Function unsafeMakeChildFiber

packages/effect/src/internal/fiberRuntime.ts:2470–2503

(
  effect: Effect.Effect<A, E, R>,
  parentFiber: FiberRuntime<B, E2>,
  parentRuntimeFlags: RuntimeFlags.RuntimeFlags,
  overrideScope: fiberScope.FiberScope | null = null
)

/** @internal */
export const unsafeMakeChildFiber = <A, E, R, E2, B>(
  effect: Effect.Effect<A, E, R>,
  parentFiber: FiberRuntime<B, E2>,
  parentRuntimeFlags: RuntimeFlags.RuntimeFlags,
  overrideScope: fiberScope.FiberScope | null = null
): FiberRuntime<A, E> => {
  const childId = FiberId.unsafeMake()
  const parentFiberRefs = parentFiber.getFiberRefs()
  const childFiberRefs = fiberRefs.forkAs(parentFiberRefs, childId)
  const childFiber = new FiberRuntime<A, E>(childId, childFiberRefs, parentRuntimeFlags)
  const childContext = fiberRefs.getOrDefault(
    childFiberRefs,
    core.currentContext as unknown as FiberRef.FiberRef<Context.Context<R>>
  )
  const supervisor = childFiber.currentSupervisor

  supervisor.onStart(
    childContext,
    effect,
    Option.some(parentFiber),
    childFiber
  )

  childFiber.addObserver((exit) => supervisor.onEnd(exit, childFiber))

  const parentScope = overrideScope !== null ? overrideScope : pipe(
    parentFiber.getFiberRef(core.currentForkScopeOverride),
    Option.getOrElse(() => parentFiber.scope())
  )

  parentScope.add(parentRuntimeFlags, childFiber)

  return childFiber
}

/* @internal */
const forkWithScopeOverride = <A, E, R>(