X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2FcoreSyn%2FCoreLint.lhs;h=59c52da46a6f691e1082163a6dbf9bf86b3f6313;hb=8100cd4395e46ae747be4298c181a4730d6206bc;hp=dda8290bf4c62702f009a1511ba40290edc46a22;hpb=0065d5ab628975892cea1ec7303f968c3338cbe1;p=ghc-hetmet.git diff --git a/compiler/coreSyn/CoreLint.lhs b/compiler/coreSyn/CoreLint.lhs index dda8290..59c52da 100644 --- a/compiler/coreSyn/CoreLint.lhs +++ b/compiler/coreSyn/CoreLint.lhs @@ -1,7 +1,9 @@ % +% (c) The University of Glasgow 2006 % (c) The GRASP/AQUA Project, Glasgow University, 1993-1998 % -\section[CoreLint]{A ``lint'' pass to check for Core correctness} + +A ``lint'' pass to check for Core correctness \begin{code} module CoreLint ( @@ -13,41 +15,32 @@ module CoreLint ( #include "HsVersions.h" import CoreSyn -import CoreFVs ( idFreeVars ) -import CoreUtils ( findDefault, exprOkForSpeculation, coreBindsSize ) -import Unify ( coreRefineTys ) +import CoreFVs +import CoreUtils import Bag -import Literal ( literalType ) -import DataCon ( dataConRepType, isVanillaDataCon, dataConTyCon, dataConWorkId ) -import TysWiredIn ( tupleCon ) -import Var ( Var, Id, TyVar, idType, tyVarKind, mustHaveLocalBinding ) +import Literal +import DataCon +import TysWiredIn +import Var +import VarEnv import VarSet -import Name ( getSrcLoc ) +import Name import PprCore -import ErrUtils ( dumpIfSet_core, ghcExit, Message, showPass, - mkLocMessage, debugTraceMsg ) -import SrcLoc ( SrcLoc, noSrcLoc, mkSrcSpan ) -import Type ( Type, tyVarsOfType, coreEqType, - splitFunTy_maybe, mkTyVarTys, - splitForAllTy_maybe, splitTyConApp_maybe, - isUnLiftedType, typeKind, mkForAllTy, mkFunTy, - isUnboxedTupleType, isSubKind, - substTyWith, emptyTvSubst, extendTvInScope, - TvSubst, TvSubstEnv, mkTvSubst, setTvSubstEnv, substTy, - extendTvSubst, composeTvSubst, isInScope, - getTvSubstEnv, getTvInScope ) -import TyCon ( isPrimTyCon ) -import BasicTypes ( RecFlag(..), Boxity(..), isNonRec ) -import StaticFlags ( opt_PprStyle_Debug ) -import DynFlags ( DynFlags, DynFlag(..), dopt ) +import ErrUtils +import SrcLoc +import Type +import Coercion +import TyCon +import BasicTypes +import StaticFlags +import DynFlags import Outputable #ifdef DEBUG import Util ( notNull ) #endif -import Maybe - +import Data.Maybe \end{code} %************************************************************************ @@ -109,6 +102,60 @@ Outstanding issues: -- * Oversaturated type app after specialisation (eta reduction -- may well be happening...); + +Note [Type lets] +~~~~~~~~~~~~~~~~ +In the desugarer, it's very very convenient to be able to say (in effect) + let a = Int in +That is, use a type let. (See notes just below for why we want this.) + +We don't have type lets in Core, so the desugarer uses type lambda + (/\a. ) Int +However, in the lambda form, we'd get lint errors from: + (/\a. let x::a = 4 in ) Int +because (x::a) doesn't look compatible with (4::Int). + +So (HACK ALERT) the Lint phase does type-beta reduction "on the fly", +as it were. It carries a type substitution (in this example [a -> Int]) +and applies this substitution before comparing types. The functin + lintTy :: Type -> LintM Type +returns a substituted type; that's the only reason it returns anything. + +When we encounter a binder (like x::a) we must apply the substitution +to the type of the binding variable. lintBinders does this. + +For Ids, the type-substituted Id is added to the in_scope set (which +itself is part of the TvSubst we are carrying down), and when we +find an occurence of an Id, we fetch it from the in-scope