It would be an optional preference (since it does slow down compilation by requiring comments to be parsed), like it is elsewhere.
But essentially anytime the compiler hits something like
// TODO: I need to eat more fiber
It'll add "I need to eat more fiber" to the todo/task list, which can be easily seen from either a tab on the compiler output, or a popup accessed with a shortcut/menu item.
For more information on how VS does it see https://docs.microsoft.com/en-us/visualstudio/ide/ using-the-task-list?view=vs-2019