Compilers is a pretty small field, yes. Perhaps developer tooling in general might be a bigger pond? You could try some experiments: writing a language server or a debug server, look into some static analysis, something regarding software manifests?

Otherwise, looking at C++, there's work in finance, gaming, embedded, scientific computing, (and others) ... all quite different areas, with different skills and experiences that would be relevant. You might also think about which companies (or even countries) you'd like to work in, and consider where you'd fit.

Do some research on presentations for C++ conferences: where do the presenters work? Look at open source libraries -- who sponsors the projects? Where do the people work for their day jobs?

If nothing else, doing a bit of thinking and research will give you a good story for why you did a particular project, or tried for a particular internship. Almost anything is a better answer than "it fell in my lap and I had no other ideas" (or "some rando on HN suggested it", for that matter).