcExpr e@(HsRnBracketOut _ brack ps) res_ty
************************************************************************
-}
-tcExpr other _ = pprPanic "tcMonoExpr" (ppr other)
+tcExpr other _ = pprPanic "tcLExpr" (ppr other)
-- Include ArrForm, ArrApp, which shouldn't appear at all
-- Also HsTcBracketOut, HsQuasiQuoteE
+
+{- *********************************************************************
+* *
+ Pragmas on expressions
+* *
+********************************************************************* -}
+
+tcExprPrag :: HsPragE GhcRn -> HsPragE GhcTc
+tcExprPrag (HsPragSCC x1 src ann) = HsPragSCC x1 src ann
+tcExprPrag (HsPragCore x1 src lbl) = HsPragCore x1 src lbl
+tcExprPrag (HsPragTick x1 src info srcInfo) = HsPragTick x1 src info srcInfo
+
+
+{- *********************************************************************
+* *
+ Expression with type signature e::ty
+* *
+********************************************************************* -}
+
+tcExprWithSig :: LHsExpr GhcRn -> LHsSigWcType (NoGhcTc GhcRn)
+ -> TcM (HsExpr GhcTc, TcSigmaType)
+tcExprWithSig expr hs_ty
+ = do { sig_info <- checkNoErrs $ -- Avoid error cascade
+ tcUserTypeSig loc hs_ty Nothing
+ ; (expr', poly_ty) <- tcExprSig expr sig_info
+ ; return (ExprWithTySig noExtField expr' hs_ty, poly_ty) }
+ where
+ loc = getLoc (hsSigWcType hs_ty)
+
{-
************************************************************************
* *
@@ -1017,11 +1038,11 @@ tcExpr other _ = pprPanic "tcMonoExpr" (ppr other)
-}
tcArithSeq :: Maybe (SyntaxExpr GhcRn) -> ArithSeqInfo GhcRn -> ExpRhoType
- -> TcM (HsExpr GhcTcId)
+ -> TcM (HsExpr GhcTc)
tcArithSeq witness seq@(From expr) res_ty
= do { (wrap, elt_ty, wit') <- arithSeqEltType witness res_ty
- ; expr' <- tcPolyExpr expr elt_ty
+ ; expr' <- tcCheckExpr expr elt_ty
; enum_from <- newMethodFromName (ArithSeqOrigin seq)
enumFromName [elt_ty]
; return $ mkHsWrap wrap $
@@ -1029,8 +1050,8 @@ tcArithSeq witness seq@(From expr) res_ty
tcArithSeq witness seq@(FromThen expr1 expr2) res_ty
= do { (wrap, elt_ty, wit') <- arithSeqEltType witness res_ty
- ; expr1' <- tcPolyExpr expr1 elt_ty
- ; expr2' <- tcPolyExpr expr2 elt_ty
+ ; expr1' <- tcCheckExpr expr1 elt_ty
+ ; expr2' <- tcCheckExpr expr2 elt_ty
; enum_from_then <- newMethodFromName (ArithSeqOrigin seq)
enumFromThenName [elt_ty]
; return $ mkHsWrap wrap $
@@ -1038,8 +1059,8 @@ tcArithSeq witness seq@(FromThen expr1 expr2) res_ty
tcArithSeq witness seq@(FromTo expr1 expr2) res_ty
= do { (wrap, elt_ty, wit') <- arithSeqEltType witness res_ty
- ; expr1' <- tcPolyExpr expr1 elt_ty
- ; expr2' <- tcPolyExpr expr2 elt_ty
+ ; expr1' <- tcCheckExpr expr1 elt_ty
+ ; expr2' <- tcCheckExpr expr2 elt_ty
; enum_from_to <- newMethodFromName (ArithSeqOrigin seq)
enumFromToName [elt_ty]
; return $ mkHsWrap wrap $
@@ -1047,9 +1068,9 @@ tcArithSeq witness seq@(FromTo expr1 expr2) res_ty
tcArithSeq witness seq@(FromThenTo expr1 expr2 expr3) res_ty
= do { (wrap, elt_ty, wit') <- arithSeqEltType witness res_ty
- ; expr1' <- tcPolyExpr expr1 elt_ty
- ; expr2' <- tcPolyExpr expr2 elt_ty
- ; expr3' <- tcPolyExpr expr3 elt_ty
+ ; expr1' <- tcCheckExpr expr1 elt_ty
+ ; expr2' <- tcCheckExpr expr2 elt_ty
+ ; expr3' <- tcCheckExpr expr3 elt_ty
; eft <- newMethodFromName (ArithSeqOrigin seq)
enumFromThenToName [elt_ty]
; return $ mkHsWrap wrap $
@@ -1076,179 +1097,245 @@ arithSeqEltType (Just fl) res_ty
************************************************************************
-}
--- HsArg is defined in GHC.Hs.Types
-
-wrapHsArgs :: (NoGhcTc (GhcPass id) ~ GhcRn)
- => LHsExpr (GhcPass id)
- -> [HsArg (LHsExpr (GhcPass id)) (LHsWcType GhcRn)]
- -> LHsExpr (GhcPass id)
-wrapHsArgs f [] = f
-wrapHsArgs f (HsValArg a : args) = wrapHsArgs (mkHsApp f a) args
-wrapHsArgs f (HsTypeArg _ t : args) = wrapHsArgs (mkHsAppType f t) args
-wrapHsArgs f (HsArgPar sp : args) = wrapHsArgs (L sp $ HsPar noExtField f) args
-
-isHsValArg :: HsArg tm ty -> Bool
-isHsValArg (HsValArg {}) = True
-isHsValArg (HsTypeArg {}) = False
-isHsValArg (HsArgPar {}) = False
-
-isArgPar :: HsArg tm ty -> Bool
-isArgPar (HsArgPar {}) = True
-isArgPar (HsValArg {}) = False
-isArgPar (HsTypeArg {}) = False
-
-isArgPar_maybe :: HsArg a b -> Maybe (HsArg c d)
-isArgPar_maybe (HsArgPar sp) = Just $ HsArgPar sp
-isArgPar_maybe _ = Nothing
-
-type LHsExprArgIn = HsArg (LHsExpr GhcRn) (LHsWcType GhcRn)
-type LHsExprArgOut = HsArg (LHsExpr GhcTcId) (LHsWcType GhcRn)
-
-tcApp1 :: HsExpr GhcRn -- either HsApp or HsAppType
- -> ExpRhoType -> TcM (HsExpr GhcTcId)
-tcApp1 e res_ty
- = do { (wrap, fun, args) <- tcApp Nothing (noLoc e) [] res_ty
- ; return (mkHsWrap wrap $ unLoc $ wrapHsArgs fun args) }
-
-tcApp :: Maybe SDoc -- like "The function `f' is applied to"
- -- or leave out to get exactly that message
- -> LHsExpr GhcRn -> [LHsExprArgIn] -- Function and args
- -> ExpRhoType -> TcM (HsWrapper, LHsExpr GhcTcId, [LHsExprArgOut])
- -- (wrap, fun, args). For an ordinary function application,
- -- these should be assembled as (wrap (fun args)).
- -- But OpApp is slightly different, so that's why the caller
- -- must assemble
-
-tcApp m_herald (L sp (HsPar _ fun)) args res_ty
- = tcApp m_herald fun (HsArgPar sp : args) res_ty
-
-tcApp m_herald (L _ (HsApp _ fun arg1)) args res_ty
- = tcApp m_herald fun (HsValArg arg1 : args) res_ty
-
-tcApp m_herald (L _ (HsAppType _ fun ty1)) args res_ty
- = tcApp m_herald fun (HsTypeArg noSrcSpan ty1 : args) res_ty
-
-tcApp m_herald fun@(L loc (HsRecFld _ fld_lbl)) args res_ty
- | Ambiguous _ lbl <- fld_lbl -- Still ambiguous
- , HsValArg (L _ arg) : _ <- filterOut isArgPar args -- A value arg is first
- , Just sig_ty <- obviousSig arg -- A type sig on the arg disambiguates
+{- Note [Typechecking applications]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+We typecheck application chains (f e1 @ty e2) specially:
+
+* So we can report errors like "in the third arument of a call of f"
+
+* So we can do Visible Type Application (VTA), for which we must not
+ eagerly instantiate the function part of the application.
+
+* So that we can do Quick Look impredicativity.
+
+The idea is:
+
+* Use collectHsArgs, which peels off
+ HsApp, HsTypeApp, HsPrag, HsPar
+ returning the function in the corner and the arguments
+
+* Use tcInferAppHead to infer the type of the fuction,
+ as an (uninstantiated) TcSigmaType
+ There are special cases for
+ HsVar, HsREcFld, and ExprWithTySig
+ Otherwise, delegate back to tcExpr, which
+ infers an (instantiated) TcRhoType
+
+Some cases that /won't/ work:
+
+1. Consider this (which uses visible type application):
+
+ (let { f :: forall a. a -> a; f x = x } in f) @Int
+
+ Since 'let' is not among the special cases for tcInferAppHead,
+ we'll delegate back to tcExpr, which will instantiate f's type
+ and the type application to @Int will fail. Too bad!
+
+-}
+
+-- HsExprArg is a very local type, used only within this module.
+-- It's really a zipper for an application chain
+-- It's a GHC-specific type, so using TTG only where necessary
+data HsExprArg id
+ = HsEValArg SrcSpan -- Of the function
+ (LHsExpr (GhcPass id))
+ | HsETypeArg SrcSpan -- Of the function
+ (LHsWcType (NoGhcTc (GhcPass id)))
+ !(XExprTypeArg id)
+ | HsEPrag SrcSpan
+ (HsPragE (GhcPass id))
+ | HsEPar SrcSpan -- Of the nested expr
+ | HsEWrap !(XArgWrap id) -- Wrapper, after typechecking only
+
+-- The outer location is the location of the application itself
+type LHsExprArgIn = HsExprArg 'Renamed
+type LHsExprArgOut = HsExprArg 'Typechecked
+
+instance OutputableBndrId id => Outputable (HsExprArg id) where
+ ppr (HsEValArg _ tm) = ppr tm
+ ppr (HsEPrag _ p) = text "HsPrag" <+> ppr p
+ ppr (HsETypeArg _ hs_ty _) = char '@' <> ppr hs_ty
+ ppr (HsEPar _) = text "HsEPar"
+ ppr (HsEWrap w) = case ghcPass @id of
+ GhcTc -> text "HsEWrap" <+> ppr w
+ _ -> empty
+
+type family XExprTypeArg id where
+ XExprTypeArg 'Parsed = NoExtField
+ XExprTypeArg 'Renamed = NoExtField
+ XExprTypeArg 'Typechecked = Type
+
+type family XArgWrap id where
+ XArgWrap 'Parsed = NoExtCon
+ XArgWrap 'Renamed = NoExtCon
+ XArgWrap 'Typechecked = HsWrapper
+
+addArgWrap :: HsWrapper -> [LHsExprArgOut] -> [LHsExprArgOut]
+addArgWrap wrap args
+ | isIdHsWrapper wrap = args
+ | otherwise = HsEWrap wrap : args
+
+collectHsArgs :: HsExpr GhcRn -> (HsExpr GhcRn, [LHsExprArgIn])
+collectHsArgs e = go e []
+ where
+ go (HsPar _ (L l fun)) args = go fun (HsEPar l : args)
+ go (HsPragE _ p (L l fun)) args = go fun (HsEPrag l p : args)
+ go (HsApp _ (L l fun) arg) args = go fun (HsEValArg l arg : args)
+ go (HsAppType _ (L l fun) hs_ty) args = go fun (HsETypeArg l hs_ty noExtField : args)
+ go e args = (e,args)
+
+applyHsArgs :: HsExpr GhcTc -> [LHsExprArgOut]-> HsExpr GhcTc
+applyHsArgs fun args
+ = go fun args
+ where
+ go fun [] = fun
+ go fun (HsEWrap wrap : args) = go (mkHsWrap wrap fun) args
+ go fun (HsEValArg l arg : args) = go (HsApp noExtField (L l fun) arg) args
+ go fun (HsETypeArg l hs_ty ty : args) = go (HsAppType ty (L l fun) hs_ty) args
+ go fun (HsEPar l : args) = go (HsPar noExtField (L l fun)) args
+ go fun (HsEPrag l p : args) = go (HsPragE noExtField p (L l fun)) args
+
+isHsValArg :: HsExprArg id -> Bool
+isHsValArg (HsEValArg {}) = True
+isHsValArg _ = False
+
+isArgPar :: HsExprArg id -> Bool
+isArgPar (HsEPar {}) = True
+isArgPar _ = False
+
+getFunLoc :: [HsExprArg 'Renamed] -> Maybe SrcSpan
+getFunLoc [] = Nothing
+getFunLoc (a:_) = Just $ case a of
+ HsEValArg l _ -> l
+ HsETypeArg l _ _ -> l
+ HsEPrag l _ -> l
+ HsEPar l -> l
+
+---------------------------
+tcApp :: HsExpr GhcRn -- either HsApp or HsAppType
+ -> ExpRhoType -> TcM (HsExpr GhcTc)
+-- See Note [Typechecking applications]
+tcApp expr res_ty
+ = do { (fun, args, app_res_ty) <- tcInferApp expr
+ ; if isTagToEnum fun
+ then tcTagToEnum expr fun args app_res_ty res_ty
+ else -- The wildly common case
+ do { let expr' = applyHsArgs fun args
+ ; addFunResCtxt True fun app_res_ty res_ty $
+ tcWrapResult expr expr' app_res_ty res_ty } }
+
+---------------------------
+tcInferApp :: HsExpr GhcRn
+ -> TcM ( HsExpr GhcTc -- Function
+ , [LHsExprArgOut] -- Arguments
+ , TcSigmaType) -- Inferred type: a sigma-type!
