[antithesis-nl]

Nice as a thought experiment, but you actually do get this in real life as well, when maintaining a public API with a large user base (where even the details of the internal workings need to be frozen over time.)

Gives you lovely stuff like the Win32 API (introduced in 1993 and still very much a thing!). CreateWindow, CreateWindowEx, CreateWindowExEx (OK, I made that up...), structs with a load-bearing length field, etc. etc. And read some Raymond Chen on the abuse that customers inflict on the more 'private' stuff...

[sitkack]

But you do get perfect backward compatibility. If you want to opt-in to the bug fix, you use a newer version of the function.

I recall there being a blog post, maybe by Joe Armstrong in which he advocated for having version numbers in functions. CreateWindow_v1 CreateWindow_v2, or you could use the commit hash.

[regularfry]

I do think version numbers in function names is the least bad version of this. I seem to recall a demonstration of a content-addressable function calling system which could effectively garbage-collect no-longer-called function implementations, but that's only useful if you have the library and all its callers in the same execution context.