2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[RnBinds]{Renaming and dependency analysis of bindings}
6 This module does renaming and dependency analysis on value bindings in
7 the abstract syntax. It does {\em not} do cycle-checks on class or
8 type-synonym declarations; those cannot be done at this stage because
9 they may be affected by renaming (which isn't fully worked out yet).
12 module RnBinds (rnTopBinds, rnTopBindsLHS, rnTopBindsRHS, -- use these for top-level bindings
13 rnLocalBindsAndThen, rnValBindsLHS, rnValBindsRHS, -- or these for local bindings
14 rnMethodBinds, renameSigs, mkSigTvFn,
15 rnMatchGroup, rnGRHSs,
16 makeMiniFixityEnv, MiniFixityEnv
19 import {-# SOURCE #-} RnExpr( rnLExpr, rnStmts )
25 import RnTypes ( rnHsSigType, rnLHsType, rnHsTypeFVs,checkPrecMatch)
26 import RnPat (rnPatsAndThen_LocalRightwards, rnBindPat,
27 NameMaker, localRecNameMaker, topRecNameMaker, applyNameMaker,
31 import DynFlags ( DynFlag(..) )
35 import PrelNames ( isUnboundName )
36 import RdrName ( RdrName, rdrNameOcc )
38 import ListSetOps ( findDupsEq )
39 import BasicTypes ( RecFlag(..) )
40 import Digraph ( SCC(..), stronglyConnComp )
44 import Maybes ( orElse )
45 import Util ( filterOut )
46 import Monad ( foldM, unless )
49 -- ToDo: Put the annotations into the monad, so that they arrive in the proper
50 -- place and can be used when complaining.
52 The code tree received by the function @rnBinds@ contains definitions
53 in where-clauses which are all apparently mutually recursive, but which may
54 not really depend upon each other. For example, in the top level program
59 the definitions of @a@ and @y@ do not depend on each other at all.
60 Unfortunately, the typechecker cannot always check such definitions.
61 \footnote{Mycroft, A. 1984. Polymorphic type schemes and recursive
62 definitions. In Proceedings of the International Symposium on Programming,
63 Toulouse, pp. 217-39. LNCS 167. Springer Verlag.}
64 However, the typechecker usually can check definitions in which only the
65 strongly connected components have been collected into recursive bindings.
66 This is precisely what the function @rnBinds@ does.
68 ToDo: deal with case where a single monobinds binds the same variable
71 The vertag tag is a unique @Int@; the tags only need to be unique
72 within one @MonoBinds@, so that unique-Int plumbing is done explicitly
73 (heavy monad machinery not needed).
76 %************************************************************************
78 %* naming conventions *
80 %************************************************************************
82 \subsection[name-conventions]{Name conventions}
84 The basic algorithm involves walking over the tree and returning a tuple
85 containing the new tree plus its free variables. Some functions, such
86 as those walking polymorphic bindings (HsBinds) and qualifier lists in
87 list comprehensions (@Quals@), return the variables bound in local
88 environments. These are then used to calculate the free variables of the
89 expression evaluated in these environments.
91 Conventions for variable names are as follows:
94 new code is given a prime to distinguish it from the old.
97 a set of variables defined in @Exp@ is written @dvExp@
100 a set of variables free in @Exp@ is written @fvExp@
103 %************************************************************************
105 %* analysing polymorphic bindings (HsBindGroup, HsBind)
107 %************************************************************************
109 \subsubsection[dep-HsBinds]{Polymorphic bindings}
111 Non-recursive expressions are reconstructed without any changes at top
112 level, although their component expressions may have to be altered.
113 However, non-recursive expressions are currently not expected as
114 \Haskell{} programs, and this code should not be executed.
116 Monomorphic bindings contain information that is returned in a tuple
117 (a @FlatMonoBinds@) containing:
121 a unique @Int@ that serves as the ``vertex tag'' for this binding.
124 the name of a function or the names in a pattern. These are a set
125 referred to as @dvLhs@, the defined variables of the left hand side.
128 the free variables of the body. These are referred to as @fvBody@.
131 the definition's actual code. This is referred to as just @code@.
134 The function @nonRecDvFv@ returns two sets of variables. The first is
135 the set of variables defined in the set of monomorphic bindings, while the
136 second is the set of free variables in those bindings.
