2010-01-27 Richard Guenther <rguenther@suse.de>

	PR libstdc++/42832
	* include/std/functional (function<>::swap): Perform bytewise
	swap of _M_functor.
	* include/tr1/functional (function<>::swap): Likewise.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@156290 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 10 insertions, 3 deletions

diff --git a/libstdc++-v3/include/tr1/functional b/libstdc++-v3/include/tr1/functional
index 4825509aed7..2052f885de8 100644
--- a/libstdc++-v3/include/tr1/functional
+++ b/libstdc++-v3/include/tr1/functional
@@ -1904,9 +1904,16 @@ namespace tr1
        */
       void swap(function& __x)
       {
-	_Any_data __old_functor = _M_functor;
-	_M_functor = __x._M_functor;
-	__x._M_functor = __old_functor;
+        /* We cannot perform direct assignments of the _M_functor
+	   parts as they are of type _Any_data and have a different
+	   dynamic type.  Doing so would violate type-based aliasing
+	   rules and lead to spurious miscompilations.
+	   Instead perform a bytewise exchange of the memory of
+	   both POD objects.
+	   ???  A wordwise exchange honoring alignment of _M_functor
+	   would be more efficient.  See PR42845.  */
+	for (unsigned i = 0; i < sizeof (_M_functor._M_pod_data); ++i)
+	  std::swap (_M_functor._M_pod_data[i], __x._M_functor._M_pod_data[i]);
 	_Manager_type __old_manager = _M_manager;
 	_M_manager = __x._M_manager;
 	__x._M_manager = __old_manager;