I've found some questions here about the can+have+V3 possibility when speaking about possible situations in the past. But there was nothing said about future perfect usage, and I wonder if we can use it to speak about some actions that can become accomplished in the future.
I know that we can use will or may/might in this case, but I feel that the meanings may be slightly different:
- I will have done it by tomorrow. - It sounds like a promise to me: I'm quite sure that I will accomplish it today.
- I may/might have done it by tomorrow - a possibility: I probably will accomplish it today, but I'm not sure at all
- *I can have done it by tomorrow - an ability: I have an opportunity to accomplish it today (but I may not use it)
Is the third sentence possible, and does it all make sense?