module CoreLint (
lintCoreBindings,
lintUnfolding,
- beginPass, endPass
+ showPass, endPass
) where
#include "HsVersions.h"
-import IO ( hPutStr, hPutStrLn, stderr, stdout )
-
-import CmdLineOpts ( opt_D_show_passes, opt_DoCoreLinting, opt_PprStyle_Debug )
import CoreSyn
import CoreFVs ( idFreeVars )
-import CoreUtils ( exprOkForSpeculation, coreBindsSize )
-
+import CoreUtils ( findDefault, exprOkForSpeculation, coreBindsSize )
+import Unify ( coreRefineTys )
import Bag
-import Literal ( Literal, literalType )
-import DataCon ( DataCon, dataConRepType )
-import Id ( mayHaveNoBinding, isDeadBinder )
-import Var ( Var, Id, TyVar, idType, tyVarKind, isTyVar, isId )
+import Literal ( literalType )
+import DataCon ( dataConRepType, isVanillaDataCon, dataConTyCon, dataConWorkId )
+import TysWiredIn ( tupleCon )
+import Var ( Var, Id, TyVar, idType, tyVarKind, mustHaveLocalBinding )
import VarSet
-import Subst ( mkTyVarSubst, substTy )
-import Name ( isLocallyDefined, getSrcLoc )
+import Name ( getSrcLoc )
import PprCore
-import ErrUtils ( doIfSet, dumpIfSet, ghcExit, Message,
- ErrMsg, addErrLocHdrLine, pprBagOfErrors )
-import PrimRep ( PrimRep(..) )
-import SrcLoc ( SrcLoc, noSrcLoc, isNoSrcLoc )
-import Type ( Type, Kind, tyVarsOfType,
- splitFunTy_maybe, mkPiType, mkTyVarTy, unUsgTy,
+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,
- splitAlgTyConApp_maybe,
- isUnboxedTupleType,
- hasMoreBoxityInfo
- )
-import TyCon ( TyCon, isPrimTyCon, tyConDataCons )
-import BasicTypes ( RecFlag(..), isNonRec )
+ 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 Outputable
-infixr 9 `thenL`, `seqL`
+#ifdef DEBUG
+import Util ( notNull )
+#endif
+
+import Maybe
+
\end{code}
%************************************************************************
%* *
-\subsection{Start and end pass}
+\subsection{End pass}
%* *
%************************************************************************
-@beginPass@ and @endPass@ don't really belong here, but it makes a convenient
+@showPass@ and @endPass@ don't really belong here, but it makes a convenient
place for them. They print out stuff before and after core passes,
and do Core Lint when necessary.
\begin{code}
-beginPass :: String -> IO ()
-beginPass pass_name
- | opt_D_show_passes
- = hPutStrLn stderr ("*** " ++ pass_name)
- | otherwise
- = return ()
-
-
-endPass :: String -> Bool -> [CoreBind] -> IO [CoreBind]
-endPass pass_name dump_flag binds
+endPass :: DynFlags -> String -> DynFlag -> [CoreBind] -> IO [CoreBind]
+endPass dflags pass_name dump_flag binds
= do
-- Report result size if required
-- This has the side effect of forcing the intermediate to be evaluated
- if opt_D_show_passes then
- hPutStrLn stdout (" Result size = " ++ show (coreBindsSize binds))
- else
- return ()
+ debugTraceMsg dflags 2 $
+ (text " Result size =" <+> int (coreBindsSize binds))
-- Report verbosely, if required
- dumpIfSet dump_flag pass_name
- (pprCoreBindings binds)
+ dumpIfSet_core dflags dump_flag pass_name (pprCoreBindings binds)
-- Type check
- lintCoreBindings pass_name binds
+ lintCoreBindings dflags pass_name binds
return binds
\end{code}
--
-- Things are *not* OK if:
