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 rnTopBinds, rnTopMonoBinds,
14 rnMethodBinds, renameSigs,
19 #include "HsVersions.h"
21 import {-# SOURCE #-} RnSource ( rnHsSigType )
24 import HsBinds ( sigsForMe )
28 import RnExpr ( rnMatch, rnGRHSs, rnPat, checkPrecMatch )
29 import RnEnv ( bindLocatedLocalsRn, lookupBndrRn, lookupGlobalOccRn,
30 warnUnusedLocalBinds, mapFvRn,
31 FreeVars, emptyFVs, plusFV, plusFVs, unitFV, addOneFV,
34 import CmdLineOpts ( opt_WarnMissingSigs )
35 import Digraph ( stronglyConnComp, SCC(..) )
36 import Name ( OccName, Name, nameOccName )
38 import RdrName ( RdrName, rdrNameOcc )
39 import BasicTypes ( RecFlag(..), TopLevelFlag(..) )
40 import Util ( thenCmp, removeDups )
41 import List ( partition )
42 import ListSetOps ( minusList )
43 import Bag ( bagToList )
44 import FiniteMap ( lookupFM, listToFM )
45 import Maybe ( isJust )
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).
77 type Cycle = [VertexTag]
78 type Edge = (VertexTag, VertexTag)
81 %************************************************************************
83 %* naming conventions *
85 %************************************************************************
87 \subsection[name-conventions]{Name conventions}
89 The basic algorithm involves walking over the tree and returning a tuple
90 containing the new tree plus its free variables. Some functions, such
91 as those walking polymorphic bindings (HsBinds) and qualifier lists in
92 list comprehensions (@Quals@), return the variables bound in local
93 environments. These are then used to calculate the free variables of the
94 expression evaluated in these environments.
96 Conventions for variable names are as follows:
99 new code is given a prime to distinguish it from the old.
102 a set of variables defined in @Exp@ is written @dvExp@
105 a set of variables free in @Exp@ is written @fvExp@
108 %************************************************************************
110 %* analysing polymorphic bindings (HsBinds, Bind, MonoBinds) *
112 %************************************************************************
114 \subsubsection[dep-HsBinds]{Polymorphic bindings}
116 Non-recursive expressions are reconstructed without any changes at top
117 level, although their component expressions may have to be altered.
118 However, non-recursive expressions are currently not expected as
119 \Haskell{} programs, and this code should not be executed.
121 Monomorphic bindings contain information that is returned in a tuple
122 (a @FlatMonoBindsInfo@) containing:
126 a unique @Int@ that serves as the ``vertex tag'' for this binding.
129 the name of a function or the names in a pattern. These are a set
130 referred to as @dvLhs@, the defined variables of the left hand side.
133 the free variables of the body. These are referred to as @fvBody@.
136 the definition's actual code. This is referred to as just @code@.
139 The function @nonRecDvFv@ returns two sets of variables. The first is
140 the set of variables defined in the set of monomorphic bindings, while the
141 second is the set of free variables in those bindings.
143 The set of variables defined in a non-recursive binding is just the
144 union of all of them, as @union@ removes duplicates. However, the
145 free variables in each successive set of cumulative bindings is the
146 union of those in the previous set plus those of the newest binding after
147 the defined variables of the previous set have been removed.
149 @rnMethodBinds@ deals only with the declarations in class and
150 instance declarations. It expects only to see @FunMonoBind@s, and
151 it expects the global environment to contain bindings for the binders
152 (which are all class operations).
154 %************************************************************************
156 \subsubsection{ Top-level bindings}
158 %************************************************************************
160 @rnTopBinds@ assumes that the environment already
161 contains bindings for the binders of this particular binding.
