Oh gosh, I forgot about that. Is that Windows only though? I remember MSVC had managed/unmanaged C++ and allowed calling between the two.

Sadly yes.

And although they don't have much love for it, they still keep it relatively up to date.

It was one of the .NET Core 3.1 main milestones.

However I would say for the purpose of binding .NET and C++, probably it doesn't need to understand everything anyway.

The C++/CLI compiler is definitely Windows-only. But I'm not sure whether the generated code would be, if you compile with /clr:pure (which can still handle everything except for setjmp/longjmp).

/clr:pure has been deprecated for some time now, unfortunately. But older compilers are still around...