--
- -- * Unsaturated type app before specialisation has been done;
+ -- * Unsaturated type app before specialisation has been done;
--
- -- * Oversaturated type app after specialisation (eta reduction
+ -- * Oversaturated type app after specialisation (eta reduction
-- may well be happening...);
\begin{code}
-lintCoreBindings :: String -> [CoreBind] -> IO ()
+lintCoreBindings :: DynFlags -> String -> [CoreBind] -> IO ()
-lintCoreBindings whoDunnit binds
- | not opt_DoCoreLinting
+lintCoreBindings dflags whoDunnit binds
+ | not (dopt Opt_DoCoreLinting dflags)
= return ()
-lintCoreBindings whoDunnit binds
+lintCoreBindings dflags whoDunnit binds
= case (initL (lint_binds binds)) of
- Nothing -> doIfSet opt_D_show_passes
- (hPutStr stderr ("*** Core Linted result of " ++ whoDunnit ++ "\n"))
-
+ Nothing -> showPass dflags ("Core Linted result of " ++ whoDunnit)
Just bad_news -> printDump (display bad_news) >>
- ghcExit 1
+ ghcExit dflags 1
where
-- 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) $
- mapL lint_bind binds
+ mapM lint_bind binds
- lint_bind (Rec prs) = mapL (lintSingleBinding Recursive) prs `seqL`
- returnL ()
+ lint_bind (Rec prs) = mapM_ (lintSingleBinding Recursive) prs
lint_bind (NonRec bndr rhs) = lintSingleBinding NonRecursive (bndr,rhs)
display bad_news
- = vcat [
- text ("*** Core Lint Errors: in result of " ++ whoDunnit ++ " ***"),
+ = vcat [ text ("*** Core Lint Errors: in result of " ++ whoDunnit ++ " ***"),
bad_news,
ptext SLIT("*** Offending Program ***"),
pprCoreBindings binds,
lintUnfolding :: SrcLoc
-> [Var] -- Treat these as in scope
-> CoreExpr
- -> Maybe Message -- Nothing => OK
+ -> Maybe Message -- Nothing => OK
lintUnfolding locn vars expr
- | not opt_DoCoreLinting
- = Nothing
-
- | otherwise
= initL (addLoc (ImportedUnfolding locn) $
- addInScopeVars vars $
- lintCoreExpr expr)
+ addInScopeVars vars $
+ lintCoreExpr expr)
\end{code}
%************************************************************************
\begin{code}
lintSingleBinding rec_flag (binder,rhs)
= addLoc (RhsOf binder) $
-
- -- Check the rhs
- lintCoreExpr rhs `thenL` \ ty ->
-
- -- Check match to RHS type
- lintBinder binder `seqL`
- checkTys binder_ty ty (mkRhsMsg binder ty) `seqL`
-
- -- Check (not isUnLiftedType) (also checks for bogus unboxed tuples)
- checkL (not (isUnLiftedType binder_ty) || (isNonRec rec_flag && exprOkForSpeculation rhs))
- (mkRhsPrimMsg binder rhs) `seqL`
-
+ -- Check the rhs
+ do { ty <- lintCoreExpr rhs
+ ; lintBinder binder -- Check match to RHS type
+ ; binder_ty <- applySubst binder_ty
+ ; checkTys binder_ty ty (mkRhsMsg binder ty)
+ -- Check (not isUnLiftedType) (also checks for bogus unboxed tuples)
+ ; checkL (not (isUnLiftedType binder_ty)
+ || (isNonRec rec_flag && exprOkForSpeculation rhs))
+ (mkRhsPrimMsg binder rhs)
-- Check whether binder's specialisations contain any out-of-scope variables
- mapL (checkBndrIdInScope binder) bndr_vars `seqL`
- returnL ()
+ ; mapM_ (checkBndrIdInScope binder) bndr_vars }
-- We should check the unfolding, if any, but this is tricky because
-- the unfolding is a SimplifiableCoreExpr. Give up for now.
