X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Frename%2FRnExpr.lhs;h=78088d52cef6c39e52e1fe3bac22ec0d89aca487;hp=6dc6801e16ac51e6bac6adce6c16e17db28db529;hb=f1cc3eb980a634e62f2739a7a25387c902fa9d8a;hpb=0a5613f40b0e32cf59966e6b56b807cdbe80aa7b diff --git a/compiler/rename/RnExpr.lhs b/compiler/rename/RnExpr.lhs index 6dc6801..78088d5 100644 --- a/compiler/rename/RnExpr.lhs +++ b/compiler/rename/RnExpr.lhs @@ -42,7 +42,6 @@ import UniqSet import Data.List import Util ( isSingleton ) import ListSetOps ( removeDups ) -import Maybes ( expectJust ) import Outputable import SrcLoc import FastString @@ -538,8 +537,8 @@ methodNamesStmt (BindStmt _ cmd _ _) = methodNamesLCmd cmd methodNamesStmt (RecStmt { recS_stmts = stmts }) = methodNamesStmts stmts `addOneFV` loopAName methodNamesStmt (LetStmt _) = emptyFVs methodNamesStmt (ParStmt _) = emptyFVs -methodNamesStmt (TransformStmt _ _ _) = emptyFVs -methodNamesStmt (GroupStmt _ _) = emptyFVs +methodNamesStmt (TransformStmt {}) = emptyFVs +methodNamesStmt (GroupStmt {}) = emptyFVs -- ParStmt, TransformStmt and GroupStmt can't occur in commands, but it's not convenient to error -- here so we just do what's convenient \end{code} @@ -635,33 +634,43 @@ rnBracket (DecBrG _) = panic "rnBracket: unexpected DecBrG" rnStmts :: HsStmtContext Name -> [LStmt RdrName] -> RnM (thing, FreeVars) -> RnM (([LStmt Name], thing), FreeVars) +-- Variables bound by the Stmts, and mentioned in thing_inside, +-- do not appear in the result FreeVars -rnStmts (MDoExpr _) = rnMDoStmts -rnStmts ctxt = rnNormalStmts ctxt +rnStmts (MDoExpr _) stmts thing_inside = rnMDoStmts stmts thing_inside +rnStmts ctxt stmts thing_inside = rnNormalStmts ctxt stmts (\ _ -> thing_inside) rnNormalStmts :: HsStmtContext Name -> [LStmt RdrName] - -> RnM (thing, FreeVars) + -> ([Name] -> RnM (thing, FreeVars)) -> RnM (([LStmt Name], thing), FreeVars) +-- Variables bound by the Stmts, and mentioned in thing_inside, +-- do not appear in the result FreeVars +-- +-- Renaming a single RecStmt can give a sequence of smaller Stmts + rnNormalStmts _ [] thing_inside - = do { (thing, fvs) <- thing_inside - ; return (([],thing), fvs) } + = do { (res, fvs) <- thing_inside [] + ; return (([], res), fvs) } rnNormalStmts ctxt (stmt@(L loc _) : stmts) thing_inside = do { ((stmts1, (stmts2, thing)), fvs) - <- setSrcSpan loc $ - rnStmt ctxt stmt $ - rnNormalStmts ctxt stmts thing_inside + <- setSrcSpan loc $ + rnStmt ctxt stmt $ \ bndrs1 -> + rnNormalStmts ctxt stmts $ \ bndrs2 -> + thing_inside (bndrs1 ++ bndrs2) ; return (((stmts1 ++ stmts2), thing), fvs) } rnStmt :: HsStmtContext Name -> LStmt RdrName - -> RnM (thing, FreeVars) + -> ([Name] -> RnM (thing, FreeVars)) -> RnM (([LStmt Name], thing), FreeVars) +-- Variables bound by the Stmt, and mentioned in thing_inside, +-- do not appear in the result FreeVars rnStmt _ (L loc (ExprStmt expr _ _)) thing_inside = do { (expr', fv_expr) <- rnLExpr expr ; (then_op, fvs1) <- lookupSyntaxName thenMName - ; (thing, fvs2) <- thing_inside + ; (thing, fvs2) <- thing_inside [] ; return (([L loc (ExprStmt expr' then_op placeHolderType)], thing), fv_expr `plusFV` fvs1 `plusFV` fvs2) } @@ -671,7 +680,7 @@ rnStmt ctxt (L loc (BindStmt pat expr _ _)) thing_inside ; (bind_op, fvs1) <- lookupSyntaxName bindMName ; (fail_op, fvs2) <- lookupSyntaxName failMName ; rnPat (StmtCtxt ctxt) pat $ \ pat' -> do - { (thing, fvs3) <- thing_inside + { (thing, fvs3) <- thing_inside (collectPatBinders pat') ; return (([L loc (BindStmt pat' expr' bind_op fail_op)], thing), fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }} -- fv_expr shouldn't really be filtered by the rnPatsAndThen @@ -680,7 +689,7 @@ rnStmt ctxt (L loc (BindStmt pat expr _ _)) thing_inside rnStmt ctxt (L loc (LetStmt binds)) thing_inside = do { checkLetStmt ctxt binds ; rnLocalBindsAndThen binds $ \binds' -> do - { (thing, fvs) <- thing_inside + { (thing, fvs) <- thing_inside (collectLocalBinders binds') ; return (([L loc (LetStmt binds')], thing), fvs) } } rnStmt ctxt (L _ (RecStmt { recS_stmts = rec_stmts })) thing_inside @@ -697,7 +706,9 @@ rnStmt ctxt (L _ (RecStmt { recS_stmts = rec_stmts })) thing_inside -- context.) ; rn_rec_stmts_and_then rec_stmts $ \ segs -> do - { (thing, fvs_later) <- thing_inside + { let bndrs = nameSetToList $ foldr (unionNameSets . (\(ds,_,_,_) -> ds)) + emptyNameSet segs + ; (thing, fvs_later) <- thing_inside bndrs ; (return_op, fvs1) <- lookupSyntaxName returnMName ; (mfix_op, fvs2) <- lookupSyntaxName mfixName ; (bind_op, fvs3) <- lookupSyntaxName bindMName @@ -730,146 +741,103 @@ rnStmt ctxt (L loc (ParStmt segs)) thing_inside ; ((segs', thing), fvs) <- rnParallelStmts (ParStmtCtxt ctxt) segs thing_inside ; return (([L loc (ParStmt segs')], thing), fvs) } -rnStmt ctxt (L loc (TransformStmt (stmts, _) usingExpr maybeByExpr)) thing_inside = do - checkTransformStmt ctxt - - (usingExpr', fv_usingExpr) <- rnLExpr usingExpr - ((stmts', binders, (maybeByExpr', thing)), fvs) <- - rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \_unshadowed_bndrs -> do - (maybeByExpr', fv_maybeByExpr) <- rnMaybeLExpr maybeByExpr - (thing, fv_thing) <- thing_inside - - return ((maybeByExpr', thing), fv_maybeByExpr `plusFV` fv_thing) +rnStmt ctxt (L loc (TransformStmt stmts _ using by)) thing_inside + = do { checkTransformStmt ctxt - return (([L loc (TransformStmt (stmts', binders) usingExpr' maybeByExpr')], thing), - fv_usingExpr `plusFV` fvs) - where - rnMaybeLExpr Nothing = return (Nothing, emptyFVs) - rnMaybeLExpr (Just expr) = do - (expr', fv_expr) <- rnLExpr expr - return (Just expr', fv_expr) + ; (using', fvs1) <- rnLExpr using + + ; ((stmts', (by', used_bndrs, thing)), fvs2) + <- rnNormalStmts (TransformStmtCtxt ctxt) stmts $ \ bndrs -> + do { (by', fvs_by) <- case by of + Nothing -> return (Nothing, emptyFVs) + Just e -> do { (e', fvs) <- rnLExpr e; return (Just e', fvs) } + ; (thing, fvs_thing) <- thing_inside bndrs + ; let fvs = fvs_by `plusFV` fvs_thing + used_bndrs = filter (`elemNameSet` fvs_thing) bndrs + ; return ((by', used_bndrs, thing), fvs) } + + ; return (([L loc (TransformStmt stmts' used_bndrs using' by')], thing), + fvs1 `plusFV` fvs2) } -rnStmt ctxt (L loc (GroupStmt (stmts, _) groupByClause)) thing_inside = do - checkTransformStmt ctxt - - -- We must rename the using expression in the context before the transform is begun - groupByClauseAction <- - case groupByClause of - GroupByNothing usingExpr -> do - (usingExpr', fv_usingExpr) <- rnLExpr usingExpr - (return . return) (GroupByNothing usingExpr', fv_usingExpr) - GroupBySomething eitherUsingExpr byExpr -> do - (eitherUsingExpr', fv_eitherUsingExpr) <- - case eitherUsingExpr of - Right _ -> return (Right $ HsVar groupWithName, unitNameSet groupWithName) - Left usingExpr -> do - (usingExpr', fv_usingExpr) <- rnLExpr usingExpr - return (Left usingExpr', fv_usingExpr) - - return $ do - (byExpr', fv_byExpr) <- rnLExpr byExpr - return (GroupBySomething eitherUsingExpr' byExpr', fv_eitherUsingExpr `plusFV` fv_byExpr) +rnStmt ctxt (L loc (GroupStmt stmts _ by using)) thing_inside + = do { checkTransformStmt ctxt - -- We only use rnNormalStmtsAndFindUsedBinders to get unshadowed_bndrs, so - -- perhaps we could refactor this to use rnNormalStmts directly? - ((stmts', _, (groupByClause', usedBinderMap, thing)), fvs) <- - rnNormalStmtsAndFindUsedBinders (TransformStmtCtxt ctxt) stmts $ \unshadowed_bndrs -> do - (groupByClause', fv_groupByClause) <- groupByClauseAction - - unshadowed_bndrs' <- mapM newLocalName unshadowed_bndrs - let binderMap = zip unshadowed_bndrs unshadowed_bndrs' - - -- Bind the "thing" inside a context where we have REBOUND everything - -- bound by the statements before the group. This is necessary since after - -- the grouping the same identifiers actually have different meanings - -- i.e. they refer to lists not singletons! - (thing, fv_thing) <- bindLocalNames unshadowed_bndrs' thing_inside - - -- We remove entries from the binder map that are not used in the thing_inside. - -- We can then use that usage information to ensure that the free variables do - -- not contain the things we just bound, but do contain the things we need to - -- make those bindings (i.e. the corresponding non-listy variables) - - -- Note that we also retain those entries which have an old binder in our - -- own free variables (the using or by expression). This is because this map - -- is reused in the desugarer to create the type to bind from the statements - -- that occur before this one. If the binders we need are not in the map, they - -- will never get bound into our desugared expression and hence the simplifier - -- crashes as we refer to variables that don't exist! - let usedBinderMap = filter - (\(old_binder, new_binder) -> - (new_binder `elemNameSet` fv_thing) || - (old_binder `elemNameSet` fv_groupByClause)) binderMap - (usedOldBinders, usedNewBinders) = unzip usedBinderMap - real_fv_thing = (delListFromNameSet fv_thing usedNewBinders) `plusFV` (mkNameSet usedOldBinders) - - return ((groupByClause', usedBinderMap, thing), fv_groupByClause `plusFV` real_fv_thing) - - traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr usedBinderMap) - return (([L loc (GroupStmt (stmts', usedBinderMap) groupByClause')], thing), fvs) - -rnNormalStmtsAndFindUsedBinders :: HsStmtContext Name - -> [LStmt RdrName] - -> ([Name] -> RnM (thing, FreeVars)) - -> RnM (([LStmt Name], [Name], thing), FreeVars) -rnNormalStmtsAndFindUsedBinders ctxt stmts thing_inside = do - ((stmts', (used_bndrs, inner_thing)), fvs) <- rnNormalStmts ctxt stmts $ do - -- Find the Names that are bound by stmts that - -- by assumption we have just renamed - local_env <- getLocalRdrEnv - let - stmts_binders = collectLStmtsBinders stmts - bndrs = map (expectJust "rnStmt" - . lookupLocalRdrEnv local_env - . unLoc) stmts_binders - - -- If shadow, we'll look up (Unqual x) twice, getting - -- the second binding both times, which is the - -- one we want - unshadowed_bndrs = nub bndrs - - -- Typecheck the thing inside, passing on all - -- the Names bound before it for its information - (thing, fvs) <- thing_inside unshadowed_bndrs - - -- Figure out which of the bound names are used - -- after the statements we renamed - let used_bndrs = filter (`elemNameSet` fvs) bndrs - return ((used_bndrs, thing), fvs) - - -- Flatten the tuple returned by the above call a bit! - return ((stmts', used_bndrs, inner_thing), fvs) - -rnParallelStmts :: HsStmtContext Name -> [([LStmt RdrName], [RdrName])] - -> RnM (thing, FreeVars) - -> RnM (([([LStmt Name], [Name])], thing), FreeVars) -rnParallelStmts ctxt segs thing_inside = do - orig_lcl_env <- getLocalRdrEnv - go orig_lcl_env [] segs - where - go orig_lcl_env bndrs [] = do - let (bndrs', dups) = removeDups cmpByOcc bndrs - inner_env = extendLocalRdrEnvList orig_lcl_env bndrs' - - mapM_ dupErr dups - (thing, fvs) <- setLocalRdrEnv inner_env thing_inside - return (([], thing), fvs) - - go orig_lcl_env bndrs_so_far ((stmts, _) : segs) = do - ((stmts', bndrs, (segs', thing)), fvs) <- rnNormalStmtsAndFindUsedBinders ctxt stmts $ \new_bndrs -> do - -- Typecheck the thing inside, passing on all - -- the Names bound, but separately; revert the envt - setLocalRdrEnv orig_lcl_env $ do - go orig_lcl_env (new_bndrs ++ bndrs_so_far) segs - - let seg' = (stmts', bndrs) - return (((seg':segs'), thing), delListFromNameSet fvs bndrs) - - cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2 - dupErr vs = addErr (ptext (sLit "Duplicate binding in parallel list comprehension for:") + -- Rename the 'using' expression in the context before the transform is begun + ; (using', fvs1) <- case using of + Left e -> do { (e', fvs) <- rnLExpr e; return (Left e', fvs) } + Right _ -> do { (e', fvs) <- lookupSyntaxName groupWithName + ; return (Right e', fvs) } + + -- Rename the stmts and the 'by' expression + -- Keep track of the variables mentioned in the 'by' expression + ; ((stmts', (by', used_bndrs, thing)), fvs2) + <- rnNormalStmts (TransformStmtCtxt ctxt) stmts $ \ bndrs -> + do { (by', fvs_by) <- mapMaybeFvRn rnLExpr by + ; (thing, fvs_thing) <- thing_inside bndrs + ; let fvs = fvs_by `plusFV` fvs_thing + used_bndrs = filter (`elemNameSet` fvs) bndrs + ; return ((by', used_bndrs, thing), fvs) } + + ; let all_fvs = fvs1 `plusFV` fvs2 + bndr_map = used_bndrs `zip` used_bndrs + + ; traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr bndr_map) + ; return (([L loc (GroupStmt stmts' bndr_map by' using')], thing), all_fvs) } + + +type ParSeg id = ([LStmt id], [id]) -- The Names are bound by the Stmts + +rnParallelStmts :: forall thing. HsStmtContext Name + -> [ParSeg RdrName] + -> ([Name] -> RnM (thing, FreeVars)) + -> RnM (([ParSeg Name], thing), FreeVars) +-- Note [Renaming parallel Stmts] +rnParallelStmts ctxt segs thing_inside + = do { orig_lcl_env <- getLocalRdrEnv + ; rn_segs orig_lcl_env [] segs } + where + rn_segs :: LocalRdrEnv + -> [Name] -> [ParSeg RdrName] + -> RnM (([ParSeg Name], thing), FreeVars) + rn_segs _ bndrs_so_far [] + = do { let (bndrs', dups) = removeDups cmpByOcc bndrs_so_far + ; mapM_ dupErr dups + ; (thing, fvs) <- bindLocalNames bndrs' (thing_inside bndrs') + ; return (([], thing), fvs) } + + rn_segs env bndrs_so_far ((stmts,_) : segs) + = do { ((stmts', (used_bndrs, segs', thing)), fvs) + <- rnNormalStmts ctxt stmts $ \ bndrs -> + setLocalRdrEnv env $ do + { ((segs', thing), fvs) <- rn_segs env (bndrs ++ bndrs_so_far) segs + ; let used_bndrs = filter (`elemNameSet` fvs) bndrs + ; return ((used_bndrs, segs', thing), fvs) } + + ; let seg' = (stmts', used_bndrs) + ; return ((seg':segs', thing), fvs) } + + cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2 + dupErr vs = addErr (ptext (sLit "Duplicate binding in parallel list comprehension for:") <+> quotes (ppr (head vs))) \end{code} +Note [Renaming parallel Stmts] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Renaming parallel statements is painful. Given, say + [ a+c | a <- as, bs <- bss + | c <- bs, a <- ds ] +Note that + (a) In order to report "Defined by not used" about 'bs', we must rename + each group of Stmts with a thing_inside whose FreeVars include at least {a,c} + + (b) We want to report that 'a' is illegally bound in both branches + + (c) The 'bs' in the second group must obviously not be captured by + the binding in the first group + +To satisfy (a) we nest the segements. +To satisfy (b) we check for duplicates just before thing_inside. +To satisfy (c) we reset the LocalRdrEnv each time. %************************************************************************ %* * @@ -916,7 +884,7 @@ rn_rec_stmts_and_then s cont ; new_lhs_and_fv <- rn_rec_stmts_lhs fix_env s -- ...bring them and their fixities into scope - ; let bound_names = map unLoc $ collectLStmtsBinders (map fst new_lhs_and_fv) + ; let bound_names = collectLStmtsBinders (map fst new_lhs_and_fv) ; bindLocalNamesFV_WithFixities bound_names fix_env $ do -- (C) do the right-hand-sides and thing-inside @@ -972,10 +940,10 @@ rn_rec_stmt_lhs fix_env (L _ (RecStmt { recS_stmts = stmts })) -- Flatten Rec in rn_rec_stmt_lhs _ stmt@(L _ (ParStmt _)) -- Syntactically illegal in mdo = pprPanic "rn_rec_stmt" (ppr stmt) -rn_rec_stmt_lhs _ stmt@(L _ (TransformStmt _ _ _)) -- Syntactically illegal in mdo +rn_rec_stmt_lhs _ stmt@(L _ (TransformStmt {})) -- Syntactically illegal in mdo = pprPanic "rn_rec_stmt" (ppr stmt) -rn_rec_stmt_lhs _ stmt@(L _ (GroupStmt _ _)) -- Syntactically illegal in mdo +rn_rec_stmt_lhs _ stmt@(L _ (GroupStmt {})) -- Syntactically illegal in mdo = pprPanic "rn_rec_stmt" (ppr stmt) rn_rec_stmt_lhs _ (L _ (LetStmt EmptyLocalBinds)) @@ -985,13 +953,13 @@ rn_rec_stmts_lhs :: MiniFixityEnv -> [LStmt RdrName] -> RnM [(LStmtLR Name RdrName, FreeVars)] rn_rec_stmts_lhs fix_env stmts - = do { let boundNames = collectLStmtsBinders stmts + = do { ls <- concatMapM (rn_rec_stmt_lhs fix_env) stmts + ; let boundNames = collectLStmtsBinders (map fst ls) -- First do error checking: we need to check for dups here because we -- don't bind all of the variables from the Stmt at once -- with bindLocatedLocals. - ; checkDupRdrNames boundNames - ; ls <- mapM (rn_rec_stmt_lhs fix_env) stmts - ; return (concat ls) } + ; checkDupNames boundNames + ; return ls } -- right-hand-sides