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).
14 rnLocalBindsAndThen, rnValBindsAndThen, rnValBinds, trimWith,
15 rnMethodBinds, renameSigs,
19 #include "HsVersions.h"
21 import {-# SOURCE #-} RnExpr( rnLExpr, rnStmts )
27 import RnTypes ( rnHsSigType, rnLHsType, rnHsTypeFVs,
28 rnLPat, rnPatsAndThen, patSigErr, checkPrecMatch )
29 import RnEnv ( bindLocatedLocalsRn, lookupLocatedBndrRn,
30 lookupLocatedInstDeclBndr, newIPNameRn,
31 lookupLocatedSigOccRn, bindPatSigTyVars, bindPatSigTyVarsFV,
32 bindLocalFixities, bindSigTyVarsFV,
33 warnUnusedLocalBinds, mapFvRn, extendTyVarEnvFVRn,
35 import DynFlags ( DynFlag(..) )
36 import Name ( Name, nameOccName, nameSrcLoc )
39 import PrelNames ( isUnboundName )
40 import RdrName ( RdrName, rdrNameOcc )
41 import SrcLoc ( mkSrcSpan, Located(..), unLoc )
42 import ListSetOps ( findDupsEq )
43 import BasicTypes ( RecFlag(..) )
44 import Digraph ( SCC(..), stronglyConnComp )
47 import Maybes ( orElse, fromJust, isJust )
48 import Util ( filterOut )
49 import Monad ( foldM )
52 -- ToDo: Put the annotations into the monad, so that they arrive in the proper
53 -- place and can be used when complaining.
55 The code tree received by the function @rnBinds@ contains definitions
56 in where-clauses which are all apparently mutually recursive, but which may
57 not really depend upon each other. For example, in the top level program
62 the definitions of @a@ and @y@ do not depend on each other at all.
63 Unfortunately, the typechecker cannot always check such definitions.
64 \footnote{Mycroft, A. 1984. Polymorphic type schemes and recursive
65 definitions. In Proceedings of the International Symposium on Programming,
66 Toulouse, pp. 217-39. LNCS 167. Springer Verlag.}
67 However, the typechecker usually can check definitions in which only the
68 strongly connected components have been collected into recursive bindings.
69 This is precisely what the function @rnBinds@ does.
71 ToDo: deal with case where a single monobinds binds the same variable
74 The vertag tag is a unique @Int@; the tags only need to be unique
75 within one @MonoBinds@, so that unique-Int plumbing is done explicitly
76 (heavy monad machinery not needed).
79 %************************************************************************
81 %* naming conventions *
83 %************************************************************************
85 \subsection[name-conventions]{Name conventions}
87 The basic algorithm involves walking over the tree and returning a tuple
88 containing the new tree plus its free variables. Some functions, such
89 as those walking polymorphic bindings (HsBinds) and qualifier lists in
90 list comprehensions (@Quals@), return the variables bound in local
91 environments. These are then used to calculate the free variables of the
92 expression evaluated in these environments.
94 Conventions for variable names are as follows:
97 new code is given a prime to distinguish it from the old.
100 a set of variables defined in @Exp@ is written @dvExp@
103 a set of variables free in @Exp@ is written @fvExp@
106 %************************************************************************
108 %* analysing polymorphic bindings (HsBindGroup, HsBind)
110 %************************************************************************
112 \subsubsection[dep-HsBinds]{Polymorphic bindings}
114 Non-recursive expressions are reconstructed without any changes at top
115 level, although their component expressions may have to be altered.
116 However, non-recursive expressions are currently not expected as
117 \Haskell{} programs, and this code should not be executed.
119 Monomorphic bindings contain information that is returned in a tuple
120 (a @FlatMonoBinds@) containing:
124 a unique @Int@ that serves as the ``vertex tag'' for this binding.
127 the name of a function or the names in a pattern. These are a set
128 referred to as @dvLhs@, the defined variables of the left hand side.
131 the free variables of the body. These are referred to as @fvBody@.
134 the definition's actual code. This is referred to as just @code@.
137 The function @nonRecDvFv@ returns two sets of variables. The first is
138 the set of variables defined in the set of monomorphic bindings, while the
139 second is the set of free variables in those bindings.
