Export relevant kokkos options

[dalg24]

Honor Kokkos_OPTIONS_NOT_TO_EXPORT list (that is used when building as part of Trilinos) and add a few options that it makes no sense to export to the list.
For instance, no one care whether I enabled self containment tests when finding an install of Kokkos.

We might want to clean further but I think it is already a step in the right direction.

Here are the changes on my local KokkosConfigCommon.cmake

--- develop
+++ this_pr
@@ -1,5 +1,5 @@
 SET(Kokkos_DEVICES THREADS)
-SET(Kokkos_OPTIONS DEPRECATION_WARNINGS;TESTS;COMPILER_WARNINGS;LAUNCH_COMPILER;CUDA_LAMBDA;COMPLEX_ALIGN)
+SET(Kokkos_OPTIONS DEPRECATION_WARNINGS;LAUNCH_COMPILER;CUDA_LAMBDA;COMPLEX_ALIGN)
 SET(Kokkos_TPLS LIBDL;THREADS)
 SET(Kokkos_ARCH )
 SET(Kokkos_CXX_COMPILER "/Library/Developer/CommandLineTools/usr/bin/c++")

[dalg24]

To elaborate a bit, I am working towards properly exporting variables such as Kokkos_ENABLE_{CUDA,HIP}_RELOCATABLE_DEVICE_CODE which is needed to enable building Trilinos against an external install of Kokkos. And my angle is to do something along these lines

diff --git a/cmake/KokkosConfigCommon.cmake.in b/cmake/KokkosConfigCommon.cmake.in
index 63949e561..597aff5b0 100644
--- a/cmake/KokkosConfigCommon.cmake.in
+++ b/cmake/KokkosConfigCommon.cmake.in
@@ -10,6 +10,9 @@ SET(Kokkos_CXX_STANDARD @KOKKOS_CXX_STANDARD@)
 FOREACH(DEV ${Kokkos_DEVICES})
   SET(Kokkos_ENABLE_${DEV} ON)
 ENDFOREACH()
+FOREACH(OPT ${Kokkos_OPTIONS})
+  SET(Kokkos_ENABLE_${OPT} ON)
+ENDFOREACH()

 IF(Kokkos_ENABLE_CUDA)
   SET(Kokkos_CUDA_ARCHITECTURES @KOKKOS_CUDA_ARCHITECTURES@)

I just don't want us to export all sort of garbage variables.

[masterleinad]

I'm wondering if we should rather whitelist options to export.

[dalg24]

Both have pros and cons. If no one feel too strongly about it I would just go with the blacklist. We might accidentally export more than we intended but we will fix it.

[masterleinad]

I would prefer if we already do the

+FOREACH(OPT ${Kokkos_OPTIONS})
+  SET(Kokkos_ENABLE_${OPT} ON)
+ENDFOREACH()

part in this pull request so that we have more uniform behavior already between building as part of Trilinos or stand-alone.

[dalg24]

I would prefer if we already do the

+FOREACH(OPT ${Kokkos_OPTIONS})
+  SET(Kokkos_ENABLE_${OPT} ON)
+ENDFOREACH()

part in this pull request so that we have more uniform behavior already between building as part of Trilinos or stand-alone.

I thought the "what" we export was a bit orthogonal to our exporting variables but I added to this PR in the hope we reach consensus.

[dalg24]

Ping

[masterleinad]

I would probably add DEPRECATION_WARNINGS if you want to Kokkos_ENABLE_CUDA_RELOCATABLE_CODE anyway.

[dalg24]

The deprecation warnings are different. Although I am not convinced it is really useful, in contrast to the ones I listed, it is something that is observable downstream.

[masterleinad]

Sure. I can see that KOKKOS_ENABLE_DEPRECATED_CODE_* might be relevant but DEPRECATION_WARNINGS could also be an impl variable.

[masterleinad]

I think exporting the options is the important change here. We can also work on the list of non-exported options elsewhere.

[cz4rs]

Both have pros and cons. If no one feel too strongly about it I would just go with the blacklist. We might accidentally export more than we intended but we will fix it.

One argument for whitelist would be readability: it's probably more important to see which options we allow to be exported versus things we don't.

[cz4rs]

Looks good to me, no strong preference on whitelist vs blacklist.