% % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[RnBinds]{Renaming and dependency analysis of bindings} This module does renaming and dependency analysis on value bindings in the abstract syntax. It does {\em not} do cycle-checks on class or type-synonym declarations; those cannot be done at this stage because they may be affected by renaming (which isn't fully worked out yet). \begin{code} module RnBinds (rnTopBinds, rnTopBindsLHS, rnTopBindsRHS, -- use these for top-level bindings rnLocalBindsAndThen, rnValBindsLHS, rnValBindsRHS, -- or these for local bindings rnMethodBinds, renameSigs, mkSigTvFn, rnMatchGroup, rnGRHSs, makeMiniFixityEnv, MiniFixityEnv ) where import {-# SOURCE #-} RnExpr( rnLExpr, rnStmts ) import HsSyn import RdrHsSyn import RnHsSyn import TcRnMonad import RnTypes ( rnHsSigType, rnLHsType, checkPrecMatch) import RnPat (rnPatsAndThen_LocalRightwards, rnBindPat, NameMaker, localRecNameMaker, topRecNameMaker, applyNameMaker ) import RnEnv import PrelNames ( mkUnboundName ) import DynFlags ( DynFlag(..) ) import Name import NameEnv import NameSet import RdrName ( RdrName, rdrNameOcc ) import SrcLoc import ListSetOps ( findDupsEq ) import BasicTypes ( RecFlag(..) ) import Digraph ( SCC(..), stronglyConnComp ) import Bag import Outputable import FastString import Data.List ( partition ) import Maybes ( orElse ) import Monad ( foldM, unless ) \end{code} -- ToDo: Put the annotations into the monad, so that they arrive in the proper -- place and can be used when complaining. The code tree received by the function @rnBinds@ contains definitions in where-clauses which are all apparently mutually recursive, but which may not really depend upon each other. For example, in the top level program \begin{verbatim} f x = y where a = x y = x \end{verbatim} the definitions of @a@ and @y@ do not depend on each other at all. Unfortunately, the typechecker cannot always check such definitions. \footnote{Mycroft, A. 1984. Polymorphic type schemes and recursive definitions. In Proceedings of the International Symposium on Programming, Toulouse, pp. 217-39. LNCS 167. Springer Verlag.} However, the typechecker usually can check definitions in which only the strongly connected components have been collected into recursive bindings. This is precisely what the function @rnBinds@ does. ToDo: deal with case where a single monobinds binds the same variable twice. The vertag tag is a unique @Int@; the tags only need to be unique within one @MonoBinds@, so that unique-Int plumbing is done explicitly (heavy monad machinery not needed). %************************************************************************ %* * %* naming conventions * %* * %************************************************************************ \subsection[name-conventions]{Name conventions} The basic algorithm involves walking over the tree and returning a tuple containing the new tree plus its free variables. Some functions, such as those walking polymorphic bindings (HsBinds) and qualifier lists in list comprehensions (@Quals@), return the variables bound in local environments. These are then used to calculate the free variables of the expression evaluated in these environments. Conventions for variable names are as follows: \begin{itemize} \item new code is given a prime to distinguish it from the old. \item a set of variables defined in @Exp@ is written @dvExp@ \item a set of variables free in @Exp@ is written @fvExp@ \end{itemize} %************************************************************************ %* * %* analysing polymorphic bindings (HsBindGroup, HsBind) %* * %************************************************************************ \subsubsection[dep-HsBinds]{Polymorphic bindings} Non-recursive expressions are reconstructed without any changes at top level, although