Initialize Visual Studio C++ environment variables by locating the latest vcvarsall.bat
Put initcl.bat file in your PATH.
In a command line, type the following command: initcl
This will initialize the console to be able to call cl.exe with the latest available Visual Studio version.
If you call initcl twice, it will ignore the second time.
If the console was already initialized by other means, then it will not be initialized again, because it is looking if %VSINSTALLDIR% is defined.