What did you find more painful about compilers than other forms of programming?

I think there is a million ways to make a compilers course.

The course I did was organized perfectly with big parts of compiler boiler plate already written, and I only had to implement parser/lexer rules and the translation of language structures into assembly instructions. Also it was a compiler for a language designed just for this course with the intention of it being specifically easy to write a compiler for it and not programming.

Without this I can imagine it being a painful experience