set. + + +Why we need type let +~~~~~~~~~~~~~~~~~~~~ +It's needed when dealing with desugarer output for GADTs. Consider + data T = forall a. T a (a->Int) Bool + f :: T -> ... -> + f (T x f True) = + f (T y g False) = +After desugaring we get + f t b = case t of + T a (x::a) (f::a->Int) (b:Bool) -> + case b of + True -> + False -> (/\b. let y=x; g=f in ) a +And for a reason I now forget, the ...... can mention a; so +we want Lint to know that b=a. Ugh. + +I tried quite hard to make the necessity for this go away, by changing the +desugarer, but the fundamental problem is this: + + T a (x::a) (y::Int) -> let fail::a = ... + in (/\b. ...(case ... of + True -> x::b + False -> fail) + ) a +Now the inner case look as though it has incompatible branches. + + \begin{code} lintCoreBindings :: DynFlags -> String -> [CoreBind] -> IO () @@ -189,6 +236,8 @@ lintSingleBinding rec_flag (binder,rhs) where binder_ty = idType binder bndr_vars = varSetElems (idFreeVars binder) + lintBinder var | isId var = lintIdBndr var $ \_ -> (return ()) + | otherwise = return () \end{code} %************************************************************************ @@ -207,18 +256,28 @@ lintCoreExpr :: CoreExpr -> LintM OutType -- lintCoreExpr e subst = exprType (subst e) lintCoreExpr (Var var) - = do { checkIdInScope var - ; applySubst (idType var) } + = do { checkL (not (var == oneTupleDataConId)) + (ptext SLIT("Illegal one-tuple")) + ; var' <- lookupIdInScope var + ; return (idType var') + } lintCoreExpr (Lit lit) = return (literalType lit) -lintCoreExpr (Note (Coerce to_ty from_ty) expr) - = do { expr_ty <- lintCoreExpr expr - ; to_ty <- lintTy to_ty - ; from_ty <- lintTy from_ty - ; checkTys from_ty expr_ty (mkCoerceErr from_ty expr_ty) - ; return to_ty } +--lintCoreExpr (Note (Coerce to_ty from_ty) expr) +-- = do { expr_ty <- lintCoreExpr expr +-- ; to_ty <- lintTy to_ty +-- ; from_ty <- lintTy from_ty +-- ; checkTys from_ty expr_ty (mkCoerceErr from_ty expr_ty) +-- ; return to_ty } + +lintCoreExpr (Cast expr co) + = do { expr_ty <- lintCoreExpr expr + ; co' <- lintTy co + ; let (from_ty, to_ty) = coercionKind co' + ; checkTys from_ty expr_ty (mkCastErr from_ty expr_ty) + ; return to_ty } lintCoreExpr (Note other_note expr) = lintCoreExpr expr @@ -226,40 +285,17 @@ lintCoreExpr (Note other_note expr) lintCoreExpr (Let (NonRec bndr rhs) body) = do { lintSingleBinding NonRecursive (bndr,rhs) ; addLoc (BodyOfLetRec [bndr]) - (addInScopeVars [bndr] (lintCoreExpr body)) } + (lintAndScopeId bndr $ \_ -> (lintCoreExpr body)) } lintCoreExpr (Let (Rec pairs) body) - = addInScopeVars bndrs $ + = lintAndScopeIds bndrs $ \_ -> do { mapM (lintSingleBinding Recursive) pairs ; addLoc (BodyOfLetRec bndrs) (lintCoreExpr body) } where bndrs = map fst pairs lintCoreExpr e@(App fun (Type ty)) --- This is like 'let' for types --- It's needed when dealing with desugarer output for GADTs. Consider --- data T = forall a. T a (a->Int) Bool --- f :: T -> ... -> --- f (T x f True) = --- f (T y g False) = --- After desugaring we get --- f t b = case t of --- T a (x::a) (f::a->Int) (b:Bool) -> --- case b of --- True -> --- False -> (/\b. let y=x; g=f in ) a --- And for a reason I now forget, the ...... can mention a; so --- we want Lint to know that b=a. Ugh. --- --- I tried quite hard to make the necessity for this go away, by changing the --- desugarer, but the fundamental problem is this: --- --- T a (x::a) (y::Int) -> let fail::a = ... --- in (/\b. ...