141 The set of variables defined in a non-recursive binding is just the
142 union of all of them, as @union@ removes duplicates. However, the
143 free variables in each successive set of cumulative bindings is the
144 union of those in the previous set plus those of the newest binding after
145 the defined variables of the previous set have been removed.
147 @rnMethodBinds@ deals only with the declarations in class and
148 instance declarations. It expects only to see @FunMonoBind@s, and
149 it expects the global environment to contain bindings for the binders
150 (which are all class operations).
152 %************************************************************************
154 \subsubsection{ Top-level bindings}
156 %************************************************************************
158 @rnTopMonoBinds@ assumes that the environment already
159 contains bindings for the binders of this particular binding.
162 rnTopBinds :: HsValBinds RdrName -> RnM (HsValBinds Name, DefUses)
164 -- The binders of the binding are in scope already;
165 -- the top level scope resolution does that
168 = do { is_boot <- tcIsHsBoot
169 ; if is_boot then rnTopBindsBoot binds
170 else rnTopBindsSrc binds }
172 rnTopBindsBoot :: HsValBinds RdrName -> RnM (HsValBinds Name, DefUses)
173 -- A hs-boot file has no bindings.
174 -- Return a single HsBindGroup with empty binds and renamed signatures
175 rnTopBindsBoot (ValBindsIn mbinds sigs)
176 = do { checkErr (isEmptyLHsBinds mbinds) (bindsInHsBootFile mbinds)
177 ; sigs' <- renameSigs okHsBootSig sigs
178 ; return (ValBindsOut [] sigs', usesOnly (hsSigsFVs sigs')) }
180 rnTopBindsSrc :: HsValBinds RdrName -> RnM (HsValBinds Name, DefUses)
181 rnTopBindsSrc binds@(ValBindsIn mbinds _)
182 = do { (binds', dus) <- rnValBinds noTrim binds
184 -- Warn about missing signatures,
185 ; let { ValBindsOut _ sigs' = binds'
186 ; ty_sig_vars = mkNameSet [ unLoc n | L _ (TypeSig n _) <- sigs']
187 ; un_sigd_bndrs = duDefs dus `minusNameSet` ty_sig_vars }
189 ; warn_missing_sigs <- doptM Opt_WarnMissingSigs
190 ; ifM (warn_missing_sigs)
191 (mappM_ missingSigWarn (nameSetToList un_sigd_bndrs))
193 ; return (binds', dus)
199 %*********************************************************
203 %*********************************************************
207 :: HsLocalBinds RdrName
208 -> (HsLocalBinds Name -> RnM (result, FreeVars))
209 -> RnM (result, FreeVars)
210 -- This version (a) assumes that the binding vars are not already in scope
211 -- (b) removes the binders from the free vars of the thing inside
212 -- The parser doesn't produce ThenBinds
213 rnLocalBindsAndThen EmptyLocalBinds thing_inside
214 = thing_inside EmptyLocalBinds
216 rnLocalBindsAndThen (HsValBinds val_binds) thing_inside
217 = rnValBindsAndThen val_binds $ \ val_binds' ->
218 thing_inside (HsValBinds val_binds')
220 rnLocalBindsAndThen (HsIPBinds binds) thing_inside
221 = rnIPBinds binds `thenM` \ (binds',fv_binds) ->
222 thing_inside (HsIPBinds binds') `thenM` \ (thing, fvs_thing) ->
223 returnM (thing, fvs_thing `plusFV` fv_binds)
226 rnIPBinds (IPBinds ip_binds _no_dict_binds)
227 = do { (ip_binds', fvs_s) <- mapAndUnzipM (wrapLocFstM rnIPBind) ip_binds
228 ; return (IPBinds ip_binds' emptyLHsBinds, plusFVs fvs_s) }
230 rnIPBind (IPBind n expr)
231 = newIPNameRn n `thenM` \ name ->
232 rnLExpr expr `thenM` \ (expr',fvExpr) ->
233 return (IPBind name expr', fvExpr)
237 %************************************************************************
241 %************************************************************************
244 rnValBindsAndThen :: HsValBinds RdrName
245 -> (HsValBinds Name -> RnM (result, FreeVars))
