The types are there for garbage collection, which is there for integration with the Web APIs which are all defined in terms of garbage collected objects.
Yoshua is part of the "loud contingent" being described. He's not on the lang team, and he's been "working on" things like keyword generics for years without any indication that they are going to make it into the language.
> We (Oli, Niko, and Yosh) are excited to announce the start of the Keyword Generics Initiative, a new initiative 1 under the purview of the language team
Maybe he's not on the language team (I haven't read enough into Rust governance structures to know definitively) but it's not like he's on some random person working on this. And yes, work takes time, I actually disagreed with his initial approach where his syntax was to have a bunch of effects before the function name, and everyone rightly mentioned how messy it was. So they should be taking it slow anyway.
The thing is that anyone can show up and spend time discussing ideas in Rust project spaces. From the outside it is easy to confuse that with actual movement toward landing changes in the language.
(The communication aspect of this is something that has bothered me many times in the past- even people who are lang team members often phrase things in a way that makes it sound like something is on its way in, when it's still just in the stage of "we're kinda noodling with ideas.")
Or put another way, a hypothetical feature that you made up in your head is the thing that requires source access. Editions do not let you change the semantics of types.
To be fair, Rust tooling does tend toward build-from-source. But this is for completely different reasons than the edition system: if you had a way to build a crate and then feed the binary into builds by future compilers, it would require zero additional work to link it into a crate using a different edition.
Exactly, hence why people should stop talking about editions as if they sort out all Rust evolution problems, in your own words it doesn't allow changing type semantics
I think you're too stuck on the current implementation. Work is going into investigating how to evolve the standard library over editions. The "easiest" win would be to have a way to do edition-dependent re-exports of types.
Not at all. It's much more efficient to implement a GC on x86 or ARM than it is on Wasm 1.0/2.0, because you control the stack layout, and you don't have an impenetrable security boundary with the JS runtime that your GC needs to interop with.
Not to mention the issue that bundling a GC implementation as part of your web page can be prohibitive in terms of download size.
Tbh I never understood nor cared why people would want to use a garbage collected language with WASM in browsers when there's already Javascript. One of the main points of WASM was to avoid GC overhead alltogether (thus the 'garbage-free' subset asm.js which then became WASM).
The reason rust-analyzer doesn't update diagnostics until you save is historical. Originally, people tried to build IDE support by reusing rustc itself, but this proved too slow and cumbersome at the time.
Rust-analyzer reimplemented the frontend in a more IDE-friendly architecture, but focused more on name resolution than on type checking. So it delegated diagnostics to literally just running `cargo check`.
As parts of rustc get rewritten over time (the trait solver, borrow checker) they have also been made more IDE-friendly and reusable, so rust-analyzer is slowly gaining the ability to surface more type checking diagnostics as you edit, without delegating to `cargo check`.
TCO is less of an optimization (which are typically best-effort on the part of the compiler) and more of an actual semantic change that expands the set of valid programs. It's like a new control flow construct that lives alongside `while` loops.
> Suppose, instead, we had a mechanism that allowed registering arbitrary panic hooks, and unregistering them when no longer needed, in any order. Then, we could do RAII-style resource handling: you could have a `CursesTerminal` type, which is responsible for cleaning up the terminal, and it cleans up the terminal on `Drop` and on panic. To do the latter, it would register a panic hook, and deregister that hook on `Drop`.
This doesn't get rid of unwinding at all- it's an inefficient reimplementation of it. There's a reason language implementations have switched away from having the main execution path register and unregister destructors and finally blocks, to storing them in a side table and recovering them at the time of the throw.
Giving special treatment to code that "explicitly wants" to handle unwinding means two things:
* You have to know when an API can unwind, and you have to make it an error to unwind when the caller isn't expecting it. If this is done statically, you are getting into effect annotation territory. If this is done dynamically, are essentially just injecting drop bombs into code that doesn't expect unwinding. Either way, you are multiplying complexity for generic code. (Not to mention you have to invent a whole new set of idioms for panic-free code.)
* You still have to be able to clean up the resources held by a caller that does expect unwinding. So all your vocabulary/glue/library code (the stuff that can't just assume panic=abort) still needs these "scoped panic hooks" in all the same places it has any level of panic awareness in Drop today.
So for anyone to actually benefit from this, they have to be writing panic-free code with whatever new static or dynamic tools come with this, and they have to be narrowly scoped and purpose-specific enough that they could essentially already today afford panic=abort. Who is this even for?
To be very explicit about something: these are all vague design handwaves, and until they become not only concrete but sufficiently clear to handle use cases people have, they're not going to go anywhere. They're vague ideas we're thinking about. Right now, panic unwind isn't going anywhere.
Hypothetically Rust could make `Mutex<InnerBlah>` work with just two bits in the same way it makes `Option<&T>` the same size as `&T`. Annotate `InnerBlah` with the information about which bits are available and let `Mutex` use them.
There was talk of Rust allowing stride != alignment. [1] I think this would mean if say `InnerBlah` has size 15 and alignment 8, `parking_lot::Mutex<InnerBlah>` can be size 16 rather than the current 24. Same would be true for an `OuterBlah` the mutex is one field of. But I don't think it'll happen.
In principle, you Rust could create something like std::num::NonZero and its corresponding sealed trait ZeroablePrimitive to mark that two bits are unused. But that doesn't exist yet as far as I know.
There are also currently the unstable rustc_layout_scalar_valid_range_start and rustc_layout_scalar_valid_range_end attributes (which are used in the definition of NonNull, etc.) which could be used for some bit patterns.
