So let each build script define its own level of sandboxing and then users can determine whether they are okay with that level or not, e.g. `cargo build --sandbox-level=...`
Rust, like C, C++, and every other systems programming language, is all about giving users the power to make mistakes. The philosophical difference when it comes to Rust is simply that it tries to force the user to flip off the safety on the gun before letting you shoot yourself in the foot. A Cargo config option letting people opt-out of sandboxing would be fully in line with Rust's philosophy.
Having a dangerous flag as a backwards compatibility flag is okay. I don’t think making users decide between multiple levels of sandboxing is constructive, they will just be trained to ignore it.
This is the kind of decision users likely don’t understand without looking at the source code of a crate and it’s bad UX to push it to be their responsibility.
No, the flag would not exist simply for backwards compatibility, it would exist because build scripts are occasionally necessary and there are plenty of legitimate uses for them, even if they should be opt-in.
