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.
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.