138 The set of variables defined in a non-recursive binding is just the
139 union of all of them, as @union@ removes duplicates. However, the
140 free variables in each successive set of cumulative bindings is the
141 union of those in the previous set plus those of the newest binding after
142 the defined variables of the previous set have been removed.
144 @rnMethodBinds@ deals only with the declarations in class and
145 instance declarations. It expects only to see @FunMonoBind@s, and
146 it expects the global environment to contain bindings for the binders
147 (which are all class operations).
149 %************************************************************************
151 \subsubsection{ Top-level bindings}
153 %************************************************************************
156 -- for top-level bindings, we need to make top-level names,
157 -- so we have a different entry point than for local bindings
158 rnTopBindsLHS :: MiniFixityEnv
159 -> HsValBinds RdrName
160 -> RnM (HsValBindsLR Name RdrName)
161 rnTopBindsLHS fix_env binds =
162 (uncurry $ rnValBindsLHSFromDoc (topRecNameMaker fix_env)) (bindersAndDoc binds) binds
164 rnTopBindsRHS :: [Name] -- the names bound by these binds
165 -> HsValBindsLR Name RdrName
166 -> RnM (HsValBinds Name, DefUses)
167 rnTopBindsRHS bound_names binds =
168 do { is_boot <- tcIsHsBoot
170 then rnTopBindsBoot binds
171 else rnValBindsRHSGen (\x -> x) -- don't trim free vars
175 -- wrapper if we don't need to do anything in between the left and right,
176 -- or anything else in the scope of the left
178 -- never used when there are fixity declarations
179 rnTopBinds :: HsValBinds RdrName
180 -> RnM (HsValBinds Name, DefUses)
182 do nl <- rnTopBindsLHS emptyFsEnv b
183 let bound_names = map unLoc (collectHsValBinders nl)
184 bindLocalNames bound_names $ rnTopBindsRHS bound_names nl
187 rnTopBindsBoot :: HsValBindsLR Name RdrName -> RnM (HsValBinds Name, DefUses)
188 -- A hs-boot file has no bindings.
189 -- Return a single HsBindGroup with empty binds and renamed signatures
190 rnTopBindsBoot (ValBindsIn mbinds sigs)
191 = do { checkErr (isEmptyLHsBinds mbinds) (bindsInHsBootFile mbinds)
192 ; sigs' <- renameSigs okHsBootSig sigs
193 ; return (ValBindsOut [] sigs', usesOnly (hsSigsFVs sigs')) }
194 rnTopBindsBoot b = pprPanic "rnTopBindsBoot" (ppr b)
199 %*********************************************************
203 %*********************************************************
206 rnLocalBindsAndThen :: HsLocalBinds RdrName
207 -> (HsLocalBinds Name -> RnM (result, FreeVars))
208 -> RnM (result, FreeVars)
209 -- This version (a) assumes that the binding vars are *not* already in scope
210 -- (b) removes the binders from the free vars of the thing inside
211 -- The parser doesn't produce ThenBinds
212 rnLocalBindsAndThen EmptyLocalBinds thing_inside
213 = thing_inside EmptyLocalBinds
215 rnLocalBindsAndThen (HsValBinds val_binds) thing_inside
216 = rnValBindsAndThen val_binds $ \ val_binds' ->
217 thing_inside (HsValBinds val_binds')
219 rnLocalBindsAndThen (HsIPBinds binds) thing_inside = do
220 (binds',fv_binds) <- rnIPBinds binds
221 (thing, fvs_thing) <- thing_inside (HsIPBinds binds')
222 return (thing, fvs_thing `plusFV` fv_binds)
224 rnIPBinds :: HsIPBinds RdrName -> RnM (HsIPBinds Name, FreeVars)
225 rnIPBinds (IPBinds ip_binds _no_dict_binds) = do
226 (ip_binds', fvs_s) <- mapAndUnzipM (wrapLocFstM rnIPBind) ip_binds
227 return (IPBinds ip_binds' emptyLHsBinds, plusFVs fvs_s)
229 rnIPBind :: IPBind RdrName -> RnM (IPBind Name, FreeVars)
230 rnIPBind (IPBind n expr) = do
231 name <- newIPNameRn n
232 (expr',fvExpr) <- rnLExpr expr
233 return (IPBind name expr', fvExpr)
237 %************************************************************************
241 %************************************************************************
244 -- wrapper for local binds
245 -- creates the documentation info and calls the helper below
246 rnValBindsLHS :: MiniFixityEnv
247 -> HsValBinds RdrName
248 -> RnM (HsValBindsLR Name RdrName)
249 rnValBindsLHS fix_env binds =
250 let (boundNames,doc) = bindersAndDoc binds
251 in rnValBindsLHSFromDoc_Local boundNames doc fix_env binds
253 -- a helper used for local binds that does the duplicates check,
254 -- just so we don't forget to do it somewhere
255 rnValBindsLHSFromDoc_Local :: [Located RdrName] -- RdrNames of the LHS (so we don't have to gather them twice)
256 -> SDoc -- doc string for dup names and shadowing
258 -> HsValBinds RdrName
259 -> RnM (HsValBindsLR Name RdrName)
261 rnValBindsLHSFromDoc_Local boundNames doc fix_env binds = do
262 -- Do error checking: we need to check for dups here because we
263 -- don't don't bind all of the variables from the ValBinds at once
264 -- with bindLocatedLocals any more.
