Change C++ standards

[ashwith chandra]

How to change the c++ standards in windows. I have implemented all the options but i didnt succeeded. I followed the c++ toolchain docs 
https://bazel.build/tutorials/ccp-toolchain-config

but still it is not taking c++20. I have added new flag -std=c++20 but no use when i compile it the msvc compiler is complaining about optional is not found in std.

I did exactly the same as the docs.