[kelnos]

Sure, but I think that's still important that it's possible. And if it doesn't get implemented, the reason may be because JVM developers have done the work to figure out that in the real world the optimization doesn't buy all that much.

Regardless, if you care about performance enough (via actual benchmarks) that you know that you really need some data to be guaranteed to be stack-allocated structs, then you probably shouldn't be using Java (or any GC'd language?) in the first place. Records don't change that calculus.