Tim Adye

Let me test this now, and then I hope we can merge this sucker.

I'm not a ROOT developer, but am a long-time semi-expert user of ROOT on Linux, Windows, and WSL. I raised this [issue on the ROOT forum](https://root-forum.cern.ch/t/root-with-wslg/54738) to see if anyone...

> Makes sense. There's one unit test failure on macOS related to an unused variable. So the warning is [here](https://github.com/acts-project/acts/blob/main/Tests/UnitTests/Core/EventData/TrackContainerComplianceTests.cpp#L77): ``` /Users/runner/work/acts/acts/build/Tests/UnitTests/Core/EventData/TrackContainerComplianceTests.cpp:77:36: error: unused variable 'caccNMeasuements' [-Werror,-Wunused-variable] ConstProxyAccessor caccNMeasuements("nMeasurements"); ```...

The macos build failure looks like an unrelated configuration problem (XercesC 3.2.5 instead of 3.3.0). Hopefully this can be fixed soon and we can see if the last update fixes...

@AJPfleger I think this is waiting for your approval, if you do approve. Thanks!

> I wonder if the `nan` is bound to an earlier FPE and we should rather fix the root cause. I don't know if FPEs come from `std::log(-ve)` giving `nan`....

Somehow #3794's changes were included here and removed from that PR. No harm done.

Just to put Paul's point another way... why do we need to requite TBB, when ACTS works fine (single-threaded) without it? (Or at least it used to, last time I...

But mostly `ACTS_USE_EXAMPLES_TBB` is on by default, rather than requested by the user with an explicit `-DACTS_USE_EXAMPLES_TBB=ON`. In this case, it is nice to have the fallback to `OFF` to...

I think it is a pity to add a required dependency without good reason. It seems this one should be quite easy to `#ifndef ACTS_EXAMPLES_NO_TBB` around the `#include` and `m_memoryStatistics`...