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).
13 -- The above warning supression flag is a temporary kludge.
14 -- While working on this module you are encouraged to remove it and fix
15 -- any warnings in the module. See
16 -- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
19 module RnBinds (rnTopBinds, rnTopBindsLHS, rnTopBindsRHS, -- use these for top-level bindings
20 rnLocalBindsAndThen, rnValBindsLHS, rnValBindsRHS, -- or these for local bindings
21 rnMethodBinds, renameSigs, mkSigTvFn,
22 rnMatchGroup, rnGRHSs,
26 #include "HsVersions.h"
28 import {-# SOURCE #-} RnExpr( rnLExpr, rnStmts )
34 import RnTypes ( rnHsSigType, rnLHsType, rnHsTypeFVs,checkPrecMatch)
35 import RnPat (rnPatsAndThen_LocalRightwards, rnPat_LocalRec, rnPat_TopRec,
36 NameMaker, localNameMaker, topNameMaker, applyNameMaker,
39 import RnEnv ( lookupLocatedBndrRn,
40 lookupInstDeclBndr, newIPNameRn,
41 lookupLocatedSigOccRn, bindPatSigTyVarsFV,
42 bindLocalFixities, bindSigTyVarsFV,
43 warnUnusedLocalBinds, mapFvRn, extendTyVarEnvFVRn,
44 bindLocatedLocalsFV, bindLocalNames, bindLocalNamesFV,
45 bindLocalNamesFV_WithFixities,
47 checkDupNames, checkShadowing
49 import DynFlags ( DynFlag(..) )
50 import HscTypes (FixItem(..))
55 import PrelNames ( isUnboundName )
56 import RdrName ( RdrName, rdrNameOcc )
57 import SrcLoc ( Located(..), unLoc, noLoc )
58 import ListSetOps ( findDupsEq )
59 import BasicTypes ( RecFlag(..) )
60 import Digraph ( SCC(..), stronglyConnComp )
63 import Maybes ( orElse )
64 import Util ( filterOut )
65 import Monad ( foldM )
68 -- ToDo: Put the annotations into the monad, so that they arrive in the proper
69 -- place and can be used when complaining.
71 The code tree received by the function @rnBinds@ contains definitions
72 in where-clauses which are all apparently mutually recursive, but which may
73 not really depend upon each other. For example, in the top level program
78 the definitions of @a@ and @y@ do not depend on each other at all.
79 Unfortunately, the typechecker cannot always check such definitions.
80 \footnote{Mycroft, A. 1984. Polymorphic type schemes and recursive
81 definitions. In Proceedings of the International Symposium on Programming,
82 Toulouse, pp. 217-39. LNCS 167. Springer Verlag.}
83 However, the typechecker usually can check definitions in which only the
84 strongly connected components have been collected into recursive bindings.
85 This is precisely what the function @rnBinds@ does.
87 ToDo: deal with case where a single monobinds binds the same variable
90 The vertag tag is a unique @Int@; the tags only need to be unique
91 within one @MonoBinds@, so that unique-Int plumbing is done explicitly
92 (heavy monad machinery not needed).
95 %************************************************************************
97 %* naming conventions *
99 %************************************************************************
101 \subsection[name-conventions]{Name conventions}
103 The basic algorithm involves walking over the tree and returning a tuple
104 containing the new tree plus its free variables. Some functions, such
105 as those walking polymorphic bindings (HsBinds) and qualifier lists in
106 list comprehensions (@Quals@), return the variables bound in local
107 environments. These are then used to calculate the free variables of the
108 expression evaluated in these environments.
110 Conventions for variable names are as follows:
113 new code is given a prime to distinguish it from the old.
116 a set of variables defined in @Exp@ is written @dvExp@
119 a set of variables free in @Exp@ is written @fvExp@
122 %************************************************************************
124 %* analysing polymorphic bindings (HsBindGroup, HsBind)
126 %************************************************************************
128 \subsubsection[dep-HsBinds]{Polymorphic bindings}
130 Non-recursive expressions are reconstructed without any changes at top
131 level, although their component expressions may have to be altered.
132 However, non-recursive expressions are currently not expected as
133 \Haskell{} programs, and this code should not be executed.
135 Monomorphic bindings contain information that is returned in a tuple
136 (a @FlatMonoBinds@) containing:
140 a unique @Int@ that serves as the ``vertex tag'' for this binding.
