X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FInst.lhs;h=5c6d8fe4dbe029bdbe0c5cfb2ffc5aea635f2920;hp=417e88aa42d0eeab3c9609fa1e51cc780ffb43ec;hb=940524aec90652b5ef81789c9a453c57c0e42cc9;hpb=ac704fcac946590eef0ec91ae19f3b47d779a75f diff --git a/compiler/typecheck/Inst.lhs b/compiler/typecheck/Inst.lhs index 417e88a..5c6d8fe 100644 --- a/compiler/typecheck/Inst.lhs +++ b/compiler/typecheck/Inst.lhs @@ -17,26 +17,26 @@ module Inst ( newDictBndr, newDictBndrs, newDictBndrsO, instCall, instStupidTheta, cloneDict, - shortCutFracLit, shortCutIntLit, newIPDict, + shortCutFracLit, shortCutIntLit, shortCutStringLit, newIPDict, newMethod, newMethodFromName, newMethodWithGivenTy, tcInstClassOp, tcSyntaxName, isHsVar, tyVarsOfInst, tyVarsOfInsts, tyVarsOfLIE, ipNamesOfInst, ipNamesOfInsts, fdPredsOfInst, fdPredsOfInsts, - instLoc, getDictClassTys, dictPred, + getDictClassTys, dictPred, - lookupInst, LookupInstResult(..), lookupPred, + lookupSimpleInst, LookupInstResult(..), tcExtendLocalInstEnv, tcGetInstEnvs, getOverlapFlag, - isDict, isClassDict, isMethod, - isIPDict, isInheritableInst, - isTyVarDict, isMethodFor, + isDict, isClassDict, isMethod, isImplicInst, + isIPDict, isInheritableInst, isMethodOrLit, + isTyVarDict, isMethodFor, getDefaultableDicts, zonkInst, zonkInsts, instToId, instToVar, instName, - InstOrigin(..), InstLoc(..), pprInstLoc + InstOrigin(..), InstLoc, pprInstLoc ) where #include "HsVersions.h" @@ -44,6 +44,7 @@ module Inst ( import {-# SOURCE #-} TcExpr( tcPolyExpr ) import {-# SOURCE #-} TcUnify( unifyType ) +import FastString(FastString) import HsSyn import TcHsSyn import TcRnMonad @@ -53,6 +54,7 @@ import FunDeps import TcMType import TcType import Type +import Class import Unify import Module import Coercion @@ -73,6 +75,7 @@ import BasicTypes import SrcLoc import DynFlags import Maybes +import Util import Outputable \end{code} @@ -81,7 +84,7 @@ Selection ~~~~~~~~~ \begin{code} instName :: Inst -> Name -instName inst = idName (instToId inst) +instName inst = Var.varName (instToVar inst) instToId :: Inst -> TcId instToId inst = ASSERT2( isId id, ppr inst ) id @@ -96,8 +99,26 @@ instToVar (Method {tci_id = id}) instToVar (Dict {tci_name = nm, tci_pred = pred}) | isEqPred pred = Var.mkCoVar nm (mkPredTy pred) | otherwise = mkLocalId nm (mkPredTy pred) - -instLoc inst = tci_loc inst +instToVar (ImplicInst {tci_name = nm, tci_tyvars = tvs, tci_given = givens, + tci_wanted = wanteds}) + = mkLocalId nm (mkImplicTy tvs givens wanteds) + +instType :: Inst -> Type +instType (LitInst {tci_ty = ty}) = ty +instType (Method {tci_id = id}) = idType id +instType (Dict {tci_pred = pred}) = mkPredTy pred +instType imp@(ImplicInst {}) = mkImplicTy (tci_tyvars imp) (tci_given imp) + (tci_wanted imp) + +mkImplicTy tvs givens wanteds -- The type of an implication constraint + = ASSERT( all isDict givens ) + -- pprTrace "mkImplicTy" (ppr givens) $ + mkForAllTys tvs $ + mkPhiTy (map dictPred givens) $ + if isSingleton wanteds then + instType (head wanteds) + else + mkTupleTy Boxed (length wanteds) (map instType wanteds) dictPred (Dict {tci_pred = pred}) = pred dictPred inst = pprPanic "dictPred" (ppr inst) @@ -111,9 +132,11 @@ getDictClassTys inst = pprPanic "getDictClassTys" (ppr inst) -- Leaving these in is really important for the call to fdPredsOfInsts -- in TcSimplify.inferLoop, because the result is fed to 'grow', -- which is supposed to be conservative -fdPredsOfInst (Dict {tci_pred = pred}) = [pred] -fdPredsOfInst (Method {tci_theta = theta}) = theta -fdPredsOfInst other = [] -- LitInsts etc +fdPredsOfInst (Dict {tci_pred = pred}) = [pred] +fdPredsOfInst (Method {tci_theta = theta}) = theta +fdPredsOfInst (ImplicInst {tci_given = gs, + tci_wanted = ws}) = fdPredsOfInsts (gs ++ ws) +fdPredsOfInst (LitInst {}) = [] fdPredsOfInsts :: [Inst] -> [PredType] fdPredsOfInsts insts = concatMap fdPredsOfInst insts @@ -123,23 +146,30 @@ isInheritableInst (Method {tci_theta = theta}) = all isInheritablePred theta isInheritableInst other = True +--------------------------------- +-- Get the implicit parameters mentioned by these Insts +-- NB: the results of these functions are insensitive to zonking + ipNamesOfInsts :: [Inst] -> [Name] ipNamesOfInst :: Inst -> [Name] --- Get the implicit parameters mentioned by these Insts --- NB: ?x and %x get different Names ipNamesOfInsts insts = [n | inst <- insts, n <- ipNamesOfInst inst] ipNamesOfInst (Dict {tci_pred = IParam n _}) = [ipNameName n] ipNamesOfInst (Method {tci_theta = theta}) = [ipNameName n | IParam n _ <- theta] ipNamesOfInst other = [] +--------------------------------- tyVarsOfInst :: Inst -> TcTyVarSet tyVarsOfInst (LitInst {tci_ty = ty}) = tyVarsOfType ty tyVarsOfInst (Dict {tci_pred = pred}) = tyVarsOfPred pred -tyVarsOfInst (Method {tci_oid = id, tci_tys = tys}) = tyVarsOfTypes tys `unionVarSet` idFreeTyVars id +tyVarsOfInst (Method {tci_oid = id, tci_tys = tys}) = tyVarsOfTypes tys `unionVarSet` varTypeTyVars id -- The id might have free type variables; in the case of -- locally-overloaded class methods, for example - +tyVarsOfInst (ImplicInst {tci_tyvars = tvs, tci_given = givens, tci_wanted = wanteds}) + = (tyVarsOfInsts givens `unionVarSet` tyVarsOfInsts wanteds) + `minusVarSet` mkVarSet tvs + `unionVarSet` unionVarSets (map varTypeTyVars tvs) + -- Remember the free tyvars of a coercion tyVarsOfInsts insts = foldr (unionVarSet . tyVarsOfInst) emptyVarSet insts tyVarsOfLIE lie = tyVarsOfInsts (lieToList lie) @@ -164,6 +194,9 @@ isIPDict :: Inst -> Bool isIPDict (Dict {tci_pred = pred}) = isIPPred pred isIPDict other = False +isImplicInst (ImplicInst {}) = True +isImplicInst other = False + isMethod :: Inst -> Bool isMethod (Method {}) = True isMethod other = False @@ -171,9 +204,33 @@ isMethod other = False isMethodFor :: TcIdSet -> Inst -> Bool isMethodFor ids (Method {tci_oid = id}) = id `elemVarSet` ids isMethodFor ids inst = False -\end{code} +isMethodOrLit :: Inst -> Bool +isMethodOrLit (Method {}) = True +isMethodOrLit (LitInst {}) = True +isMethodOrLit other = False +\end{code} +\begin{code} +getDefaultableDicts :: [Inst] -> ([(Inst, Class, TcTyVar)], TcTyVarSet) +-- Look for free dicts of the form (C tv), even inside implications +-- *and* the set of tyvars mentioned by all *other* constaints +-- This disgustingly ad-hoc function is solely to support defaulting +getDefaultableDicts insts + = (concat ps, unionVarSets tvs) + where + (ps, tvs) = mapAndUnzip get insts + get d@(Dict {tci_pred = ClassP cls [ty]}) + | Just tv <- tcGetTyVar_maybe ty = ([(d,cls,tv)], emptyVarSet) + | otherwise = ([], tyVarsOfType ty) + get (ImplicInst {tci_tyvars = tvs, tci_wanted = wanteds}) + = ([ up | up@(_,_,tv) <- ups, not (tv `elemVarSet` tv_set)], + ftvs `minusVarSet` tv_set) + where + tv_set = mkVarSet tvs + (ups, ftvs) = getDefaultableDicts wanteds + get inst = ([], tyVarsOfInst