2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[RnExpr]{Renaming of expressions}
6 Basically dependency analysis.
8 Handles @Match@, @GRHSs@, @HsExpr@, and @Qualifier@ datatypes. In
9 general, all of these functions return a renamed thing, and a set of
14 rnLExpr, rnExpr, rnStmts
17 #include "HsVersions.h"
20 import {-# SOURCE #-} TcSplice( runQuasiQuoteExpr )
23 import RnSource ( rnSrcDecls, findSplice )
24 import RnBinds ( rnLocalBindsAndThen, rnValBindsLHS, rnValBindsRHS,
25 rnMatchGroup, makeMiniFixityEnv)
28 import TcEnv ( thRnBrack )
30 import RnTypes ( rnHsTypeFVs, rnSplice, checkTH,
31 mkOpFormRn, mkOpAppRn, mkNegAppRn, checkSectionPrec)
33 import DynFlags ( DynFlag(..) )
34 import BasicTypes ( FixityDirection(..) )
40 import LoadIface ( loadInterfaceForName )
43 import Util ( isSingleton )
44 import ListSetOps ( removeDups )
54 thenM :: Monad a => a b -> (b -> a c) -> a c
57 thenM_ :: Monad a => a b -> a c -> a c
61 %************************************************************************
63 \subsubsection{Expressions}
65 %************************************************************************
68 rnExprs :: [LHsExpr RdrName] -> RnM ([LHsExpr Name], FreeVars)
69 rnExprs ls = rnExprs' ls emptyUniqSet
71 rnExprs' [] acc = return ([], acc)
72 rnExprs' (expr:exprs) acc
73 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
75 -- Now we do a "seq" on the free vars because typically it's small
76 -- or empty, especially in very long lists of constants
78 acc' = acc `plusFV` fvExpr
80 acc' `seq` rnExprs' exprs acc' `thenM` \ (exprs', fvExprs) ->
81 return (expr':exprs', fvExprs)
84 Variables. We look up the variable and return the resulting name.
87 rnLExpr :: LHsExpr RdrName -> RnM (LHsExpr Name, FreeVars)
88 rnLExpr = wrapLocFstM rnExpr
90 rnExpr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
92 finishHsVar :: Name -> RnM (HsExpr Name, FreeVars)
93 -- Separated from rnExpr because it's also used
94 -- when renaming infix expressions
95 -- See Note [Adding the implicit parameter to 'assert']
97 = do { ignore_asserts <- doptM Opt_IgnoreAsserts
98 ; if ignore_asserts || not (name `hasKey` assertIdKey)
99 then return (HsVar name, unitFV name)
100 else do { e <- mkAssertErrorExpr
101 ; return (e, unitFV name) } }
104 = do name <- lookupOccRn v
108 = newIPNameRn v `thenM` \ name ->
109 return (HsIPVar name, emptyFVs)
111 rnExpr (HsLit lit@(HsString s))
113 opt_OverloadedStrings <- doptM Opt_OverloadedStrings
114 ; if opt_OverloadedStrings then
115 rnExpr (HsOverLit (mkHsIsString s placeHolderType))
116 else -- Same as below
118 return (HsLit lit, emptyFVs)
123 return (HsLit lit, emptyFVs)
125 rnExpr (HsOverLit lit)
126 = rnOverLit lit `thenM` \ (lit', fvs) ->
127 return (HsOverLit lit', fvs)
129 rnExpr (HsApp fun arg)
130 = rnLExpr fun `thenM` \ (fun',fvFun) ->
131 rnLExpr arg `thenM` \ (arg',fvArg) ->
132 return (HsApp fun' arg', fvFun `plusFV` fvArg)
134 rnExpr (OpApp e1 (L op_loc (HsVar op_rdr)) _ e2)
135 = do { (e1', fv_e1) <- rnLExpr e1
136 ; (e2', fv_e2) <- rnLExpr e2
137 ; op_name <- setSrcSpan op_loc (lookupOccRn op_rdr)
138 ; (op', fv_op) <- finishHsVar op_name
139 -- NB: op' is usually just a variable, but might be
140 -- an applicatoin (assert "Foo.hs:47")
142 -- When renaming code synthesised from "deriving" declarations
143 -- we used to avoid fixity stuff, but we can't easily tell any
144 -- more, so I've removed the test. Adding HsPars in TcGenDeriv
145 -- should prevent bad things happening.
146 ; fixity <- lookupFixityRn op_name
147 ; final_e <- mkOpAppRn e1' (L op_loc op') fixity e2'
148 ; return (final_e, fv_e1 `plusFV` fv_op `plusFV` fv_e2) }
151 = rnLExpr e `thenM` \ (e', fv_e) ->
152 lookupSyntaxName negateName `thenM` \ (neg_name, fv_neg) ->
153 mkNegAppRn e' neg_name `thenM` \ final_e ->
154 return (final_e, fv_e `plusFV` fv_neg)
156 ------------------------------------------
157 -- Template Haskell extensions
158 -- Don't ifdef-GHCI them because we want to fail gracefully
159 -- (not with an rnExpr crash) in a stage-1 compiler.
