Re: Opcode Versioning Was: emacs master + org Wrong type argument: number-or-marker-p

[Stefan Monnier]

Sam Steingold [2022-08-04 10:59:46] wrote:
>> Emacs instead aims to be able to keep loading old byte-compiled files
>> so we try hard to change the byte-codes only in ways which are
>> backward compatible.
> This is a very noble aim.
> Does it ever happen that Emacs breaks byte-codes as a design decision?

IIRC we did drop some byte-codes, yes.  Most of them are byte-codes
which had never been generated by our byte-compiler, but I think there
were a few other cases where we judged that it had been enough years.

> Or is Emacs _supposed_ to be able to load ELC from 1990?

More or less but not really: even if the byte code itself should
probably work, it's likely to bump into incompatible changes in
the functions we define (or fail to).


        Stefan