As of git hash 0721ab29 "Remove C++ math work-arounds" of cactus at least gcc 6 must be present on a system to have full C++11 support (for both gcc and icc builds).

The newest gcc version on bethe is 5.2 and thus compilation fails with:

/home/rhaas/ET_Next/arrangements/CactusTest/TestMath/src/math_cc.cc(220): error: more than one instance of overloaded function "isinf" matches the argument list:
            function "isinf(double)"
            function "std::isinf(double)"
            argument types are: (double)
    i = isinf(1.0);

Since bethe is a private system that is apparently no longer used, I would retire it from simfactory before the release.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2607/et-cannot-be-compiled-on-caltech-bethe