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 TcMonoType ( tcHsSigType, UserTypeCtxt(..) )
31 import TcHsSyn ( TcMonoBinds, TypecheckedForeignDecl, TcForeignDecl )
32 import TcExpr ( tcCheckSigma )
34 import ErrUtils ( Message )
35 import Id ( Id, mkLocalId, mkVanillaGlobal, setIdLocalExported )
36 import IdInfo ( noCafIdInfo )
37 import PrimRep ( getPrimRepSize, isFloatingRep )
38 import Type ( typePrimRep )
39 import OccName ( mkForeignExportOcc )
40 import Name ( Name, NamedThing(..), mkExternalName )
41 import TcType ( Type, tcSplitFunTys, tcSplitTyConApp_maybe,
43 isFFIArgumentTy, isFFIImportResultTy,
44 isFFIExportResultTy, isFFILabelTy,
45 isFFIExternalTy, isFFIDynArgumentTy,
46 isFFIDynResultTy, isFFIDotnetTy, isFFIDotnetObjTy,
49 import ForeignCall ( CExportSpec(..), CCallTarget(..), CCallConv(..),
50 isDynamicTarget, isCasmTarget, withDNTypes, DNKind(..), DNCallSpec(..) )
51 import CStrings ( CLabelString, isCLabelString )
52 import PrelNames ( hasKey, ioTyConKey )
53 import CmdLineOpts ( dopt_HscLang, HscLang(..) )
60 isForeignImport :: ForeignDecl name -> Bool
61 isForeignImport (ForeignImport _ _ _ _ _) = True
62 isForeignImport _ = False
65 isForeignExport :: ForeignDecl name -> Bool
66 isForeignExport (ForeignExport _ _ _ _ _) = True
67 isForeignExport _ = False
70 %************************************************************************
74 %************************************************************************
77 tcForeignImports :: [ForeignDecl Name] -> TcM ([Id], [TypecheckedForeignDecl])
78 tcForeignImports decls
79 = mapAndUnzipM tcFImport (filter isForeignImport decls)
81 tcFImport :: RenamedForeignDecl -> TcM (Id, TypecheckedForeignDecl)
82 tcFImport fo@(ForeignImport nm hs_ty imp_decl isDeprec src_loc)
84 addErrCtxt (foreignDeclCtxt fo) $
85 tcHsSigType (ForSigCtxt nm) hs_ty `thenM` \ sig_ty ->
87 -- drop the foralls before inspecting the structure
88 -- of the foreign type.
89 (_, t_ty) = tcSplitForAllTys sig_ty
90 (arg_tys, res_ty) = tcSplitFunTys t_ty
91 id = mkLocalId nm sig_ty
92 -- Use a LocalId to obey the invariant that locally-defined
93 -- things are LocalIds. However, it does not need zonking,
94 -- (so TcHsSyn.zonkForeignExports ignores it).
96 tcCheckFIType sig_ty arg_tys res_ty imp_decl `thenM` \ imp_decl' ->
97 -- can't use sig_ty here because it :: Type and we need HsType Id
98 -- hence the undefined
99 returnM (id, ForeignImport id undefined imp_decl' isDeprec src_loc)
103 ------------ Checking types for foreign import ----------------------
105 tcCheckFIType _ arg_tys res_ty (DNImport spec)
106 = checkCg checkDotnet `thenM_`
107 getDOpts `thenM` \ dflags ->
108 checkForeignArgs (isFFIDotnetTy dflags) arg_tys `thenM_`
109 checkForeignRes True{-non IO ok-} (isFFIDotnetTy dflags) res_ty `thenM_`
110 let (DNCallSpec isStatic kind _ _ _ _) = spec in
112 DNMethod | not isStatic ->
114 [] -> addErrTc illegalDNMethodSig
116 | not (isFFIDotnetObjTy (last arg_tys)) -> addErrTc illegalDNMethodSig
117 | otherwise -> returnM ()
118 _ -> returnM ()) `thenM_`
119 returnM (DNImport (withDNTypes spec (map toDNType arg_tys) (toDNType res_ty)))
121 tcCheckFIType sig_ty arg_tys res_ty idecl@(CImport _ _ _ _ (CLabel _))
122 = checkCg checkCOrAsm `thenM_`
123 check (isFFILabelTy sig_ty) (illegalForeignTyErr empty sig_ty) `thenM_`
126 tcCheckFIType sig_ty arg_tys res_ty idecl@(CImport cconv _ _ _ CWrapper)
127 = -- Foreign wrapper (former f.e.d.)