their component expressions may have to be altered. However, non-recursive expressions are currently not expected as \Haskell{} programs, and this code should not be executed. Monomorphic bindings contain information that is returned in a tuple (a @FlatMonoBinds@) containing: \begin{enumerate} \item a unique @Int@ that serves as the ``vertex tag'' for this binding. \item the name of a function or the names in a pattern. These are a set referred to as @dvLhs@, the defined variables of the left hand side. \item the free variables of the body. These are referred to as @fvBody@. \item the definition's actual code. This is referred to as just @code@. \end{enumerate} The function @nonRecDvFv@ returns two sets of variables. The first is the set of variables defined in the set of monomorphic bindings, while the second is the set of free variables in those bindings. The set of variables defined in a non-recursive binding is just the union of all of them, as @union@ removes duplicates. However, the free variables in each successive set of cumulative bindings is the union of those in the previous set plus those of the newest binding after the defined variables of the previous set have been removed. @rnMethodBinds@ deals only with the declarations in class and instance declarations. It expects only to see @FunMonoBind@s, and it expects the global environment to contain bindings for the binders (which are all class operations). %************************************************************************ %* * \subsubsection{ Top-level bindings} %* * %************************************************************************ \begin{code} -- for top-level bindings, we need to make top-level names, -- so we have a different entry point than for local bindings rnTopBindsLHS :: MiniFixityEnv -> HsValBinds RdrName -> RnM (HsValBindsLR Name RdrName) rnTopBindsLHS fix_env binds = (uncurry $ rnValBindsLHSFromDoc (topRecNameMaker fix_env)) (bindersAndDoc binds) binds rnTopBindsRHS :: [Name] -- the names bound by these binds -> HsValBindsLR Name RdrName -> RnM (HsValBinds Name, DefUses) rnTopBindsRHS bound_names binds = do { is_boot <- tcIsHsBoot ; if is_boot then rnTopBindsBoot binds else rnValBindsRHSGen (\x -> x) -- don't trim free vars bound_names binds } -- wrapper if we don't need to do anything in between the left and right, -- or anything else in the scope of the left -- -- never used when there are fixity declarations rnTopBinds :: HsValBinds RdrName -> RnM (HsValBinds Name, DefUses) rnTopBinds b = do nl <- rnTopBindsLHS emptyFsEnv b let bound_names = map unLoc (collectHsValBinders nl) bindLocalNames bound_names $ rnTopBindsRHS bound_names nl rnTopBindsBoot :: HsValBindsLR Name RdrName -> RnM (HsValBinds Name, DefUses) -- A hs-boot file has no bindings. -- Return a single HsBindGroup with empty binds and renamed signatures rnTopBindsBoot (ValBindsIn mbinds sigs) = do { checkErr (isEmptyLHsBinds mbinds) (bindsInHsBootFile mbinds) ; sigs' <- renameSigs Nothing okHsBootSig sigs ; return (ValBindsOut [] sigs', usesOnly (hsSigsFVs sigs')) } rnTopBindsBoot b = pprPanic "rnTopBindsBoot" (ppr b) \end{code} %********************************************************* %* * HsLocalBinds %* * %********************************************************* \begin{code} rnLocalBindsAndThen :: HsLocalBinds RdrName -> (HsLocalBinds Name -> RnM (result, FreeVars)) -> RnM (result, FreeVars) -- This version (a) assumes that the binding vars are *not* already in scope -- (b) removes the binders from the free vars of the thing inside -- The parser doesn't produce ThenBinds rnLocalBindsAndThen EmptyLocalBinds thing_inside = thing_inside EmptyLocalBinds rnLocalBindsAndThen (HsValBinds val_binds) thing_inside = rnValBindsAndThen val_binds $ \ val_binds' -> thing_inside (HsValBinds