265 checkDupAndShadowedRdrNames doc boundNames
267 -- (Note that we don't want to do this at the top level, since
268 -- sorting out duplicates and shadowing there happens elsewhere.
269 -- The behavior is even different. For example,
272 -- should not produce a shadowing warning (but it will produce
273 -- an ambiguity warning if you use f), but
275 -- g = let f = ... in f
277 rnValBindsLHSFromDoc (localRecNameMaker fix_env) boundNames doc binds
279 bindersAndDoc :: HsValBinds RdrName -> ([Located RdrName], SDoc)
280 bindersAndDoc binds =
282 -- the unrenamed bndrs for error checking and reporting
283 orig = collectHsValBinders binds
284 doc = text "In the binding group for:" <+> pprWithCommas ppr (map unLoc orig)
288 -- renames the left-hand sides
289 -- generic version used both at the top level and for local binds
290 -- does some error checking, but not what gets done elsewhere at the top level
291 rnValBindsLHSFromDoc :: NameMaker
292 -> [Located RdrName] -- RdrNames of the LHS (so we don't have to gather them twice)
293 -> SDoc -- doc string for dup names and shadowing
294 -> HsValBinds RdrName
295 -> RnM (HsValBindsLR Name RdrName)
296 rnValBindsLHSFromDoc topP _original_bndrs doc (ValBindsIn mbinds sigs) = do
298 mbinds' <- mapBagM (rnBindLHS topP doc) mbinds
299 return $ ValBindsIn mbinds' sigs
300 rnValBindsLHSFromDoc _ _ _ b = pprPanic "rnValBindsLHSFromDoc" (ppr b)
302 -- assumes the LHS vars are in scope
303 -- general version used both from the top-level and for local things
305 -- does not bind the local fixity declarations
306 rnValBindsRHSGen :: (FreeVars -> FreeVars) -- for trimming free var sets
307 -- The trimming function trims the free vars we attach to a
308 -- binding so that it stays reasonably small
309 -> [Name] -- names bound by the LHSes
310 -> HsValBindsLR Name RdrName
311 -> RnM (HsValBinds Name, DefUses)
313 rnValBindsRHSGen trim _bound_names (ValBindsIn mbinds sigs) = do
316 traceRn (ptext (sLit "Rename sigs") <+> ppr (tcg_rdr_env env))
317 sigs' <- rename_sigs sigs
319 binds_w_dus <- mapBagM (rnBind (mkSigTvFn sigs') trim) mbinds
320 let (anal_binds, anal_dus) = depAnalBinds binds_w_dus
321 (valbind', valbind'_dus) = (ValBindsOut anal_binds sigs',
322 usesOnly (hsSigsFVs sigs') `plusDU` anal_dus)
323 -- We do the check-sigs after renaming the bindings,
324 -- so that we have convenient access to the binders
325 check_sigs (okBindSig (duDefs anal_dus)) sigs'
326 return (valbind', valbind'_dus)
328 rnValBindsRHSGen _ _ b = pprPanic "rnValBindsRHSGen" (ppr b)
330 -- Wrapper for local binds
332 -- The *client* of this function is responsible for checking for unused binders;
333 -- it doesn't (and can't: we don't have the thing inside the binds) happen here
335 -- The client is also responsible for bringing the fixities into scope