+-- Also used by Module.tcRnExpr to implement GHCi :type
+tcInferApp expr
+ | -- Gruesome special case for ambiguous record selectors
+ HsRecFld _ fld_lbl <- fun
+ , Ambiguous _ lbl <- fld_lbl -- Still ambiguous
+ , HsEValArg _ (L _ arg) : _ <- filterOut isArgPar args -- A value arg is first
+ , Just sig_ty <- obviousSig arg -- A type sig on the arg disambiguates
= do { sig_tc_ty <- tcHsSigWcType ExprSigCtxt sig_ty
; sel_name <- disambiguateSelector lbl sig_tc_ty
; (tc_fun, fun_ty) <- tcInferRecSelId (Unambiguous sel_name lbl)
- ; tcFunApp m_herald fun (L loc tc_fun) fun_ty args res_ty }
+ ; tcInferApp_finish fun tc_fun fun_ty args }
-tcApp _m_herald (L loc (HsVar _ (L _ fun_id))) args res_ty
- -- Special typing rule for tagToEnum#
- | fun_id `hasKey` tagToEnumKey
- , n_val_args == 1
- = tcTagToEnum loc fun_id args res_ty
+ | otherwise -- The wildly common case
+ = do { (tc_fun, fun_ty) <- set_fun_loc (tcInferAppHead fun)
+ ; tcInferApp_finish fun tc_fun fun_ty args }
where
- n_val_args = count isHsValArg args
-
-tcApp m_herald fun args res_ty
- = do { (tc_fun, fun_ty) <- tcInferFun fun
- ; tcFunApp m_herald fun tc_fun fun_ty args res_ty }
+ (fun, args) = collectHsArgs expr
+ set_fun_loc thing_inside
+ = case getFunLoc args of
+ Nothing -> thing_inside -- Don't set the location twice
+ Just loc -> setSrcSpan loc thing_inside
---------------------
-tcFunApp :: Maybe SDoc -- like "The function `f' is applied to"
- -- or leave out to get exactly that message
- -> LHsExpr GhcRn -- Renamed function
- -> LHsExpr GhcTcId -> TcSigmaType -- Function and its type
- -> [LHsExprArgIn] -- Arguments
- -> ExpRhoType -- Overall result type
- -> TcM (HsWrapper, LHsExpr GhcTcId, [LHsExprArgOut])
- -- (wrapper-for-result, fun, args)
- -- For an ordinary function application,
- -- these should be assembled as wrap_res[ fun args ]
- -- But OpApp is slightly different, so that's why the caller
- -- must assemble
-
--- tcFunApp deals with the general case;
--- the special cases are handled by tcApp
-tcFunApp m_herald rn_fun tc_fun fun_sigma rn_args res_ty
- = do { let orig = lexprCtOrigin rn_fun
-
- ; traceTc "tcFunApp" (ppr rn_fun <+> dcolon <+> ppr fun_sigma $$ ppr rn_args $$ ppr res_ty)
- ; (wrap_fun, tc_args, actual_res_ty)
- <- tcArgs rn_fun fun_sigma orig rn_args
- (m_herald `orElse` mk_app_msg rn_fun rn_args)
-
- -- this is just like tcWrapResult, but the types don't line
- -- up to call that function
- ; wrap_res <- addFunResCtxt True (unLoc rn_fun) actual_res_ty res_ty $
- tcSubTypeDS_NC_O orig GenSigCtxt
- (Just $ unLoc $ wrapHsArgs rn_fun rn_args)
- actual_res_ty res_ty
-
- ; return (wrap_res, mkLHsWrap wrap_fun tc_fun, tc_args) }
-
-mk_app_msg :: LHsExpr GhcRn -> [LHsExprArgIn] -> SDoc
-mk_app_msg fun args = sep [ text "The" <+> text what <+> quotes (ppr expr)
- , text "is applied to"]
- where
- what | null type_app_args = "function"
- | otherwise = "expression"
- -- Include visible type arguments (but not other arguments) in the herald.
- -- See Note [Herald for matchExpectedFunTys] in GHC.Tc.Utils.Unify.
- expr = mkHsAppTypes fun type_app_args
- type_app_args = [hs_ty | HsTypeArg _ hs_ty <- args]
+tcInferApp_finish
+ :: HsExpr GhcRn -- Renamed function
+ -> HsExpr GhcTc -> TcSigmaType -- Function and its type
+ -> [LHsExprArgIn] -- Arguments
+ -> TcM (HsExpr GhcTc, [LHsExprArgOut], TcSigmaType)
-mk_op_msg :: LHsExpr GhcRn -> SDoc
-mk_op_msg op = text "The operator" <+> quotes (ppr op) <+> text "takes"
+tcInferApp_finish rn_fun tc_fun fun_sigma rn_args
+ = do { traceTc "tcInferApp_finish" $
+ vcat [ ppr rn_fun <+> dcolon <+> ppr fun_sigma, ppr rn_args ]
-----------------
-tcInferFun :: LHsExpr GhcRn -> TcM (LHsExpr GhcTcId, TcSigmaType)
--- Infer type of a function
-tcInferFun (L loc (HsVar _ (L _ name)))
- = do { (fun, ty) <- setSrcSpan loc (tcInferId name)
- -- Don't wrap a context around a plain Id
- ; return (L loc fun, ty) }
+ ; (tc_args, actual_res_ty) <- tcArgs rn_fun fun_sigma rn_args
-tcInferFun (L loc (HsRecFld _ f))
- = do { (fun, ty) <- setSrcSpan loc (tcInferRecSelId f)
- -- Don't wrap a context around a plain Id
- ; return (L loc fun, ty) }
+ ; return (tc_fun, tc_args, actual_res_ty) }
-tcInferFun fun
- = tcInferSigma fun
- -- NB: tcInferSigma; see GHC.Tc.Utils.Unify
- -- Note [Deep instantiation of InferResult] in GHC.Tc.Utils.Unify
+mk_op_msg :: LHsExpr GhcRn -> SDoc
+mk_op_msg op = text "The operator" <+> quotes (ppr op) <+> text "takes"
+----------------
+tcInferAppHead :: HsExpr GhcRn -> TcM (HsExpr GhcTc, TcSigmaType)
+-- Infer type of the head of an application, returning a /SigmaType/
+-- i.e. the 'f' in (f e1 ... en)
+-- We get back a SigmaType because we have special cases for
+-- * A bare identifier (just look it up)
+-- This case also covers a record selectro HsRecFld
+-- * An expression with a type signature (e :: ty)
+--
+-- Note that [] and (,,) are both HsVar:
+-- see Note [Empty lists] and [ExplicitTuple] in GHC.Hs.Expr
+--
+-- NB: 'e' cannot be HsApp, HsTyApp, HsPrag, HsPar, because those
+-- cases are dealt with by collectHsArgs.
+--
+-- See Note [Typechecking applications]
+tcInferAppHead e
+ = case e of
+ HsVar _ (L _ nm) -> tcInferId nm
+ HsRecFld _ f -> tcInferRecSelId f
+ ExprWithTySig _ e hs_ty -> add_ctxt $ tcExprWithSig e hs_ty
+ _ -> add_ctxt $ tcInfer (tcExpr e)
+ where
+ add_ctxt thing = addErrCtxt (exprCtxt e) thing
----------------
-- | Type-check the arguments to a function, possibly including visible type
-- applications
-tcArgs :: LHsExpr GhcRn -- ^ The function itself (for err msgs only)
+tcArgs :: HsExpr GhcRn -- ^ The function itself (for err msgs only)
-> TcSigmaType -- ^ the (uninstantiated) type of the function
- -> CtOrigin -- ^ the origin for the function's type
-> [LHsExprArgIn] -- ^ the args
- -> SDoc -- ^ the herald for matchActualFunTys
- -> TcM (HsWrapper, [LHsExprArgOut], TcSigmaType)
+ -> TcM ([LHsExprArgOut], TcSigmaType)
-- ^ (a wrapper for the function, the tc'd args, result type)
-tcArgs fun orig_fun_ty fun_orig orig_args herald
- = go [] 1 orig_fun_ty orig_args
+tcArgs fun orig_fun_ty orig_args
+ = go 1 [] orig_fun_ty orig_args
where
- -- Don't count visible type arguments when determining how many arguments
- -- an expression is given in an arity mismatch error, since visible type
- -- arguments reported as a part of the expression herald itself.
+ fun_orig = exprCtOrigin fun
+ herald = sep [ text "The function" <+> quotes (ppr fun)
+ , text "is applied to"]
+
+ -- Count value args only when complaining about a function
+ -- applied to too many value args
-- See Note [Herald for matchExpectedFunTys] in GHC.Tc.Utils.Unify.
- orig_expr_args_arity = count isHsValArg orig_args
+ n_val_args = count isHsValArg orig_args
fun_is_out_of_scope -- See Note [VTA for out-of-scope functions]
= case fun of
- L _ (HsUnboundVar {}) -> True
- _ -> False
+ HsUnboundVar {} -> True
+ _ -> False
- go _ _ fun_ty [] = return (idHsWrapper, [], fun_ty)
+ go :: Int -- Which argment number this is (incl type args)
+ -> [TcSigmaType] -- Value args to which applied so far
+ -> TcSigmaType
+ -> [LHsExprArgIn] -> TcM ([LHsExprArgOut], TcSigmaType)
+ go _ _ fun_ty [] = traceTc "tcArgs:ret" (ppr fun_ty) >> return ([], fun_ty)
- go acc_args n fun_ty (HsArgPar sp : args)
- = do { (inner_wrap, args', res_ty) <- go acc_args n fun_ty args
- ; return (inner_wrap, HsArgPar sp : args', res_ty)
- }
+ go n so_far fun_ty (HsEPar sp : args)
+ = do { (args', res_ty) <- go n so_far fun_ty args
+ ; return (HsEPar sp : args', res_ty) }
- go acc_args n fun_ty (HsTypeArg l hs_ty_arg : args)
+ go n so_far fun_ty (HsEPrag sp prag : args)
+ = do { (args', res_ty) <- go n so_far fun_ty args
+ ; return (HsEPrag sp (tcExprPrag prag) : args', res_ty) }
+
+ go n so_far fun_ty (HsETypeArg loc hs_ty_arg _ : args)
| fun_is_out_of_scope -- See Note [VTA for out-of-scope functions]
- = go acc_args (n+1) fun_ty args
+ = go (n+1) so_far fun_ty args
| otherwise
= do { (wrap1, upsilon_ty) <- topInstantiateInferred fun_orig fun_ty
@@ -1266,7 +1353,6 @@ tcArgs fun orig_fun_ty fun_orig orig_args herald
; inner_ty <- zonkTcType inner_ty
-- See Note [Visible type application zonk]
; let in_scope = mkInScopeSet (tyCoVarsOfTypes [upsilon_ty, ty_arg])
-
insted_ty = substTyWithInScope in_scope [tv] [ty_arg] inner_ty
-- NB: tv and ty_arg have the same kind, so this
-- substitution is kind-respecting
@@ -1276,30 +1362,19 @@ tcArgs fun orig_fun_ty fun_orig orig_args herald
, debugPprType inner_ty
, debugPprType insted_ty ])
- ; (inner_wrap, args', res_ty)
- <- go acc_args (n+1) insted_ty args
- -- inner_wrap :: insted_ty "->" (map typeOf args') -> res_ty
- ; let inst_wrap = mkWpTyApps [ty_arg]
- ; return ( inner_wrap <.> inst_wrap <.> wrap1
- , HsTypeArg l hs_ty_arg : args'
+ ; (args', res_ty) <- go (n+1) so_far insted_ty args
+ ; return ( addArgWrap wrap1 $ HsETypeArg loc hs_ty_arg ty_arg : args'
, res_ty ) }
_ -> ty_app_err upsilon_ty hs_ty_arg }
- go acc_args n fun_ty (HsValArg arg : args)
+ go n so_far fun_ty (HsEValArg loc arg : args)
= do { (wrap, [arg_ty], res_ty)
- <- matchActualFunTysPart herald fun_orig (Just (unLoc fun)) 1 fun_ty
- acc_args orig_expr_args_arity
- -- wrap :: fun_ty "->" arg_ty -> res_ty
+ <- matchActualFunTysPart herald fun_orig (Just fun)
+ n_val_args so_far 1 fun_ty
; arg' <- tcArg fun arg arg_ty n
- ; (inner_wrap, args', inner_res_ty)
- <- go (arg_ty : acc_args) (n+1) res_ty args
- -- inner_wrap :: res_ty "->" (map typeOf args') -> inner_res_ty
- ; return ( mkWpFun idHsWrapper inner_wrap arg_ty res_ty doc <.> wrap
- , HsValArg arg' : args'
+ ; (args', inner_res_ty) <- go (n+1) (arg_ty:so_far) res_ty args
+ ; return ( addArgWrap wrap $ HsEValArg loc arg' : args'
, inner_res_ty ) }
- where
- doc = text "When checking the" <+> speakNth n <+>
- text "argument to" <+> quotes (ppr fun)
ty_app_err ty arg
= do { (_, ty) <- zonkTidyTcType emptyTidyEnv ty
@@ -1389,21 +1464,27 @@ and we had the visible type application
-}
----------------
-tcArg :: LHsExpr GhcRn -- The function (for error messages)
+tcArg :: HsExpr GhcRn -- The function (for error messages)
-> LHsExpr GhcRn -- Actual arguments
- -> TcRhoType -- expected arg type
+ -> TcSigmaType -- expected arg type
-> Int -- # of argument
- -> TcM (LHsExpr GhcTcId) -- Resulting argument
-tcArg fun arg ty arg_no = addErrCtxt (funAppCtxt fun arg arg_no) $
- tcPolyExprNC arg ty
+ -> TcM (LHsExpr GhcTc) -- Resulting argument
+tcArg fun arg ty arg_no
+ = addErrCtxt (funAppCtxt fun arg arg_no) $
+ do { traceTc "tcArg {" $
+ vcat [ text "arg #" <> ppr arg_no <+> dcolon <+> ppr ty
+ , text "arg:" <+> ppr arg ]
+ ; arg' <- tcCheckExprNC arg ty
+ ; traceTc "tcArg }" empty
+ ; return arg' }
----------------
-tcTupArgs :: [LHsTupArg GhcRn] -> [TcSigmaType] -> TcM [LHsTupArg GhcTcId]
+tcTupArgs :: [LHsTupArg GhcRn] -> [TcSigmaType] -> TcM [LHsTupArg GhcTc]
tcTupArgs args tys
= ASSERT( equalLength args tys ) mapM go (args `zip` tys)
where
go (L l (Missing {}), arg_ty) = return (L l (Missing arg_ty))
- go (L l (Present x expr), arg_ty) = do { expr' <- tcPolyExpr expr arg_ty
+ go (L l (Present x expr), arg_ty) = do { expr' <- tcCheckExpr expr arg_ty
; return (L l (Present x expr')) }
---------------------------
@@ -1429,13 +1510,13 @@ tcSyntaxOpGen :: CtOrigin
-> ([TcSigmaType] -> TcM a)
-> TcM (a, SyntaxExprTc)
tcSyntaxOpGen orig (SyntaxExprRn op) arg_tys res_ty thing_inside
- = do { (expr, sigma) <- tcInferSigma $ noLoc op
+ = do { (expr, sigma) <- tcInferAppHead op
; traceTc "tcSyntaxOpGen" (ppr op $$ ppr expr $$ ppr sigma)
; (result, expr_wrap, arg_wraps, res_wrap)
<- tcSynArgA orig sigma arg_tys res_ty $
thing_inside
; traceTc "tcSyntaxOpGen" (ppr op $$ ppr expr $$ ppr sigma )
- ; return (result, SyntaxExprTc { syn_expr = mkHsWrap expr_wrap $ unLoc expr
+ ; return (result, SyntaxExprTc { syn_expr = mkHsWrap expr_wrap expr
, syn_arg_wraps = arg_wraps
, syn_res_wrap = res_wrap }) }
tcSyntaxOpGen _ NoSyntaxExprRn _ _ _ = panic "tcSyntaxOpGen"
@@ -1511,7 +1592,7 @@ tcSynArgE orig sigma_ty syn_ty thing_inside
doc = text "When checking a rebindable syntax operator arising from" <+> ppr orig
go rho_ty (SynType the_ty)
- = do { wrap <- tcSubTypeET orig GenSigCtxt the_ty rho_ty
+ = do { wrap <- tcSubTypePat orig GenSigCtxt the_ty rho_ty
; result <- thing_inside []
; return (result, wrap) }
@@ -1608,7 +1689,7 @@ in the other order, the extra signature in f2 is reqd.