143 the name of a function or the names in a pattern. These are a set
144 referred to as @dvLhs@, the defined variables of the left hand side.
147 the free variables of the body. These are referred to as @fvBody@.
150 the definition's actual code. This is referred to as just @code@.
153 The function @nonRecDvFv@ returns two sets of variables. The first is
154 the set of variables defined in the set of monomorphic bindings, while the
155 second is the set of free variables in those bindings.
157 The set of variables defined in a non-recursive binding is just the
158 union of all of them, as @union@ removes duplicates. However, the
159 free variables in each successive set of cumulative bindings is the
160 union of those in the previous set plus those of the newest binding after
161 the defined variables of the previous set have been removed.
163 @rnMethodBinds@ deals only with the declarations in class and
164 instance declarations. It expects only to see @FunMonoBind@s, and
165 it expects the global environment to contain bindings for the binders
166 (which are all class operations).
168 %************************************************************************
170 \subsubsection{ Top-level bindings}
172 %************************************************************************
175 -- for top-level bindings, we need to make top-level names,
176 -- so we have a different entry point than for local bindings
177 rnTopBindsLHS :: UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
178 -- these fixities need to be brought into scope with the names
179 -> HsValBinds RdrName
180 -> RnM (HsValBindsLR Name RdrName)
181 rnTopBindsLHS fix_env binds =
182 (uncurry $ rnValBindsLHSFromDoc True) (bindersAndDoc binds) fix_env binds
184 rnTopBindsRHS :: [Name] -- the names bound by these binds
185 -> HsValBindsLR Name RdrName
186 -> RnM (HsValBinds Name, DefUses)
187 rnTopBindsRHS bound_names binds =
188 do { is_boot <- tcIsHsBoot
190 then rnTopBindsBoot binds
191 else rnValBindsRHSGen (\x -> x) -- don't trim free vars
195 -- wrapper if we don't need to do anything in between the left and right,
196 -- or anything else in the scope of the left
198 -- never used when there are fixity declarations
199 rnTopBinds :: HsValBinds RdrName
200 -> RnM (HsValBinds Name, DefUses)
202 do nl <- rnTopBindsLHS emptyUFM b
203 let bound_names = map unLoc (collectHsValBinders nl)
204 bindLocalNames bound_names $ rnTopBindsRHS bound_names nl
207 rnTopBindsBoot :: HsValBindsLR Name RdrName -> RnM (HsValBinds Name, DefUses)
208 -- A hs-boot file has no bindings.
209 -- Return a single HsBindGroup with empty binds and renamed signatures
210 rnTopBindsBoot (ValBindsIn mbinds sigs)
211 = do { checkErr (isEmptyLHsBinds mbinds) (bindsInHsBootFile mbinds)
212 ; sigs' <- renameSigs okHsBootSig sigs
213 ; return (ValBindsOut [] sigs', usesOnly (hsSigsFVs sigs')) }
218 %*********************************************************
222 %*********************************************************
225 rnLocalBindsAndThen :: HsLocalBinds RdrName
226 -> (HsLocalBinds Name -> RnM (result, FreeVars))
227 -> RnM (result, FreeVars)
228 -- This version (a) assumes that the binding vars are *not* already in scope
229 -- (b) removes the binders from the free vars of the thing inside
230 -- The parser doesn't produce ThenBinds
231 rnLocalBindsAndThen EmptyLocalBinds thing_inside
232 = thing_inside EmptyLocalBinds
234 rnLocalBindsAndThen (HsValBinds val_binds) thing_inside
235 = rnValBindsAndThen val_binds $ \ val_binds' ->
236 thing_inside (HsValBinds val_binds')
238 rnLocalBindsAndThen (HsIPBinds binds) thing_inside
