import CoreSyn
import CoreFVs ( idFreeVars )
import CoreUtils ( findDefault, exprOkForSpeculation, coreBindsSize )
-import Unify ( coreRefineTys )
import Bag
import Literal ( literalType )
-import DataCon ( dataConRepType, isVanillaDataCon, dataConTyCon, dataConWorkId )
+import DataCon ( dataConRepType, dataConTyCon, dataConWorkId )
import TysWiredIn ( tupleCon )
-import Var ( Var, Id, TyVar, idType, tyVarKind, mustHaveLocalBinding )
+import Var ( Var, Id, TyVar, idType, tyVarKind, mustHaveLocalBinding, setTyVarKind, setIdType )
+import VarEnv ( lookupInScope )
import VarSet
import Name ( getSrcLoc )
import PprCore
isUnboxedTupleType, isSubKind,
substTyWith, emptyTvSubst, extendTvInScope,
TvSubst, TvSubstEnv, mkTvSubst, setTvSubstEnv, substTy,
- extendTvSubst, composeTvSubst, isInScope,
- getTvSubstEnv, getTvInScope )
+ extendTvSubst, composeTvSubst, substTyVarBndr, isInScope,
+ getTvSubstEnv, getTvInScope, mkTyVarTy )
+import Coercion ( Coercion, coercionKind )
import TyCon ( isPrimTyCon )
import BasicTypes ( RecFlag(..), Boxity(..), isNonRec )
import StaticFlags ( opt_PprStyle_Debug )
-- * 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 <body>
+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. <body>) Int
+However, in the lambda form, we'd get lint errors from:
+ (/\a. let x::a = 4 in <body>) 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) = <e1>
+ f (T y g False) = <e2>
+After desugaring we get
+ f t b = case t of
+ T a (x::a) (f::a->Int) (b:Bool) ->
+ case b of
+ True -> <e1>
+ False -> (/\b. let y=x; g=f in <e2>) a
+And for a reason I now forget, the ...<e2>... 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 ()
where
binder_ty = idType binder
bndr_vars = varSetElems (idFreeVars binder)
+ lintBinder var | isId var = lintIdBndr var $ \_ -> (return ())
+ | otherwise = return ()
\end{code}
%************************************************************************
-- 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
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) = <e1>
--- f (T y g False) = <e2>
--- After desugaring we get
--- f t b = case t of
--- T a (x::a) (f::a->Int) (b:Bool) ->
--- case b of
--- True -> <e1>
--- False -> (/\b. let y=x; g=f in <e2>) a
--- And for a reason I now forget, the ...<e2>... 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
= 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
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) =
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)
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
+ | Just (tycon, tycon_arg_tys) <- splitTyConApp_maybe scrut_ty
+ = addLoc (CaseAlt alt) $ 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 (dataConRepType con)
+ (map Type tycon_arg_tys ++ 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
- } } }
-
| otherwise -- Scrut-ty is wrong shape
= addErrL (mkBadAltMsg scrut_ty alt)
\end{code}
%************************************************************************
\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}
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))
\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)
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
= 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
= 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
]
projects / ghc-hetmet.git / blobdiff