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: >> 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

--8<---------------cut here---------------start------------->8---
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.
--8<---------------cut here---------------start------------->8---

This was the case until line 1559. At line 1565, the value changed to

--8<---------------cut here---------------end--------------->8---
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)
--8<---------------cut here---------------end--------------->8---

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 

--8<---------------cut here---------------end--------------->8---
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.
--8<---------------cut here---------------end--------------->8---

Why didn't I just grep the directory at the beginning!

Hope this helps.

Best wishes,