* *
********************************************************************* -}
-tcExprSig :: LHsExpr GhcRn -> TcIdSigInfo -> TcM (LHsExpr GhcTcId, TcType)
+tcExprSig :: LHsExpr GhcRn -> TcIdSigInfo -> TcM (LHsExpr GhcTc, TcType)
tcExprSig expr (CompleteSig { sig_bndr = poly_id, sig_loc = loc })
= setSrcSpan loc $ -- Sets the location for the implication constraint
do { (tv_prs, theta, tau) <- tcInstType tcInstSkolTyVars poly_id
@@ -1621,7 +1702,7 @@ tcExprSig expr (CompleteSig { sig_bndr = poly_id, sig_loc = loc })
skol_tvs = map snd tv_prs
; (ev_binds, expr') <- checkConstraints skol_info skol_tvs given $
tcExtendNameTyVarEnv tv_prs $
- tcPolyExprNC expr tau
+ tcCheckExprNC expr tau
; let poly_wrap = mkWpTyLams skol_tvs
<.> mkWpLams given
@@ -1635,7 +1716,7 @@ tcExprSig expr sig@(PartialSig { psig_name = name, sig_loc = loc })
do { sig_inst <- tcInstSig sig
; expr' <- tcExtendNameTyVarEnv (sig_inst_skols sig_inst) $
tcExtendNameTyVarEnv (sig_inst_wcs sig_inst) $
- tcPolyExprNC expr (sig_inst_tau sig_inst)
+ tcCheckExprNC expr (sig_inst_tau sig_inst)
; return (expr', sig_inst) }
-- See Note [Partial expression signatures]
; let tau = sig_inst_tau sig_inst
@@ -1703,19 +1784,23 @@ CLong, as it should.
* *
********************************************************************* -}
-tcCheckId :: Name -> ExpRhoType -> TcM (HsExpr GhcTcId)
+tcCheckId :: Name -> ExpRhoType -> TcM (HsExpr GhcTc)
tcCheckId name res_ty
+ | name `hasKey` tagToEnumKey
+ = failWithTc (text "tagToEnum# must appear applied to one argument")
+ -- tcApp catches the case (tagToEnum# arg)
+
+ | otherwise
= do { (expr, actual_res_ty) <- tcInferId name
; traceTc "tcCheckId" (vcat [ppr name, ppr actual_res_ty, ppr res_ty])
- ; addFunResCtxt False (HsVar noExtField (noLoc name)) actual_res_ty res_ty $
+ ; addFunResCtxt False expr actual_res_ty res_ty $
tcWrapResultO (OccurrenceOf name) (HsVar noExtField (noLoc name)) expr
- actual_res_ty res_ty }
+ actual_res_ty res_ty }
-tcCheckRecSelId :: HsExpr GhcRn -> AmbiguousFieldOcc GhcRn -> ExpRhoType -> TcM (HsExpr GhcTcId)
-tcCheckRecSelId rn_expr f@(Unambiguous _ (L _ lbl)) res_ty
+tcCheckRecSelId :: HsExpr GhcRn -> AmbiguousFieldOcc GhcRn -> ExpRhoType -> TcM (HsExpr GhcTc)
+tcCheckRecSelId rn_expr f@(Unambiguous {}) res_ty
= do { (expr, actual_res_ty) <- tcInferRecSelId f
- ; addFunResCtxt False (HsRecFld noExtField f) actual_res_ty res_ty $
- tcWrapResultO (OccurrenceOfRecSel lbl) rn_expr expr actual_res_ty res_ty }
+ ; tcWrapResult rn_expr expr actual_res_ty res_ty }
tcCheckRecSelId rn_expr (Ambiguous _ lbl) res_ty
= case tcSplitFunTy_maybe =<< checkingExpType_maybe res_ty of
Nothing -> ambiguousSelector lbl
@@ -1724,7 +1809,7 @@ tcCheckRecSelId rn_expr (Ambiguous _ lbl) res_ty
res_ty }
------------------------
-tcInferRecSelId :: AmbiguousFieldOcc GhcRn -> TcM (HsExpr GhcTcId, TcRhoType)
+tcInferRecSelId :: AmbiguousFieldOcc GhcRn -> TcM (HsExpr GhcTc, TcRhoType)
tcInferRecSelId (Unambiguous sel (L _ lbl))
= do { (expr', ty) <- tc_infer_id lbl sel
; return (expr', ty) }
@@ -1732,14 +1817,10 @@ tcInferRecSelId (Ambiguous _ lbl)
= ambiguousSelector lbl
------------------------
-tcInferId :: Name -> TcM (HsExpr GhcTcId, TcSigmaType)
+tcInferId :: Name -> TcM (HsExpr GhcTc, TcSigmaType)
-- Look up an occurrence of an Id
-- Do not instantiate its type
tcInferId id_name
- | id_name `hasKey` tagToEnumKey
- = failWithTc (text "tagToEnum# must appear applied to one argument")
- -- tcApp catches the case (tagToEnum# arg)
-
| id_name `hasKey` assertIdKey
= do { dflags <- getDynFlags
; if gopt Opt_IgnoreAsserts dflags
@@ -1751,7 +1832,7 @@ tcInferId id_name
; traceTc "tcInferId" (ppr id_name <+> dcolon <+> ppr ty)
; return (expr, ty) }
-tc_infer_assert :: Name -> TcM (HsExpr GhcTcId, TcSigmaType)
+tc_infer_assert :: Name -> TcM (HsExpr GhcTc, TcSigmaType)
-- Deal with an occurrence of 'assert'
-- See Note [Adding the implicit parameter to 'assert']
tc_infer_assert assert_name
@@ -1761,7 +1842,7 @@ tc_infer_assert assert_name
; return (mkHsWrap wrap (HsVar noExtField (noLoc assert_error_id)), id_rho)
}
-tc_infer_id :: RdrName -> Name -> TcM (HsExpr GhcTcId, TcSigmaType)
+tc_infer_id :: RdrName -> Name -> TcM (HsExpr GhcTc, TcSigmaType)
tc_infer_id lbl id_name
= do { thing <- tcLookup id_name
; case thing of
@@ -1812,7 +1893,7 @@ tc_infer_id lbl id_name
| otherwise = return ()
-tcUnboundId :: HsExpr GhcRn -> OccName -> ExpRhoType -> TcM (HsExpr GhcTcId)
+tcUnboundId :: HsExpr GhcRn -> OccName -> ExpRhoType -> TcM (HsExpr GhcTc)
-- Typecheck an occurrence of an unbound Id
--
-- Some of these started life as a true expression hole "_".
@@ -1881,60 +1962,50 @@ the users that complain.
-}
-tcTagToEnum :: SrcSpan -> Name -> [LHsExprArgIn] -> ExpRhoType
- -> TcM (HsWrapper, LHsExpr GhcTcId, [LHsExprArgOut])
+isTagToEnum :: HsExpr GhcTc -> Bool
+isTagToEnum (HsVar _ (L _ fun_id)) = fun_id `hasKey` tagToEnumKey
+isTagToEnum _ = False
+
+tcTagToEnum :: HsExpr GhcRn -> HsExpr GhcTc -> [LHsExprArgOut]
+ -> TcSigmaType -> ExpRhoType
+ -> TcM (HsExpr GhcTc)
-- tagToEnum# :: forall a. Int# -> a
-- See Note [tagToEnum#] Urgh!
-tcTagToEnum loc fun_name args res_ty
- = do { fun <- tcLookupId fun_name
-
- ; let pars1 = mapMaybe isArgPar_maybe before
- pars2 = mapMaybe isArgPar_maybe after
- -- args contains exactly one HsValArg
- (before, _:after) = break isHsValArg args
-
- ; arg <- case filterOut isArgPar args of
- [HsTypeArg _ hs_ty_arg, HsValArg term_arg]
- -> do { ty_arg <- tcHsTypeApp hs_ty_arg liftedTypeKind
- ; _ <- tcSubTypeDS (OccurrenceOf fun_name) GenSigCtxt ty_arg res_ty
- -- other than influencing res_ty, we just
- -- don't care about a type arg passed in.
- -- So drop the evidence.