336 rnValBindsRHS :: [Name] -- names bound by the LHSes
337 -> HsValBindsLR Name RdrName
338 -> RnM (HsValBinds Name, DefUses)
339 rnValBindsRHS bound_names binds =
340 rnValBindsRHSGen (\ fvs -> -- only keep the names the names from this group
341 intersectNameSet (mkNameSet bound_names) fvs) bound_names binds
345 -- wrapper that does both the left- and right-hand sides
347 -- here there are no local fixity decls passed in;
348 -- the local fixity decls come from the ValBinds sigs
349 rnValBindsAndThen :: HsValBinds RdrName
350 -> (HsValBinds Name -> RnM (result, FreeVars))
351 -> RnM (result, FreeVars)
352 rnValBindsAndThen binds@(ValBindsIn _ sigs) thing_inside
353 = do { let (original_bndrs, doc) = bindersAndDoc binds
355 -- (A) Create the local fixity environment
356 ; new_fixities <- makeMiniFixityEnv [L loc sig | L loc (FixSig sig) <- sigs]
358 -- (B) Rename the LHSes
359 ; new_lhs <- rnValBindsLHSFromDoc_Local original_bndrs doc new_fixities binds
360 ; let bound_names = map unLoc $ collectHsValBinders new_lhs
362 -- ...and bring them (and their fixities) into scope
363 ; bindLocalNamesFV_WithFixities bound_names new_fixities $ do
365 { -- (C) Do the RHS and thing inside
366 (binds', dus) <- rnValBindsRHS bound_names new_lhs
367 ; (result, result_fvs) <- thing_inside binds'
369 -- Report unused bindings based on the (accurate)
372 -- should report 'x' unused
373 ; let real_uses = findUses dus result_fvs
374 ; warnUnusedLocalBinds bound_names real_uses
377 -- The variables "used" in the val binds are:
378 -- (1) the uses of the binds (duUses)
379 -- (2) the FVs of the thing-inside
380 all_uses = duUses dus `plusFV` result_fvs
381 -- Note [Unused binding hack]
382 -- ~~~~~~~~~~~~~~~~~~~~~~~~~~
383 -- Note that *in contrast* to the above reporting of
384 -- unused bindings, (1) above uses duUses to return *all*
385 -- the uses, even if the binding is unused. Otherwise consider:
387 -- y = let p = x in 'x' -- NB: p not used
388 -- If we don't "see" the dependency of 'y' on 'x', we may put the
389 -- bindings in the wrong order, and the type checker will complain
390 -- that x isn't in scope
392 -- But note that this means we won't report 'x' as unused,
393 -- whereas we would if we had { x = 3; p = x; y = 'x' }
395 ; return (result, all_uses) }}
396 -- The bound names are pruned out of all_uses
397 -- by the bindLocalNamesFV call above
399 rnValBindsAndThen bs _ = pprPanic "rnValBindsAndThen" (ppr bs)
402 -- Process the fixity declarations, making a FastString -> (Located Fixity) map
403 -- (We keep the location around for reporting duplicate fixity declarations.)
405 -- Checks for duplicates, but not that only locally defined things are fixed.
406 -- Note: for local fixity declarations, duplicates would also be checked in
407 -- check_sigs below. But we also use this function at the top level.
