In this CI run (linux-clang-avg): https://gitlab.com/petsc/petsc/-/jobs/1260342204 The compile fails building a C++ file, demangle.cxx. It fails at the first line, including <petsc/private/petscimpl.h>, down in petscsystypes.h. It bombs during the definition of complex because it looks like the compiler is not defining __cplusplus, and thus takes the wrong branch. Is this what is happening? I cannot access this machine. Thanks, Matt -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>