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.
20 #include "../includes/ghcconfig.h"
21 #include "HsVersions.h"
26 import TcHsType ( tcHsSigType, UserTypeCtxt(..) )
27 import TcExpr ( tcCheckSigma )
29 import ForeignCall ( CCallConv(..) )
30 import ErrUtils ( Message )
31 import Id ( Id, mkLocalId, mkExportedLocalId )
33 import PrimRep ( getPrimRepSize, isFloatingRep )
34 import Type ( typePrimRep )
36 import OccName ( mkForeignExportOcc )
37 import Name ( Name, NamedThing(..), mkExternalName )
38 import TcType ( Type, tcSplitFunTys, tcSplitTyConApp_maybe,
40 isFFIArgumentTy, isFFIImportResultTy,
41 isFFIExportResultTy, isFFILabelTy,
42 isFFIExternalTy, isFFIDynArgumentTy,
43 isFFIDynResultTy, isFFIDotnetTy, isFFIDotnetObjTy,
46 import ForeignCall ( CExportSpec(..), CCallTarget(..),
47 CLabelString, isCLabelString,
48 isDynamicTarget, withDNTypes, DNKind(..), DNCallSpec(..) )
49 import PrelNames ( hasKey, ioTyConKey )
50 import CmdLineOpts ( dopt_HscLang, HscLang(..) )
52 import SrcLoc ( Located(..), srcSpanStart )
53 import Bag ( consBag )
56 import MachOp ( machRepByteWidth )
62 isForeignImport :: LForeignDecl name -> Bool
63 isForeignImport (L _ (ForeignImport _ _ _ _)) = True
64 isForeignImport _ = False
67 isForeignExport :: LForeignDecl name -> Bool
68 isForeignExport (L _ (ForeignExport _ _ _ _)) = True
69 isForeignExport _ = False
72 %************************************************************************
76 %************************************************************************
79 tcForeignImports :: [LForeignDecl Name] -> TcM ([Id], [LForeignDecl Id])
80 tcForeignImports decls
81 = mapAndUnzipM (wrapLocSndM tcFImport) (filter isForeignImport decls)
83 tcFImport :: ForeignDecl Name -> TcM (Id, ForeignDecl Id)
84 tcFImport fo@(ForeignImport (L loc nm) hs_ty imp_decl isDeprec)
85 = addErrCtxt (foreignDeclCtxt fo) $
86 tcHsSigType (ForSigCtxt nm) hs_ty `thenM` \ sig_ty ->
88 -- drop the foralls before inspecting the structure
89 -- of the foreign type.
90 (_, t_ty) = tcSplitForAllTys sig_ty
91 (arg_tys, res_ty) = tcSplitFunTys t_ty
92 id = mkLocalId nm sig_ty
93 -- Use a LocalId to obey the invariant that locally-defined
94 -- things are LocalIds. However, it does not need zonking,
95 -- (so TcHsSyn.zonkForeignExports ignores it).
97 tcCheckFIType sig_ty arg_tys res_ty imp_decl `thenM` \ imp_decl' ->
98 -- can't use sig_ty here because it :: Type and we need HsType Id
99 -- hence the undefined
100 returnM (id, ForeignImport (L loc id) undefined imp_decl' isDeprec)
104 ------------ Checking types for foreign import ----------------------
106 tcCheckFIType _ arg_tys res_ty (DNImport spec)
107 = checkCg checkDotnet `thenM_`
108 getDOpts `thenM` \ dflags ->
109 checkForeignArgs (isFFIDotnetTy dflags) arg_tys `thenM_`
110 checkForeignRes True{-non IO ok-} (isFFIDotnetTy dflags) res_ty `thenM_`
111 let (DNCallSpec isStatic kind _ _ _ _) = spec in
113 DNMethod | not isStatic ->
115 [] -> addErrTc illegalDNMethodSig
117 | not (isFFIDotnetObjTy (last arg_tys)) -> addErrTc illegalDNMethodSig
118 | otherwise -> returnM ()
119 _ -> returnM ()) `thenM_`
120 returnM (DNImport (withDNTypes spec (map toDNType arg_tys) (toDNType res_ty)))
122 tcCheckFIType sig_ty arg_tys res_ty idecl@(CImport _ _ _ _ (CLabel _))
123 = checkCg checkCOrAsm `thenM_`
124 check (isFFILabelTy sig_ty) (illegalForeignTyErr empty sig_ty) `thenM_`
127 tcCheckFIType sig_ty arg_tys res_ty idecl@(CImport cconv _ _ _ CWrapper)
128 = -- Foreign wrapper (former f.e.d.)
129 -- The type must be of the form ft -> IO (FunPtr ft), where ft is a
130 -- valid foreign type. For legacy reasons ft -> IO (Ptr ft) as well
131 -- as ft -> IO Addr is accepted, too. The use of the latter two forms
132 -- is DEPRECATED, though.