%************************************************************************
\begin{code}
-lintCoreExpr :: CoreExpr -> LintM Type
+type InType = Type -- Substitution not yet applied
+type OutType = Type -- Substitution has been applied to this
+
+lintCoreExpr :: CoreExpr -> LintM OutType
+-- The returned type has the substitution from the monad
+-- already applied to it:
+-- lintCoreExpr e subst = exprType (subst e)
-lintCoreExpr (Var var) = checkIdInScope var `seqL` returnL (idType var)
-lintCoreExpr (Lit lit) = returnL (literalType lit)
+lintCoreExpr (Var var)
+ = do { checkIdInScope var
+ ; applySubst (idType var) }
+
+lintCoreExpr (Lit lit)
+ = return (literalType lit)
lintCoreExpr (Note (Coerce to_ty from_ty) expr)
- = lintCoreExpr expr `thenL` \ expr_ty ->
- lintTy to_ty `seqL`
- lintTy from_ty `seqL`
- checkTys from_ty (unUsgTy expr_ty) (mkCoerceErr from_ty expr_ty) `seqL`
- returnL to_ty
+ = 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 expr
lintCoreExpr (Let (NonRec bndr rhs) body)
- = lintSingleBinding NonRecursive (bndr,rhs) `seqL`
- addLoc (BodyOfLetRec [bndr])
- (addInScopeVars [bndr] (lintCoreExpr body))
+ = do { lintSingleBinding NonRecursive (bndr,rhs)
+ ; addLoc (BodyOfLetRec [bndr])
+ (addInScopeVars [bndr] (lintCoreExpr body)) }
-lintCoreExpr (Let (Rec pairs) body)
+lintCoreExpr (Let (Rec pairs) body)
= addInScopeVars bndrs $
- mapL (lintSingleBinding Recursive) pairs `seqL`
- addLoc (BodyOfLetRec bndrs) (lintCoreExpr body)
+ 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.
+ = 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)
- = lintCoreExpr fun `thenL` \ ty ->
- addLoc (AnExpr e) $
- lintCoreArg ty arg
+ = do { fun_ty <- lintCoreExpr fun
+ ; addLoc (AnExpr e) $
+ lintCoreArg fun_ty arg }
lintCoreExpr (Lam var expr)
- = addLoc (LambdaBodyOf var) $
- checkL (not (isUnboxedTupleType (idType var))) (mkUnboxedTupleMsg var)
- `seqL`
- (addInScopeVars [var] $
- lintCoreExpr expr `thenL` \ ty ->
- returnL (mkPiType var ty))
-
-lintCoreExpr e@(Case scrut var alts)
- = -- Check the scrutinee
- lintCoreExpr scrut `thenL` \ scrut_ty ->
-
- -- Check the binder
- lintBinder var `seqL`
-
- -- If this is an unboxed tuple case, then the binder must be dead
- {-
- checkL (if isUnboxedTupleType (idType var)
- then isDeadBinder var
- else True) (mkUnboxedTupleMsg var) `seqL`
- -}
-
- checkTys (idType var) scrut_ty (mkScrutMsg var scrut_ty) `seqL`
-
- addInScopeVars [var] (
-
- -- Check the alternatives
- checkAllCasesCovered e scrut_ty alts `seqL`
- mapL (lintCoreAlt scrut_ty) alts `thenL` \ (alt_ty : alt_tys) ->
- mapL (check alt_ty) alt_tys `seqL`
- returnL alt_ty)
- where
- check alt_ty1 alt_ty2 = checkTys alt_ty1 alt_ty2 (mkCaseAltMsg e)
+ = 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)
+ }
+ -- The applySubst is needed to apply the subst to var
+
+lintCoreExpr e@(Case scrut var alt_ty alts) =
+ -- Check the scrutinee
+ 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)
+
+ -- 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 $
+ do { -- Check the alternatives
+ checkCaseAlts e scrut_ty alts
+ ; mapM (lintCoreAlt scrut_ty alt_ty) alts
+ ; return alt_ty } }
lintCoreExpr e@(Type ty)
= addErrL (mkStrangeTyMsg e)
%* *
%************************************************************************
-The boolean argument indicates whether we should flag type
-applications to primitive types as being errors.
