multicore::Core::spawn's entrypoint should return ! according to docs

[not-nullptr]

from the docs:

Spawn a function on this core.
The closure should not return. It is currently defined as -> () because -> ! is not yet stable.

returning ! has been stable for a while now -- the following code compiles under rustc 1.85.0:

fn core_entry() -> ! {
    loop {}
}

[ithinuel]

Our current MSRV is 1.79.
I searched in the release note but couldn’t find an official statement about it.
Could you share a link to the announcement please (or the relevant tracking issue)?

[not-nullptr]

rust-lang/rust#65355 ! was stabilised in rust 1.41.0

[ithinuel]

Ah right, I see the missundestanding.

You can indeed use the ! type in the return position of a closure or a function.
However, you still cannot define a bound to an FnOnce() -> ! which is what the definition of spawn would need.

This causes:

error[E0658]: the `!` type is experimental
   --> src/multicore.rs:262:24
    |
262 |         F: FnOnce() -> ! + Send + 'static,
    |                        ^
    |
    = note: see issue #35121 <https://github.com/rust-lang/rust/issues/35121> for more information

[not-nullptr]

what a shame... hope its stabilised soon. thanks!