+
%
+% (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 (
lintCoreBindings,
lintUnfolding,
- showPass, endPass
+ showPass, endPass, endPassIf, endIteration
) where
#include "HsVersions.h"
+import NewDemand
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 Id
+import IdInfo
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 ListSetOps
+import DynFlags
import Outputable
-
-#ifdef DEBUG
-import Util ( notNull )
-#endif
-
-import Maybe
-
+import FastString
+import Util
+import Data.Maybe
\end{code}
%************************************************************************
and do Core Lint when necessary.
\begin{code}
-endPass :: DynFlags -> String -> DynFlag -> [CoreBind] -> IO [CoreBind]
-endPass dflags pass_name dump_flag binds
+endPass :: DynFlags -> String -> DynFlag -> [CoreBind] -> IO ()
+endPass = dumpAndLint dumpIfSet_core
+
+endPassIf :: Bool -> DynFlags -> String -> DynFlag -> [CoreBind] -> IO ()
+endPassIf cond = dumpAndLint (dumpIf_core cond)
+
+endIteration :: DynFlags -> String -> DynFlag -> [CoreBind] -> IO ()
+endIteration = dumpAndLint dumpIfSet_dyn
+
+dumpAndLint :: (DynFlags -> DynFlag -> String -> SDoc -> IO ())
+ -> DynFlags -> String -> DynFlag -> [CoreBind] -> IO ()
+dumpAndLint dump dflags pass_name dump_flag binds
= do
-- Report result size if required
-- This has the side effect of forcing the intermediate to be evaluated
(text " Result size =" <+> int (coreBindsSize binds))
-- Report verbosely, if required
- dumpIfSet_core dflags dump_flag pass_name (pprCoreBindings binds)
+ dump dflags dump_flag pass_name (pprCoreBindings binds)
-- Type check
lintCoreBindings dflags pass_name binds
-
- return binds
\end{code}
-- * Oversaturated type app after specialisation (eta reduction
-- may well be happening...);
+
+Note [Linting type lets]
+~~~~~~~~~~~~~~~~~~~~~~~~
+In the desugarer, it's very very convenient to be able to say (in effect)
+ let a = Type Int in <body>
+That is, use a type let. See Note [Type let] in CoreSyn.
+
+However, when linting <body> we need to remember that a=Int, else we might
+reject a correct program. So we carry a type substitution (in this example
+[a -> Int]) and apply 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.
+
+
\begin{code}
lintCoreBindings :: DynFlags -> String -> [CoreBind] -> IO ()
-lintCoreBindings dflags whoDunnit binds
+lintCoreBindings dflags _whoDunnit _binds
| not (dopt Opt_DoCoreLinting dflags)
= return ()
-- Put all the top-level binders in scope at the start
-- This is because transformation rules can bring something
-- into use 'unexpectedly'
- lint_binds binds = addInScopeVars (bindersOfBinds binds) $
+ lint_binds binds = addLoc TopLevelBindings $
+ addInScopeVars (bindersOfBinds binds) $
mapM lint_bind binds
- lint_bind (Rec prs) = mapM_ (lintSingleBinding Recursive) prs
- lint_bind (NonRec bndr rhs) = lintSingleBinding NonRecursive (bndr,rhs)
+ lint_bind (Rec prs) = mapM_ (lintSingleBinding TopLevel Recursive) prs
+ lint_bind (NonRec bndr rhs) = lintSingleBinding TopLevel NonRecursive (bndr,rhs)
display bad_news
= vcat [ text ("*** Core Lint Errors: in result of " ++ whoDunnit ++ " ***"),
bad_news,
- ptext SLIT("*** Offending Program ***"),
+ ptext (sLit "*** Offending Program ***"),
pprCoreBindings binds,
- ptext SLIT("*** End of Offense ***")
+ ptext (sLit "*** End of Offense ***")
]
\end{code}
Check a core binding, returning the list of variables bound.
