Missing dependencies for package `forest`

[Karl Berry]

    pgfopts, etoolbox, environ, xparse, and inlinedef.

Ok, added for the next update.

    PS: Just checking, this _is_ the right way to go about this, no? 

Yes.

    also happily submit a pull request or similar when I encounter issues
    like this in the future. 

The only additional bit that would ease the job for me is if you had
time to check for the TL package name corresponding to the LaTeX
packages being required. Usually they are the same, but not always. In
the list above, the only difference is that xparse = l3packages in
TL-land.

It's not a big deal, I do this check anyway, but since you mentioned ...

    (I am a bit obsessed with project specific, minimal tex
    installations (using `nix`), 

I understand. It makes for a lot of extra work, but so be it.

    so I encounter these kind of issues quite frequently).

Well, the ideal fix would be to implement loading packages on demand for
TL, as MiKTeX has, so that these static dependency lists are not so
important. Unfortunately there are many complications to doing so, and I
don't think Norbert or I is likely to ever make it a priority. Should
you have any interest in looking into it, it's been discussed on the
list several times (over the years...), so should be findable in the
archives. I don't have any specific urls at hand, though.

Best,
Karl