- ; return term_arg }
- [HsValArg term_arg] -> do { _ <- expTypeToType res_ty
- ; return term_arg }
- _ -> too_many_args "tagToEnum#" args
-
- ; res_ty <- readExpType res_ty
+tcTagToEnum expr fun args app_res_ty res_ty
+ = do { res_ty <- readExpType res_ty
; ty' <- zonkTcType res_ty
-- Check that the type is algebraic
- ; let mb_tc_app = tcSplitTyConApp_maybe ty'
- Just (tc, tc_args) = mb_tc_app
- ; checkTc (isJust mb_tc_app)
- (mk_error ty' doc1)
+ ; case tcSplitTyConApp_maybe ty' of {
+ Nothing -> do { addErrTc (mk_error ty' doc1)
+ ; vanilla_result } ;
+ Just (tc, tc_args) ->
- -- Look through any type family
+ do { -- Look through any type family
; fam_envs <- tcGetFamInstEnvs
- ; let (rep_tc, rep_args, coi)
- = tcLookupDataFamInst fam_envs tc tc_args
- -- coi :: tc tc_args ~R rep_tc rep_args
-
- ; checkTc (isEnumerationTyCon rep_tc)
- (mk_error ty' doc2)
-
- ; arg' <- tcMonoExpr arg (mkCheckExpType intPrimTy)
- ; let fun' = L loc (mkHsWrap (WpTyApp rep_ty) (HsVar noExtField (L loc fun)))
- rep_ty = mkTyConApp rep_tc rep_args
- out_args = concat
- [ pars1
- , [HsValArg arg']
- , pars2
- ]
-
- ; return (mkWpCastR (mkTcSymCo coi), fun', out_args) }
- -- coi is a Representational coercion
+ ; case tcLookupDataFamInst_maybe fam_envs tc tc_args of {
+ Nothing -> do { check_enumeration ty' tc
+ ; vanilla_result } ;
+ Just (rep_tc, rep_args, coi) ->
+
+ do { -- coi :: tc tc_args ~R rep_tc rep_args
+ check_enumeration ty' rep_tc
+ ; let val_arg = dropWhile (not . isHsValArg) args
+ rep_ty = mkTyConApp rep_tc rep_args
+ fun' = mkHsWrap (WpTyApp rep_ty) fun
+ expr' = applyHsArgs fun' val_arg
+ df_wrap = mkWpCastR (mkTcSymCo coi)
+ ; return (mkHsWrap df_wrap expr') }}}}}
+
where
+ vanilla_result
+ = do { let expr' = applyHsArgs fun args
+ ; tcWrapResult expr expr' app_res_ty res_ty }
+
+ check_enumeration ty' tc
+ | isEnumerationTyCon tc = return ()
+ | otherwise = addErrTc (mk_error ty' doc2)
+
doc1 = vcat [ text "Specify the type by giving a type signature"
, text "e.g. (tagToEnum# x) :: Bool" ]
doc2 = text "Result type must be an enumeration type"
@@ -1945,18 +2016,6 @@ tcTagToEnum loc fun_name args res_ty
<+> text "at type" <+> ppr ty)
2 what
-too_many_args :: String -> [LHsExprArgIn] -> TcM a
-too_many_args fun args
- = failWith $
- hang (text "Too many type arguments to" <+> text fun <> colon)
- 2 (sep (map pp args))
- where
- pp :: LHsExprArgIn -> SDoc
- pp (HsValArg e) = ppr e
- pp (HsTypeArg _ (HsWC { hswc_body = L _ t })) = pprHsType t
- pp (HsArgPar _) = empty
-
-
{-
************************************************************************
* *
@@ -2368,7 +2427,7 @@ tcRecordBinds
:: ConLike
-> [TcType] -- Expected type for each field
-> HsRecordBinds GhcRn
- -> TcM (HsRecordBinds GhcTcId)
+ -> TcM (HsRecordBinds GhcTc)
tcRecordBinds con_like arg_tys (HsRecFields rbinds dd)
= do { mb_binds <- mapM do_bind rbinds
@@ -2378,7 +2437,7 @@ tcRecordBinds con_like arg_tys (HsRecFields rbinds dd)
flds_w_tys = zipEqual "tcRecordBinds" fields arg_tys
do_bind :: LHsRecField GhcRn (LHsExpr GhcRn)
- -> TcM (Maybe (LHsRecField GhcTcId (LHsExpr GhcTcId)))
+ -> TcM (Maybe (LHsRecField GhcTc (LHsExpr GhcTc)))
do_bind (L l fld@(HsRecField { hsRecFieldLbl = f
, hsRecFieldArg = rhs }))
@@ -2392,7 +2451,7 @@ tcRecordUpd
:: ConLike
-> [TcType] -- Expected type for each field
-> [LHsRecField' (AmbiguousFieldOcc GhcTc) (LHsExpr GhcRn)]
- -> TcM [LHsRecUpdField GhcTcId]
+ -> TcM [LHsRecUpdField GhcTc]
tcRecordUpd con_like arg_tys rbinds = fmap catMaybes $ mapM do_bind rbinds
where
@@ -2400,7 +2459,7 @@ tcRecordUpd con_like arg_tys rbinds = fmap catMaybes $ mapM do_bind rbinds
flds_w_tys = zipEqual "tcRecordUpd" fields arg_tys
do_bind :: LHsRecField' (AmbiguousFieldOcc GhcTc) (LHsExpr GhcRn)
- -> TcM (Maybe (LHsRecUpdField GhcTcId))
+ -> TcM (Maybe (LHsRecUpdField GhcTc))
do_bind (L l fld@(HsRecField { hsRecFieldLbl = L loc af
, hsRecFieldArg = rhs }))
= do { let lbl = rdrNameAmbiguousFieldOcc af
@@ -2423,7 +2482,7 @@ tcRecordField :: ConLike -> Assoc Name Type
tcRecordField con_like flds_w_tys (L loc (FieldOcc sel_name lbl)) rhs
| Just field_ty <- assocMaybe flds_w_tys sel_name
= addErrCtxt (fieldCtxt field_lbl) $
- do { rhs' <- tcPolyExprNC rhs field_ty
+ do { rhs' <- tcCheckExprNC rhs field_ty
; let field_id = mkUserLocal (nameOccName sel_name)
(nameUnique sel_name)
field_ty loc
@@ -2494,19 +2553,18 @@ checkMissingFields con_like rbinds
Boring and alphabetical:
-}
-addExprErrCtxt :: LHsExpr GhcRn -> TcM a -> TcM a
-addExprErrCtxt expr = addErrCtxt (exprCtxt expr)
-
-exprCtxt :: LHsExpr GhcRn -> SDoc
-exprCtxt expr
- = hang (text "In the expression:") 2 (ppr (stripParensHsExpr expr))
-
fieldCtxt :: FieldLabelString -> SDoc
fieldCtxt field_name
= text "In the" <+> quotes (ppr field_name) <+> ptext (sLit "field of a record")
+addExprCtxt :: LHsExpr GhcRn -> TcRn a -> TcRn a
+addExprCtxt e thing_inside = addErrCtxt (exprCtxt (unLoc e)) thing_inside
+
+exprCtxt :: HsExpr GhcRn -> SDoc
+exprCtxt expr = hang (text "In the expression:") 2 (ppr (stripParensHsExpr expr))
+
addFunResCtxt :: Bool -- There is at least one argument
- -> HsExpr GhcRn -> TcType -> ExpRhoType
+ -> HsExpr GhcTc -> TcType -> ExpRhoType
-> TcM a -> TcM a
-- When we have a mis-match in the return type of a function
-- try to give a helpful message about too many/few arguments
diff --git a/compiler/GHC/Tc/Gen/Expr.hs-boot b/compiler/GHC/Tc/Gen/Expr.hs-boot
index 27ebefc9a3..d9138a4d7e 100644
--- a/compiler/GHC/Tc/Gen/Expr.hs-boot
+++ b/compiler/GHC/Tc/Gen/Expr.hs-boot
@@ -6,23 +6,16 @@ import GHC.Tc.Types ( TcM )
import GHC.Tc.Types.Origin ( CtOrigin )
import GHC.Hs.Extension ( GhcRn, GhcTcId )
-tcPolyExpr ::
- LHsExpr GhcRn
- -> TcSigmaType
- -> TcM (LHsExpr GhcTcId)
-
-tcMonoExpr, tcMonoExprNC ::
- LHsExpr GhcRn
- -> ExpRhoType
- -> TcM (LHsExpr GhcTcId)
-
-tcInferSigma ::
- LHsExpr GhcRn
- -> TcM (LHsExpr GhcTcId, TcSigmaType)
-
-tcInferRho, tcInferRhoNC ::
- LHsExpr GhcRn
- -> TcM (LHsExpr GhcTcId, TcRhoType)
+tcCheckExpr :: LHsExpr GhcRn -> TcSigmaType -> TcM (LHsExpr GhcTcId)
+
+tcLExpr, tcLExprNC
+ :: LHsExpr GhcRn -> ExpRhoType -> TcM (LHsExpr GhcTcId)
+tcExpr :: HsExpr GhcRn -> ExpRhoType -> TcM (HsExpr GhcTcId)
+
+tcInferRho, tcInferRhoNC
+ :: LHsExpr GhcRn-> TcM (LHsExpr GhcTcId, TcRhoType)
+
+tcInferSigma :: LHsExpr GhcRn-> TcM (LHsExpr GhcTcId, TcSigmaType)
tcSyntaxOp :: CtOrigin
-> SyntaxExprRn
diff --git a/compiler/GHC/Tc/Gen/Foreign.hs b/compiler/GHC/Tc/Gen/Foreign.hs
index f1031d6e14..858d865026 100644
--- a/compiler/GHC/Tc/Gen/Foreign.hs
+++ b/compiler/GHC/Tc/Gen/Foreign.hs
@@ -388,7 +388,7 @@ tcFExport fo@(ForeignExport { fd_name = L loc nm, fd_sig_ty = hs_ty, fd_fe = spe
= addErrCtxt (foreignDeclCtxt fo) $ do
sig_ty <- tcHsSigType (ForSigCtxt nm) hs_ty
- rhs <- tcPolyExpr (nlHsVar nm) sig_ty
+ rhs <- tcCheckExpr (nlHsVar nm) sig_ty
(norm_co, norm_sig_ty, gres) <- normaliseFfiType sig_ty
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.
diff --git a/compiler/GHC/Tc/Gen/Match.hs b/compiler/GHC/Tc/Gen/Match.hs
index 339093b47c..45fece68c0 100644
--- a/compiler/GHC/Tc/Gen/Match.hs
+++ b/compiler/GHC/Tc/Gen/Match.hs
@@ -37,7 +37,8 @@ where
import GhcPrelude
import {-# SOURCE #-} GHC.Tc.Gen.Expr( tcSyntaxOp, tcInferRhoNC, tcInferRho
- , tcCheckId, tcMonoExpr, tcMonoExprNC, tcPolyExpr )
+ , tcCheckId, tcLExpr, tcLExprNC, tcExpr
+ , tcCheckExpr )
import GHC.Types.Basic (LexicalFixity(..))
import GHC.Hs
@@ -331,7 +332,7 @@ tcDoStmts ctxt _ _ = pprPanic "tcDoStmts" (pprStmtContext ctxt)
tcBody :: LHsExpr GhcRn -> ExpRhoType -> TcM (LHsExpr GhcTcId)
tcBody body res_ty
= do { traceTc "tcBody" (ppr res_ty)
- ; tcMonoExpr body res_ty
+ ; tcLExpr body res_ty
}
{-
@@ -411,15 +412,15 @@ tcStmtsAndThen ctxt stmt_chk (L loc stmt : stmts) res_ty thing_inside
tcGuardStmt :: TcExprStmtChecker
tcGuardStmt _ (BodyStmt _ guard _ _) res_ty thing_inside
- = do { guard' <- tcMonoExpr guard (mkCheckExpType boolTy)
+ = do { guard' <- tcLExpr guard (mkCheckExpType boolTy)
; thing <- thing_inside res_ty
; return (BodyStmt boolTy guard' noSyntaxExpr noSyntaxExpr, thing) }
tcGuardStmt ctxt (BindStmt _ pat rhs) res_ty thing_inside
= do { (rhs', rhs_ty) <- tcInferRhoNC rhs
-- Stmt has a context already
- ; (pat', thing) <- tcPat_O (StmtCtxt ctxt) (lexprCtOrigin rhs)
- pat (mkCheckExpType rhs_ty) $
+ ; (pat', thing) <- tcCheckPat_O (StmtCtxt ctxt) (lexprCtOrigin rhs)
+ pat rhs_ty $
thing_inside res_ty
; return (mkTcBindStmt pat' rhs', thing) }
@@ -444,21 +445,21 @@ tcLcStmt :: TyCon -- The list type constructor ([])
-> TcExprStmtChecker
tcLcStmt _ _ (LastStmt x body noret _) elt_ty thing_inside
- = do { body' <- tcMonoExprNC body elt_ty
+ = do { body' <- tcLExprNC body elt_ty
; thing <- thing_inside (panic "tcLcStmt: thing_inside")
; return (LastStmt x body' noret noSyntaxExpr, thing) }
-- A generator, pat <- rhs
tcLcStmt m_tc ctxt (BindStmt _ pat rhs) elt_ty thing_inside
= do { pat_ty <- newFlexiTyVarTy liftedTypeKind
- ; rhs' <- tcMonoExpr rhs (mkCheckExpType $ mkTyConApp m_tc [pat_ty])
- ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat (mkCheckExpType pat_ty) $
+ ; rhs' <- tcLExpr rhs (mkCheckExpType $ mkTyConApp m_tc [pat_ty])
+ ; (pat', thing) <- tcCheckPat (StmtCtxt ctxt) pat pat_ty $
thing_inside elt_ty
; return (mkTcBindStmt pat' rhs', thing) }
-- A boolean guard
tcLcStmt _ _ (BodyStmt _ rhs _ _) elt_ty thing_inside
- = do { rhs' <- tcMonoExpr rhs (mkCheckExpType boolTy)
+ = do { rhs' <- tcLExpr rhs (mkCheckExpType boolTy)
; thing <- thing_inside elt_ty
; return (BodyStmt boolTy rhs' noSyntaxExpr noSyntaxExpr, thing) }
@@ -516,7 +517,7 @@ tcLcStmt m_tc ctxt (TransStmt { trS_form = form, trS_stmts = stmts
by_arrow $
poly_arg_ty `mkVisFunTy` poly_res_ty
- ; using' <- tcPolyExpr using using_poly_ty
+ ; using' <- tcCheckExpr using using_poly_ty
; let final_using = fmap (mkHsWrap (WpTyApp tup_ty)) using'
-- 'stmts' returns a result of type (m1_ty tuple_ty),
@@ -558,7 +559,7 @@ tcMcStmt _ (LastStmt x body noret return_op) res_ty thing_inside
= do { (body', return_op')
<- tcSyntaxOp MCompOrigin return_op [SynRho] res_ty $
