Add optional CoroutineStart parameter to launchIn

[pacher]

launchIn is a convenient shortcut, but can't be used if a start parameter of launch needs to be provided.
Shall we add an optional start to launchIn? I was wondering why not and why it is not already there.

My use case (probably similar to this):
I am not advanced user and trying to stay away from Unconfined and Undispatched, but I guess I am finally in a situation where I should use the latter.
I have a hot source which currently is still reactor Flux (not yet migrated to flow), let's call it flux.

flux()
   .asFlow()
   .onEach { ... }
   .launchIn(scope)

action()

Here action indirectly modifies the source flux. I need to be sure that by the time action is called subscription to source flux has happened and no emissions are lost between launch and action.
Do I understand correctly that I just need to launchIn(scope, start = CoroutineStart.UNDISPATCHED) to be safe?

[qwwdfsad]

Yes, UNDISPATHCED would do the trick as long as you don't have any non-trivial operators in between, e.g. buffer that actually launches a separate coroutine for flow collection.

Thanks for the use-case! I will close this as a duplicate of #1326, but will reconsider its status, keeping additional demand on it in mind