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, rnBindPat,
36 NameMaker, localRecNameMaker, topRecNameMaker, 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 checkDupAndShadowedRdrNames
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 )
64 import Maybes ( orElse )
65 import Util ( filterOut )
66 import Monad ( foldM, unless )
69 -- ToDo: Put the annotations into the monad, so that they arrive in the proper
70 -- place and can be used when complaining.
72 The code tree received by the function @rnBinds@ contains definitions
73 in where-clauses which are all apparently mutually recursive, but which may
74 not really depend upon each other. For example, in the top level program
79 the definitions of @a@ and @y@ do not depend on each other at all.
80 Unfortunately, the typechecker cannot always check such definitions.
81 \footnote{Mycroft, A. 1984. Polymorphic type schemes and recursive
82 definitions. In Proceedings of the International Symposium on Programming,
83 Toulouse, pp. 217-39. LNCS 167. Springer Verlag.}
84 However, the typechecker usually can check definitions in which only the
85 strongly connected components have been collected into recursive bindings.
86 This is precisely what the function @rnBinds@ does.
88 ToDo: deal with case where a single monobinds binds the same variable
91 The vertag tag is a unique @Int@; the tags only need to be unique
92 within one @MonoBinds@, so that unique-Int plumbing is done explicitly
93 (heavy monad machinery not needed).
96 %************************************************************************
98 %* naming conventions *
100 %************************************************************************
102 \subsection[name-conventions]{Name conventions}
104 The basic algorithm involves walking over the tree and returning a tuple
105 containing the new tree plus its free variables. Some functions, such
106 as those walking polymorphic bindings (HsBinds) and qualifier lists in
107 list comprehensions (@Quals@), return the variables bound in local
108 environments. These are then used to calculate the free variables of the
109 expression evaluated in these environments.
111 Conventions for variable names are as follows:
114 new code is given a prime to distinguish it from the old.
117 a set of variables defined in @Exp@ is written @dvExp@
120 a set of variables free in @Exp@ is written @fvExp@
123 %************************************************************************
125 %* analysing polymorphic bindings (HsBindGroup, HsBind)
127 %************************************************************************
129 \subsubsection[dep-HsBinds]{Polymorphic bindings}
131 Non-recursive expressions are reconstructed without any changes at top
132 level, although their component expressions may have to be altered.
133 However, non-recursive expressions are currently not expected as
134 \Haskell{} programs, and this code should not be executed.
136 Monomorphic bindings contain information that is returned in a tuple
137 (a @FlatMonoBinds@) containing:
141 a unique @Int@ that serves as the ``vertex tag'' for this binding.
144 the name of a function or the names in a pattern. These are a set
145 referred to as @dvLhs@, the defined variables of the left hand side.
148 the free variables of the body. These are referred to as @fvBody@.
151 the definition's actual code. This is referred to as just @code@.
154 The function @nonRecDvFv@ returns two sets of variables. The first is
155 the set of variables defined in the set of monomorphic bindings, while the
156 second is the set of free variables in those bindings.
158 The set of variables defined in a non-recursive binding is just the
159 union of all of them, as @union@ removes duplicates. However, the
160 free variables in each successive set of cumulative bindings is the
161 union of those in the previous set plus those of the newest binding after
162 the defined variables of the previous set have been removed.
164 @rnMethodBinds@ deals only with the declarations in class and
165 instance declarations. It expects only to see @FunMonoBind@s, and
166 it expects the global environment to contain bindings for the binders
167 (which are all class operations).
169 %************************************************************************
171 \subsubsection{ Top-level bindings}
173 %************************************************************************
176 -- for top-level bindings, we need to make top-level names,
177 -- so we have a different entry point than for local bindings
178 rnTopBindsLHS :: UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
179 -- these fixities need to be brought into scope with the names
180 -> HsValBinds RdrName
181 -> RnM (HsValBindsLR Name RdrName)
182 rnTopBindsLHS fix_env binds =
183 (uncurry $ rnValBindsLHSFromDoc (topRecNameMaker fix_env)) (bindersAndDoc binds) binds
185 rnTopBindsRHS :: [Name] -- the names bound by these binds
186 -> HsValBindsLR Name RdrName
187 -> RnM (HsValBinds Name, DefUses)
188 rnTopBindsRHS bound_names binds =
189 do { is_boot <- tcIsHsBoot
191 then rnTopBindsBoot binds
192 else rnValBindsRHSGen (\x -> x) -- don't trim free vars
196 -- wrapper if we don't need to do anything in between the left and right,
197 -- or anything else in the scope of the left
199 -- never used when there are fixity declarations
200 rnTopBinds :: HsValBinds RdrName
201 -> RnM (HsValBinds Name, DefUses)
203 do nl <- rnTopBindsLHS emptyUFM b
204 let bound_names = map unLoc (collectHsValBinders nl)
205 bindLocalNames bound_names $ rnTopBindsRHS bound_names nl
208 rnTopBindsBoot :: HsValBindsLR Name RdrName -> RnM (HsValBinds Name, DefUses)
209 -- A hs-boot file has no bindings.