239 = rnIPBinds binds `thenM` \ (binds',fv_binds) ->
240 thing_inside (HsIPBinds binds') `thenM` \ (thing, fvs_thing) ->
241 returnM (thing, fvs_thing `plusFV` fv_binds)
244 rnIPBinds (IPBinds ip_binds _no_dict_binds)
245 = do { (ip_binds', fvs_s) <- mapAndUnzipM (wrapLocFstM rnIPBind) ip_binds
246 ; return (IPBinds ip_binds' emptyLHsBinds, plusFVs fvs_s) }
248 rnIPBind (IPBind n expr)
249 = newIPNameRn n `thenM` \ name ->
250 rnLExpr expr `thenM` \ (expr',fvExpr) ->
251 return (IPBind name expr', fvExpr)
255 %************************************************************************
259 %************************************************************************
262 -- wrapper for local binds
263 -- creates the documentation info and calls the helper below
264 rnValBindsLHS :: UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
265 -- these fixities need to be brought into scope with the names
266 -> HsValBinds RdrName
267 -> RnM (HsValBindsLR Name RdrName)
268 rnValBindsLHS fix_env binds =
269 let (boundNames,doc) = bindersAndDoc binds
270 in rnValBindsLHSFromDoc_Local boundNames doc fix_env binds
272 -- a helper used for local binds that does the duplicates check,
273 -- just so we don't forget to do it somewhere
274 rnValBindsLHSFromDoc_Local :: [Located RdrName] -- RdrNames of the LHS (so we don't have to gather them twice)
275 -> SDoc -- doc string for dup names and shadowing
276 -> UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
277 -- these fixities need to be brought into scope with the names
278 -> HsValBinds RdrName
279 -> RnM (HsValBindsLR Name RdrName)
281 rnValBindsLHSFromDoc_Local boundNames doc fix_env binds = do
282 -- Do error checking: we need to check for dups here because we
283 -- don't don't bind all of the variables from the ValBinds at once
284 -- with bindLocatedLocals any more.
286 checkDupNames doc boundNames
287 -- Warn about shadowing, but only in source modules
288 ifOptM Opt_WarnNameShadowing (checkShadowing doc boundNames)
290 -- (Note that we don't want to do this at the top level, since
291 -- sorting out duplicates and shadowing there happens elsewhere.
292 -- The behavior is even different. For example,
295 -- should not produce a shadowing warning (but it will produce
296 -- an ambiguity warning if you use f), but
298 -- g = let f = ... in f
300 rnValBindsLHSFromDoc False boundNames doc fix_env binds
302 bindersAndDoc :: HsValBinds RdrName -> ([Located RdrName], SDoc)
303 bindersAndDoc binds =
305 -- the unrenamed bndrs for error checking and reporting
306 orig = collectHsValBinders binds
307 doc = text "In the binding group for:" <+> pprWithCommas ppr (map unLoc orig)
311 -- renames the left-hand sides
312 -- generic version used both at the top level and for local binds
313 -- does some error checking, but not what gets done elsewhere at the top level
314 rnValBindsLHSFromDoc :: Bool -- top or not
315 -> [Located RdrName] -- RdrNames of the LHS (so we don't have to gather them twice)
316 -> SDoc -- doc string for dup names and shadowing
317 -> UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
318 -- these fixities need to be brought into scope with the names
319 -> HsValBinds RdrName
320 -> RnM (HsValBindsLR Name RdrName)
321 rnValBindsLHSFromDoc topP original_bndrs doc fix_env binds@(ValBindsIn mbinds sigs)
324 mbinds' <- mapBagM (rnBindLHS topP doc fix_env) mbinds
325 return $ ValBindsIn mbinds' sigs
327 -- assumes the LHS vars are in scope
328 -- general version used both from the top-level and for local things
330 -- does not bind the local fixity declarations
331 rnValBindsRHSGen :: (FreeVars -> FreeVars) -- for trimming free var sets