\begin{code}
-lintSingleBinding rec_flag (binder,rhs)
+lintSingleBinding :: TopLevelFlag -> RecFlag -> (Id, CoreExpr) -> LintM ()
+lintSingleBinding top_lvl_flag rec_flag (binder,rhs)
= addLoc (RhsOf binder) $
-- Check the rhs
do { ty <- lintCoreExpr rhs
; checkL (not (isUnLiftedType binder_ty)
|| (isNonRec rec_flag && exprOkForSpeculation rhs))
(mkRhsPrimMsg binder rhs)
+ -- Check that if the binder is top-level or recursive, it's not demanded
+ ; checkL (not (isStrictId binder)
+ || (isNonRec rec_flag && not (isTopLevel top_lvl_flag)))
+ (mkStrictMsg binder)
-- Check whether binder's specialisations contain any out-of-scope variables
- ; mapM_ (checkBndrIdInScope binder) bndr_vars }
+ ; mapM_ (checkBndrIdInScope binder) bndr_vars
+
+ -- Check whether arity and demand type are consistent (only if demand analysis
+ -- already happened)
+ ; checkL (case maybeDmdTy of
+ Just (StrictSig dmd_ty) -> idArity binder >= dmdTypeDepth dmd_ty || exprIsTrivial rhs
+ Nothing -> True)
+ (mkArityMsg binder) }
-- We should check the unfolding, if any, but this is tricky because
- -- the unfolding is a SimplifiableCoreExpr. Give up for now.
- where
- binder_ty = idType binder
- bndr_vars = varSetElems (idFreeVars binder)
+ -- the unfolding is a SimplifiableCoreExpr. Give up for now.
+ where
+ binder_ty = idType binder
+ maybeDmdTy = idNewStrictness_maybe binder
+ bndr_vars = varSetElems (idFreeVars binder `unionVarSet` wkr_vars)
+ wkr_vars | workerExists wkr_info = unitVarSet (workerId wkr_info)
+ | otherwise = emptyVarSet
+ wkr_info = idWorkerInfo binder
+ lintBinder var | isId var = lintIdBndr var $ \_ -> (return ())
+ | otherwise = return ()
\end{code}
%************************************************************************
-- The returned type has the substitution from the monad
-- already applied to it:
-- lintCoreExpr e subst = exprType (subst e)
+--
+-- The returned "type" can be a kind, if the expression is (Type ty)
lintCoreExpr (Var var)
- = do { checkIdInScope var
- ; applySubst (idType var) }
+ = do { checkL (not (var == oneTupleDataConId))
+ (ptext (sLit "Illegal one-tuple"))
+
+ ; checkDeadIdOcc var
+ ; 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 other_note expr)
+--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 _ expr)
= lintCoreExpr expr
+lintCoreExpr (Let (NonRec tv (Type ty)) body)
+ = -- See Note [Type let] in CoreSyn
+ do { checkL (isTyVar tv) (mkKindErrMsg tv ty) -- Not quite accurate
+ ; ty' <- lintTy ty
+ ; kind' <- lintTy (tyVarKind tv)
+ ; let tv' = setTyVarKind tv kind'
+ ; checkKinds tv' ty'
+ -- Now extend the substitution so we
+ -- take advantage of it in the body
+ ; addLoc (BodyOfLetRec [tv]) $
+ addInScopeVars [tv'] $
+ extendSubstL tv' ty' $
+ lintCoreExpr body }
+
lintCoreExpr (Let (NonRec bndr rhs) body)
- = do { lintSingleBinding NonRecursive (bndr,rhs)
+ = do { lintSingleBinding NotTopLevel NonRecursive (bndr,rhs)
; addLoc (BodyOfLetRec [bndr])
- (addInScopeVars [bndr] (lintCoreExpr body)) }
+ (lintAndScopeId bndr $ \_ -> (lintCoreExpr body)) }
lintCoreExpr (Let (Rec pairs) body)
- = addInScopeVars bndrs $
- do { mapM (lintSingleBinding Recursive) pairs
+ = lintAndScopeIds bndrs $ \_ ->
+ do { mapM_ (lintSingleBinding NotTopLevel 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.
