Yeah, arguably the only answer to this question is Rust.
Java/C#/etc. are not fully compiled (you do have a compilation step, but then also an interpretation step). And while Java/C#/etc. are memory-safe in a single-threaded context, they’re not in a multi-threaded context.
I mean, yeah, valid point. JVM languages also have GraalVM for that purpose.
But I’m playing devil’s advocate here. 🙃
Arguably these don’t count, because they’re not the normal way of using these languages. Reflection isn’t properly supported in them, for example, so you may not be able to use certain libraries that you’d normally use.
These also still require a minimal runtime that’s baked into the binary, to handle garbage collection and such.
Personally, I enjoy fully compiled languages, because they generally don’t lock you into an ecosystem, i.e. you can use them to create a library which can be called from virtually any programming language, via the C ABI.
You cannot do that with a language that requires a (baked-in) runtime to run.
But yeah, obviously someone just specifying “compiled” probably won’t have all these expectations…
I don’t think data races are generally considered a memory safety issue. And a lot of languages do not do much to prevent them but are still widely considered memory safe.
Even though they are not what people mean when they say “memory-safe”, it is technically a kind of memory safety. It is unsafe to modify non-mutexed/non-atomic memory that another thread might be modifying at the same time.
Yeah, that is why I prefixed that whole comment with “arguably”.
I feel like the definition of memory safety is currently evolving, because I do think data races should be considered a memory safety issue.
You’ve got a portion of memory and access to it can be done wrongly, if the programmer isn’t careful. That’s what memory safety is supposed to prevent.
Rust prevents that by blocking you from passing a pointer for the same section of memory into different threads, unless you use a mutex or similar.
And because Rust sets a new safety standard, I feel like we’ll not refer to Java and such as “memory-safe” in twenty years, much like you wouldn’t call a car from the 90s particularly safe, even though it was at the time.
Swift does have data race safety as of Swift 6 with their actor-based concurrency model and are introducing noncopyable types/a more sophisticated ownership model over the next few releases
Hmm, that sounds quite interesting. But because I’ve had to rebut that for everyone else that responded: Is it opt-in?
I guess, I would be fine with opt-in for the actor pattern, since you either do actors in your whole codebase or you don’t, but otherwise, opt-in often defeats the point of safety measures…
It’s opt-in in Swift 5 mode and opt-out in Swift 6 mode, the Swift 6 compiler supports both modes though and lets you migrate a codebase on a module-by-module basis.
Agree that opt-in sort of defeats the point, but in practice it’s a sort of unavoidable compromise (and similar to unsafe Rust there will always be escape hatches)
Yeah, arguably the only answer to this question is Rust.
Java/C#/etc. are not fully compiled (you do have a compilation step, but then also an interpretation step). And while Java/C#/etc. are memory-safe in a single-threaded context, they’re not in a multi-threaded context.
C# has native compilation capability, thanks to Native AOT
https://learn.microsoft.com/en-us/dotnet/core/deploying/native-aot/
I mean, yeah, valid point. JVM languages also have GraalVM for that purpose.
But I’m playing devil’s advocate here. 🙃
Arguably these don’t count, because they’re not the normal way of using these languages. Reflection isn’t properly supported in them, for example, so you may not be able to use certain libraries that you’d normally use.
These also still require a minimal runtime that’s baked into the binary, to handle garbage collection and such.
Personally, I enjoy fully compiled languages, because they generally don’t lock you into an ecosystem, i.e. you can use them to create a library which can be called from virtually any programming language, via the C ABI.
You cannot do that with a language that requires a (baked-in) runtime to run.
But yeah, obviously someone just specifying “compiled” probably won’t have all these expectations…
How are they not memory safe in a multi-threadded context?
There’s nothing to prevent data races. I myself have fallen into the trap of using the same list from multiple threads.
I don’t think data races are generally considered a memory safety issue. And a lot of languages do not do much to prevent them but are still widely considered memory safe.
Even though they are not what people mean when they say “memory-safe”, it is technically a kind of memory safety. It is unsafe to modify non-mutexed/non-atomic memory that another thread might be modifying at the same time.
Yeah, that is why I prefixed that whole comment with “arguably”.
I feel like the definition of memory safety is currently evolving, because I do think data races should be considered a memory safety issue.
You’ve got a portion of memory and access to it can be done wrongly, if the programmer isn’t careful. That’s what memory safety is supposed to prevent.
Rust prevents that by blocking you from passing a pointer for the same section of memory into different threads, unless you use a mutex or similar.
And because Rust sets a new safety standard, I feel like we’ll not refer to Java and such as “memory-safe” in twenty years, much like you wouldn’t call a car from the 90s particularly safe, even though it was at the time.
Swift fits the description too
Most people would consider it so, but it actually does not either fulfill the argument I posed there: https://forums.swift.org/t/what-language-is-more-memory-safe-swift-or-rust/31987
Swift does have data race safety as of Swift 6 with their actor-based concurrency model and are introducing noncopyable types/a more sophisticated ownership model over the next few releases
Hmm, that sounds quite interesting. But because I’ve had to rebut that for everyone else that responded: Is it opt-in?
I guess, I would be fine with opt-in for the actor pattern, since you either do actors in your whole codebase or you don’t, but otherwise, opt-in often defeats the point of safety measures…
It’s opt-in in Swift 5 mode and opt-out in Swift 6 mode, the Swift 6 compiler supports both modes though and lets you migrate a codebase on a module-by-module basis.
Agree that opt-in sort of defeats the point, but in practice it’s a sort of unavoidable compromise (and similar to unsafe Rust there will always be escape hatches)