210 -- Return a single HsBindGroup with empty binds and renamed signatures
211 rnTopBindsBoot (ValBindsIn mbinds sigs)
212 = do { checkErr (isEmptyLHsBinds mbinds) (bindsInHsBootFile mbinds)
213 ; sigs' <- renameSigs okHsBootSig sigs
214 ; return (ValBindsOut [] sigs', usesOnly (hsSigsFVs sigs')) }
219 %*********************************************************
223 %*********************************************************
226 rnLocalBindsAndThen :: HsLocalBinds RdrName
227 -> (HsLocalBinds Name -> RnM (result, FreeVars))
228 -> RnM (result, FreeVars)
229 -- This version (a) assumes that the binding vars are *not* already in scope
230 -- (b) removes the binders from the free vars of the thing inside
231 -- The parser doesn't produce ThenBinds
232 rnLocalBindsAndThen EmptyLocalBinds thing_inside
233 = thing_inside EmptyLocalBinds
235 rnLocalBindsAndThen (HsValBinds val_binds) thing_inside
236 = rnValBindsAndThen val_binds $ \ val_binds' ->
237 thing_inside (HsValBinds val_binds')
239 rnLocalBindsAndThen (HsIPBinds binds) thing_inside = do
240 (binds',fv_binds) <- rnIPBinds binds
241 (thing, fvs_thing) <- thing_inside (HsIPBinds binds')
242 return (thing, fvs_thing `plusFV` fv_binds)
245 rnIPBinds (IPBinds ip_binds _no_dict_binds) = do
246 (ip_binds', fvs_s) <- mapAndUnzipM (wrapLocFstM rnIPBind) ip_binds
247 return (IPBinds ip_binds' emptyLHsBinds, plusFVs fvs_s)
249 rnIPBind (IPBind n expr) = do
250 name <- newIPNameRn n
251 (expr',fvExpr) <- rnLExpr expr
252 return (IPBind name expr', fvExpr)
256 %************************************************************************
260 %************************************************************************
263 -- wrapper for local binds
264 -- creates the documentation info and calls the helper below
265 rnValBindsLHS :: UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
266 -- these fixities need to be brought into scope with the names
267 -> HsValBinds RdrName
268 -> RnM (HsValBindsLR Name RdrName)
269 rnValBindsLHS fix_env binds =
270 let (boundNames,doc) = bindersAndDoc binds
271 in rnValBindsLHSFromDoc_Local boundNames doc fix_env binds
273 -- a helper used for local binds that does the duplicates check,
274 -- just so we don't forget to do it somewhere
275 rnValBindsLHSFromDoc_Local :: [Located RdrName] -- RdrNames of the LHS (so we don't have to gather them twice)
276 -> SDoc -- doc string for dup names and shadowing
277 -> UniqFM (Located Fixity) -- mini fixity env for the names we're about to bind
278 -- these fixities need to be brought into scope with the names
279 -> HsValBinds RdrName
280 -> RnM (HsValBindsLR Name RdrName)
282 rnValBindsLHSFromDoc_Local boundNames doc fix_env binds = do
283 -- Do error checking: we need to check for dups here because we
284 -- don't don't bind all of the variables from the ValBinds at once
285 -- with bindLocatedLocals any more.
286 checkDupAndShadowedRdrNames doc boundNames
288 -- (Note that we don't want to do this at the top level, since
289 -- sorting out duplicates and shadowing there happens elsewhere.