(case ... of --- True -> x::b --- False -> fail) --- ) a --- Now the inner case look as though it has incompatible branches. +-- See Note [Type let] above = addLoc (AnExpr e) $ go fun [ty] where @@ -267,12 +303,15 @@ lintCoreExpr e@(App fun (Type ty)) = do { go fun (ty:tys) } go (Lam tv body) (ty:tys) = do { checkL (isTyVar tv) (mkKindErrMsg tv ty) -- Not quite accurate - ; ty' <- lintTy ty; - ; checkKinds tv ty' + ; ty' <- lintTy ty + ; let kind = tyVarKind tv + ; kind' <- lintTy kind + ; let tv' = setTyVarKind tv kind' + ; checkKinds tv' ty' -- Now extend the substitution so we -- take advantage of it in the body - ; addInScopeVars [tv] $ - extendSubstL tv ty' $ + ; addInScopeVars [tv'] $ + extendSubstL tv' ty' $ go body tys } go fun tys = do { fun_ty <- lintCoreExpr fun @@ -285,14 +324,13 @@ lintCoreExpr e@(App fun arg) lintCoreExpr (Lam var expr) = addLoc (LambdaBodyOf var) $ - do { body_ty <- addInScopeVars [var] $ - lintCoreExpr expr - ; if isId var then do - { var_ty <- lintId var - ; return (mkFunTy var_ty body_ty) } - else - return (mkForAllTy var body_ty) - } + lintBinders [var] $ \[var'] -> + do { body_ty <- lintCoreExpr expr + ; if isId var' then + return (mkFunTy (idType var') body_ty) + else + return (mkForAllTy var' body_ty) + } -- The applySubst is needed to apply the subst to var lintCoreExpr e@(Case scrut var alt_ty alts) = @@ -300,17 +338,22 @@ lintCoreExpr e@(Case scrut var alt_ty alts) = do { scrut_ty <- lintCoreExpr scrut ; alt_ty <- lintTy alt_ty ; var_ty <- lintTy (idType var) - -- Don't use lintId on var, because unboxed tuple is legitimate + -- Don't use lintIdBndr on var, because unboxed tuple is legitimate - ; checkTys var_ty scrut_ty (mkScrutMsg var scrut_ty) + ; subst <- getTvSubst + ; checkTys var_ty scrut_ty (mkScrutMsg var var_ty scrut_ty subst) -- If the binder is an unboxed tuple type, don't put it in scope - ; let vars = if (isUnboxedTupleType (idType var)) then [] else [var] - ; addInScopeVars vars $ + ; let scope = if (isUnboxedTupleType (idType var)) then + pass_var + else lintAndScopeId var + ; scope $ \_ -> do { -- Check the alternatives checkCaseAlts e scrut_ty alts ; mapM (lintCoreAlt scrut_ty alt_ty) alts ; return alt_ty } } + where + pass_var f = f var lintCoreExpr e@(Type ty) = addErrL (mkStrangeTyMsg e) @@ -326,8 +369,8 @@ The basic version of these functions checks that the argument is a subtype of the required type, as one would expect. \begin{code} -lintCoreArgs :: Type -> [CoreArg] -> LintM Type -lintCoreArg :: Type -> CoreArg -> LintM Type +lintCoreArgs :: OutType -> [CoreArg] -> LintM OutType +lintCoreArg :: OutType -> CoreArg -> LintM OutType -- First argument has already had substitution applied to it \end{code} @@ -344,16 +387,18 @@ lintCoreArg fun_ty a@(Type arg_ty) = lintCoreArg fun_ty arg = -- Make sure function type matches argument do { arg_ty <- lintCoreExpr arg - ; let err = mkAppMsg fun_ty arg_ty arg + ; let err1 = mkAppMsg fun_ty arg_ty arg + err2 = mkNonFunAppMsg fun_ty arg_ty arg ; case splitFunTy_maybe fun_ty of Just (arg,res) -> - do { checkTys arg arg_ty err + do { checkTys arg arg_ty err1 ; return res } - _ -> addErrL err } + _ -> addErrL err2 } \end{code} \begin{code} -- Both args have had substitution applied +lintTyApp :: OutType -> OutType -> LintM OutType lintTyApp ty arg_ty = case splitForAllTy_maybe ty of Nothing -> addErrL (mkTyAppMsg ty arg_ty) @@ -363,22 +408,17 @@ lintTyApp ty arg_ty ; checkKinds tyvar arg_ty ; return (substTyWith [tyvar] [arg_ty] body) } -lintTyApps fun_ty [] = return fun_ty - -lintTyApps fun_ty (arg_ty : arg_tys) = - do { fun_ty' <- lintTyApp fun_ty arg_ty - ; lintTyApps fun_ty' arg_tys } - checkKinds tyvar arg_ty -- Arg type might be boxed for a function with an uncommitted -- tyvar; notably this is used so that we can give -- error :: forall a:*. String -> a -- and then apply it to both boxed and unboxed types. - = checkL (argty_kind `isSubKind` tyvar_kind) + = checkL (arg_kind `isSubKind` tyvar_kind) (mkKindErrMsg tyvar arg_ty) where tyvar_kind = tyVarKind tyvar - argty_kind = typeKind arg_ty + arg_kind | isCoVar tyvar = coercionKindPredTy arg_ty + | otherwise = typeKind arg_ty \end{code} @@ -444,50 +484,29 @@ lintCoreAlt scrut_ty alt_ty alt@(LitAlt lit, args, rhs) = lit_ty = literalType lit lintCoreAlt scrut_ty alt_ty alt@(DataAlt con, args, rhs) - | Just (tycon, tycon_arg_tys) <- splitTyConApp_maybe scrut_ty, - tycon == dataConTyCon con - = addLoc (CaseAlt alt) $ - addInScopeVars args $ -- Put the args in scope before lintBinder, - -- because the Ids mention the type variables - if isVanillaDataCon con then - do { addLoc (CasePat alt) $ do - { mapM lintBinder args - -- FIX! Add check that all args are Ids. - -- Check the pattern + | isNewTyCon (dataConTyCon con) = addErrL (mkNewTyDataConAltMsg scrut_ty alt) + | Just (tycon, tycon_arg_tys) <- splitTyConApp_maybe scrut_ty + = addLoc (CaseAlt alt) $ do + { -- First instantiate the universally quantified + -- type variables of the data constructor + -- We've already check + checkL (tycon == dataConTyCon con) (mkBadConMsg tycon con) + ; let con_payload_ty = applyTys (dataConRepType con) tycon_arg_tys + + -- And now bring the new binders into scope + ; lintBinders args $ \ args -> do + { addLoc (CasePat alt) $ do + { -- Check the pattern -- Scrutinee type must be a tycon applicn; checked by caller -- This code is remarkably compact considering what it does! -- NB: args must be in scope here so that the lintCoreArgs line works. -- NB: relies on existential type args coming *after* ordinary type args - ; con_type <- lintTyApps (dataConRepType con) tycon_arg_tys - -- Can just map Var as we know that this is a vanilla datacon - ; con_result_ty <- lintCoreArgs con_type (map Var args) + ; con_result_ty <- lintCoreArgs con_payload_ty (varsToCoreExprs args) ; checkTys con_result_ty scrut_ty (mkBadPatMsg con_result_ty scrut_ty) } -- Check the RHS - ; checkAltExpr rhs alt_ty } - - else -- GADT - do { let (tvs,ids) = span isTyVar args - ; subst <- getTvSubst - ; let in_scope = getTvInScope subst - subst_env = getTvSubstEnv subst - ; case coreRefineTys con tvs scrut_ty of { - Nothing -> return () ; -- Alternative is dead code - Just (refine, _) -> updateTvSubstEnv (composeTvSubst in_scope refine subst_env) $ - do { addLoc (CasePat alt) $ do - { tvs' <- mapM lintTy (mkTyVarTys tvs) - ; con_type <- lintTyApps (dataConRepType con) tvs' - ; mapM lintBinder ids -- Lint Ids in the refined world - ; lintCoreArgs con_type (map Var ids) - } - - ; let refined_alt_ty = substTy (mkTvSubst in_scope refine) alt_ty - -- alt_ty is already an OutType, so don't re-apply - -- the current substitution. But we must apply the - -- refinement so that the check in checkAltExpr is ok - ; checkAltExpr rhs refined_alt_ty - } } } + ; checkAltExpr rhs alt_ty } } | otherwise -- Scrut-ty is wrong shape = addErrL (mkBadAltMsg scrut_ty alt) @@ -500,24 +519,59 @@ lintCoreAlt scrut_ty alt_ty alt@(DataAlt con, args, rhs) %************************************************************************ \begin{code} -lintBinder :: Var -> LintM () -lintBinder var | isId var = lintId var >> return () - | otherwise = return () - -lintId :: Var -> LintM OutType +-- When we lint binders, we (one