+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
-
-lintCoreArgs ty [] = returnL ty
-lintCoreArgs ty (a : args)
- = lintCoreArg ty a `thenL` \ res ->
- lintCoreArgs res args
+lintCoreArg :: Type -> CoreArg -> LintM Type
+-- First argument has already had substitution applied to it
\end{code}
\begin{code}
-lintCoreArg :: Type -> CoreArg -> LintM Type
-
-lintCoreArg ty a@(Type arg_ty)
- = lintTy arg_ty `seqL`
- lintTyApp ty arg_ty
-
-lintCoreArg fun_ty arg
- = -- Make sure function type matches argument
- lintCoreExpr arg `thenL` \ arg_ty ->
- case (splitFunTy_maybe fun_ty) of
- Just (arg,res) | (arg_ty == arg) -> returnL res
- _ -> addErrL (mkAppMsg fun_ty arg_ty)
+lintCoreArgs ty [] = return ty
+lintCoreArgs ty (a : args) =
+ do { res <- lintCoreArg ty a
+ ; lintCoreArgs res args }
+
+lintCoreArg fun_ty a@(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
+ ; case splitFunTy_maybe fun_ty of
+ Just (arg,res) ->
+ do { checkTys arg arg_ty err
+ ; return res }
+ _ -> addErrL err }
\end{code}
\begin{code}
+-- Both args have had substitution applied
lintTyApp ty arg_ty
= case splitForAllTy_maybe ty of
Nothing -> addErrL (mkTyAppMsg ty arg_ty)
- Just (tyvar,body) ->
- let
- tyvar_kind = tyVarKind tyvar
- argty_kind = typeKind arg_ty
- in
- if argty_kind `hasMoreBoxityInfo` tyvar_kind
- -- 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.
- then
- returnL (substTy (mkTyVarSubst [tyvar] [arg_ty]) body)
- else
- addErrL (mkKindErrMsg tyvar arg_ty)
-
-lintTyApps fun_ty []
- = returnL fun_ty
-
-lintTyApps fun_ty (arg_ty : arg_tys)
- = lintTyApp fun_ty arg_ty `thenL` \ fun_ty' ->
- lintTyApps fun_ty' arg_tys
-\end{code}
+ Just (tyvar,body)
+ -> do { checkL (isTyVar tyvar) (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 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)
+ (mkKindErrMsg tyvar arg_ty)
+ where
+ tyvar_kind = tyVarKind tyvar
+ argty_kind = typeKind arg_ty
+\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-checkAllCasesCovered e ty [] = addErrL (mkNullAltsMsg e)
-
-checkAllCasesCovered e ty [(DEFAULT,_,_)] = nopL
+checkCaseAlts :: CoreExpr -> OutType -> [CoreAlt] -> LintM ()
+-- a) Check that the alts are non-empty
+-- b1) Check that the DEFAULT comes first, if it exists
+-- b2) Check that the others are in increasing order
+-- c) Check that there's a default for infinite types
+-- NB: Algebraic cases are not necessarily exhaustive, because
+-- the simplifer correctly eliminates case that can't
+-- possibly match.