290 -- The behavior is even different. For example,
293 -- should not produce a shadowing warning (but it will produce
294 -- an ambiguity warning if you use f), but
296 -- g = let f = ... in f
298 rnValBindsLHSFromDoc (localRecNameMaker fix_env) boundNames doc binds
300 bindersAndDoc :: HsValBinds RdrName -> ([Located RdrName], SDoc)
301 bindersAndDoc binds =
303 -- the unrenamed bndrs for error checking and reporting
304 orig = collectHsValBinders binds
305 doc = text "In the binding group for:" <+> pprWithCommas ppr (map unLoc orig)
309 -- renames the left-hand sides
310 -- generic version used both at the top level and for local binds
311 -- does some error checking, but not what gets done elsewhere at the top level
312 rnValBindsLHSFromDoc :: NameMaker
313 -> [Located RdrName] -- RdrNames of the LHS (so we don't have to gather them twice)
314 -> SDoc -- doc string for dup names and shadowing
315 -> HsValBinds RdrName
316 -> RnM (HsValBindsLR Name RdrName)
317 rnValBindsLHSFromDoc topP original_bndrs doc binds@(ValBindsIn mbinds sigs) = do
319 mbinds' <- mapBagM (rnBindLHS topP doc) mbinds
320 return $ ValBindsIn mbinds' sigs
322 -- assumes the LHS vars are in scope
323 -- general version used both from the top-level and for local things
325 -- does not bind the local fixity declarations
326 rnValBindsRHSGen :: (FreeVars -> FreeVars) -- for trimming free var sets
327 -- The trimming function trims the free vars we attach to a
328 -- binding so that it stays reasonably small
329 -> [Name] -- names bound by the LHSes
330 -> HsValBindsLR Name RdrName
331 -> RnM (HsValBinds Name, DefUses)
333 rnValBindsRHSGen trim bound_names binds@(ValBindsIn mbinds sigs) = do
335 sigs' <- rename_sigs sigs
337 binds_w_dus <- mapBagM (rnBind (mkSigTvFn sigs') trim) mbinds
338 let (anal_binds, anal_dus) = depAnalBinds binds_w_dus
339 (valbind', valbind'_dus) = (ValBindsOut anal_binds sigs',
340 usesOnly (hsSigsFVs sigs') `plusDU` anal_dus)
341 -- We do the check-sigs after renaming the bindings,
342 -- so that we have convenient access to the binders
343 check_sigs (okBindSig (duDefs anal_dus)) sigs'
344 return (valbind', valbind'_dus)
346 -- Wrapper for local binds
348 -- The *client* of this function is responsible for checking for unused binders;
349 -- it doesn't (and can't: we don't have the thing inside the binds) happen here
351 -- The client is also responsible for bringing the fixities into scope
352 rnValBindsRHS :: [Name] -- names bound by the LHSes
353 -> HsValBindsLR Name RdrName
354 -> RnM (HsValBinds Name, DefUses)
355 rnValBindsRHS bound_names binds =
356 rnValBindsRHSGen (\ fvs -> -- only keep the names the names from this group
357 intersectNameSet (mkNameSet bound_names) fvs) bound_names binds
361 -- wrapper that does both the left- and right-hand sides
363 -- here there are no local fixity decls passed in;
364 -- the local fixity decls come from the ValBinds sigs
365 rnValBindsAndThen :: HsValBinds RdrName
366 -> (HsValBinds Name -> RnM (result, FreeVars))
367 -> RnM (result, FreeVars)
368 rnValBindsAndThen binds@(ValBindsIn _ sigs) thing_inside
369 = do { let (original_bndrs, doc) = bindersAndDoc binds
371 -- (A) Create the local fixity environment
372 ; new_fixities <- makeMiniFixityEnv [L loc sig | L loc (FixSig sig) <- sigs]
374 -- (B) Rename the LHSes
375 ; new_lhs <- rnValBindsLHSFromDoc_Local original_bndrs doc new_fixities binds
376 ; let bound_names = map unLoc $ collectHsValBinders new_lhs
378 -- ...and bring them (and their fixities) into scope
379 ; bindLocalNamesFV_WithFixities bound_names new_fixities $ do
381 { -- (C) Do the RHS and thing inside
382 (binds', dus) <- rnValBindsRHS bound_names new_lhs
383 ; (result, result_fvs) <- thing_inside binds'
