> Back when he was working on Ada, they didn't store text sources at all — they used an IR called DIANA. Everyone had their own pretty-printing settings for viewing it however they wanted.

What about comments? Were they part of the IR?

(I agree with others that version control, grep etc. are also very important, and kind of a deal breaker).

I would fully expect any structured AST IR to also support comments across all aspects of the program. Ideally they would be better because by the nature of an AST IR, comment scope would be fully expressed structurally.