+
+checkCaseAlts e ty []
+ = addErrL (mkNullAltsMsg e)
+
+checkCaseAlts e ty alts =
+ do { checkL (all non_deflt con_alts) (mkNonDefltMsg e)
+ ; checkL (increasing_tag con_alts) (mkNonIncreasingAltsMsg e)
+ ; checkL (isJust maybe_deflt || not is_infinite_ty)
+ (nonExhaustiveAltsMsg e) }
+ where
+ (con_alts, maybe_deflt) = findDefault alts
-checkAllCasesCovered e scrut_ty alts
- = case splitTyConApp_maybe scrut_ty of {
- Nothing -> addErrL (badAltsMsg e);
- Just (tycon, tycon_arg_tys) ->
+ -- Check that successive alternatives have increasing tags
+ increasing_tag (alt1 : rest@( alt2 : _)) = alt1 `ltAlt` alt2 && increasing_tag rest
+ increasing_tag other = True
- if isPrimTyCon tycon then
- checkL (hasDefault alts) (nonExhaustiveAltsMsg e)
- else
-{- No longer needed
-#ifdef DEBUG
- -- Algebraic cases are not necessarily exhaustive, because
- -- the simplifer correctly eliminates case that can't
- -- possibly match.
- -- This code just emits a message to say so
- let
- missing_cons = filter not_in_alts (tyConDataCons tycon)
- not_in_alts con = all (not_in_alt con) alts
- not_in_alt con (DataCon con', _, _) = con /= con'
- not_in_alt con other = True
-
- case_bndr = case e of { Case _ bndr alts -> bndr }
- in
- if not (hasDefault alts || null missing_cons) then
- pprTrace "Exciting (but not a problem)! Non-exhaustive case:"
- (ppr case_bndr <+> ppr missing_cons)
- nopL
- else
-#endif
--}
- nopL }
+ non_deflt (DEFAULT, _, _) = False
+ non_deflt alt = True
-hasDefault [] = False
-hasDefault ((DEFAULT,_,_) : alts) = True
-hasDefault (alt : alts) = hasDefault alts
+ is_infinite_ty = case splitTyConApp_maybe ty of
+ Nothing -> False
+ Just (tycon, tycon_arg_tys) -> isPrimTyCon tycon
\end{code}
\begin{code}
-lintCoreAlt :: Type -- Type of scrutinee
+checkAltExpr :: CoreExpr -> OutType -> LintM ()
+checkAltExpr expr ann_ty
+ = do { actual_ty <- lintCoreExpr expr
+ ; checkTys actual_ty ann_ty (mkCaseAltMsg expr actual_ty ann_ty) }
+
+lintCoreAlt :: OutType -- Type of scrutinee
+ -> OutType -- Type of the alternative
-> CoreAlt
- -> LintM Type -- Type of alternatives
+ -> LintM ()
-lintCoreAlt scrut_ty alt@(DEFAULT, args, rhs)
- = checkL (null args) (mkDefaultArgsMsg args) `seqL`
- lintCoreExpr rhs
+lintCoreAlt scrut_ty alt_ty alt@(DEFAULT, args, rhs) =
+ do { checkL (null args) (mkDefaultArgsMsg args)
+ ; checkAltExpr rhs alt_ty }
-lintCoreAlt scrut_ty alt@(LitAlt lit, args, rhs)
- = checkL (null args) (mkDefaultArgsMsg args) `seqL`
- checkTys lit_ty scrut_ty
- (mkBadPatMsg lit_ty scrut_ty) `seqL`
- lintCoreExpr rhs
+lintCoreAlt scrut_ty alt_ty alt@(LitAlt lit, args, rhs) =
+ do { checkL (null args) (mkDefaultArgsMsg args)
+ ; checkTys lit_ty scrut_ty (mkBadPatMsg lit_ty scrut_ty)
+ ; checkAltExpr rhs alt_ty }
where
lit_ty = literalType lit
-lintCoreAlt scrut_ty alt@(DataAlt con, args, rhs)
- = addLoc (CaseAlt alt) (
-
- mapL (\arg -> checkL (not (isUnboxedTupleType (idType arg)))
- (mkUnboxedTupleMsg arg)) args `seqL`
-
- addInScopeVars args (
-
- -- 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.
