suppressing a warning, what's its name?

[Alexy Khrabrov]

Greetings -- I'm getting many warnings like the following one,
when compiling CORBA C++ implementations:

MMS_EntryImpl.C: In method `MMS_EntryImpl::MMS_EntryImpl(PortableServer::POA *, const char *)':
MMS_EntryImpl.C:48: warning: choosing `PortableServer::ObjectId_var::operator PortableServer::ObjectId &()' over `PortableServer::ObjectId_var::operator const PortableServer::ObjectId &() const'
MMS_EntryImpl.C:48: warning:   for conversion from `PortableServer::ObjectId_var' to `const PortableServer::ObjectId &'
MMS_EntryImpl.C:48: warning:   because conversion sequence for the argument is bette

I've tried -Wno-conversion, but that's not it.  Anybody knows whether that 
warning has a name?

Cheers,
Alexy