164 rnTopBinds :: RdrNameHsBinds -> RnMS (RenamedHsBinds, FreeVars)
166 rnTopBinds EmptyBinds = returnRn (EmptyBinds, emptyFVs)
167 rnTopBinds (MonoBind bind sigs _) = rnTopMonoBinds bind sigs
168 -- The parser doesn't produce other forms
171 rnTopMonoBinds EmptyMonoBinds sigs
172 = returnRn (EmptyBinds, emptyFVs)
174 rnTopMonoBinds mbinds sigs
175 = mapRn lookupBndrRn binder_rdr_names `thenRn` \ binder_names ->
177 binder_set = mkNameSet binder_names
178 binder_occ_fm = listToFM [(nameOccName x,x) | x <- binder_names]
180 renameSigs opt_WarnMissingSigs binder_set
181 (lookupSigOccRn binder_occ_fm) sigs `thenRn` \ (siglist, sig_fvs) ->
182 rn_mono_binds siglist mbinds `thenRn` \ (final_binds, bind_fvs) ->
183 returnRn (final_binds, bind_fvs `plusFV` sig_fvs)
185 binder_rdr_names = map fst (bagToList (collectMonoBinders mbinds))
187 -- the names appearing in the sigs have to be bound by
188 -- this group's binders.
189 lookupSigOccRn binder_occ_fm rdr_name
190 = case lookupFM binder_occ_fm (rdrNameOcc rdr_name) of
191 Nothing -> failWithRn (mkUnboundName rdr_name)
192 (unknownNameErr rdr_name)
196 %************************************************************************
200 %************************************************************************
202 \subsubsection{Nested binds}
206 \item collects up the binders for this declaration group,
207 \item checks that they form a set
208 \item extends the environment to bind them to new local names
209 \item calls @rnMonoBinds@ to do the real work
213 rnBinds :: RdrNameHsBinds
214 -> (RenamedHsBinds -> RnMS (result, FreeVars))
215 -> RnMS (result, FreeVars)
217 rnBinds EmptyBinds thing_inside = thing_inside EmptyBinds
218 rnBinds (MonoBind bind sigs _) thing_inside = rnMonoBinds bind sigs thing_inside
219 -- the parser doesn't produce other forms
222 rnMonoBinds :: RdrNameMonoBinds
224 -> (RenamedHsBinds -> RnMS (result, FreeVars))
225 -> RnMS (result, FreeVars)
227 rnMonoBinds EmptyMonoBinds sigs thing_inside = thing_inside EmptyBinds
229 rnMonoBinds mbinds sigs thing_inside -- Non-empty monobinds
230 = -- Extract all the binders in this group,
231 -- and extend current scope, inventing new names for the new binders
232 -- This also checks that the names form a set
233 bindLocatedLocalsRn (text "a binding group") mbinders_w_srclocs
236 binder_set = mkNameSet new_mbinders
238 -- Weed out the fixity declarations that do not
239 -- apply to any of the binders in this group.
240 (sigs_for_me, fixes_not_for_me) = partition forLocalBind sigs
242 forLocalBind (FixSig sig@(FixitySig name _ _ )) =
243 isJust (lookupFM binder_occ_fm (rdrNameOcc name))
244 forLocalBind _ = True
246 binder_occ_fm = listToFM [(nameOccName x,x) | x <- new_mbinders]
249 -- Rename the signatures
250 renameSigs False binder_set
251 (lookupSigOccRn binder_occ_fm) sigs_for_me `thenRn` \ (siglist, sig_fvs) ->
253 -- Report the fixity declarations in this group that
254 -- don't refer to any of the group's binders.
255 -- Then install the fixity declarations that do apply here
256 -- Notice that they scope over thing_inside too
257 mapRn_ (unknownSigErr) fixes_not_for_me `thenRn_`
259 fixity_sigs = [(name,sig) | FixSig sig@(FixitySig name _ _) <- siglist ]
261 extendFixityEnv fixity_sigs $
263 rn_mono_binds siglist mbinds `thenRn` \ (binds, bind_fvs) ->
265 -- Now do the "thing inside", and deal with the free-variable calculations
266 thing_inside binds `thenRn` \ (result,result_fvs) ->
268 all_fvs = result_fvs `plusFV` bind_fvs `plusFV` sig_fvs
269 unused_binders = nameSetToList (binder_set `minusNameSet` all_fvs)
271 warnUnusedLocalBinds unused_binders `thenRn_`
272 returnRn (result, delListFromNameSet all_fvs new_mbinders)
274 mbinders_w_srclocs = bagToList (collectMonoBinders mbinds)
278 %************************************************************************
280 \subsubsection{ MonoBinds -- the main work is done here}
282 %************************************************************************
284 @rn_mono_binds@ is used by {\em both} top-level and nested bindings.