385 -- Report unused bindings based on the (accurate)
388 -- should report 'x' unused
389 ; let real_uses = findUses dus result_fvs
390 ; warnUnusedLocalBinds bound_names real_uses
393 -- The variables "used" in the val binds are:
394 -- (1) the uses of the binds (duUses)
395 -- (2) the FVs of the thing-inside
396 all_uses = duUses dus `plusFV` result_fvs
397 -- Note [Unused binding hack]
398 -- ~~~~~~~~~~~~~~~~~~~~~~~~~~
399 -- Note that *in contrast* to the above reporting of
400 -- unused bindings, (1) above uses duUses to return *all*
401 -- the uses, even if the binding is unused. Otherwise consider:
403 -- y = let p = x in 'x' -- NB: p not used
404 -- If we don't "see" the dependency of 'y' on 'x', we may put the
405 -- bindings in the wrong order, and the type checker will complain
406 -- that x isn't in scope
408 -- But note that this means we won't report 'x' as unused,
409 -- whereas we would if we had { x = 3; p = x; y = 'x' }
411 ; return (result, all_uses) }}
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 :: NameMaker
462 -- returns the renamed left-hand side,
463 -- and the FreeVars *of the LHS*
464 -- (i.e., any free variables of the pattern)
465 -> RnM (LHsBindLR Name RdrName)
467 rnBindLHS name_maker doc (L loc (PatBind { pat_lhs = pat,
470 pat_rhs_ty=pat_rhs_ty
472 = setSrcSpan loc $ do
473 -- we don't actually use the FV processing of rnPatsAndThen here
474 (pat',pat'_fvs) <- rnBindPat name_maker pat
475 return (L loc (PatBind { pat_lhs = pat',
477 -- we temporarily store the pat's FVs here;
478 -- gets updated to the FVs of the whole bind
479 -- when doing the RHS below
481 -- these will get ignored in the next pass,
482 -- when we rename the RHS
483 pat_rhs_ty = pat_rhs_ty }))
485 rnBindLHS name_maker doc (L loc (FunBind { fun_id = name@(L nameLoc _),
487 fun_matches = matches,
488 fun_co_fn = fun_co_fn,
493 do { (newname, _fvs) <- applyNameMaker name_maker name $ \ newname ->
494 return (newname, emptyFVs)
495 ; return (L loc (FunBind { fun_id = L nameLoc newname,
497 fun_matches = matches,
498 -- we temporatily store the LHS's FVs (empty in this case) here
499 -- gets updated when doing the RHS below
501 -- everything else will get ignored in the next pass
502 fun_co_fn = fun_co_fn,
506 -- assumes the left-hands-side vars are in scope
507 rnBind :: (Name -> [Name]) -- Signature tyvar function
508 -> (FreeVars -> FreeVars) -- Trimming function for rhs free vars
509 -> LHsBindLR Name RdrName
510 -> RnM (LHsBind Name, [Name], Uses)
511 rnBind sig_fn trim (L loc (PatBind { pat_lhs = pat,
513 -- pat fvs were stored here while processing the LHS
516 do {let bndrs = collectPatBinders pat
518 ; (grhss', fvs) <- rnGRHSs PatBindRhs grhss
519 -- No scoped type variables for pattern bindings
521 ; return (L loc (PatBind { pat_lhs = pat,
523 pat_rhs_ty = placeHolderType,
524 bind_fvs = trim fvs }),
525 bndrs, pat_fvs `plusFV` fvs) }
529 (L loc (FunBind { fun_id = name,
531 fun_matches = matches,
535 -- invariant: no free vars here when it's a FunBind
537 do { let plain_name = unLoc name
539 ; (matches', fvs) <- bindSigTyVarsFV (sig_fn plain_name) $
540 -- bindSigTyVars tests for Opt_ScopedTyVars
541 rnMatchGroup (FunRhs plain_name inf) matches
543 ; checkPrecMatch inf plain_name matches'
545 ; return (L loc (FunBind { fun_id = name,
547 fun_matches = matches',
549 fun_co_fn = idHsWrapper,
550 fun_tick = Nothing }),
554 ---------------------
555 depAnalBinds :: Bag (LHsBind Name, [Name], Uses)
556 -> ([(RecFlag, LHsBinds Name)], DefUses)
557 -- Dependency analysis; this is important so that
558 -- unused-binding reporting is accurate
559 depAnalBinds binds_w_dus
560 = (map get_binds sccs, map get_du sccs)
562 sccs = stronglyConnComp edges
564 keyd_nodes = bagToList binds_w_dus `zip` [0::Int ..]
