Starting with the Visual Studio 2017 Installer, we can install multiple compilers of different versions for one Visual Studio installation.

The current detection assumes that each Visual Studio IDE version comes with at most one valid compiler. But this is wrong for Visual Studio 2017 and 2019.

I have installed the 14.22 and 14.21 compilers from Visual Studio 2019 Community edition.

The relevant folder structure looks like this:

• C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary

• • Build
    • vcvarsall.bat
    • Microsoft.VCToolsVersion.default.txt contains "14.22.27905"
    • Microsoft.VCToolsVersion.v142.default.txt contains "14.22.27905"
  • Build.14.21
    • Microsoft.VCToolsVersion.14.21.txt contains "14.21.27702"

So we can easily detect other compiler versions by looking for other Build folders.

To activate a specific compiler the vcvarsall.bat has new parameter "[-vcvars_ver=vc_version]"

So calling "vcvarsall.bat amd64 -vcvars_ver=14.21.27702" activates the second compiler.

I tried to fix this on my own. But this seems like a more involved task, because the fundamental assumption of one Visual Studio IDE version and one compiler version changed.

It seems we have to change and extend the MSVCToolChain and all the code around it. For example right now the Visual Studio IDE version is displayed instead of the compiler version.