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 "HsVersions.h"
25 import TcHsType ( tcHsSigType, UserTypeCtxt(..) )
26 import TcExpr ( tcPolyExpr )
28 import ForeignCall ( CCallConv(..) )
29 import ErrUtils ( Message )
30 import Id ( Id, mkLocalId, mkExportedLocalId )
32 import Type ( typePrimRep )
33 import SMRep ( argMachRep, primRepToCgRep, primRepHint )
35 import OccName ( mkForeignExportOcc )
36 import Name ( Name, NamedThing(..), mkExternalName )
37 import TcType ( Type, tcSplitFunTys, tcSplitTyConApp_maybe,
38 tcSplitForAllTys, tcSplitIOType_maybe,
39 isFFIArgumentTy, isFFIImportResultTy,
40 isFFIExportResultTy, isFFILabelTy,
41 isFFIExternalTy, isFFIDynArgumentTy,
42 isFFIDynResultTy, isFFIDotnetTy, isFFIDotnetObjTy,
45 import ForeignCall ( CExportSpec(..), CCallTarget(..),
46 CLabelString, isCLabelString,
47 isDynamicTarget, withDNTypes, DNKind(..), DNCallSpec(..) )
48 import PrelNames ( hasKey, ioTyConKey )
49 import DynFlags ( DynFlags(..), HscTarget(..) )
51 import SrcLoc ( Located(..), srcSpanStart )
52 import Bag ( consBag )
55 import MachOp ( machRepByteWidth, MachHint(FloatHint) )
61 isForeignImport :: LForeignDecl name -> Bool
62 isForeignImport (L _ (ForeignImport _ _ _)) = True
63 isForeignImport _ = False
66 isForeignExport :: LForeignDecl name -> Bool
67 isForeignExport (L _ (ForeignExport _ _ _)) = True
68 isForeignExport _ = False
71 %************************************************************************
75 %************************************************************************
78 tcForeignImports :: [LForeignDecl Name] -> TcM ([Id], [LForeignDecl Id])
79 tcForeignImports decls
80 = mapAndUnzipM (wrapLocSndM tcFImport) (filter isForeignImport decls)
82 tcFImport :: ForeignDecl Name -> TcM (Id, ForeignDecl Id)
83 tcFImport fo@(ForeignImport (L loc nm) hs_ty imp_decl)
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 (L loc id) undefined imp_decl')
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_`
133 checkCConv cconv `thenM_`
135 [arg1_ty] -> checkForeignArgs isFFIExternalTy arg1_tys `thenM_`
136 checkForeignRes nonIOok isFFIExportResultTy res1_ty `thenM_`
137 checkForeignRes mustBeIO isFFIDynResultTy res_ty `thenM_`
138 checkFEDArgs arg1_tys
140 (arg1_tys, res1_ty) = tcSplitFunTys arg1_ty
141 other -> addErrTc (illegalForeignTyErr empty sig_ty) ) `thenM_`
144 tcCheckFIType sig_ty arg_tys res_ty idecl@(CImport cconv safety _ _ (CFunction target))
145 | isDynamicTarget target -- Foreign import dynamic
146 = checkCg checkCOrAsmOrInterp `thenM_`
147 checkCConv cconv `thenM_`
148 case arg_tys of -- The first arg must be Ptr, FunPtr, or Addr
150 check False (illegalForeignTyErr empty sig_ty) `thenM_`
153 getDOpts `thenM` \ dflags ->
154 check (isFFIDynArgumentTy arg1_ty)
155 (illegalForeignTyErr argument arg1_ty) `thenM_`
156 checkForeignArgs (isFFIArgumentTy dflags safety) arg_tys `thenM_`
157 checkForeignRes nonIOok (isFFIImportResultTy dflags) res_ty `thenM_`
159 | otherwise -- Normal foreign import
160 = checkCg (checkCOrAsmOrDotNetOrInterp) `thenM_`
161 checkCConv cconv `thenM_`
162 checkCTarget target `thenM_`
163 getDOpts `thenM` \ dflags ->
164 checkForeignArgs (isFFIArgumentTy dflags safety) arg_tys `thenM_`
165 checkForeignRes nonIOok (isFFIImportResultTy dflags) res_ty `thenM_`
168 -- This makes a convenient place to check
169 -- that the C identifier is valid for C
170 checkCTarget (StaticTarget str)
171 = checkCg checkCOrAsmOrDotNetOrInterp `thenM_`
172 check (isCLabelString str) (badCName str)
175 On an Alpha, with foreign export dynamic, due to a giant hack when
176 building adjustor thunks, we only allow 4 integer arguments with
177 foreign export dynamic (i.e., 32 bytes of arguments after padding each
178 argument to a quadword, excluding floating-point arguments).
