[CMake] Overloading/shadowing/redefining CMake intrinsic commands

[Zaak Beekman]

I have been moving towards modern CMake where
includes/compiler-flags/libraries/etc. are using target properties and
transitive usage requirements which has greatly simplified setting up
Modern Fortran build systems. In addition, if you're going to vendor
all/most of your package's dependencies and just configure them along with
your package with a simple `add_subdirectory()` call this allows you to
setup projects that may be consumed in this way by parent projects or used
on their own. This is super convenient, and IMO, easier to understand and
deal with than super builds. The propagation of transitive properties makes
this relatively easy and seamless.

However, until I/we have time to improve the OpenCoarrays CMake
`find_package` support some of the projects my colleagues are writing/using
set the OpenCoarrays compiler wrapper script, `caf`, as $FC before invoking
CMake. This is fine until it some parent project is using
GFortran+OpenCoarrays and a child project may not need Coarrays at all.
Everything proceeds find until the tests are run because, at least on some
systems, executables will hang when compiled against MPI/Opencoarrays
without the MPI job launcher scripts being used to launch the test
executable.

I realize I can write my own function/macro and just call it from all the
projects to decide how the tests should be launched---with `cafrun` if
compiled by the `caf` wrapper script or by directly calling the executable
if compiled with GFortran. And, yes, I know that the real solution to this
problem is to improve the CMake support of OpenCoarrays... but time is
scarce at the moment.

So, my question is: Can I overload/shadow/redefine the intrinsic
`add_test()` cmake command?

This way if the child project calls `add_test()` the parent project can
redefine it if needed. Otherwise, the child project will run as intended
when configured and built on its own (i.e. just with GFortran, w/o coarray
support & OpenCoarrays).

Thanks,
Zaak

Izaak "Zaak" Beekman

-------------------------------------------------------------------------------

HPC Scientist
ParaTools Inc. <http://www.paratools.com/>
5520 Research Park Drive
Suite 100
Baltimore, MD 21228
phone: (443) 543-5059
mobile: (917) 797-3239
-------------------------------------------------------------------------------
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://cmake.org/pipermail/cmake/attachments/20180404/d91c47af/attachment.html>