Re: [Python-Dev] mingw32 and gc-header weirdness

July 22, 2009

      Hi,
...
I used mingw32 (stable distro) to build the psyco extension
on top of standard python2.6, built with Visual Studio,
and got weird crashes.
The reason is in objimpl.h:
typedef union _gc_head {
  struct {
      union _gc_head *gc_next;
      union _gc_head *gc_prev;
      Py_ssize_t gc_refs;
  } gc;
  long double dummy;  /* force worst-case alignment */
} PyGC_Head;
Mingw32 behaves funny here. The size of long double is 12 !
The size of long double is also 12 under 32-bit Linux. Perhaps mingw disagrees
with Visual Studio on some ABI subtleties (is it expected? is mingw supposed to
be ABI-compatible with Visual Studio? if yes, you may report a bug to them :-)).

Regards

Antoine.

Re: [Python-Dev] mingw32 and gc-header weirdness

Antoine Pitrou