332 -- The trimming function trims the free vars we attach to a
333 -- binding so that it stays reasonably small
334 -> [Name] -- names bound by the LHSes
335 -> HsValBindsLR Name RdrName
336 -> RnM (HsValBinds Name, DefUses)
338 rnValBindsRHSGen trim bound_names binds@(ValBindsIn mbinds sigs)
339 = do -- rename the sigs
340 sigs' <- rename_sigs sigs
342 binds_w_dus <- mapBagM (rnBind (mkSigTvFn sigs') trim) mbinds
343 let (anal_binds, anal_dus) = depAnalBinds binds_w_dus
344 (valbind', valbind'_dus) = (ValBindsOut anal_binds sigs',
345 usesOnly (hsSigsFVs sigs') `plusDU` anal_dus)
346 -- We do the check-sigs after renaming the bindings,
347 -- so that we have convenient access to the binders
348 check_sigs (okBindSig (duDefs anal_dus)) sigs'
349 returnM (valbind', valbind'_dus)
351 -- wrapper for local binds
353 -- the *client* of this function is responsible for checking for unused binders;
354 -- it doesn't (and can't: we don't have the thing inside the binds) happen here
356 -- the client is also responsible for bringing the fixities into scope
357 rnValBindsRHS :: [Name] -- names bound by the LHSes
358 -> HsValBindsLR Name RdrName
359 -> RnM (HsValBinds Name, DefUses)
360 rnValBindsRHS bound_names binds =
361 rnValBindsRHSGen (\ fvs -> -- only keep the names the names from this group
362 intersectNameSet (mkNameSet bound_names) fvs) bound_names binds
366 -- wrapper that does both the left- and right-hand sides
368 -- here there are no local fixity decls passed in;
369 -- the local fixity decls come from the ValBinds sigs
370 rnValBindsAndThen :: HsValBinds RdrName
371 -> (HsValBinds Name -> RnM (result, FreeVars))
372 -> RnM (result, FreeVars)
373 rnValBindsAndThen binds@(ValBindsIn _ sigs) thing_inside =
375 (original_bndrs, doc) = bindersAndDoc binds
378 -- (A) create the local fixity environment
379 new_fixities <- makeMiniFixityEnv [L loc sig | L loc (FixSig sig) <- sigs]
381 -- (B) rename the LHSes
382 new_lhs <- rnValBindsLHSFromDoc_Local original_bndrs doc new_fixities binds
383 let bound_names = map unLoc $ collectHsValBinders new_lhs
385 -- and bring them (and their fixities) into scope
386 bindLocalNamesFV_WithFixities bound_names new_fixities $ do
388 -- (C) do the RHS and thing inside
389 (binds', dus) <- rnValBindsRHS bound_names new_lhs
390 (result, result_fvs) <- thing_inside binds'
393 -- the variables used in the val binds are:
394 -- (1) the uses of the binds
395 -- (2) the FVs of the thing-inside
396 all_uses = (duUses dus) `plusFV` result_fvs
397 -- duUses: It's important to return all the uses. Otherwise consider:
399 -- y = let p = x in 'x' -- NB: p not used
400 -- If we don't "see" the dependency of 'y' on 'x', we may put the
401 -- bindings in the wrong order, and the type checker will complain
402 -- that x isn't in scope
404 -- check for unused binders. note that we only want to do
405 -- this for local ValBinds; it gets done elsewhere for
406 -- top-level binds (where the scoping is different)
407 unused_bndrs = [ b | b <- bound_names, not (b `elemNameSet` all_uses)]
409 warnUnusedLocalBinds unused_bndrs
412 -- the bound names are pruned out of all_uses
413 -- by the bindLocalNamesFV call above
417 -- Process the fixity declarations, making a FastString -> (Located Fixity) map
418 -- (We keep the location around for reporting duplicate fixity declarations.)
420 -- Checks for duplicates, but not that only locally defined things are fixed.
421 -- Note: for local fixity declarations, duplicates would also be checked in
422 -- check_sigs below. But we also use this function at the top level.