285 It assumes that all variables bound in this group are already in scope.
286 This is done {\em either} by pass 3 (for the top-level bindings),
287 {\em or} by @rnMonoBinds@ (for the nested ones).
290 rn_mono_binds :: [RenamedSig] -- Signatures attached to this group
292 -> RnMS (RenamedHsBinds, --
293 FreeVars) -- Free variables
295 rn_mono_binds siglist mbinds
297 -- Rename the bindings, returning a MonoBindsInfo
298 -- which is a list of indivisible vertices so far as
299 -- the strongly-connected-components (SCC) analysis is concerned
300 flattenMonoBinds siglist mbinds `thenRn` \ mbinds_info ->
302 -- Do the SCC analysis
304 edges = mkEdges (mbinds_info `zip` [(0::Int)..])
305 scc_result = stronglyConnComp edges
306 final_binds = foldr1 ThenBinds (map reconstructCycle scc_result)
308 -- Deal with bound and free-var calculation
309 rhs_fvs = plusFVs [fvs | (_,fvs,_,_) <- mbinds_info]
311 returnRn (final_binds, rhs_fvs)
314 @flattenMonoBinds@ is ever-so-slightly magical in that it sticks
315 unique ``vertex tags'' on its output; minor plumbing required.
317 Sigh --- need to pass along the signatures for the group of bindings,
318 in case any of them \fbox{\ ???\ }
321 flattenMonoBinds :: [RenamedSig] -- Signatures
323 -> RnMS [FlatMonoBindsInfo]
325 flattenMonoBinds sigs EmptyMonoBinds = returnRn []
327 flattenMonoBinds sigs (AndMonoBinds bs1 bs2)
328 = flattenMonoBinds sigs bs1 `thenRn` \ flat1 ->
329 flattenMonoBinds sigs bs2 `thenRn` \ flat2 ->
330 returnRn (flat1 ++ flat2)
332 flattenMonoBinds sigs (PatMonoBind pat grhss locn)
333 = pushSrcLocRn locn $
334 rnPat pat `thenRn` \ (pat', pat_fvs) ->
336 -- Find which things are bound in this group
338 names_bound_here = mkNameSet (collectPatBinders pat')
339 sigs_for_me = sigsForMe (`elemNameSet` names_bound_here) sigs
341 rnGRHSs grhss `thenRn` \ (grhss', fvs) ->
344 fvs `plusFV` pat_fvs,
345 PatMonoBind pat' grhss' locn,
349 flattenMonoBinds sigs (FunMonoBind name inf matches locn)
350 = pushSrcLocRn locn $
351 lookupBndrRn name `thenRn` \ new_name ->
353 sigs_for_me = sigsForMe (new_name ==) sigs
355 mapFvRn rnMatch matches `thenRn` \ (new_matches, fvs) ->
356 mapRn_ (checkPrecMatch inf new_name) new_matches `thenRn_`
358 [(unitNameSet new_name,
360 FunMonoBind new_name inf new_matches locn,
366 @rnMethodBinds@ is used for the method bindings of a class and an instance
367 declaration. Like @rnMonoBinds@ but without dependency analysis.
