Re: [C2hs] How to access inside a union using #set

2 Apr 2009


      On 02.04.2009, at 09:42, Mark Wassell wrote:
...
Hello,
I have the following:
...
typedef struct tagINPUT {
DWORD type;
union {MOUSEINPUT mi;
          KEYBDINPUT ki;
          HARDWAREINPUT hi;
         };
}INPUT, *PINPUT;
Hi Marc,
this is probably because c2hs does not (yet) support the 'Unnamed  
fields' extension (http://gcc.gnu.org/onlinedocs/gcc-4.3.3/gcc/Unnamed-Fields.html 
).

This works fine:
...
module Test where
#c
typedef struct {
  union { int x;  } u;
} S1;
#endc
test  = {#set S1.u.x #}
but this won't work:
...
module Test where
#c
typedef struct {
  union { int x;  };
} S2;
#endc
test  = {#set S2.x #}
If you care about a fix, please file a bug at http://hackage.haskell.org/trac/c2hs/wiki

cheers, benedikt
...
and in a chs file:
sendChar :: HWND -> Char -> IO ()
sendChar win ch = do
                    allocaBytes ( {#sizeof INPUT#}) $ \ptr ->
                      {#set INPUT.type #} ptr 0
                      {#set INPUT.ki.wVk #} ptr 0
                      {#set INPUT.ki.dwFlags #} ptr 0
c2hs comes up with
Test1.chs:27: (column 37) [ERROR]  >>> error
Unknown member name!
The structure has no member called `ki'.  The structure is defined at
("sendinput.h",35,9).
Test1.chs:26: (column 37) [ERROR]  >>> error
Unknown member name!
The structure has no member called `ki'.  The structure is defined at
("sendinput.h",35,9).
How do I address fields inside the union?
Cheers
Mark
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Re: [C2hs] How to access inside a union using #set

Benedikt Huber