\ [a_ty] ->
- tcMonoExprNC body (mkCheckExpType a_ty)
+ tcLExprNC body (mkCheckExpType a_ty)
; thing <- thing_inside (panic "tcMcStmt: thing_inside")
; return (LastStmt x body' noret return_op', thing) }
@@ -574,9 +575,8 @@ tcMcStmt ctxt (BindStmt xbsrn pat rhs) res_ty thing_inside
<- tcSyntaxOp MCompOrigin (xbsrn_bindOp xbsrn)
[SynRho, SynFun SynAny SynRho] res_ty $
\ [rhs_ty, pat_ty, new_res_ty] ->
- do { rhs' <- tcMonoExprNC rhs (mkCheckExpType rhs_ty)
- ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat
- (mkCheckExpType pat_ty) $
+ do { rhs' <- tcLExprNC rhs (mkCheckExpType rhs_ty)
+ ; (pat', thing) <- tcCheckPat (StmtCtxt ctxt) pat pat_ty $
thing_inside (mkCheckExpType new_res_ty)
; return (rhs', pat', thing, new_res_ty) }
@@ -607,7 +607,7 @@ tcMcStmt _ (BodyStmt _ rhs then_op guard_op) res_ty thing_inside
<- tcSyntaxOp MCompOrigin guard_op [SynAny]
(mkCheckExpType rhs_ty) $
\ [test_ty] ->
- tcMonoExpr rhs (mkCheckExpType test_ty)
+ tcLExpr rhs (mkCheckExpType test_ty)
; thing <- thing_inside (mkCheckExpType new_res_ty)
; return (thing, rhs', rhs_ty, guard_op') }
; return (BodyStmt rhs_ty rhs' then_op' guard_op', thing) }
@@ -667,7 +667,7 @@ tcMcStmt ctxt (TransStmt { trS_stmts = stmts, trS_bndrs = bindersMap
(mkCheckExpType using_arg_ty) $ \res_ty' -> do
{ by' <- case by of
Nothing -> return Nothing
- Just e -> do { e' <- tcMonoExpr e
+ Just e -> do { e' <- tcLExpr e
(mkCheckExpType by_e_ty)
; return (Just e') }
@@ -693,7 +693,7 @@ tcMcStmt ctxt (TransStmt { trS_stmts = stmts, trS_bndrs = bindersMap
--------------- Typecheck the 'fmap' function -------------
; fmap_op' <- case form of
ThenForm -> return noExpr
- _ -> fmap unLoc . tcPolyExpr (noLoc fmap_op) $
+ _ -> fmap unLoc . tcCheckExpr (noLoc fmap_op) $
mkInvForAllTy alphaTyVar $
mkInvForAllTy betaTyVar $
(alphaTy `mkVisFunTy` betaTy)
@@ -703,7 +703,7 @@ tcMcStmt ctxt (TransStmt { trS_stmts = stmts, trS_bndrs = bindersMap
--------------- Typecheck the 'using' function -------------
-- using :: ((a,b,c)->t) -> m1 (a,b,c) -> m2 (n (a,b,c))
- ; using' <- tcPolyExpr using using_poly_ty
+ ; using' <- tcCheckExpr using using_poly_ty
; let final_using = fmap (mkHsWrap (WpTyApp tup_ty)) using'
--------------- Building the bindersMap ----------------
@@ -765,7 +765,7 @@ tcMcStmt ctxt (ParStmt _ bndr_stmts_s mzip_op bind_op) res_ty thing_inside
(m_ty `mkAppTy` betaTy)
`mkVisFunTy`
(m_ty `mkAppTy` mkBoxedTupleTy [alphaTy, betaTy])
- ; mzip_op' <- unLoc `fmap` tcPolyExpr (noLoc mzip_op) mzip_ty
+ ; mzip_op' <- unLoc `fmap` tcCheckExpr (noLoc mzip_op) mzip_ty
-- type dummies since we don't know all binder types yet
; id_tys_s <- (mapM . mapM) (const (newFlexiTyVarTy liftedTypeKind))
@@ -827,7 +827,7 @@ tcMcStmt _ stmt _ _
tcDoStmt :: TcExprStmtChecker
tcDoStmt _ (LastStmt x body noret _) res_ty thing_inside
- = do { body' <- tcMonoExprNC body res_ty
+ = do { body' <- tcLExprNC body res_ty
; thing <- thing_inside (panic "tcDoStmt: thing_inside")
; return (LastStmt x body' noret noSyntaxExpr, thing) }
@@ -840,9 +840,8 @@ tcDoStmt ctxt (BindStmt xbsrn pat rhs) res_ty thing_inside
((rhs', pat', new_res_ty, thing), bind_op')
<- tcSyntaxOp DoOrigin (xbsrn_bindOp xbsrn) [SynRho, SynFun SynAny SynRho] res_ty $
\ [rhs_ty, pat_ty, new_res_ty] ->
- do { rhs' <- tcMonoExprNC rhs (mkCheckExpType rhs_ty)
- ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat
- (mkCheckExpType pat_ty) $
+ do { rhs' <- tcLExprNC rhs (mkCheckExpType rhs_ty)
+ ; (pat', thing) <- tcCheckPat (StmtCtxt ctxt) pat pat_ty $
thing_inside (mkCheckExpType new_res_ty)
; return (rhs', pat', new_res_ty, thing) }
@@ -874,7 +873,7 @@ tcDoStmt _ (BodyStmt _ rhs then_op _) res_ty thing_inside
; ((rhs', rhs_ty, thing), then_op')
<- tcSyntaxOp DoOrigin then_op [SynRho, SynRho] res_ty $
\ [rhs_ty, new_res_ty] ->
- do { rhs' <- tcMonoExprNC rhs (mkCheckExpType rhs_ty)
+ do { rhs' <- tcLExprNC rhs (mkCheckExpType rhs_ty)
; thing <- thing_inside (mkCheckExpType new_res_ty)
; return (rhs', rhs_ty, thing) }
; return (BodyStmt rhs_ty rhs' then_op' noSyntaxExpr, thing) }
@@ -890,7 +889,7 @@ tcDoStmt ctxt (RecStmt { recS_stmts = stmts, recS_later_ids = later_names
; tcExtendIdEnv tup_ids $ do
{ ((stmts', (ret_op', tup_rets)), stmts_ty)
- <- tcInferInst $ \ exp_ty ->
+ <- tcInfer $ \ exp_ty ->
tcStmtsAndThen ctxt tcDoStmt stmts exp_ty $ \ inner_res_ty ->
do { tup_rets <- zipWithM tcCheckId tup_names
(map mkCheckExpType tup_elt_tys)
@@ -902,7 +901,7 @@ tcDoStmt ctxt (RecStmt { recS_stmts = stmts, recS_later_ids = later_names
; return (ret_op', tup_rets) }
; ((_, mfix_op'), mfix_res_ty)
- <- tcInferInst $ \ exp_ty ->
+ <- tcInfer $ \ exp_ty ->
tcSyntaxOp DoOrigin mfix_op
[synKnownType (mkVisFunTy tup_ty stmts_ty)] exp_ty $
\ _ -> return ()
@@ -968,7 +967,7 @@ When typechecking
do { bar; ... } :: IO ()
we want to typecheck 'bar' in the knowledge that it should be an IO thing,
pushing info from the context into the RHS. To do this, we check the
-rebindable syntax first, and push that information into (tcMonoExprNC rhs).
+rebindable syntax first, and push that information into (tcLExprNC rhs).
Otherwise the error shows up when checking the rebindable syntax, and
the expected/inferred stuff is back to front (see #3613).
@@ -1000,7 +999,7 @@ tcApplicativeStmts
tcApplicativeStmts ctxt pairs rhs_ty thing_inside
= do { body_ty <- newFlexiTyVarTy liftedTypeKind
; let arity = length pairs
- ; ts <- replicateM (arity-1) $ newInferExpTypeInst
+ ; ts <- replicateM (arity-1) $ newInferExpType
; exp_tys <- replicateM arity $ newFlexiTyVarTy liftedTypeKind
; pat_tys <- replicateM arity $ newFlexiTyVarTy liftedTypeKind
; let fun_ty = mkVisFunTys pat_tys body_ty
@@ -1044,8 +1043,8 @@ tcApplicativeStmts ctxt pairs rhs_ty thing_inside
}, pat_ty, exp_ty)
= setSrcSpan (combineSrcSpans (getLoc pat) (getLoc rhs)) $
addErrCtxt (pprStmtInCtxt ctxt (mkRnBindStmt pat rhs)) $
- do { rhs' <- tcMonoExprNC rhs (mkCheckExpType exp_ty)
- ; (pat', _) <- tcPat (StmtCtxt ctxt) pat (mkCheckExpType pat_ty) $
+ do { rhs' <- tcLExprNC rhs (mkCheckExpType exp_ty)
+ ; (pat', _) <- tcCheckPat (StmtCtxt ctxt) pat pat_ty $
return ()
; fail_op' <- fmap join . forM fail_op $ \fail ->
tcMonadFailOp (DoPatOrigin pat) pat' fail body_ty
@@ -1061,8 +1060,8 @@ tcApplicativeStmts ctxt pairs rhs_ty thing_inside
= do { (stmts', (ret',pat')) <-
tcStmtsAndThen ctxt tcDoStmt stmts (mkCheckExpType exp_ty) $
\res_ty -> do
- { L _ ret' <- tcMonoExprNC (noLoc ret) res_ty
- ; (pat', _) <- tcPat (StmtCtxt ctxt) pat (mkCheckExpType pat_ty) $
+ { ret' <- tcExpr ret res_ty
+ ; (pat', _) <- tcCheckPat (StmtCtxt ctxt) pat pat_ty $
return ()
; return (ret', pat')
}
diff --git a/compiler/GHC/Tc/Gen/Pat.hs b/compiler/GHC/Tc/Gen/Pat.hs
index 9b3318a78f..2ae1f1cfb9 100644
--- a/compiler/GHC/Tc/Gen/Pat.hs
+++ b/compiler/GHC/Tc/Gen/Pat.hs
@@ -16,8 +16,7 @@ module GHC.Tc.Gen.Pat
( tcLetPat
, newLetBndr
, LetBndrSpec(..)
- , tcPat
- , tcPat_O
+ , tcCheckPat, tcCheckPat_O, tcInferPat
, tcPats
, addDataConStupidTheta
, badFieldCon
@@ -63,6 +62,7 @@ import Util
import Outputable
import qualified GHC.LanguageExtensions as LangExt
import Control.Arrow ( second )
+import Control.Monad ( when )
import ListSetOps ( getNth )
{-
@@ -112,20 +112,29 @@ tcPats ctxt pats pat_tys thing_inside
where
penv = PE { pe_lazy = False, pe_ctxt = LamPat ctxt, pe_orig = PatOrigin }
-tcPat :: HsMatchContext GhcRn
- -> LPat GhcRn -> ExpSigmaType
- -> TcM a -- Checker for body
- -> TcM (LPat GhcTcId, a)
-tcPat ctxt = tcPat_O ctxt PatOrigin
+tcInferPat :: HsMatchContext GhcRn -> LPat GhcRn
+ -> TcM a
+ -> TcM ((LPat GhcTcId, a), TcSigmaType)
+tcInferPat ctxt pat thing_inside
+ = tcInfer $ \ exp_ty ->
+ tc_lpat pat exp_ty penv thing_inside
+ where
+ penv = PE { pe_lazy = False, pe_ctxt = LamPat ctxt, pe_orig = PatOrigin }
+
+tcCheckPat :: HsMatchContext GhcRn
+ -> LPat GhcRn -> TcSigmaType
+ -> TcM a -- Checker for body
+ -> TcM (LPat GhcTcId, a)
+tcCheckPat ctxt = tcCheckPat_O ctxt PatOrigin
-- | A variant of 'tcPat' that takes a custom origin
-tcPat_O :: HsMatchContext GhcRn
- -> CtOrigin -- ^ origin to use if the type needs inst'ing
- -> LPat GhcRn -> ExpSigmaType
- -> TcM a -- Checker for body
- -> TcM (LPat GhcTcId, a)
-tcPat_O ctxt orig pat pat_ty thing_inside
- = tc_lpat pat pat_ty penv thing_inside
+tcCheckPat_O :: HsMatchContext GhcRn
+ -> CtOrigin -- ^ origin to use if the type needs inst'ing
+ -> LPat GhcRn -> TcSigmaType
+ -> TcM a -- Checker for body
+ -> TcM (LPat GhcTcId, a)
+tcCheckPat_O ctxt orig pat pat_ty thing_inside
+ = tc_lpat pat (mkCheckExpType pat_ty) penv thing_inside
where
penv = PE { pe_lazy = False, pe_ctxt = LamPat ctxt, pe_orig = orig }
@@ -199,7 +208,7 @@ tcPatBndr penv@(PE { pe_ctxt = LetPat { pc_lvl = bind_lvl
-- Note [Typechecking pattern bindings] in GHC.Tc.Gen.Bind
| Just bndr_id <- sig_fn bndr_name -- There is a signature
- = do { wrap <- tcSubTypePat penv exp_pat_ty (idType bndr_id)
+ = do { wrap <- tc_sub_type penv exp_pat_ty (idType bndr_id)
-- See Note [Subsumption check at pattern variables]
; traceTc "tcPatBndr(sig)" (ppr bndr_id $$ ppr (idType bndr_id) $$ ppr exp_pat_ty)
; return (wrap, bndr_id) }
@@ -243,10 +252,10 @@ newLetBndr LetLclBndr name ty
newLetBndr (LetGblBndr prags) name ty
= addInlinePrags (mkLocalId name ty) (lookupPragEnv prags name)
-tcSubTypePat :: PatEnv -> ExpSigmaType -> TcSigmaType -> TcM HsWrapper
+tc_sub_type :: PatEnv -> ExpSigmaType -> TcSigmaType -> TcM HsWrapper
-- tcSubTypeET with the UserTypeCtxt specialised to GenSigCtxt
--- Used when typechecking patterns
-tcSubTypePat penv t1 t2 = tcSubTypeET (pe_orig penv) GenSigCtxt t1 t2
+-- Used during typechecking patterns
+tc_sub_type penv t1 t2 = tcSubTypePat (pe_orig penv) GenSigCtxt t1 t2
{- Note [Subsumption check at pattern variables]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -390,22 +399,31 @@ tc_pat penv (AsPat x (L nm_loc name) pat) pat_ty thing_inside
tc_pat penv (ViewPat _ expr pat) overall_pat_ty thing_inside
= do {
- -- Expr must have type `forall a1...aN. OPT' -> B`
- -- where overall_pat_ty is an instance of OPT'.