409 makeMiniFixityEnv :: [LFixitySig RdrName] -> RnM MiniFixityEnv
411 makeMiniFixityEnv decls = foldlM add_one emptyFsEnv decls
413 add_one env (L loc (FixitySig (L name_loc name) fixity)) = do
414 { -- this fixity decl is a duplicate iff
415 -- the ReaderName's OccName's FastString is already in the env
416 -- (we only need to check the local fix_env because
417 -- definitions of non-local will be caught elsewhere)
418 let { fs = occNameFS (rdrNameOcc name)
419 ; fix_item = L loc fixity };
421 case lookupFsEnv env fs of
422 Nothing -> return $ extendFsEnv env fs fix_item
423 Just (L loc' _) -> do
425 addLocErr (L name_loc name) (dupFixityDecl loc')
429 dupFixityDecl :: SrcSpan -> RdrName -> SDoc
430 dupFixityDecl loc rdr_name
431 = vcat [ptext (sLit "Multiple fixity declarations for") <+> quotes (ppr rdr_name),
432 ptext (sLit "also at ") <+> ppr loc]
434 ---------------------
436 -- renaming a single bind
438 rnBindLHS :: NameMaker
441 -- returns the renamed left-hand side,
442 -- and the FreeVars *of the LHS*
443 -- (i.e., any free variables of the pattern)
444 -> RnM (LHsBindLR Name RdrName)
446 rnBindLHS name_maker _ (L loc (PatBind { pat_lhs = pat,
448 pat_rhs_ty=pat_rhs_ty
450 = setSrcSpan loc $ do
451 -- we don't actually use the FV processing of rnPatsAndThen here
452 (pat',pat'_fvs) <- rnBindPat name_maker pat
453 return (L loc (PatBind { pat_lhs = pat',
455 -- we temporarily store the pat's FVs here;
456 -- gets updated to the FVs of the whole bind
457 -- when doing the RHS below
459 -- these will get ignored in the next pass,
460 -- when we rename the RHS
461 pat_rhs_ty = pat_rhs_ty }))
463 rnBindLHS name_maker _ (L loc (FunBind { fun_id = name@(L nameLoc _),
465 fun_matches = matches,
466 fun_co_fn = fun_co_fn,
470 do { (newname, _fvs) <- applyNameMaker name_maker name $ \ newname ->
471 return (newname, emptyFVs)
472 ; return (L loc (FunBind { fun_id = L nameLoc newname,
474 fun_matches = matches,
475 -- we temporatily store the LHS's FVs (empty in this case) here
476 -- gets updated when doing the RHS below
478 -- everything else will get ignored in the next pass
479 fun_co_fn = fun_co_fn,
483 rnBindLHS _ _ b = pprPanic "rnBindLHS" (ppr b)
485 -- assumes the left-hands-side vars are in scope
486 rnBind :: (Name -> [Name]) -- Signature tyvar function
487 -> (FreeVars -> FreeVars) -- Trimming function for rhs free vars
488 -> LHsBindLR Name RdrName
489 -> RnM (LHsBind Name, [Name], Uses)
490 rnBind _ trim (L loc (PatBind { pat_lhs = pat,
492 -- pat fvs were stored here while
493 -- processing the LHS
496 do {let bndrs = collectPatBinders pat
498 ; (grhss', fvs) <- rnGRHSs PatBindRhs grhss
499 -- No scoped type variables for pattern bindings
501 ; return (L loc (PatBind { pat_lhs = pat,
503 pat_rhs_ty = placeHolderType,
504 bind_fvs = trim fvs }),
505 bndrs, pat_fvs `plusFV` fvs) }
509 (L loc (FunBind { fun_id = name,
511 fun_matches = matches,
515 -- invariant: no free vars here when it's a FunBind
517 do { let plain_name = unLoc name
519 ; (matches', fvs) <- bindSigTyVarsFV (sig_fn plain_name) $
520 -- bindSigTyVars tests for Opt_ScopedTyVars
521 rnMatchGroup (FunRhs plain_name inf) matches
523 ; checkPrecMatch inf plain_name matches'
525 ; return (L loc (FunBind { fun_id = name,
527 fun_matches = matches',
529 fun_co_fn = idHsWrapper,
530 fun_tick = Nothing }),
534 rnBind _ _ b = pprPanic "rnBind" (ppr b)
536 ---------------------
537 depAnalBinds :: Bag (LHsBind Name, [Name], Uses)
538 -> ([(RecFlag, LHsBinds Name)], DefUses)
539 -- Dependency analysis; this is important so that
540 -- unused-binding reporting is accurate
541 depAnalBinds binds_w_dus
542 = (map get_binds sccs, map get_du sccs)
544 sccs = stronglyConnComp edges
546 keyd_nodes = bagToList binds_w_dus `zip` [0::Int ..]
548 edges = [ (node, key, [key | n <- nameSetToList uses,
549 Just key <- [lookupNameEnv key_map n] ])
550 | (node@(_,_,uses), key) <- keyd_nodes ]
552 key_map :: NameEnv Int -- Which binding it comes from
553 key_map = mkNameEnv [(bndr, key) | ((_, bndrs, _), key) <- keyd_nodes
556 get_binds (AcyclicSCC (bind, _, _)) = (NonRecursive, unitBag bind)
557 get_binds (CyclicSCC binds_w_dus) = (Recursive, listToBag [b | (b,_,_) <- binds_w_dus])
559 get_du (AcyclicSCC (_, bndrs, uses)) = (Just (mkNameSet bndrs), uses)
560 get_du (CyclicSCC binds_w_dus) = (Just defs, uses)
562 defs = mkNameSet [b | (_,bs,_) <- binds_w_dus, b <- bs]
563 uses = unionManyNameSets [u | (_,_,u) <- binds_w_dus]
566 ---------------------
567 -- Bind the top-level forall'd type variables in the sigs.
