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 ErrUtils ( Message )
30 import Id ( Id, mkLocalId, mkExportedLocalId )
32 import PrimRep ( getPrimRepSize, isFloatingRep )
33 import Type ( typePrimRep )
35 import OccName ( mkForeignExportOcc )
36 import Name ( Name, NamedThing(..), mkExternalName )
37 import TcType ( Type, tcSplitFunTys, tcSplitTyConApp_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 CmdLineOpts ( dopt_HscLang, HscLang(..) )
51 import SrcLoc ( Located(..), srcSpanStart )
52 import Bag ( consBag )
55 import MachOp ( machRepByteWidth )
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 isDeprec)
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' isDeprec)
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 (checkCOrAsmOrDotNetOrInterp) `thenM_`
159 checkCTarget target `thenM_`
160 getDOpts `thenM` \ dflags ->
161 checkForeignArgs (isFFIArgumentTy dflags safety) arg_tys `thenM_`
162 checkForeignRes nonIOok (isFFIImportResultTy dflags) res_ty `thenM_`
165 -- This makes a convenient place to check
166 -- that the C identifier is valid for C
167 checkCTarget (StaticTarget str)
168 = checkCg checkCOrAsmOrDotNetOrInterp `thenM_`
169 check (isCLabelString str) (badCName str)
172 On an Alpha, with foreign export dynamic, due to a giant hack when
173 building adjustor thunks, we only allow 4 integer arguments with
174 foreign export dynamic (i.e., 32 bytes of arguments after padding each
175 argument to a quadword, excluding floating-point arguments).
177 The check is needed for both via-C and native-code routes
180 #include "nativeGen/NCG.h"
181 #if alpha_TARGET_ARCH
183 = check (integral_args <= 32) err
185 integral_args = sum [ machRepByteWidth rep
186 | (rep,hint) <- map typeMachRepRep arg_tys,
188 err = ptext SLIT("On Alpha, I can only handle 4 non-floating-point arguments to foreign export dynamic")
190 checkFEDArgs arg_tys = returnM ()
195 %************************************************************************
199 %************************************************************************
202 tcForeignExports :: [LForeignDecl Name]
203 -> TcM (LHsBinds TcId, [LForeignDecl TcId])
204 tcForeignExports decls
205 = foldlM combine (emptyLHsBinds, []) (filter isForeignExport decls)
207 combine (binds, fs) fe =
208 wrapLocSndM tcFExport fe `thenM` \ (b, f) ->
209 returnM (b `consBag` binds, f:fs)
211 tcFExport :: ForeignDecl Name -> TcM (LHsBind Id, ForeignDecl Id)
212 tcFExport fo@(ForeignExport (L loc nm) hs_ty spec isDeprec) =
213 addErrCtxt (foreignDeclCtxt fo) $
215 tcHsSigType (ForSigCtxt nm) hs_ty `thenM` \ sig_ty ->
216 tcCheckSigma (nlHsVar 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))
229 Nothing (srcSpanStart loc)
230 id = mkExportedLocalId gnm sig_ty
231 bind = L loc (VarBind id rhs)
233 returnM (bind, ForeignExport (L loc id) undefined spec isDeprec)
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")