423 makeMiniFixityEnv :: [LFixitySig RdrName]
424 -> RnM (UniqFM (Located Fixity)) -- key is the FastString of the OccName
425 -- of the fixity declaration it came from
427 makeMiniFixityEnv decls = foldlM add_one emptyUFM decls
429 add_one env (L loc (FixitySig (L name_loc name) fixity)) = do
430 { -- this fixity decl is a duplicate iff
431 -- the ReaderName's OccName's FastString is already in the env
432 -- (we only need to check the local fix_env because
433 -- definitions of non-local will be caught elsewhere)
434 let {occ = rdrNameOcc name;
435 curKey = occNameFS occ;
436 fix_item = L loc fixity};
438 case lookupUFM env curKey of
439 Nothing -> return $ addToUFM env curKey fix_item
440 Just (L loc' _) -> do
442 addLocErr (L name_loc name) (dupFixityDecl loc')
446 pprFixEnv :: NameEnv FixItem -> SDoc
448 = pprWithCommas (\ (FixItem n f) -> ppr f <+> ppr n)
451 dupFixityDecl loc rdr_name
452 = vcat [ptext SLIT("Multiple fixity declarations for") <+> quotes (ppr rdr_name),
453 ptext SLIT("also at ") <+> ppr loc]
455 ---------------------
457 -- renaming a single bind
459 rnBindLHS :: Bool -- top if true; local if false
461 -> UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
462 -- these fixities need to be brought into scope with the names
464 -- returns the renamed left-hand side,
465 -- and the FreeVars *of the LHS*
466 -- (i.e., any free variables of the pattern)
467 -> RnM (LHsBindLR Name RdrName)
469 rnBindLHS topP doc fix_env (L loc (PatBind { pat_lhs = pat,
472 pat_rhs_ty=pat_rhs_ty
474 = setSrcSpan loc $ do
475 -- we don't actually use the FV processing of rnPatsAndThen here
476 (pat',pat'_fvs) <- (if topP then rnPat_TopRec else rnPat_LocalRec) fix_env pat
477 return (L loc (PatBind { pat_lhs = pat',
479 -- we temporarily store the pat's FVs here;
480 -- gets updated to the FVs of the whole bind
481 -- when doing the RHS below
483 -- these will get ignored in the next pass,
484 -- when we rename the RHS
485 pat_rhs_ty = pat_rhs_ty }))
487 rnBindLHS topP doc fix_env (L loc (FunBind { fun_id = name@(L nameLoc _),
489 fun_matches = matches,
490 fun_co_fn = fun_co_fn,
494 = setSrcSpan loc $ do
495 newname <- applyNameMaker (if topP then topNameMaker else localNameMaker) name
496 return (L loc (FunBind { fun_id = L nameLoc newname,
498 fun_matches = matches,
499 -- we temporatily store the LHS's FVs (empty in this case) here
500 -- gets updated when doing the RHS below
502 -- everything else will get ignored in the next pass
503 fun_co_fn = fun_co_fn,
507 -- assumes the left-hands-side vars are in scope
508 rnBind :: (Name -> [Name]) -- Signature tyvar function
509 -> (FreeVars -> FreeVars) -- Trimming function for rhs free vars
510 -> LHsBindLR Name RdrName
511 -> RnM (LHsBind Name, [Name], Uses)
512 rnBind sig_fn trim (L loc (PatBind { pat_lhs = pat,
514 -- pat fvs were stored here while processing the LHS
517 do {let bndrs = collectPatBinders pat
519 ; (grhss', fvs) <- rnGRHSs PatBindRhs grhss
520 -- No scoped type variables for pattern bindings
522 ; return (L loc (PatBind { pat_lhs = pat,
524 pat_rhs_ty = placeHolderType,
525 bind_fvs = trim fvs }),
526 bndrs, pat_fvs `plusFV` fvs) }
530 (L loc (FunBind { fun_id = name,
532 fun_matches = matches,
536 -- invariant: no free vars here when it's a FunBind
538 do { let plain_name = unLoc name
540 ; (matches', fvs) <- bindSigTyVarsFV (sig_fn plain_name) $
541 -- bindSigTyVars tests for Opt_ScopedTyVars
542 rnMatchGroup (FunRhs plain_name inf) matches
544 ; checkPrecMatch inf plain_name matches'
546 ; return (L loc (FunBind { fun_id = name,
548 fun_matches = matches',
550 fun_co_fn = idHsWrapper,
551 fun_tick = Nothing }),
555 ---------------------
556 depAnalBinds :: Bag (LHsBind Name, [Name], Uses)
557 -> ([(RecFlag, LHsBinds Name)], DefUses)
558 -- Dependency analysis; this is important so that
559 -- unused-binding reporting is accurate
560 depAnalBinds binds_w_dus
561 = (map get_binds sccs, map get_du sccs)
563 sccs = stronglyConnComp edges
565 keyd_nodes = bagToList binds_w_dus `zip` [0::Int ..]
