Libmesh TIMPI Communicator Error and Warning

[kdang62]

Hello, I am seeing this warning message that is causing my program that uses Libmesh to error out:

./Libmesh/include/timpi/communicator.h:1217:15: warning: inline function ‘void TIMPI::Communicator::broadcast(T&, unsigned int, bool) const [with T = std::__cxx11::basic_string<char>]’ used but never defined 1217 | inline void broadcast(T & data, const unsigned int root_id=0,

Has anyone dealt with this before? The error I end up getting in my terminal is undefined symbol: _ZNK5TIMPI12Communicator9broadcastINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEEEvRT_jb

I saw a discussion about a similar issue in 2023 but no solution was posted. Thank you in advance!

[roystgnr]

Demangler says the undefined symbol is void TIMPI::Communicator::broadcast<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&, unsigned int, bool) const, which simplifies to void TIMPI::Communicator::broadcast<string>(string&, unsigned int, bool) const, but that's defined in parallel_implementation.h line 1722.

Except ... it's defined in communicator.h line 1324, not line 1217 as in your error message. What versions of libMesh and TIMPI are you building against?

[kdang62]

Thank you for your response. I am using libMesh 1.7.1

[roystgnr]

Well, that's annoying. Old enough to leave me wondering whether we've had some bug fix since, but new enough that I don't see anything that looks relevant in the diffs or git logs.

It looks as if something is seeing the generic broadcast(T&,etc) declaration in communicator.h, but not seeing the specific broadcast(string&,etc) specialization in parallel_communicator_specializations, but the latter file gets included inside communicator.h.

I suppose if you configured without MPI then we hide that specialization, expecting the generic "do-nothing" serial broadcast to cover it ... did you configure without MPI? We might have had a fix at some point relevant for that case.