MSP432E411Y-BGAEVM: std::mutex

Part Number: MSP432E411Y-BGAEVM

Hi,
I'm porting a C++ application from a Linux platform, to run under TI RTOS. If possible, I would like to use a std::mutex.
Adding:-

#include <mutex>

compiles OK, but as soon as I try and declare a

std::mutex myMutex;

it just says namespace std does not include mutex.

I have tracked down the header file in

C:\ti\ccs1040\ccs\tools\compiler\ti-cgt-arm_20.2.5.LTS\include\libcxx

and see that the first section, including namespace std, is commented out, but the later bits include _mutes_base and this seems to define std via the macro _LIBCPP_BEGIN_NAMESPACE_STD.

Ideally, to minimise change, I would like to use

  std::lock_guard<std::mutex> lk(myMutex);

but getting just the mutex working would be a good start.

Any tips?

Thanks

Jim