133 checkCg checkCOrAsmOrInterp `thenM_`
134 checkCConv cconv `thenM_`
136 [arg1_ty] -> checkForeignArgs isFFIExternalTy arg1_tys `thenM_`
137 checkForeignRes nonIOok isFFIExportResultTy res1_ty `thenM_`
138 checkForeignRes mustBeIO isFFIDynResultTy res_ty `thenM_`
139 checkFEDArgs arg1_tys
141 (arg1_tys, res1_ty) = tcSplitFunTys arg1_ty
142 other -> addErrTc (illegalForeignTyErr empty sig_ty) ) `thenM_`
145 tcCheckFIType sig_ty arg_tys res_ty idecl@(CImport cconv safety _ _ (CFunction target))
146 | isDynamicTarget target -- Foreign import dynamic
147 = checkCg checkCOrAsmOrInterp `thenM_`
148 checkCConv cconv `thenM_`
149 case arg_tys of -- The first arg must be Ptr, FunPtr, or Addr
151 check False (illegalForeignTyErr empty sig_ty) `thenM_`
154 getDOpts `thenM` \ dflags ->
155 check (isFFIDynArgumentTy arg1_ty)
156 (illegalForeignTyErr argument arg1_ty) `thenM_`
157 checkForeignArgs (isFFIArgumentTy dflags safety) arg_tys `thenM_`
158 checkForeignRes nonIOok (isFFIImportResultTy dflags) res_ty `thenM_`
160 | otherwise -- Normal foreign import
161 = checkCg (checkCOrAsmOrDotNetOrInterp) `thenM_`
162 checkCConv cconv `thenM_`
163 checkCTarget target `thenM_`
164 getDOpts `thenM` \ dflags ->
165 checkForeignArgs (isFFIArgumentTy dflags safety) arg_tys `thenM_`
166 checkForeignRes nonIOok (isFFIImportResultTy dflags) res_ty `thenM_`
169 -- This makes a convenient place to check
170 -- that the C identifier is valid for C
171 checkCTarget (StaticTarget str)
172 = checkCg checkCOrAsmOrDotNetOrInterp `thenM_`
173 check (isCLabelString str) (badCName str)
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 <= 32) err
189 integral_args = sum [ machRepByteWidth rep
190 | (rep,hint) <- map typeMachRepRep 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 :: [LForeignDecl Name]
207 -> TcM (LHsBinds TcId, [LForeignDecl TcId])
208 tcForeignExports decls
209 = foldlM combine (emptyLHsBinds, []) (filter isForeignExport decls)
211 combine (binds, fs) fe =
212 wrapLocSndM tcFExport fe `thenM` \ (b, f) ->
213 returnM (b `consBag` binds, f:fs)
215 tcFExport :: ForeignDecl Name -> TcM (LHsBind Id, ForeignDecl Id)
216 tcFExport fo@(ForeignExport (L loc nm) hs_ty spec isDeprec) =
217 addErrCtxt (foreignDeclCtxt fo) $
219 tcHsSigType (ForSigCtxt nm) hs_ty `thenM` \ sig_ty ->
220 tcCheckSigma (nlHsVar nm) sig_ty `thenM` \ rhs ->
222 tcCheckFEType sig_ty spec `thenM_`
224 -- we're exporting a function, but at a type possibly more
225 -- constrained than its declared/inferred type. Hence the need
226 -- to create a local binding which will call the exported function
227 -- at a particular type (and, maybe, overloading).
229 newUnique `thenM` \ uniq ->
230 getModule `thenM` \ mod ->
232 gnm = mkExternalName uniq mod (mkForeignExportOcc (getOccName nm))
233 Nothing (srcSpanStart loc)
234 id = mkExportedLocalId gnm sig_ty
235 bind = L loc (VarBind id rhs)
237 returnM (bind, ForeignExport (L loc id) undefined spec isDeprec)
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 checkCOrAsm HscC = Nothing
300 checkCOrAsm HscAsm = Nothing
302 = Just (text "requires via-C or native code generation (-fvia-C)")
304 checkCOrAsmOrInterp HscC = Nothing
305 checkCOrAsmOrInterp HscAsm = Nothing
306 checkCOrAsmOrInterp HscInterpreted = Nothing
307 checkCOrAsmOrInterp other
308 = Just (text "requires interpreted, C or native code generation")
310 checkCOrAsmOrDotNetOrInterp HscC = Nothing
311 checkCOrAsmOrDotNetOrInterp HscAsm = Nothing
312 checkCOrAsmOrDotNetOrInterp HscILX = Nothing
313 checkCOrAsmOrDotNetOrInterp HscInterpreted = Nothing
314 checkCOrAsmOrDotNetOrInterp other
315 = Just (text "requires interpreted, C, native or .NET ILX code generation")
318 = getDOpts `thenM` \ dflags ->
319 let hscLang = dopt_HscLang dflags in
321 HscNothing -> returnM ()
323 case check hscLang of
324 Nothing -> returnM ()
325 Just err -> addErrTc (text "Illegal foreign declaration:" <+> err)
331 checkCConv :: CCallConv -> TcM ()
332 checkCConv CCallConv = return ()
334 checkCConv StdCallConv = return ()
336 checkCConv StdCallConv = addErrTc (text "calling convention not supported on this architecture: stdcall")
343 check :: Bool -> Message -> TcM ()
344 check True _ = returnM ()
345 check _ the_err = addErrTc the_err
347 illegalForeignTyErr arg_or_res ty
348 = hang (hsep [ptext SLIT("Unacceptable"), arg_or_res,
349 ptext SLIT("type in foreign declaration:")])
352 -- Used for 'arg_or_res' argument to illegalForeignTyErr
353 argument = text "argument"
354 result = text "result"
356 badCName :: CLabelString -> Message
358 = sep [quotes (ppr target) <+> ptext SLIT("is not a valid C identifier")]
361 = hang (ptext SLIT("When checking declaration:"))
365 = ptext SLIT("'This pointer' expected as last argument")