- = addLoc (AnExpr e) $
- go fun [ty]
- where
- go (App fun (Type ty)) tys
- = 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'
- -- Now extend the substitution so we
- -- take advantage of it in the body
- ; addInScopeVars [tv] $
- extendSubstL tv ty' $
- go body tys }
- go fun tys
- = do { fun_ty <- lintCoreExpr fun
- ; lintCoreArgs fun_ty (map Type tys) }
-
lintCoreExpr e@(App fun arg)
= do { fun_ty <- lintCoreExpr fun
; addLoc (AnExpr e) $
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
- ; checkTys var_ty scrut_ty (mkScrutMsg var scrut_ty)
+ ; let mb_tc_app = splitTyConApp_maybe (idType var)
+ ; case mb_tc_app of
+ Just (tycon, _)
+ | debugIsOn &&
+ isAlgTyCon tycon &&
+ not (isOpenTyCon tycon) &&
+ null (tyConDataCons tycon) ->
+ pprTrace "Lint warning: case binder's type has no constructors" (ppr var <+> ppr (idType var))
+ -- This can legitimately happen for type families
+ $ return ()
+ _otherwise -> return ()
+
+ -- Don't use lintIdBndr on var, because unboxed tuple is legitimate
+
+ ; 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
+ mapM_ (lintCoreAlt scrut_ty alt_ty) alts
+ ; checkCaseAlts e scrut_ty alts
; return alt_ty } }
+ where
+ pass_var f = f var
-lintCoreExpr e@(Type ty)
- = addErrL (mkStrangeTyMsg e)
+lintCoreExpr (Type ty)
+ = do { ty' <- lintTy ty
+ ; return (typeKind ty') }
\end{code}
%************************************************************************
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}
do { res <- lintCoreArg ty a
; lintCoreArgs res args }
-lintCoreArg fun_ty a@(Type arg_ty) =
+lintCoreArg fun_ty (Type arg_ty) =
do { arg_ty <- lintTy arg_ty
; lintTyApp fun_ty 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)
; 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 :: Var -> Type -> LintM ()
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
+
+checkDeadIdOcc :: Id -> LintM ()
+-- Occurrences of an Id should never be dead....
+-- except when we are checking a case pattern
+checkDeadIdOcc id
+ | isDeadOcc (idOccInfo id)
+ = do { in_case <- inCasePat
+ ; checkL in_case
+ (ptext (sLit "Occurrence of a dead Id") <+> ppr id) }
+ | otherwise
+ = return ()
\end{code}
-- the simplifer correctly eliminates case that can't
-- possibly match.
-checkCaseAlts e ty []
+checkCaseAlts e _ []
= addErrL (mkNullAltsMsg e)
checkCaseAlts e ty alts =
-- Check that successive alternatives have increasing tags
increasing_tag (alt1 : rest@( alt2 : _)) = alt1 `ltAlt` alt2 && increasing_tag rest
- increasing_tag other = True
+ increasing_tag _ = True
non_deflt (DEFAULT, _, _) = False
- non_deflt alt = True
+ non_deflt _ = True
is_infinite_ty = case splitTyConApp_maybe ty of
- Nothing -> False
- Just (tycon, tycon_arg_tys) -> isPrimTyCon tycon
+ Nothing -> False
+ Just (tycon, _) -> isPrimTyCon tycon
\end{code}
\begin{code}
-> CoreAlt
-> LintM ()
-lintCoreAlt scrut_ty alt_ty alt@(DEFAULT, args, rhs) =
+lintCoreAlt _ alt_ty (DEFAULT, args, rhs) =
do { checkL (null args) (mkDefaultArgsMsg args)
; checkAltExpr rhs alt_ty }
-lintCoreAlt scrut_ty alt_ty alt@(LitAlt lit, args, rhs) =
+lintCoreAlt scrut_ty alt_ty (LitAlt lit, args, rhs) =
do { checkL (null args) (mkDefaultArgsMsg args)
; checkTys lit_ty scrut_ty (mkBadPatMsg lit_ty scrut_ty)
; checkAltExpr rhs alt_ty }
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)
+ -- 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_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)
%************************************************************************
\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
+-- See Note [Linting type lets]
-- 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}
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))
+ return x = LintM (\ _ _ errs -> (Just x, errs))
fail err = LintM (\ loc subst errs -> (Nothing, addErr subst errs (text err) loc))
