where is visual studio C++ compiler VS2017
first suggest take a look at https://perso.uclouvain.be/allan.barrea/opencv/building_tools.html , it is informative
and in VS2015 it's at C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\cl.exe
and in VS2013 it's at C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\cl.exe
and in VS2017 it's at C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\VC\Tools\MSVC\14.16.27023\bin
there're many version of cl.exe