[Bug c++/51188] invalid static_cast from type 'XBase' to type 'int'

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51188

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> 2011-11-17 19:32:13 UTC ---
It looks like the sorted fields code in lookup_field_1 needs to handle
using_decl like the unsorted fields code does.  I think this will also fix
PR51141 (instead of the patch you already posted).