https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58909
--- Comment #16 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Are those weak refs from libstdc++.a objects or from the user *.o files? If the former, perhaps we could declare some libstdc++ APIs (related to threading) as requiring linking of -lpthread and made them non-weak in libstdc++.a. I don't really see how can one reproduce this on Fedora/RHEL/CentOS where libpthread.a contains a single libpthread.o and therefore it is either you link no thread support at all, or link it completely.
