Re: Compiled code in Emacs-26 will fail in Emacs-25 if use pcase

[Lars Brinkhoff]

Stefan Monnier wrote:
>> I) Compile under master branch.
>> II) Load the resultant .elc with Emacs-25
>
> As explained by Richard, this is usually considered acceptable.
> We don't really try to provide forward compatibility of byte-code files
> between major versions.
>
> This said, occasionally we try to reduce the pain a little: e.g. in
> Emacs-25 a similar incompatibility was introduced for the compilation of
> catch&condition-case, but the bytecodes were introduced a bit earlier.
> IOW the incompatibility was fundamentally introduced in 24.4 (IIRC), but
> the use of the this new feature was only enabled in Emacs-25.1, so files
> compiled with 25.1 will usually work in 24.5 as well.

It this something that should be done with records too?  E.g.  add the
new record functions to the emacs-25 branch, but not the changes to
cl-defstruct and defclass.