Visual studio 2017 with Xamarin:

* writing some sweet code, life is good.. build and run.
*change int age to 2, build, build failed, no single message why.
*clean, clean failed, no single message why.
* build rebuild clean all or by project, nothing works, no single message why.
*change nothing, restart VS, build success !
* writing some code, same problem
*restart VS, "this project is not compatible with Visual Studio"

Good bye guys, I'm gonna kill myself

I am so glad I found a way to compile c++ for personal projects without using MS VS. Time to relieve my machine from this burden :D