#10505: more specific types in the generated *_stub.h files -------------------------------------+------------------------------------- Reporter: imz | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (FFI) | Version: 7.6.1 Resolution: | Keywords: Operating System: Linux | Architecture: Type of failure: Other | Unknown/Multiple Blocked By: | Test Case: Related Tickets: #2979, #8222 | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Description changed by imz: Old description:

Having a declaration like:

{{{#!hs foreign export ccall "respond" respond :: CWString -> IO CWString }}}

all the types in the corresponding `_stub.h` are `HsPtr`.

Wouldn't it be possible to write more specific types reflecting my expectations, i.e., `wchar_t *`?

It would be nice in order to signal automatically to the C code which uses the Haskell functions that the types of the Haskell functions changed. In simple cases, one could simply include the stub.h, and get automatically an error if the C code doesn't match the new types.

I've tried using a CTYPE pragma (cf. #2979 , #8222 ) on a newtype to get such results:

{{{#!hs newtype {-# CTYPE "wchar_t *" #-} CWString' = CWString' CWString foreign export ccall "respond" respond :: CWString' -> IO CWString }}}

but that still produces `HsPtr`. (Well, I see, the CTYPE pragma was mostly intended for imports rather than exports.)

New description: Having a declaration like: {{{#!hs foreign export ccall "respond" respond :: CWString -> IO CWString }}} all the types in the corresponding `_stub.h` are `HsPtr`. Wouldn't it be possible to write more specific types reflecting my expectations, i.e., `wchar_t *`? It would be nice in order to signal automatically to the C code which uses the Haskell functions that the types of the Haskell functions changed. In simple cases, one could simply include the stub.h, and get automatically an error if the C code doesn't match the new types. I've tried using a CTYPE pragma (cf. #2979 , #8222 , and https://mail.haskell.org/pipermail/haskell/2012-February/023155.html ) on a newtype to get such results: {{{#!hs newtype {-# CTYPE "wchar_t *" #-} CWString' = CWString' CWString foreign export ccall "respond" respond :: CWString' -> IO CWString }}} but that still produces `HsPtr`. (Well, I see, the CTYPE pragma was mostly intended for imports rather than exports.) -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10505#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler