documentation in TeX Live collections

[Emmanuel Beffara]

Hello Guix,

There has been a lot of movement around TeX Live recently and it is very nice
to see. We now have a usable modular installation and a great number of
available packages and collections. However, I don't understand what is the
proper way to reach documentation in the current system.

I installed `texlive-scheme-medium` in my home profile managed by `guix home`,
everything works including `texdoc` (although it always says « Info: Running
Texdoc not installed in the current TEXMFMAIN. » for some reason), but there
is essentially no documentation installed:

    $ texdoc inputenc
    Info: Running Texdoc not installed in the current TEXMFMAIN.
    You don't appear to have any local documentation installed.

    There may be online documentation available for "inputenc" at
        https://texdoc.org/serve/inputenc/0
    This documentation may be for a different version than you have installed.

    Would you like to search online? (y/N)

Indeed the `doc` folder is nearly empty:

    $ ls $GUIX_TEXMF/doc
    bibtex8/  bibtexu/  chktex/

Apparently, all individual packages have a specific "doc" output but
collections and schemes do not and they don't have them as inputs either. So
we end up with an installation with no documentation (apart from the three
above, which is surprising).

I tried to explicity include documentation in a sub-shell but this changes
nothing:

    $ guix shell texlive-latex:doc -- texdoc inputenc
    Info: Running Texdoc not installed in the current TEXMFMAIN.
    You don't appear to have any local documentation installed.

    There may be online documentation available for "inputenc" at
        https://texdoc.org/serve/inputenc/0
    This documentation may be for a different version than you have installed.

    Would you like to search online? (y/N)

Including the TeX Live scheme in the same shell makes things worse:

    $ guix shell texlive-scheme-medium texlive-latex:doc -- texdoc inputenc
    Info: Running Texdoc not installed in the current TEXMFMAIN.
    texdoc error: No texlive.tlpdb nor shipped tlpdb data found.

Inspecting GUIX_TEXMF in this shell reveals that it now contains two paths,
one of which does contain the right documentation:

    $ guix shell texlive-scheme-medium texlive-latex:doc
    $ env | grep TEX
    
GUIX_TEXMF=/gnu/store/fg1z0jgkj0r4v8i3rmpg0c1vfirbg1ac-profile/share/texmf-dist:/home/manu/.guix-home/profile/share/texmf-dist
    $ ls 
/gnu/store/fg1z0jgkj0r4v8i3rmpg0c1vfirbg1ac-profile/share/texmf-dist/doc
    bibtex8  bibtexu  chktex  latex
    $ export GUIX_TEXMF=${GUIX_TEXMF%:*}
    $ texdoc inputenc
    ... inputenc.pdf is displayed! ...

Apparently the fact that this GUIX_TEXMF variable contains several paths is
problematic for texdoc.

As an attempt to work around this, I tried to add texlive-latex:doc to my home
profile definition and it did make that documentation available to texdoc.
Moreover, for some reason, ALL documentation was downloaded:

    $ guix home reconfigure home.scm
    ...
     texlive-cm-66594-doc  2KiB
     texlive-etex-66594-doc  189KiB
     texlive-hyphen-complete-66594-doc  783KiB
     texlive-kpathsea-66594-doc  1022KiB
     texlive-pdftex-66594  4.2MiB
    ...
    $ ls -d /gnu/store/*-texlive-*-doc/ | wc
       1105    1105   82506

Apparently something has triggered the download of documentation for all
packages `texlive-scheme-medium` depends on but only the one I explicitly
requested is made available in the profile (which is expected). All these
other documentation were downloaded but not used and `guix gc` actually
deletes them all!

So what would be the proper way to install `texlive-scheme-medium` in a home
profile with the documentation of the packages it includes ?

-- 
Emmanuel