566 edges = [ (node, key, [key | n <- nameSetToList uses,
567 Just key <- [lookupNameEnv key_map n] ])
568 | (node@(_,_,uses), key) <- keyd_nodes ]
570 key_map :: NameEnv Int -- Which binding it comes from
571 key_map = mkNameEnv [(bndr, key) | ((_, bndrs, _), key) <- keyd_nodes
574 get_binds (AcyclicSCC (bind, _, _)) = (NonRecursive, unitBag bind)
575 get_binds (CyclicSCC binds_w_dus) = (Recursive, listToBag [b | (b,d,u) <- binds_w_dus])
577 get_du (AcyclicSCC (_, bndrs, uses)) = (Just (mkNameSet bndrs), uses)
578 get_du (CyclicSCC binds_w_dus) = (Just defs, uses)
580 defs = mkNameSet [b | (_,bs,_) <- binds_w_dus, b <- bs]
581 uses = unionManyNameSets [u | (_,_,u) <- binds_w_dus]
584 ---------------------
585 -- Bind the top-level forall'd type variables in the sigs.
588 -- The 'a' scopes over the rhs
590 -- NB: there'll usually be just one (for a function binding)
591 -- but if there are many, one may shadow the rest; too bad!
592 -- e.g x :: [a] -> [a]
595 -- In e, 'a' will be in scope, and it'll be the one from 'y'!
597 mkSigTvFn :: [LSig Name] -> (Name -> [Name])
598 -- Return a lookup function that maps an Id Name to the names
599 -- of the type variables that should scope over its body..
601 = \n -> lookupNameEnv env n `orElse` []
603 env :: NameEnv [Name]
604 env = mkNameEnv [ (name, map hsLTyVarName ltvs)
605 | L _ (TypeSig (L _ name)
606 (L _ (HsForAllTy Explicit ltvs _ _))) <- sigs]
607 -- Note the pattern-match on "Explicit"; we only bind
608 -- type variables from signatures with an explicit top-level for-all
612 @rnMethodBinds@ is used for the method bindings of a class and an instance
613 declaration. Like @rnBinds@ but without dependency analysis.
615 NOTA BENE: we record each {\em binder} of a method-bind group as a free variable.
616 That's crucial when dealing with an instance decl:
618 instance Foo (T a) where
621 This might be the {\em sole} occurrence of @op@ for an imported class @Foo@,
622 and unless @op@ occurs we won't treat the type signature of @op@ in the class
623 decl for @Foo@ as a source of instance-decl gates. But we should! Indeed,
624 in many ways the @op@ in an instance decl is just like an occurrence, not
628 rnMethodBinds :: Name -- Class name
629 -> (Name -> [Name]) -- Signature tyvar function
630 -> [Name] -- Names for generic type variables
632 -> RnM (LHsBinds Name, FreeVars)
634 rnMethodBinds cls sig_fn gen_tyvars binds
635 = foldM do_one (emptyBag,emptyFVs) (bagToList binds)
636 where do_one (binds,fvs) bind = do
637 (bind', fvs_bind) <- rnMethodBind cls sig_fn gen_tyvars bind
638 return (bind' `unionBags` binds, fvs_bind `plusFV` fvs)
640 rnMethodBind cls sig_fn gen_tyvars (L loc (FunBind { fun_id = name, fun_infix = inf,
641 fun_matches = MatchGroup matches _ }))
642 = setSrcSpan loc $ do
643 sel_name <- lookupInstDeclBndr cls name
644 let plain_name = unLoc sel_name
645 -- We use the selector name as the binder
647 bindSigTyVarsFV (sig_fn plain_name) $ do
648 (new_matches, fvs) <- mapFvRn (rn_match plain_name) matches
650 new_group = MatchGroup new_matches placeHolderType
652 checkPrecMatch inf plain_name new_group
653 return (unitBag (L loc (FunBind {
654 fun_id = sel_name, fun_infix = inf,
655 fun_matches = new_group,
656 bind_fvs = fvs, fun_co_fn = idHsWrapper,
657 fun_tick = Nothing })),
658 fvs `addOneFV` plain_name)
659 -- The 'fvs' field isn't used for method binds
661 -- Truly gruesome; bring into scope the correct members of the generic
662 -- type variables. See comments in RnSource.rnSourceDecl(ClassDecl)
663 rn_match sel_name match@(L _ (Match (L _ (TypePat ty) : _) _ _))
664 = extendTyVarEnvFVRn gen_tvs $
665 rnMatch (FunRhs sel_name inf) match
667 tvs = map (rdrNameOcc.unLoc) (extractHsTyRdrTyVars ty)
668 gen_tvs = [tv | tv <- gen_tyvars, nameOccName tv `elem` tvs]
670 rn_match sel_name match = rnMatch (FunRhs sel_name inf) match
673 -- Can't handle method pattern-bindings which bind multiple methods.