m >>= k = LintM (\ loc subst errs ->
let (res, errs') = unLintM m loc subst errs in
| LambdaBodyOf Id -- The lambda-binder
| BodyOfLetRec [Id] -- One of the binders
| CaseAlt CoreAlt -- Case alternative
- | CasePat CoreAlt -- *Pattern* of the case alternative
+ | CasePat CoreAlt -- The *pattern* of the case alternative
| AnExpr CoreExpr -- Some expression
| ImportedUnfolding SrcLoc -- Some imported unfolding (ToDo: say which)
+ | TopLevelBindings
\end{code}
initL m
= case unLintM m [] emptyTvSubst emptyBag of
(_, errs) | isEmptyBag errs -> Nothing
- | otherwise -> Just (vcat (punctuate (text "") (bagToList errs)))
+ | otherwise -> Just (vcat (punctuate blankLine (bagToList errs)))
\end{code}
\begin{code}
checkL :: Bool -> Message -> LintM ()
-checkL True msg = return ()
+checkL True _ = return ()
checkL False msg = addErrL msg
addErrL :: Message -> LintM a
(loc, cxt1) = dumpLoc (head locs)
cxts = [snd (dumpLoc loc) | loc <- locs]
context | opt_PprStyle_Debug = vcat (reverse cxts) $$ cxt1 $$
- ptext SLIT("Substitution:") <+> ppr subst
+ ptext (sLit "Substitution:") <+> ppr subst
| otherwise = cxt1
mk_msg msg = mkLocMessage (mkSrcSpan loc loc) (context $$ msg)
addLoc extra_loc m =
LintM (\ loc subst errs -> unLintM m (extra_loc:loc) subst errs)
+inCasePat :: LintM Bool -- A slight hack; see the unique call site
+inCasePat = LintM $ \ loc _ errs -> (Just (is_case_pat loc), errs)
+ where
+ is_case_pat (CasePat {} : _) = True
+ is_case_pat _other = False
+
addInScopeVars :: [Var] -> LintM a -> LintM a
-addInScopeVars vars m =
- LintM (\ loc subst errs -> unLintM m loc (extendTvInScope subst vars) errs)
+addInScopeVars vars m
+ | null dups
+ = LintM (\ loc subst errs -> unLintM m loc (extendTvInScope subst vars) errs)
+ | otherwise
+ = addErrL (dupVars dups)
+ where
+ (_, dups) = removeDups compare vars
-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 _ errs -> unLintM m loc subst' errs)
getTvSubst :: LintM TvSubst
-getTvSubst = LintM (\ loc subst errs -> (Just subst, errs))
+getTvSubst = LintM (\ _ subst errs -> (Just subst, errs))
applySubst :: Type -> LintM Type
applySubst ty = do { subst <- getTvSubst; return (substTy subst ty) }
\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)
checkBndrIdInScope binder id
= checkInScope msg id
where
- msg = ptext SLIT("is out of scope inside info for") <+>
+ 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
%************************************************************************
\begin{code}
+dumpLoc :: LintLocInfo -> (SrcLoc, SDoc)
+
dumpLoc (RhsOf v)
- = (getSrcLoc v, brackets (ptext SLIT("RHS of") <+> pp_binders [v]))
+ = (getSrcLoc v, brackets (ptext (sLit "RHS of") <+> pp_binders [v]))
dumpLoc (LambdaBodyOf b)
- = (getSrcLoc b, brackets (ptext SLIT("in body of lambda with binder") <+> pp_binder b))
+ = (getSrcLoc b, brackets (ptext (sLit "in body of lambda with binder") <+> pp_binder b))
dumpLoc (BodyOfLetRec [])
- = (noSrcLoc, brackets (ptext SLIT("In body of a letrec with no binders")))
+ = (noSrcLoc, brackets (ptext (sLit "In body of a letrec with no binders")))
dumpLoc (BodyOfLetRec bs@(_:_))
- = ( getSrcLoc (head bs), brackets (ptext SLIT("in body of letrec with binders") <+> pp_binders bs))
+ = ( getSrcLoc (head bs), brackets (ptext (sLit "in body of letrec with binders") <+> pp_binders bs))
dumpLoc (AnExpr e)
= (noSrcLoc, text "In the expression:" <+> ppr e)
-dumpLoc (CaseAlt (con, args, rhs))
+dumpLoc (CaseAlt (con, args, _))
= (noSrcLoc, text "In a case alternative:" <+> parens (ppr con <+> pp_binders args))
-dumpLoc (CasePat (con, args, rhs))
+dumpLoc (CasePat (con, args, _))
= (noSrcLoc, text "In the pattern of a case alternative:" <+> parens (ppr con <+> pp_binders args))
dumpLoc (ImportedUnfolding locn)
- = (locn, brackets (ptext SLIT("in an imported unfolding")))