246 -> RnM (result, FreeVars)
248 rnValBindsAndThen binds@(ValBindsIn mbinds sigs) thing_inside
249 = -- Extract all the binders in this group, and extend the
250 -- current scope, inventing new names for the new binders
251 -- This also checks that the names form a set
252 bindLocatedLocalsRn doc mbinders_w_srclocs $ \ bndrs ->
254 -- Then install local fixity declarations
255 -- Notice that they scope over thing_inside too
256 bindLocalFixities [sig | L _ (FixSig sig) <- sigs ] $
259 rnValBinds (trimWith bndrs) binds `thenM` \ (binds, bind_dus) ->
261 -- Now do the "thing inside"
262 thing_inside binds `thenM` \ (result,result_fvs) ->
264 -- Final error checking
266 all_uses = duUses bind_dus `plusFV` result_fvs
267 -- duUses: It's important to return all the uses, not the 'real uses'
268 -- used for warning about unused bindings. Otherwise consider:
270 -- y = let p = x in 'x' -- NB: p not used
271 -- If we don't "see" the dependency of 'y' on 'x', we may put the
272 -- bindings in the wrong order, and the type checker will complain
273 -- that x isn't in scope
275 unused_bndrs = [ b | b <- bndrs, not (b `elemNameSet` all_uses)]
277 warnUnusedLocalBinds unused_bndrs `thenM_`
279 returnM (result, delListFromNameSet all_uses bndrs)
281 mbinders_w_srclocs = collectHsBindLocatedBinders mbinds
282 doc = text "In the binding group for:"
283 <+> pprWithCommas ppr (map unLoc mbinders_w_srclocs)
285 ---------------------
286 rnValBinds :: (FreeVars -> FreeVars)
287 -> HsValBinds RdrName
288 -> RnM (HsValBinds Name, DefUses)
289 -- Assumes the binders of the binding are in scope already
291 rnValBinds trim (ValBindsIn mbinds sigs)
292 = do { sigs' <- rename_sigs sigs
294 ; binds_w_dus <- mapBagM (rnBind (mkSigTvFn sigs') trim) mbinds
296 ; let (binds', bind_dus) = depAnalBinds binds_w_dus
298 -- We do the check-sigs after renaming the bindings,
299 -- so that we have convenient access to the binders
300 ; check_sigs (okBindSig (duDefs bind_dus)) sigs'
302 ; return (ValBindsOut binds' sigs',
303 usesOnly (hsSigsFVs sigs') `plusDU` bind_dus) }
306 ---------------------
307 depAnalBinds :: Bag (LHsBind Name, [Name], Uses)
308 -> ([(RecFlag, LHsBinds Name)], DefUses)
309 -- Dependency analysis; this is important so that
310 -- unused-binding reporting is accurate
311 depAnalBinds binds_w_dus
312 = (map get_binds sccs, map get_du sccs)
314 sccs = stronglyConnComp edges
316 keyd_nodes = bagToList binds_w_dus `zip` [0::Int ..]
318 edges = [ (node, key, [fromJust mb_key | n <- nameSetToList uses,
319 let mb_key = lookupNameEnv key_map n,
321 | (node@(_,_,uses), key) <- keyd_nodes ]
323 key_map :: NameEnv Int -- Which binding it comes from
324 key_map = mkNameEnv [(bndr, key) | ((_, bndrs, _), key) <- keyd_nodes
327 get_binds (AcyclicSCC (bind, _, _)) = (NonRecursive, unitBag bind)
328 get_binds (CyclicSCC binds_w_dus) = (Recursive, listToBag [b | (b,d,u) <- binds_w_dus])
330 get_du (AcyclicSCC (_, bndrs, uses)) = (Just (mkNameSet bndrs), uses)
331 get_du (CyclicSCC binds_w_dus) = (Just defs, uses)
333 defs = mkNameSet [b | (_,bs,_) <- binds_w_dus, b <- bs]
334 uses = unionManyNameSets [u | (_,_,u) <- binds_w_dus]
337 ---------------------
338 -- Bind the top-level forall'd type variables in the sigs.
341 -- The 'a' scopes over the rhs
343 -- NB: there'll usually be just one (for a function binding)
344 -- but if there are many, one may shadow the rest; too bad!
345 -- e.g x :: [a] -> [a]
348 -- In e, 'a' will be in scope, and it'll be the one from 'y'!
350 mkSigTvFn :: [LSig Name] -> (Name -> [Name])
351 -- Return a lookup function that maps an Id Name to the names
352 -- of the type variables that should scope over its body..