674 rnMethodBind cls sig_fn gen_tyvars mbind@(L loc (PatBind other_pat _ _ _)) = do
675 addLocErr mbind methodBindErr
676 return (emptyBag, emptyFVs)
681 %************************************************************************
683 \subsubsection[dep-Sigs]{Signatures (and user-pragmas for values)}
685 %************************************************************************
687 @renameSigs@ checks for:
689 \item more than one sig for one thing;
690 \item signatures given for things not bound here;
691 \item with suitably flaggery, that all top-level things have type signatures.
694 At the moment we don't gather free-var info from the types in
695 signatures. We'd only need this if we wanted to report unused tyvars.
698 renameSigs :: (LSig Name -> Bool) -> [LSig RdrName] -> RnM [LSig Name]
699 -- Renames the signatures and performs error checks
700 renameSigs ok_sig sigs
701 = do { sigs' <- rename_sigs sigs
702 ; check_sigs ok_sig sigs'
705 ----------------------
706 rename_sigs :: [LSig RdrName] -> RnM [LSig Name]
707 rename_sigs sigs = mapM (wrapLocM renameSig) sigs
709 ----------------------
710 check_sigs :: (LSig Name -> Bool) -> [LSig Name] -> RnM ()
711 -- Used for class and instance decls, as well as regular bindings
712 check_sigs ok_sig sigs = do
713 -- Check for (a) duplicate signatures
714 -- (b) signatures for things not in this group = do
715 traceRn (text "SIGS" <+> ppr sigs)
716 mapM_ unknownSigErr (filter (not . ok_sig) sigs')
717 mapM_ dupSigDeclErr (findDupsEq eqHsSig sigs')
719 -- Don't complain about an unbound name again
720 sigs' = filterOut bad_name sigs
721 bad_name sig = case sigName sig of
722 Just n -> isUnboundName n
725 -- We use lookupLocatedSigOccRn in the signatures, which is a little bit unsatisfactory
726 -- because this won't work for:
727 -- instance Foo T where
730 -- We'll just rename the INLINE prag to refer to whatever other 'op'
731 -- is in scope. (I'm assuming that Baz.op isn't in scope unqualified.)
732 -- Doesn't seem worth much trouble to sort this.
734 renameSig :: Sig RdrName -> RnM (Sig Name)
735 -- FixitSig is renamed elsewhere.
736 renameSig (TypeSig v ty) = do
737 new_v <- lookupLocatedSigOccRn v
738 new_ty <- rnHsSigType (quotes (ppr v)) ty
739 return (TypeSig new_v new_ty)
741 renameSig (SpecInstSig ty) = do
742 new_ty <- rnLHsType (text "A SPECIALISE instance pragma") ty
743 return (SpecInstSig new_ty)
745 renameSig (SpecSig v ty inl) = do
746 new_v <- lookupLocatedSigOccRn v
747 new_ty <- rnHsSigType (quotes (ppr v)) ty
748 return (SpecSig new_v new_ty inl)
750 renameSig (InlineSig v s) = do
751 new_v <- lookupLocatedSigOccRn v
752 return (InlineSig new_v s)
754 renameSig (FixSig (FixitySig v f)) = do
755 new_v <- lookupLocatedSigOccRn v
756 return (FixSig (FixitySig new_v f))
760 ************************************************************************
764 ************************************************************************
767 rnMatchGroup :: HsMatchContext Name -> MatchGroup RdrName -> RnM (MatchGroup Name, FreeVars)
768 rnMatchGroup ctxt (MatchGroup ms _) = do
769 (new_ms, ms_fvs) <- mapFvRn (rnMatch ctxt) ms
770 return (MatchGroup new_ms placeHolderType, ms_fvs)
772 rnMatch :: HsMatchContext Name -> LMatch RdrName -> RnM (LMatch Name, FreeVars)
773 rnMatch ctxt = wrapLocFstM (rnMatch' ctxt)