inst) +\end{code} %************************************************************************ %* * @@ -197,7 +254,7 @@ newDictBndrs inst_loc theta = mapM (newDictBndr inst_loc) theta newDictBndr :: InstLoc -> TcPredType -> TcM Inst newDictBndr inst_loc pred = do { uniq <- newUnique - ; let name = mkPredName uniq (instLocSrcLoc inst_loc) pred + ; let name = mkPredName uniq inst_loc pred ; return (Dict {tci_name = name, tci_pred = pred, tci_loc = inst_loc}) } ---------------- @@ -240,7 +297,7 @@ instCallDicts loc (EqPred ty1 ty2 : preds) instCallDicts loc (pred : preds) = do { uniq <- newUnique - ; let name = mkPredName uniq (instLocSrcLoc loc) pred + ; let name = mkPredName uniq loc pred dict = Dict {tci_name = name, tci_pred = pred, tci_loc = loc} ; (dicts, co_fn) <- instCallDicts loc preds ; return (dict:dicts, co_fn <.> WpApp (instToId dict)) } @@ -262,13 +319,29 @@ newIPDict orig ip_name ty newUnique `thenM` \ uniq -> let pred = IParam ip_name ty - name = mkPredName uniq (instLocSrcLoc inst_loc) pred + name = mkPredName uniq inst_loc pred dict = Dict {tci_name = name, tci_pred = pred, tci_loc = inst_loc} in returnM (mapIPName (\n -> instToId dict) ip_name, dict) \end{code} +\begin{code} +mkPredName :: Unique -> InstLoc -> PredType -> Name +mkPredName uniq loc pred_ty + = mkInternalName uniq occ (instLocSpan loc) + where + occ = case pred_ty of + ClassP cls _ -> mkDictOcc (getOccName cls) + IParam ip _ -> getOccName (ipNameName ip) + EqPred ty _ -> mkEqPredCoOcc baseOcc + where + -- we use the outermost tycon of the lhs, if there is one, to + -- improve readability of Core code + baseOcc = case splitTyConApp_maybe ty of + Nothing -> mkOccName tcName "$" + Just (tc, _) -> getOccName tc +\end{code} %************************************************************************ %* * @@ -340,7 +413,7 @@ newMethod inst_loc id tys meth_id = mkUserLocal (mkMethodOcc (getOccName id)) new_uniq tau loc inst = Method {tci_id = meth_id, tci_oid = id, tci_tys = tys, tci_theta = theta, tci_loc = inst_loc} - loc = instLocSrcLoc inst_loc + loc = instLocSpan inst_loc in returnM inst \end{code} @@ -364,6 +437,12 @@ shortCutFracLit f ty where mk_lit con lit = HsApp (nlHsVar (dataConWrapId con)) (nlHsLit lit) +shortCutStringLit :: FastString -> TcType -> Maybe (HsExpr TcId) +shortCutStringLit s ty + | isStringTy ty -- Short cut for String + = Just (HsLit (HsString s)) + | otherwise = Nothing + mkIntegerLit :: Integer -> TcM (LHsExpr TcId) mkIntegerLit i = tcMetaTy integerTyConName `thenM` \ integer_ty -> @@ -376,6 +455,12 @@ mkRatLit r getSrcSpanM `thenM` \ span -> returnM (L span $ HsLit (HsRat r rat_ty)) +mkStrLit :: FastString -> TcM (LHsExpr TcId) +mkStrLit s + = --tcMetaTy stringTyConName `thenM` \ string_ty -> + getSrcSpanM `thenM` \ span -> + returnM (L span $ HsLit (HsString s)) + isHsVar :: HsExpr Name -> Name -> Bool isHsVar (HsVar f) g = f==g isHsVar other g = False @@ -411,6 +496,12 @@ zonkInst lit@(LitInst {tci_ty = ty}) = zonkTcType ty `thenM` \ new_ty -> returnM (lit {tci_ty = new_ty}) +zonkInst implic@(ImplicInst {}) + = ASSERT( all isImmutableTyVar (tci_tyvars implic) ) + do { givens' <- zonkInsts (tci_given implic) + ; wanteds' <- zonkInsts (tci_wanted implic) + ; return (implic {tci_given = givens',tci_wanted = wanteds'}) } + zonkInsts insts = mappM zonkInst insts \end{code} @@ -430,36 +521,41 @@ instance Outputable Inst where pprDictsTheta :: [Inst] -> SDoc -- Print in type-like fashion (Eq a, Show b) -pprDictsTheta dicts = pprTheta (map dictPred dicts) +-- The Inst can be an implication constraint, but not a Method or LitInst +pprDictsTheta insts = parens (sep (punctuate comma (map (ppr . instType) insts))) pprDictsInFull :: [Inst] -> SDoc -- Print in type-like fashion, but with source location pprDictsInFull dicts = vcat (map go dicts) where - go dict = sep [quotes (ppr (dictPred dict)), nest 2 (pprInstLoc (instLoc dict))] + go dict = sep [quotes (ppr (instType dict)), nest 2 (pprInstArising dict)] pprInsts :: [Inst] -> SDoc -- Debugging: print the evidence :: type -pprInsts insts = brackets (interpp'SP insts) +pprInsts insts = brackets (interpp'SP insts) pprInst, pprInstInFull :: Inst -> SDoc -- Debugging: print the evidence :: type -pprInst (LitInst {tci_name = nm, tci_ty = ty}) = ppr nm <+> dcolon <+> ppr ty -pprInst (Dict {tci_name = nm, tci_pred = pred}) = ppr nm <+> dcolon <+> pprPred pred - -pprInst (Method {tci_id = inst_id, tci_oid = id, tci_tys = tys}) - = ppr inst_id <+> dcolon <+> - braces (sep [ppr id <+> ptext SLIT("at"), - brackets (sep (map pprParendType tys))]) +pprInst inst = ppr (instName inst) <+> dcolon + <+> (braces (ppr (instType inst)) $$ + ifPprDebug implic_stuff) + where + implic_stuff | isImplicInst inst = ppr (tci_reft inst) + | otherwise = empty -pprInstInFull inst - = sep [quotes (pprInst inst), nest 2 (pprInstLoc (instLoc inst))] +pprInstInFull inst = sep [quotes (pprInst inst), nest 2 (pprInstArising inst)] tidyInst :: TidyEnv -> Inst -> Inst tidyInst env lit@(LitInst {tci_ty = ty}) = lit {tci_ty = tidyType env ty} tidyInst env dict@(Dict {tci_pred = pred}) = dict {tci_pred = tidyPred env pred} tidyInst env meth@(Method {tci_tys = tys}) = meth {tci_tys = tidyTypes env tys} +tidyInst env implic@(ImplicInst {}) + = implic { tci_tyvars = tvs' + , tci_given = map (tidyInst env') (tci_given implic) + , tci_wanted = map (tidyInst env') (tci_wanted implic) } + where + (env', tvs') = mapAccumL tidyTyVarBndr env (tci_tyvars implic) tidyMoreInsts :: TidyEnv -> [Inst] -> (TidyEnv, [Inst]) -- This function doesn't assume that the tyvars are in scope @@ -509,7 +605,7 @@ addLocalInst home_ie ispec -- We use tcInstSkolType because we don't want to allocate fresh -- *meta* type variables. let dfun = instanceDFunId ispec - ; (tvs', theta', tau') <- tcInstSkolType (InstSkol dfun) (idType dfun) + ; (tvs', theta', tau') <- tcInstSkolType InstSkol (idType dfun) ; let (cls, tys') = tcSplitDFunHead tau' dfun' = setIdType dfun (mkSigmaTy tvs' theta' tau') ispec' = setInstanceDFunId ispec dfun' @@ -527,7 +623,7 @@ addLocalInst home_ie ispec -- Check for duplicate instance decls ; let { (matches, _) = lookupInstEnv inst_envs cls tys' ; dup_ispecs = [ dup_ispec - | (_, dup_ispec) <- matches + | (dup_ispec, _) <- matches , let (_,_,_,dup_tys) = instanceHead dup_ispec , isJust (tcMatchTys (mkVarSet tvs') tys' dup_tys)] } -- Find memebers of the match list which ispec itself matches. @@ -581,46 +677,46 @@ addDictLoc ispec thing_inside \begin{code} data LookupInstResult = NoInstance - | SimpleInst (LHsExpr TcId) -- Just a variable, type application, or literal - | GenInst [Inst] (LHsExpr TcId) -- The expression and its needed insts + | GenInst [Inst] (LHsExpr TcId) -- The expression and its needed insts + +lookupSimpleInst :: Inst -> TcM LookupInstResult +-- This is "simple" in tthat it returns NoInstance for implication constraints -lookupInst :: Inst -> TcM LookupInstResult -- It's important