Re: Upcoming 23.1 release

[Richard Stallman <rms@gnu.org>]

      Secondly, because of Rmail-mbox's funky
    buffer-swapping design, it's not even clear to me that turning on
    auto-save-mode manually in Rmail leads to the correct buffer being
    auto-saved.

The same hook that does it for real saves
runs in this case too.

I just tested it again.  It took just 30 seconds to do M-x
auto-save-mode followed by running (do-auto-save).  However, I kept
editing and I saw that it kept saving the whole file.

I just found and fixed a bug in my change: auto-save-mode did not
toggle the mode off in an Rmail file.  But even if that had not been
fixed, it is less severe than the bug now planned for 23.1.

    I think the correct fix is to change `buffer-swap-text', giving it an
    optional argument that makes it swap the two buffers' values of
    auto-save-file-name and auto_save_modified (and possibly other
    file-related variables also).  And we need an additional hook into
    auto-save-mode that Rmail can use to ensure that M-x auto-save-mode
    turns on auto-save in the correct buffer.

That approach might work too.  But we have a fix that works, and is
much simpler.  It is better to use this, and fix the bug.