Very nice: > Zero-copy deserialization > […] The semantics of Rust guarantee that the input data outlives the period during which the output struct is in scope, meaning it is impossible to have dangling pointer errors as a result of losing the input data while the output struct still refers to it.
>The semantics of Rust guarantee that the input data outlives the period during which the output struct is in scope To be fair, so does the semantics of every language with garbage collection -- keeping things alive while there are references to them is the bread and butter of GC. EDIT: I do think it's impressive that Rust can manage this without the overhead of GC. But the sentence from the release notes immediately…
char buf[1024];
while (read(fd, buf, 1024)) {
messages.push_back(deserialize(buf));
}
for (message: messages) {
print(message);
}
I think doing reader/writer refcounting at runtime is hard because this is a case where there's nothing reasonable to do at runtime if you have incompatible references. At best you can do copy-on-write, but then you silently lose the zero-copy performance. You really want a compile-time error saying "You structured this code wrong, go redesign it or add some copies."