Scheme has a "hygienic" macro system that allows you to do arbitrary computation and code alteration at compile time.

The language doesn't see wide adoption in industry, so maybe its most important lessons have yet to be learned, but one problem with meta-programming is that it turns part of your program into a compiler.

This happens to an extent in every language. When you're writing a library, you're solving the problem "I want users to be able to write THIS and have it be the same as if they had written THAT." A compiler. Meta-programming facilities just expand how different THIS and THAT can be.

Understanding compilers is hard. So, that's at least one potential issue with compile-time programming.