Good point. In this case, the bug is in cool-framework, and I don't know that I see a great solution, regardless of the expressiveness of the constraint system.

Good point. In this case, the bug is in cool-framework, and I don't know that I see a great solution, regardless of the expressiveness of the constraint system. Ultimately I don't think there's a way to rule that out short of specifying exact versions. Unfortunately you can't retroactively change the version bounds for an existing release, so any library that specifies an upper bound admitting any yet-to-be-released version runs this risk.