that lookupInst does not put any new stuff into -- the LIE. Instead, any Insts needed by the lookup are returned in -- the LookupInstResult, where they can be further processed by tcSimplify +--------------------- Implications ------------------------ +lookupSimpleInst (ImplicInst {}) = return NoInstance --- Methods - -lookupInst (Method {tci_oid = id, tci_tys = tys, tci_theta = theta, tci_loc = loc}) +--------------------- Methods ------------------------ +lookupSimpleInst (Method {tci_oid = id, tci_tys = tys, tci_theta = theta, tci_loc = loc}) = do { (dicts, dict_app) <- instCallDicts loc theta ; let co_fn = dict_app <.> mkWpTyApps tys ; return (GenInst dicts (L span $ HsWrap co_fn (HsVar id))) } where - span = instLocSrcSpan loc - --- Literals + span = instLocSpan loc +--------------------- Literals ------------------------ -- Look for short cuts first: if the literal is *definitely* a -- int, integer, float or a double, generate the real thing here. -- This is essential (see nofib/spectral/nucleic). -- [Same shortcut as in newOverloadedLit, but we -- may have done some unification by now] -lookupInst (LitInst {tci_lit = HsIntegral i from_integer_name, tci_ty = ty, tci_loc = loc}) +lookupSimpleInst (LitInst {tci_lit = HsIntegral i from_integer_name, tci_ty = ty, tci_loc = loc}) | Just expr <- shortCutIntLit i ty - = returnM (GenInst [] (noLoc expr)) -- GenInst, not SimpleInst, because - -- expr may be a constructor application + = returnM (GenInst [] (noLoc expr)) | otherwise = ASSERT( from_integer_name `isHsVar` fromIntegerName ) -- A LitInst invariant tcLookupId fromIntegerName `thenM` \ from_integer -> tcInstClassOp loc from_integer [ty] `thenM` \ method_inst -> mkIntegerLit i `thenM` \ integer_lit -> returnM (GenInst [method_inst] - (mkHsApp (L (instLocSrcSpan loc) + (mkHsApp (L (instLocSpan loc) (HsVar (instToId method_inst))) integer_lit)) -lookupInst (LitInst {tci_lit = HsFractional f from_rat_name, tci_ty = ty, tci_loc = loc}) +lookupSimpleInst (LitInst {tci_lit = HsFractional f from_rat_name, tci_ty = ty, tci_loc = loc}) | Just expr <- shortCutFracLit f ty = returnM (GenInst [] (noLoc expr)) @@ -629,27 +725,28 @@ lookupInst (LitInst {tci_lit = HsFractional f from_rat_name, tci_ty = ty, tci_lo tcLookupId fromRationalName `thenM` \ from_rational -> tcInstClassOp loc from_rational [ty] `thenM` \ method_inst -> mkRatLit f `thenM` \ rat_lit -> - returnM (GenInst [method_inst] (mkHsApp (L (instLocSrcSpan loc) + returnM (GenInst [method_inst] (mkHsApp (L (instLocSpan loc) (HsVar (instToId method_inst))) rat_lit)) --- Dictionaries -lookupInst (Dict {tci_pred = pred, tci_loc = loc}) +lookupSimpleInst (LitInst {tci_lit = HsIsString s from_string_name, tci_ty = ty, tci_loc = loc}) + | Just expr <- shortCutStringLit s ty + = returnM (GenInst [] (noLoc expr)) + | otherwise + = ASSERT( from_string_name `isHsVar` fromStringName ) -- A LitInst invariant + tcLookupId fromStringName `thenM` \ from_string -> + tcInstClassOp loc from_string [ty] `thenM` \ method_inst -> + mkStrLit s `thenM` \ string_lit -> + returnM (GenInst [method_inst] + (mkHsApp (L (instLocSpan loc) + (HsVar (instToId method_inst))) string_lit)) + +--------------------- Dictionaries ------------------------ +lookupSimpleInst (Dict {tci_pred = pred, tci_loc = loc}) = do { mb_result <- lookupPred pred ; case mb_result of { Nothing -> return NoInstance ; - Just (tenv, dfun_id) -> do - - -- tenv is a substitution that