Re: User-defined record types, v2

[Lars Brinkhoff <lars@nocrew.org>]

Stefan Monnier wrote:
> BTW, I see further compatibility problems:
>
> if you compile a chunk of code which constructs structs, they get
> macroexpanded/inlined to code that does either
>
>     (record 'FOO <args>)
> or
>     (vector 'cl-struct-FOO <args>)
>
> depending on whether the corresponding cl-defstruct is using the old or
> the new style.
>
> So if this is in a different file from the one that does the
> `cl-defstruct` you can end up with a situation where the
> `cl-define-struct` defines a new-style struct (because it was recently
> recompiled), while some code constructs old style structs of that
> same type (because it hasn't been recompiled recently).

The easy way out would seem to have old-struct-compat set to t by
default.  Then, maybe next major release default to nil.

Or check something in the .elc file when it's loaded.  The Emacs version
number is there (or if it isn't, it's really ancient; looking at you
Emacs 16).  Explicit information about using records could be put in.