[C2hs] preprocessor questoin

[Axel Simon]

Hi Manuel,

I am trying to use the conditional compilation feature of the latest release of c2hs. My 
code looks something like this:

#include <gtk/gtkversion.h>

#if GTK_CHECK_VERSION(2,2,0)

treeStoreRemove :: (TreeStoreClass ts) => ts -> TreeIter -> IO Bool
treeStoreRemove ts ti = liftM toBool $ 
  {#call tree_store_remove#} (toTreeStore ts) ti

#else

treeStoreRemove :: (TreeStoreClass ts) => ts -> TreeIter -> IO ()
treeStoreRemove ts ti = {#call tree_store_remove#} (toTreeStore ts) ti

#endif

First of all there is a but that a newline in front of each # is lost so that cpp 
conditionals wind up on the line above (which was of course a comment, so passed 
unnoticed...).

But more important is that the test yields true but c2hs compiles the second 
version. The created .h file looks like this:

#include "gtk/gtktreestore.h"
#include <gtk/gtkversion.h>
#if GTK_CHECK_VERSION(2,2,0)
struct C2HS_COND_SENTRY_1;
#else
#endif

I don't know how the mechanism is to work but I though that with C2HS_COND_SENTRY_1 
defined code segment #1 would be inserted and similar for a C2HS_COND_SENTRY_2 which is 
kind of missing. So I tried to split the two cases into two single if statements:

#if GTK_CHECK_VERSION(2,2,0)

treeStoreRemove :: (TreeStoreClass ts) => ts -> TreeIter -> IO Bool
treeStoreRemove ts ti = liftM toBool $ 
  {#call tree_store_remove#} (toTreeStore ts) ti

#endif

#if !GTK_CHECK_VERSION(2,2,0)

treeStoreRemove :: (TreeStoreClass ts) => ts -> TreeIter -> IO ()
treeStoreRemove ts ti = {#call tree_store_remove#} (toTreeStore ts) ti

#endif

This yields:

#include "gtk/gtktreestore.h"
#include <gtk/gtkversion.h>
#if GTK_CHECK_VERSION(2,2,0)
struct C2HS_COND_SENTRY_1;
#endif
#if !GTK_CHECK_VERSION(2,2,0)
struct C2HS_COND_SENTRY_2;
#endif

...and not not a single version of treeStoreRemove winds up in the resulting file.

Am I doing something wrong or is c2hs wrong?

Thanks,
Axel.