In my experience that is just the silly amount of variables you have to export to use the VC++ compiler and this is why they provide a dedicated terminal prompt for the VC++ compiler with all the right env vars loaded. I've struggled as well automating VC++ compilation in rust as a result.

If you're so inclined to revisit this using mingw with rust you can see how here https://rust-lang.github.io/rustup/installation/windows.html

This is far easier to automate imo

I forgot to mention that I didn't have VC++ installed at all (because it's not free from all points of view).

If I remember correctly I tried installing the MinGW based Rust toolchain too, but I'll try again with the instructions you've given me.

Finding where & how to use an installed VS instance (or selecting one) in automated tooling is solved by the criminally unknown, MIT licensed, MS supported, redistributable, vswhere tool: https://github.com/microsoft/vswhere

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