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How to create a `CoroutineScope` that is a child of another ?
What I tried:
```val parentScope = ...
val childScope = parentScope + SupervisorJob()

parentScope.cancel()
parentScope.isActive // false
childScope.isActive // true (!!)```
It seems that cancelling the parent does not cancel its children. I guess I'm missing something here...

`val childScope = parentScope + SupervisorJob(parentScope.coroutineContext[Job])`

Woudln't this make them siblings rather than enforce a parent-child hierarchy?

Isn't it just either
`coroutineScope` (<https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/coroutine-scope.html|doc>)  or `supervisorScope` (<https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/supervisor-scope.html|doc>)

Well this doesn't return the scope to you, right.

<@USEUP6TBK> nope, it will be parent-child hierarchy, if you cancel childScope, parentScope will be active active.
From the SupervisorJob doc:
&gt; _* If [parent] job is specified, then this supervisor job becomes a child job of its parent and is cancelled when its parent fails or is cancelled. All this supervisor's children are cancelled in this case, too. The invocation of [cancel][Job.cancel] with exception (other than [CancellationException]) on this supervisor job also cancels parent._

Thanks <@UK592L8VC>. Thought that it was simply setting the job itself and not the parent

Indeed, that was the missing part!
I expected the child scope to directly inherit the job of its parent. It seems that this parent-child relationship should be explicitly defined

I think it's impossible because constructor can't be suspend, and there is no access to coroutineContext from non-suspend block.