"Tell me about writing a compiler" seems mostly to be a question intended to restrict your hires to fresh grads who took a compiler course or if you're trying to poach compiler writers from another company. You're not likely to get a very useful response from someone who hasn't written one recently or at all. You could just as well ask "Tell me about writing a POSIX shell", or "Tell me about writing a browser", or basically any "Tell me about writing a <FOO>". It's not a useful question unless you're specifically hiring them to write a <FOO>.