Re: wish-list for OCaml ABI compatibility rules

[Richard Jones <rich@annexia.org>]

On Wed, Jan 09, 2008 at 09:58:12AM +0100, Stefano Zacchiroli wrote:
> Let's see what would be my top wish-list items:
> 1) ability to add .mli components without breaking the ABI
> 2) ability to change non semantic relevant .mli parts (e.g. comments)
>    without breaking the ABI
> 3) (optional, i.e. which can be enabled/disabled) safety to change the
>    implementation without breaking the ABI (ATM md5sums at the .mli
>    level do *not* guarantee that native code linking would work, due to
>    inlining)
> 
> Richard, and d-o-m folks, any other request which come to your mind?
> 
> (1) and (2) above would presumably require to keep not only a single
> md5sum per .cmi, but rather an associative list mapping .mli component
> identifiers to md5sums of their "types". Then, checking for "consistent
> assumption" on such a structure would be far more expensive, but at
> least it would be required only at link time.
> 
> (3) can be enforced at package maintenance level by disabling inlining
> for native code object, and I say it would be a reasonable thing to do
> in distributions. Haven't the C lib stuff already experienced such
> issues?  (or maybe not, I don't know if code inlining across libraries
> is possible in C/C++) if so maybe we can learn from them?

This is all great stuff.  My only wonder is if it's possible & how
simple or otherwise the implementation will be ...  I have little
experience in hacking the compiler.

Rich.

-- 
Richard Jones
Red Hat