Re: Committing new smtpmail.el later tonight

[Stefan Monnier]

> The variable is obsoleted.  Isn't that the normal way to do it, possibly
> annoying people?  It's not particularly hard to migrate the info
> yourself, as I mentioned.

Of course, but we can do better.

EZ> Unlike other software, Emacs didn't until now break customizations in
EZ> such a way, not without some sort of interim period when users were
EZ> told to migrate.
> Since 24.x is a major release, maybe it's OK.  How would you do it?

I'd at least give a hint to the user.  If the user suddenly gets
prompted for his username/password (or just his email fail to get sent
for lack of authentication), her first reaction is likely to be along
the lines of M-x report-emacs-bug or some other curse.

So I think that we have two situations to handle:
- smtpmail-auth-credentials is set and auth-source can't find
  credentials (i.e. the user hasn't migrated yet), so we should warn the
  user about the need to migrate and give some pointer of how to do it.
- smtpmail-auth-credentials is set and auth-source can also find credentials
  (i.e. the user has migrated but still has the old setting).  Here we
  can output a warning about the duplicate info, but it's not
  high-priority and should be discrete.  After all, the user may use
  such a config purposefully because she likes to share a single config
  for different machines where she uses different versions of Emacs.


        Stefan