I'm sorry, but that is a naive misconception. "everything is owned by the GC" is a sign of not understanding concept of ownership, BTW. GC is not an actor in the system, so does not participate in the ownership. A Java finalizers might kind of do stuff, but that's when all references are gone, so they have exclusive ownership.
Anyway... Languages with GC still do have ownership. It is just defaulting to be the most problematic case of "shared ownership" everywhere. Shared ownership is only worry-free if you don't ever modify data. Which is possible, but actually harder and more constraining to implement in a practical software (especially if you care about any performance). So then you either have to synchronize everything with mutexes, and figure out a way to not deadlock yourself on every step (also hard), or you have to implicitly track ownership and decide who can and when mutate the data, which is exactly what Rust would make you do, but this time you get no compiler help. The only reason people don't notice that is because they do it incorrectly and it works most of the time, so they are unaware.
There is no escape from it - one has to figure out ownership with a GC or without it, because GC has nothing to do with ownership. It only reclaims memory after all references are gone. That's it. That is actually very, very little improvement.
"The only reason people don't notice that is because they do it incorrectly and it works most of the time, so they are unaware."
Ironically, that's Rust biggest problem: not using perfect ownership management works for most software most of the time and that's good enough for most people and companies.
You probably can't sell ownership management as a feature. The only thing that Rust can sell and that makes sense is "it won't crash" + "it's fast", but then there's a lot of other languages that have the first property and the second is not very appreciated, as seen in the rise of so-called Electron apps and web apps in general.
Sure. SWE is not a first industry where you can get away with cutting corners or straight incompetence. And some people are going to write a code taking care of ownership by experience, skill, etc. and they don't need Rust. They might not know they are taking care of ownership, and yet do it correctly. Rust is only formalizing and verifying it.
I think in time more and more people and teams will discover that doing stuff with Rust is just cheaper and more productive. You learn ownership once, you get great results ever after.
Ok, then educate me—what is ownership if not the responsibility for managing (cleaning up) a resource? In my C and C++ days, I never heard of it refer to some kind of exclusive permission to mutate a resource (which seems to be your meaning), but rather as the responsibility to free the resource (as in “the owner must and only the owner _can_ free the owner resource”).
It seems likely that you and I are using different definitions, and yours Rust-specific (and therefore not meaningfully generalizable to other languages, especially those with GC).
Ownership is (at least) two things: who has the responsibility for destroying an object when it's finished with, which GC takes care of, and who has the right to mutate an object while it's alive, which GC doesn't.
I mostly write Java for a living, have done for a decade, and still occasionally trip myself up by mutating an object I'd forgotten I've shared.
Thanks for responding, Steve. I understand that “ownership” implies the right to destroy in any language. The bit I’m not so clear about is whether or not there are other rights/responsibilities (such as the right to mutate) as the OP suggests and whether a definition that includes those rights/responsibilities can meaningfully apply to any language or just Rust.
Anyway... Languages with GC still do have ownership. It is just defaulting to be the most problematic case of "shared ownership" everywhere. Shared ownership is only worry-free if you don't ever modify data. Which is possible, but actually harder and more constraining to implement in a practical software (especially if you care about any performance). So then you either have to synchronize everything with mutexes, and figure out a way to not deadlock yourself on every step (also hard), or you have to implicitly track ownership and decide who can and when mutate the data, which is exactly what Rust would make you do, but this time you get no compiler help. The only reason people don't notice that is because they do it incorrectly and it works most of the time, so they are unaware.
There is no escape from it - one has to figure out ownership with a GC or without it, because GC has nothing to do with ownership. It only reclaims memory after all references are gone. That's it. That is actually very, very little improvement.