"Would have been able to do something" vs "would have been able to have done something"

Question

Tell me please if there is any difference in meaning between the following sentences.

• If I had worked overtime, I wouldn't have been able to finish my project.

• If I had worked overtime, I wouldn't have been able to have finished my project.

I cannot see the difference but feel there is a small one, if someone would use the perfect infinitive in the past conditional as in my second question. By the way, I have heard a native English speaker use the perfect infinitive in the past conditional only once.

Answer 1

The difference is subtle, but in the first, there is less of an implication that the project is, in fact, currently finished.

If I had worked overtime, I wouldn't have been able to finish my project.

There are a few things going on here that you can glean from this sentence:

1. You didn't work overtime.
2. You are or were working on some project.
3. In a world where you had worked overtime, your project would not be finished by some implied deadline.

The important thing to notice here is that it is not clear if you are still working on the project. You may be making a forecast about whether or not the project will be finished, or you may be making a statement about a past project. It's not clear.

On the other hand:

If I had worked overtime, I wouldn't have been able to have finished my project.

This statement clearly and unambiguously declares that you have finished your project. It places the project as a thing of the past.