at a time and in order): +-- 1. Lint var types or kinds (possibly substituting) +-- 2. Add the binder to the in scope set, and if its a coercion var, +-- we may extend the substitution to reflect its (possibly) new kind +lintBinders :: [Var] -> ([Var] -> LintM a) -> LintM a +lintBinders [] linterF = linterF [] +lintBinders (var:vars) linterF = lintBinder var $ \var' -> + lintBinders vars $ \ vars' -> + linterF (var':vars') + +lintBinder :: Var -> (Var -> LintM a) -> LintM a +lintBinder var linterF + | isTyVar var = lint_ty_bndr + | otherwise = lintIdBndr var linterF + where + lint_ty_bndr = do { lintTy (tyVarKind var) + ; subst <- getTvSubst + ; let (subst', tv') = substTyVarBndr subst var + ; updateTvSubst subst' (linterF tv') } + +lintIdBndr :: Var -> (Var -> LintM a) -> LintM a +-- Do substitution on the type of a binder and add the var with this +-- new type to the in-scope set of the second argument -- ToDo: lint its rules -lintId id +lintIdBndr id linterF = do { checkL (not (isUnboxedTupleType (idType id))) (mkUnboxedTupleMsg id) -- No variable can be bound to an unboxed tuple. - ; lintTy (idType id) } + ; lintAndScopeId id $ \id' -> linterF id' + } + +lintAndScopeIds :: [Var] -> ([Var] -> LintM a) -> LintM a +lintAndScopeIds ids linterF + = go ids + where + go [] = linterF [] + go (id:ids) = do { lintAndScopeId id $ \id -> + lintAndScopeIds ids $ \ids -> + linterF (id:ids) } + +lintAndScopeId :: Var -> (Var -> LintM a) -> LintM a +lintAndScopeId id linterF + = do { ty <- lintTy (idType id) + ; let id' = setIdType id ty + ; addInScopeVars [id'] $ (linterF id') + } lintTy :: InType -> LintM OutType -- Check the type, and apply the substitution to it -- ToDo: check the kind structure of the type lintTy ty = do { ty' <- applySubst ty - ; mapM_ checkIdInScope (varSetElems (tyVarsOfType ty')) + ; mapM_ checkTyVarInScope (varSetElems (tyVarsOfType ty')) ; return ty' } \end{code} @@ -538,6 +592,21 @@ newtype LintM a = Bag Message -> -- Error messages so far (Maybe a, Bag Message) } -- Result and error messages (if any) +{- Note [Type substitution] + ~~~~~~~~~~~~~~~~~~~~~~~~ +Why do we need a type substitution? Consider + /\(a:*). \(x:a). /\(a:*). id a x +This is ill typed, because (renaming variables) it is really + /\(a:*). \(x:a). /\(b:*). id b x +Hence, when checking an application, we can't naively compare x's type +(at its binding site) with its expected type (at a use site). So we +rename type binders as we go, maintaining a substitution. + +The same substitution also supports let-type, current expressed as + (/\(a:*). body) ty +Here we substitute 'ty' for 'a' in 'body', on the fly. +-} + instance Monad LintM where return x = LintM (\ loc subst errs -> (Just x, errs)) fail err = LintM (\ loc subst errs -> (Nothing, addErr subst errs (text err) loc)) @@ -595,9 +664,9 @@ addInScopeVars :: [Var] -> LintM a -> LintM a addInScopeVars vars m = LintM (\ loc subst errs -> unLintM m loc (extendTvInScope subst vars) errs) -updateTvSubstEnv :: TvSubstEnv -> LintM a -> LintM a -updateTvSubstEnv substenv m = - LintM (\ loc subst errs -> unLintM m loc (setTvSubstEnv subst substenv) errs) +updateTvSubst :: TvSubst -> LintM a -> LintM a +updateTvSubst subst' m = + LintM (\ loc subst errs -> unLintM m loc subst' errs) getTvSubst :: LintM TvSubst getTvSubst = LintM (\ loc subst errs -> (Just subst, errs)) @@ -611,11 +680,19 @@ extendSubstL tv ty m \end{code} \begin{code} -checkIdInScope :: Var -> LintM () -checkIdInScope id - = do { checkL (not (id == oneTupleDataConId)) - (ptext SLIT("Illegal one-tuple")) - ; checkInScope (ptext SLIT("is out of scope")) id } +lookupIdInScope :: Id -> LintM Id +lookupIdInScope id + | not (mustHaveLocalBinding id) + = return id -- An imported Id + | otherwise + = do { subst <- getTvSubst + ; case lookupInScope (getTvInScope subst) id of + Just v -> return v + Nothing -> do { addErrL out_of_scope + ; return id } } + where + out_of_scope = ppr id <+> ptext SLIT("is out of scope") + oneTupleDataConId :: Id -- Should not happen oneTupleDataConId = dataConWorkId (tupleCon Boxed 1) @@ -627,6 +704,9 @@ checkBndrIdInScope binder id msg = ptext SLIT("is out of scope inside info for") <+> ppr binder +checkTyVarInScope :: TyVar -> LintM () +checkTyVarInScope tv = checkInScope (ptext SLIT("is out of scope")) tv + checkInScope :: SDoc -> Var -> LintM () checkInScope loc_msg var = do { subst <- getTvSubst @@ -698,12 +778,12 @@ mkCaseAltMsg e ty1 ty2 = hang (text "Type of case alternatives not the same as the annotation on case:") 4 (vcat [ppr ty1, ppr ty2, ppr e]) -mkScrutMsg :: Id -> Type -> Message -mkScrutMsg var scrut_ty +mkScrutMsg :: Id -> Type -> Type -> TvSubst -> Message +mkScrutMsg var var_ty scrut_ty subst = vcat [text "Result binder in case doesn't match scrutinee:" <+> ppr var, - text "Result binder type:" <+> ppr (idType var), - text "Scrutinee type:" <+> ppr scrut_ty] - + text "Result binder type:" <+> ppr var_ty,--(idType var), + text "Scrutinee type:" <+> ppr scrut_ty, + hsep [ptext SLIT("Current TV subst"), ppr subst]] mkNonDefltMsg e = hang (text "Case expression with DEFAULT not at the beginnning") 4 (ppr e) @@ -714,6 +794,14 @@ nonExhaustiveAltsMsg :: CoreExpr -> Message nonExhaustiveAltsMsg e = hang (text "Case expression with non-exhaustive alternatives") 4 (ppr e) +mkBadConMsg :: TyCon -> DataCon -> Message +mkBadConMsg tycon datacon + = vcat [ + text "In a case alternative, data constructor isn't in scrutinee type:", + text "Scrutinee type constructor:" <+> ppr tycon, + text "Data con:" <+> ppr datacon + ] + mkBadPatMsg :: Type -> Type -> Message mkBadPatMsg con_result_ty scrut_ty = vcat [ @@ -728,6 +816,13 @@ mkBadAltMsg scrut_ty alt text "Scrutinee type:" <+> ppr scrut_ty, text "Alternative:" <+> pprCoreAlt alt ] +mkNewTyDataConAltMsg :: Type -> CoreAlt -> Message +mkNewTyDataConAltMsg scrut_ty alt + = vcat [ text "Data alternative for newtype datacon", + text "Scrutinee type:" <+> ppr scrut_ty, + text "Alternative:" <+> pprCoreAlt alt ] + + ------------------------------------------------------ -- Other error messages @@ -738,6 +833,13 @@ mkAppMsg fun_ty arg_ty arg hang (ptext SLIT("Arg type:")) 4 (ppr arg_ty), hang (ptext SLIT("Arg:")) 4 (ppr arg)] +mkNonFunAppMsg :: Type -> Type -> CoreExpr -> Message +mkNonFunAppMsg fun_ty arg_ty arg + = vcat [ptext SLIT("Non-function type in function position"), + hang (ptext SLIT("Fun type:")) 4 (ppr fun_ty), + hang (ptext SLIT("Arg type:")) 4 (ppr arg_ty), + hang (ptext SLIT("Arg:")) 4 (ppr arg)] + mkKindErrMsg :: TyVar -> Type -> Message mkKindErrMsg tyvar arg_ty = vcat [ptext SLIT("Kinds don't match in type application:"), @@ -774,8 +876,8 @@ mkUnboxedTupleMsg binder = vcat [hsep [ptext SLIT("A variable has unboxed tuple type:"), ppr binder], hsep [ptext SLIT("Binder's type:"), ppr (idType binder)]] -mkCoerceErr from_ty expr_ty - = vcat [ptext SLIT("From-type of Coerce differs from type of enclosed expression"), +mkCastErr from_ty expr_ty + = vcat [ptext SLIT("From-type of Cast differs from type of enclosed expression"), ptext SLIT("From-type:") <+> ppr from_ty, ptext SLIT("Type of enclosed expr:") <+> ppr expr_ty ]