https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82629
--- Comment #3 from Thorsten Kurth <thorstenkurth at me dot com> --- One more thing, In the test case I send, please change the $(XPPFLAGS) in the main.x target compilation to $(CXXFLAGS), so that -fopenmp is used at link time also. However, that does not solve the problem but it makes the Makefile more correct (the XPPFLAGS was a remnant from something I tried out earlier). Sorry for that. Best Regards Thorsten Kurth