570 -- The 'a' scopes over the rhs
572 -- NB: there'll usually be just one (for a function binding)
573 -- but if there are many, one may shadow the rest; too bad!
574 -- e.g x :: [a] -> [a]
577 -- In e, 'a' will be in scope, and it'll be the one from 'y'!
579 mkSigTvFn :: [LSig Name] -> (Name -> [Name])
580 -- Return a lookup function that maps an Id Name to the names
581 -- of the type variables that should scope over its body..
583 = \n -> lookupNameEnv env n `orElse` []
585 env :: NameEnv [Name]
586 env = mkNameEnv [ (name, map hsLTyVarName ltvs)
587 | L _ (TypeSig (L _ name)
588 (L _ (HsForAllTy Explicit ltvs _ _))) <- sigs]
589 -- Note the pattern-match on "Explicit"; we only bind
590 -- type variables from signatures with an explicit top-level for-all
594 @rnMethodBinds@ is used for the method bindings of a class and an instance
595 declaration. Like @rnBinds@ but without dependency analysis.
597 NOTA BENE: we record each {\em binder} of a method-bind group as a free variable.
598 That's crucial when dealing with an instance decl:
600 instance Foo (T a) where
603 This might be the {\em sole} occurrence of @op@ for an imported class @Foo@,
604 and unless @op@ occurs we won't treat the type signature of @op@ in the class
605 decl for @Foo@ as a source of instance-decl gates. But we should! Indeed,
606 in many ways the @op@ in an instance decl is just like an occurrence, not
610 rnMethodBinds :: Name -- Class name
611 -> (Name -> [Name]) -- Signature tyvar function
612 -> [Name] -- Names for generic type variables
614 -> RnM (LHsBinds Name, FreeVars)
616 rnMethodBinds cls sig_fn gen_tyvars binds
617 = foldM do_one (emptyBag,emptyFVs) (bagToList binds)
618 where do_one (binds,fvs) bind = do
619 (bind', fvs_bind) <- rnMethodBind cls sig_fn gen_tyvars bind
620 return (bind' `unionBags` binds, fvs_bind `plusFV` fvs)
625 -> LHsBindLR RdrName RdrName
626 -> RnM (Bag (LHsBindLR Name Name), FreeVars)
627 rnMethodBind cls sig_fn gen_tyvars (L loc (FunBind { fun_id = name, fun_infix = inf,
628 fun_matches = MatchGroup matches _ }))
629 = setSrcSpan loc $ do
630 sel_name <- lookupInstDeclBndr cls name
631 let plain_name = unLoc sel_name
632 -- We use the selector name as the binder
634 bindSigTyVarsFV (sig_fn plain_name) $ do
635 (new_matches, fvs) <- mapFvRn (rn_match plain_name) matches
637 new_group = MatchGroup new_matches placeHolderType
639 checkPrecMatch inf plain_name new_group
640 return (unitBag (L loc (FunBind {
641 fun_id = sel_name, fun_infix = inf,
642 fun_matches = new_group,
643 bind_fvs = fvs, fun_co_fn = idHsWrapper,
644 fun_tick = Nothing })),
645 fvs `addOneFV` plain_name)
646 -- The 'fvs' field isn't used for method binds
648 -- Truly gruesome; bring into scope the correct members of the generic
649 -- type variables. See comments in RnSource.rnSourceDecl(ClassDecl)
650 rn_match sel_name match@(L _ (Match (L _ (TypePat ty) : _) _ _))
651 = extendTyVarEnvFVRn gen_tvs $
652 rnMatch (FunRhs sel_name inf) match
654 tvs = map (rdrNameOcc.unLoc) (extractHsTyRdrTyVars ty)
655 gen_tvs = [tv | tv <- gen_tyvars, nameOccName tv `elem` tvs]
657 rn_match sel_name match = rnMatch (FunRhs sel_name inf) match
660 -- Can't handle method pattern-bindings which bind multiple methods.
