Rust’s scoping rules prevent most double free errors. You can get them with certain techniques but it’s also possible, say, use JNI to shoot yourself in the foot, too.

Basically, I’d say that at fond point this gets to be a lot more complicated because you’re talking about which sets of features & cultural practices make you more or less likely to make exploitable errors. Does using a GC buy you enough to balance out the complexity fetish common in the open source Java world? Which is safer probably depends on what type of projects you work on.