160 rnExpr e@(HsBracket br_body)
161 = checkTH e "bracket" `thenM_`
162 rnBracket br_body `thenM` \ (body', fvs_e) ->
163 return (HsBracket body', fvs_e)
165 rnExpr (HsSpliceE splice)
166 = rnSplice splice `thenM` \ (splice', fvs) ->
167 return (HsSpliceE splice', fvs)
170 rnExpr e@(HsQuasiQuoteE _) = pprPanic "Cant do quasiquotation without GHCi" (ppr e)
172 rnExpr (HsQuasiQuoteE qq)
173 = runQuasiQuoteExpr qq `thenM` \ (L _ expr') ->
177 ---------------------------------------------
179 -- See Note [Parsing sections] in Parser.y.pp
180 rnExpr (HsPar (L loc (section@(SectionL {}))))
181 = do { (section', fvs) <- rnSection section
182 ; return (HsPar (L loc section'), fvs) }
184 rnExpr (HsPar (L loc (section@(SectionR {}))))
185 = do { (section', fvs) <- rnSection section
186 ; return (HsPar (L loc section'), fvs) }
189 = do { (e', fvs_e) <- rnLExpr e
190 ; return (HsPar e', fvs_e) }
192 rnExpr expr@(SectionL {})
193 = do { addErr (sectionErr expr); rnSection expr }
194 rnExpr expr@(SectionR {})
195 = do { addErr (sectionErr expr); rnSection expr }
197 ---------------------------------------------
198 rnExpr (HsCoreAnn ann expr)
199 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
200 return (HsCoreAnn ann expr', fvs_expr)
202 rnExpr (HsSCC lbl expr)
203 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
204 return (HsSCC lbl expr', fvs_expr)
205 rnExpr (HsTickPragma info expr)
206 = rnLExpr expr `thenM` \ (expr', fvs_expr) ->
207 return (HsTickPragma info expr', fvs_expr)
209 rnExpr (HsLam matches)
210 = rnMatchGroup LambdaExpr matches `thenM` \ (matches', fvMatch) ->
211 return (HsLam matches', fvMatch)
213 rnExpr (HsCase expr matches)
214 = rnLExpr expr `thenM` \ (new_expr, e_fvs) ->
215 rnMatchGroup CaseAlt matches `thenM` \ (new_matches, ms_fvs) ->
216 return (HsCase new_expr new_matches, e_fvs `plusFV` ms_fvs)
218 rnExpr (HsLet binds expr)
219 = rnLocalBindsAndThen binds $ \ binds' ->
220 rnLExpr expr `thenM` \ (expr',fvExpr) ->
221 return (HsLet binds' expr', fvExpr)
223 rnExpr (HsDo do_or_lc stmts body _)
224 = do { ((stmts', body'), fvs) <- rnStmts do_or_lc stmts $
226 ; return (HsDo do_or_lc stmts' body' placeHolderType, fvs) }
228 rnExpr (ExplicitList _ exps)
229 = rnExprs exps `thenM` \ (exps', fvs) ->
230 return (ExplicitList placeHolderType exps', fvs)
232 rnExpr (ExplicitPArr _ exps)
233 = rnExprs exps `thenM` \ (exps', fvs) ->
234 return (ExplicitPArr placeHolderType exps', fvs)
236 rnExpr (ExplicitTuple tup_args boxity)
237 = do { checkTupleSection tup_args
238 ; checkTupSize (length tup_args)
239 ; (tup_args', fvs) <- mapAndUnzipM rnTupArg tup_args
240 ; return (ExplicitTuple tup_args' boxity, plusFVs fvs) }
242 rnTupArg (Present e) = do { (e',fvs) <- rnLExpr e; return (Present e', fvs) }
243 rnTupArg (Missing _) = return (Missing placeHolderType, emptyFVs)
245 rnExpr (RecordCon con_id _ rbinds)
246 = do { conname <- lookupLocatedOccRn con_id
247 ; (rbinds', fvRbinds) <- rnHsRecBinds (HsRecFieldCon (unLoc conname)) rbinds
248 ; return (RecordCon conname noPostTcExpr rbinds',
249 fvRbinds `addOneFV` unLoc conname) }
251 rnExpr (RecordUpd expr rbinds _ _ _)
252 = do { (expr', fvExpr) <- rnLExpr expr
253 ; (rbinds', fvRbinds) <- rnHsRecBinds HsRecFieldUpd rbinds
254 ; return (RecordUpd expr' rbinds' [] [] [],
255 fvExpr `plusFV` fvRbinds) }
257 rnExpr (ExprWithTySig expr pty)
258 = do { (pty', fvTy) <- rnHsTypeFVs doc pty
259 ; (expr', fvExpr) <- bindSigTyVarsFV (hsExplicitTvs pty') $
261 ; return (ExprWithTySig expr' pty', fvExpr `plusFV` fvTy) }
263 doc = text "In an expression type signature"
265 rnExpr (HsIf p b1 b2)
266 = rnLExpr p `thenM` \ (p', fvP) ->
267 rnLExpr b1 `thenM` \ (b1', fvB1) ->
268 rnLExpr b2 `thenM` \ (b2', fvB2) ->
269 return (HsIf p' b1' b2', plusFVs [fvP, fvB1, fvB2])
272 = rnHsTypeFVs doc a `thenM` \ (t, fvT) ->
273 return (HsType t, fvT)
275 doc = text "In a type argument"
277 rnExpr (ArithSeq _ seq)
278 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
279 return (ArithSeq noPostTcExpr new_seq, fvs)
281 rnExpr (PArrSeq _ seq)
282 = rnArithSeq seq `thenM` \ (new_seq, fvs) ->
283 return (PArrSeq noPostTcExpr new_seq, fvs)
286 These three are pattern syntax appearing in expressions.
287 Since all the symbols are reservedops we can simply reject them.
288 We return a (bogus) EWildPat in each case.
291 rnExpr e@EWildPat = patSynErr e
292 rnExpr e@(EAsPat {}) = patSynErr e
293 rnExpr e@(EViewPat {}) = patSynErr e
294 rnExpr e@(ELazyPat {}) = patSynErr e
297 %************************************************************************
301 %************************************************************************
304 rnExpr (HsProc pat body)
306 rnPat ProcExpr pat $ \ pat' ->
307 rnCmdTop body `thenM` \ (body',fvBody) ->
308 return (HsProc pat' body', fvBody)
310 rnExpr (HsArrApp arrow arg _ ho rtl)
311 = select_arrow_scope (rnLExpr arrow) `thenM` \ (arrow',fvArrow) ->
312 rnLExpr arg `thenM` \ (arg',fvArg) ->
313 return (HsArrApp arrow' arg' placeHolderType ho rtl,
314 fvArrow `plusFV` fvArg)
316 select_arrow_scope tc = case ho of
317 HsHigherOrderApp -> tc
318 HsFirstOrderApp -> escapeArrowScope tc
321 rnExpr (HsArrForm op (Just _) [arg1, arg2])
322 = escapeArrowScope (rnLExpr op)
323 `thenM` \ (op'@(L _ (HsVar op_name)),fv_op) ->
324 rnCmdTop arg1 `thenM` \ (arg1',fv_arg1) ->
325 rnCmdTop arg2 `thenM` \ (arg2',fv_arg2) ->
329 lookupFixityRn op_name `thenM` \ fixity ->
330 mkOpFormRn arg1' op' fixity arg2' `thenM` \ final_e ->
333 fv_arg1 `plusFV` fv_op `plusFV` fv_arg2)
335 rnExpr (HsArrForm op fixity cmds)
336 = escapeArrowScope (rnLExpr op) `thenM` \ (op',fvOp) ->
337 rnCmdArgs cmds `thenM` \ (cmds',fvCmds) ->
338 return (HsArrForm op' fixity cmds', fvOp `plusFV` fvCmds)
340 rnExpr other = pprPanic "rnExpr: unexpected expression" (ppr other)
343 ----------------------
344 -- See Note [Parsing sections] in Parser.y.pp
345 rnSection :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
346 rnSection section@(SectionR op expr)
347 = do { (op', fvs_op) <- rnLExpr op
348 ; (expr', fvs_expr) <- rnLExpr expr
349 ; checkSectionPrec InfixR section op' expr'
350 ; return (SectionR op' expr', fvs_op `plusFV` fvs_expr) }
352 rnSection section@(SectionL expr op)
353 = do { (expr', fvs_expr) <- rnLExpr expr
354 ; (op', fvs_op) <- rnLExpr op
355 ; checkSectionPrec InfixL section op' expr'
356 ; return (SectionL expr' op', fvs_op `plusFV` fvs_expr) }
358 rnSection other = pprPanic "rnSection" (ppr other)
361 %************************************************************************
365 %************************************************************************
368 rnHsRecBinds :: HsRecFieldContext -> HsRecordBinds RdrName
369 -> RnM (HsRecordBinds Name, FreeVars)
370 rnHsRecBinds ctxt rec_binds@(HsRecFields { rec_dotdot = dd })
371 = do { (flds, fvs) <- rnHsRecFields1 ctxt HsVar rec_binds
372 ; (flds', fvss) <- mapAndUnzipM rn_field flds
373 ; return (HsRecFields { rec_flds = flds', rec_dotdot = dd },
374 fvs `plusFV` plusFVs fvss) }
376 rn_field fld = do { (arg', fvs) <- rnLExpr (hsRecFieldArg fld)
377 ; return (fld { hsRecFieldArg = arg' }, fvs) }
381 %************************************************************************
385 %************************************************************************
388 rnCmdArgs :: [LHsCmdTop RdrName] -> RnM ([LHsCmdTop Name], FreeVars)
389 rnCmdArgs [] = return ([], emptyFVs)
391 = rnCmdTop arg `thenM` \ (arg',fvArg) ->
392 rnCmdArgs args `thenM` \ (args',fvArgs) ->
393 return (arg':args', fvArg `plusFV` fvArgs)
395 rnCmdTop :: LHsCmdTop RdrName -> RnM (LHsCmdTop Name, FreeVars)
396 rnCmdTop = wrapLocFstM rnCmdTop'
398 rnCmdTop' (HsCmdTop cmd _ _ _)
399 = rnLExpr (convertOpFormsLCmd cmd) `thenM` \ (cmd', fvCmd) ->
401 cmd_names = [arrAName, composeAName, firstAName] ++
402 nameSetToList (methodNamesCmd (unLoc cmd'))
404 -- Generate the rebindable syntax for the monad
405 lookupSyntaxTable cmd_names `thenM` \ (cmd_names', cmd_fvs) ->
407 return (HsCmdTop cmd' [] placeHolderType cmd_names',
408 fvCmd `plusFV` cmd_fvs)
410 ---------------------------------------------------
411 -- convert OpApp's in a command context to HsArrForm's
413 convertOpFormsLCmd :: LHsCmd id -> LHsCmd id
414 convertOpFormsLCmd = fmap convertOpFormsCmd
416 convertOpFormsCmd :: HsCmd id -> HsCmd id
418 convertOpFormsCmd (HsApp c e) = HsApp (convertOpFormsLCmd c) e
419 convertOpFormsCmd (HsLam match) = HsLam (convertOpFormsMatch match)
420 convertOpFormsCmd (OpApp c1 op fixity c2)
422 arg1 = L (getLoc c1) $ HsCmdTop (convertOpFormsLCmd c1) [] placeHolderType []
423 arg2 = L (getLoc c2) $ HsCmdTop (convertOpFormsLCmd c2) [] placeHolderType []
425 HsArrForm op (Just fixity) [arg1, arg2]
427 convertOpFormsCmd (HsPar c) = HsPar (convertOpFormsLCmd c)
429 convertOpFormsCmd (HsCase exp matches)
430 = HsCase exp (convertOpFormsMatch matches)
432 convertOpFormsCmd (HsIf exp c1 c2)
433 = HsIf exp (convertOpFormsLCmd c1) (convertOpFormsLCmd c2)
435 convertOpFormsCmd (HsLet binds cmd)
436 = HsLet binds (convertOpFormsLCmd cmd)
438 convertOpFormsCmd (HsDo ctxt stmts body ty)
439 = HsDo ctxt (map (fmap convertOpFormsStmt) stmts)
440 (convertOpFormsLCmd body) ty
442 -- Anything else is unchanged. This includes HsArrForm (already done),
443 -- things with no sub-commands, and illegal commands (which will be
444 -- caught by the type checker)
445 convertOpFormsCmd c = c
447 convertOpFormsStmt :: StmtLR id id -> StmtLR id id
448 convertOpFormsStmt (BindStmt pat cmd _ _)
449 = BindStmt pat (convertOpFormsLCmd cmd) noSyntaxExpr noSyntaxExpr
450 convertOpFormsStmt (ExprStmt cmd _ _)
451 = ExprStmt (convertOpFormsLCmd cmd) noSyntaxExpr placeHolderType
452 convertOpFormsStmt stmt@(RecStmt { recS_stmts = stmts })
453 = stmt { recS_stmts = map (fmap convertOpFormsStmt) stmts }
454 convertOpFormsStmt stmt = stmt
456 convertOpFormsMatch :: MatchGroup id -> MatchGroup id
457 convertOpFormsMatch (MatchGroup ms ty)
458 = MatchGroup (map (fmap convert) ms) ty
459 where convert (Match pat mty grhss)
460 = Match pat mty (convertOpFormsGRHSs grhss)
462 convertOpFormsGRHSs :: GRHSs id -> GRHSs id
463 convertOpFormsGRHSs (GRHSs grhss binds)
464 = GRHSs (map convertOpFormsGRHS grhss) binds
466 convertOpFormsGRHS :: Located (GRHS id) -> Located (GRHS id)
467 convertOpFormsGRHS = fmap convert
469 convert (GRHS stmts cmd) = GRHS stmts (convertOpFormsLCmd cmd)
471 ---------------------------------------------------
472 type CmdNeeds = FreeVars -- Only inhabitants are
473 -- appAName, choiceAName, loopAName
475 -- find what methods the Cmd needs (loop, choice, apply)
476 methodNamesLCmd :: LHsCmd Name -> CmdNeeds
477 methodNamesLCmd = methodNamesCmd . unLoc
479 methodNamesCmd :: HsCmd Name -> CmdNeeds
481 methodNamesCmd (HsArrApp _arrow _arg _ HsFirstOrderApp _rtl)
483 methodNamesCmd (HsArrApp _arrow _arg _ HsHigherOrderApp _rtl)
485 methodNamesCmd (HsArrForm {}) = emptyFVs
487 methodNamesCmd (HsPar c) = methodNamesLCmd c
489 methodNamesCmd (HsIf _ c1 c2)
490 = methodNamesLCmd c1 `plusFV` methodNamesLCmd c2 `addOneFV` choiceAName
492 methodNamesCmd (HsLet _ c) = methodNamesLCmd c
494 methodNamesCmd (HsDo _ stmts body _)
495 = methodNamesStmts stmts `plusFV` methodNamesLCmd body
497 methodNamesCmd (HsApp c _) = methodNamesLCmd c
499 methodNamesCmd (HsLam match) = methodNamesMatch match
501 methodNamesCmd (HsCase _ matches)
502 = methodNamesMatch matches `addOneFV` choiceAName
504 methodNamesCmd _ = emptyFVs
505 -- Other forms can't occur in commands, but it's not convenient
506 -- to error here so we just do what's convenient.