369 NOTA BENE: we record each {\em binder} of a method-bind group as a free variable.
370 That's crucial when dealing with an instance decl:
372 instance Foo (T a) where
375 This might be the {\em sole} occurrence of @op@ for an imported class @Foo@,
376 and unless @op@ occurs we won't treat the type signature of @op@ in the class
377 decl for @Foo@ as a source of instance-decl gates. But we should! Indeed,
378 in many ways the @op@ in an instance decl is just like an occurrence, not
382 rnMethodBinds :: RdrNameMonoBinds -> RnMS (RenamedMonoBinds, FreeVars)
384 rnMethodBinds EmptyMonoBinds = returnRn (EmptyMonoBinds, emptyFVs)
386 rnMethodBinds (AndMonoBinds mb1 mb2)
387 = rnMethodBinds mb1 `thenRn` \ (mb1', fvs1) ->
388 rnMethodBinds mb2 `thenRn` \ (mb2', fvs2) ->
389 returnRn (mb1' `AndMonoBinds` mb2', fvs1 `plusFV` fvs2)
391 rnMethodBinds (FunMonoBind name inf matches locn)
392 = pushSrcLocRn locn $
394 lookupGlobalOccRn name `thenRn` \ sel_name ->
395 -- We use the selector name as the binder
397 mapFvRn rnMatch matches `thenRn` \ (new_matches, fvs) ->
398 mapRn_ (checkPrecMatch inf sel_name) new_matches `thenRn_`
399 returnRn (FunMonoBind sel_name inf new_matches locn, fvs `addOneFV` sel_name)
401 rnMethodBinds (PatMonoBind (VarPatIn name) grhss locn)
402 = pushSrcLocRn locn $
403 lookupGlobalOccRn name `thenRn` \ sel_name ->
404 rnGRHSs grhss `thenRn` \ (grhss', fvs) ->
405 returnRn (PatMonoBind (VarPatIn sel_name) grhss' locn, fvs `addOneFV` sel_name)
407 -- Can't handle method pattern-bindings which bind multiple methods.
408 rnMethodBinds mbind@(PatMonoBind other_pat _ locn)
409 = pushSrcLocRn locn $
410 failWithRn (EmptyMonoBinds, emptyFVs) (methodBindErr mbind)
414 %************************************************************************
416 \subsection[reconstruct-deps]{Reconstructing dependencies}
418 %************************************************************************
420 This @MonoBinds@- and @ClassDecls@-specific code is segregated here,
421 as the two cases are similar.
424 reconstructCycle :: SCC FlatMonoBindsInfo
427 reconstructCycle (AcyclicSCC (_, _, binds, sigs))
428 = MonoBind binds sigs NonRecursive
430 reconstructCycle (CyclicSCC cycle)
431 = MonoBind this_gp_binds this_gp_sigs Recursive
433 this_gp_binds = foldr1 AndMonoBinds [binds | (_, _, binds, _) <- cycle]
434 this_gp_sigs = foldr1 (++) [sigs | (_, _, _, sigs) <- cycle]
437 %************************************************************************
439 \subsubsection{ Manipulating FlatMonoBindInfo}
441 %************************************************************************
443 During analysis a @MonoBinds@ is flattened to a @FlatMonoBindsInfo@.
444 The @RenamedMonoBinds@ is always an empty bind, a pattern binding or
445 a function binding, and has itself been dependency-analysed and
449 type FlatMonoBindsInfo
450 = (NameSet, -- Set of names defined in this vertex
451 NameSet, -- Set of names used in this vertex
453 [RenamedSig]) -- Signatures, if any, for this vertex
455 mkEdges :: [(FlatMonoBindsInfo, VertexTag)] -> [(FlatMonoBindsInfo, VertexTag, [VertexTag])]
458 = [ (info, tag, dest_vertices (nameSetToList names_used))
459 | (info@(names_defined, names_used, mbind, sigs), tag) <- flat_info
462 -- An edge (v,v') indicates that v depends on v'
463 dest_vertices src_mentions = [ target_vertex
464 | ((names_defined, _, _, _), target_vertex) <- flat_info,
465 mentioned_name <- src_mentions,
466 mentioned_name `elemNameSet` names_defined
471 %************************************************************************
473 \subsubsection[dep-Sigs]{Signatures (and user-pragmas for values)}
475 %************************************************************************
477 @renameSigs@ checks for:
479 \item more than one sig for one thing;
480 \item signatures given for things not bound here;
481 \item with suitably flaggery, that all top-level things have type signatures.
484 At the moment we don't gather free-var info from the types in
485 signatures. We'd only need this if we wanted to report unused tyvars.
488 renameSigs :: Bool -- True => warn if (required) type signatures are missing.
