Can you give an example? I've never seen a project (outside domains on APL, etc.) that seriously relied on any Unicode capabilities in the code itself (again, I am not talking about localized strings). My native language is not English, I've worked with people all over Europe, China, India, Japan, Israel, etc. - there are a lot of exciting i18n/l10n problems but I have never seen much of what a compiler would need to be concerned with.