507 -- The type checker will complain later
509 ---------------------------------------------------
510 methodNamesMatch :: MatchGroup Name -> FreeVars
511 methodNamesMatch (MatchGroup ms _)
512 = plusFVs (map do_one ms)
514 do_one (L _ (Match _ _ grhss)) = methodNamesGRHSs grhss
516 -------------------------------------------------
518 methodNamesGRHSs :: GRHSs Name -> FreeVars
519 methodNamesGRHSs (GRHSs grhss _) = plusFVs (map methodNamesGRHS grhss)
521 -------------------------------------------------
523 methodNamesGRHS :: Located (GRHS Name) -> CmdNeeds
524 methodNamesGRHS (L _ (GRHS _ rhs)) = methodNamesLCmd rhs
526 ---------------------------------------------------
527 methodNamesStmts :: [Located (StmtLR Name Name)] -> FreeVars
528 methodNamesStmts stmts = plusFVs (map methodNamesLStmt stmts)
530 ---------------------------------------------------
531 methodNamesLStmt :: Located (StmtLR Name Name) -> FreeVars
532 methodNamesLStmt = methodNamesStmt . unLoc
534 methodNamesStmt :: StmtLR Name Name -> FreeVars
535 methodNamesStmt (ExprStmt cmd _ _) = methodNamesLCmd cmd
536 methodNamesStmt (BindStmt _ cmd _ _) = methodNamesLCmd cmd
537 methodNamesStmt (RecStmt { recS_stmts = stmts }) = methodNamesStmts stmts `addOneFV` loopAName
538 methodNamesStmt (LetStmt _) = emptyFVs
539 methodNamesStmt (ParStmt _) = emptyFVs
540 methodNamesStmt (TransformStmt {}) = emptyFVs
541 methodNamesStmt (GroupStmt {}) = emptyFVs
542 -- ParStmt, TransformStmt and GroupStmt can't occur in commands, but it's not convenient to error
543 -- here so we just do what's convenient
547 %************************************************************************
551 %************************************************************************
554 rnArithSeq :: ArithSeqInfo RdrName -> RnM (ArithSeqInfo Name, FreeVars)
555 rnArithSeq (From expr)
556 = rnLExpr expr `thenM` \ (expr', fvExpr) ->
557 return (From expr', fvExpr)
559 rnArithSeq (FromThen expr1 expr2)
560 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
561 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
562 return (FromThen expr1' expr2', fvExpr1 `plusFV` fvExpr2)
564 rnArithSeq (FromTo expr1 expr2)
565 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
566 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
567 return (FromTo expr1' expr2', fvExpr1 `plusFV` fvExpr2)
569 rnArithSeq (FromThenTo expr1 expr2 expr3)
570 = rnLExpr expr1 `thenM` \ (expr1', fvExpr1) ->
571 rnLExpr expr2 `thenM` \ (expr2', fvExpr2) ->
572 rnLExpr expr3 `thenM` \ (expr3', fvExpr3) ->
573 return (FromThenTo expr1' expr2' expr3',
574 plusFVs [fvExpr1, fvExpr2, fvExpr3])
577 %************************************************************************
579 Template Haskell brackets
581 %************************************************************************
584 rnBracket :: HsBracket RdrName -> RnM (HsBracket Name, FreeVars)
585 rnBracket (VarBr n) = do { name <- lookupOccRn n
586 ; this_mod <- getModule
587 ; unless (nameIsLocalOrFrom this_mod name) $ -- Reason: deprecation checking asumes the
588 do { _ <- loadInterfaceForName msg name -- home interface is loaded, and this is the
589 ; return () } -- only way that is going to happen
590 ; return (VarBr name, unitFV name) }
592 msg = ptext (sLit "Need interface for Template Haskell quoted Name")
594 rnBracket (ExpBr e) = do { (e', fvs) <- rnLExpr e
595 ; return (ExpBr e', fvs) }
597 rnBracket (PatBr p) = rnPat ThPatQuote p $ \ p' -> return (PatBr p', emptyFVs)
599 rnBracket (TypBr t) = do { (t', fvs) <- rnHsTypeFVs doc t
600 ; return (TypBr t', fvs) }
602 doc = ptext (sLit "In a Template-Haskell quoted type")
604 rnBracket (DecBrL decls)
605 = do { (group, mb_splice) <- findSplice decls
608 Just (SpliceDecl (L loc _) _, _)
610 addErr (ptext (sLit "Declaration splices are not permitted inside declaration brackets"))
611 -- Why not? See Section 7.3 of the TH paper.
