Error async_msg is not a template my_prog C:\Program Files (x86)\IntelSWTools\system_studio_2020\compilers_and_libraries_2020.0.166\windows\tbb\include\tbb\flow_graph_opencl_node.h 354
... and many more.
If I comment out the header file //#include "tbb/flow_graph_opencl_node.h" then my program compiles again.
Maybe the installation is incomplete. I was using VS 2019 16.4.5 but it said to upgrade because of the an OpenCL requirement. That broke the Intel installations. After a few iterations of running the System Studio 2020 installer, and selecting anything "OpenCL", it stopped adding anything meaning it thinks everything is complete. Eventually I ran several Visual Studio Extension Intallers (*.vsix) in a System Studio 2020 subfolder and the Intel Compiler 19.1 and the Intel libraries (TBB, ...) where available again in the project properties.
Any ideas on what needs fixing? Files, paths, env vars, compiler settings, .... ?