default to including "man" in outputsToInstall

[dtzWill]

Fixes #24717

In particular, man tmux works after installing tmux with nix-env.

This likely breaks things or is bad for some reason, but should work as a starting point.

TODO:

• Ensure NixOS programs.man.enable = false; works (as well as = true).

[Ericson2314]

1. If this indeed is sufficient, this is super important to merge.

2. What about info outputs?

[dezgeg]

I think if you do this, programs.man.enable = false; in a NixOS configuration doesn't stop installing the manpages anymore.

I don't know of an easier solution right now, though. Maybe nix-env itself should call into some nixpkgs function to build user environments (which could then look in config.enableMan or something to see whether manpages should be installed or not).

@edolstra ?

[jokogr]

I do have some installations where I prefer not to have man pages installed to save some storage space, so please do not merge this right away.

[Ericson2314]

@dezgeg How about we control this with a config option?

[dezgeg]

The problem is that it's use-case dependant of whether the man output needs to be installed in a particular buildEnv or not, that would be a global solution to a local problem.

[Ericson2314]

@dezgeg excellent point. Can we give buildEnv an additionalOutputsToInstall parameter, which is a whitelist or predicte on output names?

[fpletz]

Does anybody know what broke this? Did multiple outputs break this? Or Nix 2.0?

I'm not using nix-env much so I'm not sure. If this didn't work in 17.09 or 17.03, this isn't a release blocker imho.

[Ericson2314]

@fpletz I'm not sure it ever worked, but I don't really know.

[matthewbauer]

Nix only started looking at outputsToInstall Nix 2.0, IIRC. Previously it would just install everything. See NixOS/nix#815

[Ericson2314]

Good sleuthing! Can we get a nix-level fix for 18.09??

[nixos-discourse]

This pull request has been mentioned on Nix community. There might be relevant details there:

https://discourse.nixos.org/t/nix-env-not-linking-man-pages-into-environment/1468/2

[matthewbauer]

I'd like to get this merged for 19.03 but I can't figure out what the error is coming from...

[dtzWill]

I'd like to get this merged for 19.03 but I can't figure out what the error is coming from...

weechat error seems to due to copying meta (including meta.outputsToInstall) to the wrapper expression which doesn't have a man output. Not sure how to best solve but seems the problem is 'best' not whether it can be solved at all :). Maybe wrapper should be propagating the man pages too? Or filter outputsToInstall when copying meta? Dunno.

[dtzWill]

!!!! 🎊 👍 😸

[LnL7]

@dezgeg I'm pretty sure programs.man.enable is not affected by this.

If I'm not mistaken the outputs of system packages are determined by environment.extraOutputsToInstall, not individual package metadata. So if that's correct this only affects nix-env -i.

EDIT: Looks like buildEnv does look at both, but /share/man paths are not included by default so it should still be ignored.

[masaeedu]

Awesome, thank you so much!

[lilyball]

We should probably extend this to include info by default.

[matthewbauer]

We should probably extend this to include info by default.

Perhaps, although at some point it makes sense to just drop outputsToInstall altogether and use nix-env's default behavior of installing everything. #44168

[lilyball]

The downside to just installing everything is this means downloading more artifacts that I may not want. For example, if a given package vends a binary, a library, and dev headers, and all I care about is the binary (which is why I'm installing it directly), I certainly don't need to download and install the dev headers.