How to call a Composable fun from coroutine while collecting a flow? compiler said you can't use Composable fun from another non Composable fun.

You can’t. As for why, consider what it would mean for a composable called from a suspend fun to emit?

I collect actions of the fragment in one non-composable fun, so one action need to call a composable fun. maybe I need to call the collecting fun from composable.

Composable functions emit nodes like UI. That UI has to have somewhere to go. If you called a composable from a coroutine, the UI it emits would have nowhere to go.

The fun that collect actions from VM is:

private fun setObservers() {
    lifecycleScope.launch {
        lifecycle.repeatOnLifecycle(Lifecycle.State.STARTED) {
            viewModel.taskDetailsActions.collect { action ->
                when(action){
                    is TaskDetailsActions.ShowSureDeleteTaskDialog -> {
                       ShowSureDeleteTaskDialog() //trigger composable fun to show AlertDialog
                    }
                }
            }
        }
    }
}

Right, so you probably want to have something like this:

var showSureDeleteTaskDialog by mutableStateOf(false)
  private set

private fun setObservers() {
  …
  is TaskDetailsActions.ShowSureDeleteTaskDialog -> {
    showSureDeleteTaskDialog = true
  }
}

and then in a composable,

if (viewModel.showSureDeleteTaskDialog) {
  Dialog { … }
}

Sorry for late response, this solution fine but the code becomes some boilerplate. I think to trigger the dialog from compose directly instead of submit the action to VM then observer it, right?

If that works, then sure that's an option, but it's probably a question of clean layering and grouping of responsibilities.