>If you use them in a way that requires an object with storage (e.g. >take their address or bind a reference to them) then yes. See >https://gcc.gnu.org/wiki/VerboseDiagnostics#missing_static_const_definition Thanks for the link. That fixed the missing symbol error. >Both your errors are linker errors due to missing symbols, but the >causes are entirely different. The only way they could have the same >cause is if you're forgetting to link to the file that contains those >symbols. The typeinfo error has now gone. I realise that is surprising, but I'm happy with the result. Thanks again for your help. On Thu, Dec 13, 2018 at 4:04 PM Jonathan Wakely <jwakely.gcc@xxxxxxxxx> wrote: > On Thu, 13 Dec 2018 at 16:01, David Aldrich > <david.aldrich.ntml@xxxxxxxxx> wrote: > > > > Thank you Jonathan for your reply. > > > > The class does indeed contain a virtual method, but that method is > defined. > > So I don't think that is the problem. > > > > I've disabled the loading of the troublesome .so library file and now > > another library is refusing to load. I am wondering whether this new > > problem is related and so would like to ask you about it. The error > > message now is: > > > > undefined symbol: _ZN8StarLibs7LinkSim2NR6NRDmrs18MAX_NUM_CDM_GROUPSE ( > > StarLibs::LinkSim::NR::NRDmrs::MAX_NUM_CDM_GROUPS ) > > > > This symbol is a constant defined in a class's header (.h file): > > > > namespace StarLibs { > > namespace LinkSim { > > namespace NR > > { > > class NRDmrs > > { > > public: > > > > static const unsigned DMSR_MAX_NSCID = 1; > > static const unsigned MAX_NUM_CDM_GROUPS = 3; > > > > This takes me back to my earlier comment. In C++14, do I need to declare > > such constants in a .cpp source file in order to give them storage and so > > make them load? > > If you use them in a way that requires an object with storage (e.g. > take their address or bind a reference to them) then yes. See > https://gcc.gnu.org/wiki/VerboseDiagnostics#missing_static_const_definition > > Both your errors are linker errors due to missing symbols, but the > causes are entirely different. The only way they could have the same > cause is if you're forgetting to link to the file that contains those > symbols. >
