Swift Concurrency MainActor does not execute when Swift DLL is called from .NET on Windows

[dima_kozhinov (Dmitry Kozhinov)]

@mattie

You can use custom executors

Not only Swift Concurrency is not easy to comprehend, you are suggesting that an ordinary programmer should modify its internals.

@mattie

However, there are some circumstances where this does not happen, and I believe they are all just bugs. If you think there is a situation where this does not happen and it is intentional behavior or some other kind of gap, I'd like to know.

@NotTheNHK

I looked into this a bit more, and I think the actual culprit is that, on non-Darwin platforms, dispatchMain() is called during the initialization of the main executor.

@David_Smith

if the main thread has special significance on the target platform like it does on Darwin, exiting it by calling dispatchMain() could certainly cause other problems.

It looks like on non-Darwin platforms the dispatchMain() is called during initialization of Swift Concurrency, which terminates the main thread (no less!), which in turn destroys all things that depend on initial/main/GUI thread.

@mattie

I believe they are all just bugs

Probably. But those that require fixing ASAP.