Re: gnus-extra-headers

[Eric Abrahamsen <eric@ericabrahamsen.net>]

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?