613 ; gbl_env <- getGblEnv
614 ; let new_gbl_env = gbl_env { tcg_dus = emptyDUs }
615 -- The emptyDUs is so that we just collect uses for this
616 -- group alone in the call to rnSrcDecls below
617 ; (tcg_env, group') <- setGblEnv new_gbl_env $
621 -- Discard the tcg_env; it contains only extra info about fixity
622 ; traceRn (text "rnBracket dec" <+> (ppr (tcg_dus tcg_env) $$ ppr (duUses (tcg_dus tcg_env))))
623 ; return (DecBrG group', duUses (tcg_dus tcg_env)) }
625 rnBracket (DecBrG _) = panic "rnBracket: unexpected DecBrG"
628 %************************************************************************
630 \subsubsection{@Stmt@s: in @do@ expressions}
632 %************************************************************************
635 rnStmts :: HsStmtContext Name -> [LStmt RdrName]
636 -> RnM (thing, FreeVars)
637 -> RnM (([LStmt Name], thing), FreeVars)
638 -- Variables bound by the Stmts, and mentioned in thing_inside,
639 -- do not appear in the result FreeVars
641 rnStmts (MDoExpr _) stmts thing_inside = rnMDoStmts stmts thing_inside
642 rnStmts ctxt stmts thing_inside = rnNormalStmts ctxt stmts (\ _ -> thing_inside)
644 rnNormalStmts :: HsStmtContext Name -> [LStmt RdrName]
645 -> ([Name] -> RnM (thing, FreeVars))
646 -> RnM (([LStmt Name], thing), FreeVars)
647 -- Variables bound by the Stmts, and mentioned in thing_inside,
648 -- do not appear in the result FreeVars
650 -- Renaming a single RecStmt can give a sequence of smaller Stmts
652 rnNormalStmts _ [] thing_inside
653 = do { (res, fvs) <- thing_inside []
654 ; return (([], res), fvs) }
656 rnNormalStmts ctxt (stmt@(L loc _) : stmts) thing_inside
657 = do { ((stmts1, (stmts2, thing)), fvs)
659 rnStmt ctxt stmt $ \ bndrs1 ->
660 rnNormalStmts ctxt stmts $ \ bndrs2 ->
661 thing_inside (bndrs1 ++ bndrs2)
662 ; return (((stmts1 ++ stmts2), thing), fvs) }
665 rnStmt :: HsStmtContext Name -> LStmt RdrName
666 -> ([Name] -> RnM (thing, FreeVars))
667 -> RnM (([LStmt Name], thing), FreeVars)
668 -- Variables bound by the Stmt, and mentioned in thing_inside,
669 -- do not appear in the result FreeVars
671 rnStmt _ (L loc (ExprStmt expr _ _)) thing_inside
672 = do { (expr', fv_expr) <- rnLExpr expr
673 ; (then_op, fvs1) <- lookupSyntaxName thenMName
674 ; (thing, fvs2) <- thing_inside []
675 ; return (([L loc (ExprStmt expr' then_op placeHolderType)], thing),
676 fv_expr `plusFV` fvs1 `plusFV` fvs2) }
678 rnStmt ctxt (L loc (BindStmt pat expr _ _)) thing_inside
679 = do { (expr', fv_expr) <- rnLExpr expr
680 -- The binders do not scope over the expression
681 ; (bind_op, fvs1) <- lookupSyntaxName bindMName
682 ; (fail_op, fvs2) <- lookupSyntaxName failMName
683 ; rnPat (StmtCtxt ctxt) pat $ \ pat' -> do
684 { (thing, fvs3) <- thing_inside (collectPatBinders pat')
685 ; return (([L loc (BindStmt pat' expr' bind_op fail_op)], thing),
686 fv_expr `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) }}
687 -- fv_expr shouldn't really be filtered by the rnPatsAndThen
688 -- but it does not matter because the names are unique
690 rnStmt ctxt (L loc (LetStmt binds)) thing_inside
691 = do { checkLetStmt ctxt binds
692 ; rnLocalBindsAndThen binds $ \binds' -> do
693 { (thing, fvs) <- thing_inside (collectLocalBinders binds')
694 ; return (([L loc (LetStmt binds')], thing), fvs) } }
696 rnStmt ctxt (L _ (RecStmt { recS_stmts = rec_stmts })) thing_inside
697 = do { checkRecStmt ctxt
699 -- Step1: Bring all the binders of the mdo into scope
700 -- (Remember that this also removes the binders from the
701 -- finally-returned free-vars.)
702 -- And rename each individual stmt, making a
703 -- singleton segment. At this stage the FwdRefs field
704 -- isn't finished: it's empty for all except a BindStmt
705 -- for which it's the fwd refs within the bind itself
706 -- (This set may not be empty, because we're in a recursive
708 ; rn_rec_stmts_and_then rec_stmts $ \ segs -> do
710 { let bndrs = nameSetToList $ foldr (unionNameSets . (\(ds,_,_,_) -> ds))
712 ; (thing, fvs_later) <- thing_inside bndrs
713 ; (return_op, fvs1) <- lookupSyntaxName returnMName
714 ; (mfix_op, fvs2) <- lookupSyntaxName mfixName
715 ; (bind_op, fvs3) <- lookupSyntaxName bindMName
717 -- Step 2: Fill in the fwd refs.
718 -- The segments are all singletons, but their fwd-ref
719 -- field mentions all the things used by the segment
720 -- that are bound after their use
721 segs_w_fwd_refs = addFwdRefs segs
723 -- Step 3: Group together the segments to make bigger segments
724 -- Invariant: in the result, no segment uses a variable
725 -- bound in a later segment
726 grouped_segs = glomSegments segs_w_fwd_refs
728 -- Step 4: Turn the segments into Stmts
729 -- Use RecStmt when and only when there are fwd refs
730 -- Also gather up the uses from the end towards the
731 -- start, so we can tell the RecStmt which things are
732 -- used 'after' the RecStmt
733 empty_rec_stmt = emptyRecStmt { recS_ret_fn = return_op
734 , recS_mfix_fn = mfix_op
735 , recS_bind_fn = bind_op }
736 (rec_stmts', fvs) = segsToStmts empty_rec_stmt grouped_segs fvs_later
738 ; return ((rec_stmts', thing), fvs `plusFV` fvs1 `plusFV` fvs2 `plusFV` fvs3) } }
740 rnStmt ctxt (L loc (ParStmt segs)) thing_inside
741 = do { checkParStmt ctxt
742 ; ((segs', thing), fvs) <- rnParallelStmts (ParStmtCtxt ctxt) segs thing_inside
743 ; return (([L loc (ParStmt segs')], thing), fvs) }
745 rnStmt ctxt (L loc (TransformStmt stmts _ using by)) thing_inside
746 = do { checkTransformStmt ctxt
748 ; (using', fvs1) <- rnLExpr using
750 ; ((stmts', (by', used_bndrs, thing)), fvs2)
751 <- rnNormalStmts (TransformStmtCtxt ctxt) stmts $ \ bndrs ->
752 do { (by', fvs_by) <- case by of
753 Nothing -> return (Nothing, emptyFVs)
754 Just e -> do { (e', fvs) <- rnLExpr e; return (Just e', fvs) }
755 ; (thing, fvs_thing) <- thing_inside bndrs
756 ; let fvs = fvs_by `plusFV` fvs_thing
757 used_bndrs = filter (`elemNameSet` fvs_thing) bndrs
758 ; return ((by', used_bndrs, thing), fvs) }
760 ; return (([L loc (TransformStmt stmts' used_bndrs using' by')], thing),
761 fvs1 `plusFV` fvs2) }
763 rnStmt ctxt (L loc (GroupStmt stmts _ by using)) thing_inside
764 = do { checkTransformStmt ctxt
766 -- Rename the 'using' expression in the context before the transform is begun