567 edges = [ (node, key, [key | n <- nameSetToList uses,
568 Just key <- [lookupNameEnv key_map n] ])
569 | (node@(_,_,uses), key) <- keyd_nodes ]
571 key_map :: NameEnv Int -- Which binding it comes from
572 key_map = mkNameEnv [(bndr, key) | ((_, bndrs, _), key) <- keyd_nodes
575 get_binds (AcyclicSCC (bind, _, _)) = (NonRecursive, unitBag bind)
576 get_binds (CyclicSCC binds_w_dus) = (Recursive, listToBag [b | (b,d,u) <- binds_w_dus])
578 get_du (AcyclicSCC (_, bndrs, uses)) = (Just (mkNameSet bndrs), uses)
579 get_du (CyclicSCC binds_w_dus) = (Just defs, uses)
581 defs = mkNameSet [b | (_,bs,_) <- binds_w_dus, b <- bs]
582 uses = unionManyNameSets [u | (_,_,u) <- binds_w_dus]
585 ---------------------
586 -- Bind the top-level forall'd type variables in the sigs.
589 -- The 'a' scopes over the rhs
591 -- NB: there'll usually be just one (for a function binding)
592 -- but if there are many, one may shadow the rest; too bad!
593 -- e.g x :: [a] -> [a]
596 -- In e, 'a' will be in scope, and it'll be the one from 'y'!
598 mkSigTvFn :: [LSig Name] -> (Name -> [Name])
599 -- Return a lookup function that maps an Id Name to the names
600 -- of the type variables that should scope over its body..
602 = \n -> lookupNameEnv env n `orElse` []
604 env :: NameEnv [Name]
605 env = mkNameEnv [ (name, map hsLTyVarName ltvs)
606 | L _ (TypeSig (L _ name)
607 (L _ (HsForAllTy Explicit ltvs _ _))) <- sigs]
608 -- Note the pattern-match on "Explicit"; we only bind
609 -- type variables from signatures with an explicit top-level for-all
613 @rnMethodBinds@ is used for the method bindings of a class and an instance
614 declaration. Like @rnBinds@ but without dependency analysis.
616 NOTA BENE: we record each {\em binder} of a method-bind group as a free variable.
617 That's crucial when dealing with an instance decl:
619 instance Foo (T a) where
622 This might be the {\em sole} occurrence of @op@ for an imported class @Foo@,
623 and unless @op@ occurs we won't treat the type signature of @op@ in the class
624 decl for @Foo@ as a source of instance-decl gates. But we should! Indeed,
625 in many ways the @op@ in an instance decl is just like an occurrence, not
629 rnMethodBinds :: Name -- Class name
630 -> (Name -> [Name]) -- Signature tyvar function
631 -> [Name] -- Names for generic type variables
633 -> RnM (LHsBinds Name, FreeVars)
635 rnMethodBinds cls sig_fn gen_tyvars binds
636 = foldM do_one (emptyBag,emptyFVs) (bagToList binds)
637 where do_one (binds,fvs) bind = do
638 (bind', fvs_bind) <- rnMethodBind cls sig_fn gen_tyvars bind
639 return (bind' `unionBags` binds, fvs_bind `plusFV` fvs)
641 rnMethodBind cls sig_fn gen_tyvars (L loc (FunBind { fun_id = name, fun_infix = inf,
642 fun_matches = MatchGroup matches _ }))
644 lookupInstDeclBndr cls name `thenM` \ sel_name ->
645 let plain_name = unLoc sel_name in
646 -- We use the selector name as the binder
648 bindSigTyVarsFV (sig_fn plain_name) $
649 mapFvRn (rn_match plain_name) matches `thenM` \ (new_matches, fvs) ->
651 new_group = MatchGroup new_matches placeHolderType
653 checkPrecMatch inf plain_name new_group `thenM_`
654 returnM (unitBag (L loc (FunBind {
655 fun_id = sel_name, fun_infix = inf,
656 fun_matches = new_group,
657 bind_fvs = fvs, fun_co_fn = idHsWrapper,
658 fun_tick = Nothing })),
659 fvs `addOneFV` plain_name)
660 -- The 'fvs' field isn't used for method binds
662 -- Truly gruesome; bring into scope the correct members of the generic
663 -- type variables. See comments in RnSource.rnSourceDecl(ClassDecl)
664 rn_match sel_name match@(L _ (Match (L _ (TypePat ty) : _) _ _))
665 = extendTyVarEnvFVRn gen_tvs $
666 rnMatch (FunRhs sel_name inf) match
668 tvs = map (rdrNameOcc.unLoc) (extractHsTyRdrTyVars ty)
669 gen_tvs = [tv | tv <- gen_tyvars, nameOccName tv `elem` tvs]
671 rn_match sel_name match = rnMatch (FunRhs sel_name inf) match
674 -- Can't handle method pattern-bindings which bind multiple methods.