- case splitTyConApp_maybe scrut_ty of { Just (tycon, tycon_arg_tys) ->
- lintTyApps (dataConRepType con) tycon_arg_tys `thenL` \ con_type ->
- lintCoreArgs con_type (map mk_arg args) `thenL` \ con_result_ty ->
- checkTys con_result_ty scrut_ty (mkBadPatMsg con_result_ty scrut_ty)
- } `seqL`
-
- -- Check the RHS
- lintCoreExpr rhs
- ))
- where
- mk_arg b | isTyVar b = Type (mkTyVarTy b)
- | otherwise = Var b
+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
+ -- 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)
+ ; 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 in_scope 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 v = nopL
--- ToDo: lint its type
-
-lintTy :: Type -> LintM ()
-lintTy ty = mapL checkIdInScope (varSetElems (tyVarsOfType ty)) `seqL`
- returnL ()
- -- ToDo: check the kind structure of the type
+lintBinder var | isId var = lintId var >> return ()
+ | otherwise = return ()
+
+lintId :: Var -> LintM OutType
+-- ToDo: lint its rules
+lintId id
+ = do { checkL (not (isUnboxedTupleType (idType id)))
+ (mkUnboxedTupleMsg id)
+ -- No variable can be bound to an unboxed tuple.
+ ; lintTy (idType 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'))
+ ; return ty' }
\end{code}
%************************************************************************
\begin{code}
-type LintM a = [LintLocInfo] -- Locations
- -> IdSet -- Local vars in scope
- -> Bag ErrMsg -- Error messages so far
- -> (Maybe a, Bag ErrMsg) -- Result and error messages (if any)
+newtype LintM a =
+ LintM { unLintM ::
+ [LintLocInfo] -> -- Locations
+ TvSubst -> -- Current type substitution; we also use this
+ -- to keep track of all the variables in scope,
+ -- both Ids and TyVars
+ Bag Message -> -- Error messages so far
+ (Maybe a, Bag Message) } -- Result and error messages (if any)
+
+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))
+ m >>= k = LintM (\ loc subst errs ->
+ let (res, errs') = unLintM m loc subst errs in
+ case res of
+ Just r -> unLintM (k r) loc subst errs'
+ Nothing -> (Nothing, errs'))
data LintLocInfo
= RhsOf Id -- The variable bound
| LambdaBodyOf Id -- The lambda-binder
| BodyOfLetRec [Id] -- One of the binders
- | CaseAlt CoreAlt -- Pattern of a case alternative
+ | CaseAlt CoreAlt -- Case alternative
+ | CasePat CoreAlt -- *Pattern* of the case alternative
| AnExpr CoreExpr -- Some expression
| ImportedUnfolding SrcLoc -- Some imported unfolding (ToDo: say which)
\end{code}
+
\begin{code}
-initL :: LintM a -> Maybe Message
+initL :: LintM a -> Maybe Message {- errors -}
initL m
- = case (m [] emptyVarSet emptyBag) of { (_, errs) ->
- if isEmptyBag errs then
- Nothing
- else
- Just (pprBagOfErrors errs)
- }
-
-returnL :: a -> LintM a
-returnL r loc scope errs = (Just r, errs)
-
-nopL :: LintM a
-nopL loc scope errs = (Nothing, errs)
-
-thenL :: LintM a -> (a -> LintM b) -> LintM b
-thenL m k loc scope errs
- = case m loc scope errs of
- (Just r, errs') -> k r loc scope errs'
- (Nothing, errs') -> (Nothing, errs')
-
-seqL :: LintM a -> LintM b -> LintM b
-seqL m k loc scope errs
- = case m loc scope errs of
- (_, errs') -> k loc scope errs'
-
-mapL :: (a -> LintM b) -> [a] -> LintM [b]
-mapL f [] = returnL []
-mapL f (x:xs)
- = f x `thenL` \ r ->
- mapL f xs `thenL` \ rs ->
- returnL (r:rs)