val_binds') rnLocalBindsAndThen (HsIPBinds binds) thing_inside = do (binds',fv_binds) <- rnIPBinds binds (thing, fvs_thing) <- thing_inside (HsIPBinds binds') return (thing, fvs_thing `plusFV` fv_binds) rnIPBinds :: HsIPBinds RdrName -> RnM (HsIPBinds Name, FreeVars) rnIPBinds (IPBinds ip_binds _no_dict_binds) = do (ip_binds', fvs_s) <- mapAndUnzipM (wrapLocFstM rnIPBind) ip_binds return (IPBinds ip_binds' emptyLHsBinds, plusFVs fvs_s) rnIPBind :: IPBind RdrName -> RnM (IPBind Name, FreeVars) rnIPBind (IPBind n expr) = do name <- newIPNameRn n (expr',fvExpr) <- rnLExpr expr return (IPBind name expr', fvExpr) \end{code} %************************************************************************ %* * ValBinds %* * %************************************************************************ \begin{code} -- wrapper for local binds -- creates the documentation info and calls the helper below rnValBindsLHS :: MiniFixityEnv -> HsValBinds RdrName -> RnM (HsValBindsLR Name RdrName) rnValBindsLHS fix_env binds = let (boundNames,doc) = bindersAndDoc binds in rnValBindsLHSFromDoc_Local boundNames doc fix_env binds -- a helper used for local binds that does the duplicates check, -- just so we don't forget to do it somewhere rnValBindsLHSFromDoc_Local :: [Located RdrName] -- RdrNames of the LHS (so we don't have to gather them twice) -> SDoc -- doc string for dup names and shadowing -> MiniFixityEnv -> HsValBinds RdrName -> RnM (HsValBindsLR Name RdrName) rnValBindsLHSFromDoc_Local boundNames doc fix_env binds = do -- Do error checking: we need to check for dups here because we -- don't don't bind all of the variables from the ValBinds at once -- with bindLocatedLocals any more. checkDupAndShadowedRdrNames doc boundNames -- (Note that we don't want to do this at the top level, since -- sorting out duplicates and shadowing there happens elsewhere. -- The behavior is even different. For example, -- import A(f) -- f = ... -- should not produce a shadowing warning (but it will produce -- an ambiguity warning if you use f), but -- import A(f) -- g = let f = ... in f -- should. rnValBindsLHSFromDoc (localRecNameMaker fix_env) boundNames doc binds bindersAndDoc :: HsValBinds RdrName -> ([Located RdrName], SDoc) bindersAndDoc binds = let -- the unrenamed bndrs for error checking and reporting orig = collectHsValBinders binds doc = text "In the binding group for:" <+> pprWithCommas ppr (map unLoc orig) in (orig, doc) -- renames the left-hand sides -- generic version used both at the top level and for local binds -- does some error checking, but not what gets done elsewhere at the top level rnValBindsLHSFromDoc :: NameMaker -> [Located RdrName] -- RdrNames of the LHS (so we don't have to gather them twice) -> SDoc -- doc string for dup names and shadowing -> HsValBinds RdrName -> RnM (HsValBindsLR Name RdrName) rnValBindsLHSFromDoc topP _original_bndrs doc (ValBindsIn mbinds sigs) = do -- rename the LHSes mbinds' <- mapBagM (rnBindLHS topP doc) mbinds return $ ValBindsIn mbinds' sigs rnValBindsLHSFromDoc _ _ _ b = pprPanic "rnValBindsLHSFromDoc" (ppr b) -- General version used both from the top-level and for local things -- Assumes the LHS vars are in scope -- -- Does not bind the local fixity declarations rnValBindsRHSGen :: (FreeVars -> FreeVars) -- for trimming free var sets -- The trimming function trims the free vars we attach to a -- binding so that it stays reasonably small -> [Name] -- names bound by the LHSes -> HsValBindsLR Name RdrName -> RnM (HsValBinds Name, DefUses) rnValBindsRHSGen trim bound_names (ValBindsIn mbinds sigs) = do -- rename the sigs env <- getGblEnv traceRn (ptext (sLit "Rename sigs") <+> ppr (tcg_rdr_env env)) sigs' <- renameSigs (Just (mkNameSet bound_names)) okBindSig sigs -- rename the RHSes binds_w_dus <- mapBagM (rnBind (mkSigTvFn