The good news is that you don't have to make a final decision right now.
If you're reasonably certain that you'd be interested in astrophysics and a PhD is at least a possibility, then looking for a program that will give you a solid foundation in physics is probably what you want. Specialising too early, committing to an astrophysics program before you've even started university, for example, tends to close more doors than it opens. A degree in physics won't close the door on astrophysics courses and it will qualify you for graduate study in astrophysics.
So then comes the question of whether or not to double major in something like computer engineering. The big concern there is that engineering is a professional field - you need to graduate from an accredited program to become a certified professional engineer. That's what a double major in computer engineering will give you. It will also qualify you to go to graduate school in computer engineering if that's at all of interest. The down side is that this will both eat up a lot of electives and could result in you having to stay in undergrad a little longer. Really the question you have to answer is whether or not that's worth the possibility of working as a computer engineer when you graduate.
It's important to make these kinds of decisions based on data too. There are a lot of people online who paint a less-than-rosy picture of what it's like to graduate with a physics degree and then transition into the working world. It's true that it can be a lot harder to find a job with a physics education, but that's because you can't really browse the classified listings under the "physics" section - at least not as easily as you can under the "engineering" section. But that doesn't mean that you won't have a job, or that you're committing to a job in the fast food service industry.