Regular void

Well, #embed has already had to undergo revision shortly after standardization in C23: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3912.htm Even the simplest features can be tricky.

Granted, the headaches come from C wanting to support some degree of source-level compatibility with C++, as well as having many implementations, including multiple *major* implementations. These are headaches languages like Rust don't have to deal with. An implementation quirk in Rust can just become the de facto standard, or supported as hack through backward compatibility features. But when you have multiple implementations that diverge, there's no tidy way to fix that mess.