> Renames without leaving an alias behind can only be legitimately done
> if the original variable was not yet released in any version;
> otherwise it's a bug that should be reported and fixed ASAP.

I've looked a bit more into it, my 26.3 checkout only has
`with-connection-local-profiles` and the 27.1 one only
`with-connection-local-variables`. On top of that it's not exactly a
rename as the function signature and behavior of the macro changed, so
that violates the assumption you can still use the 26.3 macro in 27.1.
I'll have to look deeper into this problem.

> Did you try "make TAGS" in the top-level directory, followed by
> searching the TAGS files?

Thanks, that's the kind of idea I'm looking for. I'd still need to diff
that output against that of an older Emacs version to find out what has
been removed/added between the releases, but that's fine. Another
problem is that it includes helper functions that aren't part of a
public API.

> Manually or automatically?  If manually, the result will be as
> accurate and comprehensive as NEWS.  If automatically, please tell
> what kind of implementation you have in mind.

Manually, similar to how version information is added to customizables.
The gain is having a machine-readable version you can consult from a
Lisp program. Who knows, maybe you could use it to make an Emacs Lisp
spec independent implementations could target...