I have definitely had to do archeology on 20+ year old code, including disassembly to work out actual production code was when it clearly wasn’t the version we

I have definitely had to do archeology on 20+ year old code, including disassembly to work out actual production code was when it clearly wasn’t the version we had source for, and that’s now 30+ year old code which I expect will still be in productions at least a decade from now. Equally I’ve seen COBOL compiled to new platforms because it has outlived all the systems it ran on. I’m pretty sure there must be areas of Java, or C++’s standard libraries that haven’t changed for a very long time, and will continue to be used for decades. The thing is, it’s often easier to just figure out the code, or rebuild the whole underlying platform, than to track down the original author and hope it wasn’t a Friday afternoon commit.