[Bug libstdc++/38477] [strict-aliasing] warning message contains compiler-generated symbols

["rguenth at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #1 from rguenth at gcc dot gnu dot org  2008-12-10 17:37 -------
Note that the reason the diagnostic happens is either a bug in libstdc++ or
the points-to solver or the TBAA pruning in the points-to solver.

In the end we access the object 'ctx' via a pointer of type
const struct _Rb_tree_node *.  So the question is if anywhere in 'ctx' there
is such a struct.

It seems to access the _M_t._M_impl._M_header field which is a
_Rb_tree_node_base
but I cannot see a _Rb_tree_node object in it.  Instead _Rb_tree_node is
derived
from _Rb_tree_node_base and adds a _M_value_field.  But accessing this via
this path in

        struct _Rb_tree_impl : public _Node_allocator
        {
          _Key_compare          _M_key_compare;
          _Rb_tree_node_base    _M_header;
          size_type             _M_node_count;

certainly violates aliasing rules.  I do not see what _Rb_tree_impl::_S_value
wants to access.  There seems to be nothing there?


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c++                         |libstdc++
           Keywords|                            |diagnostic


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38477