instantiates the dfun_id - -- to match the requested result type. - -- - -- We ASSUME that the dfun is quantified over the very same tyvars - -- that are bound by the tenv. - -- - -- However, the dfun - -- might have some tyvars that *only* appear in arguments - -- dfun :: forall a b. C a b, Ord b => D [a] - -- We instantiate b to a flexi type variable -- it'll presumably - -- become fixed later via functional dependencies + Just (dfun_id, mb_inst_tys) -> do + { use_stage <- getStage ; checkWellStaged (ptext SLIT("instance for") <+> quotes (ppr pred)) (topIdLvl dfun_id) use_stage @@ -658,21 +755,17 @@ lookupInst (Dict {tci_pred = pred, tci_loc = loc}) -- the substitution, tenv. For example: -- instance C X a => D X where ... -- (presumably there's a functional dependency in class C) - -- Hence the open_tvs to instantiate any un-substituted tyvars. - ; let (tyvars, rho) = tcSplitForAllTys (idType dfun_id) - open_tvs = filter (`notElemTvSubst` tenv) tyvars - ; open_tvs' <- mappM tcInstTyVar open_tvs + -- Hence mb_inst_tys :: Either TyVar TcType + + ; let inst_tv (Left tv) = do { tv' <- tcInstTyVar tv; return (mkTyVarTy tv') } + inst_tv (Right ty) = return ty + ; tys <- mappM inst_tv mb_inst_tys ; let - tenv' = extendTvSubstList tenv open_tvs (mkTyVarTys open_tvs') - -- Since the open_tvs' are freshly made, they cannot possibly be captured by - -- any nested for-alls in rho. So the in-scope set is unchanged - dfun_rho = substTy tenv' rho - (theta, _) = tcSplitPhiTy dfun_rho - src_loc = instLocSrcSpan loc + (theta, _) = tcSplitPhiTy (applyTys (idType dfun_id) tys) + src_loc = instLocSpan loc dfun = HsVar dfun_id - tys = map (substTyVar tenv') tyvars ; if null theta then - returnM (SimpleInst (L src_loc $ HsWrap (mkWpTyApps tys) dfun)) + returnM (GenInst [] (L src_loc $ HsWrap (mkWpTyApps tys) dfun)) else do { (dicts, dict_app) <- instCallDicts loc theta ; let co_fn = dict_app <.> mkWpTyApps tys @@ -680,14 +773,14 @@ lookupInst (Dict {tci_pred = pred, tci_loc = loc}) }}}} --------------- -lookupPred :: TcPredType -> TcM (Maybe (TvSubst, DFunId)) +lookupPred :: TcPredType -> TcM (Maybe (DFunId, [Either TyVar TcType])) -- Look up a class constraint in the instance environment lookupPred pred@(ClassP clas tys) = do { eps <- getEps ; tcg_env <- getGblEnv ; let inst_envs = (eps_inst_env eps, tcg_inst_env tcg_env) ; case lookupInstEnv inst_envs clas tys of { - ([(tenv, ispec)], []) + ([(ispec, inst_tys)], []) -> do { let dfun_id = is_dfun ispec ; traceTc (text "lookupInst success" <+> vcat [text "dict" <+> ppr pred, @@ -695,7 +788,7 @@ lookupPred pred@(ClassP clas tys) <+> ppr (idType dfun_id) ]) -- Record that this dfun is needed ; record_dfun_usage dfun_id - ; return (Just (tenv, dfun_id)) } ; + ; return (Just (dfun_id, inst_tys)) } ; (matches, unifs) -> do { traceTc (text "lookupInst fail" <+> @@ -710,7 +803,7 @@ lookupPred pred@(ClassP clas tys) ; return Nothing } }} -lookupPred ip_pred = return Nothing +lookupPred ip_pred = return Nothing -- Implicit parameters record_dfun_usage dfun_id = do { hsc_env <- getTopEnv @@ -799,7 +892,7 @@ syntaxNameCtxt name orig ty tidy_env msg = vcat [ptext SLIT("When checking that") <+> quotes (ppr name) <+> ptext SLIT("(needed by a syntactic construct)"), nest 2 (ptext SLIT("has the required type:") <+> ppr (tidyType tidy_env ty)), - nest 2 (pprInstLoc inst_loc)] + nest 2 (ptext SLIT("arising from") <+> pprInstLoc inst_loc)] in returnM (tidy_env, msg) \end{code}