2 % (c) The AQUA Project, Glasgow University, 1998
4 \section[TcForeign]{Typechecking \tr{foreign} declarations}
6 A foreign declaration is used to either give an externally
7 implemented function a Haskell type (and calling interface) or
8 give a Haskell function an external calling interface. Either way,
9 the range of argument and result types these functions can accommodate
10 is restricted to what the outside world understands (read C), and this
11 module checks to see if a foreign declaration has got a legal type.
21 #include "HsVersions.h"
23 import HsSyn ( ForeignDecl(..), HsExpr(..),
24 MonoBinds(..), ForeignImport(..), ForeignExport(..),
27 import RnHsSyn ( RenamedForeignDecl )
30 import TcHsType ( tcHsSigType, UserTypeCtxt(..) )
31 import TcHsSyn ( TcMonoBinds, TypecheckedForeignDecl, TcForeignDecl )
32 import TcExpr ( tcCheckSigma )
34 import ErrUtils ( Message )
35 import Id ( Id, mkLocalId, setIdLocalExported )
36 import PrimRep ( getPrimRepSize, isFloatingRep )
37 import Type ( typePrimRep )
38 import OccName ( mkForeignExportOcc )
39 import Name ( Name, NamedThing(..), mkExternalName )
40 import TcType ( Type, tcSplitFunTys, tcSplitTyConApp_maybe,
42 isFFIArgumentTy, isFFIImportResultTy,
43 isFFIExportResultTy, isFFILabelTy,
44 isFFIExternalTy, isFFIDynArgumentTy,
45 isFFIDynResultTy, isFFIDotnetTy, isFFIDotnetObjTy,
48 import ForeignCall ( CExportSpec(..), CCallTarget(..),
49 isDynamicTarget, withDNTypes, DNKind(..), DNCallSpec(..) )
50 import CStrings ( CLabelString, isCLabelString )
51 import PrelNames ( hasKey, ioTyConKey )
52 import CmdLineOpts ( dopt_HscLang, HscLang(..) )
59 isForeignImport :: ForeignDecl name -> Bool
60 isForeignImport (ForeignImport _ _ _ _ _) = True
61 isForeignImport _ = False
64 isForeignExport :: ForeignDecl name -> Bool
65 isForeignExport (ForeignExport _ _ _ _ _) = True
66 isForeignExport _ = False
69 %************************************************************************
73 %************************************************************************
76 tcForeignImports :: [ForeignDecl Name] -> TcM ([Id], [TypecheckedForeignDecl])
77 tcForeignImports decls
78 = mapAndUnzipM tcFImport (filter isForeignImport decls)
80 tcFImport :: RenamedForeignDecl -> TcM (Id, TypecheckedForeignDecl)
81 tcFImport fo@(ForeignImport nm hs_ty imp_decl isDeprec src_loc)
83 addErrCtxt (foreignDeclCtxt fo) $
84 tcHsSigType (ForSigCtxt nm) hs_ty `thenM` \ sig_ty ->
86 -- drop the foralls before inspecting the structure
87 -- of the foreign type.
88 (_, t_ty) = tcSplitForAllTys sig_ty
89 (arg_tys, res_ty) = tcSplitFunTys t_ty
90 id = mkLocalId nm sig_ty
91 -- Use a LocalId to obey the invariant that locally-defined
92 -- things are LocalIds. However, it does not need zonking,
93 -- (so TcHsSyn.zonkForeignExports ignores it).
95 tcCheckFIType sig_ty arg_tys res_ty imp_decl `thenM` \ imp_decl' ->
96 -- can't use sig_ty here because it :: Type and we need HsType Id
97 -- hence the undefined
98 returnM (id, ForeignImport id undefined imp_decl' isDeprec src_loc)
102 ------------ Checking types for foreign import ----------------------
104 tcCheckFIType _ arg_tys res_ty (DNImport spec)
105 = checkCg checkDotnet `thenM_`
106 getDOpts `thenM` \ dflags ->
107 checkForeignArgs (isFFIDotnetTy dflags) arg_tys `thenM_`
108 checkForeignRes True{-non IO ok-} (isFFIDotnetTy dflags) res_ty `thenM_`
109 let (DNCallSpec isStatic kind _ _ _ _) = spec in
111 DNMethod | not isStatic ->
113 [] -> addErrTc illegalDNMethodSig
115 | not (isFFIDotnetObjTy (last arg_tys)) -> addErrTc illegalDNMethodSig
116 | otherwise -> returnM ()
117 _ -> returnM ()) `thenM_`
118 returnM (DNImport (withDNTypes spec (map toDNType arg_tys) (toDNType res_ty)))
120 tcCheckFIType sig_ty arg_tys res_ty idecl@(CImport _ _ _ _ (CLabel _))
121 = checkCg checkCOrAsm `thenM_`
122 check (isFFILabelTy sig_ty) (illegalForeignTyErr empty sig_ty) `thenM_`
125 tcCheckFIType sig_ty arg_tys res_ty idecl@(CImport cconv _ _ _ CWrapper)
126 = -- Foreign wrapper (former f.e.d.)