775 rnMatch' ctxt match@(Match pats maybe_rhs_sig grhss)
777 -- Deal with the rhs type signature
778 bindPatSigTyVarsFV rhs_sig_tys $ do
779 opt_PatternSignatures <- doptM Opt_PatternSignatures
780 (maybe_rhs_sig', ty_fvs) <-
781 case maybe_rhs_sig of
782 Nothing -> return (Nothing, emptyFVs)
783 Just ty | opt_PatternSignatures -> do (ty', ty_fvs) <- rnHsTypeFVs doc_sig ty
784 return (Just ty', ty_fvs)
785 | otherwise -> do addLocErr ty patSigErr
786 return (Nothing, emptyFVs)
788 -- Now the main event
789 -- note that there are no local ficity decls for matches
790 rnPatsAndThen_LocalRightwards ctxt pats $ \ pats' -> do
791 (grhss', grhss_fvs) <- rnGRHSs ctxt grhss
793 return (Match pats' maybe_rhs_sig' grhss', grhss_fvs `plusFV` ty_fvs)
794 -- The bindPatSigTyVarsFV and rnPatsAndThen will remove the bound FVs
796 rhs_sig_tys = case maybe_rhs_sig of
799 doc_sig = text "In a result type-signature"
803 %************************************************************************
805 \subsubsection{Guarded right-hand sides (GRHSs)}
807 %************************************************************************
810 rnGRHSs :: HsMatchContext Name -> GRHSs RdrName -> RnM (GRHSs Name, FreeVars)
812 rnGRHSs ctxt (GRHSs grhss binds)
813 = rnLocalBindsAndThen binds $ \ binds' -> do
814 (grhss', fvGRHSs) <- mapFvRn (rnGRHS ctxt) grhss
815 return (GRHSs grhss' binds', fvGRHSs)
817 rnGRHS :: HsMatchContext Name -> LGRHS RdrName -> RnM (LGRHS Name, FreeVars)
818 rnGRHS ctxt = wrapLocFstM (rnGRHS' ctxt)
820 rnGRHS' ctxt (GRHS guards rhs)
821 = do { pattern_guards_allowed <- doptM Opt_PatternGuards
822 ; ((guards', rhs'), fvs) <- rnStmts (PatGuard ctxt) guards $
825 ; unless (pattern_guards_allowed || is_standard_guard guards')
826 (addWarn (nonStdGuardErr guards'))
828 ; return (GRHS guards' rhs', fvs) }
830 -- Standard Haskell 1.4 guards are just a single boolean
831 -- expression, rather than a list of qualifiers as in the
833 is_standard_guard [] = True
834 is_standard_guard [L _ (ExprStmt _ _ _)] = True
835 is_standard_guard other = False
838 %************************************************************************
840 \subsection{Error messages}
842 %************************************************************************
845 dupSigDeclErr sigs@(L loc sig : _)
847 vcat [ptext SLIT("Duplicate") <+> what_it_is <> colon,
848 nest 2 (vcat (map ppr_sig sigs))]
850 what_it_is = hsSigDoc sig
851 ppr_sig (L loc sig) = ppr loc <> colon <+> ppr sig
853 unknownSigErr (L loc sig)
854 = do { mod <- getModule
856 vcat [sep [ptext SLIT("Misplaced") <+> what_it_is <> colon, ppr sig],
857 extra_stuff mod sig] }
859 what_it_is = hsSigDoc sig
860 extra_stuff mod (TypeSig (L _ n) _)
861 | nameIsLocalOrFrom mod n
862 = ptext SLIT("The type signature must be given where")
863 <+> quotes (ppr n) <+> ptext SLIT("is declared")
865 = ptext SLIT("You cannot give a type signature for an imported value")
867 extra_stuff mod other = empty
870 = hang (ptext SLIT("Pattern bindings (except simple variables) not allowed in instance declarations"))
873 bindsInHsBootFile mbinds
874 = hang (ptext SLIT("Bindings in hs-boot files are not allowed"))
877 nonStdGuardErr guards
878 = hang (ptext SLIT("accepting non-standard pattern guards (use -XPatternGuards to suppress this message)"))
879 4 (interpp'SP guards)