Separate Spawn/LocalSpawn from futures-core?

[taiki-e]

I think this trait is not as stable as other futures-core's items like Stream.

Related:

• &self vs. &mut self for spawners #1669
• Should we remove FutureObj #1634 (comment)

[seanmonstar]

I agree with this, especially with the odd-feeling spawn_obj(FutureObj) method (and the issues you linked). I think it could be moved to futures-executor (and the executor implementations could be made optional, so depending on the crate doesn't require depending on executors you don't use).

It used to need to be part of core, since an executor/spawner was needed to create a Context. But since that was removed, this doesn't need to be part of core.

[taiki-e]

I think it could be moved to futures-executor (and the executor implementations could be made optional, so depending on the crate doesn't require depending on executors you don't use).

The executor implementations (LocalPool, ThreadPool) depend on futures-util, futures-util (SpawnExt, Executor01CompatExt, Executor01Future, Executor01As03) depends on Spawn trait, so we need to resolve these circular dependencies.

[cramertj]

#1925 has landed.