767 ; (using', fvs1) <- case using of
768 Left e -> do { (e', fvs) <- rnLExpr e; return (Left e', fvs) }
769 Right _ -> do { (e', fvs) <- lookupSyntaxName groupWithName
770 ; return (Right e', fvs) }
772 -- Rename the stmts and the 'by' expression
773 -- Keep track of the variables mentioned in the 'by' expression
774 ; ((stmts', (by', used_bndrs, thing)), fvs2)
775 <- rnNormalStmts (TransformStmtCtxt ctxt) stmts $ \ bndrs ->
776 do { (by', fvs_by) <- mapMaybeFvRn rnLExpr by
777 ; (thing, fvs_thing) <- thing_inside bndrs
778 ; let fvs = fvs_by `plusFV` fvs_thing
779 used_bndrs = filter (`elemNameSet` fvs) bndrs
780 ; return ((by', used_bndrs, thing), fvs) }
782 ; let all_fvs = fvs1 `plusFV` fvs2
783 bndr_map = used_bndrs `zip` used_bndrs
784 -- See Note [GroupStmt binder map] in HsExpr
786 ; traceRn (text "rnStmt: implicitly rebound these used binders:" <+> ppr bndr_map)
787 ; return (([L loc (GroupStmt stmts' bndr_map by' using')], thing), all_fvs) }
790 type ParSeg id = ([LStmt id], [id]) -- The Names are bound by the Stmts
792 rnParallelStmts :: forall thing. HsStmtContext Name
794 -> ([Name] -> RnM (thing, FreeVars))
795 -> RnM (([ParSeg Name], thing), FreeVars)
796 -- Note [Renaming parallel Stmts]
797 rnParallelStmts ctxt segs thing_inside
798 = do { orig_lcl_env <- getLocalRdrEnv
799 ; rn_segs orig_lcl_env [] segs }
801 rn_segs :: LocalRdrEnv
802 -> [Name] -> [ParSeg RdrName]
803 -> RnM (([ParSeg Name], thing), FreeVars)
804 rn_segs _ bndrs_so_far []
805 = do { let (bndrs', dups) = removeDups cmpByOcc bndrs_so_far
807 ; (thing, fvs) <- bindLocalNames bndrs' (thing_inside bndrs')
808 ; return (([], thing), fvs) }
810 rn_segs env bndrs_so_far ((stmts,_) : segs)
811 = do { ((stmts', (used_bndrs, segs', thing)), fvs)
812 <- rnNormalStmts ctxt stmts $ \ bndrs ->
813 setLocalRdrEnv env $ do
814 { ((segs', thing), fvs) <- rn_segs env (bndrs ++ bndrs_so_far) segs
815 ; let used_bndrs = filter (`elemNameSet` fvs) bndrs
816 ; return ((used_bndrs, segs', thing), fvs) }
818 ; let seg' = (stmts', used_bndrs)
819 ; return ((seg':segs', thing), fvs) }
821 cmpByOcc n1 n2 = nameOccName n1 `compare` nameOccName n2
822 dupErr vs = addErr (ptext (sLit "Duplicate binding in parallel list comprehension for:")
823 <+> quotes (ppr (head vs)))
826 Note [Renaming parallel Stmts]
827 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
828 Renaming parallel statements is painful. Given, say
829 [ a+c | a <- as, bs <- bss
832 (a) In order to report "Defined by not used" about 'bs', we must rename
833 each group of Stmts with a thing_inside whose FreeVars include at least {a,c}
835 (b) We want to report that 'a' is illegally bound in both branches
837 (c) The 'bs' in the second group must obviously not be captured by
838 the binding in the first group
840 To satisfy (a) we nest the segements.
841 To satisfy (b) we check for duplicates just before thing_inside.
842 To satisfy (c) we reset the LocalRdrEnv each time.
844 %************************************************************************
846 \subsubsection{mdo expressions}
848 %************************************************************************
851 type FwdRefs = NameSet
852 type Segment stmts = (Defs,
853 Uses, -- May include defs
854 FwdRefs, -- A subset of uses that are
855 -- (a) used before they are bound in this segment, or
856 -- (b) used here, and bound in subsequent segments
857 stmts) -- Either Stmt or [Stmt]
860 ----------------------------------------------------
862 rnMDoStmts :: [LStmt RdrName]
863 -> RnM (thing, FreeVars)
864 -> RnM (([LStmt Name], thing), FreeVars)
865 rnMDoStmts stmts thing_inside
866 = rn_rec_stmts_and_then stmts $ \ segs -> do
867 { (thing, fvs_later) <- thing_inside
868 ; let segs_w_fwd_refs = addFwdRefs segs
869 grouped_segs = glomSegments segs_w_fwd_refs
870 (stmts', fvs) = segsToStmts emptyRecStmt grouped_segs fvs_later
871 ; return ((stmts', thing), fvs) }
873 ---------------------------------------------
875 -- wrapper that does both the left- and right-hand sides
876 rn_rec_stmts_and_then :: [LStmt RdrName]
877 -- assumes that the FreeVars returned includes
878 -- the FreeVars of the Segments
879 -> ([Segment (LStmt Name)] -> RnM (a, FreeVars))
881 rn_rec_stmts_and_then s cont
882 = do { -- (A) Make the mini fixity env for all of the stmts
883 fix_env <- makeMiniFixityEnv (collectRecStmtsFixities s)
886 ; new_lhs_and_fv <- rn_rec_stmts_lhs fix_env s
888 -- ...bring them and their fixities into scope
889 ; let bound_names = collectLStmtsBinders (map fst new_lhs_and_fv)
890 ; bindLocalNamesFV bound_names $
891 addLocalFixities fix_env bound_names $ do
893 -- (C) do the right-hand-sides and thing-inside
894 { segs <- rn_rec_stmts bound_names new_lhs_and_fv
895 ; (res, fvs) <- cont segs
896 ; warnUnusedLocalBinds bound_names fvs
897 ; return (res, fvs) }}
899 -- get all the fixity decls in any Let stmt
900 collectRecStmtsFixities :: [LStmtLR RdrName RdrName] -> [LFixitySig RdrName]
901 collectRecStmtsFixities l =
902 foldr (\ s -> \acc -> case s of
903 (L _ (LetStmt (HsValBinds (ValBindsIn _ sigs)))) ->
904 foldr (\ sig -> \ acc -> case sig of
905 (L loc (FixSig s)) -> (L loc s) : acc
911 rn_rec_stmt_lhs :: MiniFixityEnv
913 -- rename LHS, and return its FVs
914 -- Warning: we will only need the FreeVars below in the case of a BindStmt,
915 -- so we don't bother to compute it accurately in the other cases
916 -> RnM [(LStmtLR Name RdrName, FreeVars)]
918 rn_rec_stmt_lhs _ (L loc (ExprStmt expr a b)) = return [(L loc (ExprStmt expr a b),
919 -- this is actually correct
922 rn_rec_stmt_lhs fix_env (L loc (BindStmt pat expr a b))
924 -- should the ctxt be MDo instead?
925 (pat', fv_pat) <- rnBindPat (localRecNameMaker fix_env) pat
926 return [(L loc (BindStmt pat' expr a b),
929 rn_rec_stmt_lhs _ (L _ (LetStmt binds@(HsIPBinds _)))
930 = failWith (badIpBinds (ptext (sLit "an mdo expression")) binds)
932 rn_rec_stmt_lhs fix_env (L loc (LetStmt (HsValBinds binds)))
933 = do (_bound_names, binds') <- rnValBindsLHS fix_env binds
934 return [(L loc (LetStmt (HsValBinds binds')),
935 -- Warning: this is bogus; see function invariant
939 -- XXX Do we need to do something with the return and mfix names?