354 = \n -> lookupNameEnv env n `orElse` []
356 env :: NameEnv [Name]
357 env = mkNameEnv [ (name, map hsLTyVarName ltvs)
358 | L _ (TypeSig (L _ name)
359 (L _ (HsForAllTy Explicit ltvs _ _))) <- sigs]
360 -- Note the pattern-match on "Explicit"; we only bind
361 -- type variables from signatures with an explicit top-level for-all
363 -- The trimming function trims the free vars we attach to a
364 -- binding so that it stays reasonably small
365 noTrim :: FreeVars -> FreeVars
366 noTrim fvs = fvs -- Used at top level
368 trimWith :: [Name] -> FreeVars -> FreeVars
369 -- Nested bindings; trim by intersection with the names bound here
370 trimWith bndrs = intersectNameSet (mkNameSet bndrs)
372 ---------------------
373 rnBind :: (Name -> [Name]) -- Signature tyvar function
374 -> (FreeVars -> FreeVars) -- Trimming function for rhs free vars
376 -> RnM (LHsBind Name, [Name], Uses)
377 rnBind sig_fn trim (L loc (PatBind { pat_lhs = pat, pat_rhs = grhss }))
379 do { (pat', pat_fvs) <- rnLPat pat
381 ; let bndrs = collectPatBinders pat'
383 ; (grhss', fvs) <- bindSigTyVarsFV (concatMap sig_fn bndrs) $
384 rnGRHSs PatBindRhs grhss
386 ; return (L loc (PatBind { pat_lhs = pat', pat_rhs = grhss',
387 pat_rhs_ty = placeHolderType, bind_fvs = trim fvs }),
388 bndrs, pat_fvs `plusFV` fvs) }
390 rnBind sig_fn trim (L loc (FunBind { fun_id = name, fun_infix = inf, fun_matches = matches }))
392 do { new_name <- lookupLocatedBndrRn name
393 ; let plain_name = unLoc new_name
395 ; (matches', fvs) <- bindSigTyVarsFV (sig_fn plain_name) $
396 rnMatchGroup (FunRhs plain_name) matches
398 ; checkPrecMatch inf plain_name matches'
400 ; return (L loc (FunBind { fun_id = new_name, fun_infix = inf, fun_matches = matches',
401 bind_fvs = trim fvs, fun_co_fn = idCoercion }),
407 @rnMethodBinds@ is used for the method bindings of a class and an instance
408 declaration. Like @rnBinds@ but without dependency analysis.
410 NOTA BENE: we record each {\em binder} of a method-bind group as a free variable.
411 That's crucial when dealing with an instance decl:
413 instance Foo (T a) where
416 This might be the {\em sole} occurrence of @op@ for an imported class @Foo@,
417 and unless @op@ occurs we won't treat the type signature of @op@ in the class
418 decl for @Foo@ as a source of instance-decl gates. But we should! Indeed,
419 in many ways the @op@ in an instance decl is just like an occurrence, not
423 rnMethodBinds :: Name -- Class name
424 -> [Name] -- Names for generic type variables
426 -> RnM (LHsBinds Name, FreeVars)
428 rnMethodBinds cls gen_tyvars binds
429 = foldM do_one (emptyBag,emptyFVs) (bagToList binds)
430 where do_one (binds,fvs) bind = do
431 (bind', fvs_bind) <- rnMethodBind cls gen_tyvars bind
432 return (bind' `unionBags` binds, fvs_bind `plusFV` fvs)
434 rnMethodBind cls gen_tyvars (L loc (FunBind { fun_id = name, fun_infix = inf,
435 fun_matches = MatchGroup matches _ }))
437 lookupLocatedInstDeclBndr cls name `thenM` \ sel_name ->
438 let plain_name = unLoc sel_name in
439 -- We use the selector name as the binder
441 mapFvRn (rn_match plain_name) matches `thenM` \ (new_matches, fvs) ->
443 new_group = MatchGroup new_matches placeHolderType
445 checkPrecMatch inf plain_name new_group `thenM_`
446 returnM (unitBag (L loc (FunBind { fun_id = sel_name, fun_infix = inf, fun_matches = new_group,
447 bind_fvs = fvs, fun_co_fn = idCoercion })),
448 fvs `addOneFV` plain_name)
449 -- The 'fvs' field isn't used for method binds
451 -- Truly gruesome; bring into scope the correct members of the generic
452 -- type variables. See comments in RnSource.rnSourceDecl(ClassDecl)
453 rn_match sel_name match@(L _ (Match (L _ (TypePat ty) : _) _ _))
454 = extendTyVarEnvFVRn gen_tvs $
455 rnMatch (FunRhs sel_name) match
457 tvs = map (rdrNameOcc.unLoc) (extractHsTyRdrTyVars ty)
458 gen_tvs = [tv | tv <- gen_tyvars, nameOccName tv `elem` tvs]
460 rn_match sel_name match = rnMatch (FunRhs sel_name) match
463 -- Can't handle method pattern-bindings which bind multiple methods.