675 rnMethodBind cls sig_fn gen_tyvars mbind@(L loc (PatBind other_pat _ _ _))
676 = addLocErr mbind methodBindErr `thenM_`
677 returnM (emptyBag, emptyFVs)
682 %************************************************************************
684 \subsubsection[dep-Sigs]{Signatures (and user-pragmas for values)}
686 %************************************************************************
688 @renameSigs@ checks for:
690 \item more than one sig for one thing;
691 \item signatures given for things not bound here;
692 \item with suitably flaggery, that all top-level things have type signatures.
695 At the moment we don't gather free-var info from the types in
696 signatures. We'd only need this if we wanted to report unused tyvars.
699 renameSigs :: (LSig Name -> Bool) -> [LSig RdrName] -> RnM [LSig Name]
700 -- Renames the signatures and performs error checks
701 renameSigs ok_sig sigs
702 = do { sigs' <- rename_sigs sigs
703 ; check_sigs ok_sig sigs'
706 ----------------------
707 rename_sigs :: [LSig RdrName] -> RnM [LSig Name]
708 rename_sigs sigs = mappM (wrapLocM renameSig) sigs
710 ----------------------
711 check_sigs :: (LSig Name -> Bool) -> [LSig Name] -> RnM ()
712 -- Used for class and instance decls, as well as regular bindings
713 check_sigs ok_sig sigs
714 -- Check for (a) duplicate signatures
715 -- (b) signatures for things not in this group
717 traceRn (text "SIGS" <+> ppr sigs)
718 ; mappM_ unknownSigErr (filter (not . ok_sig) sigs')
719 ; mappM_ dupSigDeclErr (findDupsEq eqHsSig sigs') }
721 -- Don't complain about an unbound name again
722 sigs' = filterOut bad_name sigs
723 bad_name sig = case sigName sig of
724 Just n -> isUnboundName n
727 -- We use lookupLocatedSigOccRn in the signatures, which is a little bit unsatisfactory
728 -- because this won't work for:
729 -- instance Foo T where
732 -- We'll just rename the INLINE prag to refer to whatever other 'op'
733 -- is in scope. (I'm assuming that Baz.op isn't in scope unqualified.)
734 -- Doesn't seem worth much trouble to sort this.
736 renameSig :: Sig RdrName -> RnM (Sig Name)
737 -- FixitSig is renamed elsewhere.
738 renameSig (TypeSig v ty)
739 = lookupLocatedSigOccRn v `thenM` \ new_v ->
740 rnHsSigType (quotes (ppr v)) ty `thenM` \ new_ty ->
741 returnM (TypeSig new_v new_ty)
743 renameSig (SpecInstSig ty)
744 = rnLHsType (text "A SPECIALISE instance pragma") ty `thenM` \ new_ty ->
745 returnM (SpecInstSig new_ty)
747 renameSig (SpecSig v ty inl)
748 = lookupLocatedSigOccRn v `thenM` \ new_v ->
749 rnHsSigType (quotes (ppr v)) ty `thenM` \ new_ty ->
750 returnM (SpecSig new_v new_ty inl)
752 renameSig (InlineSig v s)
753 = lookupLocatedSigOccRn v `thenM` \ new_v ->
754 returnM (InlineSig new_v s)
756 renameSig (FixSig (FixitySig v f))
757 = lookupLocatedSigOccRn v `thenM` \ new_v ->
758 returnM (FixSig (FixitySig new_v f))
762 ************************************************************************
766 ************************************************************************
769 rnMatchGroup :: HsMatchContext Name -> MatchGroup RdrName -> RnM (MatchGroup Name, FreeVars)
770 rnMatchGroup ctxt (MatchGroup ms _)
771 = mapFvRn (rnMatch ctxt) ms `thenM` \ (new_ms, ms_fvs) ->
772 returnM (MatchGroup new_ms placeHolderType, ms_fvs)
774 rnMatch :: HsMatchContext Name -> LMatch RdrName -> RnM (LMatch Name, FreeVars)
775 rnMatch ctxt = wrapLocFstM (rnMatch' ctxt)