+ = case unLintM m [] emptyTvSubst emptyBag of
+ (_, errs) | isEmptyBag errs -> Nothing
+ | otherwise -> Just (vcat (punctuate (text "") (bagToList errs)))
\end{code}
\begin{code}
checkL :: Bool -> Message -> LintM ()
-checkL True msg loc scope errs = (Nothing, errs)
-checkL False msg loc scope errs = (Nothing, addErr errs msg loc)
+checkL True msg = return ()
+checkL False msg = addErrL msg
addErrL :: Message -> LintM a
-addErrL msg loc scope errs = (Nothing, addErr errs msg loc)
-
-addErr :: Bag ErrMsg -> Message -> [LintLocInfo] -> Bag ErrMsg
+addErrL msg = LintM (\ loc subst errs -> (Nothing, addErr subst errs msg loc))
-addErr errs_so_far msg locs
- = ASSERT (not (null locs))
+addErr :: TvSubst -> Bag Message -> Message -> [LintLocInfo] -> Bag Message
+addErr subst errs_so_far msg locs
+ = ASSERT( notNull locs )
errs_so_far `snocBag` mk_msg msg
where
(loc, cxt1) = dumpLoc (head locs)
cxts = [snd (dumpLoc loc) | loc <- locs]
- context | opt_PprStyle_Debug = vcat (reverse cxts) $$ cxt1
+ context | opt_PprStyle_Debug = vcat (reverse cxts) $$ cxt1 $$
+ ptext SLIT("Substitution:") <+> ppr subst
| otherwise = cxt1
- mk_msg msg
- | isNoSrcLoc loc = (loc, hang context 4 msg)
- | otherwise = addErrLocHdrLine loc context msg
+ mk_msg msg = mkLocMessage (mkSrcSpan loc loc) (context $$ msg)
addLoc :: LintLocInfo -> LintM a -> LintM a
-addLoc extra_loc m loc scope errs
- = m (extra_loc:loc) scope errs
+addLoc extra_loc m =
+ LintM (\ loc subst errs -> unLintM m (extra_loc:loc) subst errs)
addInScopeVars :: [Var] -> LintM a -> LintM a
-addInScopeVars ids m loc scope errs
- = m loc (scope `unionVarSet` mkVarSet ids) errs
+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)
+
+getTvSubst :: LintM TvSubst
+getTvSubst = LintM (\ loc subst errs -> (Just subst, errs))
+
+applySubst :: Type -> LintM Type
+applySubst ty = do { subst <- getTvSubst; return (substTy subst ty) }
+
+extendSubstL :: TyVar -> Type -> LintM a -> LintM a
+extendSubstL tv ty m
+ = LintM (\ loc subst errs -> unLintM m loc (extendTvSubst subst tv ty) errs)
\end{code}
\begin{code}
checkIdInScope :: Var -> LintM ()
checkIdInScope id
- = checkInScope (ptext SLIT("is out of scope")) id
+ = do { checkL (not (id == oneTupleDataConId))
+ (ptext SLIT("Illegal one-tuple"))
+ ; checkInScope (ptext SLIT("is out of scope")) id }
+
+oneTupleDataConId :: Id -- Should not happen
+oneTupleDataConId = dataConWorkId (tupleCon Boxed 1)
checkBndrIdInScope :: Var -> Var -> LintM ()
checkBndrIdInScope binder id
ppr binder
checkInScope :: SDoc -> Var -> LintM ()
-checkInScope loc_msg var loc scope errs
- | isLocallyDefined var
- && not (var `elemVarSet` scope)
- && not (isId var && mayHaveNoBinding var)
- -- Micro-hack here... Class decls generate applications of their
- -- dictionary constructor, but don't generate a binding for the
- -- constructor (since it would never be used). After a single round
- -- of simplification, these dictionary constructors have been
- -- inlined (from their UnfoldInfo) to CoCons. Just between
- -- desugaring and simplfication, though, they appear as naked, unbound
- -- variables as the function in an application.
- -- The hack here simply doesn't check for out-of-scope-ness for
- -- data constructors (at least, in a function position).
