Comment (by Roland Haas):

yes, that is a possibility: https://github.com/EinsteinToolkit/ExternalLibraries-CMake and has been tested in the past.
Upside: tested, needs no extra installed packages.
Downside: Cmake is very slow to compile, so ideally I would not have to build it.

The ExternalLibraries provided CMake has been used on clusters (where cmake was too old), so is known to work (needs some support by their client thorns [basically have to look for cmake in $CMAKE_DIR/bin/cmake] though since the CST does not allow to manipulate PATH, though I suspect one could actually make that work by manipulating variables in make.FOO.defn in bindings).

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2761/some-externallibraries-require-cmake-to