489 -> NameSet -- Set of names bound in this group
490 -> (RdrName -> RnMS Name)
492 -> RnMS ([RenamedSig], FreeVars) -- List of Sig constructors
494 renameSigs sigs_required binders lookup_occ_nm sigs
495 = -- Rename the signatures
496 mapFvRn (renameSig lookup_occ_nm) sigs `thenRn` \ (sigs', fvs) ->
498 -- Check for (a) duplicate signatures
499 -- (b) signatures for things not in this group
500 -- (c) optionally, bindings with no signature
502 (goodies, dups) = removeDups cmp_sig (sigsForMe (not . isUnboundName) sigs')
503 not_this_group = sigsForMe (not . (`elemNameSet` binders)) goodies
504 type_sig_vars = [n | Sig n _ _ <- goodies]
505 un_sigd_binders | sigs_required = nameSetToList binders `minusList` type_sig_vars
508 mapRn_ dupSigDeclErr dups `thenRn_`
509 mapRn_ unknownSigErr not_this_group `thenRn_`
510 mapRn_ (addWarnRn.missingSigWarn) un_sigd_binders `thenRn_`
511 returnRn (sigs', fvs)
513 -- we need bindings of *some* sort for every name
515 -- We use lookupOccRn 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 :: (RdrName -> RnMS Name) -> Sig RdrName -> RnMS (Sig Name, FreeVars)
526 renameSig lookup_occ_nm (Sig v ty src_loc)
527 = pushSrcLocRn src_loc $
528 lookup_occ_nm v `thenRn` \ new_v ->
529 rnHsSigType (quotes (ppr v)) ty `thenRn` \ (new_ty,fvs) ->
530 returnRn (Sig new_v new_ty src_loc, fvs `addOneFV` new_v)
532 renameSig _ (SpecInstSig ty src_loc)
533 = pushSrcLocRn src_loc $
534 rnHsSigType (text "A SPECIALISE instance pragma") ty `thenRn` \ (new_ty, fvs) ->
535 returnRn (SpecInstSig new_ty src_loc, fvs)
537 renameSig lookup_occ_nm (SpecSig v ty src_loc)
538 = pushSrcLocRn src_loc $
539 lookup_occ_nm v `thenRn` \ new_v ->
540 rnHsSigType (quotes (ppr v)) ty `thenRn` \ (new_ty,fvs) ->
541 returnRn (SpecSig new_v new_ty src_loc, fvs `addOneFV` new_v)
543 renameSig lookup_occ_nm (FixSig (FixitySig v fix src_loc))
544 = pushSrcLocRn src_loc $
545 lookup_occ_nm v `thenRn` \ new_v ->
546 returnRn (FixSig (FixitySig new_v fix src_loc), unitFV new_v)
548 renameSig lookup_occ_nm (DeprecSig (Deprecation ie txt) src_loc)
549 = pushSrcLocRn src_loc $
550 renameIE lookup_occ_nm ie `thenRn` \ (new_ie, fvs) ->
551 returnRn (DeprecSig (Deprecation new_ie txt) src_loc, fvs)
553 renameSig lookup_occ_nm (InlineSig v p src_loc)
554 = pushSrcLocRn src_loc $
555 lookup_occ_nm v `thenRn` \ new_v ->
556 returnRn (InlineSig new_v p src_loc, unitFV new_v)
558 renameSig lookup_occ_nm (NoInlineSig v p src_loc)
559 = pushSrcLocRn src_loc $
560 lookup_occ_nm v `thenRn` \ new_v ->
561 returnRn (NoInlineSig new_v p src_loc, unitFV new_v)
565 renameIE :: (RdrName -> RnMS Name) -> IE RdrName -> RnMS (IE Name, FreeVars)
566 renameIE lookup_occ_nm (IEVar v)
567 = lookup_occ_nm v `thenRn` \ new_v ->
568 returnRn (IEVar new_v, unitFV new_v)
570 renameIE lookup_occ_nm (IEThingAbs v)
571 = lookup_occ_nm v `thenRn` \ new_v ->
572 returnRn (IEThingAbs new_v, unitFV new_v)
574 renameIE lookup_occ_nm (IEThingAll v)
575 = lookup_occ_nm v `thenRn` \ new_v ->
