There are two kinds of memory leaks: forgotten manual freeing (all references are gone, but allocation is not) and forgetting to get rid of references that keeps an allocation alive. Both are a kind of logical error, but the first is mostly possible in languages with manual memory management. The second one is a universal logical error (only programmer knows which live references are really needed).
In the Haskell community I’ve seen the second kind called “space leaks.” I don’t see it used much outside that community but I like the term and use it when talking about other languages as well.
I suppose all languages allow them, depending on how you define a memory leak. Garbage collected languages generally prevent them, since you never have to explicitly free memory, but if there are reference cycles, that memory can never be freed automatically. Rust has the same problem, but since rust uses lifetimes to understand when to drop things, many people expect that this will mean there can be no memory leaks, but leaks are not considered a correctness or safety issue (oom is a panic and panic is safe!). Not only explicitly possible (through Box::leak) but also possible by mistake (again, usually through reference cycles).
There are two kinds of memory leaks: forgotten manual freeing (all references are gone, but allocation is not) and forgetting to get rid of references that keeps an allocation alive. Both are a kind of logical error, but the first is mostly possible in languages with manual memory management. The second one is a universal logical error (only programmer knows which live references are really needed).
In the Haskell community I’ve seen the second kind called “space leaks.” I don’t see it used much outside that community but I like the term and use it when talking about other languages as well.
Rust allows reference-counting cycles, right?
I suppose all languages allow them, depending on how you define a memory leak. Garbage collected languages generally prevent them, since you never have to explicitly free memory, but if there are reference cycles, that memory can never be freed automatically. Rust has the same problem, but since rust uses lifetimes to understand when to drop things, many people expect that this will mean there can be no memory leaks, but leaks are not considered a correctness or safety issue (oom is a panic and panic is safe!). Not only explicitly possible (through Box::leak) but also possible by mistake (again, usually through reference cycles).
> but if there are reference cycles, that memory can never be freed automatically.
Many garbage collection algorithms can deal with cycles.