- -- Ditto primitive Ids
- = (Nothing, addErr errs (hsep [ppr var, loc_msg]) loc)
- | otherwise
- = (Nothing,errs)
+checkInScope loc_msg var =
+ do { subst <- getTvSubst
+ ; checkL (not (mustHaveLocalBinding var) || (var `isInScope` subst))
+ (hsep [ppr var, loc_msg]) }
checkTys :: Type -> Type -> Message -> LintM ()
-checkTys ty1 ty2 msg loc scope errs
- | ty1 == ty2 = (Nothing, errs)
- | otherwise = (Nothing, addErr errs msg loc)
+-- check ty2 is subtype of ty1 (ie, has same structure but usage
+-- annotations need only be consistent, not equal)
+-- Assumes ty1,ty2 are have alrady had the substitution applied
+checkTys ty1 ty2 msg = checkL (ty1 `coreEqType` ty2) msg
\end{code}
-
%************************************************************************
%* *
\subsection{Error messages}
dumpLoc (LambdaBodyOf b)
= (getSrcLoc b, brackets (ptext SLIT("in body of lambda with binder") <+> pp_binder b))
-dumpLoc (BodyOfLetRec bs)
+dumpLoc (BodyOfLetRec [])
+ = (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))
dumpLoc (AnExpr e)
= (noSrcLoc, text "In the expression:" <+> ppr e)
dumpLoc (CaseAlt (con, args, rhs))
- = (noSrcLoc, text "In a case pattern:" <+> parens (ppr con <+> ppr args))
+ = (noSrcLoc, text "In a case alternative:" <+> parens (ppr con <+> pp_binders args))
+
+dumpLoc (CasePat (con, args, rhs))
+ = (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")))
-pp_binders :: [Id] -> SDoc
+pp_binders :: [Var] -> SDoc
pp_binders bs = sep (punctuate comma (map pp_binder bs))
-pp_binder :: Id -> SDoc
-pp_binder b = hsep [ppr b, dcolon, ppr (idType b)]
+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)]
\end{code}
\begin{code}
= hang (text "DEFAULT case with binders")
4 (ppr args)
-mkCaseAltMsg :: CoreExpr -> Message
-mkCaseAltMsg e
- = hang (text "Type of case alternatives not the same:")
- 4 (ppr e)
+mkCaseAltMsg :: CoreExpr -> Type -> Type -> Message
+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
text "Result binder type:" <+> ppr (idType var),
text "Scrutinee type:" <+> ppr scrut_ty]
-badAltsMsg :: CoreExpr -> Message
-badAltsMsg e
- = hang (text "Case statement scrutinee is not a data type:")
- 4 (ppr e)
+
+mkNonDefltMsg e
+ = hang (text "Case expression with DEFAULT not at the beginnning") 4 (ppr e)
+mkNonIncreasingAltsMsg e
+ = hang (text "Case expression with badly-ordered alternatives") 4 (ppr e)
nonExhaustiveAltsMsg :: CoreExpr -> Message
nonExhaustiveAltsMsg e
- = hang (text "Case expression with non-exhaustive alternatives")
- 4 (ppr e)
+ = hang (text "Case expression with non-exhaustive alternatives") 4 (ppr e)
mkBadPatMsg :: Type -> Type -> Message
mkBadPatMsg con_result_ty scrut_ty
text "Scrutinee type:" <+> ppr scrut_ty
]
+mkBadAltMsg :: Type -> CoreAlt -> Message
+mkBadAltMsg scrut_ty alt
+ = vcat [ text "Data alternative when scrutinee is not a tycon application",
+ text "Scrutinee type:" <+> ppr scrut_ty,
+ text "Alternative:" <+> pprCoreAlt alt ]
+
------------------------------------------------------
-- Other error messages
-mkAppMsg fun arg
+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),
- hang (ptext SLIT("Arg type:")) 4 (ppr arg)]
+ 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
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