661 rnMethodBind _ _ _ mbind@(L _ (PatBind _ _ _ _)) = do
662 addLocErr mbind methodBindErr
663 return (emptyBag, emptyFVs)
665 rnMethodBind _ _ _ b = pprPanic "rnMethodBind" (ppr b)
670 %************************************************************************
672 \subsubsection[dep-Sigs]{Signatures (and user-pragmas for values)}
674 %************************************************************************
676 @renameSigs@ checks for:
678 \item more than one sig for one thing;
679 \item signatures given for things not bound here;
680 \item with suitably flaggery, that all top-level things have type signatures.
683 At the moment we don't gather free-var info from the types in
684 signatures. We'd only need this if we wanted to report unused tyvars.
687 renameSigs :: (LSig Name -> Bool) -> [LSig RdrName] -> RnM [LSig Name]
688 -- Renames the signatures and performs error checks
689 renameSigs ok_sig sigs
690 = do { sigs' <- rename_sigs sigs
691 ; check_sigs ok_sig sigs'
694 ----------------------
695 rename_sigs :: [LSig RdrName] -> RnM [LSig Name]
696 rename_sigs sigs = mapM (wrapLocM renameSig) sigs
698 ----------------------
699 check_sigs :: (LSig Name -> Bool) -> [LSig Name] -> RnM ()
700 -- Used for class and instance decls, as well as regular bindings
701 check_sigs ok_sig sigs = do
702 -- Check for (a) duplicate signatures
703 -- (b) signatures for things not in this group = do
704 traceRn (text "SIGS" <+> ppr sigs)
705 mapM_ unknownSigErr (filter (not . ok_sig) sigs')
706 mapM_ dupSigDeclErr (findDupsEq eqHsSig sigs')
708 -- Don't complain about an unbound name again
709 sigs' = filterOut bad_name sigs
710 bad_name sig = case sigName sig of
711 Just n -> isUnboundName n
714 -- We use lookupLocatedSigOccRn in the signatures, which is a little bit unsatisfactory
715 -- because this won't work for:
716 -- instance Foo T where
719 -- We'll just rename the INLINE prag to refer to whatever other 'op'
720 -- is in scope. (I'm assuming that Baz.op isn't in scope unqualified.)
721 -- Doesn't seem worth much trouble to sort this.
723 renameSig :: Sig RdrName -> RnM (Sig Name)
724 -- FixitSig is renamed elsewhere.
725 renameSig (TypeSig v ty) = do
726 new_v <- lookupLocatedSigOccRn v
727 new_ty <- rnHsSigType (quotes (ppr v)) ty
728 return (TypeSig new_v new_ty)
730 renameSig (SpecInstSig ty) = do
731 new_ty <- rnLHsType (text "A SPECIALISE instance pragma") ty
732 return (SpecInstSig new_ty)
734 renameSig (SpecSig v ty inl) = do
735 new_v <- lookupLocatedSigOccRn v
736 new_ty <- rnHsSigType (quotes (ppr v)) ty
737 return (SpecSig new_v new_ty inl)
739 renameSig (InlineSig v s) = do
740 new_v <- lookupLocatedSigOccRn v
741 return (InlineSig new_v s)
743 renameSig (FixSig (FixitySig v f)) = do
744 new_v <- lookupLocatedSigOccRn v
745 return (FixSig (FixitySig new_v f))
749 ************************************************************************
753 ************************************************************************
756 rnMatchGroup :: HsMatchContext Name -> MatchGroup RdrName -> RnM (MatchGroup Name, FreeVars)
757 rnMatchGroup ctxt (MatchGroup ms _) = do
758 (new_ms, ms_fvs) <- mapFvRn (rnMatch ctxt) ms
759 return (MatchGroup new_ms placeHolderType, ms_fvs)
761 rnMatch :: HsMatchContext Name -> LMatch RdrName -> RnM (LMatch Name, FreeVars)
762 rnMatch ctxt = wrapLocFstM (rnMatch' ctxt)
764 rnMatch' :: HsMatchContext Name -> Match RdrName -> RnM (Match Name, FreeVars)
765 rnMatch' ctxt (Match pats maybe_rhs_sig grhss)
767 -- Deal with the rhs type signature
768 bindPatSigTyVarsFV rhs_sig_tys $ do