128 -- The type must be of the form ft -> IO (FunPtr ft), where ft is a
129 -- valid foreign type. For legacy reasons ft -> IO (Ptr ft) as well
130 -- as ft -> IO Addr is accepted, too. The use of the latter two forms
131 -- is DEPRECATED, though.
132 checkCg checkCOrAsmOrInterp `thenM_`
134 [arg1_ty] -> checkForeignArgs isFFIExternalTy arg1_tys `thenM_`
135 checkForeignRes nonIOok isFFIExportResultTy res1_ty `thenM_`
136 checkForeignRes mustBeIO isFFIDynResultTy res_ty `thenM_`
137 checkFEDArgs arg1_tys
139 (arg1_tys, res1_ty) = tcSplitFunTys arg1_ty
140 other -> addErrTc (illegalForeignTyErr empty sig_ty) ) `thenM_`
143 tcCheckFIType sig_ty arg_tys res_ty idecl@(CImport _ safety _ _ (CFunction target))
144 | isDynamicTarget target -- Foreign import dynamic
145 = checkCg checkCOrAsmOrInterp `thenM_`
146 case arg_tys of -- The first arg must be Ptr, FunPtr, or Addr
148 check False (illegalForeignTyErr empty sig_ty) `thenM_`
151 getDOpts `thenM` \ dflags ->
152 check (isFFIDynArgumentTy arg1_ty)
153 (illegalForeignTyErr argument arg1_ty) `thenM_`
154 checkForeignArgs (isFFIArgumentTy dflags safety) arg_tys `thenM_`
155 checkForeignRes nonIOok (isFFIImportResultTy dflags) res_ty `thenM_`
157 | otherwise -- Normal foreign import
158 = checkCg (if isCasmTarget target
159 then checkC else checkCOrAsmOrDotNetOrInterp) `thenM_`
160 checkCTarget target `thenM_`
161 getDOpts `thenM` \ dflags ->
162 checkForeignArgs (isFFIArgumentTy dflags safety) arg_tys `thenM_`
163 checkForeignRes nonIOok (isFFIImportResultTy dflags) res_ty `thenM_`
166 -- This makes a convenient place to check
167 -- that the C identifier is valid for C
168 checkCTarget (StaticTarget str)
169 = checkCg checkCOrAsmOrDotNetOrInterp `thenM_`
170 check (isCLabelString str) (badCName str)
172 checkCTarget (CasmTarget _)
176 On an Alpha, with foreign export dynamic, due to a giant hack when
177 building adjustor thunks, we only allow 4 integer arguments with
178 foreign export dynamic (i.e., 32 bytes of arguments after padding each
179 argument to a quadword, excluding floating-point arguments).
181 The check is needed for both via-C and native-code routes
184 #include "nativeGen/NCG.h"
185 #if alpha_TARGET_ARCH
187 = check (integral_args <= 4) err
189 integral_args = sum (map getPrimRepSize $
190 filter (not . isFloatingRep) $
191 map typePrimRep arg_tys)
192 err = ptext SLIT("On Alpha, I can only handle 4 non-floating-point arguments to foreign export dynamic")
194 checkFEDArgs arg_tys = returnM ()
199 %************************************************************************
203 %************************************************************************
206 tcForeignExports :: [ForeignDecl Name]
207 -> TcM (TcMonoBinds, [TcForeignDecl])
208 tcForeignExports decls
209 = foldlM combine (EmptyMonoBinds, []) (filter isForeignExport decls)
211 combine (binds, fs) fe =
212 tcFExport fe `thenM ` \ (b, f) ->
213 returnM (b `AndMonoBinds` binds, f:fs)
215 tcFExport :: RenamedForeignDecl -> TcM (TcMonoBinds, TcForeignDecl)
216 tcFExport fo@(ForeignExport nm hs_ty spec isDeprec src_loc) =
218 addErrCtxt (foreignDeclCtxt fo) $
220 tcHsSigType (ForSigCtxt nm) hs_ty `thenM` \ sig_ty ->
221 tcCheckSigma (HsVar nm) sig_ty `thenM` \ rhs ->
223 tcCheckFEType sig_ty spec `thenM_`
225 -- we're exporting a function, but at a type possibly more
226 -- constrained than its declared/inferred type. Hence the need
227 -- to create a local binding which will call the exported function
228 -- at a particular type (and, maybe, overloading).
