Fix building with external LLVM

[stephanlachnit]

This Pull request:

Changes or fixes:

Ensure that LLVM is always linked statically. While doing so this fixes #12156 and #12152. Tested with both LLVM 13 and LLVM 16.

Checklist:

• tested changes locally
• updated the docs (if necessary)

This PR fixes #12156 #12152

[phsft-bot]

Starting build on ROOT-performance-centos8-multicore/soversion, ROOT-ubuntu2204/nortcxxmod, ROOT-ubuntu2004/python3, mac11/noimt, mac12arm/cxx20, windows10/default
How to customize builds

[stephanlachnit]

@Axel-Naumann is a backport of #12153 and this PR possible for a 6.28.xx release?

[phsft-bot]

Build failed on ROOT-ubuntu2004/python3.
Running on root-ubuntu-2004-3.cern.ch:/home/sftnight/build/workspace/root-pullrequests-build
See console output.

Failing tests:

• projectroot.gui.webdisplay.test.test_webgui_ping

[github-actions]

Test Results

         9 files           9 suites   1d 19h 23m 30s ⏱️
  2 475 tests   2 470 ✔️ 0 💤 5 ❌
21 262 runs  21 257 ✔️ 0 💤 5 ❌

For more details on these failures, see this check.

Results for commit 66f562d.

[phsft-bot]

Build failed on mac11/noimt.
Running on macphsft23.dyndns.cern.ch:/Users/sftnight/build/workspace/root-pullrequests-build
See console output.

Failing tests:

• projectroot.roottest.python.distrdf.dask.roottest_python_distrdf_dask_test_all
• projectroot.roottest.python.distrdf.spark.roottest_python_distrdf_spark_test_all

[vgvassilev]

That looks like the fix I imagined. LGTM! Thanks!

[hahnjo]

Also LGTM and CI builds are happy, so let's merge.

[hahnjo]

@Axel-Naumann is a backport of #12153 and this PR possible for a 6.28.xx release?

I think that's a good idea. Can you prepare a backport PR against v6-28-00-patches? If not I can also do it. Then up to Axel if we include it already in the next patch release that is expected ~now or later.

[stephanlachnit]

@Axel-Naumann is a backport of #12153 and this PR possible for a 6.28.xx release?

I think that's a good idea. Can you prepare a backport PR against v6-28-00-patches? If not I can also do it. Then up to Axel if we include it already in the next patch release that is expected ~now or later.

I was hoping I would be able to do so before I leave, but unfortunately I had to move and don't have access to my computer for a while... So I wouldn't mind if you give it a go, but it's also not super high priority.

[hahnjo]

So I wouldn't mind if you give it a go, but it's also not super high priority.

no worries, here we go: #13443
Happy moving 🚀

[hahnjo]

Hm, it appears the second commit breaks check-cling from ROOT with builtin_llvm=ON because it doesn't include LLVMConfig.cmake anymore, so TARGET_TRIPLE is not available. I think we can fix this in interpreter/CMakeLists.txt by forwarding the respective variable, let me investigate...

edit: #13446