180 The check is needed for both via-C and native-code routes
183 #include "nativeGen/NCG.h"
184 #if alpha_TARGET_ARCH
186 = check (integral_args <= 32) err
188 integral_args = sum [ (machRepByteWidth . argMachRep . primRepToCgRep) prim_rep
189 | prim_rep <- map typePrimRep arg_tys,
190 primRepHint prim_rep /= FloatHint ]
191 err = ptext SLIT("On Alpha, I can only handle 32 bytes of non-floating-point arguments to foreign export dynamic")
193 checkFEDArgs arg_tys = returnM ()
198 %************************************************************************
202 %************************************************************************
205 tcForeignExports :: [LForeignDecl Name]
206 -> TcM (LHsBinds TcId, [LForeignDecl TcId])
207 tcForeignExports decls
208 = foldlM combine (emptyLHsBinds, []) (filter isForeignExport decls)
210 combine (binds, fs) fe =
211 wrapLocSndM tcFExport fe `thenM` \ (b, f) ->
212 returnM (b `consBag` binds, f:fs)
214 tcFExport :: ForeignDecl Name -> TcM (LHsBind Id, ForeignDecl Id)
215 tcFExport fo@(ForeignExport (L loc nm) hs_ty spec) =
216 addErrCtxt (foreignDeclCtxt fo) $
218 tcHsSigType (ForSigCtxt nm) hs_ty `thenM` \ sig_ty ->
219 tcPolyExpr (nlHsVar nm) sig_ty `thenM` \ rhs ->
221 tcCheckFEType sig_ty spec `thenM_`
223 -- we're exporting a function, but at a type possibly more
224 -- constrained than its declared/inferred type. Hence the need
225 -- to create a local binding which will call the exported function
226 -- at a particular type (and, maybe, overloading).
228 newUnique `thenM` \ uniq ->
229 getModule `thenM` \ mod ->
231 gnm = mkExternalName uniq mod (mkForeignExportOcc (getOccName nm))
232 Nothing (srcSpanStart loc)
233 id = mkExportedLocalId gnm sig_ty
234 bind = L loc (VarBind id rhs)
236 returnM (bind, ForeignExport (L loc id) undefined spec)
239 ------------ Checking argument types for foreign export ----------------------
242 tcCheckFEType sig_ty (CExport (CExportStatic str _))
243 = check (isCLabelString str) (badCName str) `thenM_`
244 checkForeignArgs isFFIExternalTy arg_tys `thenM_`
245 checkForeignRes nonIOok isFFIExportResultTy res_ty
247 -- Drop the foralls before inspecting n
248 -- the structure of the foreign type.
249 (_, t_ty) = tcSplitForAllTys sig_ty
250 (arg_tys, res_ty) = tcSplitFunTys t_ty
255 %************************************************************************
257 \subsection{Miscellaneous}
259 %************************************************************************
262 ------------ Checking argument types for foreign import ----------------------
263 checkForeignArgs :: (Type -> Bool) -> [Type] -> TcM ()
264 checkForeignArgs pred tys
265 = mappM go tys `thenM_`
268 go ty = check (pred ty) (illegalForeignTyErr argument ty)
270 ------------ Checking result types for foreign calls ----------------------
271 -- Check that the type has the form
272 -- (IO t) or (t) , and that t satisfies the given predicate.
274 checkForeignRes :: Bool -> (Type -> Bool) -> Type -> TcM ()
279 checkForeignRes non_io_result_ok pred_res_ty ty
280 -- (IO t) is ok, and so is any newtype wrapping thereof
281 | Just (io, res_ty) <- tcSplitIOType_maybe 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 target = hscTarget dflags in
321 HscNothing -> returnM ()
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")