769 opt_PatternSignatures <- doptM Opt_PatternSignatures
770 (maybe_rhs_sig', ty_fvs) <-
771 case maybe_rhs_sig of
772 Nothing -> return (Nothing, emptyFVs)
773 Just ty | opt_PatternSignatures -> do (ty', ty_fvs) <- rnHsTypeFVs doc_sig ty
774 return (Just ty', ty_fvs)
775 | otherwise -> do addLocErr ty patSigErr
776 return (Nothing, emptyFVs)
778 -- Now the main event
779 -- note that there are no local ficity decls for matches
780 rnPatsAndThen_LocalRightwards ctxt pats $ \ pats' -> do
781 (grhss', grhss_fvs) <- rnGRHSs ctxt grhss
783 return (Match pats' maybe_rhs_sig' grhss', grhss_fvs `plusFV` ty_fvs)
784 -- The bindPatSigTyVarsFV and rnPatsAndThen will remove the bound FVs
786 rhs_sig_tys = case maybe_rhs_sig of
789 doc_sig = text "In a result type-signature"
793 %************************************************************************
795 \subsubsection{Guarded right-hand sides (GRHSs)}
797 %************************************************************************
800 rnGRHSs :: HsMatchContext Name -> GRHSs RdrName -> RnM (GRHSs Name, FreeVars)
802 rnGRHSs ctxt (GRHSs grhss binds)
803 = rnLocalBindsAndThen binds $ \ binds' -> do
804 (grhss', fvGRHSs) <- mapFvRn (rnGRHS ctxt) grhss
805 return (GRHSs grhss' binds', fvGRHSs)
807 rnGRHS :: HsMatchContext Name -> LGRHS RdrName -> RnM (LGRHS Name, FreeVars)
808 rnGRHS ctxt = wrapLocFstM (rnGRHS' ctxt)
810 rnGRHS' :: HsMatchContext Name -> GRHS RdrName -> RnM (GRHS Name, FreeVars)
811 rnGRHS' ctxt (GRHS guards rhs)
812 = do { pattern_guards_allowed <- doptM Opt_PatternGuards
813 ; ((guards', rhs'), fvs) <- rnStmts (PatGuard ctxt) guards $
816 ; unless (pattern_guards_allowed || is_standard_guard guards')
817 (addWarn (nonStdGuardErr guards'))
819 ; return (GRHS guards' rhs', fvs) }
821 -- Standard Haskell 1.4 guards are just a single boolean
822 -- expression, rather than a list of qualifiers as in the
824 is_standard_guard [] = True
825 is_standard_guard [L _ (ExprStmt _ _ _)] = True
826 is_standard_guard _ = False
829 %************************************************************************
831 \subsection{Error messages}
833 %************************************************************************
836 dupSigDeclErr :: [LSig Name] -> RnM ()
837 dupSigDeclErr sigs@(L loc sig : _)
839 vcat [ptext (sLit "Duplicate") <+> what_it_is <> colon,
840 nest 2 (vcat (map ppr_sig sigs))]
842 what_it_is = hsSigDoc sig
843 ppr_sig (L loc sig) = ppr loc <> colon <+> ppr sig
844 dupSigDeclErr [] = panic "dupSigDeclErr"
846 unknownSigErr :: LSig Name -> RnM ()
847 unknownSigErr (L loc sig)
848 = do { mod <- getModule
850 vcat [sep [ptext (sLit "Misplaced") <+> what_it_is <> colon, ppr sig],
851 extra_stuff mod sig] }
853 what_it_is = hsSigDoc sig
854 extra_stuff mod (TypeSig (L _ n) _)
855 | nameIsLocalOrFrom mod n
856 = ptext (sLit "The type signature must be given where")
857 <+> quotes (ppr n) <+> ptext (sLit "is declared")
859 = ptext (sLit "You cannot give a type signature for an imported value")
861 extra_stuff _ _ = empty
863 methodBindErr :: HsBindLR RdrName RdrName -> SDoc
865 = hang (ptext (sLit "Pattern bindings (except simple variables) not allowed in instance declarations"))
868 bindsInHsBootFile :: LHsBindsLR Name RdrName -> SDoc
869 bindsInHsBootFile mbinds
870 = hang (ptext (sLit "Bindings in hs-boot files are not allowed"))
873 nonStdGuardErr :: [LStmtLR Name Name] -> SDoc
874 nonStdGuardErr guards
875 = hang (ptext (sLit "accepting non-standard pattern guards (use -XPatternGuards to suppress this message)"))
876 4 (interpp'SP guards)