sigs') trim) mbinds let (anal_binds, anal_dus) = depAnalBinds binds_w_dus (valbind', valbind'_dus) = (ValBindsOut anal_binds sigs', usesOnly (hsSigsFVs sigs') `plusDU` anal_dus) return (valbind', valbind'_dus) rnValBindsRHSGen _ _ b = pprPanic "rnValBindsRHSGen" (ppr b) -- Wrapper for local binds -- -- The *client* of this function is responsible for checking for unused binders; -- it doesn't (and can't: we don't have the thing inside the binds) happen here -- -- The client is also responsible for bringing the fixities into scope rnValBindsRHS :: [Name] -- names bound by the LHSes -> HsValBindsLR Name RdrName -> RnM (HsValBinds Name, DefUses) rnValBindsRHS bound_names binds = rnValBindsRHSGen (\ fvs -> -- only keep the names the names from this group intersectNameSet (mkNameSet bound_names) fvs) bound_names binds -- for local binds -- wrapper that does both the left- and right-hand sides -- -- here there are no local fixity decls passed in; -- the local fixity decls come from the ValBinds sigs rnValBindsAndThen :: HsValBinds RdrName -> (HsValBinds Name -> RnM (result, FreeVars)) -> RnM (result, FreeVars) rnValBindsAndThen binds@(ValBindsIn _ sigs) thing_inside = do { let (original_bndrs, doc) = bindersAndDoc binds -- (A) Create the local fixity environment ; new_fixities <- makeMiniFixityEnv [L loc sig | L loc (FixSig sig) <- sigs] -- (B) Rename the LHSes ; new_lhs <- rnValBindsLHSFromDoc_Local original_bndrs doc new_fixities binds ; let bound_names = map unLoc $ collectHsValBinders new_lhs -- ...and bring them (and their fixities) into scope ; bindLocalNamesFV_WithFixities bound_names new_fixities $ do { -- (C) Do the RHS and thing inside (binds', dus) <- rnValBindsRHS bound_names new_lhs ; (result, result_fvs) <- thing_inside binds' -- Report unused bindings based on the (accurate) -- findUses. E.g. -- let x = x in 3 -- should report 'x' unused ; let real_uses = findUses dus result_fvs ; warnUnusedLocalBinds bound_names real_uses ; let -- The variables "used" in the val binds are: -- (1) the uses of the binds (duUses) -- (2) the FVs of the thing-inside all_uses = duUses dus `plusFV` result_fvs -- Note [Unused binding hack] -- ~~~~~~~~~~~~~~~~~~~~~~~~~~ -- Note that *in contrast* to the above reporting of -- unused bindings, (1) above uses duUses to return *all* -- the uses, even if the binding is unused. Otherwise consider: -- x = 3 -- y = let p = x in 'x' -- NB: p not used -- If we don't "see" the dependency of 'y' on 'x', we may put the -- bindings in the wrong order, and the type checker will complain -- that x isn't in scope -- -- But note that this means we won't report 'x' as unused, -- whereas we would if we had { x = 3; p = x; y = 'x' } ; return (result, all_uses) }} -- The bound names are pruned out of all_uses -- by the bindLocalNamesFV call above rnValBindsAndThen bs _ = pprPanic "rnValBindsAndThen" (ppr bs) -- Process the fixity declarations, making a FastString -> (Located Fixity) map -- (We keep the location around for reporting duplicate fixity declarations.) -- -- Checks for duplicates, but not that only locally defined things are fixed. -- Note: for local fixity declarations, duplicates would also be checked in -- check_sigs below. But we also use this function at the top level. makeMiniFixityEnv :: [LFixitySig RdrName] -> RnM MiniFixityEnv makeMiniFixityEnv decls = foldlM add_one emptyFsEnv decls where add_one env (L loc (FixitySig (L name_loc name) fixity)) = do { -- this fixity decl is a duplicate iff -- the ReaderName's OccName's FastString is already in the env -- (we only need to check the local fix_env because -- definitions of non-local will be caught elsewhere) let { fs = occNameFS (rdrNameOcc name) ; fix_item = L loc fixity }; case lookupFsEnv env fs of Nothing -> return $ extendFsEnv env fs fix_item Just (L