In Javascript there's an expectation that Javascript written 15 years ago for Netscape will also work on Firefox 89. Is that also the case with C, wrt compiler versions? I've always assumed it wasn't.
It's very much the case, so long as you stick to standard C (the full limitations of which very few people are actually aware of).
Runtime backwards compatibility is similarly extensive on platforms that care about it. You can still take a DOS app written in ANSI C89 the year that standard was released, and run it on (32-bit) Windows 10, and it'll work exactly the same. In fact, you can do this with apps all the way back to DOS 1.0.
