Incorrect test for event.udata being intptr_t

[sludin]

On OS X with gcc == i686-apple-darwin11-llvm-gcc-4.2 (GCC) 4.2.1 the following code check for event.udata being an intptr_t:

---

#include <sys/types.h>
#include <sys/event.h>
#include <sys/time.h>

int
main ()
{
  struct kevent event;
  event.udata = (intptr_t*)(&event);
  ;
  return 0;
}

---

I believe the proper check should be:

event.udata = (intptr_t)(&event);

Or something similar. The current check as written passes when event.udata us a void*.

In EventPoll_kqueue.cc the following #ifdef block is used:

#ifdef KEVENT_UDATA_INTPTR_T
# define PTR_TO_UDATA(X) (reinterpret_cast<intptr_t>(X))
#else // !KEVENT_UDATA_INTPTR_T
# define PTR_TO_UDATA(X) (X)
#endif // !KEVENT_UDATA_INTPTR_T

Since KEVENT_UDATA_INTPTR_T is set to 1 by the configure check, the:

PTR_TO_UDATA(user_data)

in update_event becomes:

reinterpret_cast<intptr_t>(user_data)

And results in the following error:

error: invalid conversion from ‘intptr_t’ to ‘void*’

[tatsuhiro-t]

Thank you for pointing out. Fixed in the master branch.

[sludin]

Fix is in, but the onion continues to peel back. The problem now comes from the difference between the C cast rules and the C++ cast rules. When compiled with gcc the following succeeds with a warning:

event.udata = (intptr_t)(&event);

Under g++ it gets an error. Should the test be run instead with ac_fn_cxx_try_compile? I am not sure the current test is getting the information you want.

[sludin]

The following diff on configure.ac might do it:

sludin@sfo-mppcg ~/src/spdylay]$ git diff
diff --git a/configure.ac b/configure.ac
index d4bac5a..ee1b176 100644
--- a/configure.ac
+++ b/configure.ac
@@ -169,6 +169,7 @@ AM_CONDITIONAL([HAVE_EPOLL], [ test "x${have_epoll}" = "xyes" ])
 AC_CHECK_FUNCS([kqueue], [have_kqueue=yes])
 AM_CONDITIONAL([HAVE_KQUEUE], [test "x${have_kqueue}" = "xyes"])

+AC_LANG_PUSH(C++)
 AC_MSG_CHECKING([whether struct kevent.udata is intptr_t])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 #include <sys/types.h>
@@ -185,6 +186,7 @@ if test "x$kevent_udata_intptr_t" = "xyes"; then
   AC_DEFINE([KEVENT_UDATA_INTPTR_T], [1],
             [Define to 1 if struct kevent.udata is intptr_t])
 fi
+AC_LANG_POP()

 if test "x$maintainer_mode" != "xno"; then
     CFLAGS="$CFLAGS -Wall -Wextra -Werror"

[tatsuhiro-t]

Thank you! Merged and pushed.