- ; (expr',expr'_inferred) <- tcInferSigma expr
-
- -- expression must be a function
+ -- We use tcInferRho here.
+ -- If we have a view function with types like:
+ -- blah -> forall b. burble
+ -- then simple-subsumption means that 'forall b' won't be instantiated
+ -- so we can typecheck the inner pattern with that type
+ -- An exotic example:
+ -- pair :: forall a. a -> forall b. b -> (a,b)
+ -- f (pair True -> x) = ...here (x :: forall b. b -> (Bool,b))
+ --
+ -- TEMPORARY: pending simple subsumption, use tcInferSigma
+ -- When removing this, remove it from Expr.hs-boot too
+ ; (expr',expr_ty) <- tcInferSigma expr
+
+ -- Expression must be a function
; let expr_orig = lexprCtOrigin expr
herald = text "A view pattern expression expects"
; (expr_wrap1, [inf_arg_ty], inf_res_ty)
- <- matchActualFunTys herald expr_orig (Just (unLoc expr)) 1 expr'_inferred
- -- expr_wrap1 :: expr'_inferred "->" (inf_arg_ty -> inf_res_ty)
+ <- matchActualFunTys herald expr_orig (Just (unLoc expr)) 1 expr_ty
+ -- expr_wrap1 :: expr_ty "->" (inf_arg_ty -> inf_res_ty)
- -- check that overall pattern is more polymorphic than arg type
- ; expr_wrap2 <- tcSubTypePat penv overall_pat_ty inf_arg_ty
+ -- Check that overall pattern is more polymorphic than arg type
+ ; expr_wrap2 <- tc_sub_type penv overall_pat_ty inf_arg_ty
-- expr_wrap2 :: overall_pat_ty "->" inf_arg_ty
- -- pattern must have inf_res_ty
+ -- Pattern must have inf_res_ty
; (pat', res) <- tc_lpat pat (mkCheckExpType inf_res_ty) penv thing_inside
; overall_pat_ty <- readExpType overall_pat_ty
@@ -510,7 +528,7 @@ tc_pat penv (ConPatIn con arg_pats) pat_ty thing_inside
-- Literal patterns
tc_pat penv (LitPat x simple_lit) pat_ty thing_inside
= do { let lit_ty = hsLitType simple_lit
- ; wrap <- tcSubTypePat penv pat_ty lit_ty
+ ; wrap <- tc_sub_type penv pat_ty lit_ty
; res <- thing_inside
; pat_ty <- readExpType pat_ty
; return ( mkHsWrapPat wrap (LitPat x (convertLit simple_lit)) pat_ty
@@ -666,6 +684,66 @@ because they won't be in scope when we do the desugaring
************************************************************************
* *
+ Pattern signatures (pat :: type)
+* *
+************************************************************************
+-}
+
+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) $
+ tcSubTypePat 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) $
+ tcSubTypePat 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")
+
+
+{- *********************************************************************
+* *
Most of the work for constructors is here
(the rest is in the ConPatIn case of tc_pat)
* *
@@ -855,7 +933,7 @@ tcPatSynPat penv (L con_span _) pat_syn pat_ty arg_pats thing_inside
prov_theta' = substTheta tenv prov_theta
req_theta' = substTheta tenv req_theta
- ; wrap <- tcSubTypePat penv pat_ty ty'
+ ; wrap <- tc_sub_type penv pat_ty ty'
; traceTc "tcPatSynPat" (ppr pat_syn $$
ppr pat_ty $$
ppr ty' $$
diff --git a/compiler/GHC/Tc/Gen/Rule.hs b/compiler/GHC/Tc/Gen/Rule.hs
index eaa0534770..35b20acaa8 100644
--- a/compiler/GHC/Tc/Gen/Rule.hs
+++ b/compiler/GHC/Tc/Gen/Rule.hs
@@ -199,7 +199,7 @@ generateRuleConstraints ty_bndrs tm_bndrs lhs rhs
do { -- See Note [Solve order for RULES]
((lhs', rule_ty), lhs_wanted) <- captureConstraints (tcInferRho lhs)
; (rhs', rhs_wanted) <- captureConstraints $
- tcMonoExpr rhs (mkCheckExpType rule_ty)
+ tcLExpr rhs (mkCheckExpType rule_ty)
; let all_lhs_wanted = bndr_wanted `andWC` lhs_wanted
; return (id_bndrs, lhs', all_lhs_wanted, rhs', rhs_wanted, rule_ty) } }
diff --git a/compiler/GHC/Tc/Gen/Splice.hs b/compiler/GHC/Tc/Gen/Splice.hs
index 87b23a8b27..830e17abd4 100644
--- a/compiler/GHC/Tc/Gen/Splice.hs
+++ b/compiler/GHC/Tc/Gen/Splice.hs
@@ -286,7 +286,7 @@ tcPendingSplice m_var (PendingRnSplice flavour splice_name expr)
= do { meta_ty <- tcMetaTy meta_ty_name
-- Expected type of splice, e.g. m Exp
; let expected_type = mkAppTy m_var meta_ty
- ; expr' <- tcPolyExpr expr expected_type
+ ; expr' <- tcCheckExpr expr expected_type
; return (PendingTcSplice splice_name expr') }
where
meta_ty_name = case flavour of
@@ -616,7 +616,7 @@ tcNestedSplice pop_stage (TcPending ps_var lie_var q@(QuoteWrapper _ m_var)) spl
; meta_exp_ty <- tcTExpTy m_var res_ty
; expr' <- setStage pop_stage $
setConstraintVar lie_var $
- tcMonoExpr expr (mkCheckExpType meta_exp_ty)
+ tcLExpr expr (mkCheckExpType meta_exp_ty)
; untypeq <- tcLookupId unTypeQName
; let expr'' = mkHsApp
(mkLHsWrap (applyQuoteWrapper q)
@@ -639,7 +639,7 @@ tcTopSplice expr res_ty
-- Top level splices must still be of type Q (TExp a)
; meta_exp_ty <- tcTExpTy q_type res_ty
; q_expr <- tcTopSpliceExpr Typed $
- tcMonoExpr expr (mkCheckExpType meta_exp_ty)
+ tcLExpr expr (mkCheckExpType meta_exp_ty)
; lcl_env <- getLclEnv
; let delayed_splice
= DelayedSplice lcl_env expr res_ty q_expr
@@ -676,7 +676,7 @@ runTopSplice (DelayedSplice lcl_env orig_expr res_ty q_expr)
captureConstraints $
addErrCtxt (spliceResultDoc zonked_q_expr) $ do
{ (exp3, _fvs) <- rnLExpr expr2
- ; tcMonoExpr exp3 (mkCheckExpType zonked_ty)}
+ ; tcLExpr exp3 (mkCheckExpType zonked_ty)}
; ev <- simplifyTop wcs
; return $ unLoc (mkHsDictLet (EvBinds ev) res)
}
@@ -709,7 +709,7 @@ tcTopSpliceExpr :: SpliceType -> TcM (LHsExpr GhcTc) -> TcM (LHsExpr GhcTc)
-- Note that set the level to Splice, regardless of the original level,
-- before typechecking the expression. For example:
-- f x = $( ...$(g 3) ... )
--- The recursive call to tcPolyExpr will simply expand the
+-- The recursive call to tcCheckExpr will simply expand the
-- inner escape before dealing with the outer one
tcTopSpliceExpr isTypedSplice tc_action
diff --git a/compiler/GHC/Tc/Module.hs b/compiler/GHC/Tc/Module.hs
index 17f2dd69d5..cc3bf4a2cc 100644
--- a/compiler/GHC/Tc/Module.hs
+++ b/compiler/GHC/Tc/Module.hs
@@ -56,7 +56,6 @@ import GHC.Iface.Env ( externaliseName )
import GHC.Tc.Gen.HsType
import GHC.Tc.Validity( checkValidType )
import GHC.Tc.Gen.Match
-import GHC.Tc.Utils.Instantiate( deeplyInstantiate )
import GHC.Tc.Utils.Unify( checkConstraints )
import GHC.Rename.HsType
import GHC.Rename.Expr
@@ -1785,8 +1784,8 @@ check_main dflags tcg_env explicit_mod_hdr export_ies
; (ev_binds, main_expr)
<- checkConstraints skol_info [] [] $
addErrCtxt mainCtxt $
- tcMonoExpr (L loc (HsVar noExtField (L loc main_name)))
- (mkCheckExpType io_ty)
+ tcLExpr (L loc (HsVar noExtField (L loc main_name)))
+ (mkCheckExpType io_ty)
-- See Note [Root-main Id]
-- Construct the binding
@@ -2491,15 +2490,11 @@ tcRnExpr hsc_env mode rdr_expr
-- Now typecheck the expression, and generalise its type
-- it might have a rank-2 type (e.g. :t runST)
uniq <- newUnique ;
- let { fresh_it = itName uniq (getLoc rdr_expr)
- ; orig = lexprCtOrigin rn_expr } ;
- ((tclvl, res_ty), lie)
+ let { fresh_it = itName uniq (getLoc rdr_expr) } ;
+ ((tclvl, (_tc_expr, res_ty)), lie)
<- captureTopConstraints $
pushTcLevelM $
- do { (_tc_expr, expr_ty) <- tcInferSigma rn_expr
- ; if inst
- then snd <$> deeplyInstantiate orig expr_ty
- else return expr_ty } ;
+ tc_infer rn_expr ;
-- Generalise
(qtvs, dicts, _, residual, _)
@@ -2525,12 +2520,35 @@ tcRnExpr hsc_env mode rdr_expr
return (snd (normaliseType fam_envs Nominal ty))
}
where
+ tc_infer expr | inst = tcInferRho expr
+ | otherwise = tcInferSigma expr
+ -- tcInferSigma: see Note [Implementing :type]
+
-- See Note [TcRnExprMode]
(inst, infer_mode, perhaps_disable_default_warnings) = case mode of
TM_Inst -> (True, NoRestrictions, id)
TM_NoInst -> (False, NoRestrictions, id)
TM_Default -> (True, EagerDefaulting, unsetWOptM Opt_WarnTypeDefaults)
+{- Note [Implementing :type]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Consider :type const
+
+We want forall a b. a -> b -> a
+and not forall {a}{b}. a -> b -> a
+
+The latter is what we'd get if we eagerly instantiated and then
+re-generalised with Inferred binders. It makes a difference, because
+it tells us we where we can use Visible Type Application (VTA).
+
+And also for :type const @Int
+we want forall b. Int -> b -> Int
+and not forall {b}. Int -> b -> Int
+
+Solution: use tcInferSigma, which in turn uses tcInferApp, which
+has a special case for application chains.
+-}
+
--------------------------
tcRnImportDecls :: HscEnv
-> [LImportDecl GhcPs]
diff --git a/compiler/GHC/Tc/TyCl/PatSyn.hs b/compiler/GHC/Tc/TyCl/PatSyn.hs
index 0a719d90d2..797ff2f594 100644
--- a/compiler/GHC/Tc/TyCl/PatSyn.hs
+++ b/compiler/GHC/Tc/TyCl/PatSyn.hs
@@ -147,8 +147,7 @@ tcInferPatSynDecl (PSB { psb_id = lname@(L _ name), psb_args = details
; let (arg_names, rec_fields, is_infix) = collectPatSynArgInfo details
; (tclvl, wanted, ((lpat', args), pat_ty))
<- pushLevelAndCaptureConstraints $
- tcInferNoInst $ \ exp_ty ->
- tcPat PatSyn lpat exp_ty $
+ tcInferPat PatSyn lpat $
mapM tcLookupId arg_names
; let (ex_tvs, prov_dicts) = tcCollectEx lpat'
@@ -386,9 +385,9 @@ tcCheckPatSynDecl psb@PSB{ psb_id = lname@(L _ name), psb_args = details
; req_dicts <- newEvVars req_theta
; (tclvl, wanted, (lpat', (ex_tvs', prov_dicts, args'))) <-
ASSERT2( equalLength arg_names arg_tys, ppr name $$ ppr arg_names $$ ppr arg_tys )
- pushLevelAndCaptureConstraints $
- tcExtendTyVarEnv univ_tvs $
- tcPat PatSyn lpat (mkCheckExpType pat_ty) $
+ pushLevelAndCaptureConstraints $
+ tcExtendTyVarEnv univ_tvs $
+ tcCheckPat PatSyn lpat pat_ty $
do { let in_scope = mkInScopeSet (mkVarSet univ_tvs)
empty_subst = mkEmptyTCvSubst in_scope
; (subst, ex_tvs') <- mapAccumLM newMetaTyVarX empty_subst ex_tvs
diff --git a/compiler/GHC/Tc/Types/Origin.hs b/compiler/GHC/Tc/Types/Origin.hs
index d67cc71150..86427853de 100644
--- a/compiler/GHC/Tc/Types/Origin.hs
+++ b/compiler/GHC/Tc/Types/Origin.hs
@@ -474,7 +474,7 @@ exprCtOrigin :: HsExpr GhcRn -> CtOrigin
exprCtOrigin (HsVar _ (L _ name)) = OccurrenceOf name
exprCtOrigin (HsUnboundVar _ uv) = UnboundOccurrenceOf uv
exprCtOrigin (HsConLikeOut {}) = panic "exprCtOrigin HsConLikeOut"
-exprCtOrigin (HsRecFld _ f) = OccurrenceOfRecSel (rdrNameAmbiguousFieldOcc f)
+exprCtOrigin (HsRecFld _ f) = OccurrenceOfRecSel (rdrNameAmbiguousFieldOcc f)
exprCtOrigin (HsOverLabel _ _ l) = OverLabelOrigin l
exprCtOrigin (HsIPVar _ ip) = IPOccOrigin ip
exprCtOrigin (HsOverLit _ lit) = LiteralOrigin lit
diff --git a/compiler/GHC/Tc/Utils/Instantiate.hs b/compiler/GHC/Tc/Utils/Instantiate.hs
index e896c7851e..7e45b5d947 100644
--- a/compiler/GHC/Tc/Utils/Instantiate.hs
+++ b/compiler/GHC/Tc/Utils/Instantiate.hs
@@ -36,7 +36,7 @@ module GHC.Tc.Utils.Instantiate (
import GhcPrelude
-import {-# SOURCE #-} GHC.Tc.Gen.Expr( tcPolyExpr, tcSyntaxOp )
+import {-# SOURCE #-} GHC.Tc.Gen.Expr( tcCheckExpr, tcSyntaxOp )
import {-# SOURCE #-} GHC.Tc.Utils.Unify( unifyType, unifyKind )
import GHC.Types.Basic ( IntegralLit(..), SourceText(..) )
@@ -639,7 +639,7 @@ tcSyntaxName orig ty (std_nm, user_nm_expr) = do
-- same type as the standard one.