127 -- The type must be of the form ft -> IO (FunPtr ft), where ft is a
128 -- valid foreign type. For legacy reasons ft -> IO (Ptr ft) as well
129 -- as ft -> IO Addr is accepted, too. The use of the latter two forms
130 -- is DEPRECATED, though.
131 checkCg checkCOrAsmOrInterp `thenM_`
133 [arg1_ty] -> checkForeignArgs isFFIExternalTy arg1_tys `thenM_`
134 checkForeignRes nonIOok isFFIExportResultTy res1_ty `thenM_`
135 checkForeignRes mustBeIO isFFIDynResultTy res_ty `thenM_`
136 checkFEDArgs arg1_tys
138 (arg1_tys, res1_ty) = tcSplitFunTys arg1_ty
139 other -> addErrTc (illegalForeignTyErr empty sig_ty) ) `thenM_`
142 tcCheckFIType sig_ty arg_tys res_ty idecl@(CImport _ safety _ _ (CFunction target))
143 | isDynamicTarget target -- Foreign import dynamic
144 = checkCg checkCOrAsmOrInterp `thenM_`
145 case arg_tys of -- The first arg must be Ptr, FunPtr, or Addr
147 check False (illegalForeignTyErr empty sig_ty) `thenM_`
150 getDOpts `thenM` \ dflags ->
151 check (isFFIDynArgumentTy arg1_ty)
152 (illegalForeignTyErr argument arg1_ty) `thenM_`
153 checkForeignArgs (isFFIArgumentTy dflags safety) arg_tys `thenM_`
154 checkForeignRes nonIOok (isFFIImportResultTy dflags) res_ty `thenM_`
156 | otherwise -- Normal foreign import
157 = checkCg (checkCOrAsmOrDotNetOrInterp) `thenM_`
158 checkCTarget target `thenM_`
159 getDOpts `thenM` \ dflags ->
160 checkForeignArgs (isFFIArgumentTy dflags safety) arg_tys `thenM_`
161 checkForeignRes nonIOok (isFFIImportResultTy dflags) res_ty `thenM_`
164 -- This makes a convenient place to check
165 -- that the C identifier is valid for C
166 checkCTarget (StaticTarget str)
167 = checkCg checkCOrAsmOrDotNetOrInterp `thenM_`
168 check (isCLabelString str) (badCName str)
171 On an Alpha, with foreign export dynamic, due to a giant hack when
172 building adjustor thunks, we only allow 4 integer arguments with
173 foreign export dynamic (i.e., 32 bytes of arguments after padding each
174 argument to a quadword, excluding floating-point arguments).
176 The check is needed for both via-C and native-code routes
179 #include "nativeGen/NCG.h"
180 #if alpha_TARGET_ARCH
182 = check (integral_args <= 4) err
184 integral_args = sum (map getPrimRepSize $
185 filter (not . isFloatingRep) $
186 map typePrimRep arg_tys)
187 err = ptext SLIT("On Alpha, I can only handle 4 non-floating-point arguments to foreign export dynamic")
189 checkFEDArgs arg_tys = returnM ()
194 %************************************************************************
198 %************************************************************************
201 tcForeignExports :: [ForeignDecl Name]
202 -> TcM (TcMonoBinds, [TcForeignDecl])
203 tcForeignExports decls
204 = foldlM combine (EmptyMonoBinds, []) (filter isForeignExport decls)
206 combine (binds, fs) fe =
207 tcFExport fe `thenM ` \ (b, f) ->
208 returnM (b `AndMonoBinds` binds, f:fs)
210 tcFExport :: RenamedForeignDecl -> TcM (TcMonoBinds, TcForeignDecl)
211 tcFExport fo@(ForeignExport nm hs_ty spec isDeprec src_loc) =
213 addErrCtxt (foreignDeclCtxt fo) $
215 tcHsSigType (ForSigCtxt nm) hs_ty `thenM` \ sig_ty ->
216 tcCheckSigma (HsVar nm) sig_ty `thenM` \ rhs ->
218 tcCheckFEType sig_ty spec `thenM_`
220 -- we're exporting a function, but at a type possibly more
221 -- constrained than its declared/inferred type. Hence the need
222 -- to create a local binding which will call the exported function
223 -- at a particular type (and, maybe, overloading).
