Equivalent of coroutine.yield(value) from rust ?

[tguichaoua]

How to call / what is the equivalent of coroutine.yield(value) from Rust code ?
I also want to pass an UserData to the yield.

[khvzak]

Unfortunately you cannot yield from Rust code as Lua does not allow to yield across C-call boundary (which is applicable to Rust).
The only way to yield is to use Rust async functions and tokio::task::yield_now

[tguichaoua]

Since it's not possible to yield accros C-call boundary, I move my api into lua.

function foo()
    local ud = _api.foo() -- call rust to create the userdata
    coroutine.yield(ud)
end