Re: gnus-extra-headers

[Colin Baxter <m43cap@yandex.com>]

>>>>> Eric Abrahamsen <eric@ericabrahamsen.net> writes:

    > Colin Baxter <m43cap@yandex.com> writes:
    >>>>>>> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
    >> 
    >> > Colin Baxter <m43cap@yandex.com> writes: >>>>>>> Eric
    >> Abrahamsen <eric@ericabrahamsen.net> writes:
    >> >> 
    >> >> > Colin Baxter <m43cap@yandex.com> writes: >> Hello Eric,
    >> >>>>>>> >> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
    >> >> >> 
    >> >> >> > Colin Baxter <m43cap@yandex.com> writes: >> Hello,
    >> >> >> >> 
    >> >> >> >> If emacs (tested with 27.2 and 28.0.50) is launched with
    >> -Q >> >> (or >> gnus-extra-headers has not been set explicitly by
    >> the >> >> user) then >> the variable gnus-extra-headers has the
    >> value:
    >> >> >> >> 
    >> >> >> >> gnus-extra-headers is a variable defined in
    >> ‘gnus-sum.el’.  >> >> Its >> value is (X-Diary-Time-Zone
    >> X-Diary-Dow X-Diary-Year >> >> >> X-Diary-Month X-Diary-Dom
    >> X-Diary-Hour X-Diary-Minute To Cc >> >> >> Keywords Gcc
    >> Newsgroups X-GM-LABELS) Original value was (To Cc >> >> >>
    >> Keywords Gcc Newsgroups X-GM-LABELS)
    >> >> >> >> 
    >> >> >> >> You can customize this variable.
    >> >> >> >> 
    >> >> >> >> 
    >> >> >> >> This variable was introduced, or its default value was
    >> >> >> changed, >> in version 25.1 of Emacs.
    >> >> >> >> 
    >> >> >> >> Documentation: Extra headers to parse.
    >> >> >> >> 
    >> >> >> >> The X-Diary settings seem to come from nndiary.el, but
    >> >> there >> is >> nothing in the doc-string to indicate this.
    >> >> >> >> 
    >> >> >> >> Is this a bug? Is not the "Original value" of >> >>
    >> gnus-extra-headers >> incorrect?
    >> >> >> 
    >> >> >> > I don't think it's really a bug. If you don't use the >>
    >> nndiary > >> backend, those headers don't get added to >>
    >> `gnus-extra-headers', > >> and it has its "original value" as >>
    >> noted in *Help*. I don't think >> > there's any contract that >>
    >> says additional libraries can't > >> manipulate the value of >>
    >> customization options... is there?
    >> >> >> 
    >> >> >> True, but the user might suppose that using -Q ensures that
    >> no >> >> extra libraries are loaded. I would have thought that
    >> nndiary >> >> constitutes an extra library. If it does not and
    >> the library >> is >> germane to -Q then why omit any mention of
    >> it from >> >> gnus-extra-headers? I have quickly looked at NEWS
    >> for emacs-25.1 >> >> but found nothing relevant.
    >> >> 
    >> >> > If I start with "emacs -Q" and a minimal Gnus setup, the >>
    >> nndiary > isn't loaded and its values aren't added to > >>
    >> `gnus-extra-headers'. The odd thing is that in my usual >>
    >> Emacs/Gnus > set up, those values _are_ added, and I don't use >>
    >> nndiary or > gnus-diary.el. Hang on, let me force an error in >>
    >> there and see > exactly what's loading it.
    >> >> 
    >> >> > Nope, I just restarted Emacs and Gnus, and did some other >
    >> >> Org/Diary/Calendar stuff for good measure, and now nothing has
    >> > >> triggered a load of 'nndiary, and the extra values aren't
    >> added.
    >> >> 
    >> >> > Obviously something, somewhere, eventually triggers that
    >> load >> in > my setup, but it doesn't seem to happen by
    >> default. I'm >> quite > ready to believe that something is
    >> loading 'nndiary when >> it > doesn't need to, but so far I don't
    >> know what it is.
    >> >> 
    >> >> > Maybe you could give it a shot? Delete nndiary.elc, stick a
    >> >> call > to (error) in nndiary.el,
    >> >> 
    >> >> How do I modify the file nndiary.el to achieve this?
    >> 
    >> > Sorry, I didn't ask how you're using Emacs, and assumed you
    >> were > running from the source tree, or had access to it. If you
    >> do have > access to nndiary.el, just edit it regularly in Emacs,
    >> and add a > line like:
    >> 
    >> > (error)
    >> 
    >> > anywhere in the file, maybe at the top. You'll need to remove >
    >> nndiary.elc, otherwise that will get loaded instead of the *el >
    >> file.
    >> 
    >> >> > and restart everything?
    >> >> 
    >> >> What I do know is that if nndiary is not present (.el) and
    >> (.elc) >> then gnus-extra-headers becomes (To Cc Keywords Gcc
    >> Newsgroups >> X-GM-LABELS).
    >> 
    >> > If those files aren't present, I guess I would have expected
    >> you > to see an error, as whatever is loading it fails to find
    >> it.
    >> 
    >> Some progress I think. I inserted (error) at various points in
    >> nndiary.el and got
    >> 
    >> gnus-extra-headers is a variable defined in ‘gnus-sum.el’.
    >> 
    >> Its value is (To Cc Keywords Gcc Newsgroups X-GM-LABELS)
    >> 
    >> You can customize this variable.  This variable was introduced,
    >> or its default value was changed, in version 25.1 of Emacs.
    >> 
    >> 
    >> This was the case until line 1559. At line 1565, the value
    >> changed to
    >> 
    >> gnus-extra-headers is a variable defined in ‘gnus-sum.el’.
    >> 
    >> Its value is (X-Diary-Time-Zone X-Diary-Dow X-Diary-Year
    >> X-Diary-Month X-Diary-Dom X-Diary-Hour X-Diary-Minute To Cc
    >> Keywords Gcc Newsgroups X-GM-LABELS) Original value was (To Cc
    >> Keywords Gcc Newsgroups X-GM-LABELS)
    >> 
    >> 
    >> At line 1563, is (add-to-list 'gnus-extra-headers header), which
    >> would appear to be the source of issue. If I comment out 1563
    >> then gnus-extra-headers reverts back to

    > I'm sorry I wasn't entirely clear here: that line was definitely
    > the source of the behavior, the question is _why_ is the file
    > getting loaded at all, if you aren't using an 'nndiary backend? I
    > wanted you to add a (error) line to nndiary.el so that, at the
    > time it was loaded, we'd get a backtrace: the backtrace will show
    > what functions were being called right before the load, and
    > hopefully that will answer the question of why the file's getting
    > loaded at all.

    > Did you see a backtrace?

No. No error or backtrace seen; just different values of the variable
depending on whether (add-to-list 'gnus-extra-headers header) is
operative or not.

I suppose it isn't an error but an inconsistency with the stated
"Original value" (To Cc Keywords Gcc Newsgroups X-GM-LABELS) of the
gnus-extra-headers variable. The "Original value" gets changed by
nndiary but the user is unaware of this and perhaps thinks, as I did,
that their setup is the culprit. It comes as a surprise to discover
"emacs -Q" leads to the same value of gnus-extra-headers.

After emacs -Q, I looked at the load history 'C-h v load-history' and
nndiary does not appear. The only gnus defuns loaded are
gnus-batch-kill and gnus-set-sorted-intersection. Significant?

I am sorry to be unhelpful.

Best wishes,

Colin.