-- Tiresome jiggling because tcCheckSigma takes a located expression
span <- getSrcSpanM
- expr <- tcPolyExpr (L span user_nm_expr) sigma1
+ expr <- tcCheckExpr (L span user_nm_expr) sigma1
return (std_nm, unLoc expr)
syntaxNameCtxt :: HsExpr GhcRn -> CtOrigin -> Type -> TidyEnv
diff --git a/compiler/GHC/Tc/Utils/Monad.hs b/compiler/GHC/Tc/Utils/Monad.hs
index 0b84f69096..918a71594d 100644
--- a/compiler/GHC/Tc/Utils/Monad.hs
+++ b/compiler/GHC/Tc/Utils/Monad.hs
@@ -835,9 +835,8 @@ addLocM :: (a -> TcM b) -> Located a -> TcM b
addLocM fn (L loc a) = setSrcSpan loc $ fn a
wrapLocM :: (a -> TcM b) -> Located a -> TcM (Located b)
--- wrapLocM :: (a -> TcM b) -> Located a -> TcM (Located b)
wrapLocM fn (L loc a) = setSrcSpan loc $ do { b <- fn a
- ; return (L loc b) }
+ ; return (L loc b) }
wrapLocFstM :: (a -> TcM (b,c)) -> Located a -> TcM (Located b, c)
wrapLocFstM fn (L loc a) =
diff --git a/compiler/GHC/Tc/Utils/TcMType.hs b/compiler/GHC/Tc/Utils/TcMType.hs
index 53b93f51a3..d37b37efe3 100644
--- a/compiler/GHC/Tc/Utils/TcMType.hs
+++ b/compiler/GHC/Tc/Utils/TcMType.hs
@@ -33,7 +33,7 @@ module GHC.Tc.Utils.TcMType (
-- Expected types
ExpType(..), ExpSigmaType, ExpRhoType,
mkCheckExpType,
- newInferExpType, newInferExpTypeInst, newInferExpTypeNoInst,
+ newInferExpType,
readExpType, readExpType_maybe,
expTypeToType, checkingExpType_maybe, checkingExpType,
tauifyExpType, inferResultToType,
@@ -440,21 +440,14 @@ test gadt/gadt-escape1.
-- actual data definition is in GHC.Tc.Utils.TcType
--- | Make an 'ExpType' suitable for inferring a type of kind * or #.
-newInferExpTypeNoInst :: TcM ExpSigmaType
-newInferExpTypeNoInst = newInferExpType False
-
-newInferExpTypeInst :: TcM ExpRhoType
-newInferExpTypeInst = newInferExpType True
-
-newInferExpType :: Bool -> TcM ExpType
-newInferExpType inst
+newInferExpType :: TcM ExpType
+newInferExpType
= do { u <- newUnique
; tclvl <- getTcLevel
- ; traceTc "newOpenInferExpType" (ppr u <+> ppr inst <+> ppr tclvl)
+ ; traceTc "newInferExpType" (ppr u <+> ppr tclvl)
; ref <- newMutVar Nothing
; return (Infer (IR { ir_uniq = u, ir_lvl = tclvl
- , ir_ref = ref, ir_inst = inst })) }
+ , ir_ref = ref })) }
-- | Extract a type out of an ExpType, if one exists. But one should always
-- exist. Unless you're quite sure you know what you're doing.
diff --git a/compiler/GHC/Tc/Utils/TcType.hs b/compiler/GHC/Tc/Utils/TcType.hs
index 8e1cef1a86..dc1ef3a69e 100644
--- a/compiler/GHC/Tc/Utils/TcType.hs
+++ b/compiler/GHC/Tc/Utils/TcType.hs
@@ -368,13 +368,6 @@ data InferResult
, ir_lvl :: TcLevel -- See Note [TcLevel of ExpType] in GHC.Tc.Utils.TcMType
- , ir_inst :: Bool
- -- True <=> deeply instantiate before returning
- -- i.e. return a RhoType
- -- False <=> do not instantiate before returning
- -- i.e. return a SigmaType
- -- See Note [Deep instantiation of InferResult] in GHC.Tc.Utils.Unify
-
, ir_ref :: IORef (Maybe TcType) }
-- The type that fills in this hole should be a Type,
-- that is, its kind should be (TYPE rr) for some rr
@@ -387,9 +380,8 @@ instance Outputable ExpType where
ppr (Infer ir) = ppr ir
instance Outputable InferResult where
- ppr (IR { ir_uniq = u, ir_lvl = lvl
- , ir_inst = inst })
- = text "Infer" <> braces (ppr u <> comma <> ppr lvl <+> ppr inst)
+ ppr (IR { ir_uniq = u, ir_lvl = lvl })
+ = text "Infer" <> braces (ppr u <> comma <> ppr lvl)
-- | Make an 'ExpType' suitable for checking.
mkCheckExpType :: TcType -> ExpType
diff --git a/compiler/GHC/Tc/Utils/Unify.hs b/compiler/GHC/Tc/Utils/Unify.hs
index c6b0f8bae4..6a4d61627b 100644
--- a/compiler/GHC/Tc/Utils/Unify.hs
+++ b/compiler/GHC/Tc/Utils/Unify.hs
@@ -15,7 +15,7 @@ module GHC.Tc.Utils.Unify (
-- Full-blown subsumption
tcWrapResult, tcWrapResultO, tcSkolemise, tcSkolemiseET,
tcSubTypeHR, tcSubTypeO, tcSubType_NC, tcSubTypeDS,
- tcSubTypeDS_NC_O, tcSubTypeET,
+ tcSubTypeDS_NC_O, tcSubTypePat,
checkConstraints, checkTvConstraints,
buildImplicationFor, emitResidualTvConstraint,
@@ -26,7 +26,7 @@ module GHC.Tc.Utils.Unify (
--------------------------------
-- Holes
- tcInferInst, tcInferNoInst,
+ tcInfer,
matchExpectedListTy,
matchExpectedTyConApp,
matchExpectedAppTy,
@@ -193,14 +193,14 @@ matchExpectedFunTys herald arity orig_ty thing_inside
--
-- But in that case we add specialized type into error context
-- anyway, because it may be useful. See also #9605.
- go acc_arg_tys n ty = addErrCtxtM mk_ctxt $
+ go acc_arg_tys n ty = addErrCtxtM (mk_ctxt acc_arg_tys ty) $
defer acc_arg_tys n (mkCheckExpType ty)
------------
defer :: [ExpSigmaType] -> Arity -> ExpRhoType -> TcM (a, HsWrapper)
defer acc_arg_tys n fun_ty
- = do { more_arg_tys <- replicateM n newInferExpTypeNoInst
- ; res_ty <- newInferExpTypeInst
+ = do { more_arg_tys <- replicateM n newInferExpType
+ ; res_ty <- newInferExpType
; result <- thing_inside (reverse acc_arg_tys ++ more_arg_tys) res_ty
; more_arg_tys <- mapM readExpType more_arg_tys
; res_ty <- readExpType res_ty
@@ -210,15 +210,12 @@ matchExpectedFunTys herald arity orig_ty thing_inside
; return (result, wrap) }
------------
- mk_ctxt :: TidyEnv -> TcM (TidyEnv, MsgDoc)
- mk_ctxt env = do { (env', ty) <- zonkTidyTcType env orig_tc_ty
- ; let (args, _) = tcSplitFunTys ty
- n_actual = length args
- (env'', orig_ty') = tidyOpenType env' orig_tc_ty
- ; return ( env''
- , mk_fun_tys_msg orig_ty' ty n_actual arity herald) }
+ mk_ctxt :: [ExpSigmaType] -> TcType -> TidyEnv -> TcM (TidyEnv, MsgDoc)
+ mk_ctxt arg_tys res_ty env
+ = do { (env', ty) <- zonkTidyTcType env (mkVisFunTys arg_tys' res_ty)
+ ; return ( env', mk_fun_tys_msg herald ty arity) }
where
- orig_tc_ty = checkingExpType "matchExpectedFunTys" orig_ty
+ arg_tys' = map (checkingExpType "matchExpectedFunTys") (reverse arg_tys)
-- this is safe b/c we're called from "go"
-- Like 'matchExpectedFunTys', but used when you have an "actual" type,
@@ -231,22 +228,28 @@ matchActualFunTys :: SDoc -- See Note [Herald for matchExpectedFunTys]
-> TcM (HsWrapper, [TcSigmaType], TcSigmaType)
-- If matchActualFunTys n ty = (wrap, [t1,..,tn], ty_r)
-- then wrap : ty ~> (t1 -> ... -> tn -> ty_r)
-matchActualFunTys herald ct_orig mb_thing arity ty
- = matchActualFunTysPart herald ct_orig mb_thing arity ty [] arity
+matchActualFunTys herald ct_orig mb_thing n_val_args_wanted fun_ty
+ = matchActualFunTysPart herald ct_orig mb_thing
+ n_val_args_wanted []
+ n_val_args_wanted fun_ty
-- | Variant of 'matchActualFunTys' that works when supplied only part
-- (that is, to the right of some arrows) of the full function type
-matchActualFunTysPart :: SDoc -- See Note [Herald for matchExpectedFunTys]
- -> CtOrigin
- -> Maybe (HsExpr GhcRn) -- the thing with type TcSigmaType
- -> Arity
- -> TcSigmaType
- -> [TcSigmaType] -- reversed args. See (*) below.
- -> Arity -- overall arity of the function, for errs
- -> TcM (HsWrapper, [TcSigmaType], TcSigmaType)
-matchActualFunTysPart herald ct_orig mb_thing arity orig_ty
- orig_old_args full_arity
- = go arity orig_old_args orig_ty
+matchActualFunTysPart
+ :: SDoc -- See Note [Herald for matchExpectedFunTys]
+ -> CtOrigin
+ -> Maybe (HsExpr GhcRn) -- The thing with type TcSigmaType
+ -> Arity -- Total number of value args in the call
+ -> [TcSigmaType] -- Types of values args to which function has
+ -- been applied already (reversed)
+ -> Arity -- Number of new value args wanted
+ -> TcSigmaType -- Type to analyse
+ -> TcM (HsWrapper, [TcSigmaType], TcSigmaType)
+-- See Note [matchActualFunTys error handling] for all these arguments
+matchActualFunTysPart herald ct_orig mb_thing
+ n_val_args_in_call arg_tys_so_far
+ n_val_args_wanted fun_ty
+ = go n_val_args_wanted arg_tys_so_far fun_ty
-- Does not allocate unnecessary meta variables: if the input already is
-- a function, we just take it apart. Not only is this efficient,
-- it's important for higher rank: the argument might be of form
@@ -274,36 +277,38 @@ matchActualFunTysPart herald ct_orig mb_thing arity orig_ty
--
-- Refactoring is welcome.
go :: Arity
- -> [TcSigmaType] -- accumulator of arguments (reversed)
+ -> [TcSigmaType] -- Types of value args to which the function has
+ -- been applied so far (reversed)
+ -- Used only for error messages
-> TcSigmaType -- the remainder of the type as we're processing
-> TcM (HsWrapper, [TcSigmaType], TcSigmaType)
go 0 _ ty = return (idHsWrapper, [], ty)
- go n acc_args ty
+ go n so_far ty
| not (null tvs && null theta)
= do { (wrap1, rho) <- topInstantiate ct_orig ty
- ; (wrap2, arg_tys, res_ty) <- go n acc_args rho
+ ; (wrap2, arg_tys, res_ty) <- go n so_far rho
; return (wrap2 <.> wrap1, arg_tys, res_ty) }
where
(tvs, theta, _) = tcSplitSigmaTy ty
- go n acc_args ty
- | Just ty' <- tcView ty = go n acc_args ty'
+ go n so_far ty
+ | Just ty' <- tcView ty = go n so_far ty'
- go n acc_args (FunTy { ft_af = af, ft_arg = arg_ty, ft_res = res_ty })
+ go n so_far (FunTy { ft_af = af, ft_arg = arg_ty, ft_res = res_ty })
= ASSERT( af == VisArg )
- do { (wrap_res, tys, ty_r) <- go (n-1) (arg_ty : acc_args) res_ty
+ do { (wrap_res, tys, ty_r) <- go (n-1) (arg_ty:so_far) res_ty
; return ( mkWpFun idHsWrapper wrap_res arg_ty ty_r doc
, arg_ty : tys, ty_r ) }
where
doc = text "When inferring the argument type of a function with type" <+>
- quotes (ppr orig_ty)
+ quotes (ppr fun_ty)
- go n acc_args ty@(TyVarTy tv)
+ go n so_far ty@(TyVarTy tv)
| isMetaTyVar tv
= do { cts <- readMetaTyVar tv
; case cts of
- Indirect ty' -> go n acc_args ty'
+ Indirect ty' -> go n so_far ty'
Flexi -> defer n ty }
-- In all other cases we bale out into ordinary unification
@@ -321,8 +326,7 @@ matchActualFunTysPart herald ct_orig mb_thing arity orig_ty
--
-- But in that case we add specialized type into error context
-- anyway, because it may be useful. See also #9605.