940 rn_rec_stmt_lhs fix_env (L _ (RecStmt { recS_stmts = stmts })) -- Flatten Rec inside Rec
941 = rn_rec_stmts_lhs fix_env stmts
943 rn_rec_stmt_lhs _ stmt@(L _ (ParStmt _)) -- Syntactically illegal in mdo
944 = pprPanic "rn_rec_stmt" (ppr stmt)
946 rn_rec_stmt_lhs _ stmt@(L _ (TransformStmt {})) -- Syntactically illegal in mdo
947 = pprPanic "rn_rec_stmt" (ppr stmt)
949 rn_rec_stmt_lhs _ stmt@(L _ (GroupStmt {})) -- Syntactically illegal in mdo
950 = pprPanic "rn_rec_stmt" (ppr stmt)
952 rn_rec_stmt_lhs _ (L _ (LetStmt EmptyLocalBinds))
953 = panic "rn_rec_stmt LetStmt EmptyLocalBinds"
955 rn_rec_stmts_lhs :: MiniFixityEnv
957 -> RnM [(LStmtLR Name RdrName, FreeVars)]
958 rn_rec_stmts_lhs fix_env stmts
959 = do { ls <- concatMapM (rn_rec_stmt_lhs fix_env) stmts
960 ; let boundNames = collectLStmtsBinders (map fst ls)
961 -- First do error checking: we need to check for dups here because we
962 -- don't bind all of the variables from the Stmt at once
963 -- with bindLocatedLocals.
964 ; checkDupNames boundNames
970 rn_rec_stmt :: [Name] -> LStmtLR Name RdrName -> FreeVars -> RnM [Segment (LStmt Name)]
971 -- Rename a Stmt that is inside a RecStmt (or mdo)
972 -- Assumes all binders are already in scope
973 -- Turns each stmt into a singleton Stmt
974 rn_rec_stmt _ (L loc (ExprStmt expr _ _)) _
975 = rnLExpr expr `thenM` \ (expr', fvs) ->
976 lookupSyntaxName thenMName `thenM` \ (then_op, fvs1) ->
977 return [(emptyNameSet, fvs `plusFV` fvs1, emptyNameSet,
978 L loc (ExprStmt expr' then_op placeHolderType))]
980 rn_rec_stmt _ (L loc (BindStmt pat' expr _ _)) fv_pat
981 = rnLExpr expr `thenM` \ (expr', fv_expr) ->
982 lookupSyntaxName bindMName `thenM` \ (bind_op, fvs1) ->
983 lookupSyntaxName failMName `thenM` \ (fail_op, fvs2) ->
985 bndrs = mkNameSet (collectPatBinders pat')
986 fvs = fv_expr `plusFV` fv_pat `plusFV` fvs1 `plusFV` fvs2
988 return [(bndrs, fvs, bndrs `intersectNameSet` fvs,
989 L loc (BindStmt pat' expr' bind_op fail_op))]
991 rn_rec_stmt _ (L _ (LetStmt binds@(HsIPBinds _))) _
992 = failWith (badIpBinds (ptext (sLit "an mdo expression")) binds)
994 rn_rec_stmt all_bndrs (L loc (LetStmt (HsValBinds binds'))) _ = do
995 (binds', du_binds) <-
996 -- fixities and unused are handled above in rn_rec_stmts_and_then
997 rnValBindsRHS (mkNameSet all_bndrs) binds'
998 return [(duDefs du_binds, allUses du_binds,
999 emptyNameSet, L loc (LetStmt (HsValBinds binds')))]
1001 -- no RecStmt case becuase they get flattened above when doing the LHSes
1002 rn_rec_stmt _ stmt@(L _ (RecStmt {})) _
1003 = pprPanic "rn_rec_stmt: RecStmt" (ppr stmt)
1005 rn_rec_stmt _ stmt@(L _ (ParStmt {})) _ -- Syntactically illegal in mdo
1006 = pprPanic "rn_rec_stmt: ParStmt" (ppr stmt)
1008 rn_rec_stmt _ stmt@(L _ (TransformStmt {})) _ -- Syntactically illegal in mdo
1009 = pprPanic "rn_rec_stmt: TransformStmt" (ppr stmt)
1011 rn_rec_stmt _ stmt@(L _ (GroupStmt {})) _ -- Syntactically illegal in mdo
1012 = pprPanic "rn_rec_stmt: GroupStmt" (ppr stmt)
1014 rn_rec_stmt _ (L _ (LetStmt EmptyLocalBinds)) _
1015 = panic "rn_rec_stmt: LetStmt EmptyLocalBinds"
1017 rn_rec_stmts :: [Name] -> [(LStmtLR Name RdrName, FreeVars)] -> RnM [Segment (LStmt Name)]
1018 rn_rec_stmts bndrs stmts = mapM (uncurry (rn_rec_stmt bndrs)) stmts `thenM` \ segs_s ->
1019 return (concat segs_s)
1021 ---------------------------------------------
1022 addFwdRefs :: [Segment a] -> [Segment a]
1023 -- So far the segments only have forward refs *within* the Stmt
1024 -- (which happens for bind: x <- ...x...)
1025 -- This function adds the cross-seg fwd ref info
1028 = fst (foldr mk_seg ([], emptyNameSet) pairs)
1030 mk_seg (defs, uses, fwds, stmts) (segs, later_defs)
1031 = (new_seg : segs, all_defs)
1033 new_seg = (defs, uses, new_fwds, stmts)
1034 all_defs = later_defs `unionNameSets` defs
1035 new_fwds = fwds `unionNameSets` (uses `intersectNameSet` later_defs)
1036 -- Add the downstream fwd refs here
1038 ----------------------------------------------------
1039 -- Glomming the singleton segments of an mdo into
1040 -- minimal recursive groups.
1042 -- At first I thought this was just strongly connected components, but
1043 -- there's an important constraint: the order of the stmts must not change.
1046 -- mdo { x <- ...y...
1053 -- Here, the first stmt mention 'y', which is bound in the third.
1054 -- But that means that the innocent second stmt (p <- z) gets caught
1055 -- up in the recursion. And that in turn means that the binding for
1056 -- 'z' has to be included... and so on.
