2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[RnSource]{Main pass of renamer}
7 module RnTypes ( rnHsType, rnHsSigType, rnHsTypeFVs, rnHsSigTypeFVs, rnContext ) where
9 import CmdLineOpts ( DynFlag(Opt_WarnMisc, Opt_WarnUnusedMatches) )
12 import RdrHsSyn ( RdrNameContext, RdrNameHsType, extractHsTyRdrTyVars, extractHsCtxtRdrTyVars )
13 import RnHsSyn ( RenamedContext, RenamedHsType, extractHsTyNames, tupleTyCon_name )
14 import RnEnv ( lookupOccRn, newIPName, bindTyVarsRn )
17 import PrelInfo ( cCallishClassKeys )
18 import RdrName ( elemRdrEnv )
19 import NameSet ( FreeVars )
20 import Unique ( Uniquable(..) )
23 import ListSetOps ( removeDupsEq )
26 #include "HsVersions.h"
29 These type renamers are in a separate module, rather than in (say) RnSource,
30 to break several loop.
32 %*********************************************************
34 \subsection{Renaming types}
36 %*********************************************************
39 rnHsTypeFVs :: SDoc -> RdrNameHsType -> RnMS (RenamedHsType, FreeVars)
40 rnHsTypeFVs doc_str ty
41 = rnHsType doc_str ty `thenRn` \ ty' ->
42 returnRn (ty', extractHsTyNames ty')
44 rnHsSigTypeFVs :: SDoc -> RdrNameHsType -> RnMS (RenamedHsType, FreeVars)
45 rnHsSigTypeFVs doc_str ty
46 = rnHsSigType doc_str ty `thenRn` \ ty' ->
47 returnRn (ty', extractHsTyNames ty')
49 rnHsSigType :: SDoc -> RdrNameHsType -> RnMS RenamedHsType
50 -- rnHsSigType is used for source-language type signatures,
51 -- which use *implicit* universal quantification.
52 rnHsSigType doc_str ty
53 = rnHsType (text "In the type signature for" <+> doc_str) ty
56 rnHsType is here because we call it from loadInstDecl, and I didn't
57 want a gratuitous knot.
60 rnHsType :: SDoc -> RdrNameHsType -> RnMS RenamedHsType
62 rnHsType doc (HsForAllTy Nothing ctxt ty)
63 -- Implicit quantifiction in source code (no kinds on tyvars)
64 -- Given the signature C => T we universally quantify
65 -- over FV(T) \ {in-scope-tyvars}
66 = getLocalNameEnv `thenRn` \ name_env ->
68 mentioned_in_tau = extractHsTyRdrTyVars ty
69 mentioned_in_ctxt = extractHsCtxtRdrTyVars ctxt
70 mentioned = nub (mentioned_in_tau ++ mentioned_in_ctxt)
71 forall_tyvars = filter (not . (`elemRdrEnv` name_env)) mentioned
73 rnForAll doc (map UserTyVar forall_tyvars) ctxt ty
75 rnHsType doc (HsForAllTy (Just forall_tyvars) ctxt tau)
76 -- Explicit quantification.
77 -- Check that the forall'd tyvars are actually
78 -- mentioned in the type, and produce a warning if not
80 mentioned_in_tau = extractHsTyRdrTyVars tau
81 mentioned_in_ctxt = extractHsCtxtRdrTyVars ctxt
82 mentioned = nub (mentioned_in_tau ++ mentioned_in_ctxt)
83 forall_tyvar_names = hsTyVarNames forall_tyvars
85 -- Explicitly quantified but not mentioned in ctxt or tau
86 warn_guys = filter (`notElem` mentioned) forall_tyvar_names
88 mapRn_ (forAllWarn doc tau) warn_guys `thenRn_`
89 rnForAll doc forall_tyvars ctxt tau
91 rnHsType doc (HsTyVar tyvar)
92 = lookupOccRn tyvar `thenRn` \ tyvar' ->
93 returnRn (HsTyVar tyvar')
95 rnHsType doc (HsOpTy ty1 opname ty2)
96 = lookupOccRn opname `thenRn` \ name' ->
97 rnHsType doc ty1 `thenRn` \ ty1' ->
98 rnHsType doc ty2 `thenRn` \ ty2' ->
99 returnRn (HsOpTy ty1' name' ty2')
101 rnHsType doc (HsNumTy i)
102 | i == 1 = returnRn (HsNumTy i)
103 | otherwise = failWithRn (HsNumTy i)
104 (ptext SLIT("Only unit numeric type pattern is valid"))
106 rnHsType doc (HsFunTy ty1 ty2)
107 = rnHsType doc ty1 `thenRn` \ ty1' ->
108 -- Might find a for-all as the arg of a function type
109 rnHsType doc ty2 `thenRn` \ ty2' ->
110 -- Or as the result. This happens when reading Prelude.hi
111 -- when we find return :: forall m. Monad m -> forall a. a -> m a
112 returnRn (HsFunTy ty1' ty2')
114 rnHsType doc (HsListTy ty)
115 = rnHsType doc ty `thenRn` \ ty' ->
116 returnRn (HsListTy ty')
118 rnHsType doc (HsPArrTy ty)
119 = rnHsType doc ty `thenRn` \ ty' ->
120 returnRn (HsPArrTy ty')
122 -- Unboxed tuples are allowed to have poly-typed arguments. These
123 -- sometimes crop up as a result of CPR worker-wrappering dictionaries.