777 rnMatch' ctxt match@(Match pats maybe_rhs_sig grhss)
779 -- Deal with the rhs type signature
780 bindPatSigTyVarsFV rhs_sig_tys $
781 doptM Opt_PatternSignatures `thenM` \ opt_PatternSignatures ->
782 (case maybe_rhs_sig of
783 Nothing -> returnM (Nothing, emptyFVs)
784 Just ty | opt_PatternSignatures -> rnHsTypeFVs doc_sig ty `thenM` \ (ty', ty_fvs) ->
785 returnM (Just ty', ty_fvs)
786 | otherwise -> addLocErr ty patSigErr `thenM_`
787 returnM (Nothing, emptyFVs)
788 ) `thenM` \ (maybe_rhs_sig', ty_fvs) ->
790 -- Now the main event
791 -- note that there are no local ficity decls for matches
792 rnPatsAndThen_LocalRightwards ctxt pats $ \ (pats',_) ->
793 rnGRHSs ctxt grhss `thenM` \ (grhss', grhss_fvs) ->
795 returnM (Match pats' maybe_rhs_sig' grhss', grhss_fvs `plusFV` ty_fvs)
796 -- The bindPatSigTyVarsFV and rnPatsAndThen will remove the bound FVs
798 rhs_sig_tys = case maybe_rhs_sig of
801 doc_sig = text "In a result type-signature"
805 %************************************************************************
807 \subsubsection{Guarded right-hand sides (GRHSs)}
809 %************************************************************************
812 rnGRHSs :: HsMatchContext Name -> GRHSs RdrName -> RnM (GRHSs Name, FreeVars)
814 rnGRHSs ctxt (GRHSs grhss binds)
815 = rnLocalBindsAndThen binds $ \ binds' ->
816 mapFvRn (rnGRHS ctxt) grhss `thenM` \ (grhss', fvGRHSs) ->
817 returnM (GRHSs grhss' binds', fvGRHSs)
819 rnGRHS :: HsMatchContext Name -> LGRHS RdrName -> RnM (LGRHS Name, FreeVars)
820 rnGRHS ctxt = wrapLocFstM (rnGRHS' ctxt)
822 rnGRHS' ctxt (GRHS guards rhs)
823 = do { pattern_guards_allowed <- doptM Opt_PatternGuards
824 ; ((guards', rhs'), fvs) <- rnStmts (PatGuard ctxt) guards $
827 ; checkM (pattern_guards_allowed || is_standard_guard guards')
828 (addWarn (nonStdGuardErr guards'))
830 ; return (GRHS guards' rhs', fvs) }
832 -- Standard Haskell 1.4 guards are just a single boolean
833 -- expression, rather than a list of qualifiers as in the
835 is_standard_guard [] = True
836 is_standard_guard [L _ (ExprStmt _ _ _)] = True
837 is_standard_guard other = False
840 %************************************************************************
842 \subsection{Error messages}
844 %************************************************************************
847 dupSigDeclErr sigs@(L loc sig : _)
849 vcat [ptext SLIT("Duplicate") <+> what_it_is <> colon,
850 nest 2 (vcat (map ppr_sig sigs))]
852 what_it_is = hsSigDoc sig
853 ppr_sig (L loc sig) = ppr loc <> colon <+> ppr sig
855 unknownSigErr (L loc sig)
856 = do { mod <- getModule
858 vcat [sep [ptext SLIT("Misplaced") <+> what_it_is <> colon, ppr sig],
859 extra_stuff mod sig] }
861 what_it_is = hsSigDoc sig
862 extra_stuff mod (TypeSig (L _ n) _)
863 | nameIsLocalOrFrom mod n
864 = ptext SLIT("The type signature must be given where")
865 <+> quotes (ppr n) <+> ptext SLIT("is declared")
867 = ptext SLIT("You cannot give a type signature for an imported value")
869 extra_stuff mod other = empty
872 = hang (ptext SLIT("Pattern bindings (except simple variables) not allowed in instance declarations"))
875 bindsInHsBootFile mbinds
876 = hang (ptext SLIT("Bindings in hs-boot files are not allowed"))
879 nonStdGuardErr guards
880 = hang (ptext SLIT("accepting non-standard pattern guards (use -XPatternGuards to suppress this message)"))
881 4 (interpp'SP guards)