1058 -- Start at the tail { r <- x }
1059 -- Now add the next one { z <- y ; r <- x }
1060 -- Now add one more { q <- x ; z <- y ; r <- x }
1061 -- Now one more... but this time we have to group a bunch into rec
1062 -- { rec { y <- ...x... ; q <- x ; z <- y } ; r <- x }
1063 -- Now one more, which we can add on without a rec
1065 -- rec { y <- ...x... ; q <- x ; z <- y } ;
1067 -- Finally we add the last one; since it mentions y we have to
1068 -- glom it togeher with the first two groups
1069 -- { rec { x <- ...y...; p <- z ; y <- ...x... ;
1070 -- q <- x ; z <- y } ;
1073 glomSegments :: [Segment (LStmt Name)] -> [Segment [LStmt Name]]
1075 glomSegments [] = []
1076 glomSegments ((defs,uses,fwds,stmt) : segs)
1077 -- Actually stmts will always be a singleton
1078 = (seg_defs, seg_uses, seg_fwds, seg_stmts) : others
1080 segs' = glomSegments segs
1081 (extras, others) = grab uses segs'
1082 (ds, us, fs, ss) = unzip4 extras
1084 seg_defs = plusFVs ds `plusFV` defs
1085 seg_uses = plusFVs us `plusFV` uses
1086 seg_fwds = plusFVs fs `plusFV` fwds
1087 seg_stmts = stmt : concat ss
1089 grab :: NameSet -- The client
1091 -> ([Segment a], -- Needed by the 'client'
1092 [Segment a]) -- Not needed by the client
1093 -- The result is simply a split of the input
1095 = (reverse yeses, reverse noes)
1097 (noes, yeses) = span not_needed (reverse dus)
1098 not_needed (defs,_,_,_) = not (intersectsNameSet defs uses)
1101 ----------------------------------------------------
1102 segsToStmts :: Stmt Name -- A RecStmt with the SyntaxOps filled in
1103 -> [Segment [LStmt Name]]
1104 -> FreeVars -- Free vars used 'later'
1105 -> ([LStmt Name], FreeVars)
1107 segsToStmts _ [] fvs_later = ([], fvs_later)
1108 segsToStmts empty_rec_stmt ((defs, uses, fwds, ss) : segs) fvs_later
1109 = ASSERT( not (null ss) )
1110 (new_stmt : later_stmts, later_uses `plusFV` uses)
1112 (later_stmts, later_uses) = segsToStmts empty_rec_stmt segs fvs_later
1113 new_stmt | non_rec = head ss
1114 | otherwise = L (getLoc (head ss)) rec_stmt
1115 rec_stmt = empty_rec_stmt { recS_stmts = ss
1116 , recS_later_ids = nameSetToList used_later
1117 , recS_rec_ids = nameSetToList fwds }
1118 non_rec = isSingleton ss && isEmptyNameSet fwds
1119 used_later = defs `intersectNameSet` later_uses
1120 -- The ones needed after the RecStmt
1123 %************************************************************************
1125 \subsubsection{Assertion utils}
1127 %************************************************************************
1130 srcSpanPrimLit :: SrcSpan -> HsExpr Name
1131 srcSpanPrimLit span = HsLit (HsStringPrim (mkFastString (showSDocOneLine (ppr span))))
1133 mkAssertErrorExpr :: RnM (HsExpr Name)
1134 -- Return an expression for (assertError "Foo.hs:27")
1136 = getSrcSpanM `thenM` \ sloc ->
1137 return (HsApp (L sloc (HsVar assertErrorName))
1138 (L sloc (srcSpanPrimLit sloc)))
1141 Note [Adding the implicit parameter to 'assert']
1142 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1143 The renamer transforms (assert e1 e2) to (assert "Foo.hs:27" e1 e2).
1144 By doing this in the renamer we allow the typechecker to just see the
1145 expanded application and do the right thing. But it's not really
1146 the Right Thing because there's no way to "undo" if you want to see
1147 the original source code. We'll have fix this in due course, when
1148 we care more about being able to reconstruct the exact original
1151 %************************************************************************
1153 \subsubsection{Errors}
1155 %************************************************************************
1159 ----------------------
1160 -- Checking when a particular Stmt is ok
1161 checkLetStmt :: HsStmtContext Name -> HsLocalBinds RdrName -> RnM ()
1162 checkLetStmt (ParStmtCtxt _) (HsIPBinds binds) = addErr (badIpBinds (ptext (sLit "a parallel list comprehension:")) binds)
1163 checkLetStmt _ctxt _binds = return ()
1164 -- We do not allow implicit-parameter bindings in a parallel
1165 -- list comprehension. I'm not sure what it might mean.
1168 checkRecStmt :: HsStmtContext Name -> RnM ()
1169 checkRecStmt (MDoExpr {}) = return () -- Recursive stmt ok in 'mdo'
1170 checkRecStmt (DoExpr {}) = return () -- and in 'do'
1171 checkRecStmt ctxt = addErr msg
1173 msg = ptext (sLit "Illegal 'rec' stmt in") <+> pprStmtContext ctxt
1176 checkParStmt :: HsStmtContext Name -> RnM ()
1178 = do { parallel_list_comp <- doptM Opt_ParallelListComp
1179 ; checkErr parallel_list_comp msg }
1181 msg = ptext (sLit "Illegal parallel list comprehension: use -XParallelListComp")
1184 checkTransformStmt :: HsStmtContext Name -> RnM ()
1185 checkTransformStmt ListComp -- Ensure we are really within a list comprehension because otherwise the
1186 -- desugarer will break when we come to operate on a parallel array
1187 = do { transform_list_comp <- doptM Opt_TransformListComp
1188 ; checkErr transform_list_comp msg }
1190 msg = ptext (sLit "Illegal transform or grouping list comprehension: use -XTransformListComp")
1191 checkTransformStmt (ParStmtCtxt ctxt) = checkTransformStmt ctxt -- Ok to nest inside a parallel comprehension
1192 checkTransformStmt (TransformStmtCtxt ctxt) = checkTransformStmt ctxt -- Ok to nest inside a parallel comprehension
1193 checkTransformStmt ctxt = addErr msg
1195 msg = ptext (sLit "Illegal transform or grouping in") <+> pprStmtContext ctxt
1198 checkTupleSection :: [HsTupArg RdrName] -> RnM ()
1199 checkTupleSection args
1200 = do { tuple_section <- doptM Opt_TupleSections
1201 ; checkErr (all tupArgPresent args || tuple_section) msg }
1203 msg = ptext (sLit "Illegal tuple section: use -XTupleSections")
1206 sectionErr :: HsExpr RdrName -> SDoc
1208 = hang (ptext (sLit "A section must be enclosed in parentheses"))
1209 2 (ptext (sLit "thus:") <+> (parens (ppr expr)))
1211 patSynErr :: HsExpr RdrName -> RnM (HsExpr Name, FreeVars)
1212 patSynErr e = do { addErr (sep [ptext (sLit "Pattern syntax in expression context:"),
1214 ; return (EWildPat, emptyFVs) }
1216 badIpBinds :: Outputable a => SDoc -> a -> SDoc
1217 badIpBinds what binds
1218 = hang (ptext (sLit "Implicit-parameter bindings illegal in") <+> what)