225 newUnique `thenM` \ uniq ->
226 getModule `thenM` \ mod ->
228 gnm = mkExternalName uniq mod (mkForeignExportOcc (getOccName nm))
230 id = setIdLocalExported (mkLocalId gnm sig_ty)
231 bind = VarMonoBind id rhs
233 returnM (bind, ForeignExport id undefined spec isDeprec src_loc)
236 ------------ Checking argument types for foreign export ----------------------
239 tcCheckFEType sig_ty (CExport (CExportStatic str _))
240 = check (isCLabelString str) (badCName str) `thenM_`
241 checkForeignArgs isFFIExternalTy arg_tys `thenM_`
242 checkForeignRes nonIOok isFFIExportResultTy res_ty
244 -- Drop the foralls before inspecting n
245 -- the structure of the foreign type.
246 (_, t_ty) = tcSplitForAllTys sig_ty
247 (arg_tys, res_ty) = tcSplitFunTys t_ty
252 %************************************************************************
254 \subsection{Miscellaneous}
256 %************************************************************************
259 ------------ Checking argument types for foreign import ----------------------
260 checkForeignArgs :: (Type -> Bool) -> [Type] -> TcM ()
261 checkForeignArgs pred tys
262 = mappM go tys `thenM_`
265 go ty = check (pred ty) (illegalForeignTyErr argument ty)
267 ------------ Checking result types for foreign calls ----------------------
268 -- Check that the type has the form
269 -- (IO t) or (t) , and that t satisfies the given predicate.
271 checkForeignRes :: Bool -> (Type -> Bool) -> Type -> TcM ()
276 checkForeignRes non_io_result_ok pred_res_ty ty
277 = case tcSplitTyConApp_maybe ty of
279 | io `hasKey` ioTyConKey && pred_res_ty res_ty
282 -> check (non_io_result_ok && pred_res_ty ty)
283 (illegalForeignTyErr result ty)
287 checkDotnet HscILX = Nothing
288 #if defined(mingw32_TARGET_OS)
289 checkDotnet HscC = Nothing
290 checkDotnet _ = Just (text "requires C code generation (-fvia-C)")
292 checkDotnet other = Just (text "requires .NET support (-filx or win32)")
295 checkCOrAsm HscC = Nothing
296 checkCOrAsm HscAsm = Nothing
298 = Just (text "requires via-C or native code generation (-fvia-C)")
300 checkCOrAsmOrInterp HscC = Nothing
301 checkCOrAsmOrInterp HscAsm = Nothing
302 checkCOrAsmOrInterp HscInterpreted = Nothing
303 checkCOrAsmOrInterp other
304 = Just (text "requires interpreted, C or native code generation")
306 checkCOrAsmOrDotNetOrInterp HscC = Nothing
307 checkCOrAsmOrDotNetOrInterp HscAsm = Nothing
308 checkCOrAsmOrDotNetOrInterp HscILX = Nothing
309 checkCOrAsmOrDotNetOrInterp HscInterpreted = Nothing
310 checkCOrAsmOrDotNetOrInterp other
311 = Just (text "requires interpreted, C, native or .NET ILX code generation")
314 = getDOpts `thenM` \ dflags ->
315 let hscLang = dopt_HscLang dflags in
317 HscNothing -> returnM ()
319 case check hscLang of
320 Nothing -> returnM ()
321 Just err -> addErrTc (text "Illegal foreign declaration:" <+> err)
327 check :: Bool -> Message -> TcM ()
328 check True _ = returnM ()
329 check _ the_err = addErrTc the_err
331 illegalForeignTyErr arg_or_res ty
332 = hang (hsep [ptext SLIT("Unacceptable"), arg_or_res,
333 ptext SLIT("type in foreign declaration:")])
336 -- Used for 'arg_or_res' argument to illegalForeignTyErr
337 argument = text "argument"
338 result = text "result"
340 badCName :: CLabelString -> Message
342 = sep [quotes (ppr target) <+> ptext SLIT("is not a valid C identifier")]
345 = hang (ptext SLIT("When checking declaration:"))
349 = ptext SLIT("'This pointer' expected as last argument")