+ = (locn, brackets (ptext (sLit "in an imported unfolding")))
+dumpLoc TopLevelBindings
+ = (noSrcLoc, empty)
pp_binders :: [Var] -> SDoc
pp_binders bs = sep (punctuate comma (map pp_binder bs))
pp_binder :: Var -> SDoc
pp_binder b | isId b = hsep [ppr b, dcolon, ppr (idType b)]
- | isTyVar b = hsep [ppr b, dcolon, ppr (tyVarKind b)]
+ | otherwise = hsep [ppr b, dcolon, ppr (tyVarKind b)]
\end{code}
\begin{code}
= 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, mkNonIncreasingAltsMsg :: CoreExpr -> Message
mkNonDefltMsg e
= hang (text "Case expression with DEFAULT not at the beginnning") 4 (ppr e)
mkNonIncreasingAltsMsg e
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 [
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
mkAppMsg :: Type -> Type -> CoreExpr -> Message
mkAppMsg fun_ty arg_ty arg
- = vcat [ptext SLIT("Argument value doesn't match argument type:"),
- 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)]
+ = vcat [ptext (sLit "Argument value doesn't match argument type:"),
+ 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)]
+
+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:"),
- hang (ptext SLIT("Type variable:"))
+ = vcat [ptext (sLit "Kinds don't match in type application:"),
+ hang (ptext (sLit "Type variable:"))
4 (ppr tyvar <+> dcolon <+> ppr (tyVarKind tyvar)),
- hang (ptext SLIT("Arg type:"))
+ hang (ptext (sLit "Arg type:"))
4 (ppr arg_ty <+> dcolon <+> ppr (typeKind arg_ty))]
mkTyAppMsg :: Type -> Type -> Message
mkTyAppMsg ty arg_ty
= vcat [text "Illegal type application:",
- hang (ptext SLIT("Exp type:"))
+ hang (ptext (sLit "Exp type:"))
4 (ppr ty <+> dcolon <+> ppr (typeKind ty)),
- hang (ptext SLIT("Arg type:"))
+ hang (ptext (sLit "Arg type:"))
4 (ppr arg_ty <+> dcolon <+> ppr (typeKind arg_ty))]
mkRhsMsg :: Id -> Type -> Message
mkRhsMsg binder ty
= vcat
- [hsep [ptext SLIT("The type of this binder doesn't match the type of its RHS:"),
+ [hsep [ptext (sLit "The type of this binder doesn't match the type of its RHS:"),
ppr binder],
- hsep [ptext SLIT("Binder's type:"), ppr (idType binder)],
- hsep [ptext SLIT("Rhs type:"), ppr ty]]
+ hsep [ptext (sLit "Binder's type:"), ppr (idType binder)],
+ hsep [ptext (sLit "Rhs type:"), ppr ty]]
mkRhsPrimMsg :: Id -> CoreExpr -> Message
-mkRhsPrimMsg binder rhs
- = vcat [hsep [ptext SLIT("The type of this binder is primitive:"),
+mkRhsPrimMsg binder _rhs
+ = vcat [hsep [ptext (sLit "The type of this binder is primitive:"),
ppr binder],
- hsep [ptext SLIT("Binder's type:"), ppr (idType binder)]
+ hsep [ptext (sLit "Binder's type:"), ppr (idType binder)]
]
+mkStrictMsg :: Id -> Message
+mkStrictMsg binder
+ = vcat [hsep [ptext (sLit "Recursive or top-level binder has strict demand info:"),
+ ppr binder],
+ hsep [ptext (sLit "Binder's demand info:"), ppr (idNewDemandInfo binder)]
+ ]
+
+mkArityMsg :: Id -> Message
+mkArityMsg binder
+ = vcat [hsep [ptext (sLit "Demand type has "),
+ ppr (dmdTypeDepth dmd_ty),
+ ptext (sLit " arguments, rhs has "),
+ ppr (idArity binder),
+ ptext (sLit "arguments, "),
+ ppr binder],
+ hsep [ptext (sLit "Binder's strictness signature:"), ppr dmd_ty]
+
+ ]
+ where (StrictSig dmd_ty) = idNewStrictness binder
+
mkUnboxedTupleMsg :: Id -> Message
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"),
- ptext SLIT("From-type:") <+> ppr from_ty,
- ptext SLIT("Type of enclosed expr:") <+> ppr expr_ty
+ = vcat [hsep [ptext (sLit "A variable has unboxed tuple type:"), ppr binder],
+ hsep [ptext (sLit "Binder's type:"), ppr (idType binder)]]
+
+mkCastErr :: Type -> Type -> Message
+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
]
-mkStrangeTyMsg e
- = ptext SLIT("Type where expression expected:") <+> ppr e
+dupVars :: [[Var]] -> Message
+dupVars vars
+ = hang (ptext (sLit "Duplicate variables brought into scope"))
+ 2 (ppr vars)
\end{code}
projects / ghc-hetmet.git / blobdiff