576 returnRn (IEThingAll new_v, unitFV new_v)
578 renameIE lookup_occ_nm (IEThingWith v vs)
579 = lookup_occ_nm v `thenRn` \ new_v ->
580 mapRn lookup_occ_nm vs `thenRn` \ new_vs ->
581 returnRn (IEThingWith new_v new_vs, plusFVs [ unitFV x | x <- new_v:new_vs ])
583 renameIE lookup_occ_nm (IEModuleContents m)
584 = returnRn (IEModuleContents m, emptyFVs)
587 Checking for distinct signatures; oh, so boring
591 cmp_sig :: RenamedSig -> RenamedSig -> Ordering
592 cmp_sig (Sig n1 _ _) (Sig n2 _ _) = n1 `compare` n2
593 cmp_sig (DeprecSig (Deprecation ie1 _) _)
594 (DeprecSig (Deprecation ie2 _) _) = cmp_ie ie1 ie2
595 cmp_sig (InlineSig n1 _ _) (InlineSig n2 _ _) = n1 `compare` n2
596 cmp_sig (NoInlineSig n1 _ _) (NoInlineSig n2 _ _) = n1 `compare` n2
597 cmp_sig (SpecInstSig ty1 _) (SpecInstSig ty2 _) = cmpHsType compare ty1 ty2
598 cmp_sig (SpecSig n1 ty1 _) (SpecSig n2 ty2 _)
599 = -- may have many specialisations for one value;
600 -- but not ones that are exactly the same...
601 thenCmp (n1 `compare` n2) (cmpHsType compare ty1 ty2)
603 cmp_sig other_1 other_2 -- Tags *must* be different
604 | (sig_tag other_1) _LT_ (sig_tag other_2) = LT
607 cmp_ie :: IE Name -> IE Name -> Ordering
608 cmp_ie (IEVar n1 ) (IEVar n2 ) = n1 `compare` n2
609 cmp_ie (IEThingAbs n1 ) (IEThingAbs n2 ) = n1 `compare` n2
610 cmp_ie (IEThingAll n1 ) (IEThingAll n2 ) = n1 `compare` n2
612 cmp_ie (IEThingWith n1 _) (IEThingWith n2 _) = n1 `compare` n2
613 cmp_ie (IEModuleContents _ ) (IEModuleContents _ ) = EQ
615 sig_tag (Sig n1 _ _) = (ILIT(1) :: FAST_INT)
616 sig_tag (SpecSig n1 _ _) = ILIT(2)
617 sig_tag (InlineSig n1 _ _) = ILIT(3)
618 sig_tag (NoInlineSig n1 _ _) = ILIT(4)
619 sig_tag (SpecInstSig _ _) = ILIT(5)
620 sig_tag (FixSig _) = ILIT(6)
621 sig_tag (DeprecSig _ _) = ILIT(7)
622 sig_tag _ = panic# "tag(RnBinds)"
625 %************************************************************************
627 \subsection{Error messages}
629 %************************************************************************
632 dupSigDeclErr (sig:sigs)
634 addErrRn (sep [ptext SLIT("Duplicate") <+> ptext what_it_is <> colon,
637 (what_it_is, loc) = sig_doc sig
641 addErrRn (sep [ptext SLIT("Misplaced"),
642 ptext what_it_is <> colon,
645 (what_it_is, loc) = sig_doc sig
647 sig_doc (Sig _ _ loc) = (SLIT("type signature"),loc)
648 sig_doc (ClassOpSig _ _ _ _ loc) = (SLIT("class-method type signature"), loc)
649 sig_doc (SpecSig _ _ loc) = (SLIT("SPECIALISE pragma"),loc)
650 sig_doc (InlineSig _ _ loc) = (SLIT("INLINE pragma"),loc)
651 sig_doc (NoInlineSig _ _ loc) = (SLIT("NOINLINE pragma"),loc)
652 sig_doc (SpecInstSig _ loc) = (SLIT("SPECIALISE instance pragma"),loc)
653 sig_doc (FixSig (FixitySig _ _ loc)) = (SLIT("fixity declaration"), loc)
654 sig_doc (DeprecSig _ loc) = (SLIT("DEPRECATED pragma"), loc)
657 = sep [ptext SLIT("definition but no type signature for"), quotes (ppr var)]
660 = hang (ptext SLIT("Can't handle multiple methods defined by one pattern binding"))