Accessing std::env::args from a Rust library in a C++ binary fails on FreeBSD

[zanchey]

I'm not sure that this is definitely a cxx problem, but here's the investigation I've done so far.

std::env::args when called from a Rust library, linked to a C++ binary, returns an empty array on FreeBSD.

There's a minimal reproducing repo at https://github.com/zanchey/argstest/ (clone and run make to produce an argstest binary) which:

• has a C++ entrypoint, that
• calls a Rust library function, that
• prints the contents of std::env::args

On Linux/glibc this correctly produces (say) Args { inner: ["./argstest", "foo", "bar", "baz"] }, but on FreeBSD returns Args { inner: [] }.

I don't know if cxx does any magic with the args vector to make it visible from Rust? I couldn't see anything obvious.