CTYPE pragma on newtype is ignored

User's guide includes an example where a CTYPE pragma is used for a newtype.

newtype {-# CTYPE            "useconds_t" #-} T = ...

However, in the following program, the CTYPE pragma seems to be ignored:

{-# LANGUAGE CApiFFI #-}
import Foreign.Ptr

foreign import capi unsafe "sys/socket.h CMSG_DATA"
  c_CMSG_DATA :: Ptr Cmsg -> Ptr a
newtype {-# CTYPE "sys/socket.h" "struct cmsghdr" #-} Cmsg = Cmsg ()

main = return ()

Save this as capi.hs, then compile it like:

ghc capi.hs -fforce-recomp -keep-tmp-files -tmpdir .

Then GHC creates a C file:

#define IN_STG_CODE 0
#include "Rts.h"
#include "Stg.h"
#ifdef __cplusplus
extern "C" {
#endif
#include <sys/socket.h>
void* ghczuwrapperZC0ZCmainZCMainZCCMSGzuDATA(void* a1) {return CMSG_DATA(a1);}
#ifdef __cplusplus
}
#endif

The argument type of the wrapper function is void *, but it should be struct cmsghdr *.

If I replace newtype with data in capi.hs, the wrapper function gets the correct type.

I can see this problem in HEAD and in 7.6.3.

Trac metadata

Trac field	Value
Version	7.6.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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