Re: as for Calc and the math library

[Eli Zaretskii <eliz@gnu.org>]

> From: Suhail Singh <suhailsingh247@gmail.com>
> Cc: Suhail Singh <suhailsingh247@gmail.com>,  gerd.moellmann@gmail.com,
>  nicolas@n16f.net,  arthur.miller@live.com,  emacs-devel@gnu.org
> Date: Wed, 14 Aug 2024 11:08:02 -0400
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> On the topic of what would be acceptable for an FFI, wouldn't something
> >> akin to what's done for modules be sufficient ?  I.e., have the users of
> >> the interface explicitly state that they are compliant.
> >> 
> >> It would scale better than an allow-list.  IIUC, Arthur mentioned this
> >> in another thread.  If this wouldn't be sufficient for an FFI, could you
> >> please elaborate on why that's the case ?
> >
> > What exactly are you suggesting?  IOW, please describe what you have
> > in mind in more detail, because I don't think I understand it.
> 
> Specifically, modify the `define-ffi-library' macro that emacs-ffi
> provides.
> 
> Presently, it takes two arguments: a SYMBOL and a NAME.  I am proposing
> that it be updated to take three arguments: a SYMBOL, a NAME and a
> GPL-COMPATIBLE-P token.  A value of `t' would be necessary for creating
> a reference to the library.

And if the value is not t, then the load will fail?  If so, then this
additional argument makes very little sense: you could instead say
that just by loading the library, the Lisp program which uses
emacs-ffi "declares" the loaded library to be GPL-compatible.  And we
are back where we began.

The way we do it when loading modules requires the _loaded_ library to
declare itself compatible, by exporting a symbol of a certain name.
That is an action by the library we load, not by the Lisp program
which loads it.