464 rnMethodBind cls gen_tyvars mbind@(L loc (PatBind other_pat _ _ _))
465 = addLocErr mbind methodBindErr `thenM_`
466 returnM (emptyBag, emptyFVs)
470 %************************************************************************
472 \subsubsection[dep-Sigs]{Signatures (and user-pragmas for values)}
474 %************************************************************************
476 @renameSigs@ checks for:
478 \item more than one sig for one thing;
479 \item signatures given for things not bound here;
480 \item with suitably flaggery, that all top-level things have type signatures.
483 At the moment we don't gather free-var info from the types in
484 signatures. We'd only need this if we wanted to report unused tyvars.
487 renameSigs :: (LSig Name -> Bool) -> [LSig RdrName] -> RnM [LSig Name]
488 -- Renames the signatures and performs error checks
489 renameSigs ok_sig sigs
490 = do { sigs' <- rename_sigs sigs
491 ; check_sigs ok_sig sigs'
494 ----------------------
495 rename_sigs :: [LSig RdrName] -> RnM [LSig Name]
496 rename_sigs sigs = mappM (wrapLocM renameSig)
497 (filter (not . isFixityLSig) sigs)
498 -- Remove fixity sigs which have been dealt with already
500 ----------------------
501 check_sigs :: (LSig Name -> Bool) -> [LSig Name] -> RnM ()
502 -- Used for class and instance decls, as well as regular bindings
503 check_sigs ok_sig sigs
504 -- Check for (a) duplicate signatures
505 -- (b) signatures for things not in this group
506 = do { mappM_ unknownSigErr (filter (not . ok_sig) sigs')
507 ; mappM_ dupSigDeclErr (findDupsEq eqHsSig sigs') }
509 -- Don't complain about an unbound name again
510 sigs' = filterOut bad_name sigs
511 bad_name sig = case sigName sig of
512 Just n -> isUnboundName n
515 -- We use lookupLocatedSigOccRn in the signatures, which is a little bit unsatisfactory
516 -- because this won't work for:
517 -- instance Foo T where
520 -- We'll just rename the INLINE prag to refer to whatever other 'op'
521 -- is in scope. (I'm assuming that Baz.op isn't in scope unqualified.)
522 -- Doesn't seem worth much trouble to sort this.
524 renameSig :: Sig RdrName -> RnM (Sig Name)
525 -- FixitSig is renamed elsewhere.
