Warn about a bug in memcpy_ with g++ 4.2 on Debian for IA-32.

	* mln/data/memcpy_.hh (mln::data::impl::memcpy_): Here.

git-svn-id: https://svn.lrde.epita.fr/svn/oln/trunk@4608 4aad255d-cdde-0310-9447-f3009e2ae8c0

milena/ChangeLog

+2009-10-06  Roland Levillain  <roland@lrde.epita.fr>
+
+	Warn about a bug in memcpy_ with g++ 4.2 on Debian for IA-32.
+
+	* mln/data/memcpy_.hh (mln::data::impl::memcpy_): Here.
+
 2009-10-02  Guillaume Lazzara  <z@lrde.epita.fr>
 	Small fixes in documentation.

milena/mln/data/memcpy_.hh

-// Copyright (C) 2007, 2008, 2009 EPITA Research and Development Laboratory (LRDE)
+// Copyright (C) 2007, 2008, 2009 EPITA Research and Development
+// Laboratory (LRDE)
 //
 // This file is part of Olena.
 //
@@ -88,6 +89,16 @@ namespace mln
 	  return;
 	}
 
+	/* FIXME: Careful, the code generated for this function by g++
+	   4.2 with high a optimization level (`-O3') and without
+	   `-fno-strict-aliasing' might be wrong (at least with
+	   Debian's g++ 4.2 on IA-32)!  Note that Debian's g++ 4.0,
+	   4.1, 4.3 and 4.4 are fine.  */
+#if defined(__GNUC__) && defined(__GNUC_MINOR__)
+# if __GNUC__ == 4 && __GNUC_MINOR__ == 2
+#  warning The code generated by g++ 4.2 on Debian GNU/Linux 5.0 for IA-32 for this function might be wrong.
+# endif
+#endif
 	if (sizeof(mln_value(Id)) == 1)
 	{
 	  std::memcpy((void*) (&dest.val()), // violent casts