- go n acc_args ty = addErrCtxtM (mk_ctxt (reverse acc_args) ty) $
- defer n ty
+ go n so_far ty = addErrCtxtM (mk_ctxt so_far ty) (defer n ty)
------------
defer n fun_ty
@@ -333,32 +337,47 @@ matchActualFunTysPart herald ct_orig mb_thing arity orig_ty
; return (mkWpCastN co, arg_tys, res_ty) }
------------
- mk_ctxt :: [TcSigmaType] -> TcSigmaType -> TidyEnv -> TcM (TidyEnv, MsgDoc)
+ mk_ctxt :: [TcType] -> TcType -> TidyEnv -> TcM (TidyEnv, MsgDoc)
mk_ctxt arg_tys res_ty env
- = do { let ty = mkVisFunTys arg_tys res_ty
- ; (env1, zonked) <- zonkTidyTcType env ty
- -- zonking might change # of args
- ; let (zonked_args, _) = tcSplitFunTys zonked
- n_actual = length zonked_args
- (env2, unzonked) = tidyOpenType env1 ty
- ; return ( env2
- , mk_fun_tys_msg unzonked zonked n_actual full_arity herald) }
-
-mk_fun_tys_msg :: TcType -- the full type passed in (unzonked)
- -> TcType -- the full type passed in (zonked)
- -> Arity -- the # of args found
- -> Arity -- the # of args wanted
- -> SDoc -- overall herald
- -> SDoc
-mk_fun_tys_msg full_ty ty n_args full_arity herald
- = herald <+> speakNOf full_arity (text "argument") <> comma $$
- if n_args == full_arity
- then text "its type is" <+> quotes (pprType full_ty) <>
- comma $$
- text "it is specialized to" <+> quotes (pprType ty)
- else sep [text "but its type" <+> quotes (pprType ty),
- if n_args == 0 then text "has none"
- else text "has only" <+> speakN n_args]
+ = do { (env', ty) <- zonkTidyTcType env $
+ mkVisFunTys (reverse arg_tys) res_ty
+ ; return (env', mk_fun_tys_msg herald ty n_val_args_in_call) }
+
+mk_fun_tys_msg :: SDoc -> TcType -> Arity -> SDoc
+mk_fun_tys_msg herald ty n_args_in_call
+ | n_args_in_call <= n_fun_args -- Enough args, in the end
+ = text "In the result of a function call"
+ | otherwise
+ = hang (herald <+> speakNOf n_args_in_call (text "value argument") <> comma)
+ 2 (sep [ text "but its type" <+> quotes (pprType ty)
+ , if n_fun_args == 0 then text "has none"
+ else text "has only" <+> speakN n_fun_args])
+ where
+ (args, _) = tcSplitFunTys ty
+ n_fun_args = length args
+
+{- Note [matchActualFunTys error handling]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+matchActualFunTysPart is made much more complicated by the
+desire to produce good error messages. Consider the application
+ f @Int x y
+In GHC.Tc.Gen.Expr.tcArgs we deal with visible type arguments,
+and then call matchActualFunTysPart for each individual value
+argument. It, in turn, must instantiate any type/dictionary args,
+before looking for an arrow type.
+
+But if it doesn't find an arrow type, it wants to generate a message
+like "f is applied to two arguments but its type only has one".
+To do that, it needs to konw about the args that tcArgs has already
+munched up -- hence passing in n_val_args_in_call and arg_tys_so_far;
+and hence also the accumulating so_far arg to 'go'.
+
+This allows us (in mk_ctxt) to construct f's /instantiated/ type,
+with just the values-arg arrows, which is what we really want
+in the error message.
+
+Ugh!
+-}
----------------------
matchExpectedListTy :: TcRhoType -> TcM (TcCoercionN, TcRhoType)
@@ -550,11 +569,11 @@ tcSubTypeHR :: CtOrigin -- ^ of the actual type
tcSubTypeHR orig = tcSubTypeDS_NC_O orig GenSigCtxt
------------------------
-tcSubTypeET :: CtOrigin -> UserTypeCtxt
+tcSubTypePat :: CtOrigin -> UserTypeCtxt
-> ExpSigmaType -> TcSigmaType -> TcM HsWrapper
-- If wrap = tc_sub_type_et t1 t2
-- => wrap :: t1 ~> t2
-tcSubTypeET orig ctxt (Check ty_actual) ty_expected
+tcSubTypePat orig ctxt (Check ty_actual) ty_expected
= tc_sub_tc_type eq_orig orig ctxt ty_actual ty_expected
where
eq_orig = TypeEqOrigin { uo_actual = ty_expected
@@ -562,14 +581,9 @@ tcSubTypeET orig ctxt (Check ty_actual) ty_expected
, uo_thing = Nothing
, uo_visible = True }
-tcSubTypeET _ _ (Infer inf_res) ty_expected
- = ASSERT2( not (ir_inst inf_res), ppr inf_res $$ ppr ty_expected )
- -- An (Infer inf_res) ExpSigmaType passed into tcSubTypeET never
- -- has the ir_inst field set. Reason: in patterns (which is what
- -- tcSubTypeET is used for) do not aggressively instantiate
- do { co <- fill_infer_result ty_expected inf_res
- -- Since ir_inst is false, we can skip fillInferResult
- -- and go straight to fill_infer_result
+tcSubTypePat _ _ (Infer inf_res) ty_expected
+ = do { co <- fillInferResult ty_expected inf_res
+ -- In patterns we do not instantatiate
; return (mkWpCastN (mkTcSymCo co)) }
@@ -643,7 +657,7 @@ tcSubTypeDS_NC_O :: CtOrigin -- origin used for instantiation only
-- ty_expected is deeply skolemised
tcSubTypeDS_NC_O inst_orig ctxt m_thing ty_actual ty_expected
= case ty_expected of
- Infer inf_res -> fillInferResult inst_orig ty_actual inf_res
+ Infer inf_res -> instantiateAndFillInferResult inst_orig ty_actual inf_res
Check ty -> tc_sub_type_ds eq_orig inst_orig ctxt ty_actual ty
where
eq_orig = TypeEqOrigin { uo_actual = ty_actual, uo_expected = ty
@@ -864,44 +878,32 @@ tcWrapResultO orig rn_expr expr actual_ty res_ty
{- **********************************************************************
%* *
- ExpType functions: tcInfer, fillInferResult
+ ExpType functions: tcInfer, instantiateAndFillInferResult
%* *
%********************************************************************* -}
-- | Infer a type using a fresh ExpType
-- See also Note [ExpType] in GHC.Tc.Utils.TcMType
--- Does not attempt to instantiate the inferred type
-tcInferNoInst :: (ExpSigmaType -> TcM a) -> TcM (a, TcSigmaType)
-tcInferNoInst = tcInfer False
-
-tcInferInst :: (ExpRhoType -> TcM a) -> TcM (a, TcRhoType)
-tcInferInst = tcInfer True
-
-tcInfer :: Bool -> (ExpSigmaType -> TcM a) -> TcM (a, TcSigmaType)
-tcInfer instantiate tc_check
- = do { res_ty <- newInferExpType instantiate
+tcInfer :: (ExpSigmaType -> TcM a) -> TcM (a, TcSigmaType)
+tcInfer tc_check
+ = do { res_ty <- newInferExpType
; result <- tc_check res_ty
; res_ty <- readExpType res_ty
; return (result, res_ty) }
-fillInferResult :: CtOrigin -> TcType -> InferResult -> TcM HsWrapper
--- If wrap = fillInferResult t1 t2
+instantiateAndFillInferResult :: CtOrigin -> TcType -> InferResult -> TcM HsWrapper
+-- If wrap = instantiateAndFillInferResult t1 t2
-- => wrap :: t1 ~> t2
--- See Note [Deep instantiation of InferResult]
-fillInferResult orig ty inf_res@(IR { ir_inst = instantiate_me })
- | instantiate_me
+-- See Note [Instantiation of InferResult]
+instantiateAndFillInferResult orig ty inf_res
= do { (wrap, rho) <- deeplyInstantiate orig ty
- ; co <- fill_infer_result rho inf_res
+ ; co <- fillInferResult rho inf_res
; return (mkWpCastN co <.> wrap) }
- | otherwise
- = do { co <- fill_infer_result ty inf_res
- ; return (mkWpCastN co) }
-
-fill_infer_result :: TcType -> InferResult -> TcM TcCoercionN
--- If wrap = fill_infer_result t1 t2
+fillInferResult :: TcType -> InferResult -> TcM TcCoercionN
+-- If wrap = fillInferResult t1 t2
-- => wrap :: t1 ~> t2
-fill_infer_result orig_ty (IR { ir_uniq = u, ir_lvl = res_lvl
+fillInferResult orig_ty (IR { ir_uniq = u, ir_lvl = res_lvl
, ir_ref = ref })
= do { (ty_co, ty_to_fill_with) <- promoteTcType res_lvl orig_ty
@@ -927,14 +929,12 @@ fill_infer_result orig_ty (IR { ir_uniq = u, ir_lvl = res_lvl
, ppr already_there ])
Nothing -> return () }
-{- Note [Deep instantiation of InferResult]
+{- Note [Instantiation of InferResult]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-In some cases we want to deeply instantiate before filling in
-an InferResult, and in some cases not. That's why InferReult
-has the ir_inst flag.
+We now always instantiate before filling in InferResult, so that
+the result is a TcRhoType: see #17173 for discussion.
-ir_inst = True: deeply instantiate
-----------------------------------
+For example:
1. Consider
f x = (*)
@@ -954,41 +954,16 @@ ir_inst = True: deeply instantiate
Here want to instantiate f's type so that the ?x::Int constraint
gets discharged by the enclosing implicit-parameter binding.
-ir_inst = False: do not instantiate
------------------------------------
-
-1. Consider this (which uses visible type application):
-
- (let { f :: forall a. a -> a; f x = x } in f) @Int
-
- We'll call GHC.Tc.Gen.Expr.tcInferFun to infer the type of the (let .. in f)
- And we don't want to instantiate the type of 'f' when we reach it,
- else the outer visible type application won't work
-
-2. :type +v. When we say
-
- :type +v const @Int
+3. Suppose one defines plus = (+). If we instantiate lazily, we will
+ infer plus :: forall a. Num a => a -> a -> a. However, the monomorphism
+ restriction compels us to infer
+ plus :: Integer -> Integer -> Integer
+ (or similar monotype). Indeed, the only way to know whether to apply
+ the monomorphism restriction at all is to instantiate
- we really want `forall b. Int -> b -> Int`. Note that this is *not*
- instantiated.
-
-3. Pattern bindings. For example:
-
- foo x
- | blah <- const @Int
- = (blah x False, blah x 'z')
-
- Note that `blah` is polymorphic. (This isn't a terribly compelling
- reason, but the choice of ir_inst does matter here.)
-
-Discussion
-----------
-We thought that we should just remove the ir_inst flag, in favor of
-always instantiating. Essentially: motivations (1) and (3) for ir_inst = False
-are not terribly exciting. However, motivation (2) is quite important.
-Furthermore, there really was not much of a simplification of the code
-in removing ir_inst, and working around it to enable flows like what we
-see in (2) is annoying. This was done in #17173.
+There is one place where we don't want to instantiate eagerly,
+namely in GHC.Tc.Module.tcRnExpr, which implements GHCi's :type
+command. See Note [Implementing :type] in GHC.Tc.Module.
-}
@@ -1187,8 +1162,8 @@ checkConstraints skol_info skol_tvs given thing_inside
; emitImplications implics
; return (ev_binds, result) }
- else -- Fast path. We check every function argument with
- -- tcPolyExpr, which uses tcSkolemise and hence checkConstraints.
+ else -- Fast path. We check every function argument with tcCheckExpr,
+ -- which uses tcSkolemise and hence checkConstraints.
-- So this fast path is well-exercised
do { res <- thing_inside
; return (emptyTcEvBinds, res) } }
diff --git a/compiler/GHC/Tc/Utils/Zonk.hs b/compiler/GHC/Tc/Utils/Zonk.hs
index 4cf02d41e0..00f11c09ae 100644
--- a/compiler/GHC/Tc/Utils/Zonk.hs
+++ b/compiler/GHC/Tc/Utils/Zonk.hs
@@ -754,9 +754,10 @@ zonkExpr env (HsApp x e1 e2)
new_e2 <- zonkLExpr env e2
return (HsApp x new_e1 new_e2)
-zonkExpr env (HsAppType x e t)
+zonkExpr env (HsAppType ty e t)
= do new_e <- zonkLExpr env e
- return (HsAppType x new_e t)
+ new_ty <- zonkTcTypeToTypeX env ty
+ return (HsAppType new_ty new_e t)
-- NB: the type is an HsType; can't zonk that!
zonkExpr _ e@(HsRnBracketOut _ _ _)
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