Comment (by Erik Schnetter):

Yes, external libraries really want traditional compiler settings. I always build external libraries externally; I think it was a mistake to use Cactus’s build system for that (downloads are large, build times are large, external libraries are not shared across configurations, etc.) I’m using Spack for all external libraries these days.

We could introduce EXTERNAL_CC etc. which we would use in external libraries.

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