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| author | Simon Marlow <marlowsd@gmail.com> | 2011-11-24 14:04:23 +0000 |
|---|---|---|
| committer | Simon Marlow <marlowsd@gmail.com> | 2011-11-24 14:56:31 +0000 |
| commit | c6b0fd62fc715aa6c666eb8afe09073ac7b87a83 (patch) | |
| tree | 3beaf6decace8519413038db29824878c00eb776 /compiler/typecheck | |
| parent | 1eedbc6b9e7f9f04087b4026fa702b969999bb90 (diff) | |
| download | haskell-c6b0fd62fc715aa6c666eb8afe09073ac7b87a83.tar.gz | |
Relax the restriction on using abstract newtypes in FFI declarations.
Given the high impact of this change, we decided to back off and make
abstract newtypes give a warning for one release, before we make it an
error in 7.6.1.
Codec/Compression/Zlib/Stream.hsc:884:1:
Warning: newtype `CInt' is used in an FFI declaration,
but its constructor is not in scope.
This will become an error in GHC 7.6.1.
When checking declaration:
foreign import ccall unsafe "static zlib.h deflate" c_deflate
:: StreamState -> CInt -> IO CInt
Diffstat (limited to 'compiler/typecheck')
| -rw-r--r-- | compiler/typecheck/TcForeign.lhs | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/compiler/typecheck/TcForeign.lhs b/compiler/typecheck/TcForeign.lhs index 886b84d22e..5a4bf776fa 100644 --- a/compiler/typecheck/TcForeign.lhs +++ b/compiler/typecheck/TcForeign.lhs @@ -121,17 +121,29 @@ normaliseFfiType' env ty0 = go [] ty0 panic "normaliseFfiType': Got more GREs than expected" _ -> return False - if newtypeOK - then do let nt_co = mkAxInstCo (newTyConCo tc) tys - add_co nt_co rec_nts' nt_rhs - else children_only + when (not newtypeOK) $ + -- later: stop_here + addWarnTc (ptext (sLit "newtype") <+> quotes (ppr tc) <+> + ptext (sLit "is used in an FFI declaration,") $$ + ptext (sLit "but its constructor is not in scope.") $$ + ptext (sLit "This will become an error in GHC 7.6.1.")) + + let nt_co = mkAxInstCo (newTyConCo tc) tys + add_co nt_co rec_nts' nt_rhs + | isFamilyTyCon tc -- Expand open tycons , (co, ty) <- normaliseTcApp env tc tys , not (isReflCo co) = add_co co rec_nts ty + | otherwise - = children_only + = return (mkReflCo ty, ty) + -- If we have reached an ordinary (non-newtype) type constructor, + -- we are done. Note that we don't need to normalise the arguments, + -- because whether an FFI type is legal or not depends only on + -- the top-level type constructor (e.g. "Ptr a" is valid for all a). where + children_only = do xs <- mapM (go rec_nts) tys let (cos, tys') = unzip xs return (mkTyConAppCo tc cos, mkTyConApp tc tys') |