loc' _) -> do { setSrcSpan loc $ addLocErr (L name_loc name) (dupFixityDecl loc') ; return env} } dupFixityDecl :: SrcSpan -> RdrName -> SDoc dupFixityDecl loc rdr_name = vcat [ptext (sLit "Multiple fixity declarations for") <+> quotes (ppr rdr_name), ptext (sLit "also at ") <+> ppr loc] --------------------- -- renaming a single bind rnBindLHS :: NameMaker -> SDoc -> LHsBind RdrName -- returns the renamed left-hand side, -- and the FreeVars *of the LHS* -- (i.e., any free variables of the pattern) -> RnM (LHsBindLR Name RdrName) rnBindLHS name_maker _ (L loc (PatBind { pat_lhs = pat, pat_rhs = grhss, pat_rhs_ty=pat_rhs_ty })) = setSrcSpan loc $ do -- we don't actually use the FV processing of rnPatsAndThen here (pat',pat'_fvs) <- rnBindPat name_maker pat return (L loc (PatBind { pat_lhs = pat', pat_rhs = grhss, -- we temporarily store the pat's FVs here; -- gets updated to the FVs of the whole bind -- when doing the RHS below bind_fvs = pat'_fvs, -- these will get ignored in the next pass, -- when we rename the RHS pat_rhs_ty = pat_rhs_ty })) rnBindLHS name_maker _ (L loc (FunBind { fun_id = name@(L nameLoc _), fun_infix = inf, fun_matches = matches, fun_co_fn = fun_co_fn, fun_tick = fun_tick })) = setSrcSpan loc $ do { (newname, _fvs) <- applyNameMaker name_maker name $ \ newname -> return (newname, emptyFVs) ; return (L loc (FunBind { fun_id = L nameLoc newname, fun_infix = inf, fun_matches = matches, -- we temporatily store the LHS's FVs (empty in this case) here -- gets updated when doing the RHS below bind_fvs = emptyFVs, -- everything else will get ignored in the next pass fun_co_fn = fun_co_fn, fun_tick = fun_tick })) } rnBindLHS _ _ b = pprPanic "rnBindLHS" (ppr b) -- assumes the left-hands-side vars are in scope rnBind :: (Name -> [Name]) -- Signature tyvar function -> (FreeVars -> FreeVars) -- Trimming function for rhs free vars -> LHsBindLR Name RdrName -> RnM (LHsBind Name, [Name], Uses) rnBind _ trim (L loc (PatBind { pat_lhs = pat, pat_rhs = grhss, -- pat fvs were stored here while -- processing the LHS bind_fvs=pat_fvs })) = setSrcSpan loc $ do {let bndrs = collectPatBinders pat ; (grhss', fvs) <- rnGRHSs PatBindRhs grhss -- No scoped type variables for pattern bindings ; return (L loc (PatBind { pat_lhs = pat, pat_rhs = grhss', pat_rhs_ty = placeHolderType, bind_fvs = trim fvs }), bndrs, pat_fvs `plusFV` fvs) } rnBind sig_fn trim (L loc (FunBind { fun_id = name, fun_infix = inf, fun_matches = matches, -- no pattern FVs bind_fvs = _ })) -- invariant: no free vars here when it's a FunBind = setSrcSpan loc $ do { let plain_name = unLoc name ; (matches', fvs) <- bindSigTyVarsFV (sig_fn plain_name) $ -- bindSigTyVars tests for Opt_ScopedTyVars rnMatchGroup (FunRhs plain_name inf) matches ; checkPrecMatch inf plain_name matches' ; return (L loc (FunBind { fun_id = name, fun_infix = inf, fun_matches = matches', bind_fvs = trim fvs, fun_co_fn = idHsWrapper, fun_tick = Nothing }), [plain_name], fvs) } rnBind _ _ b = pprPanic "rnBind" (ppr b) --------------------- depAnalBinds :: Bag (LHsBind Name, [Name], Uses) -> ([(RecFlag, LHsBinds Name)], DefUses) -- Dependency analysis; this is important so that -- unused-binding reporting is accurate depAnalBinds binds_w_dus = (map get_binds sccs, map get_du sccs) where sccs = stronglyConnComp edges keyd_nodes = bagToList binds_w_dus `zip` [0::Int ..] edges = [ (node, key, [key | n <- nameSetToList uses, Just key <- [lookupNameEnv key_map n] ]) | (node@(_,_,uses), key) <- keyd_nodes ] key_map :: NameEnv Int -- Which binding it comes from key_map = mkNameEnv [(bndr, key) | ((_, bndrs, _), key) <- keyd_nodes , bndr <- bndrs ] get_binds (AcyclicSCC (bind, _, _)) = (NonRecursive, unitBag bind) get_binds (CyclicSCC binds_w_dus) = (Recursive, listToBag [b | (b,_,_) <- binds_w_dus]) get_du (AcyclicSCC (_, bndrs, uses)) = (Just (mkNameSet bndrs), uses) get_du (CyclicSCC binds_w_dus) = (Just defs, uses) where defs = mkNameSet [b | (_,bs,_) <- binds_w_dus, b <- bs] uses = unionManyNameSets [u | (_,_,u) <- binds_w_dus] --------------------- -- Bind the top-level forall'd type variables in the sigs. -- E.g f :: a -> a -- f = rhs -- The 'a' scopes over the rhs -- -- NB: there'll usually be just one (for a function binding) -- but if there are many, one may shadow the rest; too bad! -- e.g x :: [a] -> [a] -- y :: [(a,a)] -> a -- (x,y) = e -- In e, 'a' will be in scope, and it'll be the one from 'y'! mkSigTvFn :: [LSig Name] -> (Name -> [Name]) -- Return a lookup function that maps an Id Name to the names -- of the type variables that should scope over its body.. mkSigTvFn sigs = \n -> lookupNameEnv env n `orElse` [] where env :: NameEnv [Name] env = mkNameEnv [ (name, map hsLTyVarName ltvs) | L _ (TypeSig (L _ name) (L _ (HsForAllTy Explicit ltvs _ _))) <- sigs] -- Note the pattern-match on "Explicit"; we only bind -- type variables from signatures with an explicit top-level for-all \end{code} @rnMethodBinds@ is used for the method bindings of a class and an instance declaration. Like @rnBinds@ but without dependency analysis. NOTA BENE: we record each {\em binder} of a method-bind group as a free variable. That's crucial when dealing with an instance decl: \begin{verbatim} instance Foo (T a) where op x = ... \end{verbatim} This might be the {\em sole} occurrence of @op@ for an imported class @Foo@, and unless @op@ occurs we won't treat the type signature of @op@ in the class decl for @Foo@ as a source of instance-decl gates. But we should! Indeed, in many ways the @op@ in an instance decl is just like an occurrence, not a binder. \begin{code} rnMethodBinds :: Name -- Class name -> (Name -> [Name]) -- Signature tyvar function -> [Name] -- Names for generic type variables -> LHsBinds RdrName -> RnM (LHsBinds Name, FreeVars) rnMethodBinds cls sig_fn gen_tyvars binds = foldM do_one (emptyBag,emptyFVs) (bagToList binds) where do_one (binds,fvs) bind = do (bind', fvs_bind) <- rnMethodBind cls sig_fn gen_tyvars bind return (bind' `unionBags` binds, fvs_bind `plusFV` fvs) rnMethodBind :: Name -> (Name -> [Name]) -> [Name] -> LHsBindLR RdrName RdrName -> RnM (Bag (LHsBindLR Name Name), FreeVars) rnMethodBind cls sig_fn gen_tyvars (L loc (FunBind { fun_id = name, fun_infix = inf, fun_matches = MatchGroup matches _ })) = setSrcSpan loc $ do sel_name <- lookupInstDeclBndr cls name let plain_name = unLoc sel_name -- We use the selector name as the binder bindSigTyVarsFV (sig_fn plain_name) $ do (new_matches, fvs) <- mapFvRn (rn_match plain_name) matches let new_group = MatchGroup new_matches placeHolderType checkPrecMatch inf plain_name new_group return (unitBag (L loc (FunBind { fun_id = sel_name, fun_infix = inf, fun_matches = new_group, bind_fvs = fvs, fun_co_fn = idHsWrapper, fun_tick = Nothing })), fvs `addOneFV` plain_name) -- The 'fvs' field isn't used for method binds where -- Truly gruesome; bring into scope the correct members of the generic -- type variables. See comments in RnSource.rnSourceDecl(ClassDecl) rn_match sel_name match@(L _ (Match (L _ (TypePat ty) : _) _ _)) = extendTyVarEnvFVRn gen_tvs $ rnMatch (FunRhs sel_name inf) match where tvs = map (rdrNameOcc.unLoc) (extractHsTyRdrTyVars ty) gen_tvs = [tv | tv <- gen_tyvars, nameOccName tv `elem` tvs] rn_match sel_name match = rnMatch (FunRhs sel_name inf) match -- Can't handle method pattern-bindings which bind multiple methods. rnMethodBind _ _ _ mbind@(L _ (PatBind _ _ _ _)) = do addLocErr mbind methodBindErr return (emptyBag, emptyFVs) rnMethodBind _ _ _ b = pprPanic "rnMethodBind" (ppr b) \end{code} %************************************************************************ %* * \subsubsection[dep-Sigs]{Signatures (and user-pragmas for values)} %* * %************************************************************************ @renameSigs@ checks for: \begin{enumerate} \item more than one sig for one thing; \item signatures given for things not bound here; \end{enumerate} % At the moment we don't gather free-var info from the types in signatures. We'd only need this if we wanted to report unused tyvars. \begin{code} renameSigs :: Maybe NameSet -- If (Just ns) complain if the sig isn't for one of ns -> (Sig RdrName -> Bool) -- Complain about the wrong kind of signature if this is False -> [LSig RdrName] -> RnM [LSig Name] -- Renames the signatures and performs error checks renameSigs mb_names ok_sig sigs = do { let (good_sigs, bad_sigs) = partition (ok_sig . unLoc) sigs ; mapM_ unknownSigErr bad_sigs -- Misplaced ; mapM_ dupSigDeclErr (findDupsEq eqHsSig sigs) -- Duplicate ; sigs' <- mapM (wrapLocM (renameSig mb_names)) good_sigs ; return sigs' } ---------------------- -- We use lookupSigOccRn in the signatures, which is a little bit unsatisfactory -- because this won't work for: -- instance Foo T where -- {-# INLINE op #-} -- Baz.op = ... -- We'll just rename the INLINE prag to refer to whatever other 'op' -- is in scope. (I'm assuming that Baz.op isn't in scope unqualified.) -- Doesn't seem worth much trouble to sort this. renameSig :: Maybe NameSet -> Sig RdrName -> RnM (Sig Name) -- FixitySig is renamed elsewhere. renameSig mb_names sig@(TypeSig v ty) = do { new_v <- lookupSigOccRn mb_names sig v ; new_ty <- rnHsSigType (quotes (ppr v)) ty ; return (TypeSig new_v new_ty) } renameSig _ (SpecInstSig ty) = do { new_ty <- rnLHsType (text "A SPECIALISE instance pragma") ty ; return (SpecInstSig new_ty) } renameSig mb_names sig@(SpecSig v ty inl) = do { new_v <- lookupSigOccRn mb_names sig v ; new_ty <- rnHsSigType (quotes (ppr v)) ty ; return (SpecSig new_v new_ty inl) } renameSig mb_names sig@(InlineSig v s) = do { new_v <- lookupSigOccRn mb_names sig v ; return (InlineSig new_v s) } renameSig mb_names sig@(FixSig (FixitySig v f)) = do { new_v <- lookupSigOccRn mb_names sig v ; return (FixSig (FixitySig new_v f)) } -- lookupSigOccRn is used for type signatures and pragmas -- Is this valid? -- module A -- import M( f ) -- f :: Int -> Int -- f x = x -- It's clear that the 'f' in the signature must refer to A.f -- The Haskell98 report does not stipulate this, but it will! -- So we must treat the 'f' in the signature in the same way -- as the binding occurrence of 'f', using lookupBndrRn -- -- However, consider this case: -- import M( f ) -- f :: Int -> Int -- g x = x -- We don't want to say 'f' is out of scope; instead, we want to -- return the imported 'f', so that later on the reanamer will -- correctly report "misplaced type sig". lookupSigOccRn :: Maybe NameSet -> Sig RdrName -> Located RdrName -> RnM (Located Name) lookupSigOccRn mb_names sig (L loc v) = do { mb_n <- lookupBndrRn_maybe v ; case mb_n of { Just n -> case mb_names of { Nothing -> return (L loc n) ; Just ns | n `elemNameSet` ns -> return (L loc n) | otherwise -> bale_out_with local_msg } ; Nothing -> do { mb_n <- lookupGreRn_maybe v ; case mb_n of Just _ -> bale_out_with import_msg Nothing -> bale_out_with empty } }} where bale_out_with msg = do { addErr (sep [ ptext (sLit "The") <+> hsSigDoc sig <+> ptext (sLit "for") <+> quotes (ppr v) , nest 2 $ ptext (sLit "lacks an accompanying binding")] $$ nest 2 msg) ; return (L loc (mkUnboundName v)) } local_msg = parens $ ptext (sLit "The") <+> hsSigDoc sig <+> ptext (sLit "must be given where") <+> quotes (ppr v) <+> ptext (sLit "is declared") import_msg = parens $ ptext (sLit "You cannot give a") <+> hsSigDoc sig <+> ptext (sLit "an imported value") \end{code} %************************************************************************ %* * \subsection{Match} %* * %************************************************************************ \begin{code} rnMatchGroup :: HsMatchContext Name -> MatchGroup RdrName -> RnM (MatchGroup Name, FreeVars) rnMatchGroup ctxt (MatchGroup ms _) = do (new_ms, ms_fvs) <- mapFvRn (rnMatch ctxt) ms return (MatchGroup new_ms placeHolderType, ms_fvs) rnMatch :: HsMatchContext Name -> LMatch RdrName -> RnM (LMatch Name, FreeVars) rnMatch ctxt = wrapLocFstM (rnMatch' ctxt) rnMatch' :: HsMatchContext Name -> Match RdrName -> RnM (Match Name, FreeVars) rnMatch' ctxt match@(Match pats maybe_rhs_sig grhss) = do { -- Result type signatures are no longer supported case maybe_rhs_sig of Nothing -> return () Just ty -> addLocErr ty (resSigErr ctxt match) -- Now the main event -- note that there are no local ficity decls for matches ; rnPatsAndThen_LocalRightwards ctxt pats $ \ pats' -> do { (grhss', grhss_fvs) <- rnGRHSs ctxt grhss ; return (Match pats' Nothing grhss', grhss_fvs) }} -- The bindPatSigTyVarsFV and rnPatsAndThen will remove the bound FVs where resSigErr :: HsMatchContext Name -> Match RdrName -> HsType RdrName -> SDoc resSigErr ctxt match ty = vcat [ ptext (sLit "Illegal result type signature") <+> quotes (ppr ty) , nest 2 $ ptext (sLit "Result signatures are no longer supported in pattern matches") , pprMatchInCtxt ctxt match ] \end{code} %************************************************************************ %* * \subsubsection{Guarded right-hand sides (GRHSs)} %* * %************************************************************************ \begin{code} rnGRHSs :: HsMatchContext Name -> GRHSs RdrName -> RnM (GRHSs Name, FreeVars) rnGRHSs ctxt (GRHSs grhss binds) = rnLocalBindsAndThen binds $ \ binds' -> do (grhss', fvGRHSs) <- mapFvRn (rnGRHS ctxt) grhss return (GRHSs grhss' binds', fvGRHSs) rnGRHS :: HsMatchContext Name -> LGRHS RdrName -> RnM (LGRHS Name, FreeVars) rnGRHS ctxt = wrapLocFstM (rnGRHS' ctxt) rnGRHS' :: HsMatchContext Name -> GRHS RdrName -> RnM (GRHS Name, FreeVars) rnGRHS' ctxt (GRHS guards rhs) = do { pattern_guards_allowed <- doptM Opt_PatternGuards ; ((guards', rhs'), fvs) <- rnStmts (PatGuard ctxt) guards $ rnLExpr rhs ; unless (pattern_guards_allowed || is_standard_guard guards') (addWarn (nonStdGuardErr guards')) ; return (GRHS guards' rhs', fvs) } where -- Standard Haskell 1.4 guards are just a single boolean -- expression, rather than a list of qualifiers as in the -- Glasgow extension is_standard_guard [] = True is_standard_guard [L _ (ExprStmt _ _ _)] = True is_standard_guard _ = False \end{code} %************************************************************************ %* * \subsection{Error messages} %* * %************************************************************************ \begin{code} dupSigDeclErr :: [LSig RdrName] -> RnM () dupSigDeclErr sigs@(L loc sig : _) = addErrAt loc $ vcat [ptext (sLit "Duplicate") <+> what_it_is <> colon, nest 2 (vcat (map ppr_sig sigs))] where what_it_is = hsSigDoc sig ppr_sig (L loc sig) = ppr loc <> colon <+> ppr sig dupSigDeclErr [] = panic "dupSigDeclErr" unknownSigErr :: LSig RdrName -> RnM () unknownSigErr (L loc sig) = addErrAt loc $ sep [ptext (sLit "Misplaced") <+> hsSigDoc sig <> colon, ppr sig] methodBindErr :: HsBindLR RdrName RdrName -> SDoc methodBindErr mbind = hang (ptext (sLit "Pattern bindings (except simple variables) not allowed in instance declarations")) 2 (ppr mbind) bindsInHsBootFile :: LHsBindsLR Name RdrName -> SDoc bindsInHsBootFile mbinds = hang (ptext (sLit "Bindings in hs-boot files are not allowed")) 2 (ppr mbinds) nonStdGuardErr :: [LStmtLR Name Name] -> SDoc nonStdGuardErr guards = hang (ptext (sLit "accepting non-standard pattern guards (use -XPatternGuards to suppress this message)")) 4 (interpp'SP guards) \end{code}