Two files, CarpetX/src/driver.cxx at L22 and .../boundaries.cxx at L9, include <omp.h> without checking whether _OPENMP is defined, unlike other CarpetX files such as CarpetX/src/schedule.cxx at L19. This always includes OpenMP when compiling CarpetX, which can cause compile time failure for systems that do not provide OpenMP, even with OpenMP disabled.

This bug was encountered when compiling CarpetX while OpenMP is not enabled with macOS Clang, which does not provide OpenMP by default.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2946/carpetx-includes-when-openmp-is-not