124 rnHsType doc (HsTupleTy (HsTupCon _ boxity arity) tys)
125 -- Don't do lookupOccRn, because this is built-in syntax
126 -- so it doesn't need to be in scope
127 = mapRn (rnHsType doc) tys `thenRn` \ tys' ->
128 returnRn (HsTupleTy (HsTupCon tup_name boxity arity) tys')
130 tup_name = tupleTyCon_name boxity arity
133 rnHsType doc (HsAppTy ty1 ty2)
134 = rnHsType doc ty1 `thenRn` \ ty1' ->
135 rnHsType doc ty2 `thenRn` \ ty2' ->
136 returnRn (HsAppTy ty1' ty2')
138 rnHsType doc (HsPredTy pred)
139 = rnPred doc pred `thenRn` \ pred' ->
140 returnRn (HsPredTy pred')
142 rnHsTypes doc tys = mapRn (rnHsType doc) tys
146 rnForAll doc forall_tyvars ctxt ty
147 = bindTyVarsRn doc forall_tyvars $ \ new_tyvars ->
148 rnContext doc ctxt `thenRn` \ new_ctxt ->
149 rnHsType doc ty `thenRn` \ new_ty ->
150 returnRn (mkHsForAllTy (Just new_tyvars) new_ctxt new_ty)
154 rnContext :: SDoc -> RdrNameContext -> RnMS RenamedContext
156 = mapRn rn_pred ctxt `thenRn` \ theta ->
158 -- Check for duplicate assertions
159 -- If this isn't an error, then it ought to be:
160 ifOptRn Opt_WarnMisc (
162 (_, dups) = removeDupsEq theta
163 -- We only have equality, not ordering
165 mapRn (addWarnRn . dupClassAssertWarn theta) dups
170 --Someone discovered that @CCallable@ and @CReturnable@
171 -- could be used in contexts such as:
172 -- foo :: CCallable a => a -> PrimIO Int
173 -- Doing this utterly wrecks the whole point of introducing these
174 -- classes so we specifically check that this isn't being done.
175 rn_pred pred = rnPred doc pred `thenRn` \ pred'->
176 checkRn (not (bad_pred pred'))
177 (naughtyCCallContextErr pred') `thenRn_`
180 bad_pred (HsClassP clas _) = getUnique clas `elem` cCallishClassKeys
181 bad_pred other = False
184 rnPred doc (HsClassP clas tys)
185 = lookupOccRn clas `thenRn` \ clas_name ->
186 rnHsTypes doc tys `thenRn` \ tys' ->
187 returnRn (HsClassP clas_name tys')
189 rnPred doc (HsIParam n ty)
190 = newIPName n `thenRn` \ name ->
191 rnHsType doc ty `thenRn` \ ty' ->
192 returnRn (HsIParam name ty')
197 forAllWarn doc ty tyvar
198 = ifOptRn Opt_WarnUnusedMatches $
199 getModeRn `thenRn` \ mode ->
202 InterfaceMode -> returnRn () ; -- Don't warn of unused tyvars in interface files
203 -- unless DEBUG is on, in which case it is slightly
204 -- informative. They can arise from mkRhsTyLam,
205 #endif -- leading to (say) f :: forall a b. [b] -> [b]
208 sep [ptext SLIT("The universally quantified type variable") <+> quotes (ppr tyvar),
209 nest 4 (ptext SLIT("does not appear in the type") <+> quotes (ppr ty))]
215 dupClassAssertWarn ctxt (assertion : dups)
216 = sep [hsep [ptext SLIT("Duplicate class assertion"),
217 quotes (ppr assertion),
218 ptext SLIT("in the context:")],
219 nest 4 (pprHsContext ctxt <+> ptext SLIT("..."))]
221 naughtyCCallContextErr (HsClassP clas _)
222 = sep [ptext SLIT("Can't use class") <+> quotes (ppr clas),
223 ptext SLIT("in a context")]