230 newUnique `thenM` \ uniq ->
231 getModule `thenM` \ mod ->
233 gnm = mkExternalName uniq mod (mkForeignExportOcc (getOccName nm)) src_loc
234 id = setIdLocalExported (mkLocalId gnm sig_ty)
235 bind = VarMonoBind id rhs
237 returnM (bind, ForeignExport id undefined spec isDeprec src_loc)
240 ------------ Checking argument types for foreign export ----------------------
243 tcCheckFEType sig_ty (CExport (CExportStatic str _))
244 = check (isCLabelString str) (badCName str) `thenM_`
245 checkForeignArgs isFFIExternalTy arg_tys `thenM_`
246 checkForeignRes nonIOok isFFIExportResultTy res_ty
248 -- Drop the foralls before inspecting n
249 -- the structure of the foreign type.
250 (_, t_ty) = tcSplitForAllTys sig_ty
251 (arg_tys, res_ty) = tcSplitFunTys t_ty
256 %************************************************************************
258 \subsection{Miscellaneous}
260 %************************************************************************
263 ------------ Checking argument types for foreign import ----------------------
264 checkForeignArgs :: (Type -> Bool) -> [Type] -> TcM ()
265 checkForeignArgs pred tys
266 = mappM go tys `thenM_`
269 go ty = check (pred ty) (illegalForeignTyErr argument ty)
271 ------------ Checking result types for foreign calls ----------------------
272 -- Check that the type has the form
273 -- (IO t) or (t) , and that t satisfies the given predicate.
275 checkForeignRes :: Bool -> (Type -> Bool) -> Type -> TcM ()
280 checkForeignRes non_io_result_ok pred_res_ty ty
281 = case tcSplitTyConApp_maybe ty of
283 | io `hasKey` ioTyConKey && pred_res_ty res_ty
286 -> check (non_io_result_ok && pred_res_ty ty)
287 (illegalForeignTyErr result ty)
291 checkDotnet HscILX = Nothing
292 #if defined(mingw32_TARGET_OS)
293 checkDotnet HscC = Nothing
294 checkDotnet _ = Just (text "requires C code generation (-fvia-C)")
296 checkDotnet other = Just (text "requires .NET support (-filx or win32)")
299 checkC HscC = Nothing
300 checkC other = Just (text "requires C code generation (-fvia-C)")
302 checkCOrAsm HscC = Nothing
303 checkCOrAsm HscAsm = Nothing
305 = Just (text "requires via-C or native code generation (-fvia-C)")
307 checkCOrAsmOrInterp HscC = Nothing
308 checkCOrAsmOrInterp HscAsm = Nothing
309 checkCOrAsmOrInterp HscInterpreted = Nothing
310 checkCOrAsmOrInterp other
311 = Just (text "requires interpreted, C or native code generation")
313 checkCOrAsmOrDotNet HscC = Nothing
314 checkCOrAsmOrDotNet HscAsm = Nothing
315 checkCOrAsmOrDotNet HscILX = Nothing
316 checkCOrAsmOrDotNet other
317 = Just (text "requires C, native or .NET ILX code generation")
319 checkCOrAsmOrDotNetOrInterp HscC = Nothing
320 checkCOrAsmOrDotNetOrInterp HscAsm = Nothing
321 checkCOrAsmOrDotNetOrInterp HscILX = Nothing
322 checkCOrAsmOrDotNetOrInterp HscInterpreted = Nothing
323 checkCOrAsmOrDotNetOrInterp other
324 = Just (text "requires interpreted, C, native or .NET ILX code generation")
327 = getDOpts `thenM` \ dflags ->
328 let hscLang = dopt_HscLang dflags in
330 HscNothing -> returnM ()
332 case check hscLang of
333 Nothing -> returnM ()
334 Just err -> addErrTc (text "Illegal foreign declaration:" <+> err)
340 check :: Bool -> Message -> TcM ()
341 check True _ = returnM ()
342 check _ the_err = addErrTc the_err
344 illegalForeignTyErr arg_or_res ty
345 = hang (hsep [ptext SLIT("Unacceptable"), arg_or_res,
346 ptext SLIT("type in foreign declaration:")])
349 -- Used for 'arg_or_res' argument to illegalForeignTyErr
350 argument = text "argument"
351 result = text "result"
353 badCName :: CLabelString -> Message
355 = sep [quotes (ppr target) <+> ptext SLIT("is not a valid C identifier")]
358 = hang (ptext SLIT("When checking declaration:"))
362 = ptext SLIT("'This pointer' expected as last argument")