Comment (by Roland Haas):

My biggest worry with Spac is that, unless the cluster’s module system is also based on Spac, it is often hard to integrate Spac generated packages with the cluster ones. I realize that one can often just build everything using Spac incl. MPI etc. but am not sure how confident I am in this always providing a good solution. I expect it will do somewhat poorly on clusters with proprietary hardware, eg Crays of any shape and size or clusters where MPI required a lot of hand tuning.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2553/cactus-link-command-uses-cppflags-and