Yes, “chose” in past-tense (and that whole clause about the tension displayed in public communications of these projects contemplating the change.

Both projects made this change in the last couple years. ffmpeg still requires c99 compatibility for their headers, and may indefinitely.

When Linux was created, there was not much choice. In reality, most active projects moved on and only projects with relatively extreme portability requirements stick with C89, mostly because MSVC does not support anything later properly.

I think that’s fair, but I also believe that the same things that make C89 meet “extreme portability requirements” are why Eskil still uses it.

Should everyone? No, probably not.

Yes, but also because he made it work well for him. He also understands that most of the innovations in programming languages is actually not nearly as useful as people think and often does more harm than good. Rejecting newer C standards is a bit too extreme in my opinion, as C is very slowly evolving already.