526 renameSig (TypeSig v ty)
527 = lookupLocatedSigOccRn v `thenM` \ new_v ->
528 rnHsSigType (quotes (ppr v)) ty `thenM` \ new_ty ->
529 returnM (TypeSig new_v new_ty)
531 renameSig (SpecInstSig ty)
532 = rnLHsType (text "A SPECIALISE instance pragma") ty `thenM` \ new_ty ->
533 returnM (SpecInstSig new_ty)
535 renameSig (SpecSig v ty inl)
536 = lookupLocatedSigOccRn v `thenM` \ new_v ->
537 rnHsSigType (quotes (ppr v)) ty `thenM` \ new_ty ->
538 returnM (SpecSig new_v new_ty inl)
540 renameSig (InlineSig v s)
541 = lookupLocatedSigOccRn v `thenM` \ new_v ->
542 returnM (InlineSig new_v s)
546 ************************************************************************
550 ************************************************************************
553 rnMatchGroup :: HsMatchContext Name -> MatchGroup RdrName -> RnM (MatchGroup Name, FreeVars)
554 rnMatchGroup ctxt (MatchGroup ms _)
555 = mapFvRn (rnMatch ctxt) ms `thenM` \ (new_ms, ms_fvs) ->
556 returnM (MatchGroup new_ms placeHolderType, ms_fvs)
558 rnMatch :: HsMatchContext Name -> LMatch RdrName -> RnM (LMatch Name, FreeVars)
559 rnMatch ctxt = wrapLocFstM (rnMatch' ctxt)
561 rnMatch' ctxt match@(Match pats maybe_rhs_sig grhss)
563 -- Deal with the rhs type signature
564 bindPatSigTyVarsFV rhs_sig_tys $
565 doptM Opt_GlasgowExts `thenM` \ opt_GlasgowExts ->
566 (case maybe_rhs_sig of
567 Nothing -> returnM (Nothing, emptyFVs)
568 Just ty | opt_GlasgowExts -> rnHsTypeFVs doc_sig ty `thenM` \ (ty', ty_fvs) ->
569 returnM (Just ty', ty_fvs)
570 | otherwise -> addLocErr ty patSigErr `thenM_`
571 returnM (Nothing, emptyFVs)
572 ) `thenM` \ (maybe_rhs_sig', ty_fvs) ->
574 -- Now the main event
575 rnPatsAndThen ctxt pats $ \ pats' ->
576 rnGRHSs ctxt grhss `thenM` \ (grhss', grhss_fvs) ->
578 returnM (Match pats' maybe_rhs_sig' grhss', grhss_fvs `plusFV` ty_fvs)
579 -- The bindPatSigTyVarsFV and rnPatsAndThen will remove the bound FVs
581 rhs_sig_tys = case maybe_rhs_sig of
584 doc_sig = text "In a result type-signature"
588 %************************************************************************
590 \subsubsection{Guarded right-hand sides (GRHSs)}
592 %************************************************************************
595 rnGRHSs :: HsMatchContext Name -> GRHSs RdrName -> RnM (GRHSs Name, FreeVars)
597 rnGRHSs ctxt (GRHSs grhss binds)
598 = rnLocalBindsAndThen binds $ \ binds' ->
599 mapFvRn (rnGRHS ctxt) grhss `thenM` \ (grhss', fvGRHSs) ->
600 returnM (GRHSs grhss' binds', fvGRHSs)
602 rnGRHS :: HsMatchContext Name -> LGRHS RdrName -> RnM (LGRHS Name, FreeVars)
603 rnGRHS ctxt = wrapLocFstM (rnGRHS' ctxt)
605 rnGRHS' ctxt (GRHS guards rhs)
606 = do { opt_GlasgowExts <- doptM Opt_GlasgowExts
607 ; ((guards', rhs'), fvs) <- rnStmts (PatGuard ctxt) guards $
610 ; checkM (opt_GlasgowExts || is_standard_guard guards')
611 (addWarn (nonStdGuardErr guards'))
613 ; return (GRHS guards' rhs', fvs) }
615 -- Standard Haskell 1.4 guards are just a single boolean
616 -- expression, rather than a list of qualifiers as in the
618 is_standard_guard [] = True
619 is_standard_guard [L _ (ExprStmt _ _ _)] = True
620 is_standard_guard other = False
623 %************************************************************************
625 \subsection{Error messages}
627 %************************************************************************
630 dupSigDeclErr sigs@(L loc sig : _)
632 vcat [ptext SLIT("Duplicate") <+> what_it_is <> colon,
633 nest 2 (vcat (map ppr_sig sigs))]
635 what_it_is = hsSigDoc sig
636 ppr_sig (L loc sig) = ppr loc <> colon <+> ppr sig
638 unknownSigErr (L loc sig)
640 sep [ptext SLIT("Misplaced") <+> what_it_is <> colon, ppr sig]
642 what_it_is = hsSigDoc sig
645 = addWarnAt (mkSrcSpan loc loc) $
646 sep [ptext SLIT("Definition but no type signature for"), quotes (ppr var)]
648 loc = nameSrcLoc var -- TODO: make a proper span
651 = hang (ptext SLIT("Pattern bindings (except simple variables) not allowed in instance declarations"))
654 bindsInHsBootFile mbinds
655 = hang (ptext SLIT("Bindings in hs-boot files are not allowed"))
658 nonStdGuardErr guards
659 = hang (ptext SLIT("accepting non-standard pattern guards (-fglasgow-exts to suppress this message)"))
660 4 (interpp'SP guards)