cvs commit: src/lib/libc/locale utf8.c
jhb at FreeBSD.org
Fri Oct 26 08:45:33 PDT 2007
On Thursday 25 October 2007 07:04:08 pm Scott Long wrote:
> Robert Watson wrote:
> > On Thu, 25 Oct 2007, Andrey Chernov wrote:
> >> On Thu, Oct 25, 2007 at 12:05:40PM -0700, LI Xin wrote:
> >>> Well, I think the problem is not exposing a new symbol by itself, but
> >>> __mb_sb_limit is being used in _ctype.h, in a form of __inline
> >>> functions. Therefore, the change will break new binaries running on
> >>> older systems.
> >> Yes. Only vice versa compatibility supported.
> > I think the issue here is that the change occurred very quickly after
> > the branch, and when users wanted to 'change gears' back to RELENG_7
> > from HEAD once it was created immediately ran into the problem. It
> > seems like a useful piece of post-branch advice to developers in the
> > future will be, "Please don't do things that make switching branches --
> > back or forward -- for the first few weeks after the branch is
> > created". In general, I don't think we care about forward
> > compatibility, but we are currently getting lots of reports because this
> > is one of those few times where a lot of moving backward happens.
> We do care about forward compatibility within STABLE branches, as Ken
> and I have discussed in side threads. But yes, forward compat between
> major branches is merely desired; i.e. changes will happen, and
> hopefully not for gratuitous reasons.
If we care about forward compatiblity then we can't add new features to
RELENG_X branches. For example, MFCing MSI to 6.x broke forward compat since
a 6.3 module might call the MSI methods thus can't be used on a 6.2 kernel.
AFAIK, we have _never_ promised anything wrt forward compat, only backwards
ABI compat. I can agree with Robert above that during a transition time such
as now it's really handy to be able to switch easily between branches, but I
didn't think it was ever a concern otherwise. If we are